Enhanced targeted energy transfer for adaptive vibration suppression of pipes conveying fluid

Nonlinear Dynamics - In this paper, a nonlinear energy sink and a negative stiffness element are integrated for achieving enhanced, passive, and adaptive vibration suppression for a pipe conveying...     

Synthesis of Mg–Al–carbonate layered double hydroxide by an atom-economic reaction

A clean method for preparing layered double hydroxides (LDHs) has been developed, featured by using the hydroxides of two different metals as starting materials by atom-economic reaction. The reactions were carried out under hydrothermal conditions in either a high pressure autoclave or a microwave digester. The compositions, structural parameters and thermal behavior of the resulting LDHs are very similar to those of materials produced by using the separate nucleation and aging steps (SNAS) method. The major advantage of the new method is that no by-product is produced, so that filtration and washing processes are unnecessary. The consequent reduction in water consumption is beneficial to the environment.     

The dynamic complexity of a three species food chain model

In this paper, a three-species food chain model is analytically investigated on theories of ecology and using numerical simulation. Bifurcation diagrams are obtained for biologically feasible parameters. The results show that the system exhibits rich complexity features such as stable, periodic and chaotic dynamics.     

Novel designed polymer–acyclovir conjugates with linker‐controlled drug release and hepatoma cell targeting

To develop designed polymer–drug conjugates, where the rate of drug liberation and hepatoma cell targeting function could be rationally and widely controlled, we facilely synthesized a series of novel, galactose‐functionalized polymer–acyclovir conjugates with different linkers and first reported the effect of the linker structure including the type of acyclovir‐linked bond (an ester bond or an amide bond) and relative length of the linker between acyclovir and the polymer main chain on release rate and targeting ability of conjugates. In vitro release studies showed that the cumulative released acyclovir from these polymer–acyclovir conjugates was between 24 and 65% in pH 1.2 glycine solution after 7 days. The ester bond more easily underwent hydrolysis than the amide bond. The longer the relative linker length was, the faster the acyclovir was released. The cell recognition experiments visualized using confocal laser scanning microscopy exhibited that the resultant galactose‐functionalized polymer–acyclovir conjugates had evident targeting to hepG2 cells, and targeting ability was also in connection with the relative length of linker. By choosing appropriate linker, cellular internalization of acyclovir could be well achieved. We consider these results to be helpful for the design of multifunctional polymeric prodrugs, in which the required release rate and targeting ability could be rationally controlled by predetermined molecular architecture. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 117–126, 2008     

Liquid phase epitaxial growth and optical property of flower-like ZnO nanosheets on Zinc foil

Large scale flower-like ZnO nanosheets have been synthesized on Zinc foil by a simple hydrothermal method. Their morphology and microstructures were characterized and analyzed by X-ray spectroscopy (XRD), field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HRTEM). The as-synthesized flower-like nanosheets are hexagonal phase single crystal with 200-300 nm in width, 50 nm in thickness. The growth process follows the liquid phase epitaxial growth mechanism. In this approach, the ZnO buffer is used as substrate for the growth of flower-like ZnO nanosheets. The growth direction of the nanosheets is the preferential [0 0 0 1] growth direction of ZnO. The photoluminescence spectrum of the sample exhibits only a sharp and strong UV emission centered at 386 nm, which indicates that the flower-like ZnO nanosheets on Zn foil are of good optical property.     

Error estimate of eigenvalues of perturbed second-order discrete Sturm–Liouville problems

This paper is concerned with eigenvalues of perturbed second-order vector discrete Sturm–Liouville problems. By some variational properties of eigenvalues of discrete Sturm–Liouville problems, error estimates of eigenvalues of perturbed problems, sufficiently close to a given Sturm–Liouville problem, are given under a certain non-singularity condition. Perturbations of the coefficient functions of the difference equation, the weight function, and the coefficients of the boundary condition are all considered. This, together with higher-dimension involved, results in a certain complexity of the problem and difficulty of study. As a direct consequence, continuous dependence of eigenvalues on problems is obtained under the non-singularity condition. In addition, an example is presented to illustrate the necessity of the non-singularity condition.     

A new luminol derivative as a fluorescent probe for trace analysis of copper(II)

Microchimica Acta - A new luminol derivative has been synthesized and its fluorescence has been studied. The luminol derivative emits at 460 nm in pH 10.0 phosphate buffer which is...     

Direct catalytic oxidation of cyclohexene to 1, 2-cyclohexanediol by aqueous hydrogen peroxide under solvent-free condition

Cyclohexene can be oxidized directly to 1, 2-cyclohexanediol with aqueous hydrogen peroxide under solvent-free condition using a heteropolyphosphatotungstate catalyst. And an isolated yield of 54% was obtained in this catalytic system.     

Synthesis of morphological ZnO particles by a facile solution-based chemical method

In this study, a facile solution-based chemical method has been developed to produce ZnO particles in the presence of triethanolamine (TEA) and NaOH. In this novel method, TEA acted as complexing reagents, and NaOH contributed to the transformation of ZnO precursor (Zn–TEA complex) into ZnO particles. The core of this new strategy is to transform Zn–TEA complex into morphological ZnO particles directly by a facile solution method. The results from transmission electron microscope (TEM) and field emission scanning electron microscope (FESEM) analysis revealed that the morphologies of the as-prepared ZnO samples evolved from slices to quasi-spheres by increasing the amount of TEA. X-ray diffraction (XRD), Raman and room-temperature photoluminescence (PL) tests showed that these ZnO samples had wurtzite structures. A reasonable mechanism for the transformation of Zn–TEA complex into morphological ZnO particles was supplied.