Influence of chlorinated disinfection by-products on transmission of antibiotic resistance genes in biofilms and water of a simulated drinking water distribution system

Minglu Zhang,Lingyue Zhang,Kaizong Lin,Yue Wang,Shaofeng Xu,Miao Bai,Hairong Jiang,Shuangling Wang,Yongjing Wang,Can Zhang 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.4

The spread of antibiotic resistance genes (ARGs) caused by biofilm growth in drinking water distribution systems (DWDSs) poses a serious threat to human health. The influence of disinfection by-products (DBPs) on the distribution of ARGs and mobile genetic elements (MGEs) in different phases (biofilms and water) of DWDSs is unclear. In this study, the characteristics of microbial indices, trihalomethanes (THMs), haloacetic acids (HAAs), ARGs and MGEs in biofilms and effluents of simulated DWDS reactors were detected during 150 d of operation. During the mature biofilm periods of 90 d or 120 d, for both biofilms and effluents, seven categories of ARGs (except tetracycline) and MGEs were at their highest and lowest relative abundance in the entire operation cycle, respectively. The influence of DBPs on ARGs and MGEs in the DWDS was different in different phases. In effluents, DBPs showed a stronger relationship with ARGs compared with MGEs. THMs and HAAs had positive correlations with various ARGs, which indicated that DBPs affected the distribution of resistance genes. In biofilms, the influence of MGEs on ARGs was stronger than that of DBPs on ARGs. Thus, DBPs might be an important contributor to the enrichment and spread of ARGs in water.

Study on Interleaved Three-Switch Buck-Boost Converters with Co-directional Coupling Inductor

Zhang Xianjin,Ma Wenjing,Zhu Hairong,Wu Di,Bi Shubo 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1

In order to obtain soft switching and simplify the controlling circuit of an interleaved two-switch Buck-Boost converter, two types of three-switch interleaved Buck-Boost converters are proposed in this paper. Firstly, this paper analyses the coupling process of the presented converters under a large coupling coefcient. Then, the operating principle of the two converters is given in detail. And it is concluded that the expended duty cycle and soft switching of most of power devices can be obtained and a sharing-current circuit is also not needed. This will deeply simplify the controlling circuit. Finally, the simulation and experimental results verify the analysis.

Study on Half-Bridge Voltage Balancing Circuit with Two Driving Methods

Zhang Xianjin,Zhu Hairong,Wu Di,Li Rui 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.3

A voltage balancing circuit not only can split a two-wire dc grid into a three-wire dc grid, but also can balance the voltages of series capacitors or battery packs. A half-bridge voltage balancing circuit is a simpler topology and is widely introduced. But it has not been deeply analysed. Thus, in this paper the balancing circuit with the complementary driving method is studied in detail, fi rstly. Secondly, for avoiding the reactive current occurred in the complementary driving method, the unipolar current driving method is also proposed. Finally, the prototype is implemented in the lab, and the simulation and experimental results verify the analyses.

SIMULTANEOUSLY CATALYTIC REMOVAL OF NOx AND SOOT ON RARE EARTH ELEMENT OXIDE LOADED WITH POTASSIUM AND TRANSITION NANOSIZED METAL OXIDES

ZHI JIANG,HAIRONG ZHANG,ZHONGPENG WANG,MINGXIA CHEN,WENFENG SHANGGUAN 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2008 NANO Vol.3 No.4

The simultaneous catalytic removal of NOx and soot over the rare earth element (REE) oxide-based mixture oxides loaded with potassium and transition nanosized metal oxide (designated as M/K/REE oxide) was investigated by using temperature-programmed reaction (TPR). The influence of the type of REE oxides together with the type and amount of transitional metal oxides on the catalytic removal activity was discussed. K/Nd2O3 was found to be the most active oxide among the REE oxides to simultaneous remove the NOx and soot under lean conditions. Chromium oxide was more active than the other transition metal oxides on enhancing the activity of soot oxidation of Nd2O3 loaded with potassium. The optimum loading level of chromium was about 10 wt%, with ignition temperature at about 237°C and the conversion ratio NO → N2 about 24.1%. The Mn-loading on K/Nd2O3 resulted in the biggest conversion efficiency of NO to N2 at about 30.2%. The increasing catalytic reaction of NOx–soot activities is attributed to the formation of complex crystalline phase in the catalyst together with the improving contacting between catalysts and soot.

The Inhibitory Effect of Ginseng Pectin on L-929 Cell Migration

Yuying Fan,Hairong Cheng,Dan Liu,Xu Zhang,Bo Wang,Lin Sun,Guihua Tai,Yifa Zhou 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.5

We tested the effects of ginseng pectin prepared by enzymatic hydrolysis of ginseng polysaccharides on cell migration. Ginseng pectin impaired the migration of L-929 cells and reduced their migration speed by up to 50% of control in the presence or absence of serum, suggesting it worked on both serum-dependent and serum-independent migration pathways. Ginseng pectin impaired cell migration via decreased cell spreading. These findings represent a significant contribution towards understanding the bioactivities of ginseng polysaccharides and applying them to health food and medicine.

A Novel Quality Evaluation Index and Strategies to Identify Scenting Quality of Jasmine Tea Based on Headspace Volatiles Analysis

Jie Lin,Ying Chen,Pan Zhang,Mingxing Ren,Hairong Xu,Xiaochang Wang 한국식품과학회 2013 Food Science and Biotechnology Vol.22 No.2

Jasmine tea is quite popular in daily consumption and beverage industry, and scenting quality and synthetic artificial oil are crucial issues of its quality control. The headspace volatile profiles of jasmine tea samples were analyzed by headspace-solid phase microextraction (HSSPME)coupled with GC-MS. Twenty-nine volatile compounds were determined as ‘common components’ that should exist in jasmine scented teas. Potential correlation was discovered between quality grade of jasmine tea and the ratio of peak area percentage of α-farnesene, (Z)-3-hexenyl benzoate, methyl anthranilate, and indole to that of linalool. This ratio was denoted as ‘jasmine tea flavor’ (JIF) index,a novel index for quality evaluation of jasmine tea. JTF index and common components could provide a good identification of well-scented, poor-scented, and not-scented jasmine teas. Moreover, carrier compounds might be a clear evidence for identifying fake jasmine teas that were added with synthetic fragrance oil.

Preparation and characterization of epoxidized microbial oil

Xinde Chen,Dan Yang,Lian Xiong,Bo Wang,Xuefang Chen,Can Wang,Hairong Zhang,Haijun Guo 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.3

The potential of microbial oil derived from yeasts through fermentation using crops biomass for the formation of plasticizers was investigated. Plasticizers were formed via epoxidation reaction. Five factors of the orthogonal experiment (reaction temperature, time, weight ratio of H2O2/MO, H2SO4/MO, and HCOOH/MO) have been used for optimization of parameters. To further enhance the iodine value of microbial oil and increase the epoxy value of the epoxide, an amount of soybean oil was added. The products were characterized by FTIR, 13C-NMR and 1H-NMR. Under the optimum condition, the epoxy value and the iodine value of epoxide product were 6.21% and 1.8 g I2/100 g with a yield of 91.86% at an oil conversion of 98.43%. This study successfully demonstrated the conversion of crops biomass into value-added chemicals using simple and conventional chemical reactions.

Current progress on gold recovery from refractory ore and waste electrical and electronic equipment

Ji Xuran,Shen Zhijie,Xu Wenping,Yao Shimiao,Zhang Hairong,Xiong Lian,Li Hailong,Guo Haijun,Chen Xuefang,Chen Xinde 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.9

The physical and chemical properties of gold promote its application, such as in the high-tech, electronic products, and aerospace industries. The easily leachable ore is gradually depleted. Thus, it becomes necessary to extract gold from other resources such as refractory ore and electrical and electronic equipment. The normal method of leaching for gold is cyanide leaching, but it is very dangerous for both environment and operator. Non-cyanide leaching methods, including thiourea leaching, halide leaching, and sulfate leaching have been developed to substitute cyanide leaching. A variety of methods to enrich gold from leaching solutions are described in this paper, including solvent extraction, electrowinning, activated carbon adsorption, and ion exchange resins. Among those methods, ion exchange resins can adsorb gold with high adsorption efficiency and regenerate easily as well. This paper focuses on the research progress of the recovery of gold from non-cyanide leachates by ion exchange resins, summarizes the existing resin types and elution processes, points out the limitations in the application of current ion exchange resins, and discusses possible solutions.

Mechanical and Microscopic Properties of Cement Stabilized Silt

Shaoyun Pu,Zhiduo Zhu,Weilong Song,Yu Wan,Hairong Wang,Shigong Song,Jun Zhang 대한토목학회 2020 KSCE Journal of Civil Engineering Vol.24 No.8

In order to explore the strength, water stability, compressibility, shear properties of cement stabilized silt, the one-dimensional consolidation tests, direct shear and unconfined compressiontests were conducted on cement solidified silt. In addition, the microscopic characteristics of cement stabilized silt were investigated by using scanning electron microscope (SEM) and X-ray diffraction (XRD) tests. The unconfined compression tests showed that the unconfined compressive strength (UCS) raised with cement dosage increasing, and first increased rapidly and then raised slowly with the prolongation of curing time. As curing time prolonged, the water stability coefficient (Kr) of 2% cement stabilized silt raised significantly, while the Kr of 4% and 6% cement stabilized silt almost hardly changed. As cement dosage increased, at 7 days of curing age, the compressive modulus of cement stabilized silt raised. However, at 28 and 90 days of curing, the compressive modulus first raised and then reduced. As curing time increased, the compressive modulus increased at first and then deceased slightly. The direct shear tests demonstrated that the internal friction angle of cement solidified silt was almost unchanged with increasing cement dosage, but the internal friction angle increased slightly with the prolongation of curing time. For 2% and 4% cement stabilized silt, the cohesion raised with the prolongation of curing time. Meanwhile, the cohesion of 6% cement solidified silt at 7 days was slightly larger that of 28 days. Besides, the SEM and XRD analysis indicated that the loose structure of silt was improved due to cement addition.