The aim of this work is the investigation of the metal-hydride transformation in magnesium (Mg) nanoparticles both as a function of particle size and in response to surface functionalization by clusters of transition metals (TM): Pd, Ni, Ti.

Mg nanoparticles were synthesized by the inert-gas condensation technique, which yields single crystals with six-fold symmetry whose average size can be controlled by tuning the inert gas pressure. After the synthesis the nanoparticles were passivated by slow exposure to oxygen, obtaining a core-shell morphology where a metallic core is coated by a MgO shell of about 5 nm thickness.

The material structure was investigated by Transmission Electron Microscopy (TEM), also in High Resolution (HRTEM) mode, and by X-Ray Diffraction (XRD). The sorption kinetics were analysed by a volumetric Sievert apparatus, which also allowed for a determination of the activation energies.

Small nanoparticles (≈35 nm) display interesting kinetics with gravimetric capacity of 4.5 wt.% at saturation, limited by the oxide fraction. Hydride formation proceeds by one-dimensional growth controlled by diffusion through the hydride, while the reverse transformation to metal involves interface-controlled three-dimensional growth of nuclei formed at constant rate.

On the contrary, large nanoparticles (≈450 nm) exhibit very low reactivity due to reduced probability of hydrogen dissociation/recombination and nucleation at the particle surface. For this reason, large nanoparticles were surface-decorated by TM through in situ evaporation in the inert-gas condensation chamber. This procedure results in clusters of 3-4 nm located over a portion of the MgO shell, as shown by XRD and HRTEM on Pd-decorated sample. This treatment results in dramatically improved hydrogen sorption behavior. In fact, previously inert nanoparticles now exhibit of up to 5.6 wt.%.

Real-time diffraction studies using Synchrotron Radiation were carried out during hydrogen desorption on the Pd-decorated nanoparticles. We clearly show that a Mg-Pd intermetallic phase is formed after the first heating treatment and takes active part in the transformation.

Multiferroic materials are recognized today as one of the new emerging technologies with huge potential for both academic research and commercial developments. Multiferroic composites are in particular more attractive for studies due to their enhanced properties, especially at room temperature, in comparison to the single-phase multiferroics. In this paper, we examine some of the theoretical aspects regarding one type of multiferroic composites (laminated structures) and we discuss one of the many possible applications of these exciting structures. We highlight the main advantages composite systems have over single-phase multiferroics and the similarities that exist between them.

The technology of removing cesium radionuclides from sodium coolant at the BN-350 fast reactor was realized in the form of two different types of cesium traps: stationary devices connected to the circuit and in-core devices installed into the core of reactor when it was not under operation. Carbon-graphite materials were used as sorbents in these traps to collect and concentrate radioactive cesium, accumulated in the BN-350 reactor circuits over the decades of their operation. The relatively small volume traps provided effective radiation-safe conditions for personnel working close to the primary circuit coolant and equipment during BN-350 decommissioning. These spent cesium traps represent solid radioactive wastes that must be treated before long term storage. The presence of chemically active sodium, potassium and cesium in the traps results in series of problems related to their long term storage and disposal in the Republic of Kazakhstan. As a consequence, the technology of filling spent cesium traps with lead/lead-bismuth alloy was evaluated. A set of experiments was implemented aimed at verification of calculations performed in substantiation of the proposed technology: filling a full scale cesium trap mock-up with sodium followed by its draining to determine the optimal regimes of draining; filling bench scale cesium trap mock-ups with sodium and cesium followed by sodium draining and filling with lead or lead-bismuth alloy at different temperatures and filling rates to chose the optimal regimes for filling spent cesium traps; implementation of leachability tests to determine the rate of cesium release from the filling materials into water. This paper provides a description of the experimental program carried out and the main results obtained.

Nanostructured metal oxides with high surface areas have been shown to be efficient photoelectrodes for light-to-energy conversion in dye-sensitized solar cells (DSCs). In this work we demonstrate the use of nanofibrous mats of transparent conducting oxides (TCOs) as nanostructured electrodes, especially for DSCs. The nanofibers have been obtained by electrospinning suitable inorganic precursors and polymers, followed by calcination to remove the polymer. Afterwards, TiO2 layers were generated on our 3D-electrodes by electrodeposition. An improved performance as DSC was found compared to flat electrodes of similar thickness, validating our approach.

Anionic clays has been used in the adsorption of anionic species of toxic heavy metals, such as chromium (VI), which is considered to be a dangerous pollutant, due to its deleterious effects on human health such as epithelial irritation and cancer. In this work the removal of chromium in aqueous solutions using anionic clays with Mg/Al=7 was determined. The anionic clays were synthesized by the sol-gel method at pH 10 and 11.5, and were characterized by X-ray diffraction, thermal analysis, infrared spectroscopy and N2 adsorption Brunauer-Emmett-Teller (BET). By this method, anionic clay containing brucite was obtained. The solids exhibited meso-porosity, high surface areas and thermal stability until 500°C. The data obtained from the adsorption experiments of chromium fitted to the Langmuir adsorption isotherm model and the adsorbent capacity was determined using the Langmuir adsorption equation. The maximum chromium uptake was 45 mg of Cr/g sorbent and 43 mg Cr/g sorbent for anionic clays prepared to pH 10 and 11.5, respectively. The Cr saturation point was attained after eight minutes stirring time. According to chromium adsorption values, the solution pH does not have a significant affect on the adsorption capacity of the anionic clays.

In this work we present two teaching modules, based on the combination of Scratchboard and Scratch, to be used for the study of materials' thermal properties such as thermal conductivity and heat capacity. These properties are very important for the understanding of many applications. In the design of the modules we have taken into account two scenarios, one for elementary and secondary school students and one for high school students. This determines not only the type of measurement and the analysis of the data but also the Scratch interface. The main emphasis for the lower grades is placed on the introduction of the concepts and a demonstration of the differences of the properties of different materials, while for the upper grades for making accurate measurements through inquiry based projects. Both modules have been implemented in a high school laboratory, providing reliable measurements and engaging the students in a higher level than usually.

The grain boundary has been recognized for one of the major defect structures in determining the material strength. It is increasingly important to understand the individual characteristics of various types of grain boundaries due to the recent advances in material miniaturization technique.

In the present study three types of grain boundaries of coincidence site lattice (CSL), small angle (SA), and random types are considered as the representative example of grain boundaries. The grain boundary energies and atomic configurations of CSL are first evaluated by first-principle density functional theory (DFT) and the embedded atom method (EAM) calculations. SA and random grain boundaries are subsequently constructed by the same EAM and the fundamental characteristics are investigated by the discrete dislocation mechanics models and the Voronoi polyhedral computational geometric method. As the result, it is found that the local structures are well accorded with the previously reported high resolution-transmission electron microscope (HR-TEM) observations, and that stress distributions of CSL and SA grain boundaries are localized around the grain boundary core. The random grain boundary shows extremely heterogeneous core structures including a lot of pentagon-shaped Voronoi polyhedral resulting from the amorphous-like structure.

Au nanoparticles have been attached to the surface of titania nanotube arrays by means of a deposition-precipitation method. We demonstrate a high deposition density of the gold particles over the nanotube surface and also good control over the size of the gold nanoparticles. Photocurrent measurements using such Au attached titania nanotubes as photoanodes have been measured and compared with blank titania nanotubes.

Electric Cell-Impedance Sensing (ECIS) is a real-time transduction system that can be used to detect the presence of foreign particles or pathogens by measuring the changes in impedance or resistance of a cell monolayer grown on an electrode. Herein, we present the use of ECIS for the detection of the toxicity of silver nanoparticles on Madine Derby Canine Kidney (MDCK) epithelial cells as a function of changes in the cell confluence and barrier function of the cell monolayer. The barrier function is a measure of the number of tight junctions formed between confluent cells in a monolayer; tighter confluence leads to an increase in a barrier function and thus in the measured resistance. We were able to detect exposures as low as 1 μg of 20 nm silver nanoparticles per 105 cells within 2 hours; those exposures were quantified as a significant drop in impedance and a gradual decrease in the barrier function as compared to the controls. Future work would include the detection of protein toxins using impedance sensing as well as further analysis of the barrier function using fluorescent staining.

Viscoelastic mechanical properties of biological cells are commonly measured using atomic force microscope (AFM) dynamic indentation method with spherical tips. Storage and loss modulii of cells are then computed from the indentation force-displacement response under dynamic loading conditions. It is shown in current numerical simulations that those modulii computed based on existing analysis can not reflect the true values due to the substrate effect. This effect can alter the indentation modulus by changing the geometric relations between the indentation displacement and the contact area. Typically, the cell modulii are significantly overestimated in the existing indentation analysis.

The unique properties of carbon nanotubes (CNTs) strongly depend on their structures. In this study, the growth kinetics of ultra-long multi-walled CNT (MWCNT) arrays by water-assisted chemical vapor deposition (WACVD) has been investigated based on the statistical studies of CNT wall number. It was found that the kinetics of MWCNT arrays in WACVD demonstrated a lengthening and thickening growth. In the linear lengthening stage, CNT wall number remains constant and catalysts preserve the activity; while in the thickening stage, CNTs thicken substantially through the gas phase-induced thickening process and catalysts start to deactivate. The effects of ethylene and hydrogen flow rates on the MWCNT array growth have also been studied. It was found that by changing ethylene flow rate, different linear lengthening stages corresponding to different CNT wall numbers could be obtained. These findings provide experimental solutions to fabrication MWCNT arrays with both selective heights and controllable wall numbers by WACVD.

We report on the phenomenology and kinetics of a self-spreading supported lipid bilayer (SLB) on a patterned surface. Analyses of our experiments provided two findings. One is that the self-spreading velocity increased when the SLB reached the inlet of the line patterns. This capillary effect-like behavior indicates an additional attractive interaction for SLB spreading in the line patterns. The other is that the front edge is always normal to the spreading direction even for curving lines. This can be attributed to the line tension at the spreading front edge.

Japan is located at the converging plate boundaries and is one of the most earthquake-prone zones in the world. In order to ensure the safety of a geological repository against earthquakes, a site with a high possibility of direct destruction by active faults should be excluded, and the relationship between the characteristics of seismic ground motion, subsurface structures, geological disposal system and the propagation characteristics of seismic ground motion should be fully investigated. Earthquake-resistant design based on the latest technology is also very important for ensuring the safety of a geological repository.

Following rapid improvement of seismic observation networks after the Hyogoken Nanbu earthquake in 1995, numerous seismic observation records have been obtained in the vicinity of large earthquakes. According to these seismic observations, some phenomena that might affect the safety of a geological disposal system have occurred. Some earthquakes occurred in the areas where active faults had not been identified, while some records showed that seismic motion in the deep underground environment was greater than that at the surface. We have identified the implications from the latest information concerning large earthquakes for the geological disposal program. This study made it clear that detailed investigation incorporating state-of-the-art technologies could reduce the likelihood of missing active faults to an extremely low level and a more practical analysis of seismic ground motion could be achieved by taking the latest information into account.

Poly-SiGe has quite some potential as structural MEMS layer for CMOS-MEMS integration. However, the contact resistance between SiGe MEMS and top CMOS metal should be low to avoid parasitic effects that would reduce the system performance. In this paper, a new and simple approach is proposed to achieve a low contact resistance between a top CMOS interconnect and a boron doped poly-SiGe MEMS layer deposited at 450 °C. The use of a 20 nm soft sputter etch in combination with a Ti-TiN (5-10 nm) interlayer results in a contact resistivity of 6.2 ± 0.4 × 10-7 Ωcm2 that is lower than previously reported. The uniformity of the contact resistivity across the wafer is also better than the state-of-the-art value.

Platinum (Pt) is the most efficient and highly utilized electrocatalsyt; however its high cost hinders its widespread use as a stand-alone catalyst. To remedy this problem, a nickel (Ni) encapsulated by Pt (NiⓔPt) nanocatalyst was fabricated using a cost-effective green colloidal method. The NiⓔPt nanoparticles (NPs) were then characterized using transmission electron microscope (TEM) equipped with X-ray energy dispersive spectroscopy (EDS), and X-ray powder diffraction (XRD) to determine the particle size distribution, morphology, elemental composition, and crystalline phase structure. The surface energetic was also measured using ZetaPALS™ to identify the stability of the colloidal suspension.

In the preparation of zeolite nanocrystals from the hydrothermal reaction of clear solution, the zeolite products are typically collected by high speed centrifugation. For Beta zeolite, the crystalline yield is often low, thus a good fraction of silicates reminds in the supernatant. These XRD amorphous materials turn out to be uniform nanoparticles that, after calcination, showed similar micropore structure as that of the collected beta zeolite nanocrystals. TPD measurements of hexane isomers further indicated that both the crystalline and the amorphous products were more selective toward the smaller hexane molecule.

The phonon distribution of hydrogen storage α-LaNi5H with 4h, 6m, 12n, and 12o interstitial hydrogen was calculated by using first-principles potential surfaces with a 2×2×2 supercell model in order to investigate structural and thermodynamic properties. Frequency shifts due to the phonon contribution from the internal energies of 12n < 6m < 12o < 4h appeared in specific modes originating from interstitial hydrogen and in the upper-edge modes with nickel-lattice motion. The thermodynamic stability of 12n interstitial hydrogen in α-LaNi5H due to the wide XZ storage space can be explained by its phonon amplitudes and the charge density around nickel-bonded hydrogen.

Organic single crystals offer the interesting and unique opportunity to investigate the intrinsic electrical behaviour of organic materials, excluding hopping phenomena due to grain boundaries and structural imperfections. Their structural asymmetry permits also to investigate the correlation between their three-dimensional order and their charge transport characteristics. Here we report on millimeter-sized, solution-grown organic single crystals, based on 4-hydroxycyanobenzene (4HCB), which exhibit three-dimensional anisotropic electrical properties along the three crystallographic axes a, b (constituting the main crystal flat face) and c (the crystal thickness), measured over several different samples. The carrier mobility was determined by means of space charge limited current (SCLC) and air-gap field effect transistors fabricated with 4HCB single crystals and the measured value well correlate with the structural packing anisotropy of the molecular crystal. A differential analysis of SCLC curves allowed to determine the distribution and the concentration of the dominant electrically active density of states within the gap.

The wet chemical synthesis of energy and sensor relevant nanomaterials often requires large amounts of high boiling point solvents, grams of reactants, solvent-based purification, and the use of oxygen free atmospheres. These synthetic routes are also prone to poor scalability due to requirements of precise control of high temperatures. Because of this, the potential use of metallic nanoparticles and semiconductive quantum dots (q-dots) in energy transfer and real time biosensor applications is labor intensive and expensive. We have explored a green alternative route that involves the colloidal synthesis of CdSe and CdTe quantum dots under well-controlled hydrothermal conditions (100-200°C) using simple inorganic precursors. The resulting nanomaterials are of high quality, and are easily processed depending upon application, and their synthesis is scalable. Temperature control, and synthetic scalability is provided by the use of a synthetic microwave reactor, which employs computer-controlled dielectric heating for the rapid and controllable heating.

We have proposed a spin quantum cross structure (SQCS) device as a candidate beyond CMOS. The SQCS device consists of two ferromagnetic metal thin films with their edges crossed, and sandwiches a few atoms or molecules. In this work, the spin dependent transport formula has been derived for SQCS devices with collinear ferromagnetic electrodes within the framework of the Anderson Hamiltonian. Also, the calculation of the magnetoresistance (MR) ratio has been done as a function of renormalized transfer matrices including magnetostriction effects and the other effects phenomenologically. It is shown that the MR ratio can be controlled by changing the renormalized coupling constants. The MR ratio is represented by a new formula. Also, we have realized an SQCS device with Ni magnetic thin-film electrodes, sandwiching poly (3-hexylthiophene) (P3HT): 6, 6-phenyl-C61-butyric acid methyl ester (PCBM) organic molecules between both the electrodes. The current-voltage characteristics of SQCS devices were measured by a four-terminal method and agree well with the theoretical results, quantitatively.