Mechanism study on the frequent variations of cell-bound microcystins in cyanobacterial blooms in Lake Taihu: Implications for water quality monitoring and assessments

Although Microcystis-based toxins have been intensively studied, previous studies using laboratory cultures of Microcystis strains are difficult to explain the phenomenon that microcystin concentrations and toxin variants in natural blooms differ widely and frequently within a short-term period. The present study was designed to unravel the mechanisms for the frequent variations of intracellular toxins related to the differences in cyanobacterial colonies during bloom seasons in Lake Taihu, China. Monitoring of Microcystis colonies during warm seasons indicated that the variations in microcystins in both concentrations and toxin species were associated with the frequent alteration of Microcystis colonies in Lake Taihu. High concentration of microcystins in the blooms was always associated with two Microcystis colonies, Microcystis flos-aquae and Microcystis aeruginosa, whereas when Microcystis wesenbergii was the dominant colonial type, the toxin production of the blooms was low. Additionally, environmental factors such as temperature and nutrition were also shown to have an effect on the toxin production of the blooms, and may also potentially influence the Microcystis species present. The results of the present study provides insight into a new consideration for quick water quality monitoring, assessment and risk alert in cyanobacterium- and toxin-contaminated freshwaters, which will be beneficial not only for water agencies but also for public health. (C) 2009 Elsevier Ltd. All rights reserved.

WATER-QUALITY CHANGES AND EFFECTS ON FISH POPULATIONS IN THE HANJIANG RIVER, CHINA, FOLLOWING HYDROELECTRIC DAM CONSTRUCTION

Since its completion in 1973 the Danjiangkou Dam has markedly changed downstream flows, water levels, temperatures, sediment loads and other water quality characteristics in downstream reaches of the Hanjiang River. There have been changes in the growth, spawning behaviour and overwintering condition of local fish populations, in the composition and abundance of food organisms and in the composition of the commercial fish catch. Despite the changed environment and the absence of a fish pass, fish populations are still able to grow and spawn under the new regime. Where conditions are like those of the Hanjiang River, dams may not necessarily have calamitous consequences for fishery production.

Analysis of mode quality factors and mode reflectivities for nanowire cavity by FDTD technique

The mode frequency and the quality factor of nanowire cavities are calculated from the intensity spectrum obtained by the finite-difference time-domain (FDTD) technique and the Pade approximation. In a free-standing nanowire cavity with dielectric constant epsilon = 6.0 and a length of 5 mu m, quality factors of 130, 159, and 151 are obtained for the HE11 modes with a wavelength around 375 nm, at cavity radius of 60, 75, and 90 nm, respectively. The corresponding quality factors reduce to 78, 94, and 86 for a nanowire cavity standing on a sapphire substrate with a refractive index of 1.8. The mode quality factors are also calculated for the TE01 and TM01 modes, and the mode reflectivities are calculated from the mode quality factors.

HIGH-QUALITY INGAP AND INGAP/INALP MULTIPLE-QUANTUM-WELL GROWN BY GAS-SOURCE MOLECULAR-BEAM EPITAXY

Using gas-source molecular beam epitaxy, we have obtained high-quality GaInP and (AlGa)InP epilayers lattice-matched to (100) GaAs substrates. All grown layers exhibited mirror-like surfaces. For a 1.7 mum thick Ga0.5In0.5P film, the Hall electron mobility was 3400 and 30,000 CM2/V. s at 300 and 77 K, respectively. The luminescence wavelength of (AlxGa1-x)InP samples ranged from 680 nm (for GaInP) to 590 nm (for AlInP) at room temperature, and from 644 to 513 nm at 77 K. The multiple quantum well (MQW) structure with well width of 40 angstrom showed strong luminescence intensity with wavelength of 647 nm (300 K) or 622 nm (80 K). The satellite peaks can be detected in double-crystal X-ray (DCXR) diffraction measurements of the MQW samples, which indicates the perfect structural periodicity.

中小学生欺负行为及其主要影响因素研究

The present paper studied the school bullying and the primary impact factors, for understanding the nature of bullying, and providing measures and references to the elimination and controlling of school bullying. Primarily with methods of questionnaires and psychometrics, combined with case study and interviews, the following findings were found: in Chinese culture, bullying is a behavior intentionally causing harm to the weaker or weakers. There were 5 types of bullying-physical, social exclusion, threat, breakage and verbal. In Chinese schools the occurrence of bullying had regular patterns. The factor that impact children's bullying behavior was personality traits, interpersonal techniques, family atmosphere, education and upbringing styles. In personality traits, bullies tended to be more extroversive, impulsive, obstinate, obdurate and lack of sympathy. Victims tended to be more introversive, self-restrained, lack of confidence, lonely, anxious and depressive. Both of them expressed more mental problem tendencies than normal children did. When confronted with interpersonal conflicts, they used little problem solving strategies. Bullies had more extroverted emotional responses, and victims had more social support strategies. In the light of family influence, bullies were relatively superior in family's social economic conditions. But their parents had little time and energy spent on them. They tended to be punitive, and had indulgent, reject or despotic upbringing styles. The role of victim might be related to the disadvantage of family's social economic status. Their parents had the tendency of spoiling and overindulgence. The research concluded that in different cultures the connotation of bullying was not homogenous. The occurrence of school bullying had regular patterns. Bullying behavior was primarily influenced by the personality traits of both bullies and victims, the coping strategies of interpersonal conflicts, family's social economic status, parents' basic emotional attitudes, ways of educating, punitive tendencies and school atmosphere. The occurrence of bullying behavior was the result of the combined process of past experience, behavior habits, personality traits, cognitive evaluation, certain evocative clues and the environment conditions. It reminded that quality education and mental health education in schools was essential. Strengthening basic social skill training in school, creating positive family atmosphere, having more communications between schools and families and implementing strict regulations against bullying was essential to interfere and eliminate the school bullying.