Arsenic is the focus of public attention because of its wider prevalence and toxicity. Proper sampling is important in characterizing toxic water contaminants in the groundwater. The present paper studies aspects of s...Arsenic is the focus of public attention because of its wider prevalence and toxicity. Proper sampling is important in characterizing toxic water contaminants in the groundwater. The present paper studies aspects of sampling, preservation artifacts, analytical issues etc. in a natural arsenic contaminated groundwater. The samples were collected from arsenic contaminated groundwater at three locations of village Kaudikasa in Rajnandgaon (Chhattisgarh). The standard method of sampling and preservation of arsenic was examined. The permitted sample holding time in this state is 180 days which has been found to be unrealistic on examination. The communication also compares the loss pattern of arsenic in unpreserved samples with samples preserved and kept at 4?C. It was found that about As losses during hold- ing after preservation were about 0% in one day, 35% in seven day, 70% in fifteen day, and 65% in thirty days time. Hence, the present recommended method of preservation leads to huge under reporting of As in natural samples. If the pattern of losses observed at the present location exists at other locations then the actual As levels could be much higher than the reported ones.展开更多
Background: Pattern hair loss (PHL) is the most common form of hair loss affecting both men and women. The occipital region, located at the back of the scalp, has been considered resistant to hair loss in PHL. It is o...Background: Pattern hair loss (PHL) is the most common form of hair loss affecting both men and women. The occipital region, located at the back of the scalp, has been considered resistant to hair loss in PHL. It is often used as a donor site for hair transplantation procedures. However, evidence suggests that the occipital region may also be affected by PHL, although to a lesser extent compared to the frontal and vertex regions. Objective: To assess the levels and determinants of occipital involvement in PHL, focusing on gender and disease severity. Such data would enhance the comprehensive understanding of PHL progression and inform development of improved treatment strategies. Methods: This retrospective study involved 1993 adults (1000 males, 993 females) following for PHL at a specialized hair clinic in Jeddah, Saudi Arabia. Any patient who had hair transplantation in the past and any male who had balding areas (Hamilton-Norwood scales 4 to 7) at the initial consultation was excluded. The primary outcome was occipital involvement, defined as >10% thin hairs in the trichometry assessments of the occipital region. Additional data included patients age, treatment status, disease severity, and other trichometry parameters. Results: The prevalence of occipital involvement was found to be 23.8% overall, significantly more frequent in females (35.6%) than males with early PHL (Hamilton-Norwood scales 2 and 3) (12.1%) (p Conclusion: This study underscored the relevance of gender and disease severity in occipital involvement in PHL. Females had significantly higher rates of occipital involvement, suggesting that gender differences are critical in understanding PHL progression. Future research should aim to validate these findings, with an aim to refine therapeutic and surgical approaches to improve patient outcomes.展开更多
A method to determine muzzle velocity loss according to the actual measured bore wear pattern is proposed.Therefore,it is unnecessary to conduct live firing and other experiments for determination of muzzle velocity l...A method to determine muzzle velocity loss according to the actual measured bore wear pattern is proposed.Therefore,it is unnecessary to conduct live firing and other experiments for determination of muzzle velocity loss.It has been applied to a national military standard since July 1,2004.展开更多
为解决港口岸电系统中负荷功率存在较强冲击性问题,提出一种基于储能电池的负荷功率柔性控制方法,在实现功率实时平抑和无功动态补偿的基础上,降低系统网侧线损、提升储能电池循环寿命及应对极端工况的能力。首先,介绍负荷功率柔性控制...为解决港口岸电系统中负荷功率存在较强冲击性问题,提出一种基于储能电池的负荷功率柔性控制方法,在实现功率实时平抑和无功动态补偿的基础上,降低系统网侧线损、提升储能电池循环寿命及应对极端工况的能力。首先,介绍负荷功率柔性控制系统(load power flexible control system,LPFCS)的拓扑结构及控制方式;其次,依据负荷功率和电池荷电状态来划分负荷工况,进而以负荷功率波动的平抑、防止电池过充过放以及提升储能系统应对极端工况的能力为原则,将LPFCS的工作模式分为空闲、填谷、削峰以及限幅4种模式;然后,建立系统网侧线损优化模型,求解模型得出功率补偿值的取值区间,并基于该区间确定不同工况下LPFCS的功率补偿值。最后,基于长江某岸电系统实测负荷数据,对LPFCS的工作性能进行仿真和实验验证。结果表明:LPFCS的补偿响应时间小于0.3 s,负荷功率波动抑制率达到90%,系统网侧线损率下降17.2%。展开更多
文摘Arsenic is the focus of public attention because of its wider prevalence and toxicity. Proper sampling is important in characterizing toxic water contaminants in the groundwater. The present paper studies aspects of sampling, preservation artifacts, analytical issues etc. in a natural arsenic contaminated groundwater. The samples were collected from arsenic contaminated groundwater at three locations of village Kaudikasa in Rajnandgaon (Chhattisgarh). The standard method of sampling and preservation of arsenic was examined. The permitted sample holding time in this state is 180 days which has been found to be unrealistic on examination. The communication also compares the loss pattern of arsenic in unpreserved samples with samples preserved and kept at 4?C. It was found that about As losses during hold- ing after preservation were about 0% in one day, 35% in seven day, 70% in fifteen day, and 65% in thirty days time. Hence, the present recommended method of preservation leads to huge under reporting of As in natural samples. If the pattern of losses observed at the present location exists at other locations then the actual As levels could be much higher than the reported ones.
文摘Background: Pattern hair loss (PHL) is the most common form of hair loss affecting both men and women. The occipital region, located at the back of the scalp, has been considered resistant to hair loss in PHL. It is often used as a donor site for hair transplantation procedures. However, evidence suggests that the occipital region may also be affected by PHL, although to a lesser extent compared to the frontal and vertex regions. Objective: To assess the levels and determinants of occipital involvement in PHL, focusing on gender and disease severity. Such data would enhance the comprehensive understanding of PHL progression and inform development of improved treatment strategies. Methods: This retrospective study involved 1993 adults (1000 males, 993 females) following for PHL at a specialized hair clinic in Jeddah, Saudi Arabia. Any patient who had hair transplantation in the past and any male who had balding areas (Hamilton-Norwood scales 4 to 7) at the initial consultation was excluded. The primary outcome was occipital involvement, defined as >10% thin hairs in the trichometry assessments of the occipital region. Additional data included patients age, treatment status, disease severity, and other trichometry parameters. Results: The prevalence of occipital involvement was found to be 23.8% overall, significantly more frequent in females (35.6%) than males with early PHL (Hamilton-Norwood scales 2 and 3) (12.1%) (p Conclusion: This study underscored the relevance of gender and disease severity in occipital involvement in PHL. Females had significantly higher rates of occipital involvement, suggesting that gender differences are critical in understanding PHL progression. Future research should aim to validate these findings, with an aim to refine therapeutic and surgical approaches to improve patient outcomes.
文摘A method to determine muzzle velocity loss according to the actual measured bore wear pattern is proposed.Therefore,it is unnecessary to conduct live firing and other experiments for determination of muzzle velocity loss.It has been applied to a national military standard since July 1,2004.
文摘为解决港口岸电系统中负荷功率存在较强冲击性问题,提出一种基于储能电池的负荷功率柔性控制方法,在实现功率实时平抑和无功动态补偿的基础上,降低系统网侧线损、提升储能电池循环寿命及应对极端工况的能力。首先,介绍负荷功率柔性控制系统(load power flexible control system,LPFCS)的拓扑结构及控制方式;其次,依据负荷功率和电池荷电状态来划分负荷工况,进而以负荷功率波动的平抑、防止电池过充过放以及提升储能系统应对极端工况的能力为原则,将LPFCS的工作模式分为空闲、填谷、削峰以及限幅4种模式;然后,建立系统网侧线损优化模型,求解模型得出功率补偿值的取值区间,并基于该区间确定不同工况下LPFCS的功率补偿值。最后,基于长江某岸电系统实测负荷数据,对LPFCS的工作性能进行仿真和实验验证。结果表明:LPFCS的补偿响应时间小于0.3 s,负荷功率波动抑制率达到90%,系统网侧线损率下降17.2%。
