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Porous SiO2-coated Au-Ag alloy nanoparticles for the alkyne-mediated ratiometric Raman imaging analysis of hydrogen peroxide in live cells
摘要： We prepared an ultrathin porous silica shell-coated Au-Ag alloy nanoparticle (AuAg@p-SiO2NP) and developed it as a novel alkyne-based surface-enhanced Raman scattering (SERS) nanoprobe for the ratiometric Raman imaging of exogenous and endogenous H2O2 in live cells. The AuAg@p-SiO2NPs functionalized with 4-mercaptophenylboronic acid (MPBA) and 4-mercaptophenylacetylene (MPAE, 1,986 cm-1) as internal standard were first incubated with dopamine (DA) to incorporate the bridging molecules through the formation of borate bond between DA and MPBA on the surface of nanoparticle. Then, the signaling alkyne molecules of 3-(4-(phenylethynyl) benzylthio) propanoic acid (PEB, 2,214 cm-1) were conjugated to the surface of nanoparticle through the formation of amide bond between the carboxyl group on the PEB and the amino group on the DA, forming the ratiometric SERS nanoprobe. In the presence of H2O2, the alkynyl on the PEB is released from the surface of the Au-Ag alloy nanoparticle due to the boronate-to-phenol switch, decreasing the Raman signal at 2,214 cm-1 significantly. Since the Raman signal of MPAE at 1,986 cm-1 remains unchanged, quantitative analysis of H2O2 concentration can be achieved based on the ratiometric value of I1986/I2214. Under the optimized conditions, the plot of the ratiometric value of I1986/I2214 versus the H2O2 concentration in the range from 0.12 to 8 m M revealed a good linear response with a detection limit of 52 nM based on a signal-to-noise ratio of S/N = 3. The porous SiO2-coated Au-Ag alloy nanoparticle provides a novel SERS substrate with excellent biocompatibility, high stability, and effective anti-interference ability. Together with the alkynyl derivatives as internal standard, the SERS nanoprobe reported here allows the ratiometric detection of H2O2 in live cells and can be further applied to quantify many other biomolecules by using different signaling agents.
关键词： porous SiO2-coated Au-Ag alloy nanoparticle,SERS,alkyne,cell imaging,hydrogen peroxide
更新于2025-09-23 15:23:52
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Behavior of Al/Cu/Ti electrodes in surface acoustic wave filter at high power
摘要： Driven by the need for high data-rates and continuous reduction in device size, surface acoustic wave filters are required to work under increasingly high power. In this work, a series of 2.7 GHz surface acoustic wave filters with Al/Cu/Ti three-layered electrode were fabricated and loaded with high power. Those three-layered electrodes showed weaker texture but higher stability than Al-Cu alloy electrode at high power. Morphologies, microstructures and elements distribution in cross section of fingers were analyzed carefully before and after high power loading. Results show that the circular-arc-shaped outline of fingers were appeared in most samples after high power loading, and the number of gains in the finger cross section changed from some into several with much larger volume. The features of distribution of Cu atoms also coincided with these microstructures. By finite element method and phase diagram analysis, the higher stability of Al/Cu/Ti three-layered electrodes are attributed to precipitation of θ-CuAl2 in the bottom edge of electrode finger and Cu-doped α-Al in the center top.
关键词： stress,Al-Cu alloy,high power,surface acoustic wave filter,three-layered electrode
更新于2025-09-23 15:23:52
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Corrosion study of laser cladded Ti-6Al-4V alloy in different corrosive environments
摘要： Laser cladding of Ti-6Al-4V powder on a substrate with the same chemical composition was performed at different laser powers. The effect of laser power on the microstructure and corrosion behavior was then investigated. Electrochemical studies were performed by potentiodynamic polarization tests in different corrosive environments (3.5% NaCl, 2% H2SO4 and 5% HCl solutions). Microstructural investigation together with phase characterization revealed that laser cladded Ti-6Al-4V coatings were composed of needle-like martensite (ɑ/) and coaxial hexagonal compact (ɑ) phases. The coatings were crack-free; however, some cavities were observed in the coatings produced at high laser powers. In all three corrosive environments, the coatings showed a more noble corrosion behavior compared to the untreated substrate. The results showed that corrosion potential increases from ?410 (mV) to ?130 (mV) in NaCl and from ?50 (mV) to ?20 (mV) in H2SO4 enviroments but decreases from ?60 (mV) to ?270 (mV) in HCl solution. Increasing laser power had a positive effect on the corrosion behavior in NaCl and H2SO4 solutions; however, it had a negative effect on the corrosion behavior in HCl solution.
关键词： Corrosion,Laser cladding,Ti-6Al-4V alloy,Microstructure
更新于2025-09-23 15:23:52
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Enhanced nonlinear optical properties of LiNbO3 crystal embedded with CuZn alloy nanoparticles by ion implantation
摘要： LiNbO3 crystal, as a typical nonlinear optical material, has attracted considerable interest in photonic device applications. However, LiNbO3 shows weak nonlinear optical responses due to its low laser damage threshold. Herein, the optical nonlinearities of LiNbO3 are enhanced by inducing CuZn alloy nanoparticles (NPs). The structural and optical properties of LiNbO3 with embedded NPs were investigated in detail. The third-order nonlinear susceptibilities of CuZn: LiNbO3 nanocomposites exhibit nearly 4 orders of magnitude greater than the untreated LiNbO3 due to the localized surface plasmon resonance effect. Furthermore, the nanocomposites suffer conversion from reverse-saturable absorption to saturable absorption compared with the pure LiNbO3. This feature makes the nanocomposites a potential saturable absorber leading to the realization of efficient pulse lasers.
关键词： Ion implantation,Optical nonlinearities,CuZn alloy nanoparticles,Nonlinear materials
更新于2025-09-23 15:23:52
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Preparation of multicomponent thin films by magnetron co-sputtering method: The Cu-Ti case study
摘要： The paper discusses the preparation of multicomponent thin films of Cu-Ti composite with desired elemental composition using the pulsed magnetron co-sputtering technology. The technological goal described in the paper was deposition the Cu-Ti composite with elemental ratio of about 50/50 at.%, which is close to the eutectic point from the Cu-Ti alloy system. A large difference in the sputtering yield (about seven-fold) of Cu and Ti metals was challenging, because of the features of used power supplies. Desired concentrations of the Ti and Cu elements were obtained as a result of application of multimagnetron sputtering system, where magnetrons were equipped with the Ti or Cu targets. Additionally, pulse power supply was used together with the pulse width modulation controller. Moreover, the article presents investigations of structural and mechanical properties of deposited Cu, Ti and Cu-Ti films with elemental composition of ca. 50/50 at.%. It was found that the two component Cu0.5Ti0.5 thin films were composed of Cu4Ti3 nanocrystallites built-in an amorphous matrix. As compared to the pure Cu and Ti thin films, the prepared composite exhibited improved hardness and better elasticity reflected in lower values of the Young’s modulus. The results of nanoindentation investigations showed that the Cu0.5Ti0.5 composite thin film was characterized by the hardness of 7.59 GPa.
关键词： thin film,CuTi alloy,multicomponent coating,magnetron sputtering
更新于2025-09-23 15:23:52
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Doping modulation of quasi-free-standing monolayer graphene formed on SiC(0001) through Sn1-Ge intercalation
摘要： In order to modulate the transfer doping of quasi-free-standing monolayer graphene (QFMLG) formed on SiC(0001), Ge atoms were intercalated additionally into QFMLG already formed by Sn intercalation between ZL and 6H-SiC(0001). By postannealing the Ge-deposited surface at 600 °C, the Sn1-xGex film with the 4 × √3 structure, composed of a bilayer and adatoms with dangling bonds under QFMLG, has been formed. It turns out that, in this Sn1-xGex film, Ge atoms preferentially occupy the bottom layer bound to the top Si atoms of the substrate, while Sn atoms occupy the top adatom sites. Strong correlation among the electrons localized at these adatom sites induces a semiconducting alloy film. As the postannealing temperature is increased up to 800 °C, the concentration of Ge in the intercalated film of the same 4 × √3 structure is gradually increased and the Dirac point also shifts gradually from ?0.16 eV to +0.20 eV relative to the Fermi level. Such a result confirms that the transfer doping of QFMLG on SiC(0001) has been modulated by varying the alloy composition of the Sn1-xGex interfacial film.
关键词： Scanning tunneling microscopy,Quasi-free-standing graphene,SnGe alloy intercalation,Hubbard band,Doping modulation,Photoemission spectroscopy,SiC(0001)
更新于2025-09-23 15:23:52
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Highly Sensitive Polarization Photodetection Using a Pseudo-One-Dimensional Nb <sub/> (1– <i>x</i> ) </sub> Ti <sub/><i>x</i> </sub> S <sub/>3</sub> Alloy
摘要： Low-symmetry layered two-dimensional (2D) materials with strong in-plane optical anisotropy can potentially be applied for polarization photodetection. This is especially true for those 2D materials with a direct bandgap, who can efficiently absorb light with specific axial polarization. However, discovering such new anisotropic 2D materials with direct band structure is still extremely challenging. Here, we fabricate a photodetector using a pseudo-one-dimensional (pseudo-1D) Nb(1-x)TixS3 alloy device, and demonstrate that it is highly sensitive to the polarized light due to the strong in-plane optical anisotropy and direct bandgap of the alloy by combining the angle-resolved polarization Raman spectroscopy (ARPRS), azimuth-dependent reflectance difference microscopy (ADRDM), polarization-dependent absorption spectroscopy (PDAS), and hybrid functional theory calculations. As a consequence, the polarization photodetector of the Nb(1-x)TixS3 alloy shows a large photocurrent anisotropic ratio and a high photoresponse. The choice of low-symmetry layered pseudo-1D Nb(1-x)TixS3 alloy in polarization photodetection might open up new functionalities for novel optoelectronic device applications.
关键词： low-symmetry structure,in-plane optical anisotropy,pseudo-one-dimensional materials,Nb(1-x)TixS3 ternary alloy,polarization-sensitive photodetector
更新于2025-09-23 15:23:52
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One-step machining of hierarchical micro-nano structures on Al-Mg alloy as superamphiphobic substrate for amplified SERS trace detection
摘要： Ultra-trace detection from polluted solution makes great contribution to environmental monitoring, food safety and medical analysis. However, its common difficulty arises in concentrating analytes on easily accessible substrate for highly amplified detection intensity. Herein, a superhydrophobic Al-Mg alloy surface focusing on droplet condensation and analyte detection is fabricated by an environment-friendly, efficient and low-cost machining process for surface enhanced Raman scattering (SERS) analyses. The micro-scale craters covered with nano-scale terrace-like structures have been prepared by one-step wire electrical discharge machining (WEDM). Meanwhile, wet abilities of hierarchical structures have been investigated after stearic acid modification. Results show that the as-prepared surface exhibits excellent repellent ability to water and oil drops. The resultant superamphiphobic surface also displays a 3-fold higher SERS intensity over hydrophilic Al-Mg alloy substrate. The corresponding SERS signals also show well signal reproducibility. This work sheds positive insights into fabricating accessible and efficient active substrates for SERS detection and extending potential applications of Al-Mg alloys in ultra-trace analysis in the future.
关键词： SERS,analytes detection,superamphiphobicity,micro-nano structures,Al-Mg alloy
更新于2025-09-23 15:23:52
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Intrinsic Au-decoration on anodic TiO2 nanotubes grown from metastable Ti–Au sputtered alloys—High density co-catalyst decoration enhances the photocatalytic H2 evolution
摘要： Recent work demonstrated that intrinsic Au nanoparticle decoration of TiO2 nanotube arrays (NTs) can be achieved by electrochemical anodization of Ti–Au alloy substrates. However, for a Ti–Au cast alloy produced by melt-alloying, the Au concentration cannot exceed the solubility limit of Au in Ti of 0.2 at.% – this sets constraints on the intrinsic Au nanoparticle loading on anodic TiO2 NTs. Here we explore “metastable” Ti–Au metal substrates that are produced by Ti and Au cosputtering and we establish Au concentrations that far exceed the solubility limit in cast Ti–Au alloys. We show the use of these “metastable” Ti–Au sputtered layers for the anodic formation of TiO2 NTs with a much higher density of Au nanoparticle loading than using classic alloys. Under optimized conditions (Au nanoparticle density) photocatalytic H2 production from such Au@TiO2 platforms provides a 15 times higher photocatalytic H2 evolution rate than the best rates achieved with conventional alloys.
关键词： Anodic TiO2 nanotube,Metastable Ti–Au alloy,Sputtering,Anodization,Photocatalytic H2 evolution
更新于2025-09-23 15:23:52
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Microstructure and mechanical properties of Ti/Al dissimilar joints produced by laser-MIG welding–brazing
摘要： We butt-welded AA6061 aluminum alloy to Ti6Al4V titanium alloy, dissimilar light metals, by using laser-MIG hybrid welding–brazing without grooves. The parameters of the laser and arc were optimized to produce sound joints with good formation and mechanical properties. The microstructure of the layer of intermetallic compounds (IMCs) was investigated by scanning electron microscopy and energy dispersive spectroscopy. We also tested the tensile strength of the joints with and without reinforcement. The morphology and thickness of the IMCs varied throughout the joints. A continuous thin layer of TiAl3 appeared on the top surface of the Ti6Al4V, on which some rod-like IMCs grew toward the fusion zone. In the upper region of the butt plane, because more heat accumulated there from the high-power laser coupled with the MIG arc, double-layer IMCs with a thickness of ～ 10.0 μm formed, composed of TiAl (near the Ti alloy) and TiAl3 (near the fusion zone). In the lower region of the butt plane, the double-layer IMCs became continuous and uniform, the serrated morphology disappeared, and the thickness of the IMC layer decreased to 4.0 μm. On the backside of the joint, the thickness of the compound layer (TiAl3) was about 1.0 μm. The average tensile strengths of the reinforced and unreinforced joints were 226 MPa and 210 MPa, respectively, which are up to 88% and 81% of the AA6061 tensile strength, respectively.
关键词： dissimilar joint,titanium alloy,intermetallic compounds.,Laser-MIG hybrid welding–brazing,aluminum alloy
更新于2025-09-23 15:22:29