T6热处理对7075铝合金FSW接头蠕变性能的影响

采用光学显微镜(OM)、差示扫描量热仪(DSC)、扫描电镜(SEM)、透射电镜(TEM)以及高温拉伸蠕变装置等研究了7075铝合金搅拌摩擦焊(FSW)接头经T6热处理后的显微组织、析出相以及蠕变性能。结果表明:经T6热处理后,7075铝合金搅拌摩擦焊接头焊核区细小的等轴晶发生长大,重新析出的η′相在数量、尺寸和分布状态均优于未热处理的接头;热处理后焊接头的稳态蠕变速率降低了至少1个数量级,蠕变寿命提高了2倍以上,蠕变机制由晶界扩散控制的位错滑移机制转变为自扩散控制的位错滑移机制。

盐胁迫对药食用菊花种子萌发特性的影响

菊花因其含有丰富的挥发油类、黄酮类、氨基酸以及其他各种微量化学成分,在食用和医疗保健等领域受到广泛应用。以黄香菊种子为材料,设置了5个NaCl浓度(0、40、80、120、160 mmol/L)),对NaCl胁迫处理下菊花种子的各项发芽指标进行了分析,结果表明:随着NaCl浓度的增加,菊花种子的发芽高峰期逐渐延迟,且幼苗活力指数逐渐下降;菊花种子的发芽率随盐浓度的加大而表现为先增高后降低的趋势,80 mmol/L NaCl处理的菊花种子萌发率最高,为64.3%,比CK高26.1%,相对盐害率最低,仅为-23.8%;当NaCl浓度大于80 mmol/L时,种子发芽受到明显抑制,其发芽率、发芽势、活力指数、根长等指标均显著低于CK;160 mmol/L NaCl处理的种子萌发率仅为22.3%。由此可知,适当浓度的NaCl胁迫能提升黄香菊种子的萌发率并降低相对盐害率,但菊花幼苗根系的生长发育仍受到NaCl胁迫的影响,且幼苗根长随盐浓度增加而逐渐降低。在相同NaCl浓度胁迫下,根长受抑制的程度明显高于鲜重和苗高。

新型热障涂层材料及其制备技术的研究与发展?

热障涂层(thermal barrie rcoatings,TBCs)能有效的提高航空发动机热端部件的工作温度和使用寿命。目前应用最为广泛的热障涂层材料为氧化钇部分稳定氧化锆(yttria-stabilized zirconia,YSZ),该热障涂层材料在服役温度高于1200℃下会发生相变,严重影响航空发动机的使用寿命和服役安全,难以满足新一代航空发动机的服役要求。本文综述了新型热障涂层材料的研究现状,重点介绍了掺杂改性氧化钇部分稳定氧化锆、烧绿石或萤石结构材料、钙钛矿结构化合物、磁铅石矿结构化合物以及新型黏结层材料的研究进展和发展方向,并论述了热障涂层制备技术的方法原理和优缺点,最后对热障涂层材料和制备方法的发展趋势进行了展望。

国际标准化组织粮油标准体系浅析

通过收集整理国际标准化组织(international standardization organization,ISO)最新资料和粮油及其制品相关标准,介绍ISO标准体系概况,并对ISO粮油标准体系中含油种子、果实和油籽粕、谷物和豆类、动物和植物油脂标准的分类构成、现状、特点分布和最新发展趋势等进行介绍和系统分析。分析结果表明,ISO粮油标准框架结构合理,标准体系完善,侧重于粮油质量安全方面的检测,重视食品质量安全,管理性标准、综合性标准和安全标准将是ISO制定粮油标准的未来重点。结合我国粮油标准体系的实际情况,提出从扩大标准覆盖范围、规范科学标准的制修订管理、引入科学新技术等方面提升中国粮油标准的国际影响力。

基于地理信息系统、云平台的粮食扦样外业管理技术与模式

粮油质量扦样是粮食交易、储藏、加工过程中,保留过程样本进行品质检测的重要工作,对保证公平交易以及控制粮食储藏、加工生产过程,保证粮食品质有重要意义。为解决粮食扦样外业工作存在的区域代表性不足、过程舞弊及基层系统建设困难等问题,提出了一种基于地理信息系统(GIS)、云平台(cloud platform)的扦样外业管理技术与模式,规范扦样操作过程,实现对扦样作业过程的实时记录和监管,保证了样品检测公平、公正,减少了舞弊行为;使扦、检成果轻松处理,可视直观;平台租用的管理模式,可解决基层单位建设资金及技术人员不足的问题。

Apigenin accelerates lipopolysaccharide induced apoptosis in mesenchymal stem ceils through suppressing vitamin D receptor expression

Background Transplantation of mensenchymal stem cells （MSCs） has been proposed as a promising way for tissue engineering. However, the application of MSCs for transplantation will undergo apoptosis due to the extremely harsh microenvironment such as excessive inflammation. Apigenin （API） has been reported to protect cells against inflammatory damage and cell death by exhibiting anti-inflammatory and anti-oxidative capacity. Here we investigated the modulatory effects of API in lipopolysaccharide （LPS）-mediated inflammation and apoptosis of MSCs, and further defined the underlying mechanism. Methods Effects of different concentrations of API （0, 5, 10, 20, 40 and 80 IJmol/L） for 24 hours, and LPS （0, 0.5 and 5.0 pg/ml） for 6 hours and 24 hours on MSCs viability were assayed by MTT. Based on this, MSCs were pretreated with different concentrations of API （0-40μmol/L） at the indicated times （6, 12 and 24 hours） followed by exposure to 5μg/ml LPS for 24 hours. MTT, phase-contrast microscopy, annexinV/propidium iodide （PI） double stain flow cytometry （FCM） and Hoechst staining were applied to explore the effects of API on MSCs induced by 5 μg/ml LPS for 24 hours. In addition, reverse-transcription polymerase chain reaction （RT-PCR） was applied to detect the mRNA expression of pro-inflammatory factors including cyclooxygenase-2 （COX-2）, inducible nitric oxide synthase （iNOS）, nuclear factor-kappa B （NF-KB）, pro-apoptotic gene caspase-3, Bad, and anti-apoptotic gene Bcl-2. Moreover, AutoDock software was used to imitate the docking score of API and vitamin D receptor （VDR）. In parallel, Western blotting and RT-PCR were used to investigate protein and mRNA expression of VDR. Results MSCs stimulated with LPS 5 IJg/ml for 24 hours was used as a model of apoptosis induced by over inflammatory stimulus. API （0-40μmol/L） had non-toxic effect on MSCs; however, it could decrease mRNA expression of COX-2, iNOS and NF-KB at different time points in MSCs induced by LPS, except for API at the concentration of 5 μmol/L Results from phase-contrast microscopy, MTT, Hoechst staining and AnnexinV/PI double stain FCM demonstrated that with the increasing concentrations of API and extension of administrating time, significant morphological changes of MSCs occurred, viability of cells was strongly inhibited, and meanwhile, apoptosis of LPS-administrated MSCs was exacerbated, compared with LPS individual group. In addition, API promoted caspase-3, Bad mRNA expression and inhibited Bcl-2 mRNA expression in a time-dePendent and concentration-dependent manner. Further study found that pro-apoptosis effect of API was related to suppress VDR expression. Conclusions API could inhibit the expression of inducible inflammatory factors, therefore exert the strong anti-inflammatory function. However, API could not protect MSC apoptosis induced by LPS but amplified the apoptosis, The apoptosis is related to Bad/Bcl-2 increasing and caspase-3 activation, which is mediated through suppressing VDR expression.