Investigation the effects of shear rate on stationary droplets coalescence by lattice Boltzmann

Coalescence is the process by which two or more droplets merge to form a single droplet. It can take place in many processes, ranging from meteorology to astrophysics. When two stationary droplets are suspended in a bulk vapor, if the gap between the droplets has been smaller than a critical value, the two droplets will coalesce. In this paper, single component, two phase flow is modeled under shear flow using a free energy lattice Boltzmann approach and the coalescence of stationary droplets are investigated for different cases of radius and shear rate. The results show that there is a critical gap between droplets and for the values larger than that they will not coalesce. Also in the case of constant thermophysical properties, this critical gap is a function of droplet radius and shear rate.     

Copper-doped silica cuprous sulfate (CDSCS) as a highly efficient heterogeneous nano catalyst for synthesis of 3,5-disubstituted isoxazoles

A facile and highly efficient protocol for 1,3-dipolar cycloaddition of in situ generated nitrile oxides with terminal alkynes catalyzed by copper-doped silica cuprous sulfate (CDSCS) as a new and convenient heterogeneous nano catalyst is described. In this protocol, ‘click’ cycloaddition of various structurally diverse alkynes and imidoyl chlorides in the presence of CDSCS and NaHCO₃ in a solution of i-PrOH/H₂O (1:1, V/V) furnishes the corresponding 3,5-disubstituted isoxazoles in good to excellent yields at room temperature. CDSCS was approved as a chemically and thermally stable nano catalyst that can be recovered and reused for many consecutive trials without considerable decline in its reactivity.     

Novel disilyleno- and digermylenocarbenes and SiSi containing cyclopropenylidenes at theoretical levels

Following our quest for silylenes and germylenes, we have reached at W shaped novel triplet disilyleno- and digermylenocarbenes

through optimization of 2,3-di(X)disilacyclopropenylidenes and 2,3-di(X)digermacyclopropenylidenes, respectively, at five ab initio and DFT levels (M = Si, Ge; X = H, F, Cl, Br). Also, we have met the challenge of confining SiSi double bonds in singlet cyclopropenylidene ground states by optimizing singlet 2,3-di(X)disilacyclopropenylidenes, at the same levels of theory. Results are compared and contrasted to the corresponding singlet and triplet 2,3-di(X)cyclopropenylidenes.     

Synthesis,Crystal Structure,Spectral and Thermal Studies of (<Emphasis Type="Italic">E</Emphasis>)-4-Dimethamino[(1-phenylethyl)iminomethyl]benzyne

Abstract  

Schiff-base compound (E)-4-dimethamino[(1-phenylethyl)iminomethyl]benzyne was synthesized and characterized by elemental analyses (CHN), FT-IR and ¹H-NMR spectroscopic techniques and thermogravimetric analyses (TG). Crystal structure of the title compound was obtained by single crystal X-ray diffraction. The title compound crystallizes in the monoclinic space group P2₁ with unit cell parameters: a = 8.5283(2), b = 6.0699(2), c = 13.6997(4) Ǻ, β = 91.471(2)°, V = 708.94(4) Ǻ³ and Z = 2.     

Thresholds of moving average of stationary processes for given on target significant levels

A Markov chain is associated to a finite order one-sided moving average of a discrete time stationary Gaussian process. A method is developed to specify thresholds for given on target significant levels in the sense that in the long run the probability that the moving average process lies in [L _i , L _i+1), will be π _i , i = 0,. . . ,m. Special inputs, AR(1) and MA(1) are treated in details. This article extends the work of Soltani et al. in (Commun Stat Theory Methods 36(14):2595–2606) where the inputs were assumed to be i.i.d.; and a single threshold was considered. This research was supported by Kuwait University, Research Administration, Research Grant No.[SS08/06].     

Asymptotical time response of time varying state space dynamic using homotopy perturbation method

The main goal of this study is to present a technique to find a state response of multivariable time varying systems. In this paper a novel Homotopy Perturbation based Method (HPM) will be presented to find a dynamic response of time varying system. According to this method, the linear part of the described system is partitioned into two time varying and invariant subsections. Time invariant part analytically constructs the state transition matrix. This matrix is a core of the rest of time varying differential equation without any further changes in a sequence order. The main advantage of this method is only the necessity to solve the time invariant part of the state transition matrix. Simulation results verify the significance of the proposed analytic and asymptotic method.     

Functionalization of (<Emphasis Type="Italic">n</Emphasis>, 0) CNTs (<Emphasis Type="Italic">n</Emphasis> = 3–16) by uracil: DFT studies

Density functional theory (DFT) calculations were performed to investigate stabilities and properties for uracil (U)-functionalized carbon nanotubes (CNTs). To this aim, the optimized molecular properties were evaluated for (n, 0) models of CNTs (n = 3–16) in the original and U-functionalized forms. The results indicated that the dipole moments and energy gaps were independent of tubular diameters whereas the binding energies showed that the U-functionalization could be better achieved for n = 8–11 curvatures of (n, 0) CNTs. Further studies based on the evaluated atomic-scale properties, including quadrupole coupling constants (C _Q ), indicated that the electronic properties of atoms could detect the effects of diameters variations of (n, 0) CNTs, in which the effects were very much significant for the atoms around the U-functionalization regions. Finally, the achieved results of singular U, original CNTs, and CNT-U hybrids were compared to each other to demonstrate the stabilities and properties for the U-functionalized (n, 0) CNTs.