The three-level shaft of the mixed pit shaft of Yixin Mine,built in 1983,failed continuously due to the influence of geological structure and the effect of water,which formed a collapsed space with a length of 18m,a d...The three-level shaft of the mixed pit shaft of Yixin Mine,built in 1983,failed continuously due to the influence of geological structure and the effect of water,which formed a collapsed space with a length of 18m,a depth of 12m,and a height of 12m at the level of-255m and to the southwest end.The 54m pit shaft below the-258m elevation of the pit shaft was filled with collapsed rocks forming a large loose body.The comprehensive processing plan for falling grouting and anchoring was proposed according to the geological conditions of the vertical shaft of the mixed pit shaft,adopting three-dimensional numerical simulation software as well as calculating the mechanical state of the vertical pit shaft surrounding rocks and using 3 to 5 parameters of Williams-Warnke failure criterion.展开更多
In order to prepare fluorescent material for white Light Emitting Diodes （LEDs）, a new Eu^3＋ activated molybdate phosphor SrMoO4 was fabricated with solid-state method. X-ray diffraction （XRD） showed that the dop...In order to prepare fluorescent material for white Light Emitting Diodes （LEDs）, a new Eu^3＋ activated molybdate phosphor SrMoO4 was fabricated with solid-state method. X-ray diffraction （XRD） showed that the doping of trivalent europium ion reduced the lattice parameters. The excitation and emission spectra indicated that this phosphor could be excited effectively by the visible light, and then emitted red light with the peaks located at 616 and 624 nm. The influence of Eu^3＋ concentration on the luminescent properties of Eu^3＋ doped SrMoO4 was investigated and the 25% （mole fraction） was the appropriate molar concentration. The reaction time and temperature had obvious effect on the luminescent properties. The luminescent intensity reached the strongest when it was sintered at 800 ℃ for 3 h.展开更多
The applications of carbon ion beam in tumor therapy have attracted more attention in recent years.Monte Carlo simulation is an important approach to obtain accurate radiotherapy parameters. In this work, a400 Me V/u ...The applications of carbon ion beam in tumor therapy have attracted more attention in recent years.Monte Carlo simulation is an important approach to obtain accurate radiotherapy parameters. In this work, a400 Me V/u carbon ion beam incident on water phantom was simulated with Gate/Geant4 tools. In methods, the authors set up a carbon ion beam source according to the experiment parameters of Haettner, defined the geometries and materials, set up the physics processes, and designed the means of information collection. In results,the authors obtained the longitudinal dose distribution, the lateral dose distribution, and the relative uncertainty of dose. The dose contributions of all kinds of fragments were calculated detailedly and compared with the Francis results. This work is helpful for people's understanding of the dose distributions produced by carbon ion beam and fragments in water. The simulation method is also significative for radiotherapy treatment planning of carbon ion beam, and it is easy to extend. For obtaining a special result, we may change the particle energy, particle type,target material, target geometry, physics process, detector,etc.展开更多
The front-end conditioner is an essential part of digital systems of nuclear spectrometer, which functions in two ways: (1) prevents saturation of the subsequent ADC; (2) limits the bandwidth of frequency to realize a...The front-end conditioner is an essential part of digital systems of nuclear spectrometer, which functions in two ways: (1) prevents saturation of the subsequent ADC; (2) limits the bandwidth of frequency to realize anti-aliasing. To realize the above-mentioned functions, an optimum front-end conditioner for a resistive feedback charge-sensitive preamplifier is designed. In the conditioner, the pole-zero compensation (P/Z compensation) tech- nique was used to effectively filter signals from the preamplifier. The Butterworth filter was improved after the pole-zero position was optimally set up to shape the wave of output, which tallied with the whole system. The front-end conditioner can resolve the aberration of waveform of nuclear signals in a regular Butterworth filter. Com- pared with the traditional triple-pole filtering circuitry, the circuitry of this conditioner is more compact and flexible. Moreover, its output waveform is more symmetrical and the signal-to-noise ratio (SNR) is higher. The improvement in the resolution of spectrometer is also significant.展开更多
By employing non-equilibrium Green＇s function combined with the spin-polarized density-functional theory, we investigate the spin-dependent electronic transport properties of armchair arsenene nanoribbons（a As NRs）...By employing non-equilibrium Green＇s function combined with the spin-polarized density-functional theory, we investigate the spin-dependent electronic transport properties of armchair arsenene nanoribbons（a As NRs）. Our results show that the spin-metal and spin-semiconductor properties can be observed in a As NRs with different widths. We also find that there is nearly 100% bipolar spin-filtering behavior in the a As NR-based device with antiparallel spin configuration. Moreover, rectifying behavior and giant magnetoresistance are found in the device. The corresponding physical analyses have been given.展开更多
Sustainable,environmentally friendly and low-energy desalination materials have important research value for the increasing demand of freshwater year by year.However,it is a huge challenge to maintain high heat energy...Sustainable,environmentally friendly and low-energy desalination materials have important research value for the increasing demand of freshwater year by year.However,it is a huge challenge to maintain high heat energy transfer efficiency without reducing the heat conversion capacity of specific solar photothermal conversion materials.Moreover,their efficiency and durability are greatly limited by the problems of seawater corrosion,oil,and bacteria pollutions.Till now,no related work has been reported to solve all the aforementioned problems via a simple four-birds-with-one-stone strategy.Herein,a class of multifunctional porous photothermal silver(Ag)modified Ti foams(Tf-TA/Ag series materials)is prepared for the development of advanced solar water evaporation devices,and provides alternative materials for alleviating freshwater crisis and treating sewage.The oil contact angle(OCA)changes from 41°to 180°,which significantly reduces the adhesion of oil.In addition,Tf-TA2/Ag sample also shows an excellent and sustained antibacterial effect,which maintains above 99.9%of antibacterial rate after repeated 5 times.The surface temperature of the Tf-TA2/Ag sample reaches 52.5℃ after simulated sun irradiation for 20 min,which is significantly higher than that of the contact groups(water:36.4℃,Ti foam:38.2℃ and Tf-TA2:40.9℃).The capacity of seawater evaporation and salt removal is enhanced due to the excellent photothermal properties,low reflectance,and uniform heat dissipation pores.The water production efficiency of Tf-TA2/Ag sample is 1.41 kg·m^(-2)·h^(-1) in artificial seawater and 0.76 kg·m^(-2)·h^(-1) in oily sewage under simulated sun irradiation.Furthermore,the hydrophilic and oleophobic properties of Tf-TA2/Ag are critical to extracting water from oil/water mixture in diverse water environments.Ultimately,this four-birds-with-one-stone approach provides a new perspective for the improvement of solar seawater desalination performance.展开更多
Mg-4.0Zn alloy composite reinforced by NiO-coated CNTs （NiO@CNTs） was synthesized by combining ball-milling and a casting process. The yield strength （YS） and elongation to failure of the composite were dramatical...Mg-4.0Zn alloy composite reinforced by NiO-coated CNTs （NiO@CNTs） was synthesized by combining ball-milling and a casting process. The yield strength （YS） and elongation to failure of the composite were dramatically increased by 44.9% and 38.6%, respectively, compared to its alloy counterpart. The signifi- cantly eahanced mechanical properties of the as-synthesized composite are mainly ascribed to an improved interracial bond, grain refinement and good dispersion of CNTs in the matrix via. coating NiO on CNTs. It is shown that the NiO-nanolayer on the CNTs significantly enhances the interfacial bonding strength and effectively prevents the agglomeration of CNTs. NiO@CNTs are, therefore, expected to be a highly sustainable and dispersible reinforcement for magnesium matrix composites with superior performance.展开更多
The morphological evolution of Fe-rich phases in the Alalloy has been investigated with various contents of Fe,Mn,and Cr.The results show that coarse Chinese script Fe-rich phases appear in the alloy with 0.6 wt%Fe co...The morphological evolution of Fe-rich phases in the Alalloy has been investigated with various contents of Fe,Mn,and Cr.The results show that coarse Chinese script Fe-rich phases appear in the alloy with 0.6 wt%Fe combined with trace Mn,while the blocky Fe-rich phases appear combined with trace Cr.Under the coexistence of trace Mn and Cr,a large number of fine Chinese script Fe-rich phases could be visible in the low iron-bearing AlSi_9Cu_3-alloy（0.60 wt%）.At high Fe level（1.30 wt%）,numerous Fe-rich phases with hexagonal morphologies are observed with the trace Cr,while fish-bone and pentagonal morphologies of Fe-rich phases could be simultaneously observed with the addition of both Mn and Cr.The results reveal that the trace Mn and Cr promote the morphological evolution of Fe-rich phases.The morphology evolution mechanism of Fe-rich phases has been discussed by using the atom radius and electronegativity differences of Fe,Mn,and Cr.展开更多
Positron emission tomography （PET） imaging of functional metabolism has been widely used to investigate functional recovery and to evaluate therapeutic efficacy after stroke. The voxel intensity of a PET image is th...Positron emission tomography （PET） imaging of functional metabolism has been widely used to investigate functional recovery and to evaluate therapeutic efficacy after stroke. The voxel intensity of a PET image is the most important indicator of cellular activity, but is affected by other factors such as the basal metabolic ratio of each subject. In order to locate dysfunctional regions accurately, intensity normalization by a scale factor is a prerequisite in the data analysis, for which the global mean value is most widely used. However, this is unsuitable for stroke studies. Alternatively, a specified scale factor calculated from a reference region is also used, comprising neither hyper- nor hypo-metabolic voxels. But there is no such recognized reference region for stroke studies. Therefore, we proposed a totally data-driven automatic method for unbiased scale factor generation. This factor was generated iteratively until the residual deviation of two adjacent scale factors was reduced by 〈 5%. Moreover, both simulated and real stroke data were used for evaluation, and these suggested that our proposed unbiased scale factor has better sensi- tivity and accuracy for stroke studies.展开更多
Melt processing is a promising process to fabricate Mg-CNTs(carbon nanotubes)composites with high performance and large dimensions.In this work,the liquidmixing technique and ball-milling processes as well as the stir...Melt processing is a promising process to fabricate Mg-CNTs(carbon nanotubes)composites with high performance and large dimensions.In this work,the liquidmixing technique and ball-milling processes as well as the stirring casting method were used to prepare ZM1-1.0 CNTs-L and ZM1-1.0 CNTs-B composites,respectively.The composites were studied using optical microscopy(OM),Raman spectroscopy,scanning electron microscope(SEM),transmission electron microscope(TEM)and room-temperature tensile test.The results show that the yield strength(YS),ultimate tensile strength(UTS),elongation and microhardness values of the ZM1-1.OCNTs-L composite are improved by 37.3%,29.6%,37.0%and33.3%,respectively,compared with those of ZM1 alloy.The uniform dispersion of CNTs as well as the strong interfacial bonds with the Mg matrix is the main reason for the significant improvement in mechanical properties of the as-cast composite.Liquid mixing combined with the stirring casting method is favorable to fabricate Mg-CNTs composite with high mechanical properties.展开更多
Oil-based nanofluids including 0.75%—1.75%(mass fraction) carbon nanotubes(CNTs) without any surfactants have been synthesized by a two-step process. The probes machined from 45~# steel with 22 mm diameter and 50 mm ...Oil-based nanofluids including 0.75%—1.75%(mass fraction) carbon nanotubes(CNTs) without any surfactants have been synthesized by a two-step process. The probes machined from 45~# steel with 22 mm diameter and 50 mm length are quenched in the as-synthesized CNT nanofluids for testing the cooling behaviors of the nanofluids. The laser diffraction particle size analyzer, scanning electronic microscope(SEM), X-ray diffractometer and transmission electron microscope(TEM) are used to characterize the quality and distribution of CNTs in the nanofluids. The wettability and viscosity of 30~# oil and oil-based CNT nanofluids are measured by a goniometer at 15℃ and a rotational type viscometer at 40℃, respectively. The results show that the cooling efficiency of the oil-based CNT nanofluids is better than that of 30~# oil. Moreover, the cooling rate of the naonofluids increases with the further increase of the CNT concentration. When the mass fraction of CNTs increases to 1.75%, the cooling rate of the naonofluids reaches a maximum at 760℃ and it is increased by 77.8% as compared to that of base oil. The improved cooling rate of oil by CNTs is mainly due to the uniform distribution and excellent thermal conductivity of CNTs.展开更多
文摘The three-level shaft of the mixed pit shaft of Yixin Mine,built in 1983,failed continuously due to the influence of geological structure and the effect of water,which formed a collapsed space with a length of 18m,a depth of 12m,and a height of 12m at the level of-255m and to the southwest end.The 54m pit shaft below the-258m elevation of the pit shaft was filled with collapsed rocks forming a large loose body.The comprehensive processing plan for falling grouting and anchoring was proposed according to the geological conditions of the vertical shaft of the mixed pit shaft,adopting three-dimensional numerical simulation software as well as calculating the mechanical state of the vertical pit shaft surrounding rocks and using 3 to 5 parameters of Williams-Warnke failure criterion.
基金Project supported by the Hebei Developing Foundation of Science &Technology (51215103b)
文摘In order to prepare fluorescent material for white Light Emitting Diodes （LEDs）, a new Eu^3＋ activated molybdate phosphor SrMoO4 was fabricated with solid-state method. X-ray diffraction （XRD） showed that the doping of trivalent europium ion reduced the lattice parameters. The excitation and emission spectra indicated that this phosphor could be excited effectively by the visible light, and then emitted red light with the peaks located at 616 and 624 nm. The influence of Eu^3＋ concentration on the luminescent properties of Eu^3＋ doped SrMoO4 was investigated and the 25% （mole fraction） was the appropriate molar concentration. The reaction time and temperature had obvious effect on the luminescent properties. The luminescent intensity reached the strongest when it was sintered at 800 ℃ for 3 h.
基金supported by the National Natural Science Foundation of China(No.H1809)
文摘The applications of carbon ion beam in tumor therapy have attracted more attention in recent years.Monte Carlo simulation is an important approach to obtain accurate radiotherapy parameters. In this work, a400 Me V/u carbon ion beam incident on water phantom was simulated with Gate/Geant4 tools. In methods, the authors set up a carbon ion beam source according to the experiment parameters of Haettner, defined the geometries and materials, set up the physics processes, and designed the means of information collection. In results,the authors obtained the longitudinal dose distribution, the lateral dose distribution, and the relative uncertainty of dose. The dose contributions of all kinds of fragments were calculated detailedly and compared with the Francis results. This work is helpful for people's understanding of the dose distributions produced by carbon ion beam and fragments in water. The simulation method is also significative for radiotherapy treatment planning of carbon ion beam, and it is easy to extend. For obtaining a special result, we may change the particle energy, particle type,target material, target geometry, physics process, detector,etc.
文摘The front-end conditioner is an essential part of digital systems of nuclear spectrometer, which functions in two ways: (1) prevents saturation of the subsequent ADC; (2) limits the bandwidth of frequency to realize anti-aliasing. To realize the above-mentioned functions, an optimum front-end conditioner for a resistive feedback charge-sensitive preamplifier is designed. In the conditioner, the pole-zero compensation (P/Z compensation) tech- nique was used to effectively filter signals from the preamplifier. The Butterworth filter was improved after the pole-zero position was optimally set up to shape the wave of output, which tallied with the whole system. The front-end conditioner can resolve the aberration of waveform of nuclear signals in a regular Butterworth filter. Com- pared with the traditional triple-pole filtering circuitry, the circuitry of this conditioner is more compact and flexible. Moreover, its output waveform is more symmetrical and the signal-to-noise ratio (SNR) is higher. The improvement in the resolution of spectrometer is also significant.
基金Supported by the Special Funds for Major State Basic Research Project under Grant No 2007CB924901, the National Natural Science Foundation of China under Grant No 60221502, the Knowledge Innovation Programme of Chinese Academy of Sciences under Grant No C2-12, and Science and Technology Commission of Shanghai under Grant No 07JC14059.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21673296 and 11334014)the Science and Technology Plan of Hunan Province,China(Grant No.2015RS4002)the Postdoctoral Science Foundation of Central South University,China
文摘By employing non-equilibrium Green＇s function combined with the spin-polarized density-functional theory, we investigate the spin-dependent electronic transport properties of armchair arsenene nanoribbons（a As NRs）. Our results show that the spin-metal and spin-semiconductor properties can be observed in a As NRs with different widths. We also find that there is nearly 100% bipolar spin-filtering behavior in the a As NR-based device with antiparallel spin configuration. Moreover, rectifying behavior and giant magnetoresistance are found in the device. The corresponding physical analyses have been given.
基金supported by the National Natural Science Foundation of China (12264052)the Science and Technology Research Project of Jiangxi Provincial Department of Education (GJJ211607)。
基金supported by the National Natural Science Foundation of China(Nos.52263032,62062053,22375109,52061034)the Natural Science Foundation of Inner Mongolia Province(Nos.2020BS01004,2022QN03012)Young Science and Technology Talent Program of Inner Mongolia Province(No.NJYT23001)and a Talent Development Fund of Inner Mongolia Province.
文摘Sustainable,environmentally friendly and low-energy desalination materials have important research value for the increasing demand of freshwater year by year.However,it is a huge challenge to maintain high heat energy transfer efficiency without reducing the heat conversion capacity of specific solar photothermal conversion materials.Moreover,their efficiency and durability are greatly limited by the problems of seawater corrosion,oil,and bacteria pollutions.Till now,no related work has been reported to solve all the aforementioned problems via a simple four-birds-with-one-stone strategy.Herein,a class of multifunctional porous photothermal silver(Ag)modified Ti foams(Tf-TA/Ag series materials)is prepared for the development of advanced solar water evaporation devices,and provides alternative materials for alleviating freshwater crisis and treating sewage.The oil contact angle(OCA)changes from 41°to 180°,which significantly reduces the adhesion of oil.In addition,Tf-TA2/Ag sample also shows an excellent and sustained antibacterial effect,which maintains above 99.9%of antibacterial rate after repeated 5 times.The surface temperature of the Tf-TA2/Ag sample reaches 52.5℃ after simulated sun irradiation for 20 min,which is significantly higher than that of the contact groups(water:36.4℃,Ti foam:38.2℃ and Tf-TA2:40.9℃).The capacity of seawater evaporation and salt removal is enhanced due to the excellent photothermal properties,low reflectance,and uniform heat dissipation pores.The water production efficiency of Tf-TA2/Ag sample is 1.41 kg·m^(-2)·h^(-1) in artificial seawater and 0.76 kg·m^(-2)·h^(-1) in oily sewage under simulated sun irradiation.Furthermore,the hydrophilic and oleophobic properties of Tf-TA2/Ag are critical to extracting water from oil/water mixture in diverse water environments.Ultimately,this four-birds-with-one-stone approach provides a new perspective for the improvement of solar seawater desalination performance.
基金supported by the National Key Research and Development Program(Nos.2016YFB0701201,2016YFB0701203)National Natural Science Foundation of China(Nos.51671101,51464034)+2 种基金Natural Science foundation of Jiangxi Province(No.20161ACB21003)Excellent Young Talent plan of Jiangxi Province(No.20162BCB23013)the Scientific Research Foundation of the Education Department of Jiangxi Province(Nos.GJJ151309,GJJ150010)
文摘Mg-4.0Zn alloy composite reinforced by NiO-coated CNTs （NiO@CNTs） was synthesized by combining ball-milling and a casting process. The yield strength （YS） and elongation to failure of the composite were dramatically increased by 44.9% and 38.6%, respectively, compared to its alloy counterpart. The signifi- cantly eahanced mechanical properties of the as-synthesized composite are mainly ascribed to an improved interracial bond, grain refinement and good dispersion of CNTs in the matrix via. coating NiO on CNTs. It is shown that the NiO-nanolayer on the CNTs significantly enhances the interfacial bonding strength and effectively prevents the agglomeration of CNTs. NiO@CNTs are, therefore, expected to be a highly sustainable and dispersible reinforcement for magnesium matrix composites with superior performance.
基金supported by the National Key Research and Development Plan (Nos. 2017YFB1103701, 2016YFB0701201, 2016YFB0701203)the National Natural Science Foundation of China (Nos. 51671101, 51464034, 51761037)+3 种基金the Natural Science Foundation of Jiangxi Province (Nos. 20161ACB21003, 20162BCB23013, and 20172BCB22002)the Scientific Research Foundation of the Education Department of Jiangxi Province (No. GJJ150010)the Innovative Funding for Graduate Students in Nanchang University (No. cx2016089)the Funding of Key Laboratory of Superlight Materials & Surface Technology (Harbin Engineering University), Ministry of Education
文摘The morphological evolution of Fe-rich phases in the Alalloy has been investigated with various contents of Fe,Mn,and Cr.The results show that coarse Chinese script Fe-rich phases appear in the alloy with 0.6 wt%Fe combined with trace Mn,while the blocky Fe-rich phases appear combined with trace Cr.Under the coexistence of trace Mn and Cr,a large number of fine Chinese script Fe-rich phases could be visible in the low iron-bearing AlSi_9Cu_3-alloy（0.60 wt%）.At high Fe level（1.30 wt%）,numerous Fe-rich phases with hexagonal morphologies are observed with the trace Cr,while fish-bone and pentagonal morphologies of Fe-rich phases could be simultaneously observed with the addition of both Mn and Cr.The results reveal that the trace Mn and Cr promote the morphological evolution of Fe-rich phases.The morphology evolution mechanism of Fe-rich phases has been discussed by using the atom radius and electronegativity differences of Fe,Mn,and Cr.
基金supported by the National Natural Science Foundation of China(81471741,81471728,and81671770)
文摘Positron emission tomography （PET） imaging of functional metabolism has been widely used to investigate functional recovery and to evaluate therapeutic efficacy after stroke. The voxel intensity of a PET image is the most important indicator of cellular activity, but is affected by other factors such as the basal metabolic ratio of each subject. In order to locate dysfunctional regions accurately, intensity normalization by a scale factor is a prerequisite in the data analysis, for which the global mean value is most widely used. However, this is unsuitable for stroke studies. Alternatively, a specified scale factor calculated from a reference region is also used, comprising neither hyper- nor hypo-metabolic voxels. But there is no such recognized reference region for stroke studies. Therefore, we proposed a totally data-driven automatic method for unbiased scale factor generation. This factor was generated iteratively until the residual deviation of two adjacent scale factors was reduced by 〈 5%. Moreover, both simulated and real stroke data were used for evaluation, and these suggested that our proposed unbiased scale factor has better sensi- tivity and accuracy for stroke studies.
基金financially supported by the National Natural Science Foundation of China(No.51761037)the Scientific Research Foundation of the Education Department of Jiangxi Province(No.GJJ170897)。
文摘Melt processing is a promising process to fabricate Mg-CNTs(carbon nanotubes)composites with high performance and large dimensions.In this work,the liquidmixing technique and ball-milling processes as well as the stirring casting method were used to prepare ZM1-1.0 CNTs-L and ZM1-1.0 CNTs-B composites,respectively.The composites were studied using optical microscopy(OM),Raman spectroscopy,scanning electron microscope(SEM),transmission electron microscope(TEM)and room-temperature tensile test.The results show that the yield strength(YS),ultimate tensile strength(UTS),elongation and microhardness values of the ZM1-1.OCNTs-L composite are improved by 37.3%,29.6%,37.0%and33.3%,respectively,compared with those of ZM1 alloy.The uniform dispersion of CNTs as well as the strong interfacial bonds with the Mg matrix is the main reason for the significant improvement in mechanical properties of the as-cast composite.Liquid mixing combined with the stirring casting method is favorable to fabricate Mg-CNTs composite with high mechanical properties.
基金the Jiangxi Science and Technology Projects Fund(No.z02727)the Fund for Testing and Analyzing of Nanchang University(No.201203)
文摘Oil-based nanofluids including 0.75%—1.75%(mass fraction) carbon nanotubes(CNTs) without any surfactants have been synthesized by a two-step process. The probes machined from 45~# steel with 22 mm diameter and 50 mm length are quenched in the as-synthesized CNT nanofluids for testing the cooling behaviors of the nanofluids. The laser diffraction particle size analyzer, scanning electronic microscope(SEM), X-ray diffractometer and transmission electron microscope(TEM) are used to characterize the quality and distribution of CNTs in the nanofluids. The wettability and viscosity of 30~# oil and oil-based CNT nanofluids are measured by a goniometer at 15℃ and a rotational type viscometer at 40℃, respectively. The results show that the cooling efficiency of the oil-based CNT nanofluids is better than that of 30~# oil. Moreover, the cooling rate of the naonofluids increases with the further increase of the CNT concentration. When the mass fraction of CNTs increases to 1.75%, the cooling rate of the naonofluids reaches a maximum at 760℃ and it is increased by 77.8% as compared to that of base oil. The improved cooling rate of oil by CNTs is mainly due to the uniform distribution and excellent thermal conductivity of CNTs.
