At subzero temperature, the startup capability and performance of polymer electrolyte membrane fuel cell (PEMFC) deteriorates markedly. The object of this work is to study the degradation mechanism of key components o...At subzero temperature, the startup capability and performance of polymer electrolyte membrane fuel cell (PEMFC) deteriorates markedly. The object of this work is to study the degradation mechanism of key components of PEMFC-membrane-electrode assembly (MEA) and seek feasible measures to avoid degradation. The effect of freeze/thaw cycles on the structure of MEA is investigated based on porosity and SEM measurement. The performance of a single cell was also tested before and after repetitious freeze/thaw cycles. The experimental results indicated that the performance of a PEMFC decreased along with the total operating time as well as the pore size distribution shifting and micro configuration changing. However, when the redundant water had been removed by gas purging, the performance of the PEMFC stack was almost resumed when it experienced again the same subzero temperature test. These results show that it is necessary to remove the water in PEMFCs to maintain stable performance under subzero temperature and gas purging is proved to be the effective operation.展开更多
Background An effective purging technique plays an important role in autologous hematopoietic stem cells transplantation Photodynamic therapy (PDT) provides a novel approach for this purpose This study dealt with the ...Background An effective purging technique plays an important role in autologous hematopoietic stem cells transplantation Photodynamic therapy (PDT) provides a novel approach for this purpose This study dealt with the purging effects of disulfodiphthalimidomethyl phthalolcyanine zinc (ZnPcS2P2)based photodynamic therapy (ZnPcPDT) Methods Fluorescence intensity of cell extracts was measured using a fluoresence spectrophotometry The proliferative potency of K562 cells and HL60 cells was detected using MTT colorimetric assay, Typan blue dye exclusion method, colony formation test The proliferative potency of normal hematopoietic cells was evaluated using mixture colonyforming unit (CFUMix), granulocytemacrophage colonyforming unit (CFUGM), and erythrocyte colonyforming unit (CFUE) assays K562 cells were mixed with normal mononuclear cells (MNCs) at ratios of 1∶100 and 1∶1000 for creating the model of simulated remission bone marrow Colony formation test and nestedRTPCR were carried out to detect the residual K562 cells in cell mixture Results After a 5hour incubation with ZnPcS2P2, the content of ZnPcS2P2 in normal MNCs was the lowest value At the same time, the content in K562 cells and HL60 cells was very high Therefore, the time point was selected as the optimal one for irradiating the cell suspensions ZnPcPDT could significantly kill proliferative K562 cells and HL60 cells in a dosedependent manner At the concentration of 10 μg/ml, the inhibitory rate of ZnPcPDT on the colony formation was 100% for K562 cells, 897% for HL60 cells 025 μg/ml ZnPcPDT could completely photoinactivate residual K562 cells in the simulated remission bone marrow Under an identical condition, the inhibitory rates of CFUMix, CFUGM, CFUE were 180%, 186%, and 178% respectively Conclusion ZnPcPDT appears to be a promising approach for bone marrow purging展开更多
Alumina–spinel refractories used in slit-type purging plugs are susceptible to cross-sectional damage,resulting in a serious mismatch between their service life and that of ladle.Alumina–calcium hexaluminate refract...Alumina–spinel refractories used in slit-type purging plugs are susceptible to cross-sectional damage,resulting in a serious mismatch between their service life and that of ladle.Alumina–calcium hexaluminate refractories have gradually become the new trend in purging plug materials with the development of refining technology.The thermomechanical damage of slit-type purging plugs with alumina–calcium hexaluminate refractory was investigated by the thermo-solid coupling simulation.Combined with the polynomial fitting and design of experiments methods,the influence of thermophysical parameters on temperature and thermal stress of alumina–calcium hexaluminate refractories for purging plugs was systematically analyzed.The results show that the maximum thermal stress of the purging plugs appears during the stages of steel transporting and stirring,and the vulnerable parts are located above Y=0.323 m.The thermal conductivity and the coefficient of thermal expansion of the material are the most sensitive parameters to the temperature and thermal stress inside the structure,respectively.The addition of more calcium hexaluminate can relieve the stress concentration and large deformation around the slits.Consequently,when the content of calcium hexaluminate is 47 wt.%and in the form of aggregate-binder,the temperature and thermal stress distribution inside the refractory are optimal,which can effectively improve the service life of the slit-type purging plug.展开更多
Magnesia-chrome porous purging plugs are crucial functional components to remove inclusions and stabilize the flow field during iron and steel smelting.However,practical applications of magnesia-chrome porous purging ...Magnesia-chrome porous purging plugs are crucial functional components to remove inclusions and stabilize the flow field during iron and steel smelting.However,practical applications of magnesia-chrome porous purging materials are stil hampered by the poor scouring resistance to molten steel and unstable air permeability owing to their low mechanical properties and uncontrollable pore structure.Therefore,the particle-packing type magnesiachrome porous purging materials reinforced by in situ formed spinel were prepared using fused magnesia-chrome particles and Al powders as major raw materials.The results show that in situ formed spinel solid solutions in bonding phase led to the decreased median pore size and increased pore surface fractal dimension from the reactions between Al powders and magnesia-chrome particles and along with high-temperature sintering,bonding between magnesia-chrome particles and the resultant mechanical properties of materials were greatly elevated.Besides,the results of air permeability tests and polynomial ftting indicated that the formation of spinel solid solutions was the main contributing factor for controllable air permeability,and pressure drop of porous purging materials was positively correlated with surface fractal dimension of pores.Moreover,the as-prepared porous purging materials added with 6 wt.%Al powders obtained the maximum cold crushing strength(54.2 MPa)and hot modulus of rupture(12.9 MPa)with median pore size of 24.06μm and ftting non-Darcian permeability coefficient of 0.97×10^(-6)m.展开更多
This paper aims to improve the corrosion resistance of dispersive purging plugs.White fused corundum particles and fine powder,α-Al_(2)O_(3) micropowder,Cr_(2)O_(3) micropowder,Guangxi clay and zircon powder were use...This paper aims to improve the corrosion resistance of dispersive purging plugs.White fused corundum particles and fine powder,α-Al_(2)O_(3) micropowder,Cr_(2)O_(3) micropowder,Guangxi clay and zircon powder were used as the main raw materials.The mass ratio of white fused corundum particles and fine powder was fixed at 85:15,and 0,1%,2%,or 3%(by mass)of zircon fine powder was added to replace the same amount of white fused corundum fine powder.The corundum porous material was prepared by the particle stacking pore-forming method at 1650℃for 3 h.The effect of the zircon addition on the properties and microstructure of porous materials was investigated.The results show that:after adding zircon,the permeability of the porous material increases,the cold and hot strengths increase obviously,and the expansion rate after firing decreases.When the addition of zircon is 2%,the comprehensive performance of the specimen is optimal with the smallest linear change rate and the highest permeability.展开更多
Purging plug refractories in China typically contain around 3 mass% of super-fine chromium oxide in the matrix in order to improve the performance of the purging plugs, primarily, slag corrosion and wear resistance. A...Purging plug refractories in China typically contain around 3 mass% of super-fine chromium oxide in the matrix in order to improve the performance of the purging plugs, primarily, slag corrosion and wear resistance. Alternatives to chromium oxide containing refractories have gained interest due to health concerns related to the formation of soluble chromium compounds over long storage periods of refractory wastes. Super-ground reactive alumina can replace chromium oxide in purging plug refractories and this paper discussed the new reactive alumina E-SY 88 in comparison to chromium oxide in a typical purging plug castable. The mixing behaviour, wet castable properties, as well as cured, dried, and fired properties at different temperatures up to 1 600 ℃ were compared. In addition, the hot modulus of rupture, creep behaviour, thermal shock resistance and slag corrosion resistance were tested. The microstructure after slag corrosion was investigated by SEM. The results prove that E-SY 88 is an economically viable technical alternative to chromium oxide in purging plug refractories.展开更多
OBJECTIVE:To elucidate the mechanism of the nourishing Yin and purging fire Chinese herbal mixture(NYPF)in delaying light-induced premature puberty in rats.METHODS:Twenty-one days old female SpragueDawley rats were ra...OBJECTIVE:To elucidate the mechanism of the nourishing Yin and purging fire Chinese herbal mixture(NYPF)in delaying light-induced premature puberty in rats.METHODS:Twenty-one days old female SpragueDawley rats were randomly assigned to normal group(N),long light exposure group(L),NYPF and normal saline group(NS).Rats in the L,NYPF and NS groups were exposed to 16 h:350 lux light/8 h:dark,while rats in the N group were exposed to 12 h:50 lux light/12 h:dark.NYPF and normal saline was administered to the rats in the NYPF group or NS group,respectively,from day 21.Five rats in every group were sacrificed at 9 p.m.on day 28(P28),on the day when rat's vulva opened in the L group(L-VO),on the day when the first estrous interphase occurred in rats of L group(L-E1),and on the day when the second estrous interphase occurred in rats of L group(L-E2),respectively.RESULITS:On day 34,all rats in the L group,80%of rats in the NS group,40%of rats in the N group,and 20%of rats in the NYPF group showed complete opening of the vulva.At P28,m RNA level of hypothalamic kisspeptin(Kiss-1)in the L group was significantly higher than that in the N group(P<0.05).The rats in the L and NS groups had significantly lower hypothalamic argininephenylalanine-amide(RFamide)-related peptide 3(RFRP-3)m RNA levels than those in the N group(P<0.05),whereas RFRP-3 m RNA level was significantly higher in the NYPF group than that in the L group(P<0.05).At L-VO,the ovarian index of the L and NS groups was significantly higher than that of the N group(P<0.05)and estradiol(E2)level of the NYPF group was significantly lower than that of the N and NS groups(P<0.05);hypothalamic Kiss-1 m RNA level in the L and NS groups was significantly higher than that in the N and NYPF groups(P<0.05),whereas hypothalamic RFRP-3 m RNA level in the L,NYPF,and NS groups was significantly lower than that in the N group(P<0.05).At L-E1,E2 level of the L and NS groups was significantly higher than that of the N group(P<0.01),whereas it was significantly lower in the NYPF group展开更多
基金Supported by the National Natural Science Foundation of China (No.20206030) and Ministry of Science and Technology 863 Hi-Technology Research and Development Program of China (2005AA501660).
文摘At subzero temperature, the startup capability and performance of polymer electrolyte membrane fuel cell (PEMFC) deteriorates markedly. The object of this work is to study the degradation mechanism of key components of PEMFC-membrane-electrode assembly (MEA) and seek feasible measures to avoid degradation. The effect of freeze/thaw cycles on the structure of MEA is investigated based on porosity and SEM measurement. The performance of a single cell was also tested before and after repetitious freeze/thaw cycles. The experimental results indicated that the performance of a PEMFC decreased along with the total operating time as well as the pore size distribution shifting and micro configuration changing. However, when the redundant water had been removed by gas purging, the performance of the PEMFC stack was almost resumed when it experienced again the same subzero temperature test. These results show that it is necessary to remove the water in PEMFCs to maintain stable performance under subzero temperature and gas purging is proved to be the effective operation.
文摘Background An effective purging technique plays an important role in autologous hematopoietic stem cells transplantation Photodynamic therapy (PDT) provides a novel approach for this purpose This study dealt with the purging effects of disulfodiphthalimidomethyl phthalolcyanine zinc (ZnPcS2P2)based photodynamic therapy (ZnPcPDT) Methods Fluorescence intensity of cell extracts was measured using a fluoresence spectrophotometry The proliferative potency of K562 cells and HL60 cells was detected using MTT colorimetric assay, Typan blue dye exclusion method, colony formation test The proliferative potency of normal hematopoietic cells was evaluated using mixture colonyforming unit (CFUMix), granulocytemacrophage colonyforming unit (CFUGM), and erythrocyte colonyforming unit (CFUE) assays K562 cells were mixed with normal mononuclear cells (MNCs) at ratios of 1∶100 and 1∶1000 for creating the model of simulated remission bone marrow Colony formation test and nestedRTPCR were carried out to detect the residual K562 cells in cell mixture Results After a 5hour incubation with ZnPcS2P2, the content of ZnPcS2P2 in normal MNCs was the lowest value At the same time, the content in K562 cells and HL60 cells was very high Therefore, the time point was selected as the optimal one for irradiating the cell suspensions ZnPcPDT could significantly kill proliferative K562 cells and HL60 cells in a dosedependent manner At the concentration of 10 μg/ml, the inhibitory rate of ZnPcPDT on the colony formation was 100% for K562 cells, 897% for HL60 cells 025 μg/ml ZnPcPDT could completely photoinactivate residual K562 cells in the simulated remission bone marrow Under an identical condition, the inhibitory rates of CFUMix, CFUGM, CFUE were 180%, 186%, and 178% respectively Conclusion ZnPcPDT appears to be a promising approach for bone marrow purging
基金financial support from the National Natural Science Foundation of China(U20A20270,2020BHB010,51702240,51872211 and 51802230).
文摘Alumina–spinel refractories used in slit-type purging plugs are susceptible to cross-sectional damage,resulting in a serious mismatch between their service life and that of ladle.Alumina–calcium hexaluminate refractories have gradually become the new trend in purging plug materials with the development of refining technology.The thermomechanical damage of slit-type purging plugs with alumina–calcium hexaluminate refractory was investigated by the thermo-solid coupling simulation.Combined with the polynomial fitting and design of experiments methods,the influence of thermophysical parameters on temperature and thermal stress of alumina–calcium hexaluminate refractories for purging plugs was systematically analyzed.The results show that the maximum thermal stress of the purging plugs appears during the stages of steel transporting and stirring,and the vulnerable parts are located above Y=0.323 m.The thermal conductivity and the coefficient of thermal expansion of the material are the most sensitive parameters to the temperature and thermal stress inside the structure,respectively.The addition of more calcium hexaluminate can relieve the stress concentration and large deformation around the slits.Consequently,when the content of calcium hexaluminate is 47 wt.%and in the form of aggregate-binder,the temperature and thermal stress distribution inside the refractory are optimal,which can effectively improve the service life of the slit-type purging plug.
基金the National Natural Science Foundation of China(U21A2057)the Key Research and Development Project of Hubei Province,China(2022BAA032).
文摘Magnesia-chrome porous purging plugs are crucial functional components to remove inclusions and stabilize the flow field during iron and steel smelting.However,practical applications of magnesia-chrome porous purging materials are stil hampered by the poor scouring resistance to molten steel and unstable air permeability owing to their low mechanical properties and uncontrollable pore structure.Therefore,the particle-packing type magnesiachrome porous purging materials reinforced by in situ formed spinel were prepared using fused magnesia-chrome particles and Al powders as major raw materials.The results show that in situ formed spinel solid solutions in bonding phase led to the decreased median pore size and increased pore surface fractal dimension from the reactions between Al powders and magnesia-chrome particles and along with high-temperature sintering,bonding between magnesia-chrome particles and the resultant mechanical properties of materials were greatly elevated.Besides,the results of air permeability tests and polynomial ftting indicated that the formation of spinel solid solutions was the main contributing factor for controllable air permeability,and pressure drop of porous purging materials was positively correlated with surface fractal dimension of pores.Moreover,the as-prepared porous purging materials added with 6 wt.%Al powders obtained the maximum cold crushing strength(54.2 MPa)and hot modulus of rupture(12.9 MPa)with median pore size of 24.06μm and ftting non-Darcian permeability coefficient of 0.97×10^(-6)m.
基金This work was sponsored by the National Natural Science Foundation of China(No.52172029)the Natural Science Foundation of Henan(No.202300410473).
文摘This paper aims to improve the corrosion resistance of dispersive purging plugs.White fused corundum particles and fine powder,α-Al_(2)O_(3) micropowder,Cr_(2)O_(3) micropowder,Guangxi clay and zircon powder were used as the main raw materials.The mass ratio of white fused corundum particles and fine powder was fixed at 85:15,and 0,1%,2%,or 3%(by mass)of zircon fine powder was added to replace the same amount of white fused corundum fine powder.The corundum porous material was prepared by the particle stacking pore-forming method at 1650℃for 3 h.The effect of the zircon addition on the properties and microstructure of porous materials was investigated.The results show that:after adding zircon,the permeability of the porous material increases,the cold and hot strengths increase obviously,and the expansion rate after firing decreases.When the addition of zircon is 2%,the comprehensive performance of the specimen is optimal with the smallest linear change rate and the highest permeability.
文摘Purging plug refractories in China typically contain around 3 mass% of super-fine chromium oxide in the matrix in order to improve the performance of the purging plugs, primarily, slag corrosion and wear resistance. Alternatives to chromium oxide containing refractories have gained interest due to health concerns related to the formation of soluble chromium compounds over long storage periods of refractory wastes. Super-ground reactive alumina can replace chromium oxide in purging plug refractories and this paper discussed the new reactive alumina E-SY 88 in comparison to chromium oxide in a typical purging plug castable. The mixing behaviour, wet castable properties, as well as cured, dried, and fired properties at different temperatures up to 1 600 ℃ were compared. In addition, the hot modulus of rupture, creep behaviour, thermal shock resistance and slag corrosion resistance were tested. The microstructure after slag corrosion was investigated by SEM. The results prove that E-SY 88 is an economically viable technical alternative to chromium oxide in purging plug refractories.
基金Supported by National Natural Science Foundation-funded Project:Study on the Experimental Animal Model of Precocious Puberty with Syndrome of Yin Deficiency and Fire Hyperactivity by Changing the Cycle of Light Exposure(No.81373692)The Constructive Project of Flagship Hospital of Integrated TCM with Western Medicine in Children’s Hospital of Fudan University[No.ZY(2021-2023)-0205-03]the Network Coverage of Coordinated Medical Practice Combined TCM with Western Medicine in Fudan Pediatric Medical Partnerships Union[ZY(2021-2023)-0206-06]。
文摘OBJECTIVE:To elucidate the mechanism of the nourishing Yin and purging fire Chinese herbal mixture(NYPF)in delaying light-induced premature puberty in rats.METHODS:Twenty-one days old female SpragueDawley rats were randomly assigned to normal group(N),long light exposure group(L),NYPF and normal saline group(NS).Rats in the L,NYPF and NS groups were exposed to 16 h:350 lux light/8 h:dark,while rats in the N group were exposed to 12 h:50 lux light/12 h:dark.NYPF and normal saline was administered to the rats in the NYPF group or NS group,respectively,from day 21.Five rats in every group were sacrificed at 9 p.m.on day 28(P28),on the day when rat's vulva opened in the L group(L-VO),on the day when the first estrous interphase occurred in rats of L group(L-E1),and on the day when the second estrous interphase occurred in rats of L group(L-E2),respectively.RESULITS:On day 34,all rats in the L group,80%of rats in the NS group,40%of rats in the N group,and 20%of rats in the NYPF group showed complete opening of the vulva.At P28,m RNA level of hypothalamic kisspeptin(Kiss-1)in the L group was significantly higher than that in the N group(P<0.05).The rats in the L and NS groups had significantly lower hypothalamic argininephenylalanine-amide(RFamide)-related peptide 3(RFRP-3)m RNA levels than those in the N group(P<0.05),whereas RFRP-3 m RNA level was significantly higher in the NYPF group than that in the L group(P<0.05).At L-VO,the ovarian index of the L and NS groups was significantly higher than that of the N group(P<0.05)and estradiol(E2)level of the NYPF group was significantly lower than that of the N and NS groups(P<0.05);hypothalamic Kiss-1 m RNA level in the L and NS groups was significantly higher than that in the N and NYPF groups(P<0.05),whereas hypothalamic RFRP-3 m RNA level in the L,NYPF,and NS groups was significantly lower than that in the N group(P<0.05).At L-E1,E2 level of the L and NS groups was significantly higher than that of the N group(P<0.01),whereas it was significantly lower in the NYPF group
