Metal hydrides present a feasible means of energy storage and hydrogen sensing but have several performance criteria that must be addressed, including the hysteresis effect during hydrogen loading and unloading. We present the results of a theoretical and experimental study which demonstrates the possibility to control or eliminate hysteresis during metal-hydride transformation in epitaxial Pd thin films. Theoretical analysis predicts stabilization of two-phase metal-hydride state in film due to its elastic interaction with the substrate. It is shown, by atomic force and scanning electron microscopy, that transformation in 100nm thick epitaxial Pd films on Al2O3 substrate proceeds by the formation of transversely modulated two-phase nanostructure. Morphology and crystallographic orientation of the metal-hydride interface corresponds to the theoretically predicted characteristics of coherent phases.

Well ordered arrays of carbon nanotubes (CNTs) are of interest for a broad range of potential applications including energy storage and as catalyst supports. On some substrates such as copper and nickel, CNTs do not grow well or at all. We have previously shown that mesoporous silica thin films can be deposited onto metal substrates including copper and nickel, and that, after removal of the templating surfactant, the mesoporous silica film can be used as template for the electrodeposition of metals to give metal nanostructures.[Campbell et. al., Micro. Meso. Mater., 97, 114-121 (2006)] The size of the metal nanostructures makes them attractive as seeds for growth of CNTs. We have found that under appropriate conditions nickel deposited into mesoporous silica can act as catalyst for CNT growth on a number of different substrates including copper coated silicon wafers, and nickel foam. Using three different furnaces and different feed streams it was found that the growth is sensitive to carbon source; acetylene and ethylene both produced CNTs whereas attempts to produce CNTs using xylene have so far been unsuccessful.

Well ordered mesoporous silica thin films could potentially give arrays of nanorod seeds, leading to well ordered arrays of CNTs, SEM images of some of our samples show dense CNT arrays, but do not indicate significant ordering.

We report an increase in superconducting temperature of magnesium diboride (MgB2) by minute single-wall carbon nanotubes (SWCNT) inclusions. The SWCNTs concentration was varied from 0.1wt% to 1.0wt%. The temperature dependence resistivity of sintered MgB2- SWCNTs composites containing 0.1wt%, 0.5wt% and 1.0wt% were measured and compared with that of the pure MgB2. The superconducting critical temperature (Tc) of the MgB2 increased from 40 K to as high as 42.4 K for the MgB2 containing 0.5wt% of SWCNTs. The room temperature resistivity ratio (RRR) shows dependence on the sample composition. The temperature width (ΔT) decreases with increasing SWCNT content from 0.1wt% to 1.0wt%. The normal state resistivity data were fitted with the generalized Block-Grüneisen function obtaining a Debye temperature of ∼ 900K.

Pyrochlore type compound Nd2(Zr,Ce)2O7 is considered to precipitate in ThO2-based fuel, that is not observed in irradiated UO2. In order to evaluate the influences on fuel properties, thermomechanical properties of the pyrochlore type compounds, Ln2Zr2O7 (Ln=La, Pr, Nd, Eu, Gd, Dy) and Nd2Ce2O7 were investigated. We synthesized the samples by solid-state reaction and pelletized by spark plasma sintering to make high density (≥ 90 %T.D.) pellets. The phase states and lattice parameters were examined by using X-ray diffraction and SEM/EDX analysis. The lattice parameters of Ln2Zr2O7 depended on the ionic radii of lanthanide ions. The heat capacity, thermal conductivity, linear thermal expansion coefficient, and elastic constants were also measured. It was confirmed that the thermal conductivities for Ln2Zr2O7 were lower than that for ThO2 and depended on Ln ionic radii. The values of elastic constants tended to increase with increasing the Ln ionic radii, corresponding to the thermal conductivity.

Spectral shifts of the emission lines of Erbium ions in Lithium Niobate are used to determine the build-up of intrinsic electric fields under intense light irradiation. The observed spectral shifts can be translated into internal electric fields through a calibration using applied external fields. The studies show that a substantial field can be created locally (up to 150kV/mm) with observed occasional electric breakthroughs that have a corresponding field strength of up to 35kV/mm. In addition, a modification of some Erbium incorporation sites is observed suggesting its relationship with a defect that can by photo-ionized, such as Fe2+/Fe3+.

Dimethyl sulfoxide (DMSO) and several naturally occurring polyols or their derivatives (like glycerol) have been used as cryoprotective agents (CPAs) for many years. However DMSO shows high cytotoxicity and affects differentiation of cells, so it needs to be removed immediately after thawing, whereas polyols are comparatively weaker cryoprotective agents. Furthermore, some types of cells are extremely sensitive to damage during freezing and thawing, so cannot be cryopreserved properly using current CPAs. So there is a great need to develop newer cryoprotective agents with lower cytotoxicity and high efficiency for many biological and medical purposes.

Recently we showed that carboxylated poly-L-lysine, which is classified as a polyampholyte, has a cryoprotective effect on cells in solution without any other cryoprotectant. Polyampholytes are charged polymers with both positively and negatively charged groups.

Therefore, in this research, we are developing a completely synthetic polyampholytes by radical polymerization and will try to elucidate the key parameters of cryoprotective properties. Here we chose reversible addition fragmentation chain transfer (RAFT) polymerization as the mode of polymerization as it is a kind of living polymerization method and can give control over the molecular weight and composition of the copolymer. We evaluated the livingness of the 1:1 copolymer with methacrylic acid (MAA) and 2-Dimethylamino ethyl methacrylate (DMAEMA) with 2-(Dodecylthiocarbonothioylthio)-2-methylpropionic acid as the RAFT agent and the polymer solution showed good cell viability of L929 cells after cryopreservation at 15% copolymer concentration.

We developed a multilayer hybrid structure by imbedding ZnO nanorod arrays in TiO2 network for each layer, for the pourese of taking ZnO nanorods as the highway of electron transport. ZnO nanorods can be prepared by hydrothermal process, which is simple, low cost and easy control. The ZnO nanorod arrays were grown by reported hydrothermal method, then TiO2 network was constructed by spin-coating titanium precursor sol on ZnO nanorod arrays and calcining. The electrochemical impedance spectrum measurements were taken to study the electrical properties of this kind of hybrids, and the results indicated that the effective electron lifetime reaches a magnitude of microsecond which is similar to the pure ZnO nanorod arrays. It reveals to us that ZnO nanorods may dominate the electrical properties of this nano-hybrid structure.

Although the environmental benefits of recycling plastics are well established and most geographic locations within the U.S. offer some plastic recycling, recycling rates are often low. Low recycling rates are often observed in conventional centralized recycling plants due to the challenge of collection and transportation for high-volume low-weight polymers. The recycling rates decline further when low population density, rural and relatively isolated communities are investigated because of the distance to recycling centers makes recycling difficult and both economically and energetically inefficient. The recent development of a class of open source hardware tools (e.g. RecycleBots) able to convert post-consumer plastic waste to polymer filament for 3-D printing offer a means to increase recycling rates by enabling distributed recycling. In addition, to reducing the amount of plastic disposed of in landfills, distributed recycling may also provide low-income families a means to supplement their income with domestic production of small plastic goods. This study investigates the environmental impacts of polymer recycling. A life-cycle analysis (LCA) for centralized plastic recycling is compared to the implementation of distributed recycling in rural areas. Environmental impact of both recycling scenarios is quantified in terms of energy use per unit mass of recycled plastic. A sensitivity analysis is used to determine the environmental impacts of both systems as a function of distance to recycling centers. The results of this LCA study indicate that distributed recycling of HDPE for rural regions is energetically favorable to either using virgin resin or conventional recycling processes. This study indicates that the technical progress in solar photovoltaic devices, open-source 3-D printing and polymer filament extrusion have made distributed polymer recycling and upcycling technically viable.

Proposed is the use of Hydrogen Peroxide (H2O2) as the ideal oxidant for atomic layer deposition of metal oxide films. H2O2 has similar oxidation properties to Ozone while simultaneously having slightly stronger proton transfer properties than water. Vital to the success of any vapor phase chemistry is delivery of stable compositions, temperature and pressure. This study demonstrates the viability of a new membrane technology for the precise delivery of H2O2/ H2O mixtures starting from a liquid range of 30-70%. An in-situ gas phase cleaning process to remove carbon contamination from Ge(100) surfaces using gas phase H2O2 has been characterized.

We studied the electrical properties of thermally treated V2O5-CuO-Fe2O3-P2O5 (vanadate) glasses under reducing high-vacuum conditions. The glasses were prepared by using a melt-quenching method and then applied on Al2O3 substrates as ∼40μm-thick films. The glass films were then heat treated at 375−550°C under a vacuum of 10−6 Pa. Powder X-ray diffraction showed the formation of complex oxides of both MxV2O5 (M = Cu, Fe; x = 0.12−1.3) and vanadium oxides (VOx; x = 1.5−2.5). The resistivity of the glass film crystallized at 550°C measured at 50°C and 300°C were 1.8 × 100 Ωcm and 2.8 × 10−1 Ωcm, respectively, which was 10 times lower than that of the film crystallized in air. The Seebeck coefficient was −132 μV/K at 50°C and −130 μV/K at 300°C. These results show that the vanadate glasses crystallized under the appropriate condition become potential candidate materials for semiconductor and thermoelectric application.

Solute atoms in dilute alloys have been shown to segregate at grain boundaries and stabilize them against grain growth. At present, most theories of the stabilization of nanostructured alloys do not account for the detailed atomic structure of the interfaces, but instead rely on averaged segregation energies. One of the reasons for this is the daunting task of determining segregation energies for a large number of possible sites in a given microstructure. We have developed a new approach to predicting and organizing interface structures in alloys that takes advantage of perturbation techniques and a disclination structural units model (DSUM) developed previously to describe grain boundary structure and properties in pure systems. The fundamental idea is to treat dilute alloys as a perturbed form of the pure metal systems whose energy can be determined by the DSUM. This paper introduces this method and gives a preliminary validation by comparing segregation energies for zirconium solute segregating to a grain boundary in copper calculated via the perturbation method and full atomistic simulations.

Atomic layer deposition has attracted much attention recently in fabricating noble metal nanoparticles for a wide range of applications. We have explored synthesizing palladium nanoparticles via atomic layer deposition on self-assembled monolayers modified silicon substrate. Using alkyltrichlorosilanes as the passivating agents, our results show the method is capable of fabricating Pd nanoparticles with well controlled density and particle diameter on the modified silicon substrate.

Temperature-sensitive ferrogel prepared using Fe3O4 nanoparticles are characterized under varying temperature conditions. The nanoparticles were distributed in Nisopropylacrylamide (NIPAm) during their polymerization to form hydrogel. Particle distribution and agglomeration characteristics of the prepared ferrogels were investigated using ultra small angle x-ray scattering (USAXS) at various temperatures through the Lower Critical Solution Temperature (LCST). Transmission electron microscopy (TEM) was used to estimate the particle size distribution. The magnetic property was investigated using direct current superconducting quantum interference device (DC-SQUID) under hydrated conditions. The USAXS analysis showed an increase in the volume of particles without changing the agglomeration characteristics as the temperature is increased during the measurements. The ferrogel did not show any sedimentation or particle detachment from the gel under thermal cycling. Details of our results and analysis are presented.

Magnetic polyolefin-based nanocomposites were fabricated through a facile one-pot thermal decomposition of organo-metallic precursor, i.e. Fe(CO)5 in polymer-solvent solution condition. The whole fabrication includes dissolution of polyolefin-based hosting matrix in refluxing organic solvent followed by the injection of metallic precursor to perform the in-situ thermal decomposition step. The particle sizes, morphology and dispersion quality of these in-situ synthesized magnetic nanoparticles were investigated by transmission electron microscopy (TEM). Room temperature mössbauer spectrum analysis was used to determine the species of these magnetic nanoparticles. Room temperature magnetic property investigation was utilized to further reveal the magnetic behaviors of these nanocomposites by specifying the saturation magnetization and coercive forces. Thermal gravimetric analysis (TGA) was used to determine the thermal stability of these as-prepared nanocomposites and the particle loadings. The formation mechanisms of these magnetic particles were proposed from the evidence of TEM observations and detailed evolutions are detailed as well.

A dual 137 GHz heterodyne radiometer system was used to study grooved nuclear grade graphite (SGL Group NBG17) inside an electric furnace from room temperature to 1250°C. The millimeter wave radiometer views were collinear with the electric field of one polarized parallel, and the other perpendicular, to the grooves. The anisotropic emissivity was readily detected for 100 μm wide grooves of various depths with a spacing period of 0.76 mm. The emissivity in the 500 – 1250°C temperature range was found to be 5.1 ± 0.5% when the E-field was parallel to the grooves and a factor of 2 – 4 higher, depending on groove depth, in the perpendicular direction. The parallel surface emissivity which was identical to ungrooved surface emissivity corresponded to a 137 GHz surface resistance of 5.3 Ohms, which is about 2.5 times higher than the value predicted from frequency scaling dc surface resistance. The perpendicular emissivity had a modulation with groove depth at odd integral multiples of ¼λ, predicted by electromagnetic finite difference time domain analysis.

The study of the 2D-3D structural transition in Au7 + nanocluster as a function of the number of gold atoms has been a long standing problem due to contradictory results between experiments, that show a 2D structure, and some theoretical results predicting 3D. We present a theoretical analysis, based on the pseudo Jahn-Teller effect that explains the origin of the 2D-3D structural transition controversy. It is shown that the usually assumed 2D non-degenerate ground state cluster structure with D6h symmetry is unstable due to a vibronic coupling between the ground state and one excited state, producing a puckering effect ending in a 3D stable structure with D3d symmetry. This structure presents the same surface area than the 2D, being therefore compatible with ion mobility experimental results. We discuss the effect of symmetry breaking on the Raman, IR and UV-vis spectra, which might indicate some possible sensor capabilities for this subnanometric cluster. The study is based on scalar relativistic and time-dependent DFT calculations in the Zero Order Regular Approximation (ZORA).

In this paper we present a monolithically integrated wavelength selector based on a double pin/pin a-SiC:H integrated optical active filter that requires optical switches to select visible wavelengths. Red, green, blue and violet pulsed communication channels are transmitted together, each one with a specific bit sequence. The combined optical signal is analyzed by reading out the generated photocurrent, under violet (400 nm) background applied either from the front or the back side of the device. The front and back backgrounds acts as channel selectors that selects one or more channels by splitting portions of the input multi-channel optical signals across the front and the back photodiodes. The transfer characteristics effects due to changes irradiation side are presented. The relationship between the optical inputs and the corresponding digital output levels is established through a 16-element look-up table to perform the optoelectronic conversion.

Results show that the wavelength selector acts as a reconfigurable active filter that enhances the spectral sensitivity in a specific wavelength range and quenched it in the others, tuning a specific band. A binary weighted RGBV code that takes into account the specific weights assigned to each bit position is presented and establishes the optoelectronic functions.

A green and mild synthesis of colloidal zinc oxide nanocrystals in ethanol/dimethylformamide mixtures was introduced which allows to produce stable crystalline ZnO particles and tailor their average size in the range of 2.8−4.5 nm by varying temperature and duration of post-synthesis ageing. An increase in dimethylformamide fraction in the mixture results in acceleration of ZnO nanocrystals ripening. Colloidal ZnO nanocrystals emit broadband photoluminescence in the range of 2−3 eV with the quantum yields of up to 12 %.

Bismuth ferrites crystallites were synthesized by a polyvinyl alcohol (PVA) modified hydrothermal method. X-ray diffraction (XRD) analysis indicated that the pure phase of Bi25FeO40, BiFeO3 and Bi2Fe4O9 were synthesized with initial Bi/Fe ratio of 1:1 at the temperature of 200°C for 24 h, using NaOH concentration of 2, 5 and 10 M, respectively. With addition of PVA, the individual Bi-Fe oxides could be existed in a more wide range of processing parameters. The phase evolution of bismuth ferrites in the process of hydrothermal reactions was discussed. Moreover, photocatalytic properties of the bismuth ferrites crystallites were explored. The results showed that they possessed band gaps of about 2.0 eV and performed good degradation effect at visible light region.