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electron transfer

Yang Yu, Igor Petrik, Kelly N Chacón, Parisa Hosseinzadeh, Honghui Chen, Ninian J Blackburn, Yi Lu
Type 1 copper (T1Cu) proteins are electron transfer (ET) proteins involved in many important biological processes. While the effects of changing primary and secondary coordination spheres in the T1Cu ET function have been extensively studied, no report has explored the effect of the overall protein structural perturbation on active site configuration or reduction potential of the protein, even though the protein scaffold has been proposed to play a critical role in enforcing the entatic or "rack-induced" state for ET functions...
October 19, 2016: Protein Science: a Publication of the Protein Society
Minh T Nguyen, Richard A Jones, Bradley J Holliday
CdSe nanocrystals with tunable sizes and distributions were synthesized directly from Cd(ii) ions coordinated to the conjugated backbone of a thiophene-based conducting metallopolymer. Using our seeded growth technique, the resulting nanocrystals are in direct electronic communication with the polymer, which leads to effective charge transfer between the donor and acceptor.
October 19, 2016: Chemical Communications: Chem Comm
Mingming Wang, Wei Zhan
The grand scale, ultimate efficiency, and sustainability of natural photosynthesis have inspired generations of researchers in biomimetic light energy utilization. As an essential and ubiquitous component in all photosynthetic machinery, lipids and their assemblies have long been recognized as powerful molecular scaffolds in building artificial photosynthetic systems. Model lipid bilayers, such as black lipid membranes and liposomes (vesicles), have been extensively used to host natural as well as synthetic photo- and redox-active species, thereby enabling key photosynthetic processes, such as energy transfer and photoinduced electron transfer, to be examined in well-defined, natural-like membrane settings...
October 19, 2016: Accounts of Chemical Research
Atanu Jana, Masatoshi Ishida, Jung Su Park, Steffen Bähring, Jan O Jeppesen, Jonathan L Sessler
After the epochal discovery of the "organic metal", namely, tetrathiafulvalene (TTF)-7,7,8,8-tetracyano-p-quinodimethane (TCNQ) dyad in 1973, scientists have made efforts to derivatize TTF for constructing various supramolecular architectures to control the charge-transfer processes by adjusting the donor-acceptor strength of the dyads for numerous applications. The interesting inherent electronic donor properties of TTFs control the overall electrochemical properties of the supramolecular structures, leading to the construction of highly efficient optoelectronic materials, photovoltaic solar cells, organic field-effect transistors, and optical sensors...
October 18, 2016: Chemical Reviews
Anees A Ansari, Abdul K Parchur, Brijesh Kumar, S B Rai
The design of nanostructured materials with highly stable water-dispersion and luminescence efficiency is an important concern in nanotechnology and nanomedicine. In this paper, we described the synthesis and distinct surface modification on the morphological structure and optical (optical absorption, band gap energy, excitation, emission, decay time, etc.) properties of highly crystalline water-dispersible CaF2:Ce/Tb nanocrystals (core-nanocrystals). The epitaxial growth of inert CaF2 and silica shell, respectively, on their surface forming as CaF2:Ce/Tb@CaF2 (core/shell) and CaF2:Ce/Tb@CaF2@SiO2 (core/shell/SiO2) nanoarchitecture...
December 2016: Journal of Materials Science. Materials in Medicine
Hui Zhou, Xin Zhao Deng, Ai Hua Zhang, Ren Xiang Tan
An isocyanide insertion reaction promoted by the combination of an amide and a photoredox is now presented. By using visible light, 6-amidophenanthridine derivatives can be prepared in good chemical yields under mild and eco-friendly reaction conditions. The reaction was shown to proceed through an electron transfer sequence by mechanistic experiments, and thus enabled the efficient production of 24 compounds, each with one new intramolecular aromatic ring obtained. The synthesized compounds were tested to embody good antitumor, antimicrobial and neuraminidase inhibitory activities...
October 18, 2016: Organic & Biomolecular Chemistry
Timothy J H Hele, Nandini Ananth
We derive an exact quantum propagator for nonadiabatic dynamics in multi-state systems using the mapping variable representation, where classical-like Cartesian variables are used to represent both continuous nuclear degrees of freedom and discrete electronic states. The resulting Liouvillian is a Moyal series that, when suitably approximated, can allow for the use of classical dynamics to efficiently model large systems. We demonstrate that different truncations of the exact Liouvillian lead to existing approximate semiclassical and mixed quantum-classical methods and we derive an associated error term for each method...
October 18, 2016: Faraday Discussions
Teng-Fei Lu, Wei Li, Jie Chen, Fu-Quan Bai, Jian Wang, Ling-Jun He, Hong-Xing Zhang
In this work, we designed three dyes (Ru1, Ru2, and Ru3) by modifying the square-planar quadridentate ligand of the experimental Ru(ii) complex K1, [RuL(trans-NCS)2] with L = dimethyl-6,60-bis(methyl-2-pyridylamino)-2,20-bipyridine-4,40-dicarboxylate, from a theoretical viewpoint. As is known, K1 shows obvious advantages over the famous dye N749 in light absorption ability because of its highly conjugated ancillary ligands. Density functional theory and time-dependent density functional theory methods were used to determine the geometrical structures, electronic structures and absorption spectra of the dye complexes...
October 18, 2016: Physical Chemistry Chemical Physics: PCCP
Ullah Asmat, Khan Abad, Khan Ismail
Human body is continuously exposed to different types of agents that results in the production of reactive species called as free radicals (ROS/RNS) which by the transfer of their free unpaired electron causes the oxidation of cellular machinery. In order to encounter the deleterious effects of such species, body has got endogenous antioxidant systems or it obtains exogenous antioxidants from diet that neutralizes such species and keeps the homeostasis of body. Any imbalance between the RS and antioxidants leads to produce a condition known as "oxidative stress" that results in the development of pathological condition among which one is diabetes...
September 2016: Saudi Pharmaceutical Journal: SPJ: the Official Publication of the Saudi Pharmaceutical Society
Peng Zheng, Ting Liu, Shouwu Guo
Superior first-cycle Coulomb efficiency (above 80%) is displayed by filter paper-derived micro-nano structure hard carbon, and it delivers a high reversible capacity of 286 mAh g(-1) after 100 cycles as the anode for Na-ion battery at 20 mA g(-1). These advantageous performance characteristics are attributed to the unique micro-nano structure, which reduced the first irreversible capacity loss by limiting the contact between the electrode and electrolyte, and enhanced the capacity by accelerating electron and Na-ion transfer through inter-connected nano-particles and nano-pores, respectively...
October 18, 2016: Scientific Reports
A A Baker, A I Figueroa, D Pingstone, V K Lazarov, G van der Laan, T Hesjedal
We present a study of the interaction mechanisms in magnetic trilayer structures with an MgO barrier grown by molecular beam epitaxy. The interlayer exchange coupling, Aex, is determined using SQUID magnetometry and ferromagnetic resonance (FMR), displaying an unexpected oscillatory behaviour as the thickness, tMgO, is increased from 1 to 4 nm. Transmission electron microscopy confirms the continuity and quality of the tunnelling barrier, eliminating the prospect of exchange arising from direct contact between the two ferromagnetic layers...
October 18, 2016: Scientific Reports
Fang Mao, Mamoun Taher, Oleksandr Kryshtal, Adam Kruk, Aleksandra Czyrska-Filemonowicz, Mikael Ottosson, Anna Mikaela Andersson, Urban Wiklund, Ulf Jansson
A combinatorial approach is applied to rapidly deposit and screen Ag-Al thin films to evaluate the mechanical, tribological and electrical properties as a function of chemical composition. Ag-Al thin films with large continuous composition gradients (6-60 at.% Al) were deposited by a custom-designed combinatorial magnetron sputtering system. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning and transmission electron microscopy (SEM & TEM), X-ray photoelectron spectroscopy (XPS), nanoindentation, and four-point electrical resistance screening were employed to characterize the chemical composition, structure and physical properties of the films in a rapid and time-efficient way...
October 17, 2016: ACS Applied Materials & Interfaces
Pravin Kesarwani, Paramita Chakraborty, Radhika Gudi, Shilpak Chatterjee, Gina Scurti, Kyle Toth, Patt Simms, Mahvash Husain, Kent Armeson, Shahid Husain, Elizabeth Garrett-Mayer, Chethamarakshan Vasu, Michael I Nishimura, Shikhar Mehrotra
Advancements in adoptive cell transfer therapy (ACT) has led to the use of T cells engineered with tumor specific T cell receptors, which after rapid expansion can be obtained in sufficient numbers for treating patients. However, due to massive proliferation these cells are close to replicative senescence, exhibit exhausted phenotype, and also display increased susceptibility to activation induced cell death. We have previously shown that tumor reactive T cells undergo caspase-independent cell death upon TCR restimulation with cognate antigen, which involves reactive oxygen species and c-jun N-terminal kinase...
October 14, 2016: Oncotarget
Ana Amić, Zoran Marković, Jasmina M Dimitrić Marković, Svetlana Jeremić, Bono Lučić, Dragan Amić
Free radical scavenging and inhibitory potency against cyclooxygenase-2 (COX-2) by two abundant colon metabolites of polyphenols, i.e., 3-hydroxyphenylacetic acid (3-HPAA) and 4-hydroxyphenylpropionic acid (4-HPPA) were theoretically studied. Different free radical scavenging mechanisms are investigated in water and pentyl ethanoate as a solvent. By considering electronic properties of scavenged free radicals, hydrogen atom transfer (HAT) and sequential proton loss electron transfer (SPLET) mechanisms are found to be thermodynamically probable and competitive processes in both media...
September 23, 2016: Computational Biology and Chemistry
Mathias Klein, Martina Carrillo, Joeline Xiberras, Zia-Ul Islam, Steve Swinnen, Elke Nevoigt
One advantage of using glycerol as a carbon source for industrial bioprocesses is its higher degree of reduction compared to glucose. In order to exploit this reducing power for the production of reduced compounds thereby significantly increasing maximum theoretical yields, the electrons derived from glycerol oxidation must first be saved in the form of cytosolic NAD(P)H. However, the industrial platform organism Saccharomyces cerevisiae naturally uses a FAD-dependent pathway for glycerol catabolism transferring the electrons to the respiratory chain...
October 14, 2016: Metabolic Engineering
Daisuke Asakura, Eiji Hosono, Masashi Okubo, Yusuke Nanba, Haoshen Zhou, Per-Anders Glans, Jinghua Guo
The changes in electronic structure of LiMn0.6Fe0.4PO4 nanowire during the discharge process were investigated by using ex situ soft X-ray absorption spectroscopy (XAS). The Fe L-edge XAS attributed the potential plateau at 3.45 V vs. Li/Li+ of the discharge curve to a reduction of Fe3+ to Fe2+. The Mn L-edge XAS spectra exhibited the Mn2+ multiplet structure throughout the discharge process, while the crystal-field splitting was slightly enhanced in going to the fully-discharged state. The configuration-interaction full-multiplet calculation for the XAS spectra revealed that the charge-transfer effect from the O 2p to Mn 3d orbitals should be considerably small unlike that from the O 2p to Fe 3d orbitals...
October 17, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Xiaojie Guo, Xiaocheng Wang, Zhaohui Li, Yi Dong
We propose to use a parametric mixer in a passive phase correction scheme for stable distribution of a millimeter-wave signal over fiber links. The parametric mixer is realized via ultrafast four-wave mixing processes, thereby overcoming the bandwidth limit of conventional electronic devices. The mixing of round-trip probe and local pumps generates a signal immune to transmission delay fluctuations at the remote end. This scheme is validated by an experiment that distributes a 36-GHz millimeter wave over 20-km optical fiber...
October 1, 2016: Optics Letters
Félix Beaudoin, Dany Lachance-Quirion, W A Coish, Michel Pioro-Ladrière
Microwave-frequency superconducting resonators are ideally suited to perform dispersive qubit readout, to mediate two-qubit gates, and to shuttle states between distant quantum systems. A prerequisite for these applications is a strong qubit-resonator coupling. Strong coupling between an electron-spin qubit and a microwave resonator can be achieved by correlating spin- and orbital degrees of freedom. This correlation can be achieved through the Zeeman coupling of a single electron in a double quantum dot to a spatially inhomogeneous magnetic field generated by a nearby nanomagnet...
October 17, 2016: Nanotechnology
David Williams-Young, Joshua J Goings, Xiaosong Li
Solutions of the real-time time-dependent density functional theory (RT-TDDFT) equations provide an affordable route to understanding the electronic dynamics that underpins many spectroscopic techniques. From the solutions of the RT-TDDFT equations it is possible to extract optical absorption and circular dichroism spectra, as well as descriptions of charge transfer and charge transport dynamics. In order to apply RT-TDDFT to increasingly large systems, it is necessary to develop methods to overcome computational bottlenecks...
October 17, 2016: Journal of Chemical Theory and Computation
Marko Melander, Elvar Örn Jónsson, Jens Jørgen Mortensen, Tejs Vegge, Juan María García Lastra
Combining constrained density function theory (cDFT) with Marcus theory is an efficient and promising way to address charge transfer reactions. Here, we present a general and robust implementation of cDFT within the projector augmented wave (PAW) framework. PAW pseudopotentials offer a reliable frozen-core electron description across the whole periodic table, with good transferability, as well as facilitate the extraction of all-electron quantities. The present implementation is applicable to two different wave function representations -- atomic centred basis sets (LCAO) and the finite-difference (FD) approximation utilizing real-space grids...
October 17, 2016: Journal of Chemical Theory and Computation
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