Computational spectroscopy and DFT investigations into nitrogen and oxygen bond breaking and bond making processes in model deNOx and deN2O reactions

Molecular DFT modeling combined with computational spectroscopy (EPR and IR) were applied for analysis of the NO bond breaking and NN and OO bond making in the context of deNO_x and deN₂O reactions. Interaction of NO, N₂O and NO₂ with cationic (transition metals) and anionic (surface O²⁻ ions) centers was explored at the molecular level. The elementary events such as reactant coordination, charge and spin redistributions, which are principal molecular constraints for efficient decomposition of the nitrogen oxides (N₂O and NO) were discussed. Particular attention was paid to dynamics of the NO bond cleavage in N₂O molecule through electron and oxygen atom transfer routes, evaluation of preferable coordination modes of NO, discrimination between inner- and outer-sphere mechanism of NN bond formation, and the influence of spin and electronic redistribution on the reaction course (spin catalysis). Owing to their simplicity and well known surface chemistry, model systems selected for studies of such processes include MoO_x/SiO₂, MgO and ZSM-5 zeolite exchanged with various transition metal ions (TMI) of different electron configuration and spin multiplicity: Mo⁵⁺ (d¹, ²D) Fe³⁺, Mn²⁺, Cr⁺ (d⁵, ⁶S), Fe²⁺ (d⁶, ⁵D), Co²⁺ (d⁷, ⁴F), Ni²⁺ (d⁸, ³F), Cu²⁺ (d⁹, ²D) and Cu⁺, Zn²⁺ (d¹⁰, ¹S).     

Modeling of Flow System Dynamics

This paper presents non-linear and linear models of flow system of laboratory stand (semi-industrial scale) with pressurized fluidized bed boiler. The non-linear model belongs to the class of lumped parameter models. The linear model was obtained experimentally using a novel method for design of control systems in industrial plants - MIKOZ. This study has connection with comparison of various methods of mathematical modeling of flow systems frequently encountered in power equipment.     

Hydrodenitrogenation of indole over Mo2C catalyst: Insights into mechanistic events through DFT modeling

The molecular reaction mechanism of hydrodenitrogenation of indole was studied using density-functional theory calculations of the adsorbed o-ethylaniline surrounded by mobile hydrogen atoms. It was found that the hydrogenation of o-ethylaniline occurs through two steps: consisting in redistribution of the π electron density to form multiple partial MoC(ring) bonds with the surface upon adsorption, and a subsequent hydrogen attack directed on the aromatic ring or the amine group. The direction of the hydrogen attack and the associated energy barriers determine the rate constants of the early (DDN, direct denitrogenation) and late (HYD, hydrogenation) nitrogen removal steps, and thus rules the selectivity of indole hydrodenitrogenation to ethylcyclohexane or ethylbenzene.     

Liquid fuels from canadian peat by the waterloo fast pyrolysis process

Two Canadian peats from Quebec were pyrolyzed using the Waterloo Fast Pyrolysis Process (WFPP) technology with the objective of maximizing liquid yields. A young sphagnum peat (Sogovex) gave maximum yields of organic-liquids (moisture free basis) of 45% to 47% in an optimum range of 450° to 550°C at atmospheric pressure. Char yields decreased from 35% to 26% and gas yields increased from 12% to 17% over this range. The character of the liquid product changed significantly over the optimum temperature range, with the ratio of water-soluble to water-insoluble components decreasing from 2.3 to 0.6, with an accompanying decrease in oxygen content. Pyrolysis tests using an old black peat (Premier) gave similar results, although with some what lower yields of organic liquids and higher char yields. Upgrading tests on the peat oil done under hydrodeoxygenation conditions in collaboration with Battelle PNWL resulted in a yield of about 33% of the liquid feed as a gasoline-like liquid.     

High-Temperature Electrical Insulation Behavior of Alumina Films Prepared at Room Temperature by Aerosol Deposition and Influence of Annealing Process and Powder Impurities

Alumina (Al₂O₃) is a widely used material for highly insulating films due to its very low electrical conductivity, even at high temperatures. Typically, alumina films have to be sintered far above 1200 °C, which precludes the coating of lower melting substrates. The aerosol deposition method (ADM), however, is a promising method to manufacture ceramic films at room temperature directly from the ceramic raw powder. In this work, alumina films were deposited by ADM on a three-electrode setup with guard ring and the electrical conductivity was measured between 400 and 900 °C by direct current measurements according to ASTM D257 or IEC 60093. The effects of film annealing and of zirconia impurities in the powder on the electrical conductivity were investigated. The conductivity values of the ADM films correlate well with literature data and can even be improved by annealing at 900 °C from 4.5?×?10^?12 S/cm before annealing up to 5.6?×?10^?13 S/cm after annealing (measured at 400 °C). The influence of zirconia impurities is very low as the conductivity is only slightly elevated. The ADM-processed films show a very good insulation behavior represented by an even lower electrical conductivity than conventional alumina substrates as they are commercially available for thick-film technology.     

Brain dynamics in spider-phobic individuals exposed to phobia-relevant and other emotional stimuli.

[Correction Notice: An erratum for this article was reported in Vol 9(4) of Emotion (see record 2009-11528-006). This article contained an incorrect DOI for the supplemental materials. The correct DOI is as follows: http://dx.doi.org/10.1037/a0015550.supp.] Dense sensor event-related brain potentials were measured in participants with spider phobia and nonfearful controls during viewing of phobia-relevant spider and standard emotional (pleasant, unpleasant, neutral) pictures. Irrespective of the picture content, spider phobia participants responded with larger P1 amplitudes than controls, suggesting increased vigilance in this group. Furthermore, spider phobia participants showed a significantly enlarged early posterior negativity (EPN) and late positive potential (LPP) during the encoding of phobia-relevant pictures compared to nonfearful controls. No group differences were observed for standard emotional materials indicating that these effects were specific to phobia-relevant material. Within group comparisons of the spider phobia group, though, revealed comparable EPN and LPP evoked by spider pictures and emotional (unpleasant and pleasant) picture contents. These results demonstrate a temporal unfolding in perceptual processing from unspecific vigilance (P1) to preferential responding (EPN and LPP) to phobia-relevant materials in the spider phobia group. However, at the level of early stimulus processing, these effects of increased attention seem to be related to emotional relevance of the stimulus cues rather than reflecting a fear-specific response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis and characterisation of enhanced barrier polyurethane for encapsulation of implantable medical devices

Polymeric membranes have been used as interfaces between implantable devices and biological tissues to operate as a protective barrier from water exchanging and to enhance biocompatibility. Polyurethanes have been used as biocompatible membranes for decades. In this study, copolymers of polyether urethane (PEU) with polydimethylsiloxane (PDMS) were synthesised with the goal of creating materials with low water permeability and high elasticity. PDMS was incorporated into polymer backbone as a part of the soft segment during polyurethane synthesis and physical properties as well as water permeability of resulting copolymer were studied in regard to PDMS content. Increase in PDMS content led to increase of microphase separation of the copolymer and corresponding increase in elastic modulus. Surface energy of the polymer was decreased by incorporating PDMS compared to unmodified PEU. PDMS in copolymer formed a hydrophobic surface which caused reduction in water permeability and water uptake of the membranes. Thus, PDMS containing polyurethane with its potent water resistant properties demonstrated a great promise for use as an implantable encapsulation material.     

Effect of Operating Temperature on Water‐Based Oil Sands Processing

Operating temperature is one of the most important controlling parameters in oil sands processing. Considering the massive energy consumption and green house gas emission, lowering the processing temperature is highly desirable. To achieve such an ambitious goal requires a comprehensive understanding on the role of temperature in oil sands processing. This paper provides an overview of major findings from existing studies related to oil sands processing temperature. The relation between temperature and bitumen recovery is discussed. The effect of temperature on the physiochemical properties of oil sand components, such as bitumen viscosity, bitumen surface tension and surface potentials of bitumen and solids, is analyzed. The interactions between bitumen and solids and between bitumen and gas bubbles as a function of temperature are recounted. Also discussed is the role of chemical additives in oil sand processing. It has been found that temperature affects nearly all properties of oil sands among which bitumen viscosity and bitumen‐solids adhesion impose a prominent impact on bitumen recovery. The use of selected chemical additives can reduce bitumen viscosity and/or the bitumen‐solids adhesion, and thus provide a possible way to process oil sands at a low temperature while maintaining a high bitumen recovery.     

Influence of Heat Treatment of Electrospun Carbon Nanofibers on Biological Response

The main aim of this study is to investigate the effect of fragmentation of electrospun carbon nanofibers (eCNFs) obtained at different temperatures, i.e., at 750 °C, 1000 °C, 1500 °C, 1750 °C and 2000 °C on the cellular response in vitro. In order to assess the influence of nanofibers on biological response, it was necessary to conduct physicochemical, microstructural and structural studies such as SEM, XPS, Raman spectroscopy, HRTEM and surface wettability of the obtained materials. During the in vitro study, all samples made contact with the human chondrocyte CHON-001 cell lines. The key study was to assess the genotoxicity of eCNFs using the comet test after 1 h or 24 h. Special attention was paid to the degree of crystallinity of the nanofibers, the dimensions of the degradation products and the presence of functional groups on their surface. A detailed analysis showed that the key determinant of the genotoxic effect is the surface chemistry. The presence of nitrogen-containing groups as a product of the decomposition of nitrile groups has an influence on the biological response, leading to mutations in the DNA. This effect was observed only for samples carbonized at lower temperatures, i.e., 750 °C and 1000 °C. These results are important with respect to selecting the temperature of thermal treatment of eCNFs dedicated for medical and environmental functions due to the minimization of the genotoxic effect of these materials.