Qualitative Alteration of Phospholipids in Beef Patties Cooked After Vacuum and Nonpackaged, Frozen Storage

Alterations during frozen storage of the phospholipids in high quality and very lean (7.5% fat) beef patties as influenced by vacuum packaging were studied. Meat was obtained from a closely trimmed semimembranosus muscle from a U.S. Choice Grade steer carcass. Ground patties were stored 3 days, 1.5, 3, and 4.5 months at -23 ± 1°C. Lipids were extracted after the patties were thawed and cooked. After the 3 days of frozen storage, the vacuum packaged samples indicated the presence of eight different phospholipid classes in decreasing concentration: phosphatidylcholine, phosphatidylethanolamine, sphingomyelin, lysophosphatidylcholine, phosphatidylserine, phosphatidylinositol, lysophosphatidylethanolamine, and diphosphatidylglycerol, in the nonpackaged samples; diphosphatidylglycerol and lysophosphatidylethanolamine were absent. As storage progressed, the amount of certain phospholipid classes, particularly in the nonpackaged samples, declined. After 3 months of storage in both packaged and nonpackaged samples, trace amount of lysodiphosphatidylglycerol became evident.     

端面铣削工件表面粗糙度数学模型与实验验证

目的 针对多种表面粗糙度影响因素的耦合作用使轮廓形成机理不清,导致表面粗糙度数学模型存在表面质量智能管控工业应用预测精度不足的技术难题,建立端面铣削工件表面粗糙度数学模型。方法 首先,基于加工运动学机理和刀具几何学分析端面铣削工件表面轮廓形成机理,建立考虑刀具跳动的工件表面轮廓模型以及轮廓高度偏差关于铣削力的补偿函数,并通过卷积神经网络(Convolution Neural Network,CNN)进行解析。其次,建立端面铣削表面粗糙度数学模型。最后,进行可转位面铣刀端面铣削ZG32MnMo的实验验证,分别采集轮廓数据与铣削力信号,建立以铣削力为输入、轮廓高度偏差数据为输出的铣削数据集,训练卷积神经网络解析轮廓高度补偿值并验证理论模型的准确性,对比分析考虑刀具跳动的表面粗糙度数学模型与CNN优化考虑刀具跳动的表面粗糙度数学模型的精度。结果 CNN优化考虑刀具跳动的表面粗糙度数学模型对加工重叠区与非重叠区内沿刀具进给方向的轮廓算术平均偏差Ra的预测误差分别为18.71%和14.14%,与考虑刀具跳动的表面粗糙度数学模型相比,精度分别提高了10.61%和32.83%,CNN优化考虑刀具跳动的表面粗糙度数学模型对轮廓单元的平均宽度Rsm和支承长度率Rmr(c)的预测结果与实验值吻合。结论 考虑刀具跳动以及动态铣削力耦合作用边界条件的表面粗糙度数学模型能够有效预测端面铣削表面粗糙度,可为在质量管控工程中的应用提供理论指导与技术支撑。     

MICROBIOLOGICAL QUALITY OF WHEAT STORED UNDER DIFFERENT CONDITIONS IN TURKEY

Four different types of wheat storage systems are widely used in the Marmara region. The existing storage conditions were studied and changes in the microbiological quality of the stored wheat under these conditions were assessed.
Depending on the external conditions, ambient temperatures and relative humidities in the stores were 17–26°C and 50–65% RH during summer and 3–10°C and 62–83% RH during winter, respectively. The low relative humidity level during harvesting and subsequent storage was adequate for obtaining low levels of moisture content and water activity in the produci for safe storage. The increase in relative humidity of the air during winter months did not affect the moisture content of the product considerably and the low temperature prevented mold growth. Therefore, all of the four different storage facilities were suitable for safe storage of grain for a period of one year without significant losses in quality due to microbiological load.     

Investigation of diffusion kinetics of plasma paste borided AISI 8620 steel using a mixture of B 2 O 3 paste and B 4 C/SiC

In the present study, AISI 8620 steel was plasma paste borided by using various B₂O₃ paste mixture. The plasma paste boriding process was carried out in a dc plasma system at temperatures of 973, 1023 and 1073 K for 2, 5 and 7 h in a gas mixture of 70% H₂ -30% Ar under a constant pressure of 10 mbar. The properties of the boride layer were evaluated by optical microscopy, X-ray diffraction, Vickers micro-hardness tester and the growth kinetics of the boride layers. X-ray diffraction analysis of boride layers on the surface of the steel revealed FeB and Fe₂B phases. Depending on temperature and layer thickness, the activation energies of boron in steel were found to be 124.7 kJ/mol for 100% B₂O₃.     

鞣花酸对马兜铃酸I诱导小鼠急性肾损伤的保护作用

目的:研究鞣花酸(ellagic acid,EA)对马兜铃酸I(aristolochic acids I,AAI)诱导的急性肾损伤的保护作用.方法:40只昆明小鼠(雌雄各半)随机分为健康组、模型组(10?mg/kg?mb?AAI)、EA低剂量组(10?mg/kg mb?AAI+10?mg/kg?mb?EA)和EA高剂量...