THE THERMODYNAMICS OF MICELLIZATION BY BLOCK COPOLYMER SEP IN ORGANIC SOLVENTS

The thermodynamics of micellization for polystyrene-b-poly(ethylene/propylene) two-Mock copolymer(SEP) in the mixtures of n-octane and benzene with different proportions have been studied in this paper, The critical micelle concentrations(GMC) of micelle solutions at various temperatures were measured by lost angle laser light scattering photometer(LALLS), The results shove that the micellization process of nonpolar copolymer SEP in hydrocarbon solvents ire exothermal, and the entropy change is negative, In contrast, far ordinary surfactants in water, it is the enthalpy contribution to the energy change which is responsible for micellization.

Toxicity and protective efficiency of cryoprotectants to flounder (Paralichthys olivaceus) embryos

With the purpose of finding an ideal cryoprotectant or combination of cryoprotectants in a suitable concentration for flounder (Paralichthys olivaceus) embryo cryopreservation, we tested the toxicities, at culture temperature (16 degrees C), of five most commonly used cryoprotectants-dimethyl sulfoxide (Me2SO), glycerol, methanol (MeOH), 1,2-propylene glycol (PG) and ethylene glycol (EG). In addition, cryoprotective efficiency to flounder embryos of individual and combined cryoprotectants were tested at -15 degrees C for 60 min. Five different concentrations of each of the five cryoprotectants and 20 different combinations of these cryoprotectants were tested for their protective efficiency. The results showed that the toxicity to flounder embryos of the five cryoprotectants are in the following sequence: PG < MeOH < Me2SO < glycerol < EG (P < 0.05); whereas the protective efficiency of each cryoprotectant, at -15 degrees C for a period of 60 min, are in the following sequence: PG > Me2SO approximate to MeOH approximate to glycerol > EG (greater symbols mean P < 0.05, and approximate symbols mean P > 0.05). Methanol combined with any one of the other cryoprotectants gave the best protection, while ethylene glycol combined with any one of the other cryoprotectants gave the poorest protection at -15 degrees C. Toxicity effect was concentration dependent with the lowest concentration being the least toxic for all five cryoprotectants at 16 degrees C. For PG, MeOH and glycerol, 20% solutions gave the best protection at -15 degrees C; whereas a 15% solution of Me2SO, and a 10% solution of EG, gave the best protection at -15 degrees C. (c) 2004 Elsevier Inc. All rights reserved.

Algal biotechnology industries and research activities in China

In old China there were very few people engaged in the study of the algae, but in new China, freshwater and marine algae are studied by over one hundred old and new phycologists. There is now an algal biotechnology industry consisting of an aquaculture industry, producing large amounts of the seaweeds Laminaria, Porphyra, Undaria, Gracilaria, eucheumoids, and the microalgae Dunaliella and Spirulina. There is also a phycocolloid industry, producing algin, agar and carrageenan; an industry producing chemicals and drugs, such as iodine, mannitol, phycocyanin, beta -carotene, PSS (propylene glycol alginate sulfate) and FPS (fucose-containing sulfated polysaccharides) and an industry producing food, feed and fertilizer. The Laminaria cultivation industry produces about 900,000 t dry Laminaria, probably the largest producer in the world and 13,000 t algin, undoubtedly one of the largest algin producer in the world.

PRELIMINARY STUDIES ON CRYOPRESERVATION OF SYDNEY ROCK OYSTER (SACCOSTREA GLOMERATA) LARVAE

In this study several parameters critical to the success of cryopreserving Sydney rock oyster (Saccostrea glomerata) larvae were investigated. They were: (1) cryoprotectants (10% dimethyl sulfoxide and 10% propylene glycol). (2) freezing protocols (with or without the seeding step). (3) larval concentrations (1,000, 3,000, 5,000, 10,000, 30,000 individuals mL(-1)). and (4) larval ages (6, 12, 24, 48 and 96 h old). The survival rates were determined as percentages of postthaw larvae performing active movements for the 6 and 12 h larvae or active cilia movement for the 24, 48 and 96 h larvae. Analyses showed that the difference in survival rates between different age classses was significant in all the experiments conducted, with the maximum survival rate being achieved in the 24-h-old larvae the postthaw survival rates of larvae cryopreserved with 10% dimethyl sulfoxide (93.1 +/- 0.2%) were significantly higher (P < 0.001) that those with 10% propylene glycol (81.5 +/- 0.4%). Differences in postthaw survival rates between different concentrations (1,000 30,000 individuals mL(-1)) were not significant within each of the three larval age classes (6-, 12-, and 24-h-old ) used.

Effect of cryoprotectants on hatching rate of red seabream (Pagrus major) embryos

The objectives were to investigate the effect of cryoprotectants on the hatching rate of red seabream embryos. Heart-beat embryos were immersed in: five permeable cryoprotectants, dimethyl sulfoxide (DMSO), glycerol (Gly), methanol (MeOH), 1,2-propylene glycol (PG), and ethylene glycol (EG). in concentrations of 5-30% for 10, 30, or 60 min; and two non-permeable cryoprotectants: polyvinylpyrrolidone (PVP), and sucrose (in concentrations of 5-20% for 10 or 30 min). The embryos were then washed and incubated in filtered seawater until hatching occurred. The hatching rate of the embryos treated with permeable cryoprotectants decreased (P < 0.05) with increased concentration and duration of exposure. In addition, PG was the least toxic permeable cryoprotectant, followed by DMSO and EG, whereas Gly and MeOH were the most toxic. At a concentration of 15% and 30 min exposure, the hatching rate of the embryos immersed in PG was 93.3 +/- 7.0% (mean +/- S.D.), however. in DMSO. EG, Gly. and MeOH, it was 82.7 +/- 10.4, 22.0 +/- 5.7, 0.0 +/- 0.0, and 0.0 +/- 0.0%, respectively. Hatching rate of embryos treated with PVP decreased (P < 0.05) with the increase of concentration and exposure time, whereas for embryos treated with sucrose, there was no significant decrease in comparison with the control at the concentrations used. (C) 2008 Elsevier Inc. All rights reserved.

Preliminary studies on the vitrification of red sea bream (Pagrus major) embryos

The objective was to identify an appropriate cryoprotectant and protocol for vitrification of red sea bream (Pagrus major) embryos. The toxicity of five single-agent cryoprotectants, dimethyl sulfoxide (DMSO), propylene glycol (PG), ethylene glycol (EG), glycerol (GLY), and methyl alcohol (MeOH), as well as nine cryoprotectant mixtures, were investigated by comparing post-thaw hatching rates. Two vitrifying protocols, a straw method and a solid surface vitrification method (copper floating over liquid nitrogen), were evaluated on the basis of post-thaw embryo morphology. Exposure to single-agent cryoprotectants (10% concentration for 15 min) was not toxic to embryos, whereas for higher concentrations (20 and 30%) and a longer duration of exposure (30 min), DMSO and PG were better tolerated than the other cryoprotectants. Among nine cryoprotectant mixtures, the combination of 20% DMSO + 10% PG + 10% MeOH had the lowest toxicity after exposure for 10 min or 15 min. High percentages of morphologically intact embryos, 50.6 +/- 16.7% (mean +/- S.D.) and 77.8 +/- 15.5%, were achieved by the straw vitrifying method (20.5% DMSO + 15.5% acetamide + 10% PG, thawing at 43 degrees C and washing in 0.5 M sucrose solution for 5 min) and by the solid surface vitrification method (40% GLY, thawing at 22 degrees C and washing in 0.5 M sucrose solution for 5 min). After thawing, morphological changes in the degenerated embryos included shrunken yolks and ruptured chorions. Furthermore, thawed embryos that were morphologically intact did not consistently survive incubation. (C) 2007 Elsevier Inc. All rights reserved.

Oxidative dehydrogenation of ethane and propane over Mn-based catalysts

The catalytic performances of Mn-based catalysts have been investigated for the oxidative dehydrogenation of both ethane (ODE) and propane (ODP). The results show that a LiCl/MnOx/PC (Portland cement) catalyst has an excellent catalytic performance for oxidative dehydrogenation of both ethane and propane to ethylene and propylene, more than 60% alkanes conversion and more than 80% olefins selectivity could be achieved at 650 degrees C. In addition, the results indicate that Mn-based catalysts belong to p-type semiconductors, the electrical conductivity of which is the main factor in influencing the olefins selectivity. Lithium, chlorine and PC in the LiCl/MnOx/PC catalyst are all necessary components to keep the excellent catalytic performance at a low temperature.

New progress in R&D of lower olefin synthesis

This paper gives a brief review of R&D researches for light olefin synthesis directly and indirectly from synthesis gas in the Dalian Institute of Chemical Physics (DICP). The first pilot plant test was on methanol to olefin (MTO) reaction and was finished in 1993, which was based on ZSM-5-type catalyst and fixed bed reaction. In the meantime, a new indirect method designated as SDTO (syngas via dimethylether to olefin) was proposed. In this process, metal-acid bifunctional catalyst was applied for synthesis gas to dimethylether(DME) reaction, and modified SAPO-34 catalyst that was synthesized by a new low-cost method with optimal crystal size was used to convert DME to light olefin on a fluidized bed reactor. The pilot plant test on SDTO was performed and finished in 1995. Evaluation of the pilot plant data showed that 190-200 g of DME were yielded by single-pass for each standard cubic meter of synthesis gas. For the second reaction, 1.880 tons of DME or 2.615 tons of methanol produced 1 ton of light olefins, which constitutes of 0.533 ton of ethylene, 0.349 ton of propylene and 0.118 ton of butene. DICP also paid some attention on direct conversion of synthesis gas to light olefins. A semi-pilot plant test (catalyst 1.8 1) was finished in 1995 with a CO conversion > 70% and a C(2)(=)-C(4)(=) olefin selectivity 71-74% in 1000 h. (C) 2000 Published by Elsevier Science B.V. All rights reserved.

A gas chromatographic analysis of light hydrocarbons on a column packed with modified silica gel

A one-meter long column packed with silica gel is used to separate light hydrocarbons. The silica gel has been modified with several kinds of gas chromatography stationary phases. Among these, PEG 2000 shows fairly good effect when using 80-100 meshes silica gel for the separation of mixture of methane, ethane, ethylene, acetylene, propane, propylene and n-, i-butane. The different behavior of silica gel between batch to batch is also found. When silica gel is coated with a small amount of Al2O3 prepared with sol-gel method, better resolution has been observed on a 2-meter column compared with the non-modified silica gel.

NMR study on the acidity of TS-1 zeolite

The acidic properties of TS-1 and Silicalite-I zeolites have been investigated by the solid-state MAS NMR technique capable of in situ sample pretreatment. As shown by a combination of the P-31 MAS NMR and H-1 MAS NMR techniques with trimethylphosphine, not only Bronsted acid sites but also Lewis acid sites exist in the TS-1 zeolites. Moreover, TS-1 zeolite is more acidic compared with Silicalite-1. The H-1, Si-29 MAS NMR spectra and the resonance related to Bronsted acid species in the P-31 MAS NMR spectra demonstrate clearly that the presence of titanium in the framework results in the formation of a new hydroxy group, titanols, which is more acidic than silanols of Silicalite-1. The P-31 MAS NMR measurements also illustrate convincingly the existence of at least two different Lewis acid species on the TS-1 zeolites. The conversion of propylene oxide into methoxypropanol catalyzed by TS-1 or Silicalite-I zeolite in methanol solution as a test reaction has also been described. With the increase of titanium in zeolite, TS-1 appears to have a higher activity during the reaction of propylene oxide to methoxypropanol.

Synthesis of titanium silicalites in different template systems and their catalytic performance

Titanium silicalites have been synthesized in the TPABr+ammonia, TPABr+hexanediamine, TPABr+ethylenediamine, TPABr+diethylamine, TPABr+TEAOH, TPABr+n-butylamine, TPABr+TBAOH and TBAOH+n-butylamine systems. As-synthesized titanium silicalites were characterized by XRD, IR and C-13 CP MAS NMR. Catalytic performance in epoxidation of propylene and template effect was investigated. It has been shown that both TPABr and TBAOH serve as templating agent in TPABr+TBAOH system. But in other systems, when there is enough TPABr, organic amines or ammoniums only act as the bases. TEAOH or n-butylamine can take the role of template when less TPABr is added. It indicates that the ability of organic amines or ammoniums to direct the Pentasil structure decreases as follows: TPA(+)>TBA(+)>TEA(+)>n-butylamine. Catalysts exhibiting good performance in epoxidation of propylene can be attained using TPABr as the template and ammonia, n-butylamine, diethylamine, hexanediamine or TBAOH as bases. (C) 1999 Elsevier Science B.V. All rights reserved.

Development and application of oxygen permeable membrane in selective oxidation of light alkanes

In this paper, oxygen permeable membrane used in membrane reactor for selective oxidation of alkanes will be discussed in detail. The recent developments for the membrane materials will be presented, and the strategy for the selection of the membrane materials will be outlined. The main applications of oxygen permeable membrane in selective oxidation of light alkanes will be summarized, which includes partial oxidation of methane (POM) to syngas and partial oxidation of heptane (POH) to produce H-2, oxidative coupling of methane (OCM) to C-2, oxidative dehydrogenation of ethane (ODE) to ethylene and oxidative dehydrogenation of propane (ODP) to propylene. Achievements for the membrane material developments and selective oxidation of light alkanes in membrane reactor in our group are highlighted.

New route for light olefins production from chloromethane over HSAPO-34 molecular sieve

HSAPO-34 molecular sieve was employed in chloromethane conversion and showed high performance in activity and selectivity in production of light olefins. Our detailed IR investigation allowed the identification of the active sites and the adsorbed species and demonstrated that the conversion started from 350 degrees C with alkoxy group as the intermediate. The fixed-bed catalytic testing evidenced that in the range of 350-500 degrees C, 70-80% of chloromethane was transferred to ethylene, propylene and butenes. Increasing reaction temperature favors the conversion and enhances the yield of lighter olefins. A very important reversible phenomenon, the breaking of Al-O-P bonds upon adsorption of HCl, a main product of reaction to generate a large amount of P-OH groups and the recovery of Al-O-P upon removal of HCI was revealed. (c) 2005 Elsevier B.V. All rights reserved.