果蔬气调贮藏保鲜技术研究现状与展望

气调贮藏保鲜技术具有保藏效果好, 贮藏时间长, 贮藏损耗小, 安全无污染等特点, 近年来在果蔬贮藏保鲜上的研究和应用不断发展进步。本文介绍了果蔬气调贮藏保鲜技术的分类, 陈述了气调贮藏工艺条件(温度、湿度、氧气和二氧化碳含量等)控制、气调库和气调包装材料的研究现状, 分析了果蔬气调贮藏保鲜的发展趋势。     

MiRNA-199a-3p Regulates C2C12 Myoblast Differentiation through IGF-1/AKT/mTOR Signal Pathway

MicroRNAs constitute a class of ~22-nucleotide non-coding RNAs. They modulate gene expression by associating with the 3′ untranslated regions (3′ UTRs) of messenger RNAs (mRNAs). Although multiple miRNAs are known to be regulated during myoblast differentiation, their individual roles in muscle development are still not fully understood. In this study, we showed that miR-199a-3p was highly expressed in skeletal muscle and was induced during C2C12 myoblasts differentiation. We also identified and confirmed several genes of the IGF-1/AKT/mTOR signal pathway, including IGF-1, mTOR, and RPS6KA6, as important cellular targets of miR-199a-3p in myoblasts. Overexpression of miR-199a-3p partially blocked C2C12 myoblast differentiation and the activation of AKT/mTOR signal pathway, while interference of miR-199a-3p by antisense oligonucleotides promoted C2C12 differentiation and myotube hypertrophy. Thus, our studies have established miR-199a-3p as a potential regulator of myogenesis through the suppression of IGF-1/AKT/mTOR signal pathway.     

活性填料在先驱体转化陶瓷喷管中的应用

以聚碳硅烷为先驱体，Al为活性填料，研究了活性填料Al对SiC陶瓷喷管的成型工艺、力学性能、抗氧炔焰烧蚀率、抗氧化和抗热震性能的影响。研究表明，喷管在裂解前后的体积基本不变。当喷管素坯在含有活性填料Al时，材料的室温三点弯曲强度比不含活性填料材料的强度约提高50％；抗氧炔焰烧蚀性能明显改善，抗氧炔焰烧蚀率为0.02％，比不含活性填料的喷管的抗氧炔焰烧蚀率降低了3.07％；抗氧化性能也有所提高。     

偏振场景目标探测的建模与仿真

针对用光学遥感技术探测复杂场景下的目标时,真实环境下的目标、背景反射以及大气气溶胶辐射之间具有相当大的互干扰性,本文研究了偏振场景目标的建模与仿真技术。介绍了偏振场景仿真的光学理论与偏振模型基础,对Priest-Germer模型进行了数值仿真与分析。基于Priest-Germer模型,开发了偏振视景目标探测仿真软件,给出仿真软件的设计思想和软件框架。介绍了偏振双向分布反射函数模型,给出其偏振形式的Stokes表达式并进行数值仿真分析。给出了两种目标模型分别赋予两种不同表面材质时在440nm和600nm波长辐照条件下的4组偏振仿真实验及偏振图像的灰度直方图,并进行比较和分析,结果表明:基于Priest-Germer模型的偏振仿真软件对目标、辐照波长、材质具有较高的敏感性,能够提供较好的分辨和识别能力。     

基于遗传规划和主动学习的本体实例匹配

针对现有实例匹配方法存在的准确率和学习效率不高的问题,提出了一种新的基于遗传规划和主动学习的链接规则学习方法,并用于本体实例匹配。设计了更合理的链接规则表示,并针对链接规则的特点,对遗传规划的初始种群产生、适应度函数和进化算子进行了详细设计。提出了一种考虑样本相关性的主动学习采样策略,使得稀有样本被优先训练。实验结果表明,该方法不仅学习效率更高,而且能够学习出高质量的链接规则,取得了较好的本体实例匹配结果。     

Random walk with restart: fast solutions and applications

How closely related are two nodes in a graph? How to compute this score quickly, on huge, disk-resident, real graphs? Random walk with restart (RWR) provides a good relevance score between two nodes in a weighted graph, and it has been successfully used in numerous settings, like automatic captioning of images, generalizations to the “connection subgraphs”, personalized PageRank, and many more. However, the straightforward implementations of RWR do not scale for large graphs, requiring either quadratic space and cubic pre-computation time, or slow response time on queries. We propose fast solutions to this problem. The heart of our approach is to exploit two important properties shared by many real graphs: (a) linear correlations and (b) block-wise, community-like structure. We exploit the linearity by using low-rank matrix approximation, and the community structure by graph partitioning, followed by the Sherman–Morrison lemma for matrix inversion. Experimental results on the Corel image and the DBLP dabasets demonstrate that our proposed methods achieve significant savings over the straightforward implementations: they can save several orders of magnitude in pre-computation and storage cost, and they achieve up to 150 × speed up with 90%+ quality preservation.     

BaO-Al2O3-SiO2系微晶玻璃析晶机理研究

利用烧结法制备化学计量比和高Ba含量的两组BaO-Al₂O₃-SiO₂(BAS)系微晶玻璃, 采用等转化率法计算玻璃粉的活化能随析晶过程的变化, 利用线性回归的方法确定最概然析晶机理函数, 进而对比研究添加ZrO₂和提高Ba含量对BAS系微晶玻璃析晶过程的影响. 结果表明, 4种成分的BAS系玻璃的最概然析晶机理函数均为SB(m, n)函数, 析晶过程中存在自催化的相变机制. 在化学计量比的BAS系玻璃中添加ZrO₂或者提高Ba含量, 对六方钡长石的析出表现为促进作用, 并且随着温度的降低或者析晶过程的进行, 促进效果更加明显. 在高Ba含量的BAS系玻璃中添加ZrO₂对六方钡长石的析出表现为抑制作用, 并且随着温度的升高抑制效果更加明显.     

IL-4 and IL-13 Promote Proliferation of Mammary Epithelial Cells through STAT6 and IRS-1

T helper (Th)2 cytokines such as interleukin (IL)-4 and IL-13 control immune function by acting on leukocytes. They also regulate multiple responses in non-hematopoietic cells. During pregnancy, IL-4 and IL-13 facilitate alveologenesis of mammary glands. This particular morphogenesis generates alveoli from existing ducts and requires substantial cell proliferation. Using 3D cultures of primary mouse mammary epithelial cells, we demonstrate that IL-4 and IL-13 promote cell proliferation, leading to enlargement of mammary acini with partially filled lumens. The mitogenic effects of IL-4 and IL-13 are mediated by STAT6 as inhibition of STAT6 suppresses cell proliferation and improves lumen formation. In addition, IL-4 and IL-13 stimulate tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1). Prolonged treatment with these cytokines leads to increased IRS-1 abundance, which, in turn, amplifies IL-4- and IL-13-stimulated IRS-1 tyrosine phosphorylation. Through signaling crosstalk between IL-4/IL-13 and insulin, a hormone routinely included in mammary cultures, IRS-1 tyrosine phosphorylation is further enhanced. Lowering IRS-1 expression reduces cell proliferation, suggesting that IRS-1 is involved in IL-4- and IL-13-stimulated cell proliferation. Thus, a Th2-dominant cytokine milieu during pregnancy confers mammary gland development by promoting cell proliferation.     

‘白玉’枇杷花不同花期挥发性物质分析

目的 探究枇杷花发育过程中挥发性物质的组成及变化规律。方法 采用顶空固相微萃取-气相色谱-质谱法对幼蕾期、显露期、始展期、盛花期和谢花期枇杷花的挥发性成分进行定性定量分析,并利用主成分分析法(principalcomponentanalysis,PCA)和香气活性值(odoractivityvalue,OAV)分析枇杷花的主要香气成分。结果 5个时期共检测出96种挥发性物质,分为醛类、烃类、酯类、醇类、酮类、酚类以及其他共7大类,其中苯甲醛在各个时期含量均最高。对枇杷花发育过程中的16种主要挥发性物质进行主成分分析,可简化成3个主成分,累计贡献率达到95.400%。分析发现,第1主成分与己醛、苯甲醛、二十一烷、二十四烷、苯甲醇成高度正相关,与4-甲氧基苯甲醛、4-甲氧基苯甲酸甲酯、4-甲氧基苯甲酸乙酯和苯乙醇成高度负相关。第2主成分贡献较大的组分是十五烷、二十六烷和十九烷,属于烷烃类化合物。5个时期共检测出8种关键香气物质(OAV>1),共有的香气是己醛,具青草香,其在花发育过程香气的调控中扮演着至关重要的作用,对‘白玉’枇杷花香的形成有着极大的贡献。除了己醛以外,还有癸醛、4-...     

基于网格的开放式决策支持系统模型

网格技术的出现和飞跃对决策支持系统(DSS)的发展将产生巨大影响。本文分析了当前DSS所存在的不足，介绍了网格的基本概念及网格技术对DSS的影响。最后提出了一个基本的开放DSS模型及其实现。