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https://www.readbyqxmd.com/read/29779241/visible-light-driven-chemoselective-hydrogenation-of-nitroarenes-to-anilines-in-water-via-graphitic-carbon-nitride-metal-free-photocatalysis
#1
Gang Xiao, Peifeng Li, Yilin Zhao, Shengnan Xu, Haijia Su
Green and efficient procedures are highly required for the chemoselective hydrogenation of functionalized nitroarenes to industrially important anilines. Here, we show that visible-light-driven, chemoselective hydrogenation of functionalized nitroarenes bearing the sensitive groups to anilines can be achieved in good to excellent yields (82-100%) in water under relatively mild conditions, catalyzed by low-cost and recyclable graphitic carbon nitride. It is also applicable in gram-scale reaction with 86% yield of aniline...
May 20, 2018: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/29779224/ir-catalyzed-silyl-directed-peri-borylation-of-c-h-bonds-in-fused-polycyclic-arenes-and-heteroarenes
#2
Bo Su, John F Hartwig
peri-Disubstituted naphthalenes exhibit interesting physical properties and unique chemical reactivity, due to the parallel arrangement of the bonds to the two peri-disposed substituents. Regioselective installation of a functional group at the position peri to 1-substituted naphthalenes is challenging due to the steric interaction between the existing substituent and the position at which the second one would be installed. We report an iridium-catalyzed borylation of the C-H bond peri to a silyl group in naphthalenes and analogous polyaromatic hydrocarbons...
May 20, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29779079/preparation-and-adsorption-characteristics-for-heavy-metals-of-active-silicon-adsorbent-from-leaching-residue-of-lead-zinc-tailings
#3
Chang Lei, Bo Yan, Tao Chen, Xian-Ming Xiao
To comprehensively reuse the leaching residue obtained from lead-zinc tailings, an active silicon adsorbent (ASA) was prepared from leaching residue and studied as an adsorbent for copper(II), lead(II), zinc(II), and cadmium(II) in this paper. The ASA was prepared by roasting the leaching residue with either a Na2 CO3 /residue ratio of 0.6:1 at 700 °C for 1 h or a CaCO3 /residue ratio of 0.8:1 at 800 °C for 1 h. Under these conditions, the available SiO2 content of the ASA was more than 20%. The adsorption behaviors of the metal ions onto the ASA were investigated and the Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models were used to analyze the adsorption isotherm...
May 19, 2018: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/29778928/how-does-binuclear-zinc-amidohydrolase-fwda-work-in-the-initial-step-of-methanogenesis-from-formate-to-formyl-methanofuran
#4
Xue-Wei Zhang, Shi-Lu Chen
The initial step of methanogenesis is the fixation of CO2 to formyl-methanofuran (formyl-MFR) catalyzed by formyl-MFR dehydrogenase, which can be divided into two half reactions. Herein, the second half reaction catalyzed by FwdA (formyl-methanofuran dehydrogenase subunit A), i.e., from formate to formyl-methanofuran, has been investigated using density functional theory and a chemical model based on the X-ray crystal structure. The calculations indicate that, compared with other well-known di-zinc hydrolases, the FwdA reaction employs a reverse mechanism, including the nucleophilic attack of MFR amine on formate carbon leading to a tetrahedral gem-diolate intermediate, two steps of proton transfer from amine to formate moieties assisted by the Asp385, and the CO bond dissociation to form the formyl-MFR product...
May 11, 2018: Journal of Inorganic Biochemistry
https://www.readbyqxmd.com/read/29778874/simultaneous-determination-of-dihydrotestosterone-and-its-metabolites-in-mouse-sera-by-lc-ms-ms-with-chemical-derivatization
#5
Shashank Gorityala, Shuming Yang, Monica M Montano, Yan Xu
Androgens play a vital role in prostate cancer development, and their elimination and blockade are essential in the disease management. DHT is the key ligand for androgen receptor (AR) in the prostate. It is locally synthesized from testosterone. In the prostate, DHT is predominantly metabolized to α-diol and β-diol. Recent studies indicate that impaired DHT catabolism is associated with prostate cancer, signifying the necessity of a sensitive quantitative method for the determination of DHT and its metabolites...
May 16, 2018: Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences
https://www.readbyqxmd.com/read/29778172/nanoencapsulation-of-hexavalent-chromium-with-nanoscale-zero-valent-iron-high-resolution-chemical-mapping-of-the-passivation-layer
#6
Xiao-Yue Huang, Lan Ling, Wei-Xian Zhang
Solid phase reactions of Cr(VI) with Fe(0) were investigated with spherical-aberration-corrected scanning transmission electron microscopy (Cs-STEM) integrated with X-ray energy-dispersive spectroscopy (XEDS). Near-atomic resolution elemental mappings of Cr(VI)-Fe(0) reactions were acquired. Experimental results show that rate and extent of Cr(VI) encapsulation are strongly dependent on the initial concentration of Cr(VI) in solution. Low Cr loading in nZVI (<1.0wt%) promotes the electrochemical oxidation and continuous corrosion of nZVI while high Cr loading (>1...
May 2018: Journal of Environmental Sciences (China)
https://www.readbyqxmd.com/read/29778146/performance-and-mechanism-of-cr-vi-removal-by-zero-valent-iron-loaded-onto-expanded-graphite
#7
Congbin Xu, Wenjie Yang, Weijiang Liu, Hongliang Sun, Chunlei Jiao, Ai-Jun Lin
Zero-valent iron (ZVI) was loaded on expanded graphite (EG) to produce a composite material (EG-ZVI) for efficient removal of hexavalent chromium (Cr(VI)). EG and EG-ZVI were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and Brunauer-Emmett-Teller (BET) analysis. EG-ZVI had a high specific surface area and contained sub-micron sized particles of zero-valent iron. Batch experiments were employed to evaluate the Cr(VI) removal performance...
May 2018: Journal of Environmental Sciences (China)
https://www.readbyqxmd.com/read/29778073/non-selective-rapid-electro-oxidation-of-persistent-refractory-vocs-in-industrial-wastewater-using-a-highly-catalytic-and-dimensionally-stable-irpd-ti-composite-electrode
#8
Wan-Cheol Cho, Kyung-Min Poo, Hend Omar Mohamed, Tae-Nam Kim, Yul-Seong Kim, Moon Hyun Hwang, Do-Won Jung, Kyu-Jung Chae
Volatile organic compounds (VOCs) are highly toxic contaminants commonly dissolved in industrial wastewater. Therefore, treatment of VOC-containing wastewater requires a robust and rapid reaction because liquid VOCs can become volatile secondary pollutants. In this study, electro-oxidation with catalytic composite dimensionally stable anodes (DSAs)-a promising process for degrading organic pollutants-was applied to remove various VOCs (chloroform, benzene, toluene, and trichloroethylene). Excellent treatment efficiency of VOCs was demonstrated...
May 11, 2018: Chemosphere
https://www.readbyqxmd.com/read/29778028/functional-lignocellulosic-material-for-the-remediation-of-copper-ii-ions-from-water-towards-the-design-of-a-wood-filter
#9
Selin Vitas, Tobias Keplinger, Nico Reichholf, Renato Figi, Etienne Cabane
In this study, the chemical modification of bulk beech wood is described along with its utilization as biosorbent for the remediation of copper from water. The material was prepared by esterification using anhydrides, and reaction conditions were optimized to propose a greener process, in particular by reducing the amount of solvent. This modification yields a lignocellulosic material whose native structure is preserved, with an increased amount of carboxylic groups (up to 3 mmol/g). We demonstrate that the material can remove up to 95% of copper from low concentration solutions (100- 500 ppm)...
May 9, 2018: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/29777591/bioengineering-triacetic-acid-lactone-production-in-yarrowia-lipolytica-for-pogostone-synthesis
#10
James Yu, Jenny Landberg, Farbod Shavarebi, Virginia Bilanchone, Adam Okerlund, Umayangani Wanninayake, Le Zhao, George Kraus, Suzanne Sandmeyer
Yarrowia lipolytica is an oleaginous yeast that is recognized for its ability to accumulate high levels of lipids, which can serve as precursors to biobased fuels and chemicals. Polyketides such as triacetic acid lactone (TAL) can also serve as a precursor for diverse commodity chemicals. This study used Y. lipolytica as a host organism for the production of TAL via expression of the 2-pyrone synthase gene from Gerbera hybrida. Induction of lipid biosynthesis by nitrogen-limited growth conditions increased TAL titers...
May 19, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/29777495/ameliorative-effect-of-ginseng-extract-on-phthalate-and-bisphenol-a-reprotoxicity-during-pregnancy-in-rats
#11
Islam M Saadeldin, Mohamed A Hussein, Aida Hamid Suleiman, Mahmoud G Abohassan, Mona M Ahmed, Amr A Moustafa, Abdullah F Moumen, Ayman Abdel-Aziz Swelum
Phthalates (such as DEHP) and bisphenol A (BPA) are widely used chemicals in plastics manufacturing and exert public health concerns as endocrine disrupters. This study was designed to investigate the deleterious effect of DEHP and BPA on endocrine profile of pregnant female rats and the combined treatment with ginseng extract (Panax ginseng). Seventy-two pregnant rats were divided into six groups (control, ginseng, DEHP, BPA, Gin + DEHP, and Gin + BPA), 12 females per each group. The drugs were supplemented from pregnancy day 0 until day 20...
May 18, 2018: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/29777157/transient-metal-centered-states-mediate-isomerization-of-a-photochromic-ruthenium-sulfoxide-complex
#12
Amy A Cordones, Jae Hyuk Lee, Kiryong Hong, Hana Cho, Komal Garg, Martial Boggio-Pasqua, Jeffrey J Rack, Nils Huse, Robert W Schoenlein, Tae Kyu Kim
Ultrafast isomerization reactions underpin many processes in (bio)chemical systems and molecular materials. Understanding the coupled evolution of atomic and molecular structure during isomerization is paramount for control and rational design in molecular science. Here we report transient X-ray absorption studies of the photo-induced linkage isomerization of a Ru-based photochromic molecule. X-ray spectra reveal the spin and valence charge of the Ru atom and provide experimental evidence that metal-centered excited states mediate isomerization...
May 18, 2018: Nature Communications
https://www.readbyqxmd.com/read/29776721/process-water-properties-from-hydrothermal-carbonization-of-chemical-sludge-from-a-pulp-and-board-mill
#13
Mikko Mäkelä, Julia Forsberg, Christer Söderberg, Sylvia H Larsson, Olli Dahl
Hydrothermal carbonization (HTC) can be used to break down sludge structure and generate carbonaceous hydrochar suitable for solid fuel or value-added material applications. The separation of char and the reaction medium however generates a filtrate, which needs to treated before potential discharge. Thus, this work determined filtrate properties based on HTC temperature and sludge moisture content and estimated the discharge emissions and the potential increase in analyte loads to an industrial wastewater treatment plant based on derived regression models...
May 15, 2018: Bioresource Technology
https://www.readbyqxmd.com/read/29776551/integrated-atomic-layer-deposition-and-chemical-vapor-reaction-for-the-preparation-of-metal-organic-framework-coatings-for-solid-phase-microextraction-arrow
#14
Hangzhen Lan, Leo D Salmi, Tuukka Rönkkö, Jevgeni Parshintsev, Matti Jussila, Kari Hartonen, Marianna Kemell, Marja-Liisa Riekkola
New chemical vapor reaction (CVR) and atomic layer deposition (ALD)-conversion methods were utilized for preparation of metal organic frameworks (MOFs) coatings of solid phase microextraction (SPME) Arrow for the first time. With simple, easy and convenient one-step reaction or conversion, four MOF coatings were made by suspend ALD iron oxide (Fe2 O3 ) film or aluminum oxide (Al2 O3 ) film above terephthalic acid (H2 BDC) or trimesic acid (H3 BTC) vapor. UIO-66 coating was made by zirconium (Zr)-BDC film in acetic acid vapor...
September 18, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29776055/optimal-methylation-noise-for-best-chemotactic-performance-of-e-coli
#15
Subrata Dev, Sakuntala Chatterjee
In response to a concentration gradient of chemoattractant, E. coli bacterium modulates the rotational bias of flagellar motors which control its run-and-tumble motion, to migrate towards regions of high chemoattractant concentration. Presence of stochastic noise in the biochemical pathway of the cell has important consequences on the switching mechanism of motor bias, which in turn affects the runs and tumbles of the cell in a significant way. We model the intracellular reaction network in terms of coupled time evolution of three stochastic variables-kinase activity, methylation level, and CheY-P protein level-and study the effect of methylation noise on the chemotactic performance of the cell...
March 2018: Physical Review. E
https://www.readbyqxmd.com/read/29775934/arsenic-speciation-dynamics-in-paddy-rice-soil-water-environment-sources-physico-chemical-and-biological-factors-a-review
#16
REVIEW
Prasanna Kumarathilaka, Saman Seneweera, Andrew Meharg, Jochen Bundschuh
Rice is the main staple carbohydrate source for billions of people worldwide. Natural geogenic and anthropogenic sources has led to high arsenic (As) concentrations in rice grains. This is because As is highly bioavailable to rice roots under conditions in which rice is cultivated. A multifaceted and interdisciplinary understanding, both of short-term and long-term effects, are required to identify spatial and temporal changes in As contamination levels in paddy soil-water systems. During flooding, soil pore waters are elevated in inorganic As compared to dryland cultivation systems, as anaerobism results in poorly mobile As(V), being reduced to highly mobile As(III)...
April 21, 2018: Water Research
https://www.readbyqxmd.com/read/29775933/observing-hno-3-release-dependent-upon-metal-complexes-in-malonic-acid-nitrate-droplets
#17
Xu Shao, Feng-Min Wu, Hui Yang, Shu-Feng Pang, Yun-Hong Zhang
Although the dicarboxylic acid has been reported to react with nitrate for aged internally mixed aerosols in atmosphere, the quantitative nitrate depletion dependent upon composition in particles is still not well constrained. The chemical composition evolutions for malonic acid/sodium nitrate (MA/SN), malonic acid/magnesium nitrate (MA/MN) and malonic acid/calcium nitrate (MA/CN) particles with the organic to inorganic molar ratio (OIR) of 1:1 are investigated by vacuum Fourier transform infrared spectroscopy (FTIR)...
May 9, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/29775907/hydrothermal-carbonization-of-holocellulose-into-hydrochar-structural-chemical-characteristics-and-combustion-behavior
#18
Fangyan Liu, Ruidong Yu, Xiaodi Ji, Minghui Guo
The main aim of this work was to systematically investigate the effects of time on hydrothermal carbonization of holocellulose coming from the forestry residues. Based on the results, reaction time has a significant impact on the structural, chemical, fuel characteristics and combustion behavior of hydrochars. With increasing reaction time, holocellulose is gradually converted into the amorphous hydrochars with aromatic structure and abundant oxygen-containing functional groups; the O/C and H/C decrease from 0...
May 8, 2018: Bioresource Technology
https://www.readbyqxmd.com/read/29775881/mass-flow-based-removal-and-transformation-potentials-for-tbbpa-hbcds-and-pbdes-during-wastewater-treatment-processes
#19
Un-Jung Kim, Jeong-Eun Oh
At a sewage treatment plant, 27 polybrominated diphenyl ethers, 17 methoxylated brominated diphenyl ethers, nine hydroxylated brominated diphenyl ethers, three hexabromocyclododecane diastereomers, and tetrabromobisphenol A were monitored at five major treatment stages (the influent, primary settlement stage, biological reaction stage, secondary settlement stage, and the UV irradiation disinfection stage). Hexabromocyclododecanes were the dominant chemicals, contributing 40% of the total concentrations of the chemicals in the dissolved phase of the sewage...
April 10, 2018: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/29775319/operando-evidence-for-a-universal-oxygen-evolution-mechanism-on-thermal-and-electrochemical-iridium-oxides
#20
Viktoriia A Saveleva, Li Wang, Detre Teschner, Travis E Jones, Aldo S Gago, K Andreas Friedrich, Spyridon Zafeiratos, Robert Schloegl, Elena R Savinova
Progress in the development of the proton exchange membrane (PEM) water electrolysis technology requires decreasing the anode overpotential, where the sluggish multistep oxygen evolution reaction (OER) occurs. This calls for the understanding of the nature of the active OER sites and reaction intermediates, which are still being debated. In this work, we apply synchrotron radiation - based near ambient pressure X-ray photoelectron and absorption spectroscopies under operando conditions in order to unveil the nature of the reaction intermediates and shed light on the OER mechanism on electrocatalysts most widely used in PEM electrolyzers - electrochemical and thermal iridium oxides...
May 18, 2018: Journal of Physical Chemistry Letters
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