用融熔法研制了 In_2O_3和 ITO(In_2O_3掺杂 Sn)单晶,并对其光电性能进行研究.纯 ITO 是一种简并半导体,在常温下,以晶格声子散射为主要的载流子传输机理.对 ITO 单晶,给出了载流子浓度与 Sn 掺杂浓度及载流子迁移率的关系.并对在单晶...用融熔法研制了 In_2O_3和 ITO(In_2O_3掺杂 Sn)单晶,并对其光电性能进行研究.纯 ITO 是一种简并半导体,在常温下,以晶格声子散射为主要的载流子传输机理.对 ITO 单晶,给出了载流子浓度与 Sn 掺杂浓度及载流子迁移率的关系.并对在单晶中由于用助溶剂而引入的 Pb 掺杂对材料电性能的影响作了探讨.从材料的吸收光谱图中的本征吸收限的变化及 Plasma 频率和坡度的变化,证实了我们对电性能测试的结果.EXAFS 结构测试结果给出了这二种材料导电率变化的因素.展开更多
Two-dimensional ZrS2 materials have potential for applications in nanoelectronics because of their theoretically predicted high mobility and sheet current density. Herein, we report the thickness and temperature depen...Two-dimensional ZrS2 materials have potential for applications in nanoelectronics because of their theoretically predicted high mobility and sheet current density. Herein, we report the thickness and temperature dependent transport properties of ZrS2 multilayers that were directly deposited on hexagonal boron nitride （h-BN） by chemical vapor deposition. Hysteresis-free gate sweeping, metal- insulator transition, and T-γ （γ- 0.82-1.26） temperature dependent mobility were observed in the ZrS2 films.展开更多
The general expressions based on the Fermi distribution of the free charge carriers are applied for estimation of the transport characteristics in superconductors at the temperature well above the superconducting phas...The general expressions based on the Fermi distribution of the free charge carriers are applied for estimation of the transport characteristics in superconductors at the temperature well above the superconducting phase transition temperature TC. The Hall-effect experimental results in the normal state of the superconductor YBa2Cu3O7-δ are not finally explained. On the ground of the randomly moving charge carriers, the transport characteristics of the randomly moving charge carriers for both single type and two types of the charge carriers are presented. The particular attention has been pointed to the Hall-effect measurement results of the high-TC superconductor YBa2Cu3O7-δ. It is at the first time derived the Hall coefficient expression for two type of highly degenerate charge carriers (electrons and holes) on the ground of the randomly moving charge carriers at the Fermi surface. It is shown that the Hall coefficient and other transport characteristics are determined by the ratio between the electron-like and hole-like densities of states at the Fermi surface.展开更多
The general expressions, based on the Fermi distribution of the free electrons, are applied for calculation of the kinetic coefficients in donor-doped silicon at arbitrary degree of the degeneracy of electron gas unde...The general expressions, based on the Fermi distribution of the free electrons, are applied for calculation of the kinetic coefficients in donor-doped silicon at arbitrary degree of the degeneracy of electron gas under equilibrium conditions. The classical statistics lead to large errors in estimation of the transport parameters for the materials where Fermi level is located high above the conduction band edge unless the effective density of randomly moving electrons is introduced. The obtained results for the diffusion coefficient and drift mobility are discussed together with practical approximations applicable for non-degenerate electron gas and materials with arbitrary degree of degeneracy. In particular, the drift mobility of randomly moving electrons is found to depend on the degree of degeneracy and can exceed the Hall mobility considerably. When the effective density is introduced, the traditional Einstein relation between the diffusion coefficient and the drift mobility of randomly moving electrons is conserved at any level of degeneracy. The main conclusions and formulae can be applicable for holes in acceptor-doped silicon as well.展开更多
A growing body of evidence has suggested that the imbalance of epigenetic markers and oxidative stress appears to be involved in the pathophysiology and progression of stroke.Thus,strategies that modulate these biomar...A growing body of evidence has suggested that the imbalance of epigenetic markers and oxidative stress appears to be involved in the pathophysiology and progression of stroke.Thus,strategies that modulate these biomarkers might be considered targets for neuroprotection and novel therapeutic opportunities for these patients.Physical exercise has been reported to induce changes in these epigenetic markers and improve clinical outcomes in different populations.However,little is reported on this in post-stroke patients.The purpose of this study was to investigate the effect of a single exercise session with WalkAide functional electrical stimulation(FES)on cognitive performance,clinical functional parameters,oxidative stress and epigenetic modulation in post-stroke individuals.In this crossover design study,12 post-stroke individuals aged 54–72 years of either sexes were included and subjected to a single session of exercise(45 minutes)without WalkAide functional electrical stimulation(EXE alone group),followed by another single session of exercise(45 minutes)with WalkAide functional electrical stimulation(EXE+FES group).The clinical functional outcome measures,cognitive performance and blood collections for biomarker measurements were assessed pre-and post-intervention.After intervention,higher Berg Balance Scale scores were obtained in the EXE+FES group than in the EXE alone group.There was no significant difference in the Timed Up and Go test results post-intervention between EXE alone and EXE+FES groups.After intervention,a better cognitive performance was found in both groups compared with before the intervention.After intervention,the Timed Up and Go test scores were higher in the EXE+FES group than in the EXE alone group.In addition,the intervention induced lower levels of lipid peroxidation.After intervention,carbonyl level was lower,superoxide dismutase activity and superoxide dismutase/catalase activity ratio were higher in the EXE+FES group,compared with the EXE group alone.In each group,both histone dea展开更多
The quality of an A1GaN channel heterojunction on a sapphire substrate is massively improved by using an A1- GaN/GaN composite buffer layer. We demonstrate an A10.4Gao.6N/AI0.18Ga0.82N heterojunction with a state-of-t...The quality of an A1GaN channel heterojunction on a sapphire substrate is massively improved by using an A1- GaN/GaN composite buffer layer. We demonstrate an A10.4Gao.6N/AI0.18Ga0.82N heterojunction with a state-of-the-art mobility of 815 cm2/（V.s） and a sheet resistance of 890Ω/口 under room temperature. The crystalline quality and the electrical properties of the A1GaN heterojunction material are analyzed by atomic force microscopy, high-resolution X-ray diffraction, and van der Pauw Hall and capacitance-voltage （C-V） measurements. The results indicate that the improved electrical properties should derive from the reduced surface roughness and low dislocation density.展开更多
The InGaAs/InAIAs/InP high electron mobility transistor （HEM：F） structures with lattice-matched and pseudo- morphic channels are grown by gas source molecular beam epitaxy. Effects of Si ^-doping condition and grow...The InGaAs/InAIAs/InP high electron mobility transistor （HEM：F） structures with lattice-matched and pseudo- morphic channels are grown by gas source molecular beam epitaxy. Effects of Si ^-doping condition and growth interruption on the electrical properties are investigated by changing the Si-cell temperature, doping time and growth process. It is found that the optimal Si ^-doping concentration （Nd） is about 5.0 x 1012 cm-2 and the use of growth interruption has a dramatic effect on the improvement of electrical properties. The material structure and crystal interface are analyzed by secondary ion mass spectroscopy and high resolution transmission elec- tron microscopy. An InGaAs/InAiAs/InP HEMT device with a gate length of lOOnm is fabricated. The device presents good pinch-off characteristics and the kink-effect of the device is trifling. In addition, the device exhibits fT = 249 GHa and fmax 〉 400 GHz.展开更多
The Electrical properties as a function of temperature were investigated at elevated temperatures (300 K - 800 K) on quenched samples of donor doped La-BaTiO3 system. The resistivity and carrier concentration increase...The Electrical properties as a function of temperature were investigated at elevated temperatures (300 K - 800 K) on quenched samples of donor doped La-BaTiO3 system. The resistivity and carrier concentration increased with increasing temperature. The mobility of the sample shows exponential temperature dependence and the value of mobility is in well agreement with the theoretical values. From the conductivity data the activation energy was calculated (0.036 eV) and revealed that the conduction mechanism in this system is thermally activated.展开更多
Compact molecular packing with short π-π stacking and large π-overlap in organic semiconductors is desirable for efficient charge transport and high carrier mobility. Thus charge transport anisotropy along differen...Compact molecular packing with short π-π stacking and large π-overlap in organic semiconductors is desirable for efficient charge transport and high carrier mobility. Thus charge transport anisotropy along different directions is commonly observed in organic semiconductors. Interestingly, in this article, we found that comparable charge transport property were achieved based on the single crystals of a bis-fused tetrathiafulvalene derivative （EM-TTP） compound along two interaction directions, that is, the multiple strong S…S intermolecular interactions and the π-π stacking direction, with the measured electrical conductivity and hole mobility of 0.4 S cm-1, 0.94 cm2 V i s 1 and 0.2 S cm-1, 0.65 cm2 V-1 s-1, respectively. This finding provides us a new molecular design concept for developing novel organic semiconductors with isotropic charge transport property through the synergistic effect of multiple intermolecular interactions （such as π-π interactions） and π-π stacking.展开更多
As one of the most important tumor-associated antigens of colorectal adenocarcinoma, the carcinoembryonic antigen （CEA） threatens human health seriously ali over the globe. Fast electrical and highly sensitive detec...As one of the most important tumor-associated antigens of colorectal adenocarcinoma, the carcinoembryonic antigen （CEA） threatens human health seriously ali over the globe. Fast electrical and highly sensitive detection of the CEA with A1GaN/GaN high electron mobility transistor is demonstrated experimentally. To achieve a low detection limit, the Au-gated sensing area of the sensor is functionalized with a CEA aptamer instead of the corresponding antibody. The proposed aptasensor has successfully detected different concentrations （ranging from 50picogram/milliliter （pg/ml） to 50 nanogram/milliliter （ng/ml）） of CEA and achieved a detection limit as low as 50pg/ml at Vas = 0.5 V. The drain-source current shows a c/ear increase of 11.5μA under this bias.展开更多
An aerosol electrical mobility spectrum analyzer(AEMSA),developed at Hanyang University,was employed to investigate the particle charge characteristics in the Antarctic and Arctic regions.The particle charge character...An aerosol electrical mobility spectrum analyzer(AEMSA),developed at Hanyang University,was employed to investigate the particle charge characteristics in the Antarctic and Arctic regions.The particle charge characteristics in these areas were compared with the charging state in Ansan,South Korea,located in the midlatitude,where artificial factors,such as human activity,urbanization,and traffic,might result in a higher total concentration.Furthermore,in Ansan,South Korea,the charged-particle polarity ratio was very stable and was close to 1.However,notably different particle charge characteristics were obtained in the Antarctic and Arctic regions.The imbalance between the numbers of positively and negatively charged particles was evident,resulting in more positive charges on the atmospheric particles.On average,the positively charged particle concentrations in the Antarctic and Arctic areas were 1.4 and 2.8 times higher,respectively,compared with the negatively charged particles.The developed AEMSA system and the findings of this study provide useful information on the characteristics of atmospheric aerosols in the Antarctic and Arctic regions and can be further utilized to study particle formation mechanisms.展开更多
文摘用融熔法研制了 In_2O_3和 ITO(In_2O_3掺杂 Sn)单晶,并对其光电性能进行研究.纯 ITO 是一种简并半导体,在常温下,以晶格声子散射为主要的载流子传输机理.对 ITO 单晶,给出了载流子浓度与 Sn 掺杂浓度及载流子迁移率的关系.并对在单晶中由于用助溶剂而引入的 Pb 掺杂对材料电性能的影响作了探讨.从材料的吸收光谱图中的本征吸收限的变化及 Plasma 频率和坡度的变化,证实了我们对电性能测试的结果.EXAFS 结构测试结果给出了这二种材料导电率变化的因素.
基金L. M. X. acknowledges support from National Natural Science Foundation of China （Nos. 21373066 and 11304052）, Beijing Nova programme （No. Z151100000315081） and Beijing Talents Fund （No. 2015000021223ZK17）. C. Z. C. acknowledges support from the Program for New Century Excellent Talents in University of China （No. NCET-07-0903）.
文摘Two-dimensional ZrS2 materials have potential for applications in nanoelectronics because of their theoretically predicted high mobility and sheet current density. Herein, we report the thickness and temperature dependent transport properties of ZrS2 multilayers that were directly deposited on hexagonal boron nitride （h-BN） by chemical vapor deposition. Hysteresis-free gate sweeping, metal- insulator transition, and T-γ （γ- 0.82-1.26） temperature dependent mobility were observed in the ZrS2 films.
文摘The general expressions based on the Fermi distribution of the free charge carriers are applied for estimation of the transport characteristics in superconductors at the temperature well above the superconducting phase transition temperature TC. The Hall-effect experimental results in the normal state of the superconductor YBa2Cu3O7-δ are not finally explained. On the ground of the randomly moving charge carriers, the transport characteristics of the randomly moving charge carriers for both single type and two types of the charge carriers are presented. The particular attention has been pointed to the Hall-effect measurement results of the high-TC superconductor YBa2Cu3O7-δ. It is at the first time derived the Hall coefficient expression for two type of highly degenerate charge carriers (electrons and holes) on the ground of the randomly moving charge carriers at the Fermi surface. It is shown that the Hall coefficient and other transport characteristics are determined by the ratio between the electron-like and hole-like densities of states at the Fermi surface.
文摘The general expressions, based on the Fermi distribution of the free electrons, are applied for calculation of the kinetic coefficients in donor-doped silicon at arbitrary degree of the degeneracy of electron gas under equilibrium conditions. The classical statistics lead to large errors in estimation of the transport parameters for the materials where Fermi level is located high above the conduction band edge unless the effective density of randomly moving electrons is introduced. The obtained results for the diffusion coefficient and drift mobility are discussed together with practical approximations applicable for non-degenerate electron gas and materials with arbitrary degree of degeneracy. In particular, the drift mobility of randomly moving electrons is found to depend on the degree of degeneracy and can exceed the Hall mobility considerably. When the effective density is introduced, the traditional Einstein relation between the diffusion coefficient and the drift mobility of randomly moving electrons is conserved at any level of degeneracy. The main conclusions and formulae can be applicable for holes in acceptor-doped silicon as well.
基金This work was supported by Fundação de AmparoàPesquisa do Estado do Rio Grande do Sul(FAPERGS)/BrazilandConselhoNacional de DesenvolvimentoCientífico e Tecnológico–CNPq/Brazil.
文摘A growing body of evidence has suggested that the imbalance of epigenetic markers and oxidative stress appears to be involved in the pathophysiology and progression of stroke.Thus,strategies that modulate these biomarkers might be considered targets for neuroprotection and novel therapeutic opportunities for these patients.Physical exercise has been reported to induce changes in these epigenetic markers and improve clinical outcomes in different populations.However,little is reported on this in post-stroke patients.The purpose of this study was to investigate the effect of a single exercise session with WalkAide functional electrical stimulation(FES)on cognitive performance,clinical functional parameters,oxidative stress and epigenetic modulation in post-stroke individuals.In this crossover design study,12 post-stroke individuals aged 54–72 years of either sexes were included and subjected to a single session of exercise(45 minutes)without WalkAide functional electrical stimulation(EXE alone group),followed by another single session of exercise(45 minutes)with WalkAide functional electrical stimulation(EXE+FES group).The clinical functional outcome measures,cognitive performance and blood collections for biomarker measurements were assessed pre-and post-intervention.After intervention,higher Berg Balance Scale scores were obtained in the EXE+FES group than in the EXE alone group.There was no significant difference in the Timed Up and Go test results post-intervention between EXE alone and EXE+FES groups.After intervention,a better cognitive performance was found in both groups compared with before the intervention.After intervention,the Timed Up and Go test scores were higher in the EXE+FES group than in the EXE alone group.In addition,the intervention induced lower levels of lipid peroxidation.After intervention,carbonyl level was lower,superoxide dismutase activity and superoxide dismutase/catalase activity ratio were higher in the EXE+FES group,compared with the EXE group alone.In each group,both histone dea
基金Project supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China(Grant Nos.2011ZX01002-002 and 2013ZX02308-002)the Fundamental Research Funds for the Central Universities of Ministry of Education of Chinathe National Natural Science Foundation of China(Grant Nos.61204006 and 61106063)
文摘The quality of an A1GaN channel heterojunction on a sapphire substrate is massively improved by using an A1- GaN/GaN composite buffer layer. We demonstrate an A10.4Gao.6N/AI0.18Ga0.82N heterojunction with a state-of-the-art mobility of 815 cm2/（V.s） and a sheet resistance of 890Ω/口 under room temperature. The crystalline quality and the electrical properties of the A1GaN heterojunction material are analyzed by atomic force microscopy, high-resolution X-ray diffraction, and van der Pauw Hall and capacitance-voltage （C-V） measurements. The results indicate that the improved electrical properties should derive from the reduced surface roughness and low dislocation density.
基金Supported by the National Natural Science Foundation of China under Grant No 61434006
文摘The InGaAs/InAIAs/InP high electron mobility transistor （HEM：F） structures with lattice-matched and pseudo- morphic channels are grown by gas source molecular beam epitaxy. Effects of Si ^-doping condition and growth interruption on the electrical properties are investigated by changing the Si-cell temperature, doping time and growth process. It is found that the optimal Si ^-doping concentration （Nd） is about 5.0 x 1012 cm-2 and the use of growth interruption has a dramatic effect on the improvement of electrical properties. The material structure and crystal interface are analyzed by secondary ion mass spectroscopy and high resolution transmission elec- tron microscopy. An InGaAs/InAiAs/InP HEMT device with a gate length of lOOnm is fabricated. The device presents good pinch-off characteristics and the kink-effect of the device is trifling. In addition, the device exhibits fT = 249 GHa and fmax 〉 400 GHz.
文摘The Electrical properties as a function of temperature were investigated at elevated temperatures (300 K - 800 K) on quenched samples of donor doped La-BaTiO3 system. The resistivity and carrier concentration increased with increasing temperature. The mobility of the sample shows exponential temperature dependence and the value of mobility is in well agreement with the theoretical values. From the conductivity data the activation energy was calculated (0.036 eV) and revealed that the conduction mechanism in this system is thermally activated.
基金supported by the Ministry of Science and Technology of China(2016YFB0401100,2013CB933403,2013CB933504)the National Natural Science Foundation of China(51633006,91433115,51222306,91222203,91233205,21472116)+3 种基金Chinese Academy of Sciences(XDB12030300)Beijing NOVA Programmer(Z131101000413038)Beijing Local College Innovation Team Improve Plan(IDHT20140512)Youth Innovation Promotion Association CAS
文摘Compact molecular packing with short π-π stacking and large π-overlap in organic semiconductors is desirable for efficient charge transport and high carrier mobility. Thus charge transport anisotropy along different directions is commonly observed in organic semiconductors. Interestingly, in this article, we found that comparable charge transport property were achieved based on the single crystals of a bis-fused tetrathiafulvalene derivative （EM-TTP） compound along two interaction directions, that is, the multiple strong S…S intermolecular interactions and the π-π stacking direction, with the measured electrical conductivity and hole mobility of 0.4 S cm-1, 0.94 cm2 V i s 1 and 0.2 S cm-1, 0.65 cm2 V-1 s-1, respectively. This finding provides us a new molecular design concept for developing novel organic semiconductors with isotropic charge transport property through the synergistic effect of multiple intermolecular interactions （such as π-π interactions） and π-π stacking.
基金Supported by the National Key Research and Development Program of China under Grant Nos 2016YFB0400104 and 2016YFB0400301the National Natural Science Foundation of China under Grant No 61334002the National Science and Technology Major Project
文摘As one of the most important tumor-associated antigens of colorectal adenocarcinoma, the carcinoembryonic antigen （CEA） threatens human health seriously ali over the globe. Fast electrical and highly sensitive detection of the CEA with A1GaN/GaN high electron mobility transistor is demonstrated experimentally. To achieve a low detection limit, the Au-gated sensing area of the sensor is functionalized with a CEA aptamer instead of the corresponding antibody. The proposed aptasensor has successfully detected different concentrations （ranging from 50picogram/milliliter （pg/ml） to 50 nanogram/milliliter （ng/ml）） of CEA and achieved a detection limit as low as 50pg/ml at Vas = 0.5 V. The drain-source current shows a c/ear increase of 11.5μA under this bias.
基金supported by the research fund of Hanyang University(HY-2019-P).
文摘An aerosol electrical mobility spectrum analyzer(AEMSA),developed at Hanyang University,was employed to investigate the particle charge characteristics in the Antarctic and Arctic regions.The particle charge characteristics in these areas were compared with the charging state in Ansan,South Korea,located in the midlatitude,where artificial factors,such as human activity,urbanization,and traffic,might result in a higher total concentration.Furthermore,in Ansan,South Korea,the charged-particle polarity ratio was very stable and was close to 1.However,notably different particle charge characteristics were obtained in the Antarctic and Arctic regions.The imbalance between the numbers of positively and negatively charged particles was evident,resulting in more positive charges on the atmospheric particles.On average,the positively charged particle concentrations in the Antarctic and Arctic areas were 1.4 and 2.8 times higher,respectively,compared with the negatively charged particles.The developed AEMSA system and the findings of this study provide useful information on the characteristics of atmospheric aerosols in the Antarctic and Arctic regions and can be further utilized to study particle formation mechanisms.
