The action of etching and damage by 20 keV N+ beam on the cells of Deinococcus radiodurans and Escherichia coli was investigated by scanning electron microscope (SEM) and the electron spin resonance (ESR) spectrum of ...The action of etching and damage by 20 keV N+ beam on the cells of Deinococcus radiodurans and Escherichia coli was investigated by scanning electron microscope (SEM) and the electron spin resonance (ESR) spectrum of free radicals. The results showed that N+ implantation exerted the direct action of etching and damage of momentum transferring and the indirect action of the free radicals of energy deposition on their cells, many microholes were found on the surface of cells' wall and /or membrane by SEM, the damaged DNA was determined using DNA unwinding technique, and the signal of free radicals was measured by ESR. The degree of damage to cells by ion beam gradually increased with the increase implantation dose. With the post-treatment of 2 mmol/l caffeine and 0.5 mmol / l Na2-EDTA, the survival rate of D.radiodurans and E.coli further decreased in the order of caffeine > Na2-EDTA > control, and this suggested that low energy ion beam could be implanted into nucleus, doing a damage to DNA and resulting in the mutation of organisms.展开更多
Based on the mechanism of stray current generation in underground structures,the concrete durability test device for stray current and sulphate in typical soil environment was designed to study the damage of concrete ...Based on the mechanism of stray current generation in underground structures,the concrete durability test device for stray current and sulphate in typical soil environment was designed to study the damage of concrete under the action of stray current and sulphate.The deterioration law of concrete under the action of stray current and sulphate was studied by microscopic techniques such as scanning electron microscopy (SEM) and X-ray diffraction (XRD).The microstructure of corroded concrete was observed to determine the phase composition of erosion products.The damage performances such as quality,strength,and dynamic elastic mode of corroded concrete were performed.The experimental results show that,under the action of stray current,the products of sulfate-eroded concrete are mainly gypsum,ettringite,and thaumasite;the stray current accelerates the hydration process of cement and the erosion of concrete by sulfate;when the concrete pores are filled with the erosion product,there is an increase of approximately 10% in the concrete compressive strength and dynamic elastic modulus;and the concrete compressive strength is more sensitive to the stray current electrification period than the current intensity.展开更多
基金This work is supported by the National Science Foundation of china (19605005)
文摘The action of etching and damage by 20 keV N+ beam on the cells of Deinococcus radiodurans and Escherichia coli was investigated by scanning electron microscope (SEM) and the electron spin resonance (ESR) spectrum of free radicals. The results showed that N+ implantation exerted the direct action of etching and damage of momentum transferring and the indirect action of the free radicals of energy deposition on their cells, many microholes were found on the surface of cells' wall and /or membrane by SEM, the damaged DNA was determined using DNA unwinding technique, and the signal of free radicals was measured by ESR. The degree of damage to cells by ion beam gradually increased with the increase implantation dose. With the post-treatment of 2 mmol/l caffeine and 0.5 mmol / l Na2-EDTA, the survival rate of D.radiodurans and E.coli further decreased in the order of caffeine > Na2-EDTA > control, and this suggested that low energy ion beam could be implanted into nucleus, doing a damage to DNA and resulting in the mutation of organisms.
基金Funded by the National Natural Science Foundation of China (Nos.51590914 and 52078415)the Science and Technology Program of Shaanxi Province (Nos.2019KW-047, 20JY034, and SGSNXA00XGJS20015 60)the China Scholarship Council (No.202008610268)。
文摘Based on the mechanism of stray current generation in underground structures,the concrete durability test device for stray current and sulphate in typical soil environment was designed to study the damage of concrete under the action of stray current and sulphate.The deterioration law of concrete under the action of stray current and sulphate was studied by microscopic techniques such as scanning electron microscopy (SEM) and X-ray diffraction (XRD).The microstructure of corroded concrete was observed to determine the phase composition of erosion products.The damage performances such as quality,strength,and dynamic elastic mode of corroded concrete were performed.The experimental results show that,under the action of stray current,the products of sulfate-eroded concrete are mainly gypsum,ettringite,and thaumasite;the stray current accelerates the hydration process of cement and the erosion of concrete by sulfate;when the concrete pores are filled with the erosion product,there is an increase of approximately 10% in the concrete compressive strength and dynamic elastic modulus;and the concrete compressive strength is more sensitive to the stray current electrification period than the current intensity.
