Osteoporosis caused by aging is characterized by reduced bone mass and accumulated adipocytes in the bone marrow cavity. How the balance between osteoblastogenesis and adipogenesis from bone marrow mesenchymal stem ce...Osteoporosis caused by aging is characterized by reduced bone mass and accumulated adipocytes in the bone marrow cavity. How the balance between osteoblastogenesis and adipogenesis from bone marrow mesenchymal stem cells(BMSCs) is lost upon aging is still unclear. Here, we found that the RNA-binding protein Musashi2(Msi2) regulates BMSC lineage commitment. Msi2 is commonly enriched in stem cells and tumor cells. We found that its expression was downregulated during adipogenic differentiation and upregulated during osteogenic differentiation of BMSCs. Msi2 knockout mice exhibited decreased bone mass with substantial accumulation of marrow adipocytes, similar to aging-induced osteoporosis. Depletion of Msi2 in BMSCs led to increased adipocyte commitment. Transcriptional profiling analysis revealed that Msi2 deficiency led to increased PPARγ signaling.RNA-interacting protein immunoprecipitation assays demonstrated that Msi2 could inhibit the translation of the key adipogenic factor Cebpα, thereby inhibiting PPAR signaling. Furthermore, the expression of Msi2 decreased significantly during the aging process of mice, indicating that decreased Msi2 function during aging contributes to abnormal accumulation of adipocytes in bone marrow and osteoporosis. Thus, our results provide a putative biochemical mechanism for aging-related osteoporosis, suggesting that modulating Msi2 function may benefit the treatment of bone aging.展开更多
Realization of Kondo lattice in superconducting van der Waals materials not only provides a unique opportunity for tuning the Kondo lattice behavior by electrical gating or intercalation,but also is helpful for furthe...Realization of Kondo lattice in superconducting van der Waals materials not only provides a unique opportunity for tuning the Kondo lattice behavior by electrical gating or intercalation,but also is helpful for further understanding the heavy fermion superconductivity.Here we report a low-temperature and vector-magneticfield scanning tunneling microscopy and spectroscopy study on a superconducting compound(4Hb-TaS_(2))with alternate stacking of 1T-TaS_(2)and 1H-TaS_(2)layers.We observe the quasi-two-dimensional superconductivity in the 1H-TaS_(2)layer with anisotropic response to the in-plane and out-of-plane magnetic fields.In the 1T-TaS_(2)layer,we detect the Kondo resonance peak that results from the Kondo screening of the unpaired electrons in the Star-of-David clusters.We also find that the intensity of the Kondo resonance peak is sensitive to its relative position with the Fermi level,and it can be significantly enhanced when it is further shifted towards the Fermi level by evaporating Pb atoms onto the 1T-TaS_(2)surface.Our results not only are important for fully understanding the electronic properties of 4Hb-TaS_(2),but also pave the way for creating tunable Kondo lattice in the superconducting van der Waals materials.展开更多
It is known that α-RuCl_(3) has been studied extensively because of its proximity to the Kitaev quantum-spin-liquid(QSL)phase and the possibility of approaching it by tuning the competing interactions.Here we present...It is known that α-RuCl_(3) has been studied extensively because of its proximity to the Kitaev quantum-spin-liquid(QSL)phase and the possibility of approaching it by tuning the competing interactions.Here we present the first polarized inelastic neutron scattering study on α-RuCl_(3) single crystals to explore the scattering continuum around the Γ point at the Brillouin zone center,which was hypothesized to be resulting from the Kitaev QSL state but without concrete evidence.With polarization analyses,we find that,while the spin-wave excitations around the Γ point vanish above the transition temperature T_(N),the pure magnetic continuous excitations around the Γ point are robust against temperature.Furthermore,by calculating the dynamical spin-spin correlation function using the cluster perturbation theory,we derive magnetic dispersion spectra based on the K-Γ model,which involves with a ferromagnetic Kitaev interaction of −7.2 meV and an off-diagonal interaction of 5.6 meV.We find this model can reproduce not only the spin-wave excitation spectra around the Γ point,but also the non-spin-wave continuous magnetic excitations around the Γ point.These results provide evidence for the existence of fractional excitations around the Γ point originating from the Kitaev QSL state,and further support the validity of the K-Γ model as the effective minimal spin model to describe α-RuCl_(3).展开更多
As a new type of quantum state of matter hosting low energy relativistic quasiparticles,Weyl semimetals(WSMs)have attracted significant attention for scientific community and potential quantum device applications.In t...As a new type of quantum state of matter hosting low energy relativistic quasiparticles,Weyl semimetals(WSMs)have attracted significant attention for scientific community and potential quantum device applications.In this study,we present a comprehensive investigation of the structural,magnetic,and transport properties of noncentrosymmetric RAl Si(R=Sm,Ce),which have been predicted to be new magnetic WSM candidates.Both samples exhibit nonsaturated magnetoresistance,with about 900%and 80%for Sm Al Si and Ce Al Si,respectively,at temperature of 1.8 K and magnetic field of 9 T.The carrier densities of Sm Al Si and Ce Al Si exhibit remarkable change around magnetic transition temperatures,signifying that the electronic states are sensitive to the magnetic ordering of rare-earth elements.At low temperatures,Sm Al Si reveals prominent Shubnikov–de Haas oscillations associated with the nontrivial Berry phase.High-pressure experiments demonstrate that the magnetic order is robust and survival under high pressure.Our results would yield valuable insights into WSM physics and potentials in applications to next-generation spintronic devices in the RAl Si(R=Sm,Ce)family.展开更多
As one of the most promising Kitaev quantum-spin-liquid(QSL)candidates,α-RuCl_(3)has received a great deal of attention.However,its ground state exhibits a long-range zigzag magnetic order,which defies the QSL phase....As one of the most promising Kitaev quantum-spin-liquid(QSL)candidates,α-RuCl_(3)has received a great deal of attention.However,its ground state exhibits a long-range zigzag magnetic order,which defies the QSL phase.Nevertheless,the magnetic order is fragile and can be completely suppressed by applying an external magnetic field.Here,we explore the evolution of magnetic excitations ofα-RuCl;under an in-plane magnetic field,by carrying out inelastic neutron scattering measurements on high-quality single crystals.Under zero field,there exist spin-wave excitations near the M point and a continuum near theΓpoint,which are believed to be associated with the zigzag magnetic order and fractional excitations of the Kitaev QSL state,respectively.By increasing the magnetic field,the spin-wave excitations gradually give way to the continuous excitations.On the verge of the critical fieldμ_(0)H_(c)=7.5 T,the former ones vanish and only the latter ones are left,indicating the emergence of a pure QSL state.By further increasing the field strength,the excitations near theΓpoint become more intense.By following the gap evolution of the excitations near theΓpoint,we are able to establish a phase diagram composed of three interesting phases,including a gapped zigzag order phase at low fields,possibly gapless QSL phase nearμ;H;,and gapped partially polarized phase at high fields.These results demonstrate that an in-plane magnetic field can driveα-RuCl;into a long-sought QSL state near the critical field.展开更多
In iron-based superconductors,the(0,π) or(π,0) nematicity,which describes an electronic anisotropy with a fourfold symmetry breaking,is well established and believed to be important for understanding the superconduc...In iron-based superconductors,the(0,π) or(π,0) nematicity,which describes an electronic anisotropy with a fourfold symmetry breaking,is well established and believed to be important for understanding the superconducting mechanism.However,how exactly such a nematic order observed in the normal state can be related to the superconducting pairing is still elusive.Here,by performing angular-dependent in-plane magnetoresistivity using ultra-thin flakes in the steep superconducting transition region,we unveil a nematic superconducting order along the(π,π) direction in electron-doped BaFe_(2-x)Ni_(x)As_(2) from under-doped to heavily overdoped regimes with x=0.065- 0.18.It shows superconducting gap maxima along the(π,π) direction rotated by 45° from the nematicity along(0, π) or(π,0) direction observed in the normal state.A similar(π,π)-type nematicity is also observed in the under-doped and optimally doped hole-type Ba1-yKyFe2 As_(2),with y=0.2-0.5.These results suggest that the(π,π) nematic superconducting order is a universal feature that needs to be taken into account in the superconducting pairing mechanism in iron-based superconductors.展开更多
Quantum spin liquids（QSLs） represent a novel state of matter in which quantum fluctuations prevent the conventional magnetic order from being established, and the spins remain disordered even at zero temperature. Th...Quantum spin liquids（QSLs） represent a novel state of matter in which quantum fluctuations prevent the conventional magnetic order from being established, and the spins remain disordered even at zero temperature. There have been many theoretical developments proposing various QSL states. On the other hand, experimental movement was relatively slow largely due to limitations on the candidate materials and difficulties in the measurements. In recent years, the experimental progress has been accelerated. In this topical review, we give a brief summary of experiments on the QSL candidates under magnetic fields. We arrange our discussions by two categories： i） Geometrically-frustrated systems, including triangularlattice compounds YbMgGaO4 and YbZnGaO4, κ-（BEDT-TTF）2 Cu2（CN）3, and EtMe3 Sb[Pd（dmit）2]2, and the kagom′e system ZnCu3（OH）6 Cl2; ii） the Kitaev material α-RuCl3. Among these, we will pay special attention to α-RuCl3, which has been intensively studied by ours and other groups recently. We will present evidence that both supports and rejects the QSL ground state for these materials, based on which we give several perspectives to stimulate further research activities.展开更多
Various material design strategies have been developed to enhance photocatalytic performance of TiO_(2).However,no report is available on applications of the photopiezocatalysis strategy on TiO_(2)due to its lack of p...Various material design strategies have been developed to enhance photocatalytic performance of TiO_(2).However,no report is available on applications of the photopiezocatalysis strategy on TiO_(2)due to its lack of piezoelectricity.Here we developed a low-temperature molten salt etching process to create rutile TiO_(2)nanoparticles by etching[MgO_(6)]octahedrons away from MgTiO_(3)by molten NH_(4)Cl,during which a lattice distortion occurred in TiO_(2).The lattice distortion broke the structure symmetry of rutile TiO_(2)and subsequently endowed these rutile TiO_(2)nanoparticles with an unusual piezoelectric response with the maximum effective piezoelectric coefficient(d_(33))of~41.6 pm/V,which had not previously been found in TiO_(2)photocatalysts.Thus,the photopiezocatalysis strategy was applied for the first time to enhance the photocatalytic performance of these TiO_(2)nanoparticles.The creation of lattice distortion to induce piezoelectricity could be extended to other photocatalysts that the photopiezocatalysis strategy has not been applied to and may generate novel functionalities for various technical applications.展开更多
Background: C-reactive protein to albumin ratio(CRP/Alb ratio,CAR)has been suggested as a potential prognostic biomarker in lung cancer.This updated systematic review and meta-analysis aimed to assess the association ...Background: C-reactive protein to albumin ratio(CRP/Alb ratio,CAR)has been suggested as a potential prognostic biomarker in lung cancer.This updated systematic review and meta-analysis aimed to assess the association between CAR and lung cancer prognosis in current literature.Methods: A systematic search of databases was conducted to identify relevant studies published up to April 2023.Pooled hazard ratios(HRs)and 95%confidence intervals(CIs)were calculated to assess the association between CAR and overall survival(OS)and progression-free survival(PFS)and recurrence-free survival(RF)in lung cancer patients.Results: This meta-analysis includes 16 studies with a total of 5337 patients,indicating a significant association between higher CAR and poorer OS,PFS,and RFS in lung cancer patients,with a pooled HR of 1.78(95%CI=1.60-1.99),1.57(95%CI=1.36-1.80),and 1.97(95%CI=1.40-2.77),respectively.Conclusions: This updated meta-analysis provides evidence for the potential prognostic role of CAR in lung cancer,suggesting its utility as an effective and noninvasive biomarker for identifying high-risk patients and informing treatment decisions in a cost-effective manner.However,further large-scale studies will be necessary to establish the optimal cut-off value for CAR in lung cancer and confirm the present findings.展开更多
Virtual reality(VR)has been a promising tool for developing visuospatial tasks.Among visuospatial tasks,mental rotation tasks are widely used in the assessment of visuospatial ability.Males have a distinct advantage i...Virtual reality(VR)has been a promising tool for developing visuospatial tasks.Among visuospatial tasks,mental rotation tasks are widely used in the assessment of visuospatial ability.Males have a distinct advantage in mental rotation ability compared to females,yet it is generally produced by investigations based on two-dimensional(2D)images on a computer screen.Sex differences in mental rotation tasks with three-dimensional(3D)objects in VR were not fully investigated.It is unclear whether the male's advantages in 2D mental rotation tasks are weakened in 3D tasks.The aim of this study was to provide new insights into the understanding of sex differences in mental rotation tasks presented in VR.Here,we developed a VR mental rotation task(VR-MRT)using 3D objects presented by a head-mounted display(HMD)and used VR-based eye tracking and electroencephalography(EEG)to examine eye movements and neural oscillations for males and females.Our results showed that females preferred a piecemeal strategy compared to males,suggesting a significant sex difference in visual strategy.More importantly,we found no significant sex differences in alpha-band and beta-band oscillations related to rotation processes of VR-MRT.These findings indicated that sex differences in the VR-MRT were mainly attributed to the selection of visual strategy rather than the rotation processes.The study helps to comprehensively understand the dominant factors contributing to the sex differences in the VR-MRT.展开更多
Achieving passive microparticle filtration with micropore membranes is challenging due to the capillary pinning effect of the membranes.Inspired by the teapot effect that occurs when liquid(tea)is poured from a teapot...Achieving passive microparticle filtration with micropore membranes is challenging due to the capillary pinning effect of the membranes.Inspired by the teapot effect that occurs when liquid(tea)is poured from a teapot spout,we proposed a tap-triggered self-wetting strategy and utilized the method with a 3D sieve to flter rare cells.First,a 3D-printed polymer tap-trigger microstructure was implemented.As a result,the 3μm micropore membrane gating threshold(the pressure needed to open the micropores)was lowered from above 3000 to 80 Pa by the tap-trigger microstructure that facilated the liquid leakage and spreading to self-wet more membrane area in a positive feedback loop.Then,we implemented a 3D cone-shaped cell sieve with tap-trigger microstructures.Driven by gravity,the sieve performed at a high throughput above 20 mL/min(DPBS),while the micropore size and porosity were 3μm and 14.1%,respectively.We further filtered leukocytes from whole blood samples with the proposed new 3D sieve,and the method was compared with the traditional method of leukocyte isolation by chemically removing red blood cells.The device exhibited comparable leukocyte purity but a higher platelet removal rate and lower leukocyte simulation level,facilitating downstream single-cell analysis.The key results indicated that the tap-triggered self-wetting strategy could significantly improve the performance of passive microparticle filtration.展开更多
Historical urban areas are the memory of a city, and the overall Landscape they constitute dispLays the typical scene of a city in a certain historical period. Thus, they are of value for protection. The current study...Historical urban areas are the memory of a city, and the overall Landscape they constitute dispLays the typical scene of a city in a certain historical period. Thus, they are of value for protection. The current study gives an overview on the origin and protection of historical urban areas in the world. Moreover, the study also focuses on the principles, methods, and current problems in the protection of historical urban areas under the guidance of related taws and regulations in China. FinaLLy, some effective measures to protect historicat urban areas are suggested.展开更多
Dirac nodal-line semimetals with the linear bands crossing along a line or loop, represent a new topological state of matter. Here, by carrying out magnetotransport measurements and performing first-principle calculat...Dirac nodal-line semimetals with the linear bands crossing along a line or loop, represent a new topological state of matter. Here, by carrying out magnetotransport measurements and performing first-principle calculations, we demonstrate that such a state has been realized in high-quality single crystals of SrAs_3.We obtain the nontrivial ∏ Berry phase by analysing the Shubnikov-de Haas quantum oscillations. We also observe a robust negative longitudinal magnetoresistance induced by the chiral anomaly.Accompanying first-principles calculations identifies that a single hole pocket enclosing the loop nodes is responsible for these observations.展开更多
In this study we successfully intercalated potassium(K) atoms into single ZrTe_5 crystals by liquid ammonia method, and found a semimetal-to-semiconductor transition at low temperatures in K-intercalated ZrTe_5. As th...In this study we successfully intercalated potassium(K) atoms into single ZrTe_5 crystals by liquid ammonia method, and found a semimetal-to-semiconductor transition at low temperatures in K-intercalated ZrTe_5. As the K concentration increased, the resistance anomalous peak was gradually suppressed until finally disappearing. Whilst, the corresponding Hall resistance measurements consistently showed a sign reversal. The semimetal-to-semiconductor transition can be attributed to a lattice expansion induced by atom intercalation, leading to a larger energy band gap.展开更多
Two-dimensional (2D) anisotropic rhenium diselenide (ReSe2) has attracted lots ofattention due to its promising applications in electronics and optoelectronics. However,controlled synthesis of high quality ultrathin R...Two-dimensional (2D) anisotropic rhenium diselenide (ReSe2) has attracted lots ofattention due to its promising applications in electronics and optoelectronics. However,controlled synthesis of high quality ultrathin ReSe2 remains as a challenge.Here we developed an approach for synthesizing high quality 2D ReSe2 flakes witha thickness down to monolayer by chemical vapor transport (CVT) through carefullytuning the growth kinetics. The atomic structures and anisotropy of theobtained ReSe2 flakes were intensively characterized with scanning transmissionelectron microscope and angle-resolved polarized Raman spectroscopy. Fieldeffecttransistors fabricated on the CVT-grown ReSe2 flakes showed n-typesemiconducting behavior with an on/off current ratio of 105 and a mobility up to5 cm2 V−1 s−1, which is comparable to mechanically exfoliated flakes and isobvious higher than the samples synthesized with other approaches. This study notonly make high quality 2D ReSe2 easily accessible for both fundamental and applicationexplorations but also sheds new lights on the chemical synthesis of otheranisotropic 2D materials.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)[81672119 and 81725010 to W.Z.]W Z is a scholar of‘the National Science Fund for Distinguished Young Scholars’(NSFC)[81725010]+4 种基金the Strategic Priority Research Program of the Chinese Academy of Science(XDA16020400 to P.H.)Ministry of Science and Technology of China(2017YFA0102700 to P.H.)National Natural Science Foundation of China(32170804 to PH)P.H.the fellowship of China Postdoctoral Science Foundation(2021TQ0207,2021M702184 to J.S.)the‘Basic research project of Shanghai Sixth People’s Hospital’(ynqn202102 to J.S.)。
文摘Osteoporosis caused by aging is characterized by reduced bone mass and accumulated adipocytes in the bone marrow cavity. How the balance between osteoblastogenesis and adipogenesis from bone marrow mesenchymal stem cells(BMSCs) is lost upon aging is still unclear. Here, we found that the RNA-binding protein Musashi2(Msi2) regulates BMSC lineage commitment. Msi2 is commonly enriched in stem cells and tumor cells. We found that its expression was downregulated during adipogenic differentiation and upregulated during osteogenic differentiation of BMSCs. Msi2 knockout mice exhibited decreased bone mass with substantial accumulation of marrow adipocytes, similar to aging-induced osteoporosis. Depletion of Msi2 in BMSCs led to increased adipocyte commitment. Transcriptional profiling analysis revealed that Msi2 deficiency led to increased PPARγ signaling.RNA-interacting protein immunoprecipitation assays demonstrated that Msi2 could inhibit the translation of the key adipogenic factor Cebpα, thereby inhibiting PPAR signaling. Furthermore, the expression of Msi2 decreased significantly during the aging process of mice, indicating that decreased Msi2 function during aging contributes to abnormal accumulation of adipocytes in bone marrow and osteoporosis. Thus, our results provide a putative biochemical mechanism for aging-related osteoporosis, suggesting that modulating Msi2 function may benefit the treatment of bone aging.
基金the financial support from the National Key R&D Program of China(Grant No.2020YFA0309602)the National Natural Science Foundation of China(Grant No.11874042)+7 种基金the support from National Natural Science Foundation of China(Grant No.12004250)the support from the National Natural Science Foundation of China(Grant No.12004251)the National Natural Science Foundation of China(Grant Nos.11674326 and 11774351)the start-up funding from Shanghai Tech Universitythe Shanghai Sailing Program(Grant No.20YF1430700)the Shanghai Sailing Program(Grant No.21YF1429200)the support from the National Key R&D Program(Grant No.2021YFA1600201)the Joint Funds of the National Natural Science Foundation of China and the Chinese Academy of Sciences’Large-Scale Scientific Facility(Grant Nos.U1832141,U1932217 and U2032215)。
文摘Realization of Kondo lattice in superconducting van der Waals materials not only provides a unique opportunity for tuning the Kondo lattice behavior by electrical gating or intercalation,but also is helpful for further understanding the heavy fermion superconductivity.Here we report a low-temperature and vector-magneticfield scanning tunneling microscopy and spectroscopy study on a superconducting compound(4Hb-TaS_(2))with alternate stacking of 1T-TaS_(2)and 1H-TaS_(2)layers.We observe the quasi-two-dimensional superconductivity in the 1H-TaS_(2)layer with anisotropic response to the in-plane and out-of-plane magnetic fields.In the 1T-TaS_(2)layer,we detect the Kondo resonance peak that results from the Kondo screening of the unpaired electrons in the Star-of-David clusters.We also find that the intensity of the Kondo resonance peak is sensitive to its relative position with the Fermi level,and it can be significantly enhanced when it is further shifted towards the Fermi level by evaporating Pb atoms onto the 1T-TaS_(2)surface.Our results not only are important for fully understanding the electronic properties of 4Hb-TaS_(2),but also pave the way for creating tunable Kondo lattice in the superconducting van der Waals materials.
基金supported by National Key Research and Development Program of China(Grant No.2021YFA1400400)the National Natural Science Foundation of China(Grant Nos.11822405,12074174,12074175,11774152,11904170,12004249,12004251,and 12004191)+3 种基金the Natural Science Foundation of Jiangsu Province(Grant Nos.BK20180006,BK20190436 and BK20200738)the Shanghai Sailing Program(Grant Nos.20YF1430600 and21YF1429200)the Fundamental Research Funds for the Central Universities(Grant No.020414380183)the Office of International Cooperation and Exchanges of Nanjing University。
文摘It is known that α-RuCl_(3) has been studied extensively because of its proximity to the Kitaev quantum-spin-liquid(QSL)phase and the possibility of approaching it by tuning the competing interactions.Here we present the first polarized inelastic neutron scattering study on α-RuCl_(3) single crystals to explore the scattering continuum around the Γ point at the Brillouin zone center,which was hypothesized to be resulting from the Kitaev QSL state but without concrete evidence.With polarization analyses,we find that,while the spin-wave excitations around the Γ point vanish above the transition temperature T_(N),the pure magnetic continuous excitations around the Γ point are robust against temperature.Furthermore,by calculating the dynamical spin-spin correlation function using the cluster perturbation theory,we derive magnetic dispersion spectra based on the K-Γ model,which involves with a ferromagnetic Kitaev interaction of −7.2 meV and an off-diagonal interaction of 5.6 meV.We find this model can reproduce not only the spin-wave excitation spectra around the Γ point,but also the non-spin-wave continuous magnetic excitations around the Γ point.These results provide evidence for the existence of fractional excitations around the Γ point originating from the Kitaev QSL state,and further support the validity of the K-Γ model as the effective minimal spin model to describe α-RuCl_(3).
基金supported by the National Key R&D Program of China(Grant Nos.2018YFA0704300 and 2017YFB0503302)the National Natural Science Foundation of China(Grant Nos.U1932217,11974246,12004252,61771234,and 12004251)+6 种基金the Natural Science Foundation of Shanghai(Grant Nos.19ZR1477300 and 20ZR1436100)the Science and Technology Commission of Shanghai Municipality(Grant Nos.19JC1413900 and YDZX20203100001438)the Shanghai Science and Technology Plan(Grant No.21DZ2260400),the Shanghai Sailing Program(Grant No.21YF1429200)the Interdisciplinary Program of Wuhan National High Magnetic Field Center(Grant No.WHMFC202124)the Beijing National Laboratory for Condensed Matter Physicsthe support from Analytical Instrumentation Center(Grant No.SPST-AIC10112914)Centre for High-resolution Electron Microscopy(ChEM)(Grant No.EM02161943),SPST,Shanghai Tech University。
文摘As a new type of quantum state of matter hosting low energy relativistic quasiparticles,Weyl semimetals(WSMs)have attracted significant attention for scientific community and potential quantum device applications.In this study,we present a comprehensive investigation of the structural,magnetic,and transport properties of noncentrosymmetric RAl Si(R=Sm,Ce),which have been predicted to be new magnetic WSM candidates.Both samples exhibit nonsaturated magnetoresistance,with about 900%and 80%for Sm Al Si and Ce Al Si,respectively,at temperature of 1.8 K and magnetic field of 9 T.The carrier densities of Sm Al Si and Ce Al Si exhibit remarkable change around magnetic transition temperatures,signifying that the electronic states are sensitive to the magnetic ordering of rare-earth elements.At low temperatures,Sm Al Si reveals prominent Shubnikov–de Haas oscillations associated with the nontrivial Berry phase.High-pressure experiments demonstrate that the magnetic order is robust and survival under high pressure.Our results would yield valuable insights into WSM physics and potentials in applications to next-generation spintronic devices in the RAl Si(R=Sm,Ce)family.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFA1400400)the National Natural Science Foundation of China(Grant Nos.11822405,12074174,12074175,92165205,11904170,12004249,12004251,and 12004191)+1 种基金the Natural Science Foundation of Jiangsu Province(Grant Nos.BK20180006,BK20190436,and BK20200738)the Shanghai Sailing Program(Grant Nos.20YF1430600 and 21YF1429200)。
文摘As one of the most promising Kitaev quantum-spin-liquid(QSL)candidates,α-RuCl_(3)has received a great deal of attention.However,its ground state exhibits a long-range zigzag magnetic order,which defies the QSL phase.Nevertheless,the magnetic order is fragile and can be completely suppressed by applying an external magnetic field.Here,we explore the evolution of magnetic excitations ofα-RuCl;under an in-plane magnetic field,by carrying out inelastic neutron scattering measurements on high-quality single crystals.Under zero field,there exist spin-wave excitations near the M point and a continuum near theΓpoint,which are believed to be associated with the zigzag magnetic order and fractional excitations of the Kitaev QSL state,respectively.By increasing the magnetic field,the spin-wave excitations gradually give way to the continuous excitations.On the verge of the critical fieldμ_(0)H_(c)=7.5 T,the former ones vanish and only the latter ones are left,indicating the emergence of a pure QSL state.By further increasing the field strength,the excitations near theΓpoint become more intense.By following the gap evolution of the excitations near theΓpoint,we are able to establish a phase diagram composed of three interesting phases,including a gapped zigzag order phase at low fields,possibly gapless QSL phase nearμ;H;,and gapped partially polarized phase at high fields.These results demonstrate that an in-plane magnetic field can driveα-RuCl;into a long-sought QSL state near the critical field.
基金Supported by the National Natural Science Foundation of China(Grant Nos.61771234,61727805,11674157,11674158,11774152,11822405,61521001,6157121961501222)+6 种基金the National Key Projects for Research and Development of China(Grant Nos.2016YFA0300401,2017YFB0503302,2017YFA03040022017YFB0503300)the start-up funding from ShanghaiTech University,Innovative Research Team in University(PCSIRT)the Natural Science Foundation of Shanghai Municipality(Grant No.20ZR1436100)the Science and Technology Commission of Shanghai Municipality(Grant No.YDZX20203100001438)Jiangsu Key Laboratory of Advanced Techniques for Manipulating Electromagnetic Waves,Natural Science Foundation of Jiangsu Province(Grant No.BK20180006)the Fundamental Research Funds for the Central Universities(Grant No.020414380117)。
文摘In iron-based superconductors,the(0,π) or(π,0) nematicity,which describes an electronic anisotropy with a fourfold symmetry breaking,is well established and believed to be important for understanding the superconducting mechanism.However,how exactly such a nematic order observed in the normal state can be related to the superconducting pairing is still elusive.Here,by performing angular-dependent in-plane magnetoresistivity using ultra-thin flakes in the steep superconducting transition region,we unveil a nematic superconducting order along the(π,π) direction in electron-doped BaFe_(2-x)Ni_(x)As_(2) from under-doped to heavily overdoped regimes with x=0.065- 0.18.It shows superconducting gap maxima along the(π,π) direction rotated by 45° from the nematicity along(0, π) or(π,0) direction observed in the normal state.A similar(π,π)-type nematicity is also observed in the under-doped and optimally doped hole-type Ba1-yKyFe2 As_(2),with y=0.2-0.5.These results suggest that the(π,π) nematic superconducting order is a universal feature that needs to be taken into account in the superconducting pairing mechanism in iron-based superconductors.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11674157 and 11822405)the Fundamental Research Funds for the Central Universities(Grant No.020414380105)
文摘Quantum spin liquids（QSLs） represent a novel state of matter in which quantum fluctuations prevent the conventional magnetic order from being established, and the spins remain disordered even at zero temperature. There have been many theoretical developments proposing various QSL states. On the other hand, experimental movement was relatively slow largely due to limitations on the candidate materials and difficulties in the measurements. In recent years, the experimental progress has been accelerated. In this topical review, we give a brief summary of experiments on the QSL candidates under magnetic fields. We arrange our discussions by two categories： i） Geometrically-frustrated systems, including triangularlattice compounds YbMgGaO4 and YbZnGaO4, κ-（BEDT-TTF）2 Cu2（CN）3, and EtMe3 Sb[Pd（dmit）2]2, and the kagom′e system ZnCu3（OH）6 Cl2; ii） the Kitaev material α-RuCl3. Among these, we will pay special attention to α-RuCl3, which has been intensively studied by ours and other groups recently. We will present evidence that both supports and rejects the QSL ground state for these materials, based on which we give several perspectives to stimulate further research activities.
基金This study was supported by the National Natural Science Foundation of China(Grant Nos.52272125 and 51902271)the Fundamental Research Funds for the Central Universities(Grant Nos.2682021CX116,2682020CX07,and 2682020CX08)Sichuan Science and Technology Program(Grant Nos.2020YJ0259,2020YJ0072,and 2021YFH0163).We would like to thank Analysis and Testing Center of Southwest Jiaotong University for the assistance on material characterization.
文摘Various material design strategies have been developed to enhance photocatalytic performance of TiO_(2).However,no report is available on applications of the photopiezocatalysis strategy on TiO_(2)due to its lack of piezoelectricity.Here we developed a low-temperature molten salt etching process to create rutile TiO_(2)nanoparticles by etching[MgO_(6)]octahedrons away from MgTiO_(3)by molten NH_(4)Cl,during which a lattice distortion occurred in TiO_(2).The lattice distortion broke the structure symmetry of rutile TiO_(2)and subsequently endowed these rutile TiO_(2)nanoparticles with an unusual piezoelectric response with the maximum effective piezoelectric coefficient(d_(33))of~41.6 pm/V,which had not previously been found in TiO_(2)photocatalysts.Thus,the photopiezocatalysis strategy was applied for the first time to enhance the photocatalytic performance of these TiO_(2)nanoparticles.The creation of lattice distortion to induce piezoelectricity could be extended to other photocatalysts that the photopiezocatalysis strategy has not been applied to and may generate novel functionalities for various technical applications.
文摘Background: C-reactive protein to albumin ratio(CRP/Alb ratio,CAR)has been suggested as a potential prognostic biomarker in lung cancer.This updated systematic review and meta-analysis aimed to assess the association between CAR and lung cancer prognosis in current literature.Methods: A systematic search of databases was conducted to identify relevant studies published up to April 2023.Pooled hazard ratios(HRs)and 95%confidence intervals(CIs)were calculated to assess the association between CAR and overall survival(OS)and progression-free survival(PFS)and recurrence-free survival(RF)in lung cancer patients.Results: This meta-analysis includes 16 studies with a total of 5337 patients,indicating a significant association between higher CAR and poorer OS,PFS,and RFS in lung cancer patients,with a pooled HR of 1.78(95%CI=1.60-1.99),1.57(95%CI=1.36-1.80),and 1.97(95%CI=1.40-2.77),respectively.Conclusions: This updated meta-analysis provides evidence for the potential prognostic role of CAR in lung cancer,suggesting its utility as an effective and noninvasive biomarker for identifying high-risk patients and informing treatment decisions in a cost-effective manner.However,further large-scale studies will be necessary to establish the optimal cut-off value for CAR in lung cancer and confirm the present findings.
基金This work was supported by the National Nature Science Foundation of China(11972066,T2288101,U20A20390,11827803)the National Key Research and Development Plan of China(2020YFC2005902).
文摘Virtual reality(VR)has been a promising tool for developing visuospatial tasks.Among visuospatial tasks,mental rotation tasks are widely used in the assessment of visuospatial ability.Males have a distinct advantage in mental rotation ability compared to females,yet it is generally produced by investigations based on two-dimensional(2D)images on a computer screen.Sex differences in mental rotation tasks with three-dimensional(3D)objects in VR were not fully investigated.It is unclear whether the male's advantages in 2D mental rotation tasks are weakened in 3D tasks.The aim of this study was to provide new insights into the understanding of sex differences in mental rotation tasks presented in VR.Here,we developed a VR mental rotation task(VR-MRT)using 3D objects presented by a head-mounted display(HMD)and used VR-based eye tracking and electroencephalography(EEG)to examine eye movements and neural oscillations for males and females.Our results showed that females preferred a piecemeal strategy compared to males,suggesting a significant sex difference in visual strategy.More importantly,we found no significant sex differences in alpha-band and beta-band oscillations related to rotation processes of VR-MRT.These findings indicated that sex differences in the VR-MRT were mainly attributed to the selection of visual strategy rather than the rotation processes.The study helps to comprehensively understand the dominant factors contributing to the sex differences in the VR-MRT.
基金supported by the National Key Research and Development Program of China(No.2018YFC2001100)the National Natural Science Foundation of China(No.62171441,82071314)the Scientific Research and Equipment Development Project of CAS(YJKYYQ20210031).
文摘Achieving passive microparticle filtration with micropore membranes is challenging due to the capillary pinning effect of the membranes.Inspired by the teapot effect that occurs when liquid(tea)is poured from a teapot spout,we proposed a tap-triggered self-wetting strategy and utilized the method with a 3D sieve to flter rare cells.First,a 3D-printed polymer tap-trigger microstructure was implemented.As a result,the 3μm micropore membrane gating threshold(the pressure needed to open the micropores)was lowered from above 3000 to 80 Pa by the tap-trigger microstructure that facilated the liquid leakage and spreading to self-wet more membrane area in a positive feedback loop.Then,we implemented a 3D cone-shaped cell sieve with tap-trigger microstructures.Driven by gravity,the sieve performed at a high throughput above 20 mL/min(DPBS),while the micropore size and porosity were 3μm and 14.1%,respectively.We further filtered leukocytes from whole blood samples with the proposed new 3D sieve,and the method was compared with the traditional method of leukocyte isolation by chemically removing red blood cells.The device exhibited comparable leukocyte purity but a higher platelet removal rate and lower leukocyte simulation level,facilitating downstream single-cell analysis.The key results indicated that the tap-triggered self-wetting strategy could significantly improve the performance of passive microparticle filtration.
文摘Historical urban areas are the memory of a city, and the overall Landscape they constitute dispLays the typical scene of a city in a certain historical period. Thus, they are of value for protection. The current study gives an overview on the origin and protection of historical urban areas in the world. Moreover, the study also focuses on the principles, methods, and current problems in the protection of historical urban areas under the guidance of related taws and regulations in China. FinaLLy, some effective measures to protect historicat urban areas are suggested.
基金supported by the National Natural Science Foundation of China(11674157,51372112 and 11574133)the National Key Research and Development Plan(2016YFA0300404)the National Basic Research Program of China(2015CB921202)
文摘Dirac nodal-line semimetals with the linear bands crossing along a line or loop, represent a new topological state of matter. Here, by carrying out magnetotransport measurements and performing first-principle calculations, we demonstrate that such a state has been realized in high-quality single crystals of SrAs_3.We obtain the nontrivial ∏ Berry phase by analysing the Shubnikov-de Haas quantum oscillations. We also observe a robust negative longitudinal magnetoresistance induced by the chiral anomaly.Accompanying first-principles calculations identifies that a single hole pocket enclosing the loop nodes is responsible for these observations.
基金supported by the Ministry of Science and Technology of China(Grant Nos.2014CB921103,and 2015CB921203)the National Natural Science Foundation of China(Grant Nos.11774149,11790311,11674157,11674154,51032003,1171101156,11374149,and 11374140)
文摘In this study we successfully intercalated potassium(K) atoms into single ZrTe_5 crystals by liquid ammonia method, and found a semimetal-to-semiconductor transition at low temperatures in K-intercalated ZrTe_5. As the K concentration increased, the resistance anomalous peak was gradually suppressed until finally disappearing. Whilst, the corresponding Hall resistance measurements consistently showed a sign reversal. The semimetal-to-semiconductor transition can be attributed to a lattice expansion induced by atom intercalation, leading to a larger energy band gap.
基金We acknowledge National Natural Science Foundation of China(Nos.21573125 and 21875127)Tsinghua University Initiative Scientific Research Program.
文摘Two-dimensional (2D) anisotropic rhenium diselenide (ReSe2) has attracted lots ofattention due to its promising applications in electronics and optoelectronics. However,controlled synthesis of high quality ultrathin ReSe2 remains as a challenge.Here we developed an approach for synthesizing high quality 2D ReSe2 flakes witha thickness down to monolayer by chemical vapor transport (CVT) through carefullytuning the growth kinetics. The atomic structures and anisotropy of theobtained ReSe2 flakes were intensively characterized with scanning transmissionelectron microscope and angle-resolved polarized Raman spectroscopy. Fieldeffecttransistors fabricated on the CVT-grown ReSe2 flakes showed n-typesemiconducting behavior with an on/off current ratio of 105 and a mobility up to5 cm2 V−1 s−1, which is comparable to mechanically exfoliated flakes and isobvious higher than the samples synthesized with other approaches. This study notonly make high quality 2D ReSe2 easily accessible for both fundamental and applicationexplorations but also sheds new lights on the chemical synthesis of otheranisotropic 2D materials.
