Bacteriophages infected different serotypes of Klebsiella were isolated from sewage. Among them, a heatstable polysaccharide depolymerase enzyme which could degrade bacterial exopolysaccharide effectively was prepared...Bacteriophages infected different serotypes of Klebsiella were isolated from sewage. Among them, a heatstable polysaccharide depolymerase enzyme which could degrade bacterial exopolysaccharide effectively was prepared from the phage infecting Klebsiella K13. Treatment at 60℃ for 30 min could inactivate most of the K13 phage, with the titration decreasing from 6.4×10^8 PFU/mL to 1.6×10^6 PFU/mL. However, no obvious loss of phage enzyme activity was found after this treatment. The optimum hydrolytic temperature of phage enzyme was 60℃, with an activity 57 % higher than that at 30℃. The addition of phage enzyme could result in a rapid decrease of viscosity of exopolysaccharide （EPS） solution within minutes, indicating that K13 phage polysaccharide depolymerase acts as a kind of endo-glycanohydrolase. HPLC and reducing sugar analysis showed that the hydrolysis of EPS approached approximately the maxi-mum at 4h when the final concentration of phage was 6.0 x los PFU/mL. The results showed that K/eb-siella K13 phage depolymerase enzyme could be used as a good tool for the preparation of EPS oligosac- charide.展开更多
The development of hydrogen redox electric power generators for infinite cruising range electric vehicles represents a true technological breakthrough. Such systems consist of a polymer electrolyte membrane hydrogen e...The development of hydrogen redox electric power generators for infinite cruising range electric vehicles represents a true technological breakthrough. Such systems consist of a polymer electrolyte membrane hydrogen electrolytic cell equipped with an electrostatic-induction potential-superposed water electrolytic cell that provides a stoichiometric H2-O2 fuel mixture during operation of the vehicle. This generator functions with zero power input, zero matter input and zero emission due to the so-called ＂zero power input＂ electrostatic-to-chemical energy conversion occurring in the electrolytic cell. Here, theoretical simulations were performed to verify the target performance of such generators, assuming a pair of FC （fuel cell） and electrolytic cell stacks, both of which are commercially available.展开更多
Pyrolysis gas chromatography is not a comprehensive analysis method for the determination of acrylics. Polar acrylic monomers show low abundance by gas chromatography. Because of this, a home-made pyrolysis liquid chr...Pyrolysis gas chromatography is not a comprehensive analysis method for the determination of acrylics. Polar acrylic monomers show low abundance by gas chromatography. Because of this, a home-made pyrolysis liquid chromatographic injector by means of cryogenic-focussing is developed to determine the presence and concentration of hydroxyl and carboxyl functional monomers present in water- and solvent-borne acrylics. We have shown the prove-of-principle of using cryogenic-focussing for UPLC （pyrolysis-ultra-performance liquid chromatography） injection.展开更多
As an important energy carrier in terms of carbon neutrality,green hydrogen produced by water electrolysis using renewable electricity has attracted worldwide attention.The polymer electrolyte water electrolyzer(PEWE)...As an important energy carrier in terms of carbon neutrality,green hydrogen produced by water electrolysis using renewable electricity has attracted worldwide attention.The polymer electrolyte water electrolyzer(PEWE)has the potential to be a mainstay in the green hydrogen market in the future because of its superior performance.However,the development of PEWE is constrained by the slow progress of the membrane electrode assembly(MEA),which is an essential component of PEWE and largely determines the cost and performance of the system.Therefore,the MEA must be optimized from the aspects of reducing cost and improving performance to promote the development of PEWEs.In this review,we first discuss the recent progress of the materials and design strategies of MEA,including the cost,activity,and stability of catalysts,distribution and thickness of ionomers,and ion transport efficiency of ion exchange membranes(IEMs).Then,the effects of all components and interlayer interfaces on the ions,electrons,and mass transfer in MEA and,consequently,the performance of PEWE are analyzed.Finally,we propose perspectives on developing MEA by optimizing the catalyst activity and stability of IEM,interface contact between adjacent components,and evaluation methods of performance.展开更多
基金the National Natural Science Foundation of China(No40506027 and No30771646)the Doctoral Foundation of Shandong Province(No2005BS02015)
文摘Bacteriophages infected different serotypes of Klebsiella were isolated from sewage. Among them, a heatstable polysaccharide depolymerase enzyme which could degrade bacterial exopolysaccharide effectively was prepared from the phage infecting Klebsiella K13. Treatment at 60℃ for 30 min could inactivate most of the K13 phage, with the titration decreasing from 6.4×10^8 PFU/mL to 1.6×10^6 PFU/mL. However, no obvious loss of phage enzyme activity was found after this treatment. The optimum hydrolytic temperature of phage enzyme was 60℃, with an activity 57 % higher than that at 30℃. The addition of phage enzyme could result in a rapid decrease of viscosity of exopolysaccharide （EPS） solution within minutes, indicating that K13 phage polysaccharide depolymerase acts as a kind of endo-glycanohydrolase. HPLC and reducing sugar analysis showed that the hydrolysis of EPS approached approximately the maxi-mum at 4h when the final concentration of phage was 6.0 x los PFU/mL. The results showed that K/eb-siella K13 phage depolymerase enzyme could be used as a good tool for the preparation of EPS oligosac- charide.
文摘The development of hydrogen redox electric power generators for infinite cruising range electric vehicles represents a true technological breakthrough. Such systems consist of a polymer electrolyte membrane hydrogen electrolytic cell equipped with an electrostatic-induction potential-superposed water electrolytic cell that provides a stoichiometric H2-O2 fuel mixture during operation of the vehicle. This generator functions with zero power input, zero matter input and zero emission due to the so-called ＂zero power input＂ electrostatic-to-chemical energy conversion occurring in the electrolytic cell. Here, theoretical simulations were performed to verify the target performance of such generators, assuming a pair of FC （fuel cell） and electrolytic cell stacks, both of which are commercially available.
文摘Pyrolysis gas chromatography is not a comprehensive analysis method for the determination of acrylics. Polar acrylic monomers show low abundance by gas chromatography. Because of this, a home-made pyrolysis liquid chromatographic injector by means of cryogenic-focussing is developed to determine the presence and concentration of hydroxyl and carboxyl functional monomers present in water- and solvent-borne acrylics. We have shown the prove-of-principle of using cryogenic-focussing for UPLC （pyrolysis-ultra-performance liquid chromatography） injection.
基金the National Natural Science Foundation of China(52188101)the National Science Fund for Distinguished Young Scholars(52125309)+2 种基金Guangdong Basic and Applied Basic Research Foundation(2021A1515110829)Guangdong Innovative and Entrepreneurial Research Team Program(2017ZT07C341)Shenzhen Basic Research Project(JCYJ20200109144620815).
文摘As an important energy carrier in terms of carbon neutrality,green hydrogen produced by water electrolysis using renewable electricity has attracted worldwide attention.The polymer electrolyte water electrolyzer(PEWE)has the potential to be a mainstay in the green hydrogen market in the future because of its superior performance.However,the development of PEWE is constrained by the slow progress of the membrane electrode assembly(MEA),which is an essential component of PEWE and largely determines the cost and performance of the system.Therefore,the MEA must be optimized from the aspects of reducing cost and improving performance to promote the development of PEWEs.In this review,we first discuss the recent progress of the materials and design strategies of MEA,including the cost,activity,and stability of catalysts,distribution and thickness of ionomers,and ion transport efficiency of ion exchange membranes(IEMs).Then,the effects of all components and interlayer interfaces on the ions,electrons,and mass transfer in MEA and,consequently,the performance of PEWE are analyzed.Finally,we propose perspectives on developing MEA by optimizing the catalyst activity and stability of IEM,interface contact between adjacent components,and evaluation methods of performance.
