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Evaluating impact damage to fabric-based personal armor by infrared NDT
摘要： The paper considers the thermo-mechanical mechanism of interaction between the damage agents and armor protection made of polymer fabrics. A simplified mathematical model is proposed to describe the deceleration of a damage agent within an armor fabric due to the dissipation of energy expended on irreversible stretching deformations of fabric fibers, as well as fiber slipping friction and material heating. Woven fabric layers are replaced by solid layers characterized by averaged stiffness and viscosity. A discrete numerical model of a solid material is proposed to reduce a problem with a finite number of degrees of freedom; motion equations are obtained on the basis of the Lagrange equations of the second kind, and for their integration, a stable non-conservative difference scheme is used. The software implementation is based on a functional-object paradigm which allows the modeling of conjugated processes. The parameters of governing equations are identified by using the experimental data. Some illustrative examples of interaction between damage agents and armor barriers with different arrangement of fibers are presented. The proposed model can be used to predict the quality of armor protection with the changing number and location of fibers, as well as to test the armor protection by applying the technique of infrared thermography.
关键词： Armor protection,mathematical model,irreversible deformation,infrared thermography,energy absorption,numerical scheme,composite material,fiber friction
更新于2025-09-23 15:22:29
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Characterization of Porous SiO2-TiO2 Photocatalyst and the Effect of PEG1000 Concentration
摘要： A porous SiO2-TiO2 photocatalyst was prepared through co-sol-gel method for photocatalytic degradation of methyl orange. PEG1000 was used as a template to induce porous structure in the material. Photocatalytic degradation was conducted after adsorption equilibrium to identify the contribution of both adsorption and photocatalytic degradation. The prepared material was composed of anatase TiO2 and amorphous SiO2. Many small particles formed during grinding also scattered on the surface. The average pore diameter is 16.89 nm and the total pore volume is 0.3644 cm3 g-1 along with specific surface area of 86.27 m2 g-1, as calculated by using BJH and BET methods. The SiO2-TiO2 composite may have the maximum photocatalytic activity and adsorption capacity using 0.04 mol/L of PEG1000 in the precursor.
关键词： Photocatalysis,Composite,TiO2,SiO2
更新于2025-09-23 15:22:29
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Influence of surfactant on the synthesis of BiOCl/WO3 microcomposites for enhanced adsorption in aqueous solutions
摘要： BiOCl/WO3 microcomposites were synthesized using a one-step hydrothermal route in the presence of a variety of surfactants: polyvinylpyrrolidone (PVP), triethylene glycol (TEG), and Triton X-100 (TX-100). The as-synthesized microcomposites were exploited as efficient adsorbents for removing organic dyes (rhodamine B and methylene blue). Prior to adsorption studies, the structural, functional, and morphological characteristics of these adsorbents were studied using analytical techniques, including XRD, FE-SEM, TEM, and UV-DRS, which revealed the presence of large surface areas. The experimental results show that the PVP-synthesized BiOCl/WO3 microcomposite was significantly more effective as an adsorbent than the microcomposites synthesized using TEG or TX-100. This enhanced adsorption performance is attributable to the larger surface area associated with the developed microstructure of the PVP-stabilized BiOCl/WO3 microcomposite. The BiOCl/WO3 microcomposite synthesized from PVP was subjected to parametric studies involving catalyst dosage, pH, and initial dye concentration. The experimental data were fitted to isotherm models, and the mechanism of adsorption was investigated.
关键词： Rhodamine B,Methylene Blue,BiOCl/WO3 Composite,Adsorption,Surfactant
更新于2025-09-23 15:22:29
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Switchable fluorescence immunoassay using gold nanoclusters anchored cobalt oxyhydroxide composite for sensitive detection of imidacloprid
摘要： The fabrication of a convenient fluorescence-based immunoassay (FIA) for specific antigen attract increasing concern but remains a considerable challenge, especially the laborious synthesis of nanomaterials-antibody conjugates. Herein, we circumvent this drawback by introducing a specific fluorescence signal response procedure to commercially available alkaline phosphatase (ALP)-labeled conventional immunoassay for imidacloprid detection. In this FIA protocol, gold nanoclusters (AuNCs) can anchor on the surface of two-dimensional cobalt oxyhydroxide (CoOOH) nanoflakes to form nanocomposite, resulting in remarkable decrease of fluorescence intensity. The quenching effects can be effectively reversed by introducing ascorbic acid that can trigger the decomposition of CoOOH nanoflakes. Notably, the corresponding fluorescence response induced by ascorbic acid was related to ALP activities labeled on antibody. After competitive immunoreaction, the ALP-labeled antibodies were bounded to immobilized antigen, which can regulate the fluorescence change. Utilizing fluorescence switching of system, the 50% inhibition concentration (IC50) value of FIA toward imidacloprid was obtained at 1.3 ng mL?1 which was 60-fold-of-magnitude more sensitive than that of conventional ELISA (86.4 ng mL?1). This FIA protocol not only develops new prospects for pesticide detection, but also opens up potent strategy of fluorogenic immunoassay.
关键词： Immunoassay,Composite,Alkaline phosphatase,Fluorescence,Imidacloprid
更新于2025-09-23 15:22:29
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PZT/PZT and PZT/BiT Composite Piezo-Sensors in Aerospace SHM Applications: Photochemical Metal Organic + Infiltration Deposition and Characterization
摘要： The composition of fine-ground lead zirconate-titanate powder Pb(Zr0.52Ti0.48)O3, suspended in PZT and bismuth titanate (BiT) solutions, is deposited on the curved surface of IN718 and IN738 nickel-based super alloy substrates up to 100 μm thickness. Photochemical metal organic and infiltration techniques are implemented to produce smooth, semi-dense, and crack-free random orientated thick piezoelectric films as piezo-sensors, free of any dopants or thickening polymers. Every single layer of the deposited films is heated at 200 °C with 10 wt.% excess PbO, irradiated by ultraviolet lamp (365 nm, 6 watt) for 10 min, pyrolyzed at 400 °C, and subsequently annealed at 700 °C for one hour. This process is repeated successively until reaching the desired thickness. Au and Pt thin films are deposited as the bottom and top electrodes using evaporation and sputtering methods, respectively. PZT/PZT and PZT/BiT composite films are then characterized and compared to similar PZT and BiT thick films deposited on the similar substrates. The effect of the composition and deposition process is also investigated on the crystalline phase development and microstructure morphology as well as the dielectric, ferroelectric, and piezoelectric properties of piezo-films. The maximum remnant polarization of Pr = 22.37 ± 0.01, 30.01 ± 0.01 μC/cm2, the permittivity of εr = 298 ± 3, 566 ± 5, and piezoelectric charge coefficient of d33 = 126, 148 m/V were measured versus the minimum coercive field of Ec = 50, 20 kV/cm for the PZT/PZT and PZT/BiT thick films, respectively. The thick film piezo-sensors are developed to be potentially used at frequency bandwidth of 1–5 MHz for rotary structural health monitoring and also in other industrial or medical applications as a transceiver.
关键词： piezoelectric sensor,structural health monitoring,PZT/BiT,composite,characterization,sol-gel PMOD deposition,infiltration,aerospace structure,PZT/PZT,thick film
更新于2025-09-23 15:22:29
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Synthesis and Consolidation of Nanostructured Nb <sub/>2</sub> C–Al <sub/>2</sub> O <sub/>3</sub> Composite
摘要： Although an extremely hard ceramic material, niobium carbide has low fracture toughness to use wide applications. To fabricate nanostructured composite is common method to improve fracture toughness. Nanopowder mixture of Nb2C and Al2O3 were synthesized according to the reaction from Al4C3 and Nb powders by high-energy ball milling. The synthesized mixture of Nb2C and Al2O3 powders was consolidated by pulsed current activated sintering method within two min under the 80 MPa pressure. Nb2C and Al2O3 in the composite were nano-sized phases. The fracture toughness of a nanostructured Nb2C–Al2O3 composite of this study is better than that of previous study.
关键词： Rapid Sintering,Composite,Mechanical Properties,Nb2C–Al2O3,Nanomaterial
更新于2025-09-23 15:22:29
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The Effects of the Content of NiO on the Microstructure and Photocatalytic Activity of the NiO/TiO2 Composite Film
摘要： The NiO/TiO2 composite films with the NiO content of 3 %, 5 %, 10 %, 13 %, 15 % and 20 % were prepared by mechanical coating technology and subsequent oxidation process. The composition and microstructure of the films were analyzed by X-ray Diffraction (XRD), scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS). The photocatalytic activity was evaluated and the effects of the content of NiO on microstructure and photocatalytic activity of the films were studied. The results show that NiO particles are dispersed in the Ti coatings, and the NiO concentration in the inner layer of the coatings is higher than in the outer layer. With the addition of NiO in the NiO/Ti coating, the ductility is deteriorated and the thickness is reduced of the NiO/Ti coatings. The films with NiO/TiO2/Ti composite microstructure are obtained by the oxidation of NiO/Ti coatings. Photocatalytic efficiency of the films is obviously enhanced with the help of the p-n junction heterostructure in the NiO/TiO2 films. The optimum content of NiO is about 13 %, and the degradation rate of methyl orange solution reaches the maximum value of 88.44 %.
关键词： mechanical coating technology,NiO content,photocatalytic activity,NiO/TiO2 composite films
更新于2025-09-23 15:22:29
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Engineering Tunable Broadband Near-Infrared Emission in Transparent Rare-Earth Doped Nanocrystals-in-Glass Composites via a Bottom-Up Strategy
摘要： Applications of trivalent rare earth (RE3+)-doped light sources in solid-state laser technology, optical communications, biolabeling, and solar energy management have stimulated a growing demand for broadband emission with flexible tunability and high efficiency. Codoping is a conventional strategy for manipulating the photoluminescence of active RE3+ ions. However, energy transfer between sensitizers and activators usually induces nonradiative migration depletion that brings detrimental luminescent quenching. Here, a transparent framework is employed to assemble ordered RE3+-doped emitters to extend the emission spectral range by extracting photons from a variety of RE3+ ions with sequential energy gradient. To block migration-mediated depletion between different RE3+ ions, a nanoscopic heterogeneous architecture is constructed to spatially confine the RE3+ clusters via a 'nanocrystals-in-glass composite' (NGC) structure. This bottom-up strategy endows the obtained RE3+-doped NGC with high emission intensity (nearly one order of magnitude enhancement) and broadband near-infrared emission from 1300 to 1600 nm, which covers nearly the whole low-loss optical communication window. Most crucially, NGC is a versatile approach to design tunable broadband emission for the potential applications in high-performance photonic devices, which also provides new opportunities for engineering multifunctional materials by integration and manipulation of diverse functional building units in a nanoscopic region.
关键词： luminescence,rare earth doping,broadband emission,nanocrystals-in-glass composite,near-infrared emission
更新于2025-09-23 15:22:29
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Significance of Micro and Nano PZT Particles on Dielectric and Piezoelectric Properties of PZT-PVDF Composites
摘要： PZT-PVDF composites were prepared using different particle size of PZT and a hot press apparatus has been used for making samples. The structural and compositional analysis of the composite sample was done by using Scanning Electron Microscope (SEM) and Energy Dispersive Analysis of X-rays (EDAX) respectively. The grain size of the ball milled PZT powder was analyzed using powder X-Ray Diffraction (XRD). The samples were poled at a fixed temperature for about an hour under different poling fields. The dielectric constant (εr) and the piezoelectric properties like piezoelectric strain coefficient (d33) and voltage coefficient (g33) of composite have been analyzed.
关键词： composite,ferroelectric materials,dielectric constant,strain coefficient,voltage coefficient,particle size,lead zirconate titanate
更新于2025-09-23 15:22:29
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Thermal Characterization of a PPy/PLA Composite by Photoacoustic Calorimetry and Photopyroelectric Techniques
摘要： Recently, conductive polymers have attracted attention in the field of advanced materials. Conducting polymers include polypyrrole (PPy), which is a material with commercial applications due to its stability and electrical conductivity. As technology demands increasingly flexible devices, PPy was mixed with a biodegradable and flexible polymer, polylactic acid, in order to create a composite possessing of newer properties. As it is a new material, thermal properties of this composite such as thermal diffusivity, thermal effusivity, specific heat capacity, and thermal conductivity have been investigated through the application of photoacoustic calorimetry and photopyroelectric techniques.
关键词： PPy/PLA composite,Photoacoustic calorimetry,Polymer,Photopyroelectric technique
更新于2025-09-23 15:22:29