Zn(NO_3)_2·6H_2O/2,4,6-trichloro-1,3,5-triazine(TCT) a mild and selective system for nitration of phenols

<正>Certain phenols and naphthols were nitrated regioselectively with Zn(NO_3)_2·6H_2O/TCT in acetonitrile as solvent at room temperature and short reaction time in good yields.The reaction condition was mild.TCT is a cheap and commercially available reagent.It performed as an acid catalyst in this transformation.     

Monitoring of Anti Cancer Drug Letrozole by Fast Fourier Transform Continuous Cyclic Voltammetry at Gold Microelectrode

A continuous cyclic voltammetric study of letrozole at gold microelectrode was carried out. The drug in phosphate buffer (pH 2.0) is adsorbed at ?200 mV, giving rise to change in the current of well‐defined oxidation peak of gold in the flow injection system. The proposed detection method has some of advantages, the greatest of which are as follows: first, it is no more necessary to remove oxygen from the analyte solution and second, this is a very fast and appropriate technique for determination of the drug compound in a wide variety of chromatographic analysis methods. Signal‐to‐noise ratio has significantly increased by application of discrete Fast Fourier Transform (FFT) method, background subtraction and two‐dimensional integration of the electrode response over a selected potential range and time window. Also in this work some parameters such as sweep rate, eluent pH, and accumulation time and potential were optimized. The linear concentration range was of 1.0×10^?7?1.0×10^?10 mol/L (r=0.9975) with a limit of detection and quantitation 0.08 nmol/L and 0.15 nmol/L, respectively. The method has the requisite accuracy, sensitivity, precision and selectivity to assay letrozol in tablets. The influences of pH of eluent, accumulation potential, sweep rate, and accumulation time on the determination of the letrozol were considered.     

Mixed finite difference and Galerkin methods for solving Burgers equations using interpolating scaling functions

The current paper proposes a technique for the numerical solution of Burgers equations. The method is based on finite difference formula combined with the Galerkin method, which uses the interpolating scaling functions. Several test problems are given, and the numerical results are reported to show the accuracy and efficiency of the new algorithm. Copyright © 2013 John Wiley & Sons, Ltd.     

Robust optimization for interactive multiobjective programming with imprecise information applied to R&D project portfolio selection

A multiobjective binary integer programming model for R&D project portfolio selection with competing objectives is developed when problem coefficients in both objective functions and constraints are uncertain. Robust optimization is used in dealing with uncertainty while an interactive procedure is used in making tradeoffs among the multiple objectives. Robust nondominated solutions are generated by solving the linearized counterpart of the robust augmented weighted Tchebycheff programs. A decision maker’s most preferred solution is identified in the interactive robust weighted Tchebycheff procedure by progressively eliciting and incorporating the decision maker’s preference information into the solution process. An example is presented to illustrate the solution approach and performance. The developed approach can also be applied to general multiobjective mixed integer programming problems.     

Light‐Driven Reversible Alignment Switching of Liquid Crystals Enabled by Azo Thiol Grafted Gold Nanoparticles

Stimuli‐directed alignment control of liquid crystals (LCs) with desired molecular orientation is currently in the limelight for the development of smart functional materials and devices. Here, photoresponsive azo thiol (AzoSH) was grafted onto gold nanoparticles (GNPs). The resulting hybrid GNPs were able to homogeneously mix with a commercially available nematic LC host, as evidenced by Cryo‐TEM. Interestingly, the LC nanocomposites were found to undergo reversible alignment transition upon light irradiation as a consequence of the trans–cis photoisomerization of the azo groups on the GNP surface. LC molecules in either planar or bare glass cells were able to change their alignment to vertical upon UV irradiation, while the vertically aligned LC molecules returned to the planar or random orientation under visible irradiation. Neither the azo thiol molecules nor the unfunctionalized GNPs alone promoted the alignment of the LC molecules in the system upon light irradiation. The photoinduced vertical alignment without applied electric or magnetic field was very stable over time and with respect to temperature. Furthermore, an optically switchable device based on the photostimulated reversible alignment control of LCs was demonstrated.     

Solvent‐assisted prototyping of microfluidic and optofluidic microsystems in polymers

Due to their low‐cost and processing simplicity, polymers have made a substantial impact on everyday life and scientific discoveries. Such discoveries include the use of microanalysis and optical microsystems, which—albeit simpler to prototype than their inorganic counterparts—still require dedicated procedures at high temperatures and pressures. Here, recent developments in microsystem prototyping are highlighted, based on solvent‐assisted polymer stimulation. These developments—largely inspired by the earlier demonstration of solvent‐assisted micromolding (SAMIM) for nanoimprinting—enable micronscale imprinting, but also bonding to substrates and three‐dimensional chemical functionalization via strict benchtop procedures. These solvent‐assisted strategies are categorized into two groups: those based on solvent immersion and those based on complete polymer dissolution. Recent embodiments within each group are discussed and compared in performance. Solvent‐assisted prototyping further narrows the gap of processing complexity and costs between the PDMS elastomer and thermoplastic polymer microfluidics, and also enables novel architectures and thus new opportunities in microscale Life Sciences and Chemistry investigations. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1681–1686     

Superparamagnetic Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> Nanoparticles Decorated Multiwalled Carbon Nanotubes: Preparation via Cyclic Microwave Approach and Their Drug Release Behavior

Superparamagnetic Fe₃O₄ nanoparticles decorated multiwalled carbon nanotubes were synthesized by cyclic microwave method and the effect of different reaction parameters on the products were also investigated. The as synthesized products were characterized by XRD, TEM, SEM, EDS, FT-IR, VSM, and Uv–Vis spectroscopy. It was observed that precursors’ concentration ratio had great effect on the particle size and decorating quality. Also the effect of the other parameters including irradiation power and time on product size and uniformity of the product were also investigated. The best products with desired particle size distribution obtained when irradiation power and reaction time were 900 W and 6 min, respectively. Aspirin and acetaminophen were applied as a model drug and the drug release behavior of the composite was investigated. It was observed that the drug discharge was highly dependent to the pH and can be tuned by applying magnetic field.     

Immobilization of Keggin and Preyssler tungsten heteropolyacids on various functionalized silica

The Keggin and Preyssler tungsten heteropolyacids, H3PW12O40 and H15P5W30O110, have been immobilized on the inner surface of mesoporous MCM-41, fume silica and silica-gel by means of chemical bonding to aminosilane groups. The materials were characterized by FT-IR spectroscopy, low-angle XRD and BET surface area analysis. The tendencies of heteropolyacids adsorption in solution on functionalized silicas have been investigated by UV-vis. Among the functionalized silica materials, MCM-41 showed the largest amine to silica and the least heteropolyacid to silica ratios. The BET surface area revealed that in all three cases the surface area decreased after grafting amine group and anchoring of the HPAs clusters. Low-angle XRD analysis showed that by introducing HPA into functionalized MCM-41 the intensity of the main reflection decreased significantly.