China is experiencing accelerated urbanisation,with a large number of people moving from rural to urban areas[1].It has resulted in large losses in the net primary production(NPP),biodiversity and carbon stocks and an...China is experiencing accelerated urbanisation,with a large number of people moving from rural to urban areas[1].It has resulted in large losses in the net primary production(NPP),biodiversity and carbon stocks and an increase in environmental pollution and CO_(2)emissions[2–4].In 2015,196 countries signed the Paris Agreement and committed to setting long-term goals to jointly manage climate change and reduce their individual emissions,aiming to control the increase in global average temperature from the pre-industrial level to below 2℃and to curtail the temperature rise within 1.5℃till the end of the 21st century[5].China is bolstering its efforts to achieve the climate change mitigation goals and has announced a plan for achieving carbon neutrality by 2060[6].The carbon neutrality goal poses a challenge to the current policies promoting rapid urbanisation across China.展开更多
In order to solve the problems of GaN heteroepitaxy on sapphire substrate,some techniques were explored.Freestanding GaN substrates have been made by hydride vapor phase epitaxy(HVPE),laser lift-off(LLO),and chemical ...In order to solve the problems of GaN heteroepitaxy on sapphire substrate,some techniques were explored.Freestanding GaN substrates have been made by hydride vapor phase epitaxy(HVPE),laser lift-off(LLO),and chemical mechanical polishing techniques.Wafer bending and cracking in the HVPE growth were partly settled by pulsed flow modulation method.High-crystal quality was established for 1.2 mm thick GaN substrate by X-ray diffraction measurement,in which the full width of half maximum values were 72,110 arcsec for(102),(002)peaks.A novel micro-size patterned sapphire substrate(PSS)and a nano PSS were also fabricated.High-power vertical structure light emitting diodes(VSLEDs)have been developed by Au–Sn eutectic wafer bonding,homemade micro-area LLO,and light extraction structure preparation.The high-injection-level active region with low temperature GaN sandwiched layers was used for lowefficiency droop.The light output power of VSLED was achieved as 400 mW driven at 350 mA,and the dominant wavelength is about 460 nm.The structures and properties of strain modulated superlattices(SLs)and quantum wells as well as advanced simulation of carriers transport across the electron blocking layer were investigated in laser diodes.The hole concentration was achieved as high as1.6 9 1018cm-3in AlGaN/GaN SLs:Mg by inserting an AlN layer.High-quality AlGaN epilayers and structures were grown by MOCVD.Some device structures of UV LEDs and detectors were demonstrated.The emission wavelength of 262 nm UV LED has been successfully fabricated.At last,high-quality InN and InGaN materials for solar cell were grown by boundary-temperature-controlled epitaxy and growth-temperature-controlled epitaxy.Hall-effect measurement showed a recorded electron mobility of 3,280 cm2/(V s)and a residual electron concentration of 1.47 9 1017cm-3at 300 K.展开更多
The development of semiconductors is always accompanied by the progress in controllable doping techniques.Taking AlGaN-based ultraviolet(UV)emitters as an example,despite a peak wall-plug efficiency of 15.3%at the wav...The development of semiconductors is always accompanied by the progress in controllable doping techniques.Taking AlGaN-based ultraviolet(UV)emitters as an example,despite a peak wall-plug efficiency of 15.3%at the wavelength of 275 nm,there is still a huge gap in comparison with GaN-based visible light-emitting diodes(LEDs),mainly attributed to the inefficient doping of AlGaN with increase of the Al composition.First,p-doping of Al-rich AlGaN is a long-standing challenge and the low hole concentration seriously restricts the carrier injection efficiency.Although p-GaN cladding layers are widely adopted as a compromise,the high injection barrier of holes as well as the inevitable loss of light extraction cannot be neglected.While in terms of n-doping the main issue is the degradation of the electrical property when the Al composition exceeds 80%,resulting in a low electrical efficiency in sub-250 nm UV-LEDs.This review summarizes the recent advances and outlines the major challenges in the efficient doping of Al-rich AlGaN,meanwhile the corresponding approaches pursued to overcome the doping issues are discussed in detail.展开更多
Solving the doping asymmetry issue in wide gap semiconductors is a key dificulty and long-standing challenge for device applications.Here,a desorption-tailoring strategy is proposed to juggle the carrier concentration...Solving the doping asymmetry issue in wide gap semiconductors is a key dificulty and long-standing challenge for device applications.Here,a desorption-tailoring strategy is proposed to juggle the carrier concentration and transport.Specific to the p-doping issue in Al-rich AlGaN,self-assembled p-AlGaN superlattices with an average Al composition of over 50%are prepared by adopting this approach.The hole concentration as high as 8.1×10^(18)cm^(-3)is thus realized at room temperature,which is attributed to the signifcant reduction of effective Mg activation energy to 17.5 meV through modulating the activating path,as well as the highlighted Mg surface-incorporation by an intentional interruption for desorption.More importantly,benefting from the constant ultrathin barrier thickness of only three monolayers via this approach,vertical miniband transport of holes is verifed in the p-AlGaN superlattices,greatly satisfying the demand of hole injection in device application.280 nm deep-ultraviolet light emitting diodes are then fabricated as a demo with the desorption-tailored Al-rich p-AlGaN superlattices,which exhibit a great improvement of the carrier injection efficiency and light extraction efficiency,thus leading to a 55.7%increase of the light output power.This study provides a solution for p-type doping of Al-rich AlGaN,and also sheds light on solving the doping asymmetry issue in general for wide-gap semiconductors.展开更多
According to the data of banana transcriptome sequencing, an E3 ubiquitin-protein ligase gene was cloned by RT-PCR method using the cDNA sample of banana leaves. The complete ORF of E3 ubiquitin-protein ligase is 681 ...According to the data of banana transcriptome sequencing, an E3 ubiquitin-protein ligase gene was cloned by RT-PCR method using the cDNA sample of banana leaves. The complete ORF of E3 ubiquitin-protein ligase is 681 bp long and its encoded protein showed 100% sequence identity to homologue RING-H2 finger protein (XP_009407047.1) of Musa_acuminata. Bioinformatic analysis indicated that E3 ubiquitin-protein ligase contains the Ring finger domain in C terminus and eight cross-brace motifs are found in the domain. The target gene was digested by EcoR V and EcoR I, and was inserted into prokaryotic expression vector pET-32a of the same digestions to obtain the plasmid pET32a-E3 ubiquitin-protein ligase. The recombinant plasmid was introduced into Escherichia coli strain BL21 (DE3), and induced at 25°C with 0.4 mmol/L IPTG for 6 hours. The soluble fusion protein was expressed and high purity fusion protein was obtained by Ni<sup>2+</sup>-NTA agarose affinity chromatography purification. The fusion protein was injected into mice 3 times to prepare the antiserum. Western blot analysis showed a specific protein band was detected in total protein sample of banana leaves, but not for the samples of wild-type Nicotiana benthamiana (N.B.) and wild-type Arabidopsis thaliana (A.T.), implying the antiserum was specific to banana E3 ubiquitin-protein ligase.展开更多
Submarine groundwater discharge(SGD),which can be traced using naturally occurring radium isotopes,has been recognized as a significant nutrient source and land-ocean interaction passage for the coastal waters of the ...Submarine groundwater discharge(SGD),which can be traced using naturally occurring radium isotopes,has been recognized as a significant nutrient source and land-ocean interaction passage for the coastal waters of the Daya Bay,China.However,uncertainties in assessing SGD fluxes must still be discussed in detail.In this study,we attempted to utilize the Monte Carlo method to evaluate the uncertainties of radium-derived SGD flux in the northeast and entirety of the Daya Bay.The results show that the uncertainties of the SGD estimate in the northeast bay are very sensitive to variations in excess radium inventories as well as radium inputs from bottom sediments,while the uncertainties of the SGD estimate for the entire bay are strongly affected by fluctuations in radium inputs from bottom sediments and radium end-members of SGD.This study will help to distinguish the key factors controlling the accuracy of SGD estimates in similar coastal waters.展开更多
目的研究儿童肝移植术后停用免疫抑制的可行性,探究影响患儿免疫耐受的相关因素。方法收集2013年1月至2017年1月在天津市第一中心医院儿童器官移植科接受肝移植手术且术后进行免疫抑制剂撤除的14例患儿资料。其中,男8例,女6例;体质量指...目的研究儿童肝移植术后停用免疫抑制的可行性,探究影响患儿免疫耐受的相关因素。方法收集2013年1月至2017年1月在天津市第一中心医院儿童器官移植科接受肝移植手术且术后进行免疫抑制剂撤除的14例患儿资料。其中,男8例,女6例;体质量指数(body mass index,BMI)为(20.32±4.65)kg/m^(2);受者移植时患儿年龄范围为0.58~0.71岁,中位年龄为0.58岁;纳入研究时患儿年龄范围为2.65~4.52岁,中位年龄为3.75岁;移植术后至纳入研究时间间隔为(3.08±1.10)年。供者中,男6例,女8例,供者年龄为(22.84±13.93)岁。14例患儿的移植病因均为胆道闭锁,10例为活体肝移植,4例为尸体肝移植。参与撤除免疫抑制剂临床研究的患儿中,4例为移植后淋巴增殖性疾病(post transplant lymphoproliferative disorder,PTLD)而撤除免疫抑制剂。所有患儿移植术后进行免疫治疗,>6岁的患儿采用激素+他克莫司(tacrolimus,FK506)+吗替麦考酚酯三联用药方案,≤6岁的患儿采用激素+FK506二联用药方案。14例患儿中,10例按撤除方案撤除免疫抑制剂,4例PTLD患儿根据病理类型和临床症状单独进行免疫抑制减停治疗。所有患儿定期检测肝功能,并于纳入研究时、纳入研究1年和2年时进行程序性肝活检,采用苏木精-伊红(hematoxylin and eosin,HE)染色并通过Banff标准和Ishak评分系统评估患儿肝脏急性排斥反应和纤维化程度。结果14例患儿中5例成功停用免疫抑制剂,实现免疫耐受;9例患儿免疫不耐受,其中3例在随访过程中肝功能正常,程序性活检时肝脏病理结果考虑为排斥反应;其余6例在随访过程中出现肝功能异常,此6例患儿恢复免疫抑制治疗后,肝功能均恢复到正常水平。与免疫不耐受的患儿相比,免疫耐受的患儿在移植时年龄较小,移植时的中位年龄为0.58岁,范围为0.50~0.58岁,免疫不耐受的患儿移植时的中位年龄为0.67岁,范围为0.58~2.04岁,差异具有统计展开更多
基金supported by the National Natural Science Foundation of China(42201319,42001281,42201347 and 42001324)the Guangdong Basic and Applied Basic Research Foundation(2023A1515011946 and 2023A1515011216)+1 种基金the Open Funding Project of the Key Laboratory of Marine Environmental Survey Technology and Application,Ministry of Natural Resources(MESTA-2021-B003)Independent Research Project of Guangming Laboratory Project:Moonshot Carbon Credit Rating Driven by AI and Remote Sensing Big Data(23400002)。
文摘China is experiencing accelerated urbanisation,with a large number of people moving from rural to urban areas[1].It has resulted in large losses in the net primary production(NPP),biodiversity and carbon stocks and an increase in environmental pollution and CO_(2)emissions[2–4].In 2015,196 countries signed the Paris Agreement and committed to setting long-term goals to jointly manage climate change and reduce their individual emissions,aiming to control the increase in global average temperature from the pre-industrial level to below 2℃and to curtail the temperature rise within 1.5℃till the end of the 21st century[5].China is bolstering its efforts to achieve the climate change mitigation goals and has announced a plan for achieving carbon neutrality by 2060[6].The carbon neutrality goal poses a challenge to the current policies promoting rapid urbanisation across China.
基金supported by the National Key Basic R&D Project of China(TG2011CB301900 and TG2012CB619304)the project of National High Technology of China(2011AA03A103)+1 种基金the National Natural Science Foundation of China(61076012 and60876063)the Beijing Municipal Science & Technology Commission(D111100001711002)
文摘In order to solve the problems of GaN heteroepitaxy on sapphire substrate,some techniques were explored.Freestanding GaN substrates have been made by hydride vapor phase epitaxy(HVPE),laser lift-off(LLO),and chemical mechanical polishing techniques.Wafer bending and cracking in the HVPE growth were partly settled by pulsed flow modulation method.High-crystal quality was established for 1.2 mm thick GaN substrate by X-ray diffraction measurement,in which the full width of half maximum values were 72,110 arcsec for(102),(002)peaks.A novel micro-size patterned sapphire substrate(PSS)and a nano PSS were also fabricated.High-power vertical structure light emitting diodes(VSLEDs)have been developed by Au–Sn eutectic wafer bonding,homemade micro-area LLO,and light extraction structure preparation.The high-injection-level active region with low temperature GaN sandwiched layers was used for lowefficiency droop.The light output power of VSLED was achieved as 400 mW driven at 350 mA,and the dominant wavelength is about 460 nm.The structures and properties of strain modulated superlattices(SLs)and quantum wells as well as advanced simulation of carriers transport across the electron blocking layer were investigated in laser diodes.The hole concentration was achieved as high as1.6 9 1018cm-3in AlGaN/GaN SLs:Mg by inserting an AlN layer.High-quality AlGaN epilayers and structures were grown by MOCVD.Some device structures of UV LEDs and detectors were demonstrated.The emission wavelength of 262 nm UV LED has been successfully fabricated.At last,high-quality InN and InGaN materials for solar cell were grown by boundary-temperature-controlled epitaxy and growth-temperature-controlled epitaxy.Hall-effect measurement showed a recorded electron mobility of 3,280 cm2/(V s)and a residual electron concentration of 1.47 9 1017cm-3at 300 K.
基金This work was supported by the National Key Research and Development Program of China(No.2022YFB3605100)the National Natural Science Foundation of China(Nos.62234001,61927806,61974002,62135013,and 62075081)+1 种基金the Key-Area Research and Development Program of Guangdong Province(No.2020B010172001)the Major Scientific and Technological Innovation Project(MSTIP)of Shandong Province(No.2019JZZY010209).
文摘The development of semiconductors is always accompanied by the progress in controllable doping techniques.Taking AlGaN-based ultraviolet(UV)emitters as an example,despite a peak wall-plug efficiency of 15.3%at the wavelength of 275 nm,there is still a huge gap in comparison with GaN-based visible light-emitting diodes(LEDs),mainly attributed to the inefficient doping of AlGaN with increase of the Al composition.First,p-doping of Al-rich AlGaN is a long-standing challenge and the low hole concentration seriously restricts the carrier injection efficiency.Although p-GaN cladding layers are widely adopted as a compromise,the high injection barrier of holes as well as the inevitable loss of light extraction cannot be neglected.While in terms of n-doping the main issue is the degradation of the electrical property when the Al composition exceeds 80%,resulting in a low electrical efficiency in sub-250 nm UV-LEDs.This review summarizes the recent advances and outlines the major challenges in the efficient doping of Al-rich AlGaN,meanwhile the corresponding approaches pursued to overcome the doping issues are discussed in detail.
基金the National Key Research and Development Program of China(Nos.2016YFB0400101,and 2018YFE0125700)the National Natural Science Foundation of China(Nos.61974002,62075081,and 61927806)+1 种基金the Key-Area Research and Development Program of Guangdong Province(No.2020B010172001)the Major Scientific and Technological Innovation Project(MSTIP)of Shandong Province(No.2019JZZY010209).
文摘Solving the doping asymmetry issue in wide gap semiconductors is a key dificulty and long-standing challenge for device applications.Here,a desorption-tailoring strategy is proposed to juggle the carrier concentration and transport.Specific to the p-doping issue in Al-rich AlGaN,self-assembled p-AlGaN superlattices with an average Al composition of over 50%are prepared by adopting this approach.The hole concentration as high as 8.1×10^(18)cm^(-3)is thus realized at room temperature,which is attributed to the signifcant reduction of effective Mg activation energy to 17.5 meV through modulating the activating path,as well as the highlighted Mg surface-incorporation by an intentional interruption for desorption.More importantly,benefting from the constant ultrathin barrier thickness of only three monolayers via this approach,vertical miniband transport of holes is verifed in the p-AlGaN superlattices,greatly satisfying the demand of hole injection in device application.280 nm deep-ultraviolet light emitting diodes are then fabricated as a demo with the desorption-tailored Al-rich p-AlGaN superlattices,which exhibit a great improvement of the carrier injection efficiency and light extraction efficiency,thus leading to a 55.7%increase of the light output power.This study provides a solution for p-type doping of Al-rich AlGaN,and also sheds light on solving the doping asymmetry issue in general for wide-gap semiconductors.
文摘According to the data of banana transcriptome sequencing, an E3 ubiquitin-protein ligase gene was cloned by RT-PCR method using the cDNA sample of banana leaves. The complete ORF of E3 ubiquitin-protein ligase is 681 bp long and its encoded protein showed 100% sequence identity to homologue RING-H2 finger protein (XP_009407047.1) of Musa_acuminata. Bioinformatic analysis indicated that E3 ubiquitin-protein ligase contains the Ring finger domain in C terminus and eight cross-brace motifs are found in the domain. The target gene was digested by EcoR V and EcoR I, and was inserted into prokaryotic expression vector pET-32a of the same digestions to obtain the plasmid pET32a-E3 ubiquitin-protein ligase. The recombinant plasmid was introduced into Escherichia coli strain BL21 (DE3), and induced at 25°C with 0.4 mmol/L IPTG for 6 hours. The soluble fusion protein was expressed and high purity fusion protein was obtained by Ni<sup>2+</sup>-NTA agarose affinity chromatography purification. The fusion protein was injected into mice 3 times to prepare the antiserum. Western blot analysis showed a specific protein band was detected in total protein sample of banana leaves, but not for the samples of wild-type Nicotiana benthamiana (N.B.) and wild-type Arabidopsis thaliana (A.T.), implying the antiserum was specific to banana E3 ubiquitin-protein ligase.
基金The Project of Key Laboratory of Marine Environmental Survey Technology and Application,Ministry of Natural Resources under contract No.MESTA-2021-D006the China Ocean Development Foundation under contract No.CODF-002-ZX-2021+5 种基金the Science and Technology Plan Projects of Guangdong Province under contract No.2021B1212050025the Director’s Foundation of South China Sea Bureau of Ministry of Natural Resources under contract No.230201the Research Fund Program of Guangdong Provincial Key Laboratory of Applied Marine Biology under contract No.LAMB20221007the Natural Science Foundation of Guangdong Province of China under contract No.2017A030310592the Key Program of Bureau Director of State Oceanic Administration under contract No.180104the Open Project of State Key Laboratory of Tropical Oceanography,South China Sea Institute of Oceanology,Chinese Academy of Sciences under contract No.LTO1709.
文摘Submarine groundwater discharge(SGD),which can be traced using naturally occurring radium isotopes,has been recognized as a significant nutrient source and land-ocean interaction passage for the coastal waters of the Daya Bay,China.However,uncertainties in assessing SGD fluxes must still be discussed in detail.In this study,we attempted to utilize the Monte Carlo method to evaluate the uncertainties of radium-derived SGD flux in the northeast and entirety of the Daya Bay.The results show that the uncertainties of the SGD estimate in the northeast bay are very sensitive to variations in excess radium inventories as well as radium inputs from bottom sediments,while the uncertainties of the SGD estimate for the entire bay are strongly affected by fluctuations in radium inputs from bottom sediments and radium end-members of SGD.This study will help to distinguish the key factors controlling the accuracy of SGD estimates in similar coastal waters.
文摘目的研究儿童肝移植术后停用免疫抑制的可行性,探究影响患儿免疫耐受的相关因素。方法收集2013年1月至2017年1月在天津市第一中心医院儿童器官移植科接受肝移植手术且术后进行免疫抑制剂撤除的14例患儿资料。其中,男8例,女6例;体质量指数(body mass index,BMI)为(20.32±4.65)kg/m^(2);受者移植时患儿年龄范围为0.58~0.71岁,中位年龄为0.58岁;纳入研究时患儿年龄范围为2.65~4.52岁,中位年龄为3.75岁;移植术后至纳入研究时间间隔为(3.08±1.10)年。供者中,男6例,女8例,供者年龄为(22.84±13.93)岁。14例患儿的移植病因均为胆道闭锁,10例为活体肝移植,4例为尸体肝移植。参与撤除免疫抑制剂临床研究的患儿中,4例为移植后淋巴增殖性疾病(post transplant lymphoproliferative disorder,PTLD)而撤除免疫抑制剂。所有患儿移植术后进行免疫治疗,>6岁的患儿采用激素+他克莫司(tacrolimus,FK506)+吗替麦考酚酯三联用药方案,≤6岁的患儿采用激素+FK506二联用药方案。14例患儿中,10例按撤除方案撤除免疫抑制剂,4例PTLD患儿根据病理类型和临床症状单独进行免疫抑制减停治疗。所有患儿定期检测肝功能,并于纳入研究时、纳入研究1年和2年时进行程序性肝活检,采用苏木精-伊红(hematoxylin and eosin,HE)染色并通过Banff标准和Ishak评分系统评估患儿肝脏急性排斥反应和纤维化程度。结果14例患儿中5例成功停用免疫抑制剂,实现免疫耐受;9例患儿免疫不耐受,其中3例在随访过程中肝功能正常,程序性活检时肝脏病理结果考虑为排斥反应;其余6例在随访过程中出现肝功能异常,此6例患儿恢复免疫抑制治疗后,肝功能均恢复到正常水平。与免疫不耐受的患儿相比,免疫耐受的患儿在移植时年龄较小,移植时的中位年龄为0.58岁,范围为0.50~0.58岁,免疫不耐受的患儿移植时的中位年龄为0.67岁,范围为0.58~2.04岁,差异具有统计
