HELIX-INDUCED ASYMMETRIC POLYMERIZATION

Asymmetric polymerization could be induced by an already formed optically active living prepolymer with one-handed screw sense helix conformation. The usually formed anionic active centre on the prepolymer could be changed to cationic, radical and even of Ziegler-Natta type. These living prepolymers with various kinds of active centre were all effective to induce a consequent asymmetric polymerization of a monomer which may be other than that in the prepolymer, to afford an optically active helical chain with the same screw sense as that of the prepolymer. Eight monomers have been used in the work. Optical rotation, circular dichroism and gelpermeation chromatography have been taken to prove the helix-induced asymmetric polymerization.

ELECTROCHEMICAL-BEHAVIOR OF N-METHYL-N'-HEXADECYLVIOLOGEN MONOLAYERS ON SILVER ELECTRODES - EFFECTS OF COUNTERIONS

N-Methyl-N'-hexadecylviologen (C16MV) has been the subject of several electrochemical and spectroelectrochemical studies which characterized the species present in various redox states for C16MV monolayers on silver electrode surfaces. Both self-assembled monolayers (SA) and Langmuir-Blodgett (LB) transferred systems have been studied. These indicated inconsistencies regarding the presence or absence of splitting of the first reduction peak in its cyclic voltammogram (CV). The present study demonstrates the important influence of the specific anionic species present in the supporting electrolyte. Splitting may or may not take place, depending on the size and relative strength of the adsorption of specific anions contributed by the supporting electrolyte. Small, strongly adsorbing anions such as iodide produced peak splitting in the CV of C16MV monolayers; bulky but weakly adsorbing anions such as perchlorate may disrupt the ordered structure of monolayers but produce no splitting. Ancillary data provided by surface enhanced Raman spectroscopy (SERS) was consistent with the electrochemical measurements.

INVESTIGATION OF CETYLPYRIDINIUM BROMIDE ADSORPTION AT A GLASSY-CARBON ELECTRODE SURFACE BY SPECTROELECTROCHEMISTRY WITH A LONG OPTICAL-PATH LENGTH THIN-LAYER CELL

The adsorption of cationic surfactant cetylpyridinium bromide (CPB) on a glassy carbon (GC) electrode surface has been studied by spectroelectrochemistry with a long optical path length thin-layer cell (LOPTLC) for the first time. A fine adsorption isotherm of CPB molecules from an aqueous solution containing 0.10 M KBr has been obtained over the range of (1.00-8.00) x 10(-5) M. From theoretical calculation and experimental data, adsorption of CPB on the GC electrode surface shows four distinct orientations and three large orientation transitions. Compared with the ordinary isotherm, the differential isotherm is more characteristic and would be suitable for the study of orientation transitions of organic compounds. With a theoretical treatment of the adsorption isotherm, four orientations of adsorbed CPB on a GC electrode surface coincide with the Frumkin-Langmuir type. From adsorption parameters the Frumkin-Langmuir equations, the adsorption free energy and, therefore, the equilibrium constants of orientation transitions of the CPB molecule can be obtained.

Extraction behavior of Mo and W as homologs of Sg with α-benzoinoxime

Solvent extraction of molybdenum and tungsten as homologues of Sg with a-benzoinoxime from HCl solutions has been investigated. The extraction equilibration was achieved at 20s for Mo and W. Molybdenum was almost quantitatively extracted from 0.001 to 4M HCl solutions, and the extraction yields decreased at higher and lower acid concentrations due to the formation of anionic oxychloride complex and anionic species MO42-, respectively. The extraction yield of W was lower than that of Mo during the whole range of acid concentration. The composition of the extracted species was determined by using the slope method in present experiment. The elemental analysis, IR and 1H NMR spectra of the extracted species suggest that the extracted complex contain one MoO22+or WO22+ groups bonded with two a-benzoinoxime molecules.

Comparative researches on effects of sodium dodecylbenzene sulfonate and sodium dodecyl sulfate upon Lateolabrax japonicus biomarker system

Fish Lateolabrax japonicus were exposed to anion surfactant sodium dodecylbenzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS) at 1 mg/l, respectively, for 6, 12 and 18 d, with one control group. Liver antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH) and glutathione S-transferase (GST) were determined; brain acetylcholinesterase (AChE) and liver inducible nitric oxide synthase (NOS) activities were also measured. The results of the study indicated that these parameters made different, sometimes, adverse responses to SDBS and SDS exposure, such as the activity of NOS can be inhibited by SDBS and induced by SDS, the different physico-chemical characteristics of SDBS and SDS should be responsible for their effects on enzyme activities. (c) 2005 Elsevier B.V. All rights reserved.

Screening of surfactants for harmful algal blooms mitigation

Screening experiments were conducted in order to find promising synthetic surfactants for harmful algal blooms (HABs) mitigation. The chemically synthesized surfactant cocamidopropyl betaine (CAPB) showed characteristics of relatively high inhibition efficiency, high biodegradability and low cost. The motility inhibition ratios of 10 mg/L CAPB on Cochlodinium polykrikoides and Alexandrium tamarense were about 60% after 5 min. The biodegradation test indicated that the half-life of CAPB in seawater was shorter than one day and 90% was biodegraded after five days under the initial concentration of 100 mg/L at 25degreesC. Further cell lysis experiments revealed the selective lysis effect of CAPB on different HAB organisms. More than 90% of C. polykrikoides lysed at the concentration of 10 mg/L CAPB after 24 h and at 15 mg/L CAPB after 4 h, whereas the lysis effect of CAPB on A. tamarense was slight, no more than 10% after 2 h interaction with 50 mg/L CAPB. This research provided preliminary data for CAPB as a candidate in harmful algal blooms mitigation and pointed out unresolved problems for its practical application in the meantime. (C) 2003 Elsevier Ltd. All rights reserved.

Effects of sodium dodecylbenzene sulfonate and sodium dodecyl sulfate on the Mytilus galloprovincialis biomarker system

The effects of in vivo exposure of Mytilus galloprovincialis to two anionic surfactants (SDBS and SDS) on the molecular biomarker system were studied. After continuous exposure for 72 days, activities/levels of GST, GPx and GSH were significantly higher than in corresponding control groups following exposure to 3.000 mg/L SDS and SDBS. Activities of SOD and CAT were significantly inhibited by experimental SDBS (except CAT in 0.100 mg/L group), but not by SDS. Statistical analysis of enzyme activities/levels suggested that there were significant positive relationships between GST and GPx, and negative relationships were found between GSH and CAT, GSH and SOD. Amplified fragment length polymorphism (AFLP) results showed that a greater genotoxic effect was observed for SDBS than for SDS. Based on the above results, the biomarker system of mussels can be affected by the two anionic surfactants (>= 3.000 mg/L); it was more easily affected by SDBS than by SDS. Crown Copyright (C) 2009 Published by Elsevier Inc. All rights reserved.

Response of integrated biomarkers of fish (Lateolabrax japonicus) exposed to benzo[a]pyrene and sodium dodecylbenzene sulfonate

Fish Lateolabrax japonicus were exposed to 0.1 and 1 mg/L of anion surfactant sodium dodecylbenzene sulfonate (SDBS) and to 2 and 20 mu g/L of benzo[a]pyrene (B[a]P) for 6, 12, and 18 days, with control and solvent control groups. Liver antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH), and glutathione S-transferase (GST), were determined; brain acetyleholinesterase (AChE) and liver inducible nitric oxide synthase (iNOS) activities were also measured. The results indicated that (1) L. japonicus avoided oxidative damage through antioxidant systems; (2) SOD, GPx, and GSH were induced, and GST was inhibited and then induced by B[a]P exposure; and (3) CAT, GPx, and AChE were induced while NOS was inhibited, and GST was induced and then inhibited by SDBS stress in experimental period. (c) 2005 Elsevier Inc. All rights reserved.

Preparation of Dendritic Copper Nanostructures and Their Characterization for Electroreduction

Dendritic copper nanostructures of different morphologies were synthesized by a surfactant-free electrochemical method. Single crystal nature of the nanostructures was revealed from their X-ray diffraction and electron diffraction patterns. Mechanism of dendrite formation was discussed from thermodynamic aspects using the concept of supersaturation. Supersaturation of the copper metal reduced on the surface of the electrode was the crucial factor for the generation of different morphologies. Effects of applied potential, temperature, and the solution concentration on the supersaturation were studied. The NO3- and H2O2 electroreduction ability of the dendritic materials was tested. Use of copper dendrite-modified electrode as NO3- sensor was demonstrated.

油藏数值模拟中的网格粗化和细化技术研究

The grid is a foundation of reservoir description and reservoir simulation. The scale of grid size is vital influence for the precision of reservoir simulation the gridding of reservoir parameters require reasonable interpolation method with computing quickly and accurately. The improved distant weighted interpolation method has many properties, such as logical data points selection, exact interpolation, less calculation and simply programming, and its application can improve the precision of reservoir description and reservoir simulation. The Fractal geologic statistics describes scientifically the distribution law of various geological properties in reservoir. The Fractal interpolation method is applied in grid interpolation of reservoir parameters, and the result more accorded with the geological property and configuration of reservoir, and improved the rationality and quality of interpolation calculation. Incorporating the improved distant weighted interpolation method with Fractal interpolation method during mathematical model of grid-upscaling and grid-downscaling, the softwares of GROUGH(grid-upscaling) and GFINE (grid-downscaling) were developed aiming at the questions of grid-upscaling and grid-downscaling in reservoir description and reservoir simulation. The softwares of GROUGH and GFINE initial applied in the research of fined and large-scale reservoir simulation. It obtained fined distribution of remaining oil applying grid-upscaling and grid-downscaling technique in fined reservoir simulation of Es21-2 Shengtuo oilfield, and provided strongly and scientific basis for integral and comprehensive adjustment. It's a giant tertiary oil recovery pilot area in the alkaline/surfactant/polymer flooding pilot area of west district of Gudao oilfield, and first realized fined reservoir simulation of chemical flooding using grid-upscaling and grid-downscaling technique. It has wide applied foreground and significant research value aiming at the technique of grid-upscaling and grid-downscaling in reservoir description and reservoir simulation.

Synthesis and characterization of manganese-modified MCM-41

Manganese-modified mesoporous MCM-41 molecular sieves were synthesized at the absence of alkaline metal ions under mild alkaline condition using cetylpyridinium bromide surfactant as a template, and characterized with X-ray diffraction, N-2 adsorption, transmission electron microscopy, electron spin resonance (ESR), and nuclear magnetic resonance (NMR) spectroscopies. The synthesized MnMCM-41 has a high pore volume of 1.30 cm(3) g(-1) with a corresponding surface area of 1510 m(2) g(-1). The ESR and Si-29 MAS NMR spectra revealed the presence of framework manganese ions in either the as-synthesized or calcined forms. (C) 2002 Elsevier Science B.V. All rights reserved.

Ultrasonic synthesis of silica-alumina nanomaterials with controlled mesopore distribution without using surfactants

A novel sol-gel process has been developed for the synthesis of amorphous silica-aluminas with controlled mesopore distribution without the use of organic templating agents, e.g., surfactant molecules. Ultrasonic treatment during the synthesis enables production of precursor sols with narrow particle size distribution. Atomic force microscopy analysis shows that these sol particles are spherical in shape with a narrow size distribution (i.e., 13-25 nm) and their aggregation during the gelation creates clusters containing similar sized interparticle mesopores. A nitrogen physiadsorption study indicates that the mesoporous materials containing different Si/Al ratios prepared by the new synthesis method has a large specific surface area (i.e., 587-692 m(2)/g) and similar pore sizes of 2-11 nm. Solid-state Al-27 magic angle spinning (MAS) NMR shows that most of the aluminum is located in the tetrahedral position. A transmission electron microscopy (TEM) image shows that the mesoporous silica-alumina consists of 12-25 nm spheres. Additionally, high-resolution TEM and electron diffraction indicate that some nanoparticles are characteristic of a crystal, although X-ray diffraction and Si-29 MAS NMR analysis show an amorphous material.

Acid catalyzed synthesis of ordered bifunctionalized mesoporous organosilicas with large pore

Thiol-functionalized mesoporous ethane-silicas with large pore were synthesized by co-condensation of 1,2-bis(trimethoxy-sily)ethane (BTME) with 3-mercaptopropyltrimethoxysilane (MPTMS) using nonionic oligomeric polymer C1H (OCH(2)-CH(2))(10)OH (Brij-76) or poly(alkylene oxide) block copolymer (P123) as surfactant in acidic medium. The results of powder X-ray diffraction (XRD), nitrogen gas adsorption, and transmission electron microscopy (TEM) show that the resultant materials have well-ordered hexagonal mesoscopic structure with uniform pore size distributions. (29)Si MAS NNR, (13)C CP-MAS NMR. FT-IR, and UV Raman spectroscopies confirm the attachment of thiol functionalities in the mesoporous ethane-sificas. The maximum content of the attached thiol group (-SH) in the mesoporous framework is 2.48mmol/g. The ordered mesoporous materials are efficient Hg(2+) adsorbents with almost every -SH site accessible to Hg(2+). In the presence of various kinds of heavy metal ions such as Hg(2+), Cd(2+), Zn(2+), Cu(2+) and Cr(3+), the materials synthesized using poly(alkylene oxide) block cooollxmier (Pluronic 123) g(2+), as surfactant show almost similar affinity to Hg(2+), Cd(2+), and Cr(3+), while the materials synthesized using ofigomeric polymer C(18)H(37)(OCH(2)CH(2))(10)OH (Brij-76) as surfactant exhibit high selectivity to Hg(2+). (C) 2004 Elsevier Inc. All rights reserved.

Structural relation properties of hydrothermally stable functionalized mesoporous organosilicas and catalysis

The surfactant assistant syntheses of sulfonic acid functionalized periodic mesoporous organosilicas with large pores are reported. A one-step condensation of tetramethoxysilane (TMOS) with 1,2-bis(trimethoxysilyi)ethane (BTME) and 3-mercaptopropyltrimethoxysilane (MPTMS) in highly acidic medium was performed in the presence of triblock copolymer Pluronic P123 and inorganic salt as additive. During the condensation process, thiol (-SH) group was in situ oxidized to sulfonic acid (-SO3H) by hydrogen peroxide (30 wt % H2O2). X-ray diffraction studies along with nitrogen and water sorption analyses reveal the formation of stable, highly hydrophobic, and well-ordered hexagonal mesoscopic structures in a wide range of -CH2CH2-concentrations in the mesoporous framework. The resultant materials were also investigated by Si-29 MAS and C-13 CP MAS NMR, thermogravimetric analyses, UV-Raman spectroscopy, and FT-IR spectroscopy. The role of the bridged organic group on the hydrothermal stability of the mesoporous materials was established, which revealed an enhancement in hydrothermal stability of the materials with incorporation of the bridged organic groups in the network. The catalytic performance of -SO3H functionalized mesoporous materials was investigated in the esterification of ethanol with acetic acid, and the results demonstrate that the ethane groups incorporated in the mesoporous framework have a positive influence on the catalytic behavior of the materials.

Novos sistemas terapêuticos nanotecnológicos

Monografia apresentada à Universidade Fernando Pessoa para obtenção do grau Licenciada em Ciências Farmacêuticas