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21.
The nanocrystalline cubic phase of zirconia was found to be thermally stabilized by the addition of 3 to 40 mol % manganese. The nanocrystalline cubic, tetragonal and monoclinic phases of zirconia stabilized with manganese (III)oxide (Mn‐Stabilized Zirconia) were prepared by thermal decomposition of carbonate and hydroxide precursors. Both the crystallization and isothermal phase transitions associated with Mn‐SZ were studied using high temperature x‐ray diffraction and x‐ray diffraction of quenched samples. Cubic Mn‐SZ initially crystallized and progressively transformed to tetragonal, and monoclinic structures above 700°C. The nanocrystalline cubic Mn‐SZ containing 25 mol % Mn was found to have the greatest thermal stability, retaining its cubic form at temperatures as high as 800°C for periods up to 25 hours. Higher than 40 mol %, cubic Mn2O3 was found to coexist with cubic Mn‐SZ. The crystallite sizes observed for the cubic, tetragonal and monoclinic Mn‐SZ phases ranged from 50 to 137, 130 to 220, and 195 to 450 Å respectively, indicating, for ZrO2, that particle size was a primary factor in determining its polymorphs. The classical Avrami equation for nucleation and growth was applied to the observed phase transformations. 相似文献
22.
A bounding surface plasticity model for non-coaxiality, another aspect of anisotropic behavior of sands under rotation of principal stress axes; is developed in the critical state framework. Numerous experimental evidences exist that corroborate dependence of plastic shear strain rate direction on inherent fabric anisotropy. At first, general expressions for plastic strain rate with respect to possible emerge of non-coaxial flow are obtained. Consequently, using an anisotropy state parameter that is specially developed for this model and accounts for the interaction between imposed loading and soil fabric; effect of anisotropy on plastic flow direction is taken into account. Besides, novel circumstances are proposed for plastic modulus and dilatancy under rotation of principal stress axes. Finally, it is shown that the model is able to simulate successfully the non-coaxial behavior of sands subjected to principal stress axes rotation. 相似文献
23.
Jafar Abbasi Shiran Manouchehr Mamaghani Bohari M. Yamin Jalal Albadi Farhad Shirini 《合成通讯》2013,43(13):1520-1532
A convenient, one-pot, three-component regioselective synthesis of novel 2,2′-(1,4-phenylene)-bis-(3-aryl-2-substituted imino-4-aryl-3H-thiazole) derivatives from 1,4-phenylene diisothiocyanate, aryl amines, and various phenacyl bromide, and also the regioselective synthesis of 3-alkyl-2-(aryl imino)-4-cyclopropyl-5-(2′-fluorophenyl)-thiazole derivatives from alkylisothiocyanate, aryl amines, and 2-bromo-2-(2-fluorophenyl)-1-cyclopropylethanone in the presence of poly-4-vinyl pyridine as heterogenous basic catalyst are described. This efficient method produced the products at room temperature with excellent yields (82–96%). The structures of all products were characterized by spectral and elemental analyses. The antimicrobial activity of the synthesized compounds was evaluated against Salmonella enterica, Micrococcus luteus, Bacillus subtilis, and Pseudomonas aeruginosa. 相似文献
24.
Khalil Tabatabaeian Manouchehr Mamaghani Nosratollah Mahmoodi Alireza Khorshidi 《合成通讯》2013,43(11):1677-1684
Diastereoselective conjugate 1,4-addition of indoles to α,β-unsaturated carbonyl compounds (hormone steroids) using Ru(III) as catalyst is reported. It was found that RuCl3·nH2O catalyzes the Michael addition of indoles to hormone steroids, providing new 3-alkylated derivatives in good to excellent yields. 相似文献
25.
Moona Mohsenimehr Manouchehr Mamaghani Farhad Shirini Mehdi Sheykhan Fatemeh Azimian Moghaddam 《中国化学快报》2014,25(10):1387-1391
Novel pyrido[2,3-d]pyrimidine derivatives were synthesized through a one-pot three-component approach using HAp-encapsulated-γ-Fe2O3[γ-Fe2O3@HAp-SO3H]catalyzed condensation of 6-arnino-2-(methylthio or ethylthio)pyrimidin-4(3H)-one,Meldrum's acid and aryl aldehydes at 60 ℃ and under solvent-free conditions.In this protocol the use of nanocatalyst provided a green,useful and rapid method to generate the products in short reaction times and excellent yields(88%-94%). 相似文献
26.
An efficient and convenient method for the synthesis of 1,4-dihydropyridines from β-dicarbonyl compounds, aldehydes, and ammonium acetate and the synthesis of fused 1,4-dihydropyridines from dimedone in the presence of Preyssler heteropolyacid catalyst are reported under reflux conditions with good to excellent yields. Preyssler heteropolyacid catalyst is easily prepared, stable (up to 300 °C), reusable, efficient, green and inexpensive. 相似文献
27.
-Azidophenyl -alkyl ketones in ethanolic potassium hydroxide at room temperature cyclise in high yield to 2,2-dialkylindoxyls. 相似文献
28.
Manouchehr Mamaghani Mona Jamali Moghadam Rogheyeh Hossein Nia 《Journal of the Iranian Chemical Society》2017,14(2):395-401
In this investigation, an efficient and ecofriendly multicomponent reaction is described for the green synthesis of 2-amino-5-arylpyrimido[4,5-b]quinolinedione derivatives using ZrO2 (NPs). In this protocol, the reaction of 2,6-diaminopyrimidin-4(1H)-one, arylaldehyde and 1,3-cyclohexanedione or 5,5-dimethyl-1,3-cyclohexanedione in the presence of ZrO2 (NPs) in ethylene glycol at 120 °C produced the desired products in excellent yields (90–98 %) and short reaction times (8–60 min.). Use of recyclable catalyst, green solvent, easy workup and excellent yields are the notable features of this method. 相似文献
29.
Abbas Azimi Roshan Manouchehr Mamaghani Nosrat Ollah Mahmoodi Farhad Shirini 《中国化学快报》2012,23(4):399-402
An efficient ultrasound-assisted preparation of a series of novel 4-aryl-3-methyl-4,5-dihydro-l//-pyrazolo[34-b]pyridin-6(7H)ones via the reaction of 5-amino-3-methyl-1H-pyrazole,Meldrum’s acid and various arylaldehydes using one-pot three-component approach is described.This rapid method produced the products in short reaction times(3-4 min) and excellent yields(87-95%). 相似文献
30.
Maryam Saffari Jourshari Manouchehr Mamaghani Khalil Tabatabaeian Farhad Shirini 《Journal of the Iranian Chemical Society》2012,9(1):75-80
A facile and convenient protocol was developed for the synthesis of 5-arylidene-2-imino-4-thiazolidinones using solid basic catalyst immobilized onto supported ionic liquid-like phase (SILLP) in high yields (80?C95%). The X-ray analysis of the representative compound established the Z configuration of the product at the chiral axis. 相似文献