Four arsenic-resistance genes(arsB,arsC,arsH,arsR) have been discovered in Acidithiobacillus ferrooxidans.Their gene sequences have been identified and three different arsenic-resistance mechanisms have been elucidate...Four arsenic-resistance genes(arsB,arsC,arsH,arsR) have been discovered in Acidithiobacillus ferrooxidans.Their gene sequences have been identified and three different arsenic-resistance mechanisms have been elucidated.However,the function of the arsH gene in At.ferrooxidans remains unclear.In order to evaluate the function of the arsH gene,we cloned it and expressed it in Escherichia coli.The protein was purified and its relative molecular mass was determined by SDS-PAGE(Sodium dodecyl sulfate-polyacrylamide gel electrophoresis).The results indicated that the relative molecular mass of the purified ArsH was approximately 29 kDa.The purified protein ArsH from E.coli BL21 was a flavoprotein that oxidized in vitro NADPH with an optimal pH of 6.4.展开更多
Soil and water conservation is essential for sustaining food production and for preserving the environment in arid and semi arid lands （ASALs） where conditions for agriculture and other land use systems are often ha...Soil and water conservation is essential for sustaining food production and for preserving the environment in arid and semi arid lands （ASALs） where conditions for agriculture and other land use systems are often harsh and unpredictable. The ASALs of Algeria are an important source of a variety of non wood forest products like Stipa tenacissima L. plant （esparto grass）. This research was conducted to determine the effects of different low concentration （〈 I%） polyacrylaJnide, Stipa tenacissima L. fiber （esparto grass fibers） and its mixtures with the polymer at water retention in arid and semi arid soil. All samples are characterized by infrared spectroscopy, X-ray Diffractometry, thermal analysis TG DSC and scanning electron micrographs （SEM）. The results showed that polymer blend in soil could improve better soil physical proprieties decreased evaporation and increase water retention in arid soils compared with application of any other blend at the same concentration. The use of Polyacrylamide-Cellulose blend appears to promise for reducing the labor cost of irrigation at arid and semi-arid soils, and offers safe and environmentally friendly inexpensive materials. The importance of Polyacrylamide-Cellulose blends to alleviate poor physical properties and retain water in these arid regions to sustain plant growth.展开更多
Molecular layer deposition （MLD） for the deposition of polyimide （PI） at low temperature of 110 ℃ has been firstly introduced into the field of membrane separation. With the optimized MLD deposition parameters, s...Molecular layer deposition （MLD） for the deposition of polyimide （PI） at low temperature of 110 ℃ has been firstly introduced into the field of membrane separation. With the optimized MLD deposition parameters, such low de- position temperature has successfully expanded the application of MLD for the surface modification of polymeric materials. Globular PI particulates grow on both the free surfaces as well as the pore walls of the polypropylene （PP） membranes as isolated islands during progressive precursor exposures. The PI-deposited PP membranes ex- hibit synergistically improved performances in various aspects. Evidently improved surface hydrophilicity and per- meation performance （30%） have been achieved v/a the MLD deposition of polyimide films. The overall separation efficiency maintained higher than 85% even after 250 cycles of MLD deposition. More importantly, the thermal sta- bility has been improved and the integrity of the porous structure for PI-deposited PP membranes has been well preserved even after harsh treatment, which ensures its potential application in industries.展开更多
A novel thermo-sensitive superabsorbent hydrogel with salt- and pH-responsiveness properties was obtained by grafting of mixtures of acrylic acid （AA） and N-isopropylacrylamide （N1PAM） monomers onto kappa-carragee...A novel thermo-sensitive superabsorbent hydrogel with salt- and pH-responsiveness properties was obtained by grafting of mixtures of acrylic acid （AA） and N-isopropylacrylamide （N1PAM） monomers onto kappa-carrageenan, kC, using ammonium persulfate （APS） as a free radical initiator in the presence of methylene bisacrylamide （MBA） as a crosslinker. Infrared spectroscopy was carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was examined by scanning electron microscopy （SEM）. The effect of MBA concentration and AA/NIPAM weight ratio on the water absorbency capacity has been investigated. The swelling variations of hydrogels were explained according to swelling theory based on the hydrogel chemical structure. The hydrogels exhibited salt-sensitivity and cation exchange properties. The temperature- and pH-reversibility properties of the hydrogels make the intelligent polymers as good candidates for considering as potential carriers for bioactive agents, e.g. drugs.展开更多
基金Project(50621063) supported by the National Natural Science Foundation of ChinaProject(2004CB619201) supported by the National Basic Research Program of China
文摘Four arsenic-resistance genes(arsB,arsC,arsH,arsR) have been discovered in Acidithiobacillus ferrooxidans.Their gene sequences have been identified and three different arsenic-resistance mechanisms have been elucidated.However,the function of the arsH gene in At.ferrooxidans remains unclear.In order to evaluate the function of the arsH gene,we cloned it and expressed it in Escherichia coli.The protein was purified and its relative molecular mass was determined by SDS-PAGE(Sodium dodecyl sulfate-polyacrylamide gel electrophoresis).The results indicated that the relative molecular mass of the purified ArsH was approximately 29 kDa.The purified protein ArsH from E.coli BL21 was a flavoprotein that oxidized in vitro NADPH with an optimal pH of 6.4.
文摘Soil and water conservation is essential for sustaining food production and for preserving the environment in arid and semi arid lands （ASALs） where conditions for agriculture and other land use systems are often harsh and unpredictable. The ASALs of Algeria are an important source of a variety of non wood forest products like Stipa tenacissima L. plant （esparto grass）. This research was conducted to determine the effects of different low concentration （〈 I%） polyacrylaJnide, Stipa tenacissima L. fiber （esparto grass fibers） and its mixtures with the polymer at water retention in arid and semi arid soil. All samples are characterized by infrared spectroscopy, X-ray Diffractometry, thermal analysis TG DSC and scanning electron micrographs （SEM）. The results showed that polymer blend in soil could improve better soil physical proprieties decreased evaporation and increase water retention in arid soils compared with application of any other blend at the same concentration. The use of Polyacrylamide-Cellulose blend appears to promise for reducing the labor cost of irrigation at arid and semi-arid soils, and offers safe and environmentally friendly inexpensive materials. The importance of Polyacrylamide-Cellulose blends to alleviate poor physical properties and retain water in these arid regions to sustain plant growth.
基金Supported by the National Basic Research Program of China(2015CB655301)the Jiangsu Natural Science Foundation(BK20150063)+1 种基金the Natural Science Research Program of the Jiangsu Higher Education Institutions(13KJA430005)the Project of Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Molecular layer deposition （MLD） for the deposition of polyimide （PI） at low temperature of 110 ℃ has been firstly introduced into the field of membrane separation. With the optimized MLD deposition parameters, such low de- position temperature has successfully expanded the application of MLD for the surface modification of polymeric materials. Globular PI particulates grow on both the free surfaces as well as the pore walls of the polypropylene （PP） membranes as isolated islands during progressive precursor exposures. The PI-deposited PP membranes ex- hibit synergistically improved performances in various aspects. Evidently improved surface hydrophilicity and per- meation performance （30%） have been achieved v/a the MLD deposition of polyimide films. The overall separation efficiency maintained higher than 85% even after 250 cycles of MLD deposition. More importantly, the thermal sta- bility has been improved and the integrity of the porous structure for PI-deposited PP membranes has been well preserved even after harsh treatment, which ensures its potential application in industries.
文摘A novel thermo-sensitive superabsorbent hydrogel with salt- and pH-responsiveness properties was obtained by grafting of mixtures of acrylic acid （AA） and N-isopropylacrylamide （N1PAM） monomers onto kappa-carrageenan, kC, using ammonium persulfate （APS） as a free radical initiator in the presence of methylene bisacrylamide （MBA） as a crosslinker. Infrared spectroscopy was carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was examined by scanning electron microscopy （SEM）. The effect of MBA concentration and AA/NIPAM weight ratio on the water absorbency capacity has been investigated. The swelling variations of hydrogels were explained according to swelling theory based on the hydrogel chemical structure. The hydrogels exhibited salt-sensitivity and cation exchange properties. The temperature- and pH-reversibility properties of the hydrogels make the intelligent polymers as good candidates for considering as potential carriers for bioactive agents, e.g. drugs.
