Updated version of local non-equilibrium diffusion model （LNDM） for rapid solidification of binary alloys was considered. The LNDM takes into account deviation from local equilibrium of solute concentration and solu...Updated version of local non-equilibrium diffusion model （LNDM） for rapid solidification of binary alloys was considered. The LNDM takes into account deviation from local equilibrium of solute concentration and solute flux fields in bulk liquid. The exact solutions for solute concentration and flux in bulk liquid were obtained using hyperbolic diffusion equations. The results show the transition from diffusion-limited to purely thermally controlled solidification with effective diffusion coefficient →0 and complete solute trapping KLNDM（v）→1 at v→vDb for any kind of solid-liquid interface kinetics. Critical parameter for diffusionless solidification and complete solute trapping is the diffusion speed in bulk liquid vDb. Different models for solute trapping at the interface with different interface kinetic approaches were considered.展开更多
When concentrated forces are applied at any points of the outer region of an ellipse in an infinite plate, the complex potentials are determined using the conformal mapping method and Cauchy＇s integral formula. And t...When concentrated forces are applied at any points of the outer region of an ellipse in an infinite plate, the complex potentials are determined using the conformal mapping method and Cauchy＇s integral formula. And then, based on the superposition principle, the analyt- ical solutions for stress around an elliptical hole in an infinite plate subjected to a uniform far-field stress and concentrated forces, are obtained. Tangential stress concentration will occur on the hole boundary when only far-field uniform loads are applied. When concen- trated forces are applied in the reversed directions of the uniform loads, tangential stress concentration on the hole boundary can be released significantly. In order to minimize the tangential stress concentration, we need to determine the optimum positions and values of the concentrated forces. Three different optimization methods are applied to achieve this aim. The results show that the tangential stress can be released significantly when the op- timized concentrated forces are applied.展开更多
SPR sensor with matrix arrangement of nanostructured golden spots enables both the study of low concentrations of substances in solution and the acquisition of information on the spatial layout of the diagnosed medium...SPR sensor with matrix arrangement of nanostructured golden spots enables both the study of low concentrations of substances in solution and the acquisition of information on the spatial layout of the diagnosed medium in solution. The linear response of this sensor was experimentally specified for standard solutions of alcohols in a concentration range of 0.01 - 0.5 wt%. The influence of signal noise generated by carrier substance flowing through sensing dots has been removed by data processing. This approach enables to determine refractive index changes less than 3 × 10-6.展开更多
This study investigated the effects of chlorine-based fertilizers under varying nitrogen solution concentrations in a soilless culture system. The experiment included four nitrogen solution concentration levels, with ...This study investigated the effects of chlorine-based fertilizers under varying nitrogen solution concentrations in a soilless culture system. The experiment included four nitrogen solution concentration levels, with nitrogen concentrations of 6 mmol/L (C1), 12 mmol/L (C2), 18 mmol/L (C3), and 24 mmol/L (C4). Each nutrient concentration level was further divided into four chloride ion treatments (R1, R2, R3, and R4), where 100%, 60%, 33%, and 0% of the NH4+ and K+ ions were derived from NH4Cl and KCl, respectively. The length, surface area and volume of root were significantly higher by 25.3%~136.9%, 40.1%~173.1%, 27.9%~178.0%, respectively, in the R4 treatment than in the R1 and R2 treatments at flowering stage. The aboveground biomass and yield in the R4 treatment were significantly higher, by approximately 15.6%~43.5% and 16.6%~28.6%, respectively, than in the R1, R2, and R3 treatments at the picking stage. The C3 and C4 treatments significantly decreased biomass and yield by 31.9%~50.2% and 20.7%~50.5%, respectively, compared to the C1 and C2 treatments at the picking stage. Besides, the higher nutrient solution increased the incidence of blossom-end rot. In conclusion, high concentrations of chloride ions in nutrient solutions, especially when the Cl− concentration exceeded 10 mmol/L, have been shown to inhibit tomato growth in soilless culture systems. Therefore, replacing sulfur-based fertilizers by chlorine-based fertilizers is not recommended for tomato production under the studied conditions.展开更多
Based on the difference in tendency to polymerize between tungsten and molybdenum, a new method using D309 resin was propounded. The batch tests indicate that the optimum pH value and contact time for the separation a...Based on the difference in tendency to polymerize between tungsten and molybdenum, a new method using D309 resin was propounded. The batch tests indicate that the optimum pH value and contact time for the separation are 7.0 and 4 h respectively, the maxium separation factor of W and Mo is 9.29. And the experimental resules show that isothermal absorbing tungsten and molybdenum belongs to Langmuir model and Freundlich model respectively, and the absorbing kinetics for tungsten is controlled by intra-particle diffusion. With a solution containing 70 g/L WO3 and 28.97 g/L Mo, the effluent with a mass ratio of Mo to WO3 of 76 and the eluate with a mass ratio of WO3 to Mo of 53.33 are obtained after column test.展开更多
The gel-spun ultra-high molecular weight polyethylene （UHMWPE） fibers were prepared at the industrial production line with different gel solution concentrations of 15 wt%, 18 wt% and 24 wt%. The difference in ultima...The gel-spun ultra-high molecular weight polyethylene （UHMWPE） fibers were prepared at the industrial production line with different gel solution concentrations of 15 wt%, 18 wt% and 24 wt%. The difference in ultimate structure and mechanical properties of UHMWPE fibers for different gel solution concentrations were analyzed by tensile testing, differential scanning calorimetry （DSC）, wide angle X-ray diffraction （WAXD） and small angle X-ray scattering （SAXS）. With the increase of gel solution concentration, the ultimate mechanical properties of UHMWPE fibers were decreased and the crystallization and orientation of UHMWPE fibers became inferior. Besides, both the average shish length （ （Lshsh） ） and shish misorientation （B0） of UHMWPE fibers were decreased with the increase of gel solution concentration. In addition, the appropriate increase of spinning temperature led to the further optimization of the ultimate structure and mechanical properties of UHMWPE fibers.展开更多
To reveal the affecting mechanism of cooling rate on lamellarαprecipitation,the precipitation behaviors of lamellarαphase in IMI834 titanium alloy during isothermal and non-isothermal heat treatments were quantitati...To reveal the affecting mechanism of cooling rate on lamellarαprecipitation,the precipitation behaviors of lamellarαphase in IMI834 titanium alloy during isothermal and non-isothermal heat treatments were quantitatively characterized using experimental analysis.Critical precipitation temperatures at various cooling rates were obtained using thermal dilatation testing.Using metallographic microscopy,electron microprobe analysis,and data fitting methods,the quantitative evolution models of average width,volume fraction,and solute concentration in theαandβphases were built for different temperatures or cooling rates.A comparison between the two precipitation behaviors showed that the average width and volume fraction of lamellarαphase under non-isothermal conditions were smaller than those under isothermal conditions.With increasing cooling rate,the average width and volume fraction were decreased significantly,and the critical precipitation temperatures were reduced.This phenomenon is mainly attributed to the decreased diffusion velocity of solutes Al,Mo,and Nb with increasing cooling rate.展开更多
In this article, we study the multiplicity and concentration behavior of positive solutions for the p-Laplacian equation of SchrSdinger-Kirchhoff type -εpM（εp-N∫RN｜△u｜p）△pu＋v（x｜u｜p-2u=f（u）in RN, where ...In this article, we study the multiplicity and concentration behavior of positive solutions for the p-Laplacian equation of SchrSdinger-Kirchhoff type -εpM（εp-N∫RN｜△u｜p）△pu＋v（x｜u｜p-2u=f（u）in RN, where △p is the p-Laplacian operator, 1 〈 p 〈 N, M ： R＋ → R＋ and V ： RN →R＋ are continuous functions, ε is a positive parameter, and f is a continuous function with subcritical growth. We assume that V satisfies the local condition introduced by M. del Pino and P. Felmer. By the variational methods, penalization techniques, and Lyusternik- Schnirelmann theory, we prove the existence, multiplicity, and concentration of solutions for the above equation.展开更多
Epitaxial YBCO films were deposited on （100） LaAlO3 single-crystal substrates by metalorganic deposition of metal trifluoroacetate precursors with different concentrations. All the YBCO films have Tc around 91 K and...Epitaxial YBCO films were deposited on （100） LaAlO3 single-crystal substrates by metalorganic deposition of metal trifluoroacetate precursors with different concentrations. All the YBCO films have Tc around 91 K and Jc excess 2 MA/cm^2 at 77 K in zero field. XRD θ-2θscans show all the films have c-axis normal orientation. The FWHM （full width at half-maximum intensity） values of X-ray ω-scans of （005） reflection are 0.379°, 0.283°, and 0.543° for the YBCO thin films deposited with precursor solution concentrations of 1.52, 1.0, and 0.75 mol/L, respectively. With the concentration of the precursors decreasing, the thickness of the films decreases linearly. SEM micrographs show that porosities in the films become bigger with the precursor solution concentration decreasing. The big porosities in the film with the lowest concentration precursor deteriorate the superconducting property and make it have a wider superconducting transition and a lower Jc.展开更多
The anion storage behavior of graphite positive electrode in a dual-ion battery is closely related to the solvation of anion in the corresponding electrolyte solution.The classical electrolyte solutions of Li BF_(4)^(...The anion storage behavior of graphite positive electrode in a dual-ion battery is closely related to the solvation of anion in the corresponding electrolyte solution.The classical electrolyte solutions of Li BF_(4)^(-)sulfolane(SL)have long been recognized in the community of lithium batteries and still appear promising in dual-ion batteries.Nevertheless,the solvation of BF_(4)^(-)by SL has seldom been addressed before.In this study,the solvation states of SL-BF_(4)^(-)are adjusted by varying LiBF_(4)concentration or introducing auxiliary salts of LiPF_6or SBPBF_(4)(SBP:spiro-(1,1')-bipyrrolidinium)in the electrolyte solutions of Li/graphite dualion cells.The electrochemical storage processes of SL-BF_(4)^(-)anions in graphite electrodes are investigated through in situ X-ray diffraction measurements.Two kinds of graphite intercalation compounds(GICs)with contrastive intercalation gallery heights(IGHs)have been discovered,which are ascribed to the storage of different kinds of SL-BF_(4)^(-)anions in graphite electrode.The interactions between ions and SL in the electrolyte solutions are characterized by Fourier transform infrared spectroscopy and then correlated with the performance of Li/graphite cells.展开更多
Polyphenol film deposited on platinum foil can continuously grow with time during the electrolysis of a phenol solution consisting of 0.1 mol L-1 phenol, 3 mol L-1 NaOH and 0.5 mol L-1 Na2SO4, as has been proved by th...Polyphenol film deposited on platinum foil can continuously grow with time during the electrolysis of a phenol solution consisting of 0.1 mol L-1 phenol, 3 mol L-1 NaOH and 0.5 mol L-1 Na2SO4, as has been proved by the methods of sweep potential, constant potential and constant current, and visible spectra during the electrolysis of phenol. A polyphenol film with thickness of 0.11 mm was obtained by the electrolysis of phenol at a constant potential of 0.70 V (versus Ag/AgCl with saturated KCl solution). Polyphenol film is inactive and stable in 2 mol L-1 H2SO4 solution, neutral solution and 3 mol L-1 NaOH solution and in the potential range between -0.95 and 1.35 V. The usable potential range is dependent on the pH value. Polyphenol has an ESR signal with a g factor of 2.0049. The conductivity of polyphenol is 1.2 x 10(-4) S cm(-1). In the solution of polyphenol dissolved in DMSO, the mobility of polyphenol anions is 8 x 10(-9) m(2) s(-1) V-1 at 20degreesC.展开更多
The performance of rechargeable batteries and other electrochemical systems depends on the rate at which the working ion(often a cation)is transported from one electrode to the other.The cation transference number is ...The performance of rechargeable batteries and other electrochemical systems depends on the rate at which the working ion(often a cation)is transported from one electrode to the other.The cation transference number is an important transport parameter that affects this rate.The purpose of this perspective is to distinguish between approximate and rigorous methods used in the literature to measure the transference number.We emphasize the fact that this parameter is dependent on the reference frame used in the analysis;care must be taken when comparing values obtained from different sources to account for differences in reference frames.We present data obtained from a well-characterized electrolyte.We compare rigorously determined transference numbers in two reference frames with values obtained by an approximate method.We conclude with a qualitative discussion of the relationship between the transference number and salt concentration gradients that are obtained when current is drawn through a battery。展开更多
The cholesterol solution concentration sensing characteristics based on tilted fiber Bragg grating(TFBG) are investigated by means of theoretical analysis and experiments. We prepare two groups of cholesterol solution...The cholesterol solution concentration sensing characteristics based on tilted fiber Bragg grating(TFBG) are investigated by means of theoretical analysis and experiments. We prepare two groups of cholesterol solutions with the same concentration range and different refractive index ranges. The sensitivity of the two groups of solutions was 11.83 pm·m L/mg and 124.79 pm·m L/mg, respectively. The results show that the sensitivity of cholesterol solution can be improved by adjusting the refractive index range. This conclusion is valuable for measuring the concentration of fat-soluble solution.展开更多
Selective-controlled structure and shape of CeVO4 nanocrystals were successfully synthesized via a hydrothermal method from Na3VO4·12H2O and Ce（NO3）3·6H2O.The resulting products were characterized by X-ray...Selective-controlled structure and shape of CeVO4 nanocrystals were successfully synthesized via a hydrothermal method from Na3VO4·12H2O and Ce（NO3）3·6H2O.The resulting products were characterized by X-ray powder diffraction （XRD）,field emission scanning electron microscopy （FESEM） and energy dispersive spectroscopy （EDS）.The influence of hydrothermal temperature,precursor solution concentration on the crystal and morphology of products were further studied.The results showed that the as-synthesized products exhibited pure single-crystal CeVO4 nanoparticles with tetragonal structure.The hydrothermal temperature and precursor solution concentration had important effects on the formation of CeVO4 nanoparticles.Furthermore,the growth mechanism of CeVO4 nanoparticles was explained with Ostwald ripening mechanism.展开更多
Based on the molecular theory of non-linear viscoelasticity with constrained entanglements in polymer melts, the material functions in simple shear flow were formulated, the theoretical relations between. eta((gamma) ...Based on the molecular theory of non-linear viscoelasticity with constrained entanglements in polymer melts, the material functions in simple shear flow were formulated, the theoretical relations between. eta((gamma) over dot), psi (10)((gamma) over dot) and shear rate ((gamma) over dot), and topologically constrained dimension number n ' and a were derived. Linear viscoelastic parameters (eta (0) and G(N)(0)) and topologically constrained dimension number (n ' a and <(<upsilon>)over bar>) as a function of the primary molecular weight (M-n), molecular weight between entanglements (M-C) and the entanglement sites sequence distribution in polymer chain were determined. A new method for determination of viscoelastic parameters (eta (0), psi (10), G(N)(0) and J(e)(0)), topologically constrained dimension number (n ', a and v) and molecular weight (M-n, M-c and M-e) from the shear flow measurements was proposed. It was used to determine those parameters and structures of HDPE, making a good agreement between these values and those obtained by other methods. The agreement affords a quantitative verification for the molecular theory of nonlinear viscoelasticity with constrained entanglement in polymer melts.展开更多
An approach of stochastically statistical mechanics and a unified molecular theory of nonlinear viscoelasticity with constraints of Nagai chain entanglement for polymer melts have been proposed. A multimode model stru...An approach of stochastically statistical mechanics and a unified molecular theory of nonlinear viscoelasticity with constraints of Nagai chain entanglement for polymer melts have been proposed. A multimode model structure for a single polymer chain with n tail segments and N reversible entanglement sites on the test polymer chain is developed. Based on the above model structure and the mechanism of molecular flow by the dynamical reorganization of entanglement sites, the probability distribution function of the end-to-end vectr for a single polymer chain at entangled state and the viscoelastic free energy of deformation for polymer melts are calculated by using the method of the stochastically statistical mechanics. The four types of stress-strain relation and the memory function are derived from this thery. The above theoretical relations are verified by the experimentaf data for various polymer melts. These relations are found to be in good agreement with the experimental results展开更多
Vertically oriented ZnO nanorods have been synthesized by hydrothermal method on quartz substrates with a seed layer. The influence of solution concentration on the morphology, structural and optical properties was an...Vertically oriented ZnO nanorods have been synthesized by hydrothermal method on quartz substrates with a seed layer. The influence of solution concentration on the morphology, structural and optical properties was analyzed. Results indicated that with the increase of solution concentration, the diameter and uniformity of ZnO nanorods increased. And the preferred orientation is obviously which shows better crystal quality. Typically, when the solution concentration is 0.03 mol/L, the nanorods exhibit a stronger UV emission peak located around 380 nm. In the visible region, all synthesized samples demonstrate more than 80% of optical transparency.展开更多
A model for describing solute segregation at grain boundaries has been developed for substitutional solid solution alloys,which integrates multiple factors from atomic to microstructural scales.A concept of mo-lar Gib...A model for describing solute segregation at grain boundaries has been developed for substitutional solid solution alloys,which integrates multiple factors from atomic to microstructural scales.A concept of mo-lar Gibbs free energy of segregation was introduced to evaluate the segregating capability of the solute elements in a closed system,through which the influences of grain boundary structure,grain size,ma-terial composition,and external conditions were described.Based on the evaluation of various energy forms related to solute segregation and grain growth processes,the nature of the thermal stabilization of nanograin structures by solute segregation was disclosed.A criterion for the destabilization of nanostruc-tures,which is determined by the competition of the change rates between the molar Gibbs free energy of segregation and the total energy of grain boundaries with grain size,has been proposed.This study provided guideline to achieve high-temperature stability of nanograin structures of solid solution alloys even for the weakly segregating nanocrystalline systems.展开更多
Linear triblock copolymers of poly（N-isopropylacrylamide） （PNIPAM） and poly（ethylene glycol） （PEG） with two azide groups at both block junctions （PNIPAM-N3-PEG-N3-PNIPAM） are click reacted with dipropargyl o...Linear triblock copolymers of poly（N-isopropylacrylamide） （PNIPAM） and poly（ethylene glycol） （PEG） with two azide groups at both block junctions （PNIPAM-N3-PEG-N3-PNIPAM） are click reacted with dipropargyl oxalylate under high polymer concentration （250 g/L）. Benefiting from rapid feature of alkyne-azide click reaction and spatial shielding of PNIPAM end blocks, PEG center block of PNIPAM-N3-PEG-N3-PNIPAM remains separated although PNIPAM end blocks keep in contact under this high concentration. Therefore, PNIPAM-N3-PEG-N3-PNIPAM undergoes self-cyclization at block junctions to form tadpole-shaped architecture while N3-PEG-N3 without PNIPAM end blocks inter-connects linearly. The influence of block lengths of PEG and PNIPAM on the unusual cyclization under high polymer concentration is studied.展开更多
文摘Updated version of local non-equilibrium diffusion model （LNDM） for rapid solidification of binary alloys was considered. The LNDM takes into account deviation from local equilibrium of solute concentration and solute flux fields in bulk liquid. The exact solutions for solute concentration and flux in bulk liquid were obtained using hyperbolic diffusion equations. The results show the transition from diffusion-limited to purely thermally controlled solidification with effective diffusion coefficient →0 and complete solute trapping KLNDM（v）→1 at v→vDb for any kind of solid-liquid interface kinetics. Critical parameter for diffusionless solidification and complete solute trapping is the diffusion speed in bulk liquid vDb. Different models for solute trapping at the interface with different interface kinetic approaches were considered.
基金supported by the National Natural Science Foundation of China [grant numbers 11172101, 11572126]
文摘When concentrated forces are applied at any points of the outer region of an ellipse in an infinite plate, the complex potentials are determined using the conformal mapping method and Cauchy＇s integral formula. And then, based on the superposition principle, the analyt- ical solutions for stress around an elliptical hole in an infinite plate subjected to a uniform far-field stress and concentrated forces, are obtained. Tangential stress concentration will occur on the hole boundary when only far-field uniform loads are applied. When concen- trated forces are applied in the reversed directions of the uniform loads, tangential stress concentration on the hole boundary can be released significantly. In order to minimize the tangential stress concentration, we need to determine the optimum positions and values of the concentrated forces. Three different optimization methods are applied to achieve this aim. The results show that the tangential stress can be released significantly when the op- timized concentrated forces are applied.
基金This paper was created in the Project No.LO1203“Regional Materials Science and Technology Centre—Feasibility Program”funded by Ministry of Education,Youth and Sports of the Czech Republic.
文摘SPR sensor with matrix arrangement of nanostructured golden spots enables both the study of low concentrations of substances in solution and the acquisition of information on the spatial layout of the diagnosed medium in solution. The linear response of this sensor was experimentally specified for standard solutions of alcohols in a concentration range of 0.01 - 0.5 wt%. The influence of signal noise generated by carrier substance flowing through sensing dots has been removed by data processing. This approach enables to determine refractive index changes less than 3 × 10-6.
基金Weifang Vocational College Research Project and the National Key Research and Development Program of China(2023YFE0104700).
文摘This study investigated the effects of chlorine-based fertilizers under varying nitrogen solution concentrations in a soilless culture system. The experiment included four nitrogen solution concentration levels, with nitrogen concentrations of 6 mmol/L (C1), 12 mmol/L (C2), 18 mmol/L (C3), and 24 mmol/L (C4). Each nutrient concentration level was further divided into four chloride ion treatments (R1, R2, R3, and R4), where 100%, 60%, 33%, and 0% of the NH4+ and K+ ions were derived from NH4Cl and KCl, respectively. The length, surface area and volume of root were significantly higher by 25.3%~136.9%, 40.1%~173.1%, 27.9%~178.0%, respectively, in the R4 treatment than in the R1 and R2 treatments at flowering stage. The aboveground biomass and yield in the R4 treatment were significantly higher, by approximately 15.6%~43.5% and 16.6%~28.6%, respectively, than in the R1, R2, and R3 treatments at the picking stage. The C3 and C4 treatments significantly decreased biomass and yield by 31.9%~50.2% and 20.7%~50.5%, respectively, compared to the C1 and C2 treatments at the picking stage. Besides, the higher nutrient solution increased the incidence of blossom-end rot. In conclusion, high concentrations of chloride ions in nutrient solutions, especially when the Cl− concentration exceeded 10 mmol/L, have been shown to inhibit tomato growth in soilless culture systems. Therefore, replacing sulfur-based fertilizers by chlorine-based fertilizers is not recommended for tomato production under the studied conditions.
基金Project(51174232)supported by the National Natural Science Foundation of China
文摘Based on the difference in tendency to polymerize between tungsten and molybdenum, a new method using D309 resin was propounded. The batch tests indicate that the optimum pH value and contact time for the separation are 7.0 and 4 h respectively, the maxium separation factor of W and Mo is 9.29. And the experimental resules show that isothermal absorbing tungsten and molybdenum belongs to Langmuir model and Freundlich model respectively, and the absorbing kinetics for tungsten is controlled by intra-particle diffusion. With a solution containing 70 g/L WO3 and 28.97 g/L Mo, the effluent with a mass ratio of Mo to WO3 of 76 and the eluate with a mass ratio of WO3 to Mo of 53.33 are obtained after column test.
基金financially supported by the National Natural Science Foundation of China(No.51273210)Natural Science Foundation of Ningbo Municipal(No.2015A610021)K.C.Wong Magna Fund in Ningbo University
文摘The gel-spun ultra-high molecular weight polyethylene （UHMWPE） fibers were prepared at the industrial production line with different gel solution concentrations of 15 wt%, 18 wt% and 24 wt%. The difference in ultimate structure and mechanical properties of UHMWPE fibers for different gel solution concentrations were analyzed by tensile testing, differential scanning calorimetry （DSC）, wide angle X-ray diffraction （WAXD） and small angle X-ray scattering （SAXS）. With the increase of gel solution concentration, the ultimate mechanical properties of UHMWPE fibers were decreased and the crystallization and orientation of UHMWPE fibers became inferior. Besides, both the average shish length （ （Lshsh） ） and shish misorientation （B0） of UHMWPE fibers were decreased with the increase of gel solution concentration. In addition, the appropriate increase of spinning temperature led to the further optimization of the ultimate structure and mechanical properties of UHMWPE fibers.
基金financial supports from the National Natural Science Foundation of China(No.51675433)the Natural Science Foundation for Distinguished Young Scholars of Shaanxi Province,China(No.2019JC-09)。
文摘To reveal the affecting mechanism of cooling rate on lamellarαprecipitation,the precipitation behaviors of lamellarαphase in IMI834 titanium alloy during isothermal and non-isothermal heat treatments were quantitatively characterized using experimental analysis.Critical precipitation temperatures at various cooling rates were obtained using thermal dilatation testing.Using metallographic microscopy,electron microprobe analysis,and data fitting methods,the quantitative evolution models of average width,volume fraction,and solute concentration in theαandβphases were built for different temperatures or cooling rates.A comparison between the two precipitation behaviors showed that the average width and volume fraction of lamellarαphase under non-isothermal conditions were smaller than those under isothermal conditions.With increasing cooling rate,the average width and volume fraction were decreased significantly,and the critical precipitation temperatures were reduced.This phenomenon is mainly attributed to the decreased diffusion velocity of solutes Al,Mo,and Nb with increasing cooling rate.
基金supported by Natural Science Foundation of China(11371159 and 11771166)Hubei Key Laboratory of Mathematical Sciences and Program for Changjiang Scholars and Innovative Research Team in University#IRT_17R46
文摘In this article, we study the multiplicity and concentration behavior of positive solutions for the p-Laplacian equation of SchrSdinger-Kirchhoff type -εpM（εp-N∫RN｜△u｜p）△pu＋v（x｜u｜p-2u=f（u）in RN, where △p is the p-Laplacian operator, 1 〈 p 〈 N, M ： R＋ → R＋ and V ： RN →R＋ are continuous functions, ε is a positive parameter, and f is a continuous function with subcritical growth. We assume that V satisfies the local condition introduced by M. del Pino and P. Felmer. By the variational methods, penalization techniques, and Lyusternik- Schnirelmann theory, we prove the existence, multiplicity, and concentration of solutions for the above equation.
文摘Epitaxial YBCO films were deposited on （100） LaAlO3 single-crystal substrates by metalorganic deposition of metal trifluoroacetate precursors with different concentrations. All the YBCO films have Tc around 91 K and Jc excess 2 MA/cm^2 at 77 K in zero field. XRD θ-2θscans show all the films have c-axis normal orientation. The FWHM （full width at half-maximum intensity） values of X-ray ω-scans of （005） reflection are 0.379°, 0.283°, and 0.543° for the YBCO thin films deposited with precursor solution concentrations of 1.52, 1.0, and 0.75 mol/L, respectively. With the concentration of the precursors decreasing, the thickness of the films decreases linearly. SEM micrographs show that porosities in the films become bigger with the precursor solution concentration decreasing. The big porosities in the film with the lowest concentration precursor deteriorate the superconducting property and make it have a wider superconducting transition and a lower Jc.
基金financially supported by the National Natural Science Foundation of China,China(21975251)。
文摘The anion storage behavior of graphite positive electrode in a dual-ion battery is closely related to the solvation of anion in the corresponding electrolyte solution.The classical electrolyte solutions of Li BF_(4)^(-)sulfolane(SL)have long been recognized in the community of lithium batteries and still appear promising in dual-ion batteries.Nevertheless,the solvation of BF_(4)^(-)by SL has seldom been addressed before.In this study,the solvation states of SL-BF_(4)^(-)are adjusted by varying LiBF_(4)concentration or introducing auxiliary salts of LiPF_6or SBPBF_(4)(SBP:spiro-(1,1')-bipyrrolidinium)in the electrolyte solutions of Li/graphite dualion cells.The electrochemical storage processes of SL-BF_(4)^(-)anions in graphite electrodes are investigated through in situ X-ray diffraction measurements.Two kinds of graphite intercalation compounds(GICs)with contrastive intercalation gallery heights(IGHs)have been discovered,which are ascribed to the storage of different kinds of SL-BF_(4)^(-)anions in graphite electrode.The interactions between ions and SL in the electrolyte solutions are characterized by Fourier transform infrared spectroscopy and then correlated with the performance of Li/graphite cells.
基金This work was supported by the National Natural Science Foundation of China (No. 20074027).
文摘Polyphenol film deposited on platinum foil can continuously grow with time during the electrolysis of a phenol solution consisting of 0.1 mol L-1 phenol, 3 mol L-1 NaOH and 0.5 mol L-1 Na2SO4, as has been proved by the methods of sweep potential, constant potential and constant current, and visible spectra during the electrolysis of phenol. A polyphenol film with thickness of 0.11 mm was obtained by the electrolysis of phenol at a constant potential of 0.70 V (versus Ag/AgCl with saturated KCl solution). Polyphenol film is inactive and stable in 2 mol L-1 H2SO4 solution, neutral solution and 3 mol L-1 NaOH solution and in the potential range between -0.95 and 1.35 V. The usable potential range is dependent on the pH value. Polyphenol has an ESR signal with a g factor of 2.0049. The conductivity of polyphenol is 1.2 x 10(-4) S cm(-1). In the solution of polyphenol dissolved in DMSO, the mobility of polyphenol anions is 8 x 10(-9) m(2) s(-1) V-1 at 20degreesC.
文摘The performance of rechargeable batteries and other electrochemical systems depends on the rate at which the working ion(often a cation)is transported from one electrode to the other.The cation transference number is an important transport parameter that affects this rate.The purpose of this perspective is to distinguish between approximate and rigorous methods used in the literature to measure the transference number.We emphasize the fact that this parameter is dependent on the reference frame used in the analysis;care must be taken when comparing values obtained from different sources to account for differences in reference frames.We present data obtained from a well-characterized electrolyte.We compare rigorously determined transference numbers in two reference frames with values obtained by an approximate method.We conclude with a qualitative discussion of the relationship between the transference number and salt concentration gradients that are obtained when current is drawn through a battery。
基金supported by the National Natural Science Foundation of China (No.11504434)the Natural Science Foundation of Hunan Province (No.2020JJ4935)。
文摘The cholesterol solution concentration sensing characteristics based on tilted fiber Bragg grating(TFBG) are investigated by means of theoretical analysis and experiments. We prepare two groups of cholesterol solutions with the same concentration range and different refractive index ranges. The sensitivity of the two groups of solutions was 11.83 pm·m L/mg and 124.79 pm·m L/mg, respectively. The results show that the sensitivity of cholesterol solution can be improved by adjusting the refractive index range. This conclusion is valuable for measuring the concentration of fat-soluble solution.
基金financial support by the Open Project Program of the State Key Laboratory of Solid Lu-brication, Lanzhou Institute of Chemical Physics,Chinese Academy of Sciences (0804)
文摘Selective-controlled structure and shape of CeVO4 nanocrystals were successfully synthesized via a hydrothermal method from Na3VO4·12H2O and Ce（NO3）3·6H2O.The resulting products were characterized by X-ray powder diffraction （XRD）,field emission scanning electron microscopy （FESEM） and energy dispersive spectroscopy （EDS）.The influence of hydrothermal temperature,precursor solution concentration on the crystal and morphology of products were further studied.The results showed that the as-synthesized products exhibited pure single-crystal CeVO4 nanoparticles with tetragonal structure.The hydrothermal temperature and precursor solution concentration had important effects on the formation of CeVO4 nanoparticles.Furthermore,the growth mechanism of CeVO4 nanoparticles was explained with Ostwald ripening mechanism.
基金The authors gratefully a.cknowledge financial supportfrom th6 Natiol-al Natural Science Foundatiol- of CI-h-a. The number of
文摘Based on the molecular theory of non-linear viscoelasticity with constrained entanglements in polymer melts, the material functions in simple shear flow were formulated, the theoretical relations between. eta((gamma) over dot), psi (10)((gamma) over dot) and shear rate ((gamma) over dot), and topologically constrained dimension number n ' and a were derived. Linear viscoelastic parameters (eta (0) and G(N)(0)) and topologically constrained dimension number (n ' a and <(<upsilon>)over bar>) as a function of the primary molecular weight (M-n), molecular weight between entanglements (M-C) and the entanglement sites sequence distribution in polymer chain were determined. A new method for determination of viscoelastic parameters (eta (0), psi (10), G(N)(0) and J(e)(0)), topologically constrained dimension number (n ', a and v) and molecular weight (M-n, M-c and M-e) from the shear flow measurements was proposed. It was used to determine those parameters and structures of HDPE, making a good agreement between these values and those obtained by other methods. The agreement affords a quantitative verification for the molecular theory of nonlinear viscoelasticity with constrained entanglement in polymer melts.
文摘An approach of stochastically statistical mechanics and a unified molecular theory of nonlinear viscoelasticity with constraints of Nagai chain entanglement for polymer melts have been proposed. A multimode model structure for a single polymer chain with n tail segments and N reversible entanglement sites on the test polymer chain is developed. Based on the above model structure and the mechanism of molecular flow by the dynamical reorganization of entanglement sites, the probability distribution function of the end-to-end vectr for a single polymer chain at entangled state and the viscoelastic free energy of deformation for polymer melts are calculated by using the method of the stochastically statistical mechanics. The four types of stress-strain relation and the memory function are derived from this thery. The above theoretical relations are verified by the experimentaf data for various polymer melts. These relations are found to be in good agreement with the experimental results
文摘Vertically oriented ZnO nanorods have been synthesized by hydrothermal method on quartz substrates with a seed layer. The influence of solution concentration on the morphology, structural and optical properties was analyzed. Results indicated that with the increase of solution concentration, the diameter and uniformity of ZnO nanorods increased. And the preferred orientation is obviously which shows better crystal quality. Typically, when the solution concentration is 0.03 mol/L, the nanorods exhibit a stronger UV emission peak located around 380 nm. In the visible region, all synthesized samples demonstrate more than 80% of optical transparency.
基金supported by the Beijing Natural Science Foun-dation(No.2214067)the National Key R&D Program of China(Nos.2021YFB3501502 and 2021YFB3501504)the National Natural Science Foundation of China(No.92163107).
文摘A model for describing solute segregation at grain boundaries has been developed for substitutional solid solution alloys,which integrates multiple factors from atomic to microstructural scales.A concept of mo-lar Gibbs free energy of segregation was introduced to evaluate the segregating capability of the solute elements in a closed system,through which the influences of grain boundary structure,grain size,ma-terial composition,and external conditions were described.Based on the evaluation of various energy forms related to solute segregation and grain growth processes,the nature of the thermal stabilization of nanograin structures by solute segregation was disclosed.A criterion for the destabilization of nanostruc-tures,which is determined by the competition of the change rates between the molar Gibbs free energy of segregation and the total energy of grain boundaries with grain size,has been proposed.This study provided guideline to achieve high-temperature stability of nanograin structures of solid solution alloys even for the weakly segregating nanocrystalline systems.
基金financially supported by the National Natural Scientific Foundation of China (Nos. 20934005 and 21274136)
文摘Linear triblock copolymers of poly（N-isopropylacrylamide） （PNIPAM） and poly（ethylene glycol） （PEG） with two azide groups at both block junctions （PNIPAM-N3-PEG-N3-PNIPAM） are click reacted with dipropargyl oxalylate under high polymer concentration （250 g/L）. Benefiting from rapid feature of alkyne-azide click reaction and spatial shielding of PNIPAM end blocks, PEG center block of PNIPAM-N3-PEG-N3-PNIPAM remains separated although PNIPAM end blocks keep in contact under this high concentration. Therefore, PNIPAM-N3-PEG-N3-PNIPAM undergoes self-cyclization at block junctions to form tadpole-shaped architecture while N3-PEG-N3 without PNIPAM end blocks inter-connects linearly. The influence of block lengths of PEG and PNIPAM on the unusual cyclization under high polymer concentration is studied.
