Fabrication and characterization of highly crystalline mordenite membranes on α-alumina disks via a seeded in situ template-free hydrothermal treatment

A template-free seeded short-time in situ hydrothermal treatment was carried out in a brass autoclave to synthesize crystalline mordenite (MOR) membranes on alumina-silicate disk supports with micro-scale pores. According to XRD analysis, MOR was the only zeolitic material present in the membrane layers on the supports. SEM examination of the membranes showed three different layers of the membrane thickness: (i) support sub-layer, (ii) mix penetrated mid-layer, the MOR crystals filling the pores among the support (about 4–5 μm), and (iii) MOR top-layer (about 4–5 μm). The crystalline bonds between MOR crystals of the membrane top-layer and the crystals of the support were clearly observed within the mid-layer. The continuous top-layer of zeolitic membrane was formed by many large and well-shaped crystals. The seeding treatment significantly enhanced the formation of MOR crystals onto the surface of the supports. EDAX analysis showed a Si/Al ratio of 6.8 for the MOR layer of the membrane. Due to their hydrophilic natures, the polycrystalline MOR membranes were found to be selective for continuous dehydration of different EtOH–water mixtures through an adsorption–diffusion–desorption mechanism. Both total permeation flux and separation factor of the membrane were found to increase by increasing temperature and water concentration of feed. The continuity and high crystallinity of the membrane top-layer led to the fairly high dehydration of EtOH. It was found that there was no pinhole within the layer and the morphology of the membrane was almost defect-free.     

Meshless local Petrov-Galerkin (MLPG) approximation to the two dimensional sine-Gordon equation

During the past few years, the idea of using meshless methods for numerical solution of partial differential equations (PDEs) has received much attention throughout the scientific community, and remarkable progress has been achieved on meshless methods. The meshless local Petrov-Galerkin (MLPG) method is one of the “truly meshless” methods since it does not require any background integration cells. The integrations are carried out locally over small sub-domains of regular shapes, such as circles or squares in two dimensions and spheres or cubes in three dimensions. In this paper the MLPG method for numerically solving the non-linear two-dimensional sine-Gordon (SG) equation is developed. A time-stepping method is employed to deal with the time derivative and a simple predictor-corrector scheme is performed to eliminate the non-linearity. A brief discussion is outlined for numerical integrations in the proposed algorithm. Some examples involving line and ring solitons are demonstrated and the conservation of energy in undamped SG equation is investigated. The final numerical results confirm the ability of proposed method to deal with the unsteady non-linear problems in large domains.     

Effect of Aqueous Ablation Environment on the Characteristics of ZnO Nanoparticles Produced by Laser Ablation

Effect of ablation environment on the nature of ZnO nanoparticles produced by laser ablation method in liquid medium is investigated experimentally. High purity Zn plate was irradiated by the fundamental beam of a Q-switch Nd-YAG laser in cetyltrimethylammonium bromide (CTAB), acetone, sodium dodecyl sulfate and water. Produced nanoparticles were characterized by UV–Vis absorption spectroscopy, transmission electron microscopy, scanning electron microscopy, X-ray diffraction spectrum, and fourier transform infrared spectroscopy. Results show that the highest rate of ablation occurs in CTAB. Largest nanoparticles are produced in acetone, and crystallinity of nanoparticles produced in CTAB is higher than other samples. CTAB surfactant changed the morphology of ZnO nanoparticles.     

A greedy meshless local Petrov–Galerkin methodbased on radial basis functions

The meshless local Petrov–Galerkin (MLPG) method with global radial basis functions (RBF) as trial approximation leads to a full final linear system and a large condition number. This makes MLPG less efficient when the number of data points is increased. We can overcome this drawback if we avoid using more points from the data site than absolutely necessary. In this article, we equip the MLPG method with the greedy sparse approximation technique of (Schaback, Numercail Algorithms 67 (2014), 531–547) and use it for numerical solution of partial differential equations. This scheme uses as few neighbor nodal values as possible and allows to control the consistency error by explicit calculation. Whatever the given RBF is, the final system is sparse and the algorithm is well‐conditioned. © 2015 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 32: 847–861, 2016     

Synthesis of dimethyl 4-thiazolidinylphosphine oxides via addition of dimethylphosphine oxide to 3-thiazolines

The addition of dimethylphosphine oxide and its trimethylsiloxyphosphorus(III) derivative, generated in situ, to 3-thiazolines was found to yield dimethyl 4-thiazolidinylphosphine oxides via three different synthetic routes. The structures of two products were confirmed by X-ray analysis; common features include approximate envelope conformations of the five-membered rings and hydrogen bonding of the form N–H· · ·O=P. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8 : 207–215, 1997.     

New Form of the T-Duality Due to the Stability of a Compact Dimension

We study behaviors of a compact dimension and the T-duality, in the presence of the wrapped closed bosonic strings. When the closed strings interact and form another system of strings, the radius of compactification increases. This modifies the T-duality, which we call it as T-duality-like. Some effects of the T-duality-like will be studied.