梁端加强板构造对可更换耗能梁段受力性能的影响

为了改善可更换结构体系中可更换耗能构件的受力性能,提出一种梁端端板螺栓+加强板连接构造的可更换耗能梁构件。设计并制作了2个足尺的剪切屈服型可更换耗能梁试件,对其进行拟静力反复加载试验,并采用ABAQUS软件进行有限元模拟分析,探讨梁端连接构造对可更换耗能梁破坏模式、承载力、梁端塑性应变等特征的影响。试验结果表明：试件的破坏模式为腹板-加劲肋焊缝断裂或翼缘-端板焊缝断裂,试件具有良好的承载力和耗能能力;梁端加强板构造能有效转移梁端翼缘-端板焊缝区域的塑性应变,避免构件提前发生翼缘-端板焊缝断裂,导致无法满足其变形和震后可更换需求;有限元模拟结果与试验结果吻合较好,验证了有限元模型的有效性。对5类梁端加强板构造模型进行非线性分析,结果表明,该类梁端构造均能改善梁端翼缘-端板焊缝区域应力集中现象,优化其受力特征。提出可更换耗能梁梁端端板螺栓+加强板构造的设计方法,并通过有限元模型验证了其可行性。     

渝东南地区土家特色酸鲊肉制品质量评价指标体系的初步建立

目前渝东南地区酸鲊肉制品还没有相关的质量安全标准,本研究通过对市售酸鲊肉的感官评价、理化指标、微生物指标的测定和分析,同时参照其他肉制品的相关质量安全标准,初步建立酸鲊肉制品的特色质量评价指标体系,为质量安全标准的制定提供实验室参考数据。结果表明：品质良好的酸鲊肉制品除应满足其应该具有的感官品质要求外,还应满足水分含量≤43%,食盐（以NaCl计）含量≤6.0%,总酸（以乳酸计）含量≤1.80%,氨基酸态氮含量≥0.20%,亚硝酸盐含量≤30 mg/kg,组胺含量≤50 mg/kg,大肠菌群≤3.0 MPN/g,金黄色葡萄球菌≤3.0 MPN/g,沙门氏菌、单核细胞增生李斯特氏菌均不得检出。     

高职院校思想政治理论课“三全”教育模式探讨

高职院校思想政治理论课的“三全”教育模式,就是按照“全程、全面、全新”的要求扎实推进思政理论课改革,即从时空上体现全程性,从内容上体现全面性,从体系、方法、途径上突出全新性.     

我国传统酸鲊肉制品的研究现状及展望

我国传统酸鲊肉是一种乳酸细菌型发酵肉制品,具有众多营养特点和生理功能。该文对我国传统酸鲊肉的概念、特点、历史、加工工艺等进行概述,同时概括了发酵微生物种类及作用、传统酸鲊肉生产的安全隐患和安全限量标准（或指引）,最后对我国传统酸鲊肉制品的发展进行了展望,以期为我国传统酸鲊肉制品实现工业化、规模化、规范化生产提供理论参考。     

Recent developments in the enhancement of some postharvest biocontrol agents with unconventional chemicals compounds

BackgroundProduce are susceptible to microbial attack from diverse sources and the use of novel BCAs has gained recognition as alternative and sustainable applications to lessen the current emerging problems with synthetic fungicide use. Most researchers recommend the combination of two or more biocontrol agents in postharvest diseases control. To this end, the enhancement of biocontrol agents and the mechanisms of action in biocontrol systems have attracted many research interests. In this regard, there have been remarkable efforts to develop a multifaceted system approach for disease control.Scope and approachIt has been recognized that the various methods of biological control act together additively or synergistically to achieve significant commercial level of 97–99% disease control. The integration of microbial agents with a wide range of unconventional chemicals and their corresponding mechanisms of action to controlling postharvest fungal pathogens of fruits has been proven be successful.Key findings and conclusionsIn this review, the combined strategy of unconventional chemical compounds and other BCAs have contributed to varied degree of postharvest diseases control. The beneficial effects of these methods depend on the appropriate combination of the agents based on adequate knowledge of their mechanisms of action in the biocontrol system. Lastly, efforts to upscale these methods to commercial implementation level must be given the necessary consideration.     

HPLC法测定渝东南地区传统土家特色酸鲊肉中的组胺含量

建立测定渝东南地区传统土家特色酸鲊肉中组胺含量的高效液相色谱(high performance liquid chromatography,HPLC)方法,并进行样品中组胺含量的测定。以1,7-庚二胺为内标物,丹磺酰氯为样品衍生剂;Agilent C_(18)柱为固定相,70%甲醇和30%超纯水为流动相,于波长254 nm处进行紫外检测。用0.4 mol/L高氯酸溶液提取样品中的组胺,然后测定酸鲊肉中的组胺含量。结果表明:内标物和组胺标准品分别在4.335 min和7.723 min出峰,且分离效果良好。经实验验证,组胺盐酸盐标准品的峰面积和内标物峰面积的比值与组胺质量浓度之间存在良好的线性关系,样品加标实验回收率在98.5%~102.2%之间;仪器检出限为0.50 mg/L,定量限为1.00 mg/L,精密度相对标准偏差为1.0%。经检测10个样品中组胺含量在19.68~44.15 mg/kg之间,不同样品组胺含量有显著性差异(P0.05)。本研究表明HPLC方法的灵敏度和精密度较高,是检测酸鲊肉中组胺含量的可靠方法。     

楼板对钢筋混凝土柱-钢梁空间组合体抗震性能影响研究

楼板在地震作用下对钢筋混凝土柱-钢梁组合体抗震性能的影响是建立地震作用下节点计算模型的基础,也是准确评价组合结构体系抗震性能的关键问题之一。为此,完成了3个钢筋混凝土柱-钢梁(RCS)空间组合体试件在考虑不同楼板宽度情况下的抗震性能试验,分析整个受力过程中楼板受力性态对组合构件受力特征、破坏模式等抗震性能的影响。各试验模型在加载过程中均产生梁铰破坏,并表现出较好的延性和耗能能力,最终因节点区钢梁屈曲、扁钢箍开裂和柱端混凝土压碎而丧失承载力。分析表明,楼板裂缝以横向裂缝为主,随着楼板宽度增加,次生斜裂缝增多,板底混凝土压碎区域增大;混凝土楼板与钢梁组合体对节点核心区的约束作用较明显地改善了空间组合体受力性能。对楼板混凝土和板内纵筋在受力过程中的应变进行分析,结果表明,随着楼板宽度的增加,楼板对RCS空间组合体刚度、承载力的贡献值有限。对现浇板受拉有效翼缘宽度进行分析,结果表明考虑钢-混凝土组合梁翼缘有效宽度对梁端受弯承载力、惯性矩影响较大。     

Fractionation of polysaccharides by gradient non-solvent precipitation: A review

BackgroundAlmost all natural polysaccharides have wide molecular weight distribution and the complex heterogeneous polysaccharides may also exhibit variations in proportions of sugar constituents, linkage type, degree and arrangement of branching or degree of substitution. The heterogeneity of molecular weight and chemical structure restricts basic research and application of polysaccharides. Therefore, it is meaningful to fractionate polysaccharides into fractions with high homogeneity in molecular weight and chemical structure.Scope and approachCompared with chromatography and ultrafiltration, gradient non-solvent precipitation is inexpensive, has a wide application scope and can be easily scaled up or down as required. Therefore, this work reviews fractionation of polysaccharides by gradient non-solvent precipitation. Specifically, this work describes the commonly used non-solvents, fractionation mechanism of gradient non-solvent precipitation, how to establish the fractionation procedure, assessment of the fractionation effect and factors that affect fractionation.Key findings and conclusionsThis paper provides comprehensive and detailed directions for how to fractionate a new polysaccharide using this method. It is suggested to select a suitable non-solvent and establish the fractionation procedure according to the curve of the polysaccharide recovery as a function of the non-solvent concentration. Fractionation by gradient non-solvent precipitation is based on the difference in solubility of polysaccharides. Therefore, fractionation may be affected by the precipitation conditions and those factors that can affect the solubility of polysaccharides. During fractionation, those factors that negatively affect fractionation should be strictly controlled.     

响应面法优化地参发酵酒的工艺条件

以鲜地参、糯米为原料制备地参发酵酒,并采用单因素试验及响应面法对其发酵工艺参数进行优化。结果表明,最佳发酵工艺为：鲜地参、糯米经预处理后,将地参与糯米（干质量）按7∶3比例混匀蒸熟,摊凉后按照料液比1.0∶1.8(g∶m L)加水,接入0.50%的酿酒曲,在27℃下发酵9 d。在此优化条件下,地参发酵酒感官评分为87.69分,酒精度为10.37%vol,总糖含量为13.12 g/L,总酸含量为3.24 g/L;丹参素含量为26.06 mg/L,迷迭香酸含量为32.18 mg/L,咖啡酸含量为36.84 mg/L。地参发酵酒酒色呈橘红色,光泽透明,有地参特有的香气和米酒的清香,口感清甜纯正,和谐爽口,营养丰富,保健价值突出。     

分子蒸馏脱除核桃油中塑化剂工艺优化

为探索利用分子蒸馏脱除核桃油中塑化剂的合理工艺,采用单因素实验考察了蒸馏温度、进料速度和刮膜转速对核桃油中塑化剂DEHP和DBP脱除的影响,在此基础上以DEHP和DBP的含量为指标,运用响应面法对分子蒸馏脱除核桃油中塑化剂的工艺条件进行优化。结果表明：分子蒸馏脱除核桃油中塑化剂的最佳工艺条件为蒸馏温度150?℃、进料速度250 mL/h、刮膜转速260 r/min,在此条件下核桃油中DEHP含量为0.56 mg/kg,DBP含量为0.05 mg/kg,符合我国对食品中DEHP、DBP的限量要求（DEHP≤1.5 mg/kg, DBP≤0.3 mg/kg）。