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Results for “COPPER”
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Supercritical methanol depolymerization and hydrodeoxygenation of lignin and biomass over reduced copper porous metal oxides
Supercritical methanol upgrading with a CuMgAlO x catalyst is effective at depolymerizing and hydrodeoxygenating lignin into monomers and oligomers.
Effect of ligand substituents on nickel and copper [N 4 ] complexes: electronic and redox behavior, and reactivity towards protons
The ligand substituents have a major effect on the redox potentials, catalytic efficiency and robustness of the complexes in HER.
Altered copper homeostasis underlies sensitivity of hepatocellular carcinoma to copper chelation
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Selective hydroxylation of aryl iodides to produce phenols under mild conditions using a supported copper catalyst
Atomically dispersed Cu catalyst was designed for highly efficient hydroxylation of aryl iodides under mild conditions.
Oxygen-atom transfer photochemistry of a molecular copper bromate complex
Here, we report the synthesis and oxygen-atom transfer (OAT) photochemistry of [Cu(tpa)BrO 3 ]ClO 4 . In situ spectroscopy and in crystallo experiments indicate OAT proceeds from a Cu–O fragment generated by sequential Cu–O bond cleavage and OAT from BrO x to [Cu(tpa)] + . Furthermore, these results highlight synthetic opportunities in M–O photochemistry and demonstrate the utility of in crystallo experiments to evaluating photochemical reaction mechanisms.
The effect of copper on the sub-bandgap density of states of CdTe solar cells
Two optical sub-bandgap transitions in CdTe thin-film solar cells have been identified using detailed transient photocapacitance and transient photocurrent spectroscopy measurements. A broad response centered at E V + 0.9 eV directly correlates with the quantity of Cu present in the absorber layer, while a second response at E V + 1.2 eV does not depend on Cu or Zn and may be an intrinsic defect. Furthermore, these results demonstrate the influence of Cu on the sub-bandgap density of states of CdTe, and they are critical to understanding, modeling, and improving its optoelectronic properties.
Copper-zinc superoxide dismutase is activated through a sulfenic acid intermediate at a copper ion entry site
Abstract not provided
Galvanic corrosion of copper-coated carbon steel for used nuclear fuel containers
Not Available
rf breakdown measurements in electron beam driven 200 GHz copper and copper-silver accelerating structures
Not Available
Determining whether metals nucleate homogeneously on graphite: A case study with copper
In this study, we observe that Cu clusters grow on surface terraces of graphite as a result of physical vapor deposition in ultrahigh vacuum. We show that the observation is incompatible with a variety of models incorporating homogeneous nucleation and calculations of atomic-scale energetics. An alternative explanation, ion-mediated heterogeneous nucleation, is proposed and validated, both with theory and experiment. This serves as a case study in identifying when and whether the simple, common observation of metal clusters on carbon-rich surfaces can be interpreted in terms of homogeneous nucleation. We describe a general approach for making system-specific and laboratory-specific predictions.
Control of the third dimension in copper-based square-lattice antiferromagnets
Using a mixed-ligand synthetic scheme, we create a family of quasi-two-dimensional antiferromagnets, namely, [Cu(HF 2 )(pyz) 2 ]ClO 4 [pyz = pyrazine], [CuL 2 (pyz) 2 ](ClO 4 ) 2 [L = pyO = pyridine-N-oxide and 4-phpy-O = 4-phenylpyridine-N-oxide. These materials are shown to possess equivalent two-dimensional [Cu(pyz) 2 ] 2+ nearly square layers, but exhibit interlayer spacings that vary from 6.5713 to 16.777 Å, as dictated by the axial ligands. We present the structural and magnetic properties of this family as determined via x-ray diffraction, electron-spin resonance, pulsed- and quasistatic-field magnetometry and muon-spin rotation, and compare them to those of the prototypical two-dimensional magnetic polymer Cu(pyz) 2 (ClO 4 ) 2 . We find that, within the limits of the experimental error, the two-dimensional, intralayer exchange coupling in our family of materials remains largely unaffected by the axial ligand substitution, while the observed magnetic ordering temperature (1.91 K for the material with the HF 2 axial ligand, 1.70 K for the pyO and 1.63 K for the 4-phpy-O) decreases slowly with increasing layer separation. Despite the structural motifs common to this family and Cu(pyz) 2 (ClO 4 ) 2 , the latter has significantly stronger two-dimensional exchange interactions and hence a higher ordering temperature. Here, we discuss these results, as well as the mechanisms that might drive the long-range order in these materials, in terms of departures from the ideal S = 1/2 two-dimensional square-lattice Heisenberg antiferromagnet. In particular, we find that both spin-exchange anisotropy in the intralayer interaction and interlayer couplings (exchange, dipolar, or both) are needed to account for the observed ordering temperatures, with the intralayer anisotropy becoming more important as the layers are pulled further apart.
Origin of the Bismuth-Induced Decohesion of Nickel and Copper Grain Boundaries
Not Available
Neutron and X-ray investigations of the Jahn–Teller switch in partially deuterated ammonium copper Tutton salt, (NH 4 ) 2 [Cu(H 2 O) 6 ](SO 4 ) 2
The structural phase transition accompanied by a Jahn–Teller switch has been studied over a range of H/D ratios in (NH 4 ) 2 [Cu(H 2 O) 6 ](SO 4 ) 2 (ACTS). In particular, single-crystal neutron diffraction investigations of crystals with deuteration in the range 50 to 82% are shown to be consistent with previous electron paramagnetic resonance (EPR) experiments exhibiting a phase boundary at 50% deuteration under ambient pressure. Polycrystalline samples show that the two phases can co-exist. In addition, single-crystal neutron and polycrystalline X-ray diffraction pressure experiments show a shift to lower pressure at 60% deuteration versus previous measurements at 100% deuteration.
Thermodynamics of copper‐manganese and copper‐iron spinel solid solutions
Abstract High‐temperature oxide melt solution calorimetry has been performed to investigate the energetics of spinel solid solutions in the Mn 3 O 4 ‐CuMn 2 O 4 and Fe 3 O 4 ‐CuFe 2 O 4 systems. The spinel solid solutions were synthesized by a ceramic route and calcined at appropriate temperatures to obtain single phase samples. The drop solution enthalpies of the solid solutions in the Mn 3 O 4 ‐CuMn 2 O 4 system are the same within experimental error as the enthalpies of drop solution of mechanical mixtures of the end‐members, indicating a zero heat of mixing, i.e., ideal mixing in terms of enthalpy. In Fe 3 O 4 ‐CuFe 2 O 4 , the drop solution enthalpy of the solid solutions shows a positive deviation from those of the mechanical mixture of the end‐members, suggesting negative mixing enthalpy. The formation enthalpies of the spinel solid solutions from their constituent oxides plus oxygen and from the elements were also determined.
Condensation on Superhydrophobic Copper Oxide Nanostructures
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