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A one-step,tunable method of selective reactive sputter deposition as a wrinkling approach for silver/polydimethylsiloxane for electrically conductive pliable surfaces

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Microsystems & Nanoengineering 2022年第4期8卷 221-231页

作者： Joel y.y.Loh Ali Zeineddine Moein Shayegannia Robyn McNeil Liam McRae Nazir p.Kherani Department of Electrical and Computing Engineering University of TorontoTorontoON M5S 3G4Canada Department of Material Science and Engineering University of TorontoTorontoON M5S 3E4Canada

The wrinkle period and morphology of a metal thin film on an elastic substrate is typically controlled by modifying the substrate before carrying out additional metal deposition ***,we show that a simultaneously selective and reactive sputtering plasma that modifies the surface of a polydimethylsiloxane(pDMS)substrate while not reacting with the metal during the deposition process decreases the wrinkle wavelength and induces additional wrinkling components and features such as ripples or *** selective reaction of the nitrogen plasma with pDMS functionalizes the siloxane surface into silicon *** hardens the immediate surface of pDMS,with a quadratic increase in the young’s modulus as a function of the sputtering flow *** increase in the critical strain mismatch and the corresponding presence of folds in the nitrogen-modified wrinkled silver film form a suitable plasmonic platform for surface-enhanced Raman spectroscopy(SERS),yielding an enhancement factor of 4.8×105 for detecting *** enhancement is linked to the emergence of electromagnetic hotspots from surface plasmon polariton coupling between the folds/wrinkles,which in turn enables the detection of low concentrations of organics using ***,when strained,the nitrogen-modified wrinkles enhance electrical conductivity by a factor of 12 compared with unmodified ***,the optical properties of the substrate can be tuned by altering the N2 *** simple addition of nonreactive nitrogen to silver sputtering enables simultaneous pDMS hardening and growth of the silver film and together provide a new avenue for tuning wrinkling parameters and enhancing the electrical conductivity of pliable surfaces.

关键词： silver reactive film

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Enhanced pitting corrosion resistance of a Zr-based metallic glass by ultraviolet light irradiation

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Journal of Iron and Steel Research International 2023年第8期30卷 1642-1649页

作者： Z.Chen D.p.Wang S.Wang y.X.Geng y.X.Guo y.C.Wu Z.G.Liu y.y.Zhang y.X.Wang School of Materials Science and Engineering Jiangsu University of Science and Technology.Zhenjiang 212003JiangsuChina School of Mechanical Engineering Jiangsu University of Science and TechnologyZhenjiang 212003JiangsuChina

The influence of ultraviolet light irradiation on the pitting corrosion performance of a Zr_(2)Ni metallic glass was examined using electrochemical methods and immersion test in 0.05 mol/L NaCl *** the results of potentiostatic polarization,the pitting potential of the ultraviolet light-irradiated sample shifted positively with a value of~300 mV,revealing the enhanced pitting corrosion resistance of the *** corrosion morphology after the immersion test also demonstrated lower degree of corrosion damage and improved pitting resistance of the sample with ultraviolet light irradiation.X-ray photoelectron spectroscopy analysis revealed more zirconium enrichment in the passive film and no chloride ions adsorption for the samples with ultraviolet irradiation,accounting for the suppression of the pit generation and *** findings indicate that ultraviolet light irradiation improves the pitting corrosion resistance of the Zr-based metallic glasses,which are promising structural materials to be used in corrosion environments with high ultraviolet irradiation.

关键词： Metallic glass pitting-Corrosion Ultraviolet light irradiation passive film

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Interference with the formation of the epididymal microenvironment——a new strategy for male contraception?

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Asian Journal of Andrology 2000年第1期2卷 39-45页

作者： X.D.Gong G.p.H.Leung B.L.y.Cheuk p.y.D.Wong Department of phsiology The Chinese University of Hong Kong Shatin N. T. Hong Kong ChinaDepartment of Phsiology The Chinese University of Hong Kong Shatin N. T. Hong Kong ChinaDepartment of Phsiology The Chinese University of Hong Kong Shatin N. T. Hong Kong ChinaDepartment of Phsiology The Chinese University of Hong Kong Shatin N. T. Hong Kong China

The cystic fibrosis transmembrane conductance regulator (CFIR) or the small conductance cAMp-activated chlo-ride channel encoded by the CFTR gene has been shown to play an important role in the formation of the epididymalfluid microenvironment. Recent work in our laboratory has shown that this protein is also expressed by developing germcells indicating a role of this protein in spermatogenesis. In view of the fact that the CFTR gene has a far reaching andwidespread effect on human reproduction, understanding the role of CFTR in the male reproductive tissues and its inter-vention by pharmacological agents can open a new avenue of research into the development of novel male contracep-tives. (Asian J Androl 2000; 2: 39 - 45 )

关键词： epididymis cyclooxygenase contraception cystic fibrosis transmembrane conductance regulator

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Comparison Study of Constitutive Models for Overconsolidated Clays

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Acta Mechanica Solida Sinica 2020年第1期33卷 98-120页

作者： Z.Wan y.p.yao Z.W.Gao Research Institute of Base and Foundation China Academy of Building ResearchBeijing 100013China School of Transportation Science and Engineering Beihang UniversityBeijing 100091China School of Engineering University of GlasgowGlasgow G128QQUK

Widely distributed in natural deposits,the overconsolidated(OC)clays have attracted extensive experimental investigations on their mechanical behaviors,especially in the 1960s and *** on these results,numerous constitutive models have also been *** models generally fall into two categories:one based on the classical plasticity theory and the other the bounding surface(BS)plasticity theory,with the latter being more popular and *** BS concept and the subloading surface(SS)concept are the two major BS plasticity *** features of these two concepts and the representative models based on them are introduced,*** unified hardening(UH)model for OC clays is also based on the BS plasticity theory but distinguishes itself from other models by the integration of the reference yield surface,unified hardening parameter,potential failure stress ratio,arid transformed stress *** is made to the Hvorslev envelop employed in the UH model to improve its capability of describing the behaviors of clays with extremely high overconsolidation ratio in this *** comparison among the BS model,SS model,and UH model is *** shows that all these three models can characterize the fundamental behaviors of OC clays,such as the stress dilatancy,strain softening and attainment of the critical *** UH model with the revised Hvorslev envelop has the fewest parameters which are identical to those of the modified Cam-Clay model.

关键词： Clay Overconsolidation Critical state Bounding surface Subloading surface Unified hardening model

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Effect of terrain and building structures on the airflow in an airport

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Journal of Zhejiang University-Science A(Applied physics & Engineering) 2012年第6期13卷 461-468页

作者： Dennis y. C. LEUNG W. y. LO W. y. CHOW p. W. CHAN Department of Mechanical Engineering The University of Hong Kong Hong Kong China Hong Kong Observatory Hong Kong China

The aim of this study was to perform computational fluid dynamics (CFD) simulations on the airflows at the Hong Kong International Airport (HKIA). In particular, the effects of hangar buildings and terrain were studied to explore the effects of turbulence on flying aircraft, especially during landing. The CFD simulation showed that significant differences in wind speeds may occur between the north and the south runways on the western part of the HKIA under typhoon conditions with a strong north to northwesterly wind. Simulation also showed that the hanger buildings between the two runways on the western side and the nearby terrain could be causing the observed difference in the wind speeds. The results also indicated that these obstacles could cause significant wind speed variations at the western end of the south runway. This may affect the operation of landing aircraft. The CFD results for a typical typhoon case were analyzed and found to match the wind data recorded by an aircraft landing that day.

关键词： Computational fluid dynamics (CFD) Hong Kong International Airport (HKIA) Low-level wind effect Hangars Terrain

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Forced Convective Air Cooling from Electronic Component Arrays in a parallel plate Channel

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Journal of Thermal Science 1994年第3期3卷 161-166页

作者： D.y.Cai y.p.Gan 等 NorthChinaInstituteComputingTechnology DepartmentofThermalEnergyEngineering BeijingPolytechnicUnivers

This paper discusses air forced convection heat transfer from inline protruding elements arranged in eight rows. The streamwise and spanwise spacings between elements were varied using a splitter plate that can be positioned at three different modular configurations. A set of empirical formulas waspresented to correlate the experimental data for the design of air cooling systems. Arrays of components with one odd-size module have been tested also. Experimental results show that blocks near the entrance and behind the odd-size module have improved performance compared with uniform arrangements. Accordingly, temperature sensitive components are suggested to be arranged in these locations.

关键词： convection heat transfer air cooling

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EFFECT OF SILICON ON pRODUCING DUCTILE IRON WITH COMpLEX STRUCTURE OF BAINITE AND MARTENSITE

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Acta Metallurgica Sinica(English Letters) 1998年第1期11卷 25-28页

作者： y.p.Zhang J.X.Zhu y.Q.Wang J.y.Su Xi'an Univ of Technology Xi'an China

This paper deals with an important role of silicon in producing ductile iron with quenched complex structure of bainite and martensite. The samples are cast in permanent mold and quenched in solution of sodium silicate. The result of thc experiments shows that the austenizing temperature should rise with increasing silicon content, otherwise much undissolved ferrite is present in the matrix after quenching. However the undissolvec ferrite can be decreased greatly or even eliminated by adding appropriate amount of ooron. On this condition, the amount of bainite gets increasing and the amount of residual austenite decreasing with the silicon cortent increasing. An approach has also been made to the mechanism of the effect of silicon on the transformation of bainite in ductile iron. The T.T.T. curves measured show that the increase of sllicon content causes the curve to shift to the left. This is quite different from the fact in steel.

关键词： ductile iron,silicon content bainite martensite

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Mechanisms behind the environmental sensitivity of carbon fiber reinforced polytetrafluoroethylene(pTFE)

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Friction 2024年第5期12卷 997-1015页

作者： pontus JOHANSSON p.MARKLUND M.BJORLING y.SHI Division of Machine Element LuleåUniversity of TechnologyLuleåSE-97187Sweden

Carbon fiber reinforced polytetrafluoroethylene (CF/pTFE) composites are known for their exceptional tribological performance when sliding against steel or cast iron in inert gas environments. Compared to experiments in humid air, about an order of magnitude lower wear rate and several times lower coefficient of friction have been reported for tests conducted in dry nitrogen and hydrogen. Moreover, trace moisture has been shown to affect the friction and wear significantly of this tribosystem, although a possible effect of oxygen cannot be ruled out due to uncertainties regarding the oxygen concentrations. While several studies have pointed out the environmental sensitivity of CF/pTFE, the understanding of the underlying mechanisms are very limited. The objective of this research is to investigate the individual and combined effect of oxygen and moisture on the tribological behavior of CF/pTFE sliding against steel. Additionally, this study aims to elucidate the underlying mechanisms that govern the environmental sensitivity of the system. Climate-controlled three-pin-on-disc experiments were conducted in nitrogen atmospheres at various concentrations of oxygen and moisture. The tribological results clearly demonstrate that both moisture and oxygen contribute to increased friction and wear. However, the adverse effect was much more pronounced for oxygen than moisture. A qualitative method was developed to estimate the tribofilm coverage on the CF/pTFE surface. Results showed strong correlation between high coverage of strongly adhered tribofilm and low wear rate. Moreover, a loosely adhered tribofilm was observed on top of the CF/pTFE surface in presence of moisture. FTIR analysis indicated that the loosely adhered tribofilm found in the moisture-enriched environment contained a significant amount of adsorbed water, which may explain the lower coefficient of friction in presence of moisture compared to oxygen. The adsorbed water in the loosely adhered tribofilm coul

关键词： polymer composite tribofilm tribochemistry atmosphere

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LOCAL MEDIAN ESTIMATION OF VARIANCE FUNCTION

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Acta Mathematica Scientia 2004年第1期24卷 28-38页

作者：杨瑛 W.C.Ip y.K.Kwan p.y.K.Kwan School of Mathematical Sciences Peking University Beijing 100871 China Department of Applied Mathematics The Hong Kong Polgytechnic University Hung Hom Kowloon Hongkong China

This paper considers local median estimation in fixed design regression problems. The proposed method is employed to estimate the median function and the variance function of a heteroscedastic regression model. Strong convergence rates of the proposed estimators are obtained. Simulation results are given to show the performance of the proposed methods.

关键词： Heteroscedasticity nonparametric median regression strong convergence rate variance function local median estimation

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Growth-temperature-dependent optical and acetone detection properties of ZnO thin films

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Journal of Semiconductors 2015年第7期36卷 17-21页

作者： p.S.Shewale y.S.yu Convergence of IT Devices Institute Dong-Eui University Department of Radiological Science Dong-Eui University

Zinc oxide （ZnO） thin films were prepared onto glass substrates at moderately low growth tempera- ture by two-stage spray pyrolysis technique. The effects of growth temperature on structural, optical and acetone detection properties were investigated with X-ray diffractometry, a UV-visible spectrophotometer, photoluminescence （pL） spectroscopy and a homemade gas sensor testing unit, respectively. All the films are polycrystalline with a hexagonal wurtzite phase and exhibit a preferential orientation along [002] direction. The film crystallinity is gradually enhanced with an increase in growth temperature. The optical measurements show that all the films are physically highly transparent with a transmittance greater than 82% in the visible range. The band gap of the film is observed to exhibit a slight red shift with an increasing growth temperature. The pL studies on the films show UV/violet pL band at - 395 nm. Among all the films investigated, the film deposited at 250℃ demonstrates a maximum sensitivity of 13% towards 20 ppm of acetone vapors at 300℃ operating temperature.

关键词： ZnO thin film growth temperature optical acetone sensing properties

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