The physiology and ecology of planktonic organisms are influenced by the concentration, chemical speciation and resulting bioavailability of some trace metals. The determination of the elemental structure of phytoplan...The physiology and ecology of planktonic organisms are influenced by the concentration, chemical speciation and resulting bioavailability of some trace metals. The determination of the elemental structure of phytoplankton is important for interpretation of physiological and functional states of coastal ecosystems. The present study is focused on the structure and elemental composition of the phytoplankton assemblages from the different coastal zones by instrumental neutron activation analysis (INAA), scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS). For the first time these complementary techniques were simultaneously applied to study the Black Sea phytoplankton. The concentrations of 45 elements in the coastal phytoplankton communities used as bioindicator of inorganic contamination of the Black Sea coastal area near Sevastopol, Ukraine, were determined. Phytoplankton samples were collected by total tows of the plankton net with 35 μm pore size at 3 stations situated in polluted and relatively pristine water areas of the Sevastopol coastal zone during autumn period of the phytoplankton growth. The concentration of Mg, Al, Sc, Ti, V, Mn, As, Rb, Ba, Th and Fe, Cr increases exponentially from relatively pristine station to more polluted station and 10-times and 3-times greater, respectively, in the phytoplankton of the Sevastopol Bay. The rare-earth elements have relatively the same concentration values less than 1 μg/g and tend to accumulate in the phytoplankton from the polluted station in the Sevastopol Bay. The obtained results are in a good agreement with the elemental concentration data in the oceanic plankton, plankton communities from the White Sea and the Black Sea. Using energy-dispersive X-ray spectrometry the mineral particles of unknown origin and impurities of copper (0.42% by weight) in the phytoplankton at the polluted station and zinc (0.57% by weight) at the relatively pristine station were determined.展开更多
Ore grades are currently declining and mines are increasingly required to operate more efficiently in order to save costs and conserve resources. As a result, automated procedures to control and measure process effici...Ore grades are currently declining and mines are increasingly required to operate more efficiently in order to save costs and conserve resources. As a result, automated procedures to control and measure process efficiency have become popular: The demand for sustainable mining and metals processing is globally increasing. Mineral Liberation Analysis is a well established technique to analyse and optimize mining processes and its significance to process mineralogy studies and mineral & metallurgical processing has been widely reported. Dedicated systems consisting of an optimized scanning electron microscopes (SEM) and usually several X-ray detectors are an established solution. With the advent of large area SDDs (Silicon drift detector) and progress in stage automation on conventional SEMs, the speed of X-Ray acquisition is no longer a limiting factor. However, until now, the particle analysis packages on commercially available systems do not lend themselves to Mineral Liberation Analysis without significant modification. INCAMineral is a new solution for mineral liberation analysis which runs on conventional SEMs equipped with large area SDDs.展开更多
[ Objective] The aim was to study the application of scanning electron microscopy（SEM） on the physical property and ideological distri- bution of partials. [ Method] By dint of scanning electron microscopy, the morp...[ Objective] The aim was to study the application of scanning electron microscopy（SEM） on the physical property and ideological distri- bution of partials. [ Method] By dint of scanning electron microscopy, the morphological property of each source and main elements were analyzed. Compared with morphological property of sampling point, the source of particles was determined. [ Result] The results were consistent with the analysis of CMB8.2 chemical mass balance receptor model. Taking the four detection stations in Longyan Normal Training College, Minxi Vocational ＆ Technical College, Longyan University, and Longyan Environment Monitoring Station as examples, the major air pollutants respectively were soil sand, dust of burning coal, second fugitive dust; soil sand, second fugitive dust, vehicle exhausts; second fugitive dust, soil; and second fugitive dust, vehicle exhausts, dust of burning coal. [ Conclusion] The study result had certain guiding significance to the analysis of sources of particles in the atmosphere and atmosphere environment treatment.展开更多
The utility of GIS （geographic information system） methods and spatial statistical analysis on spectral maps of sediment samples were examined. Detailed elemental maps are often constructed using energy dispersive X...The utility of GIS （geographic information system） methods and spatial statistical analysis on spectral maps of sediment samples were examined. Detailed elemental maps are often constructed using energy dispersive X-ray techniques and SEM （scanning electron microscopy）. The elemental neighborhood associations of a single element, P （phosphorus）, were quantified at a magnification of 3,000 ×. For each of the 170,000 pixels on the images which displayed a strong P concentration, neighborhoods from 0.1μm^2 to 12 μm^2 were examined for associated elemental concentrations. PCA （principal component analysis） revealed two significant neighborhood types associated with P in samples of pH 4, and three neighborhood types at pH 8. These neighborhoods corresponded to Mg-P associations commonly found to be chemically prevalent in river sediments impacted by agricultural operations. Discriminant analysis showed that the greatest accuracy in predicting sample pH could be achieved by using a neighborhood size of 12 ~m2. Potassium at relatively large neighborhood sizes was the element most significant in predicting pH. While many of the chemical associations in close proximity to P could be predicted and explained through mineral solubility, spatial analysis provided some interesting insights into the structure of the samples. Results also indicted differences in the spatial scale associated with different processes.展开更多
In scanning tunneling microscopy-induced luminescence(STML),the photon count is measured to reflect single-molecule properties,e.g.,the first molecular excited state.The energy of the first excited state is typically ...In scanning tunneling microscopy-induced luminescence(STML),the photon count is measured to reflect single-molecule properties,e.g.,the first molecular excited state.The energy of the first excited state is typically shown by a rise of the photon count as a function of the bias voltage between the tip and the substrate.It remains a challenge to determine the precise rise position of the current due to possible experimental noise.In this work,we propose an alternating current version of STML to resolve the fine structures in the photon count measurement.The measured photon count and the current at the long-time limit show a sinusoidal oscillation.The zero-frequency component of the current shows knee points at the precise voltage as the fraction of the detuning between the molecular gap and the DC component of the bias voltage.We propose to measure the energy level with discontinuity of the first derivative of such a zero-frequency component.The current method will extend the application of STML in terms of measuring molecular properties.展开更多
Sediment accumulation on the bed of open sewers and drains reduces hydraulic efficiency and can cause localized flooding.Slotted invert traps installed underneath the bed of open sewers and drains can eliminate sedime...Sediment accumulation on the bed of open sewers and drains reduces hydraulic efficiency and can cause localized flooding.Slotted invert traps installed underneath the bed of open sewers and drains can eliminate sediment build-up by catching sediment load.Previous three-dimensional(3D)computational studies have examined the particle trapping performance of invert traps of different shapes and depths under varied sediment and flow conditions,considering particles as spheres.For two-dimensional and 3D numerical modeling,researchers assumed the lid geometry to be a thin line and a plane,respectively.In this 3D numerical study,the particle trapping efficiency of a slotted irregular hexagonal invert trap fitted at the flume bottom was examined by incorporating the particle shape factor of non-spherical sewage solid particles and the thicknesses of upstream and downstream lids over the trap in the discrete phase model of the ANSYS Fluent 2020 R1 software.The volume of fluid(VOF)and the realizable k-turbulence models were used to predict the velocity field.The two-dimensional particle image velocimetry(PIV)was used to measure the velocity field inside the invert trap.The results showed that the thicknesses of upstream and downstream lids affected the velocity field and turbulent kinetic energy at all flow depths.The joint impact of the particle shape factor and lid thickness on the trap efficiency was significant.When both the lid thickness and particle shape factor were considered in the numerical modeling,trap efficiencies were underestimated,with relative errors of-8.66%to-0.65%in comparison to the experimental values of Mohsin and Kaushal(2017).They were also lower than the values predicted by Mohsin and Kaushal(2017),which showed an overall overestimation with errors of-2.3%to 17.4%.展开更多
文摘The physiology and ecology of planktonic organisms are influenced by the concentration, chemical speciation and resulting bioavailability of some trace metals. The determination of the elemental structure of phytoplankton is important for interpretation of physiological and functional states of coastal ecosystems. The present study is focused on the structure and elemental composition of the phytoplankton assemblages from the different coastal zones by instrumental neutron activation analysis (INAA), scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS). For the first time these complementary techniques were simultaneously applied to study the Black Sea phytoplankton. The concentrations of 45 elements in the coastal phytoplankton communities used as bioindicator of inorganic contamination of the Black Sea coastal area near Sevastopol, Ukraine, were determined. Phytoplankton samples were collected by total tows of the plankton net with 35 μm pore size at 3 stations situated in polluted and relatively pristine water areas of the Sevastopol coastal zone during autumn period of the phytoplankton growth. The concentration of Mg, Al, Sc, Ti, V, Mn, As, Rb, Ba, Th and Fe, Cr increases exponentially from relatively pristine station to more polluted station and 10-times and 3-times greater, respectively, in the phytoplankton of the Sevastopol Bay. The rare-earth elements have relatively the same concentration values less than 1 μg/g and tend to accumulate in the phytoplankton from the polluted station in the Sevastopol Bay. The obtained results are in a good agreement with the elemental concentration data in the oceanic plankton, plankton communities from the White Sea and the Black Sea. Using energy-dispersive X-ray spectrometry the mineral particles of unknown origin and impurities of copper (0.42% by weight) in the phytoplankton at the polluted station and zinc (0.57% by weight) at the relatively pristine station were determined.
文摘Ore grades are currently declining and mines are increasingly required to operate more efficiently in order to save costs and conserve resources. As a result, automated procedures to control and measure process efficiency have become popular: The demand for sustainable mining and metals processing is globally increasing. Mineral Liberation Analysis is a well established technique to analyse and optimize mining processes and its significance to process mineralogy studies and mineral & metallurgical processing has been widely reported. Dedicated systems consisting of an optimized scanning electron microscopes (SEM) and usually several X-ray detectors are an established solution. With the advent of large area SDDs (Silicon drift detector) and progress in stage automation on conventional SEMs, the speed of X-Ray acquisition is no longer a limiting factor. However, until now, the particle analysis packages on commercially available systems do not lend themselves to Mineral Liberation Analysis without significant modification. INCAMineral is a new solution for mineral liberation analysis which runs on conventional SEMs equipped with large area SDDs.
基金Supported by Young Teacher Innovation Program of Jilin University(421031674425)Seed Fund of Jilin University (421021614425)
文摘[ Objective] The aim was to study the application of scanning electron microscopy（SEM） on the physical property and ideological distri- bution of partials. [ Method] By dint of scanning electron microscopy, the morphological property of each source and main elements were analyzed. Compared with morphological property of sampling point, the source of particles was determined. [ Result] The results were consistent with the analysis of CMB8.2 chemical mass balance receptor model. Taking the four detection stations in Longyan Normal Training College, Minxi Vocational ＆ Technical College, Longyan University, and Longyan Environment Monitoring Station as examples, the major air pollutants respectively were soil sand, dust of burning coal, second fugitive dust; soil sand, second fugitive dust, vehicle exhausts; second fugitive dust, soil; and second fugitive dust, vehicle exhausts, dust of burning coal. [ Conclusion] The study result had certain guiding significance to the analysis of sources of particles in the atmosphere and atmosphere environment treatment.
文摘The utility of GIS （geographic information system） methods and spatial statistical analysis on spectral maps of sediment samples were examined. Detailed elemental maps are often constructed using energy dispersive X-ray techniques and SEM （scanning electron microscopy）. The elemental neighborhood associations of a single element, P （phosphorus）, were quantified at a magnification of 3,000 ×. For each of the 170,000 pixels on the images which displayed a strong P concentration, neighborhoods from 0.1μm^2 to 12 μm^2 were examined for associated elemental concentrations. PCA （principal component analysis） revealed two significant neighborhood types associated with P in samples of pH 4, and three neighborhood types at pH 8. These neighborhoods corresponded to Mg-P associations commonly found to be chemically prevalent in river sediments impacted by agricultural operations. Discriminant analysis showed that the greatest accuracy in predicting sample pH could be achieved by using a neighborhood size of 12 ~m2. Potassium at relatively large neighborhood sizes was the element most significant in predicting pH. While many of the chemical associations in close proximity to P could be predicted and explained through mineral solubility, spatial analysis provided some interesting insights into the structure of the samples. Results also indicted differences in the spatial scale associated with different processes.
基金the National Natural Science Foundation of China(NSFC)(Grant No.11875049)the NSAF(Grant Nos.U1730449 and U1930403)the National Basic Research Program of China(Grant No.2016YFA0301201).
文摘In scanning tunneling microscopy-induced luminescence(STML),the photon count is measured to reflect single-molecule properties,e.g.,the first molecular excited state.The energy of the first excited state is typically shown by a rise of the photon count as a function of the bias voltage between the tip and the substrate.It remains a challenge to determine the precise rise position of the current due to possible experimental noise.In this work,we propose an alternating current version of STML to resolve the fine structures in the photon count measurement.The measured photon count and the current at the long-time limit show a sinusoidal oscillation.The zero-frequency component of the current shows knee points at the precise voltage as the fraction of the detuning between the molecular gap and the DC component of the bias voltage.We propose to measure the energy level with discontinuity of the first derivative of such a zero-frequency component.The current method will extend the application of STML in terms of measuring molecular properties.
文摘Sediment accumulation on the bed of open sewers and drains reduces hydraulic efficiency and can cause localized flooding.Slotted invert traps installed underneath the bed of open sewers and drains can eliminate sediment build-up by catching sediment load.Previous three-dimensional(3D)computational studies have examined the particle trapping performance of invert traps of different shapes and depths under varied sediment and flow conditions,considering particles as spheres.For two-dimensional and 3D numerical modeling,researchers assumed the lid geometry to be a thin line and a plane,respectively.In this 3D numerical study,the particle trapping efficiency of a slotted irregular hexagonal invert trap fitted at the flume bottom was examined by incorporating the particle shape factor of non-spherical sewage solid particles and the thicknesses of upstream and downstream lids over the trap in the discrete phase model of the ANSYS Fluent 2020 R1 software.The volume of fluid(VOF)and the realizable k-turbulence models were used to predict the velocity field.The two-dimensional particle image velocimetry(PIV)was used to measure the velocity field inside the invert trap.The results showed that the thicknesses of upstream and downstream lids affected the velocity field and turbulent kinetic energy at all flow depths.The joint impact of the particle shape factor and lid thickness on the trap efficiency was significant.When both the lid thickness and particle shape factor were considered in the numerical modeling,trap efficiencies were underestimated,with relative errors of-8.66%to-0.65%in comparison to the experimental values of Mohsin and Kaushal(2017).They were also lower than the values predicted by Mohsin and Kaushal(2017),which showed an overall overestimation with errors of-2.3%to 17.4%.
