SnO2 based sensor structures prepared by rf magnetron sputtering technique have been studied for detecting H2 gas. Pd catalyst was integrated onto the SnO2 thin film in the form of clusters and nano-particles to obtain enhanced sensing response characteristics. The prepared sensor structures have been studied over a temperature range of 50-250°C for sensing response towards 500 ppm H2 gas. The sensor with Pd catalyst dispersed in the form of nanoparticles was found to exhibit an enhanced sensing response of 1.9×103 at a relatively low operating temperature of 150°C with a fast response time of 2 s and recovery time of 65 s towards 500 ppm H2 gas. The origin of enhanced sensing response is identified in the light of the enhanced spill over of H2 gas molecules on the uncovered surface of SnO2 thin film.

CdS/CdSe/ZnS quantum dot quantum well (QDQW) nanocrystals were synthesized using the successive ion layer adsorption and reaction technique. CdSe QWs with a well width of 1.05 nm emitted blue light at 467 nm with a spectral full-width-at-half-maximum of ∼30 nm. It was found that a 3-monolayer ZnS outer cladding layer can effectively passivate the QDQW structures, leading to a ∼35% quantum yield (QY) of the QW photoluminescence. QDQW light-emitting diodes (LEDs) with blue QW electroluminescence (EL) were fabricated. The devices with an emitting layer comprising QDQWs embedded in a poly(N-vinylcarbazole) host were five times brighter than LEDs based on closely-packed QDQWs. However, the overall EL of the devices was dominated by interface state emission due to poor charge injection into the QDQWs.

James Madison University (JMU) faculty and K-12 teachers founded in 2011 the Shenandoah Valley Nanoscience Outreach Collaboration (SVNOC) effort. The goal of SNVOC is to help K-12 teachers incorporate nanoscience concepts into their classrooms. In this work we present how SVNOC participants use the Nanodays experimental kits to help students understand basic nanotechnology principles such as “How small is small?” Our preliminary results show that for PE the best experiments are the ones that are outside the operating schema of kids so they can stimulate further research. At the HS level, there is a consensus that students need more challenging mathematics that can be extracted from these experimental kits.

The transport properties of the atomic scale side contact between different metals (Au, Ag, Pt, Cu, Ni, Pd) and graphene with open zigzag ends have been studied from first-principles electron transport calculations. According to the contact configurations, we find the weakly interacting metals (Au, Ag, Pt and Cu) can form chemical bonds at the open graphene’s atomic edges, while the strongly interacting ones form chemical bonds in the whole contact region. Comparing with the case of end contact which could effectively decrease the contact resistance, the atomic scale side contact shows better transport properties than the end contact. And the graphene/metal side contact with hydrogen terminated graphene edge show obviously large resistance than the ones with open graphene edge, which signifies the importance of the termination of graphene edge in graphene/metal contact.

The oscillatory change in the optical absorbance of NiO-TiO2 film containing Au nanoparticles in the presence of H2S gas are investigated. The oscillatory phenomena could be monitored by looking at the variation of the surface plasmon resonance peak of the Au nanoparticles embedded in the TiO2-NiO matrix. Au nanoparticles act as optical probes in the detection of H2S, while the oxide matrix is responsible for the catalytic oxidation of H2S. To the best of our knowledge, it is the first time that oscillatory phenomena are monitored by optical spectroscopy.

Plasma interactions with L-alanine in aqueous solution have been examined as a basis of fundamental processes in plasma medicine. The plasma interactions with L-alanine in aqueous solution have been examined for investigations of chemical modifications induced by exposures with the atmospheric-pressure hollow-cathode He plasma to the surface of the aqueous solution, which contained L-alanine as a solute in pure water, via chemical bonding states analyses using x-ray photoelectron spectroscopy (XPS). Measurement of hydrogen ion exponent (pH level) of pure water during the atmospheric plasma exposure showed that the pH level decreased to be acidic, but the water temperature did not change. The C 1s XPS spectrum from the L-alanine after the plasma exposure to the aqueous solution showed the decomposition of the -COOH group and the formation of -C=O group.

Systems in which DNA is adsorbed onto gold nanoparticles have the potential for applications in gene regulation therapies, drug delivery, sensing, and DNA scaffolding. However, the mechanical stability of gold nanoparticles (AuNPs) and interfacial behavior between the gold nanoparticles and thiol ligands are not well understood or quantified. The stability of DNA-AuNP) systems is, therefore, examined using a large-scale specialized finite-element approach with a dislocation-density based crystalline plasticity framework to model the AuNPs and an elastic description to model thiol ligands, DNA, and the ionic solution. For compressive loading conditions, the system exhibited morphological instabilities in the nanoparticles, as well as high stress and dislocation-density gradients at the thiol-nanoparticle attachment sites, which can affect system stability and attachment strength.

Nanophase Eu-doped Y2(CO3)3 and Eu-doped Zr(OH)4 are seeded into explosive fireballs to record the temperatures inside the fireball. The heat from the explosion decomposes the materials and converts them into Eu-doped Y2O3 and Eu-doped ZrO2, respectively. The optical signatures of these materials are compared with those of samples heated in a pyroprobe. By comparing the full-width half-max (FWHM) of the excitation peak of Eu-doped Y2(CO3)3 or comparing the ratio of two fluorescence peaks and the peak position of Eu-doped Zr(OH)4, we are able to deduce the temperatures inside the explosive fireball.

Displacements and strains can be calculated from the microscopic image of a quasiperiodic structure by the analysis of its spectral content, consisting of a discrete set of peaks (Bragg spots in the case of the crystal structure). Typically one would choose certain peak and evaluate the displacements by investigating its neighborhood. However, there is a large amount of redundancy in such an image, as similar measurement can be performed by choosing a different Bragg spot. We demonstrate an approach which in a systematic manner employs information from multiple Bragg spots for the displacement evaluation. This has a positive influence on the quality and robustness of the measurements.

Papers in the Appendix were published in electronic format as Volume 1534

The photodegradation of polypropylene (PP)/ZnO composites at different concentrations was evaluated under solar simulated exposure of respective nanocomposite films. Nanocomposites were prepared by solid mixing using a cryogenic mill, and then films were prepared by compression molding. All films showed a good dispersion of ZnO nanoparticles without affect considerably the optical properties of the films. The films were exposed in a solar simulation chamber under three xenon arc lamps with a 340nm filter. Degradation of PP/ZnO nanocomposite films was monitored by formation of oxidative groups and changes on surface microstructure. FTIR results showed that oxidation groups in nanocomposites films increased by using cuasi-spherical ZnO nanoparticles.

Complex nanoscale architectures based on gold nanoparticles (AuNPs) can result in spatially-resolved plasmonics. Herein, we demonstrate the growth of silicon nanowires (SiNWs), heterostructures of SiNWs decorated with AuNPs, and SiNWs decorated with graphene shells encapsulated gold nanoparticles (GNPs). The fabrication approach combined CVD growth of nanowires and graphene with direct nucleation of AuNPs. The plasmonic or optical properties of SiNWs and their complex heterostructures were simulated using discrete dipole approximation method. Extinction efficiency spectra peak for SiNW significantly red-shifted (from 512 nm to 597 nm or 674 nm) after decoration with AuNPs, irrespective of the incident wave vector. Finally, SiNW decorated with GNPs resulted in incident wave vector-dependent extinction efficiency peak. For this case, wave vector aligned with the nanowire axial direction showed a broad peak at ∼535 nm. However, significant scattering and no peak was observed when aligned in radial direction of the SiNWs. Such spatially-resolved and tunable plasmonic or optical properties of nanoscale heterostructures hold strong potential for optical sensor and devices.

Chemical solution deposition techniques are a very competitive low cost method to achieve coated conductors. Recently, fluorine-free CSD methods have made a great progress for the preparation of YBCO thin films and became a sustainable alternative for the well-known trifluoroacetate CSD approach. By elucidating the reaction mechanism behind this new approach, finally giving an answer to the question why it is possible to fabricate YBCO films without TFA, different processing routes were discovered giving rise to high superconducting YBCO films (>1MA.cm-2). Each route has it's own benefits. One specific route offers the opportunity to tune the crystallographic orientation. By changing one process parameter, a shift from complete c-axis to complete a-axis orientation is observed. This can be very useful for e.g. Josephson Junctions.

We particularly investigated the fundamental reaction mechanism of each reaction route, with the focus on the corresponding barium compound. Although good superconducting properties are obtained, still one major drawback limits industrial implementation: thickness. It is observed that a critical thickness of ∼500 nm eliminates the superconducting properties. Therefore, this paper gives a summary of all progress made regarding to fluorine-free water-based CSD YBCO thin films with emphasis on the possibility to control the crystallization rate.

ZnO single crystal substrates grown by the hydrothermal method have been characterized by grazing incidence X-ray topography using both monochromaticand whitesynchrotron X ray beams.11 $\bar 2$ 4 reflection wasrecorded from the (0001) wafers and the different contrast patterns produced by different threading defects were noted. To uniquely identify the Burgers vectors of these threading dislocation defects, we use raytracingsimulation to compare with observed defect contrast. Our studies showed that threading screw dislocations are not commonly observed.Most threading edge dislocationshavetheBurgers vector of1⁄3[2 $\bar 1$ $\bar 1$ 0] or1⁄3[12 $\bar 2$ 10]and a density of 2.88×104/cm2.

Model alloys have been made of pure W and 1% & 5% W-Ta and W-Re. Indentation hardness and modulus data were obtained by nanoindentation to assess the effect of composition on mechanical properties. Results showed that both the Ta and Re compositions hardened with increasing alloy content, greater in the W-5%Ta composition which showed an increase of 1.03GPa (17%), compared to a 0.43GPa (7%) increase in W-5%Re. The samples also showed very small increases in modulus of ∼ 25GPa (6%) in both W-5%Re and W-5%Ta. The samples were implanted with 3000appm concentration of helium. All samples show a substantial increase in hardness of up to 107% in the case of pure W. An appreciable difference in modulus is also seen in all samples. Initial TEM work has shown no visible He bubbles, suggesting that the mechanical properties changes are due to He-vacancy cluster formation below the resolvable limit.

Deoxyribonucleic acid (DNA) immobilization on nanoscale architectures is critical for developing bio-compatible devices and clinical diagnoses. In this study, silicon nanowires (SiNWs) were combined with gold nanoparticles encapsulated in graphitic shells (GNPs). The resulting SiNWs-GNPs heterostructures were plasma oxidized to create carboxylic (-COOH) functionality on the surface of the graphitic carbon shell. These heterostructures and their surface chemistries were studied using electron microscopy, Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy. The –COOH terminated graphitic shells in heterostructures were covalently linked with DNA. The DNA molecules on these heterostructures were detected by linking with fluorescent streptavidin and observed under a fluorescence microscope. Such inorganic heterostructure-biomolecule assemblies can be very useful in the development of biomolecule analysis and detection devices.

Very recently, Cu3BiS3 has been suggested as an alternative material for photovoltaic (PV) thin-film technologies. In this work, we analyze the electronic and optical properties of Cu3BiY 3 with the anion elements Y = S, Se, and Te, employing a first-principles approach within the density function theory. We find that the three Cu3BiY 3 compounds have indirect band gaps and the gap energies are in the region of 1.2–1.7 eV. The energy dispersions of the lowest conduction bands are small, and therefore the direct gap energies are only ∼0.1 eV larger than the fundamental gap energies. The flat conduction bands are explained by the presence of localized Bi p-states in the band gap region. Flat energy dispersion implies a large optical absorption, and the calculations reveal that the absorption coefficient of Cu3BiY 3 is larger than 105 cm−1 for photon energies of ∼2.5 eV. The absorption is stronger than other Cu-S based materials like CuInS2 and Cu2ZnSnS4. Thereby, Cu3BiY 3 has the potential to be a suitable material in thin-film PV technologies.

We have investigated BisGMA-TEGDMA dental composites with varying mass fractions of hydroxyapatite and silica filler. Commercially available dental composites with 60% silica filler were synthesized in the presence of nanometer-sized hydroxyapatite crystals. We have compared the mechanical properties of BisGMA-TEGDMA samples filled with silica only and those filled with silica and hydroxyapatite particles. We report on hardness as a function of crystalline content as determined by nanoindentation and microindentation.

Oblique-angle deposition is used to fabricate indium tin oxide (ITO) optical coatings with a porous, columnar nanostructure. Nanostructured ITO layers with a reduced refractive index are then incorporated into antireflection coating (ARC) structures with a step-graded refractive index design, enabling increased transmittance into an underlying semiconductor over a wide range of wavelengths of interest for photovoltaic applications. Low-refractive index nanostructured ITO coatings can also be combined with metal films to form an omnidirectional reflector (ODR) structure capable of achieving high internal reflectivity over a broad spectrum of wavelengths and a wide range of angles. Such conductive high-performance ODR structures on the back surface of a thin-film solar cell can potentially increase both the current and voltage output by scattering unabsorbed and emitted photons back into the active region of the device.