Biological maturation and β-adrenergic effectors: development of β-adrenergic receptors in rabbit heart

The β-adrenergic receptor, transduction processes and catalytic activity of the adenylate cyclase enzyme complex have been investigated in rabbit heart at different stages of biological maturation. The binding of [ 3 H]-dihydroalprenolol to a washed membrane preparation isolated from rabbit ventricular muscle was used to characterize β-adrenergic receptors. Significant age-related differences were noted in β-receptor affinity (K d ) and density (RD) of neonatal and adult animals; the adult K d was 3.7-fold greater and the RD 2-fold higher than the neonates. No significant differences in these parameters were detected among the 27-day old fetus and the 1- and 7-day old neonates. Age-dependent differences in agonist isoproterenol affinity for the receptor were not observed in contrast to the significant changes in antagonist (DHA) affinity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45349/1/11010_2004_Article_BF00240617.pd

Comprehensive study of the CuF<inf>2</inf> conversion reaction mechanism in a lithium ion battery

Conversion materials for lithium ion batteries have recently attracted considerable attention due to their exceptional specific capacities. Some metal fluorides, such as CuF2, are promising candidates for cathode materials owing to their high operating potential, which stems from the high electronegativity of fluorine. However, the high ionicity of the metal–fluorine bond leads to a large band gap that renders these materials poor electronic conductors. Nanosizing the active material and embedding it within a conductive matrix such as carbon can greatly improve its electrochemical performance. In contrast to other fluorides, such as FeF2 and NiF2, good capacity retention has not, however, been achieved for CuF2. The reaction mechanisms that occur in the first and subsequent cycles and the reasons for the poor charge performance of CuF2 are studied in this paper via a variety of characterization methods. In situ pair distribution function analysis clearly shows CuF2 conversion in the first discharge. However, few structural changes are seen in the following charge and subsequent cycles. Cyclic voltammetry results, in combination with in situ X-ray absorption near edge structure and ex situ nuclear magnetic resonance spectroscopy, indicate that Cu dissolution is associated with the consumption of the LiF phase, which occurs during the first charge via the formation of a Cu1+ intermediate. The dissolution process consequently prevents Cu and LiF from transforming back to CuF2. Such side reactions result in negligible capacity in subsequent cycles and make this material challenging to use in a rechargeable battery.We acknowledge the funding from the U.S. DOE BES via funding to the EFRC NECCES, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001294 (support for Rosa Robert and Lin-Shu Du) and EPSRC via the “nanoionics” programme grant (support for Xiao Hua). Use of the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory (BNL), was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886. Use of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357.This is the final published version of the article. It first appeared at http://pubs.acs.org/doi/abs/10.1021/jp503902z and is posted here under the terms of ACS's Editors' Choice scheme (http://pubs.acs.org/page/policy/authorchoice_termsofuse.html)

Postprocessing of nm-period multilayer structure

We study effects of macro- and micro-postprocessing of multilayered synthetic Ni/C film structures. The structures have nm-period one-dimensional modulation of concentration of the major components. Initially low surface and interface roughness of such structures makes them advantageous for application as a new type of substrates n nanofabrication technologies and for information storage with nm-resolution. Metastability of microstructure and high residual stresses favour the use of the structures themselves as a media for fine-scale processing

Structure and mechanical behaviour of short glass fibre-reinforced ethylene-tetrafluoroethylene copolymers

The mechanical behaviour of a copolymer, consisting of ethylene, tetrafluoroethylene, hexafluoropropylene and perfluoropropylvinylether, unfilled and filled with short glass fibres has been investigated for strains less than 5%. Different deformation modes at room temperature and at 80 °C were recorded with a video system. The resulting stress-strain, relaxation and shrinkage curves are described with a model consisting of seven basic rheological elements of three different types: spring (Hooke model), dashpot (Newton model) and slip-element (St. Vénant model). This seven-element model gives a very good approximation of all the investigated deformation modes and allows an interpretation of relaxation and retardation times of polymer segments. The plastic deformation, described by the slip-element, is assumed to be caused by slip processes in the highly disordered crystallites of the copolymer matrix

Control of hydrogen photoproduction by the proton gradient generated by cyclic electron flow in Chlamydomonas reinhardtii.

Hydrogen photoproduction by eukaryotic microalgae results from a connection between the photosynthetic electron transport chain and a plastidial hydrogenase. Algal H(2) production is a transitory phenomenon under most natural conditions, often viewed as a safety valve protecting the photosynthetic electron transport chain from overreduction. From the colony screening of an insertion mutant library of the unicellular green alga Chlamydomonas reinhardtii based on the analysis of dark-light chlorophyll fluorescence transients, we isolated a mutant impaired in cyclic electron flow around photosystem I (CEF) due to a defect in the Proton Gradient Regulation Like1 (PGRL1) protein. Under aerobiosis, nonphotochemical quenching of fluorescence (NPQ) is strongly decreased in pgrl1. Under anaerobiosis, H(2) photoproduction is strongly enhanced in the pgrl1 mutant, both during short-term and long-term measurements (in conditions of sulfur deprivation). Based on the light dependence of NPQ and hydrogen production, as well as on the enhanced hydrogen production observed in the wild-type strain in the presence of the uncoupling agent carbonyl cyanide p-trifluoromethoxyphenylhydrazone, we conclude that the proton gradient generated by CEF provokes a strong inhibition of electron supply to the hydrogenase in the wild-type strain, which is released in the pgrl1 mutant. Regulation of the trans-thylakoidal proton gradient by monitoring pgrl1 expression opens new perspectives toward reprogramming the cellular metabolism of microalgae for enhanced H(2) production