The main aim of this work was to investigate the effects of salt stress conditions on the inorganic and organic compounds of extracts from six filamentous cyanobacteria： Arthospira platensis, Oscillatoria sp., Oscill...The main aim of this work was to investigate the effects of salt stress conditions on the inorganic and organic compounds of extracts from six filamentous cyanobacteria： Arthospira platensis, Oscillatoria sp., Oscillatoria salina, Tolypothrix sp., Oscillatoria sp. SWU （Srinakharinwirot University）121 and Tolypothrix sp. SWU213. All cyanobacteria were cultures in BG （blue-green algae）11 medium： pH 7.5 at 35 ℃ for 30 days of sodium chloride in the culture medium presented 0-1.0 M. The cyanobacteria isolates grew well in BGH medium, nevertheless, growth of the majority of isolates was reduced by about 50% in the same medium containing 0.5 M NaCl. The inorganic compounds such as, Na^＋, K^＋, Ca^2＋, Mg^2＋, NH4^＋ and NO3^- were determined. All ions were reduced when NaCI was increased and Na^＋ showed highest amount in the medium followed with Mg^2＋, NH4^＋, NO3^- and Ca^2＋ in all cyanobaeteria. The organic compounds such as, betaine, proline and total lipid were determined under normal and salt stress conditions. We found that all cyanobacteria increased interesting organic compound under salt stress condition at least two folds to compare with normal condition. This is the first finding indicated that freshwater filamentous cyanobacteria could grow under salt stresses by accumulation of some organic compounds as osmoprotectants such as betaine and amino acids, being the reduction related to the amount of inorganies compounds present in cultures.展开更多
Photo-induced graft copolymerization of methyl methacrylate（MMA） onto sodium salt of partially carboxymethylated guar gum（Na-PCMGG, DS = 0.291） was carried out in an aqueous medium using ceric ammonium nitrate（CA...Photo-induced graft copolymerization of methyl methacrylate（MMA） onto sodium salt of partially carboxymethylated guar gum（Na-PCMGG, DS = 0.291） was carried out in an aqueous medium using ceric ammonium nitrate（CAN） as photoinitiator to synthesize a novel graft copolymer, Na-PCMGG-g-PMMA, which may find its potential application as a metal adsorbent. The influences of synthesis variables such as concentrations of photoinitiator（CAN）, nitric acid and monomer（MMA） as well as reaction time, temperature and amount of substrate on the grafting yields were studied and the reaction conditions for optimum photo-grafting were evaluated. At optimum concentration, the maximum values of the grafting yields achieved were G = 271.61% and GE = 63.89%. The experimental results were found to be in very good agreement with the proposed kinetic scheme. The photo-graft copolymerization of MMA onto Na-PCMGG（ DS = 0.291） was also carried out in the presence and absence of ultraviolet radiation for studying the efficiency of the photoinitiator. The influence of carboxymethyl groups introduced onto the guar gum molecules with regard to its behavior towards ultra-violet radiation induced grafting with MMA was also investigated. Photo-grafting process was confirmed and the products were characterized with the help of the spectroscopic（1H-NMR and FTIR） and SEM techniques.展开更多
文摘The main aim of this work was to investigate the effects of salt stress conditions on the inorganic and organic compounds of extracts from six filamentous cyanobacteria： Arthospira platensis, Oscillatoria sp., Oscillatoria salina, Tolypothrix sp., Oscillatoria sp. SWU （Srinakharinwirot University）121 and Tolypothrix sp. SWU213. All cyanobacteria were cultures in BG （blue-green algae）11 medium： pH 7.5 at 35 ℃ for 30 days of sodium chloride in the culture medium presented 0-1.0 M. The cyanobacteria isolates grew well in BGH medium, nevertheless, growth of the majority of isolates was reduced by about 50% in the same medium containing 0.5 M NaCl. The inorganic compounds such as, Na^＋, K^＋, Ca^2＋, Mg^2＋, NH4^＋ and NO3^- were determined. All ions were reduced when NaCI was increased and Na^＋ showed highest amount in the medium followed with Mg^2＋, NH4^＋, NO3^- and Ca^2＋ in all cyanobaeteria. The organic compounds such as, betaine, proline and total lipid were determined under normal and salt stress conditions. We found that all cyanobacteria increased interesting organic compound under salt stress condition at least two folds to compare with normal condition. This is the first finding indicated that freshwater filamentous cyanobacteria could grow under salt stresses by accumulation of some organic compounds as osmoprotectants such as betaine and amino acids, being the reduction related to the amount of inorganies compounds present in cultures.
文摘Photo-induced graft copolymerization of methyl methacrylate（MMA） onto sodium salt of partially carboxymethylated guar gum（Na-PCMGG, DS = 0.291） was carried out in an aqueous medium using ceric ammonium nitrate（CAN） as photoinitiator to synthesize a novel graft copolymer, Na-PCMGG-g-PMMA, which may find its potential application as a metal adsorbent. The influences of synthesis variables such as concentrations of photoinitiator（CAN）, nitric acid and monomer（MMA） as well as reaction time, temperature and amount of substrate on the grafting yields were studied and the reaction conditions for optimum photo-grafting were evaluated. At optimum concentration, the maximum values of the grafting yields achieved were G = 271.61% and GE = 63.89%. The experimental results were found to be in very good agreement with the proposed kinetic scheme. The photo-graft copolymerization of MMA onto Na-PCMGG（ DS = 0.291） was also carried out in the presence and absence of ultraviolet radiation for studying the efficiency of the photoinitiator. The influence of carboxymethyl groups introduced onto the guar gum molecules with regard to its behavior towards ultra-violet radiation induced grafting with MMA was also investigated. Photo-grafting process was confirmed and the products were characterized with the help of the spectroscopic（1H-NMR and FTIR） and SEM techniques.
