Destructive Adsorption of Carbon Tetrachloride on Alkaline Earth Metal Oxides

The destructive adsorption of CCl4 on MgO, CaO, SrO, and BaO has been studied as a function of the reaction temperature and the amount of CCl4 injected. The reaction was followed using in situ Raman spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and 13 C magic angle spinning nuclear magnetic resonance spectroscopy. It was found that the activity toward CCl4 parallels the basicity of the alkaline earth metal oxide; i.e., the activity decreased in the order BaO > SrO > CaO > MgO. Barium oxide readily reacted with CCl4 at 200-300 °C, and, at these low temperatures, CO2 was the only gas-phase product that evolved from the surface. At higher reaction temperatures, other alkaline earth metal oxides, such as CaO and MgO, also became active, and COCl2 was found to be a reaction intermediate in the destruction of CCl4. Although the destruction process is initiated at the surface, the continuous O 2- /Cl - exchange results in the bulk transformation of the metal oxide to the metal chloride. Barium oxide could be regenerated by dissolving the chloride in water, followed by precipitation as barium carbonate and subsequent calcination. In addition, carbon tetrachloride destruction at around 600 °C resulted in the formation of an unusual alkaline earth metal oxide chloride, viz., M4OCl6 (M ) Ba, Sr, or Ca)

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)

Scienza del Diritto

Ridescrivere la concettualità giuridica da una prospettiva costruttivista che permetta di afferrare la storicità del diritto, le possibilità e i limiti di questa macchina complesa nella quale si condensa la modernità della società modern

Thermal ageiing of Ni/C multilayers prepared by pulsed laser deposition

Ni/C multilayers are prepared by pulsed-laser deposition with different laser wavelengths. Specimens providing different interface constitutions are investigated in the initial state and after an annealing time of 20 min at temperatures between 50 and 400 degrees C. X-Ray reflectrometry and X-ray diffraction at grazing incidence of the radiation are applied for the characterisation of the samples. An increase of the double layer thickness with increasing temperature is observed for all multilayer samples. Generally this process starts at temperatures between 100 and 250 degrees C, but the sample with graded interfaces remain stable up to higher temperatures than those with abrupt interfaces. After heating at 400 degrees C the initially almost amorphous nickel layers crystallise in a thermodynamically stable f.c.c. lattice structure. For the sample with abrupt interfaces intermixing of nickel and carbon during deposition leads to the formation of crystalline nickel carbide between 200 a nd 300 degrees Celsius

Werkstoffinnovationen fuer integrierte Pyroarray-Membransysteme. Teilvorhaben: Mikrostrukturentwicklung von ferroelektrischen Duennschichtsystemen Abschlussbericht

SIGLEAvailable from TIB Hannover: F02B10 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman

Piezo-spectroscopic stress measurement near PZT-microstructures on silicon

Domain formation and polarization in ferroelectric films probably are strongly influenced by intrinsic stress. Raman microscopy offers the possibility to get informations about the stress state even in film structures with lateral dimensions of several ten microns. PZT (Pb[Zr,Ti]O3) microstructures with Pt bottom electrodes sputtered on silicon wafers were investigated using the Raman peak of the single crystalline silicon. Near edges of Pt and PZT films Raman shifts |\u394\u3bd| 641,5 cm-1 were measured corresponding to stresses in the silicon substrate near the interface in the order of several hundred MPa. The Raman shift profiles are dependent on the particular geometry of the investigated structures and specific micro structure defects near the edge. An estimate of the stress in the PZT film was obtained by modelling the stress in the silicon as a function of the distance from one edge using a finite element code