针对岩性条件劣化导致边坡稳定性下降的问题,以某露天矿山边坡为研究对象,运用SIR-20型地质雷达探测矿山滑坡体内部缺陷,并结合Slide软件模拟分析了不同岩性条件下边坡稳定性的变化规律。结果表明:软弱夹层、降雨入渗和爆破动荷载等内...针对岩性条件劣化导致边坡稳定性下降的问题,以某露天矿山边坡为研究对象,运用SIR-20型地质雷达探测矿山滑坡体内部缺陷,并结合Slide软件模拟分析了不同岩性条件下边坡稳定性的变化规律。结果表明:软弱夹层、降雨入渗和爆破动荷载等内外因共同作用造成边坡岩性劣化,进而导致边坡后期出现滑移失稳;黏聚力c值降低是岩性劣化过程中的主要力学表现,安全系数与c值呈部分抛物线关系,且c值降为50 k Pa是边坡特殊工况的失稳临界值。在综合分析矿山运行特征和岩性劣化条件基础上,提出通过减小上部第四系台阶坡面角和最终边坡角提高其永久稳定性的建议,安全系数经验证符合要求。研究结果可为矿山后期安全开采和边坡控制参数取值提供重要依据。展开更多
Soil heavy metal pollution, influenced by both natural and anthropogenic factors, significantly reduces environmental quality. In this study, Cr, Ni, Cu, As, Cd, and Pb in eight different land-use soils from Patuakhal...Soil heavy metal pollution, influenced by both natural and anthropogenic factors, significantly reduces environmental quality. In this study, Cr, Ni, Cu, As, Cd, and Pb in eight different land-use soils from Patuakhali District in Bangladesh were assessed. Concentrations of Cr, Ni, Cu, As, Cd, and Pb in soils were 1-87, 5-271, 4-181, 0-80, 0.2-24.0, and 5-276 mg kg-1, respectively, measured using an inductively coupled plasma-mass spectrometer. The enrichment factor, pollution load index (PLI), and contamination factor (CJ) of metal i were used to assess the ecological risk posed by metals in soils. The PLI ranged from 0.78 to 2.66, indicating baseline levels to progressive deterioration of soil due to metal contamination. However, C;of Cd ranged from 1.8 to 12.0, which showed that the studied soils were strongly impacted by Cd. Considering the severity of the potential ecological risk of a single metal, the descending order was Cd > As > Pb > Cu > Ni > Cr. Soils under all land uses showed moderate to very high potential ecological risk.展开更多
目的探索轻型后循环脑梗死患者在发病早期出现临床病情恶化的发生率及其影响因素。方法回顾性纳入2016年1月1日至2020年1月1日期间就诊的291例轻型后循环脑梗死患者。以急性期临床病情恶化(clinical deterioration within 24 h,CD24h)...目的探索轻型后循环脑梗死患者在发病早期出现临床病情恶化的发生率及其影响因素。方法回顾性纳入2016年1月1日至2020年1月1日期间就诊的291例轻型后循环脑梗死患者。以急性期临床病情恶化(clinical deterioration within 24 h,CD24h)和亚急性期临床病情恶化(clinical deterioration between 2 d and 14 d,CD14d)为主要终点事件。数据统计使用IBM SPSS Statistics 19.0软件,应用Pearson Chi-Square检验或Mann-Whitney U检验比较相应变量的组间差异,使用多变量Logistic回归模型分析主要终点指标的影响因素。结果主要终点事件CD24h和CD14d的发生率分别为21.6%(63/291)和30.6%(89/291),接受再灌注治疗的患者比例为13.4%(39/291)。以CD24h为终点事件的多变量Logistic回归分析模型结果显示:基线美国国立卫生院神经功能缺损评分(NIHSS)高是增加CD24h风险的正性独立影响因素(OR=1.184;95%CI=1.078~1.300;P<0.01);小脑梗死(相比脑干梗死)(OR=0.250;95%CI=0.082~0.757;P=0.014)、非大动脉粥样硬化(相比大动脉粥样硬化)(OR=0.026;95%CI=0.002~0.325;P=0.005)对CD24h有负性预测作用。以CD14d为终点事件的多变量Logistic回归分析结果提示:肺部感染(OR=28.085;95%CI=6.863~114.927;P<0.01)和基线NIHSS高(OR=1.114;95%CI=1.001~1.240;P=0.048)是增加CD14d风险的独立影响因素,而再灌注治疗(OR=0.089;95%CI=0.013~0.613,P=0.014)可降低CD14d风险;基底动脉尖部综合征(相比脑干梗死)(OR=7.526;95%CI=1.565~36.188;P=0.012)增加CD14d发生风险,而非大动脉粥样硬化(相比大动脉粥样硬化)(OR=0.076;95%CI=0.009~0.683;P=0.021)对CD14d的发生风险有负性预测作用。基线NIHSS(OR=0.834;95%CI=0.758~0.918;P<0.01),CD14d(OR=0.048;95%CI=0.018~0.130;P<0.01)和肺部感染(OR=0.045;95%CI=0.012~0.167;P<0.01)对良好临床预后(发病14 d的改良Rankin评分≤2)有负性预测作用。结论早期临床病情恶化对轻型后循环脑梗死良好临床预后有负性预测作用。大动脉粥样硬化狭窄展开更多
In this study, the influences of accumulated mileage （deterioration） and technological changes （emission standards） on emission factors （EFs） of regulated pollutants （CO, HC, and NOx） from gasoline passenger v...In this study, the influences of accumulated mileage （deterioration） and technological changes （emission standards） on emission factors （EFs） of regulated pollutants （CO, HC, and NOx） from gasoline passenger vehicles were investigated based on Inspection and Maintenance （I/M） data using the chassis dynamometer method. The accumulated mileage of passenger vehicles was significantly linearly correlated with vehicle age. For most cases, the average EFs of CO, HC and NOx were significantly linearly correlated with accumulated mileage, indicating that emission deterioration had a significant impact on pollutant EFs. Implemented emission standards markedly influenced the EFs of regulated pollutants, and EFs markedly decreased with progressing emission standards. The present study also compared EFs of regulated pollutants between this study and the International vehicle emission （IVE） model, and marked differences in EFs were seen with variations in emission standards, vehicle types and accumulated mileage; NOx EFs in this study were higher than in the IVE model. The results provide new insight into estimating regulated pollutant emissions using the IVE model.展开更多
文摘针对岩性条件劣化导致边坡稳定性下降的问题,以某露天矿山边坡为研究对象,运用SIR-20型地质雷达探测矿山滑坡体内部缺陷,并结合Slide软件模拟分析了不同岩性条件下边坡稳定性的变化规律。结果表明:软弱夹层、降雨入渗和爆破动荷载等内外因共同作用造成边坡岩性劣化,进而导致边坡后期出现滑移失稳;黏聚力c值降低是岩性劣化过程中的主要力学表现,安全系数与c值呈部分抛物线关系,且c值降为50 k Pa是边坡特殊工况的失稳临界值。在综合分析矿山运行特征和岩性劣化条件基础上,提出通过减小上部第四系台阶坡面角和最终边坡角提高其永久稳定性的建议,安全系数经验证符合要求。研究结果可为矿山后期安全开采和边坡控制参数取值提供重要依据。
基金Prof. Dr. Mohammad Shams-Ud-Din (Vice Chancellor, PSTU), for his valuable suggestions, cooperation, and provision of funding to conduct this research
文摘Soil heavy metal pollution, influenced by both natural and anthropogenic factors, significantly reduces environmental quality. In this study, Cr, Ni, Cu, As, Cd, and Pb in eight different land-use soils from Patuakhali District in Bangladesh were assessed. Concentrations of Cr, Ni, Cu, As, Cd, and Pb in soils were 1-87, 5-271, 4-181, 0-80, 0.2-24.0, and 5-276 mg kg-1, respectively, measured using an inductively coupled plasma-mass spectrometer. The enrichment factor, pollution load index (PLI), and contamination factor (CJ) of metal i were used to assess the ecological risk posed by metals in soils. The PLI ranged from 0.78 to 2.66, indicating baseline levels to progressive deterioration of soil due to metal contamination. However, C;of Cd ranged from 1.8 to 12.0, which showed that the studied soils were strongly impacted by Cd. Considering the severity of the potential ecological risk of a single metal, the descending order was Cd > As > Pb > Cu > Ni > Cr. Soils under all land uses showed moderate to very high potential ecological risk.
文摘目的探索轻型后循环脑梗死患者在发病早期出现临床病情恶化的发生率及其影响因素。方法回顾性纳入2016年1月1日至2020年1月1日期间就诊的291例轻型后循环脑梗死患者。以急性期临床病情恶化(clinical deterioration within 24 h,CD24h)和亚急性期临床病情恶化(clinical deterioration between 2 d and 14 d,CD14d)为主要终点事件。数据统计使用IBM SPSS Statistics 19.0软件,应用Pearson Chi-Square检验或Mann-Whitney U检验比较相应变量的组间差异,使用多变量Logistic回归模型分析主要终点指标的影响因素。结果主要终点事件CD24h和CD14d的发生率分别为21.6%(63/291)和30.6%(89/291),接受再灌注治疗的患者比例为13.4%(39/291)。以CD24h为终点事件的多变量Logistic回归分析模型结果显示:基线美国国立卫生院神经功能缺损评分(NIHSS)高是增加CD24h风险的正性独立影响因素(OR=1.184;95%CI=1.078~1.300;P<0.01);小脑梗死(相比脑干梗死)(OR=0.250;95%CI=0.082~0.757;P=0.014)、非大动脉粥样硬化(相比大动脉粥样硬化)(OR=0.026;95%CI=0.002~0.325;P=0.005)对CD24h有负性预测作用。以CD14d为终点事件的多变量Logistic回归分析结果提示:肺部感染(OR=28.085;95%CI=6.863~114.927;P<0.01)和基线NIHSS高(OR=1.114;95%CI=1.001~1.240;P=0.048)是增加CD14d风险的独立影响因素,而再灌注治疗(OR=0.089;95%CI=0.013~0.613,P=0.014)可降低CD14d风险;基底动脉尖部综合征(相比脑干梗死)(OR=7.526;95%CI=1.565~36.188;P=0.012)增加CD14d发生风险,而非大动脉粥样硬化(相比大动脉粥样硬化)(OR=0.076;95%CI=0.009~0.683;P=0.021)对CD14d的发生风险有负性预测作用。基线NIHSS(OR=0.834;95%CI=0.758~0.918;P<0.01),CD14d(OR=0.048;95%CI=0.018~0.130;P<0.01)和肺部感染(OR=0.045;95%CI=0.012~0.167;P<0.01)对良好临床预后(发病14 d的改良Rankin评分≤2)有负性预测作用。结论早期临床病情恶化对轻型后循环脑梗死良好临床预后有负性预测作用。大动脉粥样硬化狭窄
基金supported by the National Natural Science Foundation of China (No. 21577125)the Social Development Special Fund from Science and Technology Bureau of Hangzhou, China (No. 20110533B09)
文摘In this study, the influences of accumulated mileage （deterioration） and technological changes （emission standards） on emission factors （EFs） of regulated pollutants （CO, HC, and NOx） from gasoline passenger vehicles were investigated based on Inspection and Maintenance （I/M） data using the chassis dynamometer method. The accumulated mileage of passenger vehicles was significantly linearly correlated with vehicle age. For most cases, the average EFs of CO, HC and NOx were significantly linearly correlated with accumulated mileage, indicating that emission deterioration had a significant impact on pollutant EFs. Implemented emission standards markedly influenced the EFs of regulated pollutants, and EFs markedly decreased with progressing emission standards. The present study also compared EFs of regulated pollutants between this study and the International vehicle emission （IVE） model, and marked differences in EFs were seen with variations in emission standards, vehicle types and accumulated mileage; NOx EFs in this study were higher than in the IVE model. The results provide new insight into estimating regulated pollutant emissions using the IVE model.
