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Reversibly-propagational metamaterial absorber for sensing application
Tung, Bui Son,Khuyen, Bui Xuan,Yoo, Young Joon,Rhee, Joo Yull,Kim, Ki Won,Lam, Vu Dinh,Lee, Young Pak World Scientific Publishing Company 2018 Modern physics letters. B, Condensed matter physic Vol.32 No.4
<P>We investigated a reversibly-propagational metamaterial perfect absorber (MPA) for <I>X</I> band using two separated identically-patterned copper layers, which were deposited on continuous dielectric FR-4 layers. By adjusting oblique incidence, two separated resonances are excited, then come close to each other and is finally merged to be a perfect absorption peak at 10.1 GHz. The nature of resonance is the quadrupole mode instead of the fundamental resonances in common MPAs. The mechanism of perfect absorption is the coupling of two quadrupole resonances at their superposition, leading to an enhancement of energy absorption. Finally, we numerically presented the capability of sensing thin resonant substance using the proposed MPA. The characteristic resonance of substance, which does not appear on the absorption spectrum at the limited thickness of bare substance layer, is detected with a great magnitude of signal by exploiting the absorption resonance of MPA. Our work provides another way to obtain the reversibly-propagational absorption by controlling the incident angle instead of the geometrical structure, and might be useful for the potential devices based on MPA such as detectors and sensors.</P>
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>
Metamaterial Perfect Absorber Using the Magnetic Resonance of Dielectric Inclusions
Nguyen Van Dung,Bui Son Tung,Bui Xuan Khuyen,Young Joon Yoo,YoungPak Lee,Joo Yull Rhee,Vu Dinh Lam 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.8
In this report, we introduce a stable metamaterial perfect absorber at GHz frequency based on a novel design of a Mie-type resonance. A single perfect absorption peak is achieved at 9.54 GHz, and the influence of the structural parameters on the absorption behavior is studied; the results were consistent with dielectric-resonator theory. The absorption is demonstrated to be polarizationinsensitive; furthermore, the absorber structure can work for a wide incident angle without any change in the resonance peak. Our absorber structure can also control 47% of the resonance peak’s position by changing the temperature of the dielectric layer. Our absorber structure can also be applied as an electromagnetic-wave absorber for wide-incident-angle, thermally-controllable devices.
High-performance double-sided absorber, based on metamateria
최민기,김영주,황지섭,Bui Xuan Khuyen,Bui Son Tung,Liang-Yao Chen,이영백 한국물리학회 2019 Current Applied Physics Vol.19 No.11
We propose a double-sided metamaterial perfect absorber (MPA) at microwave frequencies, showing absorption of 96.8% at 8.45 GHz. By employing identical front metal-patterned layer for the backside of MPA, it presents the same performance for the incident wave from both sides. Minimization of the reflectance and the transmission, by matching the impedance of free space with that of the MPA and by increasing the imaginary part of refractive index, leads to high absorption. We demonstrated the absorption mechanism with the distribution of power loss and surface current at the absorption frequencies. The polarization-insensitivity was also achieved due to the symmetric pattern, and the influence of incident angle for the TE mode was also elucidated. These properties are expected to be used in practical applications such as communication device, sensing, and imaging.
Impact of EVFTA on Trade Flows of Fruits between Vietnam and the EU
Duc Trong TRAN,Van Thu BUI,Ngoc Minh VU,Tung Son PHAM,Hue Minh TRUONG,Thuy Thu DANG,Tu Van TRINH 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.5
The European Union Vietnam Free Trade Agreement (EVFTA) took effect on August 1 paving the way for increased trade between the EU and Vietnam; this marked a huge turning point for the Vietnamese economy. Agriculture products, especially fruits, must be listed when it comes to Vietnam export industries that profit the most from EVFTA. After a period of study, with the desire to contribute to the improvement in the efficiency of Vietnam’s agricultural products to the EU, the researchers want to assess the impact of the EVFTA on the flows of Vietnamese fruits to the EU market. The study uses a quantitative analysis method via the WITS-SMART model with data on export turnover and tariff reductions in parallel with the analysis of changes in factors affecting the trade flows of fruits between the two markets when the EVFTA takes effect. As a result, Vietnam’s fruit importing from the EU is expected to escalate by 29.18% in 2021, while the flow of export will only inch up by 0.955%, which is rather low compare to the increase in import value. Hence, effective policies must be introduced in Vietnam to innovate production methods and increase product quality, so that the EVFTA can be used to boost Vietnam’s fruit exports to the EU.
Nguyen Van Dung,유영준,이영백,Nguyen Thanh Tung,Bui Son Tung,Vu Dinh Lam 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.1
The influence of lattice constants on the electromagnetic behavior of a cut-wire-pair (CWP)structure has been elucidated. In this report, we performed both simulations and experiments todetermine the influence of polarization on the metamagnetic resonance of the CWP structure. Thekey finding is the result of an investigation on the plasmon hybridization between the two CWs,which showed that the polarization of the incident wave was affected. Good agreement betweennumerical simulation and measurement is achieved.
Ultra-broadband and flexible metamaterial absorber based on MoS2 cuboids with Mie resonances
Ha Duong Thi,Nam Man Hoai,Tung Bui Son,Khuyen Bui Xuan,Lam Vu Dinh,Le-Van Quynh 한국물리학회 2023 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.82 No.11
In this work, we present a type of fexible and broadband metamaterial absorber operating in the GHz range. The proposed structure consists of three layers: a periodic square-shaped array made of molybdenum disulfde (MoS2) on the top, a continuous polyimide layer in the middle and a continuous copper layer at the bottom. For fat model, the proposed absorber exhibits a broadband absorption in the frequency range of 10.1–17.6 GHz with an absorption of more than 90% under normal incidence. Due to the symmetry of structure, the absorption feature is polarization-insensitive. The absorption remains above 80% in the frequency range of 11.1–15.6 GHz when the incident angle is up to 60° for TE-polarized wave, while the absorption is higher than 90% in the frequency range of 13.5–18 GHz for incident angles up to 60° for TM-polarized wave. For bending model, the absorption is signifcantly expanded when the bending radius decreases to under 100 mm. The physical mechanism of the absorption properties is explained in detail by the electric feld distribution, the magnetic feld distribution following the Mie resonance theory and infuence of the loss of MoS2. Obtained results in the work might contribute to the development of potential applications based on metamaterials in the microwave region such as imaging, protecting and light emitting devices.