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Clare F Megarity, Julian Esselborn, Suzannah V Hexter, Florian Wittkamp, Ulf-Peter Apfel, Thomas Happe, Fraser A Armstrong
Protein film electrochemistry (PFE) has been used to study the assembly of the complex 6Fe active site of [FeFe]-hydrogenases (known as the H-cluster) from its precursors the [4Fe 4S] domain that is already coordinated within the host and the 2Fe domain that is presented as a synthetic water-soluble complex stabilized by an additional CO. Not only does PFE allow control of redox states via the electrode potential, but the immobilized state of the enzyme facilitates control of extremely low concentrations of the 2Fe complex...
October 24, 2016: Journal of the American Chemical Society
Hyun Deog Yoo, Sang-Don Han, Ryan D Bayliss, Andrew A Gewirth, Bostjan Genorio, Nav Nidhi Rajput, Kristin A Persson, Anthony K Burrell, Jordi Cabana
Hybrid supercapacitors that follow a 'rocking-chair'-type mechanism were developed by coupling divalent metal and activated carbon electrodes in non-aqueous electrolytes. Conventional supercapacitors require large amount of electrolyte to provide a sufficient quantity of ions to the electrodes, due to their Daniell-type mechanism that depletes the ions from the electrolyte whilst charging. The alternative 'rocking-chair'-type mechanism effectively enhances the energy density of supercapacitors by minimizing the necessary amount of electrolyte, because the ion is replenished from the metal anode while it is adsorbed to the cathode...
October 24, 2016: ACS Applied Materials & Interfaces
Omer Yehezkeli, Nicholas M Bedford, Eunsol Park, Ke Ma, Jennifer N Cha
There has been active interest to identify new methods to reduce CO2 into usable fuel sources. In this work, we demonstrate two types of photo-electrochemical cells (PECs) that photoreduce CO2 directly to formate in aqueous solutions both in the presence and absence of external bias or additional electron sources. The photocathodes were either a CuFeO2 /CuO electrode or a bilayer of CdTe on NiO, whereas the photoanode was a bilayer of NiOx on CdS. The PECs were characterized by using both electrochemistry and spectroscopy, and the products formed from CO2 reduction were characterized and quantified by using (1) H NMR spectroscopy and ESI-MS...
October 24, 2016: ChemSusChem
Shuo Kang, Ab F Nieuwenhuis, Klaus Mathwig, Dileep Mampallil, Zinaida A Kostiuchenko, Serge G Lemay
The diffusive mass transport of individual redox molecules was probed experimentally in microfabricated nanogap electrodes. The residence times for molecules inside a well-defined detection volume were extracted and the resulting distribution was compared with quantitative analytical predictions from random-walk theory for the time of first passage. The results suggest that a small number of strongly adsorbing sites strongly influence mass transport at trace analyte levels.
October 24, 2016: Faraday Discussions
Brian S Dolinar, Stosh A Kozimor, John F Berry
We present the synthesis, structure, and electrochemistry of K3[Mo2(SNO5)4Cl]3[Mo2(SNO5)4] (1, HSNO5 = monothiosuccinimide), the first example of a heterometallic extended metal atom node (HEMAN). The HEMAN consists of two perpendicular, intersecting lines of metal atoms formed by three [Mo2(SNO5)4Cl](-) units and one [Mo2(SNO5)4] unit tethered together by K(+) ions.
October 24, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Hong-Jie Peng, Dai-Wei Wang, Jia-Qi Huang, Xin-Bing Cheng, Zhe Yuan, Fei Wei, Qiang Zhang
Owing to the conversion chemistry of the sulfur cathode, the lithium-sulfur (Li-S) batteries exhibit high theoretical energy density. However, the intrinsic mobile redox centers during the sulfur/Li2S-to-lithium polysulfides solid-to-liquid phase transition induce low sulfur utilization and poor cycling life. Herein, the Janus separator of mesoporous cellular graphene framework (CGF)/polypropylene membrane to promote the utilization of sulfur cathode is introduced. The porous polypropylene membrane serves as an insulating substrate in contact with lithium anode while CGFs that possess high electrical conductivity of 100 S cm(-1), a large mesopore volume of 3...
January 2016: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Andrew G Yee, Peter S Freestone, Ji-Zhong Bai, Janusz Lipski
Parkinson's disease (PD) is not only associated with degeneration of dopaminergic (DAergic) neurons in the Substantia Nigra, but also with profound loss of noradrenergic neurons in the Locus Coeruleus (LC). Remarkably, LC degeneration may exceed, or even precede the loss of nigral DAergic neurons, suggesting that LC neurons may be more susceptible to damage by various insults. Using a combination of electrophysiology, fluorescence imaging and electrochemistry, we directly compared the responses of LC, nigral DAergic and nigral non-dopaminergic (non-DAergic) neurons in rat brain slices to acute application of rotenone, a mitochondrial toxin used to create animal and in vitro models of PD...
October 19, 2016: Experimental Neurology
Wenjing Liu, Rami Al-Oweini, Karen Meadows, Bassem S Bassil, Zhengguo Lin, Jonathan H Christian, Naresh S Dalal, A Martin Bossoh, Israël M Mbomekallé, Pedro de Oliveira, Jamshed Iqbal, Ulrich Kortz
The dichromium(III)-containing heteropoly-16-tungstates [Cr(III)2(B-β-Si(IV)W8O31)2](14-) (1) and [Cr(III)2(B-β-Ge(IV)W8O31)2](14-) (2) were prepared via a one-pot reaction of the composing elements in aqueous, basic medium. Polyanions 1 and 2 represent the first examples of Cr(III)-containing heteropolytungstates comprising the octatungstate unit {XW8O31} (X = Si, Ge). Magnetic studies demonstrated that, in the solid state, the two polyanions exhibit a weak antiferromagnetic interaction between the two Cr(III)centers with J = -3...
October 21, 2016: Inorganic Chemistry
Hao Zhu, Jiangli Fan, Huiying Mu, Tao Zhu, Zhen Zhang, Jianjun Du, Xiaojun Peng
Polarity-sensitive fluorescent probes are powerful chemical tools for studying biomolecular structures and activities both in vitro and in vivo. However, the lack of "off-on" polarity-sensing probes has limited the accurate monitoring of biological processes that involve an increase in local hydrophilicity. Here, we design and synthesize a series of "off-on" polarity-sensitive fluorescent probes BP series consisting of the difluoroboron dippyomethene (BODIPY) fluorophore connected to a quaternary ammonium moiety via different carbon linkers...
October 21, 2016: Scientific Reports
Hangil Lee, Yeonwoo Kim, Min Ji Kim, Ki-Jeong Kim, Byung-Kwon Kim
In order to compare the catalytic activities of reduced graphene oxide (rGO), graphene oxide (GO), and graphene, we conducted oxidation of 2-aminothiophenol (2-ATP) and reduction of nitrobenzene (NB) in their presence by using high-resolution photoemission spectroscopy (HRPES). In addition, we determined conversion rates of CO to CO2 in the presence of these catalysts by performing a residual gas analyzer (RGA) under a UHV condition, Orange II and methylene blue degradations UV-vis spectrophotometry, and electrochemistry (EC) measurements in an aqueous solution, as well as by obtaining cyclic voltammograms and determining the change of the condition of electrodes before and after the oxidation of 2-ATP...
October 20, 2016: Scientific Reports
Richard M Crooks
This article provides a summary of the Faraday Discussion on single entity electrochemistry held in York, U.K., in early September, 2016. The introduction provides some context for thinking about electrochemical studies of single entities. The next four sections follow the themes of the meeting as they relate to single-entity electrochemistry: (1) nanoparticles, nanotubes, and nanowires; (2) nanopores and nanofluidics; (3) complex surfaces and reactions at the nanoscale; and (4) molecular electroanalysis. Each paper presented at the Discussion is summarized, and some personal thoughts as to the significance of the findings, the technical advances that made the experiments possible, and common themes between articles are interspersed...
October 20, 2016: Faraday Discussions
Wen Donq Looi, Laura Chamand, Blake Brown, Anna F Brajter-Toth
The ionization of liquid samples in desorption ionization mass spectrometry (LS DESI MS), supplied continuously through a liquid interface separated in space from the spray emitter, was investigated in this work. The role of electrochemistry (EC) in the ionization process was addressed. The visual (observation) of the operation of the LS DESI MS system showed a thick spray plume generated by electrosonic ionization (ESSI) forming a liquid cone at the liquid interface. When the liquid interface was grounded the cone collapsed and the MS ion signal was lost, indicating that the LS was carried to the MS inlet by the spray that emerged from the cone...
October 20, 2016: Analytical Chemistry
Shaltiel Eloul, Richard G Compton
The diffusion of a particle from bulk solution is slowed as it moves close to an adsorbing surface. A general model is reported which is easily applied by theoreticians and experimentalists. Specifically, it is shown here that in general and regardless of the space size, the magnitude of the effect of hindered diffusion on the flux is a property of the diffusion layer thickness. We quantify and explain the effect. Predictions of concentration profiles show that a 'hindered diffusion layer' is formed near the adsorbing surface within the diffusion layer, observed even when the particle radius is just a 0...
October 19, 2016: Journal of Physical Chemistry Letters
Filiz Demircik, David Klonoff, Petra B Musholt, Sanja Ramljak, Andreas Pfützner
BACKGROUND: Devices employing electrochemistry-based correction algorithms (EBCAs) are optimized for patient use and require special handling procedures when tested in the laboratory. This study investigated the impact of sample handling on the results of an accuracy and hematocrit interference test performed with BG*Star, iBG*Star; OneTouch Verio Pro and Accu-Chek Aviva versus YSI Stat 2300. METHODS: Venous heparinized whole blood was manipulated to contain three different blood glucose concentrations (64-74, 147-163, and 313-335 mg/dL) and three different hematocrit levels (30%, 45%, and 60%)...
October 2016: Diabetes Technology & Therapeutics
Sharel Pei E, Yang-Rae Kim, David Perry, Cameron Luke Bentley, Patrick R Unwin
There is great interest in finding and developing new, efficient and more active electrocatalytic materials. Surface modification of highly oriented pyrolytic graphite (HOPG), through the introduction of surface "blisters", is demonstrated to result in an electrode material with greatly enhanced electrochemical activity. The increased electrochemical activity of these blisters, which are produced by electro-oxidation in HClO4, is revealed through the use of scanning electrochemical cell microscopy (SECCM), coupled with complementary techniques (optical microscopy, FE-SEM, Raman spectroscopy, and AFM)...
October 14, 2016: ACS Applied Materials & Interfaces
Randy P Sabatini, Michael F Mark, Daniel J Mark, Mark W Kryman, Jacqueline E Hill, William W Brennessel, Michael R Detty, Richard Eisenberg, David W McCamant
Although rhodamine dyes have been extensively studied for a variety of applications, many details of their photophysics are not yet fully understood, including the possible presence of a charge separated electronic state lying near the optically active excited singlet state and the role of twisting substituent groups in excited-state quenching. To address this, a large library of rhodamine dyes was studied in which the chalcogen is varied from O, to S and Se and the aryl group is either absent (in the pyronin series) or is a phenyl or thienyl substituent...
October 13, 2016: Photochemical & Photobiological Sciences
Kazuo Yamamoto, Yasutoshi Iriyama, Tsukasa Hirayama
All-solid-state Li-ion batteries having incombustible solid electrolytes are promising energy storage devices because they have significant advantages in terms of safety, lifetime and energy density. Electrochemical reactions, namely, Li-ion insertion/extraction reactions, commonly occur around the nanometer-scale interfaces between the electrodes and solid electrolytes. Thus, transmission electron microscopy (TEM) is an appropriate technique to directly observe such reactions, providing important information for understanding the fundamental solid-state electrochemistry and improving battery performance...
October 12, 2016: Microscopy
Todd J Anderson, Bo Zhang
Metal nanoparticles are key electrode materials in a variety of electrochemical applications including basic electron-transfer study, electrochemical sensing, and electrochemical surface enhanced Raman spectroscopy (SERS). Metal nanoparticles have also been extensively applied to electrocatalytic processes in recent years due to their high catalytic activity and large surface areas. Because the catalytic activity of metal nanoparticle is often highly dependent on their size, shape, surface ligands, and so forth, methods for examining and better understanding the correlation between particle structure and function are of great utility in the development of more efficient catalytic systems...
October 12, 2016: Accounts of Chemical Research
Travis L Sunderland, John F Berry
The first set of five heterobimetallic MM'(form)4 (form = formamidinate) complexes has been successfully synthesized containing a BiRh core. The Bi-Rh bond distances lie between 2.5196(6) and 2.572[2] Å, consistent with Bi-Rh single bonds. All complexes have rich electrochemistry, with the [BiRh]4+/5+ redox couples spanning ~ 700 mV and showing a strong correlation to remote ligand substitution. Visible spectroscopy shows two features for complexes 1 - 5 at ~ 459 and ~ 551 nm, unique to BiRh paddlewheel complexes that are attributed to LMCT bands into the Bi-Rh * orbital...
October 11, 2016: Chemistry: a European Journal
Vedran Milosavljevic, Yazan Haddad, Miguel Angel Merlos Rodrigo, Amitava Moulick, Hana Polanska, David Hynek, Zbynek Heger, Pavel Kopel, Vojtech Adam
Prostate cancer cells control energy metabolism by chelating intracellular zinc. Thus, zinc delivery has been a popular therapeutic approach for prostate cancer. Here, we propose the use of the membrane-penetrating peptide Novicidin connected to zinc-Schiff base as a carrier vehicle for the delivery of zinc to prostate cells. Mass spectrometry, electrochemistry and spectrophotometry confirmed the formation/stability of this complex and provided insight regarding the availability of zinc for complex interactions...
2016: PloS One
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