The determination of toxic metals in water using multiwalled carbon nanotubes （MWNTs） as a solid-phase extraction adsorbent prior to their determination by inductively coupled plasma mass spectrometry （ICP-MS） has...The determination of toxic metals in water using multiwalled carbon nanotubes （MWNTs） as a solid-phase extraction adsorbent prior to their determination by inductively coupled plasma mass spectrometry （ICP-MS） has been investigated. Standard addition method was applied for the calibration using aqueous solutions. Multiwalled carbon nanotubes （MWNTs） absorb these metals at pH 8.0, HNO3 of 1.0 mol-Ll is used for complete elusion of these metals from MWNTs. Previously investigated parameters have been applied for the determination of Pb, Cr, Ni and Mn in tap water samples. Fifteen tap water samples from different locations of Riyadh metropolitan area have been determined by ICP-MS after preconcentration with MWNTs.展开更多
The adsorption behavior of multiwalled carbon nanotubes （MWNTs） toward heavy elements has been investigated systemically, and a new method has been developed for the determination of trace elements in water samples ...The adsorption behavior of multiwalled carbon nanotubes （MWNTs） toward heavy elements has been investigated systemically, and a new method has been developed for the determination of trace elements in water samples based on preconcentration with mini-column packed with MWNTs prior to its determination by flame atomic absorption spectrometry （FAAS） The recommended parameters of proposed method influencing the preconcentration of the analytes, such as pH of the sample, sample flow rate and volume, elute solution and interfering ions, have been used. Under the optimized conditions, the calibration graphs were linear with the correlation coefficient range 0.9981-0.9995. According to the results, the metals were found 0.019-0.051, 0.011-0.031, 0.00-0.081, 0.00-0.0002, 0.007-0.0925, 0.00-0.0104 μg/L in water samples for Pb, Mn, Zn, Cd, Fe, Cu respectively. The percentage relative standard deviation （%RSD） for five replicate samples were 〈 5% in all cases. The method has been successfully applied to the determination of trace elements in some environmental samples with satisfactory results.展开更多
FI system was used for the determination of histamine. A mini-column filled with amberlite resin （weak cation exchanger） was introduced to the flow system. A 200 laL of the sample was injected into the carrier strea...FI system was used for the determination of histamine. A mini-column filled with amberlite resin （weak cation exchanger） was introduced to the flow system. A 200 laL of the sample was injected into the carrier stream through the injection valve. The merged streams were passed through a quartz flow cell in a spectrophotometer connected to recorder. Under the optimum conditions, the calibration curve was linear in the range 0.02-1.5 μg mL^-1 of histamine using the peak height as an analytical signal, while the detection limit was 0.01 μg mL^-1. The precision and accuracy of the method were studied depending upon the values of the relative standard deviation and relative error percentage. The selectivity of the method was investigated by studying the effect of interference from other species accompanied with histamine in fish meal. Under the optimum conditions, the system was used for on line separation, preconcentration of histamine. The proposed method was applied for the determination of histamine in fish meal. The results were compared with the standard method and a good agreement between the results was obtained.展开更多
Most aspects of construction projects mainly fall under contractual regime. However, when things go wrong such as when the project is abandoned for various reasons, they may create two different scenarios： a contract...Most aspects of construction projects mainly fall under contractual regime. However, when things go wrong such as when the project is abandoned for various reasons, they may create two different scenarios： a contract that is breached and a fixed structure that is left on the land which may constitute an incomplete benefit that is acquired by one of the parties. The transfer of such benefit is initially made with a legal ground, but that ground has since ceased to exist. If some aspect of that benefit cannot be recovered under a contract, enrichment rules may be competent to solve the problem. How to measure the different aspects of that enrichment is however a problem that may have different interpretations according to different conceptions of the foundations of enrichment liability in a particular legal system. This article explores the measures of enrichment in such cases of failed bilateral contracts scenarios working from South African perspective. It argues that in cases of failed bilateral contracts generating an enrichment situation, sanctioning a dual measure of enrichment in a legal system may be an appropriate avenue.展开更多
Mercury concentration in water, sediments and two aquatic plants were measured in the Tigris River for the period in 2013 Hg concentrations in water between 0.18-0.74 μg/g, however, in sediments ranged between 0.66-0...Mercury concentration in water, sediments and two aquatic plants were measured in the Tigris River for the period in 2013 Hg concentrations in water between 0.18-0.74 μg/g, however, in sediments ranged between 0.66-0.73 lag/g. The concentrations of accumulated mercury in aquatic plants ranged in Ceratophyllum demersum and Phragmitus australis were 0.035-0.022, 0.028-0.023 μg/g, respectively. The concentration bioconcentration factor B.C.F range between 0.331-0.209 μg/g and B.S.F 0.043-0.011 μg/g. These results indicate the ability of the aquatic plants of Tigris River to accumulate elements in their tissues more than water consequently, mercury concentrations in the food chain path way could cause health problems on public health by transfer through aquatic organisms to human. The studied plants could be considered as bioindicator for elements flow to the river from natural and anthropogenic sources. The study showed there is an increase in the concentration of this element in the Tigris River and due to the low rate of discharge of river water, which leads to high concentrations of ions dissolved and effect divorced industrial waste and sewage and irrigation water, especially in the area of Zafaraniyah a result of the large number of events industrialized as well as the impact of the Diyala River on the River Tigris.展开更多
Uranium enrichment determination by non-destructive assay is an important method in authenticating the nuclear warhead or uranium component in deep nuclear reduction verifications.In this paper,the feasibility of appl...Uranium enrichment determination by non-destructive assay is an important method in authenticating the nuclear warhead or uranium component in deep nuclear reduction verifications.In this paper,the feasibility of applying the high-energy photon interrogation to determine the uranium enrichment is studied.Simplified models are presented which were simulated by particle Monte Carlo transport code.The results indicate that the relation curves of the released neutrons and the enrichment of uranium objects are almost linear.For a uranium object of a given shape,the uranium enrichment can be obtained with the relation curves,which could be got in advance by calibration experiments or simulations.展开更多
文摘The determination of toxic metals in water using multiwalled carbon nanotubes （MWNTs） as a solid-phase extraction adsorbent prior to their determination by inductively coupled plasma mass spectrometry （ICP-MS） has been investigated. Standard addition method was applied for the calibration using aqueous solutions. Multiwalled carbon nanotubes （MWNTs） absorb these metals at pH 8.0, HNO3 of 1.0 mol-Ll is used for complete elusion of these metals from MWNTs. Previously investigated parameters have been applied for the determination of Pb, Cr, Ni and Mn in tap water samples. Fifteen tap water samples from different locations of Riyadh metropolitan area have been determined by ICP-MS after preconcentration with MWNTs.
文摘The adsorption behavior of multiwalled carbon nanotubes （MWNTs） toward heavy elements has been investigated systemically, and a new method has been developed for the determination of trace elements in water samples based on preconcentration with mini-column packed with MWNTs prior to its determination by flame atomic absorption spectrometry （FAAS） The recommended parameters of proposed method influencing the preconcentration of the analytes, such as pH of the sample, sample flow rate and volume, elute solution and interfering ions, have been used. Under the optimized conditions, the calibration graphs were linear with the correlation coefficient range 0.9981-0.9995. According to the results, the metals were found 0.019-0.051, 0.011-0.031, 0.00-0.081, 0.00-0.0002, 0.007-0.0925, 0.00-0.0104 μg/L in water samples for Pb, Mn, Zn, Cd, Fe, Cu respectively. The percentage relative standard deviation （%RSD） for five replicate samples were 〈 5% in all cases. The method has been successfully applied to the determination of trace elements in some environmental samples with satisfactory results.
文摘FI system was used for the determination of histamine. A mini-column filled with amberlite resin （weak cation exchanger） was introduced to the flow system. A 200 laL of the sample was injected into the carrier stream through the injection valve. The merged streams were passed through a quartz flow cell in a spectrophotometer connected to recorder. Under the optimum conditions, the calibration curve was linear in the range 0.02-1.5 μg mL^-1 of histamine using the peak height as an analytical signal, while the detection limit was 0.01 μg mL^-1. The precision and accuracy of the method were studied depending upon the values of the relative standard deviation and relative error percentage. The selectivity of the method was investigated by studying the effect of interference from other species accompanied with histamine in fish meal. Under the optimum conditions, the system was used for on line separation, preconcentration of histamine. The proposed method was applied for the determination of histamine in fish meal. The results were compared with the standard method and a good agreement between the results was obtained.
文摘Most aspects of construction projects mainly fall under contractual regime. However, when things go wrong such as when the project is abandoned for various reasons, they may create two different scenarios： a contract that is breached and a fixed structure that is left on the land which may constitute an incomplete benefit that is acquired by one of the parties. The transfer of such benefit is initially made with a legal ground, but that ground has since ceased to exist. If some aspect of that benefit cannot be recovered under a contract, enrichment rules may be competent to solve the problem. How to measure the different aspects of that enrichment is however a problem that may have different interpretations according to different conceptions of the foundations of enrichment liability in a particular legal system. This article explores the measures of enrichment in such cases of failed bilateral contracts scenarios working from South African perspective. It argues that in cases of failed bilateral contracts generating an enrichment situation, sanctioning a dual measure of enrichment in a legal system may be an appropriate avenue.
文摘Mercury concentration in water, sediments and two aquatic plants were measured in the Tigris River for the period in 2013 Hg concentrations in water between 0.18-0.74 μg/g, however, in sediments ranged between 0.66-0.73 lag/g. The concentrations of accumulated mercury in aquatic plants ranged in Ceratophyllum demersum and Phragmitus australis were 0.035-0.022, 0.028-0.023 μg/g, respectively. The concentration bioconcentration factor B.C.F range between 0.331-0.209 μg/g and B.S.F 0.043-0.011 μg/g. These results indicate the ability of the aquatic plants of Tigris River to accumulate elements in their tissues more than water consequently, mercury concentrations in the food chain path way could cause health problems on public health by transfer through aquatic organisms to human. The studied plants could be considered as bioindicator for elements flow to the river from natural and anthropogenic sources. The study showed there is an increase in the concentration of this element in the Tigris River and due to the low rate of discharge of river water, which leads to high concentrations of ions dissolved and effect divorced industrial waste and sewage and irrigation water, especially in the area of Zafaraniyah a result of the large number of events industrialized as well as the impact of the Diyala River on the River Tigris.
文摘Uranium enrichment determination by non-destructive assay is an important method in authenticating the nuclear warhead or uranium component in deep nuclear reduction verifications.In this paper,the feasibility of applying the high-energy photon interrogation to determine the uranium enrichment is studied.Simplified models are presented which were simulated by particle Monte Carlo transport code.The results indicate that the relation curves of the released neutrons and the enrichment of uranium objects are almost linear.For a uranium object of a given shape,the uranium enrichment can be obtained with the relation curves,which could be got in advance by calibration experiments or simulations.
