The effect of current density on electrically assisted solid-state bulk joining,so-called electrically assisted pressure joining(EAPJ),of copper(Cu)C11000 and aluminum(Al)6061-T6 alloys is investigated.During EAPJ,var...The effect of current density on electrically assisted solid-state bulk joining,so-called electrically assisted pressure joining(EAPJ),of copper(Cu)C11000 and aluminum(Al)6061-T6 alloys is investigated.During EAPJ,various combinations of electric current density and duration are applied to the cylindrical specimen assembly to reach a fixed peak temperature during continuous axial compressive plastic deformation.Then,an additional electric current is periodically applied to the specimen assembly without plastic deformation to keep the temperature elevated.Microstructural observation confirms that the defect-free joint of the selected material combination is fabricated without melting and solidification.The athermal effect of electric current on the diffusion enhancement can be accommodated by introducing the effective activation energy or the effective temperature.The microstructural analysis also demonstrates that the current density both increases the thickness of the intermetallic compound(IMC)layer at the joint interface and affects the microstructural evolution of joining materials.Finally,the mechanical properties of the joint are strongly affected by the electric current density.The present study provides insight into the effect of electric current density on the solid-state joining mechanism of EAPJ of dissimilar material combinations.展开更多
Dear editor, We read with pleasure the well-designed study by Butler et al of electrical cardioversion of emergency department patients with atrial fibrillation. We appreciate their analysis of the distinctives of pro...Dear editor, We read with pleasure the well-designed study by Butler et al of electrical cardioversion of emergency department patients with atrial fibrillation. We appreciate their analysis of the distinctives of procedural sedation when employed for this indication. Understanding the dosing adjustments to propofol undertaken by their sedationists will help us more carefully evaluate our own approach to sedating patients undergoing electrical cardioversion of atrial fibrillation.展开更多
Recently, Shunde Electric Pressure Cooker Alliance （short for EPCA） successfully made four proposals on revision of the IEC international standard for electric pressure cooker with independent intellectual property ...Recently, Shunde Electric Pressure Cooker Alliance （short for EPCA） successfully made four proposals on revision of the IEC international standard for electric pressure cooker with independent intellectual property rights, namely Elastic Structure Design, Anti-blocking Safety, Pressure Relief Safety and Lid Closing Safety. In the mean time, when participating in the activities related with revision proposals on IEC standard Electric Pressure Cooker, EPCA makes full use of the information and experience gained in these activities, improves and put forward the new-edition Electric Pressure Cooker Alliance Standard （hereafter referred to as Alliance Standard）. This article is an interpretation with this Alliance Standard aiming at bettering the pressure cooker enterprises＇ understanding with this standard, so as to guide the alliance enterprises to highlight the differentiated characteristics and product features in the links like products design, procurement of raw and auxiliary materials, manufacturing and sales, etc., as well as to let industrial peers learn about the characteristics of this standard and the products.展开更多
The electrical properties of polycrystaltine CaB6 are revealed by in-situ resistance measurements under high pressure and low temperature. Due to the existence of grain boundaries, polycrystalline CaB6 behaves with se...The electrical properties of polycrystaltine CaB6 are revealed by in-situ resistance measurements under high pressure and low temperature. Due to the existence of grain boundaries, polycrystalline CaB6 behaves with semiconducting transport properties, which is different from the semimetallic CaB6 single crystals. The temperaturedependent resistance measurement results show that before the structural phase transition at 12.3 GPa the high pressure first induces the metallization at 6.5 GPa for CAB6. Moreover, the phase diagram for CaB6 is drawn based on the investigated electric conducting properties and at least three different conducting phases are found even at moderate high pressure and low temperature, indicating that the electric nature of CaB6 is very sensitive to the environment.展开更多
Crop residue open burning is an important emission source of ambient particles in China.This study analyzed the particle emission characteristics of crop residue open burning through combustion experiments with a nove...Crop residue open burning is an important emission source of ambient particles in China.This study analyzed the particle emission characteristics of crop residue open burning through combustion experiments with a novel open combustion simulation device using three typical crop straws in north China(corn,wheat,and rice).Particle samples size ranging from 0.006–9.890μm were collected by an Electrical Low Pressure Impactor plus,a high size-resolution instrument capable of dividing particles into 14 size stages.The size distributions of organic carbon(OC),elemental carbon(EC),water-soluble ions,and elements were analyzed,and source chemical profiles were constructed for PM0.1,PM1,PM2.5,and PM10.The number concentration of particles was concentrated in the Aiken nuclei mode(0.006–0.054μm),accounting for 75%of the total number,whereas the mass concentration was concentrated in the accumulation mode(0.054–0.949μm),accounting for 85.43%of the mass loading.OC,EC,Cl−,and K(include total K and water-soluble K)were the major chemical components of the particles,whose mass percentage distributions differed from those of other components.These fivemain components exhibited a bell-shaped size distribution in the 0.006–9.890μm range,whereas the other components exhibited a U-shaped distribution.Among the chemical profiles for PM0.1–PM10,OC was the most important component at 10–30%,followed by EC at 2%–8%.The proportions of K^(+),Cl^(−),and K varied substantially in different experimental groups,ranging from 0–15%,and K+and Cl−were significantly correlated(r=0.878,α=0.000).展开更多
Al-doped ZnO（AZO） thin films were grown on c-sapphire substrates by laser ablation under different oxygen partial pressures（P_（O2））.The effect of P_（O2） on the crystal structure,preferred orientation as well a...Al-doped ZnO（AZO） thin films were grown on c-sapphire substrates by laser ablation under different oxygen partial pressures（P_（O2））.The effect of P_（O2） on the crystal structure,preferred orientation as well as the electrical and optical properties of the films was investigated.The structure characterizations indicated that the as-grown films were single-phased with a wurtzite ZnO structure,showing a significant c-axis orientation.The films were well crystallized and exhibited better crystallinity and denser texture when deposited at higher P_（O2）.At the optimum oxygen partial pressures of 10- 15 Pa,the AZO thin films were epitaxially grown on c-sapphire substrates with the（0001） plane parallel to the substrate surface,i e,the epitaxial relationship was AZO（000 1） // A1_2O_3（000 1）.With increasing P_（O2）,the value of Hall carrier mobility was increased remarkably while that of carrier concentration was decreased slightly,which led to an enhancement in electrical conductivity of the AZO thin films.All the films were highly transparent with an optical transmittance higher than 85%.展开更多
There are clear differences in the electrical conductivities of the crustal granites of the Qinghai-Tibet Plateau.Because these granites are among the major rock types on the Qinghai-Tibet Plateau, it is very importan...There are clear differences in the electrical conductivities of the crustal granites of the Qinghai-Tibet Plateau.Because these granites are among the major rock types on the Qinghai-Tibet Plateau, it is very important to detect the electrical conductivity of granites under high temperatures and pressures to study the electrical conductivity structure of this area. Using impedance spectroscopy at a frequency range of 10.1–106 Hz, the electrical conductivity of the muscovite-granite collected from Yadong was investigated at a confining pressure of 1.0 GPa and temperatures ranging from 577 to 996 K, while the electrical conductivity of the biotite-granite collected from Lhasa was investigated at a pressure of 1.0 GPa and temperatures ranging from587 to 1382 K. The calculated activation enthalpies of the Yadong muscovite-granite sample is 0.92 eV in the low-temperature range(577–919 K) and 2.16 eV in the high-temperature range(919–996 K). The activation enthalpies of the Lhasa biotite-granite sample is 0.48 eV in the low-temperature range(587–990 K) and 2.06 eV in the high-temperature range(990–1382 K). The change in the activation enthalpies of the granites at different temperature ranges may be associated with the dehydration of the two samples. The electrical conductivities of the granite samples obtained in the laboratory using impedance spectroscopy correspond well with field observations conducted near the sampling points, both in terms of the actual conductivity values and the observed variations between the low-temperature and high-temperature regimes. This correlation of laboratory and field conductivities indicates that the conductivities of the crustal rocks in the two regions closely correspond to granite conductivities.We calculated the electrical conductivities of muscovite-granite and biotite-granite samples using the effective medium and HS boundary models. When applied to the crustal rocks of southern Tibet, the results of the geophysical conductivity profiles lie within the range of laboratory data. Thus, the electrical characteristics of the crustal rocks underlying the southern Qinghai-Tibet Plateau can largely be attributed to granites, with the large changes to high conductivities at increasing depths resulting from the dehydration of crustal rocks with granitic compositions.展开更多
High pressure as an effective strategy was employed to synthesize and modulate the electrical transport properties of(Bi,Sb)_(2)Te_(3) alloys.Intrinsic point defects could be significantly regulated via high pressure,...High pressure as an effective strategy was employed to synthesize and modulate the electrical transport properties of(Bi,Sb)_(2)Te_(3) alloys.Intrinsic point defects could be significantly regulated via high pressure,inducing a suitable donor-like effect to optimize the carrier concentration.The texture and microstructure were improved with high pressure,and a nanograin with(00l)orientation was observed in the(Bi,Sb)_(2)Te_(3) matrix,suggesting that high pressure could facilitate the recrystallization of lattice defects along the(00l)orientation.Based on the synergistic effect of high pressure on intrinsic point defects,texture,and microstructure,the carrier concentration and mobility are regularly modulated,resulting in the room-temperature power factor of the(Bi,Sb)_(2)Te_(3) alloys exhibiting a strong correlation with pressure.Hence,these important results here provide a prospective strategy in the improvement in the electrical transport properties of the Bi_(2)Te_(3)-based alloys according to the rational design of intrinsic point defects,texture,and microstructure with high pressure.展开更多
基金supported by"Regional Innovation Strategy(RIS)"through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(MOE)(2021RIS-003)supported by the Technology Innovation Program(Development of design for additive manufacturing technology and low alloy steel materials with tensile strength 1.0 GPa for next-generation components,20024345)funded by the Ministry of Trade,Industry,and Energy(MOTIE,Korea)supported by the National Research Foundation of Korea(NRF)grants funded by the Ministry of Science and ICT(MSIT)(NRF-2021R1A2C3005096).
文摘The effect of current density on electrically assisted solid-state bulk joining,so-called electrically assisted pressure joining(EAPJ),of copper(Cu)C11000 and aluminum(Al)6061-T6 alloys is investigated.During EAPJ,various combinations of electric current density and duration are applied to the cylindrical specimen assembly to reach a fixed peak temperature during continuous axial compressive plastic deformation.Then,an additional electric current is periodically applied to the specimen assembly without plastic deformation to keep the temperature elevated.Microstructural observation confirms that the defect-free joint of the selected material combination is fabricated without melting and solidification.The athermal effect of electric current on the diffusion enhancement can be accommodated by introducing the effective activation energy or the effective temperature.The microstructural analysis also demonstrates that the current density both increases the thickness of the intermetallic compound(IMC)layer at the joint interface and affects the microstructural evolution of joining materials.Finally,the mechanical properties of the joint are strongly affected by the electric current density.The present study provides insight into the effect of electric current density on the solid-state joining mechanism of EAPJ of dissimilar material combinations.
文摘Dear editor, We read with pleasure the well-designed study by Butler et al of electrical cardioversion of emergency department patients with atrial fibrillation. We appreciate their analysis of the distinctives of procedural sedation when employed for this indication. Understanding the dosing adjustments to propofol undertaken by their sedationists will help us more carefully evaluate our own approach to sedating patients undergoing electrical cardioversion of atrial fibrillation.
文摘Recently, Shunde Electric Pressure Cooker Alliance （short for EPCA） successfully made four proposals on revision of the IEC international standard for electric pressure cooker with independent intellectual property rights, namely Elastic Structure Design, Anti-blocking Safety, Pressure Relief Safety and Lid Closing Safety. In the mean time, when participating in the activities related with revision proposals on IEC standard Electric Pressure Cooker, EPCA makes full use of the information and experience gained in these activities, improves and put forward the new-edition Electric Pressure Cooker Alliance Standard （hereafter referred to as Alliance Standard）. This article is an interpretation with this Alliance Standard aiming at bettering the pressure cooker enterprises＇ understanding with this standard, so as to guide the alliance enterprises to highlight the differentiated characteristics and product features in the links like products design, procurement of raw and auxiliary materials, manufacturing and sales, etc., as well as to let industrial peers learn about the characteristics of this standard and the products.
基金Supported by the National Basic Research Program of China under Grant No 2011CB808204the National Natural Science Foundation of China under Grant Nos 11374121 and 11404133
文摘The electrical properties of polycrystaltine CaB6 are revealed by in-situ resistance measurements under high pressure and low temperature. Due to the existence of grain boundaries, polycrystalline CaB6 behaves with semiconducting transport properties, which is different from the semimetallic CaB6 single crystals. The temperaturedependent resistance measurement results show that before the structural phase transition at 12.3 GPa the high pressure first induces the metallization at 6.5 GPa for CAB6. Moreover, the phase diagram for CaB6 is drawn based on the investigated electric conducting properties and at least three different conducting phases are found even at moderate high pressure and low temperature, indicating that the electric nature of CaB6 is very sensitive to the environment.
基金supported by the National Key Research and Development Program of China(No.2016YFC0208500)the Tianjin Science and Technology Program(No.18ZXSZSF00160)the Fundamental Research Funds for the Central Universities of China(Nos.ZB19500210,ZB19000804).
文摘Crop residue open burning is an important emission source of ambient particles in China.This study analyzed the particle emission characteristics of crop residue open burning through combustion experiments with a novel open combustion simulation device using three typical crop straws in north China(corn,wheat,and rice).Particle samples size ranging from 0.006–9.890μm were collected by an Electrical Low Pressure Impactor plus,a high size-resolution instrument capable of dividing particles into 14 size stages.The size distributions of organic carbon(OC),elemental carbon(EC),water-soluble ions,and elements were analyzed,and source chemical profiles were constructed for PM0.1,PM1,PM2.5,and PM10.The number concentration of particles was concentrated in the Aiken nuclei mode(0.006–0.054μm),accounting for 75%of the total number,whereas the mass concentration was concentrated in the accumulation mode(0.054–0.949μm),accounting for 85.43%of the mass loading.OC,EC,Cl−,and K(include total K and water-soluble K)were the major chemical components of the particles,whose mass percentage distributions differed from those of other components.These fivemain components exhibited a bell-shaped size distribution in the 0.006–9.890μm range,whereas the other components exhibited a U-shaped distribution.Among the chemical profiles for PM0.1–PM10,OC was the most important component at 10–30%,followed by EC at 2%–8%.The proportions of K^(+),Cl^(−),and K varied substantially in different experimental groups,ranging from 0–15%,and K+and Cl−were significantly correlated(r=0.878,α=0.000).
基金Funded by National Natural Science Foundation of China(Nos.51272195,51521001)111 project(No.B13035)+1 种基金Hubei Provincial National Natural Science Foundation(No.2015CFB724)Fundamental Research Funds for the Central Universities(Nos.2013-ZD-4,2014-KF-3)
文摘Al-doped ZnO（AZO） thin films were grown on c-sapphire substrates by laser ablation under different oxygen partial pressures（P_（O2））.The effect of P_（O2） on the crystal structure,preferred orientation as well as the electrical and optical properties of the films was investigated.The structure characterizations indicated that the as-grown films were single-phased with a wurtzite ZnO structure,showing a significant c-axis orientation.The films were well crystallized and exhibited better crystallinity and denser texture when deposited at higher P_（O2）.At the optimum oxygen partial pressures of 10- 15 Pa,the AZO thin films were epitaxially grown on c-sapphire substrates with the（0001） plane parallel to the substrate surface,i e,the epitaxial relationship was AZO（000 1） // A1_2O_3（000 1）.With increasing P_（O2）,the value of Hall carrier mobility was increased remarkably while that of carrier concentration was decreased slightly,which led to an enhancement in electrical conductivity of the AZO thin films.All the films were highly transparent with an optical transmittance higher than 85%.
基金supported by the National Natural Science Foundation of China (Grant No. 41374095)the Chinese Academy of Sciences/State Administration of Foreign Experts Affairs International Partnership Program Creative Research team (Grant No. KZZD-EW-TZ19)the Fundamental Research Funds of the China Earthquake Administration (Grant No. DQJB16B06)
文摘There are clear differences in the electrical conductivities of the crustal granites of the Qinghai-Tibet Plateau.Because these granites are among the major rock types on the Qinghai-Tibet Plateau, it is very important to detect the electrical conductivity of granites under high temperatures and pressures to study the electrical conductivity structure of this area. Using impedance spectroscopy at a frequency range of 10.1–106 Hz, the electrical conductivity of the muscovite-granite collected from Yadong was investigated at a confining pressure of 1.0 GPa and temperatures ranging from 577 to 996 K, while the electrical conductivity of the biotite-granite collected from Lhasa was investigated at a pressure of 1.0 GPa and temperatures ranging from587 to 1382 K. The calculated activation enthalpies of the Yadong muscovite-granite sample is 0.92 eV in the low-temperature range(577–919 K) and 2.16 eV in the high-temperature range(919–996 K). The activation enthalpies of the Lhasa biotite-granite sample is 0.48 eV in the low-temperature range(587–990 K) and 2.06 eV in the high-temperature range(990–1382 K). The change in the activation enthalpies of the granites at different temperature ranges may be associated with the dehydration of the two samples. The electrical conductivities of the granite samples obtained in the laboratory using impedance spectroscopy correspond well with field observations conducted near the sampling points, both in terms of the actual conductivity values and the observed variations between the low-temperature and high-temperature regimes. This correlation of laboratory and field conductivities indicates that the conductivities of the crustal rocks in the two regions closely correspond to granite conductivities.We calculated the electrical conductivities of muscovite-granite and biotite-granite samples using the effective medium and HS boundary models. When applied to the crustal rocks of southern Tibet, the results of the geophysical conductivity profiles lie within the range of laboratory data. Thus, the electrical characteristics of the crustal rocks underlying the southern Qinghai-Tibet Plateau can largely be attributed to granites, with the large changes to high conductivities at increasing depths resulting from the dehydration of crustal rocks with granitic compositions.
基金supported by the National Science Foundation of China(11464035)theChina Postdoctoral Science Foundation(2016M601397)+2 种基金the Jilin Science and Technology Development Plan(20180520012JH)the“13th Five-Year Plan”Science and Technology Research of Jilin Provincial Department of Education(JJKH20181120KJ)the Changchun University of Science and Technology(XQNJJ-2016-06).
文摘High pressure as an effective strategy was employed to synthesize and modulate the electrical transport properties of(Bi,Sb)_(2)Te_(3) alloys.Intrinsic point defects could be significantly regulated via high pressure,inducing a suitable donor-like effect to optimize the carrier concentration.The texture and microstructure were improved with high pressure,and a nanograin with(00l)orientation was observed in the(Bi,Sb)_(2)Te_(3) matrix,suggesting that high pressure could facilitate the recrystallization of lattice defects along the(00l)orientation.Based on the synergistic effect of high pressure on intrinsic point defects,texture,and microstructure,the carrier concentration and mobility are regularly modulated,resulting in the room-temperature power factor of the(Bi,Sb)_(2)Te_(3) alloys exhibiting a strong correlation with pressure.Hence,these important results here provide a prospective strategy in the improvement in the electrical transport properties of the Bi_(2)Te_(3)-based alloys according to the rational design of intrinsic point defects,texture,and microstructure with high pressure.
