PCR identification of ruminant tissue in raw and heat-treated meat meals

To control the spread of bovine spongiform encephalopathy in cattle through contaminated animal feedstuffs, screening of feed products is essential. We designed five pairs of primers to identify specifically raw and heat-treated tissue from cattle, sheep, goat, deer, and ruminants in general. A forward common primer was designed based on a conserved DNA sequence in the mitochondrial 12S rRNA-tRNA(val)-16S rRNA gene, and reverse primers were designed to hybridize with a species-specific DNA sequence for each species considered. All primers were developed to create a specific PCR product small enough (less than 200 bp) to be suitable for heat-treated material. To evaluate the effect of heat treatment, a severe sterilization condition (133 degrees C at 300 kPa for 20 min) was chosen. Species-specific amplicons were obtained from all types of heat-treated meat meals. Analysis of laboratory-contaminated vegetable meals revealed that the detection limit of the assay was 0.05% for each species analyzed. This PCR-based analysis can be used as a routine method for detecting banned animal-derived ingredients in raw and heat-treated feedstuffs.     

L-鸟氨酸发酵培养基的中心复合法优化

考察不同碳氮源对Corynebacterium glutamicum1006发酵产L-鸟氨酸的影响,并借助于statistica6.0数学分析软件,采用Plackett-Burman试验设计及中心复合试验设计分析法,对L-鸟氨酸产生菌1006进行了发酵培养基的优化研究。优化后的发酵培养基使1006菌株的L-鸟氨酸产率提高了44.03%。     

营养因子对大肠杆菌发酵产转氨酶的影响

运用“单一组分缺失法”研究了18种氨基酸,11种维生素,8种微量元素,4种嘌呤与嘧啶对大肠杆菌A5发酵产转氨酶的影响。结果表明,L-甲硫氨酸是菌体生长与产酶所必需的物质,L-缬氨酸、L-异亮氨酸和L-谷氨酸分别对菌体生长和酶转化得率的提高有显著的促进作用。在此基础上构建了一个改良的合成培养基,其组成为(g/L):葡萄糖20,(NH4)2SO45,MgSO40.5,NaCl0.5,K2HPO40.5,KH2PO40.5,氨基酸混合液(包括L-Met、L-Val、L-Ile、L-Glu)0.6,pH7.2,所产转氨酶的转化得率达到72.4%。     

Impact of Aspen Log Storage with and without Protection on OSB Performance

Outdoor log storage without protection can change the mechanical and chemical properties of wood due to infection by various fungi. To understand how outdoor log storage affects the wood and, subsequently, the strandboard quality, two piles of aspen logs were set up outside and stored for a period of four months (July to November). One of the piles was treated with a biological solution to prevent fungal growth. The other one was stored without treatment. Both piles contained non-debarked and partially debarked logs. Evaluation of sap stain development indicated that all logs had been colonized by staining fungi with average stain coverage of 9.37 to 57.18% and maximum stain penetration of 3.58 to 7.27 cm over the log cross section. The variation of fungal colonization depended on log treatment and bark condition. The most effective way to prevent stain growth was the combination of biological treatment and partial debarking. A series of strandboard was prepared from fresh and aged aspen logs. All boards made from stored logs were statistically comparable to or superior to the control boards made from fresh aspen logs. The boards made from treated/partially debarked and untreated/non-debarked logs were statistically comparable to each other except for wet MOR. In addition, these two board types were statistically stronger than other boards made from treated/non-debarked and untreated/partially debarked logs in terms of IB and water resistance. Some individual stained strands were observed on the finished board surface. Less staining was found in the boards prepared from biologically treated and partially debarked logs, compared with those made from other stored logs.     

用纳米材料改善免处理胶辊的纺纱性能

介绍了纳米材料的选用及其工艺性，阐述了应用纳米级补强材料可改善免处理胶辊的纺纱性能如表面活性、抗静电性、抗污染性及精磨后的表面状态。针对免处理胶辊纺纱所需要的力学性能、技术问题进行了科学的分析与研究，提出含纳米材料的免处理胶辊具有持续稳定的可纺性能，特别是适纺状态的表面技术特性对纺纯棉纱的综合质量水平有所提高。     

“迷魂药”揭秘

人们经常听说“蒙汗药”或者“迷魂药”——在许多中国古典小说中．外国小说中．武侠小说中又或者在一些现实的刑事案件中。这种“迷魂药“或“蒙汗药”效果神奇，人若吃了．便会昏睡过去犹如死人：或者神志迷离．任人摆布…… 究竟是什么药．竟有如此神奇的效果？     

浅谈方便面质量控制

我国方便面市场发展不平衡,质量存在较大差别,本文旨在从原辅材料、生产工艺和设备、产品外观包装及调味等方便,对方便面质量控制加以阐述。     

光引发剂对UV丝印光致变色油墨固化性能的影响

UV丝印光致变色油墨体系中主要包括了预聚物、单体、光致变色材料、光引发剂等成分,而此油墨的固化是在UV光源的照射下,引发具有化学反应活性的液态物质快速转变为固态的过程,光引发剂在此化学反应中的作用就是引发这种反应进行,因此,它是油墨体系中直接影响着油墨固化性能的主要成分之一。通过改变光引发剂的含量和种类,分别制备油墨,并测试油墨的固化速度,从而研究光引发剂对油墨的固化性能的影响。实验表明当光引发剂的含量为10%的时候,油墨的光固化性能最好。另外选出三种固化性能最好的光引发剂184、907和BP进行配方实验,结果表明由光引发剂907所制备的油墨具有最好的固化性能,并且,最佳的固化速度为68m/min(固化功率:100W/cm)。     

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目前,由于缺少直接测量水力裂缝长度及导流能力等重要参数的手段,而地下水力裂缝的存在总要反映到油气井压力与产量的变化上来,特别是压力与产量随时间的变化速度与水力裂缝的长短、导流能力的大小等参数有直接关系。在常规压裂井试井分析过程中,所使用的数据主要是停泵后的压降数据,而岩石发生破裂到停泵前这一段压裂施工压力数据则没有得到有效利用;同时,在压裂施工作业过程中也不能对裂缝的延伸状况进行动态监测。文章提供了裂缝模型的诊断技术,通过对岩石发生破裂到停泵前这一段压裂施工压力数据进行分析,确定裂缝参数随压裂时间的变化关系。这样,就可以实时地知道裂缝发育、发展和闭合的过程,对于正确指导压裂施工作业以及获得优质裂缝具有十分重要的意义。     

Sedidrill 110S型履带式地震钻机介绍

文中对Sedidrill 110S型履带武钻机的结构、主要技术参数以及使用中的注意事项进行了介绍。