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Tristan Asset, Raphael Chattot, Jakub Drnec, Pierre Bordet, Nathalie Job, Frédéric Maillard, Laetitia Dubau
The oxygen reduction reaction (ORR) activity of Pt-alloy electrocatalysts depends on (i) strain/ligand effects induced by the non-noble metal (3d transition metal or a rare-Earth ele-ment) alloyed to Pt, (ii) the orientation of the catalytic surfaces and (iii) the density of struc-tural defects (ex. vacancies, voids, interconnections). These structural defects influence the 'generalized' coordination number of Pt atoms, the Pt-alloy lattice parameter and thus the adsorption strength of the ORR intermediates (O*, OH*, OOH*)...
June 26, 2017: ACS Applied Materials & Interfaces
Guttorm Raknes, Steinar Hunskaar
BACKGROUND: Frequencies of reasons for encounter (RFEs) in emergency primary care out-of-hours (OOH) services are relevant for planning of capacities as well as to target the training of staff at casualty clinics. We aimed to present frequencies of RFEs in the different organ systems, and to identify the most frequent RFEs at different urgency levels. METHODS: We analyzed data on RFEs in Norwegian OOH services. International Classification of Primary Care (ICPC-2) RFE codes were recorded in all contacts to eight representative OOH casualty clinics in 2014 and 2015 covering 20 municipalities with a total population of 260 196...
June 24, 2017: BMC Emergency Medicine
Natav Yatom, Yuval Elbaz, Shelly Navon, Maytal Caspary Toroker
Hematite's (α-Fe2O3) major limitation to efficiently splitting water using sunlight is the low rate of the oxygen evolution reaction (OER). Thus, identifying the OER rate limiting step is a cornerstone to enhancing the current under low applied potential. Different measurement techniques showed similar absorption difference spectra during a change in applied potential on the hematite anode below and above the onset of the OER in the dark and under light. This absorption change was shown to result from surface modification during the OER, but the specific surface species could not be resolved...
June 22, 2017: Physical Chemistry Chemical Physics: PCCP
Shaohong Liu, Zhiyu Wang, Si Zhou, Fengjiao Yu, Mengzhou Yu, Chang-Yang Chiang, Wuzong Zhou, Jijun Zhao, Jieshan Qiu
The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are cornerstone reactions for many renewable energy technologies. Developing cheap yet durable substitutes of precious-metal catalysts, especially the bifunctional electrocatalysts with high activity for both ORR and OER reactions and their streamlined coupling process, are highly desirable to reduce the processing cost and complexity of renewable energy systems. Here, a facile strategy is reported for synthesizing double-shelled hybrid nanocages with outer shells of Co-N-doped graphitic carbon (Co-NGC) and inner shells of N-doped microporous carbon (NC) by templating against core-shell metal-organic frameworks...
June 19, 2017: Advanced Materials
Yuqian Liu, Xiuyun Cao, Hui Li, Zijun Zhou, Siyang Wang, Zhicong Wang, Chunlei Song, Yiyong Zhou
Phosphorus (P) fractionation and sorption behavior as well as the abundance and community composition of phosphorus-solubilizing bacteria (PSB) in sediments, including inorganic phosphate-solubilizing bacteria (IPB) and organic phosphate-mineralizing bacteria (OPB), were investigated in 27 sampling sites of five sections in the Three Gorges Reservoir (TGR) in December 2012. The calcium-bound phosphorus (CaCO3∼P) accounted for the largest part for P fractions in the sediment of TGR, which was paralleled with IPB outnumbering OPB...
June 9, 2017: Environmental Science and Pollution Research International
J F Ebert, L Huibers, F K Lippert, B Christensen, M B Christensen
BACKGROUND: Out-of-hours (OOH) health care for acute medical problems is often challenged by long waiting time for callers in need of advice and triage. Allowing patients to bypass the OOH telephone waiting line may increase patient satisfaction and provide them with a feeling of safety. We aimed to develop an "emergency access button" enabling patients to bypass the normal telephone waiting line in out-of-hours primary care (OOH-PC) if they perceive their condition to be critical and to evaluate the effect of introducing the button in terms of patient satisfaction and their feeling of safety...
May 31, 2017: BMC Health Services Research
Bishnu Thapa, H Bernhard Schlegel
Acid dissociation constants (pKa's) are key physicochemical properties that are needed to understand the structure and reactivity of molecules in solution. Theoretical pKa's have been calculated for a set of 72 organic compounds with -OH and -OOH groups (48 with known experimental pKa's). This test set includes 17 aliphatic alcohols, 25 substituted phenols, and 30 hydroperoxides. Calculations in aqueous medium have been carried out with SMD implicit solvation and three hybrid DFT functionals (B3LYP, ωB97XD, and M06-2X) with two basis sets (6-31+G(d,p) and 6-311++G(d,p))...
June 8, 2017: Journal of Physical Chemistry. A
Xuqiang Ji, Shuai Hao, Fengli Qu, Jingquan Liu, Gu Du, Abdullah M Asiri, Liang Chen, Xuping Sun
The exploration of high-performance and earth-abundant water oxidation catalysts operating under mild conditions is highly attractive and challenging. In this communication, core-shell CoFe2O4@Co-Fe-Bi nanoarray on carbon cloth (CoFe2O4@Co-Fe-Bi/CC) was successfully fabricated by in situ surface amorphization of CoFe2O4 nanoarray on CC (CoFe2O4/CC). As a 3D water oxidation electrode, CoFe2O4@Co-Fe-Bi/CC shows outstanding activity with an overpotential of 460 mV to drive a geometrical catalytic current density of 10 mA cm(-2) in 0...
May 31, 2017: Nanoscale
Andrea Posocco, Maria Paola Scapinello, Irene De Ronch, Francesco Castrogiovanni, Gianluca Lollo, Guglielmo Sergi, Iginio Tomaselli, Loris Tonon, Marco Solmi, Daniele Pescador, Elena Battistuz, Stefano Traversa, Vincenzo Zambianco, Nicola Veronese
Out of hours (OOH) doctors can have an important gate-keeping role over the access to the emergency department (ED), but the outcome and the quality of their ED referrals have been poorly studied. We aimed to investigate the outcome of patients referred to ED from OOH service and the determinants of admission or short-stay dispositions. We collected retrospectively data about referrals to ED from a local OOH service in the north-east of Italy using the OOH paper register and the ED electronic database, over the period of 01/10/2012 to 31/03/2013...
May 25, 2017: Internal and Emergency Medicine
Cristina Ortega-Moo, Rocio Durán, Bárbara Herrera, Soledad Gutiérrez-Oliva, Alejandro Toro-Labbé, Rubicelia Vargas
Phenolic compounds represent an important category of antioxidants because they help inhibit the oxidation process of organic compounds, while also acting as antiradicals in many biological processes. In this work, we analyze the transfer mechanisms for a set of catechols and resorcinols of a single electron, proton and hydrogen, with the radical peroxyl (˙OOH) and with different electron withdrawing and donating groups as substituents. By using the M05-2X exchange correlation functional within the Density Functional Theory framework combined with the 6-311++G(d,p) basis set, we were able to compute the Gibbs free energies for all mechanisms and compounds...
June 7, 2017: Physical Chemistry Chemical Physics: PCCP
Niels H Bennike, Claus Zachariae, Jeanne D Johansen
BACKGROUND: For cosmetics, it is mandatory to label 26 fragrance substances, including all constituents of fragrance mix I (FM I) and fragrance mix II (FM II). Earlier reports have not included oxidized R-limonene [hydroperoxides of R-limonene (Lim-OOH)] and oxidized linalool [hydroperoxides of linalool (Lin-OOH)], and breakdown testing of FM I and FM II has mainly been performed in selected, mix-positive patients. OBJECTIVES: To report the prevalence of sensitization to the 26 fragrances, and to assess concomitant reactivity to FM I and/or FM II...
May 16, 2017: Contact Dermatitis
Rolf David, Hélène Jamet, Vincent Nivière, Yohann Moreau, Anne Milet
Superoxide reductase is a mononuclear iron enzyme involved in superoxide radical detoxification in some bacteria. Its catalytic mechanism is associated with the remarkable formation of a ferric hydroperoxide Fe(3+)-OOH intermediate, which is specifically protonated on its proximal oxygen to generate the reaction product H2O2. Here, we present a computational study of the protonation mechanism of the Fe(3+)-OOH intermediate, at different levels of theory. This was performed on the whole system (solvated protein) using well-tempered metadynamics at the QM/MM (B3LYP/AmberFF99SB) level...
May 30, 2017: Journal of Chemical Theory and Computation
Min Ma, Fengli Qu, Xuqiang Ji, Danni Liu, Shuai Hao, Gu Du, Abdullah M Asiri, Yadong Yao, Liang Chen, Xuping Sun
There is an urgent demand to develop earth-abundant electrocatalysts for efficient and durable water oxidation under mild conditions. A nickel-substituted cobalt-borate nanowire array is developed on carbon cloth (Ni-Co-Bi/CC) via oxidative polarization of NiCo2 S4 nanoarray in potassium borate (K-Bi). As a bimetallic electrocatalyst for water oxidation, such Ni-Co-Bi/CC is superior in catalytic activity and durability in 0.1 m K-Bi (pH: 9.2), with a turnover frequency of 0.33 mol O2 s(-1) at the overpotential of 500 mV and nearly 100% Faradaic efficiency...
May 16, 2017: Small
Hejdi Gamst-Jensen, Freddy K Lippert, Ingrid Egerod
BACKGROUND: Telephone consultation and triage are used to limit the workload on emergency departments. Lack of visual cues and clinical tests put telephone consultations to a disadvantage compared to face-to-face consultations increasing the risk of under-triage. Under-triage occurs in telephone triage; however why under-triage happens is not explored yet. The aim of the study was to describe situations of under-triage in context, to assess the quality of under-triaged calls, and to identify communication patterns contributing to under-triage in a regional OOH service in the capital region of Denmark...
May 15, 2017: Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine
Daniel T Bregante, David W Flaherty
Group IV and V framework-substituted zeolites have been used for olefin epoxidation reactions for decades, yet the underlying properties that determine the selectivities and turnover rates of these catalysts have not yet been elucidated. Here, a combination of kinetic, thermodynamic, and in situ spectroscopic measurements show that when group IV (i.e., Ti, Zr, and Hf) or V (i.e., Nb and Ta) transition metals are substituted into zeolite *BEA, the metals that form stronger Lewis acids give greater selectivities and rates for the desired epoxidation pathway and present smaller enthalpic barriers for both epoxidation and H2O2 decomposition reactions...
May 9, 2017: Journal of the American Chemical Society
Federico Calle-Vallejo, Alexander Krabbe, Juan M García-Lastra
It is known that breaking the scaling relations between the adsorption energies of *O, *OH, and *OOH is paramount in catalyzing more efficiently the reduction of O2 in fuel cells and its evolution in electrolyzers. Taking metalloporphyrins as a case study, we evaluate here the adsorption energies of those adsorbates on the metal centers Cr, Mn, Fe, Co, Ni and Cu, using H, F, OH, NH2, CH3, and BH2 as ring ligands. We show that covalence systematically breaks scaling relations under vacuum by strengthening certain M-OOH bonds...
January 1, 2017: Chemical Science
Emma L D'Ambro, Kristian H Møller, Felipe D Lopez-Hilfiker, Siegfried Schobesberger, Jiumeng Liu, John E Shilling, Ben Hwan Lee, Henrik G Kjaergaard, Joel A Thornton
We report chamber measurements of secondary organic aerosol (SOA) formation from isoprene photochemical oxidation, in which radical concentrations were systematically varied and the molecular composition of semi- to low-volatility gases and SOA were measured online. Using a detailed chemical kinetics box model, we find that to explain the behavior of low-volatility products and SOA mass yields relative to input H2O2 concentrations, the second-generation dihydroxy hydroperoxy peroxy radical (C5H11O6·) must undergo an intramolecular H-shift with a net forward rate constant of order 0...
May 2, 2017: Environmental Science & Technology
Qian Yao, Xiao-Hui Sun, Ze-Rong Li, Fang-Fang Chen, Xiang-Yuan Li
Intramolecular H-migration reaction of hydroperoxyalkylperoxy radicals ((•)O2QOOH) is one of the most important reaction families in the low-temperature oxidation of hydrocarbon fuels. This reaction family is first divided into classes depending upon H atom transfer from -OOH bonded carbon or non-OOH bonded carbon, and then the two classes are further divided depending upon the ring size of the transition states and the types of the carbons from which the H atom is transferred. High pressure limit rate rules and pressure-dependent rate rules for each class are derived from the rate constants of a representative set of reactions within each class using electronic structure calculations performed at the CBS-QB3 level of theory...
April 13, 2017: Journal of Physical Chemistry. A
D V Yanykin, A A Khorobrykh, V V Terentyev, V V Klimov
Earlier the catalase-insensitive formation of organic hydroperoxides (via the interaction of organic radicals produced due to redox activity of P680(+·) (or TyrZ(·)) with molecular oxygen) has been found in Mn-depleted PS2 preparations (apo-WOC-PS2) by Khorobrykh et al. (Biochemistry 50:10658-10665, 2011). The present work describes a second pathway of the photoproduction of organic peroxides on the donor side of PS2. It was shown that illumination of CaCl2-treated PS2 membranes (deprived of the PS2 extrinsic proteins without removal of the Mn-containing water-oxidizing complex) (CaCl2-PS2) led to the photoproduction of highly lipophilic organic hydroperoxides (LP-OOH) (in amount corresponding to 1...
March 27, 2017: Photosynthesis Research
Shuo Li, Zhansheng Lu, Yi Zhang, Dongwei Ma, Zongxian Yang
Hydrogen peroxide (H2O2) is an important chemical commodity, with demand growing significantly in chemical synthesis due to its green characteristics. The mechanisms of the direct synthesis of hydrogen peroxide (DSHP) on metal-free silicon and phosphorus dual-doped graphene (Si-P-G) catalyst, based on a dispersion-corrected density functional theory (DFT-D) method, are systematically investigated. The most stable Si-P-G catalyst is presented, with the local region of dopants shown to play an important role in the adsorption and reduction of oxygen...
March 17, 2017: Physical Chemistry Chemical Physics: PCCP
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