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Reactive stepping

Lihua Huang, Chao Hu, Wei Cai, Qi Zhu, Bida Gao, Xuewen Zhang, Chunmei Ren
Fumarylacetoacetate hydrolase participates in positive regulation of salt stress in Arabidopsis. Fumarylacetoacetate hydrolase (FAH) catalyzes the hydrolysis of fumarylacetoacetate into fumarate and acetoacetate, the final step in the Tyr degradation pathway that is essential to animals. However, the Tyr degradation pathway is not well understood in plants. Previously, we found that mutation of the SHORT-DAY SENSITIVE CELL DEATH 1 (SSCD1) gene encoding FAH in Arabidopsis causes spontaneous cell death under short day, which first indicated that the Tyr degradation pathway also plays an important role in plants...
May 21, 2018: Planta
Penglin Xu, Shaojin Hu, Hou-Dao Zhang, Xiao Zheng
Recent experiments have shown that complex (1), [Fe(OTf)2(Pytacn)] (OTf = CF3SO3-, Pytacn = 1-(2'-pyridylmethyl)-4,7-dimethyl-1,4,7-triazacyclononane), is a promising artificial photosynthetic catalyst because of its distinct capability in water oxidation. Experimentalists have also synthesized several derivatives, e.g., [Fe(OTf)2(E,HPytacn)] (E = -Cl (2), -CO2Et (3) and -NO2 (4)) and [Fe(OTf)2 (E,RPytacn)] (R = -F (5) and R = -Me (6)), and proposed that the E-substituted electron-withdrawing groups could improve the catalytic efficiency...
May 22, 2018: Physical Chemistry Chemical Physics: PCCP
Christina M Sheerin, Nadia Chowdhury, Mackenzie J Lind, Erin D Kurtz, Lance M Rappaport, Erin C Berenz, Ruth C Brown, Treven Pickett, Scott D McDonald, Carla Kmett Danielson, Ananda B Amstadter
Individual differences in cognitive processes and coping behaviors play a role in the development and maintenance of posttraumatic stress disorder (PTSD). Given the large numbers of combat-exposed service members returning from the Operation Enduring Freedom (OEF), Operation Iraqi Freedom (OIF), and Operation New Dawn (OND) conflicts, exploring individual differences in cognitive-affective processes is important for informing our understanding of PTSD etiology and early intervention in military samples. The present study examined the unique main and interactive effects of negative posttrauma cognitions (i...
2018: Military Psychology
Prem Bhattarai, Bishnu H Paudel, Dilip Thakur, Balkrishna Bhattarai, Bijay Subedi, Rita Khadka
Background: Despite the successful adaptation to high altitude, some differences do occur due to long term exposure to the hypoxic environment. The effect of long term high altitude exposure on cardiac autonomic adjustment during basal and post-exercise recovery is less known. Thus we aimed to study the differences in basal cardiac autonomic adjustment and its response to exercise in highlanders and to compare it with lowlanders. Methods: The study was conducted on 29 healthy highlander males who were born and brought up at altitude of 3000 m and above from the sea level, their cardiac autonomic adjustment was compared with age, sex, physical activity and ethnicity-matched 29 healthy lowlanders using Heart Rate Variability (HRV) during rest and recovery from sub-maximal exercise (3 m step test)...
2018: Annals of Occupational and Environmental Medicine
Erik Donovan Hedegård, Ulf Ryde
The lytic polysaccharide monooxygenases (LPMOs) are copper metalloenzymes that can enhance polysaccharide depolymerization through an oxidative mechanism and hence boost generation of biofuel from e.g. cellulose. By employing density functional theory in a combination of quantum mechanics and molecular mechanics (QM/MM), we report a complete description of the molecular mechanism of LPMOs. The QM/MM scheme allows us to describe all reaction steps with a detailed protein environment and we show that this is necessary...
April 21, 2018: Chemical Science
Adam C Sedgwick, Hai-Hao Han, Jordan E Gardiner, Steven D Bull, Xiao-Peng He, Tony D James
We have developed a novel AND logic based fluorescence probe for the simultaneous detection of ONOO- and GSH ( GSH-PF3 ). The GSH-PF3 probe was synthesised over three steps starting from commercially available fluorescein. The probe was constructed by attaching the GSH reactive motif, 2,4-dinitrobenzenesulfonyl, to the previously reported boronate fluorescence based probe, PF3 . GSH-PF3 produced only a small fluorescence response towards the addition of GSH or ONOO- separately. However, when the probe was exposed to both analytes, there was a significant (40-fold) fluorescence enhancement...
April 21, 2018: Chemical Science
Yan-Li Han, Bing-Yuan Zhao, Kun-Yao Jiang, Hui-Min Yan, Zhu-Xia Zhang, Wen-Jing Yang, Zhen Guo, Yan-Rong Li
The mechanism of the Ni0 -catalyzed reductive carboxylation reaction of C(sp2 )-O and C(sp3 )-O bonds in aromatic esters with CO2 to access valuable carboxylic acids was comprehensively studied by using DFT calculations. Computational results revealed that this transformation was composed of several key steps: C-O bond cleavage, reductive elimination, and/or CO2 insertion. Of these steps, C-O bond cleavage was found to be rate-determining, and it occurred through either oxidative addition to form a NiII intermediate, or a radical pathway that involved a bimetallic species to generate two NiI species through homolytic dissociation of the C-O bond...
May 18, 2018: Chemistry, An Asian Journal
Irina V Zueva, Sofya V Lushchekina, Patrick Masson
The role of water in oxime-mediated reactivation of phosphylated cholinesterases has been asked with recurrence. To investigate oximate water structure changes in this reaction, reactivation of paraoxon-inhibited human acetylcholinesterase (AChE) was performed by the oxime HI-6 at different pH in the presence and absence of lyotropic salts: a neutral salt (NaCl), a strong chaotropic salt (LiSCN) and strong kosmotropic salts (ammonium sulfate and phosphate HPO4 2- ). At the same time, molecular dynamic simulations of enzyme reactivation under the same conditions were performed over 100 ns...
May 17, 2018: Bioscience Reports
Angelo Spinello, Matic Pavlin, Lorenzo Casalino, Alessandra Magistrato
Cytochromes P450 (CYP450) are involved in the metabolism of exogenous compounds and in the synthesis of signaling molecules. Among the latter, human aromatase (HA) promotes estrogen biosynthesis, being a key pharmacological target against breast cancers. After decades of debate, the interest in gaining a comprehensive picture of HA catalysis has been renewed by the recent discovery that Compound I (Cpd I) is the reactive species of the peculiar aromatization step. Here, we provide for the first time a complete atomic-level picture of all controversial steps of estrogen biosynthesis...
May 17, 2018: Chemistry: a European Journal
Hanieh Meteran, Erik Vindbjerg, Sigurd Wiingaard Uldall, Birte Glenthøj, Jessica Carlsson, Bob Oranje
BACKGROUND: Impairments in mechanisms underlying early information processing have been reported in posttraumatic stress disorder (PTSD); however, findings in the existing literature are inconsistent. This current study capitalizes on technological advancements of research on electroencephalographic event-related potential and applies it to a novel PTSD population consisting of trauma-affected refugees. METHODS: A total of 25 trauma-affected refugees with PTSD and 20 healthy refugee controls matched on age, gender, and country of origin completed the study...
May 17, 2018: Psychological Medicine
Stefan Jungen, Peter Chen
Intramolecular, homolytic substitution reactions between iron (II) species and various trialkylsulfonium groups were directly observed in the gas phase upon collision induced dissociation. In spite of the notoriously low reduction potential of trialkylsulfonium species and the mismatched oxidation potential of iron (II), the reactions proceed at moderate collision energies, forming an alkyl radical as well as a thioether coordinated to the iron. In contrast to classical homolytic substitutions, the attacking radical is a "metalloradical", namely iron (II) that is oxidized to iron (III) during the reaction...
May 16, 2018: Chemistry: a European Journal
Yiming Su, David Jassby, Shikun Song, Xuefei Zhou, Hongying Zhao, Jan Filip, Eleni Petala, Yalei Zhang
Sulfidation of nanoscale zerovalent iron (nZVI) has shown some fundamental improvements on reactivity and selectivity towards pollutants in dissolved oxygen (DO) stimulated Fenton-like reaction systems (DO/S-nZVI system). However, the pristine micro-structure of sulfide modified nanoscale zerovalent iron (S-nZVI) remains uncovered. In addition, the relationship between pollutant removal and the oxidation of the S-nZVI is largely unknown. The present study confirms that sulfidation not only imparts sulfide and sulfate groups onto the surface of the nanoparticle (both on the oxide shell and on flake-like structures), but also introduces sulfur into the Fe(0) core region...
May 16, 2018: Environmental Science & Technology
Xiaofei Zhu, Yinhui Ju, Jian Chen, Deye Liu, Hong Liu
We report a non-enzymatic wearable sensor for electrochemical analysis of perspiration glucose. Multi-potential steps are applied on a Au electrode, including a high negative pretreatment potential step for proton reduction which produc-es a localized alkaline condition, a moderate potential step for electrocatalytic oxidation of glucose under the alkaline condi-tion, and a positive potential step to clean and reactivate the electrode surface for the next detection. Fluorocarbon-based materials were coated on the Au electrode for improving the selectivity and robustness of the sensor...
May 16, 2018: ACS Sensors
Monalisa Goswami, Alexander Konkel, Maryam Rahimi, Marie-Laure Louillat-Habermeyer, Harald Kelm, Rongwei Jin, Bas de Bruin, Frederic William Patureau
The straightforward capture of oxidized phenothiazines with phenols under aerobic conditions represents a unique case of cross-dehydrogenative C-N bond forming reaction in terms of operational simplicity. The mechanism of this cross dehydrogenative N-arylation of phenothiazines with phenols has been an object of debate, particularly regarding the order in which the substrates are oxidized, and their potentially radical or cationic nature. Understanding the selective reactivity of phenols for oxidized phenothiazines is one of the key objectives of this study...
May 16, 2018: Chemistry: a European Journal
Yanzhou Wang, Panpan Gao, Xiaoxu Wang, Jinrong Huo, Lu Li, Yajing Zhang, Alex A Volinsky, Ping Qian, Yanjing Su
The pursuit of catalysts to promote effective water oxidization to produce oxygen has become a research subject of high priority for water splitting. Here, first-principles calculations are employed to study the water-splitting oxygen evolution reaction (OER) on ∼1.5 nm diameter Au13@Ni120P50 core-shell nanoclusters. Water splitting to produce oxygen proceeds in four intermediate reaction steps (OH*, O*, OOH* and O2). Adsorption configurations and adsorption energies for the species involved in OER on both Au13@Ni120P50 cluster and Ni12P5(001) supported by Au are presented...
May 16, 2018: Physical Chemistry Chemical Physics: PCCP
Francis Claret, Sylvain Grangeon, Annick Loschetter, Christophe Tournassat, Wout De Nolf, Nicholas Harker, Faiza Boulahya, Stéphane Gaboreau, Yannick Linard, Xavier Bourbon, Alejandro Fernandez-Martinez, Jonathan Wright
To understand the main properties of cement, a ubiquitous material, a sound description of its chemistry and mineralogy, including its reactivity in aggressive environments and its mechanical properties, is vital. In particular, the porosity distribution and associated sample carbonation, both of which affect cement's properties and durability, should be quantified accurately, and their kinetics and mechanisms of formation known both in detail and in situ . However, traditional methods of cement mineralogy analysis ( e...
March 1, 2018: IUCrJ
Xin Li, Yingjian Liang, Xiaojuan Zhang, Xiaochun Ma
OBJECTIVE: To observe the effect of heparin on the cellular morphology and the expressions of nitric oxide (NO) and reactive oxygen species (ROS) in renal microvascular endothelial cells (RMVECs) stimulated by lipopolysaccharide (LPS). METHODS: The three step gradient screen method was used to primarily culture rat RMVECs, and the 3rd and 4th generation cells with excellent growth were collected. The cells were divided into blank control group, 10 mg/L LPS treatment group and 2...
May 2018: Zhonghua Wei Zhong Bing Ji Jiu Yi Xue
Tao Zhang, Kai Schwedtmann, Jan J Weigand, Thomas Doert, Michael Ruck
The chemical reactivity of phosphonium based ionic liquids (ILs) towards tellurium at temperatures above 220 °C was systematically investigated by a series of dissolution experiments, tracking the solute tellurium species by nuclear magnetic resonance, and characterizing the reaction products by X-ray diffraction and scanning electron microscopy. The initial step is the thermal elimination of an alkyl group of the phosphonium cation of the ILs, most probably via an SN2 mechanism. The addition of tellurium follows to form trialkylphosphane tellurides as evidenced by ³¹P and ¹²⁵Te NMR spectroscopic experiments...
May 15, 2018: Chemistry: a European Journal
Philipp Wanner, Beth L Parker, Daniel Hunkeler
This modeling study aims to investigate how reactive processes in aquitards impact plume persistence in adjacent aquifers. For that purpose the migration of a trichloroethene (TCE) plume in an aquifer originating from dense non-aqueous phase liquid (DNAPL) source dissolution and back-diffusion from an underlying reactive aquitard was simulated in a 2D-numerical model. Two aquitard degradation scenarios were modeled considering one-step degradation from TCE to cis-dichloroethene (cDCE): a uniform (constant degradation with aquitard depth) and a non-uniform scenario (decreasing degradation with aquitard depth) and were compared with a no-degradation scenario...
August 15, 2018: Science of the Total Environment
C Hogan, E Speiser, S Chandola, S Suchkova, J Aulbach, J Schäfer, S Meyer, R Claessen, N Esser
We propose a quantitative and reversible method for tuning the charge localization of Au-stabilized stepped Si surfaces by site-specific hydrogenation. This is demonstrated for Si(553)-Au as a model system by combining density functional theory simulations and reflectance anisotropy spectroscopy experiments. We find that controlled H passivation is a two-step process: step-edge adsorption drives excess charge into the conducting metal chain "reservoir" and renders it insulating, while surplus H recovers metallic behavior...
April 20, 2018: Physical Review Letters
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