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.

Improved object recognition performance of UWB radar according to different window functions

Trung Kien Nguyen,홍익표 한국전기전자학회 2019 전기전자학회논문지 Vol.23 No.2

In this paper, we implemented an Ultra-Wideband radar system using Stripmap Synthetic Apertrure Radar algorithm torecognize objects inside a box. Different window functions such as Hanning, Hamming, Kaiser, and Taylor functions toimprove image recognition performance are applied and implemented to radar system. The Ultra-Wideband radar system with3.1~4.8 GHz broadband and UWB antenna were implemented to recognize the conductor plate located inside 1m3 box. Toobtain the image, we use the propagation data in the time domain according to the 1m movement distance and use the RangeDoppler algorithm. The effect of different window functions to improve the recognition performance of the image areanalyzed. From the compared results, we confirmed that the Kaiser window function can obtain a relatively good image.

Improved object recognition performance of UWB radar according to different window functions

Nguyen, Trung Kien,Hong, Ic-Pyo Institute of Korean Electrical and Electronics Eng 2019 전기전자학회논문지 Vol.23 No.2

In this paper, we implemented an Ultra-Wideband radar system using Stripmap Synthetic Apertrure Radar algorithm to recognize objects inside a box. Different window functions such as Hanning, Hamming, Kaiser, and Taylor functions to improve image recognition performance are applied and implemented to radar system. The Ultra-Wideband radar system with 3.1~4.8 GHz broadband and UWB antenna were implemented to recognize the conductor plate located inside 1m3 box. To obtain the image, we use the propagation data in the time domain according to the 1m movement distance and use the Range Doppler algorithm. The effect of different window functions to improve the recognition performance of the image are analyzed. From the compared results, we confirmed that the Kaiser window function can obtain a relatively good image.

Design challenges for 13.56MHz 10 kW resonant inverter for wireless power transfer systems

Nguyen Kien Trung,Kan Akatsu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper presents the design process of a 13.56 MHz 10 kW and high efficiency inverter for wireless power transfer systems. The main challenges that are the effect of the parasitic components, the using of the high-speed switching devices and the inverter topology are discussed. Finally, an optimal design of 10kW inverter using E-mode GaN is shown with the efficiency of over 95%.

Acetylcholinesterase, inflammation, and diabetic inhibitory activities of Lentinus giganteus

Trung Kien Nguyen,Do Bin Shin,Jae Hyuk Choi,Kyung Hoan Im,Min Woong Lee,Pyung Gyun Shin,Tae Soo Lee 한국버섯학회 2014 버섯 Vol.18 No.1

Lentinus giganteus is a edible mushroom cultivated in Asian countries. The present study was initiated to evaluate the anti-inflammatory, anti-acetylcholinesterase, anti-α-glucosidase, and free radical scavenging activities from fruiting bodies of L. giganteus extracted with methanol and hot water. The free radical scavenging activities of methanol and hot water extracts on 1,1-diphenyl-2-picrylhydrazyl (DPPH) were 92.26% and 90.17% at 2.0 mg/mL concentration, respectively and comparable with positive control, BHT. The chelating activities of methanol and hot water extracts were significantly higher than the positive control tested. The reducing power of methanol and hot water extracts showed lower activities compared to positive control, BHT. The phenolic and flavonoid contents of hot water extract were 1.56 μg/mg and 24.35 μg/mg, respectively. Nitric oxide (NO) produced by lipopolysaccahride (LPS) activated RAW 264.7 cells were significantly inhibited by treatment of methanol and hot water extracts. The methanol extract inhibited the acetylcholinesterase (AChE) activity by 91.19% at the 2.0 mg/mL concentration, whereas galanthamine, the standard drug, inhibited the AChE activity by 97.80%. The hot water extracts inhibited the α-amylase and α-glucosidase activities by 78.86% and 80.78%, respectively at the 2.0 mg/mL concentration, while acarbose, the positive control, inhibited the activities by 89.91% and 81.81%, respectively at the same concentration. Therefore, it is concluded that fruiting bodies of L. giganteus contain antioxidant, anti-inflammatory, anti-cholinesterase, and anti-diabetic substances, which can be used for natural health food for promoting human health.

Low-Power Direct Conversion Transceiver for 915 MHz Band IEEE 802.15.4b Standard Based on 0.18 μm CMOS Technology

Trung-Kien Nguyen,Viet-Hoang Le,Quoc-Hoang Duong,Seok-Kyun Han,Sang-Gug Lee,Nak-Seon Seong,Nae-Soo Kim,Cheol-Sig Pyo 한국전자통신연구원 2008 ETRI Journal Vol.30 No.1

This paper presents the experimental results of a lowpower low-cost RF transceiver for the 915 MHz band IEEE 802.15.4b standard. Low power and low cost are achieved by optimizing the transceiver architecture and circuit design techniques. The proposed transceiver shares the analog baseband section for both receive and transmit modes to reduce the silicon area. The RF transceiver consumes 11.2 mA in receive mode and 22.5 mA in transmit mode under a supply voltage of 1.8 V, in which 5 mA of quadrature voltage controlled oscillator is included. The proposed transceiver is implemented in a 0.18 μm CMOS process and occupies 10 mm2 of silicon area.

Wage Differentials among Ownership Groups and Worker Quality in Vietnamese Manufacturing

Kien Trung Nguyen,Eric D. Ramstetter 연세대학교 동서문제연구원 2017 Global economic review Vol.46 No.3

Wholly foreign multinational enterprises (WFs), joint-venture multinationals (JVs), state-owned enterprises (SOEs) pay higher wages than domestic private firms in Vietnamese manufacturing. In large samples of medium–large (20+ employees) firms, conditional differentials accounting for worker education and occupation, as well as capital intensity, size, and shares of female workers, were substantially smaller, but positive and significant. Wage levels and differentials varied substantially among industries. Conditional differentials remained positive and significant for WFs and JVs in most of the 11 industries examined, but estimates of SOE-private differentials were insignificant in most industries. Robustness checks using 2007 data yielded similar results.

Anti-cholinesterase, Skin Anti-wrinkle and Melanogenesis Inhibitory Activities of Fruiting body Extracts from Dictyophora indusiata - Queen of the Mushroom

Trung Kien Nguyen,Min Woong Lee,Jae Hyuk Choi,Kyung Hoan Im,Tae Soo Lee 한국버섯학회 2014 버섯 Vol.18 No.2

Dictyophora indusiata (Vent.) Desv., “Queen of the mushroom”, is a mushroom in family Phallaceae of Basidiomycota, which is commonly used as edible and medicinal mushroom in China and Korea. This study initiated to evaluate the anti-cholinesterase, skin anti-wrinkle and melanogenesis inhibitory of 80% methanol extract from fruiting body of D.indusiata. In the anti-cholinesterase experiment, acetyl-cholinesterase and butyryl-cholinesterase inhibitory activities were performed. The extract were inhibited acetyl-cholinesterase and butyryl-cholinesterase 44.09% and 49.14% at the concentration 1 mg/mL, respectively. The skin anti-wrinkle effect of the extract were determined by measuring anti-collagenase and anti-elastase activities. While melanogenesis inhibitory activities were performed by tyrosinase, DOPA inhibitory and melanin synthesis inhibitory activities. The tyrosinase inhibitory activity of the extract were from 37.60~68.96%, while DOPA inhibitory activity were from 15.43 ~ 29.58% at the concentration ranged from 0.125~2.0 mg/mL. In addition, cellular tyrosinase activity was tested with result of the enzyme activity reduced from 99.09% to 72.91% against 25~500 μg/mL of the extract. The methanol extract of D.indusiata was inhibited melanin synthesis activity 41.86% at the concentration 500 μg/mL. The collagenase inhibitory activity of the extract from D.indusiata were 34.87%, which was comparable with the positive control, EGCG ( 45.31%). While the extract showed good inhibition of elastase enzyme (46.64%). The experiment results suggested that fruiting body of Dictyophora indusiata could be used as natural anti-cholinesterase and skin care agents.

Free Radical Scavenging, Anti-cholinesterase, Anti-inflammation, and α-Glucosidase Inhibitory Effects of Russula compacta Fruiting bodies

Trung Kien Nguyen,Do Bin Shin,Jae Hyuk Choi,Kyung Hoan Im,Mi Ja Shim,Min Woong Lee,Tae Soo Lee 한국버섯학회 2014 버섯 Vol.18 No.1

Russula compacta, a wild mushroom, belongs to Russulaceae, Russulales of Basidiomycota. This study was conducted to evaluate the free radical scavenging, anti-inflammatory, anticholinesterase and anti-α-glucosidase effects from fruiting bodies of R. compacta extracted with methanol and hot water. In 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging effects, the methanol and hot water extracts showed good scavenging effects comparable with positive control, BHT. The chelating effect of methanol and hot water extracts of the mushroom were significantly higher than the positive control, BHT. The reducing power of the methanol and hot water extracts of the mushroom were lower than the positive control at the concentrations tested. In the HPLC anaysis of phenolic acids profile of the mushroom extract, 7 phenolic acids such as gallic acid, vanillin, rutin hydrate, resveratol, quercetin formononetin, and biochanin-A were detected. Nitric oxide (NO) production in lipopolysaccahride (LPS) activated RAW 264.7 cells was inhibited by 1.5-fold with the treatment of methanol extract when compared with the control. In the anti-cholinesterase activity assay, the methanol extract inhibited the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) effects by 73.9% and 81.05% at the 1.0 mg/mL concentration, whereas galanthamine, the standard drug, inhibited the AChE and BChE activities by 97.80% and 81.12%, respectively at the same concentration. The methanol and hot water extracts of the mushroom inhibited the α-glucosidase activity by 55.44% and 62.00%, respectively at the 2.0 mg/mL concentration, while acarbose, the positive control inhibited the α-glucosidase activity by 81.81% at the 2.0 mg/mL concentration. From the experimental results, the fruiting bodies of R. compacta contained natural antioxidant, anti-inflammatory, anti-cholinesterase, and anti-diabetic substances, which might be used for health foods.

PCB design for 13.56MHz half-bridge class D inverter for wireless power transfer system

Nguyen Kien Trung,Takuya Ogata,Shinichi Tanaka,Kan Akatsu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

At 13.56MHz, the inverter is strongly affected by parasitic elements. The print circuit board (PCB) design is very critical because it control the parasitic elements on the circuit. This paper analyzes the effect of parasitic elements on switching performance of MOSFETs in 13.56MHz class D inverter. This work also proposes an improved PCB design which can provide a 23.4% decrease in parasitic inductance comparing with conventional PCB design.