Carbothermic reduction alumina in vacuum was conducted, and the products were analysed by means of XRD and gas chromatography. Thermodynamic analysis shows that in vacuum the initial carbothermic reduction reaction te...Carbothermic reduction alumina in vacuum was conducted, and the products were analysed by means of XRD and gas chromatography. Thermodynamic analysis shows that in vacuum the initial carbothermic reduction reaction temperature reduces compared with that under normal pressure, and the preferential order of products is Al404C, Al4C3, Al2OC, Al20 and A1. Experiment results show that the carbothermic reduction products of alumina are A1404C and A14C3, and neither A12OC, Al20 or Al was found. During the carbothermic reduction process, the reaction rate of Al203 and carbon decreases gradually with increasing time. Meanwhile, lower system pressure or higher temperature is beneficial to the carbothermic reduction of alumina process. A1404C is firstly formed in the carbothermic reaction, and then A14C3 is formed in lower system pressure or at higher temperature.展开更多
Regarding the complexity and inconsistency of results in existing evaluation methods of mine cooling system, this paper clarifies the advantages, disadvantages and application of various mine cooling sys- tems through...Regarding the complexity and inconsistency of results in existing evaluation methods of mine cooling system, this paper clarifies the advantages, disadvantages and application of various mine cooling sys- tems through principle analysis, and divides all the cooling systems into air-cooling, ice-cooling and water-cooling according to the transportation of cold energy. On this basis, the paper proposes a simple and efficient evaluation method for mine cooling system. The first index of this method is the air temper- ature at point C which is 15 m away from the return wind corner at working face. A cooling system will be judged ineligible if the air temperature at point C is above 30 ℃ during operation, because in this case, the combustible gases in coal will sharply overflow, inducing gas incidents. Based on the preliminary judg- ment of the first index, another two evaluation indexes are proposed based on the cooling ability and dehumidification of an airflow volume of 1000 m3/min at point C to evaluate the investment and opera- tion cost of mine cooling system. This evaluation method has already been successfully applied in the cooling system design of Zhangshuanglou coal mine.展开更多
Pyrolysis of polytrimethylene terephthalate(PTT) fiber has been investigated by pyrolysis gas chromatography-mass spectroscopy in the temperature range from 400℃ to 750℃ in order to observe the possible effect of th...Pyrolysis of polytrimethylene terephthalate(PTT) fiber has been investigated by pyrolysis gas chromatography-mass spectroscopy in the temperature range from 400℃ to 750℃ in order to observe the possible effect of the temperature on its composition of pyrolysates.At 400℃,pyrolysis of molecular chain could occur,only 13 pyrolysates could be identified.The trimethylene moieties bound to the macromolecular core by ester bonds are cleaved at around 400℃.At 550℃-750℃,pyrolysis of molecular chain could completely take place,46 pyrolysates could be found.As the temperature increases,the compositions of pyrolysate are distinctly increased.Several compounds,especially benzoic acid,monopropenyl-p-phthalate,2-propenyl benzoate,di-2-propenyl ester,1,4-benzenedicarboxylic acid,benzene,1,5-hexadiene,biphenyl and 1,3-propanediol dibenzoate could be formed.The thermal degradation mechanism,which is determined by structure and amount of the thermal decomposition products,are described.During pyrolysis of polytrimethylene terephthalate,polymeric chain scissions take place a peeling reaction as a successive removal of the dimer units from the polymeric chain.The chain scissions are followed by the elimination reaction,linkage action and secondary reactions,which bring about a variety fragment.展开更多
Accompanied by global climate change, the annual mean air temperature has experienced a strongly increasing trend in the western China, especially in Xinjiang. The Global Climate Model （GCM） provides an efficient an...Accompanied by global climate change, the annual mean air temperature has experienced a strongly increasing trend in the western China, especially in Xinjiang. The Global Climate Model （GCM） provides an efficient and direct method to assess the process of global climate change and project future climate driven by various factors, especially human activity. Since GCMs＇ low spatial resolution cannot capture the characteristics of local climate change due to the land surface＇s complexity, downscaling methods, including Regional Climate Model （RCM）, Bias Correction method and Statistical Method, are proposed to process raw data from GCMs for local climate change assessment. This study applied the delta method, one of Bias Correction methods, to make horizonta! resolution of 24 GCMs models＇ monthly outputs into 0.5~C for analyzing Xinjiang＇s future climate pattern under three IPCC SRES. A comparison between the results from downscaled dada and raw data from GCMs shows that downscaling methods can improve local climate changing feature in complex land surface and topography and to reduce the uncertainty of climate data generated from GCMs in Xinjiang. The results showed that scenarios A1B, A2 and B1 generated similar patterns and trends in annual mean air temperature and annual precipitation in the early 21st century with fluctuations in the middle of the 21st century. The annual mean air temperature will reach 10℃ 11.1℃ and 8.5℃ in A1B, A2 and B1 by the end of the 2Pt century, respectively, while the annual precipitation during the projection period will experience an increasing trend with a little fluctuation. During 2020 and 2070, the annual temperature in A1B scenario is greater than the other scenarios on regional average. The annual precipitation in the A1B scenario is also greater than other scenarios during 2020 and 2040 on regional average. However, there exists a large uncertainty within different SRES with an range of 6℃ in annual temperature and about 200 mm in annual precipitation. Regionally, annual temperature increases less in the middle Tianshan Mountains, Yili River Basin, the Southern Tianshan Mountains, and downstream of Tarim River than in the Junggar Basin, Pamirs and the northern slope of Kunlun Mountains by the late 21st century. In the western portion of southern Xinjiang, the annual precipitation shows a slightly decreasing trend, but a significant increasing trend was found in eastern Changji, Turpan, Hami and northern Kunlun-Altun Mountains.展开更多
Objective: To study the changes of partial pressure of brain tissue oxygen (PbtO 2) and brain temperature in acute phase of severe head injury during mild hypothermia therapy and the clinical significance. Methods: On...Objective: To study the changes of partial pressure of brain tissue oxygen (PbtO 2) and brain temperature in acute phase of severe head injury during mild hypothermia therapy and the clinical significance. Methods: One hundred and sixteen patients with severe head injury were selected and divided into a mild hypothermia group (n=58), and a control group (n=58) according to odd and even numbers of hospitalization. While mild hypothermia therapy was performed PbtO 2 and brain temperature were monitored for 1 7 days (mean=86 hours), simultaneously, the intracranial pressure, rectum temperature, cerebral perfusion pressure, PaO 2 and PaCO 2 were also monitored. The patients were followed up for 6 months and the prognosis was evaluated with GOS (Glasgow outcome scale). Results: The mean value of PbtO 2 within 24 hour monitoring in the 116 patients was 13.7 mm Hg ± 4.94 mm Hg , lower than the normal value (16 mm Hg ± 40 mm Hg ) The time of PbtO 2 recovering to the normal value in the mild hypothermia group was shortened by 10± 4.15 hours compared with the control group (P< 0.05 ). The survival rate of the mild hypothermia group was 60.43 %, higher than that of the control group ( 46.55 %). After the recovery of the brain temperature, PbtO 2 increased with the rise of the brain temperature. Conclusions: Mild hypothermia can improve the survival rate of severe head injury. The technique of monitoring PbtO 2 and the brain temperature is safe and reliable, and has important clinical significance in judging disease condition and instructing clinical therapy.展开更多
基金Project(U0837604) supported by the Natural Science Foundation of Yunnan Province,ChinaProject(Jinchuan 201114) supported by the Pre Research Foundation of Jinchuan Group Ltd.,ChinaProject(2011148) supported by the Analysis and Testing Funds of Kunming University of Science and Technology,China
文摘Carbothermic reduction alumina in vacuum was conducted, and the products were analysed by means of XRD and gas chromatography. Thermodynamic analysis shows that in vacuum the initial carbothermic reduction reaction temperature reduces compared with that under normal pressure, and the preferential order of products is Al404C, Al4C3, Al2OC, Al20 and A1. Experiment results show that the carbothermic reduction products of alumina are A1404C and A14C3, and neither A12OC, Al20 or Al was found. During the carbothermic reduction process, the reaction rate of Al203 and carbon decreases gradually with increasing time. Meanwhile, lower system pressure or higher temperature is beneficial to the carbothermic reduction of alumina process. A1404C is firstly formed in the carbothermic reaction, and then A14C3 is formed in lower system pressure or at higher temperature.
基金supported by the key project of National Natural Science Foundation ‘‘Deep Heat Governance and Utilization’’ (Nos.51134005 and 41402273)the Doctoral Fund of Ministry of Education (No. 20130023110021)
文摘Regarding the complexity and inconsistency of results in existing evaluation methods of mine cooling system, this paper clarifies the advantages, disadvantages and application of various mine cooling sys- tems through principle analysis, and divides all the cooling systems into air-cooling, ice-cooling and water-cooling according to the transportation of cold energy. On this basis, the paper proposes a simple and efficient evaluation method for mine cooling system. The first index of this method is the air temper- ature at point C which is 15 m away from the return wind corner at working face. A cooling system will be judged ineligible if the air temperature at point C is above 30 ℃ during operation, because in this case, the combustible gases in coal will sharply overflow, inducing gas incidents. Based on the preliminary judg- ment of the first index, another two evaluation indexes are proposed based on the cooling ability and dehumidification of an airflow volume of 1000 m3/min at point C to evaluate the investment and opera- tion cost of mine cooling system. This evaluation method has already been successfully applied in the cooling system design of Zhangshuanglou coal mine.
文摘Pyrolysis of polytrimethylene terephthalate(PTT) fiber has been investigated by pyrolysis gas chromatography-mass spectroscopy in the temperature range from 400℃ to 750℃ in order to observe the possible effect of the temperature on its composition of pyrolysates.At 400℃,pyrolysis of molecular chain could occur,only 13 pyrolysates could be identified.The trimethylene moieties bound to the macromolecular core by ester bonds are cleaved at around 400℃.At 550℃-750℃,pyrolysis of molecular chain could completely take place,46 pyrolysates could be found.As the temperature increases,the compositions of pyrolysate are distinctly increased.Several compounds,especially benzoic acid,monopropenyl-p-phthalate,2-propenyl benzoate,di-2-propenyl ester,1,4-benzenedicarboxylic acid,benzene,1,5-hexadiene,biphenyl and 1,3-propanediol dibenzoate could be formed.The thermal degradation mechanism,which is determined by structure and amount of the thermal decomposition products,are described.During pyrolysis of polytrimethylene terephthalate,polymeric chain scissions take place a peeling reaction as a successive removal of the dimer units from the polymeric chain.The chain scissions are followed by the elimination reaction,linkage action and secondary reactions,which bring about a variety fragment.
基金supported by the Natural Sciences Foundation of China (No. 40871027)the Project of State Key Basic R & D Program of China (973 Program, 2012CB956204)supported by the U.S. Department of Energy Office of Science Funding
文摘Accompanied by global climate change, the annual mean air temperature has experienced a strongly increasing trend in the western China, especially in Xinjiang. The Global Climate Model （GCM） provides an efficient and direct method to assess the process of global climate change and project future climate driven by various factors, especially human activity. Since GCMs＇ low spatial resolution cannot capture the characteristics of local climate change due to the land surface＇s complexity, downscaling methods, including Regional Climate Model （RCM）, Bias Correction method and Statistical Method, are proposed to process raw data from GCMs for local climate change assessment. This study applied the delta method, one of Bias Correction methods, to make horizonta! resolution of 24 GCMs models＇ monthly outputs into 0.5~C for analyzing Xinjiang＇s future climate pattern under three IPCC SRES. A comparison between the results from downscaled dada and raw data from GCMs shows that downscaling methods can improve local climate changing feature in complex land surface and topography and to reduce the uncertainty of climate data generated from GCMs in Xinjiang. The results showed that scenarios A1B, A2 and B1 generated similar patterns and trends in annual mean air temperature and annual precipitation in the early 21st century with fluctuations in the middle of the 21st century. The annual mean air temperature will reach 10℃ 11.1℃ and 8.5℃ in A1B, A2 and B1 by the end of the 2Pt century, respectively, while the annual precipitation during the projection period will experience an increasing trend with a little fluctuation. During 2020 and 2070, the annual temperature in A1B scenario is greater than the other scenarios on regional average. The annual precipitation in the A1B scenario is also greater than other scenarios during 2020 and 2040 on regional average. However, there exists a large uncertainty within different SRES with an range of 6℃ in annual temperature and about 200 mm in annual precipitation. Regionally, annual temperature increases less in the middle Tianshan Mountains, Yili River Basin, the Southern Tianshan Mountains, and downstream of Tarim River than in the Junggar Basin, Pamirs and the northern slope of Kunlun Mountains by the late 21st century. In the western portion of southern Xinjiang, the annual precipitation shows a slightly decreasing trend, but a significant increasing trend was found in eastern Changji, Turpan, Hami and northern Kunlun-Altun Mountains.
文摘Objective: To study the changes of partial pressure of brain tissue oxygen (PbtO 2) and brain temperature in acute phase of severe head injury during mild hypothermia therapy and the clinical significance. Methods: One hundred and sixteen patients with severe head injury were selected and divided into a mild hypothermia group (n=58), and a control group (n=58) according to odd and even numbers of hospitalization. While mild hypothermia therapy was performed PbtO 2 and brain temperature were monitored for 1 7 days (mean=86 hours), simultaneously, the intracranial pressure, rectum temperature, cerebral perfusion pressure, PaO 2 and PaCO 2 were also monitored. The patients were followed up for 6 months and the prognosis was evaluated with GOS (Glasgow outcome scale). Results: The mean value of PbtO 2 within 24 hour monitoring in the 116 patients was 13.7 mm Hg ± 4.94 mm Hg , lower than the normal value (16 mm Hg ± 40 mm Hg ) The time of PbtO 2 recovering to the normal value in the mild hypothermia group was shortened by 10± 4.15 hours compared with the control group (P< 0.05 ). The survival rate of the mild hypothermia group was 60.43 %, higher than that of the control group ( 46.55 %). After the recovery of the brain temperature, PbtO 2 increased with the rise of the brain temperature. Conclusions: Mild hypothermia can improve the survival rate of severe head injury. The technique of monitoring PbtO 2 and the brain temperature is safe and reliable, and has important clinical significance in judging disease condition and instructing clinical therapy.
