Elastic scattering of electrons by hydrogen molecules

Elastic scattering of electrons by hydrogen molecules has been investigated in the intermediate energy range 100–2000 eV. The direct scattering amplitude consists of first Börn and second Börn minus distortion term. The contribution of exchange has been included through Ochkur approximation. The elastic differential cross-sections agree with experimental data.     

Utilising oleogel as a frying medium for deep fried Indian traditional product (Mathri) to reduce oil uptake

The purpose of this research was to use and analyze the influence of oleogel as a frying medium for developing low fat fried Indian traditional snack (Mathri). As consumer demand for fried foods grows, so does consumer concern about their health, as they are responsible for a variety of health disorders. Carnauba wax and soybean oil were used to produce oleogel in three different concentrations (5, 10 and 15%) which were further examined and used as frying medium. The oleogel effect on the quality attributes of snack were also investigated and compared with the soybean refined oil in this study. It was observed that Mathri fried in oleogel had better moisture retention, color, texture and a lower oil uptake than the Mathri fried in soybean oil. Moisture content in CRW samples ranged from 4 to 5%, but rose to 8.98% in the case of oil samples. Breaking strength of mathri fried in oil was 3382.1 ?g, which was more than the breaking strength of mathri fried in oleogel, which were 1974.8 ?g (5% CRW) and 1092.7 ?g (10% CRW) and 3168.1 ?g (15% CRW). Oleogel fried mathri absorbed 27.7%, 22% and 19.3% less oil than conventionally fried ones. The study shows that mathri with reduced fat and calorie content can be developed to suit the demand among health-conscious consumers for low fatty foods.     

Electroluminescence studies of chemically deposited (Zn‐Cd)S:Cu,F films

Electroluminescence (EL) emission has been observed under AC field excitation in chemically deposited (dipping technique) films of (Zn‐Cd)S:Cu,F using substrates of conducting glass plates. Results of XRD, SEM, absorption spectra, transmission spectra, EL emission spectra, voltage, frequency and temperature dependence and brightness waves of EL brightness are presented and discussed. SEM studies show better growth condition in presence of F. X‐ray diffraction studies show diffraction lines due to CdS and ZnS. Both the studies represent average particle sizes of the order of 1Å. Absorption studies show change in band gap due to increasing concentration of ZnS. The observed EL emission (blue‐green region) may be due to Cu, F combination. Results of transmission spectra give band gap similar to those given by absorption spectra. From voltage dependence of EL brightness acceleration‐collision mechanism is found to be effective. Frequency dependence of EL brightness shows first an increase in brightness in the lower frequency range followed by saturation at higher frequencies. Temperature dependence of EL emission shows a maximum at 40°C. Brightness waves consist of primary and secondary waves, which depend on voltage and frequency of excitation & the ambient temperature. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Glass transition and structural properties of glycidyloxypropyl-heptaphenyl polyhedral oligomeric silsesquioxane-epoxy nanocomposites

We have used molecular simulations to study the properties of nanocomposites formed by the chemical incorporation of polyhedral oligomeric silsesquioxane (POSS) particles in the cross-linked epoxy network. The particular POSS molecule chosen—glycidyloxypropyl-heptaphenyl POSS—can form only one bond with the cross-linker and thus was present as a dangling unit in the network. Four epoxy-POSS nanocomposites containing different fractions (up to 30 mass/%) of POSS particles were studied in this work. Well-relaxed atomistic model structures of the nanocomposites were created and then molecular dynamics simulations were used to characterize the density, glass transition temperature (T _g), and the coefficient of volume thermal expansion (CVTE) of the systems. In addition to the effect of nanoparticle loading, the effect of nanoparticle chemistry on the nanocomposite properties was also characterized by comparing these results with our previous results (Lin and Khare, Macromolecules 42:4319–4327, 2009) on neat cross-linked epoxy and a nanocomposite containing a POSS nanoparticle that formed eight bonds with the cross-linked network. Our results showed that incorporation of these monofunctional POSS particles into cross-linked epoxy does not cause a measurable change in its density, glass transition temperature, or the CVTE. Furthermore, simulation results were used to characterize the aggregation of POSS particles in the system. The nanofiller particles in systems containing 11, 20, and 30 mass/% POSS were found to form small clusters. The cluster-size distribution of nanoparticles was also characterized for these systems.     

Directed Diffusion Approach for Preparing Atomistic Models of Crosslinked Epoxy for Use in Molecular Simulations

A directed diffusion approach is used to create atomistic models of crosslinked epoxy. In polymerization‐based approaches for preparing epoxy model structures, conversions higher than 95% are difficult to achieve due to very slow diffusion of unreacted monomers and crosslinkers in the partially formed network. This problem is overcome by creating very long bonds in the polymerization stage, and then relaxing these to equilibrium values by using a directed‐diffusion‐based relaxation strategy. The method minimizes the use of custom code by relying on the in‐built functionality in LAMMPS package (S. Plimpton, J. Comput. Phys. 1995 , 117, 1). The approach allows for near‐complete conversion (≈99%) and the thermal and volumetric properties of the structures so prepared show good agreement with experimental data.

     

Enhancement in UV emission and band gap by Fe doping in ZnO thin films

Enhancement of the optical band gap of ZnO from 3.14 to 3.29 eV has been obtained using Fe dopant. Undoped and doped ZnO films are deposited by sol-gel spin coating. XRD patterns indicate polycrystalline nature and hexagonal wurtzite structure of Zn_1?xFe_xO films. EDX analysis confirms the presence of iron dopant. The photoluminescence spectra show an ultraviolet emission peak at 398 nm (NBE emission) and defect emission peak at 485 nm. Intensity of the NBE emission is much higher for the doped samples with its ratio to defect emission intensity highest for 2 at. %doping. The NBE emission shifts to higher energy with increasing dopant concentration in a manner similar to that exhibited by the band gap. Surface morphology has been studied using FESEM.     

Faces of Weight Polytopes and a Generalization of a Theorem of Vinberg

The paper is motivated by the study of graded representations of Takiff algebras, cominuscule parabolics, and their generalizations. We study certain special subsets of the set of weights (and of their convex hull) of the generalized Verma modules (or GVM’s) of a semisimple Lie algebra \(\mathfrak{g}\). In particular, we extend a result of Vinberg and classify the faces of the convex hull of the weights of a GVM. When the GVM is finite-dimensional, we answer a natural question that arises out of Vinberg’s result: when are two faces the same? We also extend the notion of interiors and faces to an arbitrary subfield \(\mathbb{F}\) of the real numbers, and introduce the idea of a weak \(\mathbb{F}\)–face of any subset of Euclidean space. We classify the weak \(\mathbb{F}\)–faces of all lattice polytopes, as well as of the set of lattice points in them. We show that a weak \(\mathbb{F}\)–face of the weights of a finite-dimensional \(\mathfrak{g} \)–module is precisely the set of weights lying on a face of the convex hull.