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排序方式: 共有320条查询结果,搜索用时 250 毫秒
31.
Seyyed Javad Sabounchei Sadegh SalehzadehMarjan Hosseinzadeh Fateme Akhlaghi BagherjeriHamid Reza Khavasi 《Polyhedron》2011,30(15):2486-2492
The reaction of the new ambidentate ylide, Ph3PCHCOCH2COOC2H5 (EAPPY), with HgX2 (X = Cl, Br and I) in equimolar ratios using methanol as the solvent leads to binuclear complexes of the type [EAPPY·HgX2]2 (X = Cl (1), Br (2) and I (3)). Single crystal X-ray analysis reveals the presence of a centrosymmetric dimeric structure containing the ylide and HgX2 (X = Br or I). The IR and NMR data of the product [(EAPPY)·HgCl2]2 (1), formed by the reaction of mercury(II) chloride with the same ylide, are similar to those of 2 and 3. Analytical data indicate a 1:1 stoichiometry between the ylide and Hg(II) halide in each of the three products. Theoretical studies indicate that the nature of the R group in ylides of the type Ph3PCHCOR has a weak effect on the Hg-C(ylide) bond length in binuclear Hg2L2I4 complexes. 相似文献
32.
The hydrocarbon plus fractions that comprise a significant portion of naturally occurring hydrocarbon fluids create major problems when determining the thermodynamic properties and the volumetric behavior of these fluids by equations of state. These problems arise due to the difficulty of properly characterizing the plus fractions (heavy ends). Proper characterization of the heavier components is important when cubic equations of state and/or solid formation thermodynamic models are used to describe complex phase behavior of reservoir fluids. The effect of heavy fractions characterization on thermodynamic modeling of wax precipitation has been investigated using different models including Won, Pan and proposed models. In order to characterize the plus fraction (heavier part) as a series of pseudocomponents, a probability model that expresses the mole fraction as a continuous function of the molecular weight has been used. The study has been conducted using several mixtures. Two different SCN (single carbon number), C7+ and C10+ were chosen. The Chosen SCN were distributed to multi-components of five, six, and/or ten using continuous function and Gaussian quadrature method. The results showed that the fractioning is required to be able to predict wax precipitation. Distribution of C10+ using a proper distribution function has shown improvement in predictions of WAT and the amount of wax deposited in comparison with the characterization of C7+ using semi-continuous approach. In predicting of WAT and the amount of wax build up the developed model showed superiority over the others. 相似文献
33.
Fresnel biprism is a one dimensional refractive element that has a lateral linear phase. Having been considered this element as a refractive axicon, its focal depth was evaluated theoretically and experimentally by means of Fresnel–Kirchhoff integral. It is shown that its focal length is a function of its refractive index and its apex angle. Experimental results are in very good agreement with theoretical work. 相似文献
34.
René Carmona Jean-Pierre Fouque Seyyed Mostafa Mousavi Li-Hsien Sun 《Journal of Optimization Theory and Applications》2018,179(2):366-399
We propose a model of inter-bank lending and borrowing which takes into account clearing debt obligations. The evolution of log-monetary reserves of banks is described by coupled diffusions driven by controls with delay in their drifts. Banks are minimizing their finite-horizon objective functions which take into account a quadratic cost for lending or borrowing and a linear incentive to borrow if the reserve is low or lend if the reserve is high relative to the average capitalization of the system. As such, our problem is a finite-player linear–quadratic stochastic differential game with delay. An open-loop Nash equilibrium is obtained using a system of fully coupled forward and advanced-backward stochastic differential equations. We then describe how the delay affects liquidity and systemic risk characterized by a large number of defaults. We also derive a closed-loop Nash equilibrium using a Hamilton–Jacobi–Bellman partial differential equation approach. 相似文献
35.
H. Hossienkhani V. Fayaz S. A. A. Terohid N. Azimi Z. Zarei M. Ganji 《Theoretical and Mathematical Physics》2018,194(3):415-438
We study a dilaton scalar field coupled to ghost dark energy in an anisotropic universe. The evolution of dark energy, which dominates the universe, can be completely described by a single dilaton scalar field. This connection allows reconstructing the kinetic energy and also the dynamics of the dilaton scalar field according to the evolution of the energy density. Using the latest observational data, we obtain bounds on the ghost dark energy models and also on generalized dark matter and dark energy. For this, we investigate how the expansion history H(z) is determined by observational quantities. We calculate the evolution of density perturbations in the linear regime for both ghost and generalized ghost dark energy and compare the results with ΛCDM models. We discuss the justification of the generalized second law of thermodynamics in a Bianchi type-I universe. The obtained model is stable for large time intervals but is unstable at small times. 相似文献
36.
Shahram Rezapour Hassan Khandani Seyyed M. Vaezpour 《Rendiconti del Circolo Matematico di Palermo》2010,59(2):185-197
Let (E, τ) be a topological vector space and P a cone in E. We shall define a topology τ
P
on E so that (E, τ
P
) is a normable topological vector space and P is a normal cone with normal constant M = 1. Then by using the norm, we shall give some results about common fixed points of two multifunctions on cone metric spaces. 相似文献
37.
Seyyed Majid Jafarian Amiri 《代数通讯》2013,41(6):2055-2059
38.
Bahareh Azimi Claudio Ricci Alessandra Fusco Lorenzo Zavagna Stefano Linari Giovanna Donnarumma Ahdi Hadrich Patrizia Cinelli Maria-Beatrice Coltelli Serena Danti Andrea Lazzeri 《Molecules (Basel, Switzerland)》2021,26(14)
Cosmetics has recently focused on biobased skin-compatible materials. Materials from natural sources can be used to produce more sustainable skin contact products with enhanced bioactivity. Surface functionalization using natural-based nano/microparticles is thus a subject of study, aimed at better understanding the skin compatibility of many biopolymers also deriving from biowaste. This research investigated electrospray as a method for surface modification of cellulose tissues with chitin nanofibrils (CNs) using two different sources—namely, vegetable (i.e., from fungi), and animal (from crustaceans)—and different solvent systems to obtain a biobased and skin-compatible product. The surface of cellulose tissues was uniformly decorated with electrosprayed CNs. Biological analysis revealed that all treated samples were suitable for skin applications since human dermal keratinocytes (i.e., HaCaT cells) successfully adhered to the processed tissues and were viable after being in contact with released substances in culture media. These results indicate that the use of solvents did not affect the final cytocompatibility due to their effective evaporation during the electrospray process. Such treatments did not also affect the characteristics of cellulose; in addition, they showed promising anti-inflammatory and indirect antimicrobial activity toward dermal keratinocytes in vitro. Specifically, cellulosic substrates decorated with nanochitins from shrimp showed strong immunomodulatory activity by first upregulating then downregulating the pro-inflammatory cytokines, whereas nanochitins from mushrooms displayed an overall anti-inflammatory activity via a slight decrement of the pro-inflammatory cytokines and increment of the anti-inflammatory marker. Electrospray could represent a green method for surface modification of sustainable and biofunctional skincare products. 相似文献
39.
Hossein Jafarzadeh Hamid Reza Hamedi Seyyed Hossein Asadpour 《Optical and Quantum Electronics》2013,45(11):1133-1146
In this paper, coherent and incoherent control of optical properties of open ladder- type three-level atomic system is investigated. It is shown that in the presence of spontaneously generated coherence (SGC) and incoherent pumping filed, group velocity, absorption and dispersion of the probe field can be controlled by adjusting the ratio between atomic injection and exit rates. Also, the bistabal behaviors of the system are discussed. It is shown that the ratio between atomic injections and exit rate can influence the bistabal threshold intensity and related hysteresis loop. More interestingly, it is found that SGC and incoherent pumping field effects have a central role for distinguishing between open and closed system. 相似文献
40.
Mohammad Hossein Keshavarz Sahar Belyani Seyyed Mohammad Reza Darbani Masoud Kavosh Tehrani 《无机化学与普通化学杂志》2019,645(16):1057-1061
Laser Induced Breakdown Spectroscopy (LIBS) method is introduced as a novel approach in this work to study catalyst deactivation of V2O5/γ‐‐Al2O3 for gas‐phase dehydration of glycerol and producing acrolein. The LIBS results of V2O5/γ‐Al2O3 samples are compared with those data that are obtained by Inductively Coupled Plasma Optical Emission Spectrometry (ICP‐OES). Experimental data of LIBS data specify that line intensities of vanadium are decreased by deactivation of V2O5/γ‐Al2O3 catalyst. A comparison between the results of LIBS test as well as ICP‐OES analysis shows that the amount of vanadium is decreased in the catalyst. Moreover, coke formation changes the surface of the catalyst. The results of deactivation of V2O5/γ‐Al2O3 are also compared with Pd/C catalyst deactivation. 相似文献