Effect of Burkholderia contaminans on Postharvest Diseases and Induced Resistance of Strawberry Fruits

Wang, Xiaoran,Shi, Junfeng,Wang, Rufu The Korean Society of Plant Pathology 2018 Plant Pathology Journal Vol.34 No.5

This study takes strawberry-fruits as the test material and discusses the effect of Burkholderia contaminans B-1 on preventing postharvest diseases and inducing resistance-related substances in strawberry-fruits. Soaking and wound inoculating is performed to analyze the inhibitory effects of different treatment solutions on the gray mold of postharvest strawberry-fruits. The count of antagonistic bacteria colonies in the wound is found, and the dynamic growth of antagonistic bacteria and the pathogenic fungus is observed by electron microscopy. The results indicated that, either by soaking/wound-inoculating, the fermentation and suspension of antagonistic bacteria significantly reduced the incidence of postharvest diseases of strawberry-fruits. With wound inoculation, the inhibition rate of antagonist fermentation and suspension ($1{\times}10^{10}cfu/ml$) respectively reached 77.4% and 66.7%. It also led to a significant increase in the activity of resistance-related enzymes, i.e., phenylalanine ammonia lyase (PAL), 4-coumarate coenzyme A ligase (4CL), cinnamate-4-hydroxylase (C4H) and chalcone isomerase (CHI). On 1 d and 2 d post-treatment, the activity of 4CL was respectively 3.78 and 6.1 times of the control, and on 5 d, the activity of PAL was increased by 4.47 times the control. The treatment of antagonistic bacteria delayed the peaking of cinnamyl-alcohol dehydrogenase (CAD) activity and promoted the accumulation of lignin and total phenols. The antagonistic bacteria could be well colonized in the wounds. On 4-5 d post-inoculation, the count of colonies was $10^8$ times of that upon inoculation. Electronmicroscopy indicated that the antagonistic bacteria delayed the germination of pathogenic spores in the wounds, and inhibited further elongations of the mycelia.

A Study on Chinese College Students’ Acceptance of Using Rain Classroom to Have Online English Courses During the COVID-19 Outbreak

Wang Xiaoran 중앙대학교 외국학연구소 2022 외국학연구 Vol.- No.61

This study investigated Chinese college EFL learners’ perceptions of Rain Classroom, a technology adopted for online English learning and instruction, by applying the Unified Theory of Acceptance and Use of Technology 2 (UTAUT2) model in order to determine what factors affected students’ perceptions a nd intentions to use it. This study analyzed the correlation between the variables of UTAUT2 and students’ acceptance of using Rain Classroom as a tool for delivering online College English courses during the outbreak of Covid-19 pandemic in Beijing, China. The results from the analysis of data revealed that performance expectancy (PE), facilitating conditions (FC) and hedonic motivation (HM) all played a significant role in influencing college students’ continuance intention to use Rain Classroom for their future online study. Among these, HM was the strongest determinant of the future intention to use Rain Classroom. The constructs of effort expectancy (EE) and social influence (SI), however, did not have a significant impact on behavioral intention of college EFL students regarding Rain Classroom adoption. Practical implications and possible future study directions were also proposed based on the research findings.

Effect of Burkholderia contaminans on Postharvest Diseases and Induced Resistance of Strawberry Fruits

Xiaoran Wang,Junfeng Shi,Rufu Wang 한국식물병리학회 2018 Plant Pathology Journal Vol.34 No.5

This study takes strawberry-fruits as the test material and discusses the effect of Burkholderia contaminans B-1 on preventing postharvest diseases and inducing resistance-related substances in strawberry-fruits. Soaking and wound inoculating is performed to analyze the inhibitory effects of different treatment solutions on the gray mold of postharvest strawberry-fruits. The count of antagonistic bacteria colonies in the wound is found, and the dynamic growth of antagonistic bacteria and the pathogenic fungus is observed by electron microscopy. The results indicated that, either by soaking/ wound-inoculating, the fermentation and suspension of antagonistic bacteria significantly reduced the incidence of postharvest diseases of strawberry-fruits. With wound inoculation, the inhibition rate of antagonist fermentation and suspension (1 × 1010 cfu/ml) respectively reached 77.4% and 66.7%. It also led to a significant increase in the activity of resistance-related enzymes, i.e., phenylalanine ammonia lyase (PAL), 4-coumarate coenzyme A ligase (4CL), cinnamate-4-hydroxylase (C4H) and chalcone isomerase (CHI). On 1 d and 2 d post-treatment, the activity of 4CL was respectively 3.78 and 6.1 times of the control, and on 5 d, the activity of PAL was increased by 4.47 times the control. The treatment of antagonistic bacteria delayed the peaking of cinnamyl-alcohol dehydrogenase (CAD) activity and promoted the accumulation of lignin and total phenols. The antagonistic bacteria could be well colonized in the wounds. On 4-5 d post-inoculation, the count of colonies was 108 times of that upon inoculation. Electronmicroscopy indicated that the antagonistic bacteria delayed the germination of pathogenic spores in the wounds, and inhibited further elongations of the mycelia.

Chinese English Learners’ Perspectives on Automated Writing Feedback

Wang Xiaoran 한국멀티미디어언어교육학회 2023 멀티미디어 언어교육 Vol.26 No.2

This study examined Chinese college English learners’ perspectives of the automated writing feedback generated by Pigai, the most widely used automatic writing evaluation (AWE) tool in China. Additionally, this study investigated the differences in Chinese college learners’ perspectives of Pigai feedback according to their proficiency levels. Student participants included 70 students from two classes who took the same college English course at one Chinese university. The students in class A were higher level EFL learners, while students in class B were lower level EFL learners. In both classes, Pigai was incorporated into the process-based writing practice along with teacher feedback. Students’ perspectives of the automated writing feedback generated by Pigai were investigated via survey after the course. The findings revealed that all participants demonstrated highly positive perspectives. Besides, both higher- and lower-proficiency groups exhibited similar perspectives regardless of their proficiency levels. Moreover, most participants expressed a preference for receiving both Pigai feedback and teacher feedback integrated into their writing process. Practical implications were also discussed for writing instruction using AWE technology in EFL writing classes such as AWE tools can be used with teacher feedback together to assist writing for classes with students of various proficiency levels.

Effect of an electric field on the molecular properties of tributyrin, tricaproin and tricaprylin: a theoretical study

Wang Yachao,Lin Xiaoran,Wang Mei 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.79 No.4

Tributyrin, tricaproin and tricaprylin molecules are typical representatives of short-medium chain-saturated triglycerides and maybe used as additives to improve the viscosity of natural ester insulating oil. In this work, we study the effect of an electric field on the molecular properties of the three molecules using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The level of electric field intensity during streamer initiation and propagation in insulating oil was considered for the intensities from – 3.8 × 109 V/m to 3.8 × 109 V/m. The molecular structures, infrared spectra, orbital energies and excited states under different applied electric fields were calculated. The molecular structures of the three kinds of molecules showed obvious changes and the Stark effect was observed under the electric field. Compared with tributyrin and tricaproin, the electric field has more influence on the orbital energy level of tricaprylin. The ionization potential of tricaprylin was reduced by about 25% when the electric field intensity was 3.8 × 109 V/m. The calculated results for the excited states show that the dependence of the excitation energy on the intensity of electric field was not as strong as that of the ionization potential on the electric field. On the whole, tributyrin and tricaproin showed more stable properties than tricaprylin under an applied electric field. The results can deepen our understanding of the discharge mechanism of natural esters under an applied electric field, especially the characteristics of the short-chain-saturated triglycerides. They also provide theoretical support for the improved performance of natural ester insulating oil.

Experimental study and modelling of CFRP-confined damaged and undamaged square RC columns under cyclic loading

Li Su,Xiaoran Li,Yuanfeng Wang 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.2

While the cyclic behaviour of fiber-reinforced polymer (FRP)-confined columns is studied rather extensively, the cyclic response especially the energy dissipation of FRP-confined damaged and undamaged square RC columns is not yet fully understood. In this paper, an experimental and numerical investigation was conducted to study the cyclic behavior of two different types of Carbon FRP (CFRP)-confined square RC columns: strengthened and repaired. The main variables investigated are initial damage, confinement of CFRP, longitudinal steel reinforcement ratio. The experimental results show that lower initial damage, added confinement with CFRP and longitudinal reinforcement enhance the ductility, energy dissipation capacity and strength of the columns, decrease the stiffness and strength degradation rates of all CFRP-confined square RC columns. Two hysteretic constitutive models were developed for confined damaged and undamaged concrete and cast into the non-linear beam-column fiber-based models in the software Open System for Earthquake Engineering Simulation (OpenSees) to analyze the cyclic behavior of CFRP-confined damaged and undamaged columns. The results of the numerical models are in good agreement with the experiments.

Damping determination of FRP-confined reinforced concrete columns

Yuan-Feng Wang,Xiaoran Li,Li Su 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.14 No.2

Damping as a material property plays an important role in decreasing dynamic response of structures. However, very little is known about the evaluation and application of the actual damping of Fiber Reinforced Polymer Confined Reinforced Concrete (FRP-C RC) material which is widely adopted in civil engineering at present. This paper first proposes a stress-dependent damping model for FRP-C RC material using a validated Finite Element Model (FEM), then based on this damping-stress relation, an iterative scheme is developed for the computations of the non-linear damping and dynamic response of FRP-C RC columns at any given harmonic exciting frequency. Numerical results show that at resonance, a considerable increase of the loss factor of the FRP-C RC columns effectively reduces the dynamic response of the columns, and the columns with lower concrete strength, FRP volume ratio and axial compression ratio or higher longitudinal reinforcement ratio have stronger damping values, and can relatively reduce the resonant response.

Conceptual design for a multi-rotor UAV based on variable paddle pitch

Zhen Qin,Xiaoran Tang,Ziqi Meng,Yu-Ting Wu,류성기,Yue Wang 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.10

The field of unmanned aerial vehicles has experienced a "golden era" of progress in recent years (UAV). UAVs come in a vast variety, from the commercial to the military sectors. The UAVs available today are tiny, mini multirotor devices. The advantages of the small multi-rotor structure are its small size, straightforward design, high hovering effectiveness, adaptability in changing directions, and quick flight speed. For activities like tracking and aerial photography, it is especially useful. However, the majority of multi-rotor UAVs, according to current UAV offers, are built around cameras and sensors. As a result, they can't complete other kinds of missions due to their large overall size, light weight, and small cargoes. The outbreak has sparked interest in and study into whether contactless distribution and logistics are practical. Unmanned mechanical devices for various rescue and specialized duties are also being researched by organizations. Therefore, a medium to big multi-rotor UAV needs to be researched and developed. The assembly of paddle holders and auto-tilters for medium- to large-sized multi-rotor UAVs is examined in this work. The multi-rotor UAV is intended to mount an auto-tilter. Its component strength checks are analyzed. Additionally, the blade requirements are chosen, along with strength tests of the individual components, and the structural design of the UAV rotor system is provided. The mechanical viability of the UAV is then confirmed using a motion simulation of its mechanical design.

Hazard prediction of coal and gas outburst based on fisher discriminant analysis

Chen, Liang,Wang, Enyuan,Feng, Junjun,Wang, Xiaoran,Li, Xuelong Techno-Press 2017 Geomechanics & engineering Vol.13 No.5

Coal and gas outburst is a serious dynamic disaster that occurs during coal mining and threatens the lives of coal miners. Currently, coal and gas outburst is commonly predicted using single indicator and its critical value. However, single indicator is unable to fully reflect all of the factors impacting outburst risk and has poor prediction accuracy. Therefore, a more accurate prediction method is necessary. In this work, we first analyzed on-site impacting factors and precursors of coal and gas outburst; then, we constructed a Fisher discriminant analysis (FDA) index system using the gas adsorption index of drilling cutting ${\Delta}h_2$, the drilling cutting weight S, the initial velocity of gas emission from borehole q, the thickness of soft coal h, and the maximum ratio of post-blasting gas emission peak to pre-blasting gas emission $B_{max}$; finally, we studied an FDA-based multiple indicators discriminant model of coal and gas outburst, and applied the discriminant model to predict coal and gas outburst. The results showed that the discriminant model has 100% prediction accuracy, even when some conventional indexes are lower than the warning criteria. The FDA method has a broad application prospects in coal and gas outburst prediction.

Space Charge Accumulation Mechanism Near the Stress Cone of Cable Accessories Under Electrical-Thermal Aging

Dongxin He,Wenjie Gong,Tao Zhang,Wei Wang,Xiaoran Wang,Qingquan Li 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.1

Due to the complicated structure composed of diff erent kinds of materials, space charges tend to accumulate within cable accessories, which easily leads to the electrical breakdown. To obtain insights into the space charge accumulation in cable accessories, accelerated aging was performed for 10 kV crosslinked polyethylene (XLPE) insulated cable samples with stress cones, under an AC voltage of 26.1 kV and temperatures of 103 °C and 114 °C. The space charge distribution in the cable insulation was tested at diff erent aging stages. The results show that space charge accumulates in the insulation covered by the stress cones, and the charge density and coaxial distribution region increase during aging. Together with the results for the charge measurement on peeled cable samples, it is concluded that charge accumulation is related to the semiconductor used in the stress cones. It is diffi cult for the space charge generated in the cable insulation to escape through the silicone rubber-based (SR-based) semiconductor in the stress cones, as the ability of this material to conduct charges is lower than that of a cable-shielding ethylene–vinyl acetate-based (EVA-based) semiconductor; therefore, the space charge accumulates near the outer part of the insulation. This research provides insights into the important function of semiconductor on charge accumulation in cable accessories, which will aid in research on optimizing and prolonging the lifetime of cable accessories.