The binary polyhydrides of heavy rare earth lutetium that shares a similar valence electron configuration to lanthanum have been experimentally discovered to be superconductive.The lutetium polyhydrides were successfu...The binary polyhydrides of heavy rare earth lutetium that shares a similar valence electron configuration to lanthanum have been experimentally discovered to be superconductive.The lutetium polyhydrides were successfully synthesized at high pressure and high temperature conditions using a diamond anvil cell in combinations with the in-situ high pressure laser heating technique.The resistance measurements as a function of temperature were performed at the same pressure of synthesis in order to study the transitions of superconductivity(SC).The superconducting transition with a maximum onset temperature(Tc)71 K was observed at pressure of 218 GPa in the experiments.The Tcdecreased to 65 K when pressure was at 181 GPa.From the evolution of SC at applied magnetic fields,the upper critical field at zero temperatureμ0Hc2(0)was obtained to be~36 T.The in-situ high pressure X-ray diffraction experiments imply that the high TcSC should arise from the Lu4H23phase with Pm3n symmetry that forms a new type of hydrogen cage framework different from those reported for previous light rare earth polyhydride superconductors.展开更多
The tribological behavior of AlCr_(0.5)NbTa_(x)Ti_(4-x)(x=0,0.5,and 1)refractory high-entropy alloys was systematically investigated from room temperature to 800℃.The relationship between the alloy composition,micros...The tribological behavior of AlCr_(0.5)NbTa_(x)Ti_(4-x)(x=0,0.5,and 1)refractory high-entropy alloys was systematically investigated from room temperature to 800℃.The relationship between the alloy composition,microstructure,mechanical properties,and tribological performance was analyzed.The results show that all three alloys have a body-centered cubic(bcc)single-phase structure.The Ta addition enhances solid solution strengthening and increases the melting point that would resist high-temperature thermal softening.As a result,high-temperature strength is enhanced considerably,the coefficients of friction(COF)and wear rates of the alloys are reduced considerably at elevated temperatures,demonstrating excellent friction-reducing and anti-wear properties,e.g.,the COF and wear rate of AlCr_(0.5) NbTaTi_(3) alloy at 800℃ are 0.34 and 4.40×10^(-7) mm^(3) N^(-1) m^(-1),respectively.The excellent wear resistance at high temperatures can be attributed to the formation of an oxide-tribo layer(Ta_(2)O_(5) and TiO_(2))with ultrafine-grained layers and good high-temperature mechanical properties.展开更多
The capability to sense complex pressure variations comprehensively is vital for wearable electronics and flexible human–machine interfaces.In this paper,inspired by button switches,a duplex tactile sensor based on t...The capability to sense complex pressure variations comprehensively is vital for wearable electronics and flexible human–machine interfaces.In this paper,inspired by button switches,a duplex tactile sensor based on the combination of triboelectric and piezoresistive effects is designed and fabricated.Because of its excellent mechanical strength and electrical stability,a double-networked ionic hydrogel is used as both the conductive electrode and elastic current regulator.In addition,micro-pyramidal patterned polydimethylsiloxane(PDMS)acts as both the friction layer and the encapsulation elastomer,thereby boosting the triboelectric output performance significantly.The duplex hydrogel sensor demonstrates comprehensive sensing ability in detecting the whole stimulation process including the dynamic and static pressures.The dynamic stress intensity(10–300 Pa),the action time,and the static variations(increase and decrease)of the pressure can be identified precisely from the dual-channel signals.Combined with a signal processing module,an intelligent visible door lamp is achieved for monitoring the entire“contact–hold–release–separation”state of the external stimulation,which shows great application potential for future smart robot e-skin and flexible electronics.展开更多
Abnormal expression of hydrogen peroxide(H_(2)O_(2))indicates the disorder of cell functions and is able to induce the occurrence and deterioration of numerous diseases.However,limited by its low concentration under p...Abnormal expression of hydrogen peroxide(H_(2)O_(2))indicates the disorder of cell functions and is able to induce the occurrence and deterioration of numerous diseases.However,limited by its low concentration under pathophysiological conditions,intracellular H_(2)O_(2) is still difficult to be determined to date.Herein,to achieve sensitive quantification of H_(2)O_(2) in cells,CIS/ZnS/ZnS quantum dots(CIS/d-ZnS QDs)are retrofitted with ZnO shells via self-passivation.Different from the traditional self-passivation of QDs,self-passivation of CIS/d-ZnS QDs is realized facilely without the assistance of additional cation ions,which improves optical properties of QDs and equips the QDs with a sensing layer.As a result,the CIS/d-ZnS/ZnO QDs exhibit enhanced fluorescence emission and stability.Relying on the decomposition of ZnO and ZnS shells in the presence of H_(2)O_(2),aggregated QDs reveal exciton energy transfer effect,resulting in fluorescence quenching.On a basis of this principle,a fluorescence H_(2)O_(2) sensor is further established with the CIS/d-ZnS/ZnO QDs.To be noted,since the equipped ZnO shells are more susceptible to H2O2 than original ZnS shells,analytical performance of the fluorescence sensor is remarkably promoted by the self-passivation of QDs.Accordingly,H_(2)O_(2) can be measured in 5 orders of magnitude with a limit of detection(LOD)of 0.46 nM.Furthermore,because the ZnO shells improve H2O2-responsive selectivity and sensitivity,variation of H_(2)O_(2) in cells can also be quantified with the CIS/d-ZnS/ZnO QDs.In this work,sensitive detection of intracellular H_(2)O_(2) is enabled by equipping QDs with a sensing layer,which provides an alternative perspective of functionalizing nanomaterials for analytical applications.展开更多
Superconductivity is one of most intriguing quantum phenomena,and the quest for elemental superconductors with high critical temperature(T_(c))is of great scientific significance due to their relatively simple materia...Superconductivity is one of most intriguing quantum phenomena,and the quest for elemental superconductors with high critical temperature(T_(c))is of great scientific significance due to their relatively simple material composition and the underlying mechanism.Here we report the experimental discovery of densely compressed scandium(Sc)becoming the first elemental superconductor with T_(c)breaking into 30 K range,which is comparable to the T_(c)values of the classic La-Ba-Cu-O or LaFeAsO superconductors.Our results show that T_(c)^(onset)of Sc increases from~3K at around 43GPa to~32K at about 283GPa(T_(c)^(zero)~31 K),which is well above liquid neon temperature.Interestingly,measured T_(c)shows no sign of saturation up to the maximum pressure achieved in our experiments,indicating that T_(c)may be even higher upon further compression.展开更多
基金supported by the Natural Science Foundation of Chinathe National Key R&D Program of ChinaChinese Academy of Sciences through research projects(Grant Nos.2018YFA0305700,2021YFA1401-800,and XDB33010200)。
文摘The binary polyhydrides of heavy rare earth lutetium that shares a similar valence electron configuration to lanthanum have been experimentally discovered to be superconductive.The lutetium polyhydrides were successfully synthesized at high pressure and high temperature conditions using a diamond anvil cell in combinations with the in-situ high pressure laser heating technique.The resistance measurements as a function of temperature were performed at the same pressure of synthesis in order to study the transitions of superconductivity(SC).The superconducting transition with a maximum onset temperature(Tc)71 K was observed at pressure of 218 GPa in the experiments.The Tcdecreased to 65 K when pressure was at 181 GPa.From the evolution of SC at applied magnetic fields,the upper critical field at zero temperatureμ0Hc2(0)was obtained to be~36 T.The in-situ high pressure X-ray diffraction experiments imply that the high TcSC should arise from the Lu4H23phase with Pm3n symmetry that forms a new type of hydrogen cage framework different from those reported for previous light rare earth polyhydride superconductors.
基金support from the National Key Research and Development Program(No.2022YFB3705300)National Natural Science Foundation of China(Grant No.52004224)Fundamental Research Funds for the Central Universities of China(No.3102019JC001).
文摘The tribological behavior of AlCr_(0.5)NbTa_(x)Ti_(4-x)(x=0,0.5,and 1)refractory high-entropy alloys was systematically investigated from room temperature to 800℃.The relationship between the alloy composition,microstructure,mechanical properties,and tribological performance was analyzed.The results show that all three alloys have a body-centered cubic(bcc)single-phase structure.The Ta addition enhances solid solution strengthening and increases the melting point that would resist high-temperature thermal softening.As a result,high-temperature strength is enhanced considerably,the coefficients of friction(COF)and wear rates of the alloys are reduced considerably at elevated temperatures,demonstrating excellent friction-reducing and anti-wear properties,e.g.,the COF and wear rate of AlCr_(0.5) NbTaTi_(3) alloy at 800℃ are 0.34 and 4.40×10^(-7) mm^(3) N^(-1) m^(-1),respectively.The excellent wear resistance at high temperatures can be attributed to the formation of an oxide-tribo layer(Ta_(2)O_(5) and TiO_(2))with ultrafine-grained layers and good high-temperature mechanical properties.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.51705429 and 61801525)the Fundamental Research Funds for the Central Universities,Guangdong Natural Science Funds(Grant No.2018A030313400).
文摘The capability to sense complex pressure variations comprehensively is vital for wearable electronics and flexible human–machine interfaces.In this paper,inspired by button switches,a duplex tactile sensor based on the combination of triboelectric and piezoresistive effects is designed and fabricated.Because of its excellent mechanical strength and electrical stability,a double-networked ionic hydrogel is used as both the conductive electrode and elastic current regulator.In addition,micro-pyramidal patterned polydimethylsiloxane(PDMS)acts as both the friction layer and the encapsulation elastomer,thereby boosting the triboelectric output performance significantly.The duplex hydrogel sensor demonstrates comprehensive sensing ability in detecting the whole stimulation process including the dynamic and static pressures.The dynamic stress intensity(10–300 Pa),the action time,and the static variations(increase and decrease)of the pressure can be identified precisely from the dual-channel signals.Combined with a signal processing module,an intelligent visible door lamp is achieved for monitoring the entire“contact–hold–release–separation”state of the external stimulation,which shows great application potential for future smart robot e-skin and flexible electronics.
基金This work was supported by the National Natural Science Foundation of China(Nos.21625502,21974070,and 22176099)the Natural Science Foundation of Jiangsu Province of China(Nos.BK20191367 and BK20192008).
文摘Abnormal expression of hydrogen peroxide(H_(2)O_(2))indicates the disorder of cell functions and is able to induce the occurrence and deterioration of numerous diseases.However,limited by its low concentration under pathophysiological conditions,intracellular H_(2)O_(2) is still difficult to be determined to date.Herein,to achieve sensitive quantification of H_(2)O_(2) in cells,CIS/ZnS/ZnS quantum dots(CIS/d-ZnS QDs)are retrofitted with ZnO shells via self-passivation.Different from the traditional self-passivation of QDs,self-passivation of CIS/d-ZnS QDs is realized facilely without the assistance of additional cation ions,which improves optical properties of QDs and equips the QDs with a sensing layer.As a result,the CIS/d-ZnS/ZnO QDs exhibit enhanced fluorescence emission and stability.Relying on the decomposition of ZnO and ZnS shells in the presence of H_(2)O_(2),aggregated QDs reveal exciton energy transfer effect,resulting in fluorescence quenching.On a basis of this principle,a fluorescence H_(2)O_(2) sensor is further established with the CIS/d-ZnS/ZnO QDs.To be noted,since the equipped ZnO shells are more susceptible to H2O2 than original ZnS shells,analytical performance of the fluorescence sensor is remarkably promoted by the self-passivation of QDs.Accordingly,H_(2)O_(2) can be measured in 5 orders of magnitude with a limit of detection(LOD)of 0.46 nM.Furthermore,because the ZnO shells improve H2O2-responsive selectivity and sensitivity,variation of H_(2)O_(2) in cells can also be quantified with the CIS/d-ZnS/ZnO QDs.In this work,sensitive detection of intracellular H_(2)O_(2) is enabled by equipping QDs with a sensing layer,which provides an alternative perspective of functionalizing nanomaterials for analytical applications.
基金supported by the National Key R&D Program of China(Grant No.2021YFA1401800,2022YFA1403800,and 2022YFA1403900)the National Natural Science Foundation of China(Grant Nos.11921004 and U2032220)+1 种基金Chinese Academy of Sciences(Grant No.XDB33010200)NSERC Canada for a Discovery Grant。
文摘Superconductivity is one of most intriguing quantum phenomena,and the quest for elemental superconductors with high critical temperature(T_(c))is of great scientific significance due to their relatively simple material composition and the underlying mechanism.Here we report the experimental discovery of densely compressed scandium(Sc)becoming the first elemental superconductor with T_(c)breaking into 30 K range,which is comparable to the T_(c)values of the classic La-Ba-Cu-O or LaFeAsO superconductors.Our results show that T_(c)^(onset)of Sc increases from~3K at around 43GPa to~32K at about 283GPa(T_(c)^(zero)~31 K),which is well above liquid neon temperature.Interestingly,measured T_(c)shows no sign of saturation up to the maximum pressure achieved in our experiments,indicating that T_(c)may be even higher upon further compression.
