Understanding the evolution of irradiation-induced defects is of critical importance for the performance estimation of nuclear materials under irradiation.Hereby,we systematically investigate the influence of He on th...Understanding the evolution of irradiation-induced defects is of critical importance for the performance estimation of nuclear materials under irradiation.Hereby,we systematically investigate the influence of He on the evolution of Frenkel pairs and collision cascades in tungsten(W)via using the object kinetic Monte Carlo(OKMC)method.Our findings suggest that the presence of He has significant effect on the evolution of irradiation-induced defects.On the one hand,the presence of He can facilitate the recombination of vacancies and self-interstitial atoms(SIAs)in W.This can be attributed to the formation of immobile He-SIA complexes,which increases the annihilation probability of vacancies and SIAs.On the other hand,due to the high stability and low mobility of He-vacancy complexes,the growth of large vacancy clusters in W is kinetically suppressed by He addition.Specially,in comparison with the injection of collision cascades and He in sequential way at 1223 K,the average sizes of surviving vacancy clusters in W via simultaneous way are smaller,which is in good agreement with previous experimental observations.These results advocate that the impurity with low concentration has significant effect on the evolution of irradiation-induced defects in materials,and contributes to our understanding of W performance under irradiation.展开更多
Long-term glucocorticoid use may result in sustained suppression of one or more secreted components from the hypothalamo-pituitary-adrenal axis, and often results in apoptosis. Yougui Pill（YGP）, a 10-component tradi...Long-term glucocorticoid use may result in sustained suppression of one or more secreted components from the hypothalamo-pituitary-adrenal axis, and often results in apoptosis. Yougui Pill（YGP）, a 10-component traditional Chinese herbal medicine, has been shown to be clinically effective for glucocorticoid-induced suppression of the hypothalamo-pituitary-adrenal axis. However, the pharmacological and molecular mechanisms remain unclear. We hypothesized that YGP would exert an anti-apoptosis effect on dexamethasone-treated anterior pituitary cells. In vivo experiments showed that YGP significantly reduced the number of apoptotic cells, down-regulated m RNA expression of cytochrome c, caspase-3, and caspase-9, and up-regulated m RNA expression of Bcl-2. These findings suggest that YGP reduced glucocorticoid-induced apoptosis in rat anterior pituitary cells by regulating the mitochondria-mediated apoptosis pathway.展开更多
Energetics of helium-nanocavities interactions are crucial for unveiling underlying mechanisms of nanocavity evolution in nuclear materials.Nevertheless,it becomes intractable and even not feasible to obtain these ene...Energetics of helium-nanocavities interactions are crucial for unveiling underlying mechanisms of nanocavity evolution in nuclear materials.Nevertheless,it becomes intractable and even not feasible to obtain these energetics via atomic simulations with increasing nanocavity size and increasing helium content in nanocavities.Herein,a universal scaling law of helium-induced interaction energies in nanocavities in metal systems is proposed based on electrophobic interaction of helium.Based on this scaling law and ab-initio calculations,a predictive method for binding energies of helium and displacement defects to nanocavities of arbitrary sizes and with different helium/vacancy ratios is established for BCC iron as a representative and validated by atomic simulations.This predictive method reveals that the critical helium/vacancy ratio for helium-enhanced vacancy binding to nanocavities in-creases with increasing nanocavity size,and the helium/vacancy ratio giving the highest stability of nanocavities is about 1.6.The Ostwald ripening of nanocavities is delayed by helium to higher temper-atures due to reduced vacancy de-trapping rates from nanocavities.The proposed scaling law can be generalized to many metal systems studied in the nuclear materials community.Being readily coupled into mesoscale models of irradiation damages,this predictive method facilitates clarifying helium role in cavity swelling of metallic nuclear materials.展开更多
Objective To study the chemical constituents from the roots of Rubus parvifolius. Methods The chemical constituents were extracted and purified by silica gel column chromatography. NMR spectra were used for structural...Objective To study the chemical constituents from the roots of Rubus parvifolius. Methods The chemical constituents were extracted and purified by silica gel column chromatography. NMR spectra were used for structural identification. Results Phytochemical study on the roots of R. parvifolius led to the isolation of one ceramide （1）, two anthraquinones （2 and 3）, four triterpenoids （4-7）, two flavonoids （8 and 9）, one fatty acid ester （10）, and two sterols （1 1 and 12）. Conclusion Compound 1 is isolated from the plants of family Rosaceae for the first time, and compounds 2-5 are isolated from genus Rubus for the first time. Though R. parvifolius shares the same major chemical types （triterpenoid, flavonoid, and anthraquinone） with those of R. alceaefolius, a substituent of R. parvifolius, their individual constituents are different. In addition, R. parvifolius contains ceramide （1） with high concentration, while caffeoylquinic acid reported in R. alceaefolius has not been found in R. parvifolius. Furthermore, the results from our phytochemical study are consistent with the DNA phylogenic relationship between R. parvifolius and R. alceaefolius （two separated subgenera）, suggesting that the substitution of the former species with the latter one in folk medicine might not be suitable.展开更多
We investigated the influence of hydrogen(H)on the stability and mobility of small vacancy clusters in tungsten(W)using the first-principles calculations.It is found that the presence of H not only increases the bindi...We investigated the influence of hydrogen(H)on the stability and mobility of small vacancy clusters in tungsten(W)using the first-principles calculations.It is found that the presence of H not only increases the binding energy of small vacancy clusters but also changes their most favorable configurations,owing to the strong attractive interaction between H and vacancies in W.Specifically,the binding energy of di-vacancy changes from negative to positive when the H atoms are introduced.These results suggest that the H addition can significantly promote the stability of small vacancy clusters in W.More importantly,although the migration energy barriers of H-vacancy(H-V)complexes are slightly higher than that of pure vacancy clusters,the activation energy required for complexes migration is always lower than that for dissociation.Therefore,contrary to the conventional view,the collaborative motion of H and small vacancy clusters is possible,because of the low migration energy barriers.Based on the energetic results obtained by first-principles calculations,the mean lifetime and mean diffusion distance of small H-V complexes at different temperatures are examined by the object kinetic Monte Carlo simulations.The small H-V complexes are found to be stable and mobile at moderate temperature,and thus may affect the co-evolution of H and vacancies.These results shed light on the important role of H on the vacancy behaviors and provide a good reference for understanding the defects evolution in W.展开更多
We have systemically investigated the synergistic evolution of rhenium(Re)and irradiation defects in tungsten(W)-Re alloys under different temperatures and irradiation doses using object Kinetic Monte Carlo method.Our...We have systemically investigated the synergistic evolution of rhenium(Re)and irradiation defects in tungsten(W)-Re alloys under different temperatures and irradiation doses using object Kinetic Monte Carlo method.Our results revealed the underlying mechanism for the transition of Re effect on W from beneficial to harmful during the Re-defects evolution with the increase of irradiation dose,in which tem-perature always plays a critical role.On the one hand,Re will significantly promote the defect annihila-tion at low irradiation doses and high temperatures,thereby effectively reducing their sizes and number densities.This is due to the formation of stable Re-SIAs complexes that can be eliminated by the mobile vacancy-type defects,whereas the transition of the migration pattern of SIAs only plays a weak role in the defect recombination in W-Re system.On the other hand,with the increase of irradiation dose,Re will aggregate to form Re-rich clusters or even precipitates.Interestingly,the formation mechanism of Re-rich clusters is also dependent on temperature.At low temperatures,the interstitial-mediated mech-anism plays a crucial role in the Re-rich cluster formation,while at high temperatures,both SIA-type and vacancy-type defects will act as the transport carriers of Re to promote their clustering.Accordingly,the critical conditions for the transition of Re from beneficial to harmful and the formation of Re-rich clusters at different tem peratures and irradiation doses are given with the help of the phase diagram.Our work presents the temperature dependence of the synergy of Re and irradiation defects in W-Re in fusion-relevant environment,which provides a good reference for the development of radiation-resistant materials and the prediction of W performance in fusion reactors.展开更多
基金Project supported by the Science Challenge Project(Grant No.TZ2018002)the National Natural Science Foundation of China(Grant No.11905135)the National MCF Energy R&D Program of China(Grant No.2018YFE0308103).
文摘Understanding the evolution of irradiation-induced defects is of critical importance for the performance estimation of nuclear materials under irradiation.Hereby,we systematically investigate the influence of He on the evolution of Frenkel pairs and collision cascades in tungsten(W)via using the object kinetic Monte Carlo(OKMC)method.Our findings suggest that the presence of He has significant effect on the evolution of irradiation-induced defects.On the one hand,the presence of He can facilitate the recombination of vacancies and self-interstitial atoms(SIAs)in W.This can be attributed to the formation of immobile He-SIA complexes,which increases the annihilation probability of vacancies and SIAs.On the other hand,due to the high stability and low mobility of He-vacancy complexes,the growth of large vacancy clusters in W is kinetically suppressed by He addition.Specially,in comparison with the injection of collision cascades and He in sequential way at 1223 K,the average sizes of surviving vacancy clusters in W via simultaneous way are smaller,which is in good agreement with previous experimental observations.These results advocate that the impurity with low concentration has significant effect on the evolution of irradiation-induced defects in materials,and contributes to our understanding of W performance under irradiation.
基金supported by the National Natural Science Foundation of China,No.30471576,and 30872277a grant from the Innovative Research Program in Universities of the Ministry of Education of China,No.IRT0760
文摘Long-term glucocorticoid use may result in sustained suppression of one or more secreted components from the hypothalamo-pituitary-adrenal axis, and often results in apoptosis. Yougui Pill（YGP）, a 10-component traditional Chinese herbal medicine, has been shown to be clinically effective for glucocorticoid-induced suppression of the hypothalamo-pituitary-adrenal axis. However, the pharmacological and molecular mechanisms remain unclear. We hypothesized that YGP would exert an anti-apoptosis effect on dexamethasone-treated anterior pituitary cells. In vivo experiments showed that YGP significantly reduced the number of apoptotic cells, down-regulated m RNA expression of cytochrome c, caspase-3, and caspase-9, and up-regulated m RNA expression of Bcl-2. These findings suggest that YGP reduced glucocorticoid-induced apoptosis in rat anterior pituitary cells by regulating the mitochondria-mediated apoptosis pathway.
基金supported by National MCF Energy R&D Program (2022YFE03110000)National Natural Science Foundation of China(Grant No.12192280,11935004,12275009).
文摘Energetics of helium-nanocavities interactions are crucial for unveiling underlying mechanisms of nanocavity evolution in nuclear materials.Nevertheless,it becomes intractable and even not feasible to obtain these energetics via atomic simulations with increasing nanocavity size and increasing helium content in nanocavities.Herein,a universal scaling law of helium-induced interaction energies in nanocavities in metal systems is proposed based on electrophobic interaction of helium.Based on this scaling law and ab-initio calculations,a predictive method for binding energies of helium and displacement defects to nanocavities of arbitrary sizes and with different helium/vacancy ratios is established for BCC iron as a representative and validated by atomic simulations.This predictive method reveals that the critical helium/vacancy ratio for helium-enhanced vacancy binding to nanocavities in-creases with increasing nanocavity size,and the helium/vacancy ratio giving the highest stability of nanocavities is about 1.6.The Ostwald ripening of nanocavities is delayed by helium to higher temper-atures due to reduced vacancy de-trapping rates from nanocavities.The proposed scaling law can be generalized to many metal systems studied in the nuclear materials community.Being readily coupled into mesoscale models of irradiation damages,this predictive method facilitates clarifying helium role in cavity swelling of metallic nuclear materials.
基金Administration of Traditional Chinese Medicine of Guangdong Province,China(No.20131078)
文摘Objective To study the chemical constituents from the roots of Rubus parvifolius. Methods The chemical constituents were extracted and purified by silica gel column chromatography. NMR spectra were used for structural identification. Results Phytochemical study on the roots of R. parvifolius led to the isolation of one ceramide （1）, two anthraquinones （2 and 3）, four triterpenoids （4-7）, two flavonoids （8 and 9）, one fatty acid ester （10）, and two sterols （1 1 and 12）. Conclusion Compound 1 is isolated from the plants of family Rosaceae for the first time, and compounds 2-5 are isolated from genus Rubus for the first time. Though R. parvifolius shares the same major chemical types （triterpenoid, flavonoid, and anthraquinone） with those of R. alceaefolius, a substituent of R. parvifolius, their individual constituents are different. In addition, R. parvifolius contains ceramide （1） with high concentration, while caffeoylquinic acid reported in R. alceaefolius has not been found in R. parvifolius. Furthermore, the results from our phytochemical study are consistent with the DNA phylogenic relationship between R. parvifolius and R. alceaefolius （two separated subgenera）, suggesting that the substitution of the former species with the latter one in folk medicine might not be suitable.
基金This work was financially supported by the National Natural Science Foundation of China with Grant Nos.11905135 and 12075022the Major Program of National Natural Science Foundation of China with Grant No.12192281the National MCF Energy R&D Program with Grant No.2018YFE0308103.
文摘We investigated the influence of hydrogen(H)on the stability and mobility of small vacancy clusters in tungsten(W)using the first-principles calculations.It is found that the presence of H not only increases the binding energy of small vacancy clusters but also changes their most favorable configurations,owing to the strong attractive interaction between H and vacancies in W.Specifically,the binding energy of di-vacancy changes from negative to positive when the H atoms are introduced.These results suggest that the H addition can significantly promote the stability of small vacancy clusters in W.More importantly,although the migration energy barriers of H-vacancy(H-V)complexes are slightly higher than that of pure vacancy clusters,the activation energy required for complexes migration is always lower than that for dissociation.Therefore,contrary to the conventional view,the collaborative motion of H and small vacancy clusters is possible,because of the low migration energy barriers.Based on the energetic results obtained by first-principles calculations,the mean lifetime and mean diffusion distance of small H-V complexes at different temperatures are examined by the object kinetic Monte Carlo simulations.The small H-V complexes are found to be stable and mobile at moderate temperature,and thus may affect the co-evolution of H and vacancies.These results shed light on the important role of H on the vacancy behaviors and provide a good reference for understanding the defects evolution in W.
基金This work is financially supported by the National Natu-ral Science Foundation of China(Nos.11905135,12075022 and 12192281)the National MCF Energy R&D Program(No.2018YFE0308103).
文摘We have systemically investigated the synergistic evolution of rhenium(Re)and irradiation defects in tungsten(W)-Re alloys under different temperatures and irradiation doses using object Kinetic Monte Carlo method.Our results revealed the underlying mechanism for the transition of Re effect on W from beneficial to harmful during the Re-defects evolution with the increase of irradiation dose,in which tem-perature always plays a critical role.On the one hand,Re will significantly promote the defect annihila-tion at low irradiation doses and high temperatures,thereby effectively reducing their sizes and number densities.This is due to the formation of stable Re-SIAs complexes that can be eliminated by the mobile vacancy-type defects,whereas the transition of the migration pattern of SIAs only plays a weak role in the defect recombination in W-Re system.On the other hand,with the increase of irradiation dose,Re will aggregate to form Re-rich clusters or even precipitates.Interestingly,the formation mechanism of Re-rich clusters is also dependent on temperature.At low temperatures,the interstitial-mediated mech-anism plays a crucial role in the Re-rich cluster formation,while at high temperatures,both SIA-type and vacancy-type defects will act as the transport carriers of Re to promote their clustering.Accordingly,the critical conditions for the transition of Re from beneficial to harmful and the formation of Re-rich clusters at different tem peratures and irradiation doses are given with the help of the phase diagram.Our work presents the temperature dependence of the synergy of Re and irradiation defects in W-Re in fusion-relevant environment,which provides a good reference for the development of radiation-resistant materials and the prediction of W performance in fusion reactors.
