Identification of a gene, ccr-1 (sll1242), required for chill-light tolerance and growth at 15 degrees C in Synechocystis sp PCC 6803

Synechocystis sp. PCC 6803 exposed to chill (5 degrees C)-light (100 mu mol photons m(-2) s(-1)) stress loses its ability to reinitiate growth. From a random insertion mutant library of Synechocystis sp. PCC 6803, a sll1242 mutant showing increased sensitivity to chill plus light was isolated. Mutant reconstruction and complementation with the wild-type gene confirmed the role of sll1242 in maintaining chill-light tolerance. At 15 degrees C, the autotrophic and mixotrophic growth of the mutant were both inhibited, paralleled by decreased photosynthetic activity. The expression of sll1242 was upregulated in Synechocystis sp. PCC 6803 after transfer from 30 to 15 degrees C at a photosynthetic photon flux density of 30 mu mol photons m(-2) S-1. sll1242, named ccr (cyanobacterial cold resistance gene)- 1, may be required for cold acclimation of cyanobacteria in light.

Distribution of nitrogen and phosphorus in sediment cores and overlying water of Donghu Lake

In this study, the seasonal, vertical distribution of various phosphorus and nitrogen forms in the sediment and overlying water of Donghu Lake were investigated. The concentration of total nitrogen (TN) in overlying water was high in spring and autumn, but that of NO3--N reached its peak in autumn. From summer to autumn and from winter to spring, the concentration of phosphorus in overlying water decreased, while it increased from autumn to winter. Vertical characteristic forms of phosphorus in sediment cores are total phosphorus (TP), labile phosphorus (LP), Fe-P and Al-P, obviously enriched in the surface layer (0-10 cm), but their concentrations are observably reduced along with the depth of sediment. The research is of important theoretical and practical value to understand the status and to control the developmental trend of eutrophication in Donghu Lake.

Effects of CO2 concentrations on the freshwater microalgae, Chlamydomonas reinhardtii, Chlorella pyrenoidosa and Scenedesmus obliquus (Chlorophyta)

In order to investigate the possible impacts of increased atmospheric CO2 levels on algal growth and photosynthesis, the influence of CO2 concentration was tested on three planktonic algae (Chlamydomonas reinhardtii, Chlorella pyrenoidosa, and Scenedesmus obliquus). Increased CO2 concentration enhanced significantly the growth rate of all three species. Specific growth rates reached maximal values at 30, 100, and 60 muM CO2 in C. reinhardtii, C pyrenoidosa, and S. obliquus, respectively. Such significant enhancement of growth rate with enriched CO2 was also confirmed at different levels of inorganic N and P, being more profound at limiting levels of N in C pyrenoidosa and P in S. obliquus. The maximal rates of net photosynthesis, photosynthetic efficiency and light-saturating point increased significantly (p<0.05) in high-CO2-grown cells. Elevation of the CO2 levels in cultures enhanced the photoinhibition of C. reinhardtii, but reduced that of C pyrenoidosa and S. obliquus when exposed to high photon flux density. The photo-inhibited cells recovered to some extent (from 71% to 99%) when placed under dim light or in darkness, with better recovery in high-CO2-grown C. pyrenoidosa and S. obliquus. Although pH and pCO(2) effects cannot be distinguished from this study, it can be concluded that increased CO2 concentrations with decreased pH could affect the growth rate and photosynthetic physiology of C. reinhardtii, C. pyrenoidosa, and S. obliquus.

Optimization of growth and fatty acid composition of a unicellular marine picoplankton, Nannochloropsis sp., with enriched carbon sources

A unicellular marine picoplankton, Nannochloropsis sp., was grown under CO2-enriched photoautotrophic or/and acetate-added mixotrophic conditions. Photoautotrophic conditions with enriched CO2 of 2800 mul CO2 l(-1) and aeration gave the highest biomass yield (634 mg dry wt l(-1)), the highest total lipid content (9% of dry wt), total fatty acids (64 mg g(-1) dry wt), polyunsaturated fatty acids (35% total fatty acids) and eicosapentaenoic acid (EPA, 20:5omega3) (16 mg g(-1) dry wt or 25% of total fatty acids). Mixotrophic cultures gave a greater protein content but less carbohydrates. Adding sodium acetate (2 mM) decreased the amounts of the total fatty acids and EPA. Elevation of CO2 in photoautotrophic culture thus enhances growth and raises the production of EPA in Nannochloropsis sp.

简评美国公布的15个AES候选算法

文章对美国国家标准和技术研究所（ＮＩＳＴ）最近公布的１５个ＡＥＳ候选算法的基本设计思想作了简要介绍，同时也介绍了对这些算法的最新分析结果

Species transformation of trace elements and their distribution prediction in dyestuff residue incineration

The release of heavy metals from the combustion of hazardous wastes is an environmental issue of increasing concern. The species transformation characteristics of toxic heavy metals and their distribution are considered to be a complex problem of mechanism. The behavior of hazardous dyestuff residue is investigated in a tubular furnace under the general condition of hazardous waste pyrolysis and gasfication. Data interpretation has been aided by parallel theoretical study based on a thermodynamic equilibrium model based on the principle of Gibbs free energy minimization. The results show that Ni, Zn, Mn, and Cr are more enriched in dyestuff residue incineration than other heavy metals (Hg, As, and Se) subjected to volatilization. The thermodynamic model calculation is used for explaining the experiment data at 800 degrees C and analyzing species transformation of heavy metals. These results of species transformation are used to predict the distribution and emission characteristics of trace elements. Although most trace element predictions are validated by the measurements, cautions are in order due to the complexity of incineration systems.

VLBI observations of a sample of 15 EGRET-detected AGNs at 5 GHz

We report VLBI observations of 15 EGRET-detected AGNs with European VLBI Network (EVN) at 5 GHz. All sources in the sample display core-jet structures.

Room-Temperature Continuous-Wave Operation of InGaN-Based Blue-Violet Laser Diodes with a Lifetime of 15.6 Hours

We report our recent progress of investigations on InGaN-based blue-violet laser diodes (LDs). The room-temperature (RT) cw operation lifetime of LDs has extended to longer than 15.6 h. The LD structure was grown on a c-plane free-standing (FS) GaN substrate by metal organic chemical vapor deposition (MOCVD). The typical threshold current and voltage of LD under RT cw operation are 78 mA and 6.8 V, respectively. The experimental analysis of degradation of LD performances suggests that after aging treatment, the increase of series resistance and threshold current can be mainly attributed to the deterioration of p-type ohmic contact and the decrease of internal quantum efficiency of multiple quantum well (MQW), respectively.