Exploring hydroclimatic variability and its driving mechanisms during the Holocene is essential for comprehending both historical and prospective responses of water resources to climatic shifts in Arid Central Asia(AC...Exploring hydroclimatic variability and its driving mechanisms during the Holocene is essential for comprehending both historical and prospective responses of water resources to climatic shifts in Arid Central Asia(ACA)region.However,debate persists regarding whether dryland lakes in this region exhibited aridification or humidification during the Holocene.Lopnur serves as the terminal lake of Tarim rivers during the Holocene,which offers an ideal natural laboratory to address the questions.In this study,a high-resolution chronological framework was established through precise radiocarbon dating.Multi-proxy analyses,including geochemical composition,grain size distributions,MS,LOI,and C/N ratios were conducted from a lacustrine profile in the core area of“Great ear”in the southern part of Lopnur catchment.These analyses enabled the reconstruction of hydrological dynamics and facilitated the disentanglement of independent signals linked to climate variability,runoff fluctuations,and lake-level changes.The results demonstrate that the MidHolocene(7800–4000 cal yr B.P.)was characterized by cold and humid conditions,resulting in elevated surface runoff and lake level.The Late Holocene(4000–1300 cal yr B.P.)experienced intensified aridification,characterized by reduced runoff and declining lake level.These evidences suggested a climatic regime of a distinctive alternation between“cold-wet”and“warm-dry”climatic regimes during the Mid-to-Late Holocene.Compared with the previous studies from adjacent regions,we speculate that the hydroclimatic evolution of Lopnur catchment possibly influenced by a complex interplay of large spatial scale forcings,including variations in annual insolation,greenhouse gas concentrations,and ice sheets,as well as the localized controls such as topographic features,vegetation cover,and cloud-radiative feedbacks.Our findings enhance the understanding of past climatic complexity and provide valuable insights for future water resource management strategies in drylands.展开更多
The simultaneous accumulation of photo-holes and the specific activation of substrates present a significant challenge in photo-oxidation.Herein,we propose a dual-channel collaborative catalytic platform based on holl...The simultaneous accumulation of photo-holes and the specific activation of substrates present a significant challenge in photo-oxidation.Herein,we propose a dual-channel collaborative catalytic platform based on hollow TiO_(2) microspheres,using Cu single-atom(SA)catalysts and a composite polymer chain,to create separating pathways for unidirectional photogenerated electron/hole extraction.Ferrocene-functionalized graphene quantum dots are incorporated within the polymer chain for driving benzylamine(BA)oxidation.Quasi in situ transient photovoltage and femtosecond transient absorption tests reveal that leveraging the ultrafast charge separation capability of Cu SAs(0.44 ps)not only accelerates hole transport kinetics but also induces requisite Lewis acidity for the adsorption and activation of BA.In an air atmosphere,the rate of imine production reaches 4.81 mmol g^(−1) h^(−1)(selectivity of 98%).This study demonstrates the rational design of an SA/polymer chain dual-driven catalytic platform for optimizing kinetics and precisely controlling photocatalytic transformations in organic chemistry.展开更多
光电化学(PEC)分解水是一种清洁可持续的获取氢燃料的方法,其中产氧半反应(OER)是制约整个水分解过程效率的关键步骤.因此,光阳极的性能是决定太阳能到氢能转化效率的关键因素.在各种水氧化光阳极材料中,赤铁矿(α-Fe_(2)O_(3))因具有...光电化学(PEC)分解水是一种清洁可持续的获取氢燃料的方法,其中产氧半反应(OER)是制约整个水分解过程效率的关键步骤.因此,光阳极的性能是决定太阳能到氢能转化效率的关键因素.在各种水氧化光阳极材料中,赤铁矿(α-Fe_(2)O_(3))因具有良好的化学稳定性、合适的带隙(~2.1 eV)、无毒、储量丰富等优点而成为最有前途的光阳极材料之一.然而,α-Fe_(2)O_(3)丰富的受体表面态和缓慢的水氧化动力学导致光生电荷复合严重,限制了其在光电化学中的实际应用.因此,有必要对α-Fe_(2)O_(3)进行表面工程设计以提高水氧化效率.本文提出了一种新方法,以金属有机框架(Ti-MOFs)为模板,在Ti-Fe_(2)O_(3)表面煅烧合成TiO_(2)层,然后将富活性位点的ZIF-67加载在TiO_(2)/Ti-Fe_(2)O_(3)上作为助催化剂,制备出具有较好光电化学性能的ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3)复合光阳极.X射线衍射、高分辨透射电镜、X射线光电子能谱和拉曼光谱等表征结果证实成功合成了ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3).同时,氮气等温吸附脱附曲线和表面接触角测试结果表明,MOFs衍生的TiO_(2)为介孔材料.采用表面光伏技术、光致发光光谱、飞秒-瞬态吸收光谱和电化学阻抗谱分析,研究了光生电荷的分离和复合行为.结果表明,MOFs衍生的TiO_(2)不仅可以作为钝化层有效抑制了表面复合,还作为Ti-Fe_(2)O_(3)的电子阻挡层,显著减少了电子向表面的流失,从而大大提高了Ti-Fe_(2)O_(3)表面和体相的电荷分离效率.进一步的累积电荷量测试、电化学阻抗谱和Bode图分析显示,负载MOFs衍生TiO_(2)后,可以明显促进光生空穴向电解质的注入,其多孔结构也可以增加反应接触面积,这有利于光生电荷在固液界面传输.此外,理论计算结果表明,Ti-Fe_(2)O_(3)水氧化速控步骤的能垒(ΔG=3.38 eV)明显高于TiO_(2)(ΔG=1.67 eV),说明OER更容易在TiO_(2)/Ti-Fe_(2)O_(3)表面发生,这与其光电流密度结果一致.为进一步提高反应活性和加快水氧化动力学,负载助催化剂ZIF-67后,ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3)复合光阳极实现了较好的光电化学性能,其在1.23 V vs.RHE时光电流密度高达4.04 mA cm^(‒2),是Ti-Fe_(2)O_(3)的9.3倍,并且复合光阳极的入射光子电流转换效率和空穴注入效率分别达到93%(390 nm)和91%.综上所述,本研究通过MOFs衍生的TiO_(2)和ZIF-67助催化剂改性α-Fe_(2)O_(3)光阳极,显著提升了其光电化学水氧化性能.其中,MOFs衍生TiO_(2)不仅优化了电荷分离,还促进了光生空穴的注入,从而显著提高其光电化学水氧化性能.本研究为构筑高性能的有机-无机杂化光阳极提供了新思路.展开更多
Z-scheme photocatalytic system has been regarded as a popular field of research in photoelectrochemical(PEC)water splitting.Among the many obstacles facing a Z-scheme photocatalytic system,the analysis methods of inte...Z-scheme photocatalytic system has been regarded as a popular field of research in photoelectrochemical(PEC)water splitting.Among the many obstacles facing a Z-scheme photocatalytic system,the analysis methods of interfacial Z-scheme charge transfer still remain a significant challenge.Hence,in this study,CdS/Ti-Fe_(2)O_(3)heterojunction photoanodes are elaborately designed to explore the charge-transfer behavior in PEC water splitting.In this study,photophysical measurements,including the Kelvin probe measurement,surface photovoltage spectroscopy(SPV),and transient photovoltage spectroscopy(TPV),are used to monitor the migration behavior of photogenerated charges at the interface electric field of CdS/Ti-Fe_(2)O_(3)Z-scheme heterojunction photoanodes.The Kelvin probe and SPV measurements demonstrate that CdS/Ti-Fe_(2)O_(3)interfacial driving force favors the rapid transfer of photoexcited electrons to CdS.The double-beam strategy based on TPV indicates that more electrons of Ti-Fe_(2)O_(3)are combined with the holes of CdS owing to the intensive interface electric field.The results of these measurements successfully prove the Z-scheme migration mechanism of CdS/Ti-Fe_(2)O_(3)photoanodes.Benefiting from the desirable charge transfer at the interface electric field,CdS/Ti-Fe_(2)O_(3)photoanodes exhibit superior photocatalytic oxygen evolution reaction performance compared with that of pure Ti-Fe_(2)O_(3).The photocurrent density of the 25CdS/Ti-Fe_(2)O_(3)photoanode reaches 1.94 mA/cm^(2) at 1.23 V versus reversible hydrogen electrode without excess cocatalyst,and it is two times higher than that of pure Ti-Fe_(2)O_(3)photoanode.Therefore,an outstanding strategy is provided in this study to prove the Z-scheme charge-transfer mechanism of photocatalytic systems in PEC water splitting.展开更多
Drought stress limits the growth and development of grapevines,thereby reducing productivity,but the mechanisms by which grapevines respond to drought stress remain largely uncharacterized.Here,we characterized a grou...Drought stress limits the growth and development of grapevines,thereby reducing productivity,but the mechanisms by which grapevines respond to drought stress remain largely uncharacterized.Here,we characterized a group A bZIP gene from“Kyoho”grapevine,VlbZIP30,which was shown to be induced by abscisic acid(ABA)and dehydration stress.Overexpression of VlbZIP30 in transgenic Arabidopsis thaliana enhanced dehydration tolerance.Transcriptome analysis revealed that a major proportion of ABA-responsive and/or drought-responsive genes are transcriptionally regulated by VlbZIP30 during ABA or mannitol treatment at the cotyledon greening stage.We identified an A.thaliana G-box motif(CACGTG)and a potential grapevine G-box motif(MCACGTGK)in the promoters of the 39 selected A.thaliana genes upregulated in the transgenic plants and in the 35 grapevine homologs,respectively.Subsequently,using two grapevine-related databases,we found that 74%(23/31)and 84%(21/25)of the detected grapevine genes were significantly upregulated by ABA and drought stress,respectively,suggesting that these genes are involved in ABA or dehydration stress and may be regulated by VlbZIP30 in grapevine.We propose that VlbZIP30 functions as a positive regulator of dehydration-responsive signaling in the ABA core signaling pathway.展开更多
Highly photocatalytically active cobalt-doped ZnO （ZnO：Co） nanorods have been prepared by a facile hydrothermal process. X-ray diffraction, X-ray photoelectron spectroscopy, Raman scattering and UV-vis diffuse refl...Highly photocatalytically active cobalt-doped ZnO （ZnO：Co） nanorods have been prepared by a facile hydrothermal process. X-ray diffraction, X-ray photoelectron spectroscopy, Raman scattering and UV-vis diffuse reflectance spectroscopy confirmed that the dopant ions substitute for some of the lattice zinc ions, and furthermore, that Co〉 and Co〉 ions coexist. The as-prepared ZnO：Co samples have an extended light absorption range compared with pure ZnO and showed highly efficient photocatalytic activity, only requiring 60 rain to decompose -93% of alizarin red dye under visible light irradiation （λ 〉 420 nm）, The photophysical mechanism of the visible photocatalytic activity was investigated with the help of surface photovoltage spectroscopy. The results indicated that a strong electronic interaction between the Co and ZnO was present, and that the incorporation of Co promoted the charge separation and enhanced the charge transfer ability and, at the same time, effectively inhibited the recombination of photogenerated charge carriers in ZnO, resulting in high visible light photocatalytic activity.展开更多
The synthesis of graphene-semiconductor nanocomposites has attracted increasing attention due to their interesting optoelectronic properties.However the synthesis of such nanocomposites,with decorated particles well d...The synthesis of graphene-semiconductor nanocomposites has attracted increasing attention due to their interesting optoelectronic properties.However the synthesis of such nanocomposites,with decorated particles well dispersed on graphene,is still a great challenge.This work reports a facile,one-step,solvothermal method for the synthesis of graphene-CdS and graphene-ZnS quantum dot nanocomposites directly from graphene oxide,with CdS and ZnS very well dispersed on the graphene nanosheets.Photoluminescence measurements showed that the integration of CdS and ZnS with graphene significantly decreases their photoluminescence.Transient photovoltage studies revealed that the graphene-CdS nanocomposite exhibits a very unexpected strong positive photovoltaic response,while separate samples of graphene and CdS quantum dots(QDs)of a similar size do not show any photovoltaic response.展开更多
A facile and reproducible method has been developed for the synthesis of ordered anatase Mn-TiO2 nanospheres with controllable sizes in the range 200-300 nm by simply varying the amount of manganese（lI） chloride add...A facile and reproducible method has been developed for the synthesis of ordered anatase Mn-TiO2 nanospheres with controllable sizes in the range 200-300 nm by simply varying the amount of manganese（lI） chloride added. The samples were characterized by X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, scanning electron microscope （SEM）, and transmission electron microscope （TEM） measurements, and it was found that the manganese exists in multivalent forms （Mn4＋/Mn3＋） and substitutes for some of the Ti4＋ in the anatase TiO2 lattice. The presence of Mn significantly influences the morphology and high-temperature stability of TiO2, and extends its light absorption range. Surface photovoltage and photocurrent measurements revealed that an electronic interaction between the Mn and TiO2 was present, in which Mn served as an electron acceptor and effectively inhibited the charge recombination in TiO2; this is thought to be responsible for the highly efficient photocatalytic activity of the material in the degradation of rhodarnine B （RhB） under visible-light irradiation （λ 〉 420 nm）.展开更多
Soil organic carbon(SOC)plays an essential role in the carbon cycle and global warming mitigation,and it varies spatially in relation to other soil and environmental properties.But the national distributions and the i...Soil organic carbon(SOC)plays an essential role in the carbon cycle and global warming mitigation,and it varies spatially in relation to other soil and environmental properties.But the national distributions and the impact mechanisms of SOC remain debated in China.Therefore,how soil texture and climate factors affect the SOC content and the regional differences in SOC content were explored by analyzing 7857 surface soil samples with different land-use.The results showed that the SOC content in China,with a mean value of 11.20 g·kg^(-1),increased gradually from north to south.The SOC content of arable land in each geographical area was lower than in grassland and forest-land.Although temperature also played a specific role in the SOC content,precipitation was the most critical climate factor.The SOC content was positively correlated with the silt and clay content.The lower the temperature,the greater the effect of environmental factors on SOC.In contrast,the higher the temperature,the more significant impact of soil texture on SOC.The regional difference in SOC highlights the importance of soil responses to climate change.Tempera-ture and soil texture should be explicitly considered when predicting potential future carbon cycle and sequestration.展开更多
To improve the logic stability of conventional multi-valued logic（MVL） circuits designed with a GaNbased resonate tunneling diode（RTD）, we proposed a GaN/InGaN/AlGaN multi-quantum well（MQW） RTD. The proposed RTD...To improve the logic stability of conventional multi-valued logic（MVL） circuits designed with a GaNbased resonate tunneling diode（RTD）, we proposed a GaN/InGaN/AlGaN multi-quantum well（MQW） RTD. The proposed RTD was simulated through solving the coupled Schrodinger and Poisson equations in the numerical non-equilibrium Green＇s function（NEGF） method on the TCAD platform. The proposed RTD was grown layer by layer in epitaxial technologies. Simulated results indicate that its current-voltage characteristic appears to have a wider total negative differential resistance region than those of conventional ones and an obvious hysteresis loop at room temperature. To increase the Al composite of AIGaN barrier layers properly results in increasing of both the total negative differential resistance region width and the hysteresis loop width, which is helpful to improve the logic stability of MVL circuits. Moreover, the complement resonate tunneling transistor pair consisted of the proposed RTDs or the proposed RTD and enhanced mode HEMT controlled RTD8 is capable of generating versatile MVL modes at different supply voltages less than 3.3 V, which is very attractive for implementing more complex MVL function digital integrated circuits and systems with less devices, super high speed linear or nonlinear ADC and voltage sensors with a built-in super high speed ADC function.展开更多
Objectives:To investigate the health-related quality of life(HRQL)of long-term survivors of inoperable esophageal squamous cell carcinoma(ESCC)treated with definitive radiation therapy,the real-world trends in the use...Objectives:To investigate the health-related quality of life(HRQL)of long-term survivors of inoperable esophageal squamous cell carcinoma(ESCC)treated with definitive radiation therapy,the real-world trends in the use of advanced radiation techniques,and their impact on the survival outcomes of ESCC patients.Methods:In this multicenter retrospective observational study,the medical records related to demographics and treatment of ESCC patients who were treated with definitive radiation therapy at 14 provincial hospitals in China from 1 January 2015 to 31 December 2016 were analyzed.A HRQL questionnaire was completed by survivors and collected by doctors at the final follow-up.The difference in quality of life between patients with or without recurrence was compared using the Wilcoxon-Mann-Whitney test.Overall survival(OS)was estimated using the Kaplan-Meier method and the group differences were assessed by unstratified log-rank test.The Cox proportional hazards model with Efron’s method of tie handling was used to calculate the risk factors for OS.Results:The data of a total of 3,308 patients were collected for this study,248 were excluded because of missing data,and a final of 3,060 patients were included in the analysis.Most patients(2,901;94.8%)received intensity-modulated radiotherapy(IMRT)/volumetric-modulated arc therapy(VMAT)/tomotherapy(TOMO).The 5-year OS rate was 30%.Patients who received either two-dimensional radiotherapy(2DRT;HR,2.43[95%CI,1.70-3.47];P<0.001)or three-dimensional radiotherapy(3DRT;HR,1.45[95%CI,1.14-1.84];P=0.003)had a significantly increased risk of death compared to those who received IMRT/VMAT/TOMO.Of the 716(23.4%)long-term survivors who completed the HRQL questionnaire,nearly 70%patients were still able to swallow normally or almost normally,and>80%patients did not experience weight loss.Nearly 80%patients found life very enjoyable or were fairly enjoying life.Conclusions:This large,multicenter retrospective study on ESCC patients who received definitive radiation ther-apy found that most ESCC survivors are satisfied with their quality of life.Most patients received advanced radiation technology.Patients who received either 2DRT or 3DRT had a significantly increased risk of death compared to those who received advanced radiation technology.展开更多
Herein,a cocatalyst was extensively used to enhance the photocatalytic water oxidation performance.In a cocatalyst/semiconductor system,charge transfer between a semiconductor and cocatalyst is a crucial process for t...Herein,a cocatalyst was extensively used to enhance the photocatalytic water oxidation performance.In a cocatalyst/semiconductor system,charge transfer between a semiconductor and cocatalyst is a crucial process for the photoelectrochemical(PEC)water oxidation performance;however,the influence of surface states on charge transfer has rarely been discussed.In this study,Al_(2)O_(3)was inserted into the CoPi/Ti-Fe_(2)O_(3)interface to fabricate a CoPi/Al_(2)O_(3)/Ti-Fe_(2)O_(3)photoanode.CoPi/Al_(2)O_(3)/Ti-Fe_(2)O_(3)showed a notable improvement in the photocurrent density.A combination of UV-vis diffuse reflectance spectroscopy(DRS),surface photovoltage spectroscopy(SPS),chopped light photocurrent,and photocurrents under different chopped light frequencies was used to study the real role of Al_(2)O_(3)in the charge transfer process.It was found that Al_(2)O_(3)passivated the surface states of Ti-doped Fe_(2)O_(3),leading to a better interfacial charge transfer between Ti-doped Fe_(2)O_(3)and CoPi,resulting in the enhanced PEC water oxidation performance.展开更多
基金supported by the National Natural Science Foundation of China(No.42001084)the Major Science and Technology Projects of Xinjiang Uygur Autonomous Region(Nos.2022A03009-2,2022A03009)the Third Xinjiang Scientific Expedition Program(No.2022xjkk1303)。
文摘Exploring hydroclimatic variability and its driving mechanisms during the Holocene is essential for comprehending both historical and prospective responses of water resources to climatic shifts in Arid Central Asia(ACA)region.However,debate persists regarding whether dryland lakes in this region exhibited aridification or humidification during the Holocene.Lopnur serves as the terminal lake of Tarim rivers during the Holocene,which offers an ideal natural laboratory to address the questions.In this study,a high-resolution chronological framework was established through precise radiocarbon dating.Multi-proxy analyses,including geochemical composition,grain size distributions,MS,LOI,and C/N ratios were conducted from a lacustrine profile in the core area of“Great ear”in the southern part of Lopnur catchment.These analyses enabled the reconstruction of hydrological dynamics and facilitated the disentanglement of independent signals linked to climate variability,runoff fluctuations,and lake-level changes.The results demonstrate that the MidHolocene(7800–4000 cal yr B.P.)was characterized by cold and humid conditions,resulting in elevated surface runoff and lake level.The Late Holocene(4000–1300 cal yr B.P.)experienced intensified aridification,characterized by reduced runoff and declining lake level.These evidences suggested a climatic regime of a distinctive alternation between“cold-wet”and“warm-dry”climatic regimes during the Mid-to-Late Holocene.Compared with the previous studies from adjacent regions,we speculate that the hydroclimatic evolution of Lopnur catchment possibly influenced by a complex interplay of large spatial scale forcings,including variations in annual insolation,greenhouse gas concentrations,and ice sheets,as well as the localized controls such as topographic features,vegetation cover,and cloud-radiative feedbacks.Our findings enhance the understanding of past climatic complexity and provide valuable insights for future water resource management strategies in drylands.
基金financial support provided by the National Natural Science Foundation of China(No.22172057).
文摘The simultaneous accumulation of photo-holes and the specific activation of substrates present a significant challenge in photo-oxidation.Herein,we propose a dual-channel collaborative catalytic platform based on hollow TiO_(2) microspheres,using Cu single-atom(SA)catalysts and a composite polymer chain,to create separating pathways for unidirectional photogenerated electron/hole extraction.Ferrocene-functionalized graphene quantum dots are incorporated within the polymer chain for driving benzylamine(BA)oxidation.Quasi in situ transient photovoltage and femtosecond transient absorption tests reveal that leveraging the ultrafast charge separation capability of Cu SAs(0.44 ps)not only accelerates hole transport kinetics but also induces requisite Lewis acidity for the adsorption and activation of BA.In an air atmosphere,the rate of imine production reaches 4.81 mmol g^(−1) h^(−1)(selectivity of 98%).This study demonstrates the rational design of an SA/polymer chain dual-driven catalytic platform for optimizing kinetics and precisely controlling photocatalytic transformations in organic chemistry.
文摘光电化学(PEC)分解水是一种清洁可持续的获取氢燃料的方法,其中产氧半反应(OER)是制约整个水分解过程效率的关键步骤.因此,光阳极的性能是决定太阳能到氢能转化效率的关键因素.在各种水氧化光阳极材料中,赤铁矿(α-Fe_(2)O_(3))因具有良好的化学稳定性、合适的带隙(~2.1 eV)、无毒、储量丰富等优点而成为最有前途的光阳极材料之一.然而,α-Fe_(2)O_(3)丰富的受体表面态和缓慢的水氧化动力学导致光生电荷复合严重,限制了其在光电化学中的实际应用.因此,有必要对α-Fe_(2)O_(3)进行表面工程设计以提高水氧化效率.本文提出了一种新方法,以金属有机框架(Ti-MOFs)为模板,在Ti-Fe_(2)O_(3)表面煅烧合成TiO_(2)层,然后将富活性位点的ZIF-67加载在TiO_(2)/Ti-Fe_(2)O_(3)上作为助催化剂,制备出具有较好光电化学性能的ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3)复合光阳极.X射线衍射、高分辨透射电镜、X射线光电子能谱和拉曼光谱等表征结果证实成功合成了ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3).同时,氮气等温吸附脱附曲线和表面接触角测试结果表明,MOFs衍生的TiO_(2)为介孔材料.采用表面光伏技术、光致发光光谱、飞秒-瞬态吸收光谱和电化学阻抗谱分析,研究了光生电荷的分离和复合行为.结果表明,MOFs衍生的TiO_(2)不仅可以作为钝化层有效抑制了表面复合,还作为Ti-Fe_(2)O_(3)的电子阻挡层,显著减少了电子向表面的流失,从而大大提高了Ti-Fe_(2)O_(3)表面和体相的电荷分离效率.进一步的累积电荷量测试、电化学阻抗谱和Bode图分析显示,负载MOFs衍生TiO_(2)后,可以明显促进光生空穴向电解质的注入,其多孔结构也可以增加反应接触面积,这有利于光生电荷在固液界面传输.此外,理论计算结果表明,Ti-Fe_(2)O_(3)水氧化速控步骤的能垒(ΔG=3.38 eV)明显高于TiO_(2)(ΔG=1.67 eV),说明OER更容易在TiO_(2)/Ti-Fe_(2)O_(3)表面发生,这与其光电流密度结果一致.为进一步提高反应活性和加快水氧化动力学,负载助催化剂ZIF-67后,ZIF-67/TiO_(2)/Ti-Fe_(2)O_(3)复合光阳极实现了较好的光电化学性能,其在1.23 V vs.RHE时光电流密度高达4.04 mA cm^(‒2),是Ti-Fe_(2)O_(3)的9.3倍,并且复合光阳极的入射光子电流转换效率和空穴注入效率分别达到93%(390 nm)和91%.综上所述,本研究通过MOFs衍生的TiO_(2)和ZIF-67助催化剂改性α-Fe_(2)O_(3)光阳极,显著提升了其光电化学水氧化性能.其中,MOFs衍生TiO_(2)不仅优化了电荷分离,还促进了光生空穴的注入,从而显著提高其光电化学水氧化性能.本研究为构筑高性能的有机-无机杂化光阳极提供了新思路.
文摘Z-scheme photocatalytic system has been regarded as a popular field of research in photoelectrochemical(PEC)water splitting.Among the many obstacles facing a Z-scheme photocatalytic system,the analysis methods of interfacial Z-scheme charge transfer still remain a significant challenge.Hence,in this study,CdS/Ti-Fe_(2)O_(3)heterojunction photoanodes are elaborately designed to explore the charge-transfer behavior in PEC water splitting.In this study,photophysical measurements,including the Kelvin probe measurement,surface photovoltage spectroscopy(SPV),and transient photovoltage spectroscopy(TPV),are used to monitor the migration behavior of photogenerated charges at the interface electric field of CdS/Ti-Fe_(2)O_(3)Z-scheme heterojunction photoanodes.The Kelvin probe and SPV measurements demonstrate that CdS/Ti-Fe_(2)O_(3)interfacial driving force favors the rapid transfer of photoexcited electrons to CdS.The double-beam strategy based on TPV indicates that more electrons of Ti-Fe_(2)O_(3)are combined with the holes of CdS owing to the intensive interface electric field.The results of these measurements successfully prove the Z-scheme migration mechanism of CdS/Ti-Fe_(2)O_(3)photoanodes.Benefiting from the desirable charge transfer at the interface electric field,CdS/Ti-Fe_(2)O_(3)photoanodes exhibit superior photocatalytic oxygen evolution reaction performance compared with that of pure Ti-Fe_(2)O_(3).The photocurrent density of the 25CdS/Ti-Fe_(2)O_(3)photoanode reaches 1.94 mA/cm^(2) at 1.23 V versus reversible hydrogen electrode without excess cocatalyst,and it is two times higher than that of pure Ti-Fe_(2)O_(3)photoanode.Therefore,an outstanding strategy is provided in this study to prove the Z-scheme charge-transfer mechanism of photocatalytic systems in PEC water splitting.
基金This work was supported by the National Natural Science Foundation of China(31572110)as well as the Program for Innovative Research Team of Grape Germplasm Resources and Breeding(2013KCT-25).
文摘Drought stress limits the growth and development of grapevines,thereby reducing productivity,but the mechanisms by which grapevines respond to drought stress remain largely uncharacterized.Here,we characterized a group A bZIP gene from“Kyoho”grapevine,VlbZIP30,which was shown to be induced by abscisic acid(ABA)and dehydration stress.Overexpression of VlbZIP30 in transgenic Arabidopsis thaliana enhanced dehydration tolerance.Transcriptome analysis revealed that a major proportion of ABA-responsive and/or drought-responsive genes are transcriptionally regulated by VlbZIP30 during ABA or mannitol treatment at the cotyledon greening stage.We identified an A.thaliana G-box motif(CACGTG)and a potential grapevine G-box motif(MCACGTGK)in the promoters of the 39 selected A.thaliana genes upregulated in the transgenic plants and in the 35 grapevine homologs,respectively.Subsequently,using two grapevine-related databases,we found that 74%(23/31)and 84%(21/25)of the detected grapevine genes were significantly upregulated by ABA and drought stress,respectively,suggesting that these genes are involved in ABA or dehydration stress and may be regulated by VlbZIP30 in grapevine.We propose that VlbZIP30 functions as a positive regulator of dehydration-responsive signaling in the ABA core signaling pathway.
基金Acknowledgements We are grateful to the National Basic Research Program of China （973 Program, No. 2007CB613303） for financial support. This work was also supported by the National Natural Science Foundation of China （No. 20873053）.
文摘Highly photocatalytically active cobalt-doped ZnO （ZnO：Co） nanorods have been prepared by a facile hydrothermal process. X-ray diffraction, X-ray photoelectron spectroscopy, Raman scattering and UV-vis diffuse reflectance spectroscopy confirmed that the dopant ions substitute for some of the lattice zinc ions, and furthermore, that Co〉 and Co〉 ions coexist. The as-prepared ZnO：Co samples have an extended light absorption range compared with pure ZnO and showed highly efficient photocatalytic activity, only requiring 60 rain to decompose -93% of alizarin red dye under visible light irradiation （λ 〉 420 nm）, The photophysical mechanism of the visible photocatalytic activity was investigated with the help of surface photovoltage spectroscopy. The results indicated that a strong electronic interaction between the Co and ZnO was present, and that the incorporation of Co promoted the charge separation and enhanced the charge transfer ability and, at the same time, effectively inhibited the recombination of photogenerated charge carriers in ZnO, resulting in high visible light photocatalytic activity.
基金This work was supported by the National Natural Science Foundation of China(No.20820102037)the 973 Project(Nos.2009CB930100 and 2010CB933600)+1 种基金Dr.Ping Wang gratefully acknowledges partial financial support from the China Postdoctoral Science Foundation(No.20090461047)973 Project(No.2007CB613303).
文摘The synthesis of graphene-semiconductor nanocomposites has attracted increasing attention due to their interesting optoelectronic properties.However the synthesis of such nanocomposites,with decorated particles well dispersed on graphene,is still a great challenge.This work reports a facile,one-step,solvothermal method for the synthesis of graphene-CdS and graphene-ZnS quantum dot nanocomposites directly from graphene oxide,with CdS and ZnS very well dispersed on the graphene nanosheets.Photoluminescence measurements showed that the integration of CdS and ZnS with graphene significantly decreases their photoluminescence.Transient photovoltage studies revealed that the graphene-CdS nanocomposite exhibits a very unexpected strong positive photovoltaic response,while separate samples of graphene and CdS quantum dots(QDs)of a similar size do not show any photovoltaic response.
基金This work was supported by National Program on Key Basic Research Project （973 Program） （No. 2007CB613303） and the National Natural Science Foundation of China （Nos. 20703020 and 20873053）.
文摘A facile and reproducible method has been developed for the synthesis of ordered anatase Mn-TiO2 nanospheres with controllable sizes in the range 200-300 nm by simply varying the amount of manganese（lI） chloride added. The samples were characterized by X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, scanning electron microscope （SEM）, and transmission electron microscope （TEM） measurements, and it was found that the manganese exists in multivalent forms （Mn4＋/Mn3＋） and substitutes for some of the Ti4＋ in the anatase TiO2 lattice. The presence of Mn significantly influences the morphology and high-temperature stability of TiO2, and extends its light absorption range. Surface photovoltage and photocurrent measurements revealed that an electronic interaction between the Mn and TiO2 was present, in which Mn served as an electron acceptor and effectively inhibited the charge recombination in TiO2; this is thought to be responsible for the highly efficient photocatalytic activity of the material in the degradation of rhodarnine B （RhB） under visible-light irradiation （λ 〉 420 nm）.
基金supported by the National Natural Science Foundation of China(Grant No.42107368)Independent R&D project plan of State Forestry and Grassland Administration(No.LC-6-06)+1 种基金the Shaanxi Province Innovation Talent Promotion Plan Project Technology Innovation Team(No.2018TD-037)the National Natural Science Foundation of China(Grant No.51779204)。
文摘Soil organic carbon(SOC)plays an essential role in the carbon cycle and global warming mitigation,and it varies spatially in relation to other soil and environmental properties.But the national distributions and the impact mechanisms of SOC remain debated in China.Therefore,how soil texture and climate factors affect the SOC content and the regional differences in SOC content were explored by analyzing 7857 surface soil samples with different land-use.The results showed that the SOC content in China,with a mean value of 11.20 g·kg^(-1),increased gradually from north to south.The SOC content of arable land in each geographical area was lower than in grassland and forest-land.Although temperature also played a specific role in the SOC content,precipitation was the most critical climate factor.The SOC content was positively correlated with the silt and clay content.The lower the temperature,the greater the effect of environmental factors on SOC.In contrast,the higher the temperature,the more significant impact of soil texture on SOC.The regional difference in SOC highlights the importance of soil responses to climate change.Tempera-ture and soil texture should be explicitly considered when predicting potential future carbon cycle and sequestration.
基金Project supported by the National Natural Science Foundation of China(Nos.61302009,61571171)
文摘To improve the logic stability of conventional multi-valued logic（MVL） circuits designed with a GaNbased resonate tunneling diode（RTD）, we proposed a GaN/InGaN/AlGaN multi-quantum well（MQW） RTD. The proposed RTD was simulated through solving the coupled Schrodinger and Poisson equations in the numerical non-equilibrium Green＇s function（NEGF） method on the TCAD platform. The proposed RTD was grown layer by layer in epitaxial technologies. Simulated results indicate that its current-voltage characteristic appears to have a wider total negative differential resistance region than those of conventional ones and an obvious hysteresis loop at room temperature. To increase the Al composite of AIGaN barrier layers properly results in increasing of both the total negative differential resistance region width and the hysteresis loop width, which is helpful to improve the logic stability of MVL circuits. Moreover, the complement resonate tunneling transistor pair consisted of the proposed RTDs or the proposed RTD and enhanced mode HEMT controlled RTD8 is capable of generating versatile MVL modes at different supply voltages less than 3.3 V, which is very attractive for implementing more complex MVL function digital integrated circuits and systems with less devices, super high speed linear or nonlinear ADC and voltage sensors with a built-in super high speed ADC function.
基金supported by the Sanming Project of Medicine in Shenzhen(grant num-ber:SZSM201612063)National Natural Science Foundation of China Research(grant numbers:U22A20326,81872454,21441010)the Beijing Xisike Clinical Oncology Research Foundation(grant number:Y-MSD2020-0324).
文摘Objectives:To investigate the health-related quality of life(HRQL)of long-term survivors of inoperable esophageal squamous cell carcinoma(ESCC)treated with definitive radiation therapy,the real-world trends in the use of advanced radiation techniques,and their impact on the survival outcomes of ESCC patients.Methods:In this multicenter retrospective observational study,the medical records related to demographics and treatment of ESCC patients who were treated with definitive radiation therapy at 14 provincial hospitals in China from 1 January 2015 to 31 December 2016 were analyzed.A HRQL questionnaire was completed by survivors and collected by doctors at the final follow-up.The difference in quality of life between patients with or without recurrence was compared using the Wilcoxon-Mann-Whitney test.Overall survival(OS)was estimated using the Kaplan-Meier method and the group differences were assessed by unstratified log-rank test.The Cox proportional hazards model with Efron’s method of tie handling was used to calculate the risk factors for OS.Results:The data of a total of 3,308 patients were collected for this study,248 were excluded because of missing data,and a final of 3,060 patients were included in the analysis.Most patients(2,901;94.8%)received intensity-modulated radiotherapy(IMRT)/volumetric-modulated arc therapy(VMAT)/tomotherapy(TOMO).The 5-year OS rate was 30%.Patients who received either two-dimensional radiotherapy(2DRT;HR,2.43[95%CI,1.70-3.47];P<0.001)or three-dimensional radiotherapy(3DRT;HR,1.45[95%CI,1.14-1.84];P=0.003)had a significantly increased risk of death compared to those who received IMRT/VMAT/TOMO.Of the 716(23.4%)long-term survivors who completed the HRQL questionnaire,nearly 70%patients were still able to swallow normally or almost normally,and>80%patients did not experience weight loss.Nearly 80%patients found life very enjoyable or were fairly enjoying life.Conclusions:This large,multicenter retrospective study on ESCC patients who received definitive radiation ther-apy found that most ESCC survivors are satisfied with their quality of life.Most patients received advanced radiation technology.Patients who received either 2DRT or 3DRT had a significantly increased risk of death compared to those who received advanced radiation technology.
基金the National Basic Research Program of China(973 Program)(2013CB632403)the National Natural Science Foundation of China(No.51572106)the Science and Technology Developing Funding of Jilin Province(No.20150203009GX).
文摘Herein,a cocatalyst was extensively used to enhance the photocatalytic water oxidation performance.In a cocatalyst/semiconductor system,charge transfer between a semiconductor and cocatalyst is a crucial process for the photoelectrochemical(PEC)water oxidation performance;however,the influence of surface states on charge transfer has rarely been discussed.In this study,Al_(2)O_(3)was inserted into the CoPi/Ti-Fe_(2)O_(3)interface to fabricate a CoPi/Al_(2)O_(3)/Ti-Fe_(2)O_(3)photoanode.CoPi/Al_(2)O_(3)/Ti-Fe_(2)O_(3)showed a notable improvement in the photocurrent density.A combination of UV-vis diffuse reflectance spectroscopy(DRS),surface photovoltage spectroscopy(SPS),chopped light photocurrent,and photocurrents under different chopped light frequencies was used to study the real role of Al_(2)O_(3)in the charge transfer process.It was found that Al_(2)O_(3)passivated the surface states of Ti-doped Fe_(2)O_(3),leading to a better interfacial charge transfer between Ti-doped Fe_(2)O_(3)and CoPi,resulting in the enhanced PEC water oxidation performance.
