The thermal structure of the lower mantle plays a key role in understanding the dynamic processes of the Earth's evolution and mantle convection.Because intrinsic attenuation in the lower mantle is highly sensitiv...The thermal structure of the lower mantle plays a key role in understanding the dynamic processes of the Earth's evolution and mantle convection.Because intrinsic attenuation in the lower mantle is highly sensitive to temperature,determining of the attenuation of the lower mantle could help us determine its thermal state.We attempted to constrain the attenuation of the lower mantle by measuring the amplitude ratios of p to ScP on the vertical component and s to ScS on the tangential component at short epicentral distances for seismic wave data from deep earthquakes in Northeast China.We calculated the theoretical amplitude ratios of p to ScP and s to ScS by using ray theory and the axial-symmetric spectral element method AxiSEM,as well as by considering the effects of radiation patterns,geometrical spreading,and ScP reflection coefficients.By comparing the observed amplitude ratios with the synthetic results,we constrained the quality factors as Qα≈3,000 and Qβ≈1,300 in the lower mantle beneath Northeast China,which are much larger than those in the preliminary reference Earth model(PREM)model of Qα~800 and Qβ~312.We propose that the lower mantle beneath Northeast China is relatively colder than the average mantle,resulting in weaker intrinsic attenuation and higher velocity.We estimated the temperature of the lower mantle beneath Northeast China as approximately 300–700 K colder than the global average value.展开更多
Additive manufacturing,particularly 3D printing,has revolutionized the manufacturing industry by allowing the production of complex and intricate parts at a lower cost and with greater efficiency.However,3D-printed pa...Additive manufacturing,particularly 3D printing,has revolutionized the manufacturing industry by allowing the production of complex and intricate parts at a lower cost and with greater efficiency.However,3D-printed parts frequently require post-processing or integration with other machining technologies to achieve the desired surface finish,accuracy,and mechanical properties.Ultra-precision machining(UPM)is a potential machining technology that addresses these challenges by enabling high surface quality,accuracy,and repeatability in 3D-printed components.This study provides an overview of the current state of UPM for 3D printing,including the current UPM and 3D printing stages,and the application of UPM to 3D printing.Following the presentation of current stage perspectives,this study presents a detailed discussion of the benefits of combining UPM with 3D printing and the opportunities for leveraging UPM on 3D printing or supporting each other.In particular,future opportunities focus on cutting tools manufactured via 3D printing for UPM,UPM of 3D-printed components for real-world applications,and post-machining of 3D-printed components.Finally,future prospects for integrating the two advanced manufacturing technologies into potential industries are discussed.This study concludes that UPM is a promising technology for 3D-printed components,exhibiting the potential to improve the functionality and performance of 3D-printed products in various applications.It also discusses how UPM and 3D printing can complement each other.展开更多
Although the Sichuan basin is a stable block with low historical seismicity,the Suining M5.0 earthquake on January31,2010 occurred near the center of the basin,causing casualty and substantial damage.Previous studies ...Although the Sichuan basin is a stable block with low historical seismicity,the Suining M5.0 earthquake on January31,2010 occurred near the center of the basin,causing casualty and substantial damage.Previous studies have shown that the earthquake is very shallow and may occur in the sedimentary cover rocks,but its causative fault has not been identified.Based on local broadband seismic waveform data as well as a pair of ALOS PALSAR ascending orbit data,we explore the seismogenic mechanism via further constraining the source depth and the ruptured fault.The earthquake caused ground uplift in the southeast of the epicenter area,with a maximum line of sight displacement of about 13.6 cm,much larger than the displacement caused by a M5 earthquake at a typical depth of 10 km,which indicates that the earthquake is very shallow.Through joint inversion of seismic waveform and InSAR data,we obtain the moment magnitude of Suining earthquake as MW4.5,with the strike,dip,and rake of its fault plane as 17°,66° and 90°,respectively,and the centroid depth less than 1 km,supporting that the earthquake occurred at the shallow part of a high angle thrust fault dipping to the southeast.It is further confirmed that the earthquake may be triggered by the diffusion of high-pressure fluid migrating from the underside gas reservoir.展开更多
Arbitrary manipulation of broadband terahertz waves with flexible polarization shaping at the source has great potential in expanding numerous applications,such as imaging,information encryption,and all-optical cohere...Arbitrary manipulation of broadband terahertz waves with flexible polarization shaping at the source has great potential in expanding numerous applications,such as imaging,information encryption,and all-optical coherent control of terahertz nonlinear phenomena.Topological insulators featuring unique spinmomentum-locked surface state have already exhibited very promising prospects in terahertz emission,detection,and modulation,which may lay a foundation for future on-chip topological insulator-based terahertz systems.However,polarization-shaped terahertz emitters based on topological insulators with an arbitrarily manipulated temporal evolution of the amplitude and the electric-field vector direction have not yet been explored.We systematically investigated the terahertz radiation from topological insulator Bi2Te3 nanofilms driven by femtosecond laser pulses and successfully realized the generation of efficient chiral terahertz waves with controllable chirality,ellipticity,and principal axis.The convenient engineering of the chiral terahertz waves was interpreted by a photogalvanic effect(PGE)-induced photocurrent,while the linearly polarized terahertz waves originated from linear PGE-induced shift currents.Our work not only provides further understanding of femtosecond coherent control of ultrafast spin currents but also describes an effective way to generate spin-polarized terahertz waves at the source.展开更多
We systematically investigate the influences of the input infrared spectrum, chirp, and polarization on the emitted intense terahertz spectrum and spatial dispersion in lithium niobate via optical rectification. The t...We systematically investigate the influences of the input infrared spectrum, chirp, and polarization on the emitted intense terahertz spectrum and spatial dispersion in lithium niobate via optical rectification. The terahertz yield and emission spectrum depend on both the chirp and spectrum of the input pump laser pulses. We also observe slight non-uniform spatial dispersion using a knife-edge measurement, which agrees well with the original predictions. The possible mechanism is the nonlinear distortion effect caused by high-energy laser pumping.Our study is very important and useful for developing intense terahertz systems with applications in extreme terahertz sciences and nonlinear phenomena.展开更多
Currently,there is no effective drugs for treating clinically COVID-19 except dexamethasone.We previously revealed that human identical sequences of SARS-CoV-2 promote the COVID-19 progression by upregulating hyaluron...Currently,there is no effective drugs for treating clinically COVID-19 except dexamethasone.We previously revealed that human identical sequences of SARS-CoV-2 promote the COVID-19 progression by upregulating hyaluronic acid(HA).As the inhibitor of HA synthesis,hymecromone is an approved prescription drug used for treating biliary spasm.Here,we aimed to investigate the relation between HA and COVID-19,and evaluate the therapeutic effects of hymecromone on COVID-19.Firstly,HA was closely relevant to clinical parameters,including lymphocytes(n=158;r=−0.50;P<0.0001),C-reactive protein(n=156;r=0.55;P<0.0001),D-dimer(n=154;r=0.38;P<0.0001),and fibrinogen(n=152;r=0.37;P<0.0001),as well as the mass(n=78;r=0.43;P<0.0001)and volume(n=78;r=0.41;P=0.0002)of ground-glass opacity,the mass(n=78;r=0.48;P<0.0001)and volume(n=78;r=0.47;P<0.0001)of consolidation in patient with low level of hyaluronan(HA<48.43 ng/mL).Furthermore,hyaluronan could directly cause mouse pulmonary lesions.Besides,hymecromone remarkably reduced HA via downregulating HAS2/HAS3 expression.Moreover,89%patients with hymecromone treatment had pulmonary lesion absorption while only 42%patients in control group had pulmonary lesion absorption(P<0.0001).In addition,lymphocytes recovered more quickly in hymecromone-treated patients(n=8)than control group(n=5)(P<0.05).These findings suggest that hymecromone is a promising drug for COVID-19 and deserves our further efforts to determine its effect in a larger cohort.展开更多
Dear Editor,Aberrant DNA methylation gets involved in cancer initiation,progression,and recurrence,which in turn makes it an ideal cancer biomarker.Various methylation markers or their panels have been developed in di...Dear Editor,Aberrant DNA methylation gets involved in cancer initiation,progression,and recurrence,which in turn makes it an ideal cancer biomarker.Various methylation markers or their panels have been developed in diverse cancer types.However,the model-constructing based marker mining strategy and incompatibility of application have greatly impeded their ways to clinic.Thus,single methylation marker applicable to all/most cancer types and multiple clinical scenarios is desperately needed.The hope came from the unexpected observation that HIST1H4F was universally hypermethylated in all 17 cancer types;thus,we raised the concept of“Universal Cancer Only Marker(UCOM)”and established a paradigm for discovery and clinical application of UCOM.1 Recently,a novel UCOM,hypermethylated PCDHGB7,was identified and found to advance cervical cancer(CC)screening to the precancerous stage.2 During the screening of UCOM,we discerned a bunch of cancer cell-differentially methylated regions.1 Among them,sine oculis(SIX)homeobox family of transcription factors,which were found to function as tumorigenesis regulator by promoting epithelial-to-mesenchymal transition and metastasis recently in addition to their traditional roles in tissue formation and organogenesis,3 sparked our special attention.Herein,we interrogate whether SIX6 methylation could serve as a novel UCOM and its potential applications.展开更多
We propose a spatial diffraction diagnostic method via inserting a millimeter-gap double slit into the collimated terahertz beam to monitor the minute variation of the terahertz beam in strong-field terahertz sources,...We propose a spatial diffraction diagnostic method via inserting a millimeter-gap double slit into the collimated terahertz beam to monitor the minute variation of the terahertz beam in strong-field terahertz sources,which is difficult to be resolved in conventional terahertz imaging systems.To verify the method,we intentionally fabricate tiny variations of the terahertz beam through tuning the iris for the infrared pumping beam before the tilted-pulse-front pumping setups.The phenomena can be well explained by the theory based on the tilted-pulse-front technique and terahertz diffraction.展开更多
We systematically study the optimization of highly efficient terahertz（THz） generation in lithium niobate（LN）crystal pumped by 800 nm laser pulses with 30 fs pulse duration. At room temperature, we obtain a record...We systematically study the optimization of highly efficient terahertz（THz） generation in lithium niobate（LN）crystal pumped by 800 nm laser pulses with 30 fs pulse duration. At room temperature, we obtain a record optical-to-THz energy conversion efficiency of 0.43% by chirping the pump laser pulses. Our method provides a new technique for producing millijoule THz radiation in LN via optical rectification driven by joule-level Ti：sapphire laser systems, which deliver sub-50-fs pulse durations.展开更多
基金supported by funding from the National Natural Science Foundation of China (grant no. 41904061)China Postdoctoral Science Foundation (grant no. 2018M640742)
文摘The thermal structure of the lower mantle plays a key role in understanding the dynamic processes of the Earth's evolution and mantle convection.Because intrinsic attenuation in the lower mantle is highly sensitive to temperature,determining of the attenuation of the lower mantle could help us determine its thermal state.We attempted to constrain the attenuation of the lower mantle by measuring the amplitude ratios of p to ScP on the vertical component and s to ScS on the tangential component at short epicentral distances for seismic wave data from deep earthquakes in Northeast China.We calculated the theoretical amplitude ratios of p to ScP and s to ScS by using ray theory and the axial-symmetric spectral element method AxiSEM,as well as by considering the effects of radiation patterns,geometrical spreading,and ScP reflection coefficients.By comparing the observed amplitude ratios with the synthetic results,we constrained the quality factors as Qα≈3,000 and Qβ≈1,300 in the lower mantle beneath Northeast China,which are much larger than those in the preliminary reference Earth model(PREM)model of Qα~800 and Qβ~312.We propose that the lower mantle beneath Northeast China is relatively colder than the average mantle,resulting in weaker intrinsic attenuation and higher velocity.We estimated the temperature of the lower mantle beneath Northeast China as approximately 300–700 K colder than the global average value.
基金supported by the National Natural Science Foundation of China(52202102,51972180)the Natural Science Foundation of Shandong Province(ZR2019BB030,ZR2020ME082)+3 种基金the Science and Technology Support Plan for Youth Innovation of Colleges and Universities of Shandong Province(2021KJ056)the Science Fund of Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai(AMGM2023F13,AMGM2021F05)the Undergraduate Training Program on Innovation and Entrepreneurship of Shandong Province(S202210431016)the Science,Education and Industry Integration of Basic Research Projects of Qilu University of Technology(2023PY022)。
基金supported by the State Key Laboratories in Hong Kong,China,from the Innovation and Technology Commission(project code:BBR3)of the Government of the Hong Kong Special Administrative Region,Chinathe Research Office(project codes:BBXM and BBX)of The Hong Kong Polytechnic University,China+1 种基金the Project of Strategic Importance(project codes:1-ZE0G and SBBD)of The Hong Kong Polytechnic University,Chinaand the Research Committee(project code:RMAC)of The Hong Kong Polytechnic University,China。
文摘Additive manufacturing,particularly 3D printing,has revolutionized the manufacturing industry by allowing the production of complex and intricate parts at a lower cost and with greater efficiency.However,3D-printed parts frequently require post-processing or integration with other machining technologies to achieve the desired surface finish,accuracy,and mechanical properties.Ultra-precision machining(UPM)is a potential machining technology that addresses these challenges by enabling high surface quality,accuracy,and repeatability in 3D-printed components.This study provides an overview of the current state of UPM for 3D printing,including the current UPM and 3D printing stages,and the application of UPM to 3D printing.Following the presentation of current stage perspectives,this study presents a detailed discussion of the benefits of combining UPM with 3D printing and the opportunities for leveraging UPM on 3D printing or supporting each other.In particular,future opportunities focus on cutting tools manufactured via 3D printing for UPM,UPM of 3D-printed components for real-world applications,and post-machining of 3D-printed components.Finally,future prospects for integrating the two advanced manufacturing technologies into potential industries are discussed.This study concludes that UPM is a promising technology for 3D-printed components,exhibiting the potential to improve the functionality and performance of 3D-printed products in various applications.It also discusses how UPM and 3D printing can complement each other.
基金supported by the National Natural Science Foundation of China (Grant Nos. 42030311, 41874068, 41974009)。
文摘Although the Sichuan basin is a stable block with low historical seismicity,the Suining M5.0 earthquake on January31,2010 occurred near the center of the basin,causing casualty and substantial damage.Previous studies have shown that the earthquake is very shallow and may occur in the sedimentary cover rocks,but its causative fault has not been identified.Based on local broadband seismic waveform data as well as a pair of ALOS PALSAR ascending orbit data,we explore the seismogenic mechanism via further constraining the source depth and the ruptured fault.The earthquake caused ground uplift in the southeast of the epicenter area,with a maximum line of sight displacement of about 13.6 cm,much larger than the displacement caused by a M5 earthquake at a typical depth of 10 km,which indicates that the earthquake is very shallow.Through joint inversion of seismic waveform and InSAR data,we obtain the moment magnitude of Suining earthquake as MW4.5,with the strike,dip,and rake of its fault plane as 17°,66° and 90°,respectively,and the centroid depth less than 1 km,supporting that the earthquake occurred at the shallow part of a high angle thrust fault dipping to the southeast.It is further confirmed that the earthquake may be triggered by the diffusion of high-pressure fluid migrating from the underside gas reservoir.
基金This work was supported by Beijing Natural Science Foundation(Grant No.4194083)the National Natural Science Foundation of China(Grant Nos.61905007,61774013,11827807,and 61731001)+3 种基金the National Key R&D Program of China(Grant Nos.2019YFB2203102 and 2018YFB0407602)the International Collaboration Project(Grant No.B16001)the National Key Technology Program of China(Grant No.2017ZX01032101)the Open Project Program of Wuhan National Laboratory for Optoelectronics(Grant No.2018WNLOKF001).
文摘Arbitrary manipulation of broadband terahertz waves with flexible polarization shaping at the source has great potential in expanding numerous applications,such as imaging,information encryption,and all-optical coherent control of terahertz nonlinear phenomena.Topological insulators featuring unique spinmomentum-locked surface state have already exhibited very promising prospects in terahertz emission,detection,and modulation,which may lay a foundation for future on-chip topological insulator-based terahertz systems.However,polarization-shaped terahertz emitters based on topological insulators with an arbitrarily manipulated temporal evolution of the amplitude and the electric-field vector direction have not yet been explored.We systematically investigated the terahertz radiation from topological insulator Bi2Te3 nanofilms driven by femtosecond laser pulses and successfully realized the generation of efficient chiral terahertz waves with controllable chirality,ellipticity,and principal axis.The convenient engineering of the chiral terahertz waves was interpreted by a photogalvanic effect(PGE)-induced photocurrent,while the linearly polarized terahertz waves originated from linear PGE-induced shift currents.Our work not only provides further understanding of femtosecond coherent control of ultrafast spin currents but also describes an effective way to generate spin-polarized terahertz waves at the source.
基金National Basic Research Program of China(2013CBA01501)National Natural Science Foundation of China(NSFC)(11334013,11520101003,11861121001,U1530150)+4 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(CAS)(XDB07030300,XDB16010200,XDB17030500)National Science Foundation(NSF)(0968895,1102301,1263236)863 Program(2013AA014402)“Zhuoyue” Program(ZG216S1807)“Qingba” Program(KG12052501,ZG226S1832)
文摘We systematically investigate the influences of the input infrared spectrum, chirp, and polarization on the emitted intense terahertz spectrum and spatial dispersion in lithium niobate via optical rectification. The terahertz yield and emission spectrum depend on both the chirp and spectrum of the input pump laser pulses. We also observe slight non-uniform spatial dispersion using a knife-edge measurement, which agrees well with the original predictions. The possible mechanism is the nonlinear distortion effect caused by high-energy laser pumping.Our study is very important and useful for developing intense terahertz systems with applications in extreme terahertz sciences and nonlinear phenomena.
基金the National Key R&D Program of China(2018YFC1005004)Major Special Projects of Basic Research of Shanghai Science and Technology Commission(18JC1411101)+1 种基金National Natural Science Foundation of China(31872814,32000505)Shanghai Science and Technology Innovation Action Plan,Medical Innovation Research Special Project(20Z11900900).
文摘Currently,there is no effective drugs for treating clinically COVID-19 except dexamethasone.We previously revealed that human identical sequences of SARS-CoV-2 promote the COVID-19 progression by upregulating hyaluronic acid(HA).As the inhibitor of HA synthesis,hymecromone is an approved prescription drug used for treating biliary spasm.Here,we aimed to investigate the relation between HA and COVID-19,and evaluate the therapeutic effects of hymecromone on COVID-19.Firstly,HA was closely relevant to clinical parameters,including lymphocytes(n=158;r=−0.50;P<0.0001),C-reactive protein(n=156;r=0.55;P<0.0001),D-dimer(n=154;r=0.38;P<0.0001),and fibrinogen(n=152;r=0.37;P<0.0001),as well as the mass(n=78;r=0.43;P<0.0001)and volume(n=78;r=0.41;P=0.0002)of ground-glass opacity,the mass(n=78;r=0.48;P<0.0001)and volume(n=78;r=0.47;P<0.0001)of consolidation in patient with low level of hyaluronan(HA<48.43 ng/mL).Furthermore,hyaluronan could directly cause mouse pulmonary lesions.Besides,hymecromone remarkably reduced HA via downregulating HAS2/HAS3 expression.Moreover,89%patients with hymecromone treatment had pulmonary lesion absorption while only 42%patients in control group had pulmonary lesion absorption(P<0.0001).In addition,lymphocytes recovered more quickly in hymecromone-treated patients(n=8)than control group(n=5)(P<0.05).These findings suggest that hymecromone is a promising drug for COVID-19 and deserves our further efforts to determine its effect in a larger cohort.
基金supported by National Key R&D Program of China(Grant No.2018YFC1005004)the National Natural Science Foundation of China(Grant No.31872814,32000505)the Major Special Projects of Basic Research of Shanghai Science and Technology Commission(Grant No.18JC1411101)。
文摘Dear Editor,Aberrant DNA methylation gets involved in cancer initiation,progression,and recurrence,which in turn makes it an ideal cancer biomarker.Various methylation markers or their panels have been developed in diverse cancer types.However,the model-constructing based marker mining strategy and incompatibility of application have greatly impeded their ways to clinic.Thus,single methylation marker applicable to all/most cancer types and multiple clinical scenarios is desperately needed.The hope came from the unexpected observation that HIST1H4F was universally hypermethylated in all 17 cancer types;thus,we raised the concept of“Universal Cancer Only Marker(UCOM)”and established a paradigm for discovery and clinical application of UCOM.1 Recently,a novel UCOM,hypermethylated PCDHGB7,was identified and found to advance cervical cancer(CC)screening to the precancerous stage.2 During the screening of UCOM,we discerned a bunch of cancer cell-differentially methylated regions.1 Among them,sine oculis(SIX)homeobox family of transcription factors,which were found to function as tumorigenesis regulator by promoting epithelial-to-mesenchymal transition and metastasis recently in addition to their traditional roles in tissue formation and organogenesis,3 sparked our special attention.Herein,we interrogate whether SIX6 methylation could serve as a novel UCOM and its potential applications.
基金the Science Challenge Project(No.TZ2016005)the NationalNatural Science Foundation of China(Nos.11827807,61905007,11520101003,and 11861121001)the Strategic Priority Research Programof the Chinese Academy of Sciences(No.XDB16010200)。
文摘We propose a spatial diffraction diagnostic method via inserting a millimeter-gap double slit into the collimated terahertz beam to monitor the minute variation of the terahertz beam in strong-field terahertz sources,which is difficult to be resolved in conventional terahertz imaging systems.To verify the method,we intentionally fabricate tiny variations of the terahertz beam through tuning the iris for the infrared pumping beam before the tilted-pulse-front pumping setups.The phenomena can be well explained by the theory based on the tilted-pulse-front technique and terahertz diffraction.
基金supported by the National Basic Research Program of China(No.2013CBA01501)the National Natural Science Foundation of China(No.11520101003)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDB16010200 and XDB07030300)the "Zhuoyue" Program of Beihang University(No.GZ216S1711)
文摘We systematically study the optimization of highly efficient terahertz（THz） generation in lithium niobate（LN）crystal pumped by 800 nm laser pulses with 30 fs pulse duration. At room temperature, we obtain a record optical-to-THz energy conversion efficiency of 0.43% by chirping the pump laser pulses. Our method provides a new technique for producing millijoule THz radiation in LN via optical rectification driven by joule-level Ti：sapphire laser systems, which deliver sub-50-fs pulse durations.
