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Microcurvature landscapes induce neural stem cell polarity and enhance neural differentiation

生物设计与制造(英文) 2023年第5期6卷 522-535页

作者： Ho-Yin Yuen Wai-Sze Yip suet to Xin Zhao Department of Biomedical Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong Kong SARChina State Key Laboratory of Ultra-Precision Machining Technology Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HomKowloonHong Kong SARChina

Tissue curvature has long been recognized as an important anatomical parameter that affects intracellular behaviors,and there is emerging interest in applying cell-scale curvature as a designer property to drive cell fates for tissue engineering purposes.Although neural cells are known to undergo dramatic and terminal morphological changes during development and curvature-limiting behaviors have been demonstrated in neurite outgrowth studies,there are still crucial gaps in understanding neural cell behaviors,particularly in the context of a three-dimensional(3D)curvature landscape similar to an actual tissue engineering scaffold.In this study,we fabricated two substrates of microcurvature(curvature-substrates)that present a smooth and repeating landscape with focuses of either a concave or a convex pattern.Using these curvature-substrates,we studied the properties of morphological differentiation in N2a neuroblastoma cells.In contrast to other studies where two-dimensional(2D)curvature was demonstrated to limit neurite outgrowth,we found that both the concave and convex substrates acted as continuous and uniform mechanical protrusions that significantly enhanced neural polarity and differentiation with few morphological changes in the main cell body.This enhanced differentiation was manifested in various properties,including increased neurite length,increased nuclear displacement,and upregulation of various neural markers.By demonstrating how the micron-scale curvature landscape induces neuronal polarity,we provide further insights into the design of biomaterials utilizing the influence of surface curvature in neural tissue engineering.

关键词： Curvature Neural differentiation Neurite outgrowth Mechanotransduction

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Generating micro/nanostructures on magnesium alloy surface using ultraprecision diamond surface texturing process

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Journal of Magnesium and Alloys 2023年第4期11卷 1472-1483页

作者： Hanheng Du Mengnan Jiang Zuankai Wang Zhiwei Zhu suet to State Key Laboratory of Ultra-Precision Machining Technology Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHong KongChina Department of Mechanical Engineering City University of Hong KongHong KongChina School of Mechanical Engineering Nanjing University of Science and TechnologyNanjingChina

The lightness and high strength-to-weight ratio of the magnesium alloy have attracted more interest in various applications.However,micro/nanostructure generation on their surfaces remains a challenge due to the flammability and ignition.Motivated by this,this study proposed a machining process,named the ultraprecision diamond surface texturing process,to machine the micro/nanostructures on magnesium alloy surfaces.Experimental results showed the various microstructures and sawtooth-shaped nanostructures were successfully generated on the AZ31B magnesium alloy surfaces,demonstrating the effectiveness of this proposed machining process.Furthermore,sawtooth-shaped nanostructures had the function of inducing the optical effect and generating different colors on workpiece surfaces.The colorful letter and colorful flower image were clearly viewed on magnesium alloy surfaces.The corresponding cutting force,chip morphology,and tool wear were systematically investigated to understand the machining mechanism of micro/nanostructures on magnesium alloy surfaces.The proposed machining process can further improve the performances of the magnesium alloy and extend its functions to other fields,such as optics.

关键词： Magnesium alloy Micro/nanostructure Ultraprecision diamond surface texturing Cutting force Chip morphology Structural color

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Hydrogen Ion Implantation Induced Cutting Behavior Variation in Plunge Cutting of the Monocrystalline Silicon

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Nanomanufacturing and Metrology 2021年第4期4卷 209-215页

作者： Zejia Zhao E.V.Jelenkovic Gaobo Xiao Zhuoxuan Zhuang suet to Institute of Semiconductor Manufacturing Research College of Mechatronics and Control EngineeringShenzhen UniversityNan-hai Ave 3688Shenzhen 518060GuangdongPeople’s Republic of China State Key Laboratory of Ultra-precision Machining Technology Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HornKowloonHong Kong SARPeople’s Republic of China Zhuhai Bojay Electronics Co. Ltd10 Futian RdXiangzhou DistrictZhuhai.GuangdongPeople’s Republic of China

In this study,surface modification of monocrystalline silicon with two doses of hydrogen ion implantation and the plunge cutting process were conducted to explore the influence of hydrogen ions on the cutting behavior of silicon.The results show that ion implantation is capable of deteriorating or improving the machinability of silicon,depending on the implantation dose.More cleavages and a reduction of critical depth of cut(CDoC)were observed for the silicon with a low implantation dose in the cutting direction ofin comparison to bare silicon,while no cleavage and an increase of CDoC were achieved after implantation with a high dose in the same cutting direction.Besides,the ductile cutting and thrust forces of the silicon with the low dose are larger than the bare silicon,but the forces are significantly reduced for the silicon after the high dose of implantation.The variation of the cutting forces is due to the different required stresses to overcome ductile and fracture deformation of silicon.

关键词： Hydrogen ion implantation Plunge cutting Silicon Critical depth of cut Cutting forces

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Expert insights on Malaysia’s residential solar-energy policies:shortcomings and recommendations

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Clean Energy 2022年第4期6卷 619-631页

作者： Lin-Sea Lau Yuen-Onn Choong suet-Ling Ching Chooi-Yi Wei Abdelhak Senadjki Chee-Keong Choong Ai-Na Seow Faculty of Business and Finance Universiti Tunku Abdul RahmanMalaysia

Malaysia has a long way before achieving the 20%renewable-energy penetration by 2025.Currently,merely 2%of the country’s electricity is generated by renewable energy sources including solar power.Unlike the abundant literature about solar energy,qualitative studies that focus on experts’opinions on the weaknesses of residential solar-energy policies have received less attention,particularly in the context of Malaysia.Understanding the flaws in the existing policies would lead to creating a better policy framework for solar-energy development.Thus,this study aims to identify the shortcomings of the current government initiatives and policies that deter solar photovoltaic adoption among households from experts’perspectives.Experts also provide recommendations for better future policy design and implementation.This study employs a qualitative research approach(via semi-structured interviews)in collecting experts’viewpoints.Key concerns emerging from the interviews include insufficient financial support,lack of awareness programmes and subsidized electricity tariffs.Also,interviewed experts suggest sufficient financial incentives,increased public awareness programmes and comprehensive legislation aimed at safeguarding consumer interests as a means to raising solar-energy adoption in the country.This underlines the need for policymakers to create public awareness,provide financial support and develop regulatory measures aimed at managing solar companies for the sake of solar development in Malaysia.

关键词： qualitative study interview expert insights solar energy households policy shortcomings policy recommendations

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A Machine Learning Approach: Enhancing the Predictive Performance of Pharmaceutical Stock Price Movement during COVID

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Journal of Data Analysis and Information Processing 2022年第1期10卷 1-21页

作者： Beilei He Weiyi Han suet Ying Isabelle Hon Jacobs School of Engineering University of California San Diego San Diego USA Xiaohongshu Inc. Shanghai China Centre of Industrial Relations and Human Resources University of Toronto (St. George) Toronto Canada

Predicting stock price movement direction is a challenging problem influenced by different factors and capricious events. The conventional stock price prediction machine learning models heavily rely on the internal financial features, especially the stock price history. However, there are many outside-of-company features that deeply interact with the companies’ stock price performance, especially during the COVID period. In this study, we selected 9 COVID vaccine companies and collected their relevant features over the past 20 months. We added handcrafted external information, including COVID-related statistics and company-specific vaccine progress information. We implemented, evaluated, and compared several machine learning models, including Multilayer Perceptron Neural Networks with logistic regression and decision trees with boosting and bagging algorithms. The results suggest that the application of feature engineering and data mining techniques can effectively enhance the performance of models predicting stock price movement during the COVID period. The results show that COVID-related handcrafted features help to increase the model prediction accuracy by 7.3% and AUROC by 6.5% on average. Further exploration showed that with data selection the decision tree model with gradient, boosting algorithm achieved 70% in AUROC and 66% in the accuracy.

关键词： Machine Learning Stock Price Trend Prediction Feature Engineering

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Impacts of wetting-drying cycles on short-term carbon and nitrogen dynamics in Amynthas earthworm casts

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Pedosphere 2021年第3期31卷 423-432页

作者： Michelle Man suet LAW Derrick Yuk Fo LAI Department of Geography and Resource Management The Chinese University of Hong KongShatinNew TerritoriesHong Kong SARChina Department of Biology Hong Kong Baptist UniversityKowloon TongKowloonHong Kong SARChina Centre for Environmental Policy and Resource Management The Chinese University of Hong KongShatinNew TerritoriesHong Kong SARChina

Effects of earthworm casts on soil nutrient dynamics and their responses to changing moisture availability in subtropical ecosystems remain poorly understood.This study aimed to examine short-term carbon(C)and nitrogen(N)dynamics and their interactions with wetting-drying cycles in three different structural forms(i.e.,granular,globular,and heap-like)of Amynthas earthworm casts.The rates of C and N mineralization in the earthworm casts were examined under two different wetting-drying cycles(i.e.,2-d and 4-d wetting intervals)using a rainfall simulation experiment.After three simulated rainfall events,subsamples of the earthworm casts were further incubated for 4 d for the determination of CO2 and N2O fluxes.The results of this study indicated that the impacts of wetting-drying cycles on the short-term C and N dynamics were highly variable among the three cast forms,but wetting-drying cycles significantly reduced the cumulative CO2 and N2O fluxes by 62%-83%and 57%-85%,respectively,when compared to the control without being subjected to any rainfall events.The C mineralization rates in different cast forms were affected by the amount of organic substrates and N content in casts,which were associated with the food preference and selection of earthworms.Meanwhile,the cumulative N2O fluxes did not differ among the three cast forms.Repeated wetting and drying of casts not only enhanced aggregate stability by promoting bonds between the cast particles,but also inhibited microbial survival and growth during the prolonged drying period,which together hindered decomposition and denitrification.Our findings demonstrated that the interactions between the structural forms,aggregate dynamics,and C and N cycling in the earthworm casts were highly complex.

关键词： aggregate stability Cand N cycling earthworm activity earthworm casting greenhouse gas flux mineralization organic matter rainfall simulation

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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

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Escitalopram-induced liver injury: A case report and review of literature

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World Journal of Hepatology 2019年第10期11卷 719-724页

作者： Qin Xiang Ng Christl suet Kwan Yong Wayren Loke Wee Song Yeo Alex Yu Sen Soh Institute of Mental Health Buangkok Green Medical ParkSingapore 539747Singapore MOH Holdings Pte Ltd Singapore 099253Singapore National University Hospital National University Health SystemSingapore 119074Singapore Yong Loo Lin School of Medicine National University of SingaporeSingapore 117597Singapore

BACKGROUND Depression is a growing public health problem that affects over 350 million people globally and accounts for approximately 7.5%of healthy years lost due to disability.Escitalopram,one of the first-line medications for the treatment of depression,is a selective serotonin reuptake inhibitor and one of the most commonly prescribed antidepressant medications worldwide.Although thought to be generally safe and with minimal drug-drug interactions,we herein present an unusual case of cholestatic liver injury,likely secondary to escitalopram initiation.CASE SUMMARY A 56-year-old Chinese lady presented with fever and cholestatic liver injury two weeks after initiation of escitalopram for the treatment of psychotic depression.Physical examination was unremarkable.Further investigations,including a computed tomography scan of the abdomen and pelvis and tests for hepatitis A,B and C and for autoimmune liver disease were unyielding.Hence,a diagnosis of escitalopram-induced liver injury was made.Upon stopping escitalopram,repeat liver function tests showed downtrending liver enzymes with eventual normalization of serum aspartate aminotransferase and alanine aminotransferase one-week post-discharge.CONCLUSION Clinicians should be aware of the possibility of escitalopram-induced liver injury when initiating depressed patients on antidepressant treatment.This requires extra vigilance as most patients may remain asymptomatic.Measurement of liver function tests could be considered after initiation of antidepressant treatment,especially in patients with pre-existing liver disease.

关键词： Depression Antidepressant Escitalopram Liver injury Drug-induced Druginduced liver injury

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The TripleSat constellation:a new geospatial data service model

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Geo-Spatial Information Science 2017年第2期20卷 163-173页

作者： Qiang Wen Jianjun He Shengyong Guan Ting Chen Yin Hu Wenbin Wu Feng Liu Yuexia Qiao suet Yheng Kok Samuel Yeong 21st Century Aerospace Technology Co. Ltd.BeijingChina 21st Century Aerospace Technology(Asia)Pte.Ltd. Singapore

With the increase of different sensors,applications and customers,the demand from data providers and users is for a new geospatial data service model,which supports low cost,high dexterity,and which would provide a comprehensive service.Based on such requirements and demands,the 21AT TripleSat constellation terminal and data delivery and management system has been developed by a Beijing based high-tech enterprise,Twenty First Century Aerospace Technology Co.,Ltd.(21AT).The company is the first commercial Earth observation satellite operator and service provider in China.This new geospatial data service model allows the user to directly access multi-source satellite data,manage the data order,and carry out automatic massive data production and delivery.The solution also implements safe and hierarchical user management,statistical data analysis,and automatic information reports.In addition,a mobile application is also available for users to easily access system functions.This new geospatial solution has already been successfully applied and installed in many customer sites in China,and is now available globally for international clients interested in fast geospatial solutions.It enables the success of customers’operational services.Besides providing TripleSat Constellation images,the multi-source data access system also allows the users to access other satellite data sources,based on customized agreement.This paper describes and discusses this new geospatial data service model.

关键词： Geospatial data service model 21AT TripleSat constellation geospatial instant service system

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Echocardiographic mapping of left ventricular resynchronization during cardiac resynchronization therapy procedures

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Chinese Medical Journal 2010年第13期123卷 1645-1651页

作者： CHAN Ngai-yin CHOY Chi-chung CHEUNG Kar-chun LAU Chun-leung LO Ying-keung CHU Pui-shan YUEN Ho-chuen LAU suet-ting CHOI Yuen-choi Department of Medicine & Geriatrics Princess Margaret Hospital 2-10 Princess Margaret Hospital Road Lai Chi Kok Kowloon Hong Kong China

Background Cardiac resynchronization therapy （CRT） is an effective electrical therapy for patients with moderate to severe heart failure and cardiac dyssynchrony. This study aimed to investigate the degree of acute left ventricular （LV） resynchronization with biventricular pacing （BVP） at different LV sites and to examine the feasibility of performing transthoracic echocardiography （TTE） to quantify acute LV resynchronization during CRT procedure. Methods Fourteen patients with NYHA Class Ⅲ-Ⅳ heart failure, LV ejection fraction 〈35%, QRS duration 〉120 ms and septal-lateral delay （SLD）〉60 ms on tissue Doppler imaging （TDI）, underwent CRT implant. TDI was obtained from three apical views during BVP at each accessible LV site and SLD during BVP was derived. Synchronicity gain index （Sg） by SLD was defined as （I＋（SLD at baseline - SLD at BVP）/SLD at baseline）. Results Seventy-two sites were studied. Positive resynchronization （R＋, Sg〉1） was found in 42 （58%） sites. R＋ was more likely in posterior or lateral than anterior LV sites （66% vs. 36%, P 〈0.001）. Concordance of empirical LV lead implantation sites and sites with R＋ was 50% （7/14）. Conclusions The degree of acute LV resynchronizaUon by BVP depends on LV lead location and empirical implantation of LV lead results in only 50% concordance with R＋. Performing l-rE during CRT implantation is feasible to identify LV sites with positive resynchronization.

关键词： echocardiography cardiac resynchronization therapy heart failure left ventricular lead device implantation optimization

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