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91.
Muhammad Danish M. Nawaz Tahir Sabiha Ghafoor Nazir Ahmad Saqib Ali Edward R. T. Tiekink 《Journal of chemical crystallography》2011,41(9):1365-1369
Abstract
The structure of n-Bu2Sn(2-methyl-3,5-dinitrobenzoato)2 (1) presents a rare structural motif for compounds with the general formula R 2Sn(O2CR′)2 which almost exclusively adopt skew-trapezoidal bipyramidal geometries. By contrast, the structure of (1) is polymeric with the polymer backbone comprising eight-membered {SnOCO}2 rings linked at the pivotal tin atoms. The coordination geometry is octahedral trans-C2O4. The relationship between structural motifs for R 2Sn(O2CR′)2 is discussed. Compound (1) crystallizes in the monoclinic space group P21/c with a = 5.0114(2) ?, b = 13.7120(5) ?, c = 19.5956(7) ?, β = 91.385(2)o, and Z = 2. 相似文献92.
Nazir U. Saleem S. Nawaz M. Alderremy A. A. 《Journal of Thermal Analysis and Calorimetry》2020,140(5):2519-2528
Journal of Thermal Analysis and Calorimetry - Finite element simulations for the dynamics of Casson fluid flow over time-dependent two-dimensional stretching sheet subjected to magnetic field and... 相似文献
93.
Structural Chemistry - At the end of December 2019, a novel strain of coronavirus, given the name of 2019-nCoV, emerged for exhibiting symptoms of severe acute respiratory syndrome. The virus is... 相似文献
94.
95.
Khan A Khan MI Iqbal Z Shah Y Ahmad L Nazir S Watson DG Khan JA Nasir F Khan A Ismail 《Talanta》2011,84(3):789-801
A new, simple, economical and validated high-performance liquid chromatography linked with electrochemical detector (HPLC-ECD) method has been developed and optimized for different experimental parameters to analyze the most common monothiols and disulfide (cystine, cysteine, homocysteine, methionine, reduced (GSH) and oxidized glutathione (GSSG)) and ascorbic acid present in human plasma and erythrocytes using dopamine as internal standard (IS). Complete separation of all the targets analytes and IS at 35 °C on Discovery HS C18 RP column (250 mm × 4.6 mm, 5 μm) was achieved using 0.05% TFA:methanol (97:3, v/v) as a mobile phase pumped at the rate of 0.6 ml min−1 using electrochemical detector in DC mode at the detector potential of 900 mV. The limits of detection (3 S/N) and limits of quantification (10 S/N) of the studied compounds were evaluated using dilution method. The proposed method was validated according to standard guidelines and optimization of various experimental parameters and chromatographic conditions was carried out. The optimized and validated HPLC-ECD method was successfully applied for the determination of the abovementioned compounds in human plasma and erythrocytes. The method will be quite suitable for the determination of plasma and erythrocyte profile of ascorbic acid and aminothiols in oxidative stress and other basic research studies. 相似文献
96.
We investigate the energy transfer dynamics in a donor-acceptor model by developing a time-local master equation technique based on a variational transformation of the underlying Hamiltonian. The variational transformation allows a minimisation of the Hamiltonian perturbation term dependent on the system parameters, and consequently results in a versatile master equation valid over a range of system-bath coupling strengths, temperatures, and environmental spectral densities. While our formalism reduces to the well-known Redfield, F?rster and polaron forms in the appropriate limits, in general it is not equivalent to perturbing in either the system-environment or donor-acceptor coupling strengths, and hence can provide reliable results between these limits as well. Moreover, we show how to include the effects of both environmental correlations and non-equilibrium preparations within the formalism. 相似文献
97.
Mohammad Rezaee Hossein Ali Mashayekhi Abolfazl Saleh Yaser Abdollahzadeh Mohammad Hosein Naeeni Nazir Fattahi 《Journal of separation science》2013,36(16):2629-2634
A new pretreatment method, SPE combined with dispersive liquid–liquid microextraction, was proposed for the determination of abamectin in citrus fruit samples for the first time. In this method, fruit samples were extracted by ultrasound‐assisted extraction followed by SPE. Then, the SPE was used as a disperser solvent in the next dispersive liquid–liquid microextraction step for further purification and enrichment of abamectin. The effects of various parameters on the extraction efficiency of the proposed method were investigated and optimized. Good linearity of abamectin was obtained from 0.005 to 10.0 mg/kg for B1a and from 0.05 to 10.0 mg/kg for B1b with correlation coefficient (r2) of 0.998 for B1a and 0.991 for B1b, respectively. The LODs were 0.001 and 0.008 mg/kg (S/N = 3) for B1a and B1b, respectively. The relative recoveries at three spiked levels were ranged from 87 to 96% with the RSD less than 11% (n = 3). The method has been successfully applied to the determination of abamectin in citrus fruit samples. 相似文献
98.
Meghdad Pirsaheb Nazir Fattahi Mojtaba Shamsipur Tarokh Khodadadi 《Journal of separation science》2013,36(4):684-689
Dispersive liquid–liquid microextraction based on solidification of floating organic drop coupled with HPLC‐UV detection as a fast and inexpensive technique was applied to the simultaneous extraction and determination of traces of two common herbicides, alachlor and atrazine, in aqueous samples. The critical experimental parameters, including type of the extraction and disperser solvents as well as their volumes, sample pH, salt addition, and extraction time were investigated and optimized. Under the optimum conditions, the calibration graphs found to be linear in the range of 0.1–200 μg/L with LOD in the range of 0.02–0.05 μg/L. The RSDs were in the range of 4.2–5.3% (n = 5). The relative recoveries of well, tap, and river water samples which have been spiked with different levels of herbicides were 94.0–106.0, 99.0–105.0, and 88.5–97.0%, respectively. 相似文献
99.
100.
Meghdad Pirsaheb Yadolah Fakhri Mohammad Karami Rokhsareh Akbarzadeh Zahra Safaei Nazir Fatahi 《International journal of environmental analytical chemistry》2013,93(13):1353-1364
ABSTRACTThis study was conducted to investigate the residues of pyrethroid and organophosphorus pesticide in flour and breads which were collected from local markets in Kermanshah province, Iran. Four different types of breads and two types of flour samples with high distribution were taken from market and their residues of pesticides were measured. A simple dispersive liquid–liquid microextraction (DLLME) method with solidification of floating organic drop was developed for the measurement. The health risk of these pesticides on adults and children health was assessed by target hazard quotient (THQ) using Monte Carlo simulation (MCS) method. About, 15% and 11.1% of total samples contained detectable levels of deltamethrin and malathion, respectively. None of the tested samples showed any permethrin residue. The results from all samples showed that none of the pesticides exceeded the maximum residue limits (MRLs). About 85% of pesticide residue detections were observed in tropical and mild weather area which is due to high consumption rate of insecticides in these areas. The percentile 95% of THQ is due to bread ingestion content of deltamethrin which was 0.033 and 0.070 for the adults and children, respectively, while this value for malathion was found to be, 0.015 and 0.030, respectively. In the adults and children for both deltamethrin and malathion, the percentile 95% of THQ value were lower than 1 (acceptable level). The non-carcinogenic health risk assessment indicated that bread consumers in Kermanshah province are not at a considerable risk because of deltamethrin and malathion. 相似文献