两种饲养条件对苏尼特羊肉营养品质的影响

以舍饲、放牧两种饲养方式下的12 月龄苏尼特羊不同部位的肌肉为实验材料,取股二头肌、背最长肌、臂三头肌3 个部位,测定其屠宰后45 min和24 h的pH值,分别测定其灰分、蛋白质、脂肪、硫胺素、还原糖及矿物质含量并进行比较分析。结果表明：屠宰后45 min,舍饲的苏尼特羊肉的pH值显著高于放牧（P＜0.05）,24 h后,与放牧的相比没有显著差异,舍饲苏尼特羊肉中的脂肪含量高于放牧,而放牧苏尼特羊肉中的蛋白质、灰分、硫胺素、还原糖含量高于舍饲,并且不同的矿物质之间在苏尼特羊体内吸收有一定的相关性。放牧比舍饲更有利于苏尼特羊体内蛋白质、矿物质、还原糖等营养成分的积累,从而使其羊肉的营养成分更丰富,品质更佳,具有更高的营养价值。     

Finite element analysis of the effect of micro-pore defect on linear friction welding of medium carbon steel

Micro-pore is a very common material defect. In the present paper, the temperature fields of medium carbon steel joints with and without micro-pore defect during linear friction welding （LFW） were investigated by using finite element method. The effect of micro-pore defect on the axial shortening of joints during LFW was examined. The x- and y-direction displacements of micro-pore during the LFW process were also studied. In addition, the shape of micro-pore after LFW was observed. The heat conducted from the weld inteace to the specimen interior. The fluctuation range of the temperature curves for the joint with micro-pore is larger than that without micro-pore. Position of micro-pore changes with the change of the friction time. The circular shape of micro-pore becomes oval after welding.     

Co-delivery honokiol and doxorubicin in MPEG-PLA nanoparticles

The combination chemotherapy is an important protocol in cancer therapy. Honokiol shows synergistic anticancer effect with doxorubicin. In this paper, honokiol and doxorubicin co-loaded MPEG-PLA nanoparticles were prepared. The particle size, morphology, in vitro release profile, cytotoxicity and cell proliferation study were studied in detail. The results indicated that honokiol and doxorubicin could be efficiently loaded into MPEG-PLA nanoparticles simultaneously, and could be released out in an extended period in vitro. Meanwhile, honokiol and doxorubicin in MPEG-PLA nanoparticle could efficiently suppress cancer cell proliferation in vitro. The described honokiol and doxorubicin co-loaded MPEG-PLA nanoparticle might be a novel anticancer agent.     

一起粪肠球菌引起食源性疾病暴发流行病学分析及分子溯源调查

目的调查某小型餐馆发生的一起食源性疾病暴发事件,分析事件发生的原因及危险因素,并提出预防措施。方法采用现场流行病学方法调查事件特征及危险因素,通过运用脉冲场凝胶电泳(PFGE)方法对致病因子进行同源性分析。结果共调查到5例病例,临床表现为腹泻、腹痛。调查结果提示中毒食物为2019年6月13日晚餐的卤鸡腿饭,现场卫生学调查提示可能的危险因素为卤鸡腿常温放置时间过久,供餐前重新加热时间不足。现场采样的3份病例肛拭子标本、1份卤鸡腿和1份切菜砧板棉拭样品均检出粪肠球菌,脉冲场凝胶电泳检测同源性为100%。结论食用受大量粪肠球菌污染的卤鸡腿是本次食源性疾病暴发的主要原因。建议加强小型餐馆从业人员食品安全意识,掌握正确的食品烹饪方法。     

Cascade Bioreactors Based on Host–Guest Molecular Inclusion Complexes for Triple-Negative Breast Cancer Therapy via Inducing Ferroptosis

Triple-negative breast cancer (TNBC) poses significant challenges in tumor treatment. Ferroptosis, as a novel cell death mechanism, holds promise as a potential therapeutic strategy for TNBC. In this study, cascade bioreactors based on host–guest molecular inclusion complexes (PCFP@PL/p53) are constructed for TNBC therapy via inducing ferroptosis. The bioreactors are composed of hydrophobic hemirotaxane (mPEG-β-CD/α-CD) and hydrophilic multi-branched polyethyleneimine-ferrocene (PEI-Fc). They are linked by the reactive oxygen species (ROS)-responsive molecular switch β-CD@Fc, which can be activated by high levels of ROS. This activation leads to the rapid disassembly of PCFP@PL/p53 and the subsequent release of the loaded piperlongumine (PL) and p53 plasmids. In addition to acting as a “switch,” Fc can react with hydrogen peroxide (H₂O₂) in a Fenton reaction to produce hydroxyl radicals. PL decreases intracellular reduced glutathione and induces H₂O₂ accumulation, which corporates with Fc to launch ferroptosis and activated p53. The activated p53 disrupts the SLC7A11-GSH-GPX4 pathway, further increasing the intracellular ROS levels, resulting in a cascade amplification of ROS that ultimately induces massive ferroptosis. Meanwhile, the PCFP@PL/p53-induced ferroptosis also activates the immune system in vivo, restricting the growth and metastasis of TNBC, thus providing a novel approach for TNBC therapy based on ferroptosis.     

分布式光伏项目国企开发模式及风险研究

分布式新能源发电低碳清洁、因地制宜、开发潜力巨大,是应对气候变化、化石能源资源枯竭和环境污染,推动能源革命,实现我国"30·60"双碳目标的重要途径.国有企业作为我国国民经济的中坚力量,对于促进我国分布式新能源快速健康发展具有不可替代的作用.文章系统梳理了我国分布式光伏产业的发展现状,总结了不同分布式光伏项目客户类型的...     

斜齿轮传动中啮合冲击数值研究

斜齿轮传动是一种应用广泛的机械传动形式,其啮合过程中存在冲击现象。使用MSC．Nastran的非线性仿真(SOL600)功能建立了斜齿轮啮合三维接触有限元分析模型,计算出冲击激励。使用瞬态响应分析法得到了斜齿轮在啮合冲击激励下的动力学特性,为斜齿轮传动系统的优化设计提供参考。     

线性摩擦焊IN718接头微观组织与织构演变

不同工艺参数下对IN718高温合金进行了线性摩擦焊接试验，采用OM，SEM，EBSD等对接头微观组织与织构进行了表征.结果表明，在摩擦压力169 MPa、振幅3 mm、频率35 Hz、摩擦时间6 s参数组合下获得的接头质量相对较好，但在焊缝端部仍能发现氧化物和碳化物.焊缝区δ相完全溶解，残留少量NbN；而热力影响区δ相部分溶解，部分晶界发生液化并伴有Laves相的产生.焊缝区发生了充分动态再结晶，呈现为等轴细晶组织，并在剪切力的作用下出现了明显剪切织构C（100）[011]，而热力影响区发生部分动态再结晶，形成了（335）[186]织构.     

Effects of annealing on microstructure, mechanical and electrical properties of AlCrCuFeMnTi high entropy alloy

The multi-component A1CrCuFeMnTi high entropy alloy was prepared using a vacuum arc melting process. Serial annealing processes were subsequently performed at 590 ℃, 750 ℃, 955 ℃ and 1 100 ℃ respectively with a holding time of 4 h at each temperature. The effects of annealing on microstructure, mechanical and electrical properties of as-cast alloy were investigated by using differential thermal analysis （DTA）, X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The experimental results show that two C14 hexagonal structures remain unchanged after annealing the as-cast A1CrCuFeMnTi alloy specimens being heated to 1 100℃. Both annealed and as-cast microstructures show typical cast-dendrite morphology and similar elemental segregation. The hardness of alloys declines as the annealing temperature increases while the strength of as-cast alloy improves obviously by the annealing treatment. The electrical conductivities of annealed and as-cast alloys are influenced by the distribution of interdendrite re~ions which is rich in Cu element.