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hydrogen production

Scott J Hughes, Leanne Barnard, Katayoun Mottaghi, Wolfram Tempel, Tetyana Antoshchenko, Bum Soo Hong, Abdellah Allali-Hassani, David Smil, Masoud Vedadi, Erick Strauss, Hee-Won Park
The potent antistaphylococcal activity of N-substituted pantothenamides (PanAms) has been shown to at least partially be due to the inhibition of Staphylococcus aureus's atypical type II pantothenate kinase (SaPanKII), the first enzyme of coenzyme A biosynthesis. This mechanism of action follows from SaPanKII having a binding mode for PanAms that is distinct from those of other PanKs. To dissect the molecular interactions responsible for PanAm inhibitory activity, we conducted a mini SAR study in tandem with the cocrystallization of SaPanKII with two classic PanAms (N5-Pan and N7-Pan), culminating in the synthesis and characterization of two new PanAms, N-Pip-PanAm and MeO-N5-PanAm...
September 9, 2016: ACS Infectious Diseases
Qiufang Gong, Yu Wang, Qi Hu, Jigang Zhou, Renfei Feng, Paul N Duchesne, Peng Zhang, Fengjiao Chen, Na Han, Yafei Li, Chuanhong Jin, Yanguang Li, Shuit-Tong Lee
Earlier research has been primarily focused on WC as one of the most promising earth-abundant electrocatalysts for hydrogen evolution reaction (HER), whereas the other compound in this carbide family-W2C-has received far less attention. Our theoretical calculations suggest that such a focus is misplaced and W2C is potentially more HER-active than WC. Nevertheless, the preparation of phase pure and sintering-free W2C nanostructures represents a formidable challenge. Here we develop an improved carburization method and successfully prepare ultrasmall and phase-pure W2C nanoparticles...
October 18, 2016: Nature Communications
Aníbal M Reyes, Diego S Vazquez, Ari Zeida, Martín Hugo, M Dolores Piñeyro, María Inés De Armas, Darío Estrin, Rafael Radi, Javier Santos, Madia Trujillo
Mycobacterium tuberculosis (M. tuberculosis) is the intracellular bacterium responsible for tuberculosis disease (TD). Inside the phagosomes of activated macrophages, M. tuberculosis is exposed to cytotoxic hydroperoxides such as hydrogen peroxide, fatty acid hydroperoxides and peroxynitrite. Thus, the characterization of the bacterial antioxidant systems could facilitate novel drug developments. In this work, we characterized the product of the gene Rv1608c from M. tuberculosis, which according to sequence homology had been annotated as a putative peroxiredoxin of the peroxiredoxin Q subfamily (PrxQ B from M...
October 14, 2016: Free Radical Biology & Medicine
Jing-Kai Huang, Ying-Chieh Wong, Tzu-Ting Kao, Chen-Tso Tseng, Kak-Shan Shia
A new NHPI/Co(II)-catalyzed protocol, mechanistically involving a sequence of alpha-hydrogen abstraction, 5-exo-dig cyclization, oxygen capture, hydrogen transfer and 1,4-dehydration, has been developed to facilitate aerobic oxidation of aryl-, silyl- and alkyl-capped alkynyl alpha-cyano alkanone systems, respectively, to the corresponding highly functionalized products in an effective manner, thus turning this novel chain reaction, originally occurring spontaneously in low yields, into a practical methodology...
October 17, 2016: Journal of Organic Chemistry
Xin Zhang, Ruyan Wu, Zeyi Wang, Mingxia Gao, Hongge Pan, Yongfeng Liu
Sodium alanate (NaAlH4) has attracted intense interest as a prototypical high-density hydrogen storage material. However, poor reversibility and slow kinetics limit its practical applications. In this work, a nanocrystalline ZrO2@C catalyst is synthesized using Uio-66(Zr) as a precursor and furfuryl alcohol (FA) as a carbon source. The as-synthesized ZrO2@C exhibits good catalytic activity for dehydrogenation and hydrogenation of NaAlH4. The NaAlH4-7 wt% ZrO2@C sample releases hydrogen starting from 126 °C and re-absorbs starting from 54 °C, and these temperatures are reduced by 71 °C and 36 °C, respectively, relative to those of pristine NaAlH4...
October 17, 2016: Chemistry, An Asian Journal
Claudia Weilbeer, Marcel Sickert, Sergej Naumov, Christoph Schneider
We disclose herein the first enantioselective aza-Diels-Alder reaction of b-alkyl-substituted vinylketene silyl-O,O-acetals and imines furnishing a broad range of optically highly enriched 4-alkyl-substituted 2-piperidones. As catalyst for this one-pot reaction we employed a chiral phosphoric acid which effects a vinylogous Mannich reaction directly followed by ring-closure to the lactam. Subsequent fully diastereoselective transformations including hydrogenation, enolate alkylation, and lactam alkylation/reduction processes converted the cycloadducts into various highly substituted piperidines of great utility for the synthesis of natural products and medicinally active compounds...
October 17, 2016: Chemistry: a European Journal
Heng-Jing Hu, Zhi-Sheng Jiang, Sheng-Hua Zhou, Qi-Ming Liu
The effects of hydrogen sulfide (H2S) and the nuclear factor κB (NF-κB) signaling pathway in angiotensin II (AngII)-induced endothelin-1 (ET-1) expression and subsequent cytotoxicity remain unclear. The present study aimed to investigate the hypothesis that H2S protects human umbilical vein endothelial cells (HUVECs) against AngII‑stimulated ET‑1 generation and subsequent cytotoxicity‑induced endoplasmic reticulum stress via the NF‑κB signaling pathway. The results of the present study demonstrated that AngII significantly upregulated the expression levels of ET‑1, glucose‑regulated protein 78, CCAAT‑enhancer‑binding protein homologous protein, phosphorylated (p)‑p65 and inducible nitric oxide synthase; stimulated nitric oxide production; suppressed the expression and activity of cystathionine-γ-lyase (CSE), a H2S synthetase; and decreased cell viability...
October 12, 2016: Molecular Medicine Reports
Akbar Ahmad, Domokos Gerö, Gabor Olah, Csaba Szabo
Hydrogen sulfide (H2S) has been proposed to exert pro- as well as anti-inflammatory effects in various models of critical illness. In this study, we compared bacterial lipopolysaccharide (LPS)‑induced changes in inflammatory mediator production, indices of multiple organ injury and survival in wild‑type (WT) mice and in mice with reduced expression of one of the three H2S‑producing enzymes, cystathionine-γ-lyase (CSE), cystathionine-β-synthase (CBS) or 3-mercaptopyruvate sulfurtransferase (3MST)...
October 14, 2016: International Journal of Molecular Medicine
Alexander von Weber, Scott L Anderson
Mass-selected Ptn(+) ion deposition in ultrahigh vacuum (UHV) was used to prepare a series of size-selected electrodes with Ptn (n ≤ 14) clusters supported on either glassy carbon (GC) or indium tin oxide (ITO). After characterization of the physical properties of the electrodes in UHV, an in situ method was used to study electrocatalytic activity for the oxygen reduction and ethanol oxidation reactions, without significant air exposure. For each reaction studied, there are similarities between the catalytic properties of Ptn-containing electrodes and those of nanoparticulate or bulk Pt electrodes, but there are also important differences that provide mechanistic insights...
October 17, 2016: Accounts of Chemical Research
Thomas F Boudreau, Gregory M Peck, Sean F O'Keefe, Amanda C Stewart
BACKGROUND: Fungicide residues on fruit may adversely affect yeast during cider fermentation, leading to sluggish or stuck fermentation or the production of hydrogen sulfide (H2 S), an undesirable aroma compound. This phenomenon has been studied in grape fermentation, but not in apple fermentation. Low nitrogen availability, characteristic of apples, may further exacerbate the effects of fungicides on yeast during fermentation. This study explored the effects of three fungicides: elemental sulfur (S(0) ), (known to result in increased H2 S in wine), fenbuconazole (used in orchards but not vineyards); and fludioxonil (used in post-harvest storage of apples)...
October 16, 2016: Journal of the Science of Food and Agriculture
Felix Otte, Stephan G Koller, Christopher Golz, Carsten Strohmann
The title compounds, [Sn3(CH3)9(OH)2(H2O)2][Sn(CH3)3(CHO2)2] (1) and [Sn3(CH3)9(OH)2]Cl·H2O (2), are partially condensed products of hydrolysed tri-methyl-tin chloride. In the structures of 1 and 2, short cationic tris-tannatoxanes (C9H29O2Sn3) are bridged by a diformatotri-methyl-tin anion or a chloride anion, respectively. Hydrogen bridges are present and supposedly stabilize these structures against further polymerization to the known polymeric tri-methyl-tin hydroxide. Especially noteworthy is that the formate present in this structure was formed from atmospheric CO2...
October 1, 2016: Acta Crystallographica. Section E, Crystallographic Communications
Darcie L Stack, Jason D Masuda
The title compound, C27H38ClN2(+)·C32H12BF24(-), was synthesized by reacting the product formed from a previous reaction between 1,3-bis-(2,6-diiso-propyl-phen-yl)imidazolinium-2-carboxyl-ate (SIPrCO2), and SOCl2, with sodium tetra-kis-[3,5-bis-(tri-fluoro-meth-yl)phen-yl]borate (NaBARF). In the cation, the imidazole ring is in a half-chair conformation and the formerly carbene carbon atom is bonded in a distorted trigonal-planar geometry with N-C-Cl angles of 122.96 (16) and 122.21 (16)° and an N-C-N angle of 114...
October 1, 2016: Acta Crystallographica. Section E, Crystallographic Communications
Dmitry S Poplevin, Fedor I Zubkov, Pavel V Dorovatovskii, Yan V Zubavichus, Victor N Khrustalev
The isomeric title compounds, C12H13NO4 (Ia) and C12H13NO4 (IIa), the products of an usual thermal C6-epimerization of 5-oxo-1,2,3,5,5a,6,7,9b-octa-hydro-7,9a-ep-oxy-pyrrolo-[2,1-a]iso-indole-6-carb-oxy-lic acid, represent the two different diastereomers and have very similar mol-ecular geometries. The mol-ecules of both compounds comprise a fused tetra-cyclic system containing four five-membered rings (pyrrolidine, pyrrolidinone, di-hydro-furan and tetra-hydro-furan), all of which adopt the usual envelope conformations...
October 1, 2016: Acta Crystallographica. Section E, Crystallographic Communications
Giles Major, Sue Pritchard, Kathryn Murray, Jan Paul Alappadan, Caroline Hoad, Luca Marciani, Penny Gowland, Robin Spiller
BACKGROUND & AIMS: Poorly digested, fermentable carbohydrates may induce symptoms of irritable bowel syndrome (IBS), via unclear mechanisms. We performed a randomized trial with magnetic resonance imaging (MRI) analysis to investigate correlations between symptoms and changes in small and large bowel contents following oral challenge. METHODS: We performed a 3-period crossover study of 29 adult patients with IBS (based on Rome III criteria, with symptoms of abdominal pain or discomfort for at least 2 days/week) and reported bloating...
October 13, 2016: Gastroenterology
Petra Martini, Alessandra Boschi, Gianfranco Cicoria, Licia Uccelli, Micòl Pasquali, Adriano Duatti, Gaia Pupillo, Mario Marengo, Massimo Loriggiola, Juan Esposito
The design and fabrication of a fully-automated, remotely controlled module for the extraction and purification of technetium-99m (Tc-99m), produced by proton bombardment of enriched Mo-100 molybdenum metallic targets in a low-energy medical cyclotron, is here described. After dissolution of the irradiated solid target in hydrogen peroxide, Tc-99m was obtained under the chemical form of (99m)TcO4(-), in high radionuclidic and radiochemical purity, by solvent extraction with methyl ethyl ketone (MEK). The extraction process was accomplished inside a glass column-shaped vial especially designed to allow for an easy automation of the whole procedure...
October 5, 2016: Applied Radiation and Isotopes
Hao Meng, Yuan Liu, Bruce P Lee
: Mussel adhesive moiety, catechol, has been utilized to design a wide variety of biomaterials. However, the biocompatibility and biological responses associated with the byproducts generated during the curing process of catechol has never been characterized. An in situ curable polymer model system, 4-armed polyethylene glycol polymer end-capped with dopamine (PEG-D4), was used to characterize the production of hydrogen peroxide (H2O2) during the oxidative crosslinking of catechol. Although PEG-D4 cured rapidly (under 30s), catechol continues to polymerize over several hours to form a more densely crosslinked network over time...
October 12, 2016: Acta Biomaterialia
Shulin Zhuang, Xuan Lv, Liumeng Pan, Liping Lu, Zhiwei Ge, Jiaying Wang, Jingpeng Wang, Jinsong Liu, Weiping Liu, Chunlong Zhang
Benzotriazole ultraviolet stabilizers (BUVSs) are prominent chemicals widely used in industrial and consumer products to protect against ultraviolet radiation. They are becoming contaminants of emerging concern since their residues are frequently detected in multiple environmental matrices and their toxicological implications are increasingly reported. We herein investigated the antiandrogenic activities of eight BUVSs prior to and after human CYP3A4-mediated metabolic activation/deactivation by the two-hybrid recombinant human androgen receptor yeast bioassay and the in vitro metabolism assay...
October 12, 2016: Environmental Pollution
Natalie C Sadler, Hans C Bernstein, Matthew R Melnicki, Moiz A Charania, Eric A Hill, Lindsey N Anderson, Matthew E Monroe, Richard D Smith, Alexander S Beliaev, Aaron T Wright
: Photobiologically synthesized hydrogen (H2) gas is carbon-neutral to produce and clean to combust, making it an ideal biofuel. Cyanothece sp. ATCC 51142 is a cyanobacterium capable of performing simultaneous oxygenic photosynthesis and H2 production, a highly perplexing phenomenon because H2 evolving enzymes are O2-sensitive. We employed a systems-level in vivo chemoproteomic profiling approach to explore the cellular dynamics of protein thiol redox, and how thiol redox mediates the function of the dinitrogenase NifHDK, an enzyme complex capable of aerobic hydrogenase activity...
October 14, 2016: Applied and Environmental Microbiology
Abdulla Al Masum, Maharudra Chakraborty, Soumen Ghosh, Dipranjan Laha, Parimal Karmakar, Md Maidul Islam, Subrata Mukhopadhyay
Interaction of CT DNA with Rhodamine 6G (R6G) has been studied using molecular docking, electrochemical, spectroscopic and thermodynamic methods. From the study, it was illustrated that Rhodamine 6G binds to the minor groove of CT DNA. The binding was cooperative in nature. Circular voltametric study showed significant change in peak current and peak potential due to complexation. All the studies showed that the binding constant was in the order of 10(6)M(-1). Circular dichroic spectra showed significant conformational change on binding and DNA unwind during binding...
October 6, 2016: Journal of Photochemistry and Photobiology. B, Biology
Wolfgang W Schoeller, Guido D Frey
The oxidative addition of π- and σ-bonds is studied by means of quantum chemical investigations at a MCSCF and density functional level of sophistication. The title compound (AlNacNac) induces first-order strong donor-acceptor abilities in the triplet state, giving rise to biradicaloid adducts. At second-order, it reveals carbene character. The energy barriers for the 1,2-addition reactions are fairly small, resulting from an oxidative addition, which differs from the classical 1,2-addition reaction of a carbene to an olefin...
October 14, 2016: Inorganic Chemistry
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