Structure and thermal stability of novel fluorophosphate glasses

A systematic investigation on glass formation in the PbF2-InF3-BaHPO4 ternary system has been carried out. These glasses have characterized by IR spectra, Raman spectra and differential thermal analysis. The results show that the structure of these glasses is mainly affected by BaHPO4 and InF3 contents. With decreasing BaHPO4 content, the glass structure gradually transforms from metaphosphate to polyphosphate. When InF3 content is low, it mainly acts as network modifier, when its content is high; it enters glass matrix and forms In(O,F)(6) groups connecting the polymerized phosphorus oxygen species. PbF2 mainly acts as network modifier in this system. Systematic variations of the glass transition temperature and the thermal stability index agree well with these results. The most stable glass with Delta T = 230 degrees C and S = 21.79 K is obtained. (c) 2004 Elsevier B.V. All rights reserved.

Influence of B2O3 to the inhomogeneous broadening and spectroscopic properties of Er3+/Yb3+ codoped fluorophosphate glasses

In a three-components fluorophosphate glass system, the introduction of H3BO3 brings some valuable influence to the spectroscopic and thermal properties of the glasses. With H3BO3 increases from 2 to 20mol%, ohm(6), S-ed4113/2, FWHM, T-g and fluorescence lifetime change from 3.21 x 10(-20) cm(2), 1.77 x 10(-20) cm(2), 45 nm, 480 degrees C and 8.8 ms to 4.66 x 10(-20) cm(2), 2.11 x 10(-20) cm(2), 50 nm, 541 degrees C and 7.4 ms, respectively. sigma(abs), sigma(emi), FWHM x tau(f) x sigma(emi) has a maximum when H-3 BO3 is 11 mol%. T-g and T-x-T-g increases with H3BO3 introduction. Results showed that in fluorophosphate glasses, proper amount of B2O3 can be used as a modifier to suppress upconversion and improve spectroscopic properties, broadband property and crystallization stability of the glasses while keeps the fluorescence lifetime relatively high. (c) 2005 Elsevier B.V. All rights reserved.

DRP蛋白的SUMO化修饰参与线粒体分裂调节的研究

　　SUMO (small ubiquition-like modifier) 是一类小的类泛素修饰物，能在一系列酶的作用下共价结合到目标蛋白上。 这种可逆的SUMO化修饰过程 (SUMOylation) 是调节细胞内蛋白质功能的重要方式之一，参与真核细胞内各种代谢途径。已有的研究发现，植物的SUMO化修饰参与植物花期调控，激素信号转导，抗病防御及逆境应答等生理过程。 　　线粒体是重要的细胞器，它的形态是多样和动态的。在活细胞中，线粒体不断地运动，并频繁地进行分裂与融合，维持着形态的平衡。而这种形态的动态平衡对线粒体功能的行使有着重要的意义。线粒体的分裂需要dynamin相关蛋白DRPs的参与，该类蛋白在进化中是保守的，从植物中已经鉴定出DRP3A和DRP3B两个蛋白。DRP蛋白由胞质招募到线粒体外膜上来参与膜的剪切，但有关DRP向线粒体招募和组装的机制尚不清楚。 　　本文通过对稳定表达GFP-SUMO1的BY-2悬浮细胞观察发现，SUMO1主要定位于细胞核中，在细胞质中也有少量分布；过表达SUMO1能使线粒体的片段化程度增强。而在SAE-RNAi植株及siz1突变体中，线粒体片段化程度减弱，由此提示SUMO化修饰的下调降低了线粒体的分裂水平。经序列分析发现，线粒体分裂蛋白DRP3A和DRP3B有SUMO化修饰的识别序列，而通过表达SUMO-DRP融合蛋白来加强DRP蛋白的SUMO化修饰，则能使线粒体分裂增加，从而表明SUMO化是通过对DRP的调节来影响线粒体的分裂。 我们推测SUMO化修饰的作用是能特异地保护DRP不被降解，最终导致DRP库更为稳定与活跃。总之，本文首次在植物中鉴定出SUMO1在线粒体上的作用，并暗示它可能通过调节DRP蛋白来参与线粒体分裂的新功能。

Metabolism traits of 'all-fish' growth hormone transgenic common carp (Cyprinus carpio L.)

Transgenic animals with improved qualities have the potential to upset the ecological balance of a natural environment. We investigated metabolic rates of 'all-fish' growth hormone (GH) transgenic common carp under routine conditions and during starvation periods to determine whether energy stores in transgenic fish would deplete faster than controls during natural periods of starvation. Before the oxygen uptake was measured, the mean daily feed intake of transgenic carp was 2.12 times greater than control fish during 4 days of feeding. The average oxygen uptake of GH transgenic fish was 1.32 times greater than control fish within 96 h of starvation, but was not significantly different from controls between 96 and 144 h of starvation. At the same time, GH transgenic fish did not deplete energy reserves at a faster rate than did the controls, as the carcass energy contents of the two groups following a 60-d starvation period were not significantly different. Consequently, we suggest that increased routine oxygen uptake in GH transgenic common carp over that of control fish may be mainly due to the effects of feeding, and not to an increase in basal metabolism. GH transgenic fish are similar to controls in the regulation of metabolism to normally distribute energy reserves during starvation. (c) 2008 Published by Elsevier B.V.

Effects of dietary manganese on growth and tissue manganese concentrations of juvenile gibel carp, Carassius auratus gibelio

A 68-day growth trial was conducted in a flow-through system to determine the effect of dietary manganese levels on growth and tissue manganese concentration of juvenile gibel carp (Carassius auratus gibelio). Seven purified diets containing 7.21, 8.46, 9.50, 10.50, 13.03, 19.72 and 22.17 mg manganese (as manganic sulfate) per kilogram diet were fed to triplicate groups of fish (initial weight 3.21 +/- 0.01 g). The results showed that dietary manganese levels did not significantly affect feed intake of the fish. Specific growth rate, feed efficiency, total hepatic superoxide dismutase activity, carcass and skeletal manganese concentration increased significantly with increased dietary manganese(P < 0.05) while condition factor decreased significantly(P < 0.05). It was concluded that dietary requirement of manganese was 13.77 mg Mn per kilogram diet. Carcass and skeletal manganese concentration could also be used to evaluate the manganese requirement. Total hepatic superoxide dismulase activity was not a sensitive indicator for dietary requirement.

Dietary methionine requirement for juvenile rockfish, Sebastes schlegeli

A 65-day growth trial was conducted at 19.5 degrees C to determine the optimal dietary methionine for juvenile rockfish, Sebastes schlegeli. Semipurified diets were formulated to be isonitrogenous and isoenergetic. Fish meal was used as intact protein source and crystal amino acid was used as a part of dietary protein. Six experimental diets were formulated to contain 5.8, 10.8, 15.8, 20.8, 25.8 and 30.8 g kg(-1) dietary methionine. The results showed that dietary methionine significantly affected specific growth rate, weight gain, food conversion ratio, protein productive value (PPV), energy retention efficiency, carcass index and body composition. No significant difference was found in hepatosomatic index. The dietary methionine requirement for maximum growth was 13.7 g kg(-1) dry matter or 28.0 g kg(-1) of dietary protein when cystine content was 1.2 g kg(-1) dry matter.

Comparative study on the effect of dietary lipid level on growth and feed utilization for gibel carp (Carassius auratus gibelio) and Chinese longsnout catfish (Leiocassis longirostris Gunther)

An 8-week growth trial investigated the effect of dietary lipid level on growth performance of a carnivorous fish, Chinese longsnout catfish (Leiocassis longirostris Gunther) and an omnivorous fish, gibel carp (Carassius auratus gibelio). For each species, seven isonitrogenous semi-purified diets (455 g kg(-1) crude protein for Chinese longsnout catfish and 385 g kg(-1) crude protein for gibel carp) were formulated to contain 30, 60, 90, 120, 150, 180 or 210 g kg(-1) lipid. For Chinese longsnout catfish, feed intake (FI) decreased with increasing dietary lipid and there was no significant difference in feed intake from 90 to 210 g kg(-1) lipid. Specific growth rate (SGR) increased with dietary lipid level (P < 0.05) and the 150 and 180 g kg(-1) groups were the best. Feed conversion efficiency (FCE), protein retention efficiency (PRE) and energy retention efficiency (ERE) were higher at 180 g kg(-1) lipid. For gibel carp, FI decreased with increased dietary lipid and 180 and 210 g kg(-1) lipid groups showed lower values. SGR increased with dietary lipid level and the 150 and 180 g kg(-1) were the best. FCE was higher at 180 g kg(-1) lipid level. PRE increased with dietary lipid level and there was no significant difference in groups from 120 to 210 g kg(-1) dietary lipid. ERE increased with increasing dietary lipid level, and groups fed 120, 150 and 180 g kg(-1) lipid showed the highest values. In Chinese longsnout catfish, increase in dietary lipid level, resulted in increased carcass dry matter, crude protein, crude lipid and gross energy. In gibel carp, dry matter, crude protein, and crude lipid increased with dietary lipid level. Based on regression between SGR and dietary lipid, dietary lipid requirements for Chinese longsnout catfish and gibel carp were 142.6 and 140.5 g kg(-1), respectively.

核壳结构改性剂增韧聚氯乙烯的机理及性能优化

我国是世界上聚氯乙烯产量最大的国家。由于在氯乙烯分子中氯的含量大于50%，而氯又是制碱工业的必然副产物，因此聚氯乙烯工业成为氯碱平衡中的主要杠杆。随着近年来世界石油资源的日益短缺和价格的上涨及国内聚氯乙烯产能过剩，开发聚氯乙烯的新用途，发展聚氯乙烯树脂的改性具有深远的意义。本工作的目的是以开发PVC核壳结构改性剂MBS和注塑级PVC/ABS合金为背景，对核壳粒子改性的聚氯乙烯的屈服机理和改性剂性能优化进行了研究。 对于增韧剂的研究，人们总是希望用最少的增韧剂用量来达到最好的增韧效果，即提高增韧剂的增韧效率，而且MBS改性的PVC在应用时还需要保持较高的透光率和具有一定的抗应力发白的能力。为此我们成功开发了具有高增韧效率、高透明及抗应力发白的MBS增韧剂，并研究了MBS结构特性对PVC/MBS共混物力学性能及屈服机理的影响。结果表明：粒径范围在80nm~280nm的橡胶粒子均能有效地对PVC进行增韧。大粒径的MBS通过空洞化释放三维静张应力引发基体的屈服来吸收能量，而小粒径的MBS不能产生空洞，但同样能引起基体的屈服起到增韧的作用。为了兼顾PVC/MBS共混物的韧性和透明性，我们在制备MBS时将一部分苯乙烯单体与丁二烯共聚结合来提高丁苯胶乳的折光指数与PVC基体相匹配，而另一部分苯乙烯单体以接枝的方式结合，这样可以保持MBS的弹性，并且制备的PVC/MBS共混物具有高韧性和高透明；同时我们发现MBS的内包容物及多层结构都会削弱PVC/MBS共混物的透光率。研究表明橡胶粒子的空洞化是引发共混物应力发白的主要原因。为此通过制备小粒径及具有一定交联程度的MBS来抑制空洞的产生，制备了兼有抗应力发白和韧性的MBS。成功开发了多个牌号的MBS产品，并在吉化集团公司建成了年产5000吨的生产车间，实现了MBS的工业化生产。 由于PVC的熔体流动性较差，通过与熔体流动性好的ABS树脂共混，成功开发了注塑级PVC/ABS合金。ABS树脂是SAN树脂和PB-g-SAN的共混物，在PVC中加入ABS使增韧对象由PVC基体转化为PVC/SAN共混基体，并研究了基体性质的改变对增韧效果的影响。结果表明随着PVC/ABS共混体系基体中PVC含量的增加共混物的冲击强度显著增加，形变机理发生了由银纹向剪切屈服的转变。

Pressurized electrochromatography coupled with electrospray ionization mass spectrometry for analysis of peptides and proteins

Pressurized capillary electrochromatography (pCEC) was coupled with electrospray ionization mass spectrometry (ESI-MS) using a coaxial sheath liquid interface. It was used for separation and analysis of peptides and proteins. The effects of organic modifier and applied voltage on separation were investigated, and the effects of pH value of the mobile phase and the concentration of the electrolyte on ESI-MS signal were investigated. The resolution and detection sensitivity with different separation methods (pCEC, capillary high-performance liquid chromatography) coupled on-line with mass spectrometry were compared for the separation of a peptide mixture. To evaluate the feasibility and reliability of the experimental setup of the system, tryptic digests of cytochrome c and modified protein as real samples were analyzed by using pCEC-ESI-MS.

Catalytic performance of MCM-22 zeolite for alkylation of toluene with methanol

MCM-22 zeolite with mid-strong acidity and openings of 10-membered ring channels may obtain a high catalytic activity and selectivity for alkylation of toluene with methanol. The acidic sites, for catalyzing alkylation of toluene with methanol, are weaker than that for catalyzing toluene disproportionation. Compared with silicon as a modifier, modification of MCM-22 with La(NO3)(3) is a promising way to improve the catalytic selectivity of para-xylene. In addition, the experimental results also clearly indicate the characteristics of MCM-22 structure consisting of large intracrystalline cages, some of which may locate on surface of MCM-22. (C) 2004 Elsevier B.V. All rights reserved.

Pressurized capillary electrochromatography separation of peptides with strong cation exchange and hydrophilic interaction

A pressurized capillary electrochromatography (pCEC) instrument with solvent gradient capability has been used for the separation of a peptide mixture. Retention mechanism and selectivity of the peptides were studied by pCEC using a strong cation exchange (SCX) column. The effects of applied voltage, supplementary pressure, organic modifier concentration, ionic strength,, and pH value on pCEC separation were investigated. It was found that the retention mechanism of the peptides in this system is based on a mixed mode of hydrophilic interaction, strong cation exchange, and electrophoresis. Compared with the separation results obtained by reverse phase pCEC and capillary electrophoresis (CE), this mixed-mode pCEC is more powerful for the separation of hydrophilic peptides with similar charge-to-mass ratio.

Multivariate optimization in micellar electrokinetic capillary chromatography

The optimization of the organic modifier concentration in micellar electrokinetic capillary chromatography (MECC) has been achieved by a uniform design and iterative optimization method, which has been developed for the optimization of composition of the mobile phase in high performance liquid chromatography. According to the proposed method, the uniform design technique has been applied to design the starting experiments, which can reduce the number of experiments compared with traditional simultaneous methods, such as the orthano design. The hierarchical chromatographic response function has been modified to evaluate the separation quality of a chromatogram in MECC. An iterative procedure has been adopted to search the optimal concentration of organic modifiers for improving the accuracy of retention predicted and the quality of the chromatogram. Validity of the optimization method has been proved by the separation of 31 aromatic compounds in MECC. (C) 2000 John Wiley & Sons, Inc.