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https://www.readbyqxmd.com/read/29039183/electrochemically-generated-cis-carboxylato-coordinated-iron-iv-oxo-acid-base-congeners-as-promiscuous-oxidants-of-water-pollutants
#1
David P de Sousa, Christopher J Miller, Yingyue Chang, T David Waite, Christine J McKenzie
The nonheme iron(IV) oxo complex [Fe(IV)(O)(tpenaH)](2+) and its conjugate base [Fe(IV)(O)(tpena)](+) [tpena(-) = N,N,N'-tris(2-pyridylmethyl)ethylenediamine-N'-acetate] have been prepared electrochemically in water by bulk electrolysis of solutions prepared from [Fe(III)2(μ-O)(tpenaH)2](ClO4)4 at potentials over 1.3 V (vs NHE) using inexpensive and commercially available carbon-based electrodes. Once generated, these iron(IV) oxo complexes persist at room temperature for minutes to half an hour over a wide range of pH values...
October 17, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/29038209/activation-and-inhibition-of-sodium-hydrogen-exchanger-is-a-mechanism-that-links-the-pathophysiology-and-treatment-of-diabetes-mellitus-with-that-of-heart-failure
#2
REVIEW
Milton Packer
The mechanisms underlying the progression of diabetes mellitus and heart failure are closely intertwined, such that worsening of one condition is frequently accompanied by worsening of the other; the degree of clinical acceleration is marked when the 2 coexist. Activation of the sodium-hydrogen exchanger in the heart and vasculature (NHE1 isoform) and the kidneys (NHE3 isoform) may serve as a common mechanism that links both disorders and may underlie their interplay. Insulin insensitivity and adipokine abnormalities (the hallmarks of type 2 diabetes mellitus) are characteristic features of heart failure; conversely, neurohormonal systems activated in heart failure (norepinephrine, angiotensin II, aldosterone, and neprilysin) impair insulin sensitivity and contribute to microvascular disease in diabetes mellitus...
October 17, 2017: Circulation
https://www.readbyqxmd.com/read/29035047/electrocatalytic-water-oxidation-by-a-water-soluble-copper-ii-complex-with-a-copper-bound-carbonate-group-acting-as-a-potential-proton-shuttle
#3
Fangfang Chen, Ni Wang, Haitao Lei, Dingyi Guo, Hongfei Liu, Zongyao Zhang, Wei Zhang, Wenzhen Lai, Rui Cao
Water-soluble copper(II) complexes of the dianionic tridentate pincer ligand N,N'-2,6-dimethylphenyl-2,6-pyridinedicarboxamidate (L) are catalysts for water oxidation. In [L-Cu(II)-DMF] (1, DMF = dimethylformamide) and [L-Cu(II)-OAc](-) (2, OAc = acetate), ligand L binds Cu(II) through three N atoms, which define an equatorial plane. The fourth coordination site of the equatorial plane is occupied by DMF in 1 and by OAc(-) in 2. These two complexes can electrocatalyze water oxidation to evolve O2 in 0.1 M pH 10 carbonate buffer...
October 16, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/29027700/increases-in-the-expression-of-na-h-exchanger-1-and-3-are-associated-with-insulin-signalling-in-the-ruminal-epithelium
#4
L Yan, Z Shen, Z Lu
Na(+) /H(+) exchanger (NHE), which catalyses the exchange of extracellular Na(+) for intracellular H(+) , is of importance in the maintenance of Na(+) and pH homoeostasis for rumen epithelial cells. Studies in ruminants showed that high concentrate diets could increase the expression of NHE in ruminal epithelium. Results of recent studies further indicated that insulin, as an important hormone closely related to dietary concentrate, could enhance the expression of NHE. In this study, we have investigated the mechanisms of insulin regulating the expression of NHE in rumen epithelial cells and its potential role in dietary modulation of NHE expression in ruminal epithelium of cows...
October 13, 2017: Journal of Animal Physiology and Animal Nutrition
https://www.readbyqxmd.com/read/29023122/water-photo-oxidation-initiated-by-surface-bound-organic-chromophores
#5
Michael S Eberhart, Degao Wang, Renato N Sampaio, Seth L Marquard, Bing Shan, M Kyle Brennaman, Gerald J Meyer, Christopher Dares, Thomas J Meyer
Organic chromophores can be synthesized by established methods and offer an opportunity to expand overall solar spectrum utilization for dye sensitized photoelectrosynthesis cells (DSPECs). However, there are complications in the use of organic chromophores arising from the instability of their oxidized forms, the inability of their oxidized forms to activate a water oxidation catalyst, or the absence of a sufficiently reducing excited state for electron injection into appropriate semiconductors. Three new triarylamine donor-acceptor organic dyes have been investigated here for visible light driven water oxidation...
October 12, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28936507/a-pyrene-modified-cobalt-salophen-complex-immobilized-on-multiwalled-carbon-nanotubes-acting-as-a-precursor-for-efficient-electrocatalytic-water-oxidation
#6
Ting-Ting Li, Jinjie Qian, Qianqian Zhou, Jian-Li Lin, Yue-Qing Zheng
Immobilization of earth-abundant water oxidation catalysts (WOCs) on carbon supports to produce functional electrodes for electrochemical water splitting is a crucial approach for future clean energy production. Herein we report the non-covalent immobilization of a pyrene-bearing cobalt(ii) Schiff base complex (2) on the surface of multiwalled carbon nanotubes (MWCNTs) to form a hybrid anode for electrocatalytic water oxidation. The 2/MWCNT anode displayed excellent catalytic activity and durability in neutral aqueous solution, and a catalytic current density of 1...
September 22, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28929548/an-fe-iii-aza-macrocyclic-complex-as-ph-tunable-catholyte-and-anolyte-for-redox-flow-battery-applications
#7
Pavel B Tsitovich, Anjula M Kosswattaarachchi, Matthew R Crawley, Timothy Y Tittiris, Timoth R Cook, Janet Ruth Morrow
A reversible Fe3+/Fe2+ redox couple of an aza-macrocyclic complex is evaluated as an electrolyte with a pH-tunable potential range for aqueous redox-flow batteries (RFBs). The Fe(III) complex is formed by 1,4,7-triazacyclononane (TACN) appended with three 2-methyl-imidazole donors, denoted as Fe(Tim). This complex exhibits pH-sensitive redox couples that span E1/2(Fe3+/Fe2+)=317 to -270 mV vs. NHE at pH 3.3 and pH 12.8, respectively. The 590 mV shift in potential and kinetic inertness are driven by ionization of the imidazoles at various pH values...
September 19, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28926954/evidence-for-complex-formation-of-the-bacillus-cereus-haemolysin-bl-components-in-solution
#8
Franziska Tausch, Richard Dietrich, Kristina Schauer, Robert Janowski, Dierk Niessing, Erwin Märtlbauer, Nadja Jessberger
Haemolysin BL is an important virulence factor regarding the diarrheal type of food poisoning caused by Bacillus cereus. However, the pathogenic importance of this three-component enterotoxin is difficult to access, as nearly all natural B. cereus culture supernatants additionally contain the highly cytotoxic Nhe, the second three-component toxin involved in the aetiology of B. cereus-induced food-borne diseases. To better address the toxic properties of the Hbl complex, a system for overexpression and purification of functional, cytotoxic, recombinant (r)Hbl components L₂, L₁ and B from E...
September 16, 2017: Toxins
https://www.readbyqxmd.com/read/28923730/kinetics-analysis-of-interfacial-electron-transfer-processes-in-goethite-suspensions-systems
#9
Jianzhong Ma, Chengzhu Zhu, Jun Lu, Bin Ouyang, Qiaoqin Xie, Haibo Liu, Shuchuan Peng, Tianhu Chen
The photochemical behavior of goethite has been one of the most important topics in the field of environmental science due to it plays a significant role in the removal and transformation process of numerous pollutants. However, the interfacial electron transfer process of goethite is not clear. Using a nanosecond laser flash photolysis spectrometer, we report the transient spectroscopic observations of interfacial electron-transfer reactions in goethite dispersion under UV irradiation. Excitation of goethite generated conduction-band electron (ecb(-)) and hole (h(+))...
September 7, 2017: Chemosphere
https://www.readbyqxmd.com/read/28921692/mechanistic-studies-on-the-role-of-cuii-co3-n-2-2n-as-a-water-oxidation-catalyst-carbonate-as-a-non-innocent-ligand
#10
Amir Mizrahi, Dan Meyerstein, Israel Zilbermann, Haya Kornweitz, Eric Maimon, Haim Cohen
Recently it was reported that copper bicarbonate/ carbonate complexes are good electro-catalysts for water oxidation. However, the results did not enable a decision whether the active oxidant is a CuIII or a CuIV complex. Kinetic analysis of pulse radiolysis measurements coupled with DFT calculations point out that CuIII(CO3)n3-2n complexes are the active intermediates in the electrolysis of CuII(CO3)n2-2n solution. The results enable the evaluation of E°((CuIII/II(CO3)n)aq) ~ 1.42 V vs. NHE at pH 8.4. This redox potential is in accord with the electrochemical report...
September 16, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28912833/perspectives-for-biocatalytic-lignin-utilization-cleaving-4-o-5-and-c%C3%AE-c%C3%AE-bonds-in-dimeric-lignin-model-compounds-catalyzed-by-a-promiscuous-activity-of-tyrosinase
#11
Kyoungseon Min, Taewoo Yum, Jiye Kim, Han Min Woo, Yunje Kim, Byoung-In Sang, Young Je Yoo, Yong Hwan Kim, Youngsoon Um
BACKGROUND: In the biorefinery utilizing lignocellulosic biomasses, lignin decomposition to value-added phenolic derivatives is a key issue, and recently biocatalytic delignification is emerging owing to its superior selectivity, low energy consumption, and unparalleled sustainability. However, besides heme-containing peroxidases and laccases, information about lignolytic biocatalysts is still limited till date. RESULTS: Herein, we report a promiscuous activity of tyrosinase which is closely associated with delignification requiring high redox potentials (>1...
2017: Biotechnology for Biofuels
https://www.readbyqxmd.com/read/28912799/triportheus-albus-cope-1872-in-the-blackwater-clearwater-and-whitewater-of-the-amazon-a-case-of-phenotypic-plasticity
#12
José D A Araújo, Andrea Ghelfi, Adalberto L Val
The Amazon basin includes 1000s of bodies of water, that are sorted according to their color in three types: blackwater, clearwater, and whitewater, which significantly differ in terms of their physicochemical parameters. More than 3,000 species of fish live in the rivers of the Amazon, among them, the sardine, Triportheus albus, which is one of the few species that inhabit all three types of water. The purpose of our study was to analyze if the gene expression of T. albus is determined by the different types of water, that is, if the species presents phenotypic plasticity to live in blackwater, clearwater, and whitewater...
2017: Frontiers in Genetics
https://www.readbyqxmd.com/read/28895869/amiloride-interferes-with-platelet-activating-factor-induced-respiratory-burst-and-mmp-9-release-in-bovine-neutrophils-independent-of-na-h-exchanger-1
#13
C S Larrazabal, M D Carretta, M A Hidalgo, R A Burgos
Cytoplasmic pH homeostasis is required for an appropriate response in polymorphonuclear neutrophils (PMNs). In these cells, chemotaxis and reactive oxygen species (ROS) production are reduced by the use of Na(+)/H(+) exchanger (NHE-1) inhibitors, but these results are mainly obtained using amiloride, a non-selective NHE-1 inhibitor. In bovine PMNs, the role of NHE-1 in functional responses has not been confirmed yet. The aim of this study was to determine the role of NHE-1 using amiloride and zoniporide in pH regulation, ROS production, matrix metalloproteinase 9 (MMP-9) release and calcium flux in bovine PMNs induced by the platelet activation factor (PAF), additionally we evaluated the presence of NHE-1 and NHE-2 mRNA Our data show the presence only of NHE-1 but not NHE-2 in bovine PMNs...
September 2017: Veterinary Immunology and Immunopathology
https://www.readbyqxmd.com/read/28885854/phenoxazine-a-privileged-scaffold-for-radical-trapping-antioxidants
#14
Luke A Farmer, Evan A Haidasz, Markus Griesser, Derek A Pratt
Diphenylamines are widely used to protect petroleum-derived products from autoxidation. Their efficacy as radical-trapping antioxidants (RTAs) relies on a balance of fast H-atom transfer kinetics and stability to one-electron oxidation by peroxidic species. Both H-atom transfer and one-electron oxidation are enhanced by substitution with electron-donating substituents, such as the S-atom in phenothiazines, another important class of RTA. Herein we report the results of our investigations of the RTA activity of the structurally related, but essentially ignored, phenoxazines...
September 22, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28872182/quantum-dots-in-photocatalytic-applications-efficiently-enhancing-visible-light-photocatalytic-activity-by-integrating-cdo-quantum-dots-as-sensitizers
#15
A H Reshak
The amalgamation of a wide optical band gap photocatalyst with visible-light-active CdO quantum dots (QDs) as sensitizers is one of the most efficient ways to improve photocatalytic performance under visible light irradiation. The photocatalytic performance of cadmium benzoate ((Cd(C7H5O2)2)3(CH3CN)1) is comprehensively investigated. The estimated optical band gap of cadmium benzoate is 2.64 eV and the EPc and EPv are about -0.09 V (vs. NHE) and +2.55 V (vs. NHE), respectively, which implies that cadmium benzoate possesses a high negative reduction potential of excited electrons due to its higher conduction band position, and hence, the locations of the conduction band minimum and the valence band maximum meet the redox capacity...
September 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28853874/chloride-oxidation-by-ruthenium-excited-states-in-solution
#16
Sara A M Wehlin, Ludovic Troian-Gautier, Guocan Li, Gerald J Meyer
Photodriven HCl splitting to produce solar fuels is an important goal that requires strong photo-oxidants capable of chloride oxidation. In a molecular approach toward this goal, three ruthenium compounds with 2,2'-bipyrazine backbones were found to oxidize chloride ions in acetone solution. Nanosecond transient absorption measurements provide compelling evidence for excited-state electron transfer from chloride to the Ru metal center with rate constants in excess of 10(10) M(-1) s(-1). The Cl atom product was trapped with an olefin...
September 7, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28852583/comparative-molecular-analyses-of-select-ph-and-osmoregulatory-genes-in-three-freshwater-crayfish-cherax-quadricarinatus-c-destructor-and-c-cainii
#17
Muhammad Y Ali, Ana Pavasovic, Lalith K Dammannagoda, Peter B Mather, Peter J Prentis
Systemic acid-base balance and osmotic/ionic regulation in decapod crustaceans are in part maintained by a set of transport-related enzymes such as carbonic anhydrase (CA), Na(+)/K(+)-ATPase (NKA), H(+)-ATPase (HAT), Na(+)/K(+)/2Cl(-) cotransporter (NKCC), Na(+)/Cl(-)/HCO[Formula: see text] cotransporter (NBC), Na(+)/H(+) exchanger (NHE), Arginine kinase (AK), Sarcoplasmic Ca(+2)-ATPase (SERCA) and Calreticulin (CRT). We carried out a comparative molecular analysis of these genes in three commercially important yet eco-physiologically distinct freshwater crayfish, Cherax quadricarinatus, C...
2017: PeerJ
https://www.readbyqxmd.com/read/28835421/effect-of-salt-intake-on-afferent-arteriolar-dilatation-role-of-connecting-tubule-glomerular-feedback-ctgf
#18
Hong Wang, Cesar A Romero, J X Masjoan Juncos, Sumit R Monu, Edward L Peterson, Oscar A Carretero
Afferent arteriole (Af-Art) resistance is modulated by 2 intrinsic nephron feedbacks: 1) vasoconstrictor tubuloglomerular feedback (TGF), which is mediated by NKCC2 in the macula densa and blocked by furosemide; and 2) vasodilator connecting tubule glomerular feedback (CTGF), which is mediated by ENaC in the connecting tubule and blocked by benzamil. High salt intake reduces the Af-Art vasoconstrictor ability in Dahl salt-sensitive rats (Dahl SS). Previously, we measured CTGF indirectly using the differences between the TGF responses with and without CTGF inhibition...
August 23, 2017: American Journal of Physiology. Renal Physiology
https://www.readbyqxmd.com/read/28831654/redox-potentials-of-ubiquinone-menaquinone-phylloquinone-and-plastoquinone-in-aqueous-solution
#19
Shinnosuke Kishi, Keisuke Saito, Yuki Kato, Hiroshi Ishikita
Quinones serve as redox active cofactors in bacterial photosynthetic reaction centers: photosystem I, photosystem II, cytochrome bc 1, and cytochrome b 6 f. In particular, ubiquinone is ubiquitous in animals and most bacteria and plays a key role in several cellular processes, e.g., mitochondrial electron transport. Their experimentally measured redox potential values for one-electron reduction E m(Q/Q(·-)) were already reported in dimethylformamide (DMF) versus saturated calomel electrode but not in water versus normal hydrogen electrode (NHE)...
August 22, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28813053/copper-ii-benzimidazole-complexes-as-efficient-fluorescent-probes-for-l-cysteine-in-water
#20
Duraiyarasu Maheshwaran, Selvarasu Priyanga, Ramasamy Mayilmurugan
Copper(ii) complexes [Cu(L1)(H2O)2](SO3CF3)21 and [Cu(L2)(H2O)2](SO3CF3)22 based on 2,6-bis(benzimidazolyl)pyridine were synthesized and are reported herein as highly selective "turn-on" optical probes for l-cysteine. The Cu(ii)/Cu(i) redox potential of probe 1 (0.14 V vs. NHE) was lower than that of 2 (0.233 V vs. NHE) in water. The molecular structure of 2 adopted a square pyramidal geometry (τ = 0.2545), with the Cu-Npy bond (1.958 Å) of its middle pyridine unit being shorter than the other two Cu-Nbenzim bonds (Cu-N, 1...
August 29, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
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