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electron transfer

Yuvraj Patil, Rajneesh Misra, Manish Kumar Singh, Ganesh D Sharma
A symmetrical D-π-A-π-D type small molecule consisting of thiophene flanked diketopyrrolopyrrole (DPP) as a core and an end capping ferrocene donor linked by an ethynyl bridge, denoted as Fc-DPP-Fc, was synthesized and its optical, thermal and electrochemical properties were investigated in order to explore its potential applicability as a donor for solution processed bulk heterojunction solar cells. The photophysical and electrochemical properties of this small molecule showed strong charge transfer interaction between the ferrocene donor and the DPP acceptor, and it is found to be suitable as a small molecule donor along with PC71BM as an electron acceptor for solution processed bulk heterojunction organic solar cells (OSCs)...
February 27, 2017: Physical Chemistry Chemical Physics: PCCP
Yanhui Zhang, Rongying Dai, Shirong Hu
In recent years, substantial efforts have been devoted to exploring reduced graphene oxide/TiO2 (RGO/TiO2) composite materials; however, there is still a paucity of reports on the construction of reduced graphene oxide/TiO2 with oxygen vacancies (RGO/TiO2-OV) via a facile two-step wet chemistry approach. In this work, we show a proof-of-concept study follow RGO introduced into TiO2 with oxygen vacancies, the role of oxygen vacancies as active sites in reduced graphene oxide-modified TiO2. The photocatalytic performance and related properties of blank-TiO2, blank-TiO2 with oxygen vacancies (blank-TiO2-OV), RGO/TiO2, and RGO/TiO2-OV were comparatively studied...
February 27, 2017: Physical Chemistry Chemical Physics: PCCP
Y Manolova, H Marciniak, S Tschierlei, F Fennel, F S Kamounah, S Lochbrunner, L Antonov
The solvent dependent excited state dynamics of 4-hydroxy-3-(piperidin-1-ylmethyl)-1-naphthaldehyde (compound 2), a candidate for a molecular switch based on intramolecular proton transfer, was investigated by ultrafast spectroscopy and quantum-chemical calculations. In acetonitrile a mixture of molecules in the enol and zwitterionic proton transfer (PT) form exists in the ground state. However, the zwitterion is the energetically favored one in the electronically excited state. Optical excitation of the enol form results in intramolecular proton transfer and formation of the PT form within 1...
February 27, 2017: Physical Chemistry Chemical Physics: PCCP
Yi Yang Wu, Miao Meng, Gang Yi Wang, Pengju Feng, Chun Y Liu
Four thienylene (C4H2S) bridged Mo2 dimers, [Mo2(DAniF)3]2(μ-OOCC4H2SCOO) (DAniF = N,N'-di(p-anisyl)formamidinate), [Mo2(DAniF)3]2(μ-N(H)SCC4H2SCN(H)S), [Mo2(DAniF)3]2(μ-OSCC4H2SCSO) and [Mo2(DAniF)3]2(μ-SSCC4H2SCSS), have been synthesized and studied in terms of electronic coupling. The subtle structural differences between these compounds vary largely the extent of electron delocalization; consequently, a systematic transition from Class II to Class III via Class II-III is achieved, which is probed using spectral parameters of intervalence charge transfer (IVCT) absorption (band energy, intensity and shape) for the mixed-valence complexes...
February 27, 2017: Chemical Communications: Chem Comm
Evgenii S Stoyanov, Anton S Nizovtsev
Comparison of experimental infrared (IR) spectra of the simplest carbocations (with the weakest carborane counterions in terms of basicity, CHB11Hal11(-), Hal = F, Cl) with their calculated IR spectra revealed that they are completely inconsistent, as previously reported for the t-Bu(+) cation [Stoyanov E. S., et al. J. Phys. Chem. A, 2015, 119, 8619]. This means that the generally accepted explanation of hyperconjugative stabilization of the carbocations should be revised. According to the theory, one CH bond (denoted as ) from each CH3/CH2 group transfers its σ-electron density to the empty 2pz orbital of the sp(2) C atom, whereas the σ-electron density on the other CH bonds of the CH3/CH2 group slightly increases...
February 27, 2017: Physical Chemistry Chemical Physics: PCCP
Toshiki Higashino, Akira Ueda, Junya Yoshida, Hatsumi Mori
A dihydroxy-substituted benzothienobenzothiophene, BTBT(OH)2, was synthesized, and its charge-transfer (CT) salt, β-[BTBT(OH)2]2ClO4, was successfully obtained. Thanks to the introduced hydroxy groups, a hydrogen-bonded chain structure connecting the BTBT molecules and counter anions was formed in the CT salt, which effectively increases the dimensionality of the electronic structure and consequently leads to a stable metallic state.
February 27, 2017: Chemical Communications: Chem Comm
Konrad H Engelhardt, Shashank Reddy Pinnapireddy, Elias Baghdan, Jarmila Jedelská, Udo Bakowsky
Lipid vectors are commonly used to facilitate the transfer of nucleic acids into mammalian cells. In this study, two fractions of tetraether lipids from the archaea Sulfolobus acidocaldarius were extracted and purified using different methods. The purified lipid fractions polar lipid fraction E (PLFE) and hydrolysed glycerol-dialkyl-nonitol tetraether (hGDNT) differ in their structures, charge, size, and miscibility from conventional lipids. Liposomes were prepared by mixing tetraether lipids with cholesterol (CH) and 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) resulting in stable vectors for gene delivery...
2017: Archaea: An International Microbiological Journal
Harry B Gray, Jay R Winkler
Prior to 1950, the consensus was that biological transformations occurred in two-electron steps, thereby avoiding the generation of free radicals. Dramatic advances in spectroscopy, biochemistry, and molecular biology have led to the realization that protein-based radicals participate in a vast array of vital biological mechanisms. Redox processes involving high-potential intermediates formed in reactions with O2 are particularly susceptible to radical formation. Clusters of tyrosine (Tyr) and tryptophan (Trp) residues have been found in many O2-reactive enzymes, raising the possibility that they play an antioxidant protective role...
October 2016: Israel Journal of Chemistry
John W Loughney, Catherine Lancaster, Colleen E Price, Van M Hoang, Sha Ha, Richard R Rustandi
Clostridium difficile infection (CDI) is the leading cause of gastroenteritis-associated death in the United States. The major virulent factors of C. difficile are toxin A (TcdA) and toxin B (TcdB). Toxicity is mediated by the glucosyltransferase domains on TcdA and TcdB wherein a glucose is transferred from UDP-glucose to Ras homolog family member A (RhoA) receptor. This modification results in disruption of critical cell signaling events. Vaccination against these toxins is considered the best way to combat the CDI...
January 31, 2017: Journal of Chromatography. A
Niels Egholm Pedersen, Lars Simon Rasmussen, John Asger Petersen, Thomas Alexander Gerds, Doris Østergaard, Anne Lippert
The national early warning score (NEWS) is recommended to detect deterioration in hospitalised patients. In 2013, a NEWS-based system was introduced in a hospital service with over 250,000 annual admissions, generating large amounts of NEWS data. The quality of such data has not been described. We critically assessed NEWS data recorded over 12 months. This observational study included NEWS records from adult inpatients hospitalized in the Capital Region of Denmark during 2014. Physiological variables and the use of supplementary oxygen (NEWS variables) were recorded...
February 25, 2017: Journal of Clinical Monitoring and Computing
Corinne J Thomas, Timothy P Cleland, Sheng Zhang, Caren M Gundberg, Deepak Vashishth
Osteocalcin is an important extracellular matrix bone protein that contributes to the structural properties of bone through its interactions with hydroxyapatite mineral and with collagen I. This role may be affected by glycation, a labile modification the levels of which has been shown to correlate with bone fragility. Glycation starts with the spontaneous addition of a sugar onto a free amine group on a protein, forming an Amadori product, and then proceeds through several environment-dependent stages resulting in the formation of an advanced glycation end product...
February 22, 2017: Analytical Biochemistry
P Lamberg, J Hamit-Eminovski, M D Toscano, O Eicher-Lorka, G Niaura, T Arnebrant, S Shleev, T Ruzgas
The interface between protein and material surface is of great research interest in applications varying from implants, tissue engineering to bioelectronics. Maintaining functionality of bioelements depends greatly on the immobilization process. In the present study direct electron transfer of cellobiose dehydrogenase from Humicola insolens (HiCDH), adsorbed on four different self-assembled monolayers (SAMs) formed by 5-6 chain length carbon thiols varying in terminal group structure was investigated. By using a combination of quartz crystal microbalance with dissipation, ellipsometry and electrochemistry the formation and function of the HiCDH film was studied...
February 16, 2017: Bioelectrochemistry
Xiao Qi Yang, Quan Sheng Zhang, Di Zhang, Zi Tong Sheng
Responses of electron transport to three levels of irradiation (20, 200, and 1200 μmol photons m(-2) s(-1) PAR; exposures called LL, ML and HL, respectively) were investigated in eelgrass (Zostera marina L.) utilizing the chlorophyll a fluorescence technique. Exposure to ML and HL reduced the maximum quantum yield of photosystem II (PSII) (Fv/Fm) and the maximum slope decrease of MR/MRO (VPSI), indicating the occurrence of photoinhibition of both PSII and photosystem I (PSI). A comparatively slow recovery rate of Fv/Fm due to longer half-life recovery time of PSII and 40% lower descending amplitude compared to other higher plants implied the poor resilience of the PSII...
February 14, 2017: Plant Physiology and Biochemistry: PPB
Peter Gros, Ashour Ahmed, Oliver Kühn, Peter Leinweber
The herbicide glyphosate (GLP) is supposed to be rapidly degraded or adsorbed strongly by soil solids but findings in soil years after application and concentrations in waters above legal limits question a harmless disappearance. Therefore, we conducted batch sorption experiments with 23 thoroughly characterized arable surface soils, correlated isotherm coefficients with numerous inorganic and organic soil parameters, and investigated GLP-SOM-complexes by quantum-chemical modeling. The Freundlich sorption model yielded the best fits, and coefficients Kf and nf were correlated positively with the contents of clay/silt...
February 21, 2017: Science of the Total Environment
Qidong Yin, Kai He, Aike Liu, Guangxue Wu
Conductive materials can facilitate syntrophic methane (CH4) production by improving direct interspecies electron transfer. The effect of a conductive material, ferroferric oxide (Fe3O4), on the anaerobic treatment of tryptone-based high-strength wastewater was investigated in two anaerobic sequencing batch reactors (ASBRs). One was the control reactor without amendment of Fe3O4, and the other was the Fe3O4-amended reactor. In an ASBR reaction cycle, the dosage of Fe3O4 increased the CH4 production rate by 12...
February 24, 2017: Applied Microbiology and Biotechnology
Nigar Ahmadova, Felix Ho, Stenbjorn Styring, Fikret Mamedov
Tyrosine D (TyrD) is an auxiliary redox active tyrosine residue in photosystem II (PsiI). The mechanism of TyrD oxidation was investigated by EPR spectroscopy, flash-induced fluorescence decay and thermoluminescence measurements in PsiI enriched membranes from spinach. PsiI membranes were chemically treated with 3mM ascorbate and 1mM diaminodurene and subsequent washing, leading to the complete reduction of TyrD. TyrD oxidation kinetics and competing recombination reactions were measured after a single saturating flash in the absence and presence of DCMU (inhibitor of the QB-site) in the pH range of 4...
February 21, 2017: Biochimica et Biophysica Acta
Sylvia K Choi, Myat T Lin, Hanlin Ouyang, Robert B Gennis
The cytochrome bo3 ubiquinol oxidase is one of three respiratory oxygen reductases in the aerobic respiratory chain of Escherichia coli. The generally accepted model of catalysis assumes that cyt bo3 contains two distinct ubiquinol binding sites: (i) a low affinity (QL) site which is the traditional substrate binding site; and (ii) a high affinity (QH) site where a "permanently" bound quinone acts as a cofactor, taking two electrons from the substrate quinol and passing them one-by-one to the heme b component of the enzyme which, in turn, transfers them to the heme o3/CuB active site...
February 21, 2017: Biochimica et Biophysica Acta
Silvana Pinheiro, Carles Curutchet
Förster resonance energy transfer (FRET) reactions involving ligands and aromatic amino acids can substantially impact the fluorescence properties of a protein-ligand complex, an impact intimately related to the corresponding binding mode. Structural characterization of such binding events in terms of intermolecular distances can be done through the well-known R-6 distance-dependent Förster rate expression. However, such interpretation suffers from uncertainties underlying Förster theory in the description of the electronic coupling that promotes FRET, mostly related to the dipole-dipole orientation factor, dielectric screening effects and deviations from the ideal dipole approximation...
February 24, 2017: Journal of Physical Chemistry. B
Chaozhong Guo, Youcheng Wu, Zhongbin Li, Wenli Liao, Lingtao Sun, Chao Wang, Bixia Wen, Yanrong Li, Changguo Chen
The design of noble-metal-free catalysts for oxygen reduction reaction (ORR) is very important to the commercialization of fuel cells. Here, we use a Co-modified montmorillonite (Co-MMT) as a flat template to prepare Co- and N-doped nanocarbon ORR catalysts derived from carbonization of polyaniline at controlled temperatures. The use of flat template can hinder the agglomeration of polyaniline during pyrolysis process and optimize the N-rich active site density on the surface. The addition of transition metal Co in the flat MMT template can largely promote the formation of Co-N sites in prepared catalyst, facilitating the effective improvement of catalytic activity towards the ORR with a direct four-electron transfer pathway...
December 2017: Nanoscale Research Letters
Xiren Chen, Qiandong Zhuang, Hayfaa Alradhi, ZhiMing Jin, Liangqing Zhu, Xin Chen, Jun Shao
Photoluminescence (PL) as a conventional yet powerful optical spectroscopy may provide crucial insight into the mechanism of carrier recombination and bandedge structure in semiconductors. In this study, mid-infrared PL measurements on vertically aligned InAs nanowires (NWs) are realized for the first time in a wide temperature range of up to 290 K, by which the radiative recombinations are clarified in the NWs grown on n- and p-type Si substrates, respectively. A dominant PL feature is identified to be from the type-II optical transition across the interfaces between the zinc-blend (ZB) and the wurtzite (WZ) InAs, a lower-energy feature at low temperatures is ascribed to impurity-related transition, and a higher-energy feature at high temperatures originates in the interband transition of the WZ InAs being activated by thermal-induced electron transfer...
February 23, 2017: Nano Letters
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