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.

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.

Comparative studies of AOT and NaDEHP by fluorescence technique and z-potential (ζ) measurements

The aggregation behaviors of two surfactants with the same hydrophobic tail, sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and sodium bis(2-ethylhexyl)phosphate (NaDEHP), have been investigated by the fluorescence technique and z-potential (ζ) measurements. Five fine peaks of the pyrene molecule fluorescence spectroscopy appear in the surfactant solution, and the micropolarity at which pyrene locates is monitored from the intensity ratio of the first (I1) and the third peak (I3). A wide peak around 475 nm, the emission spectra of the excimer of pyrene molecules, is observed in the NaDEHP solution, while this is not found for the AOT system. The value of I1/I3 decreases in a more limited concentration range for the AOT system than for NaDEHP, indicating that small aggregates can be more easily formed by NaDEHP molecules. The z-potential results for the aggregates formed by the two surfactants show that the interaction between AOT and PVP is stronger than that between NaDEHP and PVP.

Microscopic Model Of Nano-Scale Particles Removal In High Pressure Co2-Based Solvents

A physical model is presented to describe the kinds of static forces responsible for adhesion of nano-scale copper metal particles to silicon surface with a fluid layer. To demonstrate the extent of particle cleaning, Received in revised form equilibrium separation distance (ESD) and net adhesion force (NAF) of a regulated metal particle with different radii (10-300 nm) on the silicon surface in CO2-based cleaning systems under different pressures were simulated. Generally, increasing the pressure of the cleaning system decreased the net adhesion force between spherical copper particle and silicon surface entrapped with medium. For CO2 + isopropanol cleaning system, the equilibrium separation distance exhibited a maximum at temperature 313.15 K in the Equilibrium separation distance regions of pressure space (1.84-8.02 MPa). When the dimension of copper particle was given, for example, High pressure 50 nm radius particles, the net adhesion force decreased and equilibrium separation distance increased with increased pressure in the CO2 + H2O cleaning system at temperature 348.15 K under 2.50-12.67 MPa pressure range. However, the net adhesion force and equilibrium separation distance both decreased with an increase in surfactant concentration at given pressure (27.6 or 27.5 MPa) and temperature (318 or 298 K) for CO2 + H2O with surfactant PFPE COO-NH4+ or DiF(8)-PO4-Na+. (C) 2008 Elsevier B.V. All rights reserved.

表面活性剂存在下的光系统I的光合特性

本文主要研究了在非离子表面活性剂－辛基硫代葡萄糖苷（OTG）处理条件下菠菜叶绿体中光系统I（PSI）颗粒的光合特性，主要的研究结果如下： 1. 在所研究的OTG浓度范围内（0.01～13%，w/v），OTG对PSI的电子传递活性有显著的促进作用。而与此相对照，阴离子表面活性剂－十二烷基硫酸钠（SDS）对PSI的活性具有抑制作用。 2. OTG对PSI在SDS和高温（70℃）处理后失去的电子传递活性具有恢复作用。 3. OTG对PSI的色素结合状态和能量传递都有很大的影响，影响程度和影响方式与OTG的浓度有关。在其临界胶束浓度（cmc）以上的一定浓度范围内，OTG处理会导致PSI捕光天线色素蛋白复合体（LHCI）的解离;而更大浓度的OTG会使PSI中产生自由色素。

Evolution of different oligorneric glycyl-tRNA synthetases

There are two oligomeric types of glycyl-tRNA synthetases (GlyRSs) in genome, the alpha(2)beta(2) tetramer and alpha(2) dimer. Here, we showed that the anticodon-binding domains (ABDs) of dimeric and tetrameric GlyRSs are non-homologous, although their catalytic central domains (CCDs) are homologous. The dimeric GlyRS_ABD is fused to the C-terminal of CCD in alpha-subunit, but the tetrameric GlyRS_ABD is to the C-terminal in beta-subunit during evolution. Generally, one species only contains one oligomeric type of GlyRS, but the both oligomeric GlyRSs with the multiple homologous domains can be observed in Magnetospirillum magnetotacticum genome, nevertheless, these homologous domains are probably from different genomes. (C) 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Interaction between human interleukin-16 and CD4 receptor of HIV-1

AIM: To study the interaction between human interleukin-16 (IL-16) and the receptor CD4 (T-lymphocyte differentiation antigen) of human immunodeficiency virus type 1 (HIV-1). METHODS: Two structurally con served regions (SCRs) of human IL-16 were built by the SYBYL/Biopolymer module using the corresponding transmembrane (TM) domain of human interleukin-1 (HIL-4) and HIL-2 as the templates. The coordinates for amino-terminal residue sequence, carboxyl-terminal residue sequences, and cytoplasm loops were generated using Biopolymer's LOOP SEARCH algorithm. RESULTS: HIL-16 first formed a homodimer, then contacted with CD4 dimer further forming a dimeric complex. Subsequently, the dimeric complex constructed the tetrameric complex by two disulfide bridges between the cysteines of HIL-16 (Cys31-Cys31). CONCLUSION: The interaction model is useful to propose the action mechanism of HIL-16 and is beneficial for rational designing of novel anti-HIV drugs.

FLUCTUATION OF SIZE-FRACTIONATED ALKALINE PHOSPHATASE AFTER BLOOM DISAPPEARANCE IN TWO SHALLOW PONDS

The temporal and vertical fluctuations of size fractionated alkaline phosphatase activity (APA) and kinetics parameters as well as orthophosphate (o-P) and chlorophyll concentrations were investigated after bloom disappearance in two shallow ponds A and B from 27 October 2001 to 15 April 2002. Pond A (Microcystis) bloomed seriously but pond B did not. The data of o-P and chlorophyll suggested that phosphorus was the principal limiting nutrimental element and its vertical flux should be regarded as an important driving factor for algal growth. In pond A, the accumulation of algae-derived detritus after bloom disappearance in overlying water stimulated excretion of algal fraction APA, mainly produced by attached bacteria responsible for detritus decomposition, whereas bacterial fraction APA preferred to function in surface water. Interestingly, completely contrary phenomena were observed in pond B. In season, even though no obvious difference for size-fractionated APA in both ponds, the total APA in pond A peaked earlier showing higher activity and efficiency (low K-m and high V-max values) as a result of algal-derived detritus input. In summary, it is suggested that the excretion of alkaline phosphatase with strongly catalyzing efficiency and high activity should be taken as important contributor to algal-derived detritus decomposition, further fueling nutrient recycle and accelerating algal development next year. Furthermore, some inhibitors and surfactants were testified to be good tools to identify the origin of dissolved alkaline phosphatase.

Identification of novel SINEs from Cyprinidae and their evolutionary significance

Short interspersed nuclear elements (SINEs) are widespread among eukaryotic genomes. They are repetitive DNA sequences that have been amplified by retrotransposition. In this study, a class of SINEs were isolated from the Opsariichthys bidens genome, and named Opsar. Sequence analysis confirmed that Opsar is a new class of typical SINEs derived from tRNA molecules. With the tRNA-derived region of Opsar and through BLASTN search, we further identified Zb-SINEs from the zebrafish genome, which includes two groups: Zb-SINE-A and Zb-SINE-B. The Zb-SINE-A group comprises subfamilies of -Al--A5, and the Zb-SINE-B group is a dimer of the tRNA(Ala)-derived region and shares a similar dimeric composition to Alu. Zb-SINEs are composed of three distinct regions: a 5 end tRNA-derived region, a tRNA-unrelated region and a 3 end AT-rich region. The flanking regions are AT rich. The average length of Zb-SINEs elements is about 340 6p. Zb-SINEs account for as much as 0.1% of the whole zebrafish genome. About 70% of the Zb-SINEs are on chromosomes 11, 18, and 19. These Zb-SINEs were characterized by PCR and dot hybridization. The distribution pattern of Zb-SINEs in genome strongly supports the master genes model. The tRNA-derived regions of Opsar and Zb-SINEs were compared with the tRNA(Ala) gene, and they showed 76% similarity, indicating that Opsar and Zb-SINEs originated from an inactive tRNA(Ala) sequence or a tRNA(Ala)-like sequence. In view of the evolutionary status of zebrafish in the Cyprinidae, we deduced that Zb-SINEs were a very old class of interspersed sequences.

Water solubility enhancement of phthalates by cetyltrimethylammonium bromide and beta-cyclodextrin

Water solubility enhancements of six phthalates (five aliphatic phthalates and one phenyl phthalate) by cetyltrimethylammonium bromide (CTAB) and beta-cyclodextrin (beta-CD) were studied at 25 degreesC. The solubilities of these plithalates are remarkably enhanced by CTAB solutions above the critical micelle concentration (cmc). Only marginal enhancement of phthalate solubility was observed in solutions containing CTAB below its cmc and beta-CD at low concentrations (less than 5 mM). The solubility enhancements of the plithalates are proportional to the added amount of CTAB and beta-CD. Partition coefficients of the plithalates between monomeric CTAB surfactant and water (K-MN) and between CTAB micelle and water K-MC) were estimated from the experimental data. The mechanisms of solubility enhancements by CTAB and beta-CD were discussed. A log-linear equation was proposed and evaluated for the solubilization by CTAB below cmc, while the previously proposed linear partitioning model was questioned. The structures of the complexes formed between plithalates and beta-CD were proposed, and the formation constants were estimated. The values of log K-MC, log K-MN, and log Kbeta-CD of the plithalates were found to correlate linearly with the log K-OW of plithalates, with the exception of the solid phenyl phthalate.

Polymerization of ionic liquid-based microemulsions: A versatile method for the synthesis of polymer electrolytes

电子邮箱fyan@suda.edu.cn

气体水合物生成特性实验研究

实验研究了添加剂对甲烷气体水合物形成过程的影响。发现微量的表面活性剂降低了甲烷气体水合物在静止反应器中形成的诱导时间，并使水合物快速形成和生长，提高了水合物形成过程中的填充密度。阴离子表面活性剂（十二烷基硫酸钠）对水合物生长的促进作用比非离子表面活性剂（烷基多糖苷）强。液态烃环戊烷降低了水合物形成的诱导时间，但环戊烷不能提高水合物的填充密度。

Study on methane hydration process in a semi-continuous stirred tank reactor

The methane hydration process is investigated in a semi-continuous stirred tank reactor. Liquid temperatures and reaction rates without stirrer are compared with those occurring with stirrer, while at the same time better stirring conditions of the methane hydration process are given by the experiments. Some basic data of fluid mechanics, for example, stirring Reynolds number, Froucle number and stirrer power, are calculated during the methane hydration process, which can be applied to evaluate stirrer capacity and provide some basic data for a scaled up reactor. Based on experiment and calculations in this work, some conclusions are drawn. First, the stirrer has great influence on the methane hydration process. Batch stirring is helpful to improve the mass transfer and heat transfer performances of the methane hydration process. Second, induction time can be shortened effectively by use of the stirrer. Third, in this paper, the appropriate stirring velocity and stirring time were 320 rpm and 30 min, respectively, at 5.0 MPa, for which the storage capacity and reaction time were 159.1 V/V and 370 min, respectively. Under the condition of the on-flow state, the initial stirring Reynolds number of the fluid and the stirring power were 12,150 and 0.54 W, respectively. Fourth, some suggestions, for example, the use of another type of stirrer or some baffles, are proposed to accelerate the methane hydration process. Comparing with literature data, higher storage capacity and hydration rate are achieved in this work. Moreover, some fluid mechanics parameters are calculated, which can provide some references to engineering application.