Fabricating low-strain and fast-charging silicon-carbon composite anodes is highly desired but remains a huge challenge for lithium-ion batteries.Herein,we report a unique silicon-carbon composite fabricated by unifor...Fabricating low-strain and fast-charging silicon-carbon composite anodes is highly desired but remains a huge challenge for lithium-ion batteries.Herein,we report a unique silicon-carbon composite fabricated by uniformly dis-persing amorphous Si nanodots(SiNDs)in carbon nanospheres(SiNDs/C)that are welded on the wall of the macroporous carbon framework(MPCF)by vertical graphene(VG),labeled as MPCF@VG@SiNDs/C.The high dispersity and amor-phous features of ultrasmall SiNDs(~0.7 nm),the flexible and directed electron/Li+transport channels of VG,and the MPCF impart the MPCF@VG@SiNDs/C more lithium storage sites,rapid Li+transport path,and unique low-strain property during Li+storage.Consequently,the MPCF@VG@SiNDs/C exhibits high cycle stability(1301.4 mAh g^(-1) at 1 A g^(-1) after 1000 cycles without apparent decay)and high rate capacity(910.3 mAh g^(-1),20 A g^(-1))in half cells based on industrial electrode standards.The assembled pouch full cell delivers a high energy density(1694.0 Wh L^(-1);602.8 Wh kg^(-1))and an excellent fast-charging capability(498.5 Wh kg^(-1),charging for 16.8 min at 3 C).This study opens new possibilities for preparing advanced silicon-carbon com-posite anodes for practical applications.展开更多
Pheretima,also called“earthworms”,is a well-known animal-derived traditional Chinese medicine that is extensively used in over 50 Chinese patent medicines(CPMs)in Chinese Pharmacopoeia(2020 edition).However,its zool...Pheretima,also called“earthworms”,is a well-known animal-derived traditional Chinese medicine that is extensively used in over 50 Chinese patent medicines(CPMs)in Chinese Pharmacopoeia(2020 edition).However,its zoological origin is unclear,both in the herbal market and CPMs.In this study,a strategy for integrating in-house annotated protein databases constructed from close evolutionary relationship-sourced RNA sequencing data from public archival resources and various sequencing algorithms(restricted search,open search,and de novo)was developed to characterize the phenotype of natural peptides of three major commercial species of Pheretima,including Pheretima aspergillum(PA),Pheretima vulgaris(PV),and Metaphire magna(MM).We identified 10,477 natural peptides in the PA,7,451 in PV,and 5,896 in MM samples.Five specific signature peptides were screened and then validated using synthetic peptides;these demonstrated robust specificity for the authentication of PA,PV,and MM.Finally,all marker peptides were successfully applied to identify the zoological origins of Brain Heart capsules and Xiaohuoluo pills,revealing the inconsistent Pheretima species used in these CPMs.In conclusion,our integrated strategy could be used for the in-depth characterization of natural peptides of other animal-derived traditional Chinese medicines,especially non-model species with poorly annotated protein databases.展开更多
Ground-based optical observation has unique advantages in space target observation.However,due to the weak light-gathering ability of small-aperture optoelectronic observation telescopes,the space debris in the image ...Ground-based optical observation has unique advantages in space target observation.However,due to the weak light-gathering ability of small-aperture optoelectronic observation telescopes,the space debris in the image is weak and easily drowned in noise.In order to solve the above problems,we use digital image processing technology to extract faint space debris.We propose a high detection rate space debris automatic extraction algorithm,aiming to automatically detect space debris.We first establish a new space target description model.Our algorithm is mainly divided into two stages.The purpose of the first stage is to reduce the influence of a large number of stars.We perform wavelet transform and guided filtering for three consecutive frames,and the reconstructed wavelet that takes the median value can achieve the effect of eliminating stars.In the second stage,we adopt the method of robust principal component analysis and attribute the problem of target detection to the problem of separating the target and background of a single frame of image.After a large number of experimental results analysis,it is proved that the algorithm can effectively detect faint debris in the monitoring system of small aperture telescope,and has high precision and low computational complexity.展开更多
Voltage-gated sodium channels (VGSCs) in primary sensory neurons play a key role in transmitting pain signals to the central nervous system. BmK I, a site-3 sodium channel-specific toxin from scorpion Buthus martens...Voltage-gated sodium channels (VGSCs) in primary sensory neurons play a key role in transmitting pain signals to the central nervous system. BmK I, a site-3 sodium channel-specific toxin from scorpion Buthus martensi Karsch, induces pain behaviors in rats. How- ever, the subtypes of VGSCs targeted by BmK I were not entirely clear. We therefore investigated the effects of BmK I on the current amplitude, gating and kinetic properties of Nav1.8, which is associated with neuronal hyperexcitability in DRG neurons. It was found that BmK I dose-dependently increased Nav1.8 current in small- sized (〈25 μm) acutely dissociated DRG neurons, which correlated with its inhibition on both fast and slow in- activation. Moreover, voltage-dependent activation and steady-state inactivation curves of Nay1.8 were shifted in a hyperpolarized direction. Thus, BmK I reduced the threshold of neuronal excitability and increased action potential firing in DRG neurons. In conclusion, our data clearly demonstrated that BmK I modulated Nav1.8 re- markably, suggesting BmK I as a valuable probe for studying Nay1.8. And Navl.8 is an important target re- lated to BmK I-evoked pain.展开更多
In the process of collating the raw data,the authors noticed an inadvertent mistake occurred in Fig.3b that needs to be corrected after online publication of the article.In Fig.3b,as a result of an error in the graphi...In the process of collating the raw data,the authors noticed an inadvertent mistake occurred in Fig.3b that needs to be corrected after online publication of the article.In Fig.3b,as a result of an error in the graphics panel arrangement process,the band of NEMO was repeatedly inserted asβ-actin by mistake.The correct band is shown as below and in the updated Fig.3b.The correction did not affect any of our results or discussion as present in the original publication.We regret any inconvenience this has caused.展开更多
Grain chalkiness,an undesirable trait caused by complex factors,has great negative impacts on the quality and economic value of rice.However,little is known about the regulatory mechanism of grain chalkiness,particula...Grain chalkiness,an undesirable trait caused by complex factors,has great negative impacts on the quality and economic value of rice.However,little is known about the regulatory mechanism of grain chalkiness,particularly the effect of endoplasmic reticulum(ER)stress.Here,a genome-wide association study(GWAS)reveals that the transcription factor Osb ZIP60 is a vital regulator of rice grain chalkiness.Genetic analysis demonstrates that knockout of Osb ZIP60 results in extremely high grain chalkiness and aberrant structure of storage substances.Notably,the expression of unfolded protein response(UPR)genes,such as OsbZIP50,Os Bi P1,Os Bi P2 and Os Bi P3,is up-regulated in the endosperm cells of osbzip60,and overexpression of all these UPR genes causes various degrees of chalkiness.Furthermore,Osb ZIP60 is found to activate the expression of key genes related to grain chalkiness,such as GPA3,FSE1,FLO7,Chalk5,Os NF-YB1,and Os PK2,whose expression is significantly suppressed in osbzip60 and overexpression lines of Osb ZIP50,Os Bi P1,Os Bi P2,and Os Bi P3.Our study provides novel insights into the function of Osb ZIP60 and the role of the UPR pathway in the formation of grain chalkiness in rice.展开更多
Graphene resting on a silicon-on-insulator platform offers great potential for optoelectronic devices.In the paper,we demonstrate all-optical modulation on the graphene-silicon hybrid waveguides(GSHWs)with tens of mic...Graphene resting on a silicon-on-insulator platform offers great potential for optoelectronic devices.In the paper,we demonstrate all-optical modulation on the graphene-silicon hybrid waveguides(GSHWs)with tens of micrometers in length.Owing to strong interaction between graphene and silicon strip waveguides with compact light confinement,the modulation depth reaches 22.7%with a saturation threshold down to 1.38 pJ per pulse and a 30-μm-long graphene pad.A response time of 1.65 ps is verified by a pump-probe measurement with an energy consumption of 2.1 pJ.The complementary metal-oxide semiconductor compatible GSHWs with the strip configuration exhibit great potential for ultrafast and broadband all-optical modulation,indicating that employing two-dimensional materials has become a complementary technology to promote the silicon photonic platform.展开更多
In this paper, we propose and demonstrate an all-fiber passively Q-switched erbium doped fiber laser (EDFL) by using gold nanostars (GNSs) as a saturable absorber (SA) for the first time, to the best of our know...In this paper, we propose and demonstrate an all-fiber passively Q-switched erbium doped fiber laser (EDFL) by using gold nanostars (GNSs) as a saturable absorber (SA) for the first time, to the best of our knowledge. In comparison with other gold nanomorphologies, GNSs have multiple localized surface plasmon resonances, which means that they can be used to construct wideband ultrafast pulse lasers. By inserting the GNS SA into an EDFL cavity pumped by a 980 nm laser diode, a stable passively Q-switched laser at 1564.5 nm was achieved for a threshold pump power of 40 mW. By gradually increasing the pump power from 40 to 120 mW, the pulse duration decreases from 12.8 to 5.3 its and the repetition rate increases from 10 to 17 kHz. Our results indicate that the GNSs are a promising SA for constructing pulse lasers.展开更多
NEMO/IKKβcomplex is a central regulator of NF-κB signaling pathway,its dissociation has been considered to be an attractive therapeutic target.Herein,using a combined strategy of molecular pharmacological phenotypin...NEMO/IKKβcomplex is a central regulator of NF-κB signaling pathway,its dissociation has been considered to be an attractive therapeutic target.Herein,using a combined strategy of molecular pharmacological phenotyping,proteomics and bioinformatics analysis,Shikonin(SHK)is identified as a potential inhibitor of the IKKβ/NEMO complex.It destabilizes IKKβ/NEMO complex with IC_(50) of 174 nM,thereby significantly impairing the proliferation of colorectal cancer cells by suppressing the NF-κB pathway in vitro and in vivo.In addition,we also elucidated the potential target sites of SHK in the NEMO/IKKβcomplex.Our study provides some new insights for the development of potent small-molecule PPI inhibitors.展开更多
Due to the complex hydrogeological conditions in karst regions,it is difficult to measure sediment source contributions at a catchment scale directly.The objective of this study was to quantify the relative contributi...Due to the complex hydrogeological conditions in karst regions,it is difficult to measure sediment source contributions at a catchment scale directly.The objective of this study was to quantify the relative contributions of sediment sources and their temporal variability in a karst catchment in southwest China.Karst depressions can trap eroded sediment similar to a dam or reservoir and,thus,are representative and typical test beds for identifying sediment sources in karst regions.Three sediment cores were taken from a karst depression,58 soil samples from three potential sediment sources were collected,and 18 soil properties were analyzed.The relative contributions of cropland,forestland,and fissure or crack soils were calculated using a multivariate mixing model.The fingerprinting results demonstrated that the cropland was the main sediment source in karst catchment.Specifically,according to the mean sediment contributions of the three deposited sediment cores,the sediment contribution from cropland topsoil was 69.3%,varying from 46.9%to 92.3%,and forestland soil and crack soil accounted for 8.6%and 22.1%of the sediment yield,and varying from 2.8%to 16.5%and 4.8%-36.6%,respectively.This result indicated that great attention should be paid when using only a single core to quantify sediment provenance.Due to the deposited sediment was generally disturbed as cropland in the karst depression,the area that has not been disturbed in recent decades in depression was more appropriate to trace sediment sources in karst catchment.To the best of our knowledge,this study was the first to quantify the contributions of sediment sources in the karst catchment of southwest China.This study provides valuable information and a preliminary reference for applying a composite fingerprinting technique to quantify sediment sources in karst catchments.展开更多
Here,we developed one kind of novel TiO_(2) ceramics with colossal dielectric constant by chemical modifications(Bi^(3+) and Sb^(5+)),and discussed the physical origin for giant dielectric constant.Effects of Bi and/o...Here,we developed one kind of novel TiO_(2) ceramics with colossal dielectric constant by chemical modifications(Bi^(3+) and Sb^(5+)),and discussed the physical origin for giant dielectric constant.Effects of Bi and/or Sb on their microstructure,dielectric properties as well as its frequency and temperature stability were studied in detail.It was found that their dielectric properties are strongly sensitive to(Bi,Sb)contents,and colossal dielectric permittivity(CP)(10^(4)~10^(5))together with low dielectric loss(~5.7%)can be obtained in a wide composition range.In addition,all the ceramics possessed good frequency(10^(2)~10^(6)Hz)and temperature(-150-200℃)stability of dielectric properties.In addition,the defects caused by the Bi volatilization may be the reason for higher dielectric properties of(Bi_(0.5)Sb_(0.5))_(x)Ti_(1-x)O_(2) ceramics with respect to(A_(0.5)Sb_(0.5))_(x)Ti_(1-x)O_(2)(A=In,Pr,Dy,Sm,Gd,Yb,Ga,Al,Fe or Sc).According to the results of complex impedance and XPS,the electron-pinned defect-dipoles may be suitable to explain the CP phenomenon,and oxygen vacancies-induced by Bi^(3+)&Sb^(5+) substitution for Ti^(4+) should be responsible for conduction mechanism.We believe that this profound investigation can benefit the development of TiO_(2) ceramics as a CP material.展开更多
Beijing Daxing International Airport,a major landmark project in China and a new driver for national development,will represent the direction for the development of civil aviation airports in China.The airport,situate...Beijing Daxing International Airport,a major landmark project in China and a new driver for national development,will represent the direction for the development of civil aviation airports in China.The airport,situated in the junction of Nangezhuang,Daxing District,Beijing City and Gu’an County,Hebei Province,has seen its north terminal area and north terminal built in the first phase,covering a total construction area of about 1.4 million m2.The north terminal area is designed to have an annual throughput of 45 million passengers.展开更多
基金All authors acknowledge fund support from Guangdong Basic and Applied Basic Research Foundation(2020A1515110762)National Natural Science Foundation of China(52172084).
文摘Fabricating low-strain and fast-charging silicon-carbon composite anodes is highly desired but remains a huge challenge for lithium-ion batteries.Herein,we report a unique silicon-carbon composite fabricated by uniformly dis-persing amorphous Si nanodots(SiNDs)in carbon nanospheres(SiNDs/C)that are welded on the wall of the macroporous carbon framework(MPCF)by vertical graphene(VG),labeled as MPCF@VG@SiNDs/C.The high dispersity and amor-phous features of ultrasmall SiNDs(~0.7 nm),the flexible and directed electron/Li+transport channels of VG,and the MPCF impart the MPCF@VG@SiNDs/C more lithium storage sites,rapid Li+transport path,and unique low-strain property during Li+storage.Consequently,the MPCF@VG@SiNDs/C exhibits high cycle stability(1301.4 mAh g^(-1) at 1 A g^(-1) after 1000 cycles without apparent decay)and high rate capacity(910.3 mAh g^(-1),20 A g^(-1))in half cells based on industrial electrode standards.The assembled pouch full cell delivers a high energy density(1694.0 Wh L^(-1);602.8 Wh kg^(-1))and an excellent fast-charging capability(498.5 Wh kg^(-1),charging for 16.8 min at 3 C).This study opens new possibilities for preparing advanced silicon-carbon com-posite anodes for practical applications.
基金supported by the Key Program of the National Natural Science Foundation of China(Grant No.:82130111)the National Natural Science Foundation of China(Grant No.:81803716)+1 种基金the Qi-Huang Chief Scientist Project of the National Administration of Traditional Chinese Medicine,China(2020)the SIMM-SHUTCM Traditional Chinese Medicine Innovation Joint Research Program,China(Grant No.:E2G809H).
文摘Pheretima,also called“earthworms”,is a well-known animal-derived traditional Chinese medicine that is extensively used in over 50 Chinese patent medicines(CPMs)in Chinese Pharmacopoeia(2020 edition).However,its zoological origin is unclear,both in the herbal market and CPMs.In this study,a strategy for integrating in-house annotated protein databases constructed from close evolutionary relationship-sourced RNA sequencing data from public archival resources and various sequencing algorithms(restricted search,open search,and de novo)was developed to characterize the phenotype of natural peptides of three major commercial species of Pheretima,including Pheretima aspergillum(PA),Pheretima vulgaris(PV),and Metaphire magna(MM).We identified 10,477 natural peptides in the PA,7,451 in PV,and 5,896 in MM samples.Five specific signature peptides were screened and then validated using synthetic peptides;these demonstrated robust specificity for the authentication of PA,PV,and MM.Finally,all marker peptides were successfully applied to identify the zoological origins of Brain Heart capsules and Xiaohuoluo pills,revealing the inconsistent Pheretima species used in these CPMs.In conclusion,our integrated strategy could be used for the in-depth characterization of natural peptides of other animal-derived traditional Chinese medicines,especially non-model species with poorly annotated protein databases.
基金supported in part by the National Natural Science Foundation of China(NSFC)(U2031129 and 12003052)Youth Innovation Promotion Association of the Chinese Academy of Sciences(2018079)。
文摘Ground-based optical observation has unique advantages in space target observation.However,due to the weak light-gathering ability of small-aperture optoelectronic observation telescopes,the space debris in the image is weak and easily drowned in noise.In order to solve the above problems,we use digital image processing technology to extract faint space debris.We propose a high detection rate space debris automatic extraction algorithm,aiming to automatically detect space debris.We first establish a new space target description model.Our algorithm is mainly divided into two stages.The purpose of the first stage is to reduce the influence of a large number of stars.We perform wavelet transform and guided filtering for three consecutive frames,and the reconstructed wavelet that takes the median value can achieve the effect of eliminating stars.In the second stage,we adopt the method of robust principal component analysis and attribute the problem of target detection to the problem of separating the target and background of a single frame of image.After a large number of experimental results analysis,it is proved that the algorithm can effectively detect faint debris in the monitoring system of small aperture telescope,and has high precision and low computational complexity.
基金J.Y.H was supported by the National Basic Research Program (973 Program) (No. 2010CB529806), partially by grants from National Nat- ural Science Foundation of China (Grant Nos. 31171064 and 81402903) and Key Research Program of Science and Technology Commissions of Shanghai Municipality (11JC1404300, 13DJ 1400300). L.T. was supported by grants from National Natural Science Foundation of China (Grant Nos. 31371179 and 81300968) and A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Voltage-gated sodium channels (VGSCs) in primary sensory neurons play a key role in transmitting pain signals to the central nervous system. BmK I, a site-3 sodium channel-specific toxin from scorpion Buthus martensi Karsch, induces pain behaviors in rats. How- ever, the subtypes of VGSCs targeted by BmK I were not entirely clear. We therefore investigated the effects of BmK I on the current amplitude, gating and kinetic properties of Nav1.8, which is associated with neuronal hyperexcitability in DRG neurons. It was found that BmK I dose-dependently increased Nav1.8 current in small- sized (〈25 μm) acutely dissociated DRG neurons, which correlated with its inhibition on both fast and slow in- activation. Moreover, voltage-dependent activation and steady-state inactivation curves of Nay1.8 were shifted in a hyperpolarized direction. Thus, BmK I reduced the threshold of neuronal excitability and increased action potential firing in DRG neurons. In conclusion, our data clearly demonstrated that BmK I modulated Nav1.8 re- markably, suggesting BmK I as a valuable probe for studying Nay1.8. And Navl.8 is an important target re- lated to BmK I-evoked pain.
文摘In the process of collating the raw data,the authors noticed an inadvertent mistake occurred in Fig.3b that needs to be corrected after online publication of the article.In Fig.3b,as a result of an error in the graphics panel arrangement process,the band of NEMO was repeatedly inserted asβ-actin by mistake.The correct band is shown as below and in the updated Fig.3b.The correction did not affect any of our results or discussion as present in the original publication.We regret any inconvenience this has caused.
基金supported by grants from the National Key Research and Development Program of China (2021YFF1000202)the National Natural Science Foundation of China (31771368, 31821005,31701397)+3 种基金Ten-thousand Talents Programs of ChinaFundamental Research Funds for the Central Universities (2662020SKPY006)Wuhan Applied Foundational Frontier Project (2020020601012257)Hubei Hongshan Laboratory (2021hszd005),China
文摘Grain chalkiness,an undesirable trait caused by complex factors,has great negative impacts on the quality and economic value of rice.However,little is known about the regulatory mechanism of grain chalkiness,particularly the effect of endoplasmic reticulum(ER)stress.Here,a genome-wide association study(GWAS)reveals that the transcription factor Osb ZIP60 is a vital regulator of rice grain chalkiness.Genetic analysis demonstrates that knockout of Osb ZIP60 results in extremely high grain chalkiness and aberrant structure of storage substances.Notably,the expression of unfolded protein response(UPR)genes,such as OsbZIP50,Os Bi P1,Os Bi P2 and Os Bi P3,is up-regulated in the endosperm cells of osbzip60,and overexpression of all these UPR genes causes various degrees of chalkiness.Furthermore,Osb ZIP60 is found to activate the expression of key genes related to grain chalkiness,such as GPA3,FSE1,FLO7,Chalk5,Os NF-YB1,and Os PK2,whose expression is significantly suppressed in osbzip60 and overexpression lines of Osb ZIP50,Os Bi P1,Os Bi P2,and Os Bi P3.Our study provides novel insights into the function of Osb ZIP60 and the role of the UPR pathway in the formation of grain chalkiness in rice.
基金National Natural Science Foundation of China(61775075)State Key Laboratory of Advanced Optical Communication Systems and Networks,Shanghai Jiao Tong University,China(2019GZKF03005)。
文摘Graphene resting on a silicon-on-insulator platform offers great potential for optoelectronic devices.In the paper,we demonstrate all-optical modulation on the graphene-silicon hybrid waveguides(GSHWs)with tens of micrometers in length.Owing to strong interaction between graphene and silicon strip waveguides with compact light confinement,the modulation depth reaches 22.7%with a saturation threshold down to 1.38 pJ per pulse and a 30-μm-long graphene pad.A response time of 1.65 ps is verified by a pump-probe measurement with an energy consumption of 2.1 pJ.The complementary metal-oxide semiconductor compatible GSHWs with the strip configuration exhibit great potential for ultrafast and broadband all-optical modulation,indicating that employing two-dimensional materials has become a complementary technology to promote the silicon photonic platform.
基金National Natural Science Foundation of China(NSFC)(11474132,61378004,61527823,61605058,61605219)Natural Science Foundation of Jilin Province(20160520085JH)+3 种基金Key Technology Research and Development Project of Jilin Province(20180201120GX)Major Science and Technology Tendering Project of Jilin Province(20170203012GX)Joint Foundation from Equipment Pre-research and Ministry of Education(6141A02022413)Outstanding Young Talent Fund Project of Jilin Province(20180520188JH)
文摘In this paper, we propose and demonstrate an all-fiber passively Q-switched erbium doped fiber laser (EDFL) by using gold nanostars (GNSs) as a saturable absorber (SA) for the first time, to the best of our knowledge. In comparison with other gold nanomorphologies, GNSs have multiple localized surface plasmon resonances, which means that they can be used to construct wideband ultrafast pulse lasers. By inserting the GNS SA into an EDFL cavity pumped by a 980 nm laser diode, a stable passively Q-switched laser at 1564.5 nm was achieved for a threshold pump power of 40 mW. By gradually increasing the pump power from 40 to 120 mW, the pulse duration decreases from 12.8 to 5.3 its and the repetition rate increases from 10 to 17 kHz. Our results indicate that the GNSs are a promising SA for constructing pulse lasers.
基金the National Natural Science Foundation of China(81930112 and 82004089)National Key Research and Development Program of China(No.2018YFC1705900 and 2020YFE0202200)+1 种基金Distinguished professor of Liaoning Province(XLYC2002008)Dalian Science and Technology Leading Talents Project(2019RD15)for financial support.
文摘NEMO/IKKβcomplex is a central regulator of NF-κB signaling pathway,its dissociation has been considered to be an attractive therapeutic target.Herein,using a combined strategy of molecular pharmacological phenotyping,proteomics and bioinformatics analysis,Shikonin(SHK)is identified as a potential inhibitor of the IKKβ/NEMO complex.It destabilizes IKKβ/NEMO complex with IC_(50) of 174 nM,thereby significantly impairing the proliferation of colorectal cancer cells by suppressing the NF-κB pathway in vitro and in vivo.In addition,we also elucidated the potential target sites of SHK in the NEMO/IKKβcomplex.Our study provides some new insights for the development of potent small-molecule PPI inhibitors.
基金This study was supported by the State Key Program of National Natural Science Foundation of China(41730748)National Natural Science Foundation of China(41601299,41977073,41671287)+1 种基金Youth Innovation Promotion Association of CAS(2020359)CAS Interdisciplinary Innovation Team,and the Youth Innovation Team Project of ISA,CAS(2017QNCXTD_XXL).
文摘Due to the complex hydrogeological conditions in karst regions,it is difficult to measure sediment source contributions at a catchment scale directly.The objective of this study was to quantify the relative contributions of sediment sources and their temporal variability in a karst catchment in southwest China.Karst depressions can trap eroded sediment similar to a dam or reservoir and,thus,are representative and typical test beds for identifying sediment sources in karst regions.Three sediment cores were taken from a karst depression,58 soil samples from three potential sediment sources were collected,and 18 soil properties were analyzed.The relative contributions of cropland,forestland,and fissure or crack soils were calculated using a multivariate mixing model.The fingerprinting results demonstrated that the cropland was the main sediment source in karst catchment.Specifically,according to the mean sediment contributions of the three deposited sediment cores,the sediment contribution from cropland topsoil was 69.3%,varying from 46.9%to 92.3%,and forestland soil and crack soil accounted for 8.6%and 22.1%of the sediment yield,and varying from 2.8%to 16.5%and 4.8%-36.6%,respectively.This result indicated that great attention should be paid when using only a single core to quantify sediment provenance.Due to the deposited sediment was generally disturbed as cropland in the karst depression,the area that has not been disturbed in recent decades in depression was more appropriate to trace sediment sources in karst catchment.To the best of our knowledge,this study was the first to quantify the contributions of sediment sources in the karst catchment of southwest China.This study provides valuable information and a preliminary reference for applying a composite fingerprinting technique to quantify sediment sources in karst catchments.
基金Authors gratefully acknowledge the supports of the National Science Foundation of China(NSFC Nos.51102173 and 51472169).
文摘Here,we developed one kind of novel TiO_(2) ceramics with colossal dielectric constant by chemical modifications(Bi^(3+) and Sb^(5+)),and discussed the physical origin for giant dielectric constant.Effects of Bi and/or Sb on their microstructure,dielectric properties as well as its frequency and temperature stability were studied in detail.It was found that their dielectric properties are strongly sensitive to(Bi,Sb)contents,and colossal dielectric permittivity(CP)(10^(4)~10^(5))together with low dielectric loss(~5.7%)can be obtained in a wide composition range.In addition,all the ceramics possessed good frequency(10^(2)~10^(6)Hz)and temperature(-150-200℃)stability of dielectric properties.In addition,the defects caused by the Bi volatilization may be the reason for higher dielectric properties of(Bi_(0.5)Sb_(0.5))_(x)Ti_(1-x)O_(2) ceramics with respect to(A_(0.5)Sb_(0.5))_(x)Ti_(1-x)O_(2)(A=In,Pr,Dy,Sm,Gd,Yb,Ga,Al,Fe or Sc).According to the results of complex impedance and XPS,the electron-pinned defect-dipoles may be suitable to explain the CP phenomenon,and oxygen vacancies-induced by Bi^(3+)&Sb^(5+) substitution for Ti^(4+) should be responsible for conduction mechanism.We believe that this profound investigation can benefit the development of TiO_(2) ceramics as a CP material.
文摘Beijing Daxing International Airport,a major landmark project in China and a new driver for national development,will represent the direction for the development of civil aviation airports in China.The airport,situated in the junction of Nangezhuang,Daxing District,Beijing City and Gu’an County,Hebei Province,has seen its north terminal area and north terminal built in the first phase,covering a total construction area of about 1.4 million m2.The north terminal area is designed to have an annual throughput of 45 million passengers.