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57Fe electric and magnetic hyperfine parameters were calculated for a series of 10 iron model complexes, covering a wide range of oxidation and spin states. Employing the B3LYP hybrid method, results from nonrelativistic density functional theory (DFT) and quasi-relativistic DFT within the zero-order regular approximation (ZORA) were compared. Electron densities at the iron nuclei were calculated and correlated with experimental isomer shifts. It was shown that the fit parameters do not depend on a specific training set of iron complexes and are, therefore, more universal than might be expected. The nonrelativistic and quasi-relativistic electron densities gave fit parameters of similar quality; the ZORA densities are only shifted by a factor of 1.32, upward in the direction of the four-component Dirac-Fock value. From a correlation of calculated electric field gradients and experimental quadrupole splittings, the value of the 57Fe nuclear quadrupole moment was redetermined to a value of 0.16 barn, in good agreement with other studies. The ZORA approach gave no additional improvement of the calculated quadrupole splittings in comparison to the nonrelativistic approach. The comparison of the calculated and measured 57Fe isotropic hyperfine coupling constants (hfcc's) revealed that both the ZORA approach and the inclusion of spin-orbit contributions lead to better agreement between theory and experiment in comparison to the nonrelativistic results. For all iron complexes with small spin-orbit contributions (high-spin ferric and ferryl systems), a distinct underestimation of the isotropic hfcc's was found. Scaling factors of 1.81 (nonrelativistic DFT) and 1.69 (ZORA) are suggested. The calculated 57Fe isotropic hfcc's of the remaining model systems (low-spin ferric and high-spin ferrous systems) contain 10-50% second-order contributions and were found to be in reasonable agreement with the experimental results. This is assumed to be the consequence of error cancellation because g-tensor calculations for these systems are of poor quality with the existing DFT approaches. Excellent agreement between theory and experiment was found for the 57Fe anisotropic hfcc's. Finally, all of the obtained fit parameters were used for an application study of the [Fe(H2O)6]3+ ion. The calculated spectroscopic data are in good agreement with the Mossbauer and electron paramagnetic resonance results discussed in detail in a forthcoming paper. 相似文献
3.
Performances of a pilot-scale reed bed for the olive mill wastewater (OMW) treatment were investigated, by monitoring influent and effluent pH, total suspended solids (TSS), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), total phosphorus and polyphenols. In order to reduce the suspended matter concentration and to avoid clogging, OMW was pre-treated by adding lime putty, calcium hydroxide and hydraulic lime. The best results were obtained with 2 g/L of hydraulic lime. Pre-treated OMW was dosed in the reed bed at dilution ratios of 1/3 and 1/10 (v/v), pointing up that the latter only did not give rise to reed suffering and allowed to obtain good and durable removal efficiencies, above all for COD (74.1+/-17.6%) and polyphenols (83.4+/-17.8%). Recycling of the effluent was quite effective for the improvement of the wastewater quality, allowing a further removal of 26-70%, depending on the parameter taken into account. A post-dosage study, carried out by feeding the reed bed with the effluent of an activated sludge plant, pointed up a rapid decreasing of the outlet concentrations of the investigated parameters to values compatible with Italian regulations concerning wastewater discharge in surface water. Polyphenols were the exception, being their outlet concentration at the end of post-dosage study around 2 mg/L. 相似文献
4.
A new apparatus for the extraction of organic compounds from sea water is described. With this apparatus it is possible to extract 54 standard compounds with high recovery percentages from 9 1 of sea water with 3 ml ofn-hexane. The analysis time (about 1 h) is appreciably lower than those of the extraction methods based on RP-18 and Carbopack-B adsorption (about 15 h). Furthermore, it is possible to analyze samples without filtration. An application of this method to the analysis of Tirreno sea water is reported. 相似文献
5.
Feng K De Boni L Misoguti L Mendonca CR Meador M Hsu FL Bu XR 《Chemical communications (Cambridge, England)》2004,(10):1178-1180
Two new classes of two-photon absorbing Y-shaped molecules have been developed to possess an imidazole-thiazole core and a stilbene-type conjugation pathway with either nitro or sulfonyl as terminal electron-accepting group. 相似文献
6.
Dominique Lorcy Leonardo Mattiello Cyril Poriel Joëlle Rault-Berthelot 《Journal of Electroanalytical Chemistry》2002,530(1-2)
New three-dimensional copolymers containing 9,9′-spirobifluorenyl-ethylene units were prepared by anodic oxidation of 9,9′-spirobifluorenes 2-mono- or 2,7′-disubstituted by a dithiafulvenyl unit. The synthesis, physicochemical properties and electrochemistry of both monomers and derived oligomers and polymers are reported. 相似文献
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Yulu Yang Mingguang Wu Xingwang Zhu Hui Xu Si Ma Yongfeng Zhi Hong Xia Xiaoming Liu Jun Pan Jie-Yinn Tang Siang-Piao Chai Leonardo Palmisano Francesco Parrino Junli Liu Jianzhong Ma Ze-Lin Wang Ling Tan Yu-Fei Zhao Yu-Fei Song Pardeep Singh Pankaj Raizada Deli Jiang Di Li R. A. Geioushy Jizhen Ma Jintao Zhang Song Hu Rongjuan Feng Gang Liu Minghua Liu Zhenhua Li Mingfei Shao Neng Li Jiahe Peng Wee-Jun Ong Nikolay Kornienko Zhenyu Xing Xiujun Fan Jianmin Ma 《中国化学快报》1990,30(12):2065-2088
This roadmap demonstrates a series of two-dimensional nanomaterials, such as graphene, black phosphorus, oxides, layered double hydroxides, chalcogenides, bismuth-based layered compounds, MXenes, metal organic frameworks, covalent organic frameworks, and others, for environmental catalysis. 相似文献
9.
Leonardo Colzani 《Annali di Matematica Pura ed Applicata》1984,137(1):207-215
Summary We prove direct and converse theorems of approximation for distributions in the Hardy spaces Hp, 0
相似文献
10.
Mrcia Sousa Bispo Maria das Graas Andrade Korn Elane Santos da Boa Morte Leonardo Sena Gomes Teixeira 《Spectrochimica Acta Part B: Atomic Spectroscopy》2002,57(12):2175-2180
An analytical method for separation and pre-concentration of lead in seawater for determination by inductively coupled plasma optical emission spectrometry has been investigated. Lead was retained in the solid phase (0.5 g) composed of co-precipitated naphthalene and alizarin red. The solid phase quantitatively sorbs Pb(II) at pH 8–9, and the metal was eluted using 5.0 ml of 2 mol l−1 nitric acid. The effect of NaCl, KCl, BaCl2, CaCl2, Na2SO4, MgCl2 and Na3PO4 on the sorption of Pb(II) in the solid phase was studied. A set of solutions containing varying amounts of electrolytes (0.5; 1.0; 3.0 and 5.0% m/v) with Pb (50 μg) was prepared and the recommended procedure applied. The Na3PO4 was found to interfere; the other electrolytes did not interfere up to 5% m/v. A pre-concentration factor of 40 was obtained in this analytical procedure. The limit of detection and limit of quantification for Pb(II) were 53 and 176 μg l−1, respectively. Lead was determined in seawater samples collected in Salvador city, Bahia, Brazil. The precision, expressed as R.S.D., was 1.8–4.6%, and the recovery of lead added to seawater samples was 95–97%. 相似文献