963 resultados para COPPER(I) IODIDE
Resumo:
Boron is an element whose metallurgical possibilities have never been fully investigated. The principal reason for this fact seems to lie in the difficulties encountered in preparing elemental boron and its various intermetallic compounds.
Resumo:
Quantitative meta-analyses of randomized clinical trials investigating the specific therapeutic efficacy of homeopathic remedies yielded statistically significant differences compared to placebo. Since the remedies used contained mostly only very low concentrations of pharmacologically active compounds, these effects cannot be accounted for within the framework of current pharmacology. Theories to explain clinical effects of homeopathic remedies are partially based upon changes in diluent structure. To investigate the latter, we measured for the first time high-field (600/500 MHz) 1H T1 and T2 nuclear magnetic resonance relaxation times of H2O in homeopathic preparations with concurrent contamination control by inductively coupled plasma mass spectrometry (ICP-MS). Homeopathic preparations of quartz (10c–30c, n = 21, corresponding to iterative dilutions of 100−10–100−30), sulfur (13x–30x, n = 18, 10−13–10−30), and copper sulfate (11c–30c, n = 20, 100−11–100−30) were compared to n = 10 independent controls each (analogously agitated dilution medium) in randomized and blinded experiments. In none of the samples, the concentration of any element analyzed by ICP-MS exceeded 10 ppb. In the first measurement series (600 MHz), there was a significant increase in T1 for all samples as a function of time, and there were no significant differences between homeopathic potencies and controls. In the second measurement series (500 MHz) 1 year after preparation, we observed statistically significant increased T1 relaxation times for homeopathic sulfur preparations compared to controls. Fifteen out of 18 correlations between sample triplicates were higher for controls than for homeopathic preparations. No conclusive explanation for these phenomena can be given at present. Possible hypotheses involve differential leaching from the measurement vessel walls or a change in water molecule dynamics, i.e., in rotational correlation time and/or diffusion. Homeopathic preparations thus may exhibit specific physicochemical properties that need to be determined in detail in future investigations.
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There is an increasing demand for novel metal-based complexes with biologically relevant molecules in technology and medicine. Three new Cu(II) coordination compounds with antifungal agent isoconazole (L), namely mononuclear complexes CuCl2(L)(2) (1), and Cu(O2CMe)(2)(L)(2)center dot 2H(2)O (2) and coordination polymer Cu(pht)(L)(2)(n) (3) (where H(2)pht - o-phthalic acid) were synthesized and characterized by IR spectroscopy, thermogravimetric analysis and X-ray crystallography. X-ray analysis showed that in all complexes, the isoconazole is coordinated to Cu(II) centres by a N atom of the imidazole fragment. In complex I, the square-planar environment of Cu(II) atoms is completed by two N atoms of isoconazole and two chloride ligands, whereas the Cu(II) atoms are coordinated by two N atoms from two isoconazole ligands and two O atoms from the different carboxylate residues: acetate in 2 and phthalate in 3. The formation of an infinite chain through the bridging phthalate ligand is observed in 3. The biosynthetic ability of micromycetes Aspergillus niger CNMN FD 10 in the presence of the prepared complexes 1-3 as well as the antifungal drug isoconazole were studied. Complexes 2 and 3 accelerate the biosynthesis of enzymes (beta-glucosidase, xylanase and endoglucanase) by this fungus. Moreover, a simplified and improved method for the preparation of isoconazole nitrate was developed.
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We report a trace element - Pb isotope analytical (LIA) database on the "Singen Copper", a peculiar type of copper found in the North Alpine realm, from its type locality, the Early Bronze Age Singen Cemetery (Germany). What distinguishes “Singen Copper” from other coeval copper types? (i) is it a discrete metal lot with a uniform provenance (if so, can its provenance be constrained)? (ii) was it manufactured by a special, unique metallurgical process that can be discriminated from others? Trace element concentrations can give clues on the ore types that were mined, but they can be modified (more or less intentionally) by metallurgical operations. A more robust indicator are the ratios of chemically similar elements (e.g. Co/Ni, Bi/Sb, etc.), since they should remain nearly constant during metallurgical operations, and are expected to behave homogeneously in each mineral of a given mining area, but their partition amongst the different mineral species is known to cause strong inter-element fractionations. We tested the trace element ratio pattern predicted by geochemical arguments on the Brixlegg mining area. Brixlegg itself is not compatible with the Singen Copper objects, and we only report it because it is a rare instance of a mining area for which sufficient trace element analyses are available in the literature. We observe that As/Sb in fahlerz varies by a factor 1.8 above/below median; As/Sb in enargite varies by a factor of 2.5 with a 10 times higher median. Most of the 102 analyzed metal objects from Singen are Sb-Ni-rich, corresponding to “antimony-nickel copper” of the literature. Other trace element concentrations vary by > 100 times, ratios by factors > 50. Pb isotopic compositions are all significantly different from each other. They do not form a single linear array and require > 3 ore batches that certainly do not derive from one single mining area. Our data suggest a heterogeneous provenance of “Singen copper”. Archaeological information limits the scope to Central European sources. LIA requires a diverse supply network from many mining localities, including possibly Brittany. Trace element ratios show more heterogeneity than LIA; this can be explained either by deliberate selection of one particular ore mineral (from very many sources) or by processing of assorted ore minerals from a smaller number of sources, with the unintentional effect that the quality of the copper would not be constant, as the metallurgical properties of alloys would vary with trace element concentrations.
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The gastrin-releasing peptide receptor (GRPr) is an important molecular target for the visualization and therapy of tumors and can be targeted with radiolabeled bombesin derivatives. The present study aims to develop statine-based bombesin receptor antagonists suitable for labeling with 64Cu for imaging by positron emission tomography (PET). The potent GRPr antagonist D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 was conjugated to the sarcophagine (3,6,10,13,16,19-hexaazabicyclo[6.6.6] icosane=Sar) derivative 5-(8-methyl-3,6,10,13,16,19-hexaaza-bicyclo[6.6.6]icosan-1-ylamino)-5-oxopentanoic acid (MeCOSar) via PEG4 (LE1) and PEG2 (LE2) spacers and radiolabeled with 64Cu2+ with >95% yield and specific activities of about 100 MBq/nmol. Both Cu(II) conjugates have high affinity for GRPr (IC50: natCu-LE1, 1.4±0.1 nM; natCu-LE2, 3.8±0.6 nM). The antagonistic properties of both conjugates were confirmed by Ca2+-flux measurements. Biodistribution studies of Cu-64-LE1 exhibited specific targeting of the tumor (19.6±4.7% IA/g at 1 h p.i.) and GRPr-positive organs. Biodistribution and PET images at 4 and 24 h postinjection showed increasing tumor-to-background ratios with time. This was illustrated by the acquisition of PET images showing high tumor-to-normal tissue contrast. This study demonstrates the high affinity of the MeCOSar-PEGx-bombesin conjugates to GRPr. The stability of 64Cu complexes of MeCOSar, the long half-life of 64Cu, and the suitable biodistribution profile of the 64Cu-labeled peptides lead to PET images of high contrast suitable for potential translation into the clinic.
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A community bioassay of copper was performed using benthic macroinvertebrates colonized on multiplate substrate samplers. Five copper concentrations ranging from 0.080-2.20 mg/l total copper were administered to five artificial streams by a Mount and Brungs proportional dilutor. Free copper ion as Cu('++) ranged from .002-.053 mg/l. A sixth stream received no copper and served as a control. Substrates were sampled at days 0, 14, and 28, and the results were used to compare 13 indices used or proposed to assess aquatic environmental impact. Sensitivity of the indices to changes in communities with respect to concentration and time was the basis for the comparison.^ Results indicated that all of the 8 diversity or richness indices tested gave approximately the same result (with the exception of number of species); they increased over the first 2-3 concentrations, then declined. Included among these was the Shannon index which gave false positive results, i.e., it increased, indicating enrichment, when in fact perturbation had occurred. This result was due to the disproportionate effect on the most abundant taxa, which caused a more even distribution of individuals among species. Number of species and individuals declined with increased concentration and time, with only one exception in the case of species, indicating perturbation.^ Results of five community comparison indices were varied at day 14 but by day 28 the results indicated a clear, nearly monotonic, trend due to copper impact. It was assumed that day 28 observations, though probably still changing, were nearer stability than at day 14 and therefore more representative of natural conditions. The changes in community comparison indices showed good agreement at 28 days and reflected the general decline in species and individuals. No single community comparison index could be set apart as superior to the others. ^
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Two types of deep-sea dredges are currently under development for the mining of the manganese nodules, a deep-sea hydraulic dredge and a mechanical cable-bucket system. Both systems offer some advantages with the hydraulic system appearing to be advantageous in themining of a specific deposit for which it is designed while the cable-bucket system appears to be somewhat more flexible in working in a variety of deposits, topographic environments, and water depths. Environmental studies conducted in conjunction with deep-sea tests of the two types of mining systems currently indicate that substantially no environmental damage will be done in the mining of the deep-sea nodules. Because of the nature of the deposits and the way in which they can be mined, the manganese nodules appear to be a relatively pollution free and energy-saving source of a number of industrially important metals.
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The biogeochemistry of iodine in the waters of the Atlantic sector of the Southern Ocean was investigated during the Polarstern cruise ANTXXIV-3 ZERO&DRAKE. The speciation and distribution of iodine (iodate and iodide) in seawater was examined across gradients of iron concentrations and phytoplankton abundance, ranging from an open ocean region along the Zero Meridian to the Weddell Sea and Drake Passage. Iodine cycling in high latitudes differs from that in low latitudes due to differences in the plankton community composition and the physicochemical characteristics. Iodate concentrations ranged between 400 and 450 nmol/L from the surface to the bottom. Surface concentrations of iodide (17 to over 60 nmol/L) were about an order of magnitude higher than below the pycnocline. The peak values of iodide lay nearly always within the euphotic zone and showed a weak, positive correlation with nitrite concentrations in the upper 200 m. In all vertical profiles a pronounced sub-surface maximum in iodide appears between 50 and 200 m depth indicating an iodide drawdown at the near surface. Iodide distribution in the Weddell Sea showed elevated levels in Weddell Sea Bottom Water (WSBW) indicating slow oxidation kinetics and the potential for iodide as a tracer of WSBW formation.
Resumo:
Copper nitride is a metastable material which results very attractive because of their potential to be used in functional device. Cu3 N easily decomposes into Cu and N2 by annealing [1] or irradiation (electron, ions, laser) [2, 3]. Previous studies carried out in N-rich Cu3 N films irradiated with Cu at 42MeV evidence a very efficient sputtering of N whose yield (5×10 3 atom/ion), for a film with a thickness of just 100 nm, suggest that the origin of the sputtering has an electronic nature. This N depletion was observed to be responsible for new phase formation ( Cu2 O) and pure Cu [4]
Resumo:
Nitrogen sputtering yields as high as 104 atoms/ion, are obtained by irradiating N-rich-Cu3N films (N concentration: 33 ± 2 at.%) with Cu ions at energies in the range 10?42 MeV. The kinetics of N sputtering as a function of ion fluence is determined at several energies (stopping powers) for films deposited on both, glass and silicon substrates. The kinetic curves show that the amount of nitrogen release strongly increases with rising irradiation fluence up to reaching a saturation level at a low remaining nitrogen fraction (5?10%), in which no further nitrogen reduction is observed. The sputtering rate for nitrogen depletion is found to be independent of the substrate and to linearly increase with electronic stopping power (Se). A stopping power (Sth) threshold of ?3.5 keV/nm for nitrogen depletion has been estimated from extrapolation of the data. Experimental kinetic data have been analyzed within a bulk molecular recombination model. The microscopic mechanisms of the nitrogen depletion process are discussed in terms of a non-radiative exciton decay model. In particular, the estimated threshold is related to a minimum exciton density which is required to achieve efficient sputtering rates.
Resumo:
A one-step extraction procedure and a leaching column experiment were performed to assess the effects of citric and tartaric acids on Cu and Zn mobilization in naturally contaminated mine soils to facilitate assisted phytoextraction. A speciation modeling of the soil solution and the metal fractionation of soils were performed to elucidate the chemical processes that affected metal desorption by organic acids. Different extracting solutions were prepared, all of which contained 0.01 M KNO3 and different concentrations of organic acids: control without organic acids, 0.5 mM citric, 0.5 mM tartaric, 10 mM citric, 10 mM tartaric, and 5 mM citric +5 mM tartaric. The results of the extraction procedure showed that higher concentrations of organic acids increased metal desorption, and citric acid was more effective at facilitating metal desorption than tartaric acid. Metal desorption was mainly influenced by the decreasing pH and the dissolution of Fe and Mn oxides, not by the formation of soluble metal–organic complexes as was predicted by the speciation modeling. The results of the column study reported that low concentrations of organic acids did not significantly increase metal mobilization and that higher doses were also not able to mobilize Zn. However, 5–10 mM citric acid significantly promoted Cu mobilization (from 1 mg kg−1 in the control to 42 mg kg−1 with 10 mM citric acid) and reduced the exchangeable (from 21 to 3 mg kg−1) and the Fe and Mn oxides (from 443 to 277 mg kg−1) fractions. Citric acid could efficiently facilitate assisted phytoextraction techniques.
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The electronic structure of modified chalcopyrite CuInS2 has been analyzed from first principles within the density functional theory. The host chalcopyrite has been modified by introducing atomic impurities M at substitutional sites in the lattice host with M = C, Si, Ge, Sn, Ti, V, Cr, Fe, Co, Ni, Rh, and Ir. Both substitutions M for In and M for Cu have been analyzed. The gap and ionization energies are obtained as a function of the M-S displacements. It is interesting for both spintronic and optoelectronic applications because it can provide significant information with respect to the pressure effect and the nonradiative recombination.