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A Facile Route for the Large Scale Fabrication of Graphene Oxide Papers and Their Mechanical Enhancement by Cross-linking with Glutaraldehyde

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Nano-Micro Letters 2011年第4期3卷 215-222页

作者： Nantao Hu Lei Meng Rungang Gao Yanyan Wang Jing Chai Zhi Yang eric siu-wai kong Yafei Zhang Key Laboratory for Thin Film and Microfabrication of the Ministry of Education Research Institute of Micro/Nano Science & TechnologyShanghai Jiao Tong University

A facile route for the large scale production of graphene oxide(GO) papers and their mechanical enhancement has been presented in this work. The novel paper-like GO made from individual GO sheets in aqueous suspension can be achieved in large scale by a simple drop casting method on hydrophobic *** enhancement in mechanical stiffness(341%) and fracture strength(234%) of GO paper have been achieved upon modification with a small amount(less than 10 wt%) of glutaraldehyde(GA). The cross-linking reaction takes place between hydroxyl groups on the surface of GO and aldehyde groups of GA, through forming hemiacetal structure, which can result in distinct mechanical enhancement of the GO papers.

关键词： Graphene oxide paper Glutaraldehyde Cross-linking Mechanical enhancement

The Prospective Two-Dimensional Graphene Nanosheets: Preparation, Functionalization, and Applications

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Nano-Micro Letters 2012年第1期4卷 1-9页

作者： Zhi Yang Rungang Gao Nantao Hu Jing Chai Yingwu Cheng Liying Zhang Hao Wei eric siu-wai kong Yafei Zhang Key Laboratory for Thin Film and Microfabrication of the Ministry of Education Research Institute of Micro/Nano Science and Technology Shanghai Jiao Tong University

Graphene, as an intermediate phase between fullerene and carbon nanotube, has aroused much interests among the scientific community due to its outstanding electronic, mechanical, and thermal *** excellent electrical conductivity of 6000 S/cm, which is independent on chirality, graphene is a promising material for high-performance nanoelectronics, transparent conductor, as well as polymer composites. On account of its Young's Modulus of 1 TPa and ultimate strength of 130 GPa, isolated graphene sheet is considered to be among the strongest materials ever measured. Comparable with the single-walled carbon nanotube bundle,graphene has a thermal conductivity of 5000 W/(m·K), which suggests a potential application of graphene in polymer matrix for improving thermal properties of the graphene/polymer composite. Furthermore, graphene exhibits a very high surface area, up to a value of 2630 m^2/g. All of these outstanding properties suggest a wide application for this nanometer-thick, two-dimensional carbon material. This review article presents an overview of the significant advancement in graphene research: preparation, functionalization as well as the properties of graphene will be discussed. In addition, the feasibility and potential applications of graphene in areas, such as sensors, nanoelectronics and nanocomposites materials, will also be reviewed.

关键词： Graphene Graphite oxide Functionalization Sensors Transparent conductive films Nanocom posites

Preparation and growth mechanism of nickel nanowires under applied magnetic field

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Nano-Micro Letters 2010年第2期2卷 134-138页

作者： J.Wang L.Y.Zhang P.Liu T.M.Lan J.Zhang L.M.Wei eric siu-wai kong C.H.Jiang Y.F.Zhang National Key Laboratory of Nano/Micro Fabrication Technology Key Laboratory for Thin Film and Microfabrication of the Ministry of Education Institute of Micro and Nano Science and Technology Shanghai Jiao Tong University School of Materials Science and Engineering Shanghai Jiao Tong University Zhongyuan University of Technology

Nickel nanowires with large aspect ratio of up to 300 have been prepared by a hydrazine hydrate reduction method under applied magnetic field. The diameter of nickel nanowires is about 200 nm and length up to 60 μm. The role of magnetic field on the growth of magnetic nanowires is discussed and a magnetic nanowire growth mechanism has been proposed. Nickel ions are firstly reduced to nickel atoms by hydrazine hydrates in a strong alkaline solution and grow into tiny spherical nanoparticles. Then, these magnetic particles will align under a magnetic force and form linear chains. Furthermore, the as-formed chains can enhance the local magnetic field and attract other magnetic particles nearby, resulting finally as linear nanowires. The formation and the size of nanowires depend strongly on the magnitude of applied magnetic field.

关键词： Nanowire growth mechanism Nickel nanowires Magnetic-field assisted synthesis

Understanding the role of PIN1 in hepatocellular carcinoma

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World Journal of Gastroenterology 2016年第45期22卷 9921-9932页

作者： Chi-wai Cheng Ka-wai Leong eric Tse Department of Medicine The University of Hong Kong Queen Mary Hospital

PIN1 is a peptidyl-prolyl cis/trans isomerase that binds and catalyses isomerization of the specific motif comprising a phosphorylated serine or threonine residue preceding a proline(p Ser/Thr-Pro) in proteins. PIN1 can therefore induce conformational and functional changes of its interacting proteins that are regulated by proline-directed serine/threonine phosphorylation. Through this phosphorylation-dependent prolyl isomerization, PIN1 fine-tunes the functions of key phosphoproteins(e.g., cyclin D1, survivin, β-catenin and x-protein of hepatitis B virus) that are involved in the regulation of cell cycle progression, apoptosis, proliferation and oncogenic transformation. PIN1 has been found to be over-expressed in many cancers, including human hepatocellular carcinoma(HCC). It has been shown previously that overexpression of PIN1 contributes to the development of HCC invitro and in xenograft mouse model. In this review, we first discussed the aberrant transcription factor expression, miR NAs dysregulation, PIN1 gene promoter polymorphisms and phosphorylation of PIN1 as potential mechanisms underlying PIN1 overexpression in cancers. Furthermore, we also examined the role of PIN1 in HCC tumourigenesis by reviewing the interactions between PIN1 and various cellular and viral proteins that are involved in β-catenin, NOTCH, and PI3K/Akt/mT OR pathways, apoptosis, angiogenesis and epithelial-mesenchymal transition. Finally, the potential of PIN1 inhibitors as an anti-cancer therapy was explored and discussed.

关键词： Phosphorylation Hepatocellular carcinoma PIN1 Isomerization Hepatocarcinogenesis

Spatial memory enhances the evacuation efficiency of virtual pedestrians under poor visibility condition

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Chinese Physics B 2018年第3期27卷 560-567页

作者： Yi Ma eric wai Ming Lee Meng Shi Richard Kwok Kit Yuen Institute for Disaster Management and Reconstruction Sichuan University Chengdu 610207 China Department of Architecture and Civil Engineering City University of Hong Kong Kowloon Hong Kong China

Spatial memory is a critical navigation support tool for disoriented evacuees during evacuation under adverse environ-mental conditions such as dark or smoky conditions. Owing to the complexity of memory, it is challenging to understand the effect of spatial memory on pedestrian evacuation quantitatively. In this study, we propose a simple method to quan- titatively represent the evacuee＇s spatial memory about the emergency exit, model the evacuation of pedestrians under the guidance of the spatial memory, and investigate the effect of the evacuee＇s spatial memory on the evacuation from theoretical and physical perspectives. The result shows that （i） a good memory can significantly assist the evacuation of pedestrians under poor visibility conditions, and the evacuation can always succeed when the degree of the memory exceeds a threshold （φ〉 0.5）; （ii） the effect of memory is superior to that of ＂follow-the-crowd＂ under the same environmental conditions; （iii） in the case of multiple exits, the difference in the degree of the memory between evacuees has a significant effect （the greater the difference, the faster the evacuation） for the evacuation under poor visibility conditions. Our study provides a new quantitative insight into the effect of spatial memory on crowd evacuation under poor visibility conditions.

关键词： crowd evacuation memory visibility social force model

Widely accessible method for 3D microflow mapping at high spatial and temporal resolutions

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Microsystems & Nanoengineering 2022年第4期8卷 57-71页

作者： Evan Lammertse Nikhil Koditala Martin Sauzade Hongxiao Li Qiang Li Luc Anis Jun kong eric Brouzes Department of Biomedical Engineering Stony Brook UniversityStony BrookNY 11794USA Department of Mathematics and Statistics Department of Computer ScienceGeorgia State UniversityAtlantaGA 30302USA Laufer Center for Physical and Quantitative Biology Stony Brook UniversityStony BrookNY 11794USA Cancer Center Stony Brook School of MedicineStony BrookNY 11794USA Institute for Engineering Driven Medicine Stony Brook UniversityStony BrookNY 11794USA

Advances in microfluidic technologies rely on engineered 3D flow patterns to manipulate samples at the ***,current methods for mapping flows only provide limited 3D and temporal resolutions or require highly specialized optical ***,we present a simple defocusing approach based on brightfield microscopy and open-source software to map micro-flows in 3D at high spatial and temporal *** workflow is both integrated in ImageJ and *** track seed particles in 2D before classifying their Z-position using a reference *** compare the performance of a traditional cross-correlation method and a deep learning model in performing the classification *** validate our method on three highly relevant microfluidic examples:a channel step expansion and displacement structures as single-phase flow examples,and droplet microfluidics as a twophase flow ***,we elucidate how displacement structures efficiently shift large particles across ***,we reveal novel recirculation structures and folding patterns in the internal flow of microfluidic *** simple and widely accessible brightfield technique generates high-resolution flow maps and it will address the increasing demand for controlling fluids at the microscale by supporting the efficient design of novel microfluidic structures.

关键词： flow resolution method

VOWEL DISPERSION AND VARIABILITY—DATA FROM THREE CHINESE DIALECTS

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中国语音学报 2013年第1期 143-152页

作者： LEE wai-Sum ZEE eric Department of Chinese Translation and LinguisticsCity University of Hong Kong

The study^1 investigates dispersion and variability of the vowels of three Chinese dialects,namely Yongding,Cantonese,and Wenling with the three-,seven-,and eleven-vowel systems,*** of formant frequencies were obtained through spectral analysis of speech data from ten male and ten female speakers of each dialect Results show that a larger vowel inventory correlates a more expanded acoustical vowel space for the three Chinese dialects,which supports the prediction of the vowel dispersion theory that the larger the vowel inventory is,the more expanded vowel space will ***,the difference in vowel space is not linearly related to the difference in vowel inventory ***,the vowel dispersion theory’s prediction that variability in vowel formant frequencies is inversely related to vowel inventory size is not supported by the vowel formant data from the three Chinese dialects.

关键词： Vowel dispersion and variability Formant frequencies Acoustical vowel space Vowel inventory size Chinese dialects

Study on single-group dynamics in evacuation considering pre-defined and undeclared leadership

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Journal of Safety Science and Resilience 2023年第1期4卷 52-60页

作者： Wei Xie Dongli Gao Ruifeng Cao eric wai Ming Lee Richard Kwok Kit Yuen Jingwen Weng Department of Architecture and Civil Engineering City University of Hong KongKowloon TongHong KongChina State Key Laboratory of Fire Science University of Science and Technology of ChinaHefei 230026China

Grouping is a common phenomenon that occurs *** leader-follower relationship inside groups has often been qualitatively characterized in previous models using simple ***,a general method is lacking to quantitatively explain leadership in an evacuating *** understand the evolution of single-group dynamics throughout an evacuation,we developed an extended social force model integrated with a group force.A series of single-group evacuations from a room were *** information-theoretic method,transfer entropy(TE),was applied to detect predefined and undeclared leadership among *** results showed that the predefined leader was correctly detected by TE,suggesting its capability in measuring leadership based on time series of evacuees’movement information(e.g.,velocity and acceleration).When evacuees were grouped together,TE was higher than when they were *** presented a monotonically increasing cumulative influence curve over the investigated period,whereas followers showed a diminishing *** found that leadership emergence correlated with evacuees’spatial *** individual located in the foremost part of the group was most likely to become a leader of those in the rear,which concurred with the experimental *** observed how a large group split into smaller ones with undeclared leadership during *** observations were quantitatively verified by TE *** study provides novel insights into quantifying leadership and understanding single-group dynamics during evacuations.

关键词： Evacuation Social force model Group behavior Leadership Transfer entropy

The prediction of exit choice using cumulative prospect value

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Journal of Safety Science and Resilience 2023年第1期4卷 20-25页

作者： Dongli Gao Wei Xie Ruifeng Cao eric wai Ming Lee Richard Kwok Kit Yuen Jingwen Weng Department of Architecture and Civil Engineering City University of Hong KongHong KongChina State Key Laboratory of Fire Science University of Science and Technology of ChinaHefei230026China

Exit choice is essential for pedestrian safety and evacuation efficiency during the context of an emergency. Cumulative prospect theory is a widespread realistic decision-making theory that can transform choice outcomes and probabilities into subjective terms and integrate them as a parameter of cumulative prospect value (CPV), which determines the decision. The main contribution of this paper is the use of the CPV to predict exit choice. Furthermore, the different decision-making rules including Max, exponential(Expo), and Ratio (i.e., the three variable choice functions) were summarized and examined. This study used a confusion matrix to compare the predicted results with experimental data. Consequently, the parameters of Accuracy and F1-score showed that the predictions from Max and Expo were significantly more realistic while the results from Ratio were much more robust.

关键词： Decision-making behavior Exit choice Evacuation model Cumulative prospect value