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81.
An ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) was developed as a new approach for the extraction of organophosphorus pesticides (OPs) in water samples prior to high-performance liquid chromatography with diode array detection (HPLC-DAD). The use of a surfactant as an emulsifier in the UASEME method could enhance the dispersion of water-immiscible extraction solvent into aqueous phase and is favorable for the mass-transfer of the analytes from aqueous phase to the organic phase. Several variables that affect the extraction efficiency, including the kind and volume of the extraction solvent, the type and concentration of the surfactant, salt addition, ultrasound emulsification time and temperature, were investigated and optimized. Under the optimum experimental conditions, the calibration curve was linear in the concentration range from 1 to 200 ng mL(-1) for the seven OPs (isocarbophos, phosmet, parathion, parathion-methyl, fenitrothion, fonofos and phoxim), with the correlation coefficients (r) varying from 0.9973 to 0.9998. High enrichment factors were achieved ranging from 210 to 242. The established UASEME-HPLC-DAD method has been successfully applied for the determination of the OPs in real water samples. The limits of detection were in the range between 0.1 and 0.3 ng mL(-1). The recoveries of the target analytes over the three spiked concentration levels of the compounds (10, 50, and 100 ng mL(-1), respectively) in rain, reservoir and well water samples were between 83% and 106% with the relative standard deviations varying from 3.3% to 5.6%. 相似文献
82.
Naser Seyed-Matin Amir Hossein Jalili Masih Hosseini Jenab Seyed Majid Zekordi Ali Afzali Chapar Rasouli Akbar Zamaniyan 《Plasma Chemistry and Plasma Processing》2010,30(3):333-347
The carbon dioxide reforming of methane to synthesis gas under DC-pulsed plasma was investigated. The effects of specific
input energy and feed ratio on the product distribution and also feed conversion was studied. At the input energy of about
11 eV/molecule per methane and/or carbon dioxide the feed conversion of 38% for CH4 and 28% for CO2 and product selectivity of 74% has been attained for H2 and CO at feed flow rate of 90 ml/min. The energy consumption in this work displays potential to further study and optimization
of the process. The importance of the electron impact reactions in the process was discussed. The results show that by prudent
tuning of system variables, the process be able to run in the way of synthesis gas, instead of hydrocarbon production. 相似文献
83.
Mohsen Nikpour Hossein Eshtiagh-Hosseini Masoud Mirzaei Amir Aghaei Kaju Soroush Zarinabadi 《中国化学快报》2010,21(4):501-505
<正>A unique ionic hybrid material[C_6H_(12)N_5O]_3[(PO_4)W__(12)O_(36)]·5H_2O has been synthesized from the reaction of((1H-tetrazole-5- yl)methyl)morpholine andα-H_3[(PO_4)W_(12)O_(36)]·21H_2O.It has successfully been characterized by elemental analysis,IR and ~1H NMR spectroscopies,TGA and single-crystal X-ray diffraction method.The title compound is constructed from the three [C_6H_(12)N_5O]~+ cations andα-Keggin[(PO_4)W_(12)O_(36)]~(3-) polyoxoanion.The most remarkable structural feature of this hybrid can be described as two-dimensional inorganic infinite plane-like(2D/∞)[(PO_4)W_(12)O_(36)]~(3-)) which forming via van der Waals interactions along the x axis. 相似文献
84.
Hassan Karami Amir Aminifar Hossein Tavallali Zeinol-Abedin Namdar 《Journal of Cluster Science》2010,21(1):1-9
CdO–ZnO nanocomposite was fabricated by a sol–gel pyrrolysis method based on the poly vinyl alcohol (PVA) polymeric network.
The prepared nanocomposite was carefully characterized using scanning electron microscopy, X-Ray dispersive energy analysis,
ICP-atomic emission spectroscopy, X-Ray diffraction, transmission electron microscopy and UV–visible spectroscopy. The structure,
composition, and morphology of this composite depend on a number of aspects: the amounts of cadmium salt, zinc salt, and PVA
in the initial solution, the solvent composition, and the pyrrolysis temperature. The obtained results showed that the nanocomposite
had excellent linear nanoclusters created from nanograins. Each nanograin was made of a CdO core, completely covered by ZnO
layers. Total diameter of each nanograin was 70–90 nm. 相似文献
85.
Shubha Pandey Jyotsna R. Kar Amir Azam Siddharth Pandey H. M. Chawla 《Journal of solution chemistry》2010,39(1):107-120
Long chain calix[4]arene ethers have been examined for aggregation in nonaqueous solvents by using UV-vis molecular absorbance
spectroscopy. It has been observed that tetraalkylated (alkyl = hexadecyl and octadecyl, respectively) calix[4]arene ethers
tend to aggregate in chloroform and tetrahydrofuran, possibly via π–π stacking interactions of the phenyl moieties, and the aggregation process appears to be facilitated by the alkyl chains.
The analogous dialkylated compounds do not show any self-aggregation, plausibly due to strong hydrogen bonding between the
–OH and the –O– of calix aryl ether which seems to disrupt the aggregation process. Addition of the anionic surfactant sodium
dodecylsulfate (SDS) appears to hinder the aggregation process in nonpolar chloroform but the same surfactant facilitates
aggregation in the polar tetrahydrofuran. The cationic surfactant (cetyltrimethyl ammonium bromide) and the nonionic surfactant
(Brij-35) have no effect on this aggregation process. Unexpectedly, SDS induces aggregation of dialkylated calix[4]arene ethers
in chloroform. It has been observed that the aggregated form of the tetraalkylated calix[4]arene ethers tend to increase the
dimerization efficiency of cationic dyes (pinacyanol chloride and methylene blue) in chloroform. 相似文献
86.
Amir Khojastehnezhad Hossein Eshghi Farid Moeinpour Mehdi Bakavoli Mohammad Izadyar Javad Tajabadi 《Structural chemistry》2016,27(4):1041-1047
The mechanism (regio- and stereoselectivity) of 1,3-dipolar cycloaddition (1,3-DC) of 2-ethylthio-4-phenyl-1-azetin 1 with benzonitrile oxide 2a, 2-aminobenzonitrile oxide 2b and 2-azidobenzonitrile oxide 2c has been investigated by density functional theory-based reactivity indices and activation energy calculations at B3LYP/6-31G(d,p) level of theory in the gas and solvent phase. Thermodynamic and kinetic parameters of the possible ortho/meta regioisomeric and endo/exo stereoisomeric pathways have been determined. In order to rationalize complete endo selective fashion provided by these 1,3-DC cycloadditions, a natural steric analysis between NLMOs i,j for TS1ox and TS1on and also a second-order interaction energy, E 2, analysis between the donor–acceptor orbitals in these TSs were carried out. In all cases, the ortho pathways are more favorable compared to the meta alternatives and it is found that the endo pathway is preferred. Our results show that these cycloadditions follow an asynchronous one-step mechanism with a nonpolar character. Theoretical data are in good agreement with the experimental results. 相似文献
87.
88.
89.
Shahan Zeb Khan Muhammad Kashif Amir Imdad Ullah Asma Aamir John M. Pezzuto Tamara Kondratyuk Francine Bélanger‐Gariepy Akbar Ali Sajid Khan Zia‐ur‐Rehman 《应用有机金属化学》2016,30(6):392-398
Two new heteroleptic palladium(II) complexes have been synthesized by reacting equimolar quantities of palladium(II) chloride, sodium 4‐(2‐methoxyphenyl)piperazine‐1‐carbodithioate and diphenyl‐p‐tolylphosphine ( 1 ) or tri‐p‐tolylphosphine ( 2 ). Complexes 1 and 2 have been characterized using elemental analysis, Fourier transform infrared spectroscopy, multinuclear NMR (1H, 13C and 31P) spectroscopy and single‐crystal X‐ray analysis. The latter technique confirms a pseudo square‐planar geometry in which two adjacent positions are occupied by bidentate dithiocarbamate while chloro and substituted triphenylphosphine are present at the remaining two positions. The anticancer activity of both complexes against five different cancer cell lines (LU – human lung carcinoma, established at UIC, Department of Surgical Oncology; MCF7 – human breast adenocarcinoma, ATCC number HTB‐22?; MDA‐MB‐231 – human breast adenocarcinoma, ATCC number HTB‐26?; Hepa‐1c1c7 – mouse liver hepatoma, ATCC number CRL‐2026?; PC‐3 – human prostate adenocarcinoma, ATCC number CRL‐1435?) was determined by MTT assay, revealing 2 has higher activity than 1 . A drug–calf thymus DNA binding study with UV–visible spectroscopy reveals a higher DNA binding affinity of 2 (3.511 × 104 M?1) than 1 (4.213 × 103 M?1). Density functional theory studies confirm the relatively more stable nature of 2 than 1 . Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
90.
Reza Alizadeh Sara Majd Jabbari Amir H. Zarnani Hamidreza Barghi 《Biomedical chromatography : BMC》2016,30(9):1346-1353
The present study deals with preparation and optimization of a novel chitosan hydrogel‐based matrix by suspension cross‐linking method for controlled release of Depo‐Medrol. The controlled release of Depo‐Medrol for effective Rheumatoid arthritis disease has become an imperative field in the drug delivery system. In this context, it was intended to optimize loading circumstances by experimental design and also study the release kinetics of Depo‐Medrol entrapped in the chitosan matrix in order to obtain maximal efficiency for drug loading. The optimum concentrations of chitosan (2.5 g), glutaraldehyde (3.05 μL) and Depo‐Medrol (0.1 mg) were set up to achieve the highest value of drug loaded and the most sustained release from the chitosan matrix. In vitro monitoring of drug release kinetic using high‐performance liquid chromatography showed that 73% of the Depo‐Medrol was released within 120 min, whereas remained drug was released during the next 67 h. High correlation between first‐order and Higuchi's kinetic models indicates a controlled diffusion of Depo‐Medrol through the surrounding media. Moreover, recovery capacity >82% and entrapment efficiency of 58–88% were achieved under optimal conditions. Therefore, the new synthesized Depo Medrol–chitosan is an applicable appliance for arthritis therapy by slow release mechanism. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献