Multiple Tolerances and Dye Decolorization Ability of a Novel Laccase Identified from Staphylococcus Haemolyticus

Xingxing Li,Dongliang Liu,Zhaowei Wu,Dan Li,Yifei Cai,Yao Lu,Xin Zhao,Huping Xue 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.4

Laccases are multicopper oxidases with important industrial value. In the study, a novel laccase gene (mco) in a Staphylococcus haemolyticus isolate is identified and heterologously expressed in Escherichia coli. Mco shares less than 40% of amino acid sequence identities with the other characterized laccases, exhibiting the maximal activity at pH 4.0 and 60oC with 2,2'-azino-bis (3- ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) as a substrate. Additionally, the Mco is tolerant to a wide range of pH, heavy metal ions and many organic solvents, and it has a high decolorization capability toward textile dyes in the absence of redox mediators. The characteristics of the Mco make this laccase potentially useful for industrial applications such as textile finishing. Based on BLASTN results, mco is found to be widely distributed in both the bacterial genome and bacterial plasmids. Its potential role in oxidative defense ability of staphylococci may contribute to the bacterial colonization and survival.

Energy Absorption Characteristics of Crash Box of New Honeycomb Core Structure with Foam-Filled

Xiang Li,Yanmiao Wang,Xingxing Xu,Xiangbin Cao,Rui Li 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.1

By combining honeycomb core with the traditional crash box, an innovative foam-filled honeycomb core structure crash box is proposed to improve safety performances. Three kinds of honeycomb core crash boxes were obtained by filling the inside of the traditional crash box with the quasi-honeycomb core, the quasi-square honeycomb core and hexagonal honeycomb core. It is deduced that the energy absorption of the quasi-honeycomb core crash box increased by 42.2 %, the peak of the collision force reduced by 8.9 %. The hexagonal honeycomb core crash box and the quasi-square honeycomb core crash box also enhance the energy absorption characteristics, but the peak impact force increased by 5.6 % and 9.6 %. After filling of the Expanded Polypropylene (EPP) foam, the peak collision force of the EPP hexagonal honeycomb core crash box and the EPP quasi-square honeycomb core crash box increased by 10 %, while Fmax of the EPP quasi-honeycomb core crash box reduced by 2.3 % and the energy absorption increased by 54.6 %. Six structures were compared to highlight the energy absorption characteristics of the filling the inside of the traditional crash box with the light in weight honeycomb core and EPP foam. The research results provide a new idea for the design of crash box.

Effect of High-energy Ball Milling on the Mg Alloy Powders under Alcohol Protection

Li Gang,Liu Xingxing,Guo Qi,Tang Jianren,Yan Biao 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1

Study about the feasibility and effect of high-energy ball milling on a specific Mg alloy under protection medium of alcohol was presented via comparing with conventional vacuum milling. More fine particles with wider powder size distribution but more irregular shape were shown of the powder milled under alcohol. No obvious oxide was revealed from the two kinds of Mg alloy powders with limited milling time. And since slip induced in a preferential direction, the (002) texture was formed in the Mg alloy powders at the initial stage of alcohol milling. More O and Fe contaminants were introduced into the powders milled under alcohol according to the EDS analysis.

Ordered porous TiO2 films obtained by freezing and the application in dye sensitized solar cells

Xingxing Wang,Bingchu Yang,Kechao Zhou,Dou Zhang,Zhiyou Li,Conghua Zhou 한국물리학회 2015 Current Applied Physics Vol.15 No.5

TiO2 films with ordered porous structure were prepared by freezing. By simply freezing wet TiO2 film on a cold copper plate, ice crystals could grow from bottom of film. Removing such ice crystals then led to ordered, micro-sized pores in the films. With assistance of scanning electron microscopy and N2 adsorptionedesorption isotherms, micro-structural properties of the films were studied. Coarsening behavior of ice crystals was analyzed based on evolvement of the micro-structure. It was found that, both larger film thickness and longer freezing time were beneficial for the formation of ordered porous structure, which was caused by enhanced ice crystals growth. The films were then used to fabricate photoanode of dye sensitized solar cells, of which the photo-to-electric power conversion efficiency was evaluated. It was observed that, solar cell made of ordered porous TiO2 film came out with 13% larger photo-current density comparing to that made of conventional doctor blading method, which is due to the enhanced light scattering by the ordered porous structure.

Chitosan assisted synthesis of LiFePO4/Graphene/C composite and its electrochemical performance

Qiru Li, Zhufa Zhou,Xingxing Zhang,ShanShan Liu 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.5

LiFePO4/graphene/C composite was prepared using chitosan (CS) and graphene oxide (GO) as carbon sources via a facile solidstate method. CS can bond with GO through electrostatic force between amino group on CS and carboxy group on GO. Withhigh temperature treatment, GO can be reduced to graphene and CS can be decomposed into carbon. By adding chitosan,severe agglomeration of graphene can be prevented. As a result, a continuous conductive framework was formed. The goodconductivity facilitates electron migration, contributing to excellent electrochemical performance especially the high-rateperformance. Consequently, the composite LiFePO4/graphene/C exhibited higher initial discharge capacity of 145.2 mAh • g−1atthe low rate of 0.1 C and retained 62.6 mAh • g−1at high rate of 10 C, while the LiFePO4 merely coated with graphene (LFP/G) was 125.9 mAh • g−1(0.1 C) and 6.5 mAh • g−1(10 C), respectively.

Particle resolved CFD simulation on vapor-phase synthesis of vinyl acetate from ethylene in fixed-bed reactor

Yonghui Li,Mingkai Wang,Xingxing Cao,Zhongfeng Geng 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.5

The synthesis of vinyl acetate (VAc) from ethylene is a strongly exothermic reaction that might easily cause catalyst deactivation and reduce selectivity of VAc. Research at the bed scale helps to improve the conversion of C2H4 and the selectivity of VAc. In this study, the discrete element method (DEM) was used to construct a fixed-bed structure model via simulating the filling process of catalyst particles in the reactor. The inlet section of a reaction tube was studied, and its length was 10 cm. The temperature distribution, and the effects of particles size, inlet velocity, inlet temperature and the feed ratio of C2H4 to O2 on the reaction process were studied. Simulated results show that the bed temperature gradually increased from the wall to the center, and the temperature gradient gradually decreased along the radial direction. The maximum temperature was 438.68 K and the temperature difference from the inlet temperature was 5.54 K. Comparing the composite particle packed bed with the single particle size packed bed, the composite packed bed has higher vinyl acetate selectivity. Increasing inlet velocity from 1.5m/s to 3.5m/s, the selectivity of vinyl acetate increased from 91.71% to 92.60%. Adding an inert gas to the feed gas can increase the oxygen concentration and reduce the explosion interval of C2H4, the conversion of C2H4 and the selectivity of vinyl acetate increased.

Design-oriented fast response voltage mode buck converter with adaptive ramp control

Peng, Xingxing,Li, Changgeng The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.5

This paper proposes a new adaptive ramp voltage mode control scheme. Instead of using the conventional slow compensation path of the voltage mode, the proposed scheme adds an extra feedback path to adjust the amplitude and DC-offset of the ramp signal and to directly accelerate the duty cycle according to the output voltage variation. In addition, a design-oriented analytical method is adopted to intuitively analyzes the loop characteristics and provides accurate instructions for the implementation and optimization of the compensator. A 5-1 V buck converter is implemented in the proposed adaptive ramp control scheme with optimized compensation. Simulation and measurement results show that the converter achieves a bandwidth of up to 591 kHz with a 3 MHz switching frequency and a 65° phase margin. In addition, the undershoot voltage and the recovery time are 16 mV and 19 ㎲ with a load change from 0.5 to 1 A. The proposed control scheme shows superior transient response performance while maintaining fixed frequency operations with a simple system structure.

LncRNA PVT1 influences breast cancer cells glycolysis through sponging miR-145-5p

Qu Huan,Li Xingxing,Chen Fei,Zhang Min,Lu Xun,Gu Yun,Lv Mingming,Lu Cheng 한국유전학회 2023 Genes & Genomics Vol.45 No.5

Background Long-non-coding RNA PVT1 (lncRNA PVT1) can be used as an oncogenic regulatory non-coding RNA (ncRNA) for many cancers. However, its function and mechanism in breast cancer (BRCA) are still not clearly elucidated. Objective We attempt to explain the mechanism of PVT1’s role in breast cancer from different perspectives. Methods We analyzed the expression of PVT1 and its correlation with the breast cancer related clinical data in the The Cancer Genome Atlas (TCGA) database. We used PVT1 overexpression and knockdown lentivirus to infect breast cancer MDA-MB-231 cell line for cell function verification, in vitro using CCK-8 to measure proliferation, flow cytometry to measure apoptosis, transwell test to measure invasion and migration ability, detecting cell extracellular acidification rate (ECAR) to assess glycolysis metabolism and explore the biological functions of PVT1 in breast cancer cells. Transcriptome sequencing was used to analyze the changes of related genes in cells after overexpression of PVT1. In vivo we used a xenograft model to study the effect of PVT1 on breast cancer. Results PVT1 was up-regulated in breast cancer tissues and was positively correlated with the clinical stage of breast cancer patients. Overexpression of PVT1 in vitro promoted cell proliferation, migration and invasion, and promoted tumor growth in vivo. Knockdown of PVT1 led to the opposite biological consequence. Further bioinformatics analysis showed that PVT1 changes the glycolysis metabolism of tumors through regulation of glycolysis-related genes. In addition, the expression of miR-145-5p is negatively correlated with PVT1. We consider the possibility of PVT1 promoting cell proliferation and metastasis by regulating the aerobic glucose metabolism in breast cancer cells through sponging the miR-145-5p. Conclusion Our results reveal a potential pathway for competing endogenous RNA to regulate breast cancer glucose metabolism. PVT1 regulates glycolysis related genes expression by competitively binding to endogenous miR-145-5p in breast cancer cells to change the metabolic phenotype. This may Provide new ideas for precise molecular therapy targets for breast cancer.

Characteristic profiles of biofilm, enterotoxins and virulence of Staphylococcus aureus isolates from dairy cows in Xinjiang Province, China

Yehui Wu,Jing Li,Mengfan Qiao,Dan Meng,Qingling Meng,Jun Qiao,Xingxing Zhang,Lixia Wang,Kuojun Cai,Jinsheng Zhang,Zaichao Zhang,Weiwei Yu,Xuepeng Cai 대한수의학회 2019 Journal of Veterinary Science Vol.20 No.6

As an important zoonotic pathogen, Staphylococcus aureus (S. aureus) infection has led to serious mastitis and endometritis in infected dairy cows. HereIn this study, a total of 164 strains of S. aureus were isolated from dairy cows in Xinjiang Province, China, and subjected to assays to determine of drug susceptibility and biofilm (BF) formation ability. The eEnterotoxin-related genes were detected, and then the transcription levels of genes related to BF formation were also determined by using reverse transcription-quantitative polymerase chain reactionPCR. Moreover, the pathogenicity of these isolates with different BF formation abilities was determined via by measuring their hemolysis activity, half lethal dose (LD50) and organ bacterial load, respectively. The results showed that 83.4 % of S. aureus isolates could form BF. Among them, 40.8 % of the strains had weak BF formation ability, and most strains with a strong BF formation ability were ica gene carriers. The S. aureus isolates displayed multidrug resistance and their drug resistance was positively correlated with their BF formation ability. Moreover, 96.3 % of the S. aureus isolates carried enterotoxin genes. Among them, the detection rates of the novel enterotoxin genes were higher than thoseat of conventional enterotoxin genes. Furthermore, the isolates with a strong BF formation ability had higher LD50 but lower hemolysis ability and organ bacterial load than thoseat of the isolates with weak or no BF ability. However, those isolates without BF ability caused produced more severe pathological changes than thoseat of the isolates with strong BF formation ability. These findings suggested that higher frequencies of BF ability and presence of novel enterotoxin genes were are important characteristics of S. aureus isolates from dairy cows in Xinjiang Province, China, and such isolateswhich may posed potential threats to food safety.

Insight into the anti-corrosion performance of three imidazo-pyridazines for Al alloy in different concentrations of hydrochloric acid solutions

Xiaolei Ren,Jinwu Bai,Xingxing Gu,Hui Xu,Bochuan Tan,Shenying Xu,Jiangyu Hao,Fang Gao,Xin Li 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.113 No.-

Imidazo-pyridazine and Bromo/Chloro-Imidazo-pyridazines are employed as the inhibitors for Al alloy in0.1 M HCl and 0.5 M HCl solutions. The electrochemical tests and adsorption model analysis revealed thatthree compounds are mixed-type inhibitors and Imidazo-pyridazine exhibited the best anti-corrosionperformance for Al electrode in HCl solutions by physicochemical. From electrochemical results, the bestanti-corrosion efficiency is 88.1 % for Al in 0.5MHCl with 2.0mMIP, while the efficiency is 75.5 % for Al in0.5 M HCl with 1.0 mM IP. The different inhibition behaviors result from the probability of the formationof AlCladsand N-onium ions. The formation of adsorption is due to the electrostatic attraction betweenAlCladsand N-onium ions. The surface topography test revealed that the Imidazo-pyridazine is the best corrosionbarrier for Al in 0.5 M HCl. The dynamic simulation demonstrated that the inhibition molecules andprotonated molecules can adsorb on the Al surface spontaneously with parallel adsorption configuration nomatter in more or less Cl- atmosphere.