Boron nitride nanotubes （BN-NTs） with pure hexagonal BN phase have been synthesized by heating ball-milled boron powders in flowing ammonia gas at a temperature of 1200℃. The as-synthesized products were characteri...Boron nitride nanotubes （BN-NTs） with pure hexagonal BN phase have been synthesized by heating ball-milled boron powders in flowing ammonia gas at a temperature of 1200℃. The as-synthesized products were characterized by X-ray powder diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, and electron energy loss spectroscopy （EELS）. The diameters of nanotubes are in the rage of 40-120nm and the lengths are more than 10μm. EELS result identifies that the ratio of boron and nitrogen is almost 1：1 The growth temperature is a crucial growth parameter in controlling the structure and crystalline of BN-NTs. The nanotubes grown at 1100℃ possesses of a bamboo-like structure, while as the temperature increased to 1200℃, most of the nanotubes exhibited a cylindrical structure. In addition, changing the heating time can control the size of the nanotubes. The gas atmosphere has influence on the yield of BN-NTs during heating process. When heating atmosphere was replaced by nitrogen, the yield of nanotubes was remarkably decreased.展开更多
The roller-scraper tribosystem of automatic teller machine（ATM） plays an important role in reliable cash requests.However,the abrasive wear of the polymer tribosystem becomes a prominent problem when operating in sa...The roller-scraper tribosystem of automatic teller machine（ATM） plays an important role in reliable cash requests.However,the abrasive wear of the polymer tribosystem becomes a prominent problem when operating in sandy environment.The wear behavior of the tribosystem in a simulated sandy environment has been experimentally studied previously.However the abrasive wear mechanism of roller-scraper tribosystems is still unknown to new design.The wear rates of polymer rollers were examined comprehensively and several jumping variations were found in the full data extent.Three wear stages were classified by the magnitude of wear rates,and different dominant wear mechanisms corresponding with different particle diameter were found by examining the worn surfaces.Accordingly a presumption was proposed that wear mechanisms in different stages were correlated with sand particles of different diameter.In a verification experiment,three typical wear mechanisms including cutting,ploughing,and wedging were found corresponding with different wear stages by scanning electron microscope（SEM） examination.A theoretical analysis was carried out with a simplified sphere particle intrusion model and the transfer conditions for different wear mechanisms were studied referring to the slip-field theory.As a main result,three typical wear models versus friction coefficient of particle/roller,and particle radius were mapped with variant hardness of the polymer roller and ratio of contact shear stress to bulk shear stress.The result illuminated the abrasive wear mechanism during particle intrusion.Particularly,the critical transition conditions gave the basis for improving the wear performance of roller-scraper tribosystems in a sandy environment.展开更多
The self-assembled behavior of an unsymmetric molecule(BCDTDA)with one imidazole group as center and benzoic acid group as functional group is studied,and the regulatory behaviors of coronene(COR)and three bipyridine ...The self-assembled behavior of an unsymmetric molecule(BCDTDA)with one imidazole group as center and benzoic acid group as functional group is studied,and the regulatory behaviors of coronene(COR)and three bipyridine derivatives(named BP,PEBP-C4 and PEBP-C8)on BCDTDA self-assembly structures are also investigated.Based on highly oriented pyrolytic graphite(HOPG)substrate,scanning tunneling microscopy(STM)is used to observe the variation of assembled behaviors at the solid-liquid interface.Because of the concentration effect,BCDTDA molecules can assemble into grids and Kagomés structures in the form of N–H…O hydrogen bonded dimers.BCDTDA molecules still maintain dimeric structures in the regulation of COR and BP molecules to BCDTDA self-assembly.However,PEBP-C4 and PEBP-C8 destroy the structure of the dimers,and form a variety of co-assembled structures with BCDTDA.Different vip molecules coordinate the host molecules differently,which makes the experiment more meaningful.Combined with density functional theory(DFT)calculation,the discovery of molecular interactions provides a promising strategy for the construction of functional nanostructures and devices.展开更多
Tianshanbeilu is the largest Bronze Age site in eastern Xinjiang, China. Stretching across the entire second millennium BC, it performed a prominent role in connecting the Hexi corridor, Central China and the steppe. ...Tianshanbeilu is the largest Bronze Age site in eastern Xinjiang, China. Stretching across the entire second millennium BC, it performed a prominent role in connecting the Hexi corridor, Central China and the steppe. A further insight into the metallurgical tradition and the metal supply network is of vital importance to improve our understanding of its multi-connected nature. This paper offers a new set of chemical and isotopic data on the copper-based objects at Tianshanbeilu, including alloying elements, trace elements(impurities) and lead isotopes. Combining the concentrations of arsenic and antimony reveals that arsenic was introduced to copper partially due to the use of specific minerals tethrahedrite-tennantite. Lead isotopes demonstrate that multiple sources of copper were employed at Tianshanbeilu and a majority of them are characterized by common lead, which appears rather different from those of the Central Plains and the Hexi corridor, but highly consistent with local ores. Surprisingly, one object at Tianshanbeilu contains the well-known highly radiogenic lead. This object undoubtedly marks the westernmost boundary of the distribution of the highly radiogenic lead. We also anticipate that more lead isotopic analyses in NW China will further contribute to the study of the highly radiogenic lead in Central China.展开更多
Polymer matrix RE-Fe giant magnetostrictire composite （GMPC） was prepared using bonding and magnetic field forming technique, and magnetostriction of samples was measured for different compressive stress. The experi...Polymer matrix RE-Fe giant magnetostrictire composite （GMPC） was prepared using bonding and magnetic field forming technique, and magnetostriction of samples was measured for different compressive stress. The experimental results show thai there is certain compressive effect in GMPC. And the influence of compressive stress on magnetostriction of sample was investigated. It offers essential reference for application and device design of GMPC.展开更多
AB5-based hydrogen storage thin fdms （LaNi4.25Al0.75）, deposited on Cu substrate by dc magnetron sputtering were investigated in this study. X-ray diffraction （XRD） revealed that the microstructure of the layer wa...AB5-based hydrogen storage thin fdms （LaNi4.25Al0.75）, deposited on Cu substrate by dc magnetron sputtering were investigated in this study. X-ray diffraction （XRD） revealed that the microstructure of the layer was in crystal form. SEM and AFM analyses proved that the film appeared to be rather rough with numerous randomly sized pores of approximately 15-40 in nm diameter. Structural stability of the film was examined by the combined analyses of DSC, XRD, and SEM, which indicated that this film maintained its structural stability below 500 K or so, and a network structure was observed on the film after being heated at 700 K for 30 min. Electrochemical hydrogen-storage properties of the films were investigated by simulated battery tests. It was found that single-layered LaNi4.25A10.75 film exhibited electrochemical hydrogen-storage properties similar to typical AB5 alloys in bulk, and the maximum discharge capacity of the film was about 220 mAh/g. After 20 charge/discharge cycles, small needle-shaped aluminium oxide was formed on some fractions of the film surface.展开更多
The solar-blind ultraviolet(UV)wavelength is particularly interesting within the range of 200 nm–300 nm.Here,we propose a focusing metalens,focusing vortex beam(VB)metalens and metalens array that specifically work i...The solar-blind ultraviolet(UV)wavelength is particularly interesting within the range of 200 nm–300 nm.Here,we propose a focusing metalens,focusing vortex beam(VB)metalens and metalens array that specifically work in the UV band to focus a beam or VB.Firstly,a high numerical aperture(NA)focusing metalens working at a wavelength of 214.2 nm was designed,and the NA reached 0.83.The corresponding conversion efficiency of the unit structure reached as high as 94%,and the full width at half maximum was only 117.2 nm.Metalenses with large NA can act as optical tweezers and can be applied to trap ultracold atoms and molecules.Secondly,a focused VB metalens in the wavelength range of200 nm–300 nm was also designed,which can convert polarized light into a VB and focus the VB simultaneously.Finally,a metalens array was developed to focus VBs with different topological charges on the same focal plane.This series of UV metalenses could be widely used in UV microscopy,photolithography,photonics communication,etc.展开更多
A newly developed on-line visual ferrograph（OLVF） gives a new way for engine wear state monitoring. However, the reliability of on-line wear debris image processing is challenged in both monitoring ship engines and ...A newly developed on-line visual ferrograph（OLVF） gives a new way for engine wear state monitoring. However, the reliability of on-line wear debris image processing is challenged in both monitoring ship engines and the Caterpillar bench test, which weren＇t reported in previous studies. Two problems were encountered in monitoring engines and processing images. First, small wear debris becomes hard to be identified from the image background after monitoring for a period of time. Second, the identification accuracy for wear debris is greatly reduced by background noise because of oil getting dark after nmning a period of time. Therefore, the methods adopted in image processing are examined. Two main reasons for the problems in wear debris identification are generalized as follows. Generally, the binary threshold was determined by global image pixels, and was easily affected by the non-objective zone in the image. The boundary of the objective zone in the binary image was misrecognized because of oil color becoming lighter during monitoring. Accordingly, improvements were made as follows. The objective zone in a global binary image was identified by scanning a column of pixels, and then a secondary binary process confined in the objective zone was carried out to identify small wear debris. Linear filtering with a specific template was used to depress noise in a binary image, and then a low-pass filtering was performed to eliminate the residual noise. Furthermore, the morphology parameters of single wear debris were extracted by separating each wear debris by a gray stack, and two indexes, WRWR （relative wear rate） and WRWS （relative wear severity）, were proposed for wear description. New indexes were provided for on-line monitoring of engines.展开更多
The performance of optical interconnection has improved dramatically in recent years.Silicon-based optoelectronic heterogeneous integration is the key enabler to achieve high performance optical interconnection,which ...The performance of optical interconnection has improved dramatically in recent years.Silicon-based optoelectronic heterogeneous integration is the key enabler to achieve high performance optical interconnection,which not only provides the optical gain which is absent from native Si substrates and enables complete photonic functionalities on chip,but also improves the system performance through advanced heterogeneous integrated packaging.This paper reviews recent progress of silicon-based optoelectronic heterogeneous integration in high performance optical interconnection.The research status,development trend and application of ultra-low loss optical waveguides,high-speed detectors,high-speed modulators,lasers and 2D,2.5D,3D and monolithic integration are focused on.展开更多
Frequency combs[1, 2] consisting of equally-spaced frequencylines can be fully described by two frequencies, i.e., carrieroffset (fCEO) and repetition rate (frep). Once the two frequenciesare stabilized, the frequency...Frequency combs[1, 2] consisting of equally-spaced frequencylines can be fully described by two frequencies, i.e., carrieroffset (fCEO) and repetition rate (frep). Once the two frequenciesare stabilized, the frequency comb is well defined. Frequencycombs can be used for various applications, i.e., metrology,spectroscopy, timing, communications, absolute distancemeasurements, and so on, due to their two importantcharacteristics, i.e., stabilized frequency lines and ultra-shortoptical pulses (if the mode-locking is obtained) as shown inFig. 1.展开更多
Cholesteric liquid crystal(CLC)particles can adaptively respond to constant changes in external stimuli and thus are widely used in solvent-sensing,pattern fabrication,and anti-counterfeiting.Previous studies discusse...Cholesteric liquid crystal(CLC)particles can adaptively respond to constant changes in external stimuli and thus are widely used in solvent-sensing,pattern fabrication,and anti-counterfeiting.Previous studies discussed the color change at the center of the particles for various applications.However,few studies analyzed the color change of the brush structure of particles in response to various applications because of the complicated birefringence effect.In this paper,we present a novel integrated sensing system based on the synergetic color change from the center and the brush structure of CLC particles.This system provides abundant and additional sensing information relative to the traditional system.CLC particles are prepared by mixing reactive mesogens,a reactive chiral dopant,a non-reactive LC molecule,and a photoinitiator by using a microfluidic device and subsequent photopolymerization.The CLC particles exhibit gorgeous color at the center and brush structure upon various solvent stimuli because of the Bragg reflection and the birefringence effect,which is explained by the possible color-changing mechanism introduced in this paper.For proof-of-concept applications,such color-changing polymer particles are demonstrated in multi-solvent-sensing detection and pattern display.This study provides new insights into the development of stimuli-responsive advanced functional materials with tailorable nanostructures toward technological applications ranging from sensing to display.展开更多
High-performance nanomaterial catalysts for hydrogen evolution reaction via electrochemical water splitting are significant to the development of hydrogen energy.In this work,we report a robust and highly active catal...High-performance nanomaterial catalysts for hydrogen evolution reaction via electrochemical water splitting are significant to the development of hydrogen energy.In this work,we report a robust and highly active catalyst fabricated through direct electrochemical deposition of Pt nanodendrites at the surface of activated carbon(Pt NDs).Owing to the large elect roc he mically active area and the exposed(111) facet of Pt,Pt NDs exhibits outstanding activity towards hydrogen evolution reaction with a low requiring overpotential of 0.027 V at 10 mA/cm2 and Tafel slope of ≈22 mV/dec in acidic media.In addition,the hydrogen yield of Pt NDs is 30%-45% larger than that of commercial Pt/C at the same Pt loadings.Moreover,Pt NDs exhibits excellent lo ng-term durability whose hydrogen production efficiency remains unchanged after six-hour hydrogen production,while the efficiency of commercial Pt/C catalyst decayed 9% under the same circumstance.Considering the superiority of catalytic activity and stability,this Pt NDs present great potentiality towards practical hydrogen production application.展开更多
By using the method of stress functions, the problem of mode-Ⅱ Griffith crack in decagonal quasicrystals was solved. First, the crack problem of two-dimensional quasi-crystals was decomposed into a plane strain state...By using the method of stress functions, the problem of mode-Ⅱ Griffith crack in decagonal quasicrystals was solved. First, the crack problem of two-dimensional quasi-crystals was decomposed into a plane strain state problem superposed on anti-plane state problem and secondly, by introducing stress functions, the 18 basic elasticity equations on coupling phonon-phason field of decagonal quasicrystals were reduced to a single higher- order partial differential equations. The solution of this equation under mixed boundary conditions of mode-Ⅱ Griffith crack was obtained in terms of Fourier transform and dual integral equations methods. All components of stresses and displacements can be expressed by elemental functions and the stress intensity factor and the strain energy release rate were determined.展开更多
We explore the behaviors of optically coupled topological corner states in supercell arrays composed of photonic crystal rods,where each supercell is a second-order topological insulator.Our findings indicate that the...We explore the behaviors of optically coupled topological corner states in supercell arrays composed of photonic crystal rods,where each supercell is a second-order topological insulator.Our findings indicate that the coupled corner states possess nondegenerate eigenfrequencies at theΓpoint,with coupled dipole corner states excited resonantly by incident plane waves and displaying a polarization-independent characteristic.The resonance properties of coupled dipole corner states can be effectively modulated via evanescently near-field coupling,while multipole decomposition shows that they are primarily dominated by electric quadrupole moment and magnetic dipole moment.Furthermore,we demonstrate that these coupled corner states can form surface lattice resonances driven by diffractively far-field coupling,leading to a dramatic increase in the quality factor.This work introduces more optical approaches to tailoring photonic topological states,and holds potential applications in mid-infrared topological micro-nano devices.展开更多
Here, we report an efficient fluorescence biosensor for chondroitin sulfate（CHS） based on polyelectrolyte microspheres of carboxymethyl cellulose（CMC） and chitosan（CS） composites inducing the aggregation of grap...Here, we report an efficient fluorescence biosensor for chondroitin sulfate（CHS） based on polyelectrolyte microspheres of carboxymethyl cellulose（CMC） and chitosan（CS） composites inducing the aggregation of graphene quantum dots（GQDs）, calling CMC/CS-GQDs. The polyelectrolyte microspheres（CMC/CS microspheres） were fabricated by using anioniccationic electrostatic attraction between CMC and CS by high voltage electrostatic spray technology. The aggregating process of GQDs was based on the anionic-cationic electrostatic attraction as well. After combing with the polyelectrolyte microspheres, the fluorescence of GQDs disappeared. CHS, which widely consists in the cell surface of human beings and animals, carries a large number of negative charges on the surface. The addition of CHS enabled CHS and GQDs to compete with each other to composite with the CMC/CS microshpheres. As a result of the higher surface charge density of CHS, CMC/CS-CHS formed accompanied by the release of GQDs, and the fluorescence of the system recovered. The CHS content was detected by analyzing the system＇s fluorescence recovery, which suggested that the obtained fluorescence biosensor can accurately detect the concentration of CHS. The test results showed that the linear range of the fluorescence recovery for this biosensor with respect to CHS was 0~12.00 mg/mL, and the detection limit was 10-8 M. Besides, to test the stability of the biosensor, the CMC/CS-GQDs micropsheres persisted for one month, with a low fluorescence quenching of 9.48%. These results suggested that CMC/CS-GQDs can be utilized as efficient fluorescence biosensor for the detection of CHS. Moreover, the detection method was simple and efficient, and could be widely popularized.展开更多
We study that the different-mode(waveguide-connected)power splitter[(W)PS]can provide different-mode testing points for the optical testing.With the PS or WPS providing two different-mode testing points,the measured i...We study that the different-mode(waveguide-connected)power splitter[(W)PS]can provide different-mode testing points for the optical testing.With the PS or WPS providing two different-mode testing points,the measured insertion losses(ILs)of the three-channel and dual-mode waveguide crossing(WC)for both the fundamental transverse electric(TE0)and TE1 modes are less than 1.8 dB or 1.9 dB from 1540 nm to 1560 nm.At the same time,the crosstalks(CTs)are lower than-17.4 dB or-18.2 dB.The consistent test results indicate the accuracy of the(W)PS-based testing circuit.Additionally,combining the tunable tap couplers,the(W)PS can provide multiple testing points with different modes and different transmittances.展开更多
To achieve photon-pair generation scaling, we optimize the quality factor of microring resonators for efficient continuous-wave-pumped spontaneous four-wave mixing. Numerical studies indicate that a high intrinsic qua...To achieve photon-pair generation scaling, we optimize the quality factor of microring resonators for efficient continuous-wave-pumped spontaneous four-wave mixing. Numerical studies indicate that a high intrinsic quality factor makes high pair rate and pair brightness possible, in which the maximums take place under overcoupling and critical-coupling conditions, respectively. We fabricate six all-pass-type microring resonator samples on a silicon-on-insulator chip involving gap width as the only degree of freedom. The signal count rate, pair brightness,and coincidence rate of all the samples are characterized, which are then compared with the modified simulations by taking the detector saturation and nonlinear loss into account. Being experimentally validated for the first time to the best of our knowledge, this work explicitly demonstrates that reducing the round-trip loss in a ring cavity and designing the corresponding optimized gap width are more effective to generate high-rate or high-brightness photon pairs than the conventional strategy of simply increasing the quality factor.展开更多
Second-order topological insulators(SOTIs) have recently attracted much attention due to their capability to support lower-dimensional topological states, namely, the corner states. Here, we demonstrate that properly ...Second-order topological insulators(SOTIs) have recently attracted much attention due to their capability to support lower-dimensional topological states, namely, the corner states. Here, we demonstrate that properly designed supercell metasurfaces can support photonic corner states, meanwhile further serving as an ideal platform for the implementations of topological polaritons and dynamically reconfigurable corner states by assembling two-dimensional materials. Such metasurfaces consist of an array of finite-sized SOTIs mimicking the twodimensional Su–Schrieffer–Heeger model. We reveal that the topological transition happens in unit cells without the bandgap, and nondegenerate multipolar corner states emerge in the supercell metasurface due to the inter-and intrasupercell coupling effects. Especially since these corner states are above the light line of the metasurface, we realize the collective stimulation of the two dipolar corner states and their superposition state via far-field excitation. By stacking monolayer hexagonal boron nitride film onto the metasurface, we further achieve the topological phonon polaritons through the strong coupling between the corner state and the phonon, which is confirmed by the Rabi splitting as well as anticrossing behavior emerging in the transmission spectra.Furthermore, we reveal the robustness of the corner state and strong coupling by introducing defects into the metasurface. Finally, tunable corner state and strong coupling with on-demand control are realized by assembling monolayer graphene onto the metasurface. Our theoretical study proposes a unique hybrid-material platform for topological polaritonics and reconfigurable topological photonics, which can promote large-area topological applications in practice.展开更多
Ⅰ. OCCURRENCE AND GENERAL FEATURES OF LONGQUAN MAGNESIOAMPHIBOLEThe magnesioamphibole studied in this note was sampled from peridotite block in Longquan tectonic melange zone of Zhejiang Province, China. It appears i...Ⅰ. OCCURRENCE AND GENERAL FEATURES OF LONGQUAN MAGNESIOAMPHIBOLEThe magnesioamphibole studied in this note was sampled from peridotite block in Longquan tectonic melange zone of Zhejiang Province, China. It appears in bunchy or fibrous aggregates around the block. The length of the crystal ranges from several mm to about 1 cm. It presents inchned extinction with cANg= 10°—13°under crossed polars. According to the observation of thin sections, it is known that olivine, tale and serpentine展开更多
基金Supported by the National Natural Science Foundation of China （No.20171007）.
文摘Boron nitride nanotubes （BN-NTs） with pure hexagonal BN phase have been synthesized by heating ball-milled boron powders in flowing ammonia gas at a temperature of 1200℃. The as-synthesized products were characterized by X-ray powder diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, and electron energy loss spectroscopy （EELS）. The diameters of nanotubes are in the rage of 40-120nm and the lengths are more than 10μm. EELS result identifies that the ratio of boron and nitrogen is almost 1：1 The growth temperature is a crucial growth parameter in controlling the structure and crystalline of BN-NTs. The nanotubes grown at 1100℃ possesses of a bamboo-like structure, while as the temperature increased to 1200℃, most of the nanotubes exhibited a cylindrical structure. In addition, changing the heating time can control the size of the nanotubes. The gas atmosphere has influence on the yield of BN-NTs during heating process. When heating atmosphere was replaced by nitrogen, the yield of nanotubes was remarkably decreased.
基金supported by National Natural Science Foundation of China (Grant No. 50905135)National Basic Research Program of China (973 Program, Grant No. 2009CB724404)+1 种基金Key Program of National Natural Science Foundation of China (Grant No. 50935004)China Postdoctoral Science Foundation (Grant No. 201003672)
文摘The roller-scraper tribosystem of automatic teller machine（ATM） plays an important role in reliable cash requests.However,the abrasive wear of the polymer tribosystem becomes a prominent problem when operating in sandy environment.The wear behavior of the tribosystem in a simulated sandy environment has been experimentally studied previously.However the abrasive wear mechanism of roller-scraper tribosystems is still unknown to new design.The wear rates of polymer rollers were examined comprehensively and several jumping variations were found in the full data extent.Three wear stages were classified by the magnitude of wear rates,and different dominant wear mechanisms corresponding with different particle diameter were found by examining the worn surfaces.Accordingly a presumption was proposed that wear mechanisms in different stages were correlated with sand particles of different diameter.In a verification experiment,three typical wear mechanisms including cutting,ploughing,and wedging were found corresponding with different wear stages by scanning electron microscope（SEM） examination.A theoretical analysis was carried out with a simplified sphere particle intrusion model and the transfer conditions for different wear mechanisms were studied referring to the slip-field theory.As a main result,three typical wear models versus friction coefficient of particle/roller,and particle radius were mapped with variant hardness of the polymer roller and ratio of contact shear stress to bulk shear stress.The result illuminated the abrasive wear mechanism during particle intrusion.Particularly,the critical transition conditions gave the basis for improving the wear performance of roller-scraper tribosystems in a sandy environment.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.21972031,12064026 and 22272039)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB36000000)Jilin Chinese Academy of Sciences-Yanshen Technology Co.,Ltd.
文摘The self-assembled behavior of an unsymmetric molecule(BCDTDA)with one imidazole group as center and benzoic acid group as functional group is studied,and the regulatory behaviors of coronene(COR)and three bipyridine derivatives(named BP,PEBP-C4 and PEBP-C8)on BCDTDA self-assembly structures are also investigated.Based on highly oriented pyrolytic graphite(HOPG)substrate,scanning tunneling microscopy(STM)is used to observe the variation of assembled behaviors at the solid-liquid interface.Because of the concentration effect,BCDTDA molecules can assemble into grids and Kagomés structures in the form of N–H…O hydrogen bonded dimers.BCDTDA molecules still maintain dimeric structures in the regulation of COR and BP molecules to BCDTDA self-assembly.However,PEBP-C4 and PEBP-C8 destroy the structure of the dimers,and form a variety of co-assembled structures with BCDTDA.Different vip molecules coordinate the host molecules differently,which makes the experiment more meaningful.Combined with density functional theory(DFT)calculation,the discovery of molecular interactions provides a promising strategy for the construction of functional nanostructures and devices.
基金This work is funded by ERC advanced project FLAME(Flow of Ancient Metal Across Eurasia,670010),Social Science Research Fund of Shaanxi Province China(2014H02)academic fund of Wolfson College(University of Oxford).
文摘Tianshanbeilu is the largest Bronze Age site in eastern Xinjiang, China. Stretching across the entire second millennium BC, it performed a prominent role in connecting the Hexi corridor, Central China and the steppe. A further insight into the metallurgical tradition and the metal supply network is of vital importance to improve our understanding of its multi-connected nature. This paper offers a new set of chemical and isotopic data on the copper-based objects at Tianshanbeilu, including alloying elements, trace elements(impurities) and lead isotopes. Combining the concentrations of arsenic and antimony reveals that arsenic was introduced to copper partially due to the use of specific minerals tethrahedrite-tennantite. Lead isotopes demonstrate that multiple sources of copper were employed at Tianshanbeilu and a majority of them are characterized by common lead, which appears rather different from those of the Central Plains and the Hexi corridor, but highly consistent with local ores. Surprisingly, one object at Tianshanbeilu contains the well-known highly radiogenic lead. This object undoubtedly marks the westernmost boundary of the distribution of the highly radiogenic lead. We also anticipate that more lead isotopic analyses in NW China will further contribute to the study of the highly radiogenic lead in Central China.
文摘Polymer matrix RE-Fe giant magnetostrictire composite （GMPC） was prepared using bonding and magnetic field forming technique, and magnetostriction of samples was measured for different compressive stress. The experimental results show thai there is certain compressive effect in GMPC. And the influence of compressive stress on magnetostriction of sample was investigated. It offers essential reference for application and device design of GMPC.
文摘AB5-based hydrogen storage thin fdms （LaNi4.25Al0.75）, deposited on Cu substrate by dc magnetron sputtering were investigated in this study. X-ray diffraction （XRD） revealed that the microstructure of the layer was in crystal form. SEM and AFM analyses proved that the film appeared to be rather rough with numerous randomly sized pores of approximately 15-40 in nm diameter. Structural stability of the film was examined by the combined analyses of DSC, XRD, and SEM, which indicated that this film maintained its structural stability below 500 K or so, and a network structure was observed on the film after being heated at 700 K for 30 min. Electrochemical hydrogen-storage properties of the films were investigated by simulated battery tests. It was found that single-layered LaNi4.25A10.75 film exhibited electrochemical hydrogen-storage properties similar to typical AB5 alloys in bulk, and the maximum discharge capacity of the film was about 220 mAh/g. After 20 charge/discharge cycles, small needle-shaped aluminium oxide was formed on some fractions of the film surface.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.60907003,61805278,61875168,and 22134005)Chongqing Science Funds for Distinguished Young Scientists(Grant No.cstc2021jcyj-jqX0027)+6 种基金Innovation Research 2035 Pilot Plan of Southwest University(Grant No.SWU-XDPY22012)China Postdoctoral Science Foundation(Grant No.2018M633704)Innovation Support Program for Overseas Students in Chongqing(Grant No.cx2021008)Foundation of NUDT(Grant Nos.JC13-02-13 and ZK17-0301)Hunan Provincial Natural Science Foundation of China(Grant No.13JJ3001)Program for New Century Excellent Talents in University(Grant No.NCET-12-0142)Chongqing Talents Program for Outstanding Scientists(Grant No.cstc2021ycjh-bgzxm0178)。
文摘The solar-blind ultraviolet(UV)wavelength is particularly interesting within the range of 200 nm–300 nm.Here,we propose a focusing metalens,focusing vortex beam(VB)metalens and metalens array that specifically work in the UV band to focus a beam or VB.Firstly,a high numerical aperture(NA)focusing metalens working at a wavelength of 214.2 nm was designed,and the NA reached 0.83.The corresponding conversion efficiency of the unit structure reached as high as 94%,and the full width at half maximum was only 117.2 nm.Metalenses with large NA can act as optical tweezers and can be applied to trap ultracold atoms and molecules.Secondly,a focused VB metalens in the wavelength range of200 nm–300 nm was also designed,which can convert polarized light into a VB and focus the VB simultaneously.Finally,a metalens array was developed to focus VBs with different topological charges on the same focal plane.This series of UV metalenses could be widely used in UV microscopy,photolithography,photonics communication,etc.
基金supported by National Basic Research Program of China (973 Program, Grant No. 2009CB724404)National Hitech Research and Development Program of China (863 Program, Grant No. 2006AA04Z431)National Natural Science Foundation of China (Grant No. 50905135)
文摘A newly developed on-line visual ferrograph（OLVF） gives a new way for engine wear state monitoring. However, the reliability of on-line wear debris image processing is challenged in both monitoring ship engines and the Caterpillar bench test, which weren＇t reported in previous studies. Two problems were encountered in monitoring engines and processing images. First, small wear debris becomes hard to be identified from the image background after monitoring for a period of time. Second, the identification accuracy for wear debris is greatly reduced by background noise because of oil getting dark after nmning a period of time. Therefore, the methods adopted in image processing are examined. Two main reasons for the problems in wear debris identification are generalized as follows. Generally, the binary threshold was determined by global image pixels, and was easily affected by the non-objective zone in the image. The boundary of the objective zone in the binary image was misrecognized because of oil color becoming lighter during monitoring. Accordingly, improvements were made as follows. The objective zone in a global binary image was identified by scanning a column of pixels, and then a secondary binary process confined in the objective zone was carried out to identify small wear debris. Linear filtering with a specific template was used to depress noise in a binary image, and then a low-pass filtering was performed to eliminate the residual noise. Furthermore, the morphology parameters of single wear debris were extracted by separating each wear debris by a gray stack, and two indexes, WRWR （relative wear rate） and WRWS （relative wear severity）, were proposed for wear description. New indexes were provided for on-line monitoring of engines.
基金Project supported in part by the National Key Research and Development Program of China(Grant No.2021YFB2206504)the National Natural Science Foundation of China(Grant No.62235017)the China Postdoctoral Science Foundation(Grant No.2021M703125).
文摘The performance of optical interconnection has improved dramatically in recent years.Silicon-based optoelectronic heterogeneous integration is the key enabler to achieve high performance optical interconnection,which not only provides the optical gain which is absent from native Si substrates and enables complete photonic functionalities on chip,but also improves the system performance through advanced heterogeneous integrated packaging.This paper reviews recent progress of silicon-based optoelectronic heterogeneous integration in high performance optical interconnection.The research status,development trend and application of ultra-low loss optical waveguides,high-speed detectors,high-speed modulators,lasers and 2D,2.5D,3D and monolithic integration are focused on.
基金supported by the "Hundred-Talent" Program of Chinese Academy of Sciencesthe National Natural Science Foundation of China(61875220,61575214,61404150,61405233,and 61704181)+1 种基金the National Key R&D Program of China(2017YFF0106302 and 2017YFA0701005)Shanghai Municipal Commission of Science and Technology(17YF1430000)
文摘Frequency combs[1, 2] consisting of equally-spaced frequencylines can be fully described by two frequencies, i.e., carrieroffset (fCEO) and repetition rate (frep). Once the two frequenciesare stabilized, the frequency comb is well defined. Frequencycombs can be used for various applications, i.e., metrology,spectroscopy, timing, communications, absolute distancemeasurements, and so on, due to their two importantcharacteristics, i.e., stabilized frequency lines and ultra-shortoptical pulses (if the mode-locking is obtained) as shown inFig. 1.
基金supported by the Ministry of Science and Technology of the People’s Republic of China(2017YFA0204504)the National Natural Science Foundation of China(51873221,52073292,51673207,and 51373183)Chinese Academy of Sciences and Dutch Research Project(1A111KYSB20190072)。
文摘Cholesteric liquid crystal(CLC)particles can adaptively respond to constant changes in external stimuli and thus are widely used in solvent-sensing,pattern fabrication,and anti-counterfeiting.Previous studies discussed the color change at the center of the particles for various applications.However,few studies analyzed the color change of the brush structure of particles in response to various applications because of the complicated birefringence effect.In this paper,we present a novel integrated sensing system based on the synergetic color change from the center and the brush structure of CLC particles.This system provides abundant and additional sensing information relative to the traditional system.CLC particles are prepared by mixing reactive mesogens,a reactive chiral dopant,a non-reactive LC molecule,and a photoinitiator by using a microfluidic device and subsequent photopolymerization.The CLC particles exhibit gorgeous color at the center and brush structure upon various solvent stimuli because of the Bragg reflection and the birefringence effect,which is explained by the possible color-changing mechanism introduced in this paper.For proof-of-concept applications,such color-changing polymer particles are demonstrated in multi-solvent-sensing detection and pattern display.This study provides new insights into the development of stimuli-responsive advanced functional materials with tailorable nanostructures toward technological applications ranging from sensing to display.
基金financial support by the National Natural Science Foundation of China(Nos.51573201,51501209 and 201675165)NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Informatization(No.U1709205)+6 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA22000000)Scientific Instrument Developing Project of the Chinese Academy of Sciences(No.YZ201640)Science and Technology Major Project of Ningbo(Nos.2016S1002,2016B10038)International S&T Cooperation Program of Ningbo(No.2017D10016)for financial supportthe Chinese Academy of Sciences for Hundred Talents ProgramChinese Central Government for Thousand Young Talents Program3315 Program of Ningbo。
文摘High-performance nanomaterial catalysts for hydrogen evolution reaction via electrochemical water splitting are significant to the development of hydrogen energy.In this work,we report a robust and highly active catalyst fabricated through direct electrochemical deposition of Pt nanodendrites at the surface of activated carbon(Pt NDs).Owing to the large elect roc he mically active area and the exposed(111) facet of Pt,Pt NDs exhibits outstanding activity towards hydrogen evolution reaction with a low requiring overpotential of 0.027 V at 10 mA/cm2 and Tafel slope of ≈22 mV/dec in acidic media.In addition,the hydrogen yield of Pt NDs is 30%-45% larger than that of commercial Pt/C at the same Pt loadings.Moreover,Pt NDs exhibits excellent lo ng-term durability whose hydrogen production efficiency remains unchanged after six-hour hydrogen production,while the efficiency of commercial Pt/C catalyst decayed 9% under the same circumstance.Considering the superiority of catalytic activity and stability,this Pt NDs present great potentiality towards practical hydrogen production application.
文摘By using the method of stress functions, the problem of mode-Ⅱ Griffith crack in decagonal quasicrystals was solved. First, the crack problem of two-dimensional quasi-crystals was decomposed into a plane strain state problem superposed on anti-plane state problem and secondly, by introducing stress functions, the 18 basic elasticity equations on coupling phonon-phason field of decagonal quasicrystals were reduced to a single higher- order partial differential equations. The solution of this equation under mixed boundary conditions of mode-Ⅱ Griffith crack was obtained in terms of Fourier transform and dual integral equations methods. All components of stresses and displacements can be expressed by elemental functions and the stress intensity factor and the strain energy release rate were determined.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.62275271,12272407,and 62275269)the National Key Research and Development Program of China (Grant No.2022YFF0706005)+1 种基金the Natural Science Foundation of Hunan Province,China (Grant Nos.2023JJ40683,2022JJ40552,and 2020JJ5646)the Program for New Century Excellent Talents in University,China (Grant No.NCET-12-0142)。
文摘We explore the behaviors of optically coupled topological corner states in supercell arrays composed of photonic crystal rods,where each supercell is a second-order topological insulator.Our findings indicate that the coupled corner states possess nondegenerate eigenfrequencies at theΓpoint,with coupled dipole corner states excited resonantly by incident plane waves and displaying a polarization-independent characteristic.The resonance properties of coupled dipole corner states can be effectively modulated via evanescently near-field coupling,while multipole decomposition shows that they are primarily dominated by electric quadrupole moment and magnetic dipole moment.Furthermore,we demonstrate that these coupled corner states can form surface lattice resonances driven by diffractively far-field coupling,leading to a dramatic increase in the quality factor.This work introduces more optical approaches to tailoring photonic topological states,and holds potential applications in mid-infrared topological micro-nano devices.
文摘Here, we report an efficient fluorescence biosensor for chondroitin sulfate（CHS） based on polyelectrolyte microspheres of carboxymethyl cellulose（CMC） and chitosan（CS） composites inducing the aggregation of graphene quantum dots（GQDs）, calling CMC/CS-GQDs. The polyelectrolyte microspheres（CMC/CS microspheres） were fabricated by using anioniccationic electrostatic attraction between CMC and CS by high voltage electrostatic spray technology. The aggregating process of GQDs was based on the anionic-cationic electrostatic attraction as well. After combing with the polyelectrolyte microspheres, the fluorescence of GQDs disappeared. CHS, which widely consists in the cell surface of human beings and animals, carries a large number of negative charges on the surface. The addition of CHS enabled CHS and GQDs to compete with each other to composite with the CMC/CS microshpheres. As a result of the higher surface charge density of CHS, CMC/CS-CHS formed accompanied by the release of GQDs, and the fluorescence of the system recovered. The CHS content was detected by analyzing the system＇s fluorescence recovery, which suggested that the obtained fluorescence biosensor can accurately detect the concentration of CHS. The test results showed that the linear range of the fluorescence recovery for this biosensor with respect to CHS was 0~12.00 mg/mL, and the detection limit was 10-8 M. Besides, to test the stability of the biosensor, the CMC/CS-GQDs micropsheres persisted for one month, with a low fluorescence quenching of 9.48%. These results suggested that CMC/CS-GQDs can be utilized as efficient fluorescence biosensor for the detection of CHS. Moreover, the detection method was simple and efficient, and could be widely popularized.
基金supported by the National Key Research&Development Program of China(Grant No.2022YFF0706005)National Natural Science Foundation of China(Grant Nos.12272407,62275269,62275271,and 62305387)+4 种基金Foundation of National University of Defense Technology of China(Grant No.ZK23-03)Hunan Provincial Natural Science Foundation of China(Grant Nos.2022JJ40552 and 2023JJ40683)State Key Laboratory of High Performance Computing,National University of Defense Technology of China(Grant No.202201-12)the Hunan Provincial Innovation Foundation for Postgraduate,China(Grant No.CX20230009)State Key Laboratory of High Performance Computing,National University of Defense Technology of China(Grant No.202201-12).
文摘We study that the different-mode(waveguide-connected)power splitter[(W)PS]can provide different-mode testing points for the optical testing.With the PS or WPS providing two different-mode testing points,the measured insertion losses(ILs)of the three-channel and dual-mode waveguide crossing(WC)for both the fundamental transverse electric(TE0)and TE1 modes are less than 1.8 dB or 1.9 dB from 1540 nm to 1560 nm.At the same time,the crosstalks(CTs)are lower than-17.4 dB or-18.2 dB.The consistent test results indicate the accuracy of the(W)PS-based testing circuit.Additionally,combining the tunable tap couplers,the(W)PS can provide multiple testing points with different modes and different transmittances.
基金National Natural Science Foundation of China(NSFC)(60907003)Natural Science Foundation of Hunan Province,China(13JJ3001)+2 种基金Program for New Century Excellent Talents in University(NCET),China(NCET-12-0142)Danmarks Grundforskningsfond(DNRF)(DNRF123)China Scholarship Council(CSC)
文摘To achieve photon-pair generation scaling, we optimize the quality factor of microring resonators for efficient continuous-wave-pumped spontaneous four-wave mixing. Numerical studies indicate that a high intrinsic quality factor makes high pair rate and pair brightness possible, in which the maximums take place under overcoupling and critical-coupling conditions, respectively. We fabricate six all-pass-type microring resonator samples on a silicon-on-insulator chip involving gap width as the only degree of freedom. The signal count rate, pair brightness,and coincidence rate of all the samples are characterized, which are then compared with the modified simulations by taking the detector saturation and nonlinear loss into account. Being experimentally validated for the first time to the best of our knowledge, this work explicitly demonstrates that reducing the round-trip loss in a ring cavity and designing the corresponding optimized gap width are more effective to generate high-rate or high-brightness photon pairs than the conventional strategy of simply increasing the quality factor.
基金National Natural Science Foundation of China(60907003,61805278,62005107)China Postdoctoral Science Foundation(2018M633704)+4 种基金National University of Defense Technology(JC13-02-13,ZK17-03-01)Natural Science Foundation of Hunan Province(13JJ3001)Program for New Century Excellent Talents in University(NCET-12-0142)Hunan Provincial Innovation Foundation for Postgraduate(CX20200039)Natural Science Research of Jiangsu Higher Education Institutions of China(20KJB140007).
文摘Second-order topological insulators(SOTIs) have recently attracted much attention due to their capability to support lower-dimensional topological states, namely, the corner states. Here, we demonstrate that properly designed supercell metasurfaces can support photonic corner states, meanwhile further serving as an ideal platform for the implementations of topological polaritons and dynamically reconfigurable corner states by assembling two-dimensional materials. Such metasurfaces consist of an array of finite-sized SOTIs mimicking the twodimensional Su–Schrieffer–Heeger model. We reveal that the topological transition happens in unit cells without the bandgap, and nondegenerate multipolar corner states emerge in the supercell metasurface due to the inter-and intrasupercell coupling effects. Especially since these corner states are above the light line of the metasurface, we realize the collective stimulation of the two dipolar corner states and their superposition state via far-field excitation. By stacking monolayer hexagonal boron nitride film onto the metasurface, we further achieve the topological phonon polaritons through the strong coupling between the corner state and the phonon, which is confirmed by the Rabi splitting as well as anticrossing behavior emerging in the transmission spectra.Furthermore, we reveal the robustness of the corner state and strong coupling by introducing defects into the metasurface. Finally, tunable corner state and strong coupling with on-demand control are realized by assembling monolayer graphene onto the metasurface. Our theoretical study proposes a unique hybrid-material platform for topological polaritonics and reconfigurable topological photonics, which can promote large-area topological applications in practice.
文摘Ⅰ. OCCURRENCE AND GENERAL FEATURES OF LONGQUAN MAGNESIOAMPHIBOLEThe magnesioamphibole studied in this note was sampled from peridotite block in Longquan tectonic melange zone of Zhejiang Province, China. It appears in bunchy or fibrous aggregates around the block. The length of the crystal ranges from several mm to about 1 cm. It presents inchned extinction with cANg= 10°—13°under crossed polars. According to the observation of thin sections, it is known that olivine, tale and serpentine
