• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2224-2228
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• 2012

This study describes the ability of capillary electrochromatography (CEC) for the determination of imidacloprid and carbendazim in tomato samples. A novel liquid crystal crown ether modified hybrid silica monolithic column was synthesized, characterized and developed as separation column for the first time. Baseline separation of imidacloprid and carbendazim could be achieved using a mobile phase containing 90% (v/v) 20 mmol/L phosphate buffer (pH 7.0) and 10% (v/v) acetonitrile. The matrix matched calibration curves were linear with correlation coefficient $r^2$ > 0.9998 in the range of 0.20-10.00 mg/L. The limits of detection for imidacloprid and carbendazim were 0.061 and 0.15 mg/kg, respectively, which were below the maximum residue limits established by the European Union as well as Codex Alimentarius. Average recoveries for imidacloprid and carbendazim varied from 101.6-108.0% with relative standard deviations lower than 6.3%. This method was applied to the analysis of tomatoes collected from local markets.

• Corrosion Science and Technology
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• v.18 no.5
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• pp.168-174
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• 2019

The sol-gel methodology has been applied successfully in the synthesis of a novel hybrid coating based on dimethoxymethyl-n-octadecylsilane precursor. The newly synthesized parent coating was functionalized further with two commercially-available corrosion-inhibitive pigments Moly-$white^{(R)}$ 101-ED and Hfucophos $Zapp^{(R)}$, applied to mild steel panels, and immersed continuously in 3.5% NaCl electrolytic solution for 288 h. The corrosion protection performance of the prepared functional coatings was evaluated using electrochemical impedance spectroscopy (EIS) and DC polarization techniques. An enhancement in the barrier properties has been revealed from the electrochemical characterization data of the hybrid films, in comparison with untreated mild steel substrates following long-term immersion in 3.5% NaCl. The corrosion resistance properties of the newly developed coatings over mild steel substrates found to be largely dependent on the type of the loaded inhibitive pigment in which the Moly-white inhibitor has a positive impact on the corrosion protection performance of the parent coating, while an opposite behavior was observed upon mixing the base polymeric matrix with the commercially-available Zapp corrosion inhibitor.

• Journal of Information Display
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• v.10 no.1
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• pp.33-36
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• 2009

A new hybrid silicon thin-film transistor (TFT) fabrication process using the DPSS laser crystallization technique was developed in this study to realize low-temperature poly-Si (LTPS) and a-Si:H TFTs on the same substrate as a backplane of the active-matrix liquid crystal flat-panel display (AMLCD). LTPS TFTs were integrated into the peripheral area of the activematrix LCD panel for the gate driver circuit, and a-Si:H TFTs were used as a switching device of the pixel electrode in the active area. The technology was developed based on the current a-Si:H TFT fabrication process in the bottom-gate, back-channel etch-type configuration. The ion-doping and activation processes, which are required in the conventional LTPS technology, were thus not introduced, and the field effect mobility values of $4\sim5cm^2/V{\cdot}s$ and $0.5cm^2/V{\cdot}s$ for the LTPS and a-Si:H TFTs, respectively, were obtained. The application of this technology was demonstrated on the 14.1" WXGA+(1440$\times$900) AMLCD panel, and a smaller area, lower power consumption, higher reliability, and lower photosensitivity were realized in the gate driver circuit that was fabricated in this process compared with the a-Si:H TFT gate driver integration circuit

• Environmental Engineering Research
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• v.22 no.2
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• pp.186-192
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• 2017

The carbon paste electrode (CPE) was modified with the pristine bentonite and hybrid material (HDTMA-modified bentonite). The modified-CPEs are then employed as working electrode in an electrochemical detection of As(V) from aqueous solutions using the cyclic voltammetric measurements. Cyclic voltammograms revealed that As(V) showed reversible behavior onto the working electrode. The hybrid material-modified carbon paste electrode showed significantly enhanced electrochemical signal which was then utilized in the low level detection of As(V). Moreover, the studies were conducted at neutral pH conditions. The electrochemical studies were conducted with scan rates (20 to 200 mV/s) to deduce the mechanism of redox processes involved at the electrode surface. The anodic current was linearly increased, increasing the concentration of As(V) from 5.0 to $35.0{\mu}g/g$ using the hybrid material-modified electrode. This provided fairly a good calibration line for As(V) detection. The presence of varied concentrations of As(III) in the determination of total arsenic was studied. The influence of several cations and anions viz., Cu(II), Mn(II), Zn(II), Pb(II), Cd(II), Fe(III), $Cl^-$, $NO_3{^-}$, $PO_4{^{3-}}$, EDTA and glycine in the detection of As(V) from aqueous solution was also studied. Further, in an attempt to simulate the real matrix analysis, the tap water sample was spiked with As(V) and subjected for As(V) detection using the modified-CPE.

• Advances in materials Research
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• v.12 no.2
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• pp.119-131
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• 2023

The development of sustainable composites materials, from recycled polymeric materials and waste from the wood industry and stone processing, allows reducing the volume of these by-products, minimizing impacts on health and the environment. Nowadays, Polypropylene (PP) is the most recycled polymer in industry, while the furniture industry has increasingly used timber felled from sustainable forest plantations as a eucalypt. The powder tailing from the ornamental stone extraction and processing industry is commonly disposed of in the environment without previous treatment. Thus, the technological option for the development of composite materials presents itself as a sustainable alternative for processing and manufacturing industries, enabling the development of new materials with special technical features. The results showed that powder granite particles may be incorporated into the polypropylene matrix associated with short eucalyptus fibres forming green hybrid composites with potential application in structural engineering, such as transport and civil construction industries.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.33-41
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• 2000

Fiber reinforced metal laminates(FRMLs) were new type of hybrid materials. FRMLs consist of high strength metals(Al 5052-H34) and laminated fiber with structural adhesive bond. The effect of resin mixture ratios on the fatigue crack propagation behavior and mechanical properties of aramid fiber reinforced aluminum composites was investigated. The epoxy, diglycidylether of bisphenol A(DGEBA), was cured with methylene dianiline(MDA) with or without an accelerator(K-54). Eight kinds of resin mixture ratio were used for the experiment ; five kinds of FRMLs(1)(mixture of epoxy and curing agent) and three kinds of FRMLs(2)mixture of epoxy, curing agent and accelerator). The characteristic of fatigue crack propagation behavior and mechanical properties FRMLs(2) shows more effecting than that of FRMLs(1).

• Steel and Composite Structures
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• v.44 no.5
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• pp.707-720
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• 2022

In the present work, bending and free vibration analyses of multilayered functionally graded (FG) graphene platelet (GPL) and fiber-reinforced hybrid composite beams are carried out using the parabolic function based shear deformation theory. Parabolic variation of transverse shear stress across the thickness of beam and transverse shear stress-free conditions at top and bottom surfaces of the beam are considered, and the proposed formulation incorporates a transverse displacement field. The present theory works only with four unknowns and is computationally efficient. Hamilton's principle has been employed for deriving the governing equations. Analytical solutions are obtained for both the bending and free vibration problems in the present work considering different variations of GPLs and fibers distribution, namely, FG-X, FG-U, FG-Λ, and FG-O for beams having simply-supported boundary condition. First, the matrix is assumed to be strengthened using GPLs, and then the fibers are embedded. Multiscale modeling for material properties of functionally graded graphene platelet/fiber hybrid composites (FG-GPL/FHRC) is performed using Halpin-Tsai micromechanical model. The study reveals that the distributions of GPLs and fibers have significant impacts on the stresses, deflections, and natural frequencies of the beam. The number of layers and shape factors widely affect the behavior of FG-GPL-FHRC beams. The multilayered FG-GPL-FHRC beams turn out to be a good approximation to the FG beams without exhibiting the stress-channeling effects.

• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.735-740
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• 2002

In order to improve the anti-fogging property of polymer films, organic-inorganic hybrid coating solutions which have good hydrophilic property and transmission in the range of visible light were synthesized by the sol-gel method. The coating solutions were prepared by adding glycidoxypropyl trimethoxysilane(GPS) to a colloidal silica(15 nm) suspension(Ludox). GPS as silane coupling agent forms strong bonds to the colloidal silica and surrounding polymer matrix and links two different materials together. Solutions prepared by addition of GPS at the acidic condition resulted in coatings that were less prone to cracking, while those at the basic condition caused coatings with more cracking. These resulted in better hydrophilic property and transmission in the range of visible light for the solution prepared at the acidic condition(pH 2). Compared with coatings under acidic conditions, coatings prepared at basic conditions showed worse hydrophilic property and transmission in the range of visible light.

• Journal of the Korean Ceramic Society
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• v.34 no.9
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• pp.993-1001
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• 1997

The (0.8PPV+0.2DMPPV) copolymer and silica/borosilicate composites were synthesized by sol-gel process. The organic-inorganic hybrid solution was prepared by using of (0.8PPV+0.2DMPPV) copolymer precursor solution as a raw material for organic components and TEOS and TMB for glass components. Then by drying the solution in vacuum at 5$0^{\circ}C$ for 7days and subsequent heat treatment in vacuum at 15$0^{\circ}C$~30$0^{\circ}C$ for 2h~72h with heating rate of 0.2$^{\circ}C$/min and 1.8$^{\circ}C$/min, the organic-inorganic composites were synthesized. Microstructural evolution of the composites was characterized by DSC, IR spectrocopy, UV/VIS spectroscopy, and TEM. Elimination of the polymer precursor and degradation of the polymer were observed by DSC and Si-O and trans C=C absorption peaks were identified by IR spectra. The polymer was found to be successfully incorporated into the glass matrix and it was confirmed by the absorption peaks from the polymer in the UV/VIS spectra and the TEM results. The absorption peak of the composites was found to shift toward short wavelength side compared to that of the pure polymer and the amount of the blue shift increased with increasing the heat treatment temperature and heat treatment time and with decreasing the heating rate.

• Smart Structures and Systems
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• v.25 no.5
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• pp.605-617
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• 2020

The existence of damages in structures causes changes in the physical properties by reducing the modal parameters. In this paper, we develop a two-stages approach based on normalized Modal Strain Energy Damage Indicator (nMSEDI) for quick applications to predict the location of damage. A two-dimensional IsoGeometric Analysis (2D-IGA), Machine Learning Algorithm (MLA) and optimization techniques are combined to create a new tool. In the first stage, we introduce a modified damage identification technique based on frequencies using nMSEDI to locate the potential of damaged elements. In the second stage, after eliminating the healthy elements, the damage index values from nMSEDI are considered as input in the damage quantification algorithm. The hybrid of Teaching-Learning-Based Optimization (TLBO) with Artificial Neural Network (ANN) and Particle Swarm Optimization (PSO) are used along with nMSEDI. The objective of TLBO is to estimate the parameters of PSO-ANN to find a good training based on actual damage and estimated damage. The IGA model is updated using experimental results based on stiffness and mass matrix using the difference between calculated and measured frequencies as objective function. The feasibility and efficiency of nMSEDI-PSO-ANN after finding the best parameters by TLBO are demonstrated through the comparison with nMSEDI-IGA for different scenarios. The result of the analyses indicates that the proposed approach can be used to determine correctly the severity of damage in beam structures.