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Using benthic macrofauna to assess environmental quality of four intertidal mudflats in Hong kong and Shenzhen Coast

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Acta Oceanologica Sinica 2003年第2期22卷 309-319页

作者： CaiLizhe NoraF.y.Tam TeresaW.y.wong MaLi Gaoyang yuk-Shanwong ResearchLabortoryofSEDCofMarineEnvironmentalScience EnivonmentalScienceResearchCenterXiamenUniversityXiamen361005China DepartmentofBiologyandChermistryandCenterforCoastalPollutionControl CityUniversityofHongKongHKSARChina

Intertidal zone is a significant wetland between land and ocean. It plays an important rolein maintaining local ecological balance. Both Mai Po and Futian intertidal mudflats are located in Shenzhen Bay and are important 'refueling' point along the East Asian/Australian flyway of migratory birds. The environmental quality of Mai Po and Futian mudflats have aroused great concern due to rapid economic developments in Hong kong and Shenzhen in recent decades. Macroinfauna of Mai Po and Futian mudflats was investigated in December 2000 and the faunal data were used to assess their environmental quality. Two other mudflats, namely Ma Wan Typhoon Shelter (a more disturbed area) and Luk keng intertidal mudflat (a place with relatively less human disturbance), were also sampled for macroinfauna and used as reference mudflats. Shannon - Weaver species diversity index (Isd), biotic coefficient (Cb) and macrofaunal pollution index (Imp) of the macrofauna community on four intertidal mudflats were used to determine their environmental quality. The results showed that Luk keng intertidal mudflat was unpolluted, Mai Po and Futian mudflats were slightly polluted, and Ma Wan was moderately polluted. The pollution in Ma Wan Typhoon Shelter mainly came from various types of rubbish and fishing boats that disturbed the sediment, while pollution sources in Mai Po and Futian mudflats were discharges of industrial water, municipal sewage and from nearby rivers.

关键词： Biotic index macrofauna intertidal mudflat environmental quality

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TRIBOLOGICAL AND HIGH SPEED TURNING PERFORMANCE IN Ti_(1-x)Al_(x)N COATINGS PREPARED By CLOSE-FIELD UNBALANCED MAGNETRON SPUTTERING

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 254-260页

作者： P.W.Shum M.Escursell T.H.wong k.y.Li Z.F.Zhou y.G.Shen Advanced Coatings Applied Research Laboratory(ACARL) Department of Manufacturi ng Engineering and Engineering ManagementCity University of Hong KongKowloonHong KongChina

Titanium-aluminium-nitride(Ti_(1-x)Al_(x)N)coatings were deposited by close-field un balanced magnetron sputtering on M42 steel substrates and WC-6wt%Co inserts at 450℃.The tribological behavior was analyzed by sliding against steel and WC-6wt%Co balls,while the turning performance was evaluated by a conventional tu rning machine at high cutting speeds without using *** the tribological tests,the formation of transfer layer and the variations of hardness of the co atings played an important role for sliding against steel *** the coating s sliding against WC-6wt%Co balls,the Ti-Al-N coatings showed a similar frictio n coefficient,but the TiN coating exhibited a lower *** difference could be explained by the tri-oxidation wear *** the turning tests,a super ior cutting performance of the coating was found at x=0.45,which endured 38 min utes before the tool flank wear reached the maximum value of 0.3mm,whereas only 20 minutes were endured for the TiN *** excellent performance of the c oatings in the turning tests could be explained by the enhanced mechanical prope rties and oxidation/diffusion resistance of the coatings.

关键词： hardness Ti-Al-N coating tribology turning test wear test

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Synthesis of self-assembled nanorod vanadium oxide bundles by sonochemical treatment

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Journal of Natural Gas Chemistry 2009年第3期18卷 312-318页

作者： y.H.Taufiq-yap y.C.wong Z.Zainal M.Z.Hussein Centre of Excellence for Catalysis Science and Technology Faculty of ScienceUniversiti Putra Malaysia Department of Chemistry Faculty of ScienceUniversiti Putra Malaysia

Self-assembled nanorod of vanadium oxide bundles were synthesized by treating bulk V2O5 with high intensity sonochemical technique. The synthesized materials were characterized by X-ray diffraction （XRD）, scanning electron microscope （SEM）, transmission electron microscope （TEM） and temperature-programmed reduction （TPR） in H2. Catalytic behaviour of the materials over anaerobic n-butane oxidation was studied through temperature-programmed reaction （TPRn）. Catalytic evaluation of the sonochemical treated V2O5 products was also studied on microreactor. XRD patterns of all the vanadium samples were perfectly indexed to V2O5. The morphologies of the nanorod vanadium oxides as shown in SEM and TEM depended on the duration of the ultrasound irradiation. Prolonging the ultrasound irradiation duration resulted in materials with uniform, well defined shapes and surface structures and smaller size of nanorod vanadium oxide bundles. H2-TPR profiles showed that larger amount of oxygen species were removed from the nanorod V2O5 compared to the bulk. Furthermore, the nanorod vanadium oxide bundles, which were produced after 90, 120 and 180 min of sonochemical treatment, showed an additional reduction peak at lower temperature （-850 k）, suggesting the presence of some highly active oxygen species. TPRn in n-butane/He over these materials showed that the nanorod V2O5 with highly active oxygen species showed markedly higher activity than the bulk material, which was further proven by catalytic oxidation of n-butane.

关键词： nanorod vanadium oxide sonochemical treatment butane oxidation

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End Effect on the Twin-Wire Depth Probe

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Journal of Thermal Science 1992年第4期1卷 286-291页

作者： C.y.Liu y.W.wong 等 SchoolofMechanicalandProductionEngineering NanyangTechnologicalInstituteNayangAvenueSingapre2263 Sc

The end effect on the output voltage of a twin-wire depth probe was investigated both theoretically and ex- *** was found that the contribution of the end of the probe to the output voltage depends upon the distance between the boundary and the end of the probe and the geometrical configuration of the probe. By mounting a piece of plate to the end of the electrodes,the end effect can be ***,the size of the plate required to eliminate completely this effect is much larger than that usually mounted on commercially available *** between theoretical and experimental results was *** agreement was obtained.

关键词： twin-wire probe depth probe

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Heavy metal concentrations in edible bivalves and gastropods available in major markets of the Pearl River Delta

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Journal of Environmental Sciences 2001年第2期13卷 210-217页

作者： FANG Zhan-qiang CHEUNG R.y.H. wong M.H. Department of Biology South China Normal UniversityGuangzhou 510631China Department of Biology and Chemistry City University of Hong Kong83 Tat Chee AvenueKowloonHong Kong Institute for Natural Resources and Waste Management and Department of BiologyHong Kong Bapt ist UniversityKowloon TongHong Kong

Molluscs are able to accumulate heavy metals and impose health hazard to consumers. The main objective of the present study is to investigate the heavy metal concentrations in edible bivalves and gastropods available in major markets of the Pearl River Delta. Fourteen species of edible molluscs were purchased from six markets in Hong kong and Guangdong Province. The fresh of these biota were tested for their cadmium (Cd), copper (Cu), zinc (Zn), lead (Pb), nickel (Ni), chromium (Cr), antimony (Sb) and tin (Sn) concentrations (based on wet weight). The results indicated that amongst the 14 edible molluscs, only Cd, Pb, Ni, Cr, Sb and Sn concentrations in three species (Ruditapes philippinarum, Perna viridis and Hemifusus tuba) were within the local regulatory limits. Over 60% of bivalve species exceeded maximum permitted levels of Cd (2 mug/g) and Cr (1 mug/g), while over 40% of gastropod species exceeded the maximum levels of Sb (1 mug/g) and Cr (1 mug/g). Most of the samples collected from Hong kong had significantly higher contents of Pb and Sb, but similar levels of Cd, Cu and Zn when compared with samples collected across the border ( p y). In general, the molluscs purchased in Guangdong markets had higher metal contents than those purchased from the Hong kong markets. When compared with the Provisional Tolerable Weekly Intake or Maximum Acceptable Daily Load recommended by FAO/WHO Expert Committee on Food Additives, Cd levels of five species (Anadara ferruginea, Pinna pectinata, Chlamys nobilis, Babylonia lutosa and Hemifusus terntanus) and Cr levels of seven species ( Anadara ferruginea, Paphia undulata, Pinna pectinata, Babylonia lutosa, Hemifusus terntanus, Cymbium melo and Cipangopaludina chinensis) were higher than both the human daily acceptable limits (for Cd and Cr respectively) and the local regulatory levels (for Cd and Cr respectively).

关键词： heavy metals edible molluscs human health Pearl River Delta

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Removal of Lead from Aqueous Solution by Acinetobacter calcoaceticus

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Biomedical and Environmental Sciences 1990年第2期3卷 202-210页

作者： N.k.MAk y.k.MOk V.W.D.CHUI M.H.wong Department of Biology Hong Kong Baptist College 224 Waterloo Road Hong Kong

A bacterial strain tolerant to the presence of 400 ppm lead was isolated from digested sewage sludge. The organism was identified as Acinetobacter calcoaceticus var: anitraus (98% confidence). Both viable and formalin-inactivated bacterial cells could remove Pb from an aqueous solution. The Pb-binding ability of inactivated cells was compared with that of a commercial ion-exchange resin, Amberlite IR-I20. The metal-binding ability of A. calcoaceticus followed the sequence Pb≥Cu≥Cr≥ (Cd, Ni, and Zn)≥Co. The ability of the inactivated cells to remove Pb was pH sensitive, and the adsorption process was slightly affected at high temperature (70℃). The adsorption and desorption process worked equally well with A. calcoaceticus embedded in a polyacrylamide gel matrix. (c)1990 Academic Press, Inc.

关键词： Pb

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Are state ownership and auditors' locality determinants of asset write-downs? Evidence from China

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China Journal of Accounting Research 2018年第4期11卷 385-405页

作者： Pauline W.y.wong Department of Accountancy Hang Seng Management College

After issuing the 1998 Accounting Standards, Chinese regulators implemented additional regulations in 2001 governing write-downs of impaired assets and required assessment of recoverable amounts for four additional asset categories. As the recoverable value cannot be obtained objectively, management can discretionally assess the magnitude of write-downs to affect bottom-line profit. This study used 7258 firm-year observations in China from 1998 to2005 to examine whether the percentage of asset write-downs by statecontrolled firms differs from non-state-controlled firms, conditional upon more conservative financial reporting rules, and investigate whether local auditors support managerial decisions on asset write-downs. The empirical findings support the tendency of state-controlled ownerships to have lower asset write-downs. Local auditors also support managerial decisions on asset write-downs, especially when the companies are controlled by local governments.

关键词： Earnings management Impairments State ownership Auditor locality Political influence

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On Systems of Boundary Value Problems for Differential Inclusions

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Acta Mathematica Sinica,English Series 2007年第3期23卷 549-556页

作者： Lynn ERBE Christopher C.TISDELL Patricia J.y.wong Department of Mathematics The University of Nebraska-LincolnLincolnNE 68588-0130USA School of Mathematics and Statistics The University of New South WalesSydney 2052Australia School of Electrical and Electronic Engineering Nanyang Technological University50 Nanyan9 AvenueSingapore 639798Singapore

Herein we consider the existence of solutions to second-order, two-point boundary value problems （BVPs） for systems of ordinary differential inclusions. Some new Bernstein-Nagumo conditions are presented that ensure a priori bounds on the derivative of solutions to the differential inclusion. These a priori bound results are then applied, in conjunction with appropriate topological methods, to prove some new existence theorems for solutions to systems of BVPs for differential inclusions. The new conditions allow of the treatment of systems of BVPs without growth restrictions.

关键词： boundary value problem, systems of differential inclusions, existence of solutions a priori bounds Bernstein-Nagumo condition

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Comprehensive characterization of indoor airborne bacterial profile

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Journal of Environmental Sciences 2009年第8期21卷 1148-1152页

作者： P. L. Chan P. H. F. yu y. W. Cheng C. y. Chan P. k. wong Department of Biology The Chinese University of Hong Kong Department of Applied Biology and Chemical Technology The Hong Kong Polytechnic University Department of Microbiology The Chinese University of Hong Kong

This is the first detailed characterization of the airborne bacterial profiles in indoor environments. Two restaurants were selected for this study. Fifteen genera of bacteria were isolated from each restaurant and identified by three different bacterial identification systems including MIDI, Biolog and Riboprinter. The dominant bacteria of both restaurants were Gram-positive bacteria in which Micrococcus and Bacillus species were the most abundant. Most bacteria identified were representative species of skin and respiratory tract of human, and soil. Although the bacterial levels in these two restaurants were below the limit of the Hong kong Indoor Air Quality Objective （HkIAQO） Level 1 standard （i.e., 〈 500 cfu/m^3）, the majority of these bacteria were opportunistic pathogens. These results suggested that the identity of airborne bacteria should also be included in the IAQ to ensure there is a safety guideline for the public.

关键词： airborne bacterial profile bacterial identification indoor air quality

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A NOVEL PHASE CONTROL TECHNIQUE FOR INJECTION LOCkED OSCILLATORS

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Journal of Electronics(China) 1995年第4期12卷 374-377页

作者： kwok-Wai wong Albert k. y. Lai 曾学刚 Department of Electronic Engineering the Chinese University of Hong Kong Shatin Hong Kong University of Electronic Science and Technology of China Chengdu 610054 A novel technique to obtain injection locked oscillators phase tuning beyond 180°is demonstrated. The idea is to cascade injection locked oscillators together for phase change accumulation. A two stage injection locked oscillators can theoretically provide a maximum of 360?phase change within the locking range. This is particularly useful for phased array antenna applications.

A novel technique to obtain injection locked oscillators phase tuning beyond 180° is demonstrated. The idea is to cascade injection locked oscillators together for phase change accumulation. A two stage injection locked oscillators can theoretically provide a maximum of 360?phase change within the locking range. This is particularly useful for phased array antenna applications.

关键词： Phase control Locking Oscillators Antenna array

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