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A review on the generation, determination and mitigation of Urban Heat Island

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Journal of Environmental Sciences 2008年第1期20卷 120-128页

作者： RIZWAN Ahmed Memon dennis y.c. leung LIU chunho Department of Mechanical Engineering the University of Hong Kong Hong Kong China.

Urban Heat Island （UHI） is considered as one of the major problems in the 21st century posed to human beings as a result of urbanization and industrialization of human civilization. The large amount of heat generated from urban structures, as they.c.nsume and re-radiate solar radiations, and from the anthropogenic heat sources are the main causes of UHI. The two heat sources increase the temperatures of an urban area as compared to its surroundings, which is known as Urban Heat Island Intensity （UHII）. The problem is even worse in cities or metropolises with large population and extensive economic activities. The estimated three billion people living in the urban areas in the world are directly exposed to the problem, which will be increased significantly in the near future. Due to the severity of the problem, vast research effort has been dedicated and a wide range of literature is available for the subject. The literature available in this area includes the latest research approaches, concepts, methodologies, latest investigation tools and mitigation measures. This study was carded out to review and summarize this research area through an investigation of the most important feature of UHI. It was concluded that the heat re-radiated by the urban structures plays the most important role which should be investigated in details to study urban heating especially the UHI. It was also concluded that the future research should be focused on design and planning parameters for reducing the effects of urban heat island and ultimately living in a better environment.

关键词： urban heat island (UHI) urbanization temperature rise mitigation

A detailed comparison of the composition of(RE)-Ba-cu-O-Ag bulk superconductors

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Superconductivity 2024年第1期9卷 87-94页

作者： J.V.J.congreve y.Shi A.R.dennis H.Druiff N.c.Tutt D.A.cardwell J.H.Durrell Department of Engineering University of CambridgeCambridgeUK

The homogeneity of the microstructure and composition are critical in determining the properties of rare earthbarium‐cuprate,single grain bulk superconductors[(RE)BcO].The magnitude of the trapped magnetic field achieveable in these technologically important materials,in particular,is influenced heavily by the size and distribution of(RE)_(2)BacuO_(x)(RE‐211)flux pinning inclusions in the bulk microstructure,whereas the size and distribution of silver agglomerates present within the bulk superconducting matrix correlate directly with improved mechanical *** careful engineering,these materials have significant potential for application in range of devices related to energy storage,medicine,electro‐magnetic machinery and microelectronic *** of(RE)BcO bulk superconductors typically involves heating a powder compact above its peritectic decomposition temperature followed by slow cooling to facilitate the growth of a single ***(RE)BcO composition has a different peritectic temperature and growth rate,which,therefore,necessitates different requirements in the heating *** fabrication temperature and growth rate,for example,may have an effect on the RE‐211 and silver distribution,which may,in turn,affect the superconducting properties of the resulting single *** this work we compare the distributions of silver and RE‐211 in the single grain microstructures of y.c.Ag,GdBcO‐Ag,EuBcO‐Ag and SmBcO‐Ag bulk superconductors using optical microscopy,scanning electron microscopy and energy dispersive X‐ray *** observe that the distributions are very similar along both the a/b‐axis and c‐axis of these *** suggests that factors other than the maximum temperature used to achieve peritectic decomposition and the rate of single grain growth are particularly influential in determining the properties of the as‐processed samples in the top seeded melt growth *** observation demonstrates there is freedom to us

关键词： y.c.‐Ag GdBcO‐Ag SmBcO‐Ag EuBcO‐Ag composition Bulk superconductor

Quantitative and qualitative subgenomic RNA profiles of SARS-coV-2 in respiratory samples: A comparison between Omicron BA.2 and non-VOc-D614G

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Virologica Sinica 2024年第2期39卷 218-227页

作者： Zigui chen Rita Way yin Ng Grace Lui Lowell Ling Agnes S.y.leung chit chow Siaw Shi Boon Wendy.c.S.Ho Maggie Haitian Wang Renee Wan yi chan Albert Martin Li David Shu cheong Hui Paul Kay Sheung chan Department of Microbiology Faculty of MedicineThe Chinese University of Hong KongHong KongChina Department of Medicine and Therapeutics Faculty of MedicineThe Chinese University of Hong KongHong KongChina Department of Anaesthesia and Intensive care Faculty of MedicineThe Chinese University of Hong KongHong KongChina Department of Paediatrics Faculty of MedicineThe Chinese University of Hong KongHong KongChina Department of Anatomical and cellular Pathology Faculty of MedicineThe Chinese University of Hong KongHong KongChina Jockey.c.ub School of Public Health and Primary.c.re Faculty of MedicineThe Chinese University of Hong KongHong KongChina Stanley Ho centre for Emerging Infectious Diseases Faculty of MedicineThe Chinese University of Hong KongHong KongChina

The SARS-coV-2 Omicron variants are notorious for their transmissibility,but little is known about their subgenomic RNA(sgRNA)*** study applied RNA-seq to delineate the quantitative and qualitative profiles of canonical sgRNA of 118 respiratory samples collected from patients infected with Omicron BA.2 and compared with 338 patients infected with non-variant of concern(non-VOc)-D614G.A unique characteristic profile depicted by the relative abundance of 9 canonical sgRNAs was reproduced by both BA.2 and non-VOcD614G regardless of host gender,age and presence of ***,such profile was lost in samples with low viral load,suggesting a potential application of sgRNA pattern to indicate viral activity of individual patient at a specific time point.A characteristic qualitative profile of canonical sgRNAs was also reproduced by both BA.2 and *** presence of a full set of canonical sgRNAs carried a coherent correlation with crude viral load(AUc¼0.91,95%cI 0.88–0.94),and sgRNA ORF7b was identified to be the best surrogate marker allowing feasible routine application in characterizing the infection status of individual *** potentials in using sgRNA as a target for vaccine and antiviral development are worth pursuing.

关键词： coronavirus SARS-coV-2 Omicron BA.2 Non-VOc-D614G RNA-seq Subgenomic RNA(sgRNA)

Impacts of environmental factors on urban heating

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Journal of Environmental Sciences 2010年第12期22卷 1903-1909页

作者： Rizwan Ahmed Memon dennis y.c.leung Department of Mechanical Engineering Mehran University of Engineering & Technology Department of Mechanical Engineering The University of Hong Kong School of Energy and Environment City University of Hong Kong

This study investigated the impact of important environmental variables （i.e., wind speed, solar radiation and cloud cover） on urban heating. Meteorological parameters for fifteen years （from 1990 to 2005）, collected at a well developed and densely populated commercial area （Tsim Sha Tsui, Hong Kong）, were analyzed in details. Urban heat island intensity （UHII）, a well known indicator of urban heating, has been determined as the spatially averaged air-temperature difference between Tsim Sha Tsui and Ta Kwu Ling （a thinly populated rural area with lush vegetation）. Results showed that the UHII and cloud cover have increased by around 9.3% and 4%, respectively, whereas the wind speed and solar radiation have decreased by around 24% and 8.5%, respectively. The month of December experienced the highest UHII （10.2℃） but the lowest wind speed （2.6 m/sec） and cloud cover （3.8 oktas）. conversely, the month of April observed the highest increases in the UHII （over 100%） and the highest decreases in wind speed （over 40 %） over fifteen years. Notably, the increases in the UHII and reductions in the wind speed were the highest during the night-time and early morning. conversely, the intensity of solar radiation reduced while the intensity of urban cool island （UcII） increased during solar noon-time. Results demonstrated strong negative correlation between the UHII and wind speed （coefficient of determination, R^2 = 0.8） but no negative correlation between UcII and solar radiation attenuation. A possible negative correlation between UHII and cloud cover was investigated but could not be substantiated.

关键词： urban heat island urban cool island wind speed cloud cover

Numerical study on the ozone formation inside street canyons using a chemistry box model

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Journal of Environmental Sciences 2008年第7期20卷 832-837页

作者： chun-Ho Liu dennis y.c.leung Department of Mechanical Engineering The University of Hong KongHong Kong.

Tropospheric ozone is a secondary air pollutant produced in the presence of nitrogen oxides (NO_x),volatile organic compounds (VOcs),and solar *** an urban environment,ground-level vehicular exhaust is the major anthropogenic source of ozone *** the cases of street canyons,pollutant dilution is weakened by the surrounding buildings that creates localized high concentration of NO_x and VOcs,and thus leads to high potential of ozone *** considering the major physical and chemical p...

关键词： volatile organic compounds VOcs-to-NO_x ratio air quality vehicular emission chemistry box model

Effects of building aspect ratio,diurnal heating scenario,and wind speed on reactive pollutant dispersion in urban street canyons

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Journal of Environmental Sciences 2012年第12期24卷 2091-2103页

作者： Nelson y.O.Tong dennis y.c.leung Department of Mechanical Engineering The University of Hong Kong

A photochemistry.c.upled computational fluid dynamics （cFD） based numerical model has been developed to model the reactive pollutant dispersion within urban street canyons, particularly integrating the interrelationship among diurnal heating scenario （solar radiation affections in nighttime, daytime, and sun-rise/set）, wind speed, building aspect ratio （building-height-to-street-width）, and dispersion of reactive gases, specifically nitric oxide （NO）, nitrogen dioxide （NO2） and ozone （O3） such that a higher standard of air quality in metropolitan cities can be achieved. Validation has been done with both experimental and numerical results on flow and temperature fields in a street canyon with bottom heating, which justifies the accuracy of the current model. The model was applied to idealized street canyons of different aspect ratios from 0.5 to 8 with two different ambient wind speeds under different diurnal heating scenarios to estimate the influences of different aforementioned parameters on the chemical evolution of NO, NO2 and 03. Detailed analyses of vertical profiles of pollutant concentrations showed that different diurnal heating scenarios could substantially affect the reactive gases exchange between the street canyon and air aloft, followed by respective dispersion and reaction. Higher building aspect ratio and stronger ambient wind speed were revealed to be, in general, responsible for enhanced entrainment of 03 concentrations into the street canyons along windward walls under all diurnal heating scenarios. comparatively, particular attention can be paid on the windward wall heating and nighttime uniform surface heating scenarios.

关键词： photochemistry reactive pollutant dispersion building aspect ratio diurnal heating scenario wind speed urban streetcanyon

Superior antibody and membrane protein‑specific T‑cell responses to coronaVac by intradermal versus intramuscular routes in adolescents

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World Journal of Pediatrics 2024年第4期20卷 353-370页

作者： Jaime S.Rosa Duque Samuel M.S.cheng carolyn A.cohen Daniel leung Xiwei Wang Xiaofeng Mu yuet chung Tsun Ming Lau Manni Wang Wenyue Zhang yanmei Zhang Howard H.W.Wong Leo c.H.Tsang Sara chaothai Tsz chun Kwan John K.c.Li Karl c.K.chan Leo L.H.Luk Jenson c.H.Ho Wing yan Li Amos M.T.Lee Jennifer H.y.Lam Sau Man chan Wilfred H.S.Wong Issan y.S.Tam Masashi Mori Sophie A.Valkenburg Malik Peiris Wenwei Tu yu Lung Lau Department of Paediatrics and Adolescent Medicine The University of Hong KongHong KongChina School of Public Health The University of Hong KongHong KongChina HKU‑Pasteur Research Pole School of Public HealthThe University of Hong KongHong KongChina Research Institute for Bioresources and Biotechnology Ishikawa Prefectural UniversityNonoichiJapan Department of Microbiology and Immunology Peter Doherty Institute for Infectionand ImmunityUniversity of MelbourneMelbourneVICAustralia center for Immunology and Infection c2i Hong KongChina

Background Optimising the immunogenicity of cOVID-19 vaccines to improve their protection against disease is *** dosing by intradermal(ID)administration has been shown to be equally immunogenic as intramuscular(IM)administration for several vaccines,but the immunogenicity of ID inactivated whole severe acute respiratory syndrome coronavirus 2(SARS-coV-2)at the full dose is *** study(NcT04800133)investigated the superiority of antibody and T-cell responses of full-dose coronaVac by ID over IM administration in *** Participants aged 11–17 years received two doses of IM or ID vaccine,followed by the 3rd dose 13–42 days *** and cellular immunogenicity outcomes were measured post-dose 2(IM-cc versus ID-cc)and post-dose 3(IMccc versus ID-ccc).Doses 2 and 3 were administered to 173 and 104 adolescents,*** Spike protein(S)immunoglobulin G(IgG),S-receptor-binding domain(RBD)IgG,S IgG Fcγreceptor IIIa(FcγRIIIa)-binding,SNM[sum of individual(S),nucleocapsid protein(N),and membrane protein(M)peptide pool]-specific interleukin-2(IL-2)+cD4^(+),SNM-specific IL-2^(+)cD8^(+),S-specific IL-2^(+)cD8^(+),N-specific IL-2^(+)cD4^(+),N-specific IL-2^(+)cD8^(+)and M-specific IL-2^(+)cD4^(+)responses fulfilled the superior and non-inferior criteria for ID-cc compared to IM-cc,whereas IgG avidity was *** ID-ccc,S-RBD IgG,surrogate virus neutralisation test,90%plaque reduction neutralisation titre(PRNT90),PRNT50,S IgG avidity,S IgG FcγRIIIa-binding,M-specific IL-2^(+)cD4^(+),interferon-γ+cD8^(+)and IL-2^(+)cD8^(+)responses were superior and non-inferior to *** estimated vaccine efficacies were 49%,52%,66%and 79%for IM-cc,ID-cc,IM-ccc and ID-ccc,*** ID groups reported more local,mild adverse *** This is the first study to demonstrate superior antibody and M-specific T-cell responses by ID inactivated SARScoV-2 vaccination and serves as the basis for future research to improve the

关键词： coronaVac coronavirus disease 2019 Immunity Intradermal Vaccine

Nitric oxide removal by wastewater bacteria in a biotrickling filter

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Journal of Environmental Sciences 2014年第3期26卷 555-565页

作者： Hejingying Niu dennis y.c.leung chifat Wong Tong Zhang Mayngor chan Fred c c leung Department of Mechanical Engineering The University of Hong Kong School of Biological Sciences The University of Hong Kong Department of civil Engineering The University of Hong Kong

Nitric oxide （NO） is one of the most important air pollutants in atmosphere mainly emitted from combustion source. A biotriclding filter was designed and operated to remove NO from an air stream using bacteria extracted from the sewage sludge of a municipal sewage treatment plant. To obtain the best operation conditions for the biotrickling filter, orthogonal experiments （L9（34）） were designed. Inlet oxygen concentration was found to be the most significant factor of the biotrickling filter and has a significant negative effect on the system. The optimal conditions of the biotrickling filter occurred at a temperature of 40℃, a pH of 8.0 and a chemical oxygen demand of 165 mg/L in the recycled water with no oxygen in the system. The bacteria sample was detected by DNA sequencing technology and showed 93%-98% similarity to Pseudomonas mendocina. Moreover, a full gene sequencing results indicated the bacterium was a brand new strain and named as P. mendocina DLHK. This strain can transfer nitrate to organic nitrogen. The result suggested the assimilation nitrogen process in this system. Through the isotope experimental analysis, two intermediate products （^15NO and ^15N2O） were found. The results indicated the denitrification function and capability of the biotrickling filter in removing NO.

关键词： NO reduction biotrickling filter orthogonal experiment Pseudomonas mendocina isotope labeling

Mechanistic study of vacuum UV catalytic oxidation for toluene degradation over ceO_(2) nanorods

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Green Energy & Environment 2022年第3期7卷 533-544页

作者： Muyan Wu yingguang Zhang Haibao Huang dennis y.c.leung Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong KongChina School of Environmental Science and Engineering Sun Yat-sen UniversityGuangzhou510275China

The present study specifically investigates vacuum ultraviolet (VUV) catalytic oxidation for toluene degradation over ceO_(2) *** effects of ultraviolet photocatalytic oxidation (UV-PcO) and ozone catalytic oxidation (OZcO) were manifested in the results of toluene removal and cOx generation,while the combination of UV-PcO andOZcO (UV-OZcO) did not lead to improvement of *** the processes contribute to ozone decomposition,but no obvious synergetic effects of the different processes can be *** analysis results indicated that more toluene was oxidized into by-products,such as benzyl alcohol and benzaldehyde,by UV-OZcO rather than forming *** hydroxyl radical (·OH) and superoxide radical (·O_(2)^(-)) were found in all the processes of the VUV-PcO-OZcO system(combination of VUV photolysis,UV-PcO,OZcO and UV-OZcO processes).In the UV-OZcO process,the formation of hydroxyl radical was promoted,while that of superoxide radical was impeded,resulting in lower mineralization level of *** mechanistic study of toluene degradation over ceO_(2) nanorods in the VUV-PcO-OZcO system revealed that with the formation of·O_(2)^(-)and·OH,toluene is first oxidized to intermediates,followed by further ring–opening reaction and,finally,degradation into cO_(2) and H_(2)***_(2) nanorods function as both ozonation catalyst and photocatalyst,and the redox pair of ce^(3+)and ce^(4+)are interconvertible and can keep a balance.

关键词： toluene catalytic vacuum