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%.

Application of Metaheuristic Optimization Algorithm and 3D Printing Technique in 3D Bandpass Frequency Selective Structure

Nguyen Trung Kien,홍익표 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.2

A 3D band pass frequency selective surface structure with desired center frequency and bandwidth, designed by multiobjective optimization algorithms, is introduced in this paper. The ant colony optimization technique is used to achieve optimal design properties with the required characteristics. The performance of the manufactured structure using the 3D printing method is measured to verify the optimized structure for normal incidence. Come up with the results, the convenience of the optimization algorithm accordingly 3D printing can help in designing and constructing complex 3D structures.

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.

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, Skin whitening and Anti-collagenase activities of Milky Mushroom – Calocybe indica

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

Calocybe indica (Purkayastha, 1974), Milky mushroom, is a relatively new to the world of mushroom industry, which is belong to Lyophyllaceae of Basidiomycota, and commonly used as edible mushroom in India and Southern Asia country. This study was conducted to investigate the free radical scavenging, skin whitening and anti-collagenase activities of methanol extract from fruiting body of C.indica cultivated in Bangladesh. In addition, the polyphenol compounds of the extract were analyzed by HPLC. The mushroom extract showed good activity in lipid peroxidation which ranged from 29.35% to 55.39% at the concentration 0.125~2.0 mg/mL. The scavenging activity of the extract on 1,1-diphenyl-2-picrylhydrazy radicals were from 20.22~83.93% at the same tested concentration, which were comparable with the positive control BHT. The hydroxyl radical scavenging activity of the extract was 76.24~93.92%. The skin whitening effect of the mushroom extract was performed with UV light protecting, tyrosinase and DOPA inhibitory activities. The methanol extract absorbed UV-B wavelength with maximum level of 0.356 at 280 nm. The tyrosinase and DOPA inhibitory activities of the extract were ranged from 30.36 ~ 66.25% and 7.13 ~ 30.25% at the concentration 0.125~2.0 mg/mL, respectively. Furthermore, anti-collagenase activity were determined by measuring collagenase and elastase inhibitory activity. The collagenase and elastase inhibitory activity of the extract were 42.77% and 51.08% at the concentration 1.0 mg/mL, respectively. The experiment results suggested that fruiting body of Calocybe indica could be used as natural skin care and antioxidant agents.

A low-power CMOS direct conversion receiver with 3-dB NF and 30-kHz flicker-noise corner for 915-MHz band IEEE 802.15.4 ZigBee standard

Nguyen, Trung-Kien,Oh, Nam-Jin,Le, Viet-Hoang,Lee, Sang-Gug IEEE 2006 IEEE transactions on microwave theory and techniqu Vol.54 No.2

A low-power low flicker-noise receiver front-end for 915-MHz-band IEEE 802.15.4 standard in 0.18-μm CMOS technology is implemented. A power-constrained simultaneous noise and input matching low-noise amplifier (LNA) can be achieved by using a conventional inductive degeneration cascode amplifier with an extra gate-source capacitor. In combination with the LNA, a passive mixer showing low 1/f noise performance is adopted to convert the RF signal directly to the baseband signal. The measured results show a conversion gain of 30 dB and a noise figure of 3 dB with 1/f noise corner frequency of 30 kHz. Two-tone test measurements indicate -5-dBm input third-order intercept point and +45-dBm input second-order intercept point. The RF receiver front-end dissipates 2 mA from a 1.8-V supply.