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https://www.readbyqxmd.com/read/27925698/frustrated-lewis-pairs-like-reactivity-of-rare-earth-metal-complexes-1-4-addition-reactions-and-polymerizations-of-conjugated-polar-alkenes
#1
Pengfei Xu, Yingming Yao, Xin Xu
Three rare-earth aryloxide ion pairs ([L1REOAr]+[B(C6F5)4]-; L1 = CH3C(2,6-iPr2C6H3N)CHC(CH3)(NCH2CH2PPh2); RE = Sc, Y, Lu; Ar = 2,6-tBu2C6H3) are reported, which feature RE/P combinations exhibiting frustrated Lewis pair (FLP)-like 1,4-addition reactions towards conjugated carbonyl substrates e.g. enone, ynone and acrylic substrates. Furthermore, these RE/P complexes are found to be effective catalysts for polymerizations of conjugated polar alkene monomers. Mechanistic studies reveal that the polymerizations are initiated by novel FLP-type 1,4-additions, rather than traditional and ubiquitous covalent RE-E (E = H, C, N, etc...
December 7, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27925443/graphene-fe3o4-nanocomposites-as-efficient-anodes-to-boost-the-lifetime-and-current-output-of-microbial-fuel-cells
#2
Rong-Bin Song, Cui-E Zhao, Pan-Pan Gai, Dan Guo, Li-Ping Jiang, Qichun Zhang, Jianrong Zhang, Jun-Jie Zhu
Enhancing microbial activity and electrocatalysis through new anode material design is essential for developing microbial fuel cells (MFCs) with longer lifetimes and higher output. In this research, a novel anode material, graphene/Fe3O4 (G/Fe3O4) composite, has been designed for Shewanella-inoculated MFCs. Because Shewanella species could bind to Fe3O4 with high affinity and their growth could be well supported by Fe3O4, the bacterial cells attached quickly onto the anode surface, and their long-term activity improved...
December 7, 2016: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/27925413/mechanism-of-water-oxidation-catalysed-by-a-mononuclear-manganese-complex-py2n-tbu-2mn-h2o-2-2
#3
Yingying Li, Ke Ye, Per E M Siegbahn, Rong-Zhen Liao
The design and synthesis of biomimetic Mn complexes to catalyze oxygen evolution is a very appealing goal since water oxidation in nature employs manganese. A mononuclear Mn complex 1 [LMnII(H2O)2]2+ (L=Py2N(tBu)2) was recently reported to catalyze water oxidation electrochemically with an applied potential of 1.23 V at pH=12.2 in aqueous solution. Density functional calculations have here been performed to elucidate the mechanism of water oxidation promoted by this catalyst. The calculations showed that 1 can readily lose two protons and one electron with the production of 2 [LMnIII(OH)2]+, which then undergoes two sequential proton-coupled electron transfer processes to afford 4 [LMnVOO]+...
December 7, 2016: ChemSusChem
https://www.readbyqxmd.com/read/27925363/synthesis-of-discrete-oligomers-by-sequential-pet-raft-single-unit-monomer-insertion
#4
Jiangtao Xu, Changkui Fu, Sivaprakash Shanmugam, Craig J Hawker, Graeme Moad, Cyrille Boyer
Uniform synthetic polymers with precisely defined molar mass and monomer sequence (primary structure) have many potential high-value applications. However, a robust and versatile synthetic strategy for these materials remains one of the great challenges in polymer synthesis. Herein we describe proof-of-principle experiments for a modular strategy to produce discrete oligomers by a visible-light-mediated radical chain process. We utilize the high selectivity provided by photo-induced electron/energy transfer (PET) activation to develop efficient single unit monomer insertion (SUMI) into reversible addition-fragmentation chain-transfer (RAFT) agents...
December 7, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27925347/a-hydrogen-bonded-cyanide-bridged-co2-fe2-square-complex-exhibiting-a-three-step-spin-transition
#5
Masayuki Nihei, Yuta Yanai, I-Jui Hsu, Yoshihiro Sekine, Hiroki Oshio
Co-crystallization of a cyanide-bridged tetranuclear complex [Co2 Fe2 ] with 4-cyanophenol (CP) gave a hydrogen bonding donor-acceptor system, [Co2 Fe2 (bpy*)4 (CN)6 (tp*)2 ](PF6 )2 ⋅2 CP⋅8 BN (1). 1 exhibited a three-step phase transition between HT, IM1, IM2, and LT phases upon temperature variation. Variable temperature magnetic measurements and structural analyses revealed that the three-step spin transition is caused by electron-transfer-coupled spin transitions (ETCSTs) accompanied with alteration of the hydrogen bonding interactions...
December 7, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27925218/insights-into-light-driven-dna-repair-by-photolyases-challenges-and-opportunities-for-electronic-structure-theory
#6
Shirin Faraji, Andreas Dreuw
UV radiation causes two of the most abundant mutagenic and cytotoxic DNA lesions: cyclobutane pyrimidine dimers and 6-4 photoproducts. (6-4) photolyases are light-activated enzymes that selectively bind to DNA and trigger repair of mutagenic 6-4 photoproducts via photoinduced electron transfer from flavin adenine dinucleotide anion (FADH(-) ) to the lesion triggering repair. This review provides an overview of the sequential steps of the repair process, i.e. light absorption and resonance energy transfer, photo-induced electron transfer, and electron-induced splitting mechanisms, with an emphasis on the role of theory and computation...
December 7, 2016: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/27924782/resistive-switching-of-pt-tio-x-pt-devices-fabricated-on-flexible-parylene-c-substrates
#7
Ali Khiat, Simone Cortese, Alexander Serb, Themistoklis Prodromakis
Pt/TiO x /Pt resistive switching (RS) devices are considered to be amongst the most promising candidates in memristor family and the technology transfer to flexible substrates could open the way to new opportunities for flexible memory implementations. Hence, an important goal is to achieve a fully flexible RS memory technology. Nonetheless, several fabrication challenges are present and must be solved prior to achieving reliable device fabrication and good electronic performances. Here, we propose a fabrication method for the successful transfer of Pt/TiO x /Pt stack onto flexible Parylene-C substrates...
January 13, 2017: Nanotechnology
https://www.readbyqxmd.com/read/27924315/control-of-selective-ion-transfer-across-liquid-liquid-interfaces-a-rectifying-heterojunction-based-on-immiscible-electrolytes
#8
Guillermo Iván Guerrero-García, Francisco J Solis, Kalyan Raidongia, Andrew Robert Koltonow, Jiaxing Huang, Mónica Olvera de la Cruz
The current rectification displayed by solid-state p-n semiconductor diodes relies on the abundance of electrons and holes near the interface between the p-n junction. In analogy to this electronic device, we propose here the construction of a purely ionic liquid-state electric rectifying heterojunction displaying an excess of monovalent cations and anions near the interface between two immiscible solvents with different dielectric properties. This system does not need any physical membrane or material barrier to show preferential ion transfer but relies on the ionic solvation energy between the two immiscible solvents...
November 23, 2016: ACS Central Science
https://www.readbyqxmd.com/read/27924314/homogenous-electrocatalytic-oxygen-reduction-rates-correlate-with-reaction-overpotential-in-acidic-organic-solutions
#9
Michael L Pegis, Bradley A McKeown, Neeraj Kumar, Kai Lang, Derek J Wasylenko, X Peter Zhang, Simone Raugei, James M Mayer
Improved electrocatalysts for the oxygen reduction reaction (ORR) are critical for the advancement of fuel cell technologies. Herein, we report a series of 11 soluble iron porphyrin ORR electrocatalysts that possess turnover frequencies (TOFs) from 3 s(-1) to an unprecedented value of 2.2 × 10(6) s(-1). These TOFs correlate with the ORR overpotential, which can be modulated by changing the E1/2 of the catalyst using different ancillary ligands, by changing the solvent and solution acidity, and by changing the catalyst's protonation state...
November 23, 2016: ACS Central Science
https://www.readbyqxmd.com/read/27923678/flavin-nucleotides-act-as-electron-shuttles-mediating-reduction-of-the-2fe-2s-clusters-in-mitochondrial-outer-membrane-protein-mitoneet
#10
Aaron P Landry, Yiming Wang, Zishuo Cheng, Robert B Crochet, Yong-Hwan Lee, Huangen Ding
MitoNEET, a primary target of type II diabetes drug pioglitazone, has an essential role in regulating energy metabolism, iron homeostasis, and production of reactive oxygen species in mitochondria. Structurally, mitoNEET is anchored to the mitochondrial outer membrane via its N-terminal transmembrane α-helix. The C-terminal cytosolic domain of mitoNEET hosts a redox active [2Fe-2S] cluster via three cysteine and one histidine residues. Here we report that the reduced flavin nucleotides can rapidly reduce the mitoNEET [2Fe-2S] clusters under anaerobic or aerobic conditions...
December 3, 2016: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/27922726/bichromophoric-compounds-with-orthogonally-and-parallelly-arranged-chromophores-separated-by-rigid-spacers
#11
Dirk N H Meineke, Mariano L Bossi, Haisen Ta, Vladimir N Belov, Stefan W Hell
Electronic energy transfer (EET) between chromophores is of fundamental importance for many biological processes and optoelectronic devices. However, common models fall short in fully describing the process, especially in bichromophoric model systems with a donor and acceptor connected by a rigid linker providing perpendicular geometries. Herein, we report a novel strategy to prepare bichromophores containing adamantane or 2-(2-adamantylidene)-adamantane as rigid spacers, providing a fixed distance between chromophores, and their parallel or perpendicular arrangement without chromophore rotation...
December 6, 2016: Chemistry: a European Journal
https://www.readbyqxmd.com/read/27922206/towards-understanding-the-solvent-dynamic-control-of-the-transport-and-heterogeneous-electron-transfer-processes-in-ionic-liquids
#12
Mohsin Ahmad Bhat, Pravin P Ingole, Hyacinthe Randriamahazaka
Impact of temperature induced solvent dynamic changes on the diffusion coefficient and standard rate constant (k0) for heterogeneous electron transfer (ET) of ethylferrocene (EFc) in 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), was investigated. The results were analyzed to understand the impact of the solvent dynamic control, solute-solvent interactions, and solvent friction on the transport of redox probes and k0. Concentration dependency of diffusion coefficient for EFc in [BMIM][PF6] was observed...
December 6, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/27922086/photoelectrochemical-detection-of-alpha-fetoprotein-based-on-zno-inverse-opals-structure-electrodes-modified-by-ag2s-nanoparticles
#13
Yandong Jiang, Dali Liu, Yudan Yang, Ru Xu, Tianxiang Zhang, Kuang Sheng, Hongwei Song
In this work, a new photoelectrochemical biosensor based on Ag2S nanoparticles (NPs) modified macroporous ZnO inverse opals structure (IOs) was developed for sensitive and rapid detection of alpha fetal protein (AFP). Small size and uniformly dispersed Ag2S NPs were prepared using the Successive Ionic Layer Adsorption And Reaction (SILAR) method, which were adsorbed on ZnO IOs surface and frame work as matrix for immobilization of AFP. The composite structure of ZnO/Ag2S expanded the scope of light absorption to long wavelength, which can make full use of the light energy...
December 6, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27922059/protein-self-assembly-onto-nanodots-leads-to-formation-of-conductive-bio-based-hybrids
#14
Xiao Hu, Chenbo Dong, Rigu Su, Quan Xu, Cerasela Zoica Dinu
The next generation of nanowires that could advance the integration of functional nanosystems into synthetic applications from photocatalysis to optical devices need to demonstrate increased ability to promote electron transfer at their interfaces while ensuring optimum quantum confinement. Herein we used the biological recognition and the self-assembly properties of tubulin, a protein involved in building the filaments of cellular microtubules, to create stable, free standing and conductive sulfur-doped carbon nanodots-based conductive bio-hybrids...
December 6, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27920903/toward-clean-suspended-cvd-graphene
#15
Alexander Yulaev, Guangjun Cheng, Angela R Hight Walker, Ivan V Vlassiouk, Alline Myers, Marina S Leite, Andrei Kolmakov
The application of suspended graphene as electron transparent supporting media in electron microscopy, vacuum electronics, and micromechanical devices requires the least destructive and maximally clean transfer from their original growth substrate to the target of interest. Here, we use thermally evaporated anthracene films as the sacrificial layer for graphene transfer onto an arbitrary substrate. We show that clean suspended graphene can be achieved via desorbing the anthracene layer at temperatures in the 100 °C to 150 °C range, followed by two sequential annealing steps for the final cleaning, using Pt catalyst and activated carbon...
2016: RSC Advances
https://www.readbyqxmd.com/read/27920895/organosilane-functionalization-of-nanostructured-indium-tin-oxide-films
#16
R Pruna, F Palacio, M Martínez, O Blázquez, S Hernández, B Garrido, M López
Fabrication and organosilane-functionalization and characterization of nanostructured ITO electrodes are reported. Nanostructured ITO electrodes were obtained by electron beam evaporation, and a subsequent annealing treatment was selectively performed to modify their crystalline state. An increase in geometrical surface area in comparison with thin-film electrodes area was observed by atomic force microscopy, implying higher electroactive surface area for nanostructured ITO electrodes and thus higher detection levels...
December 6, 2016: Interface Focus
https://www.readbyqxmd.com/read/27919802/integrative-view-of-2-oxoglutarate-fe-ii-dependent-oxygenase-diversity-and-functions-in-bacteria
#17
Baolei Jia, Xiaomeng Jia, Kyung Hyun Kim, Che Ok Jeon
BACKGROUND: The 2-oxoglutarate/Fe(II)-dependent oxygenase (2OG oxygenase) superfamily is extremely diverse and includes enzymes responsible for protein modification, DNA and mRNA repair, and synthesis of secondary metabolites. METHODS: To investigate the evolutionary relationship and make functional inferences within this remarkably diverse superfamily in bacteria, we used a protein sequence similarity network and other bioinformatics tools to analyze the bacterial proteins in the superfamily...
December 2, 2016: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/27919066/designed-proteins-induce-the-formation-of-nanocage-containing-extracellular-vesicles
#18
Jörg Votteler, Cassandra Ogohara, Sue Yi, Yang Hsia, Una Nattermann, David M Belnap, Neil P King, Wesley I Sundquist
Complex biological processes are often performed by self-organizing nanostructures comprising multiple classes of macromolecules, such as ribosomes (proteins and RNA) or enveloped viruses (proteins, nucleic acids and lipids). Approaches have been developed for designing self-assembling structures consisting of either nucleic acids or proteins, but strategies for engineering hybrid biological materials are only beginning to emerge. Here we describe the design of self-assembling protein nanocages that direct their own release from human cells inside small vesicles in a manner that resembles some viruses...
November 30, 2016: Nature
https://www.readbyqxmd.com/read/27918963/isolation-of-a-facultative-anaerobic-exoelectrogenic-strain-lz-1-and-probing-electron-transfer-mechanism-in-situ-by-linking-uv-vis-spectroscopy-and-electrochemistry
#19
Lei Zhou, Dandan Deng, Yichi Zhang, Wen Zhou, Yujing Jiang, Ying Liu
A new facultative anaerobic exoelectrogenic strain LZ-1, belonging to Citrobacter freundii, has been isolated. This strain can produce current densities of 843.9 and 865.6μAcm(-2) using citrate or acetate as carbon source in a three-electrode configuration. The electricity generation performance was also analyzed in a dual-chamber MFC system, reaching a maximum power density of 1233mWm(-2). In addition to acetate and citrate, other carbon sources such as pyruvate, formate, acetate, citrate and fumarate could also be utilized to produce current by strain LZ-1...
November 27, 2016: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/27918646/bionanofiber-assisted-decoration-of-few-layered-mose2-nanosheets-on-3d-conductive-networks-for-efficient-hydrogen-evolution
#20
Feili Lai, Dingyu Yong, Xueliang Ning, Bicai Pan, Yue-E Miao, Tianxi Liu
Molybdenum diselenide (MoSe2 ) has emerged as a promising electrocatalyst for hydrogen evolution reaction (HER). However, its properties are still confined due to the limited active sites and poor conductivity. Thus, it remains a great challenge to synergistically achieve structural and electronic modulations for MoSe2 -based HER catalysts because of the contradictory relationship between these two characteristics. Herein, bacterial cellulose-derived carbon nanofibers are used to assist the uniform growth of few-layered MoSe2 nanosheets, which effectively increase the active sites of MoSe2 for hydrogen atom adsorption...
December 5, 2016: Small
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