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https://www.readbyqxmd.com/read/28927165/air-and-surface-sampling-method-for-assessing-exposures-to-quaternary-ammonium-compounds-using-liquid-chromatography-tandem-mass-spectrometry
#1
Ryan F LeBouf, Mohammed Abbas Virji, Anand Ranpara, Aleksandr B Stefaniak
This method was designed for sampling select quaternary ammonium (quat) compounds in air or on surfaces followed by analysis using ultraperformance liquid chromatography tandem mass spectrometry. Target quats were benzethonium chloride, didecyldimethylammonium bromide, benzyldimethyldodecylammonium chloride, benzyldimethyltetradecylammonium chloride, and benzyldimethylhexadecylammonium chloride. For air sampling, polytetrafluoroethylene (PTFE) filters are recommended for 15-min to 24-hour sampling. For surface sampling, Pro-wipe® 880 (PW) media was chosen...
July 1, 2017: Annals of Work Exposures and Health
https://www.readbyqxmd.com/read/28926961/effects-of-metal-ions-temperature-and-a-denaturant-on-the-oxidative-folding-pathways-of-bovine-%C3%AE-lactalbumin
#2
Reina Shinozaki, Michio Iwaoka
Bovine α-lactalbumin (αLA) has four disulfide (SS) bonds in the native form (N). On the oxidative folding pathways of this protein, two specific SS folding intermediates, i.e., (61-77, 73-91) and des[6-120], which have two and three native SS bonds, respectively, accumulate predominantly in the presence of Ca(2+). In this study, we reinvestigated the pathways using a water-soluble cyclic selenoxide reagent, trans-3,4-dihydroxyselenolane oxide (DHS(ox)), as a strong and quantitative oxidant to oxidize the fully reduced form (R)...
September 16, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28926823/preparation-characterization-and-application-of-urease-nanoparticles-for-construction-of-an-improved-potentiometric-urea-biosensor
#3
Seema Jakhar, C S Pundir
The nanoparticles (NPs) aggregates of commercial urease from jack beans (Canavalia ensiformis) were prepared by desolvation and glutaraldehyde crosslinking and functionalized by cysteamine dihydrochloride. These enzyme nanoparticles (ENPs) were characterized by transmission electron microscopy (TEM), UV and Fourier transform infrared (FTIR) spectroscopy. The TEM images of urease NPs showed their size in the range, 18-100nm with an average of 51.2nm. The ENPs were more active and stable with a longer shelf life than native enzyme molecules...
September 6, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28926790/migration-and-distribution-of-sodium-ions-and-organic-matters-during-electro-dewatering-of-waste-activated-sludge-at-different-dosages-of-sodium-sulfate
#4
Jun Xiao, Xu Wu, Wenbo Yu, Sha Liang, Jiangwei Yu, Yueyuan Gu, Huali Deng, Jiukun Hu, Keke Xiao, Jiakuan Yang
In this study, the influence of Na2SO4 on electro-dewatering (EDW) of waste activated sludge (WAS) was investigated. The highest water removal efficiency of 42.5% was achieved at the optimum Na2SO4 dosage of 12.5 g kg(-1) DS during EDW process at a constant voltage of 20 V. The migration and distribution of water, organic matters and Na(+) at different Na2SO4 dosages were investigated through layered experiments. The results indicated the entire EDW process followed the S curve model, and it can be divided into three stages: (1) initial desalination stage: at the initial few min of EDW process, the rate of electroosmosis was extremely slow while electromigration of ions like Na(+) was intense, and the electromigration was more obvious with increased Na2SO4 dosage; (2) dewatering stage: the dewatering efficiency increased dramatically via electroosmosis; (3) the dewaterability limit stage: the maximum value of dewatering efficiency has been achieved, while the water removal efficiency and dry solids content remained constant...
September 9, 2017: Chemosphere
https://www.readbyqxmd.com/read/28926788/study-of-the-degradation-process-of-ofloxacin-with-free-chlorine-by-using-esi-lcmsms-kinetic-study-by-products-formation-pathways-and-fragmentation-mechanisms
#5
Montaha H Yassine, Ahmad Rifai, Maha Hoteit, Patrick Mazellier, Mohammad Al Iskandarani
This study was conducted to gain a better understanding of the fate of fluoroquinolone antibacterial ofloxacin (OFX) which is the free available chlorine (FAC) in order to determine its effect during water chlorination process. The Direct reactions of FAC with OFX were quite rapid. A half-life of 7.7 s was measured under pseudo-first order conditions in the presence of an excess of total chlorine ([FAC]0 = 13 μM and [OFX]0 = 0.55 μM at pH 7.2 and 20 °C in buffered reagent water. Free chlorine reactions rates were of first-order type in both substrate and oxidant with specific second-order rate constants of 6...
September 4, 2017: Chemosphere
https://www.readbyqxmd.com/read/28926757/mn-ii-based-t1-and-t2-potential-mri-contrast-agent-appended-with-tryptamine-recognition-moiety-for-a%C3%AE-plaques
#6
Neeraj Rastogi, Nidhi Tyagi, Ovender Singh, B S Hemanth Kumar, Udai P Singh, Kaushik Ghosh, Raja Roy
We report the synthesis and characterization of manganese(II) complexes having pentadentate ligands L1 (2,6-bis(1-(2-phenyl-2-(pyridin-2-yl)hydrazono)ethyl)pyridine), L2 (methyl 2,6-bis((E)-1-(2-phenyl-2-(pyridin-2yl)hydrazono)ethyl)isonicotinate), L3 (N-(2-(1H-indol-3-yl)ethyl)-2,6-bis((E)-1-(2-phenyl-2-(pyridin2yl)hydrazono)ethyl)isonicotiamide) and their application as dual contrast agents for simultaneous T1 and T2 weighted magnetic resonance imaging. Single crystal analysis of all the complexes [Mn(II)L1, Mn(II)L2 and Mn(II)L3] confirm the formation of novel seven-coordinate manganese complexes with an inner sphere water and perchlorate ion...
September 5, 2017: Journal of Inorganic Biochemistry
https://www.readbyqxmd.com/read/28926723/porous-wo3-graphene-polyester-textile-electrode-materials-with-enhanced-electrochemical-performance-for-flexible-solid-state-supercapacitors
#7
Li-Na Jin, Ping Liu, Chun Jin, Jia-Nan Zhang, Shao-Wei Bian
In this work, a flexible and porous WO3/grapheme/polyester (WO3/G/PT) textile electrode was successfully prepared by in situ growing WO3 on the fiber surface inside G/PT composite fabrics. The unique electrode structure facilitates to enhance the energy storage performance because the 3D conductive network constructed by the G/PT increase the electron transportation rate, nanotructured WO3 exposed enhanced electrochemically active surface area and the hierarchically porous structure improved the electrolyte ion diffusion rate...
September 1, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28926712/pyrophosphate-release-in-the-protein-hiv-reverse-transcriptase
#8
Murat Atiş, Kenneth A Johnson, Ron Elber
Enzymatic reactions usually occur in several steps: A step of substrate binding to the surface of the protein, a step of protein re-organization around the substrate and conduction of a chemical reaction, and a step of product release. The release of inorganic phosphate - PPi - from the matrix of the protein HIV reverse transcriptase is investigated computationally. Atomically detailed simulations with explicit solvent are analyzed to obtain the free energy profile, mean first passage time, and detailed molecular mechanisms of PPi escape...
September 19, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28926707/medieval-gilding-technology-of-historical-metal-threads-revealed-by-electron-optical-and-micro-raman-spectroscopic-study-of-focused-ion-beam-milled-cross-sections
#9
Tamás Gábor Weiszburg, Katalin Gherdán, Kitti Ratter, Norbert Zajzon, Zsolt Bendő, György Z Radnoczi, Ágnes Takács, Tamás Váczi, Gábor Varga, György Szakmány
Although gilt silver threads were widely used for decorating historical textiles, their manufacturing techniques have been elusive for centuries. Contemporary written sources give only limited, sometimes ambiguous information, and detailed cross-sectional study of the microscale soft noble metal objects has been hindered by sample preparation. In this work, to give a thorough characterization of historical gilt silver threads, nano- and microscale textural, chemical and structural data on cross sections, prepared by focused ion beam milling, were collected, using various electron-optical methods (high-resolution scanning electron microscopy (SEM), wavelength-dispersive electron probe microanalysis (EPMA), electron back-scattered diffraction (EBSD) combined with energy-dispersive electron probe microanalysis (EDX), transmission electron microscopy (TEM) combined with EDX, and micro-Raman spectroscopy...
September 19, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28926698/quantification-of-lignin-and-its-structural-features-in-plant-biomass-using-13-c-lignin-as-internal-standard-for-pyrolysis-gc-sim-ms
#10
Gijs van Erven, Ries de Visser, Donny W H Merkx, Willem Strolenberg, Peter De Gijsel, Harry Gruppen, Mirjam A Kabel
Understanding mechanisms underlying plant biomass recalcitrance at molecular level can only be achieved by accurate analyses of both content and structural features of the molecules involved. Current quantification of lignin is, however, majorly based on unspecific gravimetric analysis after sulphuric acid hydrolysis. Hence, our research aimed at specific lignin quantification with concurrent characterization of its structural features. Hereto, for the first time, a polymeric (13)C lignin was used as internal standard (IS) for lignin quantification via analytical pyrolysis coupled to gas chromatography with mass-spectrometric detection in selected ion monitoring mode (py-GC-SIM-MS)...
September 19, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28926697/copper-inhibits-the-alkb-family-dna-repair-enzymes-under-wilson-s-disease-condition
#11
Ke Bian, Fangyi Chen, Zachary T Humulock, Qi Tang, Deyu Li
Disturbed metabolism of copper ions can cause diseases, such as Wilson's disease (WD). In this work, we investigated the inhibi-tory effect of Cu(II) ion on the AlkB family DNA repair enzymes in vitro, which are members of the Fe(II)/alpha-ketoglutarate-dependent dioxygenase and include human ALKBH2, ALKBH3, and E. coli AlkB proteins. None of the three proteins were significantly inhibited under normal cellular copper concentrations. But under WD related condition, we observed the activities of all three enzymes were strongly suppressed (from 95...
September 19, 2017: Chemical Research in Toxicology
https://www.readbyqxmd.com/read/28926691/cobalt-porphyrin-thiazyl-radical-coordination-polymers-towards-metal-organic-electronics
#12
Delia A Haynes, Laura J van Laeren, Orde Q Munro
Herein we delineate an unusual one-dimensional coordination polymer (CP), 3, prepared from S = ½ Co(TPP), 1, (TPP = 5,10,15,20-tetraphenylporphyrin dianion) and S = ½ 4-(4'-pyridyl)-1,2,3,5-dithiadiazolyl (py-DTDA) radical, 2. The atypically long S-S distance for CP 3 (2.12 Å) reflects fractional electron transfer from the formally Co(II) ion into the antibonding π-SOMO of the metal-bound py-DTDA bridging ligand. The bonding in solid CP 3 involves non-integer redox states in a resonance hybrid repeat unit best formulated as [Co(TPP)](0...
September 19, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28926688/covalent-triazine-frameworks-via-a-low-temperature-polycondensation-approach
#13
Kewei Wang, Liming Yang, Xi Wang, Liping Guo, Guang Cheng, Chun Zhang, Shangbin Jin, Bien Tan, Andrew Cooper
Covalent triazine frameworks (CTFs) are normally synthesized by ionothermal methods. The harsh synthetic conditions and associated limited structural diversity do not benefit for further development and practical large-scale synthesis of CTFs. Herein we report a new strategy to construct CTFs (CTF-HUSTs) via a polycondensation approach, which allows the synthesis of CTFs under mild conditions from a wide array of building blocks. Interestingly, these CTFs display a layered structure. The CTFs synthesized were also readily scaled up to gram quantities...
September 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28926687/advanced-nanostructured-anode-materials-for-sodium-ion-batteries
#14
REVIEW
Qidi Wang, Chenglong Zhao, Yaxiang Lu, Yunming Li, Yuheng Zheng, Yuruo Qi, Xiaohui Rong, Liwei Jiang, Xinguo Qi, Yuanjun Shao, Du Pan, Baohua Li, Yong-Sheng Hu, Liquan Chen
Sodium-ion batteries (NIBs), due to the advantages of low cost and relatively high safety, have attracted widespread attention all over the world, making them a promising candidate for large-scale energy storage systems. However, the inherent lower energy density to lithium-ion batteries is the issue that should be further investigated and optimized. Toward the grid-level energy storage applications, designing and discovering appropriate anode materials for NIBs are of great concern. Although many efforts on the improvements and innovations are achieved, several challenges still limit the current requirements of the large-scale application, including low energy/power densities, moderate cycle performance, and the low initial Coulombic efficiency...
September 19, 2017: Small
https://www.readbyqxmd.com/read/28926394/armd-and-presumed-dangerous-commentary-on-an-article-by-gulraj-s-matharu-bsc-hons-mrcs-mres-et-al-blood-metal-ion-thresholds-to-identify-patients-with-metal-on-metal-hip-implants-at-risk-of-adverse-reactions-to-metal-debris-an-external-multicenter-validation
#15
https://www.readbyqxmd.com/read/28926383/mri-findings-in-patients-after-small-head-metal-on-metal-total-hip-arthroplasty-with-a-minimum-follow-up-of-10-years
#16
Tobias Reiner, Thuy D Do, Matthias C Klot, Fabian Hertzsch, Kirsten Seelmann, Matthias M Gaida, Marc-André Weber, Tobias Gotterbarm
BACKGROUND: Concern has been raised about the late onset of adverse reactions to metal debris (ARMD) in patients with a small-head metal-on-metal total hip replacement. The aims of this study were to assess the frequency and characteristic appearance of ARMD in patients with a small-head (28-mm) metal-on-metal total hip replacement and elevated blood ion levels (>1 μg/L) after a minimum follow-up of 10 years and to analyze the possible risk factors associated with the prevalence of these lesions...
September 20, 2017: Journal of Bone and Joint Surgery. American Volume
https://www.readbyqxmd.com/read/28926382/blood-metal-ion-thresholds-to-identify-patients-with-metal-on-metal-hip-implants-at-risk-of-adverse-reactions-to-metal-debris-an-external-multicenter-validation-study-of-birmingham-hip-resurfacing-and-corail-pinnacle-implants
#17
Gulraj S Matharu, Fiona Berryman, Andrew Judge, Aleksi Reito, Jamie McConnell, Olli Lainiala, Stephen Young, Antti Eskelinen, Hemant G Pandit, David W Murray
BACKGROUND: The authors of recent studies have reported newly devised implant-specific blood metal ion thresholds to predict adverse reactions to metal debris (ARMD) in patients who have undergone unilateral or bilateral metal-on-metal (MoM) hip arthroplasty. These thresholds were most effective for identifying patients at low risk of ARMD. We investigated whether these newly devised blood metal ion thresholds could effectively identify patients at risk of ARMD after MoM hip arthroplasty in an external cohort of patients...
September 20, 2017: Journal of Bone and Joint Surgery. American Volume
https://www.readbyqxmd.com/read/28926256/conductivity-relaxation-relations-in-nanocomposite-polymer-electrolytes-containing-ionic-liquid
#18
Mansoureh Shojaatalhosseini, Khalid Elamin, Jan Swenson
In this study we have used nonocomposite polymer electrolytes, consisting of poly(ethylene oxide) (PEO), δ-Al2O3 nanoparticles and lithium bis(trifluoromethanesolfonyl)imide (LiTFSI) salt (with 4 wt% δ-Al2O3 and PEO:Li ratios of 16:1 and 8:1), and added different amounts of the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesolfonyl)imide (BMITFSI). The aim was to elucidate whether the ionic liquid is able to dissociate the Li-ions from the ether oxygens and thereby decouple the ionic conductivity from the segmental polymer dynamics...
September 19, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28926231/resonance-emission-enhancement-ree-for-narrow-band-red-emitting-a2gef6-mn-4-a-na-k-rb-cs-phosphors-synthesized-via-a-precipitation-cation-exchange-route
#19
Hongzhou Lian, Qingming Huang, Yeqing Chen, Kai Li, Sisi Liang, Mengmeng Shang, Manman Liu, Jun Lin
Narrow band red-emitting A2GeF6:Mn(4+) (A = Na, K, Rb, Cs) phosphors were prepared through a two-step precipitation-cation exchange route using a K2MnF6 precursor as the Mn(4+) source. The phase purity, morphology, and constituent were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectric spectroscopy (XPS), and electron paramagnetic resonance (EPR) examination. Optical properties were investigated by photoluminescence spectra (PL and PLE) and high-resolution PL. A temperature-dependent PL examination was performed to investigate the electron-phonon coupling emission mechanism of Mn(4+) in these alkali fluorogermanates...
September 19, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28926230/formation-and-characterization-of-hydrogen-boride-sheets-derived-from-mgb2-by-cation-exchange
#20
Hiroaki Nishino, Takeshi Fujita, Nguyen Thanh Cuong, Satoshi Tominaka, Masahiro Miyauchi, Soshi Iimura, Akihiko Hirata, Naoto Umezawa, Susumu Okada, Eiji Nishibori, Asahi Fujino, Tomohiro Fujimori, Shin-Ichi Ito, Junji Nakamura, Hideo Hosono, Takahiro Kondo
Two-dimensional (2D) materials are promising for applications in a wide range of fields because of their unique properties. Hydrogen boride sheets, a new 2D material recently predicted from theory, exhibit intriguing electronic and mechanical properties as well as hydrogen storage capacity. Here, we report the experimental realization of 2D hydrogen boride sheets with an empirical formula of H1B1, produced by exfoliation and complete ion-exchange between protons and magnesium cations in magnesium diboride (MgB2) with an average yield of 42...
September 19, 2017: Journal of the American Chemical Society
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