Local and global synchronization in general complex dynamical networks with delay coupling

Local and global synchronization of complex dynamical networks are studied in this paper. Some simple yet generic criteria ensuring delay-independent and delay-dependent synchronization are derived in terms of linear matrix inequalities (LMIs), which can be verified easily via interior-point algorithm. The assumption that the coupling configuration matrix is symmetric and irreducible, which is frequently used in other literatures, is removed. A network with a fixed delay and a special coupling scheme is given as an example to illustrate the theoretical results and the effectiveness of the proposed synchronization scheme.     

Degradation induced variation of LC transition of poly(n-undecyl isocyanate)

The first-order thermal transitions including side-chain melting, crystal-LC, biphasic chimney-like, and isotropic transitions of poly(n-undecyl isocyanate) (PUDIC) were investigated by varying its thermal history. After annealing at 140 °C for different periods of time, it leads to different degrees of backbiting degradation into n-undecyl isocyanurate trimer which behaves as a solvent for the rest non-degraded/rigid PUDIC to change into a lyotropic LC from thermotropic transition. Based on the degree of degradation, various amounts of trimers are present and the PUDIC demonstrates different types of thermal transitions found in DSC thermograms due to the variation of the non-degraded PUDIC concentration in solvent trimers. Finally, a phase diagram includes all types of crystallines, LC, and isotropic regions can be drawn according to the DSC thermograms.     

Infrared stealth and anticorrosion performances of organically modified silicate‐NiZn ferrite/polyaniline hybrid coatings

Hybrid coatings based on organically modified silicate‐Ni_0.5Zn_0.5Fe₂O₄/polyaniline were synthesized through a sol–gel technique with different NiZn ferrite/polyaniline weight ratio (1/1, 1/2, 1/5). These hybrid films were deposited via spin coating onto an aluminum alloy to improve the corrosion protection and to act as infrared stealth coatings. The effects induced by the NiZn ferrite/polyaniline hybrids on the chain dynamic, ferromagnetic behavior, infrared stealth, and anticorrosion performances of the coated samples were investigated. The rotating‐frame spin‐lattice relaxation times and scale of the spin‐diffusion path length indicated that the configuration of the hybrid films was highly cross‐linked and dense. The thermal extinction of the hybrid coatings increased with the increase in the polyaniline content. Potentio‐dynamic and salt‐spray analysis revealed that the hybrid films provided an exceptional barrier and corrosion protection in comparison with untreated aluminum alloy substrates. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 926–935, 2008     

Temperature driven morphological changes of hydrothermally prepared copper oxide nanoparticles

The size and shape of nanocrystals have a strong effect on the optical, electrical and catalytic properties. Therefore, controlling the size, shape and structure of nanocrystals is technically important. The controlled synthesis of CuO nanostructures was achieved using a hydrothermal process by simply controlling the precipitation reaction temperature between copper nitrate trihydrate and sodium hydroxide. The Scanning Electron Microscopy (SEM), EDS, XRD, and FTIR analysis revealed that the synthesized product at 200 °C is of pure copper oxide particles. From Scherrer formula, the prepared CuO particles varied approximately 3–7 nm in size simply by varying the reaction temperature. The synthesized particles exhibited a regular flake like morphology and had a uniform size distribution. The morphology and size depend on the reaction conditions. Copyright © 2008 John Wiley & Sons, Ltd.     

Adhesion comparison of human bone marrow stem cells on a gradient wettable surface prepared by corona treatment

Corona discharge treatment was applied to modify the surface of polyethylene (PE). The wettability of PE surface was gradually increased by power increase of a corona treatment along the PE length, indicating that the hydrophilicity of PE surface increased gradually. The adhesion and proliferation behavior of human bone marrow stem cells (hBMSCs) on the gradient PE surface was evaluated. We found that hBMSCs were adhered to and proliferated on better highly hydrophilic than hydrophobic surfaces. The plot of proliferation rate vs. the water contact angles was parabolic. These results indicate that surface wettability plays an important role in the cell attachment and proliferation.     

HPLC determination of irbesartan in human plasma: its application to pharmacokinetic studies

A simple and rapid HPLC method using fluorescence detection was developed for determination of irbesartan in human plasma. Sample preparation was accomplished through a simple deproteinization procedure with 0.4 mL of acetonitrile containing 800 ng/mL of losartan (internal standard), and to a 0.1 mL plasma sample. Chromatographic separation was performed on a Zorbax Xclipse XDB C₁₈ column (150 × 4.6 mm, i.d., 5 µm) at 40°C. An isocratic mobile phase, acetonitrile:0.1% formic acid (37:63, v/v), was run at a flow‐rate of 1.0 mL/min, and the column eluent was monitored using a fluorescence detector set at excitation and emission wavelengths of 250 and 370 nm, respectively. The retention times of irbesartan and losartan were 4.4 and 5.9 min, respectively. This assay was linear over a concentration range of 10–5000 ng/mL with a lower limit of quantification of 10 ng/mL. The coefficient of variation for this assay precision was less than 8.48%, and the accuracy exceeded 94.4%. The mean relative recoveries of irbesartan and losartan were 98.4 and 99.1%, respectively. This method was successfully applied for pharmacokinetic study after oral administration of irbesartan (300 mg) to 23 Korean healthy male volunteers. Copyright © 2009 John Wiley & Sons, Ltd.     

Blue luminescence of nanocrystalline PbWO4 phosphor synthesized via a citrate complex route assisted by microwave irradiation

Nanocrystalline PbWO₄ phosphor powders, which have scheelite structure, were successfully synthesized at low temperatures via a modified citrate complex route assisted by microwave irradiation. Crystallization of the PbWO₄ precursor were detected at 400 °C, and entirely completed at 500 °C. Prepared PbWO₄ nanocrystallites showed primarily spherical and disperse morphology. The average crystallite sizes were between 18 and 29 nm, showing an ordinary tendency to increase with temperature. The nanocrytalline PbWO₄ phosphor powders exhibited spread-eagle shape of blue luminescence. Especially the PbWO₄ phosphor powders prepared at 600 °C showed the strongest luminescent intensity, which was due to the higher crystallinity and homogeneous particle morphology.     

On the Growth and Fixed Points of Solutions of Second Order Differential Equations with Meromorphic Coefficients

In this paper, we investigate the growth and fixed points of solutions and their 1st, 2nd derivatives, differential polynomial of second order linear differential equations with meromorphic coefficients, and obtain that the exponents of convergence of these fixed points are all equal to the order of growth.