为了解酸返流量在 Barrett 食管 BE 发病中的作用,对23例(BE)、16例Ⅰ级返流性食管炎、21例Ⅱ和Ⅲ级返流性食管炎进行持续24小时食管内 pH 监测,就24小时 pH<4总百分时间、总返流次数、持续5分钟以上的返流次数及最长的返流时间4项参...为了解酸返流量在 Barrett 食管 BE 发病中的作用,对23例(BE)、16例Ⅰ级返流性食管炎、21例Ⅱ和Ⅲ级返流性食管炎进行持续24小时食管内 pH 监测,就24小时 pH<4总百分时间、总返流次数、持续5分钟以上的返流次数及最长的返流时间4项参数,将 BE 组与其它两组食管炎进行比较。结果显示:Ⅰ级返流性食管炎组与 BE 组相比,4项参数均有显著性差异(P<0.01);而Ⅱ和Ⅲ级返流性食管炎组与 BE 组相比,各参数差异均无显著性(P>0.05)。结论是酸返流量并不是导致胃食管返流发展为 BE 的主要原因。展开更多
The leaching of low-sulfur Ni-Cu matte in acid-oxygen(CuSO4-H2SO4-O2)solution at atmospheric pressure was researched.This matte was obtained from high grade Ni-Cu matte by magnetic separation,which mainly contained Ni...The leaching of low-sulfur Ni-Cu matte in acid-oxygen(CuSO4-H2SO4-O2)solution at atmospheric pressure was researched.This matte was obtained from high grade Ni-Cu matte by magnetic separation,which mainly contained Ni-Cu alloy and a small quantity of sulfides.The effects of temperature,agitation speed,oxygen flow rate,particle size,acid concentration and concentration of copper ion were studied.It is found that the matte particles are leached by shrinking core mechanism and the leaching process is electrochemically controlled.In a temperature range of 30-60℃,the surface reaction is rate-limiting step,with an apparent activation energy of 41.9 kJ/mol.But at higher temperature(70-85℃),the rate process is controlled by diffusion through the product layer,with an apparent activation energy of 7.3 kJ/mol.展开更多
Stomach cancer is still the fourth most common cancer;thus,it remains an important public health burden worldwide,especially in developing countries.The remarkable geographic variations in the rates of stomach cancer ...Stomach cancer is still the fourth most common cancer;thus,it remains an important public health burden worldwide,especially in developing countries.The remarkable geographic variations in the rates of stomach cancer indicate that dietary factors,including a range of food groups to which salt and/or nitrates have been added,may affect stomach cancer risk.In this paper,we review the results from ecologic,case-control and cohort studies on the relationship between salt or salted foods and stomach cancer risk.The majority of ecological studies indicated that the average salt intake in each population was closely correlated with gastric cancer mortality.Most case-control studies showed similar results,indicating a moderate to high increase in risk for the highest level of salt or salted food consumption.The overall results from cohort studies are not totally consistent,but are suggestive of a moderate direct association.Since salt intake has been correlated with Helicobacter pylori(H pylori) infection,it is possible that these two factors may synergize to promote the development of stomach cancer.Additionally,salt may also cause stomach cancer through directly damaging gastric mucus,improving temporary epithelial proliferation and the incidence of endogenous mutations,and inducing hypergastrinemia that leads to eventual parietal cell loss and progression to gastric cancer.Based on the considerable evidence from ecological,case-control and cohort studies worldwide and the mechanistic plausibility,limitation on salt and salted food consumption is a practical strategy for preventing gastric cancer.展开更多
Viscosities of uranium solutions in H2O and 3 mol/L HNO3 medium were measured by Ubbelhode flow vis-cometer in the concentration range of 0.5%3.0% from 10 篊 to 30 篊 at 5 篊 interval. Viscosity data were interpreted ...Viscosities of uranium solutions in H2O and 3 mol/L HNO3 medium were measured by Ubbelhode flow vis-cometer in the concentration range of 0.5%3.0% from 10 篊 to 30 篊 at 5 篊 interval. Viscosity data were interpreted in terms of an empirical equation; h =aoexp(boM+coM2). Values of coefficients ao, bo and co were calculated for all the three systems studied. Flow activation energies and thermodynamic parameters were also evaluated.展开更多
Dimethyl carbonate is an environmentally benign and biodegradable chemical.Based on integration of reactive distillation and pressure-swing distillation technologies,a novel process for synthesis of dimethyl carbonate...Dimethyl carbonate is an environmentally benign and biodegradable chemical.Based on integration of reactive distillation and pressure-swing distillation technologies,a novel process for synthesis of dimethyl carbonate through transesterification with propylene carbonate and methanol has been developed by Huang et al.In this work,the optimization of this process was performed by minimizing the total TAC.The results show that the optimal design flowsheet can save energy consumption by 18.6% with the propylene carbonate conversion of 99.9%.Then,an effective plant-wide control structure for the process was developed.Dynamic simulation results demonstrate that the temperature/flow rate cascade control plus with simple temperature control can keep not only product purity but also the conversion of the reactant at their desired values in the face of the disturbance in reactant feed flow rate and feed composition.展开更多
文摘为了解酸返流量在 Barrett 食管 BE 发病中的作用,对23例(BE)、16例Ⅰ级返流性食管炎、21例Ⅱ和Ⅲ级返流性食管炎进行持续24小时食管内 pH 监测,就24小时 pH<4总百分时间、总返流次数、持续5分钟以上的返流次数及最长的返流时间4项参数,将 BE 组与其它两组食管炎进行比较。结果显示:Ⅰ级返流性食管炎组与 BE 组相比,4项参数均有显著性差异(P<0.01);而Ⅱ和Ⅲ级返流性食管炎组与 BE 组相比,各参数差异均无显著性(P>0.05)。结论是酸返流量并不是导致胃食管返流发展为 BE 的主要原因。
基金Project(50774020) supported by the National Natural Science Foundation of China
文摘The leaching of low-sulfur Ni-Cu matte in acid-oxygen(CuSO4-H2SO4-O2)solution at atmospheric pressure was researched.This matte was obtained from high grade Ni-Cu matte by magnetic separation,which mainly contained Ni-Cu alloy and a small quantity of sulfides.The effects of temperature,agitation speed,oxygen flow rate,particle size,acid concentration and concentration of copper ion were studied.It is found that the matte particles are leached by shrinking core mechanism and the leaching process is electrochemically controlled.In a temperature range of 30-60℃,the surface reaction is rate-limiting step,with an apparent activation energy of 41.9 kJ/mol.But at higher temperature(70-85℃),the rate process is controlled by diffusion through the product layer,with an apparent activation energy of 7.3 kJ/mol.
文摘Stomach cancer is still the fourth most common cancer;thus,it remains an important public health burden worldwide,especially in developing countries.The remarkable geographic variations in the rates of stomach cancer indicate that dietary factors,including a range of food groups to which salt and/or nitrates have been added,may affect stomach cancer risk.In this paper,we review the results from ecologic,case-control and cohort studies on the relationship between salt or salted foods and stomach cancer risk.The majority of ecological studies indicated that the average salt intake in each population was closely correlated with gastric cancer mortality.Most case-control studies showed similar results,indicating a moderate to high increase in risk for the highest level of salt or salted food consumption.The overall results from cohort studies are not totally consistent,but are suggestive of a moderate direct association.Since salt intake has been correlated with Helicobacter pylori(H pylori) infection,it is possible that these two factors may synergize to promote the development of stomach cancer.Additionally,salt may also cause stomach cancer through directly damaging gastric mucus,improving temporary epithelial proliferation and the incidence of endogenous mutations,and inducing hypergastrinemia that leads to eventual parietal cell loss and progression to gastric cancer.Based on the considerable evidence from ecological,case-control and cohort studies worldwide and the mechanistic plausibility,limitation on salt and salted food consumption is a practical strategy for preventing gastric cancer.
文摘Viscosities of uranium solutions in H2O and 3 mol/L HNO3 medium were measured by Ubbelhode flow vis-cometer in the concentration range of 0.5%3.0% from 10 篊 to 30 篊 at 5 篊 interval. Viscosity data were interpreted in terms of an empirical equation; h =aoexp(boM+coM2). Values of coefficients ao, bo and co were calculated for all the three systems studied. Flow activation energies and thermodynamic parameters were also evaluated.
基金Supported by the National Natural Science Foundation of China(21306025,21576053)the International Science&Technology Cooperation Program of China(2013DFR90540)
文摘Dimethyl carbonate is an environmentally benign and biodegradable chemical.Based on integration of reactive distillation and pressure-swing distillation technologies,a novel process for synthesis of dimethyl carbonate through transesterification with propylene carbonate and methanol has been developed by Huang et al.In this work,the optimization of this process was performed by minimizing the total TAC.The results show that the optimal design flowsheet can save energy consumption by 18.6% with the propylene carbonate conversion of 99.9%.Then,an effective plant-wide control structure for the process was developed.Dynamic simulation results demonstrate that the temperature/flow rate cascade control plus with simple temperature control can keep not only product purity but also the conversion of the reactant at their desired values in the face of the disturbance in reactant feed flow rate and feed composition.
