Materials Literature
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This paper reports on ZnO/Ag Schottky junctions obtained by the low temperature atomic layer deposition process. Introducing the thin (from 1.25 to 7.5 nm) layer of hafnium dioxide between the ZnO layer and evaporated Ag Schottky contact improves the rectification ratio to about 105 at 2V. For the ZnO/Ag junctions wit…
It is widely believed that crystallization in three dimensions is primarily controlled by positional ordering, and not by bond orientational ordering. In other words, bond orientational ordering is usually considered to be merely a consequence of positional ordering and thus has often been ignored. This one-order-para…
Glucose oxidation using platinum promoted by bismuth was studied as a three-phase model reaction. Using catalyst nanoparticles and measuring the oxygen concentration in the bulk liquid, the kinetic parameters and mass transfer characteristics were determined at a temperature of 333 K. The overall reaction rate was stu…
A novel approach was proposed to fabricate super-hydrophobic surfaces by depositing aggregates of fumed silica modified with hydroxy-terminated poly-dimethylsioxane and γ-aminopropyltriethoxysilane on surfaces of glass plates. The glass plates were treated with 2,3-epoxy propoxy propyltrimethoxysilicane based on an ep…
There are increasing reports of novel metal-based chemotherapeutics that have either improved cancer cell selectivity, or alternative mechanisms of action, to existing anticancer drugs, and techniques are required for determining their sub-cellular molecular targets. Imaging methods offer many distinct advantages over…
We report the synthesis of macrocyclic DTPA conjugates of 2,2'-diaminobiphenyl and their Gd complexes of the type [Gd(L)(H(2)O)]·xH(2)O (2a,b; L = 1a,b) for use as new MRI blood-pool contrast agents (MRI BPCAs). Pharmacokinetic inertness of 2 compares well with those of analogous Gd-DTPA MRI CAs currently in use. The…
The effect of electronic interactions in graphene with vacancies or resonant scatterers is investigated. We apply dynamical mean-field theory in combination with quantum Monte Carlo simulations, which allow us to treat nonperturbatively quantum fluctuations beyond Hartree-Fock approximations. The interactions narrow t…
Basic concepts of crystallography , Basic concepts of crystallography , کتابخانه مرکزی دانشگاه علوم پزشکی تهران
In this work, we present the wetting property of the edges of a monatomic step on graphite. We have used frictional force microscope to experimentally investigate the wetting property of these edges. We have carried out quantum chemical calculations on a model system of nanographene to characterize hydrogen-bonding in…
Structural changes in RMnO{sub 3} (R= Y, Ho, Lu) under high pressure were examined by synchrotron x-ray diffraction methods at room temperature. Compression occurs more readily in the ab plane than along the c axis. With increased pressure, a pressure-induced hexagonal to orthorhombic phase transition was observed sta…
Soft-landed adsorption of Au 16 on bilayered graphene is investigated using density functional theory. The orientation of the Au 16 cluster and number of neighboring surface vacancies affect the overall structural and electronic properties of the cluster. The results of the PBE, vdW-DF, and vdW-DF2 exchange-correlatio…
It has been suggested that gastroliths are a good model for the study of biomineralization and extracellular organic matrix assembly, since they can serve as simplified cases of more complex mineralized biological structures, such as cuticles, bone, and teeth. Proteins are known to be key players in biomineralized chi…
The effects of an aluminum atom on the hydrogen adsorption onto graphene are investigated. An aluminum atom can be attached on a graphene sheet by a bond with both covalent and ionic properties. Then, the electric charge is transferred from the aluminum atom to the graphene. The activation energy for the hydrogen adso…
The authors report the fabrication of heterojunction light emitting diodes (LEDs) based on two-dimensional (2D) hexagonal ordered n-type ZnO nanomesh and p-type GaN. The 2D ZnO nanomesh array was prepared by employing polystyrene spheres as a template. When a forward bias was applied to the LED, a strong ultraviolet (…
Broadband omnidirectional antireflection (AR) coatings for solar cells optimized using simulated annealing (SA) algorithm incorporated with the solar (irradiance) spectrum at Earth's surface (AM1.57 radiation) are described. Material dispersions and reflections from the planar backside metal are considered in the rigo…
The reduction of a single-layer FeO film grown on Pt(111) by CO at elevated pressures and temperatures has been studied through an interplay of scanning tunneling microscopy, ambient-pressure X-ray photoelectron spectroscopy, and density functional theory calculations. Exposure of the FeO thin film to CO at pressures…
We report the observation of positive optical gain in silicon nanocrystals (Si-nc) embedded in silicon nitride measured by the variable stripe length technique. We evidence the onset of stimulated emission and report gain coefficients up to 52 cm−1 at the highest excitation power (6.5 W/cm2). Photoluminescence dynamic…
We report controllable coupling between exciton and localized surface plasmon in a liquid crystal device consisting of gold nanoparticles and CdSe quantum dots. Through an external electric voltage, the emission wavelength of quantum dots can be manipulated. The underlying mechanism is based on the fact that by changi…
Localized surface plasmons within silver nanocubes less than 50 nm in size were investigated using high-resolution cathodoluminescence hyperspectral imaging. Multivariate statistical analysis of the multidimensional luminescence data set allows both the identification of distinct spectral features in the emission and…
We analyze the outcomes of an extended-Drude-model approach to the optical spectra of pnictides, where the multiband nature of the electronic excitations requires a careful analysis of the role of interband processes in the optical conductivity. Through a direct comparison between model calculations of the intraband o…