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81.
Javad Safaei-Ghomi Hossein Shahbazi-Alavi Abolfazl Ziarati Raheleh Teymuri Mohammad Reza Saberi 《中国化学快报》2014,25(3):401-405
CuI nanoparticles as an efficient catalyst have been used for the preparation of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones by the four-component condensation reaction of phthalic anhydride, hydrazine monohydrate, aromatic aldehydes and malononitrile or ethyl cyanoacetate under solventfree conditions in good to excellent yields, short reaction times and environmentally benign, milder reaction conditions. 相似文献
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Hajar Hosseinian Afsaneh Valipouri Seyed Abdolkarim Hosseini Ravandi Azam Alirezazadeh 《先进技术聚合物》2019,30(4):941-950
The increasing demand for nanofibers production has led to the rapid growth of the usage of electro‐centrifugal spinning (ECS) systems especially in recent years. Besides the rapid developments, fabrication of novel fibrous materials with novel techniques is still under investigation. Polyvinylepyrrolidone (PVP) is one of the multifunctional materials, which has attracted scientific interests to be employed in a variety of advanced applications. The main objective of the present study was therefore to explore the effects of essential parameters involved in fabrication of PVP nanofibers via an ECS system. The effects of rotational speed (197‐4051 r/min) and applied voltage (0‐14 kV) on the structural and morphological properties of nanofibers were also investigated. Analyses of the scanning electron microscope (SEM) images were performed with Digimizer and SPSS16.0 software to characterize the diameter distribution of the nanofibers. The degree of crystallinity was evaluated by the X‐ray diffraction method. In order to explain the unexpected results, further investigations were performed on the motion of the jet and flow rate. The results showed that instead of nanofibers, microparticles were formed at lower voltages and rotational speeds. The increase in the applied voltage resulted in a decrease in the minimum rotational speed that is required to form continuous fluid jet. The bending instabilities were changed from whipping to spiraling at the voltages above 10 kV. This resulted in the minimum fiber diameter at a voltage between 6 and 10 kV. Moreover, the applied voltage slightly affected the degree of crystallinity. No significant change was observed in the degree of crystallinity by varying the rotational speed. 相似文献
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Nasim Seifi M. Hassan Zahedi-Niaki M. Reza Barzegari Abolghasem Davoodnia Raheleh Zhiani Amir Aghaei Kaju 《Journal of molecular catalysis. A, Chemical》2006,260(1-2):77-81
Reaction of 6-hydrazino-1,5-diphenyl-1H-pyrazolo[3,4-d]pyrimidine-4-imine with aromatic aldehyde in presence of Preyssler catalyst yielded 8-aryl-1H-pyrazolo[4,3-e][1,2,4]triazolo[4,3-a] pyrimidine-4(5H)-imine. The performance of different form of Preyssler's anions including H14[NaP5W30O110], H14-P5, mixed-addenda H14[NaP5W29 MoO110], H14-P5Mo, silica supported H14[NaP5W30O110]/SiO2 and H14-P5/SiO2 have been investigated. The reaction results were compared with that of a conventional acid catalyst (H2SO4). 相似文献
86.
Secoisolariciresinol (SECO ) is the major lignan found in flaxseed (Linum usitatissimum L.) and is present in a polymer that contains secoisolariciresinol diglucoside (SDG ). SECO, SDG and the polymer are known to have a number of health benefits, including reduction of serum cholesterol levels, delay in the onset of type II diabetes and decreased formation of breast, prostate and colon cancers. The health benefits of SECO and SDG may be partially attributed to their antioxidant properties. To better understand their antioxidant properties, SECO and SDG were oxidized using 2,2'-azobis(2-amidinopropane), an in vitro model of radical scavenging. The major lignan radical-scavenging oxidation products and their formation over time were determined. SDG was converted to four major products, which were the result of a phenoxyl radical intermediate. One of these products, a dimer of SDG, decomposed under the reaction conditions to form two of the other major products, and . SECO was converted to five major products, two of which were also the result of a phenoxyl radical intermediate. The remaining products were the result of an unexpected alkoxyl radical intermediate. The phenol oxidation products were stable under the reaction conditions, whereas two of the alcohol oxidation products decomposed. In general, only one phenol group on the lignans was oxidized, suggesting that the number of phenols per molecule may not predict radical scavenging antioxidant ability of lignans. Finally, SECO is a superior antioxidant to SDG, and it may be that the additional alcohol oxidation pathway contributes to its greater antioxidant ability. 相似文献
87.
Raheleh Hamedi Mohammad Reza Hadjmohammadi 《Journal of the Iranian Chemical Society》2017,14(5):985-993
A sensitive and rapid method based on alcoholic-assisted dispersive liquid–liquid microextraction followed by high-performance liquid chromatography for determination of citalopram in human plasma and urine samples was developed. The effects of six parameters (extraction time, stirring speed, pH, volume of extraction and disperser solvents, and ionic strength) on the extraction recovery were investigated and optimized utilizing Plackett–Burman design and Box–Behnken design, respectively. According to Plackett–Burman design results, the volume of disperser solvent, stirring speed, and extraction time had no effect on the recovery of citalopram. The optimized condition was a mixture of 172 µL of 1-octanol as extraction solvent and 400 µL of methanol as disperser solvent, pH of 10.3 and 1% w/v of salt in the sample solution. Replicating the experiment in optimized condition for five times, gave the average extraction recoveries equal to 89.42%. The detection limit of citalopram in human plasma was obtained 4 ng/mL, and the linearity was in the range of 10–1200 ng/mL. The corresponding values for human urine were 5.4 ng/mL with the linearity in the range of 10–2000 ng/mL. Relative standard deviations for inter- and intraday extraction of citalopram were less than 7% for five measurements. The proposed method was successfully implemented for the determination of citalopram in human plasma and urine samples. 相似文献
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Maryam Oudi Kazem Sanchooli Tazeh Nourallah Hazeri Maryam Fatahpour Raheleh Ahmadi 《中国化学会会志》2019,66(12):1721-1728
In the present work, the catalytic activity of quinolinic acid (QUIN) was studied for the synthesis of spirochromene and pyranopyrazole derivatives from readily available materials. The salient features of these one‐pot multicomponent protocols are the clean reaction profile, easy isolation of products, no chromatographic separation techniques, high efficiency, short reaction time, and high yield of products plus using QUIN as a new, inexpensive, commercially available, and efficient organocatalyst. 相似文献
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In this work, the electron-transport properties of the molecular junction of oligothiophenes sandwiched between two Au (111) electrodes are studied based on the combination of the density functional theory and non-equilibrium Green’s function (NEGF) approach. From the calculation of electron properties, it is revealed that by increasing the number of thiophenes rings the (highest occupied molecular orbital-lowest unlocked molecular orbital) gap and the total energy decreases. Also, the transmission coefficient at zero voltage and the current–voltage curve for the thiophene molecules is calculated. The results indicate that the electrical conductivity and the value of band gap decrease exponentially with increasing the length of the molecules. Moreover, by simulating this molecular wire, we were able to obtain a current in the range of micro-amperes, which is a good current in the electronic application. However, it is known that the linear-response conductance is overestimated about an order of magnitude or more by the NEGF?+?DFT approach when semi-local approximate functional like PBE is used. 相似文献
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Moradi Ahmad Toghraie Davood Isfahani Amir Homayoon Meghdadi Hosseinian Ali 《Journal of Thermal Analysis and Calorimetry》2019,137(5):1797-1807
Journal of Thermal Analysis and Calorimetry - This paper presents the results of an experimental investigation on the heat transfer characteristics of multi-walled carbon nanotube aqueous... 相似文献