Characterization of spectral responses of humic substances upon UV irradiation using two-dimensional correlation spectroscopy

The spectral responses of a leaf litter derived humic substance (LLHS) and Suwannee River fulvic acid (SRFA) upon ultraviolet (UV) A irradiation were characterized using two-dimensional correlation spectroscopy (2D-COS) based on the absorption and the synchronous fluorescence spectra at different irradiation times. A 12 day irradiation on the humic substances (HS) resulted in higher reduction of the absorbance relative to the dissolved organic carbon concentration, suggesting that aromatic chromophores were preferentially oxidized and/or non UV-absorbing compounds were generated by the photobleaching. Synchronous fluorescence spectra revealed the preferential removal of fulvic-like and humic-like fluorophores and delayed response of protein-like fluorescence upon the irradiation. The spectral features at long wavelengths (>430 nm) appear to be affected by intra-molecular interactions of the individual chromophores associated with shorter wavelengths. Absorption-based 2D-COS demonstrated that there are three types of absorption bands for the two HS, which changed sequentially in the order of 290-400 nm → 200-250 nm → 250-290 nm. In addition, two or three distinctive fluorescence bands in response to the irradiation were identified from 2D-COS. The sequential orders and the associated wavelength bands were possibly explained by the irradiation wavelengths and the differences between direct and indirect photochemical reactions. The interpretation of the 2D-COS results was very consistent with the kinetic rate constants individually calculated at several discrete wavelengths. Our study demonstrated that 2D-COS could be used as a powerful tool in identifying distinctive bands of HS that have dissimilar behavior and the associated sequential orders by visualizing the spectral changes at continuous wavelengths.     

光测方法在岩石力学实验观测中的应用述评

综述了常用光测方法在岩石力学实验观测中的应用,总结了这些光测方法相对于岩石力学中常用的其他方法的特点。最后在分析岩石力学实验观测新趋势的基础上,指出发展一种以数字散斑相关方法(DSCM)为基础的岩石力学观测系统,将可以满足岩石力学观测中的新的需要。     

Cell type specificity of lung cancer associated with air pollution

The aim of this study is to explore whether lung cancer associated with air pollution has cell type specificity. The air quality data (SO(2), CO, O(3), NOx) from the Taiwan EPA's air quality monitoring stations were collected between 1995 and 1998. Patients with lung cancer were identified through the National Cancer Registration Program operated by the Taiwanese government. Two major pathological types (adenocarcinoma (AC) and squamous cell carcinoma (SCC)) were considered. The Pearson correlation coefficients between the air quality index and age-standardized incidence rate per 100,000 person years (ASR) of AC and SCC were calculated for both genders for three township categories characterized by different levels of air pollution. The traffic-related NOx and CO showed significant correlations with female lung cancer incidence rate, with Pearson's correlation 0.33 (P=0.03) and 0.40 (P=0.01) respectively. However, the correlation between air pollution and lung cancer was not significant for males. Significant correlation coefficients were also found between the ratio of AC/SCC and the mean concentrations of NOx (r=0.41, P=0.04) and CO (r=0.47, P=0.02) in females. Our results show that the worse the air pollution was in the area, the higher the AC rate, regardless of gender. On the other hand, SCC incidence rates did not increase with increasing air pollution. Our results show that a correlation exists between air pollution and lung adenocarcinoma incidence.     

混凝土电通量和氯离子扩散系数的若干问题研究

采用ASTM C1202及氯离子扩散系数快速测定法(RCM法)研究了不同因素对混凝土电通量和氯离子扩散系数的影响规律,探讨了二者之间的相关性.结果表明,当水灰比、单位立方米水泥用量以及矿渣粉掺量变化时,混凝土的电通量和氯离子扩散系数之间具有较好的相关性;当含气量和粉煤灰掺量变化时,二者之间的相关性较差.     

P-反演半群上的部分核正规系

设S(P)为P-反演半群.首先介绍了S(P)上的正则P-同余和部分核正规系的概念.然后借助于部分核正规系给出了S(P)上正则P-同余的一个抽象刻画,给出了互不相交的S(P)的子集B={Bi∶i∈I}是以P∩Bi为C-集的S(P)的部分核正规系的充分必要条件.由此推出了P-正则半群上的每个P-同余完全是由其包含幂等元的部分核正规系所决定的.     

用灰色系统理论与方法确定深基坑支护方案

根据灰色关联分析原理，将影响待决策的深基坑支护方案的众多因素的理想解指标值组成比较数列，影响深基坑支护方案决策的实际指标值组成参考数列。根据灰色优化理论模型，结合实例得出综合的深基坑支护的最优支护方案。这种灰色系统理论的方法简单，概念明确，便于应用于工程实际中。     

黏土微结构参数的相关分析和主成分分析

将统计学中的相关分析和主成分分析方法引入到对土微结构参数的研究之中,并给出了具体分析方法。从而不仅可以消除不同微结构参数在反映土体内部机理方面存在的"部分信息重复"现象,而且可以大大降低微结构参数的维数。根据对累积贡献率的要求不同,可以用不同数目的主成分近似表达所有微结构参数携带的大部分信息,这使得微结构参数的广泛应用成为可能。降维得到的主成分指标,可以用来建立本构方程、强度准则等土力学关系,以反映土微结构特征与宏观力学现象之间的固有联系;并可以利用建立的关系研究土微结构再造过程。对由64幅SEM照片组成的黏土样本进行的域微结构分析表明,微结构参数之间存在明显的"信息重复"现象,2个主成分就可以反映6个原始微结构参数95.28%的信息,从而达到了降维目的。     

多道瞬态瑞雷波法在强夯地基检测中的应用探讨

文章结合工程实例通过对强夯前、后多道瞬态瑞雷波资料的对比分析,探讨多道瞬态瑞雷波法在强夯地基检测中的应用效果,综合常规静载荷试验、动力及静力触探资料,采用数值统计法计算出各测试点地基土的承载力特征值,从而对整个测区强夯加固效果进行全面评价。     

Is the association between temperature and mortality modified by age, gender and socio-economic status?

Background

A number of studies have examined the relationship between high ambient temperature and mortality. Recently, concern has arisen about whether this relationship is modified by socio-demographic factors. However, data for this type of study is relatively scarce in subtropical/tropical regions where people are well accustomed to warm temperatures.

Objective

To investigate whether the relationship between daily mean temperature and daily all-cause mortality is modified by age, gender and socio-economic status (SES) in Brisbane, Australia.

Methods

We obtained daily mean temperature and all-cause mortality data for Brisbane, Australia during 1996-2004. A generalised additive model was fitted to assess the percentage increase in all deaths with every one degree increment above the threshold temperature. Different age, gender and SES groups were included in the model as categorical variables and their modification effects were estimated separately.

Results

A total of 53,316 non-external deaths were included during the study period. There was a clear increasing trend in the harmful effect of high temperature on mortality with age. The effect estimate among women was more than 20 times that among men. We did not find an SES effect on the percent increase associated with temperature.

Conclusions

The effects of high temperature on all deaths were modified by age and gender but not by SES in Brisbane, Australia.     

多种腐蚀因素作用下钢筋混凝土结构的可靠度分析

钢筋混凝土结构可能会同时受到多种腐蚀介质的侵蚀。本文给出了钢筋混凝土结构常见的几种腐蚀失效模式。考虑了失效模式间的相关性对结构整体可靠度的影响,用系统可靠度方法分析了多种腐蚀因素作用下钢筋混凝土结构的可靠度并给出了算例。该分析方法计算简便,可以作为多种腐蚀介质环境下结构可靠度分析的参考方法。