In this work we present a theoretical study of the transport coefficients of n-type PbTe. The electronic transport coefficients are calculated using the isotropic-nearly-free-electron approximation, including the effect of band non-parabolicity on electron-phonon scattering. The lattice thermal transport coefficient is computed by employing the isotropic continuum model for the dispersion relation for acoustic as well as optical phonon branches, an isotropic anharmonic continuum model for crystal anharmonicity, and the single-mode relaxation time scheme. The role of transverse optical (TO) phonon modes in anharmonic interactions will be discussed in detail.

The relationship between nanoparticle geometry and their two dimensional assembly is investigated in order to provide insights into the three dimensional arrangement of mesocrystals. The crystal structure of the nanoparticles and their homogeneity are investigated during structure formation on the mesoscale whereby effects such as fibrillation have been observed.

LaNiO3 thin films were deposited on SrLaAlO4 (100) and SrLaAlO4 (001) single crystal substrates by a chemical solution deposition method and heat-treated in oxygen atmosphere at 700°C in tube oven. Structural, morphological, and electrical properties of the LaNiO3 thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and electrical resistivity as temperature function (Hall measurements). The X-ray diffraction data indicated good crystallinity and a structural preferential orientation. The LaNiO3 thin films have a very flat surface and no droplet was found on their surfaces. Samples of LaNiO3 grown onto (100) and (001) oriented SrLaAlO4 single crystal substrates reveled average grain size by AFM approximately 15-30 and 20-35 nm, respectively. Transport characteristics observed were clearly dependent upon the substrate orientation which exhibited a metal-to-insulator transition. The underlying mechanism is a result of competition between the mobility edge and the Fermi energy through the occupation of electron states which in turn is controlled by the disorder level induced by different growth surfaces.

One of the major barriers to the adoption of solid oxide fuel cells (SOFCs) is the short lifetime of the fuel cell stacks. A stack consists of a number of cells in series separated by an interconnect. Due to the high temperatures necessary for SOFCs, typical commercial interconnects are ceramic. Great attention has been paid to decreasing the operating temperature of SOFCs in order to extend the life and decrease the cost of the stack. As operating temperatures decrease below 1000°C, alternative interconnect materials become viable. Stainless steel interconnects are more cost effective than ceramic interconnects but the high temperatures and the oxidizing environment of the cathode leads to the formation of a chromium oxide scale that increases the stack resistance. Chromium from the stainless steel can also enter the vapor phase and redeposit on the cathode thereby blocking the electrochemically active sites. One method to neutralize these effects is to coat the metallic interconnect in a ceramic such as La.8Sr.2MnO3 (LSM). The coating acts as a diffusion barrier both against chromium diffusing into the cathode and oxygen diffusing into the interconnect. In this study LSM has been deposited using plasma spray and tested in a dual atmosphere setup using impedance spectroscopy to analyze the performance of the coatings at various temperatures. The area specific resistance and chemical composition of the scale was examined in order to determine the affect of the LSM coating.

In this study, the formation of Ni-(GeSn)x on strained and relaxed Ge1−xSnx (0.01≤x≤ 0.03) nanowires in contact areas has been investigated. The epi-layers were grown at different temperatures (290 to 380°C) by RPCVD technique. The strain in GeSn layers tailored through carefully chosen of growth parameters and virtual substrate. The nanowires were fabricated through both I-line and dry-etching. 15 nm Ni was deposited either on the contact areas or whole length of nanowires. The wires went through rapid thermal annealing at intervals of 360 to 550°C for 30s in N2 ambient. The results show the thermal stability and amount of particular phases were strain-dependent. The formation of Ni-GeSn was eased when GeSn layers were strain-free. When the Sn content is high the epi-layers suffer from Sn segregation. The Sn-rich surface impedes remarkably the Ni diffusion. The electrical conductivity measurement of nanowires shows low resistivity and Ohmic contact are obtained for Ni-GeSn.

Hybrid organic/inorganic nanostructures are engineered to function as two terminal devices with enhanced functionality. The devices are the building blocks for designing hybrid organic/inorganic circuits in the nanoscale. In our work, we have demonstrated the sensing capabilities of polymer nanocomposite thin films for designing nanoweb devices towards detection of biomolecules. Biomolecules with surface charge such as troponin-T were detected on this device by interfacing them with the polymer/metal composites. The change in electrical properties due to modulation in charge transport at the crossbar junction was identified as the measured electrical signal for designing switch based sensors. Nanotextured surface offers strong charge carrier transport and hence enhances the strength of the detected signal. The antibodyantigen interactions at the junction effectively modulate the charge transfer kinetics and modify the junction characteristics due to the surface potential associated with the organic molecules. The net change in surface charge can be measured either as changes in the diode current in the two terminal configuration or as changes in the source- drain current in the three terminal configuration. Detection sensitivity in the order of pg/mL was targeted by measuring the voltammetric current response (in microamperes).

Strontium titanate (SrTiO3) has novel properties, including a large temperature-dependent dielectric constant, and can be doped to make it metallic or even superconducting. The origin of conductivity observed at the SrTiO3/LaAlO3 interface is a topic of intense debate. In the present work, bulk single crystal SrTiO3 samples were heated at 1200°C, with the goal of producing cation vacancies. These thermally treated samples exhibited persistent photoconductivity (PPC) at room temperature. Upon exposure to sub-band-gap light (>2.9 eV), the free-electron density increases by over two orders of magnitude. This enhanced conductivity persists in the dark, at room temperature, for several days with essentially no decay. Light excites an electron from the vacancy to the conduction band, where it remains, due to a large recapture barrier. These observations highlight the importance of defects in determining the electrical properties of oxides and may point toward novel applications.

Elastic engineering strain has been regarded as a low-cost and continuously variable manner for altering the physical and chemical properties of materials, and it becomes even more important at low-dimensionality because at micro/nanoscale, materials/structures can usually bear exceptionally high elastic strains before failure. The elastic strain effects are therefore greatly magnified in micro/nanoscale structures and should be of great potential in the design of novel functional devices. The purpose of this overview is to present a summary of our recently progress in the energy band engineering of elastically bent ZnO micro/nanowires. First, we present the electronic and mechanical coupling effect in bent ZnO nanowires. Second, we summary the bending strain gradient effect on the near-band-edge (NBE) emission photon energy of bent ZnO micro/nanowires. Third, we show that the strain can induce exciton fine-structure splitting and shift in ZnO microwires. Our recent progresses illustrate that the electronic band structure of ZnO micro/nanowires can be dramatically tuned by elastic strain engineering, and point to potential future applications based on the elastic strain engineering of ZnO micro/nanowires.

Continuous composition spread (CCS) methods have been very successfully used for exploiting and optimization of new material systems. Concerning sample growth by pulsed-laser deposition (PLD) approaches towards thin films with a CCS are involved, here movable masks for partial shadowing of the substrate and multiple targets are needed to obtain linearly varying changes of composition. Here we make use of an approach allowing deposition of thin films with CCS at high growth rates by using segmented PLD targets. We describe how this approach can be used to fabricate monolithic, wavelength-selective multichannel UV-photo-detector arrays.

Charge transport through an eight-base pair methylated DNA strand and its native counterpart have been investigated. We focus on three factors, contact coupling, decoherence and temperature, which can contribute to DNA charge transport. Our results show that with the same choice of contact coupling, in the phase-coherent limit the transmission of the methylated strand is smaller in the bandgap at energies close to the highest occupied molecular orbital (HOMO), while inside the HOMO band, the transmission is oscillatory and the methylated DNA may have a larger transmission in certain energy windows. The trend in transmission also holds in the presence of the decoherence though there is a crossover in the transmission of the native and methylated strands away from the HOMO level. We also find that the transport depends on the strength of contact coupling and the measurement temperature.

Layered transition-metal dichalcogenides such as molybdenum disulfide are indirect band gap materials in their bulk form but become direct semiconductors when pared down to a single layer. This paper discusses the structural characteristics and properties of single and few-layer molybdenum disulfide. Specifically, we present aberration-corrected high-resolution transmission electron microscopy (HRTEM) investigations of the structural properties of this material. This information is augmented with data from Raman and photoluminescence spectroscopies on single and few-layer samples. High-resolution TEM images of few-layer and bulk molybdenum disulfide confirm a hexagonal structure for the material. Direct images, along with corresponding fast Fourier transforms, provide valuable information about the crystal structure and reciprocal space lattice of few-layer molybdenum disulfide. One can, for example, determine the in-plane lattice constants experimentally from analysis of the TEM images. Atomic force microscope topographic maps can yield the thickness of a monolayer of molybdenum disulfide; these maps can also be used to determine the thicknesses of multi-layered samples. Analysis of combined Raman and photoluminescence spectroscopy data are valuable in confirming the number of layers in molybdenum disulfide samples. Furthermore, the photoluminescence data can provide unique information on the nature of emission from monolayer molybdenum disulfide; it is characteristically different from that of few-layer samples. The spectral location of the monolayer peak emission agrees with what was obtained from theoretical calculations.

The meso-scale hexagonally packed order structures were obtained by solvent casting from the immiscible polymer blend solutions. The order structures were the result of phase separation occurred at the evaporation front during the solvent casting, the so-called dissipative system. The order domains were flat spheres or ellipses on the matrix surface depending on the combination of polymer blends and solvent, the diameter of spheres were tunable from 0.5 to 3 μm by the casting condition, such as the solvent used for mixing and the evaporation rate. Three blend systems, NBR/SBR, NBR/BR and PMMA/BR, formed two dimensional order structures with the domain size in μm-scale by solvent casting from those homogeneous solutions. The conditions to obtain the two dimensional meso-scale order structure were evaluated.

Complementing a multitude of activities around the International Year of Crystallography, we report here on a few resources that are helpful for integrating basic crystallography into interdisciplinary college education. We concentrate on four resources with which we are directly involved. The Crystallography Open Database (COD) features currently more than 295,000 entries and has over the last decade developed into the world’s premier open-access source for the structures of small molecules and small to medium sized unit cell crystals. ‘Educational offshoots’ of the COD with approximately a thousand entries combined provide structural information on small molecules, selected macromolecules, crystal structures, grain boundaries, and crystal morphologies in the well documented Crystallographic Information Framework (CIF) file format. This information can be displayed interactively on the website http://nanocrystallography.research.pdx.edu and freely downloaded. Files that allow for the printing of selected database entries on any 3D printer have been added to this site and are also freely downloadable. These files were created with the programs Cif2VRML and WinXMorph that convert CIF files directly into 3D printing files. Interested college educators are invited to visit our open access crystallography resource portal and suggest other resources that should receive wider exposure over this portal.

Microgels are hydrogel particles with micron and sub-micron diameters. They have beendeveloped, studied, and exploited for a broad range of applications because of their uniquecombination of size, soft mechanical properties, and controllable network properties. We havebeen using microgels to modulate the properties of surfaces to differentially control theirinteractions with tissue cells and bacteria. The long-term goal is to create biomaterials thatpromote healing while simultaneously inhibiting infection. Because poly(ethylene glycol) [PEG]is used in a number of FDA-approved products and has well-known antifouling properties, wework primarily with PEG-based microgels. We render these anionic either by copolymerizationwith monomeric acids or by blending with polyacids. Both methods produce pH-dependentnegative charge. Surfaces, both planar 2-D surfaces as well as topographically complex 3-Dsurfaces, can be modified using a hierarchy of non-line-of-sight electrostatic depositionprocesses that create biomaterials surfaces whose cell adhesiveness is modulated by a submonolayerof microgels. Average inter-microgel spacings of 1-2 microns exploit naturaldifferences between staphylococcal bacteria and tissue cells, which open the opportunity todifferentially control surface interactions with them based on length-scale effects. Afterdeposition, the microgels can be loaded with a variety of small-molecule, cationic antimicrobials.The details of loading depend on the relative sizes of the antimicrobials and the microgelnetwork structure as well as on the amount and spatial distribution of electrostatic charge withinboth the microgel and on the antimicrobial. The exposed surface between microgels can befurther modified by the adsorption of adhesion-promoting proteins such as fibronectin viaelectrostatic interaction. This approach combines a rich interplay of microgel structure andchemistry as a key component in a simple and translatable approach to modulate the surfaceproperties of next-generation biomaterials.

Swimming is dynamically a part of the hydrodynamic field and can be considered as a field of the optimal control motion. Animals move by instinct according to the situation which they are confronting with. Therefore, their instinctive motion is optimal most of the time. The movement of animals can be classified roughly into two kinds: the fast motion with the maximum speed and the motion with the minimum energy consumption. Considering the foreleg of the soft shelled turtle as a flat plane, several sets of movement of the foreleg were observed and calculated theoretically. The theoretical results agreed the observation results in the both cases with the maximum speed and the minimum energy consumption. Applying the theoretical movement of the soft shelled turtle foreleg to human movement in swimming, the general S-shaped pull stroke is the minimum energy consumption motion in free-style. It became clear that there was a different stroke for generating the maximum speed in free-style. That was the soft shelled turtle style of fast swimming, the I-shaped pull strokes. In 2002 when the author announced this theory, there was only one fast swimmer whose free-style swimming strokes coincidentally accorded with the I-shaped pull with fewer numbers of strokes at that time. He was the Olympic gold medalist Ian Thorp. Now the I-shaped stoke has become main stream in free style.

This study aimed to evaluate the effect of 12 substrates in the seedling growth of chili apple (Capsicum pubescens R. & P.) hybrid Grajales ST. The substrates were prepared with different proportions of five materials: perlite, coconut fiber, loam, Sunshine3 ® and wood dust. The seeds were sown in trays of 50 cavities. For the substrates were determined physical and chemical properties. Significant differences in growth parameters of seedlings are the effect of the substrate. Based on the remarkable accumulation of dry matter of each of the organs of the seedling, and their relative distribution, one can surmise a seedling quality with 47.70 % dry matter in leaves, 35.34 % in stem and 16.95 % in root. The substrate with better features for the production of chile apple seedlings was prepared with 25 % loam and 75 % perlite (v/v), which showed retention of 85.5 % moisture, electrical conductivity of 0.03 dS·m-1 and total porosity of 62.5 %.

Hereby, we present a synthetic route for the production of wurtzite (WZ) CdSe nanocrystals (NCs), which are essential for further shell growing reaction (e.g. CdSe/CdS dot-in-rod (DRs) nanoheterostructures). Our continuous flow reactor set-up consists of a separate nucleation chamber and growth oven. Both components can be heated up to temperatures above 350 °C to guarantee WZ crystal structure.

Furthermore, we introduce DRs as the next powerful tool concerning biological imaging and assay detection. Using DRs in cell imaging results in an increased sensitivity due to the higher brightness compared to spherical core/shell/shell (CSS) nanocrystals.

Two typed bio-conjugated soft-interface for highly sensitive immunoassay was developed by integrating a phospholipid polymer. Nano-sphered surface with poly [2-methacryloyloxyethyl phosphorylcholine (MPC)-co-n-butyl methacrylate (BMA)-co-p-nitrophenyloxycarbonyl poly(ethylene glycol) methacrylate (MEONP)]: PMBN) was prepared by electrospray deposition (ESD) method. The three dimensional nano-sphered surface can be captured an antibody with high density around 860 ng/cm2. The theoretical amount of closest packed immobilized antibodies on flat surface is around 650 ng/cm2, thus large amount of antibodies were immobilized on the nano-sphere surface. The water stability of PMBN nanostructure was improved by crosslinking with 1,4-butylenediamine and by heating. Both heated and cross-linked PMBN nanostructure was not changed at all remaining high porosity after immersing in water. The specific signal in the immunoassay was enhanced with both heated and cross-linked PMBN nanostructure. The PMBN nanostructure which has high porosity and high water stability realized highly sensitive immunoassay.

As the other platform, we developed a novel soft-interface consisting of a well-defined phospholipid polymer surface on which Staphylococcal Protein A (SpA) was site-selectively immobilized. The phospholipid polymer platform was prepared on silicon substrates using the surface-initiated atom transfer radical polymerization (SI-ATRP) technique. Orientation-controlled antibodies were achieved using enzymatic reactions, and these antibodies captured 1.8 ± 0.1 antigens on average, implying that at least 80% of immobilized antibodies reacted with 2 antigens. Theoretical multivalent binding analysis further revealed that orientation-controlled antibodies had antigen-antibody reaction equilibrium dissociation constants (Kd) as low as 8.6 × 10-10 mol/L, whereas randomly oriented and partially oriented antibodies showed Kd values of 2.0 × 10-7 mol/L and 1.2 × 10-7 mol/L, respectively. These findings support the significance of antibody orientation because controlling the orientation resulted in high reactivity and theoretical binding capacity.

An experimental analysis of the morphology changes of hexagonally close packed polystyrene sphere monolayers induced by annealing in air is presented. The triangular interstices between each triple of spheres, which are frequently used as nanoscale mask openings in colloidal lithography, are observed to gradually shrink in size and change in shape upon annealing. Top view scanning electron microscopy images reveal that different stages are involved in the closure of monolayer interstices at annealing temperatures in the range between 110°C and 120°C. In the early stages shrinkage of the triangular interstices is dominated by material transport to and thus shortening of their corners, in the late stages interstice area reduction via displacement of the triangle edges becomes significant. At intermediate annealing times the rate of interstice area reduction displays a maximum before a stabilized state characterized by a rounded isosceles triangular shape forms.