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Hop kinetic

Michael S Azzaro, Amro Dodin, Diana Y Zhang, Adam P Willard, Sean T Roberts
Researchers have long sought to use surface ligands to enhance energy migration in nanocrystal solids by decreasing the physical separation between nanocrystals and strengthening their electronic coupling. Exciton-delocalizing ligands, which possess frontier molecular orbitals that strongly mix with nanocrystal band edge states, are well-suited for this role as they can facilitate carrier wavefunction extension beyond the nanocrystal core, reducing barriers for energy transfer. This report details use of the exciton-delocalizing ligand phenyldithiocarbamate (PDTC) to tune the transport rate and diffusion length of excitons in CdSe nanocrystal solids...
April 13, 2018: Nano Letters
M Rico-Pasto, I Pastor, F Ritort
Single-molecule experiments with optical tweezers have become an important tool to study the properties and mechanisms of biological systems, such as cells and nucleic acids. In particular, force unzipping experiments have been used to extract the thermodynamics and kinetics of folding and unfolding reactions. In hopping experiments, a molecule executes transitions between the unfolded and folded states at a preset value of the force [constant force mode (CFM) under force feedback] or trap position [passive mode (PM) without feedback] and the force-dependent kinetic rates extracted from the lifetime of each state (CFM) and the rupture force distributions (PM) using the Bell-Evans model...
March 28, 2018: Journal of Chemical Physics
Pooja Sahu, Sk Musharaf Ali, Kalsanka Trivikram Shenoy, Sadhana Mohan
Cu complex, which are the key chemical species in well-known Cu-Cl hybrid thermochemical cycles and also in numerous metal hydrometallurgical and sedimentary deposit processes, displays wide variety of structural and dynamical characteristics that are further complicated by the presence of multiple oxidation states of Cu ions with different coordination chemistry, therefore are difficult to explore from experiments alone. In this article, therefore, an attempt has been made to understand the coordination behavior of Cu complex using MD simulations...
March 23, 2018: Journal of Physical Chemistry. B
Yancong Feng, Rui Tan, Yan Zhao, Rongtan Gao, Luyi Yang, Jinlong Yang, Hao Li, Guofu Zhou, Haibiao Chen, Feng Pan
A novel hybrid single Li-ion conductor (SLIC) for a Li-ion solid electrolyte was prepared by mixing aluminate complexes-polyethylene glycol (LiAl-PEG) and polyethylene oxide (PEO) for solid-state Li-ion batteries. The LiAl-PEG/PEO blend possesses high thermal stability and electrochemical stability with an oxidation decomposition voltage up to 4.8 V. Notably, this hybrid SLIC exhibits not only excellent Li-ion migration kinetics, but also good ionic conductivity as high as 4.0 × 10-5 and 2.6 × 10-4 S cm-1 at 30 and 100 °C, respectively, which is much higher than previously reported SLICs...
March 15, 2018: Nanoscale
Andrew J Kossow, Tyler G DeChiara, Steve M Neahous, William P Ebben
Plyometric exercises are frequently performed as part of a strength and conditioning program. Most studies assessed the kinetics of plyometric exercises primarily performed in the vertical plane. The purpose of this study was to evaluate the multi-planar kinetic characteristics of a variety of plyometric exercises, which have a significant horizontal component. This study also sought to assess sex differences in the intensity progression of these exercises. Ten men and ten women served as subjects. The subjects performed a variety of plyometric exercises including the double leg hop, standing long jump, single leg standing long jump, bounding, skipping, power skipping, cone hops, and 45...
March 12, 2018: Journal of Strength and Conditioning Research
Guangzheng Zuo, Xianjie Liu, Mats Fahlman, Martijn Kemerink
The impact of nanoscale morphology on conductivity and Seebeck coefficient in p-type doped all-polymer blend systems is investigated. For a strongly phase separated system (P3HT:PTB7), we achieve a Seebeck coefficient that peaks at S ∼ 1100 µV/K with conductivity σ ∼ 3·10-3 S/cm for 90% PTB7. In marked contrast, for well mixed systems (P3HT:PTB7 with 5% DIO, P3HT:PCPDTBT), we find an almost constant S ∼ 140 µV/K and σ ∼ 1 S/cm despite the energy levels being (virtually) identical in both cases...
February 28, 2018: ACS Applied Materials & Interfaces
Y Z Shi, S Xiong, Y Zhang, L K Chin, Y -Y Chen, J B Zhang, T H Zhang, W Ser, A Larson, L S Hoi, J H Wu, T N Chen, Z C Yang, Y L Hao, B Liedberg, P H Yap, D P Tsai, C-W Qiu, A Q Liu
Particle trapping and binding in optical potential wells provide a versatile platform for various biomedical applications. However, implementation systems to study multi-particle contact interactions in an optical lattice remain rare. By configuring an optofluidic lattice, we demonstrate the precise control of particle interactions and functions such as controlling aggregation and multi-hopping. The mean residence time of a single particle is found considerably reduced from 7 s, as predicted by Kramer's theory, to 0...
February 26, 2018: Nature Communications
Hiroki Sato, Daisuke Aoki, Toshikazu Takata
We developed novel size-complementary molecular and macromolecular rotaxanes using a 2,6-dimethylphenyl terminal as the axle-end-cap group in dibenzo-24-crown-8-ether (DB24C8)-based rotaxanes, where the 2,6-dimethylphenyl group was found to be less bulky than the 3,5-dimethylphenyl group. A series of molecular and macromolecular [2]rotaxanes that bear a 2,6-dimethylphenyl group as the axle-end-cap were synthesized using unsubstituted and fluorine-substituted DB24C8. Base-induced decomposition into their constituent components confirmed the occurrence of deslipping, which supports the size-complementarity of these rotaxanes...
February 2, 2018: Chemistry, An Asian Journal
Federico Raffone, Giancarlo Cicero
Even though resistance switching memories (RRAM) can be potentially employed in a broad variety of fields, like electronics and brain science, they are still affected by issues that prevent their application in circuitry. These problems are a consequence of the lack of detailed knowledge about the physical processes occurring in the device. In this work we propose a multi-scale simulation, combining Kinetic Monte Carlo and finite difference methods, to shed light on the yet unclear switching process occurring in valence change RRAM which are believed to work as consequence of the drift and diffusion of crystalline defects which act as dopants...
February 1, 2018: ACS Applied Materials & Interfaces
Jialin Mao, Utkarsh Doshi, Matthew Wright, Cornelis E C A Hop, Albert P Li, Yuan Chen
Plateable human hepatocytes with human plasma were utilized to generate the uptake transporter kinetic data for pravastatin, an organic anion transporting polypeptide (OATP) transporter substrate. The active hepatic uptake of pravastatin was determined with a Jmax value of 134.4 pmol/min/million cells and apparent Km of 76.77 µM in plateable human hepatocytes with human plasma. The physiologically based pharmacokinetic (PBPK) model with incorporation of these in vitro kinetic data successfully simulated the intravenous pharmacokinetic profile of pravastatin without applying scaling factor (the mean predicted AUC is within 1...
February 1, 2018: CPT: Pharmacometrics & Systems Pharmacology
Yiwei Li, Osman Kahraman, Christoph A Haselwandter
Diffusion can be conceptualized, at microscopic scales, as the random hopping of particles between neighboring lattice sites. In the case of diffusion in inhomogeneous media, distinct spatial domains in the system may yield distinct particle hopping rates. Starting from the master equations (MEs) governing diffusion in inhomogeneous media we derive here, for arbitrary spatial dimensions, the deterministic lattice equations (DLEs) specifying the average particle number at each lattice site for randomly diffusing particles in inhomogeneous media...
September 2017: Physical Review. E
Rui Zhang, Kenneth S Schweizer
The Elastically Collective Nonlinear Langevin Equation theory for one-component viscous liquids and suspensions is generalized to treat coupled slow activated relaxation and diffusion in glass-forming binary sphere mixtures of any composition, size ratio, and interparticle interactions. A trajectory-level dynamical coupling parameter concept is introduced to construct two coupled dynamic free energy functions for the smaller penetrant and larger matrix particle. A two-step dynamical picture is proposed where the first-step process involves matrix-facilitated penetrant hopping quantified in a self-consistent manner based on a temporal coincidence condition...
April 5, 2018: Journal of Physical Chemistry. B
Emrah Kovalak, Tolga Atay, Cem Çetin, I Meltem Atay, Mustafa Onur Serbest
OBJECTIVE: Whether surgical or conservative treatment is more effective in allowing patients to return to physical activity after anterior cruciate ligament (ACL) injury is controversial. We sought to compare mid-term outcome measures between isolated ACL tear patients who underwent reconstruction followed by closed kinetic chain exercises and those who underwent neuromuscular training only. METHODS: We retrospectively evaluated patients with ACL tears who underwent post-surgery CKC strength training after ACL reconstruction (Group A), and patients who only underwent neuromuscular training (Group B) with a minimum follow-up time of 5 years...
January 2018: Acta Orthopaedica et Traumatologica Turcica
Jiali Wang, Thomas Albers, Christof Grewer
Glutamate transporters maintain a large glutamate concentration gradient across synaptic membranes and are, thus, critical for functioning of the excitatory synapse. Mammalian glutamate transporters concentrate glutamate inside cells through energetic coupling of glutamate flux to the transmembrane concentration gradient of Na+ . Structural models based on an archeal homologue, GltPh, suggest an elevator-like carrier mechanism. However, the energetic determinants of this carrier-based movement are not well understood...
January 11, 2018: Journal of Physical Chemistry. B
Aleksandra Bazan-Wozniak, Piotr Nowicki, Robert Pietrzak
A technology of activated bio-carbons production from the residue left after supercritical extraction of hops is described. The effect of the variant of chemical activation and impregnation ratio on the physicochemical properties as well as sorption capacity towards toxic gas of acidic character (nitrogen dioxide), basic organic dye (aqueous solution of methylene blue - MB) and iodine was investigated. The materials obtained were activated bio-carbons of well-developed surface area ranging between 897 and 1095m2 /g, showing clearly acidic character of the surface...
February 2018: Environmental Research
Marie Steffenhagen, Alina Latus, Thi Minh Nguyet Trinh, Iwona Nierengarten, Ivan T Lucas, Suzanne Joiret, Jessem Landoulsi, Béatrice Delavaux-Nicot, Jean-François Nierengarten, Emmanuel Maisonhaute
A rotaxane scaffold incorporating two dithiolane anchoring units for the modification of gold surfaces has been functionalized with multiple copies of a redox unit, namely ferrocene. Surface modification has been first assessed at the single molecule level by atomic force microscopy (AFM) and scanning tunneling microscopy (STM) imaging, while tip enhanced Raman spectroscopy (TERS) provided the local vibrational signature of the ferrocenyl subunits of the rotaxanes grafted onto the gold surface. Finally, oxidation of the redox moieties within a rotaxane scaffold grafted onto gold microelectrodes has been investigated by ultrafast cyclic voltammetry...
February 1, 2018: Chemistry: a European Journal
Shaoyang Lin, Alireza K Ravari, Jie Zhu, Pavel M Usov, Meng Cai, Spencer R Ahrenholtz, Yulia Pushkar, Amanda J Morris
Investigation of chemical water oxidation was conducted on [Ru(tpy)(dcbpy)(OH2 )]2+ (tpy=2,2':6',2''-terpyridine, dcbpy=5,5'-dicarboxy-2,2'-bipyridine)-doped UiO-67 metal-organic framework (MOF). The MOF catalyst exhibited a single-site reaction pathway with kinetic behavior similar to that of a homogeneous Ru complex. The reaction was first order with respect to both the concentration of the Ru catalyst and ceric ammonium nitrate (CAN), with kcat =3(±2)×10-3  m-1  s-1 in HNO3 (pH 0.5). The common degradation pathways of ligand dissociation and dimerization were precluded by MOF incorporation, which led to sustained catalysis and greater reusability as opposed to the molecular catalyst in homogeneous solution...
January 23, 2018: ChemSusChem
Starla D Glover, Robin Tyburski, Li Liang, Cecilia Tommos, Leif Hammarström
Protein-based "hole" hopping typically involves spatially arranged redox-active tryptophan or tyrosine residues. Thermodynamic information is scarce for this type of process. The well-structured α3 W model protein was studied by protein film square wave voltammetry and transient absorption spectroscopy to obtain a comprehensive thermodynamic and kinetic description of a buried tryptophan residue. A Pourbaix diagram, correlating thermodynamic potentials (E°') with pH, is reported for W32 in α3 W and compared to equivalent data recently presented for Y32 in α3 Y ( Ravichandran , K...
January 10, 2018: Journal of the American Chemical Society
Eugene Mamontov, Alexander I Kolesnikov, Sujatha Sampath, Jeffery L Yarger
Lithium-beryllium metal hydrides, which are structurally related to their parent compound, BeH2 , offer the highest hydrogen storage capacity by weight among the metal hydrides (15.93 wt. % of hydrogen for LiBeH3 ). Challenging synthesis protocols have precluded conclusive determination of their crystallographic structure to date, but here we analyze directly the hydrogen hopping mechanisms in BeH2 and LiBeH3 using quasielastic neutron scattering, which is especially sensitive to single-particle dynamics of hydrogen...
November 24, 2017: Scientific Reports
Alejandro Méndez-Ardoy, Nagula Markandeya, Xuesong Li, Yu-Tang Tsai, Gilles Pecastaings, Thierry Buffeteau, Victor Maurizot, Luca Muccioli, Frédéric Castet, Ivan Huc, Dario M Bassani
Aromatic foldamers are bioinspired architectures whose potential use in materials remains largely unexplored. Here we report our investigation of vertical and horizontal charge transport over long distances in helical oligo-quinolinecarboxamide foldamers organized as single monolayers on Au or SiO2 . Conductive atomic force microscopy showed that vertical conductivity is efficient and that it displays a low attenuation with foldamer length (0.06 Å-1 ). In contrast, horizontal charge transport is found to be negligible, demonstrating the strong anisotropy of foldamer monolayers...
October 1, 2017: Chemical Science
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