REALIZATION OF BROADBAND AND INDEPENDENT POLARIZATION METAMATERIAL PERFECT ABSORBER BASED ON THE THIRD-ORDER RESONANCE

In this report, we studied numerically and experimentally the electromagnetic properties of perfect MAs using ring-shaped structures at microwave frequencies. By creating a magnetic resonance, the ring structure confines electromagnetic energy at the first- and third-order resonances. And then, we leveraged the super-cell structures, which consist of different rings in one unit cell to obtain broadband absorption. The results showed that the absorption band of MA is broaden from 1.3 to 2.17 GHz when the number of rings in the unit cell increases from four to nine-ring

The application of electro coagulation process for decolorization of reactive dyeing wastewater

In this study, the application of bipolar electro coagulation (EC) using iron electrode has been assessed for the removal of Remazol Black B in the simulated dye wastewater. The influence of different parameters involving pH, initial dye concentration, sodium sulfate concentration, electrolysis time, and electric current was investigated. According to the results, the anode dissolution rate can be significantly affected by the electric current and it can be found that at high sulfate concentration, the decolorization process cannot be improved. The best color removal efficiency was obtained was 98.8 ± 0.9% at pH of 10, dye concentration of 30 mg/L, and electrical current of 6 A during electrolysis time of 8 minutes. This result indicates that EC can be used as an efficient and “green” method for color removal from reactive dye solution

Isolation an agar degradation Bacillus sp. AT6 and preliminary application for seaweed saccharification

Background: Agar is a common polysaccharide found in nature. However, agar is strongly resisted to the degradation processing, leading to limitation of its application in various areas. Thus, finding an effective solution for agar saccharification significantly improves the economically effects of agar based substrates.Methods: Soil samples were collected from TienPhong Forestry Ltd. Company, ThuyXuan District, ThuaThien Hue province, Vietnam. Potential agar degrading bacteria were screened on a mineral salt agar medium. The isolate was identified based on 16S rRNA nucleotide sequence, morphological, physiological, and biochemical characteristics. Agarase production was evaluated by modification culture conditions including incubation time, shaking speed, and initial inoculum size. Molecular mass of extracellular agarase was determined by native SDS-PAGE. The effect of pH, temperature, metal ions, and organic solvents were conducted for enzyme characterization. Application of enzyme was investigated on seaweed saccharification.Result: An agar degrading bacterial strain was isolated from soils and identified as Bacillus sp. AT6. Maximal agarase accumulation obtained in the culture containing an inoculum size of 10% (v/v), shaking speed of 210 rpm, and 96 hours incubation. The agarase revealed a single band on zymogram analysis with an apparent molecular weight of 180 kDa. The optimal temperature and pH were 40°C and pH 8.0, respectively. All tested metal ions and organic solvents partially decreased enzyme activity. Treatment seaweed by agarase resulted in reducing sugars release present in the reaction, indicating the saccharification of seaweed was succeeded.Conclusion: Bacillus sp. AT6 is a new report of agarolytic bacteria that produces extracellular agarase enzymes. The present results promise strain AT6 is a great candidate for agar saccharification for industrial application

All-dielectric Metamaterial for Electromagnetically-induced Transparency in Optical Region

Metamaterial (MM) is emerging as a promising approach to manipulate electromagnetic waves, spanning from radio frequency to the optical region. In this paper, we employ an effect called electromagnetically-induced transparency (EIT) in all-dielectric MM structures to create a narrow transparent window in opaque broadband of the optical region (580-670 nm). Using dielectric materials instead of metals can mitigate the large non-radiative ohmic loss on the metal surface. The unit-cell of MM consists of Silicon (Si) bars on Silicon dioxide (SiO$_{2}$) substrate, in which two bars are directed horizontally and one bar is directed vertically. By changing the relative position and dimension of the Si bars, the EIT effect could be achieved. The optical properties of the proposed MM are investigated numerically using the finite difference method with commercial software Computer Simulation Technology (CST). Then, characteristic parameters of MM exhibiting EIT effect (EIT-MM), including Q-factor, group delay, are calculated to evaluate the applicability of EIT-MM to sensing and light confinement

HORIZONTALLY PLASMON HYBRIDIZATION ON SYMMETRIC-BREAKING METAMATERIALS

In this report, we present a study on the fundamental negative-permeability metamaterials, named as the cut-wire-pair structure. The physics of the cut-wire-pair metamaterial is interpreted using the electromagnetic analog of molecular-orbital theory. It is shown that a symmetric-breaking cut-wire-pair metamaterial is horizontally plasmon-hybridized, leading to an additional magnetic resonance beyond the conventional one. The transmission spectra and the induced energy distributions are performed to demonstrate our prediction

Potential of a deep eutectic solvent in silver nanoparticle fabrication for antibiotic residue detection

Deep eutectic solvents (DESs) have recently emerged as an alternative solvent for nanoparticle synthesis. There have been numerous advancements in the fabrication of silver nanoparticles (Ag NPs), but the potential of DESs in Ag NP synthesis was neither considered nor studied carefully. In this study, we present a novel strategy to fabricate Ag NPs in a DES (Ag NPs-DES). The DES composed of ᴅ-glucose, urea, and glycerol does not contain any anions to precipitate with Ag+ cations. Our Ag NPs-DES sample is used in a surface-enhanced Raman scattering (SERS) sensor. The two analytes for SERS quantitation are nitrofurantoin (NFT) and sulfadiazine (SDZ) whose residues can be traced down to 10−8 M. The highest enhancement factors (EFs) are competitive at 6.29 × 107 and 1.69 × 107 for NFT and SDZ, respectively. Besides, the linearity coefficients are extremely close to 1 in the range of 10−8 to 10−3 M of concentration, and the SERS substrate shows remarkable uniformity along with great selectivity. This powerful SERS performance indicates that DESs have tremendous potential in the synthesis of nanomaterials for biosensor substrate construction

Flexible Magnetic Metasurface with Defect Cavity for Wireless Power Transfer System

In this paper, we present a flexible magnetic metamaterial structure for enhancing the efficiency of wireless power transfer (WPT) systems operating at 13.56 MHz. The metasurface between transmitter (Tx) and receiver (Rx) coils of the WPT system is constructed of a 3 × 5 metamaterial unit cell array with a total size of 150 × 300 mm2. Most metamaterial structures integrated into WPT systems are in planar configurations with a rigid substrate, which limits practical applications. The proposed metasurface is fabricated on an FR-4 substrate with a thin thickness of 0.2 mm; therefore, it can be bent with radii greater than 80 mm. A defect cavity is formed in the non-homogeneous metasurface by controlling the resonant frequency of the unit cell with an external capacitor. Simulation and measurement results show that the efficiency of the WPT system is significantly enhanced with metasurfaces. The performance of the WPT system can also be optimized with suitable bend profiles of metasurfaces. This proposed flexible metasurface could be widely applied to WPT systems, especially asymmetric, bendable, or wearable WPT systems

Dual-Band, Polarization-Insensitive, Ultrathin and Flexible Metamaterial Absorber Based on High-Order Magnetic Resonance

We demonstrate a dual-band, polarization-insensitive, ultrathin and flexible metamaterial absorber (MA), based on high-order magnetic resonance. By exploiting a flexible polyimide substrate, the thickness of MA came to be 1/148 of the working wavelength. The absorption performance of the proposed structure was investigated for both planar and bending models. In the case of the planar model, a single peak was achieved at a frequency of 4.3 GHz, with an absorption of 98%. Furthermore, additional high-order absorption peaks were obtained by the bending structure on a cylindrical surface, while the fundamental peak with a high absorption was maintained well. Our work might be useful for the realization and the development of future devices, such as emitters, detectors, sensors, and energy converters