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We consider a multistage stochastic discrete program in which constraints on any stage might involve expectations that cannot be computed easily and are approximated by simulation. We study a sample average approximation (SAA) approach that uses nested sampling, in which at each stage, a number of scenarios are examined and a number of simulation replications are performed for each scenario to estimate the next-stage constraints. This approach provides an approximate solution to the multistage problem. To establish the consistency of the SAA approach, we first consider a two-stage problem and show that in the second-stage problem, given a scenario, the optimal values and solutions of the SAA converge to those of the true problem with probability one when the sample sizes go to infin... |
Magnetic absorbing materials suffer from corrosion and aging in harsh environments such as ocean and acid, which limits their practical applications. Therefore, it is important to design a material with excellent corrosion resistance and microwave absorption properties. Herein, perfluorooctyltriethoxysilane (PFOTES) modified carbonyl iron (CI) with tunable PFOTES content was prepared by the sol–gel method. The presence of PFOTES layer improved the corrosion resistance and microwave absorption of CI. The good hydrophobicity of PFOTES layer with the static contact angle of 129.73° hindered the contact of corrosive medium with CI core. The corrosion current of CI@PFOTES composite decreased significantly, and the corrosion rate was reduced by three orders of magnitude. The surface coati... |
The rational design of nanomaterials for electrochemical nanosensors from the perspective of structure–property–performance relationships is a key factor in improving the analytical performance toward residual antibiotics in food. We have investigated the effects of the crystalline phase and copper loading amount on the detection performance of Cu–MoS2 nanocomposite-based electrochemical sensors for the antibiotic chloramphenicol (CAP). The phase composition and copper loading amount on the MoS2 nanosheets can be controlled using a facile electrochemical method. Cu and Cu2O nanoparticle-based electrochemical sensors showed a higher CAP electrochemical sensing performance as compared to CuO nanoparticles due to their higher electrocatalytic activity and conductivity. Moreover, the de... |
Open access (OA) publishing is beneficial for researchers to improve recognition, representation, and visibility in academia. However, few studies have been conducted for studying the association between gender and OA publishing likelihood. Therefore, the current study explores the impacts of gender-based authorship structures on OA publishing in Vietnamese social sciences and humanities. Bayesian analysis was performed on a dataset of 3122 publications in social sciences and humanities. We found that publications with mixed-gender authorship were most likely to be published under Gold Access terms (26.31–31.65%). In contrast, the likelihood of publications with the solely male or female author(s) was lower. It is also notable that if female researcher(s) held the first-author posit... |
This study aims to develop the models of emission and fuel consumption during idling of motorcycles (MCs) in Hanoi, including the unsteady and steady idling stages. Five MC models commonly used in Hanoi were selected to measure the instantaneous emission and fuel consumption rates under the controlled conditions at the laboratory conditions. The instantaneous emission and fuel consumption models during idling were developed for the test MCs in the unsteady idling stage. The R2 of obtained models are higher than 0.9. The average emission and fuel consumption rates in the steady idling stages were determined. The average idling emissions of pollutants CO, CO2, HC and NOx were 60.9, 534.3, 10.3 and 1.8 g/h, respectively. The average fuel loss during idling is around 180 g/h. The emissi... |
MoS2-GO composites were fabricated by an ultrasonication method at room temperature. Raman spectra, emission scanning electron microscopy (SEM), and transmission electron microscopy (TEM) images were used to study the structural characteristics, morphologies, and sizes of the synthesized materials. An MoS2-GO/SPE (screen-printed electrode) was prepared by a facile dropping method and acted as an effective electrochemical sensor toward clenbuterol (CLB) and 4-nitrophenol (4-NP) detection. Based on the obtained results, the influence of analyte molecular structure on the adsorption ability and electronic interoperability between the targeted analyte and electrode surface were investigated in detail and discussed as well, through some electrochemical kinetic parameters (electron/proton... |
Herein, we demonstrate that 2-difluoromethylpyridine is a bioisosteric replacement of pyridine-N-oxide. Using the quorum sensing inhibitor 4NPO as a model compound, a library of 2-difluoromethylpyridine derivatives was designed, synthesized, and evaluated toward quorum sensing activity, biofilm formation, anti-violacein activity, and protease activity. As a result, compounds 1 (IC50 of 35 ± 1.12 μM), 5 (IC50 of 19 ± 1.01 μM), and 6 (IC50 of 27 ± 0.67 μM) showed a similar or better activity in comparison to 4NPO (IC50 of 33 ± 1.12 μM) in a quorum sensing system of Pseudomonas aeruginosa. In addition, compounds 1, 5, 6, and 4NPO showed good antibiofilm biomass of Pseudomonas aeruginosa and reduced violacein production in Chromobacterium violaceum. In terms of protease activity, compou... |
This paper studies the spectrum allocation problem between spectrum service providers (SSPs) and terminals equipped with orthogonal frequency division multiplexing (OFDM) integrated radar and communication (IRC) systems. In particular, IRC-equipped terminals such as autonomous vehicles need to buy spectrum for their radar functions, e.g., sensing and detecting distant vehicles, and communication functions, e.g., transmitting sensing data to road-side units. The terminals determine their spectrum demands from the SSPs subject to their IRC performance requirements, while the SSPs compete with each other on the service prices to attract terminals. Taking into account the complicated interactions, a hierarchical Stackelberg game is proposed to reconcile the spectrum demand and service p... |
Zinc Ferrite (ZnFe2O4, ZFO) nanoparticles (NPs) as a multi-sensing material are successfully synthesised via a hydrothermal method and a following annealing treatment. The as-prepared ZFO-NPs were applied in electrochemical and mass-type sensors by depositing NPs directly on the screen-printed electrode (SPE) and the active electrode of a quartz crystal microbalance (QCM), respectively. The obtained results show the ZFO-NPs possessed excellent detection performance to sulphur dioxide (SO2) in the range of 2.5–20 ppm at room temperature. QCM sensor coated with ZFO-NPs showed a high response, good repeatability, as well as short-response time. Moreover, the modified-SPE with ZFO-NPs sensitively responded to chloramphenicol (CAP) of concentration range from 5 to 50 μM in phosphate buff... |
This work presents a gas-phase approach for the synthesis of Cu2O/TiO2 powder-based photocatalysts using atomic layer deposition (ALD). The process is carried out in a fluidized bed reactor working at atmospheric pressure using (trimethylvinylsilyl)-hexafluoroacetulacetonate copper(I) as the Cu-precursor and H2O vapor as the oxidizer. The saturating regime of the chemical reactions and the linear growth of ALD are achieved. In combination with the unsaturated regime, the ALD approach enables the deposition of ultrasmall Cu2O clusters with average diameters in the range of 1.3–2.0 nm, narrow particle size distributions and tunable Cu2O loadings on P25 TiO2 nanoparticles. The photocatalytic performance of Cu2O/TiO2 photocatalysts is investigated by the degradation of organic dyes, inc... |
