The determination of gas pressure before uncovering coal in cross-cuts and in shafts is one of the important steps in pre- dicting coal and gas outbursts. However, the time spent for testing gas pressure is, at presen...The determination of gas pressure before uncovering coal in cross-cuts and in shafts is one of the important steps in pre- dicting coal and gas outbursts. However, the time spent for testing gas pressure is, at present, very long, seriously affecting the ap- plication of outburst prediction techniques in opening coal seams in cross-cuts and shafts. In order to reduce the time needed in gas pressure tests and to improve the accuracy of tests, we analyzed the process of gas pressure tests and examined the effect of the length of boreholes in coal seams in tests. The result shows that 1) the shorter the borehole, the easier the real pressure value of gas can be obtained and 2) the main factors affecting the time spent in gas pressure tests are the length of the borehole in coal seams, the gas emission time after the borehole has been formed and the quality of the borehole-sealing. The longer the length of the bore- hole, the longer the gas emission time and the larger the pressure-relief circle formed around the borehole, the longer the time needed for pressure tests. By controlling the length of the borehole in a test case in the Huainan mining area, and adopting a quick sealing technique using a sticky liquid method, the sealing quality was clearly improved and the gas emission time as well as the amount of gas discharged greatly decreased. Before the method described, the time required for the gas pressure to increase during the pressure test process, was more than 10 days. With our new method the required time is only 5 hours. In addition, the accuracy of the gas pressure test is greatly improved.展开更多
AIM: To investigate whether differences in the rapidity of a positive result for Helicobacter pylori can save res ources, by comparing two commercially available urease kits. METHODS: One hundred and eighty-five adult...AIM: To investigate whether differences in the rapidity of a positive result for Helicobacter pylori can save res ources, by comparing two commercially available urease kits. METHODS: One hundred and eighty-five adults (130 outpatients, 55 inpatients) undergoing gastroscopy were entered prospectively. Patients were divided into two groups: Group 1 (if they were not on PPIs, antibiotics, H2A, bismuth or sucralfate for up to 14 d prior to the endoscopy) and Group 2 (if they were on, or had been on, any of the above medication in the previous 14 d). At endoscopy two sets of biopsies, taken in random order, were placed in the wells of the Campylobacter-like organism (CLO) test (Kimberly-Clark, Utah, USA) and the Quick test (Biohit Plc, Helsinki, Finland). Five additional gastric biopsies were taken for histology/Giemsa and immunohistochemical study. The two urease test slides were read at 2 min, 30 min, 2 h and 24 h. Sensitivity and specif icity at 24 h were determined. RESULTS: At 24 h, for all patients, there was no difference in sensitivity (100% vs 97.5%), specificity (99.3%), positive (97.5%) and negative predictive values (100% vs 99.3%) between the CLO and Quick tests, respectively. There was a positive result at 30 min in 17/41 (41.5%) CLO tests, and in 28/40 (70%) Quick tests, P = 0.05. Quick test enabled the prescription of eradication therapy before discharge in all 28/40 patients. Only 12 (30%) follow-up appointments were needed. If the CLO test had been used alone, only 17 (41.5%) prescriptions would have been possible prior to discharge and 24 (58%) follow-up appointments would be needed (P = 0.001). Of 2000 gastroscopies performed annually at our unit, a saving of 123 follow-up appointments (total: 8856 Euros or 11 808 USD) would be achieved if we switched to the Quick test. CONCLUSION: Direct comparison of locally available urease test kits is worthwhile, since the appropriate choice results in a significant saving of resources. Local costs and follow-up protocols will determine the magnitude of these savings.展开更多
Durability problem of reinforced concrete for underground structures is a hot issue in the field of structural engineering. For underground structures, the prediction of structural service life and methodology for dur...Durability problem of reinforced concrete for underground structures is a hot issue in the field of structural engineering. For underground structures, the prediction of structural service life and methodology for durability design are needed to estimate structural durability. Taking the case of Xiamen Xiang＇an subsea tunnel as background, which is designed to meet the requirement of lO0-year service life, the influential factors on tunnel lining durability are analyzed. Under the criteria of crack controlling and bearing capacity of linin~ structures, the theoretical service life of Xiamen Xiang＇an subsea tunnel lining is studied. The regulations, which are needed for the diffusion capability of chloride ions in concrete by the relevant diffusion tests, are proposed. After a quick corrosion test, the bearing capacity test on eccentric short columns is implemented to investigate the variation rules in the bearing capacity of models with time. Influence of the corrosion degree of steel bars on the bearing capacity of models is also investigated. Based on the results of model tests, the acceleration ratio between the quick corrosion in laboratory test and the natural corrosion environments is established. Thus, the natural service life of subsea tunnel lining structures can be obtained by means of laboratory tests. Then, the proposed method using this modified model is employed to predict the service life of tunnel lining structures. Finally, the design and construction measures for improving the durability of lining structures of subsea tunnel are introduced. The proposed method in the present study based on a real engineering project is superior to those with only theoretical assumptions, and would be more suitable for similar projects.展开更多
Plant sap analysis has emerged as a key focus in recent agricultural research,aiming to enhance fertilizer management and improve crop nutritional assessment.Despite its current recognition as an innovative technique,...Plant sap analysis has emerged as a key focus in recent agricultural research,aiming to enhance fertilizer management and improve crop nutritional assessment.Despite its current recognition as an innovative technique,the origins of sap testing date back over 120 years,with early studies largely overlooked by contemporary researchers.This work revisits these foundational studies,exploring their findings and revealing their potential to challenge modern techniques.This study discusses historical methods of sap collection and how variations in pressure and extraction techniques can influence its nutrient composition.This retrospective examination suggests that integrating these early insights can significantly enhance current sap testing methods.展开更多
基金supported by the National Basic Research Program of China (No.2006CB202204-3).
文摘The determination of gas pressure before uncovering coal in cross-cuts and in shafts is one of the important steps in pre- dicting coal and gas outbursts. However, the time spent for testing gas pressure is, at present, very long, seriously affecting the ap- plication of outburst prediction techniques in opening coal seams in cross-cuts and shafts. In order to reduce the time needed in gas pressure tests and to improve the accuracy of tests, we analyzed the process of gas pressure tests and examined the effect of the length of boreholes in coal seams in tests. The result shows that 1) the shorter the borehole, the easier the real pressure value of gas can be obtained and 2) the main factors affecting the time spent in gas pressure tests are the length of the borehole in coal seams, the gas emission time after the borehole has been formed and the quality of the borehole-sealing. The longer the length of the bore- hole, the longer the gas emission time and the larger the pressure-relief circle formed around the borehole, the longer the time needed for pressure tests. By controlling the length of the borehole in a test case in the Huainan mining area, and adopting a quick sealing technique using a sticky liquid method, the sealing quality was clearly improved and the gas emission time as well as the amount of gas discharged greatly decreased. Before the method described, the time required for the gas pressure to increase during the pressure test process, was more than 10 days. With our new method the required time is only 5 hours. In addition, the accuracy of the gas pressure test is greatly improved.
文摘AIM: To investigate whether differences in the rapidity of a positive result for Helicobacter pylori can save res ources, by comparing two commercially available urease kits. METHODS: One hundred and eighty-five adults (130 outpatients, 55 inpatients) undergoing gastroscopy were entered prospectively. Patients were divided into two groups: Group 1 (if they were not on PPIs, antibiotics, H2A, bismuth or sucralfate for up to 14 d prior to the endoscopy) and Group 2 (if they were on, or had been on, any of the above medication in the previous 14 d). At endoscopy two sets of biopsies, taken in random order, were placed in the wells of the Campylobacter-like organism (CLO) test (Kimberly-Clark, Utah, USA) and the Quick test (Biohit Plc, Helsinki, Finland). Five additional gastric biopsies were taken for histology/Giemsa and immunohistochemical study. The two urease test slides were read at 2 min, 30 min, 2 h and 24 h. Sensitivity and specif icity at 24 h were determined. RESULTS: At 24 h, for all patients, there was no difference in sensitivity (100% vs 97.5%), specificity (99.3%), positive (97.5%) and negative predictive values (100% vs 99.3%) between the CLO and Quick tests, respectively. There was a positive result at 30 min in 17/41 (41.5%) CLO tests, and in 28/40 (70%) Quick tests, P = 0.05. Quick test enabled the prescription of eradication therapy before discharge in all 28/40 patients. Only 12 (30%) follow-up appointments were needed. If the CLO test had been used alone, only 17 (41.5%) prescriptions would have been possible prior to discharge and 24 (58%) follow-up appointments would be needed (P = 0.001). Of 2000 gastroscopies performed annually at our unit, a saving of 123 follow-up appointments (total: 8856 Euros or 11 808 USD) would be achieved if we switched to the Quick test. CONCLUSION: Direct comparison of locally available urease test kits is worthwhile, since the appropriate choice results in a significant saving of resources. Local costs and follow-up protocols will determine the magnitude of these savings.
文摘Durability problem of reinforced concrete for underground structures is a hot issue in the field of structural engineering. For underground structures, the prediction of structural service life and methodology for durability design are needed to estimate structural durability. Taking the case of Xiamen Xiang＇an subsea tunnel as background, which is designed to meet the requirement of lO0-year service life, the influential factors on tunnel lining durability are analyzed. Under the criteria of crack controlling and bearing capacity of linin~ structures, the theoretical service life of Xiamen Xiang＇an subsea tunnel lining is studied. The regulations, which are needed for the diffusion capability of chloride ions in concrete by the relevant diffusion tests, are proposed. After a quick corrosion test, the bearing capacity test on eccentric short columns is implemented to investigate the variation rules in the bearing capacity of models with time. Influence of the corrosion degree of steel bars on the bearing capacity of models is also investigated. Based on the results of model tests, the acceleration ratio between the quick corrosion in laboratory test and the natural corrosion environments is established. Thus, the natural service life of subsea tunnel lining structures can be obtained by means of laboratory tests. Then, the proposed method using this modified model is employed to predict the service life of tunnel lining structures. Finally, the design and construction measures for improving the durability of lining structures of subsea tunnel are introduced. The proposed method in the present study based on a real engineering project is superior to those with only theoretical assumptions, and would be more suitable for similar projects.
文摘Plant sap analysis has emerged as a key focus in recent agricultural research,aiming to enhance fertilizer management and improve crop nutritional assessment.Despite its current recognition as an innovative technique,the origins of sap testing date back over 120 years,with early studies largely overlooked by contemporary researchers.This work revisits these foundational studies,exploring their findings and revealing their potential to challenge modern techniques.This study discusses historical methods of sap collection and how variations in pressure and extraction techniques can influence its nutrient composition.This retrospective examination suggests that integrating these early insights can significantly enhance current sap testing methods.
