The side reaction between the active material and liquid-electrolyte cause structural damage and particle pulverization is one of the important factors leading to the capacity decay of LiNi0.80Co0.15Al0.05O2(NCA)mater...The side reaction between the active material and liquid-electrolyte cause structural damage and particle pulverization is one of the important factors leading to the capacity decay of LiNi0.80Co0.15Al0.05O2(NCA)materials in Li ion batteries(LIBs).Surface modification is an effective strategy for NCA cathodes,which could alleviate the degradation associated with surface processes.Herein,a surface structure rearrangement of NCA cathode secondary particles was reported by in-situ forming a solid electrolyte LiBO2.The LiBO2 is beneficial for alleviating the stress during charge/discharge process,thereby slowing down the rate of cracks formation in the secondary particles,which facilitates the Li+de-intercalation as well as prevents penetration of the liquid-electrolyte into the interior of the particles.As a result,the surface structure rearrangement NCA(RS-NCA)delivers a high discharge capacity of 202.5 m Ah g^-1 at 0.1 C,and exhibits excellent cycle stability with discharge capacity retaining 148 m Ah g^-1 after 200 cycles at 2 C.This surface structure rearrangement approach provides a new viewpoint in designing high-performance high-voltage LIBs.展开更多
Inductance asymmetry,which is brought by inherent asymmetric parameters,manufacture tolerance,winding fault,cables with unequal lengths,etc.,of permanent-magnet synchronous machines(PMSMs)can cause current harmonics a...Inductance asymmetry,which is brought by inherent asymmetric parameters,manufacture tolerance,winding fault,cables with unequal lengths,etc.,of permanent-magnet synchronous machines(PMSMs)can cause current harmonics and inaccurate position estimation.This paper proposes an enhanced fundamental model based sensorless control strategy for PMSMs with asymmetric inductances.The proportional-integral-resonant current regulator is introduced to reduce the second-order harmonics of currents,but there are still negative sequence components in the estimated back-electromotive forces(EMFs),which can cause the position estimated error.Differing from conventional methods in which negative sequences are filtered out before the phase-locked loop(PLL)module,the proposed method directly applies the estimated back-EMF with negative sequences as the reference input of PLL.An improved PLL with a bi-quad filter is proposed to attenuate the arising second harmonic position error and heighten the steady-state accuracy.Then,this position error is used for asymmetric inductance identification and its result is utilized to update the observer model.Furthermore,the dynamic performance is improved by the output limitation on the bi-quad filter as well as the implementation of a fast-locking technique in the PLL.The effectiveness of the proposed scheme is verified by experimental results.展开更多
Objective:The spectrum and risk of cancer in relatives of BRCA1/2 pathogenic variant carriers in the Chinese population have not been established.Methods:A family history of cancer in 9903 unselected breast cancer pat...Objective:The spectrum and risk of cancer in relatives of BRCA1/2 pathogenic variant carriers in the Chinese population have not been established.Methods:A family history of cancer in 9903 unselected breast cancer patients was retrospectively analyzed.BRCA1/2 status was determined for all patients and relative risks(RRs)were calculated to evaluate cancer risk in relatives of the patients.Results:The incidences of breast cancer in female relatives of BRCA1 carriers,BRCA2 carriers,and non-carriers were 33.0%,32.2%,and 7.7%,respectively.The corresponding incidences of ovarian cancer were 11.5%,2.4%,and 0.5%,respectively.The incidences of pancreatic cancer in male relatives of BRCA1 carriers,BRCA2 carriers,and non-carriers were 1.4%,2.7%,and 0.6%,respectively.The corresponding incidences of prostate cancer were 1.0%,2.1%,and 0.4%,respectively.The risks of breast and ovarian cancers in female relatives of BRCA1 and BRCA2 carriers were significantly higher than female relatives of non-carriers(BRCA1:RR=4.29,P<0.001 and RR=21.95,P<0.001;BRCA2:RR=4.19,P<0.001 and RR=4.65,P<0.001,respectively).Additionally,higher risks of pancreatic and prostate cancers were noted in male relatives of BRCA2 carriers than non-carriers(RR=4.34,P=0.001 and RR=4.86,P=0.001,respectively).Conclusions:Female relatives of BRCA1 and BRCA2 carriers are at increased risk for breast and ovarian cancers,and male relatives of BRCA2 carriers are at increased risk for pancreatic and prostate cancers.展开更多
In the realm of proton exchange membrane fuel cells(PEMFCs),the bipolar plates(BPs)are indispensable and serve pivotal roles in distributing reactant gases,collecting current,facilitating product water removal,and coo...In the realm of proton exchange membrane fuel cells(PEMFCs),the bipolar plates(BPs)are indispensable and serve pivotal roles in distributing reactant gases,collecting current,facilitating product water removal,and cooling the stack.Metal BPs,characterized by outstanding manufacturability,cost-effectiveness,higher power density,and mechanical strength,are emerging as viable alternatives to traditional graphite BPs.The foremost challenge for metal BPs lies in enhancing their corrosion resistance and conductivity under acidic conditions,necessitating the application of various coatings on their surfaces to ensure superior performance.This review summarizes and compares recent advancements in the research of eight distinct types of coatings for BPs in PEMFCs,including noble metal,carbide,ni-tride,and amorphous carbon(a-C)/metal compound composite coatings.The various challenges encountered in the manufacturing and fu-ture application of these coatings are also delineated.展开更多
Using 9943 OB-type stars from LAMOST DR7 in the solar neighborhood,we fit the vertical stellar density profile with the model including a single exponential distribution at different positions(R,Φ).The distributions ...Using 9943 OB-type stars from LAMOST DR7 in the solar neighborhood,we fit the vertical stellar density profile with the model including a single exponential distribution at different positions(R,Φ).The distributions of the scale heights and scale length show that the young disk traced by the OB-type stars is not axisymmetric.The scale length decreases versus the azimuthal angleΦ,i.e.,from.■kpc withΦ=-3°to■kpc withΦ=9°.Meanwhile we find signal of non-symmetry in the distribution of the scale height of the north and south of the disk plane.The scale height in the north side shows signal of flaring of the disk,while that of the south disk stays almost constant around h_(s)=130 pc.The distribution of the displaceeent of the disk plane Z_(0)also shows variance versus the azimuthal angleΦ,which displays significant differences with the warp model constrained by the Cepheid stars.We also test different values for the position of the Sun,and the distance between the Sun and the Galactic center affects the scale heights and the displacement of the disk significantly,but that does not change our conclusion that the disk is not axisymmetric.展开更多
Boost-Buck converter is widely used in LED lighting drivers. In this paper, Boost-Buck main circuit related characteristics are firstly discussed, and then a new Boost-Buck high power efficient double loop control str...Boost-Buck converter is widely used in LED lighting drivers. In this paper, Boost-Buck main circuit related characteristics are firstly discussed, and then a new Boost-Buck high power efficient double loop control strategy is built by adopting error amplifier and integrator control method. It is demonstrated that the new system has many advantages such as high efficiency, fast response, strong anti-interference, good stability after analyses and simulations of its working dynamic characteristics.展开更多
Iron oxide(Fe_(2)O_(3))emerges as a highly attractive anode candidate among rapidly expanding energy storage market.Nonethe-less,its considerable volume changes during cycling as an electrode material result in a vast...Iron oxide(Fe_(2)O_(3))emerges as a highly attractive anode candidate among rapidly expanding energy storage market.Nonethe-less,its considerable volume changes during cycling as an electrode material result in a vast reduced battery cycle life.In this work,an ap-proach is pioneered for preparing high-performance Fe_(2)O_(3)anode materials,by innovatively synthesizing a triple-layer yolk-shell Fe_(2)O_(3)uniformly coated with a conductive polypyrrole(Ppy)layer(Fe_(2)O_(3)@Ppy-TLY).The uniform polypyrrole coating introduces more reac-tion sites and adsorption sites,and maintains structure stability through charge-discharge process.In the uses as lithium-ion battery elec-trodes,Fe_(2)O_(3)@Ppy-TLY demonstrates high reversible specific capacity(maintaining a discharge capacity of 1375.11 mAh·g^(−1)after 500 cycles at 1 C),exceptional cycling stability(retaining the steady charge-discharge performance at 544.33 mAh·g^(−1)after 6000 ultrafast charge-discharge cycles at a 10 C current density),and outstanding high current charge-discharge performance(retaining a reversible ca-pacity of 156.75 mAh·g^(−1)after 10000 cycles at 15 C),thereby exhibiting superior lithium storage performance.This work introduces in-novative advancements for Fe_(2)O_(3)anode design,aiming to enhance its performance in energy storage fields.展开更多
Tin sulfide(SnS_(2))anodes have garnered significant attention within emerging energy storage technologies.However,the application of SnS_(2)is curtailed due to its inherent limitations,including poor cyclic stability...Tin sulfide(SnS_(2))anodes have garnered significant attention within emerging energy storage technologies.However,the application of SnS_(2)is curtailed due to its inherent limitations,including poor cyclic stability and inevitable volumetric expansion upon cycling.This study reports the successful fabrication of an innovative SnS_(2)-based composite,featuring an eggshell-like structured nitrogen-doped carbon coating,referred to as SnS_(2)@NxC.This novel architecture,wherein SnS_(2)acts as the core encapsulated by a nitrogen-doped carbon shell,characterized by a void space between the shell and core,is crucial in mitigating volumetric expansion.This configuration contributes to maintaining the structural integrity of the composite materials,even under the stresses of continuous cycling.Nitrogen within the carbon matrix enhances conductivity and promotes the formation of a more robust and stable solid electrolyte interphase(SEI)layer.Experimental investigations have substantiated the electrochemical superiority of the SnS_(2)@NxC electrode,demonstrating a specific capacity of 701.8 mA·h·g^(-1)after 1000 cycles at 0.5 A·g^(-1)and maintaining a capacity of 597.2mA·h·g^(-1)after 400 cycles at a heightened current density of 2 A·g^(-1).These findings underscore the exceptional cyclic performance and durability of the SnS_(2)@NxC electrode.展开更多
The authors regret that the printed version of the above article contained some errors.The funding number in acknowledgments of this paper was incorrectly marked,and we hope to correct it.We thank the National Natural...The authors regret that the printed version of the above article contained some errors.The funding number in acknowledgments of this paper was incorrectly marked,and we hope to correct it.We thank the National Natural Science Foundation of China(51764048,51703118 and 51474191),Yunnan Province Thousand Youth Talents Plan,the Application Basis Research Project of Yunnan Province Science and Technology Department(2017FD144)and Key Natural Science Foundation of Yunnan Province China(2018FA28)for providing the financial support.展开更多
The article investigates the optimal energy management(OEM)problem for microgrids.To figure out the problem in fixed time and alleviate communication load with limited resources,this article devises a novel fixed-time...The article investigates the optimal energy management(OEM)problem for microgrids.To figure out the problem in fixed time and alleviate communication load with limited resources,this article devises a novel fixed-time stability lemma and an event-triggered(ET)fixed-time distributed OEM approach.Using Lyapunov stability theory,the distributed approach has been proven to converge in fixed time and the upper bound on convergence time can be derived without dependence on the initial states.The dynamic ET method is raised to dynamically adjust the triggering threshold and reduce communication redundancy.In addition,Zeno behavior is avoided.Simulations are given to show the effectiveness and advantage of the designed distributed OEM method.展开更多
The inherent stability and durability of polystyrene(PS)make it a valuable material but also complicate its chemical recycling.Oxidative degradation via hydrogen atom transfer(HAT)is a promising route for PS recovery,...The inherent stability and durability of polystyrene(PS)make it a valuable material but also complicate its chemical recycling.Oxidative degradation via hydrogen atom transfer(HAT)is a promising route for PS recovery,yet existing methods suffer from insufficient selectivity toward target products.Herein,we demonstrate an efficient approach to selectively convert PS into benzoic acid(BA)with an impressive yield of 90%.The process uses nitrogen dioxide(NO_(2)),generated in situ from sodium nitrite and acetic acid,as the primary catalyst,with commercially available cobalt chloride(CoCl_(2))as a cocatalyst under mild conditions(180℃,2 bar(1 bar=101 kPa)O_(2)).Mechanistic studies revealed that NO_(2)simultaneously interacts with the Cα-H and Cβ-H bonds of the benzyl group via a HAT mechanism to form a dioxetane intermediate.This intermediate undergoes a ring-opening process,facilitating C-C bond cleavage and subsequent oxidation to BA.Furthermore,the demonstrated applicability of real-world PS waste underscores the potential of this process to advance PS recycling technologies,ultimately helping mitigate the environmental impact of plastic waste.展开更多
Dielectric pulse capacitors are of great concerns due to the fast charge/discharge rate and high-power density over traditional counterparts.However,energy-storage capacitor in power converters typically works at a la...Dielectric pulse capacitors are of great concerns due to the fast charge/discharge rate and high-power density over traditional counterparts.However,energy-storage capacitor in power converters typically works at a large DC-biased voltage,where the energy-storge density(Wdis)and efficiency(h)will dramatically decay,thus fatally blocks its further applications.Herein,we proposed a synergistic strategy to achieve a comprehensively improved energy storage property in Bi1exNaxTiO_(3)-NaNbO_(3)based ceramics.Configuration of chemical composition optimization,A-site vacancy engineering,grain size refinement,and sample thickness reduction were designed in the ceramics.Finally,an optimum Wdis of 8.04 J/cm^(3)and an ultrahigh h of 85%was achieved for the 0.50(0.95Bi_(0.52)Na_(0.44)TiO_(3)-0.05SrZrO_(3))-0.50NaNbO_(3)composite under a breakdown strength of 630 kV/cm,along with a stable DC-biased capacitance retention.Additionally,a superior performance stability was affirmed in a wide temperature/frequency range(25-150℃and 1-100 Hz,respectively).It also exhibits an impressive ability in fatigue resistance after being subjected to up to 106 cycles,which enable it to be a suitable candidate for high energy density storage devices.展开更多
Correction to:Radiation Detection Technology and Methods(2024)8:1-1105.https://doi.org/10.1007/s41605-024-00463-y.In this article all authors name was missing in the springer link.It has been corrected.The original ar...Correction to:Radiation Detection Technology and Methods(2024)8:1-1105.https://doi.org/10.1007/s41605-024-00463-y.In this article all authors name was missing in the springer link.It has been corrected.The original article has been corrected.展开更多
The Taurus region is one of the most extensively studied star-forming regions(SFRs).Surveys indicate that the young stars in this region are comprised of young stellar objects(YSOs)that cluster in groups associated wi...The Taurus region is one of the most extensively studied star-forming regions(SFRs).Surveys indicate that the young stars in this region are comprised of young stellar objects(YSOs)that cluster in groups associated with the molecular cloud(Grouped Young Stellar Objects,GYSOs),and some older ones that are sparsely distributed throughout the region(Distributed Young Stellar Objects,DYSOs).To bridge the age gap between the GYSOs(5 Myr)and the DYSOs(10-20 Myr),we conducted a survey to search for new YSOs in this direction.Based on infrared color excesses and Li I absorption lines,we identified 145 new YSOs.Combining these with the previously identified GYSOs and DYSOs,we constructed a sample of 519 YSOs that encompass the entire region.Subsequently,we calculated the ages of the samples based on their proximity to the local bubble.The age versus distance to the local bubble(D_(LB))relationship for the DYSOs shows a clear trend:the farther they are from the local bubble,the younger they are,which is consistent with the supernovae-driven formation scenario of the local bubble.The GYSOs also exhibit a mild age versus D_(LB)trend.However,they are significantly younger and are mostly confined to distances of 120 to 220 pc.Considering their distribution in the age versus D_(LB)space is well separated from the older DYSOs,they may also be products of the local bubble but formed in more recent and localized events.展开更多
The shear behavior of fractured rock masses critically infuences engineering stability,particularly in slope engineering.Overcoming limitations of conventional preparation methods,this study utilizes sand-powder 3D pr...The shear behavior of fractured rock masses critically infuences engineering stability,particularly in slope engineering.Overcoming limitations of conventional preparation methods,this study utilizes sand-powder 3D printing to fabricate rocklike specimens with controlled internal fractures.Direct shear tests systematically investigate fracture radius and number efects on strength evolution under constant density,with quantitative analysis revealing their diferential contributions.The results show that:(1)The failure of sand-powder 3D-printed fractured rock-like specimens exhibits brittle characteristics.The shear stress-shear displacement relationship can be divided into fve stages:compaction,elasticity,unstable development,peak,and post-peak.Crack initiation and propagation primarily occur from the late elastic stage to the peak stage.(2)An increase in fracture radius signifcantly reduces pre-peak shear stifness,resulting in a smoother curve progression,while changes in fracture number have minimal impact on the stage-specifc characteristics of the shear curve.(3)Shear strength decreases exponentially with increasing fracture radius,whereas an increase in fracture number leads to a linear reduction in shear strength.Moreover,the weakening efect of fracture number on shear strength becomes more pronounced with larger fracture radius.(4)Quantitative analysis shows that the infuence of fracture radius on shear strength is 2.4 times greater than that of fracture number.This study broadens the understanding of the shear behaviors of fractured rock masses and reveals the key infuence mechanism of fracture density on rock mass deformation and failure,and provides theoretical guidance for slope stability analysis and rock mass engineering design.展开更多
Heterojunction structures are favored for constructing photoelectrochemical ultraviolet photodetectors(PEC UV PDs),whereas lattice mismatches impede their optoelectronic performance.This work presents a novel homojunc...Heterojunction structures are favored for constructing photoelectrochemical ultraviolet photodetectors(PEC UV PDs),whereas lattice mismatches impede their optoelectronic performance.This work presents a novel homojunction consisting of two-dimensional(2D)In_(2)O_(3) nanosheets(NS)and three-dimensional(3D)In_(2)O_(3) microcubes(MC)with a suitable energy band alignment.2D In_(2)O_(3) NS not only shows an enlarged bandgap due to the quantum confinement effect but also effectively upshifts the conductive band and Fermi level stemming from the oxygen vacancy demonstrated by the theoretical simulation and experimental results.The photogenerated carrier dynamic of In_(2)O_(3) photoanodes is boosted by the 2D-3D homojunction with a built-in electric field and more electrochemically active sites,leading to higher photogenerated carrier separation efficiency,faster interfacial charge transfer,and better self-powered capability.The In_(2)O_(3)2D-3D homojunction PEC UV PDs exhibit outstanding self-powered deep-UV photoresponse at 0 V,with an ultrahigh responsivity of 316.5 mA/W for 254 nm light,a fast response speed of 15/15 ms,high detectivity of 1.12×10^(12) Jones,and an outstanding ultraviolet–visible(UV–vis)rejection ratio of 1507,surpassing most recorded PEC UV PDs.This work demonstrates the pivotal role of morphology-controlled homojunction in modulating photogenerated carrier dynamics and offers a new strategy for designing high-performance PEC devices.展开更多
No-tillage seeding has become an important approach to improve crop productivity,which needs colters of high performance to cut the root-stubble-soil composite.However,the difficulty of maize root-stubbles three-dimen...No-tillage seeding has become an important approach to improve crop productivity,which needs colters of high performance to cut the root-stubble-soil composite.However,the difficulty of maize root-stubbles three-dimensional(3D)modeling hinders finite element(FE)simulation to improve development efficiency of such colters because of maize root system complexity and opaque nature of the soil.Fortunately,the non-destructive 3D geometric model of the maize root-stubble in-situ can be established via X-ray computed tomography(CT)following by a systematic procedure.The whole procedure includes CT scanning of the maize root-stubble-soil composite sample,image reconstruction via filtered back-projection(FBP)with the Hanning filter,segmentation of root-stubble via a variational level set method,and post-processing via morphological operations.The 3D reconstruction model of the maize root-stubble in-situ presents a complete,complex and in-situ geometrical morphology,which cannot be realized via other methods,including the destructive modelling after washing via CT.This study is the first to build a 3D geometric model of a maize root-stubble in-situ via CT,which opens up new possibilities for simulation of root-stubble-soil cutting using FEM,and much other research related to plant root-stubbles.展开更多
The development of organ-on-a-chip systems demands high requirements for adequate micro-pump performance,which needs excellent performance and effective transport of active cells.In this study,we designed a piezoelect...The development of organ-on-a-chip systems demands high requirements for adequate micro-pump performance,which needs excellent performance and effective transport of active cells.In this study,we designed a piezoelectric pump with a flexible venous valve inspired by that of humans.Performance test of the proposed pump with deionized water as the transmission medium shows a maximum output flow rate of 14.95 mL/min when the input voltage is 100 V,and the pump can transfer aqueous solutions of glycerol with a viscosity of 10.8 mPa·s.Cell survival rate can reach 97.22%with a yeast cell culture solution as the transmission medium.A computational model of the electric-solid-liquid multi-physical field coupling of the piezoelectric pump with a flexible venous valve is established,and simulation results are consistent with experimental results.The proposed pump can help to construct the circulating organ-on-a-chip system,and the simple structure and portable application can enrich the design of microfluidic systems.In addition,the multi-physical field coupling computational model established for the proposed piezoelectric pump can provide an in-depth study of the characteristics of the flow field,facilitating the optimal design of the micro-pump and providing a reference for the further study of active cell transport in organ-on-a-chip systems.展开更多
基金the National Natural Science Foundation of China(51764048,51703118 and 51474191)Yunnan Province Thousand Youth Talents Plan+1 种基金the Application Basis Research Project of Yunnan Province Science and Technology Department(2017FD144)Key Natural Science Foundation of Yunnan Province China(2018FA28)for providing the financial support。
文摘The side reaction between the active material and liquid-electrolyte cause structural damage and particle pulverization is one of the important factors leading to the capacity decay of LiNi0.80Co0.15Al0.05O2(NCA)materials in Li ion batteries(LIBs).Surface modification is an effective strategy for NCA cathodes,which could alleviate the degradation associated with surface processes.Herein,a surface structure rearrangement of NCA cathode secondary particles was reported by in-situ forming a solid electrolyte LiBO2.The LiBO2 is beneficial for alleviating the stress during charge/discharge process,thereby slowing down the rate of cracks formation in the secondary particles,which facilitates the Li+de-intercalation as well as prevents penetration of the liquid-electrolyte into the interior of the particles.As a result,the surface structure rearrangement NCA(RS-NCA)delivers a high discharge capacity of 202.5 m Ah g^-1 at 0.1 C,and exhibits excellent cycle stability with discharge capacity retaining 148 m Ah g^-1 after 200 cycles at 2 C.This surface structure rearrangement approach provides a new viewpoint in designing high-performance high-voltage LIBs.
基金supported in part by the National Key R&D Program of China under Grant 2019YFB1503700in part by the National Natural Science Foundation of China under Grant 51977191。
文摘Inductance asymmetry,which is brought by inherent asymmetric parameters,manufacture tolerance,winding fault,cables with unequal lengths,etc.,of permanent-magnet synchronous machines(PMSMs)can cause current harmonics and inaccurate position estimation.This paper proposes an enhanced fundamental model based sensorless control strategy for PMSMs with asymmetric inductances.The proportional-integral-resonant current regulator is introduced to reduce the second-order harmonics of currents,but there are still negative sequence components in the estimated back-electromotive forces(EMFs),which can cause the position estimated error.Differing from conventional methods in which negative sequences are filtered out before the phase-locked loop(PLL)module,the proposed method directly applies the estimated back-EMF with negative sequences as the reference input of PLL.An improved PLL with a bi-quad filter is proposed to attenuate the arising second harmonic position error and heighten the steady-state accuracy.Then,this position error is used for asymmetric inductance identification and its result is utilized to update the observer model.Furthermore,the dynamic performance is improved by the output limitation on the bi-quad filter as well as the implementation of a fast-locking technique in the PLL.The effectiveness of the proposed scheme is verified by experimental results.
基金supported by grants from National Natural Science Foundation of China(Grant Nos.81974422,81772824,and 81802635)。
文摘Objective:The spectrum and risk of cancer in relatives of BRCA1/2 pathogenic variant carriers in the Chinese population have not been established.Methods:A family history of cancer in 9903 unselected breast cancer patients was retrospectively analyzed.BRCA1/2 status was determined for all patients and relative risks(RRs)were calculated to evaluate cancer risk in relatives of the patients.Results:The incidences of breast cancer in female relatives of BRCA1 carriers,BRCA2 carriers,and non-carriers were 33.0%,32.2%,and 7.7%,respectively.The corresponding incidences of ovarian cancer were 11.5%,2.4%,and 0.5%,respectively.The incidences of pancreatic cancer in male relatives of BRCA1 carriers,BRCA2 carriers,and non-carriers were 1.4%,2.7%,and 0.6%,respectively.The corresponding incidences of prostate cancer were 1.0%,2.1%,and 0.4%,respectively.The risks of breast and ovarian cancers in female relatives of BRCA1 and BRCA2 carriers were significantly higher than female relatives of non-carriers(BRCA1:RR=4.29,P<0.001 and RR=21.95,P<0.001;BRCA2:RR=4.19,P<0.001 and RR=4.65,P<0.001,respectively).Additionally,higher risks of pancreatic and prostate cancers were noted in male relatives of BRCA2 carriers than non-carriers(RR=4.34,P=0.001 and RR=4.86,P=0.001,respectively).Conclusions:Female relatives of BRCA1 and BRCA2 carriers are at increased risk for breast and ovarian cancers,and male relatives of BRCA2 carriers are at increased risk for pancreatic and prostate cancers.
基金the support from the Shenzhen Science and Technology Program of China(No.JCYJ20220530161614031)National Natural Science Foundation of China(No.52471094)Shaanxi Coal Chemical Industry Technology Research Institute Co.,Ltd.
文摘In the realm of proton exchange membrane fuel cells(PEMFCs),the bipolar plates(BPs)are indispensable and serve pivotal roles in distributing reactant gases,collecting current,facilitating product water removal,and cooling the stack.Metal BPs,characterized by outstanding manufacturability,cost-effectiveness,higher power density,and mechanical strength,are emerging as viable alternatives to traditional graphite BPs.The foremost challenge for metal BPs lies in enhancing their corrosion resistance and conductivity under acidic conditions,necessitating the application of various coatings on their surfaces to ensure superior performance.This review summarizes and compares recent advancements in the research of eight distinct types of coatings for BPs in PEMFCs,including noble metal,carbide,ni-tride,and amorphous carbon(a-C)/metal compound composite coatings.The various challenges encountered in the manufacturing and fu-ture application of these coatings are also delineated.
基金supported by the National Natural Science Foundation of China(NSFC,grant Nos.12173013,12103062,12003045,and 11903012)the National Key Basic R&D Program of China via 2019YFA0405500+2 种基金supported by the Natural Science Foundation of Hebei Province under grant A2021205006 and A2019205166by the project of the Hebei provincial department of science and technology under grant number 226Z7604Gthe science research grants from the China Manned Space Project。
文摘Using 9943 OB-type stars from LAMOST DR7 in the solar neighborhood,we fit the vertical stellar density profile with the model including a single exponential distribution at different positions(R,Φ).The distributions of the scale heights and scale length show that the young disk traced by the OB-type stars is not axisymmetric.The scale length decreases versus the azimuthal angleΦ,i.e.,from.■kpc withΦ=-3°to■kpc withΦ=9°.Meanwhile we find signal of non-symmetry in the distribution of the scale height of the north and south of the disk plane.The scale height in the north side shows signal of flaring of the disk,while that of the south disk stays almost constant around h_(s)=130 pc.The distribution of the displaceeent of the disk plane Z_(0)also shows variance versus the azimuthal angleΦ,which displays significant differences with the warp model constrained by the Cepheid stars.We also test different values for the position of the Sun,and the distance between the Sun and the Galactic center affects the scale heights and the displacement of the disk significantly,but that does not change our conclusion that the disk is not axisymmetric.
文摘Boost-Buck converter is widely used in LED lighting drivers. In this paper, Boost-Buck main circuit related characteristics are firstly discussed, and then a new Boost-Buck high power efficient double loop control strategy is built by adopting error amplifier and integrator control method. It is demonstrated that the new system has many advantages such as high efficiency, fast response, strong anti-interference, good stability after analyses and simulations of its working dynamic characteristics.
基金supported by the Natural Science Foundation of Jiangsu Province of China(No.BK20201008).
文摘Iron oxide(Fe_(2)O_(3))emerges as a highly attractive anode candidate among rapidly expanding energy storage market.Nonethe-less,its considerable volume changes during cycling as an electrode material result in a vast reduced battery cycle life.In this work,an ap-proach is pioneered for preparing high-performance Fe_(2)O_(3)anode materials,by innovatively synthesizing a triple-layer yolk-shell Fe_(2)O_(3)uniformly coated with a conductive polypyrrole(Ppy)layer(Fe_(2)O_(3)@Ppy-TLY).The uniform polypyrrole coating introduces more reac-tion sites and adsorption sites,and maintains structure stability through charge-discharge process.In the uses as lithium-ion battery elec-trodes,Fe_(2)O_(3)@Ppy-TLY demonstrates high reversible specific capacity(maintaining a discharge capacity of 1375.11 mAh·g^(−1)after 500 cycles at 1 C),exceptional cycling stability(retaining the steady charge-discharge performance at 544.33 mAh·g^(−1)after 6000 ultrafast charge-discharge cycles at a 10 C current density),and outstanding high current charge-discharge performance(retaining a reversible ca-pacity of 156.75 mAh·g^(−1)after 10000 cycles at 15 C),thereby exhibiting superior lithium storage performance.This work introduces in-novative advancements for Fe_(2)O_(3)anode design,aiming to enhance its performance in energy storage fields.
文摘Tin sulfide(SnS_(2))anodes have garnered significant attention within emerging energy storage technologies.However,the application of SnS_(2)is curtailed due to its inherent limitations,including poor cyclic stability and inevitable volumetric expansion upon cycling.This study reports the successful fabrication of an innovative SnS_(2)-based composite,featuring an eggshell-like structured nitrogen-doped carbon coating,referred to as SnS_(2)@NxC.This novel architecture,wherein SnS_(2)acts as the core encapsulated by a nitrogen-doped carbon shell,characterized by a void space between the shell and core,is crucial in mitigating volumetric expansion.This configuration contributes to maintaining the structural integrity of the composite materials,even under the stresses of continuous cycling.Nitrogen within the carbon matrix enhances conductivity and promotes the formation of a more robust and stable solid electrolyte interphase(SEI)layer.Experimental investigations have substantiated the electrochemical superiority of the SnS_(2)@NxC electrode,demonstrating a specific capacity of 701.8 mA·h·g^(-1)after 1000 cycles at 0.5 A·g^(-1)and maintaining a capacity of 597.2mA·h·g^(-1)after 400 cycles at a heightened current density of 2 A·g^(-1).These findings underscore the exceptional cyclic performance and durability of the SnS_(2)@NxC electrode.
文摘The authors regret that the printed version of the above article contained some errors.The funding number in acknowledgments of this paper was incorrectly marked,and we hope to correct it.We thank the National Natural Science Foundation of China(51764048,51703118 and 51474191),Yunnan Province Thousand Youth Talents Plan,the Application Basis Research Project of Yunnan Province Science and Technology Department(2017FD144)and Key Natural Science Foundation of Yunnan Province China(2018FA28)for providing the financial support.
基金supported by the National Natural Science Foundation of China(62473316,62073269)the Natural Science Foundation of Chongqing,China(CSTB2022NSCQ-MSX0963)+1 种基金Guangdong Basic and Applied Basic Research Foundation(2023A1515011220)Aeronautical Science Foundation of China(2020Z034053002)。
文摘The article investigates the optimal energy management(OEM)problem for microgrids.To figure out the problem in fixed time and alleviate communication load with limited resources,this article devises a novel fixed-time stability lemma and an event-triggered(ET)fixed-time distributed OEM approach.Using Lyapunov stability theory,the distributed approach has been proven to converge in fixed time and the upper bound on convergence time can be derived without dependence on the initial states.The dynamic ET method is raised to dynamically adjust the triggering threshold and reduce communication redundancy.In addition,Zeno behavior is avoided.Simulations are given to show the effectiveness and advantage of the designed distributed OEM method.
基金supported by the National Natural Science Foundation of China(22376183 and 22209146)the Key Research and Development Program of Zhejiang Province(2024C03112)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(GZB20230633)。
文摘The inherent stability and durability of polystyrene(PS)make it a valuable material but also complicate its chemical recycling.Oxidative degradation via hydrogen atom transfer(HAT)is a promising route for PS recovery,yet existing methods suffer from insufficient selectivity toward target products.Herein,we demonstrate an efficient approach to selectively convert PS into benzoic acid(BA)with an impressive yield of 90%.The process uses nitrogen dioxide(NO_(2)),generated in situ from sodium nitrite and acetic acid,as the primary catalyst,with commercially available cobalt chloride(CoCl_(2))as a cocatalyst under mild conditions(180℃,2 bar(1 bar=101 kPa)O_(2)).Mechanistic studies revealed that NO_(2)simultaneously interacts with the Cα-H and Cβ-H bonds of the benzyl group via a HAT mechanism to form a dioxetane intermediate.This intermediate undergoes a ring-opening process,facilitating C-C bond cleavage and subsequent oxidation to BA.Furthermore,the demonstrated applicability of real-world PS waste underscores the potential of this process to advance PS recycling technologies,ultimately helping mitigate the environmental impact of plastic waste.
基金the National Natural Science Foundation of China(No.52372101,52032005)。
文摘Dielectric pulse capacitors are of great concerns due to the fast charge/discharge rate and high-power density over traditional counterparts.However,energy-storage capacitor in power converters typically works at a large DC-biased voltage,where the energy-storge density(Wdis)and efficiency(h)will dramatically decay,thus fatally blocks its further applications.Herein,we proposed a synergistic strategy to achieve a comprehensively improved energy storage property in Bi1exNaxTiO_(3)-NaNbO_(3)based ceramics.Configuration of chemical composition optimization,A-site vacancy engineering,grain size refinement,and sample thickness reduction were designed in the ceramics.Finally,an optimum Wdis of 8.04 J/cm^(3)and an ultrahigh h of 85%was achieved for the 0.50(0.95Bi_(0.52)Na_(0.44)TiO_(3)-0.05SrZrO_(3))-0.50NaNbO_(3)composite under a breakdown strength of 630 kV/cm,along with a stable DC-biased capacitance retention.Additionally,a superior performance stability was affirmed in a wide temperature/frequency range(25-150℃and 1-100 Hz,respectively).It also exhibits an impressive ability in fatigue resistance after being subjected to up to 106 cycles,which enable it to be a suitable candidate for high energy density storage devices.
文摘Correction to:Radiation Detection Technology and Methods(2024)8:1-1105.https://doi.org/10.1007/s41605-024-00463-y.In this article all authors name was missing in the springer link.It has been corrected.The original article has been corrected.
基金supported by the National Key R&D Program of China(Grant No.2023YFA1608000)the National Natural Science Foundation of China(NSFC)(Grant Nos.12003045,and 12173013)+2 种基金the Science Foundation of Hebei Normal University(Grant No.L2022B07)the project of Hebei Provincial Department of Science and Technology(Grant No.226Z7604G)the Hebei Natural Science Foundation(NSF)(Grant Nos.A2021205006,and A2023205036)。
文摘The Taurus region is one of the most extensively studied star-forming regions(SFRs).Surveys indicate that the young stars in this region are comprised of young stellar objects(YSOs)that cluster in groups associated with the molecular cloud(Grouped Young Stellar Objects,GYSOs),and some older ones that are sparsely distributed throughout the region(Distributed Young Stellar Objects,DYSOs).To bridge the age gap between the GYSOs(5 Myr)and the DYSOs(10-20 Myr),we conducted a survey to search for new YSOs in this direction.Based on infrared color excesses and Li I absorption lines,we identified 145 new YSOs.Combining these with the previously identified GYSOs and DYSOs,we constructed a sample of 519 YSOs that encompass the entire region.Subsequently,we calculated the ages of the samples based on their proximity to the local bubble.The age versus distance to the local bubble(D_(LB))relationship for the DYSOs shows a clear trend:the farther they are from the local bubble,the younger they are,which is consistent with the supernovae-driven formation scenario of the local bubble.The GYSOs also exhibit a mild age versus D_(LB)trend.However,they are significantly younger and are mostly confined to distances of 120 to 220 pc.Considering their distribution in the age versus D_(LB)space is well separated from the older DYSOs,they may also be products of the local bubble but formed in more recent and localized events.
基金supported by the National Key Research and Development Program Young Scientist Project(2024YFC2911000)the Natural Science Foundation of Shandong Province(ZR2024ME031)+1 种基金National Natural Science Foundation of China(52474103)Natural Science Foundation of Shandong Province(ZR2024ZD22).
文摘The shear behavior of fractured rock masses critically infuences engineering stability,particularly in slope engineering.Overcoming limitations of conventional preparation methods,this study utilizes sand-powder 3D printing to fabricate rocklike specimens with controlled internal fractures.Direct shear tests systematically investigate fracture radius and number efects on strength evolution under constant density,with quantitative analysis revealing their diferential contributions.The results show that:(1)The failure of sand-powder 3D-printed fractured rock-like specimens exhibits brittle characteristics.The shear stress-shear displacement relationship can be divided into fve stages:compaction,elasticity,unstable development,peak,and post-peak.Crack initiation and propagation primarily occur from the late elastic stage to the peak stage.(2)An increase in fracture radius signifcantly reduces pre-peak shear stifness,resulting in a smoother curve progression,while changes in fracture number have minimal impact on the stage-specifc characteristics of the shear curve.(3)Shear strength decreases exponentially with increasing fracture radius,whereas an increase in fracture number leads to a linear reduction in shear strength.Moreover,the weakening efect of fracture number on shear strength becomes more pronounced with larger fracture radius.(4)Quantitative analysis shows that the infuence of fracture radius on shear strength is 2.4 times greater than that of fracture number.This study broadens the understanding of the shear behaviors of fractured rock masses and reveals the key infuence mechanism of fracture density on rock mass deformation and failure,and provides theoretical guidance for slope stability analysis and rock mass engineering design.
文摘Heterojunction structures are favored for constructing photoelectrochemical ultraviolet photodetectors(PEC UV PDs),whereas lattice mismatches impede their optoelectronic performance.This work presents a novel homojunction consisting of two-dimensional(2D)In_(2)O_(3) nanosheets(NS)and three-dimensional(3D)In_(2)O_(3) microcubes(MC)with a suitable energy band alignment.2D In_(2)O_(3) NS not only shows an enlarged bandgap due to the quantum confinement effect but also effectively upshifts the conductive band and Fermi level stemming from the oxygen vacancy demonstrated by the theoretical simulation and experimental results.The photogenerated carrier dynamic of In_(2)O_(3) photoanodes is boosted by the 2D-3D homojunction with a built-in electric field and more electrochemically active sites,leading to higher photogenerated carrier separation efficiency,faster interfacial charge transfer,and better self-powered capability.The In_(2)O_(3)2D-3D homojunction PEC UV PDs exhibit outstanding self-powered deep-UV photoresponse at 0 V,with an ultrahigh responsivity of 316.5 mA/W for 254 nm light,a fast response speed of 15/15 ms,high detectivity of 1.12×10^(12) Jones,and an outstanding ultraviolet–visible(UV–vis)rejection ratio of 1507,surpassing most recorded PEC UV PDs.This work demonstrates the pivotal role of morphology-controlled homojunction in modulating photogenerated carrier dynamics and offers a new strategy for designing high-performance PEC devices.
基金The work is financially supported by the National Natural Science Foundation of China(Grant No.51705227)University of Science and Technology Liaoning Talent Project Grants(Grant No.601011507-19)+1 种基金and Special Scientific Research Foundation of University of Science and Technology Liaoning(Grant No.2016YY02)We thank Jiuming Su for his lab assistance,and also thank Zong Zhang and Xinrui Xu for their analysis assistance.
文摘No-tillage seeding has become an important approach to improve crop productivity,which needs colters of high performance to cut the root-stubble-soil composite.However,the difficulty of maize root-stubbles three-dimensional(3D)modeling hinders finite element(FE)simulation to improve development efficiency of such colters because of maize root system complexity and opaque nature of the soil.Fortunately,the non-destructive 3D geometric model of the maize root-stubble in-situ can be established via X-ray computed tomography(CT)following by a systematic procedure.The whole procedure includes CT scanning of the maize root-stubble-soil composite sample,image reconstruction via filtered back-projection(FBP)with the Hanning filter,segmentation of root-stubble via a variational level set method,and post-processing via morphological operations.The 3D reconstruction model of the maize root-stubble in-situ presents a complete,complex and in-situ geometrical morphology,which cannot be realized via other methods,including the destructive modelling after washing via CT.This study is the first to build a 3D geometric model of a maize root-stubble in-situ via CT,which opens up new possibilities for simulation of root-stubble-soil cutting using FEM,and much other research related to plant root-stubbles.
基金supported by the National Natural Science Foundation of China(Grant Nos.51605200,61973207)Shanghai Rising-Star Program,China(Grant No.20QA1403900)the Natural Science Foundation of Shanghai,China(Grant No.19ZR1474000)。
文摘The development of organ-on-a-chip systems demands high requirements for adequate micro-pump performance,which needs excellent performance and effective transport of active cells.In this study,we designed a piezoelectric pump with a flexible venous valve inspired by that of humans.Performance test of the proposed pump with deionized water as the transmission medium shows a maximum output flow rate of 14.95 mL/min when the input voltage is 100 V,and the pump can transfer aqueous solutions of glycerol with a viscosity of 10.8 mPa·s.Cell survival rate can reach 97.22%with a yeast cell culture solution as the transmission medium.A computational model of the electric-solid-liquid multi-physical field coupling of the piezoelectric pump with a flexible venous valve is established,and simulation results are consistent with experimental results.The proposed pump can help to construct the circulating organ-on-a-chip system,and the simple structure and portable application can enrich the design of microfluidic systems.In addition,the multi-physical field coupling computational model established for the proposed piezoelectric pump can provide an in-depth study of the characteristics of the flow field,facilitating the optimal design of the micro-pump and providing a reference for the further study of active cell transport in organ-on-a-chip systems.
