AlGaN-based ultraviolet light-emitting diodes(UV-LEDs) have attracted considerable interest due to their wide range of application fields. However, they are still suffering from low light out power and unsatisfactory ...AlGaN-based ultraviolet light-emitting diodes(UV-LEDs) have attracted considerable interest due to their wide range of application fields. However, they are still suffering from low light out power and unsatisfactory quantum efficiency.The utilization of polarization-doped technique by grading the Al content in p-type layer has demonstrated its effectiveness in improving LED performances by providing sufficiently high hole concentration. However, too large degree of grading through monotonously increasing the Al content causes strains in active regions, which constrains application of this technique, especially for short wavelength UV-LEDs. To further improve 340-nm UV-LED performances, segmentally graded Al content p-Al_xGa_(1-x)N has been proposed and investigated in this work. Numerical results show that the internal quantum efficiency and output power of proposed structures are improved due to the enhanced carrier concentrations and radiative recombination rate in multiple quantum wells, compared to those of the conventional UV-LED with a stationary Al content AlGaN electron blocking layer. Moreover, by adopting the segmentally graded p-Al_xGa_(1-x)N, band bending within the last quantum barrier/p-type layer interface is effectively eliminated.展开更多
Silicon carbide nanotubes(SiCNTs) have broad application prospects in the field of micro-nanodevices due to their excellent physical properties. Based on first-principles, the difference between optical properties of ...Silicon carbide nanotubes(SiCNTs) have broad application prospects in the field of micro-nanodevices due to their excellent physical properties. Based on first-principles, the difference between optical properties of SiCNTs where C atom or Si atom is replaced by group-V element is studied. The results show that the optical absorptions of SiCNTs doped by different elements are significantly different in the band of 600 nm–1500 nm. The differences in photoconductivity, caused by different doping elements, are reflected mainly in the band above 620 nm, the difference in dielectric function and refractive index of SiCNTs are reflected mainly in the band above 500 nm. Further analysis shows that SiCNTs doped with different elements change their band structures, resulting in the differences among their optical properties. The calculation of formation energy shows that SiCNTs are more stable when group-V element replaces Si atom, except N atom. These research results will be beneficial to the applications of SiC nanomaterials in optoelectronic devices and provide a theoretical basis for selecting the SiCNTs' dopants.展开更多
Organic active units often transform into radical intermediates during the redox processes but exhibit poor cycling stability due to the uncontrollable redox of the radicals. Herein, we report a facile and efficient s...Organic active units often transform into radical intermediates during the redox processes but exhibit poor cycling stability due to the uncontrollable redox of the radicals. Herein, we report a facile and efficient strategy to modulate the molecular orbital energies, charge transport capacities, and spin electron densities of the active units in covalent organic frameworks(COFs) via regulating the conjugated unit size to optimize the redox activity and stability of the organic radicals. COFs based on different imide conjugated units exhibit tunable discharge voltages, rate performance and cycling stabilities. Detailed characterizations and theoretical calculation reveal that imide radicals are the important active intermediates during the redox processes of these COFs. Specifically, increasing the size of the imide conjugated units could effectively delocalize the radical electrons and improve the stability of the COFs electrodes. This study offers a very effective strategy to modulate the redox chemistry of organic materials for electrochemical energy storage.展开更多
Objective:To study the correlation of OPG/RANKL expression in gingival crevicular fluid with inflammatory factors, free radical generation and bone metabolism in patients with diabetes mellitus complicated by periodon...Objective:To study the correlation of OPG/RANKL expression in gingival crevicular fluid with inflammatory factors, free radical generation and bone metabolism in patients with diabetes mellitus complicated by periodontitis.Methods:Patients with diabetes mellitus complicated by periodontitis who were treated in Xi'an No. 4 Hospital between March 2015 and May 2017 were selected as the periodontitis group for the research, and healthy volunteers who underwent periodontal examination during the same period were selected as the control group. The gingival crevicular fluid was collected to determine the expression of OPG/RANKL, the contents of inflammatory factors and bone metabolism molecules as well as the generation of free radicals.Results: OPG protein expression, OPG/RANKL expression ratio as well as ICTP and Runx2 contents in gingival crevicular fluid of periodontitis group were significantly lower than those of control group whereas RANKL protein expression, TNF-α, IL-1β, IL-17, HMGB1, DKK1 and MMP1 contents as well as ROS, MDA and 8-OHdG generation were significantly higher than those of control group;OPG/RANKL expression ratio in gingival crevicular fluid of periodontitis group was negatively correlated with TNF- , IL-1β, IL-17, HMGB1, DKK1 and MMP1 contents as well as ROS, MDA and 8-OHdG generation, and positively correlated with ICTP and Runx2 contents.Conclusion: The excessive activation of inflammation and oxidative stress in periodontal tissue of patients with diabetes mellitus complicated by periodontitis can cause OPG/RANKL expression disorder and then lead to bone metabolism disorder.展开更多
Developing precise extracellular vesicles(EVs)labelling techniques with minimal disturbance is of great importance to the follow-up EVs detection and analysis.However,currently available methods such as using probes t...Developing precise extracellular vesicles(EVs)labelling techniques with minimal disturbance is of great importance to the follow-up EVs detection and analysis.However,currently available methods such as using probes to conjugate phospholipids or membrane proteins have certain limitations due to EV steric hindrance,dye aggregation,etc.Here,we present a microfluidic platform to enhance EVs’labelling efficiency and improve their detection.This platform provides excellent sample throughput and high-efficiency EV labelling at lower label concentrations with an optimized flowing rate.Flow cytometry analysis(FCM)and cellular uptake results show that EV labelling by utilizing this platform possesses the merits of a higher labelling efficiency with 64.1%relative improvement than conventional co-incubation method and a lower background noise.Moreover,this technique maintains EVs’size,morphology and biological activities.After the recipient cells uptake the EVs treated by the microfluidic platform,the spatial and temporal distribution of EVs in the cells are clearly observed.These results demonstrate that our method holds great potential in efficient labelling of EVs,which is essential to subsequent EV quantification and analysis.展开更多
Single-atom catalysts(SACs)reveal great potential for application in catalysis due to their fully exposed active sites.In general,single atoms(SAs)and the coordination substrates need to have strong interactions or ch...Single-atom catalysts(SACs)reveal great potential for application in catalysis due to their fully exposed active sites.In general,single atoms(SAs)and the coordination substrates need to have strong interactions or charge transfer to ensure the atomic dispersion,which requires the selection of a suitable substrate to stabilize the target atoms.Recent studies have demonstrated that amorphous materials with abundant defects and coordinatively unsaturated sites can be used as substrates for more efficient capturing SAs,further enhancing the catalytic performance.In this review,we discuss recent research progress of SAs loaded on amorphous substrates for enhanced catalytic activity.Firstly,we summarize the commonly used amorphous substrates for stabilizing SAs.Subsequently,we present several advanced applications of amorphous SACs in the field of catalysis,including electrocatalysis and photocatalysis.And then,we also clarify the synergistic mechanism between SAs and amorphous substrate on catalytic process.Finally,we summarize the challenges with our personal views and provide a critical outlook on how amorphous SACs continue to evolve.展开更多
Interactions between diet and the intestinal microbiome play an important role in human health and disease development.It is well known that such interactions,whether direct or indirect,trigger a series of metabolic r...Interactions between diet and the intestinal microbiome play an important role in human health and disease development.It is well known that such interactions,whether direct or indirect,trigger a series of metabolic reactions in the body.Evidence suggests that intestinal stem cells(ISCs),which are phenotypic precursors of various intestinal epithelial cells,play a significant role in the regulation of intestinal barrier function and homeostasis.The advent and evolution of intestinal organoid culture techniques have presented a key opportunity to study the association between the intestinal microenvironment and ISCs.As a result,the effects exerted by dietary factors,intestinal microbiomes,and their metabolites on the metabolic regulation of ISCs and the potential mechanisms underlying such effects are being gradually revealed.This review summarises the effects of different dietary patterns on the behaviour and functioning of ISCs and focuses on the crosstalk between intestinal microbiota,related metabolites,and ISCs,with the aim of fully understanding the relationship between these three factors and providing further insights into the complex mechanisms associated with ISCs in the human body.Gaining an understanding of these mechanisms may lead to the development of novel dietary interventions or drugs conducive to intestinal health.展开更多
铜基氧化物表面的氧化物种可以增强CO_(2)吸附,降低含氧中间体的结合能,从而提高电还原CO_(2)的一步还原产物的产率.鉴于此,在还原过程中,Cu_(2)O上的残留氧通过Sn^(2+)稳定,并且残留氧的保留通过原位拉曼光谱(Cu–O_(ads))得到了证实....铜基氧化物表面的氧化物种可以增强CO_(2)吸附,降低含氧中间体的结合能,从而提高电还原CO_(2)的一步还原产物的产率.鉴于此,在还原过程中,Cu_(2)O上的残留氧通过Sn^(2+)稳定,并且残留氧的保留通过原位拉曼光谱(Cu–O_(ads))得到了证实.同时,原位拉曼光谱和密度泛函理论计算结果证明,由于残留氧的存在,一氧化碳中间体在SnO/Cu_(2)O催化剂的吸附能比Cu_(2)O催化剂明显降低.这使得其在-0.8 V (相对于可逆氢电极)的电位下获得高达97.5%的法拉第效率.铜基氧化物催化剂的氧稳定策略对设计高性能电还原CO_(2)催化剂具有指导意义.展开更多
Monolayer and bilayer graphene sheets have been produced by a solvothermal-assisted exfoliation process in a highly polar organic solvent,acetonitrile,using expanded graphite(EG)as the starting material.It is proposed...Monolayer and bilayer graphene sheets have been produced by a solvothermal-assisted exfoliation process in a highly polar organic solvent,acetonitrile,using expanded graphite(EG)as the starting material.It is proposed that the dipole-induced dipole interactions between graphene and acetonitrile facilitate the exfoliation and dispersion of graphene.The facile and effective solvothermal-assisted exfoliation process raises the low yield of graphene reported in previous syntheses to 10 wt%12 wt%.By means of centrifugation at 2000 rpm for 90 min,monolayer and bilayer graphene were separated effectively without the need to add a stabilizer or modifi er.Electron diffraction and Raman spectroscopy indicate that the resulting graphene sheets are high quality products without any signifi cant structural defects.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61874161 and 11474105)the Science and Technology Program of Guangdong Province,China(Grant Nos.2017B010127001 and 2015B010105011)+4 种基金the Education Department Project of Guangdong Province,China(Grant No.2017KZDXM022)the Science and Technology Project of Guangzhou City,China(Grant No.201607010246)the Program for Changjiang Scholars and Innovative Research Team in Universities of China(Grant No.IRT13064)the Science and Technology Project of Shenzhen City,China(Grant No.GJHZ20180416164721073)the Science and Technology Planning of Guangdong Province,China(Grant No.2015B010112002)
文摘AlGaN-based ultraviolet light-emitting diodes(UV-LEDs) have attracted considerable interest due to their wide range of application fields. However, they are still suffering from low light out power and unsatisfactory quantum efficiency.The utilization of polarization-doped technique by grading the Al content in p-type layer has demonstrated its effectiveness in improving LED performances by providing sufficiently high hole concentration. However, too large degree of grading through monotonously increasing the Al content causes strains in active regions, which constrains application of this technique, especially for short wavelength UV-LEDs. To further improve 340-nm UV-LED performances, segmentally graded Al content p-Al_xGa_(1-x)N has been proposed and investigated in this work. Numerical results show that the internal quantum efficiency and output power of proposed structures are improved due to the enhanced carrier concentrations and radiative recombination rate in multiple quantum wells, compared to those of the conventional UV-LED with a stationary Al content AlGaN electron blocking layer. Moreover, by adopting the segmentally graded p-Al_xGa_(1-x)N, band bending within the last quantum barrier/p-type layer interface is effectively eliminated.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11574261 and 51132002)the Natural Science Foundation of Hebei Province,China (Grant No. A2015203261)。
文摘Silicon carbide nanotubes(SiCNTs) have broad application prospects in the field of micro-nanodevices due to their excellent physical properties. Based on first-principles, the difference between optical properties of SiCNTs where C atom or Si atom is replaced by group-V element is studied. The results show that the optical absorptions of SiCNTs doped by different elements are significantly different in the band of 600 nm–1500 nm. The differences in photoconductivity, caused by different doping elements, are reflected mainly in the band above 620 nm, the difference in dielectric function and refractive index of SiCNTs are reflected mainly in the band above 500 nm. Further analysis shows that SiCNTs doped with different elements change their band structures, resulting in the differences among their optical properties. The calculation of formation energy shows that SiCNTs are more stable when group-V element replaces Si atom, except N atom. These research results will be beneficial to the applications of SiC nanomaterials in optoelectronic devices and provide a theoretical basis for selecting the SiCNTs' dopants.
基金supports from the Basic Research Project of the Science and Technology Innovation Commission of Shenzhen (No. JCYJ20200109141640095)the Shenzhen Key Laboratory of Interfacial Science and Engineering of Materials (No. ZDSYS20200421111401738)+3 种基金the Leading Talents of Guangdong Province Program (No. 2016LJ06C536)the GuangdongHong Kong-Macao Joint Laboratory (No. 2019B121205001)the National Natural Science Foundation of China (No. 21875097)the support from the Hong Kong Research Grants Council (Project number CityU 11218420)。
文摘Organic active units often transform into radical intermediates during the redox processes but exhibit poor cycling stability due to the uncontrollable redox of the radicals. Herein, we report a facile and efficient strategy to modulate the molecular orbital energies, charge transport capacities, and spin electron densities of the active units in covalent organic frameworks(COFs) via regulating the conjugated unit size to optimize the redox activity and stability of the organic radicals. COFs based on different imide conjugated units exhibit tunable discharge voltages, rate performance and cycling stabilities. Detailed characterizations and theoretical calculation reveal that imide radicals are the important active intermediates during the redox processes of these COFs. Specifically, increasing the size of the imide conjugated units could effectively delocalize the radical electrons and improve the stability of the COFs electrodes. This study offers a very effective strategy to modulate the redox chemistry of organic materials for electrochemical energy storage.
文摘Objective:To study the correlation of OPG/RANKL expression in gingival crevicular fluid with inflammatory factors, free radical generation and bone metabolism in patients with diabetes mellitus complicated by periodontitis.Methods:Patients with diabetes mellitus complicated by periodontitis who were treated in Xi'an No. 4 Hospital between March 2015 and May 2017 were selected as the periodontitis group for the research, and healthy volunteers who underwent periodontal examination during the same period were selected as the control group. The gingival crevicular fluid was collected to determine the expression of OPG/RANKL, the contents of inflammatory factors and bone metabolism molecules as well as the generation of free radicals.Results: OPG protein expression, OPG/RANKL expression ratio as well as ICTP and Runx2 contents in gingival crevicular fluid of periodontitis group were significantly lower than those of control group whereas RANKL protein expression, TNF-α, IL-1β, IL-17, HMGB1, DKK1 and MMP1 contents as well as ROS, MDA and 8-OHdG generation were significantly higher than those of control group;OPG/RANKL expression ratio in gingival crevicular fluid of periodontitis group was negatively correlated with TNF- , IL-1β, IL-17, HMGB1, DKK1 and MMP1 contents as well as ROS, MDA and 8-OHdG generation, and positively correlated with ICTP and Runx2 contents.Conclusion: The excessive activation of inflammation and oxidative stress in periodontal tissue of patients with diabetes mellitus complicated by periodontitis can cause OPG/RANKL expression disorder and then lead to bone metabolism disorder.
基金supported by the National Natural Science Foundation of China(Nos.62074155,62204253 and 62205366)Guangdong Program(No.2016ZT06D631)+1 种基金Guangdong Basic and Applied Basic Research Foundation(Nos.2020A1515110938 and 2020A1515110142)Shenzhen Science and Technology Innovation Committee(Nos.KCXFZ202002011008124 and JCYJ20210324101405016)。
文摘Developing precise extracellular vesicles(EVs)labelling techniques with minimal disturbance is of great importance to the follow-up EVs detection and analysis.However,currently available methods such as using probes to conjugate phospholipids or membrane proteins have certain limitations due to EV steric hindrance,dye aggregation,etc.Here,we present a microfluidic platform to enhance EVs’labelling efficiency and improve their detection.This platform provides excellent sample throughput and high-efficiency EV labelling at lower label concentrations with an optimized flowing rate.Flow cytometry analysis(FCM)and cellular uptake results show that EV labelling by utilizing this platform possesses the merits of a higher labelling efficiency with 64.1%relative improvement than conventional co-incubation method and a lower background noise.Moreover,this technique maintains EVs’size,morphology and biological activities.After the recipient cells uptake the EVs treated by the microfluidic platform,the spatial and temporal distribution of EVs in the cells are clearly observed.These results demonstrate that our method holds great potential in efficient labelling of EVs,which is essential to subsequent EV quantification and analysis.
基金supported by the National Natural Science Foundation of China(No.22305051)the National Key Research and Development Project(No.2023YFF0611100)+3 种基金the Fundamental Research Funds for the Central Universities(No.265QZ2022002)the Natural Science Foundation of Henan Province(No.232300421104)the Funding of GRIMAT Engineering Institute(No.5222201)the National Key R&D Program of China(No.2021YFB4001301-2)。
文摘Single-atom catalysts(SACs)reveal great potential for application in catalysis due to their fully exposed active sites.In general,single atoms(SAs)and the coordination substrates need to have strong interactions or charge transfer to ensure the atomic dispersion,which requires the selection of a suitable substrate to stabilize the target atoms.Recent studies have demonstrated that amorphous materials with abundant defects and coordinatively unsaturated sites can be used as substrates for more efficient capturing SAs,further enhancing the catalytic performance.In this review,we discuss recent research progress of SAs loaded on amorphous substrates for enhanced catalytic activity.Firstly,we summarize the commonly used amorphous substrates for stabilizing SAs.Subsequently,we present several advanced applications of amorphous SACs in the field of catalysis,including electrocatalysis and photocatalysis.And then,we also clarify the synergistic mechanism between SAs and amorphous substrate on catalytic process.Finally,we summarize the challenges with our personal views and provide a critical outlook on how amorphous SACs continue to evolve.
基金supported by the National Natural Science Foundation of China(81973837)Scientific and technological innovation project of China Academy of Chinese Medical Sciences(CI2021A016)National Key projects for international cooperation on science,technology and innovation(2021YFE0201100).
文摘Interactions between diet and the intestinal microbiome play an important role in human health and disease development.It is well known that such interactions,whether direct or indirect,trigger a series of metabolic reactions in the body.Evidence suggests that intestinal stem cells(ISCs),which are phenotypic precursors of various intestinal epithelial cells,play a significant role in the regulation of intestinal barrier function and homeostasis.The advent and evolution of intestinal organoid culture techniques have presented a key opportunity to study the association between the intestinal microenvironment and ISCs.As a result,the effects exerted by dietary factors,intestinal microbiomes,and their metabolites on the metabolic regulation of ISCs and the potential mechanisms underlying such effects are being gradually revealed.This review summarises the effects of different dietary patterns on the behaviour and functioning of ISCs and focuses on the crosstalk between intestinal microbiota,related metabolites,and ISCs,with the aim of fully understanding the relationship between these three factors and providing further insights into the complex mechanisms associated with ISCs in the human body.Gaining an understanding of these mechanisms may lead to the development of novel dietary interventions or drugs conducive to intestinal health.
基金supported by Shenzhen Science and Technology Foundation of Nanshan (K20799112)the Basic Research Project of the Science and Technology Innovation Commission of Shenzhen (JCYJ20200109141640095)+4 种基金the National Natural Science Foundation of China (21875097)Shenzhen Key Laboratory of Interfacial Science and Engineering of Materials (ZDSYS20200421111401738)supported by the National Supercomputer Center in Guangzhouthe National Supercomputing Center in Shenzhen (Shenzhen Cloud Computing Center)the Center for Computational Science and Engineering at SUSTech。
文摘铜基氧化物表面的氧化物种可以增强CO_(2)吸附,降低含氧中间体的结合能,从而提高电还原CO_(2)的一步还原产物的产率.鉴于此,在还原过程中,Cu_(2)O上的残留氧通过Sn^(2+)稳定,并且残留氧的保留通过原位拉曼光谱(Cu–O_(ads))得到了证实.同时,原位拉曼光谱和密度泛函理论计算结果证明,由于残留氧的存在,一氧化碳中间体在SnO/Cu_(2)O催化剂的吸附能比Cu_(2)O催化剂明显降低.这使得其在-0.8 V (相对于可逆氢电极)的电位下获得高达97.5%的法拉第效率.铜基氧化物催化剂的氧稳定策略对设计高性能电还原CO_(2)催化剂具有指导意义.
基金by Beijing New Star Project of Science and Technology(2008B02)the Scientifi c Research Foundation for Returned Scholars from the Ministry of Education of China,the National Basic Research Program(2010CB934600)of China,Ministry of Science and Technology China and Start-up Fund of Distinguished Young Scholars at Peking University.Dr.W Qian acknowledges the postdoctoral fellowship supported by the National Nature Science Foundation of China.
文摘Monolayer and bilayer graphene sheets have been produced by a solvothermal-assisted exfoliation process in a highly polar organic solvent,acetonitrile,using expanded graphite(EG)as the starting material.It is proposed that the dipole-induced dipole interactions between graphene and acetonitrile facilitate the exfoliation and dispersion of graphene.The facile and effective solvothermal-assisted exfoliation process raises the low yield of graphene reported in previous syntheses to 10 wt%12 wt%.By means of centrifugation at 2000 rpm for 90 min,monolayer and bilayer graphene were separated effectively without the need to add a stabilizer or modifi er.Electron diffraction and Raman spectroscopy indicate that the resulting graphene sheets are high quality products without any signifi cant structural defects.
