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.

The Hedonic Method in Evaluating Apartment Price: A Case of Ho Chi Minh City, Vietnam

NGUYEN, Ha Minh,PHAN, Hung Quoc,TRAN, Tri Van,TRAN, Thang Kiem Viet Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.6

The study examines factors affecting apartment prices in the real estate market of Ho Chi Minh City, Vietnam. The study uses primary data based on surveys of customers who have traded successfully, and collects transaction data from real estate trading companies that are the top investors in Ho Chi Minh City real estate market. The collected data include 384 observations in a total of 24 districts, detailing that each district surveyed on a minimum of four projects, each project carried out a survey on a minimum of four apartments. The survey collected 339 valid questionnaires for analysis and model testing. This study employs multivariate regression with the data of 339 observations. The research results reveal that five significant factors affect positively the price of apartments in Ho Chi Minh City - apartment area, toilet and bedroom, apartment floor, reference price, and apartment interior. Besides, there are three significant factors affecting negatively the price of apartments - next price trend, distance to city center, and potential building. From the results, the research proposes solutions in the pricing of apartments in the real estate market in Ho Chi Minh City - better information system, a real estate transaction index, and stricter management of small brokerage activities.

Fiscal Decentralization, Corruption, and Income Inequality: Evidence from Vietnam

Hung Thanh NGUYEN,Thuy Hoang Ngoc VO,Duc Doan Minh LE,Vu Thanh NGUYEN 한국유통과학회 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.11

The objective of this research paper is to study the simultaneous relationship between fiscal decentralization, corruption, and income inequality among Vietnamese provinces. We use a balanced panel data set of 63 provinces/cities in Vietnam in the period from 2011 to 2018. The study used 3SLS-GMM (Three Stage Least Squares - Generalized Method of Moments estimator) and GMM-HAC (Generalized Method of Moments - Heteroskedastic and Autocorrelation Consistent estimator). Empirical evidence shows a strong simultaneous relationship: increased corruption will increase regional income disparities, income inequality, and increase fiscal decentralization. In addition, the results also suggest that an increase in per-capita income will reduce the level of corruption, or better control corruption of each province. The degree of increase in income inequality, which reduces fiscal decentralization, is the same for trade liberalization. All demonstrate that there is a simultaneous relationship between fiscal decentralization, corruption, and income inequality. In a region of high public governance quality, fiscal decentralization positively effects its economic growth. This issue will indirectly increase income inequality between provinces within a country. Our findings imply that a country’s fiscal decentralization strategy should be linked to improving corruption control and local governance effectiveness, indirectly improving income inequality between localities or regions.

Triterpenoid saponins from the roots of Rosa rugosa Thunb. as rat intestinal sucrase inhibitors

Nguyen Phuong Thao,Bui Thi Thuy Luyen,주성호,Tran Manh Hung,Nguyen Xuan Cuong,Nguyen Hoai Nam,권영인,Chau Van Minh,김영호 대한약학회 2014 Archives of Pharmacal Research Vol.37 No.10

Medicinal plants constitute an important sourceof potential therapeutic agents for diabetes. The purpose ofpresent study is to investigate the effect of root extract ofRosa rugosa Thunb. on inhibition of sucrase related todiabetes mellitus (DM). Bioassay-guided fractionation ofthe methanol extract led to the identification of 13 triterpenoidsaponins (1–13). Their structures were elucidatedon the basis of extensive spectroscopic analysis, including1D, 2D NMR, and MS. The n-butanol fraction showedpotent rat intestinal sucrase inhibitory activity with value of87.62 ± 5.84 % inhibition compared to the positive controlacarbose (50.96 ± 2.97 % inhibition at 0.02 mM). Subsequently, compounds 11–13 (1.0 mM) exhibited significantsucrase inhibitory activity, with inhibition percentagevalues of 41.17 ± 3.52, 46.80 ± 4.00, and39.39 ± 4.19 %, respectively. Whereas, compounds 2–6,8, and 10 showed moderate sucrase inhibitory activity(ranging from 13.26 ± 7.00 to 32.08 ± 6.04 % inhibition)at a same concentration. The data provide a starting pointfor creating new sucrase inhibitors, which may be usefulfor the development of effective therapies for the treatmentof DM.

Formulation optimization of orally disintegrating tablets containing solid dispersion of felodipine and hydroxypropyl methylcellulose using face-centered central composite design

Nguyen-Thach Tung,Man-Van Hung,Xuan-Minh Vo,Thanh-Hai Nguyen,Thi-Minh-Hue Pham 한국약제학회 2014 Journal of Pharmaceutical Investigation Vol.44 No.2

A novel dosage form integrating solid dispersion(SD) in orally disintegrating tablets (ODTs) wasdeveloped and optimized by the face-centered centralcomposite design to improve poorly soluble property andslow onset action time of felodipine (Fel). SD of Fel andhydroxypropyl methylcellulose E6 was prepared by solventevaporation method. Differential scanning calorimetry andfourier transforms infrared spectroscopy indicated that Feltransformed from crystalline to amorphous state by theformation of hydrogen bond between –N–H in Fel and O–Rin HPMC. The accelerated stability test in 45 C, 75 % RHdemonstrated that the optimized SD was stable in terms ofthe dissolution rate of Fel and thermodynamic property. The ODTs containing SD (Fel:HPMC E6 = 1:3) wereprepared by direct compression technique. The face-centeredcentral composite design with the ODT-SD wasemployed to investigate the effect of mannitol (X1),crospovidone XL (X2) on the ODT-SD disintegration time(Y1), % Fel released after 5 min (Y2) and the ODT-SDfriability (Y3). ANOVA test showed that X2 and X2 * X2had a significant effect on the ODT-SD disintegration time(p\0.05). Meanwhile, the dissolution rate of Fel after5 min did not remarkably depend on any independentvariables (p[0.05). The ODT-SD friability was substantiallyproportional to the amount of mannitol (X1)(p\0.05). The optimized ODT-SD disintegration time, %Fel released after 5 min, and friability were 27.67 s, 88.35and 0.48 %, respectively.

A Study on the Poverty of Mountain People Depending on Forests

NGUYEN, Phuong Thi Minh,NGUYEN, Song Van,DO, Duc Tai,NGUYEN, Quynh Thi Thuy,DINH, Thanh Trung,NGUYEN, Hang Phan Thu Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.7

Livelihood capitals have a clear influence on livelihood development. As for the livelihood results, it has been pointed out in the analysis of the poor households that the ability of people to escape poverty depends especially on the access to livelihood capitals. This study aims to analyze the impacts of livelihood capital on poverty among mountain people who depend on forests through human capital, social capital, natural capital, physical capital and financial capital. This research employs the model of binary regression function. Independent variables x1, x2, …, xn are targets of livelihood strategy, vulnerability context, and livelihood capitals. These variables were selected to be included in the original model with dependent variable Y as poor and non-poor households. This study surveys households living in upland areas, near forests, and households of ethnic minorities. The results show that,out of the poor household rate, nearly 4% are newly-poor households or those falling back into poverty. Therefore, the government needs to pay more attention to this disadvantaged group and implements policies such as education and training policies, credit support policies, policies to support forest development, and payment for forest environmental services in the context of emerging countries like Vietnam.

A New Battery Approach to Wind Generation System in Frequency Control Market

Nguyen, Minh Y.,Nguyen, Dinh Hung,Yoon, Yong Tae The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.4

Wind power producers face many regulation costs in deregulated environment, which remarkably lowers the value of wind power in comparison with conventional sources. One of these costs is associated with the real-time variation of power output and being paid in frequency control market according to the variation band. This paper presents a new approach to coordination of battery energy storage in wind generation system for reducing the payment in frequency control market. The approach depends on the statistic data of wind generation and the prediction of frequency control market price to determine the optimal variation band which is then kept by the real-time charging and discharging of batteries, ultimately the minimum cost of frequency regulation can be obtained. The optimization problem is formulated as trade-off between the decrease in the regulation payment and the increase in the cost of using battery, and vice versus. The approach is applied to a study case and the results of simulation show its effectiveness.

Highly effective adsorption of organic dyes from aqueous solutions on longan seed-derived activated carbon

Nguyen Van Hung,Bui Thi Minh Nguyet,Nguyen Huu Nghi,Nguyen Mau Thanh,Nguyen Duc Vu Quyen,Vo Thang Nguyen,Dao Ngoc Nhiem,Dinh Quang Khieu 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.3

In this study, longan seeds - an agricultural by-product was used to fabricate activated carbon (LSAC) through two-step pyrolysis with pre-carbonization at low temperature in the first step and then activation by H3PO4. LSAC with large surface area and porous structure exhibits an excellent capacity of absorption towards both cationic dyes (methylene blue (MB), rhodamine-B (RhB)) and anionic dyes (methyl orange (MO), congo red (CR)). Experimental data can be described well by the pseudo-second kinetic model. The maximum adsorption capacity based on Langmuir isotherm model was found as 502.84; 397.77; 464.66 and 350.64 mg.g−1 for MB, RhB, MO and CR, respectively. The adsorption of MB, RhB and CR on LSAC is spontaneous and endothermic, while that for MO is spontaneous but exothermic. Furthermore, the adsorption mechanism of dyes on LSAC was also studied showing that it can occur by electrostatic interaction, hydrogen bonding, the filling of pores involving the interaction between dye ions with specific functional groups such as –OH, –COOH, –NH2 and –PO43− on the LSAC surface. These results suggest that LSAC material may be envisaged as a promising adsorbent for treatment of wastewater in textile industries.

A New Approach for Corrective and Preventive Control to Unsolvable Case in Power Networks having DERs

Hung Nguyen Dinh,Minh Y Nguyen 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.3

Recently, Korean system operating conditions have gradually approached an upper limit. When a contingency occurs, the power system may have no solutions. Different from the cases of bad initial guesses or the solutions are too close to the solvability boundary in which numerical methods can be applied, for unsolvable cases, the only way to restore solvability would be structure modifications. In this paper, a new approach for corrective and preventive control to such cases is proposed in two steps: (i) finding any solution regardless its feasibility; (ii) for the infeasible solution, make it feasible with additional modifications at load buses having Distributed Energy Resources. The test case built based on the peak load profile of 2008 by KEPCO including 1336 buses is analyzed. Since reactive power compensation is optimized to restore solvability, all demands are met, therefore no blackouts happen. The proposed method was integrated in the LP program designed by power21 Corporation.

Lanostane Triterpenoids from Ganoderma tropicum Collected in Vietnam and Their Nitroblue Tetrazolium Reductive Activity In Vitro

Nguyen Thi Duyen,Nguyen Minh Khoi,Phan Nguyen Truong Thang,Duong Minh Tan,Tran Viet Hung,Do Thi Ha 한국생약학회 2020 Natural Product Sciences Vol.26 No.4

A new compound, 3β-acetoxylanosta-7,9(11),24-triene-26-al (3), and seven known compounds (1 – 2 and 4 – 8) were isolated from Ganoderma tropicum (Jung.) Bres. collected in Tay Nguyen, Vietnam. The structures of these compounds were determined by one- and two-dimensional nuclear magnetic resonance spectroscopy, electrospray ionization mass spectrometry (ESI-MS), and high-resolution ESI-MS, and by comparison with literature data. All of the isolated compounds were tested for nitroblue tetrazolium (NBT) reduction activity in Saccharomyces cerevisiae-stimulated RAW 246.7 cells. Among them, compounds 2 – 4 and 6 – 8 enhanced the NBT reduction in a dose-dependent manner.