Only a few studies have reported the efects of electrochemical hydrogenation on the tensile mechanical properties of additively manufactured Ti–6Al–4V alloy,in all of them the alloy was processed by laser powder-bed...Only a few studies have reported the efects of electrochemical hydrogenation on the tensile mechanical properties of additively manufactured Ti–6Al–4V alloy,in all of them the alloy was processed by laser powder-bed fusion.Furthermore,the efects of either hot isostatic pressing(HIP)or heat treatment(HT)post-treatments on the mechanical properties were not reported.Here,the Young’s modulus,ultimate tensile stress,and uniform(homogeneous)strain of as-built electron beam melted(EBM)Ti–6Al–4V alloys were studied using small tensile specimens before and after electrochemical hydrogenation,as well as before and after secondary processes of HIP at 920℃ and HT at 1000℃.The tensile properties of all hydrogenated alloys were signifcantly degraded compared to their non-hydrogenated counterparts.The yield stress could not be determined for all hydrogenated alloys,as failure occurred at a strain below 0.2%ofset.The uniform strain of the hydrogenated alloys was less than 1%,compared to 1%–5%for the non-hydrogenated alloys.The fracture mode of the hydrogenated alloys after HIP and HT revealed cleavage fracture,indicating increased brittleness.In the as-built hydrogenated alloy,the fracture mode varied with location:brittle fracture occurred near the surface due to the formation of a hydride layer,while a more ductile fracture with dimples was observed below this layer.展开更多
In order to produce low-cost titanium(Ti)with high productivity,fundamental studies on producing metallic Ti from titanium dioxide(TiO_(2))in the cold pressed pellets were conducted by metallothermic reduction with an...In order to produce low-cost titanium(Ti)with high productivity,fundamental studies on producing metallic Ti from titanium dioxide(TiO_(2))in the cold pressed pellets were conducted by metallothermic reduction with an indirect contact method.This paper focuses on discussing the mechanism of the reduction process and the relationships of RM(a revised reduction index)with reduction temperature,reduction time,and mole ratio of TiO_(2) to CaCl_(2)(nTiO_(2)/nCaCl_(2))in the pellets.The results show that metallic Ti was obtained from the reduction of TiO_(2) in the pellets by calcium(Ca)vapor;pellets were reduced homogenously and Ca vapor diffused into the porous pellets by Knudsen diffusion or the mixing diffusion of molecular diffusion and Knudsen diffusion at 1273 K;RM increased with the increases of temperature and reduction time and was 96.34%when T_(Redu)=1273 K,t_(Redu)=6 h,and nTiO_(2)/nCaCl_(2)=4;the reasonable nTiO_(2)/nCaCl_(2) value is 3−5 for the pellets with enough strength and high RM.展开更多
Scandia pressed cathodes were prepared by powder metallurgy method using mixed powder of scandia doped tungsten and barium-calcium aluminates obtained by different mixing methods.The element distribution uniformity gr...Scandia pressed cathodes were prepared by powder metallurgy method using mixed powder of scandia doped tungsten and barium-calcium aluminates obtained by different mixing methods.The element distribution uniformity greatly affected the emission property.The powder prepared by ball-milling had small particle size and uniform distribution of different elements.This kind of powder was favorable for the chemical reaction among Ba,Ca aluminates,scandia and tungsten to take place sufficiently to form active substance which can improve the emission property.The emission current density of the cathode prepared with ball-milling powder was about 8 times higher than that prepared by manually mixing method,4 times higher than Os coated M-type cathode.The higher content of the active substance on the cathode surface prepared by ball-milling led to the better emission performance of the cathode.展开更多
This study explores the utilization of various chemometric analytical methods for determining the quality of pressed sesame oil with different adulteration levels of refined sesame oil using UV spectral fingerprints.T...This study explores the utilization of various chemometric analytical methods for determining the quality of pressed sesame oil with different adulteration levels of refined sesame oil using UV spectral fingerprints.The goal of this study was to provide a reliable tool for assessing the quality of sesame oil.The UV spectra of 51 samples of pressed sesame oil and 420 adulterated samples with refined sesame oil were measured in the range of 200-330 nm.Various classification and prediction methods,including linear discrimination analysis(LDA),support vector machines(SVM),soft independent modeling of class analogy(SIMCA),partial least squares regression(PLSR),support vector machine regression(SVR),and back-propagation neural network(BPNN),were employed to analyze the UV spectral data of pressed sesame oil and adulterated sesame oil.The results indicated that SVM outperformed the other classification methods in qualitatively identifying adulterated sesame oil,achieving an accuracy of 96.15%,a sensitivity of 97.87%,and a specificity of 80%.For quantitative analysis,BPNN yielded the best prediction results,with an R^(2) value of 0.99,RMSEP of 2.34%,and RPD value of 10.60(LOD of 8.60%and LOQ of 28.67%).Overall,the developed models exhibited significant potential for rapidly identifying and predicting the quality of sesame oil.展开更多
Since the Internet of Things（IoT） secret information is easy to leak in data transfer,a data secure transmission model based on compressed sensing（CS） and digital watermarking technology is proposed here. Firstly,...Since the Internet of Things（IoT） secret information is easy to leak in data transfer,a data secure transmission model based on compressed sensing（CS） and digital watermarking technology is proposed here. Firstly, for node coding end, the digital watermarking technology is used to embed secret information in the conventional data carrier. Secondly, these data are reused to build the target transfer data by the CS algorithm which are called observed signals. Thirdly, these signals are transmitted to the base station through the wireless channel. After obtaining these observed signals, the decoder reconstructs the data carrier containing privacy information. Finally, the privacy information is obtained by digital watermark extraction algorithm to achieve the secret transmission of signals. By adopting the watermarking and compression sensing to hide secret information in the end of node code, the algorithm complexity and energy consumption are reduced. Meanwhile, the security of secret information is increased.The simulation results show that the method is able to accurately reconstruct the original signal and the energy consumption of the sensor node is also reduced significantly in consideration of the packet loss.展开更多
How time flies!I’m a little sad when I realize that I will graduate from junior high school in a few months.Luckily,I have some wonderful memories.The person who impressed me most was my friend.My English was bad bef...How time flies!I’m a little sad when I realize that I will graduate from junior high school in a few months.Luckily,I have some wonderful memories.The person who impressed me most was my friend.My English was bad before and I felt unhappy about it.So I told it to a girl called Mary,who was good at English.She was willing to help me and made friends with me.She taught me some useful ways to learn English.展开更多
Time flies like an arrow,and time lost never returns.In the past few years of my junior high school life,what impressed me most was running.At first,I didn’t like sports.I thought I was supposed to spend more time on...Time flies like an arrow,and time lost never returns.In the past few years of my junior high school life,what impressed me most was running.At first,I didn’t like sports.I thought I was supposed to spend more time on school work than on exercise.But gradually,I found that running was not only good for my health,but also helped me relieve stress.When I opened my arms and stretched my legs on the playground,I was like a deer running in the field,which made me get a sense of belonging.展开更多
The present work reports the effect of thermal induced porosity(TIP)on the high-cycle fatigue(HCF)and very high-cycle fatigue(VHCF)behaviors of hot-isostatic-pressed(HIPed)Ti-6Al-4V alloy from gasatomized powder.The r...The present work reports the effect of thermal induced porosity(TIP)on the high-cycle fatigue(HCF)and very high-cycle fatigue(VHCF)behaviors of hot-isostatic-pressed(HIPed)Ti-6Al-4V alloy from gasatomized powder.The results show that the residual pores in the as-HIPed powder compacts present no obvious effect on the HCF life.The regrowth of the residual pores can be observed after solution heat treatment.The pore location ranks the most harmful for the fatigue life compared with the other initiating defects.The maximum stress intensity factors were calculated.The plastic zone size of fine granular area(FGA)is much less than the characteristic size of the microstructure,and the crucial size of the internal pores in this study is about 40μm.The failure types of fatigue specimens in the VHCF regime were classified,and the competition of different failure types was described based on the modified Poisson distribution.展开更多
To increase the adhesion strength between the coating and the substrate, sintered Ti（C,N）-based cermets were selected and deposited with monolayer TiN using a multiarc ion-plating technique; subsequently, hot isosta...To increase the adhesion strength between the coating and the substrate, sintered Ti（C,N）-based cermets were selected and deposited with monolayer TiN using a multiarc ion-plating technique; subsequently, hot isostatic pressing （HIPhag） treatment was performed at 1000℃ using nitrogen pressure up to 110 MPa. The mechanical properties of cermets after a coating process and subsequent HIPing treatment have been evaluated with respect to the hardness, the residual stress, and the coating adhesion. The results show that atter the HIPing process, there was a higher increase ha critical load ha the TiN-coated cermets with lower surface roughness compared with those with higher surface roughness. In all cases, the residual stress was found to be compressive. The effects of substrate surface roughness and posttreatment on the adhesion strength of the coatings were thus investigated. It was also fotmd that the HIPing posttreatment process is well suited for hacreasing the adhesion strength between the coating and the substrate.展开更多
60NiTi alloy is considered to be a promising material for specialized bearing and gear applications due to its high hardness,strength,and low modulus.However,fabricating 60NiTi through conventional processing methods ...60NiTi alloy is considered to be a promising material for specialized bearing and gear applications due to its high hardness,strength,and low modulus.However,fabricating 60NiTi through conventional processing methods is challenging due to the brittleness and poor workability.In this study,60NiTi with high relative density was successfully fabricated directly from pre-alloyed powder through hot isostatic pressing.The effects of solution and aging treatments on microstructure and mechanical properties were systematically studied by advanced characterization techniques.The hot-isostatic-pressed 60NiTi showed low average hardness and elastic strain due to the formation of a soft Ni_(3)Ti phase and B2 NiTi matrix.Solution treatment above 1000℃dissolved the Ni_(3)Ti phase and promoted the formation of nanoscale Ni_(4)Ti_(3)precipitates,which significantly improved the hardness,strength,and elastic strain of 60NiTi.The formation of the Ni_(4)Ti_(3) phase can be mainly attributed to the driving forces induced by the chemical supersaturation and mechanical stress concentration.Finally,the phase transformation mechanisms during heat treatment and compression test were discussed.展开更多
The hot compressive deformation behavior of hot isostatically pressed Ti-47.5Al-2Cr-2Nb-0.2W-0.2B alloy using gas atomization powders was systematically investigated and the processing map was obtained in the temperat...The hot compressive deformation behavior of hot isostatically pressed Ti-47.5Al-2Cr-2Nb-0.2W-0.2B alloy using gas atomization powders was systematically investigated and the processing map was obtained in the temperature range of 1323-1473 Kand strain rate range of 0.001-0.5s^（-1）.The calculated activation energy in the above variational ranges of temperature and strain rate possesses a low activation energy value of approximately 365.6kJ/mol based on the constitutive relationship models developed with the Arrhenius-type constitutive model respectively considering the strain rate and deformation temperature.The hot working flow behavior during the deformation process was analyzed combined with the microstructural evolution.Meanwhile,the processing maps during the deformation process were established based on the dynamic material model and Prasad instability criterion under different deformation conditions.Finally,the optimal hot processing window of this alloy corresponding to the wide temperature range of 1353-1453 Kand the low strain rate of 0.001-0.1s^（-1） was obtained.展开更多
Characteristics of magnetic hardening in cast-hot pressed magnet Pr_(19)Fe_(74.5)B_5Cu_(1.5)were stu- died.The microstructure features and virgin magnetization curve reveal a nucleation control- led coercivity mechani...Characteristics of magnetic hardening in cast-hot pressed magnet Pr_(19)Fe_(74.5)B_5Cu_(1.5)were stu- died.The microstructure features and virgin magnetization curve reveal a nucleation control- led coercivity mechanism.Regression analysis shows that the intrinsic coercivity varies inversely as the logarithm of the average grain size: _iH_c(MA/m)=1.7312-0.48161nd(μm) which confirms the randomness of nucleation of reversed domains and the statistical nature of coercivity,indicating that the decrease of grain size would reduce the average number of de- fects on its surface and lower the probability of magnetization reversal of a grain and the cu- mulative fraction of the grains that have reversed their magnetization.Coercivity is thus en- hanced.展开更多
Nd-Fe-B hot-pressed(HP) magnet prepared from melt-spun MQU-F flakes features coarse grains(CG)with the average size of both 200 nm(CGS) and 700 nm(CGL) at flake boundary.The grain growth at the flake boundary of Nd2 F...Nd-Fe-B hot-pressed(HP) magnet prepared from melt-spun MQU-F flakes features coarse grains(CG)with the average size of both 200 nm(CGS) and 700 nm(CGL) at flake boundary.The grain growth at the flake boundary of Nd2 Fe14B/α-Fe composite HP magnet before and after diffusion of low-melting-point Pr82Cu18 phase was investigated,revealing the indispensable role of surface RE-rich phase of meltspun flakes in the formation of CG in HP magnet.The dominant role of surface oxygen content of melt-spun flakes in the formation of CGL has been clarified with etching method.The HP magnet prepared from the etched flakes with dramatically decreased oxygen content exhibits the CG regions merely with homoge neous equiaxed CGS at flake boundary.Consequently,the coercivity(μ0 Hc) shows significant increase while remanent magnetization(μ0 Mr) inappreciable change.Further investigation with sieving method reveals the elimination of CGL via removal of the fine Nd-Fe-B flakes smaller than 54 μm due to their much higher oxygen content,confirming the dominant role of oxygen content in the formation of CGL.The quantitative analysis on the magnetic properties of the above HP magnets reveals the monotonic increase of coercivity(μ0 Hc) and negligible change of remanent magnetization(μ0 Mr) with decreased oxygen contents of Nd-Fe-B flakes.The maximum value of coercivity(μ0 Hc) increases from2.26 to 2.47 T as the oxygen content decreases from 0.1692 wt% to 0.079 wt%.展开更多
Powder compacts of the system Bi2–xPbxSr2Ca2Cu3Oy with 0 ≤ x ≤ 0.5 molar ratio using both techniques;isothermal hot pressing and the solid state reaction (sintering). The XRD of the hot pressed powder compacts of t...Powder compacts of the system Bi2–xPbxSr2Ca2Cu3Oy with 0 ≤ x ≤ 0.5 molar ratio using both techniques;isothermal hot pressing and the solid state reaction (sintering). The XRD of the hot pressed powder compacts of the nominal compositions Bi2–xPbxSr2Ca2Cu3Oy showed 2212 and 2223 phases. The resistivity temperature variations belonging to the composition Bi1.8Pb0.2Sr2Ca2Cu3Oy showed metal-superconducting transition at Tons = 143 K for the annealed sample for 24 h. The annealed nominal composition Bi1.5Pb0.5Sr2Ca2Cu3Oy for 18 h showed metal to superconducting transition at 80 K.展开更多
Myofibroblasts,the primary effector cells for implant-induced fibrosis,contribute to this process by secreting excessive collagen-rich matrix and contracting.Thus,approaches that suppress myofibroblasts may achieve de...Myofibroblasts,the primary effector cells for implant-induced fibrosis,contribute to this process by secreting excessive collagen-rich matrix and contracting.Thus,approaches that suppress myofibroblasts may achieve desirable suppression effects in the fibrotic process.As one of the important physical properties of materials,material topographical structures have been proven to affect various aspects of cell behaviors,so is it possible to manipulate the formation of myofibroblasts by tailoring the topographical properties of medical devices?In this study,polycaprolactone(PCL)surfaces with typical micropatterns(micro column and micro pit)were fabricated.The regulatory effects of surface micropatterns on the myofibroblastic differentiation of fibroblasts were investigated.Compared to the flat surfaces and surfaces with micro pit,surfaces with micro columns triggered the F-to G-actin transition,inhibiting the nuclear transfer of myocardin-related transcription factor-A.Subsequently,the downstream geneα-smooth muscle actin,which is a marker of myofibroblasts,was suppressed.Further in vivo investigation showed that PCL implants with micro-column-patterned surfaces inhibited the formation of peri-implant fibrotic capsules.Our results demonstrate that surface topographical properties are a potent regulator of fibroblast differentiation into myofibroblasts and highlight the antifibrotic potential of modifying surfaces with micro-column patterns.展开更多
Contemporary Social Sciences is an English-language journal founded by Sichuan Academy of Social Sciences(SASS)in March 2016.It is China’s first and only English academic journal established by a local academy of soc...Contemporary Social Sciences is an English-language journal founded by Sichuan Academy of Social Sciences(SASS)in March 2016.It is China’s first and only English academic journal established by a local academy of social sciences,as well as Sichuan’s only English academic journal in humanities and social sciences with a CN serial number.As a publication run in line with the requirements of China’s press and publication authority,Contemporary Social Sciences publishes outstanding research in the field of social sciences in China and also includes high-quality research work by foreign scholars on the development of China’s western regions and its reform and opening up.The aim is to help promote China’s academic achievements to the world and give China a stronger voice in the global community of social sciences.展开更多
Light-regulated gene expression systems allow controlling gene expression in space and time with high accuracy.Contrary to previous synthetic light sensors that incorporate two-component systems which require localiza...Light-regulated gene expression systems allow controlling gene expression in space and time with high accuracy.Contrary to previous synthetic light sensors that incorporate two-component systems which require localization at the plasma membrane,soluble one-component repression systems provide several advantageous characteristics.Firstly,they are soluble and able to diffuse across the cytoplasm.Secondly,they are smaller and of lower complexity,enabling less taxing expression and optimization of fewer parts.Thirdly,repression through steric hindrance is a widespread regulation mechanism that does not require specific interaction with host factors,potentially enabling implementation in different organisms.Herein,we present the design of the synthetic promoter P_(EL)that in combination with the light-regulated dimer EL222 constitutes a onecomponent repression system.Inspired by previously engineered synthetic promoters and the Escherichia coli lacZYA promoter,we designed P_(EL)with two EL222 operators positioned to hinder RNA polymerase binding when EL222 is bound.P_(EL)is repressed by EL222 under conditions of white light with a light-regulated repression ratio of five.Further,alternating conditions of darkness and light in cycles as short as one hour showed that repression is reversible.The design of the P_(EL)EL222 system herein presented could aid the design and implementation of analogous one-component optogenetic repression systems.Finally,we compare the P_(EL)-EL222 system with similar systems and suggest general improvements that could optimize and extend the functionality of EL222-based as well as other one-component repression systems.展开更多
The Crop Journal is a bimonthly scientific journal co-sponsored by the Crop Science Society of China and the Institute of Crop Science,Chinese Academy of Agricultural Sciences,and China Science Publishing&Media Gr...The Crop Journal is a bimonthly scientific journal co-sponsored by the Crop Science Society of China and the Institute of Crop Science,Chinese Academy of Agricultural Sciences,and China Science Publishing&Media Group Ltd.It is published by Science Press and KeAi(founded by China Science Publishing&Media Ltd.and Elsevier).展开更多
Covalent organic frameworks(COFs)are an emerging class of porous crystalline materials formed by the precise assembly of organic molecular building blocks into extended periodic structures via strong covalent bonds.Th...Covalent organic frameworks(COFs)are an emerging class of porous crystalline materials formed by the precise assembly of organic molecular building blocks into extended periodic structures via strong covalent bonds.They feature well-defined pore structure,high specific surface area,and tunable physicochemical properties,endowing them with broad application prospects in gas storage,molecular separation.展开更多
基金supported by the Pazy Foundation of the Israel Atomic Energy Commission and the Israeli Council of Higher Education(Grant No.322/20)。
文摘Only a few studies have reported the efects of electrochemical hydrogenation on the tensile mechanical properties of additively manufactured Ti–6Al–4V alloy,in all of them the alloy was processed by laser powder-bed fusion.Furthermore,the efects of either hot isostatic pressing(HIP)or heat treatment(HT)post-treatments on the mechanical properties were not reported.Here,the Young’s modulus,ultimate tensile stress,and uniform(homogeneous)strain of as-built electron beam melted(EBM)Ti–6Al–4V alloys were studied using small tensile specimens before and after electrochemical hydrogenation,as well as before and after secondary processes of HIP at 920℃ and HT at 1000℃.The tensile properties of all hydrogenated alloys were signifcantly degraded compared to their non-hydrogenated counterparts.The yield stress could not be determined for all hydrogenated alloys,as failure occurred at a strain below 0.2%ofset.The uniform strain of the hydrogenated alloys was less than 1%,compared to 1%–5%for the non-hydrogenated alloys.The fracture mode of the hydrogenated alloys after HIP and HT revealed cleavage fracture,indicating increased brittleness.In the as-built hydrogenated alloy,the fracture mode varied with location:brittle fracture occurred near the surface due to the formation of a hydride layer,while a more ductile fracture with dimples was observed below this layer.
基金Projects(51774071,50804007,51974073)supported by the National Natural Science Foundation of China。
文摘In order to produce low-cost titanium(Ti)with high productivity,fundamental studies on producing metallic Ti from titanium dioxide(TiO_(2))in the cold pressed pellets were conducted by metallothermic reduction with an indirect contact method.This paper focuses on discussing the mechanism of the reduction process and the relationships of RM(a revised reduction index)with reduction temperature,reduction time,and mole ratio of TiO_(2) to CaCl_(2)(nTiO_(2)/nCaCl_(2))in the pellets.The results show that metallic Ti was obtained from the reduction of TiO_(2) in the pellets by calcium(Ca)vapor;pellets were reduced homogenously and Ca vapor diffused into the porous pellets by Knudsen diffusion or the mixing diffusion of molecular diffusion and Knudsen diffusion at 1273 K;RM increased with the increases of temperature and reduction time and was 96.34%when T_(Redu)=1273 K,t_(Redu)=6 h,and nTiO_(2)/nCaCl_(2)=4;the reasonable nTiO_(2)/nCaCl_(2) value is 3−5 for the pellets with enough strength and high RM.
基金Project supported by the National Natural Science Foundation of China (51071005)Beijing Natural Science Foundation (2102007)Program for Excellent Talents in Beijing (PHR201006101)
文摘Scandia pressed cathodes were prepared by powder metallurgy method using mixed powder of scandia doped tungsten and barium-calcium aluminates obtained by different mixing methods.The element distribution uniformity greatly affected the emission property.The powder prepared by ball-milling had small particle size and uniform distribution of different elements.This kind of powder was favorable for the chemical reaction among Ba,Ca aluminates,scandia and tungsten to take place sufficiently to form active substance which can improve the emission property.The emission current density of the cathode prepared with ball-milling powder was about 8 times higher than that prepared by manually mixing method,4 times higher than Os coated M-type cathode.The higher content of the active substance on the cathode surface prepared by ball-milling led to the better emission performance of the cathode.
基金supported by the project number of“China Agricultural Research System funded by the Ministry of Agriculture”CARS-14,the Key Project of Science and Technology of Henan Province (201300110600)the“Double First-Class”Project for Postgraduate Academic Innovation Enhancement Programme of Henan University of Technology (HAUTSYL2023TS16)Education and Teaching Reform Research and Practice Project in School of International Education,Henan University of Technology (GJXY202407).
文摘This study explores the utilization of various chemometric analytical methods for determining the quality of pressed sesame oil with different adulteration levels of refined sesame oil using UV spectral fingerprints.The goal of this study was to provide a reliable tool for assessing the quality of sesame oil.The UV spectra of 51 samples of pressed sesame oil and 420 adulterated samples with refined sesame oil were measured in the range of 200-330 nm.Various classification and prediction methods,including linear discrimination analysis(LDA),support vector machines(SVM),soft independent modeling of class analogy(SIMCA),partial least squares regression(PLSR),support vector machine regression(SVR),and back-propagation neural network(BPNN),were employed to analyze the UV spectral data of pressed sesame oil and adulterated sesame oil.The results indicated that SVM outperformed the other classification methods in qualitatively identifying adulterated sesame oil,achieving an accuracy of 96.15%,a sensitivity of 97.87%,and a specificity of 80%.For quantitative analysis,BPNN yielded the best prediction results,with an R^(2) value of 0.99,RMSEP of 2.34%,and RPD value of 10.60(LOD of 8.60%and LOQ of 28.67%).Overall,the developed models exhibited significant potential for rapidly identifying and predicting the quality of sesame oil.
基金Supported by the Foundation of Tianjin for Science and Technology Innovation(10FDZDGX00400,11ZCKFGX00900)Key Project of Educational Reform Foundation of Tianjin Municipal Education Commission(C03-0809)
文摘Since the Internet of Things（IoT） secret information is easy to leak in data transfer,a data secure transmission model based on compressed sensing（CS） and digital watermarking technology is proposed here. Firstly, for node coding end, the digital watermarking technology is used to embed secret information in the conventional data carrier. Secondly, these data are reused to build the target transfer data by the CS algorithm which are called observed signals. Thirdly, these signals are transmitted to the base station through the wireless channel. After obtaining these observed signals, the decoder reconstructs the data carrier containing privacy information. Finally, the privacy information is obtained by digital watermark extraction algorithm to achieve the secret transmission of signals. By adopting the watermarking and compression sensing to hide secret information in the end of node code, the algorithm complexity and energy consumption are reduced. Meanwhile, the security of secret information is increased.The simulation results show that the method is able to accurately reconstruct the original signal and the energy consumption of the sensor node is also reduced significantly in consideration of the packet loss.
文摘How time flies!I’m a little sad when I realize that I will graduate from junior high school in a few months.Luckily,I have some wonderful memories.The person who impressed me most was my friend.My English was bad before and I felt unhappy about it.So I told it to a girl called Mary,who was good at English.She was willing to help me and made friends with me.She taught me some useful ways to learn English.
文摘Time flies like an arrow,and time lost never returns.In the past few years of my junior high school life,what impressed me most was running.At first,I didn’t like sports.I thought I was supposed to spend more time on school work than on exercise.But gradually,I found that running was not only good for my health,but also helped me relieve stress.When I opened my arms and stretched my legs on the playground,I was like a deer running in the field,which made me get a sense of belonging.
基金financially supported by the Natural Science Foundation of Shanxi Province,China(No.201901D211085)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(STIP)
文摘The present work reports the effect of thermal induced porosity(TIP)on the high-cycle fatigue(HCF)and very high-cycle fatigue(VHCF)behaviors of hot-isostatic-pressed(HIPed)Ti-6Al-4V alloy from gasatomized powder.The results show that the residual pores in the as-HIPed powder compacts present no obvious effect on the HCF life.The regrowth of the residual pores can be observed after solution heat treatment.The pore location ranks the most harmful for the fatigue life compared with the other initiating defects.The maximum stress intensity factors were calculated.The plastic zone size of fine granular area(FGA)is much less than the characteristic size of the microstructure,and the crucial size of the internal pores in this study is about 40μm.The failure types of fatigue specimens in the VHCF regime were classified,and the competition of different failure types was described based on the modified Poisson distribution.
基金This work was financially supported by the National Natural Science Foundation of China (No. 50074017).
文摘To increase the adhesion strength between the coating and the substrate, sintered Ti（C,N）-based cermets were selected and deposited with monolayer TiN using a multiarc ion-plating technique; subsequently, hot isostatic pressing （HIPhag） treatment was performed at 1000℃ using nitrogen pressure up to 110 MPa. The mechanical properties of cermets after a coating process and subsequent HIPing treatment have been evaluated with respect to the hardness, the residual stress, and the coating adhesion. The results show that atter the HIPing process, there was a higher increase ha critical load ha the TiN-coated cermets with lower surface roughness compared with those with higher surface roughness. In all cases, the residual stress was found to be compressive. The effects of substrate surface roughness and posttreatment on the adhesion strength of the coatings were thus investigated. It was also fotmd that the HIPing posttreatment process is well suited for hacreasing the adhesion strength between the coating and the substrate.
文摘60NiTi alloy is considered to be a promising material for specialized bearing and gear applications due to its high hardness,strength,and low modulus.However,fabricating 60NiTi through conventional processing methods is challenging due to the brittleness and poor workability.In this study,60NiTi with high relative density was successfully fabricated directly from pre-alloyed powder through hot isostatic pressing.The effects of solution and aging treatments on microstructure and mechanical properties were systematically studied by advanced characterization techniques.The hot-isostatic-pressed 60NiTi showed low average hardness and elastic strain due to the formation of a soft Ni_(3)Ti phase and B2 NiTi matrix.Solution treatment above 1000℃dissolved the Ni_(3)Ti phase and promoted the formation of nanoscale Ni_(4)Ti_(3)precipitates,which significantly improved the hardness,strength,and elastic strain of 60NiTi.The formation of the Ni_(4)Ti_(3) phase can be mainly attributed to the driving forces induced by the chemical supersaturation and mechanical stress concentration.Finally,the phase transformation mechanisms during heat treatment and compression test were discussed.
基金the financial supports from the National Natural Science Foundation of China(Grant Nos.51301157 and 51434007)the National High Technology Research and Development Program of China 863 Program(Grant No.2013AA031103)
文摘The hot compressive deformation behavior of hot isostatically pressed Ti-47.5Al-2Cr-2Nb-0.2W-0.2B alloy using gas atomization powders was systematically investigated and the processing map was obtained in the temperature range of 1323-1473 Kand strain rate range of 0.001-0.5s^（-1）.The calculated activation energy in the above variational ranges of temperature and strain rate possesses a low activation energy value of approximately 365.6kJ/mol based on the constitutive relationship models developed with the Arrhenius-type constitutive model respectively considering the strain rate and deformation temperature.The hot working flow behavior during the deformation process was analyzed combined with the microstructural evolution.Meanwhile,the processing maps during the deformation process were established based on the dynamic material model and Prasad instability criterion under different deformation conditions.Finally,the optimal hot processing window of this alloy corresponding to the wide temperature range of 1353-1453 Kand the low strain rate of 0.001-0.1s^（-1） was obtained.
文摘Characteristics of magnetic hardening in cast-hot pressed magnet Pr_(19)Fe_(74.5)B_5Cu_(1.5)were stu- died.The microstructure features and virgin magnetization curve reveal a nucleation control- led coercivity mechanism.Regression analysis shows that the intrinsic coercivity varies inversely as the logarithm of the average grain size: _iH_c(MA/m)=1.7312-0.48161nd(μm) which confirms the randomness of nucleation of reversed domains and the statistical nature of coercivity,indicating that the decrease of grain size would reduce the average number of de- fects on its surface and lower the probability of magnetization reversal of a grain and the cu- mulative fraction of the grains that have reversed their magnetization.Coercivity is thus en- hanced.
基金Project supported by the Ningbo Science and Technology Major (2017B10002,2019B10093)the National Natural Science Foundation of China (51671207,51301192)Zhejiang Province Technology Application Research (LGG19E010001)。
文摘Nd-Fe-B hot-pressed(HP) magnet prepared from melt-spun MQU-F flakes features coarse grains(CG)with the average size of both 200 nm(CGS) and 700 nm(CGL) at flake boundary.The grain growth at the flake boundary of Nd2 Fe14B/α-Fe composite HP magnet before and after diffusion of low-melting-point Pr82Cu18 phase was investigated,revealing the indispensable role of surface RE-rich phase of meltspun flakes in the formation of CG in HP magnet.The dominant role of surface oxygen content of melt-spun flakes in the formation of CGL has been clarified with etching method.The HP magnet prepared from the etched flakes with dramatically decreased oxygen content exhibits the CG regions merely with homoge neous equiaxed CGS at flake boundary.Consequently,the coercivity(μ0 Hc) shows significant increase while remanent magnetization(μ0 Mr) inappreciable change.Further investigation with sieving method reveals the elimination of CGL via removal of the fine Nd-Fe-B flakes smaller than 54 μm due to their much higher oxygen content,confirming the dominant role of oxygen content in the formation of CGL.The quantitative analysis on the magnetic properties of the above HP magnets reveals the monotonic increase of coercivity(μ0 Hc) and negligible change of remanent magnetization(μ0 Mr) with decreased oxygen contents of Nd-Fe-B flakes.The maximum value of coercivity(μ0 Hc) increases from2.26 to 2.47 T as the oxygen content decreases from 0.1692 wt% to 0.079 wt%.
文摘Powder compacts of the system Bi2–xPbxSr2Ca2Cu3Oy with 0 ≤ x ≤ 0.5 molar ratio using both techniques;isothermal hot pressing and the solid state reaction (sintering). The XRD of the hot pressed powder compacts of the nominal compositions Bi2–xPbxSr2Ca2Cu3Oy showed 2212 and 2223 phases. The resistivity temperature variations belonging to the composition Bi1.8Pb0.2Sr2Ca2Cu3Oy showed metal-superconducting transition at Tons = 143 K for the annealed sample for 24 h. The annealed nominal composition Bi1.5Pb0.5Sr2Ca2Cu3Oy for 18 h showed metal to superconducting transition at 80 K.
基金the National Natural Science Foundation of China(T2288101,31971266,U22A20157,32022041,and 82272152)the Guangdong Basic and Applied Basic Research Foundation(2022A1515011925)the Key Research and Development Program of Guangzhou(202007020002)。
文摘Myofibroblasts,the primary effector cells for implant-induced fibrosis,contribute to this process by secreting excessive collagen-rich matrix and contracting.Thus,approaches that suppress myofibroblasts may achieve desirable suppression effects in the fibrotic process.As one of the important physical properties of materials,material topographical structures have been proven to affect various aspects of cell behaviors,so is it possible to manipulate the formation of myofibroblasts by tailoring the topographical properties of medical devices?In this study,polycaprolactone(PCL)surfaces with typical micropatterns(micro column and micro pit)were fabricated.The regulatory effects of surface micropatterns on the myofibroblastic differentiation of fibroblasts were investigated.Compared to the flat surfaces and surfaces with micro pit,surfaces with micro columns triggered the F-to G-actin transition,inhibiting the nuclear transfer of myocardin-related transcription factor-A.Subsequently,the downstream geneα-smooth muscle actin,which is a marker of myofibroblasts,was suppressed.Further in vivo investigation showed that PCL implants with micro-column-patterned surfaces inhibited the formation of peri-implant fibrotic capsules.Our results demonstrate that surface topographical properties are a potent regulator of fibroblast differentiation into myofibroblasts and highlight the antifibrotic potential of modifying surfaces with micro-column patterns.
文摘Contemporary Social Sciences is an English-language journal founded by Sichuan Academy of Social Sciences(SASS)in March 2016.It is China’s first and only English academic journal established by a local academy of social sciences,as well as Sichuan’s only English academic journal in humanities and social sciences with a CN serial number.As a publication run in line with the requirements of China’s press and publication authority,Contemporary Social Sciences publishes outstanding research in the field of social sciences in China and also includes high-quality research work by foreign scholars on the development of China’s western regions and its reform and opening up.The aim is to help promote China’s academic achievements to the world and give China a stronger voice in the global community of social sciences.
基金the fluorescence spectrum of EL222,and Adam Wegelius is gratefully acknowledged for experimental assistance.AJ acknowledges funding from FP7-ICT-610730(EVOPROG)FP7-KBBE-613745(PROMYS)+2 种基金H2020 Marie Sklodowska-Curie Actions 642738(MetaRNA)Biotechnology and Biological Biological Sciences Research Council(BBSRC)BB/P020615/1(EVO-ENGINE),Engineering and Physical Sciences Research Council-Biotechnology and Biological Sciences Research Council(EPSRC-BBSRC)BB/M017982/1(WISB centre),and the departmental allocation from the School of Life Sciences(U.Warwick)PL acknowledges funding from the Knut och Alice Wallenbergs Stiftelse(project MoSE,No.2011.0067)and the Swedish Energy Agency(No.11674-5).
文摘Light-regulated gene expression systems allow controlling gene expression in space and time with high accuracy.Contrary to previous synthetic light sensors that incorporate two-component systems which require localization at the plasma membrane,soluble one-component repression systems provide several advantageous characteristics.Firstly,they are soluble and able to diffuse across the cytoplasm.Secondly,they are smaller and of lower complexity,enabling less taxing expression and optimization of fewer parts.Thirdly,repression through steric hindrance is a widespread regulation mechanism that does not require specific interaction with host factors,potentially enabling implementation in different organisms.Herein,we present the design of the synthetic promoter P_(EL)that in combination with the light-regulated dimer EL222 constitutes a onecomponent repression system.Inspired by previously engineered synthetic promoters and the Escherichia coli lacZYA promoter,we designed P_(EL)with two EL222 operators positioned to hinder RNA polymerase binding when EL222 is bound.P_(EL)is repressed by EL222 under conditions of white light with a light-regulated repression ratio of five.Further,alternating conditions of darkness and light in cycles as short as one hour showed that repression is reversible.The design of the P_(EL)EL222 system herein presented could aid the design and implementation of analogous one-component optogenetic repression systems.Finally,we compare the P_(EL)-EL222 system with similar systems and suggest general improvements that could optimize and extend the functionality of EL222-based as well as other one-component repression systems.
文摘The Crop Journal is a bimonthly scientific journal co-sponsored by the Crop Science Society of China and the Institute of Crop Science,Chinese Academy of Agricultural Sciences,and China Science Publishing&Media Group Ltd.It is published by Science Press and KeAi(founded by China Science Publishing&Media Ltd.and Elsevier).
文摘Covalent organic frameworks(COFs)are an emerging class of porous crystalline materials formed by the precise assembly of organic molecular building blocks into extended periodic structures via strong covalent bonds.They feature well-defined pore structure,high specific surface area,and tunable physicochemical properties,endowing them with broad application prospects in gas storage,molecular separation.
