As the chemical industry expands,the use of benzene,toluene,and xylene(collectively known as BTX)in industrial production has increased greatly.Meanwhile,the toxic nature and potential health hazards of BTX gases cann...As the chemical industry expands,the use of benzene,toluene,and xylene(collectively known as BTX)in industrial production has increased greatly.Meanwhile,the toxic nature and potential health hazards of BTX gases cannot be ignored due to low-concentration leaks underline the critical need for rapid and real-time monitoring of these gases.Chemiresistive metal oxide semiconductor(MOS)-based gas sensors,which are extensively used for gas detection in both industrial settings and everyday life,emerge as one of the optimal solutions for trace BTX detection.These sensors are highly valued for their high sensitivity and low detection limits.Nevertheless,the improvement of selectivity towards specific BTX gases to achieve efficient and precise detection still remains challenging.This review summarizes the chemiresistive MOS-based gas sensors designed for BTX detection,categorizing them based on the components of sensing materials-basically into three groups:single-component,single heterojunction,and multiple heterojunctions gas sensing materials.Further,the review proposes the future application prospects of chemiresistive MOS-based BTX gas sensors,with specific emphasis on their significance in promoting industrial safety and environmental monitoring.展开更多
The study of trace metals in the atmosphere and lake water is important due to their critical effects on humans, aquatic animals and the geochemical balance of ecosystems. The objective of this study was to investigat...The study of trace metals in the atmosphere and lake water is important due to their critical effects on humans, aquatic animals and the geochemical balance of ecosystems. The objective of this study was to investigate the concentration of trace metals in atmospheric and lake water samples during the rainy season （before and after precipitation） between November and December 2015. Typical methods of sample preparation for trace metal determination such as cloud point extraction, solid phase extraction and dispersive liquid- liquid micro-extraction are time-consuming and difficult to perform; therefore, there is a crucial need for development of more effective sample preparation procedure. A convection microwave assisted digestion procedure for extraction of trace metals was developed for use prior to inductively couple plasma-mass spectrometric determination. The result showed that metals like zinc （133.50-419.30 μg/m3） and aluminum （53.58-378.93 μg/m3） had higher concentrations in atmospheric samples as compared to lake samples before precipitation. On the other hand, the concentrations of zinc, aluminum, chromium and arsenic were significantly higher in lake samples after precipitation and lower in atmospheric samples. The relationship between physicochemical parameters （pH and turbidity） and heavy metal concentrations was investigated as well. Furthermore, enrichment factor analysis indicated that anthropogenic sources such as soil dust, biomass burning and fuel combustion influenced the metal concentrations in the atmosphere.展开更多
Established system equivalences for transition systems, such as trace equivalence and failures equivalence, require the ob- servations to be exactly identical. However, an accurate measure- ment is impossible when int...Established system equivalences for transition systems, such as trace equivalence and failures equivalence, require the ob- servations to be exactly identical. However, an accurate measure- ment is impossible when interacting with the physical world, hence exact equivalence is restrictive and not robust. Using Baire met- ric, a generalized framework of transition system approximation is proposed by developing the notions of approximate language equivalence and approximate singleton failures （SF） equivalence. The framework takes the traditional exact equivalence as a special case. The approximate language equivalence is coarser than the approximate Slc equivalence, just like the hierarchy of the exact ones. The main conclusion is that the two approximate equiva- lences satisfy the transitive property, consequently, they can be successively used in transition system approximation.展开更多
Tomato is a market gardening product that plays an important nutritional and economic role in Burkina Faso. However, the bad use of pesticides for its production could have negative impacts </span><span style...Tomato is a market gardening product that plays an important nutritional and economic role in Burkina Faso. However, the bad use of pesticides for its production could have negative impacts </span><span style="font-family:Verdana;">consumers’</span><span style="font-family:Verdana;"> health. The objective of the present study was to assess the concentration of trace metal elements (Pb, Cd </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> As), 15N isotopes (</span></span><span style="font-family:Verdana;">NO<sub>2</sub><sup style="margin-left:-7px;">-</sup></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> NO<sub>3</sub><sup style="margin-left:-7px;">-</sup></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> NH<sub>4</sub><sup style="margin-left:-7px;">+</sup></span><span style="font-family:Verdana;">) and phosphorus (</span><span style="font-family:Verdana;">PO<sub>4</sub><sup style="margin-left:-7px;">2-</sup></span><span style="font-family:""><span style="font-family:Verdana;">) in tomatoes according to cultivation practices. Thus, three tomato varieties (Mon</span><span><span style="font-family:Verdana;">gal F1, F1 Cobra 26 </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> Roma F1) were grown using organic and conventional production methods on 2 sites at Nongr Massom, (commune of Kadiogo province). The trace metal el</span></span><span style="font-family:Verdana;">ements were analyzed using atomic absorption spectrophotometry, the isotopes 15N (</span></span><span style="font-family:Verdana;">NO<sub>2</sub><sup style="margin-left:-7px;">-</sup></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> NO<sub>3</sub><sup style="margin-left:-7px;">-</sup></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> NH<sub>4</sub><sup style="margin-left:-7px;">+</sup></span><span style="font-family:Verdana;">) and phosphorus (</span><span style="font-family:Verdana;">PO<sub>4</sub><sup style="margin-left:-7px;">3-</sup></span><span style="font-family:Verdana;">) using standardized methods. Tomatoes from conventional agriculture had higher levels of trace metal elements (0.163</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:Verdana;">0.298 mg/Kg, 0.082</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">0.146 mg/Kg </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> 0.018</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">0.032 mg/Kg respectively for Pb, Cd </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> As) than those from organic agriculture samples. </span><span style="font-family:Verdana;">Concentration</span><span style="font-family:Verdana;"> of trace metal</span></span><span style="font-family:Verdana;"> is</span><span style="font-family:""><span style="font-family:Verdana;"> lower for organic production with a reduction of 19.02%, 19.69% </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> 20.77% for Pb, Cd </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> As respectively compared to conventional production. High levels were recorded for the Roma F1 variety. The concentrations of trace metal elements in organic production are lower than the codex standards (2010) while those in conventional production are higher. These results could be due to the use of chemical inputs that could </span><span style="font-family:Verdana;">have a negative impact on</span><span style="font-family:Verdana;"> the nutritional quality of these tomatoes. The concentration of trace metal elements in tomato fruits is strongly correlated by production method and less by the variety (genetic).展开更多
This article presents a review of the analytical relevance of trace metal speciation analysis, which must be considered in environmental and biophysicochemical systems for reliable and efficient assessment and monitor...This article presents a review of the analytical relevance of trace metal speciation analysis, which must be considered in environmental and biophysicochemical systems for reliable and efficient assessment and monitoring of trace metals. Examples are given of methodological approaches used for speciation analysis. An overview of speciation analysis in sediments, aquatic ecosystems and agrosystems is also presented.展开更多
Accumulation and releasing of trace metal elements on aluminum containing sediments of inner drinking water pipe is discussed,as studied from five variations effecting:raw water quality,chemical reagents,solution pH a...Accumulation and releasing of trace metal elements on aluminum containing sediments of inner drinking water pipe is discussed,as studied from five variations effecting:raw water quality,chemical reagents,solution pH and drinking water flow condition.In order to decrease the release of trace metal elements,and to ensure the pipe operation and human safety,water quality adjustment is suggested to avoid aluminum containing sediments formation in drinking distribution system.The maximum amounts of accumulation of common trace metal elements are given.Future trends of development in this field are also proposed.展开更多
The Doppler backscattering system has been widely used for turbulence measurements,and the microwave beam will be backscattered near the cut-off layer when the Brag condition is fulfilled.In tokamak,the ray-tracing co...The Doppler backscattering system has been widely used for turbulence measurements,and the microwave beam will be backscattered near the cut-off layer when the Brag condition is fulfilled.In tokamak,the ray-tracing code is used to obtain the radial position and perpendicular wave number of the scattering layer for turbulence velocity measurement and the WKB（Wentzel-Kramers-Brillouin） approximation should be satisfied for optical propagation.To calculate the backscattering location and wave number at the cut-off layer only,a single ray tracing in the cross section is enough,while for spatial and wave number resolution calculation,multiple rays reflecting the microwave beam size should be used.Considering the angle between the wave vector and the magnetic field,a three-dimension quasi-optical Gaussian ray tracing is sometimes needed.展开更多
The task to estimate all the parameters of an unknown quantum state, also called quantum state tomography, is essential for characterizing and controlling quantum systems. In this paper, we utilize observable time tra...The task to estimate all the parameters of an unknown quantum state, also called quantum state tomography, is essential for characterizing and controlling quantum systems. In this paper, we utilize observable time traces to identify the initial quantum state of a closed quantum system, based on the state space approach in the control theory. In the informationally complete scenario, we show that with a linear regression estimation (LRE), the mean squared error (MSE) scales as , where N is the resource number. In the informationally incomplete scenario, we introduce regularization LRE to perform the state tomography task. We employ PBH test to demonstrate that closed quantum systems with only one observable are informationally incomplete and propose using observables, where d is the dimension of the quantum state, for informational completeness. Numerical examples demonstrate the effectiveness of our method.展开更多
In this paper,a new method for simultaneous spectrophotometric analysis of multi- component with double-system was developed.The multivariate calibration method,principal component analysis-partial least squares(PCA-P...In this paper,a new method for simultaneous spectrophotometric analysis of multi- component with double-system was developed.The multivariate calibration method,principal component analysis-partial least squares(PCA-PLS),was described and applied to the processing of measurement data.A demonstration,simultaneous determination of cobalt,nickel,copper,zinc and iron with double-system(5-Br-PADAP and PAR as chromogenic chelate reagents,respectively) was given.The results showed that the method with douhle-system gave better precision than those with single system and MLR(in this paper,AKC method was selected)did not give satis- fied precision in any situation.展开更多
Linear minimum mean square error(MMSE)detection has been shown to achieve near-optimal performance for massive multiple-input multiple-output(MIMO)systems but inevitably involves complicated matrix inversion,which ent...Linear minimum mean square error(MMSE)detection has been shown to achieve near-optimal performance for massive multiple-input multiple-output(MIMO)systems but inevitably involves complicated matrix inversion,which entails high complexity.To avoid the exact matrix inversion,a considerable number of implicit and explicit approximate matrix inversion based detection methods is proposed.By combining the advantages of both the explicit and the implicit matrix inversion,this paper introduces a new low-complexity signal detection algorithm.Firstly,the relationship between implicit and explicit techniques is analyzed.Then,an enhanced Newton iteration method is introduced to realize an approximate MMSE detection for massive MIMO uplink systems.The proposed improved Newton iteration significantly reduces the complexity of conventional Newton iteration.However,its complexity is still high for higher iterations.Thus,it is applied only for first two iterations.For subsequent iterations,we propose a novel trace iterative method(TIM)based low-complexity algorithm,which has significantly lower complexity than higher Newton iterations.Convergence guarantees of the proposed detector are also provided.Numerical simulations verify that the proposed detector exhibits significant performance enhancement over recently reported iterative detectors and achieves close-to-MMSE performance while retaining the low-complexity advantage for systems with hundreds of antennas.展开更多
Household desalinated drinking water samples collected from outdoor points and from indoor consumption points at 99 locations representing more than 95% of the residential areas in Kuwait were analyzed for 25 trace el...Household desalinated drinking water samples collected from outdoor points and from indoor consumption points at 99 locations representing more than 95% of the residential areas in Kuwait were analyzed for 25 trace elements and water quality parameters. Only Al, Cr, Co, Cu, Fe, Pb, Ni, and Zn were found to be over-represented at the consumption point compared with the outdoor point, with wide variations among the sampling locations and elements. The highest increases were observed for Fe (135%) and Zn (123%), followed by Pb (69%), Co (58%), Cu (42%), Cr (31%), and Al (30%), and the lowest increase was observed for Ni (19%). In most cases, the increases in Cu, Fe, and Zn were inversely proportional to the conductivity and directly proportional to the Cl– concentration. In the outdoor samples, only Fe exceeded the US-EPA guideline (in 3% of the outdoor samples taken), whereas Fe, Pb, and Ni exceeded the US-EPA and WHO guidelines in 8.5%, 0.3%, and 1% of the indoor consumption point samples, respectively. Thus, leaching from household utilities may cause health concerns for consumers of drinking water in Kuwait. The increases in Fe were the highest in the summer (240%), and in this regard, Fe exhibited the greatest difference between summer and winter (the increase was 139% higher in the summer). The results of the present study may be useful for water production authorities and consumers in Kuwait and suggest the use of alternative new pipes with more resistant internal coatings and connecting techniques.展开更多
Numerous nanocarriers have been currently developed for intracellular delivery.The potential cytotoxicity of these very small inorganic nanocarriers has raised great consideration.Thus,it becomes of utmost importance ...Numerous nanocarriers have been currently developed for intracellular delivery.The potential cytotoxicity of these very small inorganic nanocarriers has raised great consideration.Thus,it becomes of utmost importance to conduct the intracellular trace of nanocarriers.Among many analytical techniques,surface enhanced Raman scattering(SERS)method is one of the current state-of-the-art techniques for cell visualization and trace.In this work,a novel stellate porous silica based gene delivery system has been designed for SERS trace purpose.A stellate porous silica nanoparticle modified with many small Au nanoparticles is designed to replace common metallic SERS tags.The results show that the designed system not only could deliver si RNA into cells for therapy,but also could realize SERS trace with high sensitivity and non-invasive features.The constructed delivery system has considerable potential to trace the dynamic gene delivery in living cells.展开更多
Supervisory control and fault diagnosis of hybrid systems need to have complete information about the discrete states transitions of the underling system. From this point of view, the hybrid system should be abstracte...Supervisory control and fault diagnosis of hybrid systems need to have complete information about the discrete states transitions of the underling system. From this point of view, the hybrid system should be abstracted to a Discrete Trace Transition System (DTTS) and represented by a discrete mode transition graph. In this paper an effective method is proposed for generating discrete mode transition graph of a hybrid system. This method can be used for a general class of industrial hybrid plants which are defined by Polyhedral Invariant Hybrid Automata (PIHA). In these automata there are no resetting maps, while invariant sets are defined by linear inequalities. Therefore, based on the continuity property of the state trajectories in a PIHA, the problem is reduced to finding possible transitions between all two adjacent discrete modes. In the presented method, the possibility and the direction of such transitions are detected only by computing the angle between the vector field and the normal vector of the switching surfaces. Thus, unlike the most other reachability methods, there is no need to solve differential equations and to do mapping computations. In addition, the proposed method, with some modifications can be applied for extracting Stochastic or Timed Discrete Trace Transition Systems.展开更多
The Lake Zowla-Aného lagoon hydro system, located on the southeast coast of Togo, is very exposed to metal contamination as it receives a huge amount of untreated domestic and industrial effluents from Aného...The Lake Zowla-Aného lagoon hydro system, located on the southeast coast of Togo, is very exposed to metal contamination as it receives a huge amount of untreated domestic and industrial effluents from Aného City and the phosphorite treatment plant at Kpémé. This study aims to assess the concentrations of seven heavy metals and their bioaccumulation status in soft tissues and shells of the mangrove oyster (<i>Crassostrea gasar</i>) collected from this aquatic environment. Samples were collected in January, April and July 2017 at two stations and analyzed using flame atomic absorption spectrophotometry. Results indicate that the waters are contaminated by Cd, Pb and Cr with average concentrations that are significantly above WHO standards. At both locations, the contents of the trace elements (except Cr) in oysters’ soft tissues were significantly higher than those in the shells. In the soft tissues, the concentration of Cr, Cu, Zn, As, Cd, Hg, and Pb ranged (in mg·kg<sup>-1</sup>) from 4.33 to 23.14, 93.4 to 366.7, 455.68 to 1384.15, 0.11 to 1.34, 16.42 to 62.6, 0.05 to 0.473 and 0.39 to 21.08, respectively. Furthermore, statistical analyses showed marked differences in mean concentrations between sampling time on the one hand, and between sampling locations on the other hand (p < 0.05). The highest metal concentrations were recorded in oysters collected in June at Zalivé whereas the lowest values were recorded in April at Zowla. Based on BCF results in the lagoon system, the oyster <i>C. gasar</i> can be used as a biomonitor of Zn, Cd, Cu and Hg exposure. Finally, the Cd, Pb, As, Zn and Cu concentrations in soft tissues and were found to be significantly higher than the permissible limit for human consumption according to WHO and FAO and thus pose a threat to human health.展开更多
The omnivorous fish species, <i>C. nigrodigitatus</i> feeds mainly on benthic organisms and may therefore consume contaminated food throughout its food web. This can lead to the bioaccumulation of contamin...The omnivorous fish species, <i>C. nigrodigitatus</i> feeds mainly on benthic organisms and may therefore consume contaminated food throughout its food web. This can lead to the bioaccumulation of contaminants such as trace elements in their tissues. However, fish consumption is a major pathway of human exposure to contaminants which may cause public health problems. The aim of the present study is to assess trace elements contamination in some species from the food web of <i>C. nigrodigitatus</i>. For this, 10 main food items of the silver catfish were collected at two sites from February to July 2017 and analyzed using an Atomic Absorption Spectrometer coupled with a hydride and cold vapour generator. The concentrations of trace elements varied greatly from one species to another and within each species. These values ranged from 0.007 mg/kg for Hg in C hippos to 354.84 mg/kg for Mn in <i>P. fusca</i>. The most contaminated species by trace elements were benthic organisms: <i>M. perna</i> (Cd, Pb, Hg), <i>Pagurus</i> sp. (Cr, Ni, Cu, Zn), <i>G. paradoxa</i> (As) and <i>P. fusca</i> (Mn). The average concentrations of trace elements found in species were, for the most part, above WHO standards except Hg in <i>M. perna</i> and <i>G. paradoxa</i>. The water-based bioconcentration factors (BCFw) reach 92.58 for Cd, 44.72 for Pb, 382.49 for Hg and 1514.34 for As in <i>M. perna</i>. It is therefore necessary to pay particular attention to this ecosystem and to put in place a better management plan.展开更多
It is of great importance to obtain precise trace data,as traces are frequently the sole visible and measurable parameter in most outcrops.The manual recognition and detection of traces on high-resolution three-dimens...It is of great importance to obtain precise trace data,as traces are frequently the sole visible and measurable parameter in most outcrops.The manual recognition and detection of traces on high-resolution three-dimensional(3D)models are relatively straightforward but time-consuming.One potential solution to enhance this process is to use machine learning algorithms to detect the 3D traces.In this study,a unique pixel-wise texture mapper algorithm generates a dense point cloud representation of an outcrop with the precise resolution of the original textured 3D model.A virtual digital image rendering was then employed to capture virtual images of selected regions.This technique helps to overcome limitations caused by the surface morphology of the rock mass,such as restricted access,lighting conditions,and shading effects.After AI-powered trace detection on two-dimensional(2D)images,a 3D data structuring technique was applied to the selected trace pixels.In the 3D data structuring,the trace data were structured through 2D thinning,3D reprojection,clustering,segmentation,and segment linking.Finally,the linked segments were exported as 3D polylines,with each polyline in the output corresponding to a trace.The efficacy of the proposed method was assessed using a 3D model of a real-world case study,which was used to compare the results of artificial intelligence(AI)-aided and human intelligence trace detection.Rosette diagrams,which visualize the distribution of trace orientations,confirmed the high similarity between the automatically and manually generated trace maps.In conclusion,the proposed semi-automatic method was easy to use,fast,and accurate in detecting the dominant jointing system of the rock mass.展开更多
基金supported by the National Natural Science Foundation of China(Nos.62104045,52101213)Jiangsu Provincial Department of Science and Technology of China(No.BE2022426).
文摘As the chemical industry expands,the use of benzene,toluene,and xylene(collectively known as BTX)in industrial production has increased greatly.Meanwhile,the toxic nature and potential health hazards of BTX gases cannot be ignored due to low-concentration leaks underline the critical need for rapid and real-time monitoring of these gases.Chemiresistive metal oxide semiconductor(MOS)-based gas sensors,which are extensively used for gas detection in both industrial settings and everyday life,emerge as one of the optimal solutions for trace BTX detection.These sensors are highly valued for their high sensitivity and low detection limits.Nevertheless,the improvement of selectivity towards specific BTX gases to achieve efficient and precise detection still remains challenging.This review summarizes the chemiresistive MOS-based gas sensors designed for BTX detection,categorizing them based on the components of sensing materials-basically into three groups:single-component,single heterojunction,and multiple heterojunctions gas sensing materials.Further,the review proposes the future application prospects of chemiresistive MOS-based BTX gas sensors,with specific emphasis on their significance in promoting industrial safety and environmental monitoring.
基金supported by the Universiti Tunku Abdul Rahman under Universiti Research Grant(No.IPSR/RMC/UTARRF/C1-13/G03)
文摘The study of trace metals in the atmosphere and lake water is important due to their critical effects on humans, aquatic animals and the geochemical balance of ecosystems. The objective of this study was to investigate the concentration of trace metals in atmospheric and lake water samples during the rainy season （before and after precipitation） between November and December 2015. Typical methods of sample preparation for trace metal determination such as cloud point extraction, solid phase extraction and dispersive liquid- liquid micro-extraction are time-consuming and difficult to perform; therefore, there is a crucial need for development of more effective sample preparation procedure. A convection microwave assisted digestion procedure for extraction of trace metals was developed for use prior to inductively couple plasma-mass spectrometric determination. The result showed that metals like zinc （133.50-419.30 μg/m3） and aluminum （53.58-378.93 μg/m3） had higher concentrations in atmospheric samples as compared to lake samples before precipitation. On the other hand, the concentrations of zinc, aluminum, chromium and arsenic were significantly higher in lake samples after precipitation and lower in atmospheric samples. The relationship between physicochemical parameters （pH and turbidity） and heavy metal concentrations was investigated as well. Furthermore, enrichment factor analysis indicated that anthropogenic sources such as soil dust, biomass burning and fuel combustion influenced the metal concentrations in the atmosphere.
基金supported by the National Natural Science Foundation of China(1137100311461006)+4 种基金the Natural Science Foundation of Guangxi(2011GXNSFA0181542012GXNSFGA060003)the Science and Technology Foundation of Guangxi(10169-1)the Scientific Research Project from Guangxi Education Department(201012MS274)Open Research Fund Program of Guangxi Key Laboratory of Hybrid Computation and IC Design Analysis(HCIC201301)
文摘Established system equivalences for transition systems, such as trace equivalence and failures equivalence, require the ob- servations to be exactly identical. However, an accurate measure- ment is impossible when interacting with the physical world, hence exact equivalence is restrictive and not robust. Using Baire met- ric, a generalized framework of transition system approximation is proposed by developing the notions of approximate language equivalence and approximate singleton failures （SF） equivalence. The framework takes the traditional exact equivalence as a special case. The approximate language equivalence is coarser than the approximate Slc equivalence, just like the hierarchy of the exact ones. The main conclusion is that the two approximate equiva- lences satisfy the transitive property, consequently, they can be successively used in transition system approximation.
文摘Tomato is a market gardening product that plays an important nutritional and economic role in Burkina Faso. However, the bad use of pesticides for its production could have negative impacts </span><span style="font-family:Verdana;">consumers’</span><span style="font-family:Verdana;"> health. The objective of the present study was to assess the concentration of trace metal elements (Pb, Cd </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> As), 15N isotopes (</span></span><span style="font-family:Verdana;">NO<sub>2</sub><sup style="margin-left:-7px;">-</sup></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> NO<sub>3</sub><sup style="margin-left:-7px;">-</sup></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> NH<sub>4</sub><sup style="margin-left:-7px;">+</sup></span><span style="font-family:Verdana;">) and phosphorus (</span><span style="font-family:Verdana;">PO<sub>4</sub><sup style="margin-left:-7px;">2-</sup></span><span style="font-family:""><span style="font-family:Verdana;">) in tomatoes according to cultivation practices. Thus, three tomato varieties (Mon</span><span><span style="font-family:Verdana;">gal F1, F1 Cobra 26 </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> Roma F1) were grown using organic and conventional production methods on 2 sites at Nongr Massom, (commune of Kadiogo province). The trace metal el</span></span><span style="font-family:Verdana;">ements were analyzed using atomic absorption spectrophotometry, the isotopes 15N (</span></span><span style="font-family:Verdana;">NO<sub>2</sub><sup style="margin-left:-7px;">-</sup></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> NO<sub>3</sub><sup style="margin-left:-7px;">-</sup></span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> NH<sub>4</sub><sup style="margin-left:-7px;">+</sup></span><span style="font-family:Verdana;">) and phosphorus (</span><span style="font-family:Verdana;">PO<sub>4</sub><sup style="margin-left:-7px;">3-</sup></span><span style="font-family:Verdana;">) using standardized methods. Tomatoes from conventional agriculture had higher levels of trace metal elements (0.163</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:Verdana;">0.298 mg/Kg, 0.082</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">0.146 mg/Kg </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> 0.018</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">0.032 mg/Kg respectively for Pb, Cd </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> As) than those from organic agriculture samples. </span><span style="font-family:Verdana;">Concentration</span><span style="font-family:Verdana;"> of trace metal</span></span><span style="font-family:Verdana;"> is</span><span style="font-family:""><span style="font-family:Verdana;"> lower for organic production with a reduction of 19.02%, 19.69% </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> 20.77% for Pb, Cd </span><span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> As respectively compared to conventional production. High levels were recorded for the Roma F1 variety. The concentrations of trace metal elements in organic production are lower than the codex standards (2010) while those in conventional production are higher. These results could be due to the use of chemical inputs that could </span><span style="font-family:Verdana;">have a negative impact on</span><span style="font-family:Verdana;"> the nutritional quality of these tomatoes. The concentration of trace metal elements in tomato fruits is strongly correlated by production method and less by the variety (genetic).
文摘This article presents a review of the analytical relevance of trace metal speciation analysis, which must be considered in environmental and biophysicochemical systems for reliable and efficient assessment and monitoring of trace metals. Examples are given of methodological approaches used for speciation analysis. An overview of speciation analysis in sediments, aquatic ecosystems and agrosystems is also presented.
基金This work was supported by City Collage of Science and Technology.Chongqing University and Chongqing HaiRun institute of energy saving research。
文摘Accumulation and releasing of trace metal elements on aluminum containing sediments of inner drinking water pipe is discussed,as studied from five variations effecting:raw water quality,chemical reagents,solution pH and drinking water flow condition.In order to decrease the release of trace metal elements,and to ensure the pipe operation and human safety,water quality adjustment is suggested to avoid aluminum containing sediments formation in drinking distribution system.The maximum amounts of accumulation of common trace metal elements are given.Future trends of development in this field are also proposed.
基金supported by National Natural Science Foundation of China(Nos.10990211 and 11105146)the ITER-CN Project973 Program of China(No.2013GB106002)
文摘The Doppler backscattering system has been widely used for turbulence measurements,and the microwave beam will be backscattered near the cut-off layer when the Brag condition is fulfilled.In tokamak,the ray-tracing code is used to obtain the radial position and perpendicular wave number of the scattering layer for turbulence velocity measurement and the WKB（Wentzel-Kramers-Brillouin） approximation should be satisfied for optical propagation.To calculate the backscattering location and wave number at the cut-off layer only,a single ray tracing in the cross section is enough,while for spatial and wave number resolution calculation,multiple rays reflecting the microwave beam size should be used.Considering the angle between the wave vector and the magnetic field,a three-dimension quasi-optical Gaussian ray tracing is sometimes needed.
基金supported by the National Natural Science Foundation of China(Nos.62173229,12288201)the Australian Research Council Future Fellowship Funding Scheme under Project FT220100656 and the Discovery Project Funding Scheme under Project DP210101938.
文摘The task to estimate all the parameters of an unknown quantum state, also called quantum state tomography, is essential for characterizing and controlling quantum systems. In this paper, we utilize observable time traces to identify the initial quantum state of a closed quantum system, based on the state space approach in the control theory. In the informationally complete scenario, we show that with a linear regression estimation (LRE), the mean squared error (MSE) scales as , where N is the resource number. In the informationally incomplete scenario, we introduce regularization LRE to perform the state tomography task. We employ PBH test to demonstrate that closed quantum systems with only one observable are informationally incomplete and propose using observables, where d is the dimension of the quantum state, for informational completeness. Numerical examples demonstrate the effectiveness of our method.
基金This project was supported by the Natural Science Foundation of Jiangxi Province
文摘In this paper,a new method for simultaneous spectrophotometric analysis of multi- component with double-system was developed.The multivariate calibration method,principal component analysis-partial least squares(PCA-PLS),was described and applied to the processing of measurement data.A demonstration,simultaneous determination of cobalt,nickel,copper,zinc and iron with double-system(5-Br-PADAP and PAR as chromogenic chelate reagents,respectively) was given.The results showed that the method with douhle-system gave better precision than those with single system and MLR(in this paper,AKC method was selected)did not give satis- fied precision in any situation.
基金supported by National Natural Science Foundation of China(62371225,62371227)。
文摘Linear minimum mean square error(MMSE)detection has been shown to achieve near-optimal performance for massive multiple-input multiple-output(MIMO)systems but inevitably involves complicated matrix inversion,which entails high complexity.To avoid the exact matrix inversion,a considerable number of implicit and explicit approximate matrix inversion based detection methods is proposed.By combining the advantages of both the explicit and the implicit matrix inversion,this paper introduces a new low-complexity signal detection algorithm.Firstly,the relationship between implicit and explicit techniques is analyzed.Then,an enhanced Newton iteration method is introduced to realize an approximate MMSE detection for massive MIMO uplink systems.The proposed improved Newton iteration significantly reduces the complexity of conventional Newton iteration.However,its complexity is still high for higher iterations.Thus,it is applied only for first two iterations.For subsequent iterations,we propose a novel trace iterative method(TIM)based low-complexity algorithm,which has significantly lower complexity than higher Newton iterations.Convergence guarantees of the proposed detector are also provided.Numerical simulations verify that the proposed detector exhibits significant performance enhancement over recently reported iterative detectors and achieves close-to-MMSE performance while retaining the low-complexity advantage for systems with hundreds of antennas.
文摘Household desalinated drinking water samples collected from outdoor points and from indoor consumption points at 99 locations representing more than 95% of the residential areas in Kuwait were analyzed for 25 trace elements and water quality parameters. Only Al, Cr, Co, Cu, Fe, Pb, Ni, and Zn were found to be over-represented at the consumption point compared with the outdoor point, with wide variations among the sampling locations and elements. The highest increases were observed for Fe (135%) and Zn (123%), followed by Pb (69%), Co (58%), Cu (42%), Cr (31%), and Al (30%), and the lowest increase was observed for Ni (19%). In most cases, the increases in Cu, Fe, and Zn were inversely proportional to the conductivity and directly proportional to the Cl– concentration. In the outdoor samples, only Fe exceeded the US-EPA guideline (in 3% of the outdoor samples taken), whereas Fe, Pb, and Ni exceeded the US-EPA and WHO guidelines in 8.5%, 0.3%, and 1% of the indoor consumption point samples, respectively. Thus, leaching from household utilities may cause health concerns for consumers of drinking water in Kuwait. The increases in Fe were the highest in the summer (240%), and in this regard, Fe exhibited the greatest difference between summer and winter (the increase was 139% higher in the summer). The results of the present study may be useful for water production authorities and consumers in Kuwait and suggest the use of alternative new pipes with more resistant internal coatings and connecting techniques.
基金financially supported by the Australian Research Council(ARC)Discovery Projects(Nos.DP140104062 and DP160104866)Fundamental Research Funds for the Central Universities(Nos.FRF-TP-19-017B1,2302015-06500017,FRF-BR-19-003B,FRF-BD-20-14A)National Natural Science Foundation of China(No.21501009)。
文摘Numerous nanocarriers have been currently developed for intracellular delivery.The potential cytotoxicity of these very small inorganic nanocarriers has raised great consideration.Thus,it becomes of utmost importance to conduct the intracellular trace of nanocarriers.Among many analytical techniques,surface enhanced Raman scattering(SERS)method is one of the current state-of-the-art techniques for cell visualization and trace.In this work,a novel stellate porous silica based gene delivery system has been designed for SERS trace purpose.A stellate porous silica nanoparticle modified with many small Au nanoparticles is designed to replace common metallic SERS tags.The results show that the designed system not only could deliver si RNA into cells for therapy,but also could realize SERS trace with high sensitivity and non-invasive features.The constructed delivery system has considerable potential to trace the dynamic gene delivery in living cells.
文摘Supervisory control and fault diagnosis of hybrid systems need to have complete information about the discrete states transitions of the underling system. From this point of view, the hybrid system should be abstracted to a Discrete Trace Transition System (DTTS) and represented by a discrete mode transition graph. In this paper an effective method is proposed for generating discrete mode transition graph of a hybrid system. This method can be used for a general class of industrial hybrid plants which are defined by Polyhedral Invariant Hybrid Automata (PIHA). In these automata there are no resetting maps, while invariant sets are defined by linear inequalities. Therefore, based on the continuity property of the state trajectories in a PIHA, the problem is reduced to finding possible transitions between all two adjacent discrete modes. In the presented method, the possibility and the direction of such transitions are detected only by computing the angle between the vector field and the normal vector of the switching surfaces. Thus, unlike the most other reachability methods, there is no need to solve differential equations and to do mapping computations. In addition, the proposed method, with some modifications can be applied for extracting Stochastic or Timed Discrete Trace Transition Systems.
文摘The Lake Zowla-Aného lagoon hydro system, located on the southeast coast of Togo, is very exposed to metal contamination as it receives a huge amount of untreated domestic and industrial effluents from Aného City and the phosphorite treatment plant at Kpémé. This study aims to assess the concentrations of seven heavy metals and their bioaccumulation status in soft tissues and shells of the mangrove oyster (<i>Crassostrea gasar</i>) collected from this aquatic environment. Samples were collected in January, April and July 2017 at two stations and analyzed using flame atomic absorption spectrophotometry. Results indicate that the waters are contaminated by Cd, Pb and Cr with average concentrations that are significantly above WHO standards. At both locations, the contents of the trace elements (except Cr) in oysters’ soft tissues were significantly higher than those in the shells. In the soft tissues, the concentration of Cr, Cu, Zn, As, Cd, Hg, and Pb ranged (in mg·kg<sup>-1</sup>) from 4.33 to 23.14, 93.4 to 366.7, 455.68 to 1384.15, 0.11 to 1.34, 16.42 to 62.6, 0.05 to 0.473 and 0.39 to 21.08, respectively. Furthermore, statistical analyses showed marked differences in mean concentrations between sampling time on the one hand, and between sampling locations on the other hand (p < 0.05). The highest metal concentrations were recorded in oysters collected in June at Zalivé whereas the lowest values were recorded in April at Zowla. Based on BCF results in the lagoon system, the oyster <i>C. gasar</i> can be used as a biomonitor of Zn, Cd, Cu and Hg exposure. Finally, the Cd, Pb, As, Zn and Cu concentrations in soft tissues and were found to be significantly higher than the permissible limit for human consumption according to WHO and FAO and thus pose a threat to human health.
文摘The omnivorous fish species, <i>C. nigrodigitatus</i> feeds mainly on benthic organisms and may therefore consume contaminated food throughout its food web. This can lead to the bioaccumulation of contaminants such as trace elements in their tissues. However, fish consumption is a major pathway of human exposure to contaminants which may cause public health problems. The aim of the present study is to assess trace elements contamination in some species from the food web of <i>C. nigrodigitatus</i>. For this, 10 main food items of the silver catfish were collected at two sites from February to July 2017 and analyzed using an Atomic Absorption Spectrometer coupled with a hydride and cold vapour generator. The concentrations of trace elements varied greatly from one species to another and within each species. These values ranged from 0.007 mg/kg for Hg in C hippos to 354.84 mg/kg for Mn in <i>P. fusca</i>. The most contaminated species by trace elements were benthic organisms: <i>M. perna</i> (Cd, Pb, Hg), <i>Pagurus</i> sp. (Cr, Ni, Cu, Zn), <i>G. paradoxa</i> (As) and <i>P. fusca</i> (Mn). The average concentrations of trace elements found in species were, for the most part, above WHO standards except Hg in <i>M. perna</i> and <i>G. paradoxa</i>. The water-based bioconcentration factors (BCFw) reach 92.58 for Cd, 44.72 for Pb, 382.49 for Hg and 1514.34 for As in <i>M. perna</i>. It is therefore necessary to pay particular attention to this ecosystem and to put in place a better management plan.
基金supported by grants from the Human Resources Development program (Grant No.20204010600250)the Training Program of CCUS for the Green Growth (Grant No.20214000000500)by the Korea Institute of Energy Technology Evaluation and Planning (KETEP)funded by the Ministry of Trade,Industry,and Energy of the Korean Government (MOTIE).
文摘It is of great importance to obtain precise trace data,as traces are frequently the sole visible and measurable parameter in most outcrops.The manual recognition and detection of traces on high-resolution three-dimensional(3D)models are relatively straightforward but time-consuming.One potential solution to enhance this process is to use machine learning algorithms to detect the 3D traces.In this study,a unique pixel-wise texture mapper algorithm generates a dense point cloud representation of an outcrop with the precise resolution of the original textured 3D model.A virtual digital image rendering was then employed to capture virtual images of selected regions.This technique helps to overcome limitations caused by the surface morphology of the rock mass,such as restricted access,lighting conditions,and shading effects.After AI-powered trace detection on two-dimensional(2D)images,a 3D data structuring technique was applied to the selected trace pixels.In the 3D data structuring,the trace data were structured through 2D thinning,3D reprojection,clustering,segmentation,and segment linking.Finally,the linked segments were exported as 3D polylines,with each polyline in the output corresponding to a trace.The efficacy of the proposed method was assessed using a 3D model of a real-world case study,which was used to compare the results of artificial intelligence(AI)-aided and human intelligence trace detection.Rosette diagrams,which visualize the distribution of trace orientations,confirmed the high similarity between the automatically and manually generated trace maps.In conclusion,the proposed semi-automatic method was easy to use,fast,and accurate in detecting the dominant jointing system of the rock mass.
