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- Quan-Hoang Vuong (27)
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This article presents a cylinder-type magnetic camera (CMC) system in nondestructive testing (NDT) of a heat exchanger (HX) tube. The CMC system is developed for the inspection of corrosion on HX tubes of nuclear power plants. The CMC probe works based on the principle of eddy current testing, in which a single-large bobbin coil is used to supply eddy current on the tube, and a matrix array of InSb Hall sensor is used to measure the electromagnetic field around the corrosion. The CMC system can measure both the real and imaginary components of the magnetic field. The CMC system can operate in two modes: single-line scan mode by selecting a single-line Hall sensor or area scan mode by the electrical scan. The limitations and advantages of each operation mode will be presented. The CM... |
In this study, we have investigated the influence of crystallinity, phase ratio, and heterojunction formation on the sensing performance of ZnO/ZnFe2O4 (ZnO/ZFO) nanocomposite-based electrochemical sensors for the detection of furazolidone (FZD) antibiotic drug. Results obtained show that the crystallinity and phase ratio of ZnO/ZFO nanocomposites have decisive effects on their electron transfer and active site density. Tuning the crystallinity and ZnO content of ZnO/ZFO nanocomposites is an effective way to enhance the FZD electrochemical sensing performance. Findings from this research suggested that the formation of ZnO/ZFO heterojunction could significantly improve their electrochemical responses for FZD due to arising of the internal electric field and redistribution of Zn2+, F... |
In the current work, we report the on-chip fabrication of a low-temperature H2S sensor based on p-type Co3O4 nanofibers (NFs) using the electrospinning method. The FESEM images show the typical spider-net like morphologies of synthesized Co3O4 NFs with an average diameter of 90 nm formed on the comb-like electrodes. The EDX data indicate the presence of Co and O elements in the NFs. The XRD analysis results confirm the formation of single-phase cubic spinel nanocrystalline structures (Fd3 m) for the synthesized Co3O4 NFs. The Raman results are in agreement with the XRD data through the presence of five typical vibration modes of the nanocrystalline Co3O4. The gas sensing properties of the fabricated Co3O4 NF sensors are tested to 1 ppm H2S within a temperature range of 150 °C to 450... |
The role of magnon-phonon coupling in the low-temperature behavior of the spin Seebeck effect (SSE) in YIG/Pt has been puzzling for more than a decade. To elucidate the origin of the anomalous peak around 80 K, we investigate the temperature evolution of SSE, spin Hall magnetoresistance (SMR), and magnetic anisotropy in the same YIG/Pt heterostructure. We find that these effects, along with magnetic damping, show the peaks at the same temperature (∼80 K). This simultaneous occurrence, where no heat is applied in the case of SMR, rules out the phonon-magnon drag related origin of SSE in the YIG/Pt system. We further show that the intrinsic surface anisotropy behavior in YIG is responsible for controlling the SSE, SMR, and magnetic damping in the YIG/Pt structure. Our findings not onl... |
An efficient colorimetric probe based on surface-functionalized silver nanoparticles (AgNPs) was prepared for sensitive thiram pesticide detection in water samples. The influence of various surface capping agents including polyhexamethylene biguanide hydr |
Herein, we report a green, expeditious, and practically simple protocol for direct coupling of carboxylate salts and ammonium salts under ACN/H2O conditions at room temperature without the addition of tertiary amine bases. The water-soluble coupling reagent EDC·HCl is a key component in the reaction. The reaction runs smoothly with unsubstituted/substituted ammonium salts and provides a clean product without column chromatography. Our reaction tolerates both carboxylate (which are unstable in other forms) and amine salts (which are unstable/volatile when present in free form). We believe that the reported method could be used as an alternative and suitable method at the laboratory and industrial scales |
COVID-19, caused by SARS-CoV-2, has led to a global pandemic. The World Health Organization has also declared an infodemic (ie, a plethora of information regarding COVID-19 containing both false and accurate information circulated on the internet). Hence, it has become critical to test the veracity of information shared online and analyze the evolution of discussed topics among citizens related to the pandemic. |
Orange-red-emitting Eu3+-doped Ca9Gd(PO4)7 phosphors have been obtained by a sol-gel technique. These phosphors, excited by UV (270 nm) and near UV light (394 nm), emit orange-red light in the range of 580–710 nm. The Ca9Gd(PO4)7:7 mol% Eu3+ phosphor annealed at 1100 °C shows the highest PL intensity. Judd-Ofelt analysis reveals that the neighbor surroundings of Eu3+ ions are asymmetric, and the lowest asymmetry value is found at the dopant ratio of 7 mol%. The optimal phosphor excited by the wavelength of 394 nm displays an excellent thermal stability (∼76.4 % at 160 °C) with an activation energy of 0.163 eV. The corresponding CIE chromaticity coordinates (x; y) and color purity are calculated to be (0.5849; 0.3635) and 84.6 %, respectively. The quantum efficiency values of the Ca9... |
This paper concerns the staffing optimization problem in multi-skill call centers. The objective is to find a minimal cost staffing solution while meeting a target level for the quality of service (QoS) to customers. We consider a staffing problem in which joint chance constraints are imposed on the QoS of the day. Our joint chance-constrained formulation is more rational capturing the correlation between different call types, as compared to separate chance-constrained versions considered in previous studies. We show that, in general, the probability functions in the joint-chance constraints display S-shaped curves, and the optimal solutions should belong to the concave regions of the curves. Thus, we propose an approach combining a heuristic phase to identify solutions lying in the... |
Low driving field-induced large strain in ternary lead-free Na0.5Bi0.5TiO3-SrTiO3-ABO3 piezoceramics In this letter, three ternary lead-free Na0.5Bi0.5TiO3-SrTiO3-ABO3 piezoceramics (ABO3 = LiNbO3, BaZrO3, and LaFeO3) were studied. The addition of ABO3 into Na0.5Bi0.5TiO3-SrTiO3 ceramic induces a ferroelectric tetragonal-to-ergodic relaxor pseudocubic phase transition, resulting in the significant disruption of ferroelectric order with the shift of the ferroelectric-relaxor transition temperature down to below room temperature. The conventional furnace sintering and microwave sintering methods are conducted in this study to improve the electric field-induced strain properties of BNST-LN piezoceramic. Interestingly, the Na0.5Bi0.5TiO3-SrTiO3-LiNbO3 sample sintered via microwave sintering method shows an ultrahigh normalized strain of 995 pm/V at an ultralow driving field of 2 kV/mm,... |
