排序方式: 共有106条查询结果,搜索用时 312 毫秒
1.
Yousef Abdossalami Asl Yadollah Yamini Shahram Seidi Behnam Ebrahimpour 《Analytica chimica acta》2015
In the present research, an effective on chip electromembrane extraction (CEME) coupled with high performance liquid chromatography was presented for analysis of nortriptyline (NOR) and amitriptyline (AMI) as basic model analytes from urine samples. The chip consists of two polymethyl methacrylate (PMMA) parts with two craved microfluidic channels in each part. These channels were used as flow path for the sample solution and a thin compartment for the acceptor phase. A porous polypropylene sheet membrane impregnated with an organic solvent was placed between two parts of chip device to separate the channels. Two platinum electrodes were mounted at the bottom of these channels that were connected to a power supply providing the electrical driving force for migration of ionized analytes from sample solution through the porous sheet membrane into the acceptor phase. This new setup provides effective and reproducible extractions with low volume of sample solution. Efficient parameters on CEME of the model analytes were optimized using one variable at a time method. Under the optimized conditions, the calibration curve was linear in the range of 10.0–500 μg L−1 with coefficient of determination (r2) more than 0.9902. The relative standard deviations (RSDs %) for extraction and determination of the analytes were less than 6.8% based on six replicate measurements. LODs less than 4.0 μg L−1 were obtained for both of the model analytes. The preconcentration factors higher than 17.0-fold were obtained. The results demonstrated that CEME would be used efficiently for extraction and determination of AMI and NOR from urine samples. 相似文献
2.
Z. Sanjabi Eznaveh M.H. Zahamtkesh A.R. Kamali Asl S. Bagheri 《Radiation measurements》2010,45(1):89-91
A new class of three-dimensional dosimeter (PRESAGE) has recently emerged, that consists of an optically clear polyurethane matrix containing a leuco dye and a free radical initiator. The dye exhibits a radiochromic response when exposed to ionizing radiation, changing color in proportion to the radiation dose. In this work we investigate and characterize the sensitivity of this new dosimeter by changing the portion of these two materials in the feature. Our results show considerable improvement in both dosimeter sensitivity and dose response stability by changing the percents of leuco dye and free radical initiator to approach to an optimum value. 相似文献
3.
Na[cyclo‐(P5tBu4)] ( 1 ) reacts with [FeBr2(CO)4] (2:1) to give the first homoleptic iron(II) complex [Fe{cyclo‐(P5tBu4)}2] ( 2 ) containing two tridentate cyclo‐(P5tBu4)– ligands. Thermolysis of 2 up to 500 °C produces a new phosphorus‐rich iron phosphide, calculated as FeP6 according to the mass change. 相似文献
4.
Ahmet Colak Ender Cekirge Serdar Karaböcek Aslıgül Küçükdumlu Nagihan Sağlam Ertunga Melek Col Rza Abbasoğlu 《Chemical Papers》2009,63(5):554-561
Nucleolytic activities of some new oxime-type ligand complexes were investigated by neutral agarose gel electrophoresis. Analysis
of the cleavage products in agarose gel indicated that all complexes used converted supercoiled pUC18 plasmid DNA to its nicked
or linear form. It was found that nucleolytic activities of the complexes depend on the complex concentration, reaction time
and the presence of a cooxidant (magnesium monoperoxyphthalate, MMPP) in the reaction mixture. However, the complexes cleaved
pUC18 plasmid DNA at all investigated pH values. Nucleolytic activities of complexes were investigated for different complex
concentrations (0.1–100 μmol L−1), pH values (6.0–10.0) and reaction times (0–60 min). Molecular modeling studies performed by the Hyperchem Software together
with DNA-binding studies showed that planar sites of the complexes intercalated into double stranded DNA. It can be concluded
that all oxime-type ligand complexes used can be evaluated as nuclease mimics. 相似文献
5.
Liquid–liquid equilibrium (LLE) data of the solubility (binodal) curves and tie-line end compositions were examined for mixtures of {(water (1) + levulinic acid (2) + dimethyl succinate or dimethyl glutarate or dimethyl adipate (3)} at 298.15 K and 101.3 ± 0.7 kPa. The reliability of the experimental tie-line data was confirmed by using the Othmer–Tobias correlation. The LLE data of the ternary systems were predicted by UNIFAC method. The LLE data were correlated fairly well with UNIQUAC and NRTL models, indicating the reliability of the UNIQUAC and NRTL equations for these ternary systems. The best results were achieved with the NRTL equation, using non-randomness parameter (α = 0.3) for the correlation. Distribution coefficients and separation factors were measured to evaluate the extracting capability of the solvents. 相似文献
6.
Poly(dodecylmethacrylate-co-methyleugenol) P(DDMA-co-Meu) and poly(dodecylmethacrylate-co-methylchavicol) P(DDMA-co-Mch) gels were synthesized in ethanol using free radical cross-linking polymerization method at 60 °C for 24 h in the presence of azobisisobutyronitrile (AIBN) and triethylene glycol dimethacrylate (TEGDMA) as initiator and cross-linker, respectively. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the gels. These gels were used to investigate swelling behaviors in linalool and methyl eugenol, in essential oil mixture of phenyl propanoid and terpenoid, and also in various solvents. While the equilibrium swelling values (ESV) of both gels were higher in linalool than in methyl eugenol, the result was vice versa in the case of essential oil mixture. ESVs of both gels were also obtained in various solvents with different functional groups and the highest ESV of both gels were obtained in toluene, and the lowest ESV of P(DDMA-co-Meu) and P(DDMA-co-Mch) was in methanol and in ethylene glycol, respectively. While P(DDMA-co-Meu) is sensitive to carbon number change in alcohol, P(DDMA-co-Mch) is less sensitive. In the case of esters, increase of carbon number in functional group causes a more significant change in ESV than an increase of carbon number in aliphatic chain. Experimental results were correlated by the first-order and second-order models. The second-order model was more suitable than the other. While P(DDMA-co-Meu) gel swelled in linalool exhibits a Fickian diffusion character, the diffusion mechanism of the gel in methyl eugenol is a non-Fickian one. In the case of P(DDMA-co-Mch), the result is vice versa. 相似文献
7.
Ali Hossein Kianfar Sanam Asl Khademi Roghaye Hashemi Fath Mahmoud Roushani Mojtaba Shamsipur 《Journal of the Iranian Chemical Society》2013,10(2):347-355
The VO(IV) complexes of tridentate ONN Schiff ligands were synthesized and characterized by IR, UV–Vis and elemental analysis. The electrochemical properties of the vanadyl complexes were investigated by cyclic voltammetry. A good correlation was observed between the oxidation potentials and the electron-withdrawing character of the substituents on the Schiff base ligands, showing the following trend: MeO < H < Br < NO2. The thermogravimetry (TG) and differential thermoanalysis (DTA) of the VO(IV) complexes were carried out in the range of 20–700 °C. The VOL1(OH2) and VOL2(OH2) decomposed in three steps, whereas the VOL3(OH2) and VOL4(OH2) complexes decomposed in two steps. The thermal decomposition of these complexes is closely related to the nature of the Schiff base ligands and proceeds via first-order kinetics. The structures of compounds were determined by ab initio calculations. The optimized molecular geometry and atomic charges were calculated using MP2 method with 6-31G(d) basis. The results suggested that, in the complexes, V(IV) ion is in square-pyramid N2O3 coordination geometry. Also the bond lengths and angles were studied and compared. 相似文献
8.
We analyze the problem of pricing and hedging contingent claims in the multi-period, discrete time, discrete state case using the concept of a “λ gain–loss ratio opportunity”. Pricing results somewhat different from, but reminiscent of, the arbitrage pricing theorems of mathematical finance are obtained. Our analysis provides tighter price bounds on the contingent claim in an incomplete market, which may converge to a unique price for a specific value of a gain–loss preference parameter imposed by the market while the hedging policies may be different for different sides of the same trade. The results are obtained in the simpler framework of stochastic linear programming in a multi-period setting, and have the appealing feature of being very simple to derive and to articulate even for the non-specialist. They also extend to markets with transaction costs. 相似文献
9.
Application of Monte Carlo simulation method to polymerization kinetics over Ziegler–Natta catalysts
In the current work, the Monte Carlo simulation method was applied to ethylene polymerization over Ziegler–Natta catalysts. As expected, polymerization over each center of a Ziegler–Natta catalyst leads to a polymer having a Schultz–Flory molecular weight distribution. Notwithstanding, the total molecular weight distribution obtained by all catalyst centers together is at least twice as broad as that of each center. As another interesting finding, the introduction of hydrogen to the reaction deactivates the catalyst active centers and thereby reduces the catalyst activity. Nevertheless, it does not mainly affect the polymerization kinetics. In addition, the polymer molecular weight falls as hydrogen is added to the reaction since it acts as a strong transfer agent. The same effect is seen when cocatalyst concentration increases. Hydrogen also widens the polymer molecular weight distribution. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 45–56, 2009 相似文献
10.
Realization of a Framework for Simulation-Based Large-Scale Shape Optimization Using Vertex Morphing
Ghantasala Aditya Najian Asl Reza Geiser Armin Brodie Andrew Papoutsis Efthymios Bletzinger Kai-Uwe 《Journal of Optimization Theory and Applications》2021,189(1):164-189
Journal of Optimization Theory and Applications - There is a significant tendency in the industry for automation of the engineering design process. This requires the capability of analyzing an... 相似文献