The high critical electric field strength of Ga_(2)O_(3)enables higher operating voltages and reduced switching losses in power electronic devices.Suitable Schottky metals and epitaxial films are essential for further...The high critical electric field strength of Ga_(2)O_(3)enables higher operating voltages and reduced switching losses in power electronic devices.Suitable Schottky metals and epitaxial films are essential for further enhancing device performance.In this work,the fabrication of vertical Ga_(2)O_(3)barrier diodes with three different barrier metals was carried out on an n--Ga_(2)O_(3)homogeneous epitaxial film deposited on an n+-β-Ga_(2)O_(3)substrate by metal-organic chemical vapor deposition,excluding the use of edge terminals.The ideal factor,barrier height,specific on-resistance,and breakdown voltage characteristics of all devices were investigated at room temperature.In addition,the vertical Ga_(2)O_(3)barrier diodes achieve a higher breakdown volt-age and exhibit a reverse leakage as low as 4.82×10^(-8)A/cm^(2)by constructing a NiO/Ga_(2)O_(3)heterojunction.Therefore,Ga_(2)O_(3)power detailed investigations into Schottky barrier metal and NiO/Ga_(2)O_(3)heterojunction of Ga_(2)O_(3)homogeneous epitaxial films are of great research potential in high-efficiency,high-power,and high-reliability applications.展开更多
Gallium oxide(Ga_2O_3), a typical ultra wide bandgap semiconductor, with a bandgap of ~4.9 e V, critical breakdown field of 8 MV/cm, and Baliga's figure of merit of 3444, is promising to be used in high-power and ...Gallium oxide(Ga_2O_3), a typical ultra wide bandgap semiconductor, with a bandgap of ~4.9 e V, critical breakdown field of 8 MV/cm, and Baliga's figure of merit of 3444, is promising to be used in high-power and high-voltage devices.Recently, a keen interest in employing Ga_2O_3 in power devices has been aroused. Many researches have verified that Ga_2O_3 is an ideal candidate for fabricating power devices. In this review, we summarized the recent progress of field-effect transistors(FETs) and Schottky barrier diodes(SBDs) based on Ga_2O_3, which may provide a guideline for Ga_2O_3 to be preferably used in power devices fabrication.展开更多
A self-powered solar-blind ultraviolet(UV)photodetector(PD)was successfully constructed on a Ga_(2)O_(3)/Bi_(2)WO_(6)heterojunction,which was fabricated by spin-coating the hydrothermally grown Bi_(2)WO_(6)onto MOCVD-...A self-powered solar-blind ultraviolet(UV)photodetector(PD)was successfully constructed on a Ga_(2)O_(3)/Bi_(2)WO_(6)heterojunction,which was fabricated by spin-coating the hydrothermally grown Bi_(2)WO_(6)onto MOCVD-grown Ga_(2)O_(3)film.The results show that a typical type-I heterojunction is formed at the interface of the Ga_(2)O_(3)film and clustered Bi_(2)WO_(6),which demonstrates a distinct photovoltaic effect with an open-circuit voltage of 0.18 V under the irradiation of 254 nm UV light.Moreover,the Ga_(2)O_(3)/Bi_(2)WO_(6)PD displays excellent photodetection performance with an ultra-low dark current of~6 fA,and a high light-to-dark current ratio(PDCR)of 3.5 x 10^(4)in self-powered mode(0 V),as well as a best responsivity result of 2.21 mA/W in power supply mode(5 V).Furthermore,the PD possesses a stable and fast response speed under different light intensities and voltages.At zero voltage,the PD exhibits a fast rise time of 132 ms and 162 ms,as well as a quick decay time of 69 ms and 522 ms,respectively.In general,the newly attempted Ga_(2)O_(3)/Bi_(2)WO_(6)heterojunction may become a potential candidate for the realization of self-powered and high-performance UV photodetectors.展开更多
Ar-N_(2)-O_(2)ternary shielding gas is employed in dissimilar welding between high nitrogen steel and low alloy steel.The effect of O_(2)and N_(2)is investigated based on the systematical analysis of the metal transfe...Ar-N_(2)-O_(2)ternary shielding gas is employed in dissimilar welding between high nitrogen steel and low alloy steel.The effect of O_(2)and N_(2)is investigated based on the systematical analysis of the metal transfer,nitrogen escape phenomenon,weld appearance,nondestructive detection,nitrogen content distribution,microstructure and mechanical properties.There are two nitrogen sources of the nitrogen in the weld:high nitrogen base material and shielding gas.The effect of shielding gas is mainly reflected in these two aspects.The change of the droplet transfer mode affects the fusion ratio,N2in the shielding gas can increase nitrogen content and promote the nitrogen uniform distribution.The addition of 2%O_(2)to Ar matrix can change the metal transfer from globular transfer to spray transfer,high nitrogen base material is thereby dissolved more to the molten pool,making nitrogen content increase,ferrite decrease and the mechanical properties improve.When applying N2-containing shielding gas,arc stability becomes poor and short-circuiting transfer frequency increases due to the nitrogen escape from droplets and the molten pool.Performance of the joints is improved with N_(2)increasing,but internal gas pores are easier to appear because of the poor capacity of low alloy steel to dissolve nitrogen,The generation of pores will greatly reduce the impact resistance.4-8%N2content in shielding gas is recommended in this study considering the integrated properties of the dissimilar welded joint.展开更多
A flower-like SnO_(2)–SnO/porous Ga N(FSS/PGaN) heterojunction was fabricated for the first time via a facile spraying process, and the whole process also involved hydrothermal preparation of FSS and electrochemical ...A flower-like SnO_(2)–SnO/porous Ga N(FSS/PGaN) heterojunction was fabricated for the first time via a facile spraying process, and the whole process also involved hydrothermal preparation of FSS and electrochemical wet etching of GaN,and SnO_(2)–SnO composites with p–n junctions were loaded onto PGaN surface directly applied to H_(2)S sensor. Meanwhile,the excellent transport capability of heterojunction between FSS and PGaN facilitates electron transfer, that is, a response time as short as 65 s and a release time up to 27 s can be achieved merely at 150℃ under 50 ppm H_(2)S concentration, which has laid a reasonable theoretical and experimental foundation for the subsequent PGaN-based heterojunction gas sensor.The lowering working temperature and high sensitivity(23.5 at 200 ppm H2S) are attributed to the structure of PGaN itself and the heterojunction between SnO_(2)–SnO and PGaN. In addition, the as-obtained sensor showed ultra-high test stability.The simple design strategy of FSS/PGaN-based H_(2)S sensor highlights its potential in various applications.展开更多
Theε-Ga_(2)O_(3) thin film was grown on sapphire substrate by using metalorganic chemical vapor deposition(MOCVD)method,and then was used to fabricate a deep-ultraviolet(DUV)photodetector(PD).Theε-Ga_(2)O_(3) thin f...Theε-Ga_(2)O_(3) thin film was grown on sapphire substrate by using metalorganic chemical vapor deposition(MOCVD)method,and then was used to fabricate a deep-ultraviolet(DUV)photodetector(PD).Theε-Ga_(2)O_(3) thin film shown good crystal quality and decent surface morphology.Irradiated by a 254-nm DUV light,the photodetector displayed good optoelectronic performance and high wavelength selectivity,such as photoresponsivity(R)of 175.69 A/W,detectivity(D*)of 2.46×10^(15) Jones,external quantum efficiency(EQE)of 8.6×10^(4)%and good photocurrent-intensity linearity,suggesting decent DUV photosensing performance.At 5 V and under illumination with light intensity of 800μW/cm2,the photocurrent gain is as high as 859 owing to the recycling gain mechanism and delayed carrier recombination;and the photocurrent gain decreases as the incident light intensity increases because of the recombination of photogenerated carriers by the large photon flux.展开更多
As a promising ultra-wide bandgap semiconductor material,gallium oxide(Ga_(2)O_(3))is attracting extensive attention of researchers due to its feasible growth process,appropriate bandgap of 4.4 e V-5.3 e V allowing fo...As a promising ultra-wide bandgap semiconductor material,gallium oxide(Ga_(2)O_(3))is attracting extensive attention of researchers due to its feasible growth process,appropriate bandgap of 4.4 e V-5.3 e V allowing for deep-ultraviolet(deepUV)detection,good physical and chemical stability,high breakdown field strength and electron mobility,etc.Different from the strict processes for controllable crystalline Ga_(2)O_(3)(usually refer to as stable monoclinicβ-Ga_(2)O_(3)),amorphous Ga_(2)O_(3)(a-Ga_(2)O_(3))film can be prepared uniformly at low temperature on a large-area deposition substrate,suggesting great advantages such as low manufacturing cost and excellent flexibility,dispensing with high-temperature and high vacuum techniques.Thus,a-Ga_(2)O_(3)extremely facilitates important applications in various applied fields.Therefore,in this concise review,we summarize several major deposition methods for a-Ga_(2)O_(3)films,of which the characteristics are discussed.Additionally,potential methods to optimize the film properties are proposed by right of the inspiration from some recent studies.Subsequently,the applications of a-Ga_(2)O_(3)thin films,e.g.,in photodetectors,resistive random access memories(RRAMs)and gas sensors,are represented with a fruitful discussion of their structures and operating mechanisms.展开更多
To improve the efficiency of the desulfurization process, the drawdown mechanism of light particles in stirred tank is studied in this paper. For both up and down pumping modes, the just drawdown speeds(Njd) of floati...To improve the efficiency of the desulfurization process, the drawdown mechanism of light particles in stirred tank is studied in this paper. For both up and down pumping modes, the just drawdown speeds(Njd) of floating particles in transformative Kanbara Reactor(KR) are measured in one and four baffled stirred tanks experimentally. Then numerical simulations with standard k-ε model coupled with volume of fluid model(VOF) and discrete phase model(DPM) are conducted to analyze the flow field at the just drawdown speed Njd. The torques on the impeller obtained from experiments and simulations agree well with each other, which indicates the validity of our numerical simulations. Based on the simulations, three main drawdown mechanisms for floating particles, the axial circulation, turbulent fluctuation and largescale eddies, are analyzed. It's found that the axial circulation dominates the drawdown process at small submergence(S = 1/4 T and 1/3 T) and the large-scale eddies play a major role at large submergence(S = 2/3 T and 3/4 T). Besides, the turbulent fluctuation affects the drawdown process significantly for up pumping mode at small submergence(S = 1/4 T and 1/3 T) and for down pumping mode at large submergence(S = 2/3 T and 3/4 T). This paper helps to provide a more comprehensive understanding of the KR desulphurizer drawdown process in the baffled stirred tank.展开更多
Melatonin is a naturally occurring compound in plants. Here, we tested the effect of exogenous melatonin on rapeseed(Brassica napus L.) grown under salt stress. Application of 30 μmol L^(–1) melatonin alleviated sal...Melatonin is a naturally occurring compound in plants. Here, we tested the effect of exogenous melatonin on rapeseed(Brassica napus L.) grown under salt stress. Application of 30 μmol L^(–1) melatonin alleviated salt-induced growth inhibition, and the shoot fresh weight, the shoot dry weight, the root fresh weight, and the root dry weight of seedlings treated with exogenous melatonin increased by 128.2, 142.9, 122.2, and 124.2%, respectively, compared to those under salt stress. In addition, several physiological parameters were evaluated. The activities of antioxidant enzymes including peroxidase(POD), catalase(CAT) and ascorbate peroxidase(APX) were enhanced by 16.5, 19.3, and 14.2% compared to their activities in plants without exogenous melatonin application under salt stress, while the H_2O_2 content was decreased by 11.2% by exogenous melatonin. Furthermore, melatonin treatment promoted solute accumulation by increasing the contents of proline(26.8%), soluble sugars(15.1%) and proteins(58.8%). The results also suggested that higher concentrations(>50 μmol L^(–1)) of melatonin could attenuate or even prevent the beneficial effects on seedling development. In conclusion, application of a low concentration of exogenous melatonin to rapeseed plants under salt stress can improve the H_2O_2-scavenging capacity by enhancing the activities of antioxidant enzymes such as POD, CAT and APX, and can also alleviate osmotic stress by promoting the accumulation of osmoregulatory substances such as soluble proteins, proline, and water soluble glucan. Ultimately, exogenous melatonin facilitates root development and improves the biomass of rapeseed seedlings grown under salt stress, thereby effectively alleviating the damage of salt stress in rapeseed seedlings.展开更多
RNA sequencing of the sensitive GH01 variety of Brassica napus L. seedling roots under 12 h of waterlogging was compared with previously published data of the ZS9 tolerant variety to unravel genetic mechanisms of wate...RNA sequencing of the sensitive GH01 variety of Brassica napus L. seedling roots under 12 h of waterlogging was compared with previously published data of the ZS9 tolerant variety to unravel genetic mechanisms of waterlogging tolerance beyond natural variation. A total of 2 977 genes with similar expression patterns and 17 genes with opposite expression patterns were identified in the transcription profiles of ZS9 and GH01. An additional 1 438 genes in ZS9 and 1 861 genes in GH01 showed strain specific regulation. Analysis of the overlapped genes between ZS9 and GH01 revealed that waterlogging tolerance is determined by ability to regulate genes with similar expression patterns. Moreover, differences in both gene expression profiles and abscisic acid(ABA) contents between the two varieties suggest that ABA may play some role in waterlogging tolerance. This study identifies a subset of candidate genes for further functional analysis.展开更多
AIM:To determine the effect of different Roux-en-Y gastric bypass procedures in gastric carcinoma patients with type 2 diabetes mellitus.METHODS:A retrospective analysis of the clinical data of 54 patients with gastri...AIM:To determine the effect of different Roux-en-Y gastric bypass procedures in gastric carcinoma patients with type 2 diabetes mellitus.METHODS:A retrospective analysis of the clinical data of 54 patients with gastric cancer and type 2 diabetes mellitus treated in the Department of General Surgery from January 2006 to June 2013 was conducted.The patients underwent gastrectomy using different Rouxen-Y gastric bypass procedures(traditional,n=26;modified,n=28).Fasting plasma glucose(FPG),two hour postprandial blood glucose(2 h PBG)and hemoglobin A1c(Hb A1c)were analyzed before surgery(0 mo)and 1,3 and 6 mo after surgery.RESULTS:FPG and 2 h PBG levels were significantlydecreased 1 mo after surgery in the traditional Rouxen-Y gastric bypass group(FPG 7.5±1.3 vs 10.7±1.2,P<0.05)(2 h PBG 10.2±1.8 vs 13.8±3.2,P<0.05).FPG and 2 h PBG levels were significantly decreased after surgery in the modified Roux-en-Y gastric bypass group(FPG 6.9±1.2 vs 10.5±1.1,6.5±1.3 vs 10.5±1.1,6.4±1.2 vs 10.5±1.1,P<0.05)(2 h PBG9.9±2.2 vs 14.1±2.9,9.2±2.4 vs 14.1±2.9,8.9±2.6 vs 14.1±2.9,P<0.05).Compared with the levels before surgery,Hb A1c levels were significantly decreased 3 and 6 mo after surgery(7.2±1.1 vs 10.5±1.1,5.5±1.1 vs 10.5±1.1,P<0.05).Significant differences between the two groups regarding FPG,2 h PBG and Hb A1c concentration were observed 3 and 6mo after surgery(FPG 10.1±1.5 vs 6.5±1.3,10.3±1.4 vs 6.4±1.2,P<0.05)(2 h PBG 13.1±2.8 vs 9.2±2.4,13.6±3.1 vs 8.9±2.6,P<0.05)(Hb A1c 10.1±1.4 vs 7.2±1.1,10.5±1.3 vs 5.5±1.1,P<0.05).CONCLUSION:Modified Roux-en-Y gastric bypass can improve glucose metabolism in type 2 diabetic patients with gastric cancer.展开更多
High nitrogen stainless steel with nitrogen content of 0.75%was welded by gas metal arc welding with Ar-N_(2)-O_(2)ternary shielding gas.The effect of the ternary shielding gas on the retention and improvement of nitr...High nitrogen stainless steel with nitrogen content of 0.75%was welded by gas metal arc welding with Ar-N_(2)-O_(2)ternary shielding gas.The effect of the ternary shielding gas on the retention and improvement of nitrogen content in the weld was identified.Surfacing test was conducted first to compare the ability of O_(2)and CO_(2)in prompting nitrogen dissolution.The nitrogen content of the surfacing metal with O_(2)is slightly higher than CO_(2).And then AreN_(2)-O_(2)shielding gas was applied to weld high nitrogen stainless steel.After using N_(2)-containing shielding gas,the nitrogen content of the weld was improved by 0.1 wt%.As N_(2)continued to increase,the increment of nitrogen content was not obvious,but the ferrite decreased from the top to the bottom.When the proportion of N_(2)reached 20%,a full austenitic weld was obtained and the tensile strength was improved by 8.7%.Combined with the results of surfacing test and welding test,it is concluded that the main effect of N_(2)is to inhibit the escape of nitrogen and suppress the nitrogen diffusion from bottom to the top in the molten pool.展开更多
基金supported by BUPT Excellent Ph.D. Students Foundation (CX2023301)in part by the National Natural Science Foundation of China (62204019)
文摘The high critical electric field strength of Ga_(2)O_(3)enables higher operating voltages and reduced switching losses in power electronic devices.Suitable Schottky metals and epitaxial films are essential for further enhancing device performance.In this work,the fabrication of vertical Ga_(2)O_(3)barrier diodes with three different barrier metals was carried out on an n--Ga_(2)O_(3)homogeneous epitaxial film deposited on an n+-β-Ga_(2)O_(3)substrate by metal-organic chemical vapor deposition,excluding the use of edge terminals.The ideal factor,barrier height,specific on-resistance,and breakdown voltage characteristics of all devices were investigated at room temperature.In addition,the vertical Ga_(2)O_(3)barrier diodes achieve a higher breakdown volt-age and exhibit a reverse leakage as low as 4.82×10^(-8)A/cm^(2)by constructing a NiO/Ga_(2)O_(3)heterojunction.Therefore,Ga_(2)O_(3)power detailed investigations into Schottky barrier metal and NiO/Ga_(2)O_(3)heterojunction of Ga_(2)O_(3)homogeneous epitaxial films are of great research potential in high-efficiency,high-power,and high-reliability applications.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61774019,51572033,and 51572241)the Beijing Municipal Commission of Science and Technology,China(Grant No.SX2018-04)
文摘Gallium oxide(Ga_2O_3), a typical ultra wide bandgap semiconductor, with a bandgap of ~4.9 e V, critical breakdown field of 8 MV/cm, and Baliga's figure of merit of 3444, is promising to be used in high-power and high-voltage devices.Recently, a keen interest in employing Ga_2O_3 in power devices has been aroused. Many researches have verified that Ga_2O_3 is an ideal candidate for fabricating power devices. In this review, we summarized the recent progress of field-effect transistors(FETs) and Schottky barrier diodes(SBDs) based on Ga_2O_3, which may provide a guideline for Ga_2O_3 to be preferably used in power devices fabrication.
基金Project supported by the National Key Research and Development Program of China(Grant No.2022YFB3605404)Natural Science Research Start up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications(Grant Nos.XK1060921119,XK1060921115,and XK1060921002)+1 种基金National Natural Science Foundation of China(Grant No.62204125)China Postdoctoral Science Foundation(Grant No.2022M721689)。
文摘A self-powered solar-blind ultraviolet(UV)photodetector(PD)was successfully constructed on a Ga_(2)O_(3)/Bi_(2)WO_(6)heterojunction,which was fabricated by spin-coating the hydrothermally grown Bi_(2)WO_(6)onto MOCVD-grown Ga_(2)O_(3)film.The results show that a typical type-I heterojunction is formed at the interface of the Ga_(2)O_(3)film and clustered Bi_(2)WO_(6),which demonstrates a distinct photovoltaic effect with an open-circuit voltage of 0.18 V under the irradiation of 254 nm UV light.Moreover,the Ga_(2)O_(3)/Bi_(2)WO_(6)PD displays excellent photodetection performance with an ultra-low dark current of~6 fA,and a high light-to-dark current ratio(PDCR)of 3.5 x 10^(4)in self-powered mode(0 V),as well as a best responsivity result of 2.21 mA/W in power supply mode(5 V).Furthermore,the PD possesses a stable and fast response speed under different light intensities and voltages.At zero voltage,the PD exhibits a fast rise time of 132 ms and 162 ms,as well as a quick decay time of 69 ms and 522 ms,respectively.In general,the newly attempted Ga_(2)O_(3)/Bi_(2)WO_(6)heterojunction may become a potential candidate for the realization of self-powered and high-performance UV photodetectors.
文摘Ar-N_(2)-O_(2)ternary shielding gas is employed in dissimilar welding between high nitrogen steel and low alloy steel.The effect of O_(2)and N_(2)is investigated based on the systematical analysis of the metal transfer,nitrogen escape phenomenon,weld appearance,nondestructive detection,nitrogen content distribution,microstructure and mechanical properties.There are two nitrogen sources of the nitrogen in the weld:high nitrogen base material and shielding gas.The effect of shielding gas is mainly reflected in these two aspects.The change of the droplet transfer mode affects the fusion ratio,N2in the shielding gas can increase nitrogen content and promote the nitrogen uniform distribution.The addition of 2%O_(2)to Ar matrix can change the metal transfer from globular transfer to spray transfer,high nitrogen base material is thereby dissolved more to the molten pool,making nitrogen content increase,ferrite decrease and the mechanical properties improve.When applying N2-containing shielding gas,arc stability becomes poor and short-circuiting transfer frequency increases due to the nitrogen escape from droplets and the molten pool.Performance of the joints is improved with N_(2)increasing,but internal gas pores are easier to appear because of the poor capacity of low alloy steel to dissolve nitrogen,The generation of pores will greatly reduce the impact resistance.4-8%N2content in shielding gas is recommended in this study considering the integrated properties of the dissimilar welded joint.
基金supported by the Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications (Grant Nos. XK1060921115 and XK1060921002)Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 62204125)+1 种基金the National Key R&D Program of China (Grant No. 2022YFB3605404)the Natural Science Foundation of Guangdong Province, China (Grant No. 2019A1515010790)。
文摘A flower-like SnO_(2)–SnO/porous Ga N(FSS/PGaN) heterojunction was fabricated for the first time via a facile spraying process, and the whole process also involved hydrothermal preparation of FSS and electrochemical wet etching of GaN,and SnO_(2)–SnO composites with p–n junctions were loaded onto PGaN surface directly applied to H_(2)S sensor. Meanwhile,the excellent transport capability of heterojunction between FSS and PGaN facilitates electron transfer, that is, a response time as short as 65 s and a release time up to 27 s can be achieved merely at 150℃ under 50 ppm H_(2)S concentration, which has laid a reasonable theoretical and experimental foundation for the subsequent PGaN-based heterojunction gas sensor.The lowering working temperature and high sensitivity(23.5 at 200 ppm H2S) are attributed to the structure of PGaN itself and the heterojunction between SnO_(2)–SnO and PGaN. In addition, the as-obtained sensor showed ultra-high test stability.The simple design strategy of FSS/PGaN-based H_(2)S sensor highlights its potential in various applications.
基金the National Natural Science Foundation of China(Ganrt No.62004047)。
文摘Theε-Ga_(2)O_(3) thin film was grown on sapphire substrate by using metalorganic chemical vapor deposition(MOCVD)method,and then was used to fabricate a deep-ultraviolet(DUV)photodetector(PD).Theε-Ga_(2)O_(3) thin film shown good crystal quality and decent surface morphology.Irradiated by a 254-nm DUV light,the photodetector displayed good optoelectronic performance and high wavelength selectivity,such as photoresponsivity(R)of 175.69 A/W,detectivity(D*)of 2.46×10^(15) Jones,external quantum efficiency(EQE)of 8.6×10^(4)%and good photocurrent-intensity linearity,suggesting decent DUV photosensing performance.At 5 V and under illumination with light intensity of 800μW/cm2,the photocurrent gain is as high as 859 owing to the recycling gain mechanism and delayed carrier recombination;and the photocurrent gain decreases as the incident light intensity increases because of the recombination of photogenerated carriers by the large photon flux.
基金Project supported by the National Key Research and Development Program of China(Grant No.2022YFB3605404)the National Natural Science Foundation of China(Grant Nos.62204126 and 62204125)+1 种基金the Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications(Grant Nos.XK1060921119,XK1060921002,and XK1060921115)the Open Fund of the Key Laboratory of Aerospace Information Materials and Physics(NUAA)MIIT。
文摘As a promising ultra-wide bandgap semiconductor material,gallium oxide(Ga_(2)O_(3))is attracting extensive attention of researchers due to its feasible growth process,appropriate bandgap of 4.4 e V-5.3 e V allowing for deep-ultraviolet(deepUV)detection,good physical and chemical stability,high breakdown field strength and electron mobility,etc.Different from the strict processes for controllable crystalline Ga_(2)O_(3)(usually refer to as stable monoclinicβ-Ga_(2)O_(3)),amorphous Ga_(2)O_(3)(a-Ga_(2)O_(3))film can be prepared uniformly at low temperature on a large-area deposition substrate,suggesting great advantages such as low manufacturing cost and excellent flexibility,dispensing with high-temperature and high vacuum techniques.Thus,a-Ga_(2)O_(3)extremely facilitates important applications in various applied fields.Therefore,in this concise review,we summarize several major deposition methods for a-Ga_(2)O_(3)films,of which the characteristics are discussed.Additionally,potential methods to optimize the film properties are proposed by right of the inspiration from some recent studies.Subsequently,the applications of a-Ga_(2)O_(3)thin films,e.g.,in photodetectors,resistive random access memories(RRAMs)and gas sensors,are represented with a fruitful discussion of their structures and operating mechanisms.
基金Supported by the National Natural Science Foundation of China(51474109,51609090,51679097)the Science Research Project of Huazhong University of Science and Technology(0118140077,2006140115)
文摘To improve the efficiency of the desulfurization process, the drawdown mechanism of light particles in stirred tank is studied in this paper. For both up and down pumping modes, the just drawdown speeds(Njd) of floating particles in transformative Kanbara Reactor(KR) are measured in one and four baffled stirred tanks experimentally. Then numerical simulations with standard k-ε model coupled with volume of fluid model(VOF) and discrete phase model(DPM) are conducted to analyze the flow field at the just drawdown speed Njd. The torques on the impeller obtained from experiments and simulations agree well with each other, which indicates the validity of our numerical simulations. Based on the simulations, three main drawdown mechanisms for floating particles, the axial circulation, turbulent fluctuation and largescale eddies, are analyzed. It's found that the axial circulation dominates the drawdown process at small submergence(S = 1/4 T and 1/3 T) and the large-scale eddies play a major role at large submergence(S = 2/3 T and 3/4 T). Besides, the turbulent fluctuation affects the drawdown process significantly for up pumping mode at small submergence(S = 1/4 T and 1/3 T) and for down pumping mode at large submergence(S = 2/3 T and 3/4 T). This paper helps to provide a more comprehensive understanding of the KR desulphurizer drawdown process in the baffled stirred tank.
基金supported by the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences (CAAS)the Hubei Agricultural Science and Technology Innovation Center, Chinathe Canola Key Industrial Innovation Team of Xiaogan, China
文摘Melatonin is a naturally occurring compound in plants. Here, we tested the effect of exogenous melatonin on rapeseed(Brassica napus L.) grown under salt stress. Application of 30 μmol L^(–1) melatonin alleviated salt-induced growth inhibition, and the shoot fresh weight, the shoot dry weight, the root fresh weight, and the root dry weight of seedlings treated with exogenous melatonin increased by 128.2, 142.9, 122.2, and 124.2%, respectively, compared to those under salt stress. In addition, several physiological parameters were evaluated. The activities of antioxidant enzymes including peroxidase(POD), catalase(CAT) and ascorbate peroxidase(APX) were enhanced by 16.5, 19.3, and 14.2% compared to their activities in plants without exogenous melatonin application under salt stress, while the H_2O_2 content was decreased by 11.2% by exogenous melatonin. Furthermore, melatonin treatment promoted solute accumulation by increasing the contents of proline(26.8%), soluble sugars(15.1%) and proteins(58.8%). The results also suggested that higher concentrations(>50 μmol L^(–1)) of melatonin could attenuate or even prevent the beneficial effects on seedling development. In conclusion, application of a low concentration of exogenous melatonin to rapeseed plants under salt stress can improve the H_2O_2-scavenging capacity by enhancing the activities of antioxidant enzymes such as POD, CAT and APX, and can also alleviate osmotic stress by promoting the accumulation of osmoregulatory substances such as soluble proteins, proline, and water soluble glucan. Ultimately, exogenous melatonin facilitates root development and improves the biomass of rapeseed seedlings grown under salt stress, thereby effectively alleviating the damage of salt stress in rapeseed seedlings.
文摘RNA sequencing of the sensitive GH01 variety of Brassica napus L. seedling roots under 12 h of waterlogging was compared with previously published data of the ZS9 tolerant variety to unravel genetic mechanisms of waterlogging tolerance beyond natural variation. A total of 2 977 genes with similar expression patterns and 17 genes with opposite expression patterns were identified in the transcription profiles of ZS9 and GH01. An additional 1 438 genes in ZS9 and 1 861 genes in GH01 showed strain specific regulation. Analysis of the overlapped genes between ZS9 and GH01 revealed that waterlogging tolerance is determined by ability to regulate genes with similar expression patterns. Moreover, differences in both gene expression profiles and abscisic acid(ABA) contents between the two varieties suggest that ABA may play some role in waterlogging tolerance. This study identifies a subset of candidate genes for further functional analysis.
基金Supported by The Basic Research Projects of Shenzhen R&D Funding in Science and Technology,No.JCYJ20130402113802233 and No.JC201005260209A
文摘AIM:To determine the effect of different Roux-en-Y gastric bypass procedures in gastric carcinoma patients with type 2 diabetes mellitus.METHODS:A retrospective analysis of the clinical data of 54 patients with gastric cancer and type 2 diabetes mellitus treated in the Department of General Surgery from January 2006 to June 2013 was conducted.The patients underwent gastrectomy using different Rouxen-Y gastric bypass procedures(traditional,n=26;modified,n=28).Fasting plasma glucose(FPG),two hour postprandial blood glucose(2 h PBG)and hemoglobin A1c(Hb A1c)were analyzed before surgery(0 mo)and 1,3 and 6 mo after surgery.RESULTS:FPG and 2 h PBG levels were significantlydecreased 1 mo after surgery in the traditional Rouxen-Y gastric bypass group(FPG 7.5±1.3 vs 10.7±1.2,P<0.05)(2 h PBG 10.2±1.8 vs 13.8±3.2,P<0.05).FPG and 2 h PBG levels were significantly decreased after surgery in the modified Roux-en-Y gastric bypass group(FPG 6.9±1.2 vs 10.5±1.1,6.5±1.3 vs 10.5±1.1,6.4±1.2 vs 10.5±1.1,P<0.05)(2 h PBG9.9±2.2 vs 14.1±2.9,9.2±2.4 vs 14.1±2.9,8.9±2.6 vs 14.1±2.9,P<0.05).Compared with the levels before surgery,Hb A1c levels were significantly decreased 3 and 6 mo after surgery(7.2±1.1 vs 10.5±1.1,5.5±1.1 vs 10.5±1.1,P<0.05).Significant differences between the two groups regarding FPG,2 h PBG and Hb A1c concentration were observed 3 and 6mo after surgery(FPG 10.1±1.5 vs 6.5±1.3,10.3±1.4 vs 6.4±1.2,P<0.05)(2 h PBG 13.1±2.8 vs 9.2±2.4,13.6±3.1 vs 8.9±2.6,P<0.05)(Hb A1c 10.1±1.4 vs 7.2±1.1,10.5±1.3 vs 5.5±1.1,P<0.05).CONCLUSION:Modified Roux-en-Y gastric bypass can improve glucose metabolism in type 2 diabetic patients with gastric cancer.
文摘High nitrogen stainless steel with nitrogen content of 0.75%was welded by gas metal arc welding with Ar-N_(2)-O_(2)ternary shielding gas.The effect of the ternary shielding gas on the retention and improvement of nitrogen content in the weld was identified.Surfacing test was conducted first to compare the ability of O_(2)and CO_(2)in prompting nitrogen dissolution.The nitrogen content of the surfacing metal with O_(2)is slightly higher than CO_(2).And then AreN_(2)-O_(2)shielding gas was applied to weld high nitrogen stainless steel.After using N_(2)-containing shielding gas,the nitrogen content of the weld was improved by 0.1 wt%.As N_(2)continued to increase,the increment of nitrogen content was not obvious,but the ferrite decreased from the top to the bottom.When the proportion of N_(2)reached 20%,a full austenitic weld was obtained and the tensile strength was improved by 8.7%.Combined with the results of surfacing test and welding test,it is concluded that the main effect of N_(2)is to inhibit the escape of nitrogen and suppress the nitrogen diffusion from bottom to the top in the molten pool.
