Constructions and applications of rigid spaces,I

The two major results proved are: (1) The category TOP of topological spaces contains a complete nonreflective subcategory. (2) Under the assumption (2^m)⁺ < 2^2m, for each infinite cardinal number m there exists a Hausdorff space of cardinality m, in which the identity map is the only nonconstant continuous self-map. The first result is proved as a consequence of another result which answers a question of Herrlich concerning strongly rigid spaces; it is then used to settle in the negative a conjecture concerning the characterization of reflective subcategories in TOP. In addition, several interesting spaces are constructed.     

Effect of initial conditions on the near-field development of a round jet

This paper examines the effects of using different grids, placed at the nozzle exit plane, on the subsequent development of a subsonic round air jet. Modifications to the initial development of the jet are achieved in a passive manner by placing different grids at the nozzle exit plane. Time-averaged statistics of the velocity, including spectra, are combined with a numerical linear instability investigation. The grids suppress the initial shear layer instability whereas they damp the jet column instability. As a result, the streamwise decay and radial spreading of the perturbed jets are reduced. The instability analysis yields realistic values for the fastest growing instability frequency but incorrect growth rates.     

Enhancing profitability of dry mill ethanol plants

An Aspen Plus™ modeling platform was developed to evaluate the performance of the conversion process of degermed defibered corn (DDC) to ethanol in 15- and 40-million gallons per year (MGPY) dry mill ethanol plants. Upstream corn milling equipment in conventional dry mill ethanol plants was replaced with germ and fiber separation equipment. DDC with higher starch content was fed to the existing saccharification and fermentation units, resulting in higher ethanol productivity than with regular corn. The results of the DDC models were compared with those of conventional dry mill ethanol process models. A simple financial analysis that included capital and operating costs, revenues, earnings, and return on investment was created to evaluate each model comparatively. Case studies were performed on 15- and 40-MGPY base case models with two DDC process designs and DDC with a mechanical oil extraction process.     

Study on the ferromagnetism in Co and N doped ZnO thin films

Present investigation reports the structural, optical and magnetic properties of co-doping of Co and N ions in ZnO samples, prepared by two distinct methods. In the first method, samples are synthesized by Sol–gel technique in which the Co and N are co-doped simultaneously during the growth process itself. In the second case, N ions are implanted in the Co doped ZnO thin films grown by Pulsed Laser Deposition (PLD). Structural studies showed that the nitrogen implantation on Co doped ZnO samples developed compressive stress in the films. X-ray photoelectron spectroscopy confirmed the doping of Co and N in ZnO matrix. In the Resonant Raman scattering multiple LO phonons up to fifth order are observed in the (Co, N) co-doped ZnO. Photoluminescence spectra showed that there is reduction in the bandgap due to the presence of Co in the lattice and also the presence of Zn vacancies in the films. All samples showed ferromagnetic behavior at room temperature. The magnetic moment observed in the implanted films is found to be varied with the different dosages of the implanted N ions. First principle calculations have been carried out to study the possible magnetic interaction in the co-doped system. Present study shows that the ferromagnetic interaction is due to the hybridization between N 2p and Co 3d states in the (Co, N) co-doped ZnO and is very sensitive to the geometrical configurations of dopants and the vacancy in the ZnO host lattice.     

First principles study of structural,electronic, mechanical and thermal properties of A15 intermetallic compounds Ti3X (X=Au,Pt, Ir)

The structural, electronic, elastic, mechanical and thermal properties of Ti₃Au, Ti₃Pt and Ti₃Ir intermetallic compounds crystallizing in A15 structure have been studied using density functional theory within generalized gradient approximation (GGA) for the exchange correlation potential. Elastic properties such as Young's modulus (E), rigidity modulus (G), bulk modulus (B), Poisson's ratio (σ) and elastic anisotropic factor (A) have been calculated. From the present study it is noted that Ti₃Ir is the hardest compound among the three materials studied due to its larger bulk modulus. Also, it is more ductile in nature.     

Dynamics and thermodynamics of water around EcoRI bound to a minimally mutated DNA chain

Water plays an important role in protein-DNA interactions. Here, we examine using molecular dynamics simulations the differences in the dynamic and thermodynamic properties of water in the interfacial and intercalating regions of EcoRI bound to the cognate and to a minimally mutated noncognate DNA chain. The results show that the noncognate complex is not only more hydrated than the cognate complex, but the interfacial waters in the noncognate complex exhibit a faster dynamics, which in turn reduces the hydrogen-bond lifetimes. Thus, the higher hydration, faster reorientation dynamics and faster hydrogen-bond-relaxation times of water, taken together, indicate that, even with a minimal mutation of the DNA sequence, the interfacial regions of the noncognate complex are more poised to allowing the protein to diffuse away than to promoting the formation of a stable complex. Alternatively, the results imply that the slowed water dynamics in the interfacial regions when the protein chances upon a cognate sequence allow the formation of a stable specific protein-DNA complex leading to catalytic action.     

Effects of interfacial modifications on electrical properties of laminar composite dielectrics

The reported work highlights that both polarizibility and quasi-DC conductivity, the two most important parameters for high energy density materials, can be influenced by the surface polarity of an oxide and interfacial surface tension between the oxide and polymer in a laminar composite. Surface modification of laminar composites, composed of thermally grown silica and vapor phase grown Parylene C thin films using organosilanes, was used to control silica surface polarity and interfacial surface tension. Surface polarity of thermally grown silica was found to control the interfacial dipolar energy states.     

Nature of halide binding to the molybdenum site of sulfite oxidase

Valuable information on the active sites of molybdenum enzymes has been provided from both Mo(V) electron paramagnetic resonance (EPR) spectroscopy and X-ray absorption spectroscopy (XAS). One of three major categories of Mo(V) EPR signals from the molybdenum enzyme sulfite oxidase is the low-pH signal, which forms in the presence of chloride. Two alternative structures for this species have been proposed, one in which the chloride is coordinated directly to Mo and a second in which chloride is held in the arginine-rich basic pocket some 5 ? from Mo. Here we present an independent assessment of the structure of this species by using XAS of the analogous bromide and iodide complexes. We show that there is no evidence of direct Mo-I coordination, and that the data are consistent with a structure in which the halide is bound at ～5 ? from Mo.