Materials Letters: X最新文献

An efficient dry electrode is required to effectively record the biopotential signals. This study proposes a dry electrode for ECG monitoring based on highly flexible, conductive, and antibacterial silver nanorods (AgNRs) grown via a novel glancing angle deposition and RGO-PDMS composite matrix. The fabricated electrode possesses good electrical conductivity and skin contact impedance between 70.1 ± 0.7 kΩ to 5.6 ± 1.7 kΩ for frequencies ranging from 40 Hz to 1 kHz, comparable to conventional Ag/AgCl wet electrodes. These electrodes give excellent quality ECG signals and do not cause skin irritation even after several hours of usage. They offer high skin compatibility and good signal quality, which are prominent features for cardiorespiratory monitoring.

An organic crystalline salt − 2,4-Diamino-6-methyl-1,3,5-triazin- 1-ium hydrogen oxalate (DMTO) has hydrogen interactions viz. NH⋯O, CH⋯O, NH⋯N and OH⋯O gives interesting vibrational effect. X-ray diffraction study reveals that DMTO is crystallized in triclinic centrosymmetric space group P-1 as expected. Structural as well as the vibrational spectra have been discussed on the basis of density functional theory (DFT) using B3LYP hybrid functional with the basis set 6–311++G(d,p). Acidic proton of the oxalic acid (OA) is transferred to 2,4-diamino-6-methyl-1,3,5-triazine (DAMT) and giving rise to singly protonated 2,4-diamino-6-methyl-1,3,5-triazinium ion.

Cobalt-copper-zinc ferrite (CoCuZnF) nanoparticles were synthesized using the precipitation method. The characterization of CoCuZnF was carried out using powder XRD, Raman, IR, UV–vis, and FEG-SEM. The TG-DSC data of NTO, and nNTO containing the catalyst was used to study the thermal decomposition behavior. Three non-isothermal methods were used to evaluate the kinetic parameters. The kinetics data suggests that incorporation of CoCuZnF additive can effectively decrease the high activation energy of NTO by ∼83–88 kJ mol⁻¹ and nNTO (∼205–216 kJ mol⁻¹). The decomposition of both NTO and nNTO was faster in the presence of CoCuZnF, suggesting its plausible use in the high explosive munitions containing NTO.

This paper presents results of application of Ultrasonic Waves UW in civil engineering. The measurement has been performed by ultrasonic reflection technique using a transducer with central frequency 0,5MHz. Several methods of analysis and signal processing have been applied to detect the position of reflections and to measure the time of flight between two echoes related to the reflection at the mortar interfaces. The experiments performed in the laboratory are carried to determine the ultrasonic velocity of the wave backscattered by samples. This allowed determining the ultrasonic velocity of UW in the mortar in order to deduce the durability of each mortar according to its microstructure. The objective is to make a comparative study of the various methods of analysis of the ultrasonic signals as: Continuous Wavelet Transform (CWT), Wigner Ville (WVD), Pseudo Wigner–Ville distribution (PWVD), Smoothed Pseudo Wigner–Ville Distribution (SPWVD) and Hilbert Transform (HT).

In today’s scenario, a number of nanocomposites are evidencing handy control in in vitro biological studies like anti-inflammatory and antidiabetic activity. Since the nanocomposite action and mechanism are totally different from others, like simple molecules of antibiotics. This work described a facile one-pot hydrothermal synthesis of the rGO-MnO₂ nanocomposite. The prepared samples were characterized and confirmed by XRD, UV, SEM, EDX, and XPS studies. Furthermore, the catalytic performance evolved through in vitro biological applications such as anti-inflammatory and antidiabetic activities. rGO-MnO₂ nanocomposite has more biological activity than pure MnO₂ nanoparticles, as demonstrated by the results.

Zinc-Nickel Ferrite (Zn_(1−x)Ni_xFe₂O₄) nanoparticles were synthesized by solution combustion method using urea as a fuel and varying the cation concentration (x = 0, 0.2, 0.4, 0.6, 0.8, 1). The effects of cation concentration, on the crystallite size, morphology, absorption properties have been studied. The X-ray diffraction and FTIR results confirm the formation of single-phase spinel structure of Zinc-Nickel Ferrite nanoparticles. FESEM and TEM study reveals the formation of uniform spherical shape distribution of Zn_(1−x)Ni_xFe₂O₄ nanoparticles. The bandgap values were calculated for the prepared samples using UV–Visible spectrophotometer.

Surface-enhanced Raman spectroscopy (SERS) exhibits intriguing analytical application owing to their non-invasive method, specificity, and sensitivity. However, development of tunable SERS active substrate remains a challenge. Herein, we report a straightforward chronoamperometric co-deposition strategy, utilizing a reducing agent, to form bimetallic coating comprised of Cu/Ag on silica substrate, where alteration of deposition current endows fractional variations in the nucleation/growth of Cu²⁺ → Cu⁺/Cu⁰ and Ag²⁺ → Ag⁺/Ag⁰. Properties of optical reflectance, surface chemistry, topography, and nanocrystallite cluster orientation were characterized. Experimental results confirm bimetallic coating with large proportion of Ag on Cu matrix could enable better SERS behavior with studied model, Rhodamine 6G.

This article considers the nanoparticles suspended in the gas phase in the vicinity of a 3D-printed surface during additive manufacturing via Laser Beam Powder Bed Fusion (LB-PBF) and Directed Energy Deposition (DED). The results of this research show that the primary pollutants during the laser additive manufacturing using metal powder are aggregated core–shell nanoparticles with an average particle size of about 10 nm. High-resolution microscopy shows the chemical composition of the volume and surface of each particle; in particular, the “core” consists of Fe, Cr, and Ni atoms and the “shell” is a thin oxide layer.

Uniaxial tensile tests were carried out on nickel sheets containing only few grains across the thickness thus presenting a so-called multicrystalline state. Pristine sheets used as reference and substrates covered by a nickel layer deposited by physical vapor deposition (magnetron sputtering) were studied. Results attest that the surface treatment affects the plastic deformation mechanisms by playing the role of a blocking barrier to dislocation movement which leads to a significant improvement of mechanical performances. The surface restructuring of the nickel sheets is efficient to stop dislocation escape through free surfaces and allows a mechanical improvement of the well-known strong mechanical softening of the multicrystals.

This work demonstrates how an interference pattern can improve the performance of remote laser cutting of pure copper foils, making the cutting process effective even for a low power laser source. The proof of concept is carried out by using a nanosecond laser source with a pulse duration of 5 ns, coupled with a two-beam scanning interference setup, producing a spatial period of 12.5 µm. In the experiments, processing parameters as pulse-to-pulse distance, laser power and scanning speed are varied, to optimize the foil breakthrough and their effect on the generated material modifications are investigated. A comparison between the processing results employing the interference pattern and single beam with a Gaussian energy distribution is carried out. While the single beam process is not sufficient for cutting a 10 µm thin metallic foil, the interference treatment shows an improvement over 100%. In addition, only small spatter formations are detected, with average particle sizes of 1.75 ± 0.82 µm on the top side of the foil. The bottom side of a fully separated copper foil only depicts small spatter formations of less than 1 µm.