第94届美国生态学会年会在新墨西哥州阿尔伯克基召开

<正>美国生态学会(ESA)第94届年会于2009年8月2日到7日在新墨西哥州阿尔伯克基(Albuquerque)的国际会议中心举行,3000多人参加此次会议。会议主题是"Ecological Knowledge and a Global Sustainable Society"。8月2日下午5时,美

抗生素产生菌的自身防卫机制研究

抗生素产生菌的自身防卫机制研究李明祺，吴文芳，张成刚（中国科学院沈阳应用生态研究所，１１００１５）抗生素是在微生物初级代谢过程中，由于特定的分支点受到阻碍而产生的物质，即所谓次级代谢物质。自然界中这种次级代谢物在微生物体内含量少，尚不至于对产生菌构成...

Synthesis, characterization, and electroluminescence of PPV copolymers containing electron and hole-transporting units

Three series of poly(phenylene vinylene) (PPV) derivatives containing hole-transporting triphenylamine derivatives [N-(4-octoxylphenyl)diphenylamine, N,N'-di(4-octyloxylphenyl)-N,N'-diphenyl-1,4-phenylenediamine, and N,N'-di(4-octoxylphenyl)-N,N'-diphenylbenzidine] (donor) and electron-transporting oxadiazole unit (2,5-diphenyl-1,3,4-oxadiazole) (acceptor) in the main chain were synthesized by improved Wittig copolymerization. The resulting donor-acceptor (D-A) polymers are readily soluble in common organic solvents, such as chloroform, dichloroethane, THF, and toluene.

Screening and Structural Characterization of alpha-Glucosidase Inhibitors from Hawthorn Leaf Flavonoids Extract by Ultrafiltration LC-DAD-MSn and SORI-CID FTICR MS

In vitro a-glucosidase inhibition assays and ultrafiltration liquid chromatography with photodiode array detection coupled to electrospray ionization tandem mass spectrometry (ultrafiltration LC-DAD-ESI-MSn) were combined to screen a-glucosidase inhibitors from hawthorn leaf flavonoids extract (HLFE). As a result, four compounds were identified as alpha-glucosidase inhibitors in the HLFE, and their structures were confirmed to be quercetin-3-O-rha-(1-4)-glc-rha and C-glycosylflavones (vitexin-2 ''-O-glucoside, vitexin-2 ''-O-rhamnoside and vitexin) by high-resolution sustained off resonance irradiation collision-induced dissociation (SORI-CID) data obtained by Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS).

A Fully Diarylmethylene-Bridged Triphenylamine Derivative as Novel Host for Highly Efficient Green Phosphorescent OLEDs

A fully diarylmethylene-bridged triphenylamine derivative is efficiently synthesized. It has an almost planar triphenylamine (TPA) skeleton and exhibits excellent thermal and morphological stability. Devices with the novel TPA derivative as host material and Ir(ppy)(3) as triplet emitter show a maximum current efficiency of 83.5 cd/A and a maximum power efficiency of 71.4 Im/W for green electrophosphorescence.

A simple method to prepare titania nanomaterials of core-shell structure, hollow nanospheres and mesoporous nanoparticles

A simple method to prepare titania nanomaterials of core-shell structure, hollow nanospheres and mesoporous nanoparticles has been developed. The core-shell nanostructures with NH4Cl as core and TiO2 center dot xH(2)O-NH4Cl as shell were prepared in nonaqueous system by the deposition on the surface of the aggregated NH4Cl crystals, which could be transformed into mesoporous anatase nanoparticles or hollow nanospheres by calcination at 500A degrees C or extraction with methanol, respectively. The hierarchical mesoporous nanostructures benefited the photocatalytic activities of the resultant titania nanomaterials, demonstrated by the UV light photodegradation of Methyl Orange.

Synthesis of a novel electroactive ABA triblock copolymer and its spontaneous self-assembly in water

An electroactive triblock copolymer of poly(ethylene glycol) (PEG) and aniline pentamer (AP), PEG-block-AP-block-PEG (PAP), was synthesized via polycondensation in the presence of N,N'-dicyclohexylcarbodiimide (DCC). The UV-vis spectra and cyclic-voltammograms (CV) spectra exhibited an excellent electroactivity of the triblock copolymer. The amphiphilic triblock copolymer self-assembles spontaneously into uniform micellar aggregates when the triblock copolymer was added directly to the aqueous solution. The size of the aggregates can be changed with the oxidation state of the AP segment in the PAP copolymer and the aggregates were pH-sensitive to the surrounding water solution, which provides a potential application in controlled drug release.

Crystallization and melting behaviors of PPC-BS/PVA blends

The isothermal crystallization and melting behaviors of poly(propylene carbonate) end-capped with benzenesulfonyl/poly (vinyl alcohol) (PPC-BS/PVA) blends over rich PVA composition range were first investigated by differential scanning calorimetry (DSC). PPS-BS/PVA interaction parameter, chi(12), calculated from equilibrium melting temperature depression was -0.44, revealing miscibility of PPC-BS with PVA in the melt and favorable interactions. The temperature dependence of crystallization rate constant at initial crystallization stage was analyzed using the modified Lauritzen-Hoffman expression. The chain width, a(0), the thickness of a monomolecular layer, b(0), the fold and lateral surface-free energies, sigma(e) and sigma, and the work of chain folding, q, for neat PVA were first reckoned to be 4.50 Angstrom, 4.78 Angstrom, 76.0 erg.cm(-2), and 4.70 kcal.mol(-1), respectively. The values of sigma(e) and q for PVA in PPC-BS/PVA blends exhibited a maximum in the neighborhood of 10/90 PPC-BS/PV, respectively.