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131.
Omid Zabihi Aminreza KhodabandehS. Mojtaba Mostafavi 《Polymer Degradation and Stability》2012,97(1):3-13
Polythiophene nanoparticles as a conductive filler was prepared with average diameter of 20-35 nm and its molecular structure was confirmed by the FT-IR, TEM, XRD and UV-vis analysis. A new conductive epoxy nanocomposite was synthesized by curing of diglycidyl ether of bisphenol A/4,4′-(4,4′ Isopropylidenediphenoxy) bis (Phthalic Anhydride) involving various percentages of polythiophene nanoparticles. DSC and DMTA studies revealed that low percentage of the polythiophene nanoparticles, i.e. 1%, results in improved crosslink density as evidenced by increasing in the glass transition temperature. The addition of polythiophene nanoparticles into the epoxy matrix resulted in a significant increment in the electrical conductivity, mechanical properties, thermal stability and activation energy of thermal degradation. The advanced isoconversional method is utilized to describe the curing behavior and thermal degradation process of the neat epoxy and epoxy nanocomposite. We have utilized the Coats-Redfern and Criado methods to find the solid state thermal degradation reaction mechanism. For the nanocomposite, the mechanism was recognized to be two-dimensional diffusion (D2) reaction and it changes to a nucleation and growth (A4) for pure epoxy system. 相似文献
132.
Iman?Jabbari Zahir Abadi Omid?Sadeghi Hamid?Reza?Lotfizadeh Zhad Najmeh?Tavassoli Vahid?Amani Mostafa?M.?AminiEmail author 《Journal of Sol-Gel Science and Technology》2012,61(1):90-95
Nanoporous silica SBA-15 was prepared to evaluate its application as an oral drug delivery system. A series of surface-functionalized
nanopore materials as efficient clarithromycin delivery carriers was investigated. An efficient pH-responsive carrier system
was constructed by hydrogen bond interaction between carboxyl and hydroxyl groups in the clarithromycin and the amine group
in modified SBA-15. HPLC analyses of clarithromycin were run on a C18 column using a mobile phase comprised of potassium dihydrogen phosphate, acetonitrile and methanol (30:40:30, v/v/v). Active
molecules such as clarithromycin could be stored and released from the pore voids of SBA-15 by changing the pH. The amount
of clarithromycin stored in the pores of nanoporous silica based on TREN [tris(2-aminoethyl) amine]-modified SBA-15 rods was
up to 46 ± 4.8 wt% at pH 8. In addition, when the pH was below 4, clarithromycin was steadily released from the pores of SBA-15
(up to 97 wt% in simulated gastric medium). 相似文献
133.
Ezzatollah Najafi Mostafa M. Amini Omid Sadeghi Hamid Reza Khavasi Seik Weng Ng 《Heteroatom Chemistry》2011,22(6):699-706
The reaction of 4,4′‐bipy with dimethyltin(IV) chloride iso‐thiocyanate affords the one‐dimensional (1D) coordination polymer, [Me2Sn(NCS)Cl·(4,4′‐bipy)]n ( 1 ), whereas reaction of dimethyltin(IV) dichloride with sodium pyrazine‐2‐carboxylate in the presence of potassium iso‐thiocyanate affords the two‐dimensional (2D) coordination polymer, {[Me2Sn(C4H3N2COO)2]2 [Me2Sn(NCS)2]}n ( 2 ). Both coordination polymers were characterized by elemental analysis and infrared spectroscopy in addition to 1H and 13C NMR spectroscopy of the soluble coordination polymer ( 1 ). A single‐crystal structure determination showed that the asymmetric unit in 1 contains Me2Sn(NCS)Cl and 4,4′‐bipy moieties and a 1D infinite rigid chain structure forms through bridging of the 4,4′‐bipy ligand between tin atoms and the geometry around the tin atom is a distorted octahedral. Coordination polymer 2 contains two distinct tin atom geometrics in which one tin atom is seven coordinate, and the other is six coordinate. The two tin atom environments are best described as a pentagonal bipyramidal in the former and distorted octahedral in the latter where the carboxylate groups bridge the two tin atoms and construct a 2D‐coordination polymer. The 119Sn NMR spectroscopy indicates the octahedral geometry of 1 retains in solution. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:699–706, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/.20736 相似文献
134.
The goal of the research presented here is to apply a global analysis of an inductively heated Czochralski furnace for a real sapphire crystal growth system and predict the characteristics of the temperature and flow fields in the system. To do it, for the beginning stage of a sapphire growth process, influence of melt and gas convection combined with radiative heat transfer on the temperature field of the system and the crystal‐melt interface have been studied numerically using the steady state two‐dimensional finite element method. For radiative heat transfer, internal radiation through the grown crystal and surface to surface radiation for the exposed surfaces have been taken into account. The numerical results demonstrate that there are a powerful vortex which arises from the natural convection in the melt and a strong and large vortex that flows upwards along the afterheater side wall and downwards along the seed and crystal sides in the gas part. In addition, a wavy shape has been observed for the crystal‐melt interface with a deflection towards the melt. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
135.
In this study, magnetite (Fe3O4) nanocrystals with a size range of 25 nm were prepared by the facile chemical coprecipitation method by a surfactant-assisted from the solution of FeCl3.6H2O salt-solution. In the process, we used octanoic acid as surfactant. In addition, the magnetic hysteresis measured shows that the rods obtained display ferromagnetic properties at room temperature. The samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The magnetic property was studied with vibrating sample magnetometer. 相似文献
136.
Mieszawska AJ Gianella A Cormode DP Zhao Y Meijerink A Langer R Farokhzad OC Fayad ZA Mulder WJ 《Chemical communications (Cambridge, England)》2012,48(47):5835-5837
Polylactic-co-glycolic acid (PLGA) based nanoparticles are biocompatible and biodegradable and therefore have been extensively investigated as therapeutic carriers. Here, we engineered diagnostically active PLGA nanoparticles that incorporate high payloads of nanocrystals into their core for tunable bioimaging features. We accomplished this through esterification reactions of PLGA to generate polymers modified with nanocrystals. The PLGA nanoparticles formed from modified PLGA polymers that were functionalized with either gold nanocrystals or quantum dots exhibited favorable features for computed tomography and optical imaging, respectively. 相似文献
137.
Network design problem has been, and is, an important problem in transportation. Following an earlier effort in designing a meta-heuristic search technique by an ant system, this paper attempts to hybridize this concept with other meta-heuristic concepts such as genetic algorithm, simulated annealing, and tabu search. Seven hybrids have been devised and tested on the network of Sioux Falls. It has been observed that the hybrids are more effective to solve the network design problem than the base ant system. Application of the hybrid containing all four concepts on a real network of a city with over 2 million population has also proved to be more effective than the base network, in the sense of finding better solutions sooner. 相似文献
138.
Mehdi Razavi Mohammadhossein Fathi Omid Savabi Daryoosh Vashaee Lobat Tayebi 《Surface and interface analysis : SIA》2014,46(6):387-392
Magnesium alloys are promising biomaterials as biodegradable implant for orthopedic applications. However, their low corrosion resistance and poor bioactivity have prohibited their implant applications. In order to enhance these two properties, a nano‐grain merwinite coating was prepared on magnesium alloy. Its corrosion and the bioactivity behavior were characterized with electrochemical and immersion tests. The results showed that the nano‐grain merwinite coating can improve both the corrosion resistance and the bioactivity of the magnesium alloy making it an appropriate material for biodegradable bone implants. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
139.
Mohammad Hemmat Esfe Seyfolah Saedodin Omid Mahian Somchai Wongwises 《Journal of Thermal Analysis and Calorimetry》2014,117(2):675-681
A considerable number of studies can be found on the thermal conductivity of nanofluids in which Al2O3 nanoparticles are used as additives. In the present study, the aim is to measure the thermal conductivity of very narrow Al2O3 nanoparticles with the size of 5 nm suspended in water. The thermal conductivity of nanofluids with concentrations up to 5 % is measured in a temperature range between 26 and 55 °C. Using the experimental data, a correlation is presented as a function of the temperature and volume fraction of nanoparticles. Finally, a sensitivity analysis is performed to assess the sensitivity of thermal conductivity of nanofluids to increase the particle loading at different temperatures. The sensitivity analysis reveals that at a given concentration, the sensitivity of thermal conductivity to particle loading increases when the temperature increases. 相似文献
140.
Dr. Lauren K. Macreadie Dr. Ravichandar Babarao Caitlin J. Setter Seok J. Lee Dr. Omid T. Qazvini Dr. Aaron J. Seeber Dr. John Tsanaktsidis Prof. Shane G. Telfer Prof. Stuart R. Batten Prof. Matthew R. Hill 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(15):6146-6154
The resurgence of interest in the hydrogen economy could hinge on the distribution of hydrogen in a safe and efficient manner. Whilst great progress has been made with cryogenic hydrogen storage or liquefied ammonia, liquid organic hydrogen carriers (LOHCs) remain attractive due to their lack of need for cryogenic temperatures or high pressures, most commonly a cycle between methylcyclohexane and toluene. Oxidation of methylcyclohexane to release hydrogen will be more efficient if the equilibrium limitations can be removed by separating the mixture. This report describes a family of six ternary and quaternary multicomponent metal–organic frameworks (MOFs) that contain the three-dimensional cubane-1,4-dicarboxylate (cdc) ligand. Of these MOFs, the most promising is a quaternary MOF (CUB-30), comprising cdc, 4,4′-biphenyldicarboxylate (bpdc) and tritopic truxene linkers. Contrary to conventional wisdom that adsorptive interactions with larger, hydrocarbon guests are dominated by π–π interactions, here we report that contoured aliphatic pore environments can exhibit high selectivity and capacity for LOHC separations at low pressures. This is the first time, to the best of our knowledge, where selective adsorption for cyclohexane over benzene is witnessed, underlining the unique adsorptive behavior afforded by the unconventional cubane moiety. 相似文献