Vanadium shale is an important vanadium-bearing resource in China, with total vanadium reserves in vanadium shale accounting for more than 87 percent of domestic vanadium reserves.[1] Numerous studies have shown that the vanadium content of vanadium shale is low and that most of the vanadium is encapsulated in the crystal structure of the mica, which is difficult to destroy.[2] Therefore, excess sulfuric acid is usually used in the leaching process to increase the vanadium leaching rate.[3] Due to the complexity and variety of minerals in vanadium shale, often accompanied by pyrite, hematite and other iron-containing minerals, the vanadium leach solution obtained by acid leaching has a low pH and contains a large number of impurity iron ions.To meet the requirements for vanadium extraction by subsequent extraction methods, the pH of the vanadium-containing acid leach solution needs to be adjusted to above 1.8. Electrodialysis(ED) is considered to be an alternative to alkali neutralisation, which has the advantages of no vanadium loss, recoverable sulfuric acid, low waste residue and environmental friendliness.[4] 

Current studies have shown that Fe³⁺ in vanadium acid leach solution can form precipitate before the pH reaches 1.8, which adversely affects the ion exchange membrane.[5] However, the precipitation pH of Fe²⁺ is much higher, exceeding 1.8 or more. Therefore, before the recovery of sulfuric acid using ED, the Fe³⁺ in the vanadium-containing acid leach solution needs to be reduced to Fe²⁺ to ensure that the ED process is carried out smoothly.   

The effects of sodium sulfite, reduced iron powder and sodium hypophosphite on the reduction of Fe³⁺ and on the ED process were investigated in the present work. XRD, SEM-EDS and the pH tests were used to analyse the changes in the precipitates. UV spectrophotometry and the pH tests were used to analyse the changes in Fe²⁺ before and after reduction and during the ED process.Titration and ICP results were used to illustrate the migration of vanadium and impurity ions during the ED process.  

The results demonstrated that the acid leach solution with sodium hypophosphite as the reducing agent did not produce precipitation during the adjustment of pH to 1.8 by ED. Excess sodium hypophosphite could completely reduce Fe³⁺ to Fe²⁺ and prevent Fe²⁺ from being oxidised to Fe³⁺ by oxygen during ED. By monitoring the pH of the solution, precipitation formation and vanadium concentration in the acid leaching solution, it is shown that the acid recovery rate by electrodialysis can reach more than 80% and vanadium retention rate can reach more than 95%.

Determining Bond work index is part of the preparation plant design phase of a mining project, and can significantly affect the design costs associated with comminution.  According to the standard Bond procedure, the work index is determined by simulating dry grinding in a closed cycle in a Bond ball mill until a circulating load of 250 % was established.  This paper represents a continuation of research on the determination of the Bond work index for fine samples. The obtained results confirmed the validity and accuracy of the presented procedure. .

The main part of chrome ore reserves in Albania is represented by chrome ores with a low Cr2O3 content, mainly below 12%. There are currently 16 chromium enrichment plants operating in Albania, which process raw chromium ores with content ranging from 5% to 12% and rarely up to 20% Cr2O3.

The very low content of Cr2O3 in the raw material of these plants has increased the production cost of chrome concentrates, doing necessary the testing efforts to improve the technological-economic indicators.

This paper aims to show the results of the tests and analyses that were done in some of the plants and the results that were achieved through the measures taken to increase the concentrate grade, to reduce losses and to reduce the production cost of chrome concentrates. The method followed has been that of taking samples in the industrial process and analyzing them, thus finding opportunities where to intervene in the process to improve the technical-economic indicators.

Based in the testing and analyses it has been implemented the removal of significant amounts of waste before the grinding process or before the enrichment processes, through pre-concentration processes, which has reduced the cost of processing per ton of raw material. Also, it was concluded that the separation and enrichment of very fine particles in the equipment with suitable parameters for the treatment of fine particles improves the recovery, reducing the losses of Cr2O3 in the tailings. 

Flotation tailings is waste material produced during the flotation process. Proper management and storage of these raw material is crucial to minimizing negative environmental impacts. The main elements contained in flotation tailings are copper (0.13 %) and iron (4.22 %). In addition, the tailings contain zinc, lead, aluminum, magnesium and calcium. The application of hydrometallurgical operations is possible for raw materials with a low metal content or a complex composition. The right choice of reagents is important for a successful process. Sulfuric acid is used as one of the most common reagents for the leaching copper from flotation tailings. [1] On the other hand, ionic liquids are recognized as green reagents due to their characteristics such as viscosity, thermal stability, negligible volatility, non-toxicity and high conductivity. [2] The leaching experiments were carried out in a sulfuric acid solution (H₂SO₄) and an ionic liquid solution 1-butyl-3-methyl-imidazolium hydrogen sulfate ([bmim]HSO₄) in the presence of hydrogen peroxide (H₂O₂). The diluted solution was analysed for copper and iron using a multiparameter photometer and ICP-OAS. Reagents concentrations of 0.01 mol/dm³ and 0.05 mol/dm³ without hydrogen peroxide were also tested. Leaching flotation tailings with sulfuric acid, the copper leaching degree reached 71.05% at lower solution concentrations and 76.59% at higher solution concentrations. When leaching flotation tailings with an ionic liquid solution of the same concentrations, the copper leaching degree was 72.57% and 77.10% for 0.01 mol/dm³ and 0.05 mol/dm³, respectively as shown in a previous study [3]. When leaching with sulfuric acid and in the presence of 0.1 mol/dm³ H₂O₂, the leaching degree of copper was 80.85% at the lower concentration of the solution and 82.24% at the higher concentration of the solution. In the leaching of flotation tailings with an ionic liquid solution of the same concentrations, and in the presence of 0.1 mol/dm³ H₂O₂, the leaching degree of copper was 72.56% (for 0.01 mol/dm³) and 83.14% (for 0.05 mol/dm³). The dissolution of iron was <5% under the tested conditions. These results indicate that hydrogen peroxide has a slight effect for the leaching process of flotation tailings. At the higher acid concentrations tested for both reagents, a greater influence of hydrogen peroxide can also be observed.  

The electrical and electronic industry faces growing demands to address environmental degradation and social challenges arising from its linear production and consumption methods. To tackle these challenges, this paper proposes an innovative and inclusive framework that integrates the traditional Circular Economy Business Model (CEBM) Canvas with social considerations tailored for this industry. The framework aims to assist the electrical and electronic industry in adopting more sustainable and socially responsible practices while maintaining competitiveness and profitability. The development of the framework involves a multifaceted approach. Initially, an extensive review of existing literature identified crucial principles and successful practices in CEBM Canvas, as well as social responsibility within the sector. Additionally, research methods employed included case study analyses of companies in the sector, industry reports, and surveys that gathered insights from various industry stakeholders to shape the framework's design in order to provide a fundamental understanding of circular economy principles and relevant social issues within the electrical and electronic industry. The proposed framework consists of ten essential elements, including circular value proposition, circular revenue streams, key customer segments, circular customer relationships, circular channels, key circular resources, key circular activities, key circular partnerships, circular cost structure, and social considerations. Embracing this framework, the electrical and electronic industry can not only mitigate environmental risks but also contribute positively to foster societal benefits and promote social equity within the industry. It's evident that the forementioned approach embodies a comprehensive strategy for promoting circularity and ethical responsibility in the electrical and electronic industry, contributing to the transition towards a more equitable and regenerative economy.

Vanadium-bearing black shale, commonly known as stone coal, has been identified to have enrichments of vanadium. It is a strategic advantage vanadium resources in China, accounting for 87% of the global shale-hosted vanadium reserves [1]. It typically forms through shallow marine sediments at high temperature and pressure in certain reducing environment [1, 2]. There are vanadium enrichments in the black shale elsewhere in the world include United States, Australia, Argentina and Kazakhstan [4]. Compared to vanadium titanium magnetite resources, vanadium-bearing shale has emerged as a significant source of strategic vanadium products due to its low contents of iron, copper, chromium and manganese.

The world has entered a new era where the fourth industrial revolution and sixth scientific and technological revolution overlap for major countries and economies to strategically allocate mineral resources for emerging industries. Vanadium, a kind of rare metal, remains an important strategic reserve resource for developed nations. China currently holds the title of the world's largest vanadium producer and supplier with 255,500 tons produced in 2021 as reported by the Vanitec. Currently, V₂O₅ and other basic vanadium industrial products account for approximately 70% of the market share in China while high-end vanadium products make up over 20% [3]. With the implementation of the national strategic industrial layout, the acceleration of investment in key emerging sectors such as marine engineering, aerospace, new energy, and new materials will significantly propel the sustained growth in demand for high-end vanadium products. Efficient and environmentally-friendly extraction methods along with advanced manufacturing techniques have become crucial focal points for ensuring the healthy and sustainable development of vanadium resources in China, thereby enhancing international competitiveness.

Over the past two decades, the vanadium-bearing shale industry has undergone rapid development, transitioning from conventional and inefficient production to the integration of the entire industrial chain encompassing beneficiation, extraction, and material manufacturing. Vanadium products derived from black shale account for approximately 40% of China's total high-end vanadium product output. Significant advancements have been achieved in the efficient extraction of vanadium from shale sources, as well as in the effective separation of individual metals and the manufacturing of high-end adaptive components.

Mr. President, Ladies and Gentlemen

I consider it a great honor that you invited me to your Symposium, and I regret that I cannot attend it. However, it remains for me a strong pleasure to write a few words about Professor Georgios Anastasakis, as he was one of my first students, whose development I followed closely during his career so far in the School of Mining and Metallurgy of the National Technical University of Athens, where we have now worked for a long period as colleagues. During this time, we became close friends, and now, 45 years later, after a rich scientific, teaching and research career, he is being honored in your distinguished Symposium that bears his name.

Mr. Anastasakis has worked tirelessly in teaching and research on a wide variety of topics, with a focus on mineral beneficiation and sustainable development. He dealt with issues of basic and applied research, producing an extremely large number of publications with high impact in the respective scientific field, thus opening new scientific perspectives. He also worked on numerous research projects together with other researchers to solve actual industrial problems.

Moreover, his scientific activity was not exhausted in publications, but it was coupled with his active participation as a member of international congress organizing and scientific committees, member of scientific boards, reviewer of scientific journals, and member of scientific and editorial boards, as well as other related activities on international level.

We must not yet overlook his exemplary engagement in the context of his teaching duties and in the multi-year direction of the Mineral Processing Laboratory, which produced excellently educated engineers and professionals in this field.

Thanks to the aforementioned overall achievements, he gained international recognition, for which he undoubtedly deserves an award.

Litigation finance, a mechanism where third-party funders provide capital to litigants in exchange for a portion of the recovery, has been gaining traction globally. This paper explores the development, current application, and future prospects of litigation finance in China, a country with a burgeoning economy and evolving legal landscape.  

The concept of litigation finance in China is relatively nascent compared to Western jurisdictions. Initially, the practice faced significant skepticism due to concerns over potential ethical issues and regulatory challenges. However, as China continues to modernize its legal system and economy, the acceptance of litigation finance has grown. The early 2010s marked the beginning of more structured litigation finance activities, with increasing involvement from both domestic and international funding entities.

China's rapid economic growth has led to a complex commercial environment where disputes are inevitable. The current economic landscape, characterized by high-stakes commercial litigation and arbitration, creates a fertile ground for litigation finance. The tightening of credit conditions and the need for businesses to manage cash flow have amplified the demand for alternative financing options, including litigation funding. This financial tool allows companies to pursue meritorious claims without bearing the upfront costs, thereby leveling the playing field, especially for smaller enterprises.

From a legal standpoint, the potential for litigation finance in China is substantial. The Chinese legal system has been progressively aligning with international standards, which includes a more robust framework for the protection of commercial rights. Despite the progress, there remain significant regulatory ambiguities and cultural hurdles. The lack of a comprehensive legal framework specifically addressing litigation finance poses challenges, yet also presents opportunities for legal innovation and reform.

The application of litigation finance in China is diverse, spanning from commercial litigation to arbitration and insolvency proceedings. Major cities like Beijing, Shanghai, and Shenzhen have seen a rise in litigation finance activities, supported by local legal firms and international funders establishing a presence. Case studies indicate that litigation finance has been particularly beneficial in complex commercial disputes where the cost of litigation is prohibitively high. 

Looking ahead, the prospects for litigation finance in China are promising. The ongoing reforms in the legal sector, combined with China's strategic focus on fostering a business-friendly environment, suggest a favorable trajectory for litigation finance. However, the industry must navigate regulatory uncertainties and cultural resistance. Building a transparent and ethical framework will be crucial for gaining wider acceptance among litigants, lawyers, and the judiciary.  

In conclusion, litigation finance is poised to play a significant role in China's legal and economic landscape. Its ability to democratize access to justice and provide financial relief in litigation-heavy environments positions it as a critical tool for the future. With continued legal reforms and increased awareness, litigation finance can thrive, offering new avenues for dispute resolution and contributing to the overall efficiency of the Chinese legal system.
This paper aims to provide a comprehensive overview of the current state and future potential of litigation finance in China, highlighting the economic drivers, legal perspectives, and practical applications that shape this evolving industry.  

This paper analyses the Power Purchase Agreement (PPA) as a tool for securing electricity within the context of free energy trade between private entities and state support for promoting energy production from renewable sources to meet green transition and sustainable development goals. It further delves into the various implications of these agreements on the broad energy market. The PPA is a crucial mechanism for securing financing for the construction of power generation plants. The analysis includes different types of PPAs, their advantages, elements, termination, and the risks for both the buyer and the seller. The paper also provides a precise summary of decisions made by the European Court of Justice regarding Power Purchase Agreements, particularly focusing on how these agreements are categorized and evaluated as state aid. The aim is to provide a comprehensive overview of the legal aspects of renewable PPAs, while also taking into account considerations of Albanian legislation.

India is one of the 3^rd  largest steel producers in the world, Iron Ore Beneficiation & Pelletization plants along with DRI plants which will remain the backbone of Iron & Steel Industry in the world. Existing DRI plants were commissioned by employing processing techniques suitable for good quality Iron ore lumps / fines.

Present scenario some of them are utilizing   various types of process equipment and technologies i.e., rotary kiln, T.G. KILN, S.G. kiln, VSK, and Roller KILN Gate process methods. Through our innovative technology we don’t want to embrace machineries. The entire process can be carried out with the help of chemicals and, hence, sponge iron and steel industries can avoid huge investments in machinery. The chemical and physical properties of the green pellets are the same as that of the conventional method as they undergo the same conventional treatment. By graduating to this simple process, sponge iron and steel manufacturers can reduce capex by an impressive 35-40%. In the conventional method, green pellets are fired in the rotary kiln for which, over and above coal needed for injection, coal lumps, dolomite and limestone are fed. The author said, “Our innovation requires only injecting coal firing. Also, there is no need for separation after receiving the material from the kiln. We encourage the use of powder waste from mines so that production and fuel costs can be curtailed. Specific coal consumption comes down by 10% and as there is no accretion and no fused lump formation, the refractory repairing cost can be reduced by 50%. Also, maintenance, power and production costs can be reduced.”

Raghuvamsi Technologies is using only fines to produce 10 to 20 mm pellets in the rotary kiln. the green pellets keep calcined continuously at a desired rate. Once the mix is fed into the drum, heating by an external burner located near the ignition hood starts and suction of each pellet moving from feed to the discharging end is ensured. It is important that the amount of water used should not be either too little or too much. Insufficient moisture should not generate capillary that is required for bonding. Once nucleation starts, pellets start growing at an exponential rate. The ratio of water to chemical (whether powder or liquid) used is 10:1 and maintaining this ratio is crucial. For 1,000 liters of water, the amount of chemical to be used should not exceed 10.0 liters. These green pellets are then dried in normal temperature or kiln waste heat at 100-150 degree Celsius to produce pellets with acceptable strength.

Catalytic Wet Peroxide Oxidation (CWPO) allows the removal of recalcitrant organic compounds under mild conditions when using hydrogen peroxide and a solid catalyst with redox properties to generate •OH from the H₂O₂ decomposition [1]. Clays modified with the mixed Al/Fe system have shown excellent performance in CWPO systems for the degradation of organic compounds (including contaminants of emerging concern) present in wastewater [2]. In this study, a series of pillared interlayered clays including aluminum, iron and cooper has been prepared. This work presents a comparative study of those solids on the phenol oxidation in diluted aqueous medium with hydrogen peroxide at 25°C and atmospheric pressure. 

Al, mixed Al-Fe and Al-Cu pillared clays have been prepared using the conventional method in a dilute medium with two parameters added to this synthesis. The first is the cooling of clay suspension and the second one is the exchange between clay and metal solutions before pillaring.

The dispersion of the cold clay suspension, before the pillaring, increases the basal spacing and the specific surface area. Mixed Al-Fe and Al-Cu pillared clays have comparable performances in very mild reaction conditions, although they showed some differences in the H₂O₂ decomposition kinetics. A total conversion of H₂O₂ is obtained without completely phenol conversion over mixed Al-Fe pillared clays suggesting the presence of the active species in these catalysts.

Iron exchanged and post-pillared clay with mixed (Al-Fe) solution containing 10% of iron expressed as molar percentage (Fe/MR-AlFe(10)) is the most efficient for this reaction combining good catalytic activity with high stability against iron leaching (0.02%). Its shows total phenol degradation, the highest H₂O₂ decomposition (85.7%) and more than 80% of TOC removal after 15h of reaction.

In order to verify the effect of ultrasonic waves to control the invasion of the golden mussel, Limnoperna fortunei, three experiments were made with different numbersof individuals and for each experiment the sonicator device was using at 40kHz frequency. In addition, the tests varied in time and days of exposure of the mussels to ultrasonic waves. As a result, several numbers for mortality and decoupling of the analyzedsamples were noted, with significant differences regarding the exposure time per experiment and days in which  the sampleswere submitted. Thus, the use of ultrasound to descale and kill the golden musselswas efficient and may be an alternative to control the invasion of L. fortunei.

In 1991, Limnoperna fortunei (Dunker, 1857), also known as the golden mussel, was found at the mouth of the Rio de la Plata and, since then, it has expanded rapidly, mainly along the Paraguay and Paraná rivers. Vessel traffic between Argentina and Brazil has become one of the main causes of golden mussel dispersal (DINIZ, 2010). This invasive species originates from Southeast Asia and has spread to South America through the ballast water of ships coming from China (RIBOLLI et al., 2021).

This bivalve mollusk has a great capacity for proliferation, which is due to its morphological characteristics, such as its shells and its sessile characteristic, in addition to its evolution shaped by the environment (PAULA et al. 2021). Thus, it is expected that invasive alien species without control of their proliferation become an environmental, social and economic problem in environments that are not originally their natural habitat (IBAMA, 2020).

The invasion of golden mussels, for example, generates numerous environmental consequences, compromising biomes, lakes, vegetation cover, water quality, among others. The release of organic material (pseudofeces) by these organisms affects the phytoplanktonic 

and zooplanktonic community, causing loss of habitat for some species of fish and other organisms (IBAMA, 2020).

With regard to technologies developed by man, hydroelectric plants are one of the main structures that suffer from the invasion of the golden mussel (PAULA et al., 2021). In addition, net cages are also significantly affected by golden mussel fouling (COSTA et al. 2012). When detecting the presence of larvae in ballast water from contaminated vessels, control strategies must be developed to avoid further contamination and intense propagation of the species, mitigating its impacts (SANTOS; WÜRDIG; MANSUR; 2005).

The first National Strategy on Invasive Exotic Species defined criteria for analysis and classification of species and, according to CONABIO Resolution nº 5, of October 21, 2009, the golden mussel can be categorized as an exotic and invasive species, since its Dispersion translates into social, economic and environmental risks. Therefore, it is important to develop strategies to mitigate and contain its dispersion and/or impact (MINISTÉRIO DO MEIO AMBIENTE, 2009).

Control methods with ultrasonic waves for golden mussels in hydroelectric power plants are still the subject and there is not a significant amount of related studies, however, their application has been shown to be significant (PEREIRA, 2012). The elaboration of analysis around this exotic species, exploring the ultrasonic techniques, shows promise in fulfilling the objectives of containment and control of the proliferation of L. fortunei, as well as, consequently, mitigating its implications in the environment, society and economy.

OBJECTIVES

General objectives

To verify the effect of ultrasonic waves on the control of golden mussels.

Specific objectives

 Carry out and publicize the ultrasonic technique for controlling the golden mussel;

 Understand, in the literature, how the invasions of Limnoperna fortunei affect industries and environments, and the possibilities of control;

 Evaluate the influence of ultrasonic waves on the control of golden mussels under different time intervals.

According to Almeida 

Despite bringing several consequences to industries with systems already infested by L. fortunei, given the research carried out in recent years, this problem can be solved, since many methods have become efficient in combating mussels, such as the use of sonicator devices.

This study was able to prove the effectiveness of ultrasound for the decoupling and death of golden mussels, which enables their control based on this physical treatment. Therefore, this study becomes extremely relevant, above all, given the need to reduce the economic and environmental impacts caused by the golden mussel which, as mentioned in this research, can range from the obstruction of pumps in hydroelectric plants to impacts on the quality of water and biomes, among other problems.

Finally, it is possible to carry out future research that explores other parameters for the experiments, such as the use of other ultrasound bath devices, as well as different exposure times. Other delimitations that may also contribute to this line of research can address how ultrasonic waves can be used in loco, in order to establish a control method in the place where incrustations cause damage to companies and other environments that need control, thus being able to bring advances to the solutions for controlling the golden mussel through ultrasonic waves.

According to the International Energy Agency (IEA) [1], the steel sector, among heavy industries, ranks first in CO2 emissions and second in energy consumption. Iron and steel are directly responsible for 2.6 gigatons of carbon dioxide (GT CO2) emissions annually, accounting for 7% of the total global energy system. The Sixth Assessment Report (AR6) of the IPCC (United Nations Intergovernmental Panel on Climate Change) of 2023 [2], containing a comprehensive study on the climate situation of the planet, has shown in a worrying way that the goals established on December 12, 2015, in the Paris Agreement, which aims to limit global warming to less than 2, preferably 1.5 degrees Celsius, are increasingly out of reach. Brazil is the largest steel producer in Latin America and the ninth largest in the world, according to the Instituto Aço Brasil [3]. Brazil's energy park has large renewable energy sources (hydroelectric, wind, solar and biomass plants), reaching 93.1% of electricity generation in 2023, E3G [4].In this way, with the decarbonization process of steel production, combined with the use of Biochar, green hydrogen, will make Brazil a major player in the production of green steel.This study aims to evaluate the ways and processes in which Brazil has been planning its decarbonization, thus contributing to achieving the goals of the Paris agreement.

The kinematic viscosity of samples of Fe_73.5Cu₁M₃Si_13.5B₉ iron-based magnetically soft alloy with different inhibitors M = Nb, Mo, V, Cr in heating and cooling regimes has been studied. Polytherms of physical properties were obtained and activation energies of viscous flow were calculated. It is shown that the greatest nonlinearity of the temperature dependence of viscosity in logarithmic and inverse scales is observed in the heating process [1].

Maturation of the melt at a fixed temperature is accompanied by viscosity fluctuations, the amplitude of which significantly exceeds the random error of measurement. The greatest temporal instability of the melt is observed at the temperature of structural transformations. The reason for the oscillations may be the transition from the non-equilibrium structure of the melt, inherited from the initial crystalline phases, to the equilibrium state associated with the periodic appearance and destruction of cluster structures and intensive structural reorganization of the melt [2].

The study of multicomponent melts shows that the structures of liquid and solid states are interrelated. The most homogeneous structure has a melt heated above the critical temperature, which corresponds to the temperature of structural transformation. Amorphous precursor obtained from homogeneous melt has higher plasticity and hardness, higher enthalpy of crystallization [3]. After nanocrystallization of the amorphous precursor obtained from a superheated melt, a material with higher permeability was obtained, with an increased fraction of small nanocrystals of 2 nm.

Quartzite is a metamorphic, silicate ornamental rock with a high quartz (SiO2) content. Its waste generally comes from the cutting process made with diamond blades. The use of charcoal as a replacement for coke allows for a 100% reduction in CO2 emissions in the steel production process in steel mills. The objective of this work was to analyze the behavior of quartzite as a reducing agent for new forms of charcoal production from crops (bamboo, rice residues, corn, soybeans), thus seeking high productivity, while avoiding the emission of greenhouse gases into the atmosphere, complying with the Paris Treaty. Environmental transformations to combat climate change require investments in technology, such as partnerships between academia, industry and government, cooperating. 

The electrodeposition of Zn-Ni is classified by Brenner [1], as anomalous codeposition, because zinc, the less noble metal, is preferentially deposited to nickel the more noble metal. The inhibition of H⁺ reduction occurs with increasing Zn ions concentration in solution [2]. Anomalous codeposition is favored in chloride medium and inhibited in boric acid [3].

The reaction kinetic of Zn-Ni codéposition was investigated in acid solutions. The effects of solution composition and pH were analyzed. The inhibition of H+ reduction occurs with increasing Zn ions concentration in solution. Increasing pH values causes Zn deposition during Ni-Zn codeposition. Anomalous codeposition is favored in chloride medium and inhibited in boric acid. When alloy deposition becomes the main process, the interfacial pH is governed by the individual metal deposition that controls the kinetic behavior. The interfacial pH increases during separate Ni deposition, meaning that it occurs with simultaneous consumption of H+. Anomalous codeposition process is not due to a saturation of species at the electrode surface.

The interest of the present work is focused in the study of the simultaneous electrodeposition of Ni and Zn. In the first part we studied the effect of the composition of the solution on the composition of the electrodeposited alloys. The second part is focused on the effect of boric acid on the codeposition of nickel and zinc.

Titanium is not rare, being the ninth most abundant chemical element in the earth's crust, behind metals such as aluminum, iron and magnesium [1]. Nickel and titanium alloys (Ni-Ti) are part of a group of metallic alloys whose main feature is the shape memory effect (EMF), known as shape memory alloys (SLM), or smart alloys. This alloy was characterized by having excellent electrical and mechanical properties, high resistance to corrosion and fatigue, with values equal to or greater than those of stainless steel ABNT 316L and titanium alloy ASTM F 136 [2]. The intermetallic formed are very difficult. to be removed by subsequent heat treatments, being thermodynamically more stable than Ni-Ti. The emergence of these intermediate phases is related to the manufacturing process of the alloy and the subsequent thermal or thermomechanical treatments [3]. Biocompatibility is understood as the affinity that must exist between a certain material and the biological environment in which it needs to remain. The material implanted in the body may or may not produce reactions [4]. Compared to conventional metallurgy, the Powder Metallurgy technique has become competitive both for technological and economic reasons: in the production of large quantities of parts, in complex shapes or with base material with a high melting point. It is a technique in constant evolution, with the development of new alloys [5]. After obtaining the metallic powders, the compaction step takes place, called Cold Pressing, which occurs at room temperature. In this process, the powder is placed in die cavities mounted on compression presses, being compressed to determined pressures, according to the type of powder used and the final characteristics desired in the sintered products [6].

The AISI 420A (SUS420J2) stainless steel is commonly subjected to quenching and tempering heat treatments when intended for various high-value applications. However, the proper selection of the austenitizing temperature, a step preceding the fast cooling in quenching, remains challenging. Numerous reports in the literature, as well as in industry, make it clear that slight alterations in this parameter strongly modify the mechanical properties of tempered products, even when using the same cooling rate. In this context, the present study aimed to evaluate the effect of the austenitizing temperature on the carbide dissolution and the martensitic transformation in this steel. For this purpose, resources such as computer thermodynamic simulation and dilatometry were used concomitantly with structural characterization techniques. It was concluded that with the increase in temperature in association with the continuous carbide dissolution, there was a significant austenite enrichment in C and Cr, which strongly contributed to the decrease in martensitic transformation critical temperatures. In this scenario, the increase in austenitizing temperature led to a significant hardening of the martensitic microstructure, reaching up to a 59% increase in Vickers hardness with a 275°C increase in this heat treatment parameter.

Currently, all over the world, intensive development of new materials is being carried out for the development of industry. Of particular note are materials containing metal borides. In our case, Hf and Sc borides, which have a unique set of physicochemical properties: high melting point, mechanical strength, thermal stability and exceptional wear resistance, corrosion and oxidation. These unique properties make them ideal for high temperature applications in key areas, such as the aerospace industry, nuclear power, the automotive industry and the latest electronic devices, and also as a component of light heat-resistant alloys.

In most cases, the production of composite and nanostructured materials is carried out as a result of various oxide reduction reactions and therefore the study of processes of this type is one of the main tasks.

The purpose of this work was to conduct a thermodynamic analysis of the formation of Hf and Sc borides, and based on this analysis, to conduct experiments on the manufacture of nanostructured composite materials in the future.

A thermodynamic analysis of the Sc-Hf-B-O-C system at high temperatures in vacuum was performed for the following reactions: 1. Sc₂O₃+HfO₂+3B₂O₃+14C=2ScB₂+HfB₂+14CO;

2. Sc₂O₃+HfO₂+6H₃BO₃+23C=2ScB₂+HfB₂+9H2+23CO.

Information about the FTA of the system in question has not been found in the available literature. Therefore, it is of great interest to carry out the FTA of these reactions. The calculations were carried out using the ASTRA-4 program [3] in the temperature range of 1000-3000 K with a step of 200⁰ in vacuum.

When studying the equilibrium of a reaction, knowledge of the properties and accurate, reliable thermodynamic data of the components and compounds involved in the system is necessary. However, data on some thermodynamic characteristics of these borides (H⁰₂₉₈-H⁰₀, ∆H_mel, C_p, C_p(liq))  are not observed in reference books.In this regard, we calculated the values of these thermody-namic characteristics of the indicated borides, the calculation methods for which were developed in [1] and entered into the ASTRA-4 program database.

The main results of FTA are presented in the form of diagrams (dependence of the content of components on temperature in the range of 1000-3000 K).

Thus, it can be concluded that the method of complete thermodynamic analysis used by us makes it possible to judge not only the equilibrium conditions of the processes occurring in the system, but also the mechanism of interaction of components in complex systems and, consequently, adjust the composition of the final product, and it is also possible to minimize the number of experiments.

Three-dimensional (3D) composites have emerged as a solution to the limitations of two-dimensional (2D) laminates, such as low impact toughness, poor damage tolerance, and high susceptibility to delamination. The fabrication of 3D fibers involves techniques such as weaving, braiding, knitting, Z-pinning, and stitching. The stitching method consists of inserting reinforcing threads, typically made of carbon, glass, or aramid, in the thickness direction. Stitched 3D composites already have significant applications, primarily in the aerospace and aeronautical industries, but they are also being noted in the naval and automotive industries [1]. Under specific configurations, stitching has demonstrated the ability to improve impact resistance at different velocities. An increase in the Charpy impact resistance of 3D composites compared to laminates has been identified [3]. Additionally, an increase in the ballistic impact resistance of woven 3D composites has been observed. This improvement was associated with the stitching's ability to divert the projectile's path. Furthermore, the role of the reinforcing bundles in absorbing deformation energy and preventing interlaminar shear failures was highlighted, ensuring that the fibers reach their maximum tensile strength potential [4]. 

This study analyzed the configurations of 3D and 2D composites. Samples of aramid fabric fully stitched with aramid bundles were fabricated. Subsequently, all samples were impregnated with epoxy resin using the resin infusion technique. The preliminary results of the test firing of a .45 caliber projectile were promising. Both configurations demonstrated the ability to retain the projectile that struck the plates with 450 Joules. However, the 3D composites exhibited an indentation caused by the projectiles that was smaller than that of the 2D composites. Upon observing the composite, no delaminations were identified in the 3D composite plates, suggesting that the stitching capability contributes to containing the propagation of delamination.

Commonly metals, ceramics, and polymers have been widely used in the manufacturing of armor components. However, due to the growing demand for components that provide comparable ballistic impact resistance with a significant reduction in weight, laminated composite structures have emerged as key substitutes. These composites have found significant application in the construction of components for bulletproof vests, ballistic panels, and military vehicle protection [1]. The mechanical performance of structural composites is strongly dependent on the volumetric fraction of their constituents and the presence of defects, such as voids, resulting from the manufacturing process. Optimal properties are generally achieved when the laminated composite structure has a high reinforcement volume fraction and a low void content. However, when addressing composites intended for ballistic applications, voids might not be detrimental. Indeed, in high-speed impact scenarios, a wave is generated and travels through the material. This wave induces stresses in the material, potentially resulting in strain, as well as partial or complete perforation of the target. Voids generated during the molding process do not necessarily have a detrimental effect [2]. On the contrary, they have the ability to induce a change in the wave medium, altering the stress imposed on the material. Therefore, manufacturing techniques that are simpler and economically viable, tending to generate composites with a higher void volume, may prove efficient for the production of ballistic components. In the present work, composite plates made of aramid fiber and impregnated with epoxy resin were produced using the vacuum-assisted resin transfer molding and compression molding techniques. Subsequently, a residual velocity test was conducted by firing a .45 caliber projectile using a pressure rifle. Preliminary results revealed that although there was no statistically significant difference in the absorbed energy value between the samples, and no sample was completely perforated, there was a clear distinction in the fracture mode. The sample produced by compression molding exhibited a much greater indentation compared to that manufactured by infusion, which, in turn, dissipated the shot's energy through total layer delamination. This suggests that, in terms of application in bulletproof vests, the infusion-manufactured sample showed superior performance, as it would result in less trauma for the user [3].

Fiber-reinforced polymer composites are widely used in various industries, such as defense, aeronautics, aerospace, civil construction, and sporting goods. These structures often face high mechanical stress situations, such as dynamic and static loads in structural applications. Generally, the matrix-fiber interface plays a crucial role in the mechanical strength of composites. Issues such as inadequate adhesion between the fiber and the polymer matrix can reduce load transfer, resulting in lower mechanical performance of these materials. In recent years, numerous studies have focused on optimizing this interface to enhance the properties of composites, including fiber surface treatments, the use of coupling agents, and improvements in matrix chemistry [1]. This work aims to review some of these parameters, which can be controlled by engineers during the design phase to improve the performance of fiber-reinforced polymer composites according to their applications [2]. The review highlights recent progress made to overcome the mechanical limitations presented by this class of materials, focusing on improving strength through the optimization of the matrix-fiber interface, presenting an updated overview of the state of the art on the topic [3].

Commonly metals, ceramics, and polymers have been widely used in the manufacturing of armor components. However, due to the growing demand for components that provide comparable ballistic impact resistance with a significant reduction in weight, laminated composite structures have emerged as key substitutes. These composites have found significant application in the construction of components for bulletproof vests, ballistic panels, and military vehicle protection [1]. The mechanical performance of structural composites is strongly dependent on the volumetric fraction of their constituents and the presence of defects, such as voids, resulting from the manufacturing process. Optimal properties are generally achieved when the laminated composite structure has a high reinforcement volume fraction and a low void content. However, when addressing composites intended for ballistic applications, voids might not be detrimental. Indeed, in high-speed impact scenarios, a wave is generated and travels through the material. This wave induces stresses in the material, potentially resulting in
strain, as well as partial or complete perforation of the target. Voids generated during the molding process do not necessarily have a detrimental effect [2]. On the contrary, they have the ability to induce a change in the wave medium, altering the stress imposed on the material. Therefore, manufacturing techniques that are simpler and economically viable, tending to generate composites with a higher void volume, may prove efficient for the production of ballistic components. In the present work, composite plates made of aramid fiber and impregnated with epoxy resin were produced using the vacuum-assisted resin transfer molding and compression molding techniques. Subsequently, a residual velocity test was conducted by firing a .45 caliber projectile using a pressure rifle. Preliminary results revealed that although there was no statistically significant difference in the absorbed energy value between the samples, and no sample was completely perforated, there was a clear distinction in the fracture mode. The sample produced by compression molding exhibited a much greater indentation compared to that manufactured by infusion, which, in turn, dissipated the shot's energy through total layer delamination. This suggests that, in terms of application in bulletproof vests, the infusion-manufactured sample showed superior performance, as it would result in less trauma for the user [3].

The ballistic performance of epoxy matrix composites reinforced with 10, 20 and 30% by volume of babassu fibers was investigated for the first time. The tests carried out included Izod impact tests and ballistic tests with 0.22 caliber ammunition. The Izod impact tests showed significant improvements with increasing babassu fiber content, indicating greater strength of the composites. Scanning electron microscopy analysis revealed the fracture modes of the composites, highlighting brittle fractures in the epoxy matrix, as well as other mechanisms such as fiber breakage and delamination in the fiber-reinforced composites. In the ballistic tests, a significant increase in the energy absorbed by the composites was observed. All composites outperformed pure epoxy by more than 3.5 times in ballistic energy absorption, highlighting the potential of babassu fibers for engineering and defense applications. These results indicate that babassu fibers can be an effective and sustainable alternative for improving the performance of composite materials.

To complement the previous results, an analysis of the chemical and morphological properties of babassu fibers (Attalea speciosa Mart. ex Spreng.) was carried out in order to assess their potential as reinforcement in the production of epoxy matrix composites. The diameter distribution was analyzed in a sample of one hundred fibers, allowing its variation to be verified. Determination of the chemical properties involved experimental analysis of the constituent index and X-ray diffraction. The diffractogram was used to calculate the crystallinity index and microfibrillar angle, crucial parameters that indicate the consistency of the mechanical properties of babassu fibers and the viability of their use in composites. The results showed that babassu fiber has a chemical composition of 28.53% lignin, 32.34% hemicellulose and 37.97% cellulose. It also had a high crystallinity index of 81.06% and a microfibril angle of 7.67°. These characteristics, together with previous results, indicate that babassu fibers have favorable chemical and morphological properties for use as reinforcements in composites, highlighting their potential as an important material for applications in technological areas.

The comparative study aimed to explore the thermal neutron transmission factor utilizing the Watt spectrum for uranium-235 fission[1-3]. In the course of the analysis, a noteworthy observation emerged, revealing that borated polyethylene exhibited a notably lower efficiency compared to regular polyethylene counterparts[4-5]. This disparity implies that while boron offers advantageous moderating properties, its incorporation may introduce other characteristics that detract from its efficacy in facilitating thermal neutron transmission[6]. This outcome underscores the critical necessity of evaluating not solely the moderating capabilities of materials but also other intrinsic traits that might impact the behavior of thermal neutrons. Specifically, boron-polyethylene (referred to as E-boron) displayed a marginally elevated transmission factor at 79.48% in contrast to common polyethylene (PE) at 78.68%. This finding suggests that the presumed homogeneity of boron-polyethylene, containing an approximate 1% boron-10 concentration, failed to exert any discernible effect on neutron flux attenuation[7]. Such a phenomenon could potentially stem from the material's inherent incapacity to maintain its uniformity in the solid state. Despite the considerable neutron-absorbing capacity conferred by carbon within the polymer, the post-reaction homogeneity of the material surprisingly facilitated radiation passage. These observations necessitate a deeper exploration into the intricate interplay between material composition, structural integrity, and neutron transmission efficiency. Furthermore, they underscore the need for a comprehensive understanding of the multifaceted factors influencing the behavior of thermal neutrons within varying material matrices. This study not only sheds light on the complexities surrounding boron-enhanced polyethylene but also underscores the broader importance of considering diverse material characteristics in the design and optimization of neutron-modulating materials for nuclear applications.

Advancements in materials research for the nuclear industry coincide with the rising energy demand [1],[2]. Consequently, discussions around new materials aim to enhance the efficiency of their applications within the nuclear domain. An essential aspect of reactor operation involves understanding the behavior of fuel rods during UO2 pellet fission reactions [3],[4], and consequently, the heat transfer mechanisms involved in this process. To delve into these pivotal characteristics, a study was conducted on the criticality of a fuel rod clad with Zircaloy doped with graphene nanotubes [6],[7] via simulation using the MCNP code. Simulations of the fuel element were conducted with enrichment distributions of 3.2%, 2.5%, and 1.9% of UO2, based on a hypothetical PWR type reactor model [5]. The hypothetical scenario considered a fuel for a PWR reactor comprising 25 fuel rods with UO2 pellets exhibiting three enrichment zones of 3.2%, 2.5%, and 1.9%, as illustrated in Figure 1, with a height of 3.6 m, simulated using the MCNP5 software. To fulfill the study's objective, the first simulation involved pure Zircaloy-4, serving as the reference standard for criticality of the fuel element. Subsequently, another simulation entailed this alloy doped with 10% of graphene nanotubes. The result obtained for the effective multiplication factor (keff) with the coated rod under study was keff = 1.39132 ± 0.00064. When compared to the reference value of the hypothetical fuel element keff = 1.39207 ± 0.05, a relative percentage deviation of approximately δ ≈ 0.1% was observed. Based on this analysis, it can be concluded that doping Zircaloy-4 with 10% graphene nanotubes does not significantly alter the criticality parameter, indicating no significant changes in the neutronic parameters. Subsequent steps of the study will focus on assessing the heat transfer efficiency of the doped cladding and any associated mechanical alterations.

Materials and that can be used to protect against ionizing radiation. [1] The present work aimed to calculate the transmission factors of the epoxy matrix composite with graphene nanotubes at the proportions of 10%, 30%, and 40%, respectively, for use as shielding for electromagnetic and neutron radiation.A computational model was created to evaluate, through simulation using the Monte Carlo method with MCNP5, the radiation transmitted by epoxy-based polymer matrix composite materials and graphene nanotubes [2],[3]. Three study model compositions with 10%, 30%, and 40% graphene nanotubes in the matrix were analyzed. Initially, the designed setup was chosen because it had already been used in other works. The experiment was also simulated for fast neutrons (8 MeV, 6 MeV, and 1 MeV), epithermal neutrons (1 eV), and thermal neutrons (0.025 eV and 0.001 eV) with energies [5],[6]. For both photons and neutrons, the Tally F1 was discretized into 100 energy intervals to obtain data for calculating the transmission factor [4]. It is observed that for electromagnetic radiation, there is no significant change with the addition of material for the energy levels presented. However, the material composites behave relatively well for the attenuation of fast and thermal neutrons. It can be seen that for 1 MeV neutrons, the material composite had a significant improvement with the addition of fiber. Therefore, it is concluded that for fast neutron shielding, the material composite performed better. It can be seen that the composite in question showed a high upscattering rate, and it should be analyzed which element acted for this.

Noise pollution is increasingly recognized as a public health issue, with studies linking excessive noise exposure to a range of adverse health problems, such as sleep disturbance, stress-related disorders, cardiovascular diseases, and cognitive impairment. This growing awareness of the detrimental effects of noise pollution has underscored the importance of acoustic comfort in buildings on a global scale, highlighting the control of noise propagation in determining the final quality of architectural projects.In response to this recognition of the importance of acoustic building comfort and the elevated frequency of complaints of users regarding noise generated, particularly in multi-story buildings, Brazilian Standard was implemented in 2013. This standard is designed to guarantee acoustic performance and meet the expectations of building users by setting forth acceptable noise transmission levels. Furthermore, in 2021, additional standards addressing acoustic insulation and field measurements of airborne noise were also introduced [7,8], further solidifying the commitment to ensuring optimal acoustic conditions within buildings and enhancing occupant comfort and well-being. The imperative of establishing conducive acoustic environments led to an increase in research and development efforts, resulting in novel materials and construction methodologies attuned to the exigencies of architecture. It is known that to achieve the goal of mitigating sounds transmitted through a building structure, it is essential to disrupt the rigid connection responsible for propagating mechanical vibration. The incorporation of highly porous materials into floors offers potential for bolstering sound absorption capabilities. Strategies such as altering the impact surface, using elastic separation, or introducing resilient materials between the floor covering and structural slab prove to be efficient and became common. Despite these solutions demanding specialized labor for execution, there remains a dearth of research assessing their actual acoustic performance.Integrating environmental awareness with advances in acoustic engineering, civil construction emerges as a leading sector actively integrating recycled solid waste into building components to promote sustainability, consequently enhancing acoustic performance [1,2]. These solutions not only exhibit superior soundproofing characteristics but also complement sustainability goals.An example of waste that is readily and abundantly found in Brazil, and, above all, must be handled properly, is the end-of-life tire. This material has been the focus of numerous studies exploring its integration into mortars [3-5]. According to Institute of Environment and Renewable Natural Resources [6], over a million new tires were manufactured, generating more than five hundred thousand tons of end-of-life tire waste in Brazil in 2017. Furthermore, tire rubber is classified as Class II non-hazardous waste, indicating that it poses no potential risks to the environment and public health [7].To actively contribute to the mitigation of noise in multi-story buildings and to further the goals of sustainability, this study delves into the incorporation of rubber derived from end-of-life tire waste into the mortar used for subfloor applications. The investigation aims to assess the effectiveness of this innovative approach in enhancing acoustic insulation and promoting environmentally conscious construction practices.

Composite materials are engineered by combining two or more materials with distinct properties, yielding a material with superior characteristics compared to its individual components. These composites often find application in shielding against ionizing radiation [1]. This study aims to assess the transmission factors of an epoxy matrix composite embedded with silica (SiO2) nanoparticles, at proportions of 10%, 30%, and 40%, for electromagnetic radiation and neutron shielding purposes. A computational model was developed to evaluate radiation transmission through simulations using the Monte Carlo method with MCNP5 [2],[3]. Three composite configurations with varying silica nanoparticle concentrations in the matrix were analyzed. The experimental setup was chosen based on prior research, with a sphere radius of 1 cm adopted. The simulations encompassed fast neutrons (8 MeV, 6 MeV, and 1 MeV), epithermal neutrons (1 eV), and thermal neutrons (0.025 eV and 0.001 eV) [4],[5]. Tally F1 was utilized for both photons and neutrons, discretized into 100 energy intervals to gather transmission factor data [6]. Notably, no significant alteration was observed in electromagnetic radiation transmission with the addition of material across the studied energy levels. However, the composite materials exhibited favorable attenuation properties for fast and thermal neutrons. Particularly, a substantial enhancement in shielding efficiency against 1 MeV neutrons was noted with the incorporation of fibers. Consequently, the composite material demonstrated superior performance in shielding fast neutrons, aligning with existing literature [7]. Furthermore, the composite exhibited a notable upscattering rate, prompting further investigation into the contributing elements.

As energy demand rises, the drive for materials research in the nuclear industry intensifies [1],[2]. Consequently, discussions center on novel materials aimed at enhancing efficiency within the nuclear domain. Presently, ongoing studies focus on the utilization of SiC in nuclear power plants, owing to its proven efficacy in averting hydrogen gas emissions during LOCA-type accidents [3][4].  A concern in reactor operations is comprehending the behavior of fuel rods during the fission process of UO2 pellets [5],[6], and the ensuing heat exchange mechanisms. To unravel these key characteristics, a study scrutinized the criticality of a fuel rod sheathed in Zircaloy doped with SiC nanoparticles [7],[8], employing simulation via the MCNP code. Simulations of the fuel element encompassed an enrichment distribution of 3.2%, 2.5%, and 1.9% of UO2 based on a hypothetical PWR reactor model. Utilizing the MCNP5 software, a hypothetical fuel assembly for a PWR reactor was modeled with 25 fuel rods housing UO2 pellets across three enrichment zones (3.2%, 2.5%, and 1.9%) and standing 3.6 meters tall. The simulation employed the kcode method to compute the criticality of the simulated fuel, with 10,000 neutrons per cycle over a total of 100 cycles, half of which were passive. To fulfill the study's objective, the initial simulation employed pure Zircaloy-4 as a reference standard for fuel element criticality, with a subsequent simulation incorporating this alloy doped with 10% SiC. The resultant effective multiplication factor (keff) for the coated rod was calculated as keff = 1.39132 ± 0.00064, compared to the reference value of keff = 1.39207 ± 0.00072, yielding a relative percentage deviation of approximately |δ| ≈ 0.054%. Notably, doping Zircaloy with SiC nanoparticles demonstrated no significant alteration in neutron production, facilitating alloy enhancement without compromising energy production efficiency. The simulation results suggest that the addition of SiC nanoparticles can enhance the properties of Zircaloy alloy without sacrificing energy production efficiency. The minor relative deviation between the keff values for doped and undoped rods indicates insignificant impact on fuel rod criticality. Overall, this study underscores the promise of SiC nanoparticle doping in improving alloy properties, necessitating further research to validate these findings and explore potential benefits in greater detail.

Several applications were investigated, including fuel rod coatings, structural alloys, and cooling materials in nuclear reactors, with an emphasis on enhancing performance, safety, and durability [1]. The results demonstrated that niobium doping offers numerous benefits, such as improved corrosion resistance, increased stability in high-temperature and radiation environments, and a reduction in criticality of nuclear fuel elements [2-3]. These findings highlight the potential of niobium as a strategic material in the nuclear industry, providing promising solutions to the challenges of safe and efficient nuclear reactor operations, including those of small modular reactors (SMRs)[4]. The effective multiplication factor (keff) for a rod coated with 10% niobium was keff = 1.10807 ± 0.00058. Compared to the undoped reference value of keff = 1.12086 ± 0.00064, there is a relative reduction in criticality of approximately 1.14%. The computational simulation using MCNP5 with kcode provided a detailed analysis of nuclear fuel criticality. The results showed that doping Stainless Steel 316[5-6] with niobium reduced the effective multiplication factor (keff) by about 1.14%. This suggests that adding niobium significantly affects neutron production, crucial for PWR nuclear reactor operation. This reduction indicates niobium's effectiveness in controlling nuclear reactions and mitigating reactor operation risks[7-8]. Thus, niobium plays a key role in optimizing the performance and safety of nuclear fuel elements. The potential application of niobium in small modular reactors (SMRs) will be studied, as it could significantly enhance the safety, efficiency, and durability of next-generation nuclear energy systems. Its unique properties make it a valuable material for a wide range of applications in the nuclear industry.

The research examined the simulated transmission factor of depleted uranium dioxide for gamma radiation shielding. Depleted uranium dioxide, a dense and mildly radioactive material mainly consisting of uranium-238, finds extensive use in military contexts, notably in armor-piercing munitions[1-2]. However, it also serves civilian purposes like radiation shielding in medical settings, counterweights in aerospace and naval vessels, radiation protection in shielding, and stabilizers in construction[3]. The investigation validated its efficacy in shielding gamma radiation emitted by cesium-137 and cobalt-60 isotopes[4]. The increase in transmission factor for cobalt-60 is not linear, a phenomenon attributed to the manner in which gamma radiation interacts with matter at energies of 1.17 and 1.33 MeV. As gamma ray or electromagnetic radiation energy escalates, its penetrative capacity intensifies. Moreover, the interaction of radiation with matter, particularly the formation of pairs emitting positrons of annihilation, contributes to the heightened transmission factor observed for cobalt-60 energies[5]. With the consideration of the obtained transmission factor results of 11.01% for cesium-137 and 65.56% for cobalt-60, it is apparent that depleted uranium dioxide demonstrates efficacy in shielding against gamma radiation across various energy spectrums[6]. Its exceptional density and inherent radiation absorption capabilities render it indispensable in environments necessitating robust radiation protection measures, such as nuclear facilities, research laboratories, radioactive material storage locales, and space missions. However, prudence mandates a comprehensive evaluation of potential health and environmental risks associated with depleted uranium dioxide utilization[7-8]. The possibility of radioactive particle release underscores the imperative for meticulous safety protocols and rigorous risk assessment frameworks. Consequently, while depleted uranium dioxide stands as a viable option for gamma radiation shielding applications, strategic deployment strategies and stringent safety measures remain pivotal considerations in maximizing its benefits while mitigating associated risks.

The quest for enhanced materials in the nuclear industry is escalating alongside the surge in energy demand. This drive has led to the exploration of novel materials aimed at optimizing nuclear applications[1-2]. Among these, niobium has long been scrutinized as an alloying agent due to its advantageous attributes, including low thermal neutron absorption and robustness under the extreme conditions prevailing within nuclear reactors. A pivotal aspect of reactor operation revolves around comprehending the behavior of fuel rods during the fission process of UO2 pellets and, by extension, the dynamics of heat transfer therein. To delve into these critical parameters, a study delved into the crucial matter of a fuel rod sheathed in niobium-doped Zircaloy, employing MCNP code simulations. These simulations encompassed a variety of enrichment levels (3.2%, 2.5%, and 1.9% UO2) based on a hypothetical PWR reactor model[3]. The investigation focused on assessing the criticality of fuel rods encased in Zircaloy-4 doped with niobium nanoparticles. MCNP5 code facilitated the simulations, modeling a fuel element comprising 25 rods housing UO2 pellets across three enrichment zones[4-5]. The fuel element's height stood at 3.6 meters. Utilizing the kcode method, the criticality of the simulated fuel was evaluated. A total of 10,000 neutrons per cycle were employed over 100 cycles, half of which were passive. The analysis yielded an effective multiplication factor (keff) of 1.380303 ± 0.0007 for the coated rod, compared to 1.39207 ± 0.00072 for the reference undoped rod, reflecting a relative deviation of approximately |δ| ≈ 0.84%. Notably, doping Zircaloy with niobium nanoparticles showcased no substantial influence on neutron production, preserving the alloy's energy production efficiency.  This observation underscores the potential for enhancing Zircaloy's properties through niobium nanoparticle doping without compromising energy production efficiency [6-8]. The marginal relative deviation in keff values between doped and undoped rods suggests minimal impact on criticality. Hence, niobium nanoparticle doping emerges as a promising avenue for refining alloy properties while maintaining energy production efficiency. Nonetheless, further research is warranted to validate these findings and delve deeper into the advantages of niobium doping.

SAE 5160 steel has applicability in several industrial branches due to its good tensile and fatigue resistance, as well as having good tenacity, high hardenability and ductility. However, in the case of a steel that has carbon contents between 0.65 and 0.64%, it becomes very hard and abrasive, wearing out the tool very quickly. In addition, it has relatively low levels of chromium, manganese, silicon, and other elements, alone or in combination. This naturally results in a steel that is more difficult to machine than common carbon steels ⁽¹⁾. 

Machining is a complex process that requires a significant level of preparation and experimentation, as it involves numerous variables. Thus, it is almost impossible to accurately predict the behavior of metals when they are machined ⁽²⁾. It is of great importance to try to minimize this unpredictability as much as possible, which is mainly since it is a plastic deformation process where the restriction is given by the cutting tool and by the variety of options of input parameters in the process. Some of these input parameters are characteristics of the material to be machined, coolant, machine used to perform the machining, cutting tool, machining speed, feed rate and more ⁽²⁾.

The knowledge acquired through experimentation is beneficial for several reasons, including increased operational safety, cost reduction, assertiveness of results and reduced time spent on finishing.

Some research available in the literature ^(3-5) has indicated the need to study the cutting parameters as well as to evaluate the behavior of tool wear, to outline strategies to facilitate the machining process. Herein, for the first time, this study is carried out for SAE 5160 steel.

In this work, the cutting parameters influences in the turning of a SAE 5160 steel bar were analyzed, using two different cutting tools starting from the parameters indicated by the manufacturers and adapting them to the best machining conditions, aiming at greater use of the cutting tools, evaluating the results and impacts on operational risk as well as material properties. At the end, find a working range where the industry can perform rough machining in an economical, efficient and safe way.

Composites with natural lignocellulosic fibers (NLFs) currently have extremely diverse applications, including in engineering industries, due to their lower cost and density, as well as ease of processing. Another notable material, graphene oxide, has attracted considerable attention for its properties, mainly as a coating to improve interfacial adhesion in polymer composites. Therefore, this research focuses on investigating the dynamic mechanical (DMA) and thermomechanical analysis (TMA) for epoxy matrix composites containing 30% by volume of CM sedge fiber incorporated with graphene oxide. Compared to the control group (untreated epoxy) the damping factor (Tan δ), being the ratio of the loss modulus under storage, is significantly increased from (0.55-0.75) for the composites reinforced with 30% of CM sedge fibers incorporated with graphene oxide. The Tg found at 127°C for condition 30 FJGO/EP was higher than the other EP conditions, 30 FJ/EP and 30 SF/EP-GO, as well as the coefficient of thermal expansion (208.52 to 248.95 x 10−6/°C). The mass loss for the 30 SFGO/EP condition in the first stage was slightly higher than the EP condition (1.63%). These DMA and TMA results prove to be promising.

Natural fibers have been widely studied and used in polymeric biocomposites, aiming to enhance their mechanical and thermal properties. These fibers stand out for their relatively low cost and sustainable characteristics. However, when used as reinforcement, they present adhesion issues to polymer matrices due to their hydrophilic nature, contrasting with hydrophobic matrices. Surface treatments are a feasible solution to enhance this interaction. In this study, the effectiveness of three surface treatments applied to coffee husk fiber waste (CHFW) was evaluated to enhance the performance of green polyurethane (GPU) biocomposites based on castor oil. The analyzed treatments were: i) chemical with sodium hydroxide (NaOH) solutions, ii) hydrothermal under high temperatures and pressures (HYD), and iii) biological with solid-state fermentation by the fungus Phanerochaete chrysosporium (BIO. For evaluation, biocomposites were fabricated with 20% by weight of CHFW (in natura and with each of the proposed treatments: NaOH, HYD, and BIO). The tensile strength of the biocomposites was analyzed based on ASTM D3039 [2], the water absorption, and morphology through scanning electron microscopy. A superior increase of over 60% in tensile strength was observed in biocomposites reinforced with CHFW-HYD, compared to in natura CHFW, with achieved strength of 16.3 MPa. Surface treatments on lignocellulosic fibers or particles contribute to enhancing the interface between particles and the matrix, thus increasing mechanical properties. There were no significant modifications in the water absorption of the biocomposites. Scanning electron microscopy analyses showed an improvement in the interface between GPU and CHFW-HID compared to other treatments. Based on the results, it can be concluded that the HIDRO treatment was the only one resulting in increases in tensile strength. SEM images confirmed better adhesion of polyurethane to lignocellulosic particles, which is related to the reduction of extractive compounds on the surface of the coffee husk.

The golden mussel, Limnoperna fortunei (Dunker, 1857), an invasive species that arrived in South America in the 1990s, has caused significant impacts on Brazilian aquatic ecosystems [1]. The objective of this study was to investigate the potential of the herbicide glyphosate as a tool to control populations of golden mussels, whose proliferation results in environmental and economic damage. Two experiments were conducted to evaluate the toxic effects of glyphosate on golden mussels, revealing a direct correlation between the concentration of the herbicide and the mortality of the organisms [2]. Proliferation occurs at high population density, reaching populations of 150,000 specimens per square meter in natural environments and up to 240,000 specimens/m² in structures built by man [3]. Statistical analysis strengthened these observations, indicating significant differences in results. Furthermore, the feasibility of using glyphosate to contain fouling of golden mussels was discussed and the possibility of using these molluscs as a laboratory study model was explored. Importantly, the use of ultrasound to dislodge and eliminate golden mussels proved to be efficient and may represent an alternative to control the invasion of L. fortunei in your research [4]. Despite increasing information on biology, dispersal and control methods, studies on mussel behavior are still scarce in Brazil [5]. The findings highlight the importance of considering environmentally sustainable approaches to dealing with the spread of golden mussels, while highlighting the potential of glyphosate as a control option.

This study aims to evaluate the performance characteristics of polymer composite materials composed of light-curing acrylic resin utilized in additive manufacturing through the AM method via vat polymerization employing a DLP process, alongside flax fibers, using dynamic mechanical analysis (DMA). DMA measures the viscoelastic properties of a material in terms of stiffness and damping, including storage modulus (E'), loss modulus (E"), and the ratio between these moduli, tangent δ, as well as the glass transition temperature (Tg). The samples were printed to dimensions of 65x12x3.5 mm and in fractions of 0%, 0.5%, 1%, 1.5%, and 2% flax fiber. After printing, they underwent exposure to UV light (405 nm) for 12 hours. Subsequently, the specimens were subjected to dynamic mechanical analysis, which revealed an increase in initial E' between the 0% and 2% samples to 2041 MPa and 2083 MPa, respectively. The loss modulus (E") showed values of 214 MPa at 45° and 176 MPa at 58°, while Tg recorded values of 80°C and 88°C. In comparison to other composites, a reduction of up to 59% was observed in the storage modulus (E'), alongside a significant decrease in the loss modulus peak (E"). The composites exhibited more pronounced peaks in the tan δ graph compared to the pure resin. Notably, the composite with a 2% mass fraction demonstrated an 8°C increase in the glass transition temperature (Tg) when contrasted with the pure resin. The remaining composites maintained a glass transition temperature within the range of 72°C to 76°C.

The use of cellulose nanofibers and post-use coffee capsules for composites is a sustainable option to minimize environmental impacts, reduce waste generated, and add value to the materials [1]. Applying these composites as adsorbent material is a promising solution to guarantee a circular economy aimed at sustainability, making it possible to integrate the environmental problems caused by plastic and forestry waste with the remediation of areas affected by oil spills [2]. In obtaining cellulose nanofibers, the bark fibers and chips were pre-treated with an alkaline solution to remove amorphous components such as lignin and hemicellulose and subjected to the steam explosion process for defibrillation [3,4]. Polymeric composites were obtained with a coffee capsule matrix reinforced with 5, 10, and 20% (m/m) of bark and chips. These composites were used to obtain test specimens and were subjected to tests to evaluate the oil adsorption capacity. The thermal analysis results (TG/DTG and DSC) showed that the alkaline treatment followed by steam explosion increased the thermal stability of the fibers present in the Eucalyptus bark and decreased the stability of the chip flakes. The micrographs showed better adhesion of cellulose nanofibers from the bark and chip chips to the polymer matrix than cellulose microfibers. The BET/ BJH results showed that the bark has a larger surface area and larger pore volume but a smaller pore size, which may influence adsorption. Alkaline and steam explosion treatments increased the crystallinity of all samples. Specimens obtained from composites reinforced with 20% m/m of exploded showed the best adsorption efficiency, representing an unprecedented and encouraging result.

The emergence of diseases caused by the advent of human aging has led to the development of materials in bone tissue engineering (BTE) that can aid in the development of clinical treatments. Among these materials is the development of synthetic bone grafts through additive manufacturing. In this study, the scaffolds were developed by fused deposition modeling (FDM) using polylactic acid (PLA) doped with hydroxyapatite (HA) extracted from the scales of the pirarucu (Arapaima gigas). Fourier transform infrared spectroscopy (FTIR) analysis reveals bands at 1096 cm-1; 1018-1011 cm-1, 602 - 555 cm-1 that are attributed to calcium phosphate and hydroxyapatite minerals. Thermal analysis reveals four periods of weight loss, related to moisture loss, elimination of organic compounds, carbonation and removal of hydroxyls from HA sites. The addition of HA resulted in a decrease of 20.38% in compressive strength and 25.67% in apparent compressive modulus. Obtaining compressive strength of 3.14 MPa and 2.5 MPa, respectively, for samples SFP and SF1H and, respectively, compressive modulus of 108.55 MPa and 80.68 MPa.

The search for synthetic materials with bioactive, osteoconductive, and biocompatible characteristics is becoming highly desirable for various biomedical applications. Hydroxyapatite (HA), a biomaterial, is an inorganic ceramic that closely resembles the mineral apatite, primarily found in human bones and teeth. Its characteristics, such as biocompatibility, cell adhesion, bioactivity, and degradation, are fundamental for potential applications as a biomaterial, particularly in bone regeneration [1][2]. Thus, this study aims to synthesize and characterize hydroxyapatite using the precipitation technique by the wet method, with the use of acid/base reagents. In order to analyze the chemical elements and microstructure of the obtained material, techniques such as X-Ray Diffraction (XRD), Rietveld Refinement, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS) were employed. The XRD results showed peaks of hydroxyapatite and calcium oxide. The FTIR analysis revealed vibration bands of carbonates (CO₃^2-) and phosphates (PO₄^3-), characteristic of the material. SEM indicated irregular morphologies with different shapes and forms. Additionally, EDS analysis showed the presence of calcium, phosphorus, and oxygen, and through this result, the Ca/P molar ratio was determined to be 1.60. The characterizations indicated the presence of B-type carbonated hydroxyapatite, suggesting a nanometric form with good crystallinity and density. Furthermore, it is suggested that the hydroxyapatite obtained in this study has great potential to be applied as a biomaterial.

A problem of the connection of cosmology with elementary particle physics is shown on the level of uncertainty relations. At the scales about 10^-2 m the contribution of one single type virtual elementary particles in the lower boundary of vacuum energy is considered. The observed value of vacuum energy or energy density on the large scale of the Universe corresponds only to this scale. This is the energy about 3.34 GeV per each one cubic meter. The minimal high energy physics scale achieved by experiments at present is considered. The lower boundary of the energy is generated by the quantum vacuum of empty space and the quantum vacuum limited by matter in the Universe mainly at scales down to 10^-15 m and more much are not in agreement with the observed value, as that is established. These lower limits for the energies of the vacuum are considered in the model of estimating where they generate by the presence of virtual particles in free space and the virtual particles which are limited by matter and exist together with matter in the Universe. The numerical values of the boundary energies are obtained using the computer algorithm.

Black shale is a unique vanadium-bearing resource in China. Therefore, extraction of vanadium from black shale for high value applications becomes important [1]. Biological vanadium extraction from black shale is an emerging alternative to conventional metal extraction. During bioleaching, rare metals in minerals are converted to a soluble or extractable state by the action of bacteria [2,3,4]. Compared with traditional recycling process, the bioleaching is greener, more efficient and requires lower cost as well as energy [5]. Acidithiobacillus ferrooxidans (A. ferrooxidans) is one of the most important autotrophic bacterium involved in bioleaching. It is also a bioleaching microorganism that was well studied and was of most economic benefits in biological metallurgy.

However, the biotechnology of vanadium extraction still faces problems such as irrational regulation of influencing factors, low leaching rate, and poor fluorine tolerance of bacterial strains. To address the above problems, this paper domesticates a fluoride-tolerant bacterium, utilizes the role of fluoride in chemical leaching that can destroy the mica crystal lattice, and uses fluoride as a leaching aid to improve vanadium bioleaching in a new process.

In this paper, the fluoride tolerance domestication of the leaching strain Acidithiobacillus ferrooxidans and its mechanism and the parameters of the factors affecting the bioleaching process of vanadium-bearing shale was investigated. On the one hand, fluoride-tolerant strains were obtained by successive transient domestication, and the mechanism of fluoride tolerance in mineral-leaching strains was investigated from the genomic point of view; On the other hand, the influence of various factors on the bioleaching efficiency of vanadium-bearing shale was investigated, and the optimal process parameters for vanadium bioleaching were determined.

A strain tolerant to 0.05 mol/L F^- was obtained by eight consecutive transplants, and the enriched culture was used for vanadium biorefining, which showed good leaching performance on vanadium shale, with an increase of about 15% in leaching rate compared with chemical leaching.

Urban public transport is a vital part of urban mobility, especially in cities with a significant young population.

The appropriate public transport services should be seen from the aspect of fulfilling the passenger demands opposite the general cost, negative impacts on the transportation community as well as the externalities. Ecological transport in urban planning plays a decisive role towards creating spaces for sustainable living. Through Eco transport it is achieved the reduction in greenhouse gas emissions, improving air quality and reducing traffic congestion. 

The various current trends or developments are not always the possibility of achieving an ecological transport system for developing countries. Financial constraints can present challenges to the implementation of infrastructure projects. Therefore, in these places, improvement should be seen within the existing space of the infrastructure.

In this paper, the trip frequency of the public transport lines for a case study has been analyzed and improved through linear and non-linear programming optimization methods according to the minimization trip frequency that consequently cause fuel consumption, gas emissions while respecting the passenger demand, passenger service without significant delays, constrained number of bus fleets, and daily fuel budget.

The crystalline PEO₆LiX complex features a tunnel-like polymer/salt structure that facilitates rapid lithium ion movement. However, its practical application is restricted because high ionic conductivity is only achievable with low molecular weight PEO; as the molecular weight increases, the alignment of tunnels is disrupted, resulting in reduced conductivity. High aspect ratio nanofillers derived from cellulose nanowhiskers are proposed to enhance tunnel structure formation. Compared to unfilled electrolytes, the ion conductivity at room temperature increases by up to 1100% when filled with cellulose nanowhiskers. Wide angle X-ray scattering (WAXS) reveals that adding cellulose nanowhiskers transforms the structure from an amorphous to a crystalline phase due to the enhanced crystallization driven by the interaction between the cellulose surface and polymer chains. Temperature-dependent conductivity measurements indicate that the activation energy for Li+ hopping is lower in samples filled with acidic cellulose nanowhiskers. Quasi-elastic neutron scattering (QENS) shows that the acidic surface stabilizes the rotation of PEO₆ channels, which likely accounts for the reduced activation energy and increased conductivity.

During the processing of polymetallic ores, a large amount of waste is formed containing heavy metal sulphides, which, as a result of natural leaching, enter the mine and mine wastewater, polluting the environment. The toxic effect of heavy metals on living organisms leads to disruption of enzymatic reactions .

This work is devoted to the study of the possibility of electrolytic purification of wastewater, primarily from copper (II) ions, which are characterized by high toxicity and are one of the main sources of pollution of the hydrosphere. The electrolysis method ensures minimal costs for their further processing and creates the possibility of implementing resource-saving and low-waste processes.

However, the difficulties of cleaning dilute solutions from heavy metal ions by means of electrodeposition are associated with the low speed of the process and the presence of side reactions. Therefore, the development of the method and the creation of effective designs of industrial devices that allow the intensification of the electrolysis process open up the prospect of using the method to extract metals from dilute solutions.

To extract copper with a high degree and high current yield from dilute solutions, we have developed a special design of an reactor with a high hydrodynamic regime [1].

In the reactorr, the radially arranged electrodes have the shape of a Leprechaun. In the center of the electrolyzer, there is a mechanical stirrer of an original shape, which directs the flow of liquid between the electrodes with a strong centrifugal force. The shape of the electrodes maintains the flow of liquid in a circular motion along the wall of the cylindrical reactor. The reactor operates on the hydrocyclone principle and the flow of liquid moving at high speed along the electrodes removes the cathode product, which, after passing through the corresponding windows of the reactor, is collected at the bottom of the conical body (collector), from where it is periodically unloaded. The reactor achieved a significant improvement in the intensity of forced convection and a solution to the problem of removing copper powder from flat stainless steel cathodes.

Large-scale laboratory tests have shown that a cascade arrangement of two such reactors, one of which operates at high current values ​​(I-15A, Cu-1.08g/l, Q-85.2%, ɳ-62.1%, W-3800 kW∙hour/t), and the other at lower ones (I-4.0A, , Cu-0.16g/l, Q-68.6%, ɳ-27.5%, W-7339 kW∙hour/t), allows a total extraction of up to 95.4% of copper from quarry water with a current efficiency of 54.9% with a residual copper concentration in the solution of 0.05 g/l and a specific energy consumption of 4175 kW∙hour/t, which corresponds to 5-10% of the cost of copper.

As the research results showed, the bottleneck in the design of the above reactor with flat steel electrodes is the process of extracting copper with a concentration of Cu≤0.16 g/l (second reactor).

In order to intensify the reactor process at very low copper concentrations  in solution Cu≤0.16 g/l, we designed a new electrochemical reactor, in the center of which a volumetric-porous flow-through cathode block with a mechanical stirrer is located [2]. The cathode block consists of perforated cylindrical graphite on which a carbon material with high physical, chemical and operational properties is wrapped along its entire height. The mechanical stirrer facilitates the free passage of liquid through the pores of the carbon-graphite material, thereby reducing the hydrodynamic resistance of the solution flow and increasing the rate of metal deposition by reducing the cathodic polarization in the thickness of the carbon material.

It has been experimentally established that when using an electrolyzer with flat steel cathodes from dilute solutions (Cu≤0.16 g/l), copper extraction in 1 hour is 19.6% with an extraction rate of 2.22 g/h˖m2, while in an electrolyzer with cathodes made of carbon-graphite materials, all other things being equal, it is 83-84% with an extraction rate of 15.1 g/h˖m2, as a result of which the intensity of the process increases by 6.8 times. 

It is important to note that electrolytic copper can be extracted from the surface of a carbonaceous material by repeated chemical or electrochemical regeneration without changing its electrode properties.

The Nickel-Titanium (NiTi) alloy belongs to the group of smart materials, standing out for its excellent shape memory properties, superelasticity, damping, and biocompatibility. This alloy is used in both technological fields and, more importantly, in medical and dental areas. The use of powder metallurgy processes in the production of titanium alloy products is justified by its economic advantages, such as high raw material utilization, low energy transformation compared to fusion processes, excellent dimensional tolerance, allowing for various combinations and control of chemical elements (alloys). Therefore, powder metallurgy becomes an interesting process in the development of new materials, with a tendency to reduce the manufacturing costs of Ni-Ti alloys, achieving mechanical properties similar to human bone.This study proposes a microstructural analysis and an examination of the physical and mechanical properties of the NiTi alloy processed via powder metallurgy, combining temperature and time to produce a material suitable for biocompatibility feasibility testing in the human body.The alloy sintering was conducted over 24, 36, and 48 hours at a temperature of 932°C without the presence of the liquid phase. This study includes characterization techniques for mechanical properties using Vickers microhardness, and metallographic analysis using Optical Microscopy (OM) and Scanning Electron Microscopy (SEM).It was observed that with increased sintering time: porosity decreased, resulting in volumetric shrinkage and increased density. Thus, sintering for 36 hours proved to be the most ideal, potentially resulting in an alloy with the best shape memory effect properties.

Many perovskites and their piezoelectric composites have been investigated for harvesting ambient mechanical energy over the past two decades; however, the prospects for their commercialization appear remote because of several practical challenges. Therefore, highly scalable supersonic cold-spraying technology was used to fabricate flexible piezoelectric films of poly(vinylidene fluoride) (PVDF) and a novel perovskite SrTiO₃ (ST). Substantial shear stress was exerted on PVDF during cold spraying owing to the hydrothermally synthesized SrTiO₃ nanocubes and supersonic velocity, and the resulting film delivered an effective piezoelectric coefficient (69.6 pm·V^-1) as confirmed by piezo-response force microscopy. As a result, the piezoelectric nanogenerator yields a maximum power of 130 µW at a load resistance of 0.9 MΩ. The composite film exhibited durability for 21,000 tapping cycles with 20 N applied force and 7 Hz frequency. The flexibility endurance was confirmed from 3000 bending cycles, and bending PENG attached to knee delivered 1 and 2.3 V on bending to 45 and 90°, respectively. After electrical poling, the PENG was subjected to a 20 N tapping force that yielded a piezopotential of 31 V. To the best of our knowledge, this is the first time piezoelectricity was obtained using an ST/PVDF composite via mechanical energy harvesting. The flexible PENG film deposited by cold-spraying shows good potential for wearable self-powered devices.

The presence of electroactive β- and γ-phases in poly(vinylidene fluoride) (PVDF) increased by more than two folds upon supersonically spraying Sr₂SnO₄ nanorods (SSO-NRs). Shear stress between the PVDF and SSO-NRs, induced by supersonic blowing and catastrophic impact against the substrate, amplified the β- and γ-phases, which enhanced the energy-harvesting performance of a flexible piezoelectric nanogenerator (PENG). The high-aspect-ratio SSO-NRs magnified the influence of shear stress by intensifying the turbulence induced by their swirling. The supersonically driven shear stress caused multidirectional stretching, elongation, and twisting of the PVDF and transformed a large amount of the α-phase into electroactive β- and γ-phases, as evidenced by X-ray diffractometry and infrared spectroscopy. The composite film with a minimal filler content of 2.5 wt% exhibited a piezopotential of 40 V without additional poling. The optimal SSO/PVDF-based PENG delivered a high power density of 87 µW·cm⁻²_, when it was subjected to a tapping force. Furthermore, the practical applicability of the PENG was illustrated using air pressure, vibration, and human body movements. The fabricated PENG device was integrated with a supercapacitor electrode to demonstrate its wide range of applications in wearable and portable electronics.

Highly flexible and conductive carbon nanofibers (CNFs) embedded with pseudocapacitive iron–vanadium oxide (FVO) were fabricated via electrospinning followed by high-temperature annealing (900 °C). CNFs have a graphitic structure with minimal defects, which could hinder the access of electrolytic ions to multivalent FVO. Therefore, a sacrificial polymer, such as poly(methyl methacrylate) (PMMA), was introduced to enhance the electrolytic ion pathways by altering the internal structure of nanofiber. In addition, terephthalic acid was added to a polyacrylonitrile–PMMA solution to facilitate flexibility by increasing the cross-linking of the electrospun fibers. The fabricated flexible FVO/CNFs exhibited significantly enhanced electrochemical performance. The optimal sample had a high areal capacitance of 1058 mF·cm⁻² at a current density of 2.5 mA·cm^-2 and showed 100% capacitance retention during long-term cycling (10,000 cycles). The capacitance retention decreased to 81.3% when the current density was increased to 25 mA·cm^-2. The wider potential window of 0–1.6 V increased the energy density to 389 µW·h·cm^-2. The optimal FVO/CNF sample maintained 90% capacitance retention after 200 bending cycles.

The proper utilization and upcycling of plastic waste are essential for mitigating environmental damage, optimizing resource use, and advancing a circular economy [1]. Phosphorus doping of carbon materials introduces a high density of phosphorus-containing active groups and expands interlayer distances, which significantly boosts the electrochemical performance of the anode material [2].

In this study, we upcycled waste PET into phosphorus-doped hard carbon (P-HC) through a single-step pyrolysis process with orthophosphoric acid (H₃PO₄), aiming to enhance the electrochemical properties of the resultant carbon. The synthesized P-HC was characterized using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA-DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to elucidate its structural and thermal properties.

Electrochemical characterizations revealed that the P-HC anodes exhibit superior lithium storage capabilities, including high specific capacity and excellent rate capability (492 mAhg^-1 at 0.1 Ag^-1 and 131 mAhg^-1 at 3.5 Ag^-1, respectively), significantly outperforming non-doped PET-derived carbon. This enhancement is attributed to the improved electrical conductivity and structural stability imparted by phosphorus doping [3]. The P-HC anodes retained a high specific capacity after numerous cycles, demonstrating their potential for long-term application in LIBs.

This study presents a dual solution to plastic pollution and energy storage challenges by converting PET waste into high-performance anode materials for next-generation LIBs. This sustainable approach not only mitigates environmental impact but also contributes to the advancement of energy storage technologies.

The objective of this practical study was to ascertain whether metal sulfides (Me= Ni, Cd, Bi, Mo) can demonstrate synergistic effects when combined with carbon nitride, particularly in the g-C₃N₄/Bi₂S₃ composite, for the photocatalytic production of hydrogen from water using sunlight [1]. This represents a significant advantage, as it circumvents the necessity for the use of costly co-catalysts such as platinum. In this study, the composite was created using a combination of thermal and mechanochemical synthesis. Samples with varying component ratios in terms of bismuth sulfide (33.3%, 5.25%, 2.56%, 1.27%, 0.5%) were prepared with the objective of identifying the most efficient photocatalyst for hydrogen production. The findings indicated that the most efficacious photocatalyst for hydrogen production was theg-C₃N₄/Bi₂S₃ ratio of  2.56%. The findings indicated that the combination of bismuth sulfide and carbon nitride in the presence of visible sunlight exhibited a synergistic effect, thereby enhancing photocatalytic efficiency. This has the effect of reducing the cost of utilizing the material in question as a photocatalyst and in synthesis. SEM images depicts of the bismuth sulfide as a tubular structure, while the carbonitride is represented as a layered composition. This work contributes to advancing the fields of photocatalysis, organic dye degradation, hydrogen generation, and materials science.

The purpose of this work was to evaluate at different stages of environmental recovery the changes in chemical and physical attributes of topsoil impacted by iron mining in the Itabira-MG region that belongs to a mining company,  The environmental recovery of iron mining waste piles in a mine in the Itabira-MG region was evaluated and the physical and chemical attributes that influenced the recovery of the degraded areas were assessed. The results of analyses from different stages of topsoil pile recovery were compared and the results were statistically evaluated. The influence of these parameters on predicting the recovery of these impacted areas was verified. It was observed that the older waste piles showed better results regarding the presence of vegetation and microbiota. The chemical analysis of the soil showed a lower availability of nitrogen and phosphate. Metals showed a slight relative decrease (due to leaching and consumption by microorganisms in general). The upper layers showed greater variation in the general parameters of their components due to the removal promoted by vegetation. The total organic matter, for example, was found to be higher in more superficial layers due to the decomposition of plants, while deeper layers may have their total organic matter values related to old surface plants that were buried during the topsoil extraction process.

The aluminum industry faces an unprecedented crisis, characterized by significant environmental degradation and resource depletion. As one of the most energy-intensive sectors, its impact on global greenhouse gas emissions is alarming, necessitating immediate and innovative solutions. This poster investigates the transformative potential of AI-driven technologies in revolutionizing sustainable sourcing practices and enhancing supply chain transparency, positioning them as essential tools for combating these challenges.

By harnessing real-time data analytics and advanced machine learning algorithms, we examine how AI can optimize resource efficiency, improve visibility, and substantially reduce carbon footprints. For example, companies such as Alcoa have reported a 20% decrease in emissions following the implementation of AI systems for energy monitoring, which also enhance supply chain traceability and accountability. Our research poses critical questions: How can AI facilitate ethical sourcing in complex supply chains, and what specific metrics should guide sustainability impact assessments?

Employing a mixed-methods approach, our analysis includes qualitative case studies alongside quantitative data, revealing significant correlations between AI integration and improved sustainability outcomes. Furthermore, we explore interdisciplinary insights from materials science and environmental policy, illustrating the broader implications of AI innovations for transparency and ethical practices.

This work serves as a catalyst for deeper discussion and collaboration among industry leaders, policymakers, and researchers, advocating for a concerted effort toward sustainable development. We conclude with a call to action for further exploration of AI’s role in creating a more resilient and sustainable aluminum supply chain, aiming not just to meet current challenges but to redefine industry standards for the future.

Recent research has increasingly focused on lithium-sulfur (Li-S) batteries due to their notable advantages, such as a high theoretical capacity of 1675 mAh/g, low cost, and the abundance of sulfur. Despite these benefits, the commercialization of Li-S batteries is hindered by several challenges, including the insulating nature of sulfur, substantial volume expansion of up to 80%, and the polysulfide shuttle effect. To overcome these obstacles, various strategies have been proposed, including the incorporation of carbon-based materials as a matrix for sulfur, the use of polar materials, and modifications to the separators, etc. [1].

Graphene oxide (GO) is a highly advantageous host material used in Lithium-sulfur batteries owing to its superior electronic conductivity, extensive specific surface area, and advantageous mechanical flexibility. These properties make GO well-suited for the integration of sulfur particles, thereby promoting more efficient electron transfer and improving the overall effectiveness of the composite material [2].

MXenes are a diverse group of 2D early transition-metal carbides, nitrides or carbonitrides. Their surfaces, made up of transition metals (such as Ti, V, Zr, and Nb) and termination groups such as -O, -OH and -F are highly hydrophilic and form strong bonds with polysulfides. This makes MXenes promising for preventing polysulfide shuttling and enhancing the stability of Li-S batteries [3].

Using carbon-based materials from natural biomass waste, like rice husk (RH), is popular for being cost-effective, renewable, and sustainable. These materials also have intrinsic micro and mesoporosity, making RH a promising source for low-cost, porous carbons. For the modification of Li-S battery separator, a key approach is creating composites of carbon and MXene. This combination offers numerous active sites for efficient electrochemical charge transfer and strong adsorption of lithium polysulfides (LiPSs). The composite effectively captures LiPSs through both chemical and physical interactions and helps manage volume expansion during battery cycling [4].

GO/S and GPC/MXene composites were synthesized and characterized using SEM, TEM, XPS, and XRD. SEM images confirmed the successful removal of "A" layers from the MAX phases, showing structural changes. 

Electrochemical tests were performed with CR2032 coin cells. A slurry of 80 wt% GO/S, 10 wt% conductive acetylene black, and 10 wt% polyvinylidene fluoride binder in N-methyl-2-pyrrolidone was coated onto carbon-coated aluminum foil to make the cathode. Additionally, the GPC/MXene composite was coated onto a Celgard 2400 separator. The GO/S cathodes with bare separator achieved an initial discharge capacity of 1210.71 mAh/g, while with GPC/Mxene coated separator reached 1632.9 mAh/g. After 100 cycles, their capacities were 864.47 mAh/g and 1011.88 mAh/g, respectively, highlighting their potential for Li-S battery applications.

The quality and functional properties of any material, including composite systems, are determined by their phase composition and structural characteristics. One of the effective methods of influencing and regulating the level of activity of the system is mechanochemical treatment (MCT) of powder systems, which allows changing their degree of dispersion, defectiveness and forming highly active formations on the surface of particles [1]. The role of surface structures is extremely important in the creation of modified powder materials with a given set of properties. 

Modification of mineral powder particles directly during the grinding process is one of the areas of mechanochemical processing of inorganic materials [2, 3]. Mechanochemical processing will allow purposefully changing the state and chemical activity of the mineral components of the charge mixtures. 

The work involved studies on obtaining SHS heat insulators with pre-activated raw materials. Experimental work was carried out using natural mineral raw materials - grade "A" calcined diatomite crumb (fraction 0-0.2 mm). During preliminary mechanical activation, graphite was used as a modifier in the amount of 10 and 20%. Aluminum grade APV was used as a reducing agent. Sodium liquid glass served as a binder.

A positive effect of using various modifiers during the MCT of diatomite, activating the combustion process, was established. The selection of modifiers provides an increase in the strength of the synthesized SHS composites as a result of the formation of aluminate compounds in the synthesis products and a decrease in thermal conductivity to 0.157 W/m*K due to the formation of an ultraporous structure of the samples.

Scanning tunneling microscope (STM) [1] is an experimental device mostly known for direct obtaining of three-dimensional images of conductive solid surfaces with an atomic resolution. In 2003, Xu and Tao [2] introduced a new experimental technique based on the STM device for inspecting electric properties of single molecules. By repeated formation and breaking of a large number of junctions formed by STM metal (gold) tip and substrate electrodes with a molecule trapped in between, they were able to determine an electric conductance of a given molecule. Named an STM-based break junction (STM-BJ) technique, it has become the most common method used to study electronic properties of single‑molecule junctions. [3] In this work we demonstrate the ability of our highly‑sensitive STM-BJ setup to distinguish between two different states of conjugation (namely the aromatic conjugation and cross‑conjugation) on a pair of 4‑pyridyl‑ethynyl‑terminated representative model molecules. The variation of conjugation in probed systems is provided via core structure formed by one of two stable oxy‑derivatives of anthracene. Presented experimental method has been applied to examine the conjugate states of monomeric metalloporphyrin units in monolayers.

Kosovo possesses vast coal reserves, which have historically ensured energy security and economic stability. However, the environmental consequences of relying on coal, including high carbon emissions and air pollution, have prompted debates about the sustainability of this energy source. This paper explores the tension between energy security and environmental sustainability in Kosovo’s coal-based power sector. It evaluates the economic benefits of coal for a small, developing nation while addressing the growing environmental and health costs. The study argues that while renewable energy is seen as a cleaner alternative, the transition is fraught with challenges due to the country's dependence on coal and lack of renewable infrastructure. A more realistic approach could involve improving coal efficiency and implementing cleaner technologies to balance energy security with environmental goals. This analysis highlights the need for a pragmatic, gradual shift rather than an immediate overhaul of Kosovo's energy sector.

This paper explores the transformation of Kosovo's industrial sector from lignite-based energy to sustainable practices, with an emphasis on applying the Life Cycle Assessment - LCA methodology. The research explores how key industries, including lignite, ferronickel, and rare metal production, can improve competitiveness while reducing environmental impacts. A significant focus is placed on the production of synthetic gas from lignite, a key byproduct that can serve as an energy source, and the integration of sustainable practices within lignite power plants to mitigate environmental degradation. The FLOGEN Sustainability Framework is evaluated as a practical implementation model for embedding ecological principles into industrial processes. Three production models—linear, quasi-cyclic, and dynamic equilibrium—are analyzed, with the dynamic equilibrium model, which mirrors natural ecosystem cycles, identified as the most viable for achieving sustainability. This model stresses the continuous recycling and reuse of energy and waste, aligning industrial processes with ecological systems. However, the realization of such a model demands advanced technologies, innovative equipment, and the restructuring of industrial parks. The paper posits that adopting this approach, including the utilization of lignite-derived gas, can catalyze industrial restructuring, drive economic growth, improve social well-being, and protect the environment, thereby enhancing Kosovo’s industrial competitiveness.

Titanium alloy (Ti-6Al-4V) has been widely used in medical field due to its good biocompatibility and machinability. However, Ti-6Al-4V lacks antibacterial ability, which can be easy to lead the surgical infection by bacteria. At the same time, the release of the toxic ions such as Al or V in Ti-6Al-4V to the human body under the physiological environment is also easy to cause harm to the human body. Therefore, in order to solve the above problems, this study first used magnetron sputtering technique to prepare TiN-Cu composite coatings on the surface of Ti-6Al-4V, which is expected to take advantage of Cu's antibacterial properties to achieve long-term antibacterial effects while preventing the release of toxic ions. Second, in order to enhance cell adhesion of the TiN-Cu composite coatings, plasma immersion ion implantation (PIII) was used to implant Mg ions into the surface of the composite coatings respectively. A series of measurements (such as XRD, XPS, SEM, etc.) were used to analyze the structure, composition and mechanical properties of TiN-Cu composite coatings before and after implantation with different ions. L929 cells and Mc3t3-e1 cells were used to analyze the cell proliferation and adhesion on the sample surfaces. The survival of Escherichia coli by using the coating plate method. The results showed that the surface of Mg+ implanted TiN-Cu composite film had the best antibacterial property and cell proliferation ability with the highest protein adsorption ability. Cu trapped electrons on the bacteria's surface and destroyed their membranes. In addition, the bonding of Cu and respiratory enzymes in the bacteria also caused bacterial dysfunction. The implanted Mg+ on the surface stimulated protein adsorption, the cell adhesion and proliferation.

The wide use of refractory metal carbides in industry as structural and tool materials that are able to operate at high temperatures and loads in aggressive media causes great interest for the development of novel sustainable, highly efficient, eco-friendly and safe methods for their production. High-temperature electrochemical synthesis (HTES) from molten salts is one of them. 

The HTES of carbides can be effected in two ways. In the first case, the molten electrolyte contains one synthesis component in the molecular or ionic form, which is discharged at the second synthesis component. The formation of carbide takes place as a result of the reaction diffusion of discharge products deep into the electrode material. Either—alkali (alkaline-earth) metal carbonates, which can be reduced to elemental carbon on the cathode made of a refractory metal (electrochemical carbidization) [1], or refractory metal ions, which are reduced to metal on the graphite cathode [2], are used as discharging component. The above processes occur at a low rate at relatively high temperatures and produce compounds of variable composition in the form of coatings.

In the second case, the electrolyte contains both synthesis components, which can discharge together (thermodynamic or quasi-equilibrium synthesis conditions) or sequentially (kinetic synthesis conditions) at the neutral electrode [3]. After that, a chemical interaction of discharge products takes place at the cathode to from a new carbide phase. The thermodynamic synthesis conditions are undoubtedly more interesting theoretically and promising in practical use. By varying the electrolysis conditions and modes (electrolytic bath composition, current density, and temperature), one can obtain single-phase carbides of a given composition in the form of coatings or ultrafine powders, as well as composite mixtures with other metals and carbon.

To effect electrosynthesis under thermodynamic conditions in a wide current density range, two conditions must be fulfilled:

(1) The synthesis must take place at close values of refractory metal and carbon deposition potential. The theoretical analysis of the electrowinning of alloys, presented in [4], showed that if the deposition potential difference of alloy components (∆E) is not over 0.2 V, the alloy composition will not depend on the current density used, viz the process will take place under quasi-equilibrium conditions.

(2) Electrosynthesis is a many-electron process. Therefore, the second necessary condition for synthesis is effecting partial many-electron reduction reactions of synthesis precursors over a narrow potential range practically in one stage. The sources of metal and carbon are their oxy-compounds M_xWO₄, M_xCO₃ (M = Li, Na, Ca, Ba, Mg) and CO₂. The discharge products react chemically with each other to form carbides.

Electrochemical processes in ionic melts at high temperature differ greatly from low-temperature processes in aqueous electrolytes. At high temperature, the effect of catalytic properties of the electrode material on the electrode kinetics becomes weaker. At the same time, the catalyzing role of the medium (electrolyte composition) becomes more pronounced. 

The effect of the medium on the kinetics of electrode reactions is clearly manifested in the reduction processes of tungstate and molybdate anions (complex coordination compounds of d metals in the higher valent state) and carbonate anions. The specific mechanism of formation of electrochemical active spaces (EASs) and many-electron charge transfer reaction are characteristic peculiarities of the electroreduction of the above compounds.

The essence of cation catalysis is the transformation of complicated complex anionic species into a new active state by the action of cations with strong polarizing effect (Li⁺, Ba²⁺, Ca²⁺, Mg²⁺) [5, 6]. This leads to a change in the electronic and energy state of anion, the formation of new EASs, and a change in their composition, the rate of EASs formation and charge transfer reactions. Ultimately, this leads to the fact that carbide precursors are reduced at close potentials and conditions for the implementation of the synthesis of carbides in a wide range of current densities are created. 

The paper presents the application of the cation catalysis phenomenon for effecting the HTES of nanoscale tungsten and molybdenum carbide powders in molten salts.

This report presents the results of the studies of the influence of the molten reaction medium composition and electrolysis conditions on the composition, properties and yield of the producing molybdenum and tungsten carbides.

Necessary conditions for the implementation of the high-temperature electrochemical synthesis (HES) of refractory metal carbides in molten salts are the joint or sequential deposition of the corresponding metal and carbon on the cathode surface, that is, respectively, “thermodynamic” or “kinetic” synthesis modes [1]; as well as providing conditions for their interaction with each other. A third synthesis mode is also possible, when one of the synthesis components (carbon or metal) is used as a cathode material. In our work, we implemented the first “thermodynamic” mode of the HES, selected and studied systems and conditions for the electrochemical extraction of refractory metal and carbon from molten salts in a close and narrow range of potentials.

Mixtures of molten halides with oxygen-containing compounds of molybdenum (tungsten) and lithium carbonate were used as the initial reaction medium. Carbon dioxide, located at different partial pressures above the molten electrolyte (from 1 to 15 atm.), was also used as a carbon precursor. The research methods used in our studies are: cyclic voltammetry, galvano- and potentio- static modes of electrolysis, chemical and X-ray phase analyses, scanning and transmission microscopy, Raman spectroscopy, and nitrogen adsorption-desorption method.

Metal and carbon oxyanions ([MO₄]^2-; [CO₃]^2-), their oxides in the highest valence state (MO₃ and CO₂) were used as precursors for the synthesis components (where M = Mo; W). The pointed oxyanions are characterized by the presence of acid-base equilibrium in the electrolyte with the formation of a oxide anion. The latter determines the basicity of the melt. These equilibriums have a great influence on the kinetics and the route of the oxyanion electroreduction. We changed the basicity of the molten medium by introducing oxide ion acceptors - acid additives of various types (cations with a high specific charge, anions with a high affinity for the oxide anion, fluoride anions) into the electrolyte. This approach made it possible to form in situ new electrochemically active particles (ECAP) of metal and carbon, which could be reduced at similar values of their deposition potentials.

We used various acidic additives in our studies (magnesium cations, metaphosphate anions, fluoride anions), which bind oxide ions that are released at the cathode from metal and carbon oxyanions during the discharge, and promote the formation of new ECAPs in the electrolyte: cationized oxyanions of metal and carbon; dimeric metal complexes; fluorine-oxide metal complexes. This made it possible to shift the deposition potentials of metals and carbon to the positive potential region up to 0.5 V and obtain a reduction in the consumption of electrical energy for electrolysis. It should be noted that the introduced acid additives do not participate in the electrode processes. This technique is a good example of the use of electrochemical catalysis to realize sustainable electrochemical synthesis.

Five compositions of electrolytic bathes were studied: (1) Na,K|Cl-Na₂МO₄-MgCl₂-CO₂ (7.5-14 atm.); (2) Na,K|Cl-Na₂МO₄-NaPO₃-CO₂ (5-17 atm.); (3) Na,K|Cl,F-Na₃МO₃F₃-CO₂ (10-17 atm.); (4) Na,K|Cl-Na₂W₂O₇-CO₂ (7.5-12.5 atm.); (5) Na,K|Cl-Na₂W₂O₇-Li₂CO₃-CO₂ (5-12.5 atm.). The good solubility of potassium and sodium chlorides in water simplifies the washing of products from residues of the synthesis medium. For each of the five indicated salt mixtures, the sequence of electrochemical transformations occurring during the electrochemical reduction of oxygen-containing metal and carbon compounds introduced into the electrolytic baths separately or together was studied using cyclic voltammetry; the mechanisms and kinetic features of electrode processes were established; the optimal concentrations of each precursor for the synthesis were determined. The results of electrochemical studies and features of the electrolysis for each mixture of salts are presented in [2–5].

It has been established that the composition and properties of the synthesized carbides are influenced not only by the electrolysis conditions (voltage on the bath, current density, temperature, duration), but also by the ionic composition (qualitative and quantitative) of the initial reaction medium. The highest yield of single-phase stoichiometric metal carbides with minimal specific energy consumption is realized in system (3).

Thus, it was shown that it is possible to change the path and kinetics of the electroreduction reaction of metal and carbon oxy-anions by changing the cationic and anionic composition of the electrolytic bath (thereby forming new ECPs in the reaction medium). This makes it possible to bring together (combine) the deposition potentials of tungsten (molybdenum) and carbon and to carry out the synthesis of both single-phase carbide phases and mixtures based on them with other metals and carbon in a wide range of current densities. 

During the pyrochemical processing of spent nuclear fuel, multicomponent molten mixtures are formed based on the LiCl-KCl eutectic, containing UCl₃, PuCl₃ and a large number of chlorides of elements - fission fragments (CeCl₃, NdCl₃, SrCl₂, BaCl₂, CdCl₂, CsCl, RbCl, etc.). Electrochemical methods are supposed to be used to separate fission products. Therefore, it is important to know the electrical conductivity of such melts. However, obtaining experimental data for many various multicomponent mixtures is practically insurmountable challenge. Therefore, it is necessary to find a way to reliably estimate their electrical conductivity.

To develop a model and semi-empirical method for assessing the electrical conductivity of multicomponent melts of arbitrary composition with good accuracy, a fairly wide base of experimental data is required. To expand this base, we measured the electrical conductivity of a large number of binary, ternary and various multicomponent, including uranium-containing molten mixtures in wide ranges of temperatures and concentrations, using capillary quartz cells with platinum electrodes and the AC-bridge method. The density of such mixtures was estimated and the molar electrical conductivity was calculated. The results are systematized, and some of the results are published in [1–4].

In all cases, the electrical conductivity of molten mixtures increases with increasing temperature. When heavy cations are added to the molten LiCl-KCl eutectic, the formation of complex chloride anions, which are less mobile than individual ions, occurs. This leads to a decrease in the concentration of current carriers Li⁺, K⁺ and, especially, Cl^–, and as a result, a decrease in the electrical conductivity of the melt.

The electrical conductivity of molten mixtures is a highly non-additive property. Its deviations from the additive sum of electrical conductivities of individual components can reach tens of percent. The stronger the interaction in the system, the greater the deviation of the molar electrical conductivity from additivity.

We propose to evaluate the electrical conductivity of multicomponent mixtures as an additive sum of the electrical conductivities of binary mixtures. We have shown that in this case, the electrical conductivities of molten ternary and quaternary mixtures differ from the experimentally found values by no more than 2%, that is, within the experimental error, since deviations from additivity have been already taken into account in binary mixtures analysis. In other words, we bring the multicomponent molten mixture closer to the ideal one by variation of the subsystems (components of the mixture).
 

Electrical conductivity is one of the most important properties required for a competent organization of electrolytic processes in molten salts media; in particular, the processes of the production and refining of metallic hafnium and its separation from zirconium. The separation of zirconium and hafnium is especially important because they have very different thermal neutron capture cross sections: Zr value is ~0.18 barn, Hf value is 115 barns. Both elements are used in nuclear engineering.

Previously, in a series of experimental works, we measured the electrical conductivity of zirconium tetrachloride solutions in various molten alkali metal chlorides [1–5]. In this work, we measured for the first time the electrical conductivity of molten HfCl4 mixtures with a low-melting solvent (LiCl-KCl)eut. A special attention was paid to the purity of the salts used. The measurements were carried out in a capillary-type quartz cell of a special design [4, 5] with a constant within the range of 95.2–91.9 cm^–1. The resistance of the molten mixtures was recorded using an R-5058 AC bridge at a frequency of 10 kHz. The concentration of HfCl4 ranged from 0 to 30 mol.%, and the temperature varied from 780 to1063 K.

With increasing temperature, the values electrical conductivity of molten (LiCl-KCl)_eut.-HfCl₄ mixtures increased from 0.86 to 2.08 S/cm as a result of an increase in the mobility of ions (simple and complex) and a decrease in the viscosity of the melt. As the HfCl4 concentration increased, the electrical conductivity decreased.

A molecular melt of pure hafnium tetrachloride, consisting of HfCl₄ and Hf₂Cl₈ molecules, has a high saturated vapor pressure (45-60 atm) and a very low electrical conductivity (5-7)∙10^-6 S/cm [6]. When interacting with molten alkali metal chlorides, HfCl₄ molecules are ionized and form strong complex anions HfCl₆^2- that displace alkali cations into the second coordination sphere. When the HfCl₄ concentration increased to 33 mol. %, the concentration of relatively weakly mobile complex groups HfCl₆^2- increased. These groups contain 6 chlorine anions and are quite firmly bound to the four-charged metal. The concentrations of the main current carriers: Li⁺, K⁺ and especially mobile Cl- anions decreased more and more. This led to a decrease in the electrical conductivity of the melts. The previously studied molten (LiCl-KCl)-ZrCl₄ mixture illustrated a smaller decrease in the electrical conductivity at the increase in the tetrachloride concentration as opposed to the hafnium-containing mixtures. This indicates a lower strength of the ZrCl₆^2- complexes compared to HfCl₆^2- complexes.
 

The changes in the saturated vapor composition and the volatility of the components of molten mixtures of uranium and some other metal tetrachlorides (ThCl4, HfCl4, ZrCl4, TiCl4) with alkali metal chlorides as functions of the temperature, concentration and cationic composition of the melts are discussed using our experimental data and those obtained by other researchers, mainly employees of the Institute of High-Temperature Electrochemistry (Ural Branch, Russian Academy of Sciences).

Like many other high-valence chemical elements, tetravalent uranium acts as a powerful complexing agent in molten alkali metal chlorides; hence, its dissolution is accompanied by substantial rearrangements of bonds of particles leading to the formation of stable complex anions: MeCl_7^(3-), MeCl_6^(2-), Me_2 Cl_10^(2-) (Me - U, Th) and MeCl_6^(2-) (Me - Hf, Zr, Ti) at the concentrations up to 50 or 33 mol % MeCl4, respectively. The complex formation is manifested as a sharp decrease in the saturated vapor pressure of the components of the molten mixtures due to which not only uranium tetrachloride but also such volatile compounds as ThCl4, HfCl4, ZrCl4, and TiCl4 are retained in solutions even at high temperatures. The strength of complex anions increases with decreasing temperature and concentration of the corresponding tetrachloride and under the counterpolarizing action of alkaline cations in the series from Li+ to Cs+ on chlorine anions in the complex chloride groups. As a result, the volatilities of UCl4, ThCl4, HfCl4, ZrCl4, andTiCl4 and the composition of vapors above the solutions in the ionic melts vary over broad ranges.

A decrease in the volatility of tetrachloride results in a decrease in its content in the saturated vapors over the melts. Hafnium, zirconium, and titanium tetrachlorides (especially TiCl4) are significantly more volatile in the individual state than UCl4 andThCl4 and have higher volatilities and contents in the saturated vapors over the solutions in molten alkali metal chlorides. The vapor over solutions in molten metal chlorides of titanium tetrachloride, which has the highest volatility among the considered tetrachlorides, almost completely consists of its molecules only. 

The temperature, concentration, and composition dependences of the saturated vapor pressures and volatilities of the components of solutions of uranium, thorium, hafnium, zirconium, and titanium tetrachlorides can be used as reference material for the organization of diverse pyrometallurgical and pyrochemical (e.g. electrolytic) processes based on salt melts.
 

Chlorine gas is one of the most important reagent and product of many chemical reactions and technological processes involving molten salts, it is also often used in organic chemistry and photochemistry. Data on the optical spectroscopy of gaseous chlorine obtained over a wide temperature range provide additional information about the properties of chlorine and its reactivity.
Electronic absorption spectra (EAS) of chlorine gas were recorded in the range of 8333÷50000 cm-1 (200÷1200 nm). The spectrum consists of a single broad absorption band located mainly in the range 20000÷43500 cm-1 (230÷500 nm). There is no absorption in the range of 500÷1200 nm. The spectra were recorded in the temperature range from 0 to 1000°C approximately every 100 degrees. 

With increasing temperature, the optical density of the absorption band decreases, and the position of the maximum shifts slightly (~ 1 nm per 100 degrees) to the short wavelength region [1]. The shape of the absorption band does not change significantly, although there is a tendency to the band broadening with increasing temperature. As the temperature rises, gaseous chlorine expands and fewer chlorine molecules enter the light beam. To compensate the influence of density change, all further considerations will be carried out in extinction units , dm2/mol.
If the parameters of the potential curves, between which electronic-vibrational transitions occur, are specified, then the question arises what transitions will be more likely and what transitions will be less likely. The excitation of the Cl2 molecule (20277 cm-1) is caused by the transition from the ground state X^1 ∑_g^+▒Cl_2 to the antibonding 1ПuCl2 state [2], which is accompanied by the dissociation of the molecule. Unlike an atom, a molecule consists of two connected subsystems; these subsystems move at significantly different speeds. The set of electrons is a fast subsystem, the set of nuclei is a slow one. Thus, in the process of electronic-vibrational transitions, the molecule finds itself in an excited electronic state at the same value of the internuclear distance r, in which it was caught in the act of absorption. Halogen molecules represent a rare case where r* r. It is obvious that in this case the most probable transitions (v=0  v*=n) are accompanied by a significant increase in the reserve of vibrational energy, and the high-frequency edge of the electronic-vibrational spectrum can become continuous, which corresponds to transitions in the section of the upper potential curve lying above the dissociation boundary. Under such conditions, the chlorine molecule dissociates as a result of a significant relative shift of the stable functions U(r) along the r axis rather than due to a transition to an unstable potential curve. 
In the early 1950s, Sulzer and Wieland [3] proposed an equation describing the temperature dependence of extinction in the Franck-Condon approximation, which, however, did not describe the temperature shift of the absorption band maximum. Later, Golovitsky and Mikhailov [4] proposed an amendment that takes into account the displacement of the maximum with increasing temperature. This shift is apparently a consequence of the manifestation of anharmonic vibrations of the diatomic chlorine molecule [5].
 

In various technological processes using molten salts, molecular chlorine is released or absorbed. When conducting scientific research involving melts, there are often cases, in which an oxidizing atmosphere of chlorine is necessary, or chlorine is a reaction product. This raises the question concerning the mechanism of chlorine solubility and its influence on the processes being studied. Thus, the purpose of this work is to establish the mechanism of chlorine dissolution in molten alkali metal chlorides.
The purpose of this work is to establish the mechanism of chlorine dissolution in molten alkali metal chlorides.
Electronic absorption spectra of saturated chlorine solutions in molten NaCl, NaCl - KCl, KCl, CsCl were recorded in the temperature range from the melting point of salt to 1000 °C with an interval of approximately one hundred degrees. The work was carried out using an SF-26 spectrophotometer (Russia) adapted for operation with high-temperature melts.
In all salts studied, the long-wavelength edge of the absorption band was reliably detected. With increasing temperature, this absorption edge shifted to longer wavelengths in all chlorides. For sodium chloride and an equimolar mixture of sodium and potassium chlorides, it was possible to record a wide plateau with a maximum shifted to the region of higher energies compared to the absorption maximum of chlorine gas. For the other salts, the maximum could not be recorded; this is due to the large absorption of the salt - solvent.
From the data [1 - 7] it is known that the solubility of chlorine in the studied melts is several mole percent. This is significantly higher than the solubility of inert gases, so it is reasonable to assume that the simplest type of polyhalide compounds Cl₃^- is formed in the melt. In addition, we have established a shift in the position of the maximum of the chlorine band in the melt to the high-frequency region [8]. This shift confirms the formation of Cl₃^- complexes in the melt.
In accordance with the theory of molecular orbitals, the sharing of valence electrons in such a complex leads to the formation of axial three-center molecular orbitals. Filling them with electrons in accordance with the principle of minimum energy ensures the stability of such a group of atoms. The stability of such particles at high temperatures can probably be explained by the fact that the anions of the molten salt are not solvated and have high activity.
On the other hand, the close coincidence of the maxima in molten salts with the maximum absorption of chlorine gas, as well as a slight shift of the maximum and an increase in solubility with temperature, allow us to draw a conclusion about the predominant inert gas mechanism of chlorine dissolution. Based on the data presented, it can be concluded that both physical dissolution and chemical interaction with the formation of particles of the Cl₃^- type take place.
 

Electronic absorption spectra (EAS) of rare earth ions in melts are scantily known. Since 4f electrons spend most of their time very near the nucleus, thee are well shielded by all the other electrons of a lanthanide ion from the influence of the crystalline fields of surrounding ligands. This circumstance, coupled with the fact that the spin-orbit interaction is about ten times larger for 4f than 3d electrons, makes the spectra of 4f ions much less sensitive to environmental changes than those of d-ions. However, spectra of the several 4f-cations (Ce(III), Pr(III), Tb(III)) contain not only orbitally-forbidden f↔f transitions, but also 4fⁿ↔4f^n-15d¹ allowed ones. These transitions are almost unexplored. Only very scant data on Ce(III) available [1].

EAS of CeCl₃ and TbCl₃ dilute solutions was recorded in molten NaCl, NaCl-KCl (1:1), KCl and CsCl over the range 40000 to 8000 cm^-1. Quartz 2 mm pathlength cells were used for measurements, temperature region was from 700 (800) up to 1000 ⁰C. Concentrations were about 0.005 mol/l (near 0.03 mol %) in case of CeCl₃ and essentially higher ~0.5 mol/l (~2 mol %) for TbCl₃. By way of example EAS of CeCl₃ and TbCl₃ in molten NaCl-KCl consist of one weakly asymmetrical band with maximum near 31000 and 37000 cm^-1 respectively. This band is 2 to 3 times narrower than the electron-transfer bands. In contrast to f↔f transitions intensity of these bands diminishes as temperature is rises, and rises in the row of the solvents from NaCl to CsCl. However, oscillator strength reduces only slightly with essential increasing of temperature. These changes are result of surroundings influence upon d-sublevel only. By mathematical analysis it was shown band observed consists of two ones. All available data are well compatible with octahedral melt structure – CeCl₆^3- and TbCl₆^3- complex formation.

Acetamide has a valuable combination of properties which are only beginning to be recognized. Besides low cost and many convenient physical properties, it is also highly polar and has an enthalpy of fusion comparable to that of many inorganic salts which makes it a potential phase change heat storage material. Moreover, in the molten phase it is an excellent solvent for both organics and, particularly, for many inorganic salts. Acetamide melts have found applications as electrolytes for electrochemical treatment of metals [1, 2]. The possibility of electrochemical synthesis of refractory compounds from acetamide melts at 120°С has been examined for Ti-B as an example. In the binary system CH₃CONH₂–(NH₄)₂TiF₆ a new process, which is more electropositive than the decomposition of acetamide and more electronegative than the acetamide discharge has been observed. The scan rate independence of potential characterizes the observed processes as reversible charge transfer. This process corresponds to the one-electron irreversible charge exchange: Ti(IV)/Ti(III). In the binary system CH₃CONH₂–NH₄BF₄ only the decomposition of carbamide has been observed. In the ternary system CH₃CONH₂–(NH₄)₂TiF₆–NH₄BF₄ a new process, which is more electropositive than the decomposition of acetamide and more electronegative than the one-electron charge exchange: Ti(IV)/Ti(III) has been observed. This process corresponds to the electrochemical synthesis of Ti-B compound. Ultra thin coatings of titanium boride have been obtained on nickel by the electrolysis from a CH₃CONH₂–(NH₄)₂TiF₆–NH₄BF₄ melt at 120°C at current densities of 10-20 mA/cm².