Enhanced affinochromism of polydiacetylene monolayer in response to bacteria by incorporating US nano-crystallites

By incorporating bio-specific receptors, such as p-10,12-pentacosadiyne-1-N-(3,6,9-trioxaundecylamide)-alpha-D-mannopyranoside (MPDA), into 10,12-pentacosadiyonic acid (PDA) monolayer, the MPDA/PDA monolayer underwent affinochromatic transition in response to the bacteria binding to the receptor. Here, we described a new method to study the membrane/macromolececular interaction between Escherichia coli (E coli) and mannose and its relative affinochromism by modifying MPDA/PDA with CdS nano-crystallites (MPDA/PDA-CdS). CdS not only triggered the strong tropism of the bacteria but also reduced the rigidity of the MPDA/PDA backbone, resulting in the enhanced affinochromism. This discovery might be of significance in basic biophysical studies of membrane/macromolececular and designing novel biosensor.

In(OH)(3) and In2O3 nanorod bundles and spheres: Microemulsion-mediated hydrothermal synthesis and luminescence properties

Indium hydroxide, In(OH)(3), nano-microstructures with two kinds of morphology, nanorod bundles (around 500 nm in length and 200 nm in diameter) and caddice spherelike agglomerates (around 750 - 1000 nm in diameter), were successfully prepared by the cetyltrimethylammonium bromide (CTAB)/water/cyclohexane/n-pentanol microemulsion-mediated hydrothermal process. Calcination of the In(OH)(3) crystals with different morphologies (nanorod bundles and spheres) at 600 degrees C in air yielded In2O3 crystals with the same morphology. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and photoluminescence (PL) spectra as well as kinetic decays were used to characterize the samples. The pH values of microemulsion play an important role in the morphological control of the as-formed In(OH)(3) nano-microstructures from the hydrothermal process. The formation mechanisms for the In( OH) 3 nano- microstructures have been proposed on an aggregation mechanism. In2O3 nanorod bundles and spheres show a similar blue emission peaking around 416 and 439 nm under the 383-nm UV excitation, which is mainly attributed to the oxygen vacancies in the In2O3 nano-microstructures.

A solvothermal route to size- and shape-controlled CdSe and CdTe nanocrystals

The size- and shape-controlled CdSe and CdTe nanocrystals, which exhibit obvious quantum confinement effect, have been synthesized by a solvothermal route. It is found that initial precursor concentrations are key factors in controlling the shape of the resulting nanocrystals. Moreover, the obtained nanocrystals are all of zinc blende structure, regardless of their sizes and shapes. A possible mechanism for the formation and growth of the nanocrystals is put forward. It is inferred that the adhesion and subsequent recrystallization of nanocrystals with an assistance of remaining monomers should be a major reason for formation and growth of the elongated nanocrystals.

Studies on the non-covalent complexes between oleanolic acid and cyclodextrins using electrospray ionization tandem mass spectrometry

Non-covalent inclusion complexes formed between an anti-inflammatory drug, oleanolic acid (OA), and alpha-, beta- and gamma-cyclodextrins (CDs) were investigated by means of solubility studies and electrospray ionization tandem mass spectrometry (ESI-MSn). The order of calculated association constants (K-1:1) of complexes between OA and different CDs in solution is in good agreement with the order of their relative peak intensities and the relative CID energies of the complexes under the same ESI-MSn conditions. These results indicate a direct correlation between the behaviors of solution- and gas-phase complexes. ESI-MS can thus be used to evaluate solution-phase non-covalent complexes successfully. The experimental results show that the most stable 1:1 inclusion complexes between three CDs and OA can be formed, but 2:1 CD-OA complexes can be formed with beta- and gamma-CDs. Multi-component complexes of alpha-CD-OA-beta-CD (1:1:1), alpha-CD-OA-gamma-CD (1:1:1) and beta-CD-OA-gamma-CD (1:1:1) were found in equimolar CD mixtures with excess OA. The formation of 2:1 and multi-component 1:1:1 non-covalent CD-OA complexes indicates that beta- and gamma-CD are able to form sandwich-type inclusion non-covalent complexes with OA. The above results can be partly supported by the relative sizes of OA and CD cavities by molecular modeling calculations.

UV-Vis and surface photovoltage spectra of Fe2O3/polystyrene composite microspheres

Fe2O3 sol with the particle diameter of 3-5 nm was flocculated by the addition of SDS, and the flocculate formed was redispersed by the further addition of that surfactant. Thus the surfactant bilayer was formed on the surface of Fe2O3. The emulsion polymerization of styrene (St) adsolubilized oil the surfactant adsorbed bilayer was carried out by initiator potassium persulfate (KPS). The UV-Vis and surface photovoltage spectra (SPS) indicate that the Fe2O3 particles were encapsulated in polystyrene(PSt) successfully.

A novel method for preparing ordered SnO2/TiO2 alternate nanoparticulate films

A novel method using LB films as precursors to prepare pure inorganic ordered film with periodic structure was developed. Surfactant-stabilized SnO2 nanoparticulate organosols and TiO2 nanoparticulate organosols were prepared and used as spreading solutions. Using LB technique, the good film-forming ability of the surfactant-stabilized SnO2 nanoparticles and TiO2 nanoparticles was confirmed by the determination of the pi -A isotherms. The surfactant-stabilized SnO2 and TiO2 nanoparticulate monolayers were fabricated on the water surface and then were transferred to solid substrates (CaF2, quartz, silicon, and so on) alternately, layer-by-layer. Then the as-deposited alternate LB film was treated at different temperatures. The as-deposited alternate LB film and the treated film were characterized by Fourier transform infrared spectroscopy, UV visible spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results indicate that our method was successful. The as-deposited alternate LB film formed a periodic structure with a long spacing of 6.5 nm that was composed of SnO2 nanoparticles, TiO2 nanoparticles, and arachidic acid. The treated film composed of SnO2 nanoparticles and TiO2 nanoparticles formed a pure inorganic periodic structure with an ordered distance of 5.4 nm. (C) 2001 Academic Press.

Surface photovoltage spectra and photoelectrochemical properties of semiconductor-sensitized nanostructured TiO2 electrodes

Three kinds of TiO2 nanostructured thin films and their CdS-sensitized films, consisting of different sizes of TiO2 nanoparticles prepared with different methods, have been investigated. The surface photovoltage spectra (SPS) measurements indicate that the density of surface states on TiO2 is likely dependent upon the details of prepared methods. TiO2 particles prepared from basic sol have more surface states than that prepared from acidic sol. When the TiO2 thin films prepared using the TiO2 sols were sensitized by CdS particles, the SPS responses relative to the surface states on TiO2 from 350 to 800 nm were decreased. The photoelectrochemical properties of nanostructured TiO2 electrodes suggest that the fewer the surface states and the smaller the particle sizes of TiO2, the larger the photocurrent response. For CdS sensitized TiO2 thin film electrode, it is shown that the semiconductor sensitization is an efficient way to decrease the influence of surface states on the charge separation, and can improve the intensity of photocurrent response. (C) 2001 Elsevier Science B.V. All rights reserved.

Cyclodextrin-catalyzed oxidation of glutathione in solution and in an ion trap

Incubated solutions containing glutathione (GSH) and alpha- or beta-cyclodextrins (CDs) were analyzed using electrospray mass spectrometry and tandem mass spectrometry, The results suggest that both CDs can catalyze oxidation of GSH to the oxidized glutathione (GSSG). The collision-induced dissociation (CID) of the 1:1 and 1:2 (CD/GSH) and 1:1 (CD/GSSG) complexes reveals the strong interactions of the CDs with the peptides tested. The 1:2 (CD/GSH) complex is considered to be the oxidation reaction intermediate, which indicates that the three-dimensional structure of the complexed two GSHs in CD complexes Is different from that of the proton-bound GSH dimer, The oxidation product, GSSG, Is also observed in the CID spectrum of the singly charged 1:1 (CD/GSH) complex, suggesting that a complex ion-complex ion reaction occurs by forming a doubly charged complex dimer, as a result of the ability of ion trap to accumulate and activate ions. The observations indicate that ion trap mass spectrometry can be used to explore cyclodextrin-catalyzed reactions and to carry out complex gaseous chemistry research. Copyright (C) 1999 John Wiley & Sons, Ltd.

化学溶液法和超声化学法制备硫化镉薄膜

通过对用化学溶液法制备硫化镉薄膜的微观生长过程和机理的研究，建立一种在溶液中进行超声波化学制备硫化镉半导体薄膜的方法.用扫描电子显微镜对化学溶液法和超声化学法沉积的硫化镉薄膜的生长过程进行跟踪观察. 讨论了硫化镉薄膜的UV可见光谱

Multilayer assemblies of colloidal ZnS doped with silver and polyelectrolytes based on electrostatic interaction

Multilayer assemblies of silver doped ZnS colloid and polycation were fabricated by a self-assembly technique exploiting electrostatic interaction. UV/Vis spectra showed the uniform deposition process and X-ray photoemission spectroscopy (XPS) confirmed the coexistence of silver. It was found that the emission spectra of the silver doped ZnS colloid red-shifted to 528 nm comparing with undoped ZnS colloid. However, the most important finding was that the luminescence intensity of doped ZnS assembled in films was much stronger than that of undoped ZnS in films and that of doped ZnS in the spin-casting film. The mechanism of the enhancement luminescence was discussed. (C) 1998 Elsevier Science S.A. All rights reserved.

Self-assembly of the pre-formed inclusion complexes between cyclodextrins and alkanethiols on gold electrodes

A new kind of self-assembled monolayer (SAM) formed in aqueous solution through the pre-formed inclusion complexes (abbreviated CD . C-n) between alpha-, beta-cyclodextrins (CDs) and alkanethiols (CH3(CH2)(n-1)SH, n = 10, 14 and 18) was prepared successfully on gold electrodes. High-resolution H-1 NMR was used to confirm the formation of CD . C-n. X-ray photoelectron spectroscopy, cyclic voltammetry and chronoamperometry were used to characterize the resulting SAMs (denoted as M-CD . Cn). It was found that M-CD . Cn were more stable against repeated potential cycling in 0.5 M H2SO4 than SAMs of CH3(CH2)(n-1)SH (denoted as M-Cn), with a relative sequence of Mbeta-CD . Cn > Malpha-CD . Cn > M-Cn. In addition, an order of blocking the electron transfer between gold electrodes and redox couples (both Fe(CN)(6)(3-) and Ru(NH3)(6)(3+)) in solution, M-CD . C10 > M-CD . C14 > M-CD . C18, was observed. A plausible explanation is provided to elucidate some of the observations. (C) 1997 Elsevier Science S.A.

裂解色谱法研究环化顺-1,4-丁二烯-异戊二烯无规共聚物

如同顺-1,4-聚丁二烯(PBd)和聚异戊二烯(PIP),在一定的催化条件下,顺-1,4-丁二烯-异戊二烯无规共聚物(PBI,简称丁戊无规共聚物)可生成环化顺-1,4-丁戊无规共聚物(CP-BI)。作者曾报道用裂解色谱法表征环化顺-1,4-聚丁二烯(CPBd),本文对不同组成的CPBI和PBI进行了裂解色谱比较研究。 表1所列试样由实验室合成。用CDS pyro-probe 190型裂解器,SP-2305E型气相色谱仪,FID。裂解温度700℃,裂解时间5秒,色谱柱4mm×3m不锈钢柱,填充20%SE-30固定相(101白色担体),柱温106℃,载气氮气40mL/min。试样量约30μg,放于石英管内,后者再插入

聚萘的裂解色谱研究

聚萘是一种新型的高分子,掺杂后具有导电性能,是一种导电聚合物。本文用裂解色谱法(PGC)研究了它的热裂解行为,分离鉴定了主要和特征裂解产物,并在此基础上,对其分子链结构和裂解机理进行了讨论。 实验部分 (一)样品 聚萘(PN):由本实验室直接从萘合成,使用前在100℃下真空热处理48小时加以提纯。 (二)仪器和实验条件 裂解器:美同CDS Py-ro-Probe 190型(丝式);裂解温度300-800℃,裂解时间5s。色谱仪:北分厂-2305E型,氢火焰离子化检

具有多层结构的新型蒸发源

本文报道了一种具有多层结构的新型蒸发源,指出了它的特点和用该蒸发源制备CdS太阳电池的结果。