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排序方式: 共有344条查询结果,搜索用时 15 毫秒
61.
H. Bargozin R. A. Hadadhania H. Faraji M. Yavari 《Journal of Dispersion Science and Technology》2016,37(6):884-893
By a new method of modeling, the DLVO energy interaction between rough nanoparticles and rough surfaces is investigated at various conditions. Rippled sphere model and surface element integration method are used. For calculation of energy interaction, the spherical coordinates are used and by increasing the radius ratio of two particles, the pseudo flat surfaces are generated. With increasing the radius ratio of two particles to 50, the large particle behaves as flat surface in front of small particle. Roughness, size of particles, temperature, zeta potential, capacity, and concentration of ions, which influence the stability of nanocolloidal solutions, are considered by the new method. Spherical coordinates enable to model the rough nanoparticles and rough surfaces so that no simplifying assumptions are needed, which was very difficult and time-consuming in Cartesian coordinate system. New method could predict the effect of different parameters on the stability of nanocolloidal systems precisely, easily, and at short times in comparison to Cartesian coordinate. 相似文献
62.
63.
Synthesis of tetrasubstituted pyrroles by the three-component condensation reaction of acid chlorides, dialkyl acetylenedicarboxylates,
and amino acids in the presence of various room-temperature ionic liquids (RTILs) as catalysts in water is reported. Among
the ionic liquids used, the basic functionalized ionic liquid, butyl methyl imidazolium hydroxide [bmim]OH, was the most effective
catalyst. The influence of reaction temperature, reaction time, and amount of ionic liquid on the reaction was investigated.
The [bmim]OH/H2O catalyst system could be reused for at least five recycles without appreciable loss of efficiency. 相似文献
64.
Mohammad A. Khalilzadeh Issa Yavari Zinatossadat Hossaini Hasan Sadeghifar 《Monatshefte für Chemie / Chemical Monthly》2009,140(4):467-471
Abstract A novel method for oxazine ring formation is established using the reaction of ammonium thiocyanate and acid chlorides with
napthols in the presence of N-methylimidazole to afford [1,3]oxazine-4-thione derivatives in excellent yields.
Graphical abstract
相似文献
65.
Issa Yavari Rahimeh Hajinasiri S. Zahra Sayyed-Alangi 《Monatshefte für Chemie / Chemical Monthly》2009,140(2):205-207
Abstract 1-Ethyl-3-methylimidazolium bromide was used as a green recyclable alternative to volatile organic solvents for KOH catalyzed
three-component synthesis of diethyl alkylsulfanylmethylmalonates from aldehydes, diethyl malonate, and alkylthiols.
Graphical Abstract A synthesis of diethyl alkylsulfanylmethylmalonates catalyzed by KOH in an ionic liquid
相似文献
66.
Arash Yavari 《Archive for Rational Mechanics and Analysis》2013,209(1):237-253
Compatibility equations of elasticity are almost 150 years old. Interestingly, they do not seem to have been rigorously studied, to date, for non-simply-connected bodies. In this paper we derive necessary and sufficient compatibility equations of nonlinear elasticity for arbitrary non-simply-connected bodies when the ambient space is Euclidean. For a non-simply-connected body, a measure of strain may not be compatible, even if the standard compatibility equations (“bulk” compatibility equations) are satisfied. It turns out that there may be topological obstructions to compatibility; this paper aims to understand them for both deformation gradient F and the right Cauchy-Green strain C = F T F. We show that the necessary and sufficient conditions for compatibility of deformation gradient F are the vanishing of its exterior derivative and all its periods, that is, its integral over generators of the first homology group of the material manifold. We will show that not every non-null-homotopic path requires supplementary compatibility equations for F and linearized strain e. We then find both necessary and sufficient compatibility conditions for the right Cauchy-Green strain tensor C for arbitrary non-simply-connected bodies when the material and ambient space manifolds have the same dimensions. We discuss the well-known necessary compatibility equations in the linearized setting and the Cesàro-Volterra path integral. We then obtain the sufficient conditions of compatibility for the linearized strain when the body is not simply-connected. To summarize, the question of compatibility reduces to two issues: i) an integrability condition, which is d(F dX) = 0 for the deformation gradient and a curvature vanishing condition for C, and ii) a topological condition. For F dx this is a homological condition because the equation one is trying to solve takes the form dφ = F dX. For C, however, parallel transport is involved, which means that one needs to solve an equation of the form dR/ ds = RK, where R takes values in the orthogonal group. This is, therefore, a question about an orthogonal representation of the fundamental group, which, as the orthogonal group is not commutative, cannot, in general, be reduced to a homological question. 相似文献
67.
Morteza Yavari 《理论物理通讯》2013,60(3):323-327
The study of the energy localization in f(R) theories of gravity has attracted much interest in recent years. In this paper, the vacuum solutions of the modified field equations for a power model of plane symmetric metric are studied in metric f(R) gravity with the assumption of constant Ricci scalar. Next, we determine the energy-momentum complexes in f(R) theories of gravity for this spacetime for some important models. We also show that these models satisfy the stability and constant curvature conditions. 相似文献
68.
In this paper, the effects of interband and intraband transitions on the gain and phase stabilities in quantum dot semiconductor optical amplifier (QD-SOA) are investigated both temporally and spectrally employing electrical and optical pumping schemes. For this purpose, the carrier rate equations in different energy states coupled to the traveling wave optical field equation have been numerically solved to derive the dynamical behavior of QD-SOA. Our results show that the gain and phase response can be stabled under optical pumping (OP) scheme because the role of the interband and intraband transitions on the dynamics of QD-SOA is reduced. This behavior leads to high-speed pattern effect-free cross-phase modulation (XPM) in QD-SOA. It is found that optically pumped QD-SOA can have high performance in phase based applications. Moreover, it is shown that under OP scheme although the QD-SOA has lower gain value and slower gain recovery time, the ultrafast cross-gain modulation (XGM) without pattern effect is possible and the phase is recovered within a shorter time compared to EP scheme. The behavior arises from the different capacity of the carrier reservoir for pumping schemes. 相似文献
69.
Landau damping in a dipolar Bose–Fermi mixture in the Bose–Einstein condensation(BEC) limit 下载免费PDF全文
By using a mean-field approximation which describes the coupled oscillations of condensate and noncondensate atoms in the collisionless regime, Landau damping in a dilute dipolar Bose–Fermi mixture in the BEC limit where Fermi superfluid is treated as tightly bounded molecules, is investigated. In the case of a uniform quasi-two-dimensional(2D)case, the results for the Landau damping due to the Bose–Fermi interaction are obtained at low and high temperatures. It is shown that at low temperatures, the Landau damping rate is exponentially suppressed. By increasing the strength of dipolar interaction, and the energy of boson quasiparticles, Landau damping is suppressed over a broader temperature range. 相似文献
70.
Fatemeh Esmaeili‐Marandi Mina Saeedi Issa Yavari Mohammad Mahdavi Abbas Shafiee 《Helvetica chimica acta》2016,99(1):37-40
A synthesis of isoindolo[2,1‐a]quinazolinedione derivatives, coupled with a 1,2,3‐triazole ring system, via the reaction of isatoic anhydride, HC?CCH2NH2, and 2‐formylbenzoic acid is described, which led to the formation of the isoindolo[2,1‐a]quinazoline‐5,11‐dione scaffold having a C?C bond that participated in a click reaction with various organic azides. 相似文献