Preliminary List of Abstracts (Alphabetical Order)

1ST INTL. SYMP. ON COMPOSITE, CERAMIC AND NANO MATERIALS PROCESSING, CHARACTERIZATION AND APPLICATIONS SYMPOSIUM

Core-shell microcapsules were generated using a polymer-induced liquid-precursor (PILP) mineralization process to deposit a calcium carbonate (CaCO3) mineral shell on the surface of surfactant-stabilized fluidic particles comprised of either oil-in-water emulsion droplets or liposomes. Morphological analyses were performed by various microscopic techniques, where it was observed that PILP droplets preferentially adsorb to anionic surfactants/lipids that stabilize the suspension, and due to their liquid-like character, coalesce to form a smooth and continuous mineral coating. The processing conditions for forming these CaCO3-coated microcapsules are benign, and they can virtually encapsulate any active agent of interest. Hydrophobic compounds, for example, can be dissolved in oil-in-water emulsions, while hydrophilic and/or hydrophobic compounds can be dissolved within liposomes, which can then be coated with the mineral shell. Confocal microscopy was used to demonstrate an oil-soluble fluorescent dye is encapsulated in the interior of the emulsion, or both hydrophilic and hydrophobic compounds are incorporated with the aqueous and hydrocarbon regions of liposomes, respectively. The metastable morphology of the CaCO3 shell enables a pH dependent degradation of the particles, allowing the release of the active agent of interest. These CaCO3-coated microcapsules can be dried down to a powder, while retaining the fluidic core, which could save in storage and transportation expenses because the large solution phase of the suspension is removed. We believe that these core-shell particles have a myriad of potential applications because of their inherent environmentally-benign composition and biocompatibility. Core-shell microcapsules, for example, could be used in environmental applications, such as release of pesticide or fertilizer, in chemical reactions, such as release of catalyst of specific reagents, in hair/skin care products for release of conditioner or other compounds, in health care for release of pharmaceutics, or in self-healing composites for release of a sealant capsule fracture.

Bone is a hierarchical composite which, at the nanostructural level, consists of an assembly of collagen fibrils that are embedded with uniaxially-aligned nanocrystals of hydroxyapatite. Our studies have revealed that this nanostructure can be reproduced in vitro using a polymer-induced liquid-precursor (PILP) mineralization process. The polymeric additive consists of acidic polypeptides (e.g. Polyaspartic acidic) or proteins (e.g. Osteopontin) that can mimic the action of non-collagenous proteins found in bone. The high charge density of the polyanionic additive sequesters ions so that liquid-liquid phase separation occurs, forming nanodroplets of a hydrated amorphous mineral precursor. The infiltration of nanodroplets into the collagen fibrils leads to intrafibrillar mineral, which is the foundation of bone nanostructure. We have put forth a (controversial) hypothesis regarding the mechanism of intrafibrillar mineralization, which proposes that a liquid-phase amorphous precursor induced by the polypeptide can be drawn into the gaps and grooves of collagen fibrils by capillary action, which upon solidification and crystallization, leads to an interpenetrating organic-inorganic composite with bone-like nanostructure. Through reaction parameters optimization, bone compositions matching (60-70wt% mineral) have been achieved in various types of collagen scaffolds. Biogenic collagen matrices can also be mineralized by this process, such as rat tail tendon and demineralized bone; However, there are currently limitations in the depth of penetration that can be attained in these dense scaffolds. Therefore, our current studies are directed at assembling parallel-fibered collagen which can be mineralized in the form of laminated composites, mimicking the lamellar microstructure of bone. Through cell signaling mechanisms provided by the osteopontin additive, the potential for modulating osteoclast resorption of these bone-like composites might be achieved. The long range goal of these studies is using this model system to understand bone formation and pathologies, and from applications perspective, preparing bioresorbable load-bearing bone substitutes.

Olivine structured LiMPO4 (M = Fe, Mn, Co & Ni) nano particles are potential cathode materials for high power Li-ion batteries (>4V: Li+/Li). Unfortunately, LiMPO4 has low intrinsic electronic and ionic conductivity due to defect association effects, which have a strong impact on its transport properties [1].In order to overcome the mentioned associated problems, several synthesis methods have been devised. Thus, nano size structured materials with different shapes were developed followed by surface engineering with electronically conducting materials like carbon, etc. Several literature reports on pure and different carbon additives coated over LiMPO4 (M = Fe, Mn, etc.) nano particles showed significant improvement in their electrical and electrochemical properties [2-4]. Therefore, the present work is aimed to study the PVP assisted polyol and resin coating processes to produce pure and carbon coated LiMPO4 (M= Co & Ni) nanoparticles, referred as LiNiPO4/C & LiNiPO4/C, subject to characterization by XRD, SEM, TEM-EDS and Impedance spectroscopy techniques. The detailed results will be presented and discussed.

This work describes the obtaining of silicon nitride, a ceramic powder for advanced ceramics, starting from mesoporous silica, which is obtained by acidic attack of serpentinite rocks. Serpentinite rocks come from the heaps resulted from the former exploitation of asbestos in the South West of Romania. The mesoporous silica was used as a host for the polymerization of acrylonitrile in order to obtain hybrid inorganic-organic polymer nanocomposites. The hybrid nanocomposites were turned into silicon nitride by 3 subsequent thermal treatments in controlled atmosphere. The chemical and structural changes during the preparation process of Si3N4 starting from serpentinite were followed by FTIR, BET, XPS, GPC, SEM, TEM, XRD, TGA-DTG and by chemical analytical methods.

The acoustic emission (AE) method, in conjunction with the dielectric measurements, has been used to study phase transitions in numerous ceramic and single crystalline relaxor ferroelectrics, such as the prototypical Pb(Zn1/3Nb2/3)O3 and Pb(Mg1/3Nb2/3)O3 perovskite compounds and their solid solutions with PbTiO3. Common features related to the critical conditions responsible for the giant piezoelectric and electromechanical responses in all relaxor systems have been studied. The extraordinary properties have been revealed at critical points in the X-T-E (composition-temperature-electric field) phase diagrams of the compounds studied, being related to the existence polar nanoregions (PNRs). We have found that the critical electric fields in relaxor ferroelectrics correspond to maximal AE activity at minimum values of the diffuse thermal dielectric permittivity peaks. A combined investigation of the critical phenomena comprising the AE, dielectric spectroscopy, in situ Raman scattering and time-resolved synchrotron XRD structural analysis has been carried out to the origin of the giant piezoelectricitiy. The primary types and driving mechanisms behind the PNR atomic clustering associated with the critical behavior have been revealed. Some applications of relaxor ferroelectrics as candidate materials for broadband and high-sensitivity ultrasonic transducers and sensors is discussed as well.

Two different alumina and silica sources were used to synthesize faujasite zeolite by hydrothermal treatment. In the conventional synthesis (CS), sodium aluminate and sodium silicate were used. A gel was prepared using NaOH and the crystallization was carried out at 90°C for different periods of time. A second synthesis (RS) was performed using a raw material called fly ash; It was mixed with NaOH and submitted to heat treatment at 600°C, for 2 h. Subsequently, it was submitted at ageing step and then crystallization was performed at 90°C. Samples were collected at different periods of time and they were characterized by XRD, SEM, XRF and FT-IR. The results for CS synthesis indicated the amorphous phase persists after 4h of crystallization. The faujasite zeolite appeared after six hours, and the crystalline phase after 8 h. For RS synthesis silicate and aluminate species were detected after the heat treatment. After two hours of crystallization, the P zeolite was formed, the faujasite zeolite was detected after 6 h together to P zeolite; Eight hours later the faujasite zeolite was the unique crystalline phase. This behavior indicated the metastability of zeolites. P zeolite goes through a dissolution process led to a rearrangement in T-O bonds, generating a different structure, the faujasite. Variation in the contents of Si, Al and Na were observed in the samples of the two synthesis routes. Evidences of building structure units (BSU) of zeolite were found by FT-IR. For RS synthesis, single and double rings were formed during the first 4 hours of crystallization corresponding to BSU of P zeolite structure, while vibrations of the double 6-members rings were observed after 6 h, en both CS and RS synthesis. These results showed the nature of silica and alumina sources is a crucial parameter in the zeolites crystallization process.

Bio-resorbable composite has gained tremendous interest in the field of biomaterials research. Ionizing radiation offers unique advantages for the modification of polymers for biomedical applications. In the present study, bioactive and biodegradable polymers chitosan and gelatin were used to prepare bio-absorbable composite film through solution casting process followed by UV irradiation with different dose strength. 2-hydroxyethyl methacrylate (HEMA) was used as a cross-linking monomer and phosphate glass (PG) as a reinforcement filler. The composite films were obtained by diluting gelatin (G), phosphate glass (PG) and HEMA with G: PG ratio of 88:12 wt%, G: HEMA ratio of 50:50 wt% and G: PG: HEMA ratio of 44:12:44 wt% in hot water. Incorporation of PG improved the mechanical properties of the composite films. Stereo microscope analysis revealed the porous nature of UV irradiated composite film. The chitosan film was prepared in 2% acetic acid solution and the prepared film was soaked into HEMA monomer containing methanol solvent and photo initiator for various time span to investigate the monomer concentration, soaking time and solvent effect on the performance of chitosan film. UV radiation was employed to induce cross-linking and photo-grafting. The evidence of cross-linking and grafting was provided by Fourier Transform Infrared Spectroscopy. The results regarding monomer and solvent concentration as well as UV dose intensity on the yield of cross-linking were presented in terms of polymer loading, mechanical performance, water absorbance and thermal stability. The prepared composite films can have a potential use in biomedical application both in drug delivery and tissue engineering.

Nanostructured metals are of interest because of their unique physical and mechanical properties of high strength, creep resistance and aims towards potential use in a variety of applications. Ball milling at cryogenic temperatures (Cryo-milling) is more effective in this capacity due to the low temperature by slow-recovery, cold welding and minimizing diffusion distances between powder particles. Its low energy ball milling process produces nanostructures in metal powders through severe repetitive deformation. Powder with a particle size less than 40Aμm was mechanically milled in liquid nitrogen environment for 3 to10 h, and stainless steel balls with a diameter of 6.4 mm were used as the grinding media with the ball-to-powder mass ratio of 30:1. Outcome powder is consolidated in FSW machine on the principle of High Shear Powder Consolidation technique. The advantages in newly designed Cryo-milling setup are a setting of simple parameters and there is uniformity in the outcome powder.

Clay, being the most common mineral, is a composite of several minerals such as iron oxides, alumina, silica etc and it has many useful properties, including high specific surface area and excellent adsorptive capacity. Nevertheless, due to the low purity level of the material in nature, its usefulness at high temperatures that exceed 1200oC has been hampered. In this study, an attempt was made in order to investigate the possibility of using various composite minerals in the clay as an advantage to synthesize mullite fibers and zircon ceramic based composites through powder metallurgy technique for high temperature applications.Powder yttria-stabilized zirconia (YSZ) was mixed in a tubular mixer with varying compositions of clay with known mineralogical composition and it was also mechanically milled in a planetary ball mill. The raw clay and blended powders/clay were compacted into standard sample dimensions and finally fired at 1200oC and 1300oC for one hour, also at 1400oC and 1500oC for one, two and three hours. The calcined blends and compacted samples were characterized using ultra-high resolution field emission scanning electron microscope (UHR-FEGSEM) equipped with energy dispersive spectroscopy (EDX) and X-ray diffractometry (XRD). Various mechanical properties of the samples were also determined with the intention to select a recipe of optimum performance. Zircon phase was discovered in the samples of powder/clay mixtures from temperature of 1200oC. Mullite fibers were also discovered in those samples at 1400oC. The addition of the YSZ greatly improved the mechanical properties of the samples when compared to those without the additives. It was concluded that the optimum performance was obtained from the sample with composition 30% (vol) ZrO2 and 70% (vol) clay fired at 1400oC.

The discontinuously reinforced metal matrix composites (MMCs) offer several advantages over conventional alloys. For nanosize materials synthesis, high nucleation and low growth rates are required. Thermal plasma could provide these requirements for synthesis of nanocomposite materials. This presentation will review the various types of in-situ processing of nanocomposites. The thermal plasma processing of nanoscale lightweight alloy matrix TiC and TIN composites is discussed. The in-situ formed reinforcements are thermodynamically stable and disperse uniformly in the alloy matrix. The alloy -TiN composite was synthesized in a non-transferred arc D.C. Plasma reactor from ilmenite ore concentrate using methane and nitrogen as the reactive gases. The standard Gibbs energy minimization method was used to calculate the equilibrium composition of reaction species. A mathematical model was developed to describe the plasma gas and particle dynamics and conversion yields. The model was used to study the thermal decomposition of ilmenite in the non-transferred arc plasma reactor. The computed production rates of TiN from ilmenite using nitrogen and methane gas mixtures are in the range of 0.6 to 3.37 kg/m3/s at 2500 K. The products were characterized with SEM, EDAX, and X-ray diffraction. Experimental results showed that composite with matrix alloy and reinforced nanoscale TiN was formed. The discontinuous reinforcement TiN was well distributed in the matrix phase of alloy. TiN dimension are about 300 nm. The production of composites powders and advanced materials by plasma technology are discussed.

This presentation is aimed at underlying the principles, synthesis, characterization and applications of inorganic nanotubes (INT) and fullerene-like (IF) nanoparticles (NP) from 2-D layered compounds. While the high temperature synthesis and study of IF materials and INT from layered metal dichalcogenides, like WS2 and MoS2 remain a major challenge, progress with the synthesis of IF and INT structures from various other compounds has been realized, as well. Intercalation and doping of these nanostructures, which lend themselves to interesting electronic properties, have been realized, too. Core-shell nanotubular structures, like PbI2@WS2 and SnS/SnS2 and PbS/NbS2 nanotubes from "misfit" compounds have been recently reported. In particular, in view of their anticipated interesting electronic, optical and magnetic properties, the recent progress with the synthesis and structure of nanotubes from variety of misfit compounds is of a particular interest and will be discussed in some detail. Re doping of the IF and INT endow them with interesting electrical and other physio-chemical properties. Major progress has been achieved in elucidating the structure of INT and IF using advanced microscopy techniques, like aberration corrected TEM and electron tomography. Extensive experimental and theoretical analysis of the mechanical properties of individual INT and more recently IF NP was performed casting light on their behavior as superior solid lubricants and their potential use for reinforcing different polymer matrices. IF-MS2 (M=W,Mo, etc) were shown to be superior solid lubricants in variety of forms, including an additive to various lubricating fluids/greases and for various self-lubricating coating and were recently commercialized. Some new potential applications for these and related materials will be discussed in the fields high toughness nanocomposites, etc.

Ferroelectrics are multifunctional materials (piezoelectric, pyroelectric, tunable dielectric constant, non-linear optical properties) that are in use for many high-technology applications (non-volatile memories, thermal imaging, optical shutters, etc.). Among the most used are those ferroelectrics with perovskite structure, such as BaTiO3 or PZT solid solutions. For many years, these materials were used in applications in the bulk form, single crystals or ceramics. The growing demand on integrating the devices based on ferroelectrics with semiconductor technology has shifted the interest towards thin films. The rapid development of the deposition techniques allows, nowadays, the growth of high quality epitaxial structures based on ferroelectric layers with oxide structure. However, all these heterostructures are including interfaces, and the quality of the interfaces can have a considerable impact on the macroscopic properties of the structure or on the physical characteristics of the device including the irrespective structure. Therefore, the study of interface properties in correlation with the macroscopic physical properties such as polarization, dielectric constant or leakage current is very important. Here we report on some recent results obtained on the role of interfaces in some epitaxial structures based on ferroelectric perovskites. The investigations involved several techniques, such as structural investigations by XRD and (HR)TEM, investigation of domain structure by PFM and macroscopic electrical measurements. The main conclusion was that the interfaces may dominate the macroscopic properties. Other important conclusion, referring specifically to the electrode-ferroelectric interface, is that the polarization charges are controlling the band-bending and the height of the potential barrier. Furthermore, it was found that interfaces can enhance the dielectric constant, the stress at the interfaces can induce thickness driven phase transitions, or that the memory window in MFS structures can be affected by the quality of the interfaces. The above results open new perspectives in designing ferroelectric based structures interface engineering.

The possibility of mechanical properties regulation of ceramic masses on the basis of loessial breeds is shown in this abstract.The influence of various additives on plasticizing durability of ceramic masses is here studied. The mechanism of additives action on plastic-knitting properties of loessial breeds is developed. Chemical processes proceeding at modification of ceramic loessial masses by various additives (including by production wastes) as well as the dislocation of clay (loessial masses) structure and its influence on formation of product are investigated. The possibility of industrial wastes usage for brick and tile manufacture is also shown.

Silicon nitride (Si3N4) is an advanced structural ceramic material which is being used for engineering applications such as heat engines and gas turbines. In this laboratory scale study, carbothermic production of silicon nitride from rice husks was investigated in detail. A highly pure mixture of carbon and silica was obtained by pyrolysis of water washed and acid leached rice husks from Turkey's Black Sea region. The obtained mixture was then treated in a tubular electric resistance furnace at a temperature range of 1300-1500 degrees centigrade under nitrogen flow rate of 50L/h. The results indicated that it was possible to produce Si3N4 from Turkish rice husks at the optimum nitridation conditions experimentally determined.

Carbide nanoparticles were added to the hypoeutectic Al-Si melts in the amount of 0.001-0.1 wt. %. A fine microstructure of the alloy was achieved by a modification process as a result of direct influence of the nanoparticles to the metal crystallization process. Macro- and micro- structures of the aluminium alloy specimens fabricated by casting process were investigated and their mechanical properties were tested. After T6 heat treatment of the obtained modified alloys, the following properties have been achieved: The elongation increased by 20-60% in different parts of a cast whiles the tensile strength remained unchanged.A high resolution electron microscopy (HR-TEM) study indicated a high concentration of dislocations near grain boundaries in the modified alloy samples. These grain boundaries seem to serve as obstacles to dislocation motion. It was therefore concluded that the mechanical properties improvement of the aluminum alloy modified with carbide nanoparticles can be explained by the grain-size strengthening mechanism.

Metal nanoparticles on oxide substrates have gained a markedly increasing consideration with regard to both scientific and technological purposes. Significant variations in the Au/SiO2 optical and mechanical response are induced by modifications of the system morphology from cluster-like systems, where gold nanoparticles are dispersed on the silica surface, to island-like structures, where Au aggregates are partially interconnected between each other, and ultimately, to continuous films. Properties of gold films sputtered under different conditions onto borosilicate glass substrate were studied. The mechanical properties of sputtered gold layers were examined using nanoindenter. The surface elastic modulus and hardness were determined and scratch tests were performed. XRD analysis provided information about the gold crystalline nano-structure. XRD method was employed to determine surface texture, crystallite size and microstrain. The study of mechanical properties of Au/SiO2 was supported by measurement of its chemical composition. Depth concentration profile of oxygen in gold silica nanosystem was determined from RBS spectra. The surface morphology was examined by Atomic Force Microscopy and by Scanning Electron Microscope. The elastic modulus decreases rapidly from the surface up to the depth of ca 20 nm. The dependence of the hardness on the tip displacement into the surface indicates dramatic hardness decline. Sputtering of gold on glass substrate leads to formation of polycrystals with a preferential orientation in the (111) direction. The concentration of oxygen decreases monotonously with increasing depth. With ongoing deposition, interconnections between individual clusters are formed and the deposited layer becomes homogeneous and uniform.

Zero-valent iron nanoparticles are widely applicable for remediation of contaminated waters, surface water and wastewaters. There are many sites in UA and Europe, where these nanoparticles were tested or used for full scale remediation. The particles are produced either by milling of microscopic particles in aqueous or non-aqueous environment or by chemical reduction in gas atmosphere of hydrogen at high temperature. The particles are surface modified to improve their migration and reactivity. Besides knowing the particle application properties, the basic particle characteristics and features are unknown. This is due to their relatively rapid oxidation and by this change of surface properties. The goal of the paper is to make an overview of zero-valent iron nanoparticles and their composites preparation. Particle characterization by a wide spectrum of methods including TEM, SEM, BET, size distribution, Mossbauer spectroscopy, zeta potential etc. Is also included.

Engineered-nanotubular structures offer exciting progress toward the design of multifunctional medical implants. To bring this to reality, one should know the mechanical, electrical, surface, and biocompatibility properties of such structures. The mechanic of nanotubes is important from mechanotransduction points of view. It was observed that the fabrication of TiO2 nanotubes with elastic modulus close to actual bone promotes osteoblast growth. In order to investigate this effect, series of novel experiments on measuring the mechanical properties of individual TiO2 nanotubes followed by in-vitro cell culture test were conducted. The nanotubes were tested in the chamber of transmission electron microscope using an in-situ atomic force microscopy stage with force resolutions better than 1 nN. Thin and thick nanotubes were tested to check if there were variations of mechanical properties as a function of size. It was shown that the nanotubular characteristics of the surface improve cell proliferation, attachment and spreading of osteoblast cells. Finally, it was observed that as the nanotubes become stiffer, the density of cells increases. Based on these findings, we speculate that surface modification of Ti implants by TiO2 nanotubes with elastic behavior close to the actual bone can be promising to overcome stress-shielding, a common reason for implant failures.

Recently, the high voltage power lines and electrical insulators were widely developed in order to conduct electricity.The electrical discharge phenomenon caused by contamination of insulator surfaces is one of the main problems that affects electric power systems. In this research, TiO2-SiO2 nano coating was applied on electrical insulator via sol-gel method at first, and then, the hydrophobicity properties of this coating were investigated. The coating sol was prepared by using titanium tetra isopropoxide (TTIP), tetraethoxysilane, hydrochloric acid, ammoniac, absolute alcohol and deionized water as reactant materials. TiO2-SiO2 thin film was deposited on substrate by sol-gel dip coating method at a withdrawal speed of 10 cm/min. The X-ray diffraction results showed no trace of TiO2-SiO2 peaks, while the presence of absorption peaks of Ti-O and Si-O bonds were obtained by FTIR spectrometer. Data of hydrophobicity test revealed that the contact angle increased from 89 to 140 degrees and the maximum value was achieved for sample with 25% TiO2. SEM micrographs indicated that fabricated coating was uniform without any crack. The final result by AFM roughness analysis exhibited the roughness value of prepared coatings, which was increased by increasing the TiO2 content. Therefore, it was revealed that the TiO2 coating surface contamination could be reduced.

In this contribution, the authors present a study on the influence of various processing parameters in the formation of new phases on boron carbide porous particulate substrates via direct nitridation. A Taguchi experimental design allowed establishing the quantitative effect of atmosphere, time, temperature, and gas flow rate on phase type, amount and morphology of products. Afterwards, an optimization of the processing parameters on the formation of boron nitride was performed. According to the analysis of variance (ANOVA), the optimum conditions to maximize the amount of BN were: HPA (high purity air) atmosphere, 60 min, 1300°C and a flow rate of 60 cm3/min. The specimens were analyzed using FT-IR spectroscopy, XRD, SEM and EDS. The study was complemented with thermal analyses of the substrate and thermodynamic calculations using the FactSage® software and databases, in order to elucidate the formation of the different phases in the processed samples. Experimental results show the presence of new phases, including boron aluminate and boron nitride, which indicates that formation of BN on BC particles in nitrogen containing atmospheres by direct nitridation reactions is feasible.

Nowadays, there are many studies about hydroxyapatite (HA) coatings on metal substrate for biomedical application. However, one of the most important factors to be improved is the cracking of the coating as a result of thermal treatment to consolidate it. This problem is due to a difference on thermal properties between ceramic and metal.In this work, a dental porcelain (DP) was used as intermediate thermal properties material to minimize the residual stress between HA and 316L stainless generated during sintering process. The DP and HA were deposited by electrophoretic deposition at constant voltage using organic solvents as dispersing media. The zeta potential was determined for both ceramics. The mass deposited was evaluated as function of deposition time, and the coating was sinterized at 850, 900 and 950°C. The coatings were characterized by Scanning Electron Microscopy and the adhesion strength of sintered coatings was evaluated according to ASTM F1044-87.The result showed the coating was dense, homogenous and cracking free at the sintering temperature of 950°C. The adhesion strength under this condition was around 14.6 MPa.

Gold nanoshells were produced by using gold nanoparticles obtained via salt reduction of KclAu4 on silver nanopartilces as template. The nominal size of the gold nanoparticles was 3 nm and for silver template was 30 nm. Afterwards, samples were characterized by STEM, FTIR and Raman spectroscopy, respectively. Gold Nanoshell shows a typical branched grown with sizes of 50 nm. FTIR studies showed the functional groups typically present in the reactions. These groups were alcohols, PVP used as reactor for gold nanoparticles, and VPR used as functionalizing copolymer. Finally, the Raman results yield a characteristic peak of the reactants contributions and that corresponding to solvates AgCl + HCl. Also, we discuss the formation of gold nanorings by the galvanic replacement of Ag nanosphere template particles. The Au/Ag nanoshells can be converted to nanorings upon addition of excess HAuCl4.

Super paramagnetic iron oxide nanoparticles (SPIONs) have shown great promise in biomedical applications. Here, we report a systematic study of functionalization of tunable size Fe3O4 nanoparticles. Novel nano-Fe3O4 based composites with functional groups have been prepared by solvent-thermal method. By adjusting the molar ratios of Fe3+ and carboxylate, nano-Fe3O4 particles with various size distributions from 800 nm to 1210 nm can be obtained. By adding NaOH content, the morphology of Fe3O4 nanoparticle can be controlled from sphere to regular octahedron. When protecting from silica coat, which forms core-shell structures, several functional groups (-COOH, -NH2, and -SH nanoparticle) are grafted on the surface of Fe3O4 as the activating group to absorb heavy metal ions (e.g, Pb+, Cd2+). The absorption results show that nano-Fe3O4 based composite maintains an effective performance of removing heavy metal ions, suggesting that the nano-Fe3O4 based composite could become a potential medicine for heavy metal poisoning therapy.

An L8 Taguchi experiment was designed and conducted to determine the quantitative effect of processing parameters (test temperature and time, nitrogen gas flow rate, NH4OH position, Na2SiF6 quantity) on the amount (weight) of films/coatings on aluminum sheet substrates. Films/coatings based on (NH4)2SiF6 (NH4)3AlF6 and NH4AlF4 were deposited on aluminum sheet substrates by the HYSY-CVD route (Hybrid system chemical vapor deposition), using Na2SiF6, NH4OH and N2 as precursors. After deposition treatments, the coated aluminum samples were characterized by SEM (Scanning Electronic Microscopy), EDS (Energy Dispersive Scanning) and XRD (Diffraction X-Rays). The results from the analyses by XRD showed that films/coating are formed by a mix of (NH4)2SiF6, (NH4)3AlF6, and NH4AlF4 phases. The SEM analysis shows that films/coating microstructure has crystals with polyhedral, cuboid and hexagonal geometry and size under 5 μm, and the films/coatings have a thickness of approximately 25 μm. The results from the analysis of variance (ANOVA) indicate that the parameter that most significantly affects the variability in the amount of film/coating on the aluminum sheet is the test temperature (T), with 84.2 % contribution. The optimum conditions to maximize the amount of coatings on aluminum sheet substrates are: 15 g of Na2SiF6, test time of 30 min, processing temperature of 1000°C, a nitrogen flow rate of 15 cm3/min and NH4OH precursor liquid placed in the center of the reactor.

Albeit composites have been considered for long an extra class of materials. A thoughtful analysis readily suggests that they are perhaps the consummate benchmark of materials, because they may encompass all other classes of materials. Furthermore, with the advent of the field of nanoscience and nanotechnology, the concept of composites was quickly assimilated and applied to situations at the nanometer scale, giving place to the "nanocomposites" class of materials. At the same time, and due to an intense research activity, a countless number of new or modified composite materials developments were reported in the literature. These new developments did reflect the fact that the concept of composites is nowadays exploited not only from the structural standpoint but also from the functional and thermal applications outlook. It should be kept in mind that the concept of composites was originally conceived with the intention of primarily enhancing the mechanical properties of a given material, clearly distinguishing between the matrix and the reinforcing phase. However, with the advent of nanocomposites and with the use of the concept of composites for functional and thermal applications, not only it is pertinent to review the new concepts brought up in dozens of publications but also to propose an updated classification of them. The aim of this contribution is to review the essentials behind the subject matter of composite materials and highlight the recent trends involving new concepts, definitions and updated classifications in an in-depth but also in an easy-to-understand and accessible language. Future perspectives for some of the new developments are also outlined.

During the last two decades, various examples of stable species, which cannot be represented by standard Lewis/ or Kekule structures, were prepared and studied experimentally. Different kinds of stable biradicals 1,2,3 are known. The first stable carbon-based Schlenk's diradical was prepared in 19154. The most stable singlet 1,3-diradical 2,2-dimetoxy substituted cyclopentane derivative known to date has a lifetime of microseconds at room temperature 2. Molecular design of the stable triplet carbens 5 successfully completed by the "bottleable" diantracyl substituted triplet carbene with a lifetime more then week.Formal biradical 2,5-diamino-1,4-benzoquinonediimine is a very stable crystalline compound.6 Azaacene (5,7-diphenyl-5H,12H-quinoxalino[2,3-b]phenazine) also possesses a singlet ground state. This is a result of the delicate tuning between covalent (biradical) and polar (zwitterions) contributions to the resulting electronic structure could.Some of biradical Non-Kekule molecules show a pronounced zwitterionic structure, which was explained by model indicated that electron donor and acceptor substituents placed at opposite sides of a benzene ring (1,2,4,5-substitution) can result in electron transfer favouring a zwitterionic ground state.7Singlet carbenes11were stabilized by electron donation from 1,3-substituents into the vacant p-AO of the central C atom. The first stable crystalline diaminocarbene was reported by Arduengo et al. In 1991.9 Numerous stable singlet carbenes were prepared during the last two decades.1,10 A substantial stabilization of singlet ground state and a corresponding increase of the singlet-triplet gap for non-Kekule molecules can be attained for molecules isoelectronic with the dianions of antiaromatic hydrocarbons. 2,5-diheterosubstituted-pentalenes and 1,5-di-heterosubstituted-cyclooctatetraenes are predicted to be stable persistent non-Kekule molecules11,12 due to strong stabilization by intra-molecular charge transfer.1 K.Wentrup, Science, 295, 1846 (2005) 2 M. Abe, W. Adam, T. Heidenfelder, W. M. Nau, X. Y.Zhang, J. Am. Chem. Soc. 122, 2019 (2000)3 D. Scheschkewitz, H. Amii, H. Gornitzka, W. W. Schoeller, D. Bourissou, G. Bertrand, Science, 295, 1880 (2002)4 W. Schlenk, M. Brauns, Ber. Dtsch. Chem. Ges. 48, 66, (1915)5 E. Iwamoto, K. Hirai and H. Tomioka, J. Am. Chem. Soc., 125, 14664 (2003)6 P.Braunstein, O.Siri, J. -P.Taquet, M. -M.Rohmer, M.Benard, R.J.Welter, R. J. Am. Chem. Soc., 125, 12246, (2003)7 Y. Haas and S. Zilberg, J. Am. Chem. Soc., 126, 8991, (2004)8 A. J. Arduengo, Acc. Chem. Res. 32, 913 (1999)9 A. J. Arduengo, R. L. Harlow, M. Kline, J.Am.Chem.Soc., 113, 361, (1991)10 W. Kirmse, Angew. Chem. Int. Ed., 43, 1767 (2004)11 S. Zilberg and Y. Haas, J. Phys. Chem., A110 , 8397 (2006)12 S. Zilberg, E. Tsivion, Y. Haas, J. Phys. Chem., A112, 12799 (2008)

Colloidal silica particles are being intensively studied due to their potential applications in catalysis, intelligent materials, optoelectronic devices, photonic bandgap crystals, masks for lithographic nanopatterning, etc. On the other hand, in nanoscale electronic, photonic and plasmonic devices, feature dimensions shrink towards a critical limit, and new experimental approaches have to be explored in lithographic patterning in order to create ordered arrays of metallic nanostructures with useful optical properties.For this work, spherical submicrometer-sized silica particles were prepared by the sol-gel technique and deposited as a self-assembled monolayer onto silica glass plates using a spin coater system. This silica monolayer is then used as a mask to create regular arrays of nanoscale features in the sample by 1 MeV Ag ion implantation. By this way, after the removal of silica particles and an adequate thermal annealing of the as implanted samples, the formation of Ag nano-objects was confirmed by the presence of the surface plasmon resonance in the optical absorption spectra.The size and shape of the array of metallic deposits were studied by scanning and transmission electron microscopy, respectively. The total amount of implanted Ag was measured by Rutherford Backscattering Spectrometry (RBS). Finally, the long range order of the Ag nanoparticle assembly and its plasmonics properties were characterized by means of a Fast Fourier Transform study and optical absorption measurements, respectively.

Indian bauxite with Fe2O3 and TiO2 was used to study its phase development with sintering temperature in the temperature range 1000-1650oC. It was found that sintered bauxite samples contains large amount of vitreous phase along with considerable amount of low melting FeAlTiO5 phase. Presence of low melting FeAlTiO5 phase and glass is primarily responsible for inferior high temperature strength of bauxite. As received bauxite samples exhibit Refractoriness under load (RUL) of 1450oC. In the present work, raw bauxite without beneficiation was reaction sintered with reactive source of silica in the temperature range 1500-1600oC to minimize FeAlTiO5 phase formation at elevated temperature. Scanning electron microscopy confirms the reduction of glassy phase and FeAlTiO5 phase. Prevention of low melting phase formation improved the RUL of value added product developed from bauxite. Value added high alumina aggregates exhibits a RUL of 1600oC. This value added high alumina aggregates may find high temperature refractory application.

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