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- Quan-Hoang Vuong (27)
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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... |
Fingerprint-inspired elastomeric grating meta-skin (EGMS) is herein fabricated to investigate the chirality of fingerprints. The EGMS is made by a facile nanoimprinting method with a diffraction grating as a template using polydimethylsiloxane, followed by gold deposition. The chirality of the surface is caused by symmetry breaking, induced by the pattern (P) and curvature (T). Furthermore, the chiroptical properties of EGMS are reconfigurable through the control of the skew angle (θ), which is the angle between P and T. The chiroptical properties of a fingerprint are also shown and interpreted in this perspective. On the basis of the results, we suggest the strategy to impart chirality on the surface, which is reconfigurable by controlling P and T. It will be a useful method to pro... |
In this research, we proposed the concept of “unusual transformation,” which realizes transformation between two very different image sets as an extension of CycleGAN. CycleGAN is a new deep-learning-based AI technology that can realize transformation between two image sets. Although conventional CycleGAN researchers have tried transformation between two similar image sets, we applied CycleGAN to the transformation of two very different image sets such as between portraits photos and Ikebana or Shan-Shui paintings. Then to obtain a better result, we improved CycleGAN by adding a new loss function and developed “UTGAN (Unusual Transformation GAN).” We found that by using UTGAN, portrait photos and animal photos are transformed into Ikabana-like and Shan-Shui-like images. Then we carr... |
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... |
We study a solution approach for a staffing 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 to customers. We consider a common situation in which the arrival rates are unobserved random variables for which preliminary forecasts are available in a first stage when making the initial staffing decision. In a second stage, more accurate forecasts are obtained and the staffing may have to be modified at a cost, to meet the constraints. This leads to a challenging two-stage stochastic optimization problem in which the quantities involved in the (nonlinear) constraints can only be estimated via simulation, so several independent simulations are required for each first-level scenario. We p... |
A large number of piezoelectric polymers have been studied and applied widely recently and become an attractive topic in both material science and applied engineering fields. Piezoelectric polymers such as Poly(vinyl fluoride) and Poly(γ-benzyl, L-glutamate) fabricated in nanofibers have shown impressive properties in the aspect of low weight, high flexibility and high piezoelectricity. One of the major parameters influencing to the piezoelectricity of electrospun fibers is the orientation. This paper reviews the contribution of fiber orientation to the piezoelectricity properties and the technique to manipulate the orientation. The research group introduces for the first time a fully integrated and compact electrospinning system which is low cost and suitable for both lab-scale and... |
Turbine blades have a very special structure. Previously, their manufacture was mainly done by casting in metal molds. This paper presents the results of research on the effects of technological parameters on the accuracy and surface roughness of turbine blades when machining on the 5-axis CNC milling machines. In the study, reverse engineering method was used to create the file designed according to the template, and the machining programming was done on Mastercam software, using the Postprocessor to output the machining code suitable for machining on the CNC milling machines. Taguchi method is applied in experiments, analyzing the influence of turbine blade machining technology parameters. Research results show that the feed rate plays the most important role to minimize the surfa... |
In this work, we are interested in studying the parallel drone scheduling traveling salesman problem (PDSTSP), where deliveries are split between a truck and a fleet of drones. The truck performs a common delivery tour, while the drones are forced to perform back and forth trips between customers and a depot. The objective is to minimize the completion time coming back to the depot of all the vehicles. We present a hybrid ant colony optimization (HACO) metaheuristic to solve the problem. Our algorithm is based on an idea from the literature that represents a PDSTSP solution as a permutation of all customers. And then a dynamic programming is used to decompose the customer sequence into a tour for the truck and trips for the drones. We propose a new dynamic programming combined with ... |
