Experimental formulation of an anti fouling paint with tributyl tin oxide as toxic pigment

Results of the experimental formulation of an antifouling paint incorporating TBTO as toxic pigment are presented in this paper. Of the various resins tested, namely, phenolic, cashew nut shell liquid (CNSL), epoxy linseed oil with rosin and limed rosin, the paint composition with limed rosin gave the critical leaching rate of TBTO. Acid alkali test showed dissolution of matrix and visible migration of toxin to the surface. Accelerated corrosion tests had not recorded any signs of corrosion in panels painted with or without barrier coat. Raft exposure studies indicated that the new formulation could resist fouling accumulation on painted panels for 9 months.

Ferrocement buoys for mussel culture

A method is described for culturing mussels (Mytilus smaragdinus) using ferrocement buoys, which may be used in the construction of a raft house or a flotation system for nets and cages.

Selection of materials for marine instruments

The paper describes the selection of materials for the reliable operation of oceanographic instruments. For selecting the material, raft immersion tests were carried out for one year. Results of the tests are presented. Comparisons between metals were discussed.

Contributions of phosphatase and microbial activity to internal phosphorus loading and their relation to lake eutrophication

Phosphatase may accelerate the process of lake eutrophication through improving phosphorus bioavailability. This mechanism was studied in three Chinese eutrophic shallow lakes (Lake Taihu, Lake Longyang,and Lake Lianhua). Phosphatase activity was related to the concentration of soluble reactive phosphorus (SRP) and chlorophyll a. Stability of dissolved phosphatase in reverse micelles may be attributed to molecular size, conformation and active residues of the enzyme. At the site with Microcystis bloomed in Lake Taihu, dissolved phosphatase activity was higher and more stable in micelles, SRP concentrations were lower in interstitial water, the contents of different forms of phosphorus and the amounts of aerobic bacteria were lower while respiration efficiency was higher in sediments. Phosphobacteria, both inorganic and organic and other microorganisms were abundant in surface water but rare in sediments. Therefore, internal phosphorus may substantially flux into water column by enzymatic hydrolysis and anaerobic release, together with mobility of bacteria, thereby initiating the bloom. In short, biological mechanism may act in concert with physical and chemical factors to drive the internal phosphorus release and accelerate lake eutrophication.

Vertical variation in dissolved alkaline phosphatase activity in a shallow eutrophic lake determined in reverse micelles

We evaluated the feasibility of microencapsulating dissolved alkaline phosphatase of a water body into reverse micelle systems prepared by hexadecyltrimethylammonium bromide as a surfactant in cyclohexane and 1-butanol as co-surfactant. The dissolved alkaline phosphatase activity within the micelle was described, including its kinetic parameters and the effects of pH and temperature on catalytic activity in surface, overlying and interstitial water of Lake Donghu. We found the similarities on the behavior of dissolved alkaline phosphatase of surface and interstitial water in reverse micelles, which was distinctly different from its behavior in the overlying water. This difference likely reflected the different origins of the dissolved alkaline phosphatase in the vertical profile of the lake. This system provides a novel tool with which to study the diversity and ecological significance of extracellular enzymes in aquatic environments.

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.

INFLUENCE OF LINEAR ALKYLBENZENE SULFONATE (LAS) AS ORGANIC COSOLVENT ON LEACHING BEHAVIOR OF PCDD/FS FROM FLY-ASH AND SOIL

The leaching of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) was measured in soil and standard fly ash column eluted with pure water and linear alkylbenzene sulfonate (LAS)- water. The data obtained were used to evaluate the leachability of PCDD/Fs from waste dump like incineration residual slag and fly ash deposition. The leaching rate was shown to be increased significantly by using LAS water. The leachate contents of PCDD/Fs were above their known water solubility. Concentration of PCDD/Fs in the leachates as well as the relative leaching (calculated on the fly ash content) increased with increasing chlorinating degree and decreasing water solubility. LAS above the critical micelle concentration (CMC) probably enhances PCDD/Fs solubility.

一个支持可信主体特权最小化的多级安全模型

对已有多级安全模型的可信主体支持进行回顾和分析,提出了DLS(离散标记序列)多级安全模型.该模型将可信主体的生命周期分解为一系列非可信状态,对每一个状态赋予一个敏感标记.可信主体的当前敏感标记等于当前非可信状态的敏感标记,非可信状态的切换由预定义的可信请求事件触发.从而可信主体的当前敏感标记可以根据其应用逻辑而动态调整.同时给出了模型保持系统安全性的安全状态和规则.与Bell模型等可信主体敏感标记范围模型相比,该模型在多级安全的策略范围内实现了可信主体的特权最小化.

水凝胶的制备及壳聚糖的改性和应用

水凝胶用作创口敷料时有很多的优点。壳聚糖是天然的阳离子多糖,已经在很多领域得到了应用。我们制备了几种具有抑菌能力的水凝胶敷料，同时利用可生物降解聚酯和多聚肽对壳聚糖进行了修饰，得到了一些新的结果。 本论文的工作主要包括以下两部分： 一.含有抗生素或纳米银粒子的水凝胶的制备和表征。 1．载药聚乙烯醇/聚乙烯基吡咯烷酮/壳聚糖（PVA-PVP-Chitosan）复合水凝胶的制备和抑菌性能评价。采用循环冷冻－熔融与辐射交联相结合的方法制备出了PVA-PVP-chitosan复合水凝胶，测定了凝胶的溶胀率、凝胶含量、力学强度和结晶性能，并考察了所用壳聚糖分子量，冷冻－熔融循环处理次数和辐射剂量对凝胶性能的影响。然后通过溶胀法将抗生素（环丙沙星）和壳寡糖载入水凝胶中，考察了它们的体外释放行为。同时利用琼脂糖平板法检验了载药凝胶的抑菌能力，结果表明它们可以有效抑制革兰氏阳性菌和革兰氏阴性菌的繁殖和生长。 2．含纳米银-PVA-PVP水凝胶的制备和抑菌性能评价。通过循环冷冻－熔融法制备了含银的PVA-PVP复合水凝胶。以含银的PVA-PVP复合膜为模型，利用DSC、红外光谱、紫外－可见光谱和X-射线衍射考察了掺入的纳米银与PVA-PVP网络的相互作用。利用扫描电镜观察了PVA-PVP凝胶的网络结构和银纳米粒子在网络中的分布。利用琼脂糖平板法和LB肉汤法对含银PVA-PVP凝胶的抑菌性能进行了评价，结果证明这种水凝胶可以有效抑制大肠杆菌和金黄色葡萄球菌的生长和繁殖。 二. 壳聚糖的改性和应用。 1．发展了一种制备聚ε－己内酯（PCL）接枝壳聚糖共聚物的新方法，并且由合成的接枝共聚物在水中自组装得到纳米粒子。利用DLS、AFM和SEM对纳米粒子进行了表征，结果显示制备的纳米粒子为圆球形或椭圆形。利用茚三酮显色法准确测定了活性胺基的含量，发现纳米粒子表面活性胺基的数量可以通过改变PCL接枝度进行调节。 2．由6-O-三苯甲基壳聚糖引发赖氨酸NCA的开环聚合得到了聚赖氨酸（PLL）接枝壳聚糖阳离子共聚物。利用红外光谱、核磁共振和GPC对接枝共聚物的分子结构和分子量进行了表征。通过动态光散射测量发现接枝共聚物可以和小牛胸腺DNA形成粒径在100~340 nm之间的复合物。凝胶阻滞电泳证明接枝共聚物对质粒DNA的结合和保护能力要优于壳聚糖。细胞转染实验证明接枝共聚物对293T和Hela细胞的转染效率要远远高于壳聚糖原料和PLL。同时，接枝共聚物的转染效率对PLL的聚合度有明显的依赖性，增加PLL聚合度有助于提高接枝共聚物的转染效率。这种新型的阳离子接枝共聚物有望用作高效基因载体。

Comparison of aggregation behaviors between branched and linear block polyethers: MesoDyn simulation study

The comparison of aggregation behaviors between the branched block polyether T1107 (polyether A) and linear polyether (EO)(60)(PO)(40)(EO)(60) (polyether B) in aqueous solution are investigated by the MesoDyn simulation. Polyether A forms micelles at lower concentration and has a smaller aggregation number than B. Both the polyethers show the time-dependent micellar growth behaviors. The spherical micelles appear and then change to rod-like micelles with time evolution in the 10 vol% solution of polyether A. The micellar cluster appears and changes to pseudo-spherical micelles with time evolution in the 20 vol% solution of polyether A. However, the spherical micelles appear and change to micellar cluster with time evolution in the 20 vol% polyether B solution. The shear can induce the micellar transition of both block polyethers. When the shear rate is 1x10(5) s(-1), the shear can induce the sphere-to-rod transition of both polyethers at the concentration of 10 and 20 vol%. When the shear rate is lower than 1x10(5) s(-1), the huge micelles and micellar clusters can be formed in the 10 and 20 vol% polyether A systems under the shear, while the huge micelles are formed and then disaggregated with the time evolution in the 20 vol% polyether B system.

流体力学半径对估算胶体微球聚集速率常数的影响

胶体粒子聚集速率常数实验值远低于理论值一直是被普遍关注的问题.聚集速率常数的理论推导是基于粒子的几何半径来考虑的,但决定粒子扩散速率及聚集速率的应该是粒子的流体力学半径(大于几何半径),因而它是使聚集速率常数实验值低于理论值的因素之一.影响流体力学半径的因素很多,其中,带电粒子在溶液中因表面存在双电层,会明显增大流体力学半径,造成聚集速率减慢.而双电层的厚度又随溶液中离子强度的不同而改变.本工作在聚集速率的公式中引入了修正因子,即几何半径与其流体力学半径之比,以修正由于用几何半径代替流体力学半径带来的误差.其中几何半径和流体力学半径可以分别用扫描电镜(SEM)和动态光散射(DLS)来测定.以两种粒径的聚苯乙烯带电微球为例,考察了在不同离子强度下,该误差的大小.结果发现,对于半径为30 nm的微球,用流体力学半径计算的慢聚集速率常数比理论值偏低约8%.该误差随离子强度增加而减少.对于快聚集情况,流体力学半径对聚集速率基本没有影响.

Self-assembly of a hydrophobic polypeptide containing a short hydrophilic middle segment: Vesicles to large compound micelles

This report describes a facile route to prepare the vesicles and large compound micelles (LCMs) from a series of poly(epsilon-benzyloxycarbonyl L-lysine)-block-poly[diethylene glycol bis(3-amino propyl) ether]-block-poly(epsilon-benzyloxycarbonyl L-lySine) (PZLL-DGBE-PZLL) in their water solution, depending on molecular weight of the polypeptides. A pyrene probe is used to demonstrate the aggregate formation of PZLL-DGBE-PZLL in solution, and also to measure their critical micelle concentration as a function of molecular weight of the polymer.

Novel pH- and temperature-responsive block copolymers with tunable pH-responsive range

A series of novel pH- and temperature-responsive diblock copolymers composed of poly(N-isopropylacrylamide) (PNIPAM) and poly[(L-glutamic acid)-co-(gamma-benzyl L-glutamate)] [P(GA-co-BLG)] were prepared. The influence of hydrophobic benzyl groups on the phase transition of the copolymers was studied for the first time. With increasing BLG content in P(GA-co-BLG) block, the thermal phase transition of the diblock copolymer became sharper at a designated pH and the critical curve of phase diagram of the diblock copolymer shifted to a higher pH region.

Ion-Responsive Behavior of Ionic-Liquid Surfactant Aggregates with Applications in Controlled Release and Emulsification

We propose a simple but efficient, rapid, and quantitative ion-responsive micelle system based on counter-anion exchange of a surfactant with an imidazolium unit. The ion-exchange reaction results in the amphiphilic-to-hydrophobic transition of the imidazolium salt, leading to the destruction of the micelles, which has been successfully applied to control led release and emulsification.

One-pot synthesis and characterization of hyperbranched poly(ester-amide)s from commercially available dicarboxylic acids and multihydroxyl secondary Amines

A convenient and cost-effective strategy for synthesis of hyperbranched poly(ester-amide)s from commercially available dicarboxylic acids (A(2)) and multihydroxyl secondary amine (CB2) has been developed. By optimizing the conditions of model reactions, the AB(2)-type intermediates were formed dominantly during the initial reaction stage. Without any purification, the AB(2) intermediate was subjected to thermal polycondensation in the absence of any catalyst to prepare the aliphatic and semiaromatic hyperbranched poly(ester-amide)s bearing multi-hydroxyl end-groups.