顶空固相微萃取气相色谱/质谱法测定 "米邦塔"仙人掌挥发性成分

用顶空固相微萃取方法收集仙人掌的挥发性成分。所得到的仙人掌挥发性成分用气相色谱-质谱(GC-MS)法分离并分析鉴定其成分及质量分数,共鉴定出47个化合物,主要为酸、醛、脂类和酮类物质,其中酸类物质41.99%;醛类物质20.15%;醇类物质19.92%;酯类物质4.25%;酮类物质3.43%。此外还鉴定出4种胺类物质(2.22%),1种酚类物质(0.80%),1种呋喃类物质和2种硫化物(1.46%)。     

巴西蘑菇菌丝体中抑瘤活性甾醇的分离和结构鉴定

筛选巴西蘑菇菌丝体醇提物中的抗肿瘤活性成分。巴西蘑菇深层发酵的菌丝体，在用热水提取出水溶性成分（主要是活性多糖）后，对其残渣用85％的乙醇提取，以S180荷瘤鼠为模型，对乙醇提取物进行抑瘤活性为导向的分级。先用丙酮、正己烷分步提取，再经硅胶柱层析进一步分级，并对分离出的高抑瘤活性组分，利用紫外、红外、质谱和NMR进行结构鉴定。根据抑瘤活性大小分步提取，最后经硅胶柱层析后，分离出6个组分，其中组分3抑瘤活性最强，腹腔注射（i．P．）50mg／kg／d，对S180荷瘤鼠的瘤重抑制率达78．30％。组分3在石油醚（60℃-90℃）中反复结晶得淡黄色结晶体，经波谱解析，确定为麦角甾醇。巴西蘑菇菌丝体醇提物中的主要抗肿瘤活性成分是麦角甾醇。     

Effects of nitrogen source and carbon/nitrogen ratio on batch fermentation of glutathione by Candida utilis

Several inorganic/organic N-containing substances were tested as nitrogen source for efficient glutathione production by C. utilis WSH 02-08. Although the strain could assimilate all the inorganic/organic nitrogen, urea and ammonium sulfate were found more favorable to cell growth and glutathione biosynthesis in a flask, respectively, and an optimal C/N ratio existed for each as 5.6 mol/mol and 8.3 mol/mol. A mixed nitrogen source of urea and ammonium under diverse C/N ratios could not boost glutathione fermentation despite the many mixed strategies that were introduced. Batch glutathione production in a stirred fermentor, using the sole or mixed nitrogen sources of urea and ammonium sulfate under their optimal C/N ratios, were conducted; urea was further proved to be the best nitrogen source for glutathione production. The reason was then quantitatively described by kinetic model, together with the distribution of flux for metabolites in metabolic network of glutathione biosynthesis by C. utilis WSH 02-08.     

面料性能与翻领直上尺寸的相关性研究

面料性能是影响翻领直上尺寸的重要因素之一,本文对10种不同面料的主要性能参数与翻领直上尺寸之间的关系进行了测试和分析.结果表明:面料拉伸回弹性、压缩回弹性及单位面积质量对直上尺寸的影响较大;拉伸回弹性、压缩回弹性越大,直上尺寸越小;单位面积质量越大,直上尺寸越大.     

磁控溅射工艺参数对涤纶织物表面沉积铜膜性能的影响

在室温条件下采用射频磁控溅射法在涤纶平纹机织物表面沉积纳米Cu薄膜,借助原子力显微镜(AFM)观察镀膜前后样品表面变化。通过分别改变镀膜时间、溅射功率和气体压强,研究其对样品透光性和导电性的影响。实验结果表明,经Cu镀层处理的涤纶平纹织物对紫外光和可见光的吸收能力明显优于原样。溅射压强增加,透光性能增强,铜膜方块电阻增加,导电性能减弱;镀膜时间延长和溅射功率增加,样品透射率降低,屏蔽紫外线和可见光效果明显,在溅射时间接近15min和溅射功率增加到120W后,样品屏蔽效果不明显,铜膜方块电阻随溅射功率增加而减小,导电性能增强。     

Manufacturing, properties and shelf life of labneh: a review

Labneh is a concentrated yogurt widely produced and consumed in the Middle Eastern countries and Balkans.
This review focuses attention on the different manufacturing methods of labneh and its quality in terms of microbiology, rheology, sensory and nutrition. The shelf life of this healthy milk-derived product is also discussed in this review.     

光脉冲在非啁啾光纤光栅中的透射传输研究

基于均匀布拉格光纤光栅的色散特性,阐述丁激光啁啾脉冲的传输演变特性,研究了工作于传输方式的非啁啾光纤光栅的透射传输特性。讨论了光源线宽、光栅长度、光栅耦合系数等光栅参数以及初始脉宽、初始啁啾等参量对补偿光纤长度的影响,通过理论计算和模拟实验研究光栅对脉冲的补偿能力。     

Lipase-catalyzed synthesis of O-lauroyl l-serinamide and O-lauroyl l-threoninamide

O-Lauroyl l-serinamide and O-lauroyl l-threoninamide were synthesized with an immobilized lipase using lauric acid and l-serinamide or l-threoninamide in water-miscible organic solvents, of which 2-methyl-2-propanol gave the highest conversion of 93% for O-lauroyl l-serinamide at 50 mmol-l-serinamide/L and 100 mmol-lauric acid/L. The addition of 4 Å 1/16 molecular sieves at 50 mg/mL increased the conversion to 53% for O-lauroyl l-threoninamide at 50 mmol-l-threoninamide/L and 150 mmol-lauric acid/L in 2-methyl-2-butanol. The difference of conversion between the two products was exactly proportional to the difference of solubility of aminoacid amides.     

Effects of modified atmosphere packaging with various sizes of silicon gum film window on the storage of Agrocybe Chaxingu Huang and the modelling of its respiration rate

An Agrocybe chaxingu Huang packaged in 5% O₂‐ and 10% CO₂‐modified atmospheres with different sizes (0, 0.5, 1.0 and 1.5cm²) of silicon gum film window was stored at a temperature of 3 ± 1°C for 20 days. Changes of ascorbic acid content, titratable acidity, electrolyte leakage and sensory characteristic were evaluated. Significant differences were found among the packages with different sizes of silicon gum film window on ascorbic acid content, titratable acidity, electrolyte leakage, general appearance, firmness and odour after 8, 8, 12, 12, 12 and 4 days of storage, respectively. The package with a 1.0cm² silicon gum film window was the most effective for keeping the quality of Agrocybe chaxingu Huang. Based on the optimum storage condition in this study, an enzyme kinetics respiration model was set successfully and the applicability of the enzyme kinetics respiration model was verified by using the packages of Agrocybe chaxingu Huang with weights of 105 and 125g, respectively. Copyright © 2007 John Wiley & Sons, Ltd.     

一种新的虹膜定位算法

提出了一种新的虹膜预处理方法，即使用联合扩散滤波器对虹膜进行平滑处理，利用其保边光滑的特性提取虹膜内边缘的若干点，再使用3点确定圆心的方法计算虹膜圆心，最后使用标准Hough变换进行小范围精确定位。仿真结果显示，该算法性能优于文献中提出的算法，稳定性、速度和精度已经达到较高程度。