Matrix effect primarily impacts the accuracy and precision of zircon LA-ICP-MS U-Pb data.This paper describes three types of matrix effect in zircon LA-ICPMS U-Pb dating,i.e.,the element matrix effect,high Ddpa or ura...Matrix effect primarily impacts the accuracy and precision of zircon LA-ICP-MS U-Pb data.This paper describes three types of matrix effect in zircon LA-ICPMS U-Pb dating,i.e.,the element matrix effect,high Ddpa or uranium matrix effect and alpha dose matrix effect,and illustrates the correction of these three effects.In addition,we point out the limitation and possible problems of the existing correction methods.展开更多
Garnet occurs in a wide range of rock types,from mantle peridotites to granites,from eclogites to skarns.In recent years,garnet LA-ICP-MS(Laser Ablation Inductively Coupled Plasma Mass Spectrometry)U-Pb dating has pro...Garnet occurs in a wide range of rock types,from mantle peridotites to granites,from eclogites to skarns.In recent years,garnet LA-ICP-MS(Laser Ablation Inductively Coupled Plasma Mass Spectrometry)U-Pb dating has provided a powerful solution for retrieving the ages of rock formations,but successful dating is often prohibited by the low concentration of U.However,the concentration of U,a trace element of garnet,is unknown prior to the LA-ICP-MS analysis.In this study,we propose that the U concentration in garnet can be predicted by the contents of major and minor elements,which can be quantitatively obtained by EPMA(electron probe microanalysis).Using a supervised machine learning method(neural network),a model is trained to discriminate U-rich(>2 ppm)and U-poor(<2 ppm)garnets,based on EPMA results.Results of cross validation shows that the model has an average accuracy of~92%and is a powerful tool in detecting datable U-rich garnet.To facilitate the use of the discriminator,it is programmed as a stand-alone Microsoft Excel spreadsheet(HighUGarnet)and users directly paste the molar proportions of garnet end members into it and obtain the discrimination result.展开更多
Laser ablation coupled with inductively coupled plasma-mass spectrometry (LA-ICP-MS) calibration was conducted with multiple spot analyses on eleven intact rock samples using both an internal standard (IS) method and ...Laser ablation coupled with inductively coupled plasma-mass spectrometry (LA-ICP-MS) calibration was conducted with multiple spot analyses on eleven intact rock samples using both an internal standard (IS) method and a modified constant-sum (MCS) method. Methods were then compared for reported bulk elemental composition of the rocks. The MCS method was based on the sum of eight major elements, which is spatially more stable than one single major ele-ment as used in the IS method, and is quite constant among different rock samples. Calibrations were performed with standard reference materials NIST SRM 610, 612, 614, and 616. Little difference was found between using a single standard and a set of standards, because of the good linearity shown by the reference materials. Comparison of the two calibration methods shows that the MCS method produced better and more stable results than the IS method for heterogeneous samples. With the MCS method, approximately 94% to 95% of the total measurements are within the range of ±100% relative deviation, compared with 82% to 86% with the IS method. The IS method resulted insubstantial overestimations for some rock samples (e.g., 648% for Basalt BCR-2 using NIST SRM 610 as the calibration standard), while the largest deviation with the MCS method was 216% for U in Eagle Ford shale #80 sample. For Quartz latite QLO-1, a relative homogeneous sample, the IS method generated slightly better results than the MCS method. Regardless of method, spatially heterogeneous distribution of elements in the intact rock at the scale of the laser spot is considered to be the main reason for the large relative deviations seen in our work compared to published results.展开更多
The interaction between nanoparticles (NPs) and pollutants affects their bioavailability and toxicity.However,the processes by which NPs and pollutants change in vivo have rarely been explored.Here,using laser ablatio...The interaction between nanoparticles (NPs) and pollutants affects their bioavailability and toxicity.However,the processes by which NPs and pollutants change in vivo have rarely been explored.Here,using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS),we found that both nanoplastics and ZnO NPs caused more Cd to accumulate in zebrafish larvae,but with distinct pathways.Nanoplastics could adsorb Cd^(2+) and transfer it into the larvae through the“Trojan horse”effect.The coexposure of nanoplastics and Cd^(2+) caused Cd to accumulate in the abdomen where the nanoplastics were located without dissociation,showing a lower toxic effect than Cd^(2+) exposure alone.ZnO NPs weakly adsorbed Cd^(2+),but they increased the Zn and Cd contents in larvae by enhancing the expression of metal transporters.The coexposure of ZnO and Cd^(2+) evenly distributed Cd in the larvae,revealing a more severe toxic effect than Cd^(2+) exposure alone.Our results demonstrated the changing bioavailability and toxicity of Cd induced by different NPs.This also shows the vital role LA-ICP-MS plays in revealing the relationship between toxicity and bioavailability.In addition,the long-term effect of bioavailability on heavy metal toxicity and nanosafety deserves further investigation.展开更多
In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to ...In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.展开更多
Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The t...Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The traditional thermal elastic-plastic finite element method(TEP-FEM)can accurately predict welding deformation.However,its efficiency is low because of the complex nonlinear transient computation,making it difficult to meet the needs of rapid engineering evaluation.To address this challenge,this study proposes an efficient prediction method for welding deformation in marine thin plate butt welds.This method is based on the coupled temperature gradient-thermal strain method(TG-TSM)that integrates inherent strain theory with a shell element finite element model.The proposed method first extracts the distribution pattern and characteristic value of welding-induced inherent strain through TEP-FEM analysis.This strain is then converted into the equivalent thermal load applied to the shell element model for rapid computation.The proposed method-particularly,the gradual temperature gradient-thermal strain method(GTG-TSM)-achieved improved computational efficiency and consistent precision.Furthermore,the proposed method required much less computation time than the traditional TEP-FEM.Thus,this study lays the foundation for future prediction of welding deformation in more complex marine thin plates.展开更多
文摘Matrix effect primarily impacts the accuracy and precision of zircon LA-ICP-MS U-Pb data.This paper describes three types of matrix effect in zircon LA-ICPMS U-Pb dating,i.e.,the element matrix effect,high Ddpa or uranium matrix effect and alpha dose matrix effect,and illustrates the correction of these three effects.In addition,we point out the limitation and possible problems of the existing correction methods.
基金financially supported by the National Natural Science Foundation of China(Nos.41872078 and 41502069)the Young Elite Scientists Sponsorship Program by CAST(No.YESS20180143)+1 种基金Fundamental Research Funds for the Central Universities(No.FRF-TP-18-017A3)the 111 Project of the Ministry of Science and Technology,China(No.BPO719021).
文摘Garnet occurs in a wide range of rock types,from mantle peridotites to granites,from eclogites to skarns.In recent years,garnet LA-ICP-MS(Laser Ablation Inductively Coupled Plasma Mass Spectrometry)U-Pb dating has provided a powerful solution for retrieving the ages of rock formations,but successful dating is often prohibited by the low concentration of U.However,the concentration of U,a trace element of garnet,is unknown prior to the LA-ICP-MS analysis.In this study,we propose that the U concentration in garnet can be predicted by the contents of major and minor elements,which can be quantitatively obtained by EPMA(electron probe microanalysis).Using a supervised machine learning method(neural network),a model is trained to discriminate U-rich(>2 ppm)and U-poor(<2 ppm)garnets,based on EPMA results.Results of cross validation shows that the model has an average accuracy of~92%and is a powerful tool in detecting datable U-rich garnet.To facilitate the use of the discriminator,it is programmed as a stand-alone Microsoft Excel spreadsheet(HighUGarnet)and users directly paste the molar proportions of garnet end members into it and obtain the discrimination result.
文摘Laser ablation coupled with inductively coupled plasma-mass spectrometry (LA-ICP-MS) calibration was conducted with multiple spot analyses on eleven intact rock samples using both an internal standard (IS) method and a modified constant-sum (MCS) method. Methods were then compared for reported bulk elemental composition of the rocks. The MCS method was based on the sum of eight major elements, which is spatially more stable than one single major ele-ment as used in the IS method, and is quite constant among different rock samples. Calibrations were performed with standard reference materials NIST SRM 610, 612, 614, and 616. Little difference was found between using a single standard and a set of standards, because of the good linearity shown by the reference materials. Comparison of the two calibration methods shows that the MCS method produced better and more stable results than the IS method for heterogeneous samples. With the MCS method, approximately 94% to 95% of the total measurements are within the range of ±100% relative deviation, compared with 82% to 86% with the IS method. The IS method resulted insubstantial overestimations for some rock samples (e.g., 648% for Basalt BCR-2 using NIST SRM 610 as the calibration standard), while the largest deviation with the MCS method was 216% for U in Eagle Ford shale #80 sample. For Quartz latite QLO-1, a relative homogeneous sample, the IS method generated slightly better results than the MCS method. Regardless of method, spatially heterogeneous distribution of elements in the intact rock at the scale of the laser spot is considered to be the main reason for the large relative deviations seen in our work compared to published results.
基金financially supported by the National Natural Science Foundation of China(NSFC,Nos.22174103 and 21575107)。
文摘The interaction between nanoparticles (NPs) and pollutants affects their bioavailability and toxicity.However,the processes by which NPs and pollutants change in vivo have rarely been explored.Here,using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS),we found that both nanoplastics and ZnO NPs caused more Cd to accumulate in zebrafish larvae,but with distinct pathways.Nanoplastics could adsorb Cd^(2+) and transfer it into the larvae through the“Trojan horse”effect.The coexposure of nanoplastics and Cd^(2+) caused Cd to accumulate in the abdomen where the nanoplastics were located without dissociation,showing a lower toxic effect than Cd^(2+) exposure alone.ZnO NPs weakly adsorbed Cd^(2+),but they increased the Zn and Cd contents in larvae by enhancing the expression of metal transporters.The coexposure of ZnO and Cd^(2+) evenly distributed Cd in the larvae,revealing a more severe toxic effect than Cd^(2+) exposure alone.Our results demonstrated the changing bioavailability and toxicity of Cd induced by different NPs.This also shows the vital role LA-ICP-MS plays in revealing the relationship between toxicity and bioavailability.In addition,the long-term effect of bioavailability on heavy metal toxicity and nanosafety deserves further investigation.
基金Supported in part by Natural Science Foundation of Guangxi(2023GXNSFAA026246)in part by the Central Government's Guide to Local Science and Technology Development Fund(GuikeZY23055044)in part by the National Natural Science Foundation of China(62363003)。
文摘In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.
基金Supported by the National Natural Science Foundation of China under Grant No.51975138the High-Tech Ship Scientific Research Project from the Ministry of Industry and Information Technology under Grant No.CJ05N20the National Defense Basic Research Project under Grant No.JCKY2023604C006.
文摘Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The traditional thermal elastic-plastic finite element method(TEP-FEM)can accurately predict welding deformation.However,its efficiency is low because of the complex nonlinear transient computation,making it difficult to meet the needs of rapid engineering evaluation.To address this challenge,this study proposes an efficient prediction method for welding deformation in marine thin plate butt welds.This method is based on the coupled temperature gradient-thermal strain method(TG-TSM)that integrates inherent strain theory with a shell element finite element model.The proposed method first extracts the distribution pattern and characteristic value of welding-induced inherent strain through TEP-FEM analysis.This strain is then converted into the equivalent thermal load applied to the shell element model for rapid computation.The proposed method-particularly,the gradual temperature gradient-thermal strain method(GTG-TSM)-achieved improved computational efficiency and consistent precision.Furthermore,the proposed method required much less computation time than the traditional TEP-FEM.Thus,this study lays the foundation for future prediction of welding deformation in more complex marine thin plates.
