The spatial concentrations, seasonal trends, profiles and congener pairs of ambient polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） were investigated within a seasonally active ...The spatial concentrations, seasonal trends, profiles and congener pairs of ambient polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） were investigated within a seasonally active sampling scheme during Jun 2008 and Jan 2009 in Tianjin City, northern China. The PCDD/F concentrations ranged 14.2-172 fg I-TEQ/m3 （average 69.3 fg I-TEQ/m3） in summer and （89.8-1.01） x 103 fg I-TEQ/m3 （average 509 fg I-TEQ/m3） in winter, respectively, except for the E-waste dismantling site where much higher values were observed （1.04 x 103 fg I-TEQ]m3 in summer and 7.123 x 103 fg I-TEQ/m3 in winter）. The results indicated a significantly seasonal trend with higher TEQ values in winter as compared with summer, which could be related to increased emission sources and seasonal variations of the atmospheric boundary layer height. 2,3,4,7,8-PeCDF was the dominant contributor to the total PCDD/F toxic equivalents, and 2,3,7,8-TCDD was detected at almost all the sampling sites in winter. Most of the similarly substituted PCDD/F congener pairs exhibited high correlations, suggesting that they might have similar environmental fate or sources. But different seasonal and spatial distributions of PCDD/F concentrations indicated that the emission sources might be intermittent.展开更多
BACKGROUND There are two types of esophageal varices(EVs):high-risk EVs(HEVs)and lowrisk EVs,and HEVs pose a greater threat to patient life than low-risk EVs.The diagnosis of EVs is mainly conducted by gastroscopy,whi...BACKGROUND There are two types of esophageal varices(EVs):high-risk EVs(HEVs)and lowrisk EVs,and HEVs pose a greater threat to patient life than low-risk EVs.The diagnosis of EVs is mainly conducted by gastroscopy,which can cause discomfort to patients,or by non-invasive prediction models.A number of noninvasive models for predicting EVs have been reported;however,those that are based on the formula for calculation of liver and spleen volume in HEVs have not been reported.AIM To establish a non-invasive prediction model based on the formula for liver and spleen volume for predicting HEVs in patients with viral cirrhosis.METHODS Data from 86 EV patients with viral cirrhosis were collected.Actual liver and spleen volumes of the patients were determined by computed tomography,and their calculated liver and spleen volumes were calculated by standard formulas.Other imaging and biochemical data were determined.The impact of each parameter on HEVs was analyzed by univariate and multivariate analyses,the data from which were employed to establish a non-invasive prediction model.Then the established prediction model was compared with other previous prediction models.Finally,the discriminating ability,calibration ability,and clinical efficacy of the new model was verified in both the modeling group and the external validation group.RESULTS Data from univariate and multivariate analyses indicated that the liver-spleen volume ratio,spleen volume change rate,and aspartate aminotransferase were correlated with HEVs.These indexes were successfully used to establish the noninvasive prediction model.The comparison of the models showed that the established model could better predict HEVs compared with previous models.The discriminating ability,calibration ability,and clinical efficacy of the new model were affirmed.CONCLUSION The non-invasive prediction model for predicting HEVs in patients with viral cirrhosis was successfully established.The new model is reliable for predicting HEVs and has clinical applicability.展开更多
The effects of different curing systems on the properties of high volume fine mineral powder RPC （reactive powder concrete） and the appearances of hydrates were studied. The experimental results show that dry-heatin...The effects of different curing systems on the properties of high volume fine mineral powder RPC （reactive powder concrete） and the appearances of hydrates were studied. The experimental results show that dry-heating curing promotes the development of pozzolanic reactivity of fine mineral powder; due to low cement content, 0.20 water-bind ratio and high reactive fine mineral powder content, the strength of RPC increases by around 200% after steam curing and subsequent dry-heating curing. Scanning electron microscopy and energy spectrum diagram showed that： after the high volume fine mineral powder RPC with 0.16 water-bind ratio underwent steam curing and dry-heating curing, there was no significant change in the appearance of hydrates; after the RPC with 0.20 water-bind ratio, the cement content of 150 kg/m3 and more steel slag powder underwent dry-heating curing, there was a certain change in the appearance of C-S-H, the structure of gel was more compact and was uniformly distributed, and the Ca/Si of C-S-H gel decreased from 1.41 to around 1.20.展开更多
基金supported by the Ministry of Environmental Protection of China for the Project of Toxic Substances in the Atmosphere and Their Effect to the Soilthe National Basic Research Program (973) of China(No.2009CB421600)the National Natural Science Foundation of China (No.20897011, 20907059)
文摘The spatial concentrations, seasonal trends, profiles and congener pairs of ambient polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） were investigated within a seasonally active sampling scheme during Jun 2008 and Jan 2009 in Tianjin City, northern China. The PCDD/F concentrations ranged 14.2-172 fg I-TEQ/m3 （average 69.3 fg I-TEQ/m3） in summer and （89.8-1.01） x 103 fg I-TEQ/m3 （average 509 fg I-TEQ/m3） in winter, respectively, except for the E-waste dismantling site where much higher values were observed （1.04 x 103 fg I-TEQ]m3 in summer and 7.123 x 103 fg I-TEQ/m3 in winter）. The results indicated a significantly seasonal trend with higher TEQ values in winter as compared with summer, which could be related to increased emission sources and seasonal variations of the atmospheric boundary layer height. 2,3,4,7,8-PeCDF was the dominant contributor to the total PCDD/F toxic equivalents, and 2,3,7,8-TCDD was detected at almost all the sampling sites in winter. Most of the similarly substituted PCDD/F congener pairs exhibited high correlations, suggesting that they might have similar environmental fate or sources. But different seasonal and spatial distributions of PCDD/F concentrations indicated that the emission sources might be intermittent.
文摘BACKGROUND There are two types of esophageal varices(EVs):high-risk EVs(HEVs)and lowrisk EVs,and HEVs pose a greater threat to patient life than low-risk EVs.The diagnosis of EVs is mainly conducted by gastroscopy,which can cause discomfort to patients,or by non-invasive prediction models.A number of noninvasive models for predicting EVs have been reported;however,those that are based on the formula for calculation of liver and spleen volume in HEVs have not been reported.AIM To establish a non-invasive prediction model based on the formula for liver and spleen volume for predicting HEVs in patients with viral cirrhosis.METHODS Data from 86 EV patients with viral cirrhosis were collected.Actual liver and spleen volumes of the patients were determined by computed tomography,and their calculated liver and spleen volumes were calculated by standard formulas.Other imaging and biochemical data were determined.The impact of each parameter on HEVs was analyzed by univariate and multivariate analyses,the data from which were employed to establish a non-invasive prediction model.Then the established prediction model was compared with other previous prediction models.Finally,the discriminating ability,calibration ability,and clinical efficacy of the new model was verified in both the modeling group and the external validation group.RESULTS Data from univariate and multivariate analyses indicated that the liver-spleen volume ratio,spleen volume change rate,and aspartate aminotransferase were correlated with HEVs.These indexes were successfully used to establish the noninvasive prediction model.The comparison of the models showed that the established model could better predict HEVs compared with previous models.The discriminating ability,calibration ability,and clinical efficacy of the new model were affirmed.CONCLUSION The non-invasive prediction model for predicting HEVs in patients with viral cirrhosis was successfully established.The new model is reliable for predicting HEVs and has clinical applicability.
基金Funded by the Science and Technology Foundation of Beijing Municipal Education Commission (KM200410016004)
文摘The effects of different curing systems on the properties of high volume fine mineral powder RPC （reactive powder concrete） and the appearances of hydrates were studied. The experimental results show that dry-heating curing promotes the development of pozzolanic reactivity of fine mineral powder; due to low cement content, 0.20 water-bind ratio and high reactive fine mineral powder content, the strength of RPC increases by around 200% after steam curing and subsequent dry-heating curing. Scanning electron microscopy and energy spectrum diagram showed that： after the high volume fine mineral powder RPC with 0.16 water-bind ratio underwent steam curing and dry-heating curing, there was no significant change in the appearance of hydrates; after the RPC with 0.20 water-bind ratio, the cement content of 150 kg/m3 and more steel slag powder underwent dry-heating curing, there was a certain change in the appearance of C-S-H, the structure of gel was more compact and was uniformly distributed, and the Ca/Si of C-S-H gel decreased from 1.41 to around 1.20.
