Dioxomolybdenum(VI) complexes of 2-hydroxybenzaldehyde 4-phenyl-S-methylthiosemicarbazone

Mixed ligand complexes of dioxomolybdenum(VI) with 2-hydroxybenzaldehyde 4-phenyl-S-methylthiosemicarbazone (H₂L) were prepared with the formula [MoO₂(L)D] (D = H₂O, methyl, n-butyl, and n-undecyl alcohol, DMF, DMSO, pyridine, 4-picoline, and 3,5-lutidine). The compounds were characterized by elemental analysis, IR and ¹H NMR spectroscopy. The thermal decomposition of the compounds were investigated by using TGA, DTG, and DTA methods in air, and the thermal behavior depending on the second ligand molecule was discussed. A single crystal of the DMF coordinated complex was studied by X-ray diffractometry. The text was submitted by the authors in English.     

An experimental investigation into the effect of vortex generators on the near-wake flow of a circular cylinder

The effect of the streamwise vortex generators on the near-wake flow structure of a circular cylinder was experimentally investigated. Digital particle image velocimetry (DPIV) measurements were performed in a large circulating water tunnel facility at a Reynolds number of 41,300 where the flow around a bare cylinder was expected to be at the sub-critical flow state. In order to capture various flow properties and to provide a detailed wake flow topology, the DPIV images were analysed with three different but complementary flow field decomposition techniques which are Reynolds averaging, phase averaging and proper orthogonal decomposition (POD). The effect of the vortex generators was clearly demonstrated both in qualitative and in quantitative manner. Various topological features such as vorticity and stress distribution of the flow fields as well as many other key flow characteristics including the length scales and the Strouhal number were discussed in the study. To the best of the authors’ knowledge, the study presents the first DPIV visualization of the near-wake flow of a circular cylinder fitted with the vortex generators in the open literature.     

Phase morphology of iPP/aPS/SEP blends

Supermolecular structure and phase morphology of the ternary isotactic polypropylene/atactic polystyrene/poly(styrene-b-ethylene-co-propylene) (iPP/aPS/SEP) compression molded blends with 100/0, 90/10, 70/30, and 50/50 iPP/aPS weight ratios and with different amounts of added SEP compatibilizer were studied by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD). SEP significantly reduced the size of dispersed aPS particles that enabled better spherulitization in the iPP matrix. Furthermore, iPP spherulites in ternary blends with 90/10 iPP/aPS weight ratio became larger in comparison with the pure iPP. TEM revealed that the SEP formed continuous interface layer around the dispersed aPS particles even when only 2.5 wt.% of SEP was added. Particle size distribution was distinctly bimodal. When the SEP content was increased to 10 wt.%, joining together smaller and bigger aPS and SEP particles formed dispersed aggregates. Additionally, both amorphous components (aPS and SEP) influenced crystallization process of iPP matrix and so modified, to some extent, its final supermolecular structure. SEP compatibilizer did not significantly affect crystallite orientation. The increase of crystallite sizes, which was more affected by the addition of aPS than by the addition of SEP, seemed to be influenced by the solidification effect rather than by the phase morphology of the blends.     

Critical behavior and magnetic entropy change in the La0.6Sr0.4Mn0.8Fe0.1Cr0.1O3 perovskite

Critical behavior in the La_0.6Sr_0.4Mn_0.8Fe_0.1Cr_0.1O₃ ceramics was studied using magnetization methods. Results show that the paramagnetic–ferromagnetic transition is of second order. Based on the critical behavior analysis using the Banerjee criterion and the Kouvel–Fisher method, we find the critical exponents: β=0.395±0.010, γ=1.402±0.010, and δ=5.208±0.007, for which the magnetic interaction is satisfied within the three-dimensional Heisenberg model. Results indicate the presence of short-range interactions. The magnetic entropy change (−ΔS_M) reached maximum values of 1.75, 1.45, 1.15, 0.8 and 0.43 J Kg⁻¹ K⁻¹ under a magnetic field variation of 5, 4, 3, 2 and 1 T, respectively. Nevertheless, these (−ΔS_M) values are much low for any potential application at this moment. The nature of this phenomenon is discussed in relation to the characteristics of the magnetic phase transition and critical exponents.     

A novel approach for strong S-Box generation algorithm design based on chaotic scaled Zhongtang system

Nonlinear Dynamics - Substitution Box (S-Box) is one of the most significant structures used to create an encryption which is strong and resistant against attacks in block encryption algorithms....     

Synthesis and proton conductivity studies of polystyrene‐based triazole functional polymer membranes

In this study, poly(vinylbenzylchloride) (PVBC) was produced by free‐radical polymerization of 4‐vinylbenzylchloride, and then it was functionalized with 3‐amino‐1,2,4‐triazole (ATri) and 1H‐1,2,4‐triazole (Tri). The composition of the polymers was verified by elemental analysis, and the structure was characterized by Fourier transform infrared and ¹³C‐nuclear magnetic resonance spectra. PVBC was modified by ATri with 68% and Tri with 50% yield. The polymers were doped with trifluoromethanesulfonic acid (TA) at various molar ratios, X = 0.5, 1, 2, and 3 with respect to aminotriazole and triazole units. Proton transfer from TA to the triazole rings was proved with Fourier transform infrared spectroscopy. Thermogravimetric analysis showed that the samples are thermally stable up to approximately 200 °C. Differential scanning calorimetry results illustrated the homogeneity of the materials. Under anhydrous conditions, PVBCATri3TA and PVBCTri3TA showed highest proton conductivity of 0.086 and 0.042 S/cm, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis,microwave‐promoted catalytic activity in Suzuki–Miyaura cross‐coupling reactions and antimicrobial properties of novel benzimidazole salts bearing trimethylsilyl group

A mixture of benzimidazole salts (2–7), Pd(OAc)₂ and K₂CO₃ in DMF–H₂O catalyzes the Suzuki–Miyaura cross‐coupling reactions promoted by microwave irradiation resulting in high yield within a short time. In particular, the yield of the Suzuki–Miyaura reactions with aryl bromides was found to be nearly quantitative. The synthesized benzimidazole salts (2–7) were identified by ¹H‐¹³C, NMR, IR spectroscopic methods and microanalysis. The molecular structure of 1 was determined by X‐ray crystallography. The antibacterial and antifungal activities of the novel benzimidazole derivatives (1–7) were also tested against standard strains. Copyright © 2011 John Wiley & Sons, Ltd.