Cobalt nanomaterials with promoters have been prepared by precipitation followed by calcination and impregnation method. The obtained materials are characterized by ICP, H2-TPR, BET and XRD. A small addition of manganese increases the specific surface area of cobalt nanomaterials and thermostability under reduction atmosphere. Bulk Co3O4 has been reduced in two steps (Co3+→Co2+→Co). A small addition of manganese to the cobalt oxide shifts the reduction peaks to high temperatures.

Nonresonant inelastic x-ray scattering (NIXS) measurements probing the 5d → 5f electronic transitions at the uranium O 4,5 edges in a localized electron system such as UO2 show a good agreement with many-electron atomic spectral calculations. The higher multipole spectra are split into two peaks that can be assigned as the 5d 5/2 and 5d 3/2 structures, despite the large electrostatic interactions. A new sum rule for the branching ratio of spin-orbit split core levels in electric multipole spectra, which generalizes the sum rule for dipole transitions in x-ray absorption spectroscopy, allows for a systematic analysis of the NIXS spectra. The branching ratio is linearly proportional to the expectation value of the angular part of the spin-orbit interaction in the initial state, where the rank of the multipole determines the coefficient of the linear dependence. This spin-orbit sum rule can be an important diagnostic tool for high-energy spectroscopies.

The parameters influencing the formation of silver nanoparticles are reported. We used poly(vinyl alcohol) (PVA), maltose and silver nitrate as stabilizer, reductant and silver nanoparticles precursor, respectively. The formation of nanoparticles depended upon reaction temperature and pH of solution. The pH of solution controlled by HCl and NaOH. The reaction rate and amount of nanoparticles increase with increasing the reaction temperature. Also, formation of nanoparticles are influenced by pH. The size distribution and dispersion of Ag nanoparticles formed in PVA solution were observed by Transmission electron microscopy (TEM) and the reaction rate and amount of nanoparticles were characterized UV-vis spectrophotometer.

Amorphous silicon-germanium (a-Si0.01Ge0.99:H) thin film, practically amorphous germanium with small concentration of silicon, were deposited by the low frequency PECVD technique under different flow gas of phosphine in the range of QPH3 = 20 to 100 sccm. In this range the phosphorous concentration in gas phase was calculated as XP= 4 to 20 % which resulted in a content in solid phase [P]sol=0.12% - 0.4%. The P content of the solid phase was measured by SIMS profiling and it was also observed a preferential incorporation of phosphorous in the range of [P]sol=0.12% - 0.3%. Hydrogen concentration in the films was determined from FTIR and SIMS measurements. The activation energy was determined by measuring the temperature dependence of conductivity in DC regime in a vacuum thermostat. For the a-Si0.01Ge0.99:H films it is found that the activation energy have a minimum, (Ea= 0.15eV), its conductivity at room temperature have a maximum and there is a minimum of of both band tail and deep localized state for a phosphorous incorporation in solid phase [P] =0.28%.

After the closure of a high-level waste repository, corrosion of the carbon steel overpack will occur. The corrosion products can then migrate into bentonite and affect the migration behavior of radionuclides in bentonite. Therefore, electrochemical experiments, with Fe2+ supplied by anodic corrosion of carbon steel, were carried out to study trivalent lanthanides in compacted bentonite. The interface between a carbon steel coupon and bentonite (dry density, 1.5 Mg/m3) was spiked with a tracer solution containing Nd(NO3)3, Eu(NO3)3, Dy(NO3)3, and Er(NO3)3. The carbon steel coupon was connected as the working electrode to a potentiostat and held at a constant potential between -550 and 0 mV (vs. Ag/AgCl reference electrode) for 7 days. A model using dispersion and electromigration could explain the measured profiles in the bentonite specimens. The best-fit electromigration velocity was related to the applied electric potential and was 1.0–3.8 nm/s for Nd, Eu, Dy, and Er ions. For these lanthanides, the best-fit dispersion coefficient was also related to the applied potential and was 0.8–1.6 μm2/s, and the dispersion length was calculated as 0.2 mm from the linear relationship between the dispersion coefficient and electromigration velocity. Finally, the apparent diffusion coefficient for these lanthanides was estimated as 0.6–0.9 μm2/s.

Graphene-based materials have emerged as exceptional candidates for the development of novel, high performance actuators. Developing such an actuation material requires an in depth knowledge of the physics of operation and, therefrom, how to best optimize its performance. We investigate the electromechanical actuation of pristine monolayer graphene to elucidate the origin of this material’s exceptional electromechanical actuation performance. It is shown that the electrostatic double-layer (EDL) effect is dominant compared to the quantum-mechanical (QM) effect upon charging and electrolyte immersion. Seeking to optimize the QM actuation performance, we preliminarily investigate graphene oxide (GO) as a potential graphene-based actuation material, and find that it exhibits both unique and high performance responses. Having demonstrated huge stresses (~100 GPa) and high strains (~0.4%), graphene-based materials are uniquely positioned to address future industrial actuation challenges.

In this paper, we have performed further investigations and deepened our understanding of Polymer Resistive Random Access Memory devices (PoRRAM) on silicon substrate. Organic thin films based on blend of fullerene (C60) molecules and poly-methyl-methacrylate resist (PMMA) were analyzed from a material and electrical point of views. We have enlightened first the necessity of thermal treatment on the nano-composite layer in order to obtain memory effect in the device. Indeed from I-V measurements, only devices that had a thermal activation exhibited the hysteresis phenomenon, characteristic of the memory effect. The impact of thermal annealing has been investigated by morphological analysis (AFM and confocal microscopy) before and after thermal treatment. This process step induced the C60 molecules aggregation in the polymer matrix. The morphological study of these aggregates coupled with electrical measurements allowed us to determine the influence of aggregation on the electrical behavior. Due to their flexibility, this organic memories based on PMMA:C60 nanocomposites show a strong potential for an adaptation on plastic substrate.

The objective of this study is to establish alloy designing which can reduce the amount of V for a Ni-base dual two-phase intermetallic alloy, without degenerating the dual two-phase microstructure. It was demonstrated that the favorable dual two-phase microstructure will be maintained as far as the valence electron concentration (e/a) of the alloys added by Cr is not so much different from that of the base alloy (i.e. the alloy without additive elements). Consequently, it was found that the dual two-phase microstructure was maintained even though the amounts of V were reduced by 7 at.%, 7 at.%, and 10at.% by substituting of Cr for V, Cr for both of Ni and V, and Cr for Ni, respectively. The hardness of the alloys with reduced V content was higher than that of the base alloy.

The wetting behavior of polyamide films was modified by depositing electrospun nanofibers manufactured from the same polyamide material. Glycerol contact angles on the film surfaces with low coverage of electrospun nanofibers were successfully predicted using a Cassie-Baxter relationship but could not be predicted for high electrospun nanofiber coverage.

We performed magnetoresistance (MR) measurements on bulk carbon nanotube sheets that had been partially aligned by post-fabrication stretching. The magnetic field was applied under different orientations with respect to the direction of the stretch, while the electric current was either parallel or perpendicular to the direction of the stretch. We found that the fielddependence of the MR is composed of two terms, one positive and one negative. The magnitudes of both terms are largest when the field is parallel with the direction of the stretch. If the sheets are treated with nitric acid, the positive term is removed and the MR is smallest when the field is aligned with the magnetic field. We attribute these anisotropic features to magnetoelastic effects induced by the coupling between the magnetic catalyst nanoparticles, the magnetic field, and the network of nanotubes.

Full automation of electron microscopy is now a mature technology that is being applied internationally mainly for mineralogical characterization. This technology has increased the speed and reliability of the characterization of ores and mineral processing products. It allows developing the most appropriate beneficiation technology for a new ore body. It helps to determine the potential, the optimization and the limitations of mineral concentrator plants. It can also be applied to the betterment of the environmental management of the metallurgical residues. This presentation will discuss the main approaches for fully automated electron microscopy. Additionally, an application case is presented, focusing on the characterization of complex ore of rare earth minerals.

Cement-based materials, like concrete and mortar, are widely used in radioactive waste repositories. A deep characterization of these heterogeneous materials, and of their main phases, is necessary to evaluate their capability of retaining critical radionuclides (RN).

In this study, the ion beam technique micro- Particle Induced X- Ray Emission (μPIXE) is used to characterize the concrete and mortar used in the Spanish low level waste repository. Two calcium silicate hydrate (CSH) phases with different Ca/Si ratio are also studied, because they are known to be amongst the most relevant phases, formed upon cement hydration, that retain RN. The retention of thorium on the above mention materials, as relevant tetravalent actinide, is also analyzed. Results are compared with Scanning Electron Microscopy- Energy Dispersive X-Ray Spectroscopy (SEM-EDX) analyses.

Self-disposal option for heat-generating radioactive waste (HLW, spent fuel, sealed radioactive sources) known also as rock melting concept was considered in the 70s as a viable but alternative disposal option by both DOE in the USA and Atomic Industry Ministry in the USSR. Self-disposal is currently reconsidered with a novel purpose – to penetrate into the very deep Earth’s layers beneath the Moho’s discontinuity and to explore Earth interior. Self-descending heat generating capsules can be used for disposal of dangerous radioactive wastes in extremely deep layers of the Earth preventing any release of radionuclides into the biosphere. Descending of capsules continues until enough heat is generated by radionuclides to provide partial melting of surrounding rock. Estimates show that extreme depths of several tens and up to hundred km can be reached by capsules which could never be achieved by other techniques.

By contracting with the Parr Instrument Company and Bruker Optical Systems, we have developed a system for continuous monitoring of hydrothermal and room temperature reactions by Raman spectroscopy. Using the uranyl peroxide cage cluster {[UO2(O2)(OH)]16[UO2(OM)2]4}24- (denoted {U20R}) and a coordination polymer made from uranyl ions and 4,4’-biphenyldicarboxylate as model systems, we demonstrate the spectroscopically observable changes associated with reaction progress and crystallization.

The objective of the present in vitro research was to determine cardiomyocyte functions on poly-lactic-co-glycolic acid (50:50 (PLA:PGA); PLGA) with greater amounts of carbon nanofibers (CNFs) using an in vitro electrical stimulation system for myocardial tissue engineering applications. The addition of CNFs can increase the conductivity and strength of pure PLGA. For this reason, different PLGA: CNF ratios (100:0, 75:25, 50:50, 25:75, 0:100 wt%) were created where conductivity and cytocompatibility properties under electrical stimulation with human cardiomyocytes were determined. Results showed that PLGA:CNF materials were conductive and that conductivity increased with greater amounts of PLGA added, from 0 S.m-1 for 100:0 wt% (pure PLGA) to 6.5x10-3 S.m-1 for 0:100 wt% (pure CNFs) materials. Furthermore, results indicated that cardiomyocyte cell density increased with continuous electrical stimulation (rectangular, 2 nm, 5 V/cm, 1 Hz) after 1, 3, and 5 days as well as a slight increase in Troponin I excretion compared to non-electrically stimulated normal cardiomyocyte cell functions. This study, thus, provides an alternative conductive scaffold using nanotechnology which should be further explored for numerous cardiovascular applications.

In this paper, an experimental study aimed at achieving better control of the deposition patterns of carbon nanotubes (CNTs) is presented. CNTs were grown on a long of reactor by the catalytic chemical vapor deposition (CVD) of a benzene/ferrocene solution at 1073 K. The deposition patterns on the substrate were controlled for process times and carrier gas flow rates. In order to investigate the reaction mechanism and production rate for the growth of CNTs in catalyst CVD, computational fluid dynamics (CFD) model was developed in this study. Then the computational model was integrated with the dynamic model to optimize the process parameters formulating a correlation between turbulence, deposition rate for the growth of carbon nanotubes and parameters as process time and carrier gas flow rate. Scanning electron microscopes (SEM) are used to characterize carbon nanotubes products.

Classical molecular dynamics simulations were used to compare the fracture behavior of pristine and disordered specimens of a simplified nuclear glass. The disordered specimen is prepared in order to mimic the effects of accumulating displacement cascades. It is characterized by a decreasing Boron coordination and an increasing Na concentration in a modifying role. We observe an enhancement of the plasticity of the disordered glass and a decrease of the elastic limit, resulting in greater fracture toughness. The simulation findings are consistent with experimental results.

New materials are needed to replace degenerated intervertebral disc tissue and to provide longer-term solutions for chronic back-pain. Replacement tissue potentially could be engineered by seeding cells into a scaffold that mimics the architecture of natural tissue. Many natural tissues, including the nucleus pulposus (the central region of the intervertebral disc) consist of collagen nanofibers embedded in a gel-like matrix. Recently it was shown that electrospun micro- or nano-fiber structures of considerable thickness can be produced by collecting fibers in an ethanol bath. Here, randomly aligned polycaprolactone electrospun fiber structures up to 50 mm thick are backfilled with alginate hydrogels to form novel composite materials that mimic the fiber-reinforced structure of the nucleus pulposus. The composites are characterized using both indentation and tensile testing. The composites are mechanically robust, exhibiting substantial strain-to-failure. The method presented here provides a way to create large biomimetic scaffolds that more closely mimic the composite structure of natural tissue.

Effusion measurements of hydrogen and implanted helium are reported for (undoped) amorphous and crystalline Si:H and related materials. Effusion of helium observed at temperatures > 600°C is attributed to isolated voids present in the material from the preparation process. While rather high void densities are detected for amorphous silicon films prepared by such deposition techniques like vacuum evaporation or sputtering, much smaller densities are found for plasma grown hydrogenated amorphous silicon (a-Si:H). For device-grade a-Si:H, the density of cavities which can trap helium is estimated to be about 2x1018/cm3at most, suggesting that crystalline silicon type divacancies are not the major hydrogen incorporation site.

The metal-catalyst-free growth of carbon nanotubes (CNTs) using chemical vapor deposition and the application in field-effect transistors (FETs) is presented. The CNT growth process used a 3-nm-thick Ge layer on SiO2 that was subsequently annealed to produce Ge nanoparticles. Raman measurements show the presence of radial breathing mode (RBM) peaks and the absence of the disorder induced D-band, indicating single walled CNTs (SWNTs) with a low defect density. The synthesized CNTs are used to fabricate CNTFETs and the best device has a state-of-the-art on/off current ratio of 3×108 and a steep sub-threshold slope of 110 mV/decade.