RKKY interaction in the zigzag-edge silicene-like nanoflake

By considering the Kane-Mele-Hubbard approximation on the honeycomb lattice, we investigate the spin-spin correlation for two magnetic impurities in zigzag edge silicene-like nanoflake (ZSiLF). The dependence of the spatial behaviors of RKKY interaction on the electron-electron (e-e), intrinsic spin-orbit interactions (ISOI) and, electric field are systematically investigated. Generally, the spatial behaviors of the RKKY interaction sensitively change by changing e-e interaction and electric field strengths in the presence of ISOI. The ISOI in a ZSiLF result in long-range in-plane and Ising interactions. Moreover, e-e interaction induces non-zero Dzyaloshinsky-Moriya (DM) term and nearly distance-independent Ising interaction (similar to graphene nanoflake) in the presence of ISOI. Furthermore, with considering e-e interaction, the in-plane DM interaction increases by increasing the strengths of the electric field and ISOI.     

The study of the weibel electromagnetic instability growth rate in the presence of the body stress

Body stress flow can be expected in the fast ignition imploding of the inertial fusion process that strongly damps small‐scale velocity structures. The Weibel instability is one of the plasma instabilities that require anisotropy in the distribution function. The body stress effect was neglected in the calculation of the Weibel instability growth rate. In this article, the propagation condition of impinging waves and the growing modes of the Weibel instability on the plasma density gradient of the fuel fusion with the body stress flow are investigated. Calculations show that the minimum value of the body stress rate threshold in the linear polarization is about 2.96 times greater than that of the circular polarization. Increasing 10 times of the density gradient and decreasing 2 times of the wavelength in the linear polarization and the circular polarization, respectively, lead to about 1.78 × 10⁶ times increment and 0.019 times decrement in the maximum of the Weibel instability growth rate. Also, the Weibel instability growth rate maximum in the circular polarization is about 10⁷ times greater than that of the linear polarization. The body stress flow and the density gradient tend to stabilize the Weibel instability in the circular polarization and act as a destabilizing source in the linear polarization. Therefore, by increasing steps of the density gradient plasma near the relativistic electron beam‐emitting region, in the circular polarization, the Weibel instability occurs at a higher stress flow.     

Modification of Multiple Knot $B$-Spline Wavelet for Solving (Partially) Dirichlet Boundary Value Problem

A construction of multiple knot B-spline wavelets has been given in [C. K. Chui and E. Quak, Wavelet on a bounded interval, In: D. Braess and L. L. Schumaker, editors. Numerical methods of approximation theory. Basel: Birkhauser Verlag; (1992), pp. 57-76]. In this work, we first modify these wavelets to solve the elliptic (partially) Dirichlet boundary value problems by Galerkin and Petrov Galerkin methods. We generalize this construction to two dimensional case by Tensor product space. In addition, the solution of the system discretized by Galerkin method with modified multiple knot B-spline wavelets is discussed. We also consider a nonlinear partial differential equation for unsteady flows in an open channel called Saint-Venant. Since the solving of this problem by some methods such as finite difference and finite element produce unsuitable approximations specially in the ends of channel, it is solved by multiple knot B-spline wavelet method that yields a very well approximation. Finally, some numerical examples are given to support our theoretical results.     

Composite Polymer Nanoparticles via Transitional Phase Inversion Emulsification and Polymerisation

Summary: A new route was employed to produce composite polymer nanoparticles. First, a model polymer (a low molecular-weight polyisobutene) was dissolved in a model monomer (styrene) and then the solution was emulsified in water containing a pair of nonionic surfactants via a transitional phase inversion route. After phase inversion, which produced an oil-in-water miniemulsion, polymerisation of the vinyl monomer gave composite polymer particles. Low temperature emulsification was not practical because the inverted oil-in-water emulsions reinverted to water-in-oil emulsions upon raising the temperature to the reaction temperature. Miniemulsions prepared at the reaction temperature with low monomer content in the oil phase showed good stabilty in the course of polymerisation and produced latexes with a particle size similar to the size of drops in the initial miniemulsions.     

A novel one‐pot procedure for preparation of some new condensed pyrido[2,3‐d]pyrimidine(1H,3H)‐2,4‐diones

A novel one‐pot procedure for preparation of some new condensed pyrido[2,3‐d]pyrimidine(1H,3H)‐2,4‐diones based on condensation of ninhydrin, alkyl cyanoacetate, and 6‐aminouracil derivatives has been reported. The reactions were carried out in refluxed ethanol and were completed in less than 2 h. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:16–18, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20242     

The Crystallization,Melting Behaviors and Thermal Stability of Cross-linked Poly(3-hydroxybutyrate-<Emphasis Type="Italic">co</Emphasis>-3-hydroxyvalerate) by Octavinyloctasilasesquioxane

A series of cross-linked poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/octavinyloctasilasesquioxane (PHBV/OVS) composites were obtained by a simple melt reactive processing technique. Dicumyl peroxide (DCP) and OVS were employed as a free radical initiator and a cross-linking agent, respectively. The chemical structure of these produced composites were identified by ¹H/¹³C/²⁹Si-nuclear magnetic resonance spectroscopy (¹H/¹³C/²⁹Si-NMR) and Fourier transform infrared spectroscopy (FTIR). The melting behavior, non-isothermal crystallization, spherulite morphology and thermal stability property of PHBV/OVS composites were also investigated. The nucleation behaviors and crystallization rate of PHBV/OVS were significantly enhanced with the formation of cross-linked networks with different side-chains and cross-linking points. The red shift of crystalline peak temperature with addition of a small amount of OVS content evidenced the higher crystalline ability compared with the neat PHBV. However there was a threshold content, beyond which the crystallization rate weakened again. Additionally, the cross-linked structure of PHBV/OVS composites could be adjusted by changing the amount of OVS.     

Nano titania-supported sulfonic acid (n-TSA) as an efficient,inexpensive, and reusable catalyst for one-pot synthesis of 1, 8-dioxo-octahydroxanthene and tetrahydrobenzo[<Emphasis Type="Italic">b</Emphasis>]pyran derivatives

This paper explains how with the help of nano titania-supported sulfonic acid (n-TSA), new 1,8-dioxo-octahydroxanthene and tetrahydrobenzo[b]pyran derivatives can be produced. To do this, at first n-TSA, which is relatively cheap, easy separable and reusable was made. Next, using this nano catalyst,1,8-dioxo-octahydroxanthene and tetrahydrobenzo[b]pyran derivatives were synthesized from di-ketones and various aromatic aldehydes/or malononitrile without using solvent. Appropriate one-pot operation using different aromatic aldehydes with both electron donating and withdrawing groups have resulted in the best yields. Reusability of the nano catalyst, environmental friendliness, reduced reaction time, non-toxic reaction medium and catalyst high activity are substantial advantages of this work. Nowadays, it is really important that the catalyst can be recovered easily and reused five times while maintaining catalytic activity.     

Methylene blue removal from aqueous solution by magnetic clinoptilolite/chitosan/EDTA nanocomposite

In this study, clinoptilolite as a natural zeolite which was magnetized using precipitation of maghemite nanoparticles was coated by chitosan and then modified by thylenediamine tetra-acetic acid to add functional groups and its performance in the removal of toxic methylene blue from aqueous solution was investigated. Synthesized magnetic nanocomposite was characterized by VSM, XRD, SEM, and FTIR analyses. The saturation magnetization of the final nanocomposite was obtained as 22.2 emu/g. In addition, the factors affecting adsorption process and its optimization were investigated using response surface methodology and central composite design. Data obtained by different isotherm, adsorption kinetic and thermodynamic models were also studied. The results showed good agreement of these data with the Freundlich isotherm model (R ² = 0.99), and it was found that adsorption follows the second-order kinetics model (R ² = 1). Negative values of ΔG and positive values of ΔH obtained from this adsorption thermodynamic study revealed that the methylene blue adsorption process is exothermic and spontaneous. The optimum conditions to ensure maximum adsorption efficiency were determined, and included pH = 5.54, adsorbent amount of 0.03 g, temperature of 31.18 °C, and initial solution concentration of 16.21 mg/l which resulted in a removal efficiency of 99.44%. The results indicated that this nanocomposite can be used as a proper adsorbent for adsorbing methylene blue and other dye contaminants.     

The use of graphite/TiO2 nanocomposite additive for preparation of polyacrylic based visible-light induced antibacterial and self-cleaning coating

Research on Chemical Intermediates - Graphite/TiO2 nanocomposite additive was used to make a photocatalytic, hydrophilic, and antibacterial polyacrylic based coating. Various amounts of...