Comparison of rancimat evaluation modes to assess oxidative stability of fish oils

Two Rancimat evaluation modes, the induction period (IP), and the time needed to achieve a selected difference in conductivity (tΔK) were compared for assessing relative stability of anchovy, sardine, and hake liver oils. Mean coefficients of variation were 2.5 and 2.4% for IP and tΔK values, respectively, for oils oxidized in the range 55–90°C. Natural logarithms of IP and tΔK values varied linearly with temperature (P<0.001). A linear relationship (r=0.999) was established between the IP and tΔK values (P<0.001). Relative oxidative stability of fish oils was determined with the same degree of confidence by either IP or tΔK values.     

High-pressure effects on lipid oxidation

Rendered pork fat (0.44 water activity, A_w) was subjected to high-pressure treatment of 800 MPa for 20 min at 19°C prior to storage at 4, 25, and 50°C. In all cases, high pressure-treated samples oxidized more rapidly (had a shorter induction period) as shown by the peroxide value (PV), 2-thiobarbituric acid value, and ultraviolet absorbance. The effect was less marked at lower pressures. In contrast, at all water activities outside the range of 0.40–0.55, the PV of the high pressure-treated pork fat was lower than control samples stored similarly, and the PV of rancid fat decreased slightly on pressure treatment at 19°C, but not at higher temperatures. This effect may explain the observed inhibition of oxidation at most water activities. At 0.40–0.55 A_w, other factors, such as the liberation of transition metals, may override the destruction of peroxides.     

水解酸化—填料式SBR技术处理啤酒废水

采用水解酸化－填料式SBR工艺处理啤酒废水。处理后出水水质达到GB8978－96国家污水综合排放标准。     

Approach to the Synthesis of Dimeric Salen-Co(Ⅲ):A Recoverable Catalyst for Rac-Eprichlorohydrin HKR

The synthesis of chiral dimeric Salen ligand 5, 5＇-methylene-di-[（R, R ）-｜ N-（3-tert-butylsalicylidine）-N＇- （ 3＇, 5＇-di- tert-butylsalicylidene） ｜ - 1, 2-cyclohexanediamine ] which using 2-tert-butylphenol as starting material is reported. This compound reacts with cobalt （Ⅱ） acetate and then oxidized by air to give dimeric Salen catalyst 5 in this paper, which catalyzes the hydrolytic kinetic resolution （HKR） of racemic epichlorohydrin to afford biologically important chiral epoxides and diols. Ee values of diol up to 97 % were obtained, and the catalyst was recovered with no apparent loss.     

水解酸化—生物接触氧化法处理制药废水

为处理制药废水,经多方案比较决定采用水解酸化—生物接触氧化法处理工艺。通过水解酸化可提高废水的可生化性,便于进一步降解有机污染物,充分发挥生物接触氧化法的作用,从而能保证COD、BOD、SS等达标排放。     

高档原纸生产废水处理工艺设计和运行

结合某工程实例,就高档特种原纸生产废水处理的工艺选择进行了探讨,提出了清污分流、分别处理的工艺路线,其中造纸废水采用浅层气浮的物化处理方式,涂布废水采用水解 SBR的生物处理方式,并简述了各构筑物的设备配置、设计参数及调试情况。运行结果表明,该工艺处理效果较好。     

Solubility and viscosity of herring (Clupea harengus) proteins as affected by freezing and frozen storage

ABSTRACT:  The aim of this work was to evaluate the effects of freezing and frozen storage at –24 °C on the quality of Icelandic herring fillets, focusing on protein solubility and viscosity at pH 2.7 and 11 used for pH-aided protein isolation. The evaluation of quality was based on chemical analyses, protein degradation measurements, and changes in protein solubility and viscosity at pH 2.7 and 11 after up to 6-mo frozen storage of the herring fillets. Lipid oxidation measured as TBARS values increased significantly during the frozen storage ( P < 0.05). Protein solubility at pH 2.7 decreased during frozen storage for 6 mo, where the solubility was about 10% lower after 6-mo frozen storage compared to the beginning ( P < 0.05). At pH 11, the solubility became approximately 15% lower after 6-mo frozen storage compared to initial solubility ( P < 0.05). Viscosity, measured at pH 2.7, increased after 3 mo of frozen storage ( P < 0.05). At pH 11, the viscosity increased significantly after 1-wk frozen storage, compared to fresh herring fillets, but did not increase significantly with further storage ( P < 0.05). Changes found in solubility and viscosity indicated protein degradation due to freezing and frozen storage. SDS-PAGE analysis did not reveal any protein cross-linking or aggregation formation, either with frozen storage or due to exposure to low pH.     

有机酯类合成润滑油水解安定性的研究

研究了抗磨剂、抗氧剂和防腐剂对酯类油水解安定性的影响,发现有机胺类化合物能提高酯类油的水解安定性。     

PA6／EHDPET共混纤维的形态结构

将聚酰胺６（ＰＡ６）与易水解性聚酯（ＥＨＤＰＥＴ）以体积比７／３的比例在工业规模的生产装置上进行熔体共混纺丝,再经拉伸→定型→卷曲→切断等切加工制得短纤维。用扫描电镜观察了共混纤维经碱水解及甲酸溶解后的形态结构,确认经碱水解处理后的纤维呈多孔中空藕状,而甲酸溶解后则呈超细纤维状,因此原共混纤维是以ＰＡ６为连续相,以ＥＨＤＰＥＴ为分散相的海－岛型复合纤维,并从流变学实验结果解释了该结构的成因。     

Poly(ester amide)s derived from tartaric and succinic acids: Changes in structure and properties upon hydrolytic degradation

The changes in structure and properties taking place in a set of tartaric acid‐based polyamides and poly(ester amide)s upon hydrolytic degradation were examined. Poly(hexamethylene 2,3‐di‐O‐methyl‐L ‐tartaramide)s, either pure or containing minor amounts of succinate ester groups (≤10%), were exposed to humidity or incubated in buffered water at pH 7.4 and 37°C, and their thermal and mechanical properties were evaluated as a function of time. Both moisture uptake and hydrolysis induced a noticeable decay in the tensile properties of polymers. These effects were greatly enhanced by the presence of ester groups, whereas no large differences were noticed for changes in the enantiomeric composition. Variations in the glass transition temperatures and melting points appeared to be slight, whereas crystallinity clearly increased with incubation time. The latter effect was most apparent in poly(ester amide)s with a nearly racemic composition, in which a crystal‐to‐crystal transition was observed to take place upon degradation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 486–494, 2000