A high power dual-wavelength Ti：sapphire laser system with wide turning range and high efficiency is described, which consists of two prism-dispersed resonators pumped by an a11-solid-state frequency-doubled Nd：YAG ...A high power dual-wavelength Ti：sapphire laser system with wide turning range and high efficiency is described, which consists of two prism-dispersed resonators pumped by an a11-solid-state frequency-doubled Nd：YAG laser. Tunable dual-wavelength outputs, with one wavelength range from 750nm to 795nm and the other from 80Ohm to 850nm, have been demonstrated. With a pump power of 23 W at 532nm, a repetition rate of 6.5kHz and a pulse width of 67.6ns, the maximum dual-wavelength output power of 5.6 W at 785.3nm and 812.1 run, with a pulse width of 17.2ns and a line width of 2nm, has been achieved, leading to an optical-to-optical conversion efficiency of 24.4%.展开更多
Genetic engineering in filamentous N2-fixing cyanobacteria usually involves Anabaena sp. PCC 7120 and several other non-aggregating species. Mass culture and harvest of such species are more energy consuming relative ...Genetic engineering in filamentous N2-fixing cyanobacteria usually involves Anabaena sp. PCC 7120 and several other non-aggregating species. Mass culture and harvest of such species are more energy consuming relative to aggregating species. To establish a gene transfer system for aggregating species, we tested many species of Anabaena and Nostoc, and identified Nostoc muscorum FACHB244 as a species that can be genetically manipulated using the conjugative gene transfer system. To promote biodegradation of organophosphorus pollutants in aquatic environments, we introduced a plasmid containing the organophosphorus-degradation gene （opd） into Anabaena sp. PCC 7120 and Nostoc muscorum FACHB244 by conjugation. The opd gene was driven by a strong promoter, Pp,bA. From both species, we obtained transgenic strains having organophosphorus-degradation activities. At 25~C, the whole-cell activities of the transgenic Anabaena and Nostoc strains were 0.163~0.001 and 0.289~0.042 unit/gg Chl a, respectively. However, most colonies resulting from the gene transfer showed no activity. PCR and DNA sequencing revealed deletions or rearrangements in the plasmid in some of the colonies. Expression of the green fluorescent protein gene from the same promoter in Anabaena sp. PCC 7120 showed similar results. These results suggest that there is the potential to promote the degradation of organophosphorus pollutants with transgenic cyanobacteria and that selection of high-expression transgenic colonies is important for genetic engineering of Anabaena and Nostoc species. For the first time, we established a gene transfer and expression system in an aggregating filamentous N2-fixing cyanobacterium. The genetic manipulation system of Nostoc muscorum FACHB244 could be utilized in the elimination of pollutants and large-scale production of valuable proteins or metabolites.展开更多
The salt-resistant nitrogen-fixing cyanobacteria 888 was experimentally applied to the reclamation of saline and alkali soil in Songnen Plain in China. The pH, electrical conductivity (EC) and sodium adsorption ratio ...The salt-resistant nitrogen-fixing cyanobacteria 888 was experimentally applied to the reclamation of saline and alkali soil in Songnen Plain in China. The pH, electrical conductivity (EC) and sodium adsorption ratio (SAR) of different saline soils were studied and compared. Results show that different saline soils exhibit various physico-chemical properties. Saline-sodic soils in Songnen Plain are ameliorated by using nitrogen-fixing blue-green algae 888 in the experiment. It is indicated that cyanobacteria 888 can grow in saline and alkaline soils, and the conditions favorable for its growth are soil moisture of 50% and dry algae inoculation at 0.03 mg/cm2. The main actions of nitrogen-fixing cyanobacteria are keeping the adsorbability of rubber sheath for sodium, increasing the organic matter content of the soils and decreasing the pH and the degree of salinity in the soils. But the arid climate and soil depth are the main factors that limit the restoration of saline and alkaline soils.展开更多
Cyanothece sp. 113 is a unicellular, aerobic, diazotrophic and photosynthetic marine cyanobacterium. The optimal medium for exopolysaccharide yield by the strain was 70.0 g/L of NaCl, and 0.9 g/L of MgSO4 based on the...Cyanothece sp. 113 is a unicellular, aerobic, diazotrophic and photosynthetic marine cyanobacterium. The optimal medium for exopolysaccharide yield by the strain was 70.0 g/L of NaCl, and 0.9 g/L of MgSO4 based on the modified F/2 medium for cultivation of marine algae. The optimal cultivation condition for exopolysaccharide yield by this cyanobacterial strain was 29℃, aeration, and continuous illumination at 86.0 μE/M^2/S. Under the optimal conditions, over 18.4 g/L of exopolysaccharide was produced within 12 days. This was so far the highest exopolysaccharide yield produced with strains of Cyanothece sp. obtained.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 10474071, 60637010, 60671036 and 60278001, and the Tianjin Applied Fundamental Research Project under Grant No 07JCZDJC05900.
文摘A high power dual-wavelength Ti：sapphire laser system with wide turning range and high efficiency is described, which consists of two prism-dispersed resonators pumped by an a11-solid-state frequency-doubled Nd：YAG laser. Tunable dual-wavelength outputs, with one wavelength range from 750nm to 795nm and the other from 80Ohm to 850nm, have been demonstrated. With a pump power of 23 W at 532nm, a repetition rate of 6.5kHz and a pulse width of 67.6ns, the maximum dual-wavelength output power of 5.6 W at 785.3nm and 812.1 run, with a pulse width of 17.2ns and a line width of 2nm, has been achieved, leading to an optical-to-optical conversion efficiency of 24.4%.
基金Supported by the National High Technology Research and Development Program of China (863 Program) (No. 2002AA601170)the National Natural Science Foundation of China (No. 30623001)
文摘Genetic engineering in filamentous N2-fixing cyanobacteria usually involves Anabaena sp. PCC 7120 and several other non-aggregating species. Mass culture and harvest of such species are more energy consuming relative to aggregating species. To establish a gene transfer system for aggregating species, we tested many species of Anabaena and Nostoc, and identified Nostoc muscorum FACHB244 as a species that can be genetically manipulated using the conjugative gene transfer system. To promote biodegradation of organophosphorus pollutants in aquatic environments, we introduced a plasmid containing the organophosphorus-degradation gene （opd） into Anabaena sp. PCC 7120 and Nostoc muscorum FACHB244 by conjugation. The opd gene was driven by a strong promoter, Pp,bA. From both species, we obtained transgenic strains having organophosphorus-degradation activities. At 25~C, the whole-cell activities of the transgenic Anabaena and Nostoc strains were 0.163~0.001 and 0.289~0.042 unit/gg Chl a, respectively. However, most colonies resulting from the gene transfer showed no activity. PCR and DNA sequencing revealed deletions or rearrangements in the plasmid in some of the colonies. Expression of the green fluorescent protein gene from the same promoter in Anabaena sp. PCC 7120 showed similar results. These results suggest that there is the potential to promote the degradation of organophosphorus pollutants with transgenic cyanobacteria and that selection of high-expression transgenic colonies is important for genetic engineering of Anabaena and Nostoc species. For the first time, we established a gene transfer and expression system in an aggregating filamentous N2-fixing cyanobacterium. The genetic manipulation system of Nostoc muscorum FACHB244 could be utilized in the elimination of pollutants and large-scale production of valuable proteins or metabolites.
基金Sponsored by the Major State Scientific and Technological Projects of Water Pollution Control and Treatment(Grant No.2008ZX07208-005)
文摘The salt-resistant nitrogen-fixing cyanobacteria 888 was experimentally applied to the reclamation of saline and alkali soil in Songnen Plain in China. The pH, electrical conductivity (EC) and sodium adsorption ratio (SAR) of different saline soils were studied and compared. Results show that different saline soils exhibit various physico-chemical properties. Saline-sodic soils in Songnen Plain are ameliorated by using nitrogen-fixing blue-green algae 888 in the experiment. It is indicated that cyanobacteria 888 can grow in saline and alkaline soils, and the conditions favorable for its growth are soil moisture of 50% and dry algae inoculation at 0.03 mg/cm2. The main actions of nitrogen-fixing cyanobacteria are keeping the adsorbability of rubber sheath for sodium, increasing the organic matter content of the soils and decreasing the pH and the degree of salinity in the soils. But the arid climate and soil depth are the main factors that limit the restoration of saline and alkaline soils.
文摘Cyanothece sp. 113 is a unicellular, aerobic, diazotrophic and photosynthetic marine cyanobacterium. The optimal medium for exopolysaccharide yield by the strain was 70.0 g/L of NaCl, and 0.9 g/L of MgSO4 based on the modified F/2 medium for cultivation of marine algae. The optimal cultivation condition for exopolysaccharide yield by this cyanobacterial strain was 29℃, aeration, and continuous illumination at 86.0 μE/M^2/S. Under the optimal conditions, over 18.4 g/L of exopolysaccharide was produced within 12 days. This was so far the highest exopolysaccharide yield produced with strains of Cyanothece sp. obtained.
