High-order ghost-point immersed boundary method for viscous compressible flows based on summation-by-parts operators

A high-order immersed boundary method is devised for the compressible Navier-Stokes equations by employing high-order summation-by-parts difference operators. The immersed boundaries are treated as sharp interfaces by enforcing the solid wall boundary conditions via flow variables at ghost points. Two different interpolation schemes are tested to compute values at the ghost points and a hybrid treatment is used. The first method provides the bilinearly interpolated flow variables at the image points of the corresponding ghost points and the second method applies the boundary condition at the immersed boundary by using the weighted least squares method with high-order polynomials. The approach is verified and validated for compressible flow past a circular cylinder at moderate Reynolds numbers. The tonal sound generated by vortex shedding from a circular cylinder is also investigated. In order to demonstrate the capability of the solver to handle complex geometries in practical cases, flow in a cross-section of a human upper airway is simulated.     

Synthesis,Characterization, and Catalytic Activity of Heteroleptic Rhodium Complex for C–N Couplings

Russian Journal of Coordination Chemistry - We have reported synthesis of complex [Rh(COD)(L{Me})Cl] (III), where L{Me} (II) is N-(1-methylpyridin-4(1H)-ylidene)benzamide and COD is...     

Ethylene to Propylene over Zeolite ZSM-5: Improved Catalyst Performance by Treatment with CuO

Russian Journal of Applied Chemistry - In this paper, the ZSM-5 zeolite base is used to produce light olefins in the process of converting ethylene to propylene, as well as copper oxide to improve...     

Temperature effects on spreading of water nano‐droplet on poly(methyl methacrylate): A molecular dynamics simulation study

In this article, the effect of temperature on the spreading behavior of a water nano‐droplet on poly(methyl methacrylate) substrate is investigated. The contact angle analysis illustrates that the spreading process occurs in a stage‐like manner and the increase in temperature causes a regime change from partial to total wetting. The interaction energy distributions show that there exist sites on the surface which could trap water molecules and provide a better path for other molecules to overcome the asperities. Estimations of the coefficients of self‐diffusivity suggest that temperature has a major effect in the reorientation stage, which results in the formation of the interfacial layer. In the second stage of spreading, temperature affects the process by providing sufficient energy for water molecules to overcome the interactions with the substrate. Therefore, this stage is controlled by the movement of water molecules on the surface and is highly influenced by their interaction with the surface asperities, strong interaction sites, and the carbonyl groups. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1532–1541     

Stability study of the gastric floating dosage form of capecitabine

Since administration of capecitabine tablets leading to dose limiting makes the unfavorable toxicity, preparation of sustained-release tablets will overcome most of these side effects. The aim of this study was to prepare and study the stability of capecitabine sustained-release tablets. Sustained-release tablets of capecitabine were characterized by differential scanning calorimetry, X-ray diffraction, and infrared and ultraviolet spectroscopy techniques to determine the stability of the tablets. All tests carried out for tablets upon preparation as well as 6 and 12 months after preparation. The gradual decomposition of capecitabine sustained-release tablets stored at accelerated conditions (40 °C in 75 % of relative humidity) was indicated by decreasing values of peak purity and melting temperature, calculated from the Van’t Hoff equation. Except for the occurrence of one sharp peak for long-term stability and some sharp peaks in the accelerated condition, all peaks showed a crystallized nature. But the FTIR and UV results showed that there were no changes between the initial sustained-release tablets and stored tablets. Although the XRD results showed more peaks in the accelerated condition tablets, the crystalline form of capecitabine was maintained. These findings demonstrate that the capecitabine sustained-release tablet has excellent stability in normal and long-term storage conditions, with slight changes in the accelerated condition.