Preparation of Non-woven Fabric Reinforced Poly(vinylidene fluoride) Composite Membranes for Water Treatment

Xiao Wu,Huiju Shao,Jifeng Cheng,Dongdong Kang 한국섬유공학회 2022 Fibers and polymers Vol.23 No.5

To optimize the mechanical properties of polymeric membranes fabricated by non-solvent induced phaseseparation (NIPS), a non-woven fabric has been used to reinforce the composite membrane. However, it remains a challengeto prepare an intact polymer membrane on the non-woven fabric because casting dopes usually spread into the poroussubstrate. Herein, a kind of non-woven fabric reinforced poly(vinylidene fluoride) (PVDF) composite membrane wasfabricated by using poly(vinyl pyrrolidone) (PVP) to control the viscosity of casting dopes. Additionally, the effects of nonwovenfabric on the membrane structure and properties were explored in the light of dynamics during the phase inversionprocess. A porous skin layer and long finger-like pores were successfully created on the surface and inner of membraneswhen 6 wt% PVP was added in the casting dopes. Compared with pure PVDF membranes, the pure water flux of the resultantmembrane was elevated from 49.9 L/m2h to 656 L/m2h, BSA rejection from 40.5 % to 86.4 %, and flux recovery ratio (FRR)from 58.7 % to 86.1 %. More importantly, it also possessed outstanding mechanical properties, which far outperforms theresults reported in some literatures. This study suggests a promising strategy to fabricate PVDF composite membranes withpreeminent properties for wastewater treatment.

A Comparative Study on Refusal Speech Actbetween Chinese Korean Language Learners andthe Native Koreans

Xiao Wu,Xianghua Tai,김진식 한국중원언어학회 2019 언어학연구 Vol.0 No.51

Refusal is one of typical speech acts in daily communication. As a face-threatening act, refusal might bring burdens to both parties of dialogue. To reduce potential conflicts, various refusal strategies (e.g., giving a reason, evasive expression, proposition, etc) were studied. Despite extensive cultural contents shared by China and South Korea, there are significant differences in social ideologies and ways of thinking, which result in variations in pragmatic strategies for refusal speech acts. However, few studies have focused on differences in speech acts between non-native Chinese students learning Korean and native Koreans. This study investigates differences in refusal speech acts between native Korean exchange students and Chinese learners of the Korean language at different proficiency levels from universities in Qingdao. The study employs methods of DCT and role-playing conversations with 24 refusal scenes as well as self-defined classification of refusal strategies. Results showed significant differences between them in terms of quantity and frequency of refusal strategies. This study could help to prepare lesson plans for Chinese Korean language learners and guide them to learn the Korean language more effectively.

Production and Development of Small-Sized Watermelon in China

Xiaowu Sun,Shezhang Tang 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

The genome of the mesopolyploid crop species Brassica rapa

Wang, Xiaowu,Wang, Hanzhong,Wang, Jun,Sun, Rifei,Wu, Jian,Liu, Shengyi,Bai, Yinqi,Mun, Jeong-Hwan,Bancroft, Ian,Cheng, Feng,Huang, Sanwen,Li, Xixiang,Hua, Wei,Wang, Junyi,Wang, Xiyin,Freeling, Michael Nature Publishing Group, a division of Macmillan P 2011 Nature genetics Vol.43 No.10

We report the annotation and analysis of the draft genome sequence of Brassica rapa accession Chiifu-401-42, a Chinese cabbage. We modeled 41,174 protein coding genes in the B. rapa genome, which has undergone genome triplication. We used Arabidopsis thaliana as an outgroup for investigating the consequences of genome triplication, such as structural and functional evolution. The extent of gene loss (fractionation) among triplicated genome segments varies, with one of the three copies consistently retaining a disproportionately large fraction of the genes expected to have been present in its ancestor. Variation in the number of members of gene families present in the genome may contribute to the remarkable morphological plasticity of Brassica species. The B. rapa genome sequence provides an important resource for studying the evolution of polyploid genomes and underpins the genetic improvement of Brassica oil and vegetable crops.

Deletion of lacD gene affected stress tolerance and virulence of Streptococcus suis serotype 2

Jiang Xiaowu,Zhu Lexin,Zhan Dongbo 한국미생물학회 2022 The journal of microbiology Vol.60 No.9

Streptococcus suis type 2 (S. suis type 2, SS2), an infectious pathogen which is zoonotic and can induce severely public health concern. Our previous research identified a newly differential secreted effector of tagatose-bisphosphate aldolase (LacD) mediated by VirD4 factor within the putative type IV secretion system of SS2, whereas the functional basis and roles in virulence of LacD remain elusive. Here in this study, the LacD was found enzymatic and can be activated to express under oxidative stress. Gene mutant and its complemental strain (ΔlacD and cΔlacD) were constructed to analyze the phenotypes, virulence and transcriptomic profiles as compared with the parental strain. The lacD gene deletion showed no effect on growth capability and cells morphology of SS2. However, reduced tolerance to oxidative and heat stress conditions, increased antimicrobial susceptibility to ciprofloxacin and kanamycin were found in ΔlacD strain. Further, the LacD deficiency led to weakened invasion and attenuated virulence since an easier phagocytosed and more prone to be cleared of SS2 in macrophages were shown in ΔlacD mutant. Distinctive transcriptional profiling in ΔlacD strain and typical downregulated genes with significant mRNA changes including alcohol dehydrogenase, GTPase, integrative and conjugative elements, and iron ABC transporters which were mainly involved in cell division, stress response, antimicrobial susceptibility and virulence regulation, were examined and confirmed by RNA sequencing and real time qPCR. In summary, the results demonstrated for the first time that LacD was a pluripotent protein mediated the metabolic, stress and virulent effect of SS2.

Printing of self-healable gelatin conductors engineered for improving physical and electrical functions: Exploring potential application in soft actuators and sensors

최건오,Xiaowu Tang,Rixuan Wang,Kaibin Wu,정용진,안태규,김세현,Liwei Mi 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.116 No.-

Significant efforts have been devoted to developing dielectric elastomer actuators owing to their mechanicalflexibilities, silent operation, and muscle-like performances. However, it still remains a challenge todemonstrate the actuators that maintain function when subjected to damage because most soft materialsconstituting such devices are vulnerable to mechanical stresses during repeated operation. Here, selfhealableelectrodes suitable for dielectric elastomer actuators were prepared from an eco-friendlygelatin-based composite including conductive ions and hydrogen bonds. Electrohydrodynamic printingwas used to reproducibly fabricate a custom-made electrode with desired geometry. The printedgelatin-based electrodes were attached onto elastomers to fabricate dielectric elastomer actuators. Thedevices exhibited good actuator operation and, owing to the self-healing capability of the gelatinbasedelectrodes, almost fully recovered their performances with an efficiency of up to 96.8% even afterthe electrodes were damaged. Furthermore, the potential application of the gelatin-based electrode wasexplored by using them as a strain sensor; this sensor showed a sensitive dependence of electrical resistanceon external joint movements. We believe this work provides a useful guideline for designing selfhealableconductive composites that can be effectively used to make printed actuators and sensorsendowed with good ionic conductivity and useful mechanical properties.

Observer-based Intermittent Consensus Control of Nonlinear Singular Multi-agent Systems

Xinxin Xie,Xiaowu Mu 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.9

This paper studies the leader-following consensus for a class of nonlinear singular multi-agent systems. Unlike the related works, the case that states of agents are unavailable and communication channel among agents may be subjected to frequently attacks is considered, where agents can only communicate with their neighbors on some disconnected time intervals. Based on graph theory, singular system theory and multi-Lyapunov function approach, the observer-based intermittent feedback control protocol and sufficient conditions are given to ensure the existence and uniqueness of solutions and consensus of the considered systems. Besides, a description of state jumps of the systems at the instants of communication changes is presented. Finally, a numerical example is given to illustrate the feasibility of the result.

H∞ Containment Control of Multi-agent Systems with Random Communication Time-varying Delay

Minhong He,Xiaowu Mu 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.4

This paper investigates the H∞ containment control problem of multi-agent systems with random communication time-delay. The information exchanges between the agents are supposed to be randomly delayed, characterized by a Bernoulli distribution sequence. And a neighbor-based protocol with random communication delay is proposed. As external perturbation exits broadly in many practical systems, the paper deals with it by using H∞ control theory. By applying stochastic technique, Lyapunov analysis and the free-weighting matrices technique, theoretical results show that the followers will ultimately converge to the convex hull spanned by the leaders in the mean square sense with a prescribed H∞ performance index. Finally, a numerical example is given to demonstrate the validity of the theoretical results.

Aerosol Measurement and Property Analysis Based on Data Collected by a Micro-pulse LIDAR over Shanghai, China

Xingyou Huang,Xiaowu Yang,Fuhai Geng,Hua Zhang,Qianshan He,Lingbing Bu 한국광학회 2010 Current Optics and Photonics Vol.14 No.3

A micro-pulse LIDAR system (MPL) was employed to measure the aerosol over Pudong, Shanghai from July 2008 to January 2009. Based on Fernald method, aerosol optical variables such as extinction coefficient were retrieved and analyzed. Results show that aerosol exists mainly in low layers; aerosol loading reaches its maximum in the afternoon, and then decreases with time until its minimum at night. Most of the aerosol concentrates in the layer below 3 km, and optical extinction coefficient in the layer below 2 km contributes 84.25% of that below 6 km. Two extinction coefficient peaks appear in the near surface layer up to 500 m and in the level around 1000 m. Aerosol extinction coefficient shows a seasonal downward trend from summer to winter.

Event-driven Fault Tolerant Control for Networked Switched Linear Systems with Asynchronous Switching

Yang Song,Xiaowu Mu 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.6

In this paper, the event-driven fault tolerant control is investigated for networked switched linear systems subject to actuator failures with asynchronous switching. Firstly, by applying the augmented switching signal technique and event-driven communication scheme, the original systems is established as a closed-loop linear switched systems, and the fault tolerant control is considered for networked switched linear systems under the given actuator failures model. In addition, compared with the common Lyapunov function method, a piece-wise Lyapunov functionis proposed in this paper to analysis the H∞ performance of the switched linear systems with actuator failures. After that, sufficient conditions are established to ensure the exponential stability of systems, which are obtained under dwell time and average dwell time, respectively. Finally, an example is given to illustrate the effectiveness of the conclusion.