An integral constitutive equation and a set of material functions for describing the strain history of polymer melts were formulated in terms of the Cauchy-Green and Finger tensors. A simple memory function and the de...An integral constitutive equation and a set of material functions for describing the strain history of polymer melts were formulated in terms of the Cauchy-Green and Finger tensors. A simple memory function and the dependence of ηo and τt on M3.4 were derived from the theory of non-linear viscoelasticity with constraints of entanglements for polymer melts and substituted into the Oldroye-Walters-Fredickson constitutive equation. An integral constitutive equation for polymer melts was consequently obtained. Some material functions of the constitutive equation related to certain 'test flow' are examined as follows : (1) simple steady shear flow; (2) steady elongation flow; (3) small-amplitude oscillatory shear flow; (4) stress growth upon the inception of steady shear elongation flow; (5) stress relaxation (modulus and compllance). These theoretical relations for simple steady shear flow were compared with experimental data from our laboratory and references for various polymer melts and concentrated solutions. A good agreement between the theory and experiment was achieved.展开更多
A novel technique of Moveable Reduction Bed Hydride Generator（MRBHG）was applied tohe hydride generation or cold vapor generation of As，Se，Ge，and Hg existing In TraditionalChinese Medicinal Material（TCM）．The si...A novel technique of Moveable Reduction Bed Hydride Generator（MRBHG）was applied tohe hydride generation or cold vapor generation of As，Se，Ge，and Hg existing In TraditionalChinese Medicinal Material（TCM）．The simultaneous determination of the multi－elements wasperformed with ICP－MS．A solid reduction system involving the use of potassiumtetraborohydride and tartaric acid was applied to generating metal hydride or cold vaporefficiently．The factors affecting the metal cold vapor generation were studied．The mainadvantage of the technique is that only a 4μL volume of sample was required for the cold vapor展开更多
The experiment regarding material determination of a vehicle part was conducted.The experiment on stamping production of a part using the steels A,B and C was made.The strain data on the deformed parts were measured.T...The experiment regarding material determination of a vehicle part was conducted.The experiment on stamping production of a part using the steels A,B and C was made.The strain data on the deformed parts were measured.The forming limit diagrams for the steels were examined and evaluated.The results show that three steels are unsuitable for this stamping part.The desired material properties with an optimal strain hardening exponent value were determined using experimental and analytical methods.The steel D was chosen as a desired material.The results show that the steel D is appropriate for mass production.In addition,the feasibility of the application of thinner material to this part was studied.The validity of the material selection was verified theoretically and experimentally.展开更多
The composition, microstructure, mechanical and frictional properties of PTFE and its fillers were represented and analyzed by XRD, SEM, DSC, XPS and large-scale polarizing microscope. The results show that PTFE has a...The composition, microstructure, mechanical and frictional properties of PTFE and its fillers were represented and analyzed by XRD, SEM, DSC, XPS and large-scale polarizing microscope. The results show that PTFE has a flocculent structure with high melt temperature and decomposition temperature, big contact angle and crystallinity, and low surface hardness, compression strength, friction coefficient, wearing capacity and surface energy. Cooling rate influenced the friction coefficient and wear resistance. Graphite and molybdenum disulfide have a flake structure, and molybdenum disulfide has a big contact angle and low surface energy. Copper powder has a globular structure and its chief component is Cu-Pb alloy, and there is a loose layer on the surface. Carbon fiber has a rod structure and there are C=O and C-O-C polar groups on the skeleton surface. The decreasing order of water absorption capacity is graphite, carbon fiber, molybdenum disulfide, PTFE and copper powder.展开更多
This paper introduces the ceramic materials fusion method to use porcelain crucible instead of platinum crucible. By this method, not only the funds can be saved, but also the operation becomes simple and the analysed...This paper introduces the ceramic materials fusion method to use porcelain crucible instead of platinum crucible. By this method, not only the funds can be saved, but also the operation becomes simple and the analysed results are accurate and reliable. On the other hand, the high fusion point materials, such as high aluminum ceramic raw ma- terials, can also be melted and their aluminum contents can be determined by this method. Thus, it can be widely used in the students laboratory and routine analysis of small and middle industrial enterprises.展开更多
A promising electrochemical sensor based on PANI/AgCl hybrid material has been developed. The organic/inorganic hybrid material has exhibited good electrocatalytic properties by cyclic voltammetry measurement and diff...A promising electrochemical sensor based on PANI/AgCl hybrid material has been developed. The organic/inorganic hybrid material has exhibited good electrocatalytic properties by cyclic voltammetry measurement and differential pulse voltammetry. The oxidation overpotential of dopamine decreased dramatically, and the oxidation peak current increased significantly at PANI/AgCl/GCE compared to those obtained at PANI/GCE, AgCl/GCE and bare GCE, corresponding to the synergistic effect between PANI and inorganic particle AgCl. Under the optimized conditions, the linear response in the concentration range of 0.7 to 6.0 μM for the selective determination dopamine on the PANI/AgCl/GCE is obtained with a detection limit of 5.4 × 10–8 M (S/N = 3) using differential pulse voltammetry. The results indicated that the modified electrode can be used to determine dopamine without the interference from ascorbic acid and ensure high sensitivity and good selectivity.展开更多
Using ultra high purity NaF-NaKCO3 in the Fluorescence spectrometry, determination of sub ppb levels of Uranium in the electronic materials has been achieved. The method could be applied to determination of Uranium in...Using ultra high purity NaF-NaKCO3 in the Fluorescence spectrometry, determination of sub ppb levels of Uranium in the electronic materials has been achieved. The method could be applied to determination of Uranium in any electronic materials.展开更多
Crystal structure prediction(CSP)is a foundational computational technique for determining the atomic arrangements of crystalline materials,especially under high-pressure conditions.While CSP plays a critical role in ...Crystal structure prediction(CSP)is a foundational computational technique for determining the atomic arrangements of crystalline materials,especially under high-pressure conditions.While CSP plays a critical role in materials science,traditional approaches often encounter significant challenges related to computational efficiency and scalability,particularly when applied to complex systems.Recent advances in machine learning(ML)have shown tremendous promise in addressing these limitations,enabling the rapid and accurate prediction of crystal structures across a wide range of chemical compositions and external conditions.This review provides a concise overview of recent progress in ML-assisted CSP methodologies,with a particular focus on machine learning potentials and generative models.By critically analyzing these advances,we highlight the transformative impact of ML in accelerating materials discovery,enhancing computational efficiency,and broadening the applicability of CSP.Additionally,we discuss emerging opportunities and challenges in this rapidly evolving field.展开更多
Fast,precise structure determination of unknown compounds has been the foundation but with a persistent challenge in the field of chemical research.Among various chemical characterization techniques,single-crystal X-r...Fast,precise structure determination of unknown compounds has been the foundation but with a persistent challenge in the field of chemical research.Among various chemical characterization techniques,single-crystal X-ray diffraction(SCXRD)stands out as the most straightforward and accurate method in modern structural chemistry.By precisely determining the three-dimensional arrangement of atoms within a crystal,it provides direct atomic-level evidence for understanding the relationship between material structure and properties[1].展开更多
Conventionally, an experimentally determined phase diagram requires studies of phase formation at a range of temperatures for each composition, which takes years of effort from multiple research groups. Combinatorial ...Conventionally, an experimentally determined phase diagram requires studies of phase formation at a range of temperatures for each composition, which takes years of effort from multiple research groups. Combinatorial materials chip technology, featuring high-throughput synthesis and characterization, is able to determine the phase diagram of an entire composition spread of a binary or ternary system at a single temperature on one materials library, which, though significantly increasing efficiency, still requires many libraries processed at a series of temperatures in order to complete a phase diagram. In this paper, we propose a "one-chip method" to construct a complete phase diagram by individually synthesizing each pixel step by step with a progressive pulse of energy to heat at different temperatures while monitoring the phase evolution on the pixel in situ in real time. Repeating this process pixel by pixel throughout the whole chip allows the entire binary or ternary phase diagram to be mapped on one chip in a single experiment. The feasibility of this methodology is demonstrated in a study of a Ge-Sb-Te ternary alloy system, on which the amorphouscrystalline phase boundary is determined.展开更多
The polonium-210 activity in raw material targets which was used to make the start neutron source rods of Qinshan Nuclear Power Station was determined in calorimetry. The calorimeter used is a twin-cup isothermal one....The polonium-210 activity in raw material targets which was used to make the start neutron source rods of Qinshan Nuclear Power Station was determined in calorimetry. The calorimeter used is a twin-cup isothermal one. It works at room temperature and does not need any device of constant temperature. The instruments used for calorimetry are simple and have good properties. The background is from -1μV to + 2 μ V when the room temperature changs between 16℃ and 28 ℃. The data gotten in calorimetry are in correspondence within ±3.4 % with those from liquid scintillation method after the targets were dissolved, additionally in correspondence within ±1.7% with the data given by Amersham Laboratories for 241Am determination.展开更多
An inverse method for parameters identification of discrete element model combined with experiment is proposed.The inverse problem of parameter identification is transmitted to solve an optimization problem by minimiz...An inverse method for parameters identification of discrete element model combined with experiment is proposed.The inverse problem of parameter identification is transmitted to solve an optimization problem by minimizing the distance between the numerical calculations and experiment responses.In this method,the discrete element method is employed as numerical calculator for the forward problem.Then,the orthogonal experiment design with range analysis was used to carry out parameters sensitivity analysis.In addition,to improve the computational efficiency,the approximate model technique is used to replace the actual computational model.The intergeneration projection genetic algorithm(IP-GA)is employed as the optimization algorithm.Consequently,the parameters of the discrete element model are determined.To verify the effectiveness and accuracy of the inverse results,the comparisons of shape deviation experiments with discrete element simulations are provided.It indicates that the effective and reliable discrete element model parameters can be quickly obtained through several sets of experimental data.Hence,this inverse method can be applied more widely to determine the parameters of discrete element model for other materials.展开更多
The possibilities of determining creep parameters for a simple Norton law material are explored from indentation creep testing. Using creep finite element analysis the creep indentation test technique is analyzed in t...The possibilities of determining creep parameters for a simple Norton law material are explored from indentation creep testing. Using creep finite element analysis the creep indentation test technique is analyzed in terms of indentation rates at constant loads. Emphasis is placed on the relationships between the steady creep behavior of indentation systems and the creep property of the indented materials. The role of indenter geometry, size effects and macroscopic constraints is explicitly considered on indentation creep experiments. The influence of macroscopic constraints from the material systems becomes important when the size of the indenter is of the same order of magnitude as the size of the testing material. Two methods have been presented to assess the creep property of the indented material from the indentation experimental results on the single-phase-material and two-phase-material systems. The results contribute to a better mechanical understanding and extending the application of indentation creep testing.展开更多
In this study,zirconia containing refractory samples were decomposed by dilute nitric acid.The chloride ion content in the leaching solution was determined by thiocyanate spectrophotometry.The influences of the leachi...In this study,zirconia containing refractory samples were decomposed by dilute nitric acid.The chloride ion content in the leaching solution was determined by thiocyanate spectrophotometry.The influences of the leaching method of the sample pretreatment and the coloration condition of the solution to be tested on the test results were studied.The precision test was carried out and the results were compared with those determined by ion chromatography.The results showed that the zirconia containing refractories were boiled with dilute nitric acid to obtain the test solution.The influence of zirconium hydrolysis on determination was removed by centrifugation.The chlorine contents in zirconia containing refractories determined by spectrophotometry have low relative standard deviation(RSD),showing slight testing difference with those determined by ion chromatograghy.展开更多
Three directions of development of kinetic indentation methods.Physical-energetic analysis of the indentation force diagram according to ISO 14577.Physical theory and universal criterion for the macrohardness of a mat...Three directions of development of kinetic indentation methods.Physical-energetic analysis of the indentation force diagram according to ISO 14577.Physical theory and universal criterion for the macrohardness of a material.Model of the physical process,thermomechanical potential,function of the state of the kinetic macroindentation process.Method for determining the physical function and unit of measurement of the kinetic macrohardness of a material.The ratio of the values of the empirical(standard)and physical macrohardness of the material.Physical reason for the appearance of the size effect in empirical indentation methods.The principle of determining the standard value of physical macrohardness.展开更多
Results of analytical studies of the physical properties of the function and number of empirical macrohardness based on the standard experimental force diagram of kinetic macroindentation by a sphere.An analytical com...Results of analytical studies of the physical properties of the function and number of empirical macrohardness based on the standard experimental force diagram of kinetic macroindentation by a sphere.An analytical comparison method and a criterion for the similarity of the physical and empirical macrohardness of a material are proposed.The physical properties of the hardness measurement process using the Calvert-Johnson method are shown.The physical reasons for the size effect when measuring macrohardness are considered.The universal physical unit and standard of macrohardness of kinetic macroindentation by a sphere is substantiated.展开更多
文摘An integral constitutive equation and a set of material functions for describing the strain history of polymer melts were formulated in terms of the Cauchy-Green and Finger tensors. A simple memory function and the dependence of ηo and τt on M3.4 were derived from the theory of non-linear viscoelasticity with constraints of entanglements for polymer melts and substituted into the Oldroye-Walters-Fredickson constitutive equation. An integral constitutive equation for polymer melts was consequently obtained. Some material functions of the constitutive equation related to certain 'test flow' are examined as follows : (1) simple steady shear flow; (2) steady elongation flow; (3) small-amplitude oscillatory shear flow; (4) stress growth upon the inception of steady shear elongation flow; (5) stress relaxation (modulus and compllance). These theoretical relations for simple steady shear flow were compared with experimental data from our laboratory and references for various polymer melts and concentrated solutions. A good agreement between the theory and experiment was achieved.
文摘A novel technique of Moveable Reduction Bed Hydride Generator（MRBHG）was applied tohe hydride generation or cold vapor generation of As，Se，Ge，and Hg existing In TraditionalChinese Medicinal Material（TCM）．The simultaneous determination of the multi－elements wasperformed with ICP－MS．A solid reduction system involving the use of potassiumtetraborohydride and tartaric acid was applied to generating metal hydride or cold vaporefficiently．The factors affecting the metal cold vapor generation were studied．The mainadvantage of the technique is that only a 4μL volume of sample was required for the cold vapor
文摘The experiment regarding material determination of a vehicle part was conducted.The experiment on stamping production of a part using the steels A,B and C was made.The strain data on the deformed parts were measured.The forming limit diagrams for the steels were examined and evaluated.The results show that three steels are unsuitable for this stamping part.The desired material properties with an optimal strain hardening exponent value were determined using experimental and analytical methods.The steel D was chosen as a desired material.The results show that the steel D is appropriate for mass production.In addition,the feasibility of the application of thinner material to this part was studied.The validity of the material selection was verified theoretically and experimentally.
文摘The composition, microstructure, mechanical and frictional properties of PTFE and its fillers were represented and analyzed by XRD, SEM, DSC, XPS and large-scale polarizing microscope. The results show that PTFE has a flocculent structure with high melt temperature and decomposition temperature, big contact angle and crystallinity, and low surface hardness, compression strength, friction coefficient, wearing capacity and surface energy. Cooling rate influenced the friction coefficient and wear resistance. Graphite and molybdenum disulfide have a flake structure, and molybdenum disulfide has a big contact angle and low surface energy. Copper powder has a globular structure and its chief component is Cu-Pb alloy, and there is a loose layer on the surface. Carbon fiber has a rod structure and there are C=O and C-O-C polar groups on the skeleton surface. The decreasing order of water absorption capacity is graphite, carbon fiber, molybdenum disulfide, PTFE and copper powder.
文摘This paper introduces the ceramic materials fusion method to use porcelain crucible instead of platinum crucible. By this method, not only the funds can be saved, but also the operation becomes simple and the analysed results are accurate and reliable. On the other hand, the high fusion point materials, such as high aluminum ceramic raw ma- terials, can also be melted and their aluminum contents can be determined by this method. Thus, it can be widely used in the students laboratory and routine analysis of small and middle industrial enterprises.
文摘A promising electrochemical sensor based on PANI/AgCl hybrid material has been developed. The organic/inorganic hybrid material has exhibited good electrocatalytic properties by cyclic voltammetry measurement and differential pulse voltammetry. The oxidation overpotential of dopamine decreased dramatically, and the oxidation peak current increased significantly at PANI/AgCl/GCE compared to those obtained at PANI/GCE, AgCl/GCE and bare GCE, corresponding to the synergistic effect between PANI and inorganic particle AgCl. Under the optimized conditions, the linear response in the concentration range of 0.7 to 6.0 μM for the selective determination dopamine on the PANI/AgCl/GCE is obtained with a detection limit of 5.4 × 10–8 M (S/N = 3) using differential pulse voltammetry. The results indicated that the modified electrode can be used to determine dopamine without the interference from ascorbic acid and ensure high sensitivity and good selectivity.
文摘Using ultra high purity NaF-NaKCO3 in the Fluorescence spectrometry, determination of sub ppb levels of Uranium in the electronic materials has been achieved. The method could be applied to determination of Uranium in any electronic materials.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1402304)the National Natural Science Foundation of China(Grant Nos.12034009,12374005,52288102,52090024,and T2225013)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Program for JLU Science and Technology Innovative Research Team.
文摘Crystal structure prediction(CSP)is a foundational computational technique for determining the atomic arrangements of crystalline materials,especially under high-pressure conditions.While CSP plays a critical role in materials science,traditional approaches often encounter significant challenges related to computational efficiency and scalability,particularly when applied to complex systems.Recent advances in machine learning(ML)have shown tremendous promise in addressing these limitations,enabling the rapid and accurate prediction of crystal structures across a wide range of chemical compositions and external conditions.This review provides a concise overview of recent progress in ML-assisted CSP methodologies,with a particular focus on machine learning potentials and generative models.By critically analyzing these advances,we highlight the transformative impact of ML in accelerating materials discovery,enhancing computational efficiency,and broadening the applicability of CSP.Additionally,we discuss emerging opportunities and challenges in this rapidly evolving field.
基金the National Natural Science Foundation of China(Nos.22471014 and 22271013)the Beijing Natural Science Foundation(No.2232024)for financial support.
文摘Fast,precise structure determination of unknown compounds has been the foundation but with a persistent challenge in the field of chemical research.Among various chemical characterization techniques,single-crystal X-ray diffraction(SCXRD)stands out as the most straightforward and accurate method in modern structural chemistry.By precisely determining the three-dimensional arrangement of atoms within a crystal,it provides direct atomic-level evidence for understanding the relationship between material structure and properties[1].
基金supported in part by National High Technology Research and Development Program (2015AA034204)the National Natural Science Foundation of China (51472044)
文摘Conventionally, an experimentally determined phase diagram requires studies of phase formation at a range of temperatures for each composition, which takes years of effort from multiple research groups. Combinatorial materials chip technology, featuring high-throughput synthesis and characterization, is able to determine the phase diagram of an entire composition spread of a binary or ternary system at a single temperature on one materials library, which, though significantly increasing efficiency, still requires many libraries processed at a series of temperatures in order to complete a phase diagram. In this paper, we propose a "one-chip method" to construct a complete phase diagram by individually synthesizing each pixel step by step with a progressive pulse of energy to heat at different temperatures while monitoring the phase evolution on the pixel in situ in real time. Repeating this process pixel by pixel throughout the whole chip allows the entire binary or ternary phase diagram to be mapped on one chip in a single experiment. The feasibility of this methodology is demonstrated in a study of a Ge-Sb-Te ternary alloy system, on which the amorphouscrystalline phase boundary is determined.
文摘The polonium-210 activity in raw material targets which was used to make the start neutron source rods of Qinshan Nuclear Power Station was determined in calorimetry. The calorimeter used is a twin-cup isothermal one. It works at room temperature and does not need any device of constant temperature. The instruments used for calorimetry are simple and have good properties. The background is from -1μV to + 2 μ V when the room temperature changs between 16℃ and 28 ℃. The data gotten in calorimetry are in correspondence within ±3.4 % with those from liquid scintillation method after the targets were dissolved, additionally in correspondence within ±1.7% with the data given by Amersham Laboratories for 241Am determination.
基金supported by the National Natural Science Foundation of China(11602212)the Natural Science Foundation of Hunan Province of China(2018JJ3509)supported by the National Natural Science Foundation of China(51605409,11802258,51775468).
文摘An inverse method for parameters identification of discrete element model combined with experiment is proposed.The inverse problem of parameter identification is transmitted to solve an optimization problem by minimizing the distance between the numerical calculations and experiment responses.In this method,the discrete element method is employed as numerical calculator for the forward problem.Then,the orthogonal experiment design with range analysis was used to carry out parameters sensitivity analysis.In addition,to improve the computational efficiency,the approximate model technique is used to replace the actual computational model.The intergeneration projection genetic algorithm(IP-GA)is employed as the optimization algorithm.Consequently,the parameters of the discrete element model are determined.To verify the effectiveness and accuracy of the inverse results,the comparisons of shape deviation experiments with discrete element simulations are provided.It indicates that the effective and reliable discrete element model parameters can be quickly obtained through several sets of experimental data.Hence,this inverse method can be applied more widely to determine the parameters of discrete element model for other materials.
文摘The possibilities of determining creep parameters for a simple Norton law material are explored from indentation creep testing. Using creep finite element analysis the creep indentation test technique is analyzed in terms of indentation rates at constant loads. Emphasis is placed on the relationships between the steady creep behavior of indentation systems and the creep property of the indented materials. The role of indenter geometry, size effects and macroscopic constraints is explicitly considered on indentation creep experiments. The influence of macroscopic constraints from the material systems becomes important when the size of the indenter is of the same order of magnitude as the size of the testing material. Two methods have been presented to assess the creep property of the indented material from the indentation experimental results on the single-phase-material and two-phase-material systems. The results contribute to a better mechanical understanding and extending the application of indentation creep testing.
文摘In this study,zirconia containing refractory samples were decomposed by dilute nitric acid.The chloride ion content in the leaching solution was determined by thiocyanate spectrophotometry.The influences of the leaching method of the sample pretreatment and the coloration condition of the solution to be tested on the test results were studied.The precision test was carried out and the results were compared with those determined by ion chromatography.The results showed that the zirconia containing refractories were boiled with dilute nitric acid to obtain the test solution.The influence of zirconium hydrolysis on determination was removed by centrifugation.The chlorine contents in zirconia containing refractories determined by spectrophotometry have low relative standard deviation(RSD),showing slight testing difference with those determined by ion chromatograghy.
文摘Three directions of development of kinetic indentation methods.Physical-energetic analysis of the indentation force diagram according to ISO 14577.Physical theory and universal criterion for the macrohardness of a material.Model of the physical process,thermomechanical potential,function of the state of the kinetic macroindentation process.Method for determining the physical function and unit of measurement of the kinetic macrohardness of a material.The ratio of the values of the empirical(standard)and physical macrohardness of the material.Physical reason for the appearance of the size effect in empirical indentation methods.The principle of determining the standard value of physical macrohardness.
文摘Results of analytical studies of the physical properties of the function and number of empirical macrohardness based on the standard experimental force diagram of kinetic macroindentation by a sphere.An analytical comparison method and a criterion for the similarity of the physical and empirical macrohardness of a material are proposed.The physical properties of the hardness measurement process using the Calvert-Johnson method are shown.The physical reasons for the size effect when measuring macrohardness are considered.The universal physical unit and standard of macrohardness of kinetic macroindentation by a sphere is substantiated.
