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41.
Understanding the dynamics of vortex matter subjected to random and correlated pinning disorders in layered superconductors
remains a topic of considerable interest. The dynamical behavior of vortices in these systems shows a rich variety of effects
due to many competing interactions. Here, we study the ac response of as-grown as well as heavy-ion-irradiated Tl2Ba2CaCu2O8 (Tl-2212) thin films by using a micro Hall-probe susceptometer. We find that the dynamics of vortices in the high-temperature,
low-field regime of the H-T phase diagram investigated here depends on the nature of pinning defects. While the decay of screening currents J(t) indicates a glassy behavior in both types of samples, the nature of the glassy phase is different in the two cases. Samples
with columnar defects show distinct signature of a Bose glass in the measurement of J(t) and the angular dependence of the irreversibility field (B irr). 相似文献
42.
M. V. Leena Chandra S. Karthikeyan S. Selvasekarapandian D. Vinoth Pandi S. Monisha S. Arulmozhi Packiaseeli 《Ionics》2016,22(12):2409-2420
A solid polymer blend electrolyte is prepared using poly(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA) polymers with different molecular weight percentage (wt%) of ammonium thiocyanate (NH4SCN) by solution casting technique with tetrahydrofuran (THF) as a solvent. The structural, morphological, vibrational, thermal and electrical properties of the prepared polymer blend electrolytes have been studied. The incorporation of NH4SCN into the polymeric matrix causes decrease in the degree of crystallinity of the samples. The complex formation between the polymer and salt has been confirmed by FTIR technique. The increase in T g with increase in salt concentration has been investigated. The maximum conductivity of 3.684?×?10?3 S cm?1 has been observed for the composition of 70PVAc/30PMMA/30 wt% of NH4SCN at 303 K. This value of ionic conductivity is five orders of magnitude greater than that of 70PVAc/30PMMA polymer membrane. Dielectric and transport studies have been done. The highest conducting polymer electrolyte is used to fabricate proton battery with the configuration Zn/ZnSO4·7H2O (anode) ||polymer electrolyte||PbO2/V2O5 (cathode). The open circuit voltage of the fabricated battery is 1.83 V, and its performance has been studied. 相似文献
43.
44.
Shreyas Supekar Dr. Ana P. Gamiz‐Hernandez Prof. Dr. Ville R. I. Kaila 《Angewandte Chemie (International ed. in English)》2016,55(39):11940-11944
Cytochrome c oxidase (CcO) is a redox‐driven proton pump that powers aerobic respiratory chains. We show here by multi‐scale molecular simulations that a protonated water cluster near the active site is likely to serve as the transient proton‐loading site (PLS) that stores a proton during the pumping process. The pKa of this water cluster is sensitive to the redox states of the enzyme, showing distinct similarities to other energy converting proton pumps. 相似文献
45.
46.
Boonta Chutvirasakul Nantana Nuchtavorn Leena Suntornsuk Yong Zeng 《Electrophoresis》2020,41(5-6):311-318
Exosome quantification is important for estimation of informative messengers (e.g., proteins, lipids, RNA, etc.) involving physiological and pathological effects. This work aimed to develop a simple and rapid distance-based paper portable device using exosome-capture vesicles (polydiacetylene conjugated with antiCD81) for exosome quantification in cell cultures. This novel concept relied on distinct aggregation of exosomes and exosome-capture vesicles leading to different solvent migration. Distances of the migration were used as signal readouts, which could be detected by naked eye. PDA-antiCD81 as exosome-capture vesicles were optimized (e.g., size, reaction ratio, and concentration) and the paper designs were investigated (e.g., diameter of sample reservoir and lamination layer) to enhance the solvent stop-flow effects. Finally, exosome screening on three cell culture samples (COLO1, MDA-MB-231, and HuR-KO1 subclone) was demonstrated. The method could linearly measure exosome concentrations in correlation with solvent migration distances in the range of 106–1010 particles/mL (R2 > 0.98) from the cell culture samples. The exosome concentration measurements by the developed device were independently assessed by nanoparticle tracking analysis. Results demonstrated no statistically significant difference (p > 0.05) by t-test. This low-cost and rapid device allows a portable platform for exosome quantification without the requirement of expensive equipment and expertise of operation. The developed device could potentially be useful for quantification of other biomarker-related extracellular vesicles. 相似文献
47.
Hitesh B. JalaniAmit N. Pandya Arshi B. BaraiyaJitendra C. Kaila Dhaivat H. PandyaJayesh A. Sharma V. SudarsanamKamala K. Vasu 《Tetrahedron letters》2011,52(48):6331-6335
Herein, we report an efficient and facile synthesis of substituted 2-aminopyrroles from the reaction of enaminone-amidine adduct and various phenacyl, benzyl, or heteroalkyl halides in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in good to excellent yields. The reaction proceeds through an intramolecular 5-exo trig cyclization resulting into diversely substituted 2-aminopyrroles. 相似文献
48.
Proton transfer (pT) reactions in biochemical processes are often mediated by chains of hydrogen-bonded water molecules. We use hybrid density functional calculations to study pT along quasi one-dimensional water arrays that connect an imidazolium-imidazole proton donor-acceptor pair. We characterize the structures of intermediates and transition states, the energetics, and the dynamics of the pT reactions, including vibrational contributions to kinetic isotope effects. In molecular dynamics simulations of pT transition paths, we find that for short water chains with four water molecules, the pT reactions are semi-concerted. The formation of a high-energy hydronium intermediate next to the proton-donating group is avoided by a simultaneous transfer of a proton from the donor to the first water molecule, and from the first water molecule into the water chain. Lowering the dielectric constant of the environment and increasing the water chain length both reduce the barrier for pT. We study the effect of the driving force on the energetics of the pT reaction by changing the proton affinity of the donor and acceptor groups through halogen and methyl substitutions. We find that the barrier of the pT reaction depends linearly on the proton affinity of the donor but is nearly independent of the proton affinity of the acceptor, corresponding to Br?nsted slopes of one and zero, respectively. 相似文献
49.
Fliegl H Lehtonen O Sundholm D Kaila VR 《Physical chemistry chemical physics : PCCP》2011,13(2):434-437
We present here a "non-invasive" computational method to estimate the strength of individual hydrogen bonds using magnetically induced currents. The method is calibrated using H-bonding dimers, and applied on Watson-Crick DNA base pairs and proton wires in carbonic anhydrase. 相似文献
50.
Kirsi S. Mikkonen Leena Pitk?nen Ville Liljestr?m Elina Mabasa Bergstr?m Ritva Serimaa Lennart Salmén Maija Tenkanen 《Cellulose (London, England)》2012,19(2):467-480
The chemical structure of rye arabinoxylan (rAX) was systematically modified, exploiting selective enzymes to mimic different
naturally occurring xylans, i.e., its degree of substitution (DS) was decreased using α-l-arabinofuranosidase, and a controlled decrease in the degree of polymerization (DP) was performed using endo-1,4-β-d-xylanase. The arabinose to xylose ratio was decreased from 0.45 to 0.27 and the weight-average molar mass was decreased from
184,000 to 49,000 g/mol. The resulting samples were used to prepare films, as such, and with 15% (wt. − %) softwood-derived
microfibrillated cellulose (MFC) to obtain novel plant-derived biocomposite materials. The enzymatic tailoring of rAX increased
the crystallinity of films, evidenced by X-ray diffraction studies, and the addition of MFC to the debranched, low DS rAX
induced the formation of ordered structures visible with polarizing optical microscopy. MFC decreased the moisture uptake
of films and increased the relative humidity of softening of the films, detected with moisture scanning dynamic mechanical
analysis. For the first time, the chemical structure of xylan was proven to significantly affect the reinforcement potential
of nano-sized cellulose, as the tensile strength of films from high DP rAXs, but not that of low DP rAXs, clearly increased
with the addition of MFC. At the same time, MFC only increased the Young’s modulus of films from rAX with high arabinose content,
regardless of DP. 相似文献