This paper performs molecular dynamics simulations to investigate the role of the monovalent cations K, Na and the divalent cation Ca on the stability and swelling of montmorillonite. The recently developed CLAYFF for...This paper performs molecular dynamics simulations to investigate the role of the monovalent cations K, Na and the divalent cation Ca on the stability and swelling of montmorillonite. The recently developed CLAYFF force field is used to predict the basal spacing as a function of the water content in the interlayer. The simulations reproduced the swelling pattern of these montmorillonites, suggesting a mechanism of their hydration different （K＋ 〈 Na＋ 〈 Ca2＋） from that of K＋-, Na＋-, and Ca2＋-montmorillonites. In particular, these results indicate that the valence of the cations has the larger impact on the behaviour of clay water systems. It also finds that the differences in size and hydration energy of K＋, Na＋ and Ca2＋ ions have strong implications for the structure of interlayer. This leads to the differences in the layer spacings of the simulated K＋-, Na＋-, and Ca2＋-montmorillonites. Furthermore, these simulations show that the K cations interact strongly with the clay sheets for the dehydrated clay sheets, but for the hydrated clays the Ca cations interact clearly strongly with the clay sheets.展开更多
High mobility group A2（HMGA2） protein is a small nonhistone chromosomal protein that can modulate transcription of an ample number of genes.Many previous studies demonstrate that up-regulation of HMGA2 expression oc...High mobility group A2（HMGA2） protein is a small nonhistone chromosomal protein that can modulate transcription of an ample number of genes.Many previous studies demonstrate that up-regulation of HMGA2 expression occurrs in many kinds of cancers including colorectal cancer,suggesting that HMGA2 might play a critical role in the progression of various tumors.However,the exact role of HMGA2 in colorectal cancer has not been determined.To verify the essential role of HMGA2 in the growth and invasiveness of colorectal cancer,HMGA2 expression was down-regulated by RNA interference（RNAi） in SW480 cells.We observed that the knockdown of HMGA2 led to the significant inhibition of proliferation and invasion of SW480 cells in vitro.These results suggest that HMGA2 might play a crucial role in the progression of colorectal cancer,and be a potential therapeutic target for human colorectal cancer.展开更多
Classical molecular dynamics simulations are used to investigate the fission gas Xe behavior in a U-Mo alloy fuel matrix. The embedded atom method potential proposed by Smirnova et al. is used to describe the U-Mo-Xe ...Classical molecular dynamics simulations are used to investigate the fission gas Xe behavior in a U-Mo alloy fuel matrix. The embedded atom method potential proposed by Smirnova et al. is used to describe the U-Mo-Xe system. The results show that the initial configuration of interstitial Xe atoms in U-Mo alloys is very instable and has a strong tendency to get together and to form a Xe bubble by ejecting the adjacent U atoms and Mo atoms from their former normal lattice sites. The pressure in Xe bubbles is initially quite high and then drops with increasing Xe concentration obviously. The matrix swelling of U-Mo alloys associated with the Xe bubble growth follows approximately a linear relationship with the ratio of Xe to U at low Xe concentration while the rate of swelling increases rapidly at high Xe concentration. The simulation results are in good agreement with the experimental data. The recovery of the damaged structure in the U-Mo alloys matrix is also investigated. It is shown that a damaged structure cannot be recovered completely after a system is relaxed for a long time while still having lots of defects.展开更多
The effect and mechanism of phenylacetic acid on the proliferation of pancreatic carcinoma cells were investigated in cultured pancreatic carcinoma BXPC-3 cells by means of 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenylt...The effect and mechanism of phenylacetic acid on the proliferation of pancreatic carcinoma cells were investigated in cultured pancreatic carcinoma BXPC-3 cells by means of 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide assay and flow cytometry assay.The results show that the treatment of pancreatic carcinoma cells with phenylacetic acid significantly inhibited the cell proliferation in time-dependent and dose-dependent manners.The proliferation of BXPC-3 cells was inhibited at the stage of S phase,the cells at the end stage of S phase were accumulated abundantly,and thus DNA synthesis could not be accomplished entirely.In addition,the expression of adenosine deaminases acting on RNA（ADARs） mRNA in BXPC-3 cells and pancreatic carcinoma specimen were detected by RT-PCR.Having been treated with phenylacetic acid,ADAR2 mRNA in BXPC-3 cells was significantly decreased,the differences were of statistical significance（P0.01）.Taken together,these results suggest that phenylacetic acid may likely regulate the proliferation of pancreatic carcinoma cells through the regulation of ADAR2 mRNA expression.展开更多
基金Project supported by the Key Laboratory of Mountain Hazards and Earth Surface Processes, the Chinese Academy of Sciences
文摘This paper performs molecular dynamics simulations to investigate the role of the monovalent cations K, Na and the divalent cation Ca on the stability and swelling of montmorillonite. The recently developed CLAYFF force field is used to predict the basal spacing as a function of the water content in the interlayer. The simulations reproduced the swelling pattern of these montmorillonites, suggesting a mechanism of their hydration different （K＋ 〈 Na＋ 〈 Ca2＋） from that of K＋-, Na＋-, and Ca2＋-montmorillonites. In particular, these results indicate that the valence of the cations has the larger impact on the behaviour of clay water systems. It also finds that the differences in size and hydration energy of K＋, Na＋ and Ca2＋ ions have strong implications for the structure of interlayer. This leads to the differences in the layer spacings of the simulated K＋-, Na＋-, and Ca2＋-montmorillonites. Furthermore, these simulations show that the K cations interact strongly with the clay sheets for the dehydrated clay sheets, but for the hydrated clays the Ca cations interact clearly strongly with the clay sheets.
文摘High mobility group A2（HMGA2） protein is a small nonhistone chromosomal protein that can modulate transcription of an ample number of genes.Many previous studies demonstrate that up-regulation of HMGA2 expression occurrs in many kinds of cancers including colorectal cancer,suggesting that HMGA2 might play a critical role in the progression of various tumors.However,the exact role of HMGA2 in colorectal cancer has not been determined.To verify the essential role of HMGA2 in the growth and invasiveness of colorectal cancer,HMGA2 expression was down-regulated by RNA interference（RNAi） in SW480 cells.We observed that the knockdown of HMGA2 led to the significant inhibition of proliferation and invasion of SW480 cells in vitro.These results suggest that HMGA2 might play a crucial role in the progression of colorectal cancer,and be a potential therapeutic target for human colorectal cancer.
基金Supported by the National Natural Science Foundation of China under Grant Nos 91226203 and 11205146.
文摘Classical molecular dynamics simulations are used to investigate the fission gas Xe behavior in a U-Mo alloy fuel matrix. The embedded atom method potential proposed by Smirnova et al. is used to describe the U-Mo-Xe system. The results show that the initial configuration of interstitial Xe atoms in U-Mo alloys is very instable and has a strong tendency to get together and to form a Xe bubble by ejecting the adjacent U atoms and Mo atoms from their former normal lattice sites. The pressure in Xe bubbles is initially quite high and then drops with increasing Xe concentration obviously. The matrix swelling of U-Mo alloys associated with the Xe bubble growth follows approximately a linear relationship with the ratio of Xe to U at low Xe concentration while the rate of swelling increases rapidly at high Xe concentration. The simulation results are in good agreement with the experimental data. The recovery of the damaged structure in the U-Mo alloys matrix is also investigated. It is shown that a damaged structure cannot be recovered completely after a system is relaxed for a long time while still having lots of defects.
基金Supported by the National Natural Science Foundation of China(Nos.30801354 and 30970791)the Jilin Provincial Science & Technology Department,China(No.20080154)
文摘The effect and mechanism of phenylacetic acid on the proliferation of pancreatic carcinoma cells were investigated in cultured pancreatic carcinoma BXPC-3 cells by means of 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide assay and flow cytometry assay.The results show that the treatment of pancreatic carcinoma cells with phenylacetic acid significantly inhibited the cell proliferation in time-dependent and dose-dependent manners.The proliferation of BXPC-3 cells was inhibited at the stage of S phase,the cells at the end stage of S phase were accumulated abundantly,and thus DNA synthesis could not be accomplished entirely.In addition,the expression of adenosine deaminases acting on RNA（ADARs） mRNA in BXPC-3 cells and pancreatic carcinoma specimen were detected by RT-PCR.Having been treated with phenylacetic acid,ADAR2 mRNA in BXPC-3 cells was significantly decreased,the differences were of statistical significance（P0.01）.Taken together,these results suggest that phenylacetic acid may likely regulate the proliferation of pancreatic carcinoma cells through the regulation of ADAR2 mRNA expression.
