Molybdenum oxide(MoO_(3)), with superior features of multi-electrochemical states, high theoretical capacitance, and low cost, is a desirable supercapacitor electrode material but suffers from low conductivity and ins...Molybdenum oxide(MoO_(3)), with superior features of multi-electrochemical states, high theoretical capacitance, and low cost, is a desirable supercapacitor electrode material but suffers from low conductivity and insufficient active sites. The MoO_(3) capacitance can be largely amplified by introducing oxygen(O) vacancies, but the mechanisms at the atomic scale are still ambiguous.Herein, O vacancies are created at the O2 and O3 sites in the MoO_(3) nanobelts by carbonization to maximize the supercapacitance in the MoO_(2.39). The supercapacitive storage is mainly ascribed to the proton adsorption at the O1 sites to create Mo–OH, leading to an expansion of the interlayer spacing along the lattice B-axis. Roughly 98% of the initial supercapacitance is retained after 1000 cycles,due to the reversible change in the interlayer spacing. Our results provide an insight into the oxygen deficiency-related mechanisms of the supercapacitive performance at the atomic scale and devise a facile method to enhance the supercapacitance for energy storage and conversion.展开更多
The anomalous hysteresis in a perovskite solar cell induced by an asymmetric field is confirmed by a capacitance–voltage measurement. By applying several cycles of alternating reverse and forward scans, this hysteres...The anomalous hysteresis in a perovskite solar cell induced by an asymmetric field is confirmed by a capacitance–voltage measurement. By applying several cycles of alternating reverse and forward scans, this hysteresis phenomenon is obviously alleviated, resulting in a hysteresis-less state in the perovskite solar cell. Meanwhile, the open-circuit voltage and power conversion efficiency of the perovskite solar cell are enhanced by 55.74% and 61.30%, respectively, while the current density and fill factor keep almost invariable. The operation of alleviating hysteresis is essential for further research and is likely to bring in performance gains.展开更多
Large-scale deployment of Internet of Things (IoT),a revolutionary innovation for a better world,is hampered by the limitation of energy self-sufficiency.Constructing transition metal nitride (TMN)-based micro-superca...Large-scale deployment of Internet of Things (IoT),a revolutionary innovation for a better world,is hampered by the limitation of energy self-sufficiency.Constructing transition metal nitride (TMN)-based micro-supercapacitors is a possible solution by taking advantage of the high conductivity,large specific capacitance,and large tap density of the materials.However,the pseudocapacitive storage mechanism of TMNs is still unclear consequently impeding the design of microdevices.Herein,the functions and mechanism of TMNs with different metal oxynitride (TMNO_(x)) concentrations in pseudocapacitive electrodes are investigated systematically by in situ Raman scattering,ex situ X-ray photoelectron spectroscopy,as well as ion isolation and substitution cyclic voltammetry.It is found that the specific capacitances of TMNs depend on the TMNO_(x) concentrations and the N–M–O site is responsible for the large pseudocapacitance via the Faradic reaction between TMNO_(x) and OH^(-).Our study elucidates the mechanism pertaining to pseudocapacitive charge storage of TMNs and provides insights into the design and optimization of TMNO_(x) as well as other electrode materials for pseudocapacitors.展开更多
Objective:To determine the serum inflammatory cytokines and oxidative stress parameters of diabetic retinopathy (DR) patients to explore their possible role in the DR.Methods: 116 cases of type 2 diabetic patients wer...Objective:To determine the serum inflammatory cytokines and oxidative stress parameters of diabetic retinopathy (DR) patients to explore their possible role in the DR.Methods: 116 cases of type 2 diabetic patients were selected from June 2015 to June 2016 in our hospital as research subjects, divided into diabetic Diabetes without retinopathy (NDR group,n = 63) and diabetic with retinopathy patients (DR group,n = 53). And 60 cases of healthy check-ups of the same period in our hospital medical center were selected as normal control group (NC). The VEGF, IL-6, TNF-α , MDA and SOD levels of three groups of patients were detected. Results:The IL-6 levels of NC group, NDR group and DR group were increased gradually, and the difference was statistically significant (P<0.05). The TNF-α levels of NC group, NDR group and DR group were increased gradually, and the difference was statistically significant (P<0.05). The VEGF levels of NC group, NDR group and DR group were increased gradually, and the difference was statistically significant (P<0.05). The malondialdehyde (MDA) levels of NC group, NDR group and DR group increased gradually, and the difference was statistically significant (P<0.05). The superoxide dismutase (SOD) levels of NC group, NDR group and DR group were decreased gradually, and the difference was statistically significant (P<0.05). Conclusions: DR patients express high levels of IL-6, TNF-α and VEGF, and there exists significant oxidative stress in DR, which shows that the inflammation occurrence and oxidative stress state play an important role in the development of DR.展开更多
Drawing on a dataset covering a large number of randomly sampled villages across China, the present paper examines the issue of residential solid waste management service provision in rural China, Using a logistic mod...Drawing on a dataset covering a large number of randomly sampled villages across China, the present paper examines the issue of residential solid waste management service provision in rural China, Using a logistic model we evaluate the impacts of different factors on service provision at the village level with regard to residential solid waste disposal. These factors include the environmental pressures caused by residential solid waste generation, the financial capacity of the Villagers＇ Committee, village elections and the individual characteristics of village heads. We find that living density, village per capita income, the ratio of irrigated land, and the per capita profit submitted by village enterprises to the Villagers＇ Committee all have positive impacts on service provision. Moreover, village heads who are popularly elected by villagers are more likely to provide services that satisfy voters＇ demands.展开更多
Using nationally representative data, the present paper examines the impact of China＇s ongoing rural tax reform on farmers. The difficulties in further local governance restructuring are also discussed. It is argued ...Using nationally representative data, the present paper examines the impact of China＇s ongoing rural tax reform on farmers. The difficulties in further local governance restructuring are also discussed. It is argued that the issues associated with rural taxation and local governance in China result from inherent tension between an increasingly liberalized economic system and a still centralized political system. Although rural tax reform has helped to reduce farmers＂ tax burdens in the short term, the establishment of an effective local governance regime requires coordinated reforms to downsize local bureaucracy by providing social security for laid-off cadres, to strengthen local accountability by granting higher local formal tax autonomy, and to promote meaningful participation by expanding local democracy.展开更多
Oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)are the key processes in water splitting.Compared with the two-electron process in HER,the four-electron process of OER is slow because of the more com...Oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)are the key processes in water splitting.Compared with the two-electron process in HER,the four-electron process of OER is slow because of the more complex series of reactions.Therefore,a good understanding of the direct O_(2) evolution mechanism(DOEM)in OER is crucial to design high-efficiency catalysts to overcome the limitations imposed by the conventional adsorption evolution mechanism.In this work,honeycomb Ni_(3)N-Co_(3)N was prepared on carbon cloth(Ni_(3)N-Co_(3)N/CC)to investigate the DOEM.Density functional theory and in situ Raman scattering spectroscopy demonstrated that the OER process on Ni_(3)N-Co_(3)N/CC proceeded via the DOEM pathway,in which Ni_(3)N and Co_(3)N share the roles of dragging OH^(-),splitting off H-O bonds,and adsorbing other OH^(-),leading to significantly reduced Gibbs’s energy barriers of ΔG_(*OH) to ΔG_(O*)and ΔG_(O*)to ΔG_(O*OH).Moreover,the vertical honeycomb structure and conductive CC substrate contributed to the structural stability,conductivity,and quick O_(2) release capability.The Ni_(3)N-Co_(3)N/CC required low overpotentials of 320 and 495 mV to reach a current density of 10 and 100 mA cm^(-2),respectively.Moreover,the Ni_(3)N-Co_(3)N/CC delivered excellent stability with>90% retention of the initial current density over an 80-h-long test.展开更多
基金financially supported by the Hong Kong Baptist University(No.RMGS-2019-1-03A)。
文摘Molybdenum oxide(MoO_(3)), with superior features of multi-electrochemical states, high theoretical capacitance, and low cost, is a desirable supercapacitor electrode material but suffers from low conductivity and insufficient active sites. The MoO_(3) capacitance can be largely amplified by introducing oxygen(O) vacancies, but the mechanisms at the atomic scale are still ambiguous.Herein, O vacancies are created at the O2 and O3 sites in the MoO_(3) nanobelts by carbonization to maximize the supercapacitance in the MoO_(2.39). The supercapacitive storage is mainly ascribed to the proton adsorption at the O1 sites to create Mo–OH, leading to an expansion of the interlayer spacing along the lattice B-axis. Roughly 98% of the initial supercapacitance is retained after 1000 cycles,due to the reversible change in the interlayer spacing. Our results provide an insight into the oxygen deficiency-related mechanisms of the supercapacitive performance at the atomic scale and devise a facile method to enhance the supercapacitance for energy storage and conversion.
基金supported by the National Natural Science Foundation of China(Grant Nos.11474105 and 51172079)the Science and Technology Program of Guangdong Province,China(Grant Nos.2015B090903078 and 2015B010105011)+1 种基金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)
文摘The anomalous hysteresis in a perovskite solar cell induced by an asymmetric field is confirmed by a capacitance–voltage measurement. By applying several cycles of alternating reverse and forward scans, this hysteresis phenomenon is obviously alleviated, resulting in a hysteresis-less state in the perovskite solar cell. Meanwhile, the open-circuit voltage and power conversion efficiency of the perovskite solar cell are enhanced by 55.74% and 61.30%, respectively, while the current density and fill factor keep almost invariable. The operation of alleviating hysteresis is essential for further research and is likely to bring in performance gains.
基金financially supported by the Hong Kong Scholars Program (XJ2018009)the City University of Hong Kong Strategic Research Grant (SRG) (7005505)+3 种基金the Shenzhen – Hong Kong Innovative Collaborative Research and Development Program (SGLH20181109110802117 and CityU 9240014)the National Natural Science Foundation of China(U2004210, 21875080, 51572100 and 52003129)the Innovative Research Group Project of the Natural Science Foundation of Hubei Province (2019CFA020)the Shandong Provincial Natural Science Foundation (ZR2019BB006)。
文摘Large-scale deployment of Internet of Things (IoT),a revolutionary innovation for a better world,is hampered by the limitation of energy self-sufficiency.Constructing transition metal nitride (TMN)-based micro-supercapacitors is a possible solution by taking advantage of the high conductivity,large specific capacitance,and large tap density of the materials.However,the pseudocapacitive storage mechanism of TMNs is still unclear consequently impeding the design of microdevices.Herein,the functions and mechanism of TMNs with different metal oxynitride (TMNO_(x)) concentrations in pseudocapacitive electrodes are investigated systematically by in situ Raman scattering,ex situ X-ray photoelectron spectroscopy,as well as ion isolation and substitution cyclic voltammetry.It is found that the specific capacitances of TMNs depend on the TMNO_(x) concentrations and the N–M–O site is responsible for the large pseudocapacitance via the Faradic reaction between TMNO_(x) and OH^(-).Our study elucidates the mechanism pertaining to pseudocapacitive charge storage of TMNs and provides insights into the design and optimization of TMNO_(x) as well as other electrode materials for pseudocapacitors.
文摘Objective:To determine the serum inflammatory cytokines and oxidative stress parameters of diabetic retinopathy (DR) patients to explore their possible role in the DR.Methods: 116 cases of type 2 diabetic patients were selected from June 2015 to June 2016 in our hospital as research subjects, divided into diabetic Diabetes without retinopathy (NDR group,n = 63) and diabetic with retinopathy patients (DR group,n = 53). And 60 cases of healthy check-ups of the same period in our hospital medical center were selected as normal control group (NC). The VEGF, IL-6, TNF-α , MDA and SOD levels of three groups of patients were detected. Results:The IL-6 levels of NC group, NDR group and DR group were increased gradually, and the difference was statistically significant (P<0.05). The TNF-α levels of NC group, NDR group and DR group were increased gradually, and the difference was statistically significant (P<0.05). The VEGF levels of NC group, NDR group and DR group were increased gradually, and the difference was statistically significant (P<0.05). The malondialdehyde (MDA) levels of NC group, NDR group and DR group increased gradually, and the difference was statistically significant (P<0.05). The superoxide dismutase (SOD) levels of NC group, NDR group and DR group were decreased gradually, and the difference was statistically significant (P<0.05). Conclusions: DR patients express high levels of IL-6, TNF-α and VEGF, and there exists significant oxidative stress in DR, which shows that the inflammation occurrence and oxidative stress state play an important role in the development of DR.
基金the China National Science Foundation (Project 70703027)the Economy of Environment Program for Southeast Asia (EEPSEA)/IDRC (Project 003591-064)
文摘Drawing on a dataset covering a large number of randomly sampled villages across China, the present paper examines the issue of residential solid waste management service provision in rural China, Using a logistic model we evaluate the impacts of different factors on service provision at the village level with regard to residential solid waste disposal. These factors include the environmental pressures caused by residential solid waste generation, the financial capacity of the Villagers＇ Committee, village elections and the individual characteristics of village heads. We find that living density, village per capita income, the ratio of irrigated land, and the per capita profit submitted by village enterprises to the Villagers＇ Committee all have positive impacts on service provision. Moreover, village heads who are popularly elected by villagers are more likely to provide services that satisfy voters＇ demands.
基金financial support from the Chinese National Science Foundation(Project 703030l1,70633002)Ford Foundation+1 种基金the Chinese Academy of Science Innovation Project(KSCX2-YW-N.039)the Matching NSFC Fund of the Institute of Geographical Sciences and Natural Resource Research,the Chinese Academy of Sciences.
文摘Using nationally representative data, the present paper examines the impact of China＇s ongoing rural tax reform on farmers. The difficulties in further local governance restructuring are also discussed. It is argued that the issues associated with rural taxation and local governance in China result from inherent tension between an increasingly liberalized economic system and a still centralized political system. Although rural tax reform has helped to reduce farmers＂ tax burdens in the short term, the establishment of an effective local governance regime requires coordinated reforms to downsize local bureaucracy by providing social security for laid-off cadres, to strengthen local accountability by granting higher local formal tax autonomy, and to promote meaningful participation by expanding local democracy.
基金financially supported by the City University of Hong Kong HK Tech 300(SF202109174)the National Natural Science Foundation of China(51902118)the International Postdoctoral Exchange Fellowship program(PC2021026)。
文摘Oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)are the key processes in water splitting.Compared with the two-electron process in HER,the four-electron process of OER is slow because of the more complex series of reactions.Therefore,a good understanding of the direct O_(2) evolution mechanism(DOEM)in OER is crucial to design high-efficiency catalysts to overcome the limitations imposed by the conventional adsorption evolution mechanism.In this work,honeycomb Ni_(3)N-Co_(3)N was prepared on carbon cloth(Ni_(3)N-Co_(3)N/CC)to investigate the DOEM.Density functional theory and in situ Raman scattering spectroscopy demonstrated that the OER process on Ni_(3)N-Co_(3)N/CC proceeded via the DOEM pathway,in which Ni_(3)N and Co_(3)N share the roles of dragging OH^(-),splitting off H-O bonds,and adsorbing other OH^(-),leading to significantly reduced Gibbs’s energy barriers of ΔG_(*OH) to ΔG_(O*)and ΔG_(O*)to ΔG_(O*OH).Moreover,the vertical honeycomb structure and conductive CC substrate contributed to the structural stability,conductivity,and quick O_(2) release capability.The Ni_(3)N-Co_(3)N/CC required low overpotentials of 320 and 495 mV to reach a current density of 10 and 100 mA cm^(-2),respectively.Moreover,the Ni_(3)N-Co_(3)N/CC delivered excellent stability with>90% retention of the initial current density over an 80-h-long test.
