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Recent research situation in tin dioxide nanomaterials： synthesis, microstructures, and properties

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Frontiers of Materials Science 2013年第3期7卷 203-226页

作者： Zhi-Wen cHEN chan-Hung SHEk c. M. Lawrence WU Joseph k. L. LAI Shanghai Applied Radiation Institute School of Environmental and Chemical Engineering Shanghai University Shanghai 200444 China Department of Physics and Materials Science City University of Hong Kong Tat Chee Avenue Kowloon Tong Hong Kong China

This review article summarizes the new research in solid-state physical chemistry understanding of the microstructure characteristics of semiconductor tin oxide thin films made in the last years in our group. The work mainly focuses on the fabrication technology of semiconductor tin oxides thin films by using pulsed laser deposition （PLD） as well as the application of this technology on new micro- and nanostructured materials. It is an interdisciplinary work that integrates the areas of physics, chemistry and materials science.

关键词： tin dioxide thin film synthesis microstructure nanostructure property

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

Sensitivity of precipitation statistics to urban growth in a subtropical coastal megacity cluster

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Journal of Environmental Sciences 2017年第9期29卷 6-12页

作者： christopher claus Holst Johnny c.L.chan chi-Yung Tam School of Energy and Enuironment City Uniuersity of liong KongHong KongChina Guy carpenter Asia-Pacific climate Impact centre City Uniuersity of Hong KongHong KongChina Earth System Science Programme The Chinese Uniuersity of Hong KongHong KongChina

This short paper presents an investigation on how human activities may or may not affect precipitation based on numerical simulations of precipitation in a benchmark case with modified lower boundary conditions, representing different stages of urban development in the model. The results indicate that certain degrees of urbanization affect the likelihood of heavy precipitation significantly, while less urbanized or smaller cities are much less prone to these effects. Such a result can be explained based on our previous work where the sensitivity of precipitation statistics to surface anthropogenic heat sources lies in the generation of buoyancy and turbulence in the planetary boundary layer and dissipation through triggering of convection. Thus only mega cities of sufficient size, and hence human-activity-related anthropogenic heat emission, can expect to experience such effects. In other words, as cities grow, their effects upon precipitation appear to grow as well.

关键词： Urban precipitation Micro climate sensitivity Urbanization

Ophthalmology in the time of cOVID-19: experience from Hong kong Eye Hospital

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International Journal of Ophthalmology(English edition) 2020年第6期13卷 851-859页

作者： Stephanie S.L.cheung cherie Y.k.Wong Jason c.k.chan carmen k.M.chan N.M.Lam Hunter k.L.Yuen Victoria W.Y.Wong chi Wai Tsang clement c.Y.Tham Department of Ophthalmology and Visual Sciences the Chinese University of Hong KongHong Kong SARChina Hong kong Eye Hospital Hong Kong SARChina

AIM:To review international guidelines and to share our infection control experience during the coronavirus disease 2019(cOVID-19)pandemic at a tertiary eye centre in Hong ***:Infection control guidelines and recommendations from international ophthalmological bodies are reviewed and *** measures at our hospital were drawn up as per international and local health authorities’guidelines and implemented with the collaboration of doctors,nurses and administrative ***:The aims of our infection control measures are to 1)minimize cross-infection within the hospital;2)protect and support hospital staff;3)ensure environmental *** minimize the risk of cross-infection,outpatient attendance and elective surgery have been reduced by 40%,and general anesthesia procedures were reduced by 90%.Patients entering the hospital are screened for fever,travel history,contact and cluster history,and cOVID-19 related *** protect and support hospital staff,we ensure provision of adequate personal protective equipment(PPE)and provide clear guidelines on the level of PPE needed,depending on the clinical *** protective measures include provision of work uniforms,easy access to alcohol-based hand rub,opening new lunch areas,implementation of self-monitoring and self-reporting systems,and communication via online education and ***,environmental control is achieved by ensuring regular disinfection of the hospital premise,enhancing ventilation,and usage of disposable ophthalmic ***:Our multi-pronged approach to infection control is,so far,successful in minimizing infection risks,while allowing the maintenance of essential ophthalmic services.

关键词： cOVID-19 coronavirus SARS-coV-2 ophthalmology infection control Hong kong

Detection of Breaking Waves Using X-Band Pulse Radar in the Nearshore Region

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china Ocean Engineering 2013年第4期27卷 549-556页

作者： Y.c.Lin c.c.chang M.c.Lee H.c.chan J.M.Leu Department of Hydraulic and Ocean Engineering National Cheng-Kung University Department of Soil and Water conservation National Chung Hsing University Department of Hospitality Management Taiwan Shoufu University

An X-band pulsed Doppler microwave radar has been used to determine the characteristics of breaking waves. Field experiments were conducted at the Shuang-Si estuary in the north of Taiwan in the winter of 2005. Analyses on maxima radar cross section and Doppler frequency shift are done to characterize wave breaking zones. Based on observations of breaking waves, the wave breaking zones are shown to be located at water depths of 1.8 to 2.2 m in the experimental site. In general, the results indicate that a radar system has the potential to delineate the spatial variation of breaking waves clearly and that this is sufficient to achieve a measurement operation for near-shore air-sea interaction events.

关键词： radar Doppler effect wave breaking coastal zone

Large-eddy Simulation of Ethanol Spray-Air combustion and Its Experimental Validation

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chinese Journal of chemical Engineering 2014年第2期22卷 214-220页

作者：李科周力行 chan c.k Department of Engineering Mechanics Tsinghua University School of Energy and Environment Inner Mongolian University of Science and Technology Department of Applied Mathematics Hong Kong Polytecnic University

Large-eddy simulation of spray combustion is under its rapid *** combustion models were used by different ***,these models are less validated by detailed experimental *** this paper,large-eddy simulation(LES)of ethanol spray-air combustion was made using an Eulerian-Lagrangian approach,a subgrid-scale kinetic energy stress model,and a filtered finite-rate combustion model,neglecting the sub-grid scale reaction *** simulation results are compared with experimental dada in the literature and validated in *** LES obtained statistically averaged gas temperature is in much better agreement with the experimental results than Reynolds averaged(RANS)modeling using the most complex probability density function(PDF)equation combustion *** instantaneous LES results show the coherent structures of the shear region near the high-temperature flame zone and the fuel vapor concentration map,indicating that the droplets are concentrated in this shear *** instantaneous temperature,oxygen and carbon dioxide concentration maps show the close interaction between the coherent structures and the combustion reaction.

关键词： ethanol-air two-phase flow spray combustion large-eddy simulation

Multi-omic analyses identify mucosa bacteria and fecal metabolites associated with weight loss after fecal microbiota transplantation

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The Innovation 2022年第5期3卷 129-139页

作者： Fen Zhang Tao Zuo Yating Wan Zhilu Xu chunpan cheung Amy YLi Wenyi Zhu Whitney Tang Paul k.S.chan Francis k.L.chan Siew c.Ng Department of Medicine and Therapeutics Institute of Digestive DiseaseState Key Laboratory of Digestive DiseasesLKS Institute of Health SciencesThe Chinese University of Hong KongHong Kong 999077China Microbiota I-center(MagIc) Hong Kong 999077China Department of Microbiology The Chinese University of Hong KongHong Kong 999077China center for Gut Microbiota Research Faculty of MedicineThe Chinese University of Hong KongHong Kong 999077China

Fecal microbiota transplantation(FMT)has shown promising results in animal models of obesity,while results in human studies are *** aimed to determine factors associated with weight loss after FMT in nine obese subjects using serial multi-omics analysis of the fecal and mucosal *** mucosal microbiome,fecal microbiome,and fecal metabolome showed individual clustering in each subject after *** colonic microbiome in patients showed more marked variance after FMT compared with the duodenal microbiome,characterized by an increased relative abundance of *** who lost weight after FMT sustained enrichment of Bifidobacterium bifidum and Alistipes onderdonkii in the duodenal,colonic mucosal,and fecal microbiome and increased levels of phosphopantothenate biosynthesis and fecal metabolite eicosapentaenoic acid(EPA),compared with those without weight *** levels of amino acid metabolism-associated were positively correlated with the fecal abundance of ***,and fatty acid metabolism-associated metabolites showed positive correlations with ***.

关键词： metabolism sustained weight

catalytic conversion of glucose to small polyols over a binary catalyst of vanadium modified beta zeolite and Ru/c

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Journal of Energy chemistry 2019年第7期28卷 88-95页

作者： Joby Sebastian Mingyuan Zheng Xinsheng Li Jifeng Pang chan Wang Tao Zhang Dalian Institute of chemical Physics Chinese Academy of Sciences

catalytic conversion of glucose, the most abundant carbohydrate, to chemicals of petroleum origin has great desirability in terms of sustainability and industrial implementation. In this work, we attempted to exploit the vanadium-based catalysts with high retro-aldol condensation(RAc) activity for the synthesis of small polyols from glucose. Vanadium species incorporated or anchored beta zeolites were found to work effectively in synergy with 1 Ru/Ac to produce hydroxyacetone(HA) as the major product(34%)in a semi-continuously stirred tank reactor under 5% glucose concentration. catalyst characterization by UV-vis and Raman spectral analysis revealed vanadium species mainly stayed in the incorporated form(tetrahedral) at 0.5% of loading and in the supported form(octahedral) at higher loadings up to 8%. Pyridine infrared spectra and temperature programmed desorption of NH3 revealed weak Lewis acid sites in dominance. Vanadium species in the catalysts displayed multiple catalytic roles(isomerization and RAc reaction, and synergism with the hydrogenation catalyst) in the synthesis of HA from glucose. Structureactivity correlation pointed out that the catalytic activity of vanadium species is not dependent on it coordination status, nevertheless, the adjacent vanadium atoms could possibly improve the isomerization rate over the RAc rate in favor of high yield of HA. The catalyst system is recyclable to at least five times without any considerable loss in its activity and structural integrity. The results presented here provide a promising route for the sustainable production of HA and polyols from carbohydrates by using a highly selective vanadium catalyst.

关键词： Vanadium Glucose Retro-aldol condensation Polyols Hydroxyacetone

ZnS Semiconductive Powder Doped with Transition Metal Ions via Mechanochemical Synthesis Technique

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过程工程学报 2004年第Z1期4卷 424-430页

作者： R.F. Louh c.k. Lin Oscar Lin G.S. chen c.c. chan Dept. of Mater. Sci. & Eng. Feng Chia University Taichung 407 China Dept. of chem. Eng. Feng Chia University Taichung 407 China

The solid state synthesis can be carried out by using the initial pure metal zinc and inorganic sulfur powder mixtures by means of the mechanochemical synthesis route. The completion of solid state reaction between pure zinc and sulfur powder to produce c-ZnS and h-ZnS phases via such a route was rather fast, as compared to other non-sulfide systems by the similar method. The study was aimed to investigate the microstructure development and phase formation through the solid state reaction by controlling the processing parameters involved in this process including grinding media to powder weight ratio, solid state reaction duration, reaction atmosphere, stoichiometric ratio of zinc and sulfur elements, grinding media and choice of minor additives such as teflon-based polymeric lubricants and transition metal dopants (Mn, cu). Both as-synthesized powders and heat-treated ZnS materials with various stoichiometric ratios were characterized by XRD, EXAFS and XANES analysis. The interesting results from X-ray absorption spectroscopy (XAS) would provide us some strong evidence whether stoichiometric and non-stoichiometric ZnS material can be successfully formed. The minor amount (0.5wt%)of Mn+2 or cu+2 ion dopants added to the powder batch with the Zn/S stoichiometric ratio between1.00 to 1.05 was found to favor the reaction rate in the mechanochemical synthesis. Moreover, the obtained results of ZnS phase development under reaction conditions and different transition metal dopants in this study would imply that synthesis of other kind of sulfide compounds can be achieved using the demonstrated technique.

关键词： mechanochemical synthesis ZnS powder,semiconductor powder synthesis solid sate reaction transition metal ions