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121.
Isam M. Salih Amina S. Aljaber Mohamed A-Z Eltayeb Yousif Sulfab 《Transition Metal Chemistry》2013,38(2):213-218
The kinetics of oxidation of N,N′-ethylenebis(isonitrosoacetyleacetoneimine)copper(II) complex, CuIIL, by N-bromosuccinimide (SBr) in weakly aqueous acidic solutions was studied under pseudo-first-order conditions. Plots of ln(A ∞ ? A t ) versus time where A t and A ∞ are absorbance values of the Cu(III) product at time t and infinity, respectively, showed marked deviations from linearity. The curves showed an acceleration of reaction rate consistent with an autocatalytic behavior. In the presence of Hg(II) ions, plots of ln(A ∞ ? A t ) versus time are linear up to >85 % of reaction. The value of the observed rate constant, k obs, increases with decreasing pH. At constant reaction conditions, the dependence of the observed rate constants, k obs, is described by Eq. (1). 1 $$ k_{\text{obs}} = k_{\text{o}} + k_{1} \left[ {{\text{H}}^{ + } } \right] $$ The dependence of both k o and k 1 on [SBr] is not linear. The mechanism of the title reaction is consistent with an inner sphere mechanism in which a pre-equilibrium step precedes the electron transfer step. The overall rate law is represented by Eq. (2) where [CuIIL]t and K 1 represent the total copper(II) complex concentration and the pre-equilibrium formation constant, respectively. 2 $$ d\left[ {{\text{Cu}}^{\text{III}} {\text{L}}^{ + } } \right]/dt = \left\{ {\left( {k_{\text{o}} + k_{1} \left[ {{\text{H}}^{ + } } \right]} \right)\left[ {\text{SBr}} \right]\left[ {{\text{Cu}}^{\text{II}} {\text{L}}} \right]_{t} } \right\}/\left( {1 + K_{1} \left[ {\text{SBr}} \right]} \right) $$ . 相似文献
122.
123.
Orhan ?çelli Salih Erzeneo?lu Güven Çankaya 《Journal of Quantitative Spectroscopy & Radiative Transfer》2005,91(4):485-491
Effective atomic numbers for CuCoNi alloys against changing Ni contents were measured in the X-ray energy range from 15.746 to 40.930 keV. The gamma rays emitted a 241Am point source have been send on absorbers to be used transmission arrangement. The X-rays were counted by a Si(Li) detector with a resolution of 160 eV at 5.9 keV. The compositions of the Ni films were determined to be 0.03, 0.47, 0.62, 1.23, 1.22 and 1.6 by a scanning electron microscopy in CuCoNi alloys prepared against changing Ni contents. CoCuNi alloy films were prepared with an electrodeposition technique. Also, the total effective atomic numbers of each alloy were estimated using mixture rule. The measured values were compared with estimated values for alloys. 相似文献
124.
A novel type of ionophore ligands, 3′-(2,3-dihydroxypropylthio)-phthalonitrile and 4′(2,3-dihydroxypropylthio)-phthalonitrile, and their α- and β-tetrasubstituted metallo phthalocyanines, (MPc), (M = ZnII, CoII, MnIIICl, FeIIIAc, CuII) have been prepared and fully characterized by elemental analysis, FT-IR, 1H and 13C NMR, and MS (ESI and Maldi-TOF). The complexes are soluble in both polar and non-polar solvents, such as MeOH and EtOH, THF, CHCl3 and CH2Cl2. The spectroscopic properties of the complexes are affected strongly by the electron-donating sulfanyl units on the periphery of the phthalocyanines. The cation binding properties of the complexes, for example using AgI and PdII, were evaluated by UV-Vis spectroscopy and the results show the formation of polynuclear phthalocyanine complexes. Functional donors on the periphery of the zinc and copper complexes coordinate to AgI and PdII to give ca. a 2:1 metal-phthalocyanine complex binding ratio for the concentration of 2.5 × 10−5 M (Pc) and 1.0 × 10−3 M (Metal ions). Voltammetric and in-situ spectroelectrochemical studies were performed to characterize the redox behavior of the complexes. An in-situ electrocolorimetric method was applied to investigate the colors of the electro-generated anionic and cationic forms of the complexes. 相似文献
125.
Zinc oxide (ZnO) based fibers with a diameter of 80-100 nm were prepared by electrospinning. Polyvinyl alcohol (PVA) and zinc acetate dihydrate were dissolved in water and the polymer/salt solution was electrospun at 2.5 kV cm−1. The resulting electrospun fibers were subjected to calcination at 500 °C for 2 h to obtain ZnO-based fibers. Humidity sensing properties of the fiber mats were investigated by quartz crystal microbalance (QCM) method and electrical measurements. The adsorption kinetics under constant relative humidity (RH) between 10% and 90% were explained using Langmuir adsorption model. Results of the measurements showed that ZnO-based fibers were found to be promising candidate for humidity sensing applications at room temperature. 相似文献
126.
127.
Taher Sharshar H. Ebrahim Hassan Hassan A. Arida Abdulkadir Aydarous Salih A. Bazaid Mamdouh A. Ahmed 《Isotopes in environmental and health studies》2013,49(1):132-151
The levels of radioactivity and heavy metals in soil, plant and groundwater samples collected from the area of the new campus of Taif University, Saudi Arabia, and its neighbouring areas have been determined. High-resolution gamma-ray spectroscopy was used for radioactivity measurements, and inductively coupled plasma atomic emission spectroscopy was used to determine the concentration of heavy metals. The means of 226Ra, 228Ra and 40K concentrations in water samples collected from four wells were found to be 0.13±0.03, 0.05±0.03 and 1.3±0.5 Bq l?1, respectively. The means of 238U, 226Ra, 228Ra (232Th for soil samples) and 40K concentrations in wild plant and soil samples were found to be 3.7±4.1, 8.8±11.6, 3.8±2.9 and 1025±685, and 8.6±3.4, 12.8±3.4, 16.6±7.1 and 618±82 Bq kg?1 dry weight (DW), respectively. The 137Cs of artificial origin was also detected in soil samples with a mean concentration of 3.8±2.2 Bq kg?1 DW. Evaluating the results, it can be concluded that the concentrations of 238U, 226Ra, 232Th and 40K in soil samples fall within the world average. Furthermore, 19 trace and major elements in groundwater samples and 22 elements in soil and plant samples were determined. The sampling locations of soil can be classified into three groups (relatively high, medium and low polluted) according to their calculated metal pollution index using the contents of trace and major elements. A cluster analysis of the contents of radioactivity and trace element contents in soil samples shows the presence of two main distinct clusters of sampling locations. 相似文献
128.
Hajo Idriss Isam Salih A. K. Sam 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(2):333-338
This study was conducted primarily to measure and map radon activity concentration in wells within water supply network of
Khartoum State. Ground water samples were collected before and after autumn and analysed using low level γ-spectrometry equipped
with HPGe-detector. Radon activity concentration was found in the range of 1.58–345.10 Bq/L with an average value of 59.20 ± 6.60 Bq/L.
Upon comparing the radon concentration values obtained with EPA it was found they were far below the maximum contaminant level
of EPA with the exception five samples. Physicochemical water parameters were measured and no correlation was noted between
radon concentration and these parameters. The overall annual effective dose for adults due to radon ingestion is less than
WHO recommended reference dose level for most except 14 samples. 相似文献
129.
Najeba F. Salih 《Isotopes in environmental and health studies》2019,55(1):80-91
This study entails the measurement of the specific activity of natural radionuclides (226Ra, 40K and 232Th) in 18 tooth samples obtained from the clinic of the Universiti Sains Malaysia (USM), Penang, by using an HPGe detector. The specific activity of 226Ra, 40K and 232Th was measured to estimate the hazard index of the radionuclides, radium equivalent activities (Raeq), external, internal hazard indices (Hex, Hin), and absorbed dose (Dout, Din). The maximum values of concentration of 226Ra, 232Th and 40K in the tooth samples were found to be 60.82, 60.29 and 594.22?Bq kg?1, respectively. Maximum values of Raeq, Hex, Hin, Dout and Din were found to be 192.78?Bq kg?1, 0.520, 0.685, 89.29 and 169.81?nGy h–1, Iγ and Iα as 0.702 and 0.304, respectively. The results were lower than the average world value (UNSCEAR). In addition, a strong correlation was found between the concentrations of 226Ra and Raeq, between energy and net area, as well as between radionuclides (226Ra, 40K and 232Th) in tooth samples and age of volunteers. This study showed that the concentrations and hazard indices of tooth samples are below the recommended safe levels; therefore, the study area is considered safe in terms of radiological health hazards. 相似文献
130.
Orhan ?çelli Salih Erzeneo?lu 《Journal of Quantitative Spectroscopy & Radiative Transfer》2004,88(4):519-524
The mass attenuation coefficients for V2O3, VO2, VF3, NH4VO3, VF4, NiF2, NiCl2, NiCl2H2O, NiF24H2O, NiCl26H2O, Ni(ClO4)26H2O were measured in the X-ray energy range from 15.746 to using a Si(Li) detector. The measured values are compared with the theoretical ones calculated using WinXcom. 相似文献