Search results for "COPP"
showing 10 items of 3147 documents
Isomorphous replacement of MII ions in MII–GdIII dimers (MII = CuII, MnII, NiII, CoII, ZnII): magnetic studies of the products
2011
Complexes [M(II)Gd(III){pyCO(OEt)pyC(OH)(OEt)py}₃](ClO₄)₂·EtOH [M(II) = Cu(II) (1), Mn(II) (2), Ni(II) (3), Co(II) (4) and Zn(II) (5)] crystallize in the monoclinic Cc space group and contain one hexacoordinate M(II) ion and one enneacoordinate Gd(III) ion, bridged by three {pyCO(OEt)pyC(OH)(OEt)py}⁻ ligands. Magnetic susceptibility measurements indicate a ferromagnetic interaction for 1 and antiferromagnetic interactions for 2-4. Using the Ĥ = -JŜ(Gd(III))Ŝ(M(II)) spin Hamiltonian formalism, fits to the magnetic susceptibility data yielded J values of +0.32 cm⁻¹ for 1, -1.7 cm⁻¹ for 2, and -0.22 cm⁻¹ for 3. In complex 4, the orbital contributions of Co(II) precluded the determination of th…
Exploring the Specificity of Rationally Designed Peptides Reconstituted from the Cell-Free Extract of Deinococcus radiodurans toward Mn(II) and Cu(II)
2020
A series of five rationally designed decapeptides [DEHGTAVMLK (DP1), THMVLAKGED (DP2), GTAVMLKDEH (Term-DEH), TMVLDEHAKG (Mid-DEH), and DEHGGGGDEH (Bis-DEH)] have been studied for their interactions with Cu(II) and Mn(II) ions. The peptides, constructed including the most prevalent amino acid content found in the cell-free extract of Deinococcus radiodurans (DR), play a fundamental role in the antioxidant mechanism related to its exceptional radioresistance. Mn(II) ions, in complex with these peptides, are found to be an essential ingredient for the DR protection kit. In this work, a detailed characterization of Cu(II) systems was included, because Cu(II)–peptide complexes have also shown r…
Cu-substituted lanthanum ferrite perovskites: Preparation, characterization and photocatalytic activity in gas-solid regime under simulated solar lig…
2016
Lanthanum orthoferrites LaFeO3 nanopowders doped with 20 mol% of Sr and 0-10-20 mol% of Cu were prepared by citrate auto-combustion synthesis and investigated in terms of crystal structure, morphology, surface area and optical properties by using several characterization techniques. The band gap energy values were found to range from 2.35 eV for LaFeO3 to 1.86 eV for the samples with the highest content of copper, this trend reflects the decrease of the particle size. All powders showed photocurrent response, the highest photocurrent was obtained for undoped orthoferrite calcined at 600°C. Their physical-chemical properties were related to photoelectrochemical behaviour. The the position of…
Materials, Techniques, and Conservation of Historic Stained Glass “Grisailles”
2015
A grisaille is a brown-blackish paint applied onto the inner surface of stained glass to draw the contours and details of the figures and to produce the effect of shades and volumes. Grisailles were traditionally made of finely ground oxides of iron but also of copper, zinc, lead, or manganese mixed with a flux such as lead ground glass and a binder and fixed onto the flat glass by firing. The grisailles have typical layer thickness varying between 10 and 100 µm and are formed by a complex mixture of pigment particles, crystalline, and amorphous reaction compounds, aging, and weathering compounds. The high brilliance, collimation, energy selection, and monochromacity of the SR beam are idea…
Immobilization of copper complexes with (1,10-phenanthrolinyl)phosphonates on titania supports for sustainable catalysis
2017
Different strategies for the immobilization of copper complexes with 1,10-phenanthroline (phen) using the phosphonate anchoring group were investigated to prepare robust and porous heterogeneous catalysts. Homoleptic and heteroleptic copper(I) complexes with phen bearing the bis(trimethylsiloxy)phosphoryl anchoring group (Pphen-Si) at different positions of the phen backbone were prepared and covalently incorporated into titania (TiO2) xerogels by using the sol–gel process or grafted onto the surface of mesoporous TiO2 (SBET = 650 m2 g−1). Copper(I) bis(Pphen-Si) complexes were the only complexes that were successfully anchored onto the TiO2 surface because the heterogenization was often ac…
Magnetostructural relationships in polymorphic ethylmalonate-containing copper(ii) coordination polymers
2018
Three ethylmalonate-containing copper(II) chiral complexes of the formula {[Cu(H2O)4][Cu(Etmal)2(H2O)]}n (1), [Cu(Etmal)(H2O)]n (2) and {[Cu(Etmal)(H2O)]·H2O}n (3) (H2Etmal = ethylmalonic acid) were obtained by reacting copper(II) nitrate trihydrate, ethylmalonic acid and sodium carbonate in water. Compound 1 is a chiral zigzag chain with regular alternation of [Cu(Etmal)2(H2O)]2− and [Cu(H2O)4]2+ units, the former acting as bis-monodentate ligands toward the latter ones through the two carboxylate groups. The chirality of 1 is a result of the [Cu(Etmal)2(H2O)]2− fragment whose five-coordinate copper(II) surrounding exhibits the Δ or Λ conformation within the Δ or Λ-crystals. The structure …
Dismantling and electrochemical copper recovery from Waste Printed Circuit Boards in H2SO4–CuSO4–NaCl solutions
2019
Abstract The worldwide growing of electrical and electronic equipment makes increasingly urgent to find environmentally friendly treatments for e-waste. In this paper, the attention has been focused on i) the eco-friendly dismantling of the electronic components from Waste Printed Circuit Boards and ii) recovering of pure metallic copper, which is the most abundant metal and one of the most valuable in Printed Circuit Boards. After an experimental optimization study, we found that a solution containing 0.5 M H2SO4, 0.4 M CuSO4, and 4 M NaCl can be successfully used to disassemble the electronic components from the boards by leaching of all exposed metals. Air was blown into the leaching sol…
Ein kalorimeter für hochenergetische elektronenstrahlen
1968
Abstract Construction details and experimental data are given for a total absorption calorimeter used for electron beams of several hundred MeV and for beam power up to 15 kW. In order to obtain high precision, precautions were taken to obtain very high heat insulation, specially by using a temperature controlled radiation shield. The heat loss of the 700 kg copper block corresponds to less than 10 −3 °C/h. Due to design calculations and confirmed by preliminary comparison tests with other beam monitors we consider the absolute accuracy to be 1% or probably better.
The influence of Zn$^{2+}$ ions on the local structure and thermochromic properties of Cu$_{1-x}$Zn$_x$MoO$_4$ solid solutions
2021
I. P., A. K. and A. K. would like to thank the support of the Latvian Council of Science project No. lzp-2019/1-0071. I.P. acknowledges the L‘OREAL Baltic “For Women In Science” Program with the support of the Latvian National Commission for UNESCO and the Latvian Academy of Sciences. The experiment at the PETRA III synchrotron was performed within project No. I-20190277 EC. The synchrotron experiments have been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2…
Interpretation of the Cu K-edge EXAFS spectra of Cu3N using ab initio molecular dynamics
2020
Financial support provided by ERDF project No. 1.1.1.2/VIAA/l/16/147 (1.1.1.2/16/I/001) under the activity “Post-doctoral research aid” realized at the Institute of Solid State Physics, University of Latvia is greatly acknowledged. This work was supported by a grant from the Swiss National Supercomputing Centre (CSCS) under the project ID s681 .