LiCo1−yMyO2 positive electrodes for rechargeable lithium batteries: II. Nickel substituted materials grown by the citrate method

[Abstract] The layered LiCo1−yNiyO2 microcrystalline powders were synthesized by a sol–gel method using citric acid as a chelating agent in the range 0.2 ≤ y ≤ 0.8. Submicron-sized particles of the precursor were obtained at temperature below 400 °C and microcrystalline powders were grown by thermal treatment at 700 °C for 5 h in air. The carboxylic-based acid functioned such as a fuel, decomposed the homogeneous precipitate of metal complexes at low temperature, and yielded the free impurity LiCo1−yNiyO2 single-phases suitable for electrochemical applications. The synthesized products were characterized by structural, spectroscopic and thermal analyses. FT-IR measurements provide information on the growth process and the final local environment in the cationic sublattice of LiCo1−yNiyO2 solid solution. The electrochemical performance of the synthesized products in rechargeable Li cells was evaluated using non-aqueous solution 1 M LiPF6 in EC-DMC as electrolyte. The electrochemical features of a series of LiCo1−yNiyO2 compounds (0.2 ≤ y ≤ 1.0) are discussed in relation with their synthesis procedure and substitutive amount. The substitution of Ni3+ for Co3+ in LiCo1−yNiyO2 for y = 0.75 shows improvement of the specific capacity at ca. 187 mAh/g upon 32 cycles

Single-Molecule Analysis Reveals the Kinetics and Physiological Relevance of MutL-ssDNA Binding

DNA binding by MutL homologs (MLH/PMS) during mismatch repair (MMR) has been considered based on biochemical and genetic studies. Bulk studies with MutL and its yeast homologs Mlh1-Pms1 have suggested an integral role for a single-stranded DNA (ssDNA) binding activity during MMR. We have developed single-molecule Förster resonance energy transfer (smFRET) and a single-molecule DNA flow-extension assays to examine MutL interaction with ssDNA in real time. The smFRET assay allowed us to observe MutL-ssDNA association and dissociation. We determined that MutL-ssDNA binding required ATP and was the greatest at ionic strength below 25 mM (KD = 29 nM) while it dramatically decreases above 100 mM (KD>2 µM). Single-molecule DNA flow-extension analysis suggests that multiple MutL proteins may bind ssDNA at low ionic strength but this activity does not enhance stability at elevated ionic strengths. These studies are consistent with the conclusion that a stable MutL-ssDNA interaction is unlikely to occur at physiological salt eliminating a number of MMR models. However, the activity may infer some related dynamic DNA transaction process during MMR

Design concepts for the Cherenkov Telescope Array CTA: an advanced facility for ground-based high-energy gamma-ray astronomy

Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA

Cosmic ray oriented performance studies for the JEM-EUSO first level trigger

JEM-EUSO is a space mission designed to investigate Ultra-High Energy Cosmic Rays and Neutrinos (E > 5 ⋅ 1019 eV) from the International Space Station (ISS). Looking down from above its wide angle telescope is able to observe their air showers and collect such data from a very wide area. Highly specific trigger algorithms are needed to drastically reduce the data load in the presence of both atmospheric and human activity related background light, yet retain the rare cosmic ray events recorded in the telescope. We report the performance in offline testing of the first level trigger algorithm on data from JEM-EUSO prototypes and laboratory measurements observing different light sources: data taken during a high altitude balloon flight over Canada, laser pulses observed from the ground traversing the real atmosphere, and model landscapes reproducing realistic aspect ratios and light conditions as would be seen from the ISS itself. The first level trigger logic successfully kept the trigger rate within the permissible bounds when challenged with artificially produced as well as naturally encountered night sky background fluctuations and while retaining events with general air-shower characteristics

LiCo1-yMyO2 positive electrodes for rechargeable lithium batteries. II. Nickel substituted materials grown by the citrate method

International audienceThe layered LiCo1-yNiyO2 microcrystalline powders were synthesized by a sol-gel method using citric acid as a chelating agent in the range 0.2 <= y <= 0.8. Submicron-sized particles of the precursor were obtained at temperature below 400 degrees C and microcrystalline powders were grown by thermal treatment at 700 degrees C for 5 h in air. The carboxylic-based acid functioned such as a fuel, decomposed the homogeneous precipitate of metal complexes at low temperature, and yielded the free impurity LiCo1-yNiyO2 single-phases suitable for electrochemical applications. The synthesized products were characterized by structural, spectroscopic and thermal analyses. FT-IR measurements provide information on the growth process and the final local environment in the cationic sublattice of LiCo1-yNiyO2 solid solution. The electrochemical performance of the synthesized products in rechargeable Li cells was evaluated using non-aqueous solution I M LiPF6 in EC-DMC as electrolyte. The electrochemical features of a series of LiCo1-yNiyO2 compounds (0.2 <= y <= 1.0) are discussed in relation with their synthesis procedure and substitutive amount. The substitution of Ni3+ for Co3+ in LiCo1-yNiyO2 for y = 0.75 shows improvement of the specific capacity at ca. 187 mAh/g upon 32 cycles. (c) 2005 Elsevier B.V. All rights reserved

The efficacy of surfactants in stabilizing coating of nano-structured CuO particles onto the surface of cotton fibers and their antimicrobial activity

The efficacy of surfactants in stabilizing CuO-NPs onto the surface of the cotton fibers and their ability to produce homogeneous CuO-coated cotton composite was studied using different types of surfactants. The use of surfactants provides better adhesion of the CuO NPs and consequence, enhanced its coating stability during exploitation. The optical structure and morphology of the coated cotton fabrics were examined by several methods include: X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform spectroscopy (FTIR). The CuO-NPs-coated cotton fabrics have resisted the intensive 10 washing cycles in particular, in presence of SDS (25% loss of CuO) in comparison with TX-100 (66.5% loss of CuO). The CuO-NPs coated cotton materials have also showed an excellent inhibition for the growth of the medically relevant staphylococcus aureus

Nano-structured zinc oxide-cotton fibers: synthesis, characterization and applications

International audienceZinc oxide nanoparticles were prepared and subsequently deposited onto the surface of the cotton fiber by ultrasonic irradiation. The optical, structure and morphology of the coated and un-coated cotton were examined by UV, fourier transform infrared spectroscopy, X-ray diffraction analysis (XRD) and scanning electron microscope (SEM)/Energy Dispersive X-ray analysis. XRD analysis revealed the presence of the crystalline metal oxide of hexagonal phase with an average crystallite size of 12 nm. These nanoparticles are probably physically adsorbed onto the cotton fiber surface. SEM analysis showed a distribution of ZnO nanorod assemblies of various diameters and lengths physically adsorbed onto the cotton fiber surface may take place. The ZnO-cotton fiber nano-composite were tested against Escherichia coli (gram negative) and Staphylococcus aureus (gram positive) cultures, and showed a significant antimicrobial activity