青蛤凝集素CSL对酿酒酵母细胞形态的影响

通过研究青蛤凝集素CSL与酵母细胞壁肽聚糖的相互作用及CSL与酿酒酵母细胞结合后其表面积的变化,分析CSL对酿酒酵母细胞作用的影响。结果表明,固相吸附测试中,CSL可与酵母细胞壁肽聚糖结合,两者的结合具有浓度依赖关系,该结合位点受甘露糖（D-Mannose）及N-乙酰-D-半乳糖胺（N-acetyl-D-galactosamine）的抑制。CSL与酿酒酵母细胞壁相互作用,导致了它的表面积发生了改变,这表明其细胞壁发生了变化。对照组与CSL添加组两组酵母菌内的Ca²⁺含量未发生明显变化。扫描电镜观察表明,对照组酵母细胞表面较圆润光滑,CSL添加组酵母细胞表面有较多赘附凸起。研究结果为CSL促进酵母发酵能力的机理提供基础数据。      

杨木纤维/聚乙烯复合材料拉伸性能微观力学模型

制备了不同杨木纤维含量的杨木纤维/聚乙烯复合材料,利用Hirsch模型、Kelly-Tyson模型和Bowyer-Bader模型对杨木纤维/聚乙烯复合材料的微观力学进行建模,通过对杨木纤维/聚乙烯复合材料及塑料基体的拉伸应力-应变曲线和杨木纤维长度分布的研究,计算得到杨木纤维在聚乙烯基体中的取向系数、界面剪切强度和本征抗拉强度,解释了杨木纤维/聚乙烯复合材料拉伸性能的变化规律。此外,利用微观力学模型计算得到了亚临界纤维、超临界纤维、塑料基体对杨木纤维/聚乙烯复合材料拉伸强度的贡献比例。     

加压溶剂法提取紫色马铃薯中花色苷的工艺优化

以紫色马铃薯粉为原料,使用加压溶剂提取的方法萃取紫色马铃薯中的花色苷。探讨提取时间、提取温度、料液比和提取剂的浓度对花色苷提取率的影响,并通过响应面法确定了最佳提取工艺参数为乙醇浓度为77%,提取温度为67℃,提取时间为25 min,料液比为1∶58,在最优条件下的花色苷提取量为200.13 mg/100 g。超声波辅助提取法提取紫色马铃薯中的花色苷,其最佳工艺条件下提取花色苷量为139.30 mg/100 g,加压溶剂法提取量高于超声波辅助提取法。      

Stress-field in a bone medium having a star-shaped crack

The stress-field in a bone medium containing a star-shaped crack is analytically studied. The anisotropy of osseous tissues (as per previous experimental observations) has been taken into account. The star-crack is formed by the interaction of a number of Griffith cracks of equal lengths when the face of the crack is subjected to a prescribed pressure. By choosing a suitable Airy stress function, a fourth order differential equation is derived from the compatibility relations. By using the Mellin transform method, this equation is solved. The boundary conditions reduce the problem to that of solving a pair of dual integral equations. The dual equations are then reduced to a Fredholm integral equation of the second kind, which is solved by resorting to numerical techniques. Numerical computation is made for studying the variation of the stress-field in the bone medium in the vicinity of the crack. The effect of bone anisotropy on the intensified stress-field is also studied.     

水泵汽蚀防护措施的研究现状

介绍了水泵汽蚀现象、危害及影响因素,对水泵汽蚀防护的各种措施进行了阐述.     

预防组培中蓖麻子叶节玻璃化的研究

为了预防蓖麻子叶节在组织培养过程中的玻璃化现象,以建立其高效的遗传转化体系,本实验对影响子叶节生长状态的几个因素进行了初步研究。结果表明,在胚轴、子叶均为淡黄色的时期切取蓖麻子叶节,接种在1/8MS、内含10g/L琼脂粉、20g/L蔗糖、8.0mg/LZT、1.0mg/LNAA的培养基中进行培养,能有效地预防蓖麻子叶节玻璃化。     

超滤浓缩制备南瓜果胶的工艺研究

采用超滤浓缩后乙醇沉淀的方法制备南瓜果胶.通过单因素试验,确定优化超滤条件为:超滤膜截留分子量50 kD,压力0.08 MPa,温度25 ℃,溶液pH 7.0;在该条件下,将南瓜果胶提取液浓缩至原体积1/5,再加入80%乙醇溶液沉淀果胶并洗涤果胶1次,所得的南瓜果胶纯度为80.08%,得率为8.50%,凝胶度为120.25,酯化度为31.82,干燥失重为4.26%,总灰分为3.22%,半乳糖醛酸为88.10%,pH为2.7,铅及砷含量分别为1.2 mg/kg和0.036 mg/kg,各项指标均达到国家质量标准QB 2484--2000.     

米尔贝霉素毒理学研究进展

简要介绍了生物农药米尔贝霉素（milbemectin）毒理学研究进展,包括急性毒性、慢性毒性以及致畸性研究等,为其相关研究提供参考。     

超高效液相色谱-串联质谱法测定土壤、蔬菜及水果中苯醚甲环唑和丙环唑残留

建立了超高效液相色谱-串联四极杆液质谱联用(UPLC-MS/MS)检测土壤、番茄、茄子、梨和香蕉中苯醚甲环唑和丙环唑的残留分析方法.样品采用乙酸乙酯提取,弗罗里硅土固相萃取柱净化,超高效液相色谱分离多反应监测模式下测定,外标法定量.结果显示:苯醚甲环唑和丙环唑的线性关系良好.苯醚甲环唑和丙环唑在不同基质中平均回收率分别为79.7%～107.1%和72.8%～104.6%,相对标准偏差分别为0.7%～13.1%和2.7%～18.9%.最低检出质量分数均为0.001 mg/kg.     

Inhibitory effects of garlic and other spices on biogenic amine production in Myeolchi-jeot,Korean salted and fermented anchovy product

This study was carried out to reduce biogenic amine contents in Myeolchi-jeot, Korean salted and fermented anchovy (Engraulis japonicus). The effects of a variety of spices including ginger, garlic, green onion, red pepper, clove and cinnamon, on biogenic amine production were determined by HPLC. The greatest inhibitory effect on biogenic amine production was observed in the culture treated by garlic extract. In the culture, the contents of putrescine, cadaverine, histamine, tyramine and spermidine were reduced by up to 11.2%, 18.4%, 11.7%, 30.9% and 17.4%, respectively, compared to control. The other spice extracts tested showed less or no effect in reducing biogenic amine contents. In addition, the extract of garlic showed the highest antimicrobial activity against the amine producers tested. The extract of garlic at a concentration of 5% (weight basis) was finally applied to the ripening of Myeolchi-jeot in situ, and then overall production of biogenic amines in Myeolchi-jeot was found to be reduced by up to 8.7%, compared to control. Consequently, it is expected that the findings of this study might be helpful for enhancing the safety of Myeolchi-jeot.