Search results for "COPP"
showing 10 items of 3147 documents
Fast synthesis of single-phased 110 K bismuth superconductor by freeze-drying of acetic precursors. Kinetic role of calcium and copper oxides
1993
Abstract Although the usefulness of solution procedures to improve the synthesis of bismuth HTSC has been argued, an adequate control of the procedural variables has allowed us to isolate the 110 K phase as the only superconducting phase after such a short sintering time as 22 h. The precursors used have been freeze-dried powders resulting from acetic solutions containing excess Ca and Cu. TGA-DTA and XRD experiments have been performed to follow the subsequent solid-state reaction processes. The initial formation of a mixed bismuth-lead oxoacetate, as intermediate to (Bi 1− y Pb y ) 2 CuO 4 , and the presence of an excess of Ca 2 CuO 3 in the last reaction step are two of the main factors …
Discovering Copper for Methane C–H Bond Functionalization
2015
The copper complex Tp(CF3)2,BrCu(NCMe) (1, Tp(CF3)2,Br = hydrotris((3,5-bis(trifluoromethyl)-4-bromo)-pyrazol-1-yl)borate) catalyzes the insertion of the CHCO2Et group (from ethyl diazoacetate N2CHCO2Et, EDA) into the C–H bonds of methane, in a homogeneous process that uses supercritical carbon dioxide (scCO2) as the reaction medium. Other light alkanes such as ethane, propane, and butane have been also functionalized with this copper-based catalyst, in the first example of the derivatization of the series of C1–C4 alkanes with this metal and a soluble catalyst.
Computer simulation of disordering and premelting of low-index faces of copper.
1992
Molecular dynamics and the effective-medium theory have been applied to investigate the structure and dynamics of (110), (100), and (111) faces of copper in the whole temperature range from 0 K up to the bulk melting point, which has been determined to be 1240\ifmmode\pm\else\textpm\fi{}25 K. The observed order in the surface stability follows the order in the packing density. (110) disorders first via anharmonic effects (up to 700 K), then by vacancy-adatom formation and finally by premelting of the surface at about 1200 K. The (110) solid-melt interface is anisotropic and broadened, having a tendency to form small fluctuating (111) facets in equilibrium, which is suggested to be the atomi…
Synthesis and Magnetic Properties of a Copper Cube: [Cu 4 (OH) 4 (C 16 H 18 N 2 ) 4 ] 4+ (ClO 4 ) 4 C 3 H 6 O [C 16 H 18 N 2 =( E )‐1,6‐[Di(pyridin‐4…
2019
We are grateful to the National Mass Spectrometry Service Center for mass spectra and to the UK National Crystallography Service for data sets. Supplementary Figure S1-S4: IR and UV/Vis spectra of compound 1
Control and Simplicity in the Nanoprocessing of Semiconducting Copper-Iodine Double Chain Coordination Polymers
2018
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Inorganic Chemistry © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/abs/10.1021/acs.inorgchem.8b00364
Roughening of the Cu(110) surface
1993
The structure of the Cu(110) surface is studied at high temperatures using a combination of lattice-gas Monte Carlo and molecular dynamics methods with identical many-atom interactions derived from the effective medium theory. The anisotropic six-vertex model is used in the interpretation of the lattice-gas results. We find a clear roughening transition around T_R=1000K and T_R/T_M=0.81. Molecular dynamics reveals the clustering of surface defects as the atomistic mechanism of the transition and allows us to estimate characteristic time scales. For the system of size 50x50, the time scale of the local roughening at 1150 K of an initially smooth surface is of the order of 100 ps.
Fluorinated Fullerene Molecule on Cu(001) Surface as a Controllable Source of Fluorine Atoms
2018
A coverage-dependent growth of well-ordered copper halogenide structures as a result of fluorinated fullerene molecule adsorption on Cu(001) surface has been studied by means of scanning tunneling ...
The oxidation state of a protein observed molecole-by-molecule.
2005
We report the observation of the redox state of the blue copper protein azurin on the single-molecule level. The fluorescence of a small fluorophore attached to the protein is modulated by the change in absorption of the copper center via fluorescence resonance energy transfer (FRET). In our model system, the fluorescence label Cy5 was coupled to azurin from Pseudomonas aeruginosa via cysteine K27C. The Cy5 fluorescence was partially quenched by the absorption of the copper center of azurin in its oxidized state. In the reduced state, absorption is negligible, and thus no quenching occurs. We report on single-molecule measurements, both in solution by using fluorescence correlation spectros…
Thermally Regenerative Ammonia Batteries for Waste-Heat Exploitation
2018
It is widely accepted that one of the most important issue to be faced by the scientific community is how to sustain the modern way of living and the related energy demand. While a long term target is the transition to a full-renewable energy system, a closer exigency is the optimization of the processes already existing. It has been calculated that about 370.41 TWh of potential energy is annually lost in Europe in the form of waste-heat from the industrial sector [1]. Waste heat comprises all the thermal energy with a temperature below 130 °C [2] (or 300 °C [1]), that hardly can find a useful application with the state of the art industrial technologies. Indeed, electrochemical technologie…
Electrochemical analysis of the alterations in copper pigments using charge transfer coefficient/peak potential diagrams. Application to microsamples…
2001
The alteration of copper pigments in art samples was studied by linear scan and cyclic voltammetry using sample-modified Elvacite 2044 film electrodes on the basis of two-dimensional diagrams of charge transfer coefficients calculated from Tafel plots of reductive dissolution processes vs. peak potential. Characteristic voltammetric peaks were obtained for pigments used in the baroque vault frescoes of the Basílica de la Virgen de los Desamparados painted by Antonio Palomino. Results obtained by voltammetric techniques were compared with those from SEM/EDX and FT-IR analysis obtaining a good agreement and leaving to an unambiguous identification of pigments used by Palomino and their altera…