In this paper,a type of reinforcing structure for composite shell with single and through hole is presented.The experimental tests for the composite shells without hole,with single hole and reinforced structure,with t...In this paper,a type of reinforcing structure for composite shell with single and through hole is presented.The experimental tests for the composite shells without hole,with single hole and reinforced structure,with through hole and reinforced structure subjected to hydrostatic pressure were carried out by the designed experimental test system.The mechanical responses of the composite shells under hydrostatic pressure are obtained by the high-speed camera and strain measurement.The results show that the entire deformation process of the shell can be divided into three:uniform compression,"buckling mode formation"and buckling.The"buckling mode formation"process is captured and reported for the first time.For the composite shell with single hole,the proposed reinforcing structure has a significant reinforcement effect on the shell and the buckling capacity of the shell is not weaker than the complete composite shell.For the composite shell with through hole,sealing effect can be achieved by the proposed reinforcing structure,but the buckling capacity of the shell after reinforcement can only reach 77%of the original buckling capacity.展开更多
Enzymatic hydrolysis of proteins can enhance their emulsifying properties and antioxidant activities.However,the problem related to the hydrolysis of proteins was the generation of the bitter taste.Recently,high hydro...Enzymatic hydrolysis of proteins can enhance their emulsifying properties and antioxidant activities.However,the problem related to the hydrolysis of proteins was the generation of the bitter taste.Recently,high hydrostatic pressure(HHP)treatment has attracted much interest and has been used in several studies on protein modification.Hence,the study aimed to investigate the effects of enzymatic hydrolysis by Corolase PP under different pressure treatments(0.1,100,200,and 300 MPa for 1-5 h at 50℃)on the emulsifying property,antioxidant activity,and bitterness of soybean protein isolate hydrolysate(SPIH).As observed,the hydrolysate obtained at 200 MPa for 4 h had the highest emulsifying activity index(47.49 m^(2)/g)and emulsifying stability index(92.98%),and it had higher antioxidant activities(44.77%DPPH free radical scavenging activity,31.12%superoxide anion radical scavenging activity,and 61.50%copper ion chelating activity).At the same time,the enhancement of emulsion stability was related to the increase of zeta potential and the decrease of mean particle size.In addition,the hydrolysate obtained at 200 MPa for 4 h had a lower bitterness value and showed better palatability.This study has a broad application prospect in developing food ingredients and healthy foods.展开更多
The shear failure of rocks under both a static triaxial stress and a dynamic disturbance is common in deep underground engineering and it is therefore essential for the design of underground engineering to quantitivel...The shear failure of rocks under both a static triaxial stress and a dynamic disturbance is common in deep underground engineering and it is therefore essential for the design of underground engineering to quantitively estimate the dynamic ModeⅡfracture toughness KⅡCof rocks under a triaxial stress state.However,the method for determining the dynamic KⅡCof rocks under a triaxial stress has not been developed yet.With an optimal sample preparation,the short core in compression(SCC)method was designed and verified in this study to measure the dynamic KⅡCof Fangshan marble(FM)subjected to different hydrostatic pressures through a triaxial dynamic testing system.The formula for calculating the dynamic KⅡCof the rock SCC specimen under hydrostatic pressures was obtained by using the finite element method in combination with secondary cracks.The experimental results indicate that the failure mode of the rock SCC specimen under a hydrostatic pressure is the shear fracture and the KⅡCof FM increases as the loading rate.In addition,at a given loading rate the dynamic rock KⅡCis barely affected by hydrostatic pressures.Another important observation is that the dynamic fracture energy of FM enhances with loading rates and hydrostatic pressures.展开更多
The effect of hydrostatic pressure on the vibration dispersion characteristics of fluid-shell coupled structures was studied.Both fluid-loaded cylindrical shells and fluid-filled cylindrical shells were considered.Num...The effect of hydrostatic pressure on the vibration dispersion characteristics of fluid-shell coupled structures was studied.Both fluid-loaded cylindrical shells and fluid-filled cylindrical shells were considered.Numerical analysis was applied to solve the dispersion equations for shells filled with or loaded with fluid at various hydrostatic pressures.The results for external pressure showed that non-dimensional axial wave numbers are nearly independent when the pressure is below the critical level.The influence of internal pressure on wave numbers was found significant for the real branch s=1 and the complex branches of dispersion curves.The presence of internal pressure increased the cut on frequencies for the branch s=1 for high order wave modes.展开更多
As a non-thermal processing technology,high hydrostatic pressure(HHP)can be used for starch modification without affecting the quality and flavour constituents.The effect of HHP on starch is closely related to the tre...As a non-thermal processing technology,high hydrostatic pressure(HHP)can be used for starch modification without affecting the quality and flavour constituents.The effect of HHP on starch is closely related to the treatment time of HHP.In this paper,we investigated the impacts of HHP treatment time(0,5,10,15,20,25,30 min)on the microstructure,gelatinization and thermal properties as well as in vitro digestibility of oat starch by scanning electron microscopy,X-ray diffraction,Fourier transform infrared spectroscopy,13C NMR and differential scanning calorimeter.Results showed that 5-min HHP treatment led to deformation and decreases in short-range ordered and doublehelix structures of oat starch granules,and further extending the treatment time to 15 min or above caused the formation of a gelatinous connection zone,increase of particle size,disintegration of short-range ordered and double-helix structures,and crystal structure change from A type to V type,indicating gelatinization occurred.Longer treatment time also resulted in the reduction in both the viscosity and the stability of oat starch.These indicated that HHP treatment time greatly influenced the microstructure of oat starch,and the oat starch experienced crystalline destruction(5 min),crystalline disintegration(15 min)and gelatinization(>15 min)during HHP treatment.Results of in vitro digestibility showed that the rapidly digestible starch(RDS)content declined first after treatment for 5 to 10 min then rose with the time extending from 15 to 30 min,indicating that longer pressure treatment time was unfavourable to the health benefits of oat starch for humans with diabetes and cardiovascular disease.Therefore,the 500-MPa treatment time for oat starch is recommended not more than 15 min.This study provides theoretical guidance for the application of HHP technology in starch modification and development of health foods.展开更多
The initial geometric imperfection is one of the primary factors affecting the buckling behaviors of composite cylindrical shells under hydrostatic pressure.In this study,ovality and thickness variations as two repres...The initial geometric imperfection is one of the primary factors affecting the buckling behaviors of composite cylindrical shells under hydrostatic pressure.In this study,ovality and thickness variations as two representative types of the geometric imperfections are considered.After measuring the geometric imperfections,a typical carbon fiber reinforced polymers(CFRP)cylindrical shell is tested to obtain the buckling pressure.The buckling behaviors of the shell sample are analyzed in combination with the strain responses.By using the nonlinear numerical analysis,the buckling shapes of the CFRP cylinder shells with different combinations of ovality and thickness variation are firstly discussed.The rules of influence of such imperfections on the buckling pressure are then obtained by nonlinear regression method.Finally,an empirical formula is proposed to predict the buckling pressure of the composite cylinder shells,and the calculated results from the formula are in good agreement with the numerical results.展开更多
The electronic band structure of GaxIn1-xAs alloy is calculated by using the local empirical pseudo-potential method including the effective disorder potential in the virtual crystal approximation. The compositional e...The electronic band structure of GaxIn1-xAs alloy is calculated by using the local empirical pseudo-potential method including the effective disorder potential in the virtual crystal approximation. The compositional effect of the electronic energy band structure of this alloy is studied with composition x ranging from 0 to 1. Various physical quantities such as band gaps, bowing parameters, refractive indices, and high frequency dielectric constants of the considered alloys with different Ga concentrations are calculated. The effects of both temperature and hydrostatic pressure on the calculated quantities are studied. The obtained results are found to be in good agreement with the available experimental and published data.展开更多
We studied the structural and electronic properties of carbon nanotubes under hydrostatic pressures based on molecular dynamics simulations and first principles band structure calculations. It is found that carbon nan...We studied the structural and electronic properties of carbon nanotubes under hydrostatic pressures based on molecular dynamics simulations and first principles band structure calculations. It is found that carbon nanotubes experience a hard-to-soft transition as external pressure increases. The bulk modulus of soft phase is two orders of magnitude smaller than that of hard phase. The band structure calculations show that band gap of （10, 0） nanotube increases with the increase of pressure at low pressures. Above a critical pressure （5.70GPa）, band gap of （10, 0） nanotube drops rapidly and becomes zero at 6.62GPa. Moreover, the calculated charge density shows that a large pressure can induce an sp^2-to-sp^3 bonding transition, which is confirmed by recent experiments on deformed carbon nanotubes.展开更多
Band structure of wurtzite （WZ） GaAs nanowires （NWs） is investigated by using photoluminescenee measurements under hydrostatic pressure at 6 K. We demonstrate that WZ GaAs NWs have a direct bandgap transition with...Band structure of wurtzite （WZ） GaAs nanowires （NWs） is investigated by using photoluminescenee measurements under hydrostatic pressure at 6 K. We demonstrate that WZ GaAs NWs have a direct bandgap transition with an emission energy of 1.53eV, corresponding to the optical transition between conduction band Г7c and valence band Г9v in WZ GaAs. The direct-to-pseudodirect bandgap transition can be observed by applying a pressure approximately above 2.5 GPa.展开更多
The underwater anechoic coating technology,which considers pressure resistance and low-frequency broadband sound absorption,has become a research hotspot in underwater acoustics and has received wide attention to addr...The underwater anechoic coating technology,which considers pressure resistance and low-frequency broadband sound absorption,has become a research hotspot in underwater acoustics and has received wide attention to address the increasingly advanced low-frequency sonar detection technology and adapt to the working environment of underwater vehicles in deep submergence.One the one hand,controlling low-frequency sound waves in water is more challenging than in air.On the other hand,in addition to initiating structural deformation,hydrostatic pressure also changes material parameters,both of which have a major effect on the sound absorption performance of the anechoic coating.Therefore,resolving the pressure resistance and acoustic performance of underwater acoustic coatings is difficult.Particularly,a bottleneck problem that must be addressed in this field is the acoustic structure design with low-frequency broadband sound absorption under high hydrostatic pressure.Based on the influence of hydrostatic pressure on underwater anechoic coatings,the research status of underwater acoustic structures under hydrostatic pressure from the aspects of sound absorption mechanisms,analysis methods,and structural designs is reviewed in this paper.Finally,the challenges and research trends encountered by underwater anechoic coating technology under hydrostatic pressure are summarized,providing a reference for the design and research of low-frequency broadband anechoic coating.展开更多
Kondo semimetal CeRu4Sn6 is attracting renewed attention due to the theoretically predicted nontrivial topology in its electronic band structure. We report hydrostatic and chemical pressure effects on the transport pr...Kondo semimetal CeRu4Sn6 is attracting renewed attention due to the theoretically predicted nontrivial topology in its electronic band structure. We report hydrostatic and chemical pressure effects on the transport properties of single- and poly-crystalline samples. The electrical resistivity p （T） is gradually enhanced by applying pressure over a wide temperature range from room temperature down to 25 mK. Two thermal activation gaps estimated from high- and low-temperature windows are found to increase with pressure. A flat p（T） observed at the lowest temperatures below 300 mK appears to be robust against both pressure and field. This feature as well as the increase of the energy gaps calls for more intensive investigations with respect to electron correlations and band topology.展开更多
Deep petroleum resources are in a high-temperature environment.However,the traditional deep rock coring method has no temperature preserved measures and ignores the effect of temperature on rock porosity and permeabil...Deep petroleum resources are in a high-temperature environment.However,the traditional deep rock coring method has no temperature preserved measures and ignores the effect of temperature on rock porosity and permeability,which will lead to the distortion of the petroleum resources reserves assessment.Therefore,the hollow glass microspheres/epoxy resin(HGM/EP)composites were innovatively proposed as temperature preserved materials for in-situ temperature-preserved coring(ITP-Coring),and the physical,mechanical,and temperature preserved properties were evaluated.The results indicated that:As the HGM content increased,the density and mechanical properties of the composites gradually decreased,while the water absorption was deficient without hydrostatic pressure.For composites with 50 vol%HGM,when the hydrostatic pressure reached 60 MPa,the water absorption was above 30.19%,and the physical and mechanical properties of composites were weakened.When the hydrostatic pressure was lower than 40 MPa,the mechanical properties and thermal conductivity of composites were almost unchanged.Therefore,the composites with 50 vol%HGM can be used for ITPCoring operations in deep environments with the highest hydrostatic pressure of 40 MPa.Finally,to further understand the temperature preserved performance of composites in practical applications,the temperature preserved properties were measured.An unsteady-state heat transfer model was established based on the test results,then the theoretical change of the core temperature during the coring process was obtained.The above tests results can provide a research basis for deep rock in-situ temperature preserved corer and support accurate assessment of deep petroleum reserves.展开更多
The Al and La elements are added to the Sn9Zn alloy to obtain the fusible alloy for the mitigation devices of solid propellant rocket motors. Differential scanning calorimetry(DSC), metallographic analysis,scanning el...The Al and La elements are added to the Sn9Zn alloy to obtain the fusible alloy for the mitigation devices of solid propellant rocket motors. Differential scanning calorimetry(DSC), metallographic analysis,scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), tensile testing and fracture analysis were used to study the effect of Al and La elements on the microstructure, melting characteristics, and mechanical properties of the Sn9Zn alloy. Whether the fusible diaphragm can effectively relieve pressure was investigated by the hydrostatic pressure at high-temperature test. Experimental results show that the melting point of the Sn9Zn-0.8Al0·2La and Sn9Zn-3Al0·2La fusible alloys can meet the predetermined working temperature of ventilation. The mechanical properties of those are more than 35% higher than that of the Sn9Zn alloy at-50°C-70°C, and the mechanical strength is reduced by 80% at 175°C. It is proven by the hydrostatic pressure at high-temperature test that the fusible diaphragm can relieve pressure effectively and can be used for the design of the mitigation devices of solid propellant rocket motors.展开更多
Antiferroelectric ferroelectric （AFE-FE） phase transition in ceramic Pbo.97Lao.02（Zro.75Snon36Tion14）O3 （PLZST） was studied by dielectric spectroscopy as functions of frequency （102-105 Hz） and pressure （0-50...Antiferroelectric ferroelectric （AFE-FE） phase transition in ceramic Pbo.97Lao.02（Zro.75Snon36Tion14）O3 （PLZST） was studied by dielectric spectroscopy as functions of frequency （102-105 Hz） and pressure （0-500 MPa） under a DC electric field. The hydrostatic pressure-dependent remnant polarization and dielectric constant were mea- sured. The results show that remnant polarization of the metastable rhombohedral ferroelectric PLZST poled ceramic decreases sharply and depoles completely at phase transition under hydrostatic pressure. The dielectric constant um dergoes an abrupt jump twice during a load and unload cycle under an electric field. The two abrupt jumps correspond to two phase transitions, FE AFE and AFE-FE.展开更多
This paper investigates the pyroelectric of poled antiferroelectric （AFE） ceramic Pbo.97Lao.02 （Zro.69Sno.196 Ti0.114）03 and its remnant polarization dependence of hydrostatic pressure. The results show that the b...This paper investigates the pyroelectric of poled antiferroelectric （AFE） ceramic Pbo.97Lao.02 （Zro.69Sno.196 Ti0.114）03 and its remnant polarization dependence of hydrostatic pressure. The results show that the bound charges of poled sample can be released in short time by temperature field or pressure field. The released charge abruptly forms a large pulse current. The phenomena of released charge under external fields result in the ferroelectric-AFE phase transition induced by temperature or hydrostatic pressure.展开更多
The kagome metals AV_(3)Sb_(5)(A=K,Rb,Cs)under ambient pressure exhibit an unusual charge order,from which superconductivity emerges.In this work,by applying hydrostatic pressure using a liquid pressure medium and car...The kagome metals AV_(3)Sb_(5)(A=K,Rb,Cs)under ambient pressure exhibit an unusual charge order,from which superconductivity emerges.In this work,by applying hydrostatic pressure using a liquid pressure medium and carrying out electrical resistance measurements for RbV_(3)Sb_(5),we find that the charge order becomes suppressed under a modest pressure pc(1.4 GPa<pc<1.6 GPa),while the superconducting transition temperature Tc is maximized.Tc is then gradually weakened with further increase of pressure and reaches a minimum around 14.3 GPa,before exhibiting another{maximum}around 22.8 GPa,signifying the presence of a second superconducting dome.Distinct normal state resistance anomalies are found to be associated with the second superconducting dome,similar to KV_(3)Sb_(5).Our findings point to qualitatively similar temperature-pressure phase diagrams in KV_(3)Sb_(5) and RbV_(3)Sb_(5),{and suggest a close link}between the second superconducting dome and the high-pressure resistance anomalies.展开更多
Gas migration in coal bed is a multiple-physical process, of which not only includes gas desorption/diffusion through coal matrix and gas Darcy flow through the cleat system, but also results in deformation of solid c...Gas migration in coal bed is a multiple-physical process, of which not only includes gas desorption/diffusion through coal matrix and gas Darcy flow through the cleat system, but also results in deformation of solid coal. Especially for enhanced coal bed methane(ECBM) and CO2 capture and sequestration(CCS), gas injection is mainly controlled by the gas diffusivity in the coal matrix and coal permeability.Although the relevant coal permeability models have been frequently developed, how the dual-porosity system of coal affects gas adsorption/diffusion is still poorly understood. In this paper, a series of experiments were carried out in order to investigate deformation evolution of intact coal subjected to hydrostatic pressure of different gases(including pure H2, N2 and CO2) under isotherm injection. In the testing process, the coal strain and injected gas pressure were measured simultaneously. The results show that the pressure of non-adsorptive helium remained unchanged throughout the isothermal injection process, in which the volumetric strain of the coal shrinked firstly and maintained unchanged at lower isobaric pressure. With the injected pressure increasing, the coal volume underwent a transition from shrinking to recovery(still less than initial volume of the coal). In contrast, N2 injection caused the coal to shrink firstly and then recover with decreasing gas pressure. The recovery volume was larger than the initial volume due to adsorption-induced swelling. For the case of CO2 injection, although the stronger adsorption effect could result in swelling of the solid coal, the presence of higher gas pressure appears to contribute the swelling coal to shrink. These results indicate that the evolution of coal deformation is time dependent throughout the migration of injected gas. From the mechanical characteristics of poroelastical materials, distribution of pore pressure within the coal is to vary with the gas injection,during which the pore pressure in the cleats will rapidly increase, in contrast, the pore pressure in the matrix will hysteretically elevate. Such a difference on changes of pore pressure between the cleats and the matrix will contribute to the shrinkage of the matrix as a result of initially greater effective stress.Besides, both gas-adsorption-induced swelling and decreasing effective stress also control the coal deformation transition. This work gives us an insight into investigation on influence of effective stress on coal-gas interaction.展开更多
We established a novel droplet model (with-gravity model) to show the gravity effect of the droplet in the contact angle experiment.By using with-gravity model, we obtained a three-dimensional topography of the drople...We established a novel droplet model (with-gravity model) to show the gravity effect of the droplet in the contact angle experiment.By using with-gravity model, we obtained a three-dimensional topography of the droplet including the height of the droplet, the shape of the baseline and the circumference of the baseline.Comparing the with-gravity model with the ideal spherical model, our model considered the measurement error caused by gravity effect in the contact angle experiment which is a key point to influence the three-dimension topography of the droplet.From the calculation of our model, we found that there were two important points to enhance the measurement error: the size of the droplet and the contact angle.With the droplet and the contact angle became larger, measurement error was obviously increased.展开更多
基金supported by the Ningbo Major Research and Development Plan Project(Grant No.2024Z135)the Natural Science Basic Research Program of Shaanxi Province(Grant No.2024JC-YBMS-322)+1 种基金China Postdoctoral Science Foundation(Grant No.2020M673492)National Natural Science Foundation of China(Grant No.51909219)。
文摘In this paper,a type of reinforcing structure for composite shell with single and through hole is presented.The experimental tests for the composite shells without hole,with single hole and reinforced structure,with through hole and reinforced structure subjected to hydrostatic pressure were carried out by the designed experimental test system.The mechanical responses of the composite shells under hydrostatic pressure are obtained by the high-speed camera and strain measurement.The results show that the entire deformation process of the shell can be divided into three:uniform compression,"buckling mode formation"and buckling.The"buckling mode formation"process is captured and reported for the first time.For the composite shell with single hole,the proposed reinforcing structure has a significant reinforcement effect on the shell and the buckling capacity of the shell is not weaker than the complete composite shell.For the composite shell with through hole,sealing effect can be achieved by the proposed reinforcing structure,but the buckling capacity of the shell after reinforcement can only reach 77%of the original buckling capacity.
基金supported by the Doctoral Research Foundation of Bohai University (05013/0520bs006)the Science and Technology Project of“Unveiling and Commanding”Liaoning Province (2021JH1/10400033)the Scientific Research Project from Education Department of Liaoning Province (LJ2020010)。
文摘Enzymatic hydrolysis of proteins can enhance their emulsifying properties and antioxidant activities.However,the problem related to the hydrolysis of proteins was the generation of the bitter taste.Recently,high hydrostatic pressure(HHP)treatment has attracted much interest and has been used in several studies on protein modification.Hence,the study aimed to investigate the effects of enzymatic hydrolysis by Corolase PP under different pressure treatments(0.1,100,200,and 300 MPa for 1-5 h at 50℃)on the emulsifying property,antioxidant activity,and bitterness of soybean protein isolate hydrolysate(SPIH).As observed,the hydrolysate obtained at 200 MPa for 4 h had the highest emulsifying activity index(47.49 m^(2)/g)and emulsifying stability index(92.98%),and it had higher antioxidant activities(44.77%DPPH free radical scavenging activity,31.12%superoxide anion radical scavenging activity,and 61.50%copper ion chelating activity).At the same time,the enhancement of emulsion stability was related to the increase of zeta potential and the decrease of mean particle size.In addition,the hydrolysate obtained at 200 MPa for 4 h had a lower bitterness value and showed better palatability.This study has a broad application prospect in developing food ingredients and healthy foods.
基金supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)(No.72031326)the National Natural Science Foundation of China(No.52079091)+2 种基金supported by Academy of Finland under Grant No.322518supported by the opening project of State Key Laboratory of Explosion Science and Technology(Beijing Institute of Technology)The opening project number is KFJJ20-01M。
文摘The shear failure of rocks under both a static triaxial stress and a dynamic disturbance is common in deep underground engineering and it is therefore essential for the design of underground engineering to quantitively estimate the dynamic ModeⅡfracture toughness KⅡCof rocks under a triaxial stress state.However,the method for determining the dynamic KⅡCof rocks under a triaxial stress has not been developed yet.With an optimal sample preparation,the short core in compression(SCC)method was designed and verified in this study to measure the dynamic KⅡCof Fangshan marble(FM)subjected to different hydrostatic pressures through a triaxial dynamic testing system.The formula for calculating the dynamic KⅡCof the rock SCC specimen under hydrostatic pressures was obtained by using the finite element method in combination with secondary cracks.The experimental results indicate that the failure mode of the rock SCC specimen under a hydrostatic pressure is the shear fracture and the KⅡCof FM increases as the loading rate.In addition,at a given loading rate the dynamic rock KⅡCis barely affected by hydrostatic pressures.Another important observation is that the dynamic fracture energy of FM enhances with loading rates and hydrostatic pressures.
文摘The effect of hydrostatic pressure on the vibration dispersion characteristics of fluid-shell coupled structures was studied.Both fluid-loaded cylindrical shells and fluid-filled cylindrical shells were considered.Numerical analysis was applied to solve the dispersion equations for shells filled with or loaded with fluid at various hydrostatic pressures.The results for external pressure showed that non-dimensional axial wave numbers are nearly independent when the pressure is below the critical level.The influence of internal pressure on wave numbers was found significant for the real branch s=1 and the complex branches of dispersion curves.The presence of internal pressure increased the cut on frequencies for the branch s=1 for high order wave modes.
基金supported financially by the National Natural Science Foundation of China (Grant No.31760468 and32060515)Inner Mongolia Autonomous Region Science and Technology Plan Project (No.2020GG0064)
文摘As a non-thermal processing technology,high hydrostatic pressure(HHP)can be used for starch modification without affecting the quality and flavour constituents.The effect of HHP on starch is closely related to the treatment time of HHP.In this paper,we investigated the impacts of HHP treatment time(0,5,10,15,20,25,30 min)on the microstructure,gelatinization and thermal properties as well as in vitro digestibility of oat starch by scanning electron microscopy,X-ray diffraction,Fourier transform infrared spectroscopy,13C NMR and differential scanning calorimeter.Results showed that 5-min HHP treatment led to deformation and decreases in short-range ordered and doublehelix structures of oat starch granules,and further extending the treatment time to 15 min or above caused the formation of a gelatinous connection zone,increase of particle size,disintegration of short-range ordered and double-helix structures,and crystal structure change from A type to V type,indicating gelatinization occurred.Longer treatment time also resulted in the reduction in both the viscosity and the stability of oat starch.These indicated that HHP treatment time greatly influenced the microstructure of oat starch,and the oat starch experienced crystalline destruction(5 min),crystalline disintegration(15 min)and gelatinization(>15 min)during HHP treatment.Results of in vitro digestibility showed that the rapidly digestible starch(RDS)content declined first after treatment for 5 to 10 min then rose with the time extending from 15 to 30 min,indicating that longer pressure treatment time was unfavourable to the health benefits of oat starch for humans with diabetes and cardiovascular disease.Therefore,the 500-MPa treatment time for oat starch is recommended not more than 15 min.This study provides theoretical guidance for the application of HHP technology in starch modification and development of health foods.
基金supported by the National Natural Science Foundation of China(Grant No.51909219)the National Key Research and Development Program of China(Grant No.2016YFC0301300)+1 种基金Fundamental Research Funds for the Central Universities(Grant No.3102019JC006)China Postdoctoral Science Foundation(Grand No.2020M673492)。
文摘The initial geometric imperfection is one of the primary factors affecting the buckling behaviors of composite cylindrical shells under hydrostatic pressure.In this study,ovality and thickness variations as two representative types of the geometric imperfections are considered.After measuring the geometric imperfections,a typical carbon fiber reinforced polymers(CFRP)cylindrical shell is tested to obtain the buckling pressure.The buckling behaviors of the shell sample are analyzed in combination with the strain responses.By using the nonlinear numerical analysis,the buckling shapes of the CFRP cylinder shells with different combinations of ovality and thickness variation are firstly discussed.The rules of influence of such imperfections on the buckling pressure are then obtained by nonlinear regression method.Finally,an empirical formula is proposed to predict the buckling pressure of the composite cylinder shells,and the calculated results from the formula are in good agreement with the numerical results.
文摘The electronic band structure of GaxIn1-xAs alloy is calculated by using the local empirical pseudo-potential method including the effective disorder potential in the virtual crystal approximation. The compositional effect of the electronic energy band structure of this alloy is studied with composition x ranging from 0 to 1. Various physical quantities such as band gaps, bowing parameters, refractive indices, and high frequency dielectric constants of the considered alloys with different Ga concentrations are calculated. The effects of both temperature and hydrostatic pressure on the calculated quantities are studied. The obtained results are found to be in good agreement with the available experimental and published data.
基金supported by the National Natural Science Foundation of China (Grant Nos 10674070 and 10674113)the Scientific Research Fund of Hunan Provincial Education Department of China (Grant No 05C105)
文摘We studied the structural and electronic properties of carbon nanotubes under hydrostatic pressures based on molecular dynamics simulations and first principles band structure calculations. It is found that carbon nanotubes experience a hard-to-soft transition as external pressure increases. The bulk modulus of soft phase is two orders of magnitude smaller than that of hard phase. The band structure calculations show that band gap of （10, 0） nanotube increases with the increase of pressure at low pressures. Above a critical pressure （5.70GPa）, band gap of （10, 0） nanotube drops rapidly and becomes zero at 6.62GPa. Moreover, the calculated charge density shows that a large pressure can induce an sp^2-to-sp^3 bonding transition, which is confirmed by recent experiments on deformed carbon nanotubes.
基金Supported by the National Natural Science Foundation of China under Grant No 11474275
文摘Band structure of wurtzite （WZ） GaAs nanowires （NWs） is investigated by using photoluminescenee measurements under hydrostatic pressure at 6 K. We demonstrate that WZ GaAs NWs have a direct bandgap transition with an emission energy of 1.53eV, corresponding to the optical transition between conduction band Г7c and valence band Г9v in WZ GaAs. The direct-to-pseudodirect bandgap transition can be observed by applying a pressure approximately above 2.5 GPa.
基金Supported by the National Natural Science Foundation of China(Grant No.52271309)Natural Science Foundation of Heilongjiang Province of China(Grant No.YQ2022E104)Doctoral Science and Technology Innovation Fund of Harbin Engineering University(Grant No.3072023GIP0302).
文摘The underwater anechoic coating technology,which considers pressure resistance and low-frequency broadband sound absorption,has become a research hotspot in underwater acoustics and has received wide attention to address the increasingly advanced low-frequency sonar detection technology and adapt to the working environment of underwater vehicles in deep submergence.One the one hand,controlling low-frequency sound waves in water is more challenging than in air.On the other hand,in addition to initiating structural deformation,hydrostatic pressure also changes material parameters,both of which have a major effect on the sound absorption performance of the anechoic coating.Therefore,resolving the pressure resistance and acoustic performance of underwater acoustic coatings is difficult.Particularly,a bottleneck problem that must be addressed in this field is the acoustic structure design with low-frequency broadband sound absorption under high hydrostatic pressure.Based on the influence of hydrostatic pressure on underwater anechoic coatings,the research status of underwater acoustic structures under hydrostatic pressure from the aspects of sound absorption mechanisms,analysis methods,and structural designs is reviewed in this paper.Finally,the challenges and research trends encountered by underwater anechoic coating technology under hydrostatic pressure are summarized,providing a reference for the design and research of low-frequency broadband anechoic coating.
基金Project supported by the Ministry of Science and Technology of China(Grant Nos.2015CB921303 and 2017YFA0303103)the National Natural Science Foundation of China(Grant Nos.11474332 and 11774404)the Chinese Academy of Sciences through the Strategic Priority Research Program(Grant No.XDB07020200)
文摘Kondo semimetal CeRu4Sn6 is attracting renewed attention due to the theoretically predicted nontrivial topology in its electronic band structure. We report hydrostatic and chemical pressure effects on the transport properties of single- and poly-crystalline samples. The electrical resistivity p （T） is gradually enhanced by applying pressure over a wide temperature range from room temperature down to 25 mK. Two thermal activation gaps estimated from high- and low-temperature windows are found to increase with pressure. A flat p（T） observed at the lowest temperatures below 300 mK appears to be robust against both pressure and field. This feature as well as the increase of the energy gaps calls for more intensive investigations with respect to electron correlations and band topology.
基金National Natural Science Foundation of China(grant number 51827901)funded by the Program for Guangdong Introducing Innovative and Enterpreneurial Teams(No.2019ZT08G315)Shenzhen Basic Research Program(General Program)(No.JCYJ20190808153416970)
文摘Deep petroleum resources are in a high-temperature environment.However,the traditional deep rock coring method has no temperature preserved measures and ignores the effect of temperature on rock porosity and permeability,which will lead to the distortion of the petroleum resources reserves assessment.Therefore,the hollow glass microspheres/epoxy resin(HGM/EP)composites were innovatively proposed as temperature preserved materials for in-situ temperature-preserved coring(ITP-Coring),and the physical,mechanical,and temperature preserved properties were evaluated.The results indicated that:As the HGM content increased,the density and mechanical properties of the composites gradually decreased,while the water absorption was deficient without hydrostatic pressure.For composites with 50 vol%HGM,when the hydrostatic pressure reached 60 MPa,the water absorption was above 30.19%,and the physical and mechanical properties of composites were weakened.When the hydrostatic pressure was lower than 40 MPa,the mechanical properties and thermal conductivity of composites were almost unchanged.Therefore,the composites with 50 vol%HGM can be used for ITPCoring operations in deep environments with the highest hydrostatic pressure of 40 MPa.Finally,to further understand the temperature preserved performance of composites in practical applications,the temperature preserved properties were measured.An unsteady-state heat transfer model was established based on the test results,then the theoretical change of the core temperature during the coring process was obtained.The above tests results can provide a research basis for deep rock in-situ temperature preserved corer and support accurate assessment of deep petroleum reserves.
基金the National Natural Science Foundation of China (Grant No. 11772058)。
文摘The Al and La elements are added to the Sn9Zn alloy to obtain the fusible alloy for the mitigation devices of solid propellant rocket motors. Differential scanning calorimetry(DSC), metallographic analysis,scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), tensile testing and fracture analysis were used to study the effect of Al and La elements on the microstructure, melting characteristics, and mechanical properties of the Sn9Zn alloy. Whether the fusible diaphragm can effectively relieve pressure was investigated by the hydrostatic pressure at high-temperature test. Experimental results show that the melting point of the Sn9Zn-0.8Al0·2La and Sn9Zn-3Al0·2La fusible alloys can meet the predetermined working temperature of ventilation. The mechanical properties of those are more than 35% higher than that of the Sn9Zn alloy at-50°C-70°C, and the mechanical strength is reduced by 80% at 175°C. It is proven by the hydrostatic pressure at high-temperature test that the fusible diaphragm can relieve pressure effectively and can be used for the design of the mitigation devices of solid propellant rocket motors.
基金Project supported by the National Basic Research Program of China (Grant No.2009CB623306)the International Science & Technology Cooperation Program of China (Grant No.2010DFR50480)the National Natural Science Foundation of China (Grant No.10976022)
文摘Antiferroelectric ferroelectric （AFE-FE） phase transition in ceramic Pbo.97Lao.02（Zro.75Snon36Tion14）O3 （PLZST） was studied by dielectric spectroscopy as functions of frequency （102-105 Hz） and pressure （0-500 MPa） under a DC electric field. The hydrostatic pressure-dependent remnant polarization and dielectric constant were mea- sured. The results show that remnant polarization of the metastable rhombohedral ferroelectric PLZST poled ceramic decreases sharply and depoles completely at phase transition under hydrostatic pressure. The dielectric constant um dergoes an abrupt jump twice during a load and unload cycle under an electric field. The two abrupt jumps correspond to two phase transitions, FE AFE and AFE-FE.
基金supported by the National Basic Research Program of China (973 Program) (Grant No. 2009CB623306)the National Natural Science Foundation of China (Grant No. 60528008)+1 种基金the Key Science and Technology Research Project from the Ministry of Education of China (Grant No. 108180)the National Natural Science Foundation of China-NSAF (Grant No. 10976022)
文摘This paper investigates the pyroelectric of poled antiferroelectric （AFE） ceramic Pbo.97Lao.02 （Zro.69Sno.196 Ti0.114）03 and its remnant polarization dependence of hydrostatic pressure. The results show that the bound charges of poled sample can be released in short time by temperature field or pressure field. The released charge abruptly forms a large pulse current. The phenomena of released charge under external fields result in the ferroelectric-AFE phase transition induced by temperature or hydrostatic pressure.
基金the National Key R&D Program of China(Grant Nos.2017YFA0303100 and 2016YFA0300202)the Key R&D Program of Zhejiang Province,China(Grant No.2021C01002)+3 种基金the National Natural Science Foundation of China(Grant Nos.11974306 and 12034017)the Fundamental Research Funds for the Central Universities of Chinasupport via the UC Santa Barbara NSF Quantum Foundry funded via the Q-AMASE-i program under award DMR-1906325support from the California Nano Systems Institute through the Elings fellowship program。
文摘The kagome metals AV_(3)Sb_(5)(A=K,Rb,Cs)under ambient pressure exhibit an unusual charge order,from which superconductivity emerges.In this work,by applying hydrostatic pressure using a liquid pressure medium and carrying out electrical resistance measurements for RbV_(3)Sb_(5),we find that the charge order becomes suppressed under a modest pressure pc(1.4 GPa<pc<1.6 GPa),while the superconducting transition temperature Tc is maximized.Tc is then gradually weakened with further increase of pressure and reaches a minimum around 14.3 GPa,before exhibiting another{maximum}around 22.8 GPa,signifying the presence of a second superconducting dome.Distinct normal state resistance anomalies are found to be associated with the second superconducting dome,similar to KV_(3)Sb_(5).Our findings point to qualitatively similar temperature-pressure phase diagrams in KV_(3)Sb_(5) and RbV_(3)Sb_(5),{and suggest a close link}between the second superconducting dome and the high-pressure resistance anomalies.
基金founded by the National Natural Science Foundation of China(Nos.41202194,41172116,and2013M542097)the Natural Science Foundation of Shandong Province,China(No.ZR2012EEQ021)+1 种基金‘‘Leading Talent Plan’’ of Shandong University of Science and Technology,Chinaresearch groups for ‘‘Taishan Scholar’’ and ‘‘Controlon Instability of Deep Surrounding Rocks’’ of SDUST
文摘Gas migration in coal bed is a multiple-physical process, of which not only includes gas desorption/diffusion through coal matrix and gas Darcy flow through the cleat system, but also results in deformation of solid coal. Especially for enhanced coal bed methane(ECBM) and CO2 capture and sequestration(CCS), gas injection is mainly controlled by the gas diffusivity in the coal matrix and coal permeability.Although the relevant coal permeability models have been frequently developed, how the dual-porosity system of coal affects gas adsorption/diffusion is still poorly understood. In this paper, a series of experiments were carried out in order to investigate deformation evolution of intact coal subjected to hydrostatic pressure of different gases(including pure H2, N2 and CO2) under isotherm injection. In the testing process, the coal strain and injected gas pressure were measured simultaneously. The results show that the pressure of non-adsorptive helium remained unchanged throughout the isothermal injection process, in which the volumetric strain of the coal shrinked firstly and maintained unchanged at lower isobaric pressure. With the injected pressure increasing, the coal volume underwent a transition from shrinking to recovery(still less than initial volume of the coal). In contrast, N2 injection caused the coal to shrink firstly and then recover with decreasing gas pressure. The recovery volume was larger than the initial volume due to adsorption-induced swelling. For the case of CO2 injection, although the stronger adsorption effect could result in swelling of the solid coal, the presence of higher gas pressure appears to contribute the swelling coal to shrink. These results indicate that the evolution of coal deformation is time dependent throughout the migration of injected gas. From the mechanical characteristics of poroelastical materials, distribution of pore pressure within the coal is to vary with the gas injection,during which the pore pressure in the cleats will rapidly increase, in contrast, the pore pressure in the matrix will hysteretically elevate. Such a difference on changes of pore pressure between the cleats and the matrix will contribute to the shrinkage of the matrix as a result of initially greater effective stress.Besides, both gas-adsorption-induced swelling and decreasing effective stress also control the coal deformation transition. This work gives us an insight into investigation on influence of effective stress on coal-gas interaction.
基金Funded by Beijing Natural Science Foundation (No. 2062004)National Natural Science Foundation of China (No. 50502001 and No. 60576012)+1 种基金the Fundamental Research Funds for the Central UniversitiesNorth China Institute of Science and Technology (No. 2011B24)
文摘We established a novel droplet model (with-gravity model) to show the gravity effect of the droplet in the contact angle experiment.By using with-gravity model, we obtained a three-dimensional topography of the droplet including the height of the droplet, the shape of the baseline and the circumference of the baseline.Comparing the with-gravity model with the ideal spherical model, our model considered the measurement error caused by gravity effect in the contact angle experiment which is a key point to influence the three-dimension topography of the droplet.From the calculation of our model, we found that there were two important points to enhance the measurement error: the size of the droplet and the contact angle.With the droplet and the contact angle became larger, measurement error was obviously increased.
