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Fabio Ribeiro Negreiros, Luana Sucupira Pedroza, Flavio Leandro Souza, Gustavo Martini Dalpian
Haematite (α-Fe2O3) is a potential candidate for photo-electrochemical water splitting. It is abundant and its electronic properties fit those needed for this kind of device. However, very little is known about the intermediate steps of this photon-induced water splitting process. We propose here that surface iron vacancies can be the main defects responsible for the activity of haematite in the photoelectrochemical reaction. We perform DFT+U calculations and explicitly add holes to show that these defects are common in iron-terminated (0001) surfaces...
November 20, 2017: Physical Chemistry Chemical Physics: PCCP
Ryo Yamauchi, Tomomi Kinoshita, Yoshinori Hasegawa, Satoshi Iwamoto
The secondary process of lipid peroxidation proceeds by the free radical reaction to produce some toxic aldehydes. Since γ-tocopherol (γ-TH), one of the major forms of vitamin E in some vegetable oils, acts as a free radical scavenger, γ-TH may suppress the formation of such aldehydes. This study reports the effect and reaction products of γ-TH on the hemin- or myoglobin-catalyzed decomposition of 1-palmitoyl-2-linoleoyl-3-sn-phosphatidylcholine 13-hydroperoxide (PLPC-OOH) in micelles and liposomes. γ-TH and PLPC-OOH in micelles were reacted in the presence of hemin, and the reaction products were characterized as 1-palmitoyl-2-[(8a-dioxy-γ-tocopherone)-12,13-epoxyoctadecenoyl]-3-sn-phosphatidylcholines (γT-OO-epoxyPLPC), 1-palmitoyl-2-[(γ-tocopheroxy)-12,13-epoxyoctadecenoyl]-3-sn-phosphatidylcholines (γT-epoxyPLPC), and the adducts of γ-TH dimer with PLPC-OOH derived epoxyperoxyl and epoxyalkyl radicals (γTD-OO-epoxyPLPC and γTD-epoxyPLPC)...
November 7, 2017: Chemistry and Physics of Lipids
Samuel I Mann, Tillmann Heinisch, Thomas R Ward, A S Borovik
Copper-hydroperoxido species (Cu(II)-OOH) have been proposed to be key intermediates in biological and synthetic oxidations. Using biotin-streptavidin (Sav) technology, artificial copper proteins have been developed to stabilize a Cu(II)-OOH complex in solution and in crystallo. Stability is achieved because the Sav host provides a local environment around the Cu-OOH that includes a network of hydrogen bonds to the hydroperoxido ligand. Systematic deletions of individual hydrogen bonds to the Cu-OOH complex were accomplished using different Sav variants and demonstrated that stability is achieved with a single hydrogen bond to the proximal O-atom of the hydroperoxido ligand: changing this interaction to only include the distal O-atom produced a reactive variant that oxidized an external substrate...
November 15, 2017: Journal of the American Chemical Society
Huayu Chen, Shuxin Ouyang, Ming Zhao, Yunxiang Li, Jinhua Ye
Water splitting has been greatly limited by the sluggish kinetics of the oxygen evolution reaction (OER). High-oxidation-state metal species are required as the favorable active sites in OER. Here, amorphous Cox-Fe-B (x is the molar ratio of Co/Fe), Co-B, and Fe-B compounds were successfully synthesized as the oxygen evolution electrocatalysts. The calculation of turnover frequency (TOF) indicates that both the Co and Fe sites are active for OER. Cyclic voltammetry, X-ray photoelectron spectroscopy, and long-term stability curves were used to demonstrate that Fe can stabilize Co in a higher oxidation level and meanwhile promote the generation of OOH-like species (the key intermediates for OER)...
November 13, 2017: ACS Applied Materials & Interfaces
Olivier Holtomo, Mama Nsangou, Jean Jules Fifen, Ousmanou Motapon
DFT methods including B3LYP, B3PW91 and M05-2x associated to 6-31+G(d,p) were used for the structural and antioxidant potency studies of phenylethyl-3,4-dihydroxy-hydrocinnamate (PDH). Solvents were employed according to their protric and aprotic character. So, calculated structures agree with the experimental data. O4H4 is propitious to scavenge radicals whatever the medium except in water where O3H3 and O4H4 are competitive. The explicit solvents of dichloromethane (DCM) and water present a disparity of OH bond dissociation enthalpy and free energy (BDE and BDFE)...
October 28, 2017: Journal of Molecular Graphics & Modelling
Sippakorn Wannakao, Thana Maihom, Kanokwan Kongpatpanich, Jumras Limtrakul, Vinich Promarak
The oxygen evolution and oxygen reduction reactions (OER and ORR, respectively) are important in the field of renewable and clean energy, particularly for hydrogen production and fuel cells. These applications have so far been limited because of the high price of the catalysts and the energy loss due to overpotentials. Hence, non-precious metal catalysts with high efficiency toward the OER/ORR are desirable. In this work, we employ density functional theory (DFT) calculations to study the OER/ORR on metalloporphyrin and halogenated metalloporphyrin frameworks...
November 8, 2017: Physical Chemistry Chemical Physics: PCCP
Vladimir Tripkovic
In the conventional theoretical approach, oxygen reduction reaction activities are assessed through a volcano plot using activity descriptors. The volcano plot relies on several approximations, e.g. the reaction kinetics are commonly overlooked and the interaction of hydrophilic intermediates with water is considered constant regardless of the metal surface. Herein, we demonstrate by means of density functional theory calculations that the binding energies of hydrophilic intermediates are strongly influenced by hydrogen bonding (HB) to surface water molecules...
November 8, 2017: Physical Chemistry Chemical Physics: PCCP
Zalika Klemenc-Ketiš, Ellen Tveter Deilkås, Dag Hofoss, Gunnar Tschudi Bondevik
INTRODUCTION: Patient safety culture is a concept which describes how leader and staff interaction, attitudes, routines and practices protect patients from adverse events in healthcare. We aimed to investigate patient safety culture in Slovenian out-of-hours health care (OOHC) clinics, and determine the possible factors that might be associated with it. METHODS: This was a cross-sectional study, which took place in Slovenian OOHC, as part of the international study entitled Patient Safety Culture in European Out-of-Hours Services (SAFE-EUR-OOH)...
October 2017: Zdravstveno Varstvo
Malgorzata Opydo-Chanek, Katarzyna Śladowska, Kamil Blicharski, Jaromir Mikeš, Peter Fedoročko, Ulf Niemeyer, Lidia Mazur
BACKGROUND/AIM: The oxazaphosphorines, ifosfamide and cyclophosphamide, represent a class of alkylating agents. The aim of the present in vitro study was to compare antileukemic activity of 4-hydroperoxyifosfamide (4-OOH-IF) and 4-hydroperoxycyclophosphamide (4-OOH-CP). MATERIALS AND METHODS: The experiments were performed on MOLT-4 and ML-1 cells. The research was conducted using flow cytometry fluorescein diacetate/propidium iodide (PI), fluorescein-conjugated annexin V/PI, CaspGLOW Red Active Caspase-8 and -9, CellEvent™ Caspase-3/7 Green assays, and tetramethylrhodamine ethyl ester test...
November 2017: Anticancer Research
Yang Wang, Haixiong Liu, Xiaofeng Zhang, Zilong Zhang, Deguang Huang
A di-(2-pyridylmethyl)phenylamine ((PyCH2)2NPh) supported Cu(ii)/O2 catalytic system was explored with the synthesis of pyridylmethyl-based compounds of carboxylate (PyCOOH), amide (PyC(O)NHPh), and imine (PyCH[double bond, length as m-dash]NPh) from the oxidative N-dealkylation of N-(2-pyridylmethyl)phenylamine (PyCH2NHPh) and its derivatives, by means of controlling the addition of a base and/or water to the reaction system under a dioxygen atmosphere at room temperature. Experimental studies showed that the imine and amide species could be precursors in succession in the way to the final oxidation state of carboxylates...
November 7, 2017: Organic & Biomolecular Chemistry
Nicola Seriani
In recent years, hematite has attracted great interest as a photocatalyst for water splitting, but many questions remain unanswered about the mechanisms and the main limiting factors. For this reason, density functional theory has been used to understand the optical, electronic and chemical properties of this material at an atomistic level. Bulk doping can be used to reduce the band gap, and to increase photoabsorption and charge mobility. Charge transport takes place through adiabatic polaron hopping. The stable (0 0 0 1) surface has a stoichiometric termination when exposed to oxygen, it becomes hydroxylated in water, and it has an oxygen-rich termination under illumination in a photoelectrochemical setup...
October 23, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Gary M Wessel
No abstract text is available yet for this article.
October 2017: Molecular Reproduction and Development
Hilde Carin Storhaug, Sara Bjune Mead, Aslak Steinsbekk
BACKGROUND: To investigate opinions among employees at an Out-of-Hours general practitioner (OOH-GP) service and a safety alarm service about the establishment of a generic call-centre. METHODS: Qualitative study using individual and group interviews with 14 employees and managers involved in preparation of a merge into a new generic call-centre. They were asked about their opinions towards establishing a generic call-centre where all contact about unplanned health inquiries from the public had to be done by telephone and how to solve more requests on the phone...
October 17, 2017: BMC Family Practice
Annelies Colliers, Samuel Coenen, Hilde Philips, Roy Remmen, Sibyl Anthierens
INTRODUCTION: Antimicrobial resistance is a major public health threat driven by inappropriate antibiotic use, mainly in general practice and for respiratory tract infections. In Belgium, the quality of general practitioners' (GPs) antibiotic prescribing is low. To improve antibiotic use, we need a better understanding of this quality problem and corresponding interventions. A general practitioners cooperative (GPC) for out-of-hours (OOH) care presents a unique opportunity to reach a large group of GPs and work on quality improvement...
October 15, 2017: BMJ Open
Jin Hee Park, Bong-Soo Kim, Chul-Min Chon
Different environmental conditions such as pH and dissolved elements of mine stream induce precipitation of different minerals and their associated microbial community may vary. Therefore, mine precipitates from various environmental conditions were collected and their associated microbiota were analyzed through metagenomic DNA sequencing. Various Fe and Mn minerals including ferrihydrite, schwertmannite, goethite, birnessite, and Mn-substituted δ-FeOOH (δ-(Fe1-x, Mnx)OOH) were found in the different environmental conditions...
October 9, 2017: Chemosphere
Sanping Zhao, Hailing Xi, Yanjun Zuo, Qi Wang, Zhicheng Wang, Zengyuan Yan
(13)C NMR spectra showed that peroxymonocarbonate (HCO4(-)) was generated in the NaHCO3-activated H2O2 solution and pH was a key factor in its production. A cycle for the bicarbonate anion was proposed as HCO3(-)→HCO3 → (CO2)2*→CO2(aq)→HCO4(-) (H2CO4)→HCO3(-) (HCO3) basing on the results of NMR, electron paramagnetic resonance, chemiluminescence analysis. In this cycle, (CO2)2* was the key intermediate and (CO2)2*→2CO2+hv was the rate controlling step. Thioanisole and paraoxon, the simulants of sulfur mustard gas and nerve gas, respectively, were efficiently decontaminated by the NaHCO3-activated H2O2 solution...
October 2, 2017: Journal of Hazardous Materials
Chloé Raffalli, Elodie Clouet, Salen Kuresepi, Marie-Hélène Damiens, Jean-Pierre Lepoittevin, Marc Pallardy, Pierre-Jacques Ferret, Elena Giménez-Arnau, Saadia Kerdine-Römer
Allergic contact dermatitis (ACD) is regarded as the most frequent expression of immunotoxicity in humans. Many odorant terpenes commonly used in fragrance compositions are considered as weak skin sensitizers, whereas some of their autoxidation products, allylic hydroperoxides, are classified as strong sensitizers according to the Local Lymph Node Assay (LLNA). However, the mechanism of their effects on the immune system remains unclear. Since dendritic cells play a key role in ACD, we studied their activation by the frequently used linalool (LINA) and limonene (LIMO), and their respective sensitizing allylic hydroperoxides (LINA-OOH, LIMO-OOH)...
September 29, 2017: Toxicological Sciences: An Official Journal of the Society of Toxicology
Lili Xing, Junwei Lucas Bao, Zhandong Wang, Feng Zhang, Donald G Truhlar
Oxygenates with carbonyl and hydroperoxy functional groups are important intermediates that are generated during the autoxidation of organic compounds in the atmosphere and during the autoignition of transport fuels. In the troposphere, the degradation of carbonyl hydroperoxides leads to low-vapor-pressure polyfunctional species that may precipitate in clouds and fog droplets or to the formation of secondary organic aerosols (SOAs). In combustion, the fate of carbonyl hydroperoxides is important for the performance of advanced combustion engines, especially for autoignition...
October 27, 2017: Journal of the American Chemical Society
Michael Edelstein, Adeola Agbebiyi, Diane Ashiru-Oredope, Susan Hopkins
Objectives: Antimicrobial resistance is a global threat, increasing morbidity and mortality. In England, publicly funded clinical commissioning groups (CCGs) commission out-of-hours (OOH) primary care services outside daytime hours. OOH consultations represent 1% of in-hours general practice (GP) consultations. Antibiotic prescriptions increased 32% in non-GP community services between 2010 and 2013. We describe OOH antibiotic prescribing patterns and trends between 2010 and 2014. Methods: We: estimated the proportion of CCGs with OOH data available; described and compared antibiotic prescribing by volume of prescribed items, seasonality and trends in GP and OOH, using linear regression; and compared the proportion of broad-spectrum to total antibiotic prescriptions in OOHs with their respective CCGs in terms of seasonality and trends, using binomial regression...
September 18, 2017: Journal of Antimicrobial Chemotherapy
Ru-Fang Zhao, Le Yu, Fu-Qiang Zhou, Jin-Feng Li, Bing Yin
A combined ab initio and DFT study is performed in this work to explore the superhalogen properties of polynuclear structures based on the ligands of -OH, -OOH and -OF. According to high-level CCSD(T) results, all the structures here are superhalogens whose properties are superior to the corresponding mononuclear ones. Although inferior to similar structures based on F ligands, some of the superhalogens here are capable of transcending the traditional ones based on Cl atoms. Therefore the superhalogen properties of the anions here are still promising and they have an important advantage of high safety, which is crucial for practical applications...
October 11, 2017: Physical Chemistry Chemical Physics: PCCP
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