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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...
May 24, 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, Helene Jamet, Vincent Niviere, 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 Fe3+-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 Fe3+ OOH intermediate, at different level of theory. This was performed on the whole system (solvated protein) using well-tempered metadynamics at the QM/MM (B3LYP/AmberFF99SB) level...
May 16, 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...
April 19, 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
Karen Busk Nørøxe, Linda Huibers, Grete Moth, Peter Vedsted
BACKGROUND: Optimal utilisation of the out-of-hours primary care (OOH-PC) services remains a concern in public health policy. We need more knowledge on potentially avoidable contacts. This study examines the frequency of medically assessed inappropriate OOH-PC calls from adults, explores factors associated with such assessment, and examines the relation to patient-assessed severity of health problem and fulfilment of expectations. METHODS: We performed secondary analyses of data from a large cross-sectional survey on contacts to Danish OOH-PC...
March 14, 2017: BMC Family Practice
Tarali Devi, Yong-Min Lee, Jieun Jung, Muniyandi Sankaralingam, Wonwoo Nam, Shunichi Fukuzumi
Metal-superoxo species are involved in a variety of enzymatic oxidation reactions, and multi-electron oxidation of substrates is frequently observed in those enzymatic reactions. A Cr(III) -superoxo complex, [Cr(III) (O2 )(TMC)(Cl)](+) (1; TMC=1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), is described that acts as a novel three-electron oxidant in the oxidation of dihydronicotinamide adenine dinucleotide (NADH) analogues. In the reactions of 1 with NADH analogues, a Cr(IV) -oxo complex, [Cr(IV) (O)(TMC)(Cl)](+) (2), is formed by a heterolytic O-O bond cleavage of a putative Cr(II) -hydroperoxo complex, [Cr(II) (OOH)(TMC)(Cl)], which is generated by hydride transfer from NADH analogues to 1...
March 7, 2017: Angewandte Chemie
Filipe Natalio, Stefanie Wiese, Wolfgang Brandt, Ludger Wessjohann
Boron's unusual properties inspired major advances in chemistry. In nature, the existence and importance of boron has been fairly explored (e.g. bacterial signaling, plant development) but its role as biological catalyst was never reported. Here, we show that boric acid [B(OH)3 ] can restore chloroperoxidase activity of Curvularia inaequalis recombinant apo-haloperoxidase's (HPO) in the presence of hydrogen peroxide and chloride ions. Molecular modeling and semi-empirical PM7 calculations support a thermodynamically highly favored (bio)catalytic mechanism similarly to vanadium haloperoxidases (V-HPO) in which [B(OH)3 ] is assumedly located in apo-HPO's active site and a monoperoxyborate [B(OH)3 (OOH)(-) ] intermediate is formed and stabilized by interaction with specific active site amino acids leading ultimately to the formation of HOCl...
March 1, 2017: Chemistry: a European Journal
Kenta Arai, Ayako Tashiro, Yuui Osaka, Michio Iwaoka
We previously reported that water-soluble cyclic selenides can mimic the antioxidative function of glutathione peroxidase (GPx) in water through a simple catalytic cycle, in which the selenide (>Se) is oxidized by H₂O₂ to the selenoxide (>Se=O) and the selenoxide is reduced by a thiol back to the selenide. In methanol, however, the GPx-like activity could not be explained by this simple scenario. To look into the reasons for the unusual behaviors in methanol, monoamino-substituted cyclic selenides with a variable ring size were synthesized, and the intermediates of the catalytic cycle were characterized by means of (77)Se-NMR and LC-MS spectroscopies...
February 25, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Padmaja Krishnan, Minghui Liu, Pierre A Itty, Zhi Liu, Vanessa Rheinheimer, Min-Hong Zhang, Paulo J M Monteiro, Liya E Yu
Consecutive eight study phases under the successive presence and absence of UV irradiation, water vapor, and oxygen were conducted to characterize surface changes in the photocatalytic TiO2 powder using near-ambient-pressure X-ray photoelectron spectroscopy (XPS). Both Ti 2p and O 1s spectra show hysteresis through the experimental course. Under all the study environments, the bridging hydroxyl (OHbr) and terminal hydroxyl (OHt) are identified at 1.1-1.3 eV and 2.1-2.3 eV above lattice oxygen, respectively...
February 27, 2017: Scientific Reports
Naoki Shimizu, Hannah Bersabe, Junya Ito, Shunji Kato, Ryo Towada, Takahiro Eitsuka, Shigefumi Kuwahara, Teruo Miyazawa, Kiyotaka Nakagawa
Squalene (SQ), a main component of human sebum, is readily photooxidized by exposure to sunlight, producing six squalene monohydroperoxide (SQ-OOH) isomers. Despite its known connection to various skin conditions, few studies have sought to analyze SQ-OOH at the isomeric level. In this study, we aimed to develop a method to discriminate each SQ-OOH isomer with the use of tandem mass spectrometry (MS/MS). The six standard SQ-OOH isomers were prepared by photooxidizing SQ in the presence of rose bengal, a photosensitizer, and isolated by semipreparative high-performance liquid chromatography (HPLC)...
February 10, 2017: Journal of Oleo Science
Hasse C Knap, Solvejg Jørgensen
We have used quantum mechanical chemical calculations (CCSD(T)-F12a/cc-pVDZ-F12//M06-2X/aug-cc-pVTZ) to investigate the hydrogen shift (H-shift) reactions in acyl peroxy and hydroperoxy acyl peroxy radicals. We have focused on the H-shift reactions from a hydroperoxy group (OOH) (1,X-OOH H-shift with X = 6, 7, 8, or 9) in the hydroperoxy acyl peroxy radicals, this H-shift is a reversible reaction and it scrambles between two peroxides, hydroperoxy acyl peroxy and peroxy peroxoic acid radicals. The forward reaction rate constants of the 1,X-OOH H-shift reactions are estimated to be above 10(3) s(-1) with transition state theory corrected with Eckart quantum tunnelling correction...
February 13, 2017: Journal of Physical Chemistry. A
Nathalie Ségaud, Constance De Thomasson, Caroline Daverat, Katell Sénéchal-David, Amandine Dos Santos, Vincent Steinmetz, Philippe Maître, Jean-Noël Rebilly, Frédéric Banse, Olivia Reinaud
A heteroditopic ligand associated with a calix[6]arene scaffold bearing a tris(imidazole) coordinating site at its small rim and an amine/pyridine ligand at its large rim has been prepared, and its regioselective coordination to Zn(II) at the small rim and Fe(II) in the amine/pyridine ligand has been achieved. The heterodinuclear complex obtained displays an overall cone conformation capped by the tris(imidazole)Zn(II) moiety and bears a non-heme Fe(II) complex at its base. Each of the metal centers exhibits one labile position, allowing the coordination inside the cavity of a guest alkylamine at Zn(II) and the generation of reaction intermediates (Fe(III) (OOH) and Fe(IV) O) at the large rim...
February 24, 2017: Chemistry: a European Journal
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