The molybdenum disilicide （MoSi2 ） based heating element is more and more important in modern industries relating to thermal treatment, melting and sintering due to its high working temperature. In China, the consum...The molybdenum disilicide （MoSi2 ） based heating element is more and more important in modern industries relating to thermal treatment, melting and sintering due to its high working temperature. In China, the consumption of the MoSi2 heating element continues to increase with development and upgrading of industries. However, the MoSi2 heating element .from local manufacturers still has poor quality and thus results in waste of precious molybdenum resource. In this review, the recent research results of production process of MoSi2 heating elements were briefly summarized. The purity and particle size distribution of starting MoSi2 powder as well as the mixing and sintering processes were identified as major impact fators on the performance of MoSi2 heating elements. This review points out the improving direction for local MoSi2 heating elements.展开更多
Ten male buffalo calves were randomly allotted into five groups of two each. Four groups were fed with cadmium, molybdenum, cadmium-molybdenum, and copper-cadmium-molybdenum respectively for 130 days to determine the ...Ten male buffalo calves were randomly allotted into five groups of two each. Four groups were fed with cadmium, molybdenum, cadmium-molybdenum, and copper-cadmium-molybdenum respectively for 130 days to determine the elements' metabolic interactions in calves. These results indicated that cadmium and molybdenum could increase the accumulation of molybdenum and cadmium in liver and kidneys in buffalo calves, but copper could not. reduce to normal the levels of molybdenum and cadmium in liver and kidneys caused by cadmium-molybdenum. In addition, we found the copper concentrations in liver and kindeys was significantly greater in treatment calves than in controls.展开更多
The early Cambrian carbonaceous shale and laminated chert-phosphorite assemble (the black rock series) are widespread at the northwest margin of the Tarim Basin, Northwest China. In combination with previously reporte...The early Cambrian carbonaceous shale and laminated chert-phosphorite assemble (the black rock series) are widespread at the northwest margin of the Tarim Basin, Northwest China. In combination with previously reported data, we present stable molybdenum isotope (δ98/95Mo), TOC, and redox-sensitive trace elements to evaluate the sedimentary conditions in early Cambrian water column during the deposition of the black rock series in the Tarim Basin. Redox variation was documented based on enrichment factors (MoEF, VEF, and UEF) and redox-sensitiv elements ratios (Ni/Co, V/Cr, δU), etc. During the early Cambrian, there was transgressive event, and the sea level continues to rise. In the basal Cambrian, laminated chert-phosphorite assemble with low TOC concentrations suggest the oxic sedimentary condition in a restricted basin. Light Mo isotope values and redox sensitive elements enrichment in the carbonaceous shale layer indicate lack oxygenic sedimentary condition, and was suboxic/anoxic conditions during the transgressive phase. The hydrothermal fluids from the open ocean affected the whole deposition process of the black rock series.展开更多
IM To study the relationship between trace element Mo and gastric cancer.MATERIALS AND METHODS Soil samples were collected according to its type in different areas of Jiangxi Province; available molybdenum content i...IM To study the relationship between trace element Mo and gastric cancer.MATERIALS AND METHODS Soil samples were collected according to its type in different areas of Jiangxi Province; available molybdenum content in soil was measured by catalytic polarography and rank correlation method was used to analyse correlation between the mean of soil available molybdenum and mortality rate of gastric cancer in each county and city in Jiangxi Province. Gastric cancer cases were selected from the authors′ hospital, occiput hair was collected to measure its molybdenum content with an atomic absorption spectrograph and controls were selected from the same hospital for comparison. Gastric cancer cases were selected from three hospitals at the same time, blood samples were taken on an empty stomach and serum molybdenum contents were measured with the atomic absorption spectrograph, and controls were selected from the same hospitals. Blind method was used in the whole course (chemical analysts did not know the source and nature of samples).RESULTS A negative correlation existed between soil available molybdenum content and mortality rate of gastric cancer (r=-0285, P<005); hair molybdenum contents of gastric cancer cases were lower than those of healthy controls (0308μg/g±0673μg/g and 0707μg/g±0561μg/g respectively, P<001); serum molybdenum contents of patients were also lower than those of healthy controls (2184μg/L±749μg/L and 2538μg/L±858μg/L respectively, P<005).CONCLUSION Deficiency of molybdenum may be one of the risk factors in gastric cancer.展开更多
在使用能量色散X射线荧光光谱仪定量分析钼铜矿中低含量Cu和Mo元素过程中,X光管的原级谱对测量结果影响非常大。为了降低这一影响,采用蒙特卡洛软件模拟了用Ag,Cu和Mo,Ti三种材质的滤片,在不同厚度情况下对原级谱的影响。模拟结果显示,1...在使用能量色散X射线荧光光谱仪定量分析钼铜矿中低含量Cu和Mo元素过程中,X光管的原级谱对测量结果影响非常大。为了降低这一影响,采用蒙特卡洛软件模拟了用Ag,Cu和Mo,Ti三种材质的滤片,在不同厚度情况下对原级谱的影响。模拟结果显示,1 mm Ti滤片测铜钼元素效果优于0.2 mm Ag滤片、0.02 mm Cu和0.1 mm Mo滤片。根据模拟结果,在实验室用三种滤片对样品进行了实测,谱线图对比显示,用Cu+Mo作滤片测钼元素时,本底计数大于200,用Ag和Ti作滤片测钼元素,几乎没有本底影响。但相同的样品,用Ti作滤片测得钼最高计数为800左右,而用Ag作滤片时测得钼最高计数为300左右。由此可见,用Ti作滤片测钼元素时,X光管原级谱对被测量元素的干扰影响小,其本底低于用银滤片和铜钼滤片。Ti滤片在降低本底影响的同时,钼的计数率最高,说明射线强度损失最少。用Cu+Mo作滤片测铜元素时,铜最高计数为300,用Ag作滤片时铜最高计数为180左右,而用Ti作滤片铜最高计数为500左右。由此可见,在铜元素含量较低时,用Ti作滤片测铜元素,铜的计数率最高,射线强度损失最少。通过公式计算显示:用1 mm Ti滤片测钼铜矿中铜的检出限为5.63 mg·kg^-1,钼的检出限为1.39 mg·kg^-1,检出限明显降低。采用不同含量的标准样品进行测量与化学分析拟合,通过工作曲线可见,高、低含量的样品均具有良好的线性关系,误差水平符合正常化学分析误差标准,R2为0.99及以上,说明1 mm Ti滤片测量精密度高。同一个样品进行多次重复测量,其Cu元素的RSD(%)=0.59,Mo元素的RSD(%)=0.3,均小于1,表明仪器测量稳定性好,样品测试结果具有重现性。研究结果为使用能量色散X射线荧光光谱仪测定钼铜矿中的钼和铜滤光片的选择及其厚度的确定提供了可信的依据,推荐选用1 mm Ti滤片。经过实际现场的检验。该方法稳定可靠,具有重要的实际应用价值。展开更多
文摘The molybdenum disilicide （MoSi2 ） based heating element is more and more important in modern industries relating to thermal treatment, melting and sintering due to its high working temperature. In China, the consumption of the MoSi2 heating element continues to increase with development and upgrading of industries. However, the MoSi2 heating element .from local manufacturers still has poor quality and thus results in waste of precious molybdenum resource. In this review, the recent research results of production process of MoSi2 heating elements were briefly summarized. The purity and particle size distribution of starting MoSi2 powder as well as the mixing and sintering processes were identified as major impact fators on the performance of MoSi2 heating elements. This review points out the improving direction for local MoSi2 heating elements.
文摘Ten male buffalo calves were randomly allotted into five groups of two each. Four groups were fed with cadmium, molybdenum, cadmium-molybdenum, and copper-cadmium-molybdenum respectively for 130 days to determine the elements' metabolic interactions in calves. These results indicated that cadmium and molybdenum could increase the accumulation of molybdenum and cadmium in liver and kidneys in buffalo calves, but copper could not. reduce to normal the levels of molybdenum and cadmium in liver and kidneys caused by cadmium-molybdenum. In addition, we found the copper concentrations in liver and kindeys was significantly greater in treatment calves than in controls.
文摘The early Cambrian carbonaceous shale and laminated chert-phosphorite assemble (the black rock series) are widespread at the northwest margin of the Tarim Basin, Northwest China. In combination with previously reported data, we present stable molybdenum isotope (δ98/95Mo), TOC, and redox-sensitive trace elements to evaluate the sedimentary conditions in early Cambrian water column during the deposition of the black rock series in the Tarim Basin. Redox variation was documented based on enrichment factors (MoEF, VEF, and UEF) and redox-sensitiv elements ratios (Ni/Co, V/Cr, δU), etc. During the early Cambrian, there was transgressive event, and the sea level continues to rise. In the basal Cambrian, laminated chert-phosphorite assemble with low TOC concentrations suggest the oxic sedimentary condition in a restricted basin. Light Mo isotope values and redox sensitive elements enrichment in the carbonaceous shale layer indicate lack oxygenic sedimentary condition, and was suboxic/anoxic conditions during the transgressive phase. The hydrothermal fluids from the open ocean affected the whole deposition process of the black rock series.
文摘IM To study the relationship between trace element Mo and gastric cancer.MATERIALS AND METHODS Soil samples were collected according to its type in different areas of Jiangxi Province; available molybdenum content in soil was measured by catalytic polarography and rank correlation method was used to analyse correlation between the mean of soil available molybdenum and mortality rate of gastric cancer in each county and city in Jiangxi Province. Gastric cancer cases were selected from the authors′ hospital, occiput hair was collected to measure its molybdenum content with an atomic absorption spectrograph and controls were selected from the same hospital for comparison. Gastric cancer cases were selected from three hospitals at the same time, blood samples were taken on an empty stomach and serum molybdenum contents were measured with the atomic absorption spectrograph, and controls were selected from the same hospitals. Blind method was used in the whole course (chemical analysts did not know the source and nature of samples).RESULTS A negative correlation existed between soil available molybdenum content and mortality rate of gastric cancer (r=-0285, P<005); hair molybdenum contents of gastric cancer cases were lower than those of healthy controls (0308μg/g±0673μg/g and 0707μg/g±0561μg/g respectively, P<001); serum molybdenum contents of patients were also lower than those of healthy controls (2184μg/L±749μg/L and 2538μg/L±858μg/L respectively, P<005).CONCLUSION Deficiency of molybdenum may be one of the risk factors in gastric cancer.
文摘在使用能量色散X射线荧光光谱仪定量分析钼铜矿中低含量Cu和Mo元素过程中,X光管的原级谱对测量结果影响非常大。为了降低这一影响,采用蒙特卡洛软件模拟了用Ag,Cu和Mo,Ti三种材质的滤片,在不同厚度情况下对原级谱的影响。模拟结果显示,1 mm Ti滤片测铜钼元素效果优于0.2 mm Ag滤片、0.02 mm Cu和0.1 mm Mo滤片。根据模拟结果,在实验室用三种滤片对样品进行了实测,谱线图对比显示,用Cu+Mo作滤片测钼元素时,本底计数大于200,用Ag和Ti作滤片测钼元素,几乎没有本底影响。但相同的样品,用Ti作滤片测得钼最高计数为800左右,而用Ag作滤片时测得钼最高计数为300左右。由此可见,用Ti作滤片测钼元素时,X光管原级谱对被测量元素的干扰影响小,其本底低于用银滤片和铜钼滤片。Ti滤片在降低本底影响的同时,钼的计数率最高,说明射线强度损失最少。用Cu+Mo作滤片测铜元素时,铜最高计数为300,用Ag作滤片时铜最高计数为180左右,而用Ti作滤片铜最高计数为500左右。由此可见,在铜元素含量较低时,用Ti作滤片测铜元素,铜的计数率最高,射线强度损失最少。通过公式计算显示:用1 mm Ti滤片测钼铜矿中铜的检出限为5.63 mg·kg^-1,钼的检出限为1.39 mg·kg^-1,检出限明显降低。采用不同含量的标准样品进行测量与化学分析拟合,通过工作曲线可见,高、低含量的样品均具有良好的线性关系,误差水平符合正常化学分析误差标准,R2为0.99及以上,说明1 mm Ti滤片测量精密度高。同一个样品进行多次重复测量,其Cu元素的RSD(%)=0.59,Mo元素的RSD(%)=0.3,均小于1,表明仪器测量稳定性好,样品测试结果具有重现性。研究结果为使用能量色散X射线荧光光谱仪测定钼铜矿中的钼和铜滤光片的选择及其厚度的确定提供了可信的依据,推荐选用1 mm Ti滤片。经过实际现场的检验。该方法稳定可靠,具有重要的实际应用价值。
