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21.
EPR and magnetic susceptibility experiments have been performed on x(CuO·MnO)(1?x)[2B2O3·K2O] glasses with x varying in the range 0?x?50 mol.%. For x?3 mol.% both Cu2+ and Mn2+ ions are present mostly as the isolated species. The increase of the g-tensor values and bonding parameters (α2, β2, δ2) for Cu2+ ions together with the increase of TM ions concentration in the 0.2–1 mol.% range was noticed. In the case of 5 ? x ? 30 mol.% the dipole-dipole and superexchange interactions occur between transition metal ions, the first type of interactions prevailing in this range of concentration. For x30 mol.% the superexchange interaction prevail. The strong interaction between Cu2+ and Mn2+ gives rise to the exchange coupled Cu2+Mn2+ pairs in the studied glasses with x 3 mol.%. 相似文献
22.
Campos J Esqueda AC López-Serrano J Sánchez L Cossio FP de Cozar A Alvarez E Maya C Carmona E 《Journal of the American Chemical Society》2010,132(47):16765-16767
The synthesis and structural characterization of a mixed-sandwich (η(5)-C(5)Me(5))Rh(III) complex of the cyclometalated phosphine PMeXyl(2) (Xyl = 2,6-C(6)H(3)Me(2)) with unusual κ(4)-P,C,C',C' coordination (compound 1-BAr(f); BAr(f) = B(3,5-C(6)H(3)(CF(3))(2))(4)) are reported. A reversible κ(4) to κ(2) change in the binding of the chelating phosphine in cation 1(+) induced by dihydrogen and hydrosilanes triggers a highly efficient Si-H/Si-D (or Si-T) exchange applicable to a wide range of hydrosilanes. Catalysis can be carried out in an organic solvent solution or without solvent, with catalyst loadings as low as 0.001 mol %, and the catalyst may be recycled a number of times. 相似文献
23.
E. Forizs L. David O. Cozar V. Chiş C. Craciun R. Tetean M. Todica 《Applied magnetic resonance》1999,16(4):499-506
The CuL2X2 (L = 7-chlor-l,3-dihydro-3-hydroxi-5-phenyl-2H-l,4-benzodiazepin-2-one, also known as oxazepam, X = Cl, Br) complexes were prepared and investigated by ESR (electron spin resonance) method. Powder ESR spectra of CuL2X2 compounds at room temperature show the presence of monomeric species having an axial symmetry with a small rhombic distortion. In case of compounds with Cl there is a superposition of two nonequivalent mononuclear species, one with adx2 - y2 d_{x^2 - y^2 } ground state and another with adz2 d_{z^2 } ground state. In pyridine (Py) and dimethylformamide (DMF) solutions the monomeric species prevail. Two different monomeric species, one with pseudotetrahedral (Td) and the other with elongated tetrahedral-octahedral symmetry, were evidenced in DMF solutions adsorbed on NaY zeolite. In Py-DMF solutions two monomeric species were also identified. Dimeric species appear in DMF and Py solutions adsorbed on NaY zeolite through the coordination of two Cu(II) ions at the same keto-oxygen from one oxazepam molecule. 相似文献
24.
I. Ardelean Gh. Ilonca O. Cozar I. Chicinaş Gh. Ciologria 《Solid State Communications》1982,43(9):707-709
The results of magnetic studies on xCuO · (1 ? x) [2B2O3 · PbO] glasses with 0 ? x ? 50 mol.%, are reported. These results evidenced that the copper ions, in this glass system, are in Cu2+ and Cu+ valence states. From Curie constant is determined the amount of the copper ions in bivalent state. For glasses with x > 5 mol.% CuO, an antiferromagnetic behaviour is evidenced. 相似文献
25.
Daraban L Cosma C Fiat T Cozar O Croitoru MD 《Analytical and bioanalytical chemistry》1996,355(3-4):370-371
A nondestructive method has been used for the qualitative and quantitative determination of elements such as Au, Cu, Ag in minerals and especially in golden sand. The induced radioactivity has been analyzed with a high resolution gamma spectrometer containing a Ge(Li) semiconductor detector type and a multichannel analyzer. The samples have been collected from the alluvia of the Mure? and Some?ul Mic river basins, proving the presence of gold and copper in small concentrations. These results have been correlated to previous data showing the existence of some gold mines in these zones. This nondestructive, rapid and highly sensitive method can be used for industrial processes [1] control and prospections. The use of a NaI(Tl) scintillation crystal for routine measurements of the 198Au radioisotope type and the interferences by copper, silver and indium in the irradiated samples are discussed. 相似文献
26.
O. Cozar I. Bratu L. David C. Crăciun A. Hernanz R. Navarro M. de la Fuente C. Bălan 《Applied magnetic resonance》2001,21(1):71-78
Electron paramagnetic resonance investigation of the Cu(II) complexes with guanosine-5′-monophosphate (5′-GMP) and cytidine-5′-monophosphate (5′-CMP) shows the affinity of the Cu(II) ion to interact with the base and the phosphate group. The different modes of the coordination of the metal ion at the nucleotide and the water molecules lead to octahedral species, distorted by dynamical Jahn-Teller effect (g0 = 2.106) for the Cu(II)-5′-CMP complex and rhombically distorted (g1 = 2.358, g2 = 2.126, g3 = 2.068) or tetragonally distorted (g∥′ = 2.299, g⊥′ = 2.126) for the Cu(II)-5′ -GMP complex. The compound with 5′-CMP presents also a more stable in time square-planar species (g∥ = 2.265, A∥ = 162 G, g⊥ = 2.076). The local symmetry changes in aqueous solution by coordination of water molecules. 相似文献
27.
O. Cozar I. Ardelean V. Simon L. David V. Mih N. Vedean 《Applied magnetic resonance》1999,16(4):529-537
EPR investigation on xV2O5 · (100 −x)[2P2O5 · Na2O] and xV2O5 · (100 −x)[P2O5 · mNa2O] (m = 1.5 and 2) glass systems was performed. The changes observed in the EPR spectra of xV2O5× (100 −x)[2P2O5 · Na2O] glasses with increasing content of vanadium oxide are explained supposing that these spectra consist of two superposed EPR signals, one with hyperfine structure typical for isolated ions and another one consisting of a broad line without hyperfine structure characteristic for clustered ions. The clustered V4+ ions are not evidenced at low V2O5 contents (x = 5 mol%). The EPR spectra of xV2O5 · (100 −x)[P2O5 · mNa2O] glasses indicate a superposition of two or three hyperfine structures attributed to nonequivalent VO2+ centers. Spin Hamiltonian parameters (g, A), dipolar hyperfine coupling parameter (P) and Fermi contact interaction term (K) have been evaluated. The ratio between the number of clustered and isolated ions was also determined. 相似文献
28.
Maria Jesus Alvarez-Cubero Luis Javier Martinez-Gonzalez Maria Saiz Pedro Carmona-Saez Juan Carlos Alvarez Manrique Pascual-Geler Jose Antonio Lorente Jose Manuel Cozar 《Experimental & molecular medicine》2015,47(8):e176
The aim of this study was to analyze the use of 12 single-nucleotide polymorphisms in genes ELAC2, RNASEL and MSR1 as biomarkers for prostate cancer (PCa) detection and progression, as well as perform a genetic classification of high-risk patients. A cohort of 451 men (235 patients and 216 controls) was studied. We calculated means of regression analysis using clinical values (stage, prostate-specific antigen, Gleason score and progression) in patients and controls at the basal stage and after a follow-up of 72 months. Significantly different allele frequencies between patients and controls were observed for rs1904577 and rs918 (MSR1 gene) and for rs17552022 and rs5030739 (ELAC2). We found evidence of increased risk for PCa in rs486907 and rs2127565 in variants AA and CC, respectively. In addition, rs627928 (TT–GT), rs486907 (AG) and rs3747531 (CG–CC) were associated with low tumor aggressiveness. Some had a weak linkage, such as rs1904577 and rs2127565, rs4792311 and rs17552022, and rs1904577 and rs918. Our study provides the proof-of-principle that some of the genetic variants (such as rs486907, rs627928 and rs2127565) in genes RNASEL, MSR1 and ELAC2 can be used as predictors of aggressiveness and progression of PCa. In the future, clinical use of these biomarkers, in combination with current ones, could potentially reduce the rate of unnecessary biopsies and specific treatments. 相似文献
29.
The changes observed in the IR and ESR spectra of the xV2O5(1 ? x)[0.8P2O5 ? 0.2BaO] glass system with 0 ≤ x ≤ 50 mol% show that vanadium oxide acts as a network modifier at low concentration (x ≤ 5 mol%) and as a network former for high content (x ≥ 10 mol%). Thus the IR bands belonging to the phosphate groups are strongly reduced except the specific bands of the short chain phosphate units due to the phosphate network depolymerization and the spectra are dominated by the vibrations characteristic for POP, POV and VOV linkages. At the same time the changes observed in the ESR spectra of these glasses are explained supposing the superposition of two signals, one with a well-resolved hyperfine structure typical for isolated V4+ ions and a broad line characteristic for clustered ions. The line width dependence versus V2O5 content shows that dipole–dipole interactions exist between vanadium ions until x = 5 mol% and the superexchange interactions prevail at high content (x > 10 mol%). 相似文献
30.
O. Cozar L. David V. Chis E. Forisz C. Cosma G. Damian 《Fresenius' Journal of Analytical Chemistry》1996,355(5-6):701-702
CuL2X2 (L = 7-chloro-1,3-dihydro-1-methyl-5-phenyl-3H-1,4-benzodiazepin-2-one, also known as diazepam, X = Cl, Br) complexes have been prepared and investigated by ESR spectroscopy. Powder ESR spectra of these complexes suggest a planar-rhombic distorted local symmetry. The CH3Cl solutions spectra show the presence of pseudo-tetrahedral species with a 3dxy+4pz mixture ground state for the paramagnetic electron. The anisotropic spectra obtained for the Cu(II)-diazepam solution adsorbed on NaY zeolite confirm the existence of a CuN2X2 chromophore. 相似文献