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Additive manufacturing of composite materials and functionally graded structures using selective heat melting technique

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Journal of Materials Science & Technology 2020年第12期47卷 243-252页

作者： Kalaimani Markandan Ruijing Lim Pawan Kumar Kanaujia Ian Seetoh Muhammad Raziq bin Mohd Rosdi Zhi Huey Tey Jun Seng Goh yee cheong lam Changquan Lai Temasek Laboratories Nanyang Technological University50 Nanyang Drive637553Singapore School of Physical&Mathematical Sciences Nanyang Technological University21 Nanyang Link637371Singapore School of Mechanical&Aerospace Engineering Nanyang Technological University50 Nanyang Avenue639798Singapore School of Materials Science&Engineering Nanyang Technological University50 Nanyang Avenue639798Singapore

The feasibility of using selective heat melting(SHM) to fabricate composite materials and functionally graded structures was *** report,for the first time,the successful 3 D printing of copper(Cu)-polyethylene(PE) composite,iron(Fe)-polyethylene(PE) composite and functionally graded CuO foams using the SHM *** was found that a low feed rate,high airflow rate and high airflow temperature were required for efficient delivery of heat from the emitted hot air to the powder bed,so that the PE binder particles can melt and form dense composites with smooth *** best mechanical properties were exhibited by composites with 80 vol.% PE,as lower PE concentrations led to deficient binding of the metal particles,while higher PE concentrations meant that very few metal particles were available to strengthen the *** strength exhibited by Cu-PE composites was comparable to engineering plastics such as polycarbonate,with the added advantage of being electrically *** average conductivity of the samples,0.152±0.28 S/m,was on par with physically crosslinked graphene *** subjecting a Cu-PE composite,with Cu concentration graded from 10 vol.% to 30 vol.%,to a high temperature debinding and sintering treatment in air,CuO foam with graded porosity can be *** CuO foam was observed to fail in a layer-by-layer manner under mechanical compression,which is a characteristic of functionally graded *** study shows that,compared to existing 3 D printing techniques,SHM can be cheaper,have wider material compatibility,occupy a smaller footprint and potentially induce less residual stresses in the fabricated ***,it could be a valuable complement to current additive manufacturing techniques for fabricating mechanically strong composite materials and functionally graded structures.

关键词： Selective heat melting Functionally graded materials Additive manufacturing Multimaterial

Picosecond Laser Surface Texturing of a Stavax Steel Substrate for Wettability Control

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Engineering 2018年第6期4卷 816-821页

作者： Xincai Wang Hongyu Zheng Yinchi Wan Wenhe Feng yee cheong lam Singapore Institute of Manufacturing Technology(SIMTech) A*STARSingapore 138634Singapore SIMTech-NTU Joint Laboratory(Precision Machining) Nanyang Technological UniversitySingapore 639798Singapore School of Mechanical Engineering Shandong University of TechnologyZibo 255000China

In this investigation,a picosecond laser was employed to fabricate surface textures on a Stavax steel substrate,which is a key material for mold fabrication in the manufacturing of various polymer *** main types of surface textures were fabricated on a Stavax steel substrate:periodic ripples,a two-scale hierarchical two-dimensional array of micro-bumps,and a micro-pits array with *** wettability of the laser-textured Stavax steel surface was converted from its original hydrophilicity into hydrophobicity and even super-hydrophobicity after exposure to *** results clearly show that this super-hydrophobicity is mainly due to the surface *** ultrafast laserinduced catalytic effect may play a secondary role in modifying the surface chemistry so as to lower the surface *** laser-induced surface textures on the metal mold substrates were then replicated onto polypropylene substrates via the polymer injection molding *** surface wettability of the molded polypropylene was found to be changed from the original hydrophilicity to *** developed process holds the potential to improve the performance of fabricated plastic products in terms of wettability control and easy cleaning.

关键词： Picosecond laser Surface texturing Stavax steel Polymer Hydrophobicity

Tapered optical fiber DNA biosensor for detecting Leptospira DNA

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Asian Pacific Journal of Tropical Medicine 2023年第3期16卷 119-128页

作者： Jia-Yong lam Mohd Hanif Yaacob Hui-yee Chee Department of Medical Microbiology Faculty of Medicine and Health SciencesUniversiti Putra Malaysia43400 UPM SerdangSelangorMalaysia Department of Computer and Communication Systems Engineering Faculty of EngineeringUniversiti Putra Malaysia43400 UPM SerdangSelangorMalaysia Wireless and Photonics Networks Research Centre(WiPNET) Universiti Putra Malaysia43400 UPM SerdangSelangorMalaysia

Objective: To establish a DNA detection platform based on a tapered optical fiber to detect Leptospira DNA by targeting the leptospiral secY ***: The biosensor works on the principle of light propagating in the special geometry of the optical fiber tapered from a waist diameter of 125 to 12 μm. The fiber surface was functionalized through a cascade of chemical treatments and the immobilization of a DNA capture probe targeting the secY gene. The presence of the target DNA was determined from the wavelength shift in the optical transmission ***: The biosensor demonstrated good sensitivity, detecting Leptospira DNA at 0.001 ng/μL, and was selective for Leptospira DNA without cross-reactivity with non-leptospiral microorganisms. The biosensor specifically detected DNA that was specifically amplified through the loop-mediated isothermal amplification ***: These findings warrant the potential of this platform to be developed as a novel alternative approach to diagnose leptospirosis.

关键词： DNA biosensor Tapered optical fiber Leptospirosis Leptospira

Novel role of STAT3 in microglia-dependent neuroinflammation after experimental subarachnoid haemorrhage

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Stroke & Vascular Neurology 2022年第1期7卷 62-70页

作者： Zhiyuan Vera Zheng Junfan Chen Hao Lyu Sin Yu Erica lam Gang Lu Wai yee Chan George K C Wong Department of Surgery The Chinese University of Hong KongShatinHong Kong Department of Surgery Hainan General HospitalHaikouHainanChina School of Biomedical Science The Chinese University of Hong KongShatinHong Kong

Background and purpose Signal transducer and activator of transcription 3(STAT3)may contribute to the proinflammation in the central nervous system diseases by modulating the microglial ***,this study was intended to investigate the effect of STAT3 on microglia-dependent neuroinflammation and functional outcome after experimental subarachnoid haemorrhage(SAH).Methods The SAH model was established by endovascular perforation in the ***-time PCR(RtPCR)and western blot were used to examine the dynamic STAT3 signalling pathway responses after *** clarify the role of the STAT3 signalling pathway in the microglia-dependent neuroinflammation after SAH,the microglia-specific STAT3 knockout(KO)mice were generated by the Cre-LoxP *** neurological functions were assessed by Catwalk and Morris water maze *** loss after SAH was determined by immunohistochemistry *** polarisation status after STAT3 KO was then examined by RtPCR and *** The STAT3 and Janus kinase-signal transducer 2 activated immediately with the upregulation and phosphorylation after *** factors and related mediators altered dynamically and *** STAT3 deletion ameliorated the neurological impairment and alleviated the early neuronal loss after *** investigate the underlying mechanism,we examined the microglial reaction after STAT3 ***3 deletion reversed the increase of microglia after *** of STAT3 triggered the early morphological changes of microglia and primed microglia from M1 to M2 ***,microglial STAT3 deletion suppressed the SAH-induced proinflammation and promoted the anti-inflammation in the early *** STAT3 is closely related to the microglial polarisation transition and modulation of microglia-dependent *** STAT3 deletion improved neurological function and neuronal survival probably through promoting M2 polarisation and anti-inf

关键词： STAT3 inflammation reversed

Association between the elderly frequent attender to the emergency department and 30-day mortality： A retrospective study over 10 years

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World Journal of Emergency Medicine 2018年第1期9卷 20-25页

作者： Yuzeng Shen yee Chien Tay Edward Wee Kwan Too Nan Liu Shao Wei lam Marcus Eng Hock Ong Department of Emergency Medicine Singapore General Hospital Singapore Department of Emergency Medicine Sengkang Health Singapore Business Analytics Program National University of Singapore Singapore Singhealth Health Selvices Research Centre Singapore

BACKGROUND: To determine if elderly frequent attenders are associated with increased 30-day mortality, assess resource utilization by the elderly frequent attenders and identify associated characteristics that contribute to mortality. METHODS: Retrospective observational study of electronic clinical records of all emergency department(ED) visits over a 10-year period to an urban tertiary general hospital in Singapore. Patients aged 65 years and older, with 3 or more visits within a calendar year were identified. Outcomes measured include 30-day mortality, admission rate, admission diagnosis and duration spent at ED. Chi-square-tests were used to assess categorical factors and Student t-test was used to assess continuous variables on their association with being a frequent attender. Univariate and multivariate logistic regressions were conducted on all significant independent factors on to the outcome variable(30-day mortality), to determine factor independent odds ratios of being a frequent ***: 1.381 million attendance records were analyzed. Elderly patients accounted for 25.5% of all attendances, of which 31.3% are frequent attenders. Their 30-day mortality rate increased from 4.0% in the first visit, to 8.8% in the third visit, peaking at 10.2% in the sixth visit. Factors associated with mortality include patients with neoplasms, ambulance utilization, male gender and having attended the ED the previous ***: Elderly attenders have a higher 30-day mortality risk compared to the overall ED population, with mortality risk more marked for frequent attenders. This study illustrates the importance and need for interventions to address frequent ED visits by the elderly, especially in an aging society.

关键词： Frequent attenders Elderly Emergency department Mortality

Techno-economic Analysis of Distributed Hydrogen Production from Natural Gas

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Chinese Journal of Chemical Engineering 2012年第3期20卷 489-496页

作者： LUK Ho Ting LEI Ho Man NG Wai yee lam Koon Fung Department of Chemical and Biomolecular Engineering the Hong Kong University of Science and TechnologyHong KongChina

It is well established that hydrogen has the potential to make a significant contribution to the world energy *** U.S.,majority of hydrogen production plants implement steam methane reforming(SMR) for centralized hydrogen ***,there is a wide lack of agreement on the nascent stage of using hydrogen as fuel in vehicles industry because of the difficulty in delivery and *** performing technological and economic analysis,this work aims to establish the most feasible hydrogen production pathway for automotives in near *** the evaluation,processes such as thermal cracking of ammonia and centralized hydrogen production followed by bulk delivery are eliminated while on-site steam reforming of methanol and natural gas are the most technologically feasible *** two processes are further evaluated by comprehensive economic *** results showed that the steam reforming(SR) of natural gas has a shorter payback time and a higher return on investment(ROI) and internal rate of return(IRR).Sensitivity analysis has also been constructed to evaluate the impact of variables like NG feedstock price,capital of investment and operating capacity factor on the overall production cost of *** on this study,natural gas is prompted to be the most economically and technologically available raw material for short-term hydrogen production before the transition to renewable energy source such as solar energy,biomass and wind power.

关键词： gas station cost analysis steam reforming ammonia cracking

Advances in fabricating spherical alginate hydrogels with controlled particle designs by ionotropic gelation as encapsulation systems

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Particuology 2016年第1期14卷 44-60页

作者： Jun-yee Leong Weng-Hoong lam Kiang-Wei Ho Wan-Ping Voo Micky Fu-Xiang Lee Hui-Peng Lim Swee-Lu Lim Beng-Ti Tey Denis Poncelet alan Lagoon Selatan Bandar Sunway Selangor 46150 Malaysia Advanced Engineering Platform Monash University Malaysia Jalan Lagoon Selatan Bandar Sunway Selangor 46150 Malaysia Oniris UMR CNRS 6144 GEPEA rue de la Geraudiere BP82225 Nantes 44322 France

Alginate is a biopolymer that has exceptional gelling properties, which allow easy gel formation under safe and mild conditions. Consequently, it is often used to encapsulate a variety of cargos, such as cells, enzymes, and lipids, and is typically employed as a model to study hydrogel-based encapsulation sys- tems. Since the first use of alginate in the encapsulation field in the 1970s, many methods have been developed to produce alginate hydrogel particles of different sizes, structures, and morphologies. This review provides an overview of the current progress in the fabrication of alginate hydrogels with vari- ous particle designs, including a discussion of dispersion techniques to pre-template alginate particles, gelation mechanisms, considerations in selecting suitable fabrication methods, and future directions.

关键词： Alginate lonotropic gelation Immobilization Encapsulation Hydrogel

Cultural adaptation and content validity of a Chinese translation of the‘Person-Centered Primary Care Measure’:findings from cognitive debriefing

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Family Medicine and Community Health 2020年第4期8卷 90-97页

作者： Emily Tsui yee Tse Cindy Lo Kuen lam Carlos King Ho Wong Weng yee Chin Rebecca S Etz Stephen J Zyzanski Kurt C Stange Department of Family Medicine and Primary Care Li Ka Shing Faculty of MedicineThe University of Hong KongHong Kong SARChina Department of Pharmacology and Pharmacy Li Ka Shing Faculty of MedicineThe University of Hong KongHong Kong SARChina Department of Family Medicine&Population Health Virginia Commonwealth University School of MedicineRichmondVirginiaUSA Center for Community Health Integration School of MedicineCase Western Reserve UniversityClevelandOhioUSA

Objectives To develop an equivalent Chinese translation of the Person-Centered Primary Care Measure(PCPCM)and to establish its cultural adaptability and content validity through cognitive *** The original English PCPCM was first translated into Chinese by double forward-translation by professional *** reconciliated Chinese version was then doubly back-translated into English by two other professional translators blinded to the *** affirmation on its linguistic equivalence with the developers of the original English PCPCM,the reconciliated Chinese PCPCM was sent for cognitive debriefing with 20 Chinese-speaking primary care subjects by a trained interviewer using structured probing questions to collect their opinions on the clarity,comprehensibility and relevance of each item and response option in the *** Subjects were invited from a primary care clinic in Hong Kong to undergo the cognitive debriefing *** interviews were divided into four groups chronologically to allow revision of the items to be made in *** Ten males and 10 females above the age of 18 completed the cognitive *** were all Cantonese-speaking Chinese recruited by convenience *** with cognitive impairment,could not read Chinese,too old or too sick to complete the interviews were excluded from the *** An average of 3.3 min(range 3-4 min)was required for the subjects to self-complete the *** items were generally perceived to be easily understood and *** were made to items with the content validity index(CVI)on clarity or understanding<0.8 in each round of the interviews or if a majority of the subjects suggested *** were made to two items in the Chinese PCPCM throughout the whole cognitive debriefing process before the final version was *** average CVI on clarity of the Chinese PCPCM items ranged from 0.75 to *** average CVI on un

关键词： translator interview validity

Effect of Rorrico, extracted from group of Chinese medicines, on influenza A and H1N1 infections

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Journal of Traditional Chinese Medicine 2016年第6期36卷 701-705页

作者： Shiu Hon Chui yee Hou Wong Ming Yiu Fong yee Man Chiu Christopher Wai Kei lam State Key Laboratory of Quality Research in Chinese Medicine Macao Institute for Applied Research in Medicine and Health Macao University of Science and Technology Clinical Laboratory Diagnostix Medical Center Central

OBJECTIVE: To investigate the therapeutic and preventive effects of Rorrico on influenza, especially influenza A viral infection, including swine flu(H1N1)in ***: Eighty-nine subjects were recruited in Hong Kong and Macao, and divided into treatment group(TG) and prevention group(PG) based on their influenza A and swine flu symptoms. All subjects were prescribed Rorrico or placebo, and monitored by a Chinese medicine practitioner. Blood samples were collected before and after 7-day Rorrico or placebo treatment for laboratory ***: After treatment, there were some full recoveries and obvious relief of onset symptoms in the TG. Blood test results showed that Rorrico produced(a) no adverse effects on subjects' renal andliver functions, muscle enzyme and hematological status,(b) no up-regulation of pro-inflammatory cytokines tumour necrosis factor-a and interleukin-18 in both TG and PG,(c) mild yet statistically significant elevation of plasma mannose-binding lectin(MBL) in ***: Rorrico has no up-regulating effect on the participants' immune response, or, equally likely, the immuno-modulatory effects of Rorrico do not non-specifically or unnecessarily promote inflammation when not required. It is possible that oral administration of Rorrico can promote hepatic synthesis of MBL in healthy PG subjects, thereby conferring increased protection against infection.

关键词： Rorrico Influenza A Virus H1N1 Subtype Tumor necrosis factor-alpha Interleukin-18