The lack of Ethics in the academic world is a serious problem. The criticism of Jonathan Swift in Gulliver Travels (1726), is still valid [1]. In this sense, we remain in middle age. This is not the only obsolete thing nowadays: In the year 2000, The Roman Right of Roman Emperors is still used. Arminius revolt [2] was against the Roman code of laws, essentially. Maybe what makes the Roman ridiculous is the punishment system: jail for everything. The time of jail varies since 1-2 days to entire life. Also signing a confession (even if innocent) may result in condemnation.

Criticizing the authorities is always a risky task: Galileu Galilei was incarcerated for defending that the Earth orbits the Sun (and not the inverse). To avoid trouble, Copernicus asked to have his book published after his death. Criticizing “authorities” always is a risky task, because then “authorities” are no longer “authorities” and lose their political power, money and other assets.

In the 20^th Century Cecilia Payne was forced to change her conclusions in her PHD Thesis [3]. No Nobel Prize to her! By another hand, influential people are able to publish wrong papers. Everett was advised by John Weller [4], a very influential figure in the politics of Physics. Thus, the Many World hypothesis [4] was published (but it obviously violates the principle of conservation of energy!). Such absurd papers are published and can receive large number of citations. By another hand, Oliver Heaviside also almost was banned from scientific life [5]. No Nobel Prize for him!

There are Lobby for some authors. Thus, be careful about “invited papers”, which may even admit completely wrong ideas! The two more relevant corrupt issues are the “networking” and the Ponzi scheme. Correct papers are rejected, whereas wrong papers are accepted and even published several times. Editors and Referees are “rigorous” with some authors, and lenient with others. The Ponzi (or pyramid) scheme makes that the PHD candidate always have to confirm the thesis of the advisor. 

Here it is discussed on how we can escape from such corrupt system. The Fourier series were presented in 1807, but Poisson, Legendre and others denied its publication [6]. Soon after Fourier published a book (by his own) in 1822, Fourier was elected for the Royal Society [7]  (but 15 years were missed)! Conclusion: The soapbox oratory is the ultimate solution [8].

Nowadays, sustainability and good use of resources and waste are necessary. So, this work seeks to synthesize a ceramic material from natural waste, as well as its characterization and biological evaluation after all the steps that anticipate in vivo application. In this way, brushite, which is a dihydrate dicalcium phosphate mineral that is a calcium phosphate present in the natural mineralization of tissues, can be obtained synthetically from chicken eggshells. It is used as a biomaterial for different applications such as medical treatment, especially orthopedic treatment and bone repair, agrobiological inorganic fertilizers. Brushite has the property of adsorbing ions and changing its active sites with calcium, such as Zn and Ag ions, which can enhance the biocompatible and bactericidal potential of the biomaterial, respectively. In this work, we started with the synthesis of bruxite nanopowders (previously performed) that was characterization by microscopy and physical-chemistry analysis (MEV-topography, MET-nanoscale, FTIR-chemistry-group, XRD Rietveld- material identity). The cytotoxicity was then tested by in vitro microbiological analysis in a nutrient medium using 3 species of bacteria was made ISO-10993-5- ceramic tests. The results shows that was possible to obtain bruxite through the results of chemical-physical characterization and the initial results in vitro indicate that it is a biocompatible nanoceramic. 

Thanks to Faperj 203.409/2023 - SEl-260003/016585/2023 for supporting the research, to CAPES, CNPQ and to the student Ronald Palandi Cardoso for helping with the cultivation of microorganisms and to Prof. Yutao Xing for helping with the MET analysis.

With the green hydrogen starting at 4.45  US$/kg, [1] hydrogen usage seems difficult. Not only the green hydrogen is very expensive, even the gray hydrogen is uneconomical. However, hydrogen production is a possibility when there is oversupply of electric energy.

In California, renewables as solar and wind already able to provide almost 100% of the energy, avoiding fossil fuels as coal and natural gas [2]. Both windy days or sunny days offer the possibility of in-excess production of energy [2], which can be employed for cheap hydrogen production.

Usually, DRI – Direct Reduction of Iron – request high quality iron ore [3], offering a possibility for Brazil in this market. Vale is considering a hub for HBI (hot briquetted iron) in Porto do Açu in Brazil [4]. Other possible hubs are planned for Saudi Arabia, Oman and Dubai, due to the possibility of cheap natural gas [5].

This study addresses economic issues of hydrogen usage in steelmaking.

Although the denomination “steelmaking” is much more  common in English, the world “siderurgy”  also exists in English. The name “siderurgy” comes from the old Greek world for iron: sideros. Steelmaking and Ironmaking revolutionized the history of humankind: There are distincts quality of life for the 4 main hystorical ages: stone age, copper age [1], bronze age, and iron age. 

Nowadays it became clear that the Old Egyptians were less advanced in metallurgy - or ironmaking - than their neighbors: The Tut-ankh-amon dagger is  meteoritic (due to high nickel) and, besides, it probably was imported from Mittani or Hittite lands [2], thats is, present day Turkey .

The transition of bronze to iron and steel was very important for quality of life: In the iron age, furniture could be easily  manufactured, and also ships and boats. This revolutionized the commerce. Bronze was very expensive due to the scarce and essential alloying element  tin (11-12% in bronze). Instead, iron ore can be found almost everywhere.

It is reviewed the complex process that gave origin to smelting [3,4], for steel and iron production:  Magnetite maybe the first ore used for reduction. The origin of first smelting techniques are still uncertain [5]. More and more it became clear that Black Sea regions started the iron smelting process, possibly in areas related to the Chalybes [6], near present day Trebzon.

The present study investigates the advantages and feasibility of the shaft furnace in direct reduction processes, highlighting its energy efficiency and flexibility in the choice of reducing agents. The complexity of the processes involved within the furnace is addressed, dividing it into four distinct zones. Although mathematical models have been developed to predict direct reduction, their application is limited due to the simplification required in the face of the complexity of the phenomena. The integration of the shaft furnace with partial replacement of the charge by self-reducing pellets is explored, demonstrating a potential increase in process efficiency and reduction in CO₂ emissions. This study proposes a multiphase and multicomponent mathematical model to predict the internal temperature distribution of the furnace, validated by simulations on an industrial scale. The results indicate a significant increase in productivity and metalization when using self-reducing pellets, as well as, a reduction in carbon emissions when partially replacing conventional reducing gas with hydrogen. The findings highlight the importance of optimizing operational parameters to maximize the benefits of the shaft furnace in direct iron production.

This study investigates the potential of combined injection of hydrogen as fuel and pulverized charcoal (PCH) in the operation of blast furnaces, aiming to reduce carbon emissions and increase energy efficiency. Through a detailed computational model, we analyzed various operational scenarios with different rates of PCH and hydrogen injection. The results demonstrate that the partial or total replacement of pulverized coal (PC) with PCH can significantly increase blast furnace productivity, reducing coke consumption and carbon emissions. An improvement in internal material distribution and temperature was also observed, with an acceleration in burden descent and a modification in the temperature pattern in the raceway region. Furthermore, it was found that progressive increases in PCH and hydrogen injection can lead to substantial increases in blast furnace productivity, with additional reductions in coke consumption and carbon emissions. These results highlight the potential of combined hydrogen and PCH injection as a viable strategy to promote sustainability and efficiency in the steel industry, aligned with decarbonization and circular economy objectives.

In 1926, Vito Volterra presented the Pray-Predator model to evalute the effect of time on the population of species [1].

In mathematics, the Lotka-Volterra equations are a couple of first-order, nonlinear, differential equations, which can be used for describing chaotic systems.   Lotka-Volterra equations are typically  used for describing the dynamics of biological systems, when two species interact: one as prey and the other as predator.

The model can be used to evalute the economy. The idea of Adam Smith of the “Invisible hand” [2] is completely wrong.

Unfortunately, Adam Smith reasoning has dominated the economy for centuries, maybe.

Here it is shown that some economic crisis [3], as 1929 [4] and 1987 [ 5], may have been origin on the excess of capital.

The reasoning presented here can be used to understand variations of  price of commodities, as discussed previously [6].

Thus “bubbles” in economy [7] can be predicted, thus mitigating the nephast effect of possible stock market crisis. The Lotke -Volterra equations [8] can be used for the prediction of such “bubbles”.

The present situation of the market and applications of rare-earths is reviewed. It is given special attention for discussing the possibility of substitution of  rare-earth magnets by other families of magnets.

Three are the main commercial applications of rare-earths: i) luminescent phosphors, ii) magnets, and iii) catalysis.

For catalysis, the cheap rare-earths as cerium and lanthanum are employed.  Luminescent phosphors are essential in many applications, as lasers and, for example, erbium is used in optical fibers. However, in spite of its relevance, erbium is not expensive as Tb and Dy. 

In LED applications, the rare-earths are used as thin films, and , thus the demand in volume  is not very significant when compared with the demand for magnets. The use of white LED (light emission diode) significantly reduced the demand for europium after 2015, but this application is still relevant. In the 1960s and up the 1980s, Europium was the most expensive rare-earth, due to extreme demand.

The rare-earth market is nowadays driven by Tb, Dy, Nd and Pr, which are employed in rare-earth iron permanent magnets of the RE2Fe14B family (RE=rare earth). For applications in high temperature, dysprosium and terbium are added, and this made the demand and price of Dy and Tb be skyrocketing.

SmCo magnets have the problem of using the expensive element cobalt. Nowadays the demand and price of cobalt increased conbseiderably due to application in rechargeable battteries, and thus, SmCo use in large scale is avoided, but they remain relevant for high temperature applications (above 150oC).

Possible alternatives for rare-earth  permanents magnets are discussed. Among the few options for replacement are the ferrite magnets (BaFe12O19 or SrFe12O19), the Alnico magnes based on shape anisotropy and maybe iron nitrogen. Economic and technical feasibility of these families of magnets are discussed.

Its is given a brief overview about recent mining projects in Brazil, which are focusing on ionic clays, with the objective of extracting the scarce and expensive elements terbium and dysprosium. 

It was recently presented a model [1-3] able to predict the magnetic anisotropy of any sample, This is called the "Simultanoeus Fitting Method" SFM.

According the SFM method, the magnetic anisotropy can be determined, since magnetic measurements are performed at the  (_|_) perpendicular and (//) parallel directions (relative to the alignment direction). The method assumes samples with alignment in one preferential direction, thus with uniaxial anisotropy. This kind of anisotropy is typically found in samples prepared by powder metallurgy, where the alignbment is obtained by applying magnetic fields in grains with single domain size. 

Using the SFM, the crystallographic texture of samples can be determined directly from magnetic measurements, avoiding complicated, laborious and expensive techniques as EBSD - Electron BackSacterred Diffraction.

A symmetrical distribution as for example the Gaussian, is used for describing the crystallographic texture.

Other distribution functions can also be used, since they are symmetrical. This includes Cauchy -Lorentz, Voigt and Pearson VII as possibilities.

It is experimentally found that f=cos(theta)^n or Gaussian distributions describe very well the texture of the samples.

The model allows the re-evaluation of experimental data. Here it is discussed how to apply the model in very different samples.

These samples are SmFeN (magnetocrystalline anisotropy), Alnico, (shape anisotropy [4,5]) and cobalt-needle samples.

In cobalt needle samples the shape anisotropy and the magnetocrystalline anisotropy may have the same order of magnitude.

It is discussed the question of dominant anisotropy.

When considering nanocrystalline structures, we are near the microscopic world.

What is the difference between the macro and micro world?

The difference is subtle. For atoms, the macrosocopic world holds, and atoms can be assumed as rigid spheres. In metals this is expressed by a nucleus surrounded by a cloud of electrons.

Inside the atom, the electrons spin the nucleus, in a perpetuum motion. By another hand, in the macroscopic  world, perpetuum motion does not exist (due to friction, for example).

Here, different philosophical approaches of quantum mechanics are discussed, as the Bohmian mechanics, the Bohr interpretation (Kopenhagen) and also the Everett many-worlds hypothesis.

Instead of a “many worlds”, it seems clear that the correct interpretation would be the “many paths”, in agreement with Feynman view.

Experiments have in general confirmed the Bohr interpretation, thus rulling out the Bohmian mechanics

Also by using the Kopenhagen interpretation, the Heisenberg uncertainty principle can be reinterpreted,  showing that time is not absolute.

Also, it will be discussed that as the electron has to be defined using 5 variables (3 dimensions, spin and time) [1], it will be argued that in the microscopic world there are extra dimensions, which we can not observe in the macroscopic world. (In the macro world, we see 4 dimensions: (x,y,z time))  

The concept of Flatland, as exposed in Carl Sagan Cosmos [2] will be used to clarify the different philosophical interpretations of quantum mechanics.

The hysteresis curves of a material are capable of showing the relationship between the magnetization and the applied magnetic field. These curves are crucial to understanding the magnetic properties of ferrites, which are widely used in electronic applications, such as transformers and inductors. In this work, hysteresis curves of barium and strontium ferrites, in varying proportions, were adjusted using the Hyperbolic Tangent Model. This model demonstrated a good capacity for adjusting the observed hysteresis curves, which present a characteristic sigmoidal aspect. The parameters obtained from the adjustment allowed a better understanding of the physical and magnetic properties of the analyzed samples. The Hyperbolic Tangent Model proved to be effective not only due to the high correlation coefficient achieved, but also due to its ability to reflect the nuances of the magnetic properties under different conditions. The results obtained may have significant implications for the application of these ferrites in magnetic and electronic devices, since understanding their fundamental properties is crucial to optimizing the performance of these materials in different contexts. In short, the work highlights the importance of mathematical modeling as a tool for elucidating the magnetic characteristics of barium and strontium ferrites. The results suggest that the Hyperbolic Tangent Model is a promising approach for future investigations into magnetic materials consisting of ferrites.

In the ancient time, the resources were very limited. Thus ancient people learned to use ocean currents and wind in their travels. It was a sustainable process, which lasted many centuries. 

There are several examples that may be usefull for the present time.

Wind can push the ships at a significant speed. For example:

Launched in 1869,  the  tea clipper Cutty Sark  was very famous due to its velocity. The Cutty Sark could reach 17.5 knots [1], and it was considerable one of the fastest ships of the XIX Century, however it was made obsolete by steam engines. 

When the Portuguese explored the South Atlantic ocean [2,3], they found that currents pushed them from Africa, and made them arriving in Brazil.

There are also indications that Portuguese also visited North-America, and the names “Newfoundland”  is translation of the Portuguese “Terra Nova”, and “Labrador” comes directly from the Portuguese name “Lavrador” [4]. The Hamy-King worldmap shows the presence fo Portuguese in North-America near the year of 1500.

Wind and ocean currents were very relevant in Ancient world, as also earlier reported by Homer.

For example, the Odyssey of Homer may, in fact, indicate a  travel to the Ballearic Isands, by means of South France ocean currents. For example, the island of Calypso “Ogygya” in fact can be interpreted as  Ibiza.

The war for Troy is due to the fact that, there is a 5 knot current flowing from the Dardanellos to the Agean Sea. Only in summer this strong current could be overcome by wind [6], and only during few days. The Trojans used to ask tribute and mooring fees [6], making the Greeks discontent. In fact, almost every year there as a war in Troy (and in summer time).

These ancient voyages only were possible due to competent use of wind and ocean currents. 

It is discussed how the competent knowledge of wind and ocean currents could be used nowadays for saving fuel in navigation.

The most used textbooks in the area of magnetic materials remain Chikazumi [1] and its north-american counterpart, Cullity [2].

Even these books are essentially correct, there are some needed corrections, also because these books are more than 50 years old, and some advances happened in this period. Some necessary corrections and amendments have been discussed in recent papers [3,4,5].

The most relevant correction is the description of exchange energy term, and also the nature and structure of the domain wall. The Bloch wall [6] is wrong . As consequence, there is no magnetic reversal by curling, which also has to be removed from textbooks [4].

The concept of heat in energy losses has also been discussed recently, and also the nature of the dissipative processes in a hysteresis cycle [5]. 

The Jiles-Atherton model lacks physical basis [7]. The hysteresis can be interpreted geometrically, as discussed recently [7].  The origin of Magnetic Barkhausen Noise has also  been clarified recently [8].

Coercivity mechanism in Sm-Co magnets of the 2:17 type were clarified [9], and should be inserted in the textbooks.

Stirling machines have been always extensively studied. NASA has suggested Stirling machines for applications is spacecraft [1].Ford considered the Stirling machines for common passenger cars in early 1970s [2]. Stirling machines have been considered a possibility for moving submarines [3]. Many studies considered Stirling machines in connection with solar power [4]. However, with the reduction of the price of solar panels along the last decade,  photovoltaic solar energy became very cheap. At the present time, the cheaper options of energy are onshore wind and photovoltaic solar [5]. 

Another interesting option is given by Stirling machines: As they work on basis of difference of temperature, by preserving the cold of the night and the heat of day, Stirling machines can be activated, thus producing electricity. This enables the application of Stirling machines in homes. For example, small Stirling machines can be used for charging rechargeable batteries (and cell phones), among other applications.