Removal of Nitrogen Oxides in Diesel Engine Exhaust by Plasma Assisted Molecular Sieves

This paper reports the studies conducted on removal of oxides of nitrogen (NOx) from diesel engine exhaust using electrical discharge plasma combined with adsorbing materials such as molecular sieves. This study is being reported for the first time. The exhaust is taken from a diesel engine of 6 kW under no load conditions. The characteristic behavior of a pulse energized dielectric barrier discharge reactor in the diesel exhaust treatment is reported. The NOx removal was not significant (36%) when the reactor without any packing was used. However, when the reactor was packed with molecular sieves (MS -3A, -4A & -13X), the NOx removal efficiency was increased to 78% particularly at a temperature of 200 °C. The studies were conducted at different temperatures and the results were discussed.

Catalyst-Packed Non-Thermal Plasma Reactor for Removal of Nitrogen Oxides

A single-stage plasma-catalytic reactor in which catalytic materials were packed was used to remove nitrogen oxides. The packing material was scoria being made of various metal oxides including Al2O3, MgO, TiO2, etc. Scoria was able to act not only as dielectric pellets but also as a catalyst in the presence of reducing agent such as ethylene and ammonia. Without plasma discharge, scoria did not work well as a catalyst in the temperature range of 100 °C to 200 °C, showing less than 10% of NOx removal efficiency. When plasma is produced inside the reactor, the NOx removal efficiency could be increased to 60% in this temperature range.

High resolution facies record on late Holocene flood plain sediments from lower reaches of Narmada Valley, Western India

A high resolution quantitative granulometric record for site Uchediya 21A degrees 43'2.22aEuro(3) N, 73A degrees 6'26.22aEuro(3) E; 10 m a. s. l.] gives understanding towards accretion history of the late Holocene flood plain in the lower reaches of Narmada River. Two sediment facies (sandy and muddy) and seven subfacies (sandy subfacies: St(MS+FS+CS), SmFS+MS, Sl(FS+VFS), and St(MS + CS); muddy subfacies: FmSILT+VFS+FS, FmSILT+VFS (O) and FmSILT+VFS (T)) are identified based on cluster analysis supplemented with sedimentary structures observed in field and other laboratory data. Changes in hydrodynamics are further deduced based on various sedimentological parameters and their ratios leading to arrive at a depositional model.

The Effects of Nitrogen Bonding on Hardness of AIN/CrN Multilayer Hard Coatings

AIN/CrN multilayer hard coatings with various bilayer thicknesses were fabricated by a reactive sputtering process. The microstructural and mechanical characterizations of multilayer coatings were investigated through transmission electron microscope (TEM) observations and the hardness measurements by nano indentation. In particular, the variation of chemical bonding states of the bilayer nitrides was elucidated by near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Many broken nitrogen bonds were formed by decreasing the bilayer thickness of AIN/CrN multilayer coatings. Existence of optimum AIN/CrN multilayer coatings thickness for maximum hardness could be explained by the competition of softening by the formation of broken nitrogen bonds and strengthening induced by decreasing bilayer thickness.

Hardness and Nitrogen Bonding Structure of A(x)Ti(1-x)N/CrN Multilayer Hard Coating

AlxTi1-xN/CrN multilayer coatings were fabricated by magnetron sputtering and those hardness variations were studied by observing the crack propagation and measuring the chemical bonding state of nitrides by Ti addition. While AlN/CrN multilayer shown stair-like crack propagation, AlxTi1-xN/CrN multilayer illustrated straight crack propagation. Most interestingly, Ti addition induced more broken nitrogen bonds in the nitride multilayers, leading to the reduction of hardness. However, the hardness of Al0.25Ti0.75N/CrN multilayer, having high Ti contents, increased by the formation of many Ti-N bond again instead of Al-N bond. From these results, we found that linear crack propagation behavior was dominated by broken nitrogen bonds in the AlxT1-xN/CrN multilayer coatings.

A novel oxidative transformation of alcohols to nitriles: an efficient utility of azides as a nitrogen source

An efficient methodology to oxidize benzylic and cinnamyl alcohols to their corresponding nitriles in excellent yields has been developed. This methodology employs DDQ as an oxidant and TMSN3 as a source of nitrogen in the presence of a catalytic amount of Cu(ClO4)(2)center dot 6H(2)O.

Approaches to alpha-amino acids via rearrangement to electron-deficient nitrogen: Beckmann and Hofmann rearrangements of appropriate carboxyl-protected substrates

The titled approaches were effected with various 2-substituted benzoylacetic acid oximes 3 (Beckmann) and 2-substituted malonamic acids 9 (Hofmann), their carboxyl groups being masked as a 2,4,10-trioxaadamantane unit (an orthoacetate). The oxime mesylates have been rearranged with basic Al2O3 in refluxing CHCl3, and the malonamic acids with phenyliodoso acetate and KOH/MeOH. Both routes are characterized by excellent overall yields. Structure confirmation of final products was conducted with X-ray diffraction in selected cases. The final N-benzoyl and N-(methoxycarbonyl) products are alpha-amino acids with both carboxyl and amino protection; hence, they are of great interest in peptide synthesis.

Phylogenetic analysis and molecular dating suggest that hemidactylus anamallensis is not a member of the hemidactylus radiation and has an ancient late cretaceous origin

Background of the Work: The phylogenetic position and evolution of Hemidactylus anamallensis (family Gekkonidae) has been much debated in recent times. In the past it has been variously assigned to genus Hoplodactylus (Diplodactylidae) as well as a monotypic genus `Dravidogecko' (Gekkonidae). Since 1995, this species has been assigned to Hemidactylus, but there is much disagreement between authors regarding its phylogenetic position within this genus. In a recent molecular study H. anamallensis was sister to Hemidactylus but appeared distinct from it in both mitochondrial and nuclear markers. However, this study did not include genera closely allied to Hemidactylus, thus a robust evaluation of this hypothesis was not undertaken. Methods: The objective of this study was to investigate the phylogenetic position of H. anamallensis within the gekkonid radiation. To this end, several nuclear and mitochondrial markers were sequenced from H. anamallensis, selected members of the Hemidactylus radiation and genera closely allied to Hemidactylus. These sequences in conjunction with published sequences were subjected to multiple phylogenetic analyses. Furthermore the nuclear dataset was also subjected to molecular dating analysis to ascertain the divergence between H. anamallensis and related genera. Results and Conclusion: Results showed that H. anamallensis lineage was indeed sister to Hemidactylus group but was separated from the rest of the Hemidactylus by a long branch. The divergence estimates supported a scenario wherein H. anamallensis dispersed across a marine barrier to the drifting peninsular Indian plate in the late Cretaceous whereas Hemidactylus arrived on the peninsular India after the Indian plate collided with the Eurasian plate. Based on these molecular evidence and biogeographical scenario we suggest that the genus Dravidogecko should be resurrected.

Gas Phase Oxygen Quenching Studies of Ketone Tracers for Laser-Induced Fluorescence Applications in Nitrogen Bath Gas

In this paper we report the quantitative oxygen quenching effect on laser-induced fluorescence of acetone, methyl ethyl ketone, and 3-pentanone at low pressures (approximate to 700torr) with oxygen partial pressures up to 450torr. Nitrogen was used as a bath gas in which these molecular tracers were added in different quantities according to their vapor pressure at room temperature. These tracers were excited by using a frequency-quadrupled, Q-switched, Nd:YAG laser (266nm). Stern-Volmer plots were found to be linear for all the tracers, suggesting that quenching is collisional in nature. Stern-Volmer coefficients (k(sv)) and quenching rate constants (k(q)) were calculated from Stern-Volmer plots. The effects of oxygen on the laser-induced fluorescence of acetone, methyl ethyl ketone, and 3-pentanone were compared with each other. Further, the Smoluchowski theory was used to calculate the quenching parameters and compared with the experimental results.

Supercapacitors based on nitrogen-doped reduced graphene oxide and borocarbonitrides

Nitrogen-doped reduced giaphene oxide (RGO) samples with different nitrogen content, prepared by two different methods, as well as nitrogen-doped few-layer graphene have been investigated as supercapacitor electrodes. Two electrode measurements have been carried out both in aqueous (6 M KOH) and in ionic liquid media. Nitrogen-doped reduced graphene oxides exhibit satisfactory specific capacitance, the values reaching 126 F/g at a scan rate of 10 mV/s in aqueous medium. Besides providing supercapacitor characteristics, the study has shown the nitrogen content and surface area to be important factors. High surface-area borocarbonitrides, BxCyNz, prepared by the urea route appear to be excellent supercapacitor electrode materials. Thus, BC4.5N exhibits a specific capacitance of 169 F/g at a scan rate of 10 mV/s in aqueous medium. In an ionic liquid medium, nitrogen-doped RGO and BC4.5N exhibit specific capacitance values of 258 F/g and 240 F/g at a scan rate of 5 mV/s. The ionic liquid enables a larger operating voltage range of 0.0-2.5 V compared to 0.0-1 V in aqueous medium. (C) 2013 Elsevier Ltd. All rights reserved.

Efficient Dendrimer-DNA Complexation and Gene Delivery Vector Properties of Nitrogen-Core Poly(propyl ether imine) Dendrimer in Mammalian Cells

Dendrimers as vectors for gene delivery were established, primarily by utilizing few prominent dendrimer types so far. We report herein studies of DNA complexation efficacies and gene delivery vector properties of a nitrogen-core poly(propyl ether imine) (PETIM) dendrimer, constituted with 22 tertiary amine internal branches and 24 primary amines at the periphery. The interaction of the dendrimer with pEGFPDNA was evaluated through UV-vis, circular dichroism (CD) spectral studies, ethidium bromide fluorescence emission quenching, thermal melting, and gel retardation assays, from which most changes to DNA structure during complexation was found to occur at a weight ratio of dendrimer:DNA similar to 2:1. The zeta potential measurements further confirmed this stoichiometry at electroneutrality. The structure of a DNA oligomer upon dendrimer complexation was simulated through molecular modeling and the simulation showed that the dendrimer enfolded DNA oligomer along both major and minor grooves, without causing DNA deformation, in 1:1 and 2:1 dendrimer-to-DNA complexes. Atomic force microscopy (AFM) studies on dendrimer-pEGFP DNA complex showed an increase in the average z-height as a result of dendrimers decorating the DNA, without causing a distortion of the DNA structure. Cytotoxicity studies involving five different mammalian cell lines, using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide] (MTT) assay, reveal the dendrimer toxicity profile (IC50) values of similar to 400-1000 mu g mL(-1), depending on the cell line tested. Quantitative estimation, using luciferase assay, showed that the gene transfection was at least 100 times higher when compared to poly(ethylene imine) branched polymer, having similar number of cationic sites as the dendrimer. The present study establishes the physicochemical behavior of new nitrogen-core PETIM dendrimer-DNA complexes, their lower toxicities, and efficient gene delivery vector properties.

Metal-metal charge transfer and interfacial charge transfer mechanism for the visible light photocatalytic activity of cerium and nitrogen co-doped TiO2

Nanosized cerium and nitrogen co-doped TiO2 (Ce-TiO2-xNx) was synthesized by sol gel method and characterized by powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), FESEM, Fourier transform infrared, N-2 adsorption and desorption methods, photoluminescence and ultraviolet-visible (UV-vis) DRS techniques. PXRD analysis shows the dopant decreases the crystallite sizes and slows the crystallization of the titania matrix. XPS confirm the existence of cerium ion in +3 or +4 state, and nitrogen in -3 state in Ce-TiO2-xNx. The modified surface of TiO2 provides highly active sites for the dyes at the periphery of the Ce-O-Ti interface and also inhibits Ce particles from sintering. UV-visible DRS studies show that the metal-metal charge transfer (MMCT) of Ti/Ce assembly (Ti4+/Ce3+ -> Ti3+/Ce4+) is responsible for the visible light photocatalytic activity. Photoluminescence was used to determine the effect of cerium ion on the electron-hole pair separation between the two interfaces Ce-TiO2-xNx and Ce2O3. This separation increases with the increase of cerium and nitrogen ion concentrations of doped samples. The degradation kinetics of methylene blue and methyl violet dyes in the presence of sol gel TiO2, Ce-TiO2-xNx and commercial Degussa P25 was determined. The higher visible light activity of Ce-TiO2-xNx was due to the participation of MMCT and interfacial charge transfer mechanism.

Synthesis, properties and applications of graphene doped with boron, nitrogen and other elements

Chemical doping of graphene becomes necessary to create a band gap which is useful for various applications. Furthermore, chemical doping of elements like boron and nitrogen in graphene gives rise to useful properties. Since chemically doped graphene is both of academic and technical importance, we have prepared this article on the present status of various aspects of this important class of materials. In doing so, we have covered the recent literature on this subject citing all the major references. Some of the aspects that we have covered are the synthesis of chemically doped graphene followed by properties and applications. The applications discussed relate to gas adsorption, lithium batteries, supercapacitors, oxygen reduction reaction, field emission and photochemical water splitting. Characterization of chemically doped graphene also included. We believe that the article will be useful to all those interested in graphene and related materials and provides the present status of the subject. (C) 2014 Elsevier Ltd. All rights reserved.

Contrasting geochemical signatures on land from the Middle and Late Permian extinction events

The end of the Palaeozoic is marked by two mass-extinction events during the Middle Permian (Capitanian) and the Late Permian (Changhsingian). Given similarities between the two events in geochemical signatures, such as large magnitude negative C-13 anomalies, sedimentological signatures such as claystone breccias, and the approximate contemporaneous emplacement of large igneous provinces, many authors have sought a common causal mechanism. Here, a new high-resolution continental record of the Capitanian event from Portal Mountain, Antarctica, is compared with previously published Changhsingian records of geochemical signatures of weathering intensity and palaeoclimatic change. Geochemical means of discriminating sedimentary provenance (Ti/Al, U/Th and La/Ce ratios) all indicate a common provenance for the Portal Mountain sediments and associated palaeosols, so changes spanning the Capitanian extinction represent changes in weathering intensity rather than sediment source. Proxies for weathering intensity chemical index of alteration, W and rare earth element accumulation all decline across the Capitanian extinction event at Portal Mountain, which is in contrast to the increased weathering recorded globally at the Late Permian extinction. Furthermore, palaeoclimatic proxies are consistent with unchanging or cooler climatic conditions throughout the Capitanian event, which contrasts with Changhsingian records that all indicate a significant syn-extinction and post-extinction series of greenhouse warming events. Although both the Capitanian and Changhsingian event records indicate significant redox shifts, palaeosol geochemistry of the Changhsingian event indicates more reducing conditions, whereas the new Capitanian record of reduced trace metal abundances (Cr, Cu, Ni and Ce) indicates more oxidizing conditions. Taken together, the differences in weathering intensity, redox and the lack of evidence for significant climatic change in the new record suggest that the Capitanian mass extinction was not triggered by dyke injection of coal-beds, as in the Changhsingian extinction, and may instead have been triggered directly by the Emeishan large igneous province or by the interaction of Emeishan basalts with platform carbonates.