我国冬小麦霜冻灾害致灾因子危险度评价——基于作物生育阶段气象指标

霜冻是一种威胁农业生产的气象灾害,对其致灾因子危险度的研究,可为大尺度的作物霜冻灾害区划及农业保险提供依据。根据作物生长发育的阶段性原理,以全国751个气象台站56年的逐日最低气温资料以及作物生育期资料为基础,统计得到冬小麦各个生育阶段不同灾害等级（轻霜冻、中霜冻、重霜冻）的年霜冻日数,并计算出冬小麦全生育期内不同等级霜冻的发生概率,基于以上两项指标对冬小麦霜冻致灾因子危险度做出评价。结果表明,研究期内重霜冻年霜日最大值为129d,而轻霜冻和中霜冻霜日最大值分别为23 d和19 d,冬小麦受重霜冻危害时间较长;冬小麦霜冻的频发区、多发区、少发区从北向南依次分布,随着霜冻等级增加,频发区的面积差异不大,但多发区的面积减小、少发区面积增大;冬小麦霜冻灾害危险度等级最低的地区主要分布在低纬度的几个省份,如海南、广东、广西、云南等,危险度等级最高的地区集中在青藏高原地区。     

Effects of acute γ-irradiation on the aquatic microbial microcosm in comparison with chemicals

Effects of acute γ-irradiation were investigated in the aquatic microcosm consisting of green algae (Chlorella sp. and Scenedesmus sp.) and a blue–green alga (Tolypothrix sp.) as producers; an oligochaete (Aeolosoma hemprichi), rotifers (Lecane sp. and Philodina sp.) and a ciliate protozoan (Cyclidium glaucoma) as consumers; and more than four species of bacteria as decomposers. At 100 Gy, populations were not affected in any taxa. At 500–5000 Gy, one or three taxa died out and populations of two or three taxa decreased over time, while that of Tolypothrix sp. increased. This Tolypothrix sp. increase was likely an indirect effect due to interspecies interactions. The principal response curve analysis revealed that the main trend of the effects was a dose-dependent population decrease. For a better understanding of radiation risks in aquatic microbial communities, effect doses of γ-rays compared with copper, herbicides and detergents were evaluated using the radiochemoecological conceptual model and the effect index for microcosm.     

Radionuclides in cigarettes may lead to carcinogenesis via p16 inactivation

It is widely accepted that tobacco smoke is responsible for the vast majority of lung cancers worldwide. There are many known and suspected carcinogens present in cigarette smoke, including α-emitting radioisotopes. Epidemiologic studies have shown that increased lung cancer risk is associated with exposure to ionizing radiation, and it is estimated that the majority of smoking-induced lung cancers may be at least partly attributable to the inhaled and deposited radiation dose from radioisotopes in the cigarette smoke itself. Recent research shows that silencing of the tumor suppressor gene p16^INK4a (p16) by promoter methylation plays a role in smoking-related lung cancer. Inactivation of p16 has also been associated with lung cancer incidence in radiation-exposed workers, suggesting that radionuclides in cigarette smoke may be acting with other compounds to cause smoking-induced lung cancer. We evaluated the mechanism of ionizing radiation as an accepted cause of lung cancer in terms of its dose from tobacco smoke and silencing of p16. Because both radiation and cigarette smoking are associated with inactivation of p16, and p16 inactivation has been shown to play a major role in carcinogenesis, ionizing radiation from cigarette smoke likely plays a role in lung cancer risk. How large a role it plays, relative to chemical carcinogens and other modes of action, remains to be elucidated.     

崇明东滩不同部位的季节性沉积研究

2002年4月至2003年4月,通过对崇明东滩南部、中部和北部的标志桩观测以及实地观测分析,发现崇明东滩在一年中不同季节冲淤变化过程存在很大差异：春季到夏季,南部以冲刷为主,中部和北部以淤积为主;夏季到秋季,南部和中部以淤积为主,北部表现为冲刷;秋季到冬季,南部、中部和北部都以冲刷为主;头一年冬季到次年春季,南部和北部以淤积为主,中部则表现为冲刷。在同一观测路线上,不同季节高、中、低潮滩冲淤也存在一定差异。通过对沉积物粒度、水体含沙量等指标的测试,并借助潮差等资料,探究了影响潮滩季节性沉积的因素,发现潮滩季节性沉积与潮滩基础地貌、水体含沙量、水动力、潮流等有密切关系;但在不同部位不同季节,各因素对潮滩冲淤影响程度各不相同。     

Gas/particle partitioning of atmospheric PCDD/Fs in a satellite town in Eastern China

Gas/particle partitioning of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in ambient air was investigated in a satellite town in Eastern China from April 2007 to January 2008 comprehending large temperature variations (from 3 to 34 °C, daily average). Molecular weight, molecular structure and ambient temperatures are the three major factors that govern the gas/particle partitioning of atmospheric PCDD/Fs throughout the year. Generally, good agreements were obtained (except for winter) between measured particulate fractions and theoretical estimates of both the Junge–Pankow adsorption model and Harner Bidleman absorption model using different sets of subcooled liquid vapor pressure and octanol–air partition coefficient (K_oa), respectively. Models utilizing estimates, derived from gas chromatographic retention indices (GC-RIs), are more accurate than that of entropy-based. Moreover, during winter, the K_oa-based model using the GC-RIs approach performs better on lower chlorinated PCDD/Fs than that of -based. Furthermore, possible sources of mismatch between measured and predicted values in winter (3–7 °C) were discussed. Gas adsorption artifact was demonstrated to be of minor importance for the phenomena observed. On the other hand, large deviations of slopes (m_r) and intercepts (b_r) in logK_p vs. plots from theoretical values are observed in the literature data and these are found to be linearly correlated with ambient temperatures (P<0.001) in this study. This indicates that the non-equilibrium partitioning of PCDD/Fs in winter may be significantly influenced by the colder temperatures that may have slowed down the exchange between gaseous and particulate fractions.     

移动通信基站电磁辐射时空分布及衰减特征

根据理论计算公式和实测数据,研究基站电磁辐射水平、垂直方向的衰减趋势,分析影响基站电磁辐射时空分布的各种因素,认为基站电磁辐射实际影响范围要远小于安全防护距离。     

风险管理在水电工程中的应用

水电工程是一个在建设过程中充满风险的、相当复杂的系统工程,其风险管理伴随着工程建设的全过程.随着我国水电工程建设体制改革的进一步深化,风险管理越来越受到工程界的重视.分析了在水电工程中存在的主要危险有害因素,提出了具体的风险管理和评价方法,并对一些主要的评价方法进行了大致的比较,同时对水电工程的风险管理工作提出了一些改进措施.     

复杂社会技术系统安全控制人因研究的转变趋向

在分析复杂社会技术系统的特征及其事故机制的基础上,总结出目前安全控制的人因研究领域中的4种新趋向:分别是从关注个体因素到关注组织因素;从强调行政控制到呼吁社会控制;从考察近端因子到探讨远端征兆;从考核导向向优化发展导向。四大趋势的转变为系统的安全控制提供了新的视角,也开辟了安全控制研究新的领域。最后,笔者结合4方面的转变,针对我国实际情况提出了相应的企业安全管理建议。     

首钢孟家冲尾矿坝渗流稳定分析

针对孟家冲尾矿库坝面出现的渗水现象,对坝体的渗流以及稳定进行计算分析。计算结果表明,由于堆积坝的不断升高,导致坝体浸润线抬高,安全稳定系数降低,从而将造成坝体失稳,出现溃坝事故。为消除隐患,提出采用辐射井排渗的设计方案,并对该方案的可行性进行计算分析。