Effect of Phosphate-Containing Acrylic Dispersants on Rheological and Dielectric Properties of Carbon Black-Filled Epoxy System

Bui Thanh Son,Nguyen Ngoc Trung,이은성,배진영 한국고분자학회 2012 Macromolecular Research Vol.20 No.6

This article describes the use of copolymeric dispersants with an acrylic backbone and phosphate side groups for formulating carbon black (CB)-epoxy composites. Six phosphate-modified acrylic copolymer dispersants were prepared from the corresponding epoxy-containing acrylic copolymers. The phosphate-modified dispersant with the highest concentration of hydrophobic alkyl chains and typical phosphate moiety groups showed a desirable passivation effect on the CB, and was found to lower the viscosity of the CB-epoxy paste, leading to the well-cured composite after heat treatment. The thick composite film prepared by employing the CB/phosphate-containing dispersant/epoxy paste was built up on a Cu plate by a screen printing process followed by thermal curing. The dielectric properties of the 3.1 vol% CB-filled epoxy film showed a high dielectric constant (K 6280) and a rather low dissipation factor (Df, 61%) @ 1 MHz.

A Facial Synthesis of Ba Doped g-C<SUB>3</SUB>N<SUB>4</SUB> Photocatalyst for Improving Photocatalytic Activity under Visible Light Irradiation

Thanh-Son Bui,Min-Hee Park,Ryeo-Gyeong Youn,Byeong-Kyu Lee 한국대기환경학회 2018 한국대기환경학회 학술대회논문집 Vol.2018 No.10

Facile fabrication of novel Ba-doped g-C₃N₄ photocatalyst with remarkably enhanced photocatalytic activity towards tetracycline elimination under visible-light irradiation

Bui, Thanh Son,Bansal, Palak,Lee, Byeong-Kyu,Mahvelati-Shamsabadi, Tahereh,Soltani, Tayyebeh Elsevier 2020 APPLIED SURFACE SCIENCE - Vol.506 No.-

<P><B>Abstract</B></P> <P>A novel photocatalyst, Ba-doped graphitic carbon nitride (g-C<SUB>3</SUB>N<SUB>4</SUB>), was synthesized via a facial thermal condensation method. Ba at a loading of 2% revealed the highest photocatalytic degradation efficiency of tetracycline (TC) (91.94%) after 120 min of visible light irradiation at an optimal pH of 10. An overall synergy of 69.26% was observed in the case of Ba (2%)-doped g-C<SUB>3</SUB>N<SUB>4</SUB> over pure g-C<SUB>3</SUB>N<SUB>4</SUB>. The remarkable improvement in the TC degradation performance is due to the narrower band-gap energy, the larger surface areas and the lower recombination rate of charge carriers detected through photoluminescence (PL) quenching, suggesting the multiple roles of the Ba doping. The synthesized novel photocatalyst displayed extremely high stability after 5 cycles as confirmed through various characterization techniques. The intermediates generated during the photocatalytic reaction were also detected through liquid chromatography–mass spectrometry (LC-MS) analysis and used to predict the degradation pathway of TC. Photoelectrochemical (PEC) measurements combined with photocatalytic performance obviously demonstrated that Ba doping effectively enhanced the separation of charge carriers and decreased the electron/hole recombination in the g-C<SUB>3</SUB>N<SUB>4</SUB> structure.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ba<B>-</B>doped g-C<SUB>3</SUB>N<SUB>4</SUB> was fabricated via a thermal condensation method. </LI> <LI> A lower recombination rate of photo-induced e<SUP>−</SUP> and h<SUP>+</SUP> pairs in Ba<B>-</B>doped g-C<SUB>3</SUB>N<SUB>4</SUB>. </LI> <LI> 91.94% of tetracycline (TC) was degraded within 120 min irradiation at an optimal pH of 10. </LI> <LI> Ba<B>-</B>doped g-C<SUB>3</SUB>N<SUB>4</SUB> retained high stability even after five cycles of use. </LI> <LI> h<SUP>+</SUP> is the predominant oxidative species for TC photodegradation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Investigation of various cavity configurations for metamaterial-enhanced field-localizing wireless power transfer

Bui, Huu Nguyen,Pham, Thanh Son,Ngo, Viet,Lee, Jong-Wook American Institute of Physics 2017 Journal of Applied Physics Vol.122 No.9

Adsorption of pharmaceuticals onto trimethylsilylated mesoporous SBA-15

Bui, Tung Xuan,Pham, Viet Hung,Le, Son Thanh,Choi, Heechul Elsevier 2013 Journal of hazardous materials Vol.254 No.-

<P><B>Abstract</B></P> <P>The adsorption of a complex mixture of 12 selected pharmaceuticals to trimethylsilylated mesoporous SBA-15 (TMS-SBA-15) has been investigated by batch adsorption experiments. The adsorption of pharmaceuticals to TMS-SBA-15 was highly dependent on the solution pH and pharmaceutical properties (i.e., hydrophobicity (log <I>K</I> <SUB>ow</SUB>) and acidity (p<I>K</I> <SUB>a</SUB>)). Good log–log linear relationships between the adsorption (<I>K</I> <SUB>d</SUB>) and pH-dependent octanol–water coefficients ( K ow pH ) were then established among the neutral, anionic, and cationic compounds, suggesting hydrophobic interaction as a primary driving force in the adsorption. In addition, the neutral species of each compound accounted for a major contribution to the overall compound adsorption onto TMS-SBA-15. The adsorption kinetics of pharmaceuticals was evaluated by the nonlinear first-order and pseudo-second-order models. The first-order model gave a better fit for five pharmaceuticals with lower adsorption capacity, whereas the pseudo-second-order model fitted better for seven pharmaceuticals having higher adsorption capacity. In the same group of properties, pharmaceuticals having higher adsorption capacity exhibited faster adsorption rates. The rate-limiting steps for adsorption of pharmaceuticals onto TMS-SBA-15 are boundary layer diffusion and intraparticle diffusion including diffusion in mesopores and micropores. In addition, the adsorption of pharmaceuticals to TMS-SBA-15 was not influenced by the change of initial pharmaceutical concentration (10–100μgL<SUP>−1</SUP>) and the presence of natural organic matter.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Trimethylsilylated SBA-15 for adsorptive removal of a mixture of 12 pharmaceuticals. </LI> <LI> Hydrophobic interaction as a primary driving force in the adsorption. </LI> <LI> The rate-limiting steps were diffusion through boundary layer, mesopores and micropores. </LI> <LI> Adsorption efficiency was not changed as pharmaceutical concentration varied. </LI> <LI> Adsorption efficiency was not influenced by the presence of natural organic matters. </LI> </UL> </P>

Investigation of various cavity configurations for field-localizing wireless power transfer to small IoT devices

Bui Huu Nguyen(부이 후),Thanh Son Pham(팜 탄손),Jong-Wook Lee(이종욱) 한국통신학회 2018 한국통신학회 학술대회논문집 Vol.2018 No.1

Wave propagation control and switching for wireless power transfer using tunable 2-D magnetic metamaterials

Pham, Thanh Son,Bui, Huu Nguyen,Lee, Jong-Wook Elsevier 2019 Journal of magnetism and magnetic materials Vol.485 No.-

<P><B>Abstract</B></P> <P>Magnetic metamaterials operating at low megahertz frequencies provide various important commercial and research applications. In this work, we investigate the control of wave propagation in two-dimensional (2-D) tunable magnetic metamaterials for wireless power transfer (WPT). The propagation control is achieved by using reconfigurable defect cavities formed in the metamaterial, which allows for the dynamic creation of various waveguide configurations with switching control. The physical mechanism for creating the cavity is described using Fano interference, in which the resonant frequency of the cavity falls into the bandgap of the metasurface. And the routing and transmission control of the proposed waveguide is easily achieved by resonant switching. The proposed approach allows highly localized, strong field confinement in the deep subwavelength scale of 2.6λ × 10<SUP>−3</SUP>. The transmission losses and bandwidths of various dynamically tunable metamaterial waveguides are experimentally characterized. This result can find useful applications for integrated surface wave devices and planar WPT.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Investigation of new type of magnetic metamaterial working at low MHz frequency range. </LI> <LI> Active tunable magnetic metamaterial applied for wireless power transfer. </LI> <LI> A defect cavity is introduced for localization of the magnetic field into deep subwavelength scale. </LI> <LI> New type of low loss 2-D waveguide created by novel defect cavity mode. </LI> <LI> Simple and effective transmission switching control on 2-D metasurface for wireless power transfer. </LI> </UL> </P>

Nano-porous Silicon Microcavity Sensors for Determination of Organic Fuel Mixtures

Van Hoi Pham,Huy Bui,Le Ha Hoang,Thuy Van Nguyen,The Anh Nguyen,Thanh Son Pham,Quang Minh Ngo 한국광학회 2013 Current Optics and Photonics Vol.17 No.5

We present the preparation and characteristics of liquid-phase sensors based on nano-porous silicon multilayer structures for determination of organic content in gasoline. The principle of the sensor is a determination of the cavity-resonant wavelength shift caused by refractive index change of the nano-porous silicon multilayer cavity due to the interaction with liquids. We use the transfer matrix method (TMM)for the design and prediction of characteristics of microcavity sensors based on nano-porous silicon multilayer structures. The preparation process of the nano-porous silicon microcavity is based on electrochemical etching of single-crystal silicon substrates, which can exactly control the porosity and thickness of the porous silicon layers. The basic characteristics of sensors obtained by experimental measurements of the different liquids with known refractive indices are in good agreement with simulation calculations. The reversibility of liquid-phase sensors is confirmed by fast complete evaporation of organic solvents using a low vacuum pump. The nano-porous silicon microcavity sensors can be used to determine different kinds of organic fuel mixtures such as bio-fuel (E5), A92 added ethanol and methanol of different concentrations up to 15%.

A Low-Cost Speech to Sign Language Converter

Le, Minh,Le, Thanh Minh,Bui, Vu Duc,Truong, Son Ngoc International Journal of Computer ScienceNetwork S 2021 International journal of computer science and netw Vol.21 No.3

This paper presents a design of a speech to sign language converter for deaf and hard of hearing people. The device is low-cost, low-power consumption, and it can be able to work entirely offline. The speech recognition is implemented using an open-source API, Pocketsphinx library. In this work, we proposed a context-oriented language model, which measures the similarity between the recognized speech and the predefined speech to decide the output. The output speech is selected from the recommended speech stored in the database, which is the best match to the recognized speech. The proposed context-oriented language model can improve the speech recognition rate by 21% for working entirely offline. A decision module based on determining the similarity between the two texts using Levenshtein distance decides the output sign language. The output sign language corresponding to the recognized speech is generated as a set of sequential images. The speech to sign language converter is deployed on a Raspberry Pi Zero board for low-cost deaf assistive devices.

Visible light-driven photocatalytic degradation of doxycycline using ZnO/g-C₃N₄/biochar composite in aqueous solution

Nguyen Van Hung,Bui Thi Minh Nguyet,Nguyen Huu Nghi,Nguyen Minh Luon,Nguyen Ngoc Bich,Le Van Thanh Son,Nguyen Trung Kien,Dao Ngoc Nhiem,Nguyen Thanh Tuoi,Dinh Quang Khieu 대한환경공학회 2024 Environmental Engineering Research Vol.29 No.4

In the present work, ZnO/g-C₃N₄/biochar was prepared, and it was used for visible-light driven photocatalytic degradation of some colorants (methylene blue, rhodamine B, methyl orange) and some antibiotics (doxycycline, ciprofloxacin, amoxicilline). Biochar was prepared by pyrolysing Phragmites australis biomass. The ZnO/g-C₃N₄/biochar composite was synthesized with the alkaline hydrolysis method. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, transition electron microscopy, energy dispersive X-ray/elemental mapping, ultraviolet-visible-diffuse reflectance spectroscopy, photoluminescence spectroscopy, nitrogen adsorption/desorption isotherms and X-ray photoelectron spectroscopy. The results show that ZnO nanoparticles with a large surface area are highly dispersed on the g-C₃N₄ particle surface and biochar. The composite exhibits superior photocatalytic degradation ability toward doxycycline, a broad-spectrum antibiotic of the tetracycline compared with individual components (ZnO or g-C₃N₄) and satisfies stability after six treatment cycles. The kinetics and degradation mechanisms of doxycyline were also addressed. In addition, the present catalyst also exhibits the photocatalytic degradation of methylene blue, rhodamine B, methyl orange, ciprofloxacin and amoxicillin in visible-light regions.