Effect of seasonal variation on dust samples of a winter fog affected urban environment of India,South East Asia

Physical and chemical characteristics of leaf dust (LD) samples, collected between 2011 and 2013, of a severely winter fog affected and polluted urban environment (Allahabad, India) of Indo-Gangetic plain are presented in this study. The weather changes in the study area are grouped into three effective annual seasonal periods – winter fog, pre-monsoon and post-monsoon. The pronounced impact of seasonal variations is observed in LD characteristics, as ~46% of the winter fog period samples ranges in size between 2.5 and 20 µm with high magnetic susceptibility (up to 938.22 × 10^?8 m³ kg^?1). In comparison, 35% of the LD from pre-monsoon period occurs in the size range of 100–300 µm with low magnetic susceptibility (up to 43.29 × 10^?8 m³ kg^?1). The fractal analysis involving submicroscopic clast dimension of LD also reveals a seasonal influence. The toxic metals (Pb, Zn, Cd, Cr and Ni) in LD belonging to winter fog and post-monsoon periods increase in comparison to samples from pre-monsoon time. Multivariate statistical analysis of trace element data suggests that the LD collected from winter fog and post-monsoon periods originate predominantly from anthropogenic source, whereas those collected during pre-monsoon owe their origin to crustal and anthropogenic sources, mainly. The present study has demonstrated the role of seasonal variation in controlling the physical and chemical properties of particulate matter based on multiple parameter analyses, and the derivation of the dust load from a mixed source (upper continental crust, anthropogenic and vehicular) for the study area for the first time.     

基于振动监测的静载荷滑动轴承接触摩擦故障诊断实验研究

采用静载荷滑动轴承试验台模拟轴颈-轴承从液体润滑状态逐步向干摩擦状态过渡时的接触摩擦故障的发生和发展过程,进而利用振动信号诊断滑动轴承的接触摩擦故障;通过对特征参数进行归一化处理得到无量纲特征参数,进而通过无量纲特征参数的适当数学组合得到无量纲诊断准则,并探讨了无量纲诊断准则的适用性.结果表明:利用所得到的无量纲诊断准则进行轴颈-轴承接触摩擦故障诊断时无须建立用于模式识别的标准模,可实现快捷方便的故障诊断;无量纲诊断准则对工况不敏感,而对故障更敏感,适用于可变工况下滑动轴承的故障诊断,且诊断成本较低.     

黄炎培与卢作孚的人际交往

黄炎培与卢作孚以教育与实业两种救国思潮为媒介建立了频繁的互动交往。黄炎培因推动职业教育的发展,与工商界人士往来频繁;卢作孚以兴办实业为重心,在兴办实业的过程中注重教育理念的灌输。两人的交往过程,是民初实业与教育两种救国思潮融合的代表。两人互相扶持,互相帮助,共同推进了各自事业的发展。     

“还NP呢”句式考察

"还NP呢"是现代汉语口语中习用的一种句式,我们将"还NP呢"分成S1~S6六组,并从句法、语义、语用三个平面逐一进行考察。六组状中结构表达了不同的语义:NP名不副实(S1名大于实,S6名小于实);连不如NP的都没有实现,就更不用说NP了(S2);NP已经不复存在(S3);NP和不如NP的相比,程度上更高(S4);通过说话人对NP的戏谑否定,实现否定前述信息的目的(S5)。并由此传递或责备、或否定、或褒扬的语气。     

基于混沌的三江平原月降水时间序列分析

三江平原是我国最大的淡水沼泽区,近年来降水的减少是导致湿地减少的一个重要的自然因素.别拉洪河是三江平原上比较有代表性的沼泽性河流.以别拉洪水文站的降水序列为例,通过相空间重构,分别计算了序列的关联维、最大Lyapunov指数以及Kolmogorov熵等几个序列特征量.计算表明:三江平原月降水序列中是存在明显的混沌特征的,这为以后建立三江平原月降水的混沌预测模型提供了理论依据.     

在文学史的视野里——从故事性看海岩小说的创作路向

海岩是当代最有市场号召力的作家之一。他的小说创作持续而稳定，时间跨度达二十多年，每一部小说的推出都造成了轰动效应和流行趋势。本文透过纷繁复杂的现象，试图回到上世纪80年代文学历史的现场，在诸多的比较和选择当中，结合海岩自身的阅历和思维特点，来探讨他以故事为中心的创作路向的个人化定位。     

上海市地貌类型与地貌分区

本文从沉积相分析出发,采用形态、成因、年龄和组成物质等综合标志,将上海地区地貌类型划分为三角洲平原、三角洲前缘、前三角洲、潮坪、滨海平原和湖沼平原共六大单元,以及河口砂岛、湖沼洼地等18个次一级地貌类型和数10个更小的地貌形态。并按地貌类型的组合特征,结合本区农业地貌条件利用与改造的地域差异,明显地将本区划分为河口三角洲、东部滨海平原和西部湖沼平原三个地貌区。     

大学生艰苦奋斗状况的调查与思考

艰苦奋斗是中华民族的优良传统,然而大学生艰苦奋斗的状况不容乐观,究其原因:是家长过度纵容,学校教育的缺失,社会不良风气的影响,学生主体以艰苦奋斗为荣的荣辱观还没有完全形成。为此,要弘扬中华民族艰苦奋斗的优良传统,就必须增强培养大学生以艰苦奋斗为荣的紧迫性,培养大生以艰苦奋斗为荣的荣辱观要注重实效性,要营造全社会践行以艰苦奋斗为荣的氛围。     

Cytotoxicity of benzophenanthridine alkaloids from the roots of Zanthoxylum nitidum (Roxb.) DC. var. fastuosum How ex Huang

This work aimed to investigate benzophenanthridine from the roots of Zanthoxylum nitidum (Roxb.) DC. var. fastuosum How ex Huang for the first time. Thirteen benzophenanthridines were isolated, and our results of the cytotoxic activities indicated that compound 6 exhibited the best potency against A549, Hela, SMMC-7721 and EJ, with the IC₅₀ values of 27.50, 37.50, 16.95 and 60.42 μM, respectively. Compounds 7 and 11 also showed strong cytotoxicity when tested against the four human cancer cell lines (A549, Hela, SMMC-7721 and EJ), while only compounds 12 and 13 displayed cytotoxicity in inhibiting BALL-1 proliferation among all the compounds. These results suggested that benzophenanthridines may become a valid alternative of potential basis for new anti-proliferative agents.     

Optimal uncertainty size in distributionally robust inverse covariance estimation

In a recent paper, Nguyen et al. (2018) built a distributionally robust estimator for the precision matrix of the Gaussian distribution. The distributional uncertainty size is a key ingredient in the construction of this estimator. We develop a statistical theory which shows how to optimally choose the uncertainty size to minimize the associated Stein loss. Surprisingly, rather than the expected canonical square-root scaling rate, the optimal uncertainty size scales linearly with the sample size.