Materials Literature
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We use a recently developed self-consistent GW approximation to present first principles calculations of the conduction band spin splitting in GaAs under [110] strain. The spin orbit interaction is taken into account as a perturbation to the scalar relativistic hamiltonian. These are the first calculations of conducti…
The (TiO2)n clusters and their anions for n = 1-4 have been studied with coupled cluster theory [CCSD(T)] and density functional theory (DFT). For n > 1, numerous conformations are located for both the neutral and anionic clusters, and their relative energies are calculated at both the DFT and CCSD(T) levels. The CCSD…
The reactivity of heterogeneous metal catalysts can be a strong function of the coverage of adsorbates. For example, Pt-catalyzed NO oxidation to NO 2 requires high concentrations of chemisorbed (surface-bound) O, but the development of surface oxides is detrimental to reaction kinetics. Quantifying the structures, pr…
We investigate the effects of electron and acoustic-phonon confinement on the low-field electron mobility of thin square silicon nanowires (SiNWs) that are surrounded by SiO$_2$ and gated. We employ a self-consistent Poisson-Schrödinger-Monte Carlo solver that accounts for scattering due to acoustic phonons (confined…
The first 52 fs of a time evolution of the electron density in OCS after an interaction with an intense sub 10 fs laser pulse are studied using the time-dependent density functional theory. The nuclear motion in this linear trimer is simulated by the classical molecular dynamics method. Laser fields of intensity 10^{1…
One-dimensional nonlinear phononic crystals have been assembled from periodic diatomic chains of stainless steel cylinders alternated with Polytetrafluoroethylene (PTFE) spheres. We report the presence of acoustic band gaps in the dispersion relation of the linearized systems and study the transformation of single and…
Several Niobium oxides of formula Ba2LnFeNb4O15 (Ln = La, Pr, Nd, Sm, Eu, Gd) with the Tetragonal Tungsten Bronze (TTB) structure have been synthesised by conventional solid-state methods. The Neodymium, Samarium and Europium compounds are ferroelectric with Curie temperature ranging from 320 to 440K. The Praseodymium…
We investigate the relationship between electronics and geometry in a nonplanar SiGe/Si resonant quantum cavity (RQC) subject to a magnetic field. The transfer matrix technique originally due to Usuki and coworkers (Phys. Rev. B 52, 8244 1995) has been modified to account for the nonzero local curvature of the RQC. Ou…
We investigate the photoconversion of aqueous 8 nm Ag nanocrystal seeds into 70 nm single crystal plate nanoprisms. The process relies on the excitation of Ag surface plasmons. The process requires dioxygen, and the transformation rate is first-order in seed concentration. Although citrate is necessary for the convers…
We report experimental results of ^{75}As and ^{139}La nuclear magnetic resonance (NMR) in the iron-based layered La(O_{1-x}F_{x})FeAs (x= 0.0, 0.04 and 0.11) system. In the undoped LaOFeAs, 1/T_1 of ^{139}La exhibits a distinct peak at T_N ~ 142 K below which the spectra become broadened due to the internal magnetic…
Diffusional limitations of mass transport have adverse effects on engineering tissues that normally have high vascularity and cellularity. The current electrospinning method is not always successful to create micropores to encourage cell infiltration within the scaffold, especially when relatively large-sized pores ar…
We present an algorithm for generating all derivative superstructures---for arbitrary parent structures and for any number of atom types. This algorithm enumerates superlattices and atomic configurations in a geometry-independent way. The key concept is to use the quotient group associated with each superlattice to de…
Predicting the strain hardening properties of crystals constitutes a long-standing challenge for dislocation theory. The main difficulty resides in the integration of dislocation processes through a wide range of time and length scales, up to macroscopic dimensions. In the present multiscale approach, dislocation dyna…
The synthesis of ordered mesoporous metal composites and ordered mesoporous metals is a challenge because metals have high surface energies that favor low surface areas. We present results from the self-assembly of block copolymers with ligand-stabilized platinum nanoparticles, leading to lamellar CCM-Pt-4 and inverse…
The chemical synthesis and photoluminescence properties of either dispersed or supported carbogenic nanoparticles are described. In the first case, ionic nanoparticles are obtained by thermal oxidation of an appropriate citrate salt. In the second, carbogenic nanoparticles decorate the external surfaces of zeolite cry…
Graphene has attracted a lot of interest for fundamental studies as well as for potential applications. Till now, micromechanical cleavage (MC) of graphite has been used to produce high-quality graphene sheets on different substrates. Clear understanding of the substrate effect is important for the potential device fa…
The possibility of using ultrasonic waves in the reaction between methylene diphenyl diisocyanate (MDI) and polypropylene glycol (PPG) to create polyurethanes is described in this article. This normally slow reaction without chemical catalysts was found to occur to completion within minutes in the presence of ultrason…
Abstract Thermal degradation of maleic anhydride grafted polyethylene (manPE) in nitrogen and in air was studied by thermogravimetry and differential scanning calorimetry. The decomposition temperature of manPE in nitrogen shifted to a higher value with increasing heating rate, but a complex thermal phenomenon was obs…
Abstract New type of nanocomposites containing various proportions of montmorillonite in aromatic polyamide was prepared via solution intercalation method. Aramid chains were synthesized by reacting 4,4′‐oxydianiline with isophthaloyl chloride in N , N ′‐dimethyl acetamide. Dodecylamine was used as swelling agent to c…
Abstract The crystallization structures of Polypropylene (PP) injection‐molded bars nucleated by nucleating agent were detected from the skin layer to the core zone, layer by layer. α‐phase nucleating agent 1,3:2,4‐bis (3,4‐dimethylbenzylidene) sorbitol (DMDBS, Millad 3988), β‐phase nucleating agent aryl amides compou…