Supramolecular Network Based on the Self‐Assembly of γ‐Cyclodextrin with Poly(ethylene glycol) and its Shape Memory Effect

A novel supramolecular network has been prepared based on the formation of inclusion complexes between γ‐cyclodextrin and poly(ethylene glycol), in which the PEG chains are interlocked by γ‐CD rings. This PEG/γ‐CD network exhibits good shape memory behavior because of the crosslinked structure. The crosslinked PEG/γ‐CD inclusion complexes and PEG crystallites account for the fixing phase and reversible phase, respectively. The characteristics of the materials have been investigated by ¹H NMR spectroscopy, XRD, DSC, DMA, viscosity tests, and swelling measurements.

     

4,5-二氢-1,2,4-三唑-5-硫酮席夫碱的合成和生物活性

以4-氨基-4,5-二氢-3-苯氧甲基-1氢-1,2,4-三唑-5-硫酮与取代苯甲醛为原料反应制得了9个新的三唑硫酮席夫碱类化合物,经IR、1H NMR和元素分析确定了各化合物结构。初步室内毒力测试结果表明该类化合物其具有较好的杀菌活性。     

Interdiffusion of Al-Ni system enhanced by ultrasonic vibration at ambient temperature

At ambient temperature, Al–1%Si wire of 25 μm diameter was bonded successfully onto the Au/Ni/Cu pad by ultrasonic wedge bonding technology. Physical process of the bond formation and the interface joining essence were investigated. It is found that the wire was softened by ultrasonic vibration, at the same time, pressure was loaded on the wire and plastic flow was generated in the bonding wire, which promoted the diffusion for Ni into Al. Ultrasonic vibration enhanced the interdiffusion that resulted from the inner defects such as dislocations, vacancies, voids and so on, which ascribed to short circuit diffusion.     

Tuning quadratic nonlinear photonic crystal fibers for zero group-velocity mismatch

We consider an index-guiding silica photonic crystal fiber with a triangular hole pattern and a periodically poled quadratic nonlinearity. By tuning the pitch and the relative hole size, second-harmonic generation with zero group-velocity mismatch is found for any fundamental wavelength above 780 nm. The nonlinear strength is optimized when the fundamental has maximum confinement in the core. The conversion bandwidth allows for femtosecond-pulse conversion, and 4%-180%W(-1)cm(-2) relative efficiencies were found.     

A practical and green approach towards synthesis of multisubstituted imidazoles using boric acid as efficient catalyst

An efficient one-pot, cyclocondensation of ammonium acetate, 1,2-diphenyl ethanedione, aromatic aldehyde or arylamine, and catalyzed by boric acid is achieved to form multisubstituted imidazole derivatives. Boric acid as green property is harmless to the environment and has improved the yield of multisubstituted imidazole derivatives. Moreover, we have tested the biological activities of imidazole derivatives by the four fungi. And the investigations showed most of imidazole derivatives have antifungal action on four fungus.     

Correlation between crystallinity and resistive switching behavior of sputtered WO3 thin films

The as-deposited WO₃ thin films were post-annealed at different temperatures (300 °C and 600 °C) in air to investigate a correlation between crystallinity and switching behavior of WO₃ thin films. Associating the results of XRD, FTIR, XPS and FESEM measurements, the annealing-caused crystallinity change contributes to the variation of the switching behaviors of the WO₃ thin films. The as-deposited WO₃ films with low crystalline structure are preferred for random Ag conducting path, resulting in large switching ratio but fluctuating I–V hysteresis, whereas the annealed WO₃ films with crystallized compact structure limits Ag conducting path, favoring the stable I–V hysteresis but small switching ratio. It is therefore concluded that electrochemical redox reaction-controlled resistance switching depends not only on electrode materials (inert and reactive electrodes) but also on crystallinity of host oxide.     

Anthraquinones from Morinda officinalis roots enhance adipocyte differentiation in 3T3-L1 cells

To search for anti-diabetic and insulin-sensitising natural products, the effect on adipocyte differentiation was investigated by assessing fat accumulation in 3T3-L1 preadipocytes using Oil Red O staining. Fractionation and separation of n-hexane and CHCl? fractions of Morinda officinalis (Rubiaceae) using several chromatographic methods led to the isolation of three anthraquinones, 1,2-dimethoxyanthraquinone (1), alizarin-2-methyl ether (2) and rubiadin-1-methyl ether (3). Among them, alizarin-2-methyl ether (2) showed the strongest enhancing activity, followed by rubiadin-1-methyl ether (3) and 1,2-dimethoxyanthraquinone (1). At a concentration of 100?μM, alizarin-2-methyl ether (2) enhanced adipocyte differentiation by up to 131% (compared to insulin-treated cells). Thus, these compounds could be beneficial in the treatment of diabetes.     

On the possible catalysis by single water molecules of gas-phase hydrogen abstraction reactions by OH radicals

The gas phase hydrogen abstraction reaction between OH and CY(2)XH, where X = H, F, OH, or NH(2) and Y = H, CH(3) or F, in the absence and presence of a single water molecule is investigated using both density function theory, B3LYP, and explicitly correlated coupled cluster theory, CCSD(T)-F12. We find that a single water molecule could have a catalytic effect at low temperatures possible in laboratory experiments, but does not seem to catalyze these reactions at 298 K, and will not play a role under relevant atmospheric conditions.     

New indoles from the roots of Brassica rapa ssp. campestris

Two new indoles, 2-C-β-D-glucopyranosyl-1-methoxyindole-3-acetonitrile (1) and 6-hydroxy-1-methylindole3-acetonitrile (2), along with two known indoles [caulilexin C (3) and arvelexin (4)], were isolated from turnip roots (Brassica rapa ssp. campestris L.). The structures of the compounds were established on the basis of NMR, FAB-MS, and IR spectroscopic data.