Insights into the mechanism of Nitrobenzene reduction to aniline over Pt catalyst and the significance of the adsorption of phenyl group on kinetics

Aniline (C6H5NH2) plays a significant role in both industry and daily life, and can be synthesized via catalytic hydrogenation of nitrobenzene (C6H5NO2) over transition metals; however fundamental investigations on reaction mechanisms in the heterogeneous catalysis are still lacking. In this work, the nitrobenzene reduction reaction over the Pt(111) model catalyst was studied using density functional theory (DFT) with the inclusion of van der Waals interaction, for fundamentally understanding the mechanisms at atomic and molecular levels. It was found that the double H-induced dissociation of N-O bond was the preferential path for the activation of nitro group, having a much lower reaction barrier than that of the direct dissociation and single H-induced dissociation paths. The overall mechanisms have been identified as: C6H5NO2* → C6H5NOOH* → C6H5N(OH)2* → C6H5NOH* → C6H5NHOH* → C6H5NH* → C6H5NH2*. The overall barrier of the nitro group reduction was calculated to be 0.75 eV, which is much lower than that of the benzene reduction (1.08 eV). Our DFT data elucidates clearly the reason why the major product of nitrobenzene reduction reaction was aniline. Furthermore, the adsorption/desorption of phenyl group was found to have significant impacts on kinetic barriers. Generally, in the hydrogenation process (N-H or O-H bond association), the phenyl group preferred to adsorb on the surface; but in the dissociation process (N-O bond dissociation) it preferred to desorb transiently at the transition state and to adsorb again when the dissociation was completed. This study also provides a solid theoretical insight into the selective catalysis of the large aromatic compounds

The technology of career guidance activity within interregional interdepartmental project «Trans - ural navigator»

Рассматриваются современные технологии профориентационной деятельности, уделяется внимание профориентационному ресурсу чемпионатов WorldskillsThe article tells about modern technologies of career guidance activity, pays attention to career guidance resource of Worldskill

DNA-Interacting Characteristics of the Archaeal Rudiviral Protein SIRV2_Gp1

Whereas the infection cycles of many bacterial and eukaryotic viruses have been characterized in detail, those of archaeal viruses remain largely unexplored. Recently, studies on a few model archaeal viruses such as SIRV2 (Sulfolobus islandicus rod-shaped virus) have revealed an unusual lysis mechanism that involves the formation of pyramidal egress structures on the host cell surface. To expand understanding of the infection cycle of SIRV2, we aimed to functionally characterize gp1, which is a SIRV2 gene with unknown function. The SIRV2_Gp1 protein is highly expressed during early stages of infection and it is the only protein that is encoded twice on the viral genome. It harbours a helix-turn-helix motif and was therefore hypothesized to bind DNA. The DNA-binding behavior of SIRV2_Gp1 was characterized with electrophoretic mobility shift assays and atomic force microscopy. We provide evidence that the protein interacts with DNA and that it forms large aggregates, thereby causing extreme condensation of the DNA. Furthermore, the N-terminal domain of the protein mediates toxicity to the viral host Sulfolobus. Our findings may lead to biotechnological applications, such as the development of a toxic peptide for the containment of pathogenic bacteria, and add to our understanding of the Rudiviral infection cycle.status: publishe

Secondary metabolites of <i>Xylaria</i> sp., an endophytic fungus from <i>Taxus mairei</i>

<p>One new metabolite 3,7-dimethyl-9-(-2,2,5,5-tetramethyl-1,3-dioxolan-4-yl)nona-1,6-dien-3-ol, together with nine known compounds, were isolated from the strain <i>Xylaria</i> sp., an endophytic fungus of <i>Taxus mairei</i>. Their structures were deduced from 1D and 2D NMR data. In vitro cytotoxicity and antibacterial activity of these compounds were evaluated. Some of them exhibited substantial activity.</p

Insights into reaction mechanisms of ethanol electrooxidation at the Pt/Au(111) interfaces using density functional theory

Understanding ethanol electrooxidation reaction kinetics is fundamental to the development of direct ethanol fuel cells. The utilization of binary PtAu catalysts has been reported recently as an effective strategy to enhance ethanol electrocatalytic oxidation; however, the catalytic reaction mechanisms are still unclear. In this work, we systematically studied the ethanol electrooxidation reaction mechanisms on Pt/Au(111) model surfaces at an atomic level through high level density functional theory (DFT) calculations; particularly the flat (111) terrace and the stepped (111) × (110) and (111) × (100) interfaces with diverse surface atomic arrangements were considered, respectively. It was found that for ethanol dissociation, the flat (111) terrace is more active than the stepped (111) × (110) and (111) × (100) interfaces. The stepped interfaces, however, could activate water from the aqueous electrolyte solution to form adsorbed OH* at the electrode potential below 0.53 V vs. SHE (standard hydrogen electrode), which is of great importance in coupling with the CH3CO* intermediate formed from ethanol dissociation to produce acetic acid as the final product of the ethanol electrooxidation reaction without releasing CO2. The C–C bond splitting process for ethanol oxidation to form C1 products was very limited. The terrace sites can facilitate both ethanol decomposition and acetic acid formation at the electrode potential above 0.53 V vs. SHE. Our results clearly identify the fact that for ethanol electrooxidation reactions, with an increase in electrode potential, the active sites on Pt/Au(111) surfaces change from those at the stepped interfaces to the flat terrace sites.</p

Brain areas showing different activations after lose trials among WIN, LOSS, and TIE situations.

<p>Upper: Comparisons among WIN, LOSS and TIE conditions after loss trials. Bottom: The Beta figures in Insula, ACC, and SFG in lose trials in different situations.</p

Regional brain activity changes in different comparisons

a<p>Peak MNI Coordinates.</p>b<p>Number of voxels. <i>p</i><0.01 FWE corrected and at least 30 voxels. Voxel size = 3*3*3.</p>c<p>The brain regions were referenced to the software Xjview (<a href="http://www.alivelearn.net/xjview8" target="_blank">http://www.alivelearn.net/xjview8</a>) and double checked with atlas.</p

Brain areas showing different activations after win trials among WIN, LOSS, and TIE situations.

<p><b>Upper</b>: Higher activation is found in posterior cingulate cortex in LOSS to TIE condition. No difference was found in other comparisons. <b>Bottom</b>: Beta figures in PCC in win trials in different situations.</p

Correlations between brain activations and self report experience.

<p><b>a</b>) Correlation between brain activations in insula and the participants' experiences to lose in WIN condition. <b>b</b>) Correlation between brain activations in insula and the participants' experiences to lose in LOSS condition. <b>c</b>) Correlation between brain activations in SFG and the participants' craving for win in WIN condition. <b>d</b>) Correlation between brain activations in SFG and the participants' craving for win in LOSS condition. <b>e</b>) Correlation between brain activations in ACC and the participants' experiences to lose in LOSS condition. <b>f</b>) Correlation between brain activations in PCC and the participants' experiences to lose in LOSS condition.</p

The timeline of one trial in present task.

<p>First, the backsides of two playing cards were shown and participants were asked to choose either the right or the left card with a button press. After 1.5(red playing cards, including the heart and diamond J, Q, K) or lost (black playing cards; including the spade and club J, Q, K) 10 Yuan.</p