Surface-enhanced Raman Spectroscopy(SERS)is a nondestructive technique for rapid detection of analytes even at the single-molecule level.However,highly sensitive and reliable SERS substrates are mostly fabricated with...Surface-enhanced Raman Spectroscopy(SERS)is a nondestructive technique for rapid detection of analytes even at the single-molecule level.However,highly sensitive and reliable SERS substrates are mostly fabricated with complex nanofabrication techniques,greatly restricting their practical applications.A convenient electrochemical method for transforming the surface of commercial gold wires/foils into silver-alloyed nanostructures is demonstrated in this report.Au substrates are treated with repetitive anodic and cathodic bias in an electrolyte of thiourea,in a one-pot one-step manner.X-rays absorption fine structure(XAFS)spectroscopy confirms that the AuAg alloy is induced at the surface.The unique AuAg alloyed surface nanostructures are particularly advantageous when served as SERS substrates,enabling a remarkably sensitive detection of Rhodamine B(a detection limit of 10^(-14)M,and uniform strong response throughout the substrates at 10^(-12)M).展开更多
Optical emission spectroscopy （OES） was used to study the gas phase composition near the substrate surface during diamond deposition by high-power DC arc plasma jet chemical vapor deposition （CVD）. C2 radical was ...Optical emission spectroscopy （OES） was used to study the gas phase composition near the substrate surface during diamond deposition by high-power DC arc plasma jet chemical vapor deposition （CVD）. C2 radical was determined as the main carbon radical in this plasma atmosphere. The deposition parameters, such as substrate temperature, anode-substrate distance, methane concentration, and gas flow rate, were inspected to find out the influence on the gas phase. A strong dependence of the concentrations and distribution of radicals on substrate temperature was confirmed by the design of experiments （DOE）. An explanation for this dependence could be that radicals near the substrate surface may have additional ionization or dissociation and also have recombination, or are consumed on the substrate surface where chemical reactions occur.展开更多
Classical theory of heterogeneous nucleation has been developed with an implied hypothesis of smooth substrate surfaces; however, morphologies of any real substrate surfaces are generally complicated and demonstrate f...Classical theory of heterogeneous nucleation has been developed with an implied hypothesis of smooth substrate surfaces; however, morphologies of any real substrate surfaces are generally complicated and demonstrate fractal characteristics. In this paper, the wettability between the embryo and the fractal substrate surface was discussed, and heterogeneous nucleation behaviors were theoretically analyzed. The result shows that the roughness factor of a fractal surface varies with the scale of the embryo. As a result, the fractal character of the substrate surface has important effects on heterogeneous nucleation behaviors. It has been shown that the energy barrier for heterogeneous nucleation of a non-wetting phase on a fractal rough surface increases with increasing fractal dimensions, and both the critical nucleus radius and the nucleation energy barrier decrease with increasing fractal dimensions for heterogeneous nucleation of a wetting phase on the fractal rough surface. For a non-wetting system, the critical nucleus radius shows a slight shift with changes of the intrinsic wetting angle, but for a wetting system, the critical nucleus radius shows an obvious change with decreasing intrinsic wetting angle, thus imposes a stronger effect on the heterogeneous nucleation behaviors.展开更多
ZnO films were prepared at different substrate temperatures through spraying pyrolysis deposition of zinc chloride precursor onto glass substrate. Substrate temperature affects surface morphology of films and therefor...ZnO films were prepared at different substrate temperatures through spraying pyrolysis deposition of zinc chloride precursor onto glass substrate. Substrate temperature affects surface morphology of films and therefore their optical and electrical properties. All films are polycrystalline with Wurtzite crystal structure and preferentially grow along c-axis direction. Formation of ZnO rods start at about 500 °C. The diameter and length of rods deposited at 500 °C are350–500 and 550–700 nm, respectively. By increasing substrate temperature, film becomes more coverage and diameter of the rods reduces to 250–300 nm but their length increases to 1,000–1,200 nm, respectively. Optical transmission in visible region decreases with increasing substrate temperature. An ultraviolet emission and two visible emissions at 2.82 and2.37 eV are observed for photoluminescence spectra at room temperature. The resistivity of ZnO films increases with increasing substrate temperature due to surface morphology.展开更多
The matrix metalloproteinase (MMP) stromelysin-3 (ST3) has long been implicated to play an important role in extracellular matrix (ECM) remodeling and cell fate determination during normal and pathological processes. ...The matrix metalloproteinase (MMP) stromelysin-3 (ST3) has long been implicated to play an important role in extracellular matrix (ECM) remodeling and cell fate determination during normal and pathological processes. However like other MMPs, the molecular basis of ST3 function in vivo remains unclear due to the lack of information on its physiological substrates. Furthermore, ST3 has only weak activities toward all tested ECM proteins. Using thyroid hormone-dependent Xenopus laevis metamorphosis as a model, we demonstrated previously that ST3 is important for apoptosis and tissue morphogenesis during intestinal remodeling. Here, we used yeast two-hybrid screen with mRNAs from metamorphosing tadpoles to identify potential substrate of ST3 during development. We thus isolated the 37 kd laminin receptor precursor (LR). We showed that LR binds to ST3 in vitro and can be cleaved by ST3 at two sites distinct from where other MMPs cleave. Through peptide sequencing, we determined that the two cleavage sites are in the extracellular domain between the transmembrane domain and laminin binding sequence. Furthermore, we demon strated that these cleavage sites are conserved in human LR. These results together with high levels of human LR and ST3 expression in carcinomas suggest that LR is a likely in vivo substrate of ST3 and that its cleavage by ST3 may alter cell-extracellular matrix interaction, thus, playing a role in mediating the effects of ST3 on cell fate and behavior ob- served during development and pathogenesis.展开更多
Frequency-selective surface （FSS） is a two-dimensional periodic structure consisting of a dielectric substrate and the metal units （or apertures） arranged periodically on it. When manufacturing the substrate, its ...Frequency-selective surface （FSS） is a two-dimensional periodic structure consisting of a dielectric substrate and the metal units （or apertures） arranged periodically on it. When manufacturing the substrate, its thickness and dielectric constant suffer process tolerances. This may induce the center frequency of the FSS to shift, and consequently influence its characteristics. In this paper, a bandpass FSS structure is designed. The units are the Jerusalem crosses arranged squarely. The mode-matching technique is used for simulation. The influence of the tolerances of the substrate＇s thickness and dielectric constant on the center frequency is analyzed. Results show that the tolerances of thickness and dielectric constant have different influences on the center frequency of the FSS. It is necessary to ensure the process tolerance of the dielectric constant in the design and manufacturing of the substrate in order to stabilize the center frequency.展开更多
Development of cost-effective, highly reproducible non-conventional fabrication techniques for anisotropic metal nanostructures is essential to realizing potential applications of plasmonic devices, photonic devices, ...Development of cost-effective, highly reproducible non-conventional fabrication techniques for anisotropic metal nanostructures is essential to realizing potential applications of plasmonic devices, photonic devices, and surface enhanced Raman scattering （SERS） phenomenon based sensors. This report highlights the fabrication of nanotriangle arrays via nanoimprinting to overcome difficulties in creating large-area SERS active substrates with uniform, reproducible Raman signals. Electron beam lithography of anisotropic nanostructures, formation of arrays of nanotriangles in silicon and the transfer of triangular shapes to polymethylmethacrylate （PMMA） sheets via nanoimprinting have not been reported elsewhere. The reuse of silicon masters offers potential for production of low cost SERS substrates. The SERS activity and reproducibility of nanotriangles are illustrated and a consistent average enhancement factor of up to -2.9 × 1011, which is the highest value reported for a patterned SERS substrate, is achieved.展开更多
We theoretically investigate the transport property of graphene surface plasmon polaritons(GSPPs) on curved graphene substrates. The dispersion relationship, propagation length, and field confinement are calculated by...We theoretically investigate the transport property of graphene surface plasmon polaritons(GSPPs) on curved graphene substrates. The dispersion relationship, propagation length, and field confinement are calculated by an analytical method and compared with those on planar substrates. Based on our theory, the bend of graphene nearly does not affect the property of GSPPs except for an extremely small shift to the lower frequency for the same effective mode index. The field distributions and the eigenfrequencies of GSPPs on planar and cylindrical substrates are calculated by the finite element method, which validates our theoretical analysis. Moreover, three types of graphene-guided optical interconnections of GSPPs, namely, planar to curved graphene film, curved to planar graphene film, and curved to curved graphene film, are proposed and examined in detail. The theoretical results show that the GSPPs propagation on curved graphene substrates and interconnections will not induce any additional losses if the phase-matching condition is satisfied. Additionally, the extreme tiny size of curved graphene for interconnection at a certain spectra range is predicted by our theory and validated by the simulation of 90° turning of GSPPs. The bending effect on the property of GSPPs is systematically analyzed and identified. Our studies would be helpful to instruct design of plasmonic devices involving curved GSPPs, such as nanophotoniccircuits, flexible plasmonic, and biocompatible devices.展开更多
Nanodevices based on the single nanoparticle represent innovative and promising technology,which could satisfy the increasing requirements of high accuracy,low energy consumption,and small volume.However,the acquisiti...Nanodevices based on the single nanoparticle represent innovative and promising technology,which could satisfy the increasing requirements of high accuracy,low energy consumption,and small volume.However,the acquisition of single particles involves complex operation,and the corresponding nanodevices display low-throughput.Herein,we present a facile strategy to construct a single-particle platform with high throughput via substrate surface potential modulated a large-area and large-spacing nanoparticle assembly.Such platform not only avoids optic interference but also ensures the independent electrically conductive channel of single particle on substrate.Therefore,the dark-field microscopic imaging and single-particle scattering signals collecting of individual nanoparticles with plasmonic effect are satisfactory achieved based on the platform,and the first success in the fabrication of nano-organic-light-emitting-diodes with single nanoparticle resolution in nanoscale.All the results indicate that the strategy may find promising applications in the in situ single-particle research such as single-particle detection,singleparticle catalysis,and optoelectronics.展开更多
Principles applied to the elements of design that bring them together into one design. This research distinguishes about the architectural design criteria and the comparisonal methods of two squares; one is Taksim in ...Principles applied to the elements of design that bring them together into one design. This research distinguishes about the architectural design criteria and the comparisonal methods of two squares; one is Taksim in Turkey and in Vatican Sen Petro Square in Rome.展开更多
The properties of Quasi-longitudinal leaky surface acoustic wave(QLLSAW) on Y-rotated cut quartz substrates were presented. The phase velocity of QLLSAW on the quartz substrate along some orientations can be up from 6...The properties of Quasi-longitudinal leaky surface acoustic wave(QLLSAW) on Y-rotated cut quartz substrates were presented. The phase velocity of QLLSAW on the quartz substrate along some orientations can be up from 6200 m/s to 7100 m/s, circa 100% above that of regular SAW. Both theoretical and experimental results show that QLLSAW propagating along some promising orientations for SAW devices are of small power flow angle and low tem-perature coefficient, for example, along the Euler angle (0°155.25°? 42°?, the measurements of phase velocity and temperature coefficient of delay of QLLSAW are 6201 m/s and 12.9 ppm/℃. The experimental results show that QLLSAW had little absorption by liquid loading on the substrate surface, which proved that the direction of particle motion is the same as wave vector and parallel to the surface of the substrates, i.e., the wave is of the properties of longitudinal wave.展开更多
Metal foams have been intensively studied as three-dimensional （3-D） bulk mass-support for various applications because of their high conductivities and attractive mechanical properties. However, the relatively low ...Metal foams have been intensively studied as three-dimensional （3-D） bulk mass-support for various applications because of their high conductivities and attractive mechanical properties. However, the relatively low surface area of conventional metal foams largely limits their performance in applications such as charge storage. Here, we present a convenient electrochemical method for addressing this problem using Cu foams as an example. High surface area Cu foams are fabricated in a one-pot one-step manner by repetitive electrodeposition and dealloying treatments. The obtained Cu foams exhibit greatly improved performance for different applications like surface enhanced Raman spectroscopy （SERS） substrates and 3-D bulk supercapacitor electrodes.展开更多
Liquid metals(LM) such as eutectic gallium-indium and gallium-indium-tin are important functional liquid-state metal materials with many unique properties, which have attracted wide attentions especially from soft rob...Liquid metals(LM) such as eutectic gallium-indium and gallium-indium-tin are important functional liquid-state metal materials with many unique properties, which have attracted wide attentions especially from soft robot area. Recently the amoeba-like transformations of LM on the graphite surface are discovered, which present a promising future for the design and assemble of self-fueled actuators with dendritically deformable body. It appears that the surface tension of the LM can be significantly reduced when it contacts graphite surface in alkaline solution. Clearly, the specific surface should play a vital role in inducing these intriguing behaviors, which is valuable and inspiring in soft robot design. However, the information regarding varied materials functions underlying these behaviors remains unknown. To explore the generalized effects of surface materials in those intriguing behavior, several materials including glass, graphite, nickel and copper oxides(CuO) were comparatively investigated as substrate surfaces.Important results were obtained that only LM amoeba transformations were observed on graphite and CuO surfaces. In order to identify the proper surface condition for LM transformation, the intrinsic properties of substrate surfaces, such as the surface charge and roughness, as well as the specific interaction with LM like wetting behavior and mutual locomotion etc., were characterized. The integrated results revealed that LM droplet appears more likely to deform on surfaces with higher positive surface charge density, higher roughness and less bubble generation on them. In addition, another surface material,CuOx, is identified to own similar ability to graphite, which is valuable in achieving amoeba-like transformation. Moreover, this study offers a fundamental understanding of the surface properties in realizing LM amoeba transformations, which would shed light on packing and structure design of liquid metal-based soft device within multi-material system.展开更多
Plasmon coupling is an essential strategy to realize strong local electromagnetic(EM)field which is crucial for high-performance plasmonic devices.In this work,multiple plasmon couplings are demonstrated in three-dime...Plasmon coupling is an essential strategy to realize strong local electromagnetic(EM)field which is crucial for high-performance plasmonic devices.In this work,multiple plasmon couplings are demonstrated in three-dimensional(3D)hybrid plasmonic systems composed of polydimethylsiloxane-supported ordered silver nanocone(AgNC)arrays decorated with high-density gold nanoparticles(AuNPs)which are fabricated by a template-assisted physical vapor deposition process.Strong interparticle coupling,particle-film coupling,inter-cone coupling,and particle-cone coupling are revealed by numerical simulations in such composite nanostructures,which produce intense and high-density EM hot spots,boosting highly sensitive and reproducible surface enhanced Raman scattering(SERS)detection with an enhancement factor of-1.74×10^(8).Furthermore,a linear correlation between logarithmic Raman intensity and logarithmic concentration of probe molecules is observed in a large concentration range.These results offer new ideas to develop novel plasmonic devices,and provide alternative strategy to realize flexible and high-performance SERS sensors for trace molecule detection and quantitative analysis.展开更多
基金supported by Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park (Project HZQBKCZYB-2020030)National Key R&D Program of China (Project 2017YFA0204403)+2 种基金the National Natural Science Foundation of China (Project 51590892)the Major Program of Changsha Science and Technology (Project kh2003023)the Innovation and Technology Commission of HKSAR through Hong Kong Branch of National Precious Metals Material Engineering Research Centre,and the City University of Hong Kong (Project 9667207)。
文摘Surface-enhanced Raman Spectroscopy(SERS)is a nondestructive technique for rapid detection of analytes even at the single-molecule level.However,highly sensitive and reliable SERS substrates are mostly fabricated with complex nanofabrication techniques,greatly restricting their practical applications.A convenient electrochemical method for transforming the surface of commercial gold wires/foils into silver-alloyed nanostructures is demonstrated in this report.Au substrates are treated with repetitive anodic and cathodic bias in an electrolyte of thiourea,in a one-pot one-step manner.X-rays absorption fine structure(XAFS)spectroscopy confirms that the AuAg alloy is induced at the surface.The unique AuAg alloyed surface nanostructures are particularly advantageous when served as SERS substrates,enabling a remarkably sensitive detection of Rhodamine B(a detection limit of 10^(-14)M,and uniform strong response throughout the substrates at 10^(-12)M).
基金the National High-Tech Research and Development Program of China (No.2002AA305508)the National Natural Science Foundation of China (No.50472095)+1 种基金the Scientific Research Foundation for the Returned Overseas Chinese Scholars (No.2003-14)Beijing Novel Project (No. 2003A13).]
文摘Optical emission spectroscopy （OES） was used to study the gas phase composition near the substrate surface during diamond deposition by high-power DC arc plasma jet chemical vapor deposition （CVD）. C2 radical was determined as the main carbon radical in this plasma atmosphere. The deposition parameters, such as substrate temperature, anode-substrate distance, methane concentration, and gas flow rate, were inspected to find out the influence on the gas phase. A strong dependence of the concentrations and distribution of radicals on substrate temperature was confirmed by the design of experiments （DOE）. An explanation for this dependence could be that radicals near the substrate surface may have additional ionization or dissociation and also have recombination, or are consumed on the substrate surface where chemical reactions occur.
基金supported by the National Basic Research Program ("973" Program) of China (No.2011CB610402)the National Natural Science Foundation of China (Nos. 50901061 and 50971102)+1 种基金the fund of the State Key Laboratory of Solidification Processing in NWPU, China (Nos. 02-TZ-2008 and 36-TP-2009)the Programme of Introducing Talents of Discipline to Universities (No. 08040)
文摘Classical theory of heterogeneous nucleation has been developed with an implied hypothesis of smooth substrate surfaces; however, morphologies of any real substrate surfaces are generally complicated and demonstrate fractal characteristics. In this paper, the wettability between the embryo and the fractal substrate surface was discussed, and heterogeneous nucleation behaviors were theoretically analyzed. The result shows that the roughness factor of a fractal surface varies with the scale of the embryo. As a result, the fractal character of the substrate surface has important effects on heterogeneous nucleation behaviors. It has been shown that the energy barrier for heterogeneous nucleation of a non-wetting phase on a fractal rough surface increases with increasing fractal dimensions, and both the critical nucleus radius and the nucleation energy barrier decrease with increasing fractal dimensions for heterogeneous nucleation of a wetting phase on the fractal rough surface. For a non-wetting system, the critical nucleus radius shows a slight shift with changes of the intrinsic wetting angle, but for a wetting system, the critical nucleus radius shows an obvious change with decreasing intrinsic wetting angle, thus imposes a stronger effect on the heterogeneous nucleation behaviors.
文摘ZnO films were prepared at different substrate temperatures through spraying pyrolysis deposition of zinc chloride precursor onto glass substrate. Substrate temperature affects surface morphology of films and therefore their optical and electrical properties. All films are polycrystalline with Wurtzite crystal structure and preferentially grow along c-axis direction. Formation of ZnO rods start at about 500 °C. The diameter and length of rods deposited at 500 °C are350–500 and 550–700 nm, respectively. By increasing substrate temperature, film becomes more coverage and diameter of the rods reduces to 250–300 nm but their length increases to 1,000–1,200 nm, respectively. Optical transmission in visible region decreases with increasing substrate temperature. An ultraviolet emission and two visible emissions at 2.82 and2.37 eV are observed for photoluminescence spectra at room temperature. The resistivity of ZnO films increases with increasing substrate temperature due to surface morphology.
文摘The matrix metalloproteinase (MMP) stromelysin-3 (ST3) has long been implicated to play an important role in extracellular matrix (ECM) remodeling and cell fate determination during normal and pathological processes. However like other MMPs, the molecular basis of ST3 function in vivo remains unclear due to the lack of information on its physiological substrates. Furthermore, ST3 has only weak activities toward all tested ECM proteins. Using thyroid hormone-dependent Xenopus laevis metamorphosis as a model, we demonstrated previously that ST3 is important for apoptosis and tissue morphogenesis during intestinal remodeling. Here, we used yeast two-hybrid screen with mRNAs from metamorphosing tadpoles to identify potential substrate of ST3 during development. We thus isolated the 37 kd laminin receptor precursor (LR). We showed that LR binds to ST3 in vitro and can be cleaved by ST3 at two sites distinct from where other MMPs cleave. Through peptide sequencing, we determined that the two cleavage sites are in the extracellular domain between the transmembrane domain and laminin binding sequence. Furthermore, we demon strated that these cleavage sites are conserved in human LR. These results together with high levels of human LR and ST3 expression in carcinomas suggest that LR is a likely in vivo substrate of ST3 and that its cleavage by ST3 may alter cell-extracellular matrix interaction, thus, playing a role in mediating the effects of ST3 on cell fate and behavior ob- served during development and pathogenesis.
文摘Frequency-selective surface （FSS） is a two-dimensional periodic structure consisting of a dielectric substrate and the metal units （or apertures） arranged periodically on it. When manufacturing the substrate, its thickness and dielectric constant suffer process tolerances. This may induce the center frequency of the FSS to shift, and consequently influence its characteristics. In this paper, a bandpass FSS structure is designed. The units are the Jerusalem crosses arranged squarely. The mode-matching technique is used for simulation. The influence of the tolerances of the substrate＇s thickness and dielectric constant on the center frequency is analyzed. Results show that the tolerances of thickness and dielectric constant have different influences on the center frequency of the FSS. It is necessary to ensure the process tolerance of the dielectric constant in the design and manufacturing of the substrate in order to stabilize the center frequency.
文摘Development of cost-effective, highly reproducible non-conventional fabrication techniques for anisotropic metal nanostructures is essential to realizing potential applications of plasmonic devices, photonic devices, and surface enhanced Raman scattering （SERS） phenomenon based sensors. This report highlights the fabrication of nanotriangle arrays via nanoimprinting to overcome difficulties in creating large-area SERS active substrates with uniform, reproducible Raman signals. Electron beam lithography of anisotropic nanostructures, formation of arrays of nanotriangles in silicon and the transfer of triangular shapes to polymethylmethacrylate （PMMA） sheets via nanoimprinting have not been reported elsewhere. The reuse of silicon masters offers potential for production of low cost SERS substrates. The SERS activity and reproducibility of nanotriangles are illustrated and a consistent average enhancement factor of up to -2.9 × 1011, which is the highest value reported for a patterned SERS substrate, is achieved.
基金supported by the 973 Program of China (nos. 2013CB632704 and 2011CB922002)the National Natural Science Foundation of China (no. 11204365)
文摘We theoretically investigate the transport property of graphene surface plasmon polaritons(GSPPs) on curved graphene substrates. The dispersion relationship, propagation length, and field confinement are calculated by an analytical method and compared with those on planar substrates. Based on our theory, the bend of graphene nearly does not affect the property of GSPPs except for an extremely small shift to the lower frequency for the same effective mode index. The field distributions and the eigenfrequencies of GSPPs on planar and cylindrical substrates are calculated by the finite element method, which validates our theoretical analysis. Moreover, three types of graphene-guided optical interconnections of GSPPs, namely, planar to curved graphene film, curved to planar graphene film, and curved to curved graphene film, are proposed and examined in detail. The theoretical results show that the GSPPs propagation on curved graphene substrates and interconnections will not induce any additional losses if the phase-matching condition is satisfied. Additionally, the extreme tiny size of curved graphene for interconnection at a certain spectra range is predicted by our theory and validated by the simulation of 90° turning of GSPPs. The bending effect on the property of GSPPs is systematically analyzed and identified. Our studies would be helpful to instruct design of plasmonic devices involving curved GSPPs, such as nanophotoniccircuits, flexible plasmonic, and biocompatible devices.
基金supported by the National Natural Science Foundation of China(Nos.21822202 and 22072104)the National Key R&D Program of China(International Collaboration program)granted by the Chinese Ministry of Science and Technology(No.2018YFE0200700).
文摘Nanodevices based on the single nanoparticle represent innovative and promising technology,which could satisfy the increasing requirements of high accuracy,low energy consumption,and small volume.However,the acquisition of single particles involves complex operation,and the corresponding nanodevices display low-throughput.Herein,we present a facile strategy to construct a single-particle platform with high throughput via substrate surface potential modulated a large-area and large-spacing nanoparticle assembly.Such platform not only avoids optic interference but also ensures the independent electrically conductive channel of single particle on substrate.Therefore,the dark-field microscopic imaging and single-particle scattering signals collecting of individual nanoparticles with plasmonic effect are satisfactory achieved based on the platform,and the first success in the fabrication of nano-organic-light-emitting-diodes with single nanoparticle resolution in nanoscale.All the results indicate that the strategy may find promising applications in the in situ single-particle research such as single-particle detection,singleparticle catalysis,and optoelectronics.
文摘Principles applied to the elements of design that bring them together into one design. This research distinguishes about the architectural design criteria and the comparisonal methods of two squares; one is Taksim in Turkey and in Vatican Sen Petro Square in Rome.
文摘The properties of Quasi-longitudinal leaky surface acoustic wave(QLLSAW) on Y-rotated cut quartz substrates were presented. The phase velocity of QLLSAW on the quartz substrate along some orientations can be up from 6200 m/s to 7100 m/s, circa 100% above that of regular SAW. Both theoretical and experimental results show that QLLSAW propagating along some promising orientations for SAW devices are of small power flow angle and low tem-perature coefficient, for example, along the Euler angle (0°155.25°? 42°?, the measurements of phase velocity and temperature coefficient of delay of QLLSAW are 6201 m/s and 12.9 ppm/℃. The experimental results show that QLLSAW had little absorption by liquid loading on the substrate surface, which proved that the direction of particle motion is the same as wave vector and parallel to the surface of the substrates, i.e., the wave is of the properties of longitudinal wave.
文摘Metal foams have been intensively studied as three-dimensional （3-D） bulk mass-support for various applications because of their high conductivities and attractive mechanical properties. However, the relatively low surface area of conventional metal foams largely limits their performance in applications such as charge storage. Here, we present a convenient electrochemical method for addressing this problem using Cu foams as an example. High surface area Cu foams are fabricated in a one-pot one-step manner by repetitive electrodeposition and dealloying treatments. The obtained Cu foams exhibit greatly improved performance for different applications like surface enhanced Raman spectroscopy （SERS） substrates and 3-D bulk supercapacitor electrodes.
基金supported by the Dean’s Research Funding from the Chinese Academy of Sciences, Beijing Municipal Science and Technology Funding(Z151100003715002)the National Natural Science Foundation of China (61307065) and the National Key Research and Development Program of China (2016YFA0200500)
文摘Liquid metals(LM) such as eutectic gallium-indium and gallium-indium-tin are important functional liquid-state metal materials with many unique properties, which have attracted wide attentions especially from soft robot area. Recently the amoeba-like transformations of LM on the graphite surface are discovered, which present a promising future for the design and assemble of self-fueled actuators with dendritically deformable body. It appears that the surface tension of the LM can be significantly reduced when it contacts graphite surface in alkaline solution. Clearly, the specific surface should play a vital role in inducing these intriguing behaviors, which is valuable and inspiring in soft robot design. However, the information regarding varied materials functions underlying these behaviors remains unknown. To explore the generalized effects of surface materials in those intriguing behavior, several materials including glass, graphite, nickel and copper oxides(CuO) were comparatively investigated as substrate surfaces.Important results were obtained that only LM amoeba transformations were observed on graphite and CuO surfaces. In order to identify the proper surface condition for LM transformation, the intrinsic properties of substrate surfaces, such as the surface charge and roughness, as well as the specific interaction with LM like wetting behavior and mutual locomotion etc., were characterized. The integrated results revealed that LM droplet appears more likely to deform on surfaces with higher positive surface charge density, higher roughness and less bubble generation on them. In addition, another surface material,CuOx, is identified to own similar ability to graphite, which is valuable in achieving amoeba-like transformation. Moreover, this study offers a fundamental understanding of the surface properties in realizing LM amoeba transformations, which would shed light on packing and structure design of liquid metal-based soft device within multi-material system.
基金supported by the National Natural Science Foundation of China(No.51871003).
文摘Plasmon coupling is an essential strategy to realize strong local electromagnetic(EM)field which is crucial for high-performance plasmonic devices.In this work,multiple plasmon couplings are demonstrated in three-dimensional(3D)hybrid plasmonic systems composed of polydimethylsiloxane-supported ordered silver nanocone(AgNC)arrays decorated with high-density gold nanoparticles(AuNPs)which are fabricated by a template-assisted physical vapor deposition process.Strong interparticle coupling,particle-film coupling,inter-cone coupling,and particle-cone coupling are revealed by numerical simulations in such composite nanostructures,which produce intense and high-density EM hot spots,boosting highly sensitive and reproducible surface enhanced Raman scattering(SERS)detection with an enhancement factor of-1.74×10^(8).Furthermore,a linear correlation between logarithmic Raman intensity and logarithmic concentration of probe molecules is observed in a large concentration range.These results offer new ideas to develop novel plasmonic devices,and provide alternative strategy to realize flexible and high-performance SERS sensors for trace molecule detection and quantitative analysis.
