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Majorana fermions in semiconducting nanowire and Fulde–Ferrell superconductor hybrid structures

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Frontiers of physics 2019年第1期14卷 147-154页

作者： Jia Liu Chun fai chan Ming Gong Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials and School of Physics and Telecommunication Engineering South China Normal University Guangzhou 510006 China Department of Physics and Center of Coherence The Chinese University of Hong Kong Shatin N. T. Hong Kong China Key Laboratory of Quantum Information University of Science and Technology of China Hefei 230026 China Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials and School of Physics and Telecommunication Engineering South China Normal University Guangzhou 510006 China

The novel idea that spin-orbit coupling (SOC) and an s-wave pairing system can lead to induced pwave pairing with a strong magnetic limit, has stimulated widespread interest in searching for Majorana fermions (MFs) in semiconductor-superconductor hybrid structures. However, despite major advances in the semiconductor nanotechnology, this system has several inherent limitations that prohibit the realization and identification of MFs. We overcome these limitations by replacing the s-wave superconductor with the type-II Fulde-Ferrell (FF) superconductor, in which the center-of-mass momentum of the Cooper pair renormalizes the in-plane Zeeman field and chemical potential. As a result, MFs can be realized in semiconductor nanowires with small values of the Landé g-factor and high carrier densities. The SOC strength directly influences the topological boundary;thus, the topological phase transition and associated MFs can be engineered by an external electric field. Theoretically, almost all semiconductor nanowires can be used to realize MFs by using the FF superconductor. However, we find that InP nanowire is more suitable for the realization of MFs compared to InAs and InSb nanowires. Thus, this new scheme can take full advantage of the semiconductor nanotechnology for the realization of MFs in semiconductor-superconductor hybrid structures.

关键词： Majorana fermion topological transition Pfaffian FF-superconductor hybrid structure

Can microfluidics address biomanufacturing challenges in drug/gene/cell therapies?

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Regenerative Biomaterials 2016年第2期3卷 87-98页

作者： Hon fai chan Siying Ma Kam W.Leong Department of Biomedical Engineering Department of Systems BiologyColumbia UniversityNew YorkNY 10032USA

Translation of any inventions into products requires *** of drug/gene/cell delivery systems will eventually face manufacturing challenges,which require the establishment of standardized processes to produce biologically-relevant products of high quality without incurring prohibitive *** technologies present many advantages to improve the quality of drug/gene/cell delivery *** also offer the benefits of *** remains unclear is whether they can meet the scale-up *** this perspective,we discuss the advantages of microfluidic-assisted synthesis of nanoscale drug/gene delivery systems,formation of microscale drug/cell-encapsulated particles,generation of genetically engineered cells and fabrication of macroscale drug/cell-loaded micro-/*** also highlight the scale-up challenges one would face in adopting microfluidic technologies for the manufacturing of these therapeutic delivery systems.

关键词： microfluidics biomanufacturing nanoparticle microencapsulation microfiber

Immunomodulation by mesenchymal stem cells:Interplay between mesenchymal stem cells and regulatory lymphocytes

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World Journal of Stem Cells 2016年第9期8卷 268-278页

作者： Oscar Ka-fai Ma Koon Ho chan Department of Medicine Li Ka Shing Faculty of Medicine the University of Hong Kong

Mesenchymal stem cells(MSCs) possess immunomodulatory properties, which confer enormous potential for clinical application. Considerable evidence revealed their efficacy on various animal models of autoimmune diseases, such as multiple sclerosis, systemic lupus erythematosus and uveitis. MSCs elicit their immunomodulatory effects by inhibiting lymphocyte activation and proliferation, forbidding the secretion of proinflammatory cytokines, limiting the function of antigen presenting cells, and inducing regulatory T(Treg) and B(Breg) cells. The induction of Treg and Breg cells is of particular interest since Treg and Breg cells have significant roles in maintaining immune tolerance. Several mechanisms have been proposed regarding to the MSCs-mediated induction of Treg and Breg cells. Accordingly, MSCs induce regulatory lymphocytes through secretion of multiple pleiotropic cytokines, cell-to-cell contact with target cells and modulation of antigen-presenting cells. Here, we summarized how MSCs induce Treg and Breg cells to provoke immunosuppression.

关键词： Mesenchymal stem cells Regulatory T cells Regulatory B cells Immunomodulation Autoimmunity

Large-area perovskite films for PV applications:A perspective from nucleation and crystallization

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Journal of Energy Chemistry 2021年第8期30卷 626-641,I0013页

作者： Yuanhang Yang Zexu Xue Long Chen cho fai Jonathan Lau Zhiping Wang Key Lab of Artificial Micro-and Nano-Structures of Ministry of Education of China School of Physics and TechnologyWuhan UniversityWuhan 430072China Canadian Solar Inc. Suzhou 215129China School of Microelectronics Wuhan UniversityWuhan 430072China

Perovskite solar cells(PSCs)have attracted significant research interest due to the rapid rise in ***,a large efficiency gap still exists between laboratory-based small devices and industrialoriented large-scale *** of the main reasons for the efficiency losses is the degraded quality and morphology of the deposited large-area films,which is closely associated with crystallization *** this review,we discuss the nucleation and crystallization processes in solution and vaporbased up-scaling deposition methods for large-area perovskite *** review recent scientific achievements and technical developments that have been made in the field of large-area *** present the existing problems that limit the performance of large devices and extensively discuss the key influencing parameters from the perspective of nucleation and crystallization over large *** review highlights the importance of crystallization control in up-scaling fabrications and presents promising strategies towards large-area perovskite-based optoelectronic devices.

关键词： Large area Perovskite solar cells Nucleation Crystallization Solution and vacuum processes

Mesoplasticity Approach to Studies of the Cutting Mechanism in Ultra-precision Machining

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Chinese Journal of Mechanical Engineering 2014年第2期27卷 219-228页

作者： LEE WB Rongbin WANG Hao TO Suet CHEUNG Chi fai chan chang Yuen Partner State Key Laboratory of Ultra-precision Machining Technology The Hong Kong Polytechnic University

There have been various theoretical attempts by researchers worldwide to link up different scales of plasticity studies from the nano-, micro- and macro-scale of observation, based on molecular dynamics, crystal plasticity and continuum mechanics. Very few attempts, however, have been reported in ultra-precision machining studies. A mesoplasticity approach advocated by Lee and Yang is adopted by the authors and is successfully applied to studies of the micro-cutting mechanisms in ultra-precision machining. Traditionally, the shear angle in metal cutting, as well as the cutting force variation, can only be determined from cutting tests. In the pioneering work of the authors, the use of mesoplasticity theory enables prediction of the fluctuation of the shear angle and micro-cutting force, shear band formation, chip morphology in diamond turning and size effect in nano-indentation. These findings are verified by experiments. The mesoplasticity formulation opens up a new direction of studies to enable how the plastic behaviour of materials and their constitutive representations in deformation processing, such as machining can be predicted, assessed and deduced from the basic properties of the materials measurable at the microscale.

关键词： ultra-precision machining cutting mechanism mesoplasticity shear angle prediction size effect,micro-cutting force variation high frequency tool-tip vibration

Simple black holes with anisotropic fluid

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Chinese Physics C 2019年第2期43卷 125-131页

作者： Inyong cho Hyeong-chan Kim School of Liberal Arts Seoul National University of Science and Technology School of Liberal Arts and Sciences Korea National University of Transportation

We study a spherically symmetric spacetime made of an anisotropic fluid whose radial equation-of-state is given by p_1=-ρ. This case allows analytic solutions and is a good example for studying the static configuration of a black hole plus matter. For a given equation-of-state parameter w_2 = p_2/ρ for angular directions, we find the exact solutions of the Einstein equation described by two parameters. We classify the solutions into six types based on the behavior of the metric function. Depending on the parameters, the solutions can have event and cosmological horizons. One of the solution types corresponds to a generalization of the Reissner-Nordstr(o|¨)m black hole, the thermodynamic properties for which are obtained in a simple form. The solutions are stable under radial perturbations.

关键词： black hole exact solution general relativity

Late retroperitoneal recurrence of hepatocellular carcinoma 12 years after initial diagnosis

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World Journal of Gastroenterology 2010年第17期16卷 2187-2189页

作者： Tiffany cho-Lam Wong Ka-fai To Simon See-Ming Hou Sidney Kam-Hung Yip Chi-fai Ng Department of Surgery Prince of Wales HospitalThe Chinese University of Hong Kong Department of Anatomical and Cellular Pathology The Chinese University of Hong Kong

Hepatocellular carcinoma (HCC) is an aggressive tumor with poor long-term ***,we present an unusual patient with a solitary recurrence of HCC in the right kidney 12 years after the initial *** illustrates the importan... 详细信息

关键词： Hepatocellular carcinoma Late recurrence Metastasis Retroperitoneal

Potential role of Lycium barbarum polysaccharides in glaucoma management:evidence from preclinical in vivo studies

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Neural Regeneration Research 2023年第12期18卷 2623-2632页

作者： Yamunadevi Lakshmanan Francisca Siu Yin Wong Kwok-fai So Henry Ho-Lung chan Centre for Eye and Vision Research(CEVR) 17W Hong Kong Science ParkHong Kong Special Administrative RegionChina Guangdong-Hongkong-Macao(GHM)Institute of CNS Regeneration Jinan UniversityGuangzhouGuangdong ProvinceChina Department of Ophthalmology LKS Faculty of MedicineThe University of Hong KongHong Kong Special Administrative RegionChina Laboratory of Experimental Optometry(Neuroscience) School of OptometryThe Hong Kong Polytechnic UniversityHong Kong Special Administrative RegionChina Research Centre for SHARP Vision(RCSV) The Hong Kong Polytechnic UniversityHong Kong Special Administrative RegionChina University Research Facilities in Behavioral and Systems Neuroscience(UBSN) The Hong Kong Polytechnic UniversityHong Kong Special Administrative RegionChina

In recent years,the pharmacological benefits of herbal extracts have been revisited for their potential neuroprotective effects in *** polysaccharides extracted from the fruits of Lycium barbarum L.,or Lycium barbarum polysaccharides,exert their anti-aging effect through reducing oxidative stress,modulating the immune response,enhancing neuronal responses,and promoting *** therapeutic efficacy of Lycium barbarum polysaccharides in preserving retinal ganglion cells and their functions was demonstrated in a range of experimental models of optic *** include the acute and chronic ocular hypertension models,the partial optic nerve transection model,and the ischemic-reperfusion injuries *** on these findings,Lycium barbarum polysaccharides appear to be a good candidate to be developed as a neuroprotective agent for treating multifactorial *** review aims to present a comprehensive review on the latest preclinical evidence on the pre-and post-treatment benefits of Lycium barbarum polysaccharides in retinal ganglion cell *** possible mechanisms of Lycium barbarum polysaccharides mediating retinal ganglion cell neuroprotection will also be ***,the potential research gaps in the effective translation of Lycium barbarum polysaccharides treatment into clinical glaucoma management will be discussed.

关键词： animal model complementary and alternative medicine glaucoma retinal ganglion cell Lycium barbarum polysaccharide neuroprotection neuro-rescue ocular hypertension post-treatment pre-treatment

Porous FeS nanofibers with numerous nanovoids obtained by Kirkendall diffusion effect for use as anode materials for sodium-ion batteries

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Nano Research 2017年第3期10卷 897-907页

作者： Jung Sang cho Jin-Sung Park Yun chan Kang Department of Materials Science and Engineering Korea University Anam-Dong Seongbuk-Gu Seou1136-713 Republic of Korea Department of Engineering Chemistry Chungbuk National University Chungbuk 361-763 Republic of Korea

Porous FeS nanofibers with numerous nanovoids for use as anode materials for sodium-ion batteries were prepared by electrospinning and subsequent sulfidation. The post-treatment of the as-spun Fe（acac）3-polyacrylonitrile composite nanofibers in an air atmosphere yielded hollow Fe2O3 nanofibers due to Ostwald ripening. The ultrafine Fe2O3 nanocrystals formed at the center of the fiber diffused toward the outside of the fiber via Ostwald ripening. On sulfidation, the Fe2O3 hollow nanofibers were transformed into porous FeS nanofibers, which contained numerous nanovoids. The formation of porosity in the FeS nanofibers was driven by nanoscale Kirkendall diffusion. The porous FeS nanofibers were very structurally stable and had superior sodium-ion storage properties compared with the hollow Fe2O3 nanofibers. The discharge capacities of the porous FeS nanofibers for the Ist and 150th cycles at a current density of 500 mA.g-1 were 561 and 592 mA.h-g-1, respectively. The FeS nanofibers had final discharge capacities of 456, 437, 413, 394, 380, and 353 mA-h.g-1 at current densities of 0.2, 0.5, 1.0, 2.0, 3.0, and 5.0 A.g-1, respectively.

关键词： iron sulfide sodium-ion batteries Kirkendall effect nanofibers electrospinning