Direct observation of microcavitation in underwater adhesion of mushroom-shaped adhesive microstructure

In this work we report on experiments aimed at testing the cavitation hypothesis [Varenberg, M.; Gorb, S. J. R. Soc., Interface 2008, 5, 383–385] proposed to explain the strong underwater adhesion of mushroom-shaped adhesive microstructures (MSAMSs). For this purpose, we measured the pull-off forces of individual MSAMSs by detaching them from a glass substrate under different wetting conditions and simultaneously video recording the detachment behavior at very high temporal resolution (54,000–100,000 fps). Although microcavitation was observed during the detachment of individual MSAMSs, which was a consequence of water inclusions present at the glass–MSAMS contact interface subjected to negative pressure (tension), the pull-off forces were consistently lower, around 50%, of those measured under ambient conditions. This result supports the assumption that the recently observed strong underwater adhesion of MSAMS is due to an air layer between individual MSAMSs [Kizilkan, E.; Heepe, L.; Gorb, S. N. Underwater adhesion of mushroom-shaped adhesive microstructure: An air-entrapment effect. In Biological and biomimetic adhesives: Challenges and opportunities; Santos, R.; Aldred, N.; Gorb, S. N.; Flammang, P., Eds.; The Royal Society of Chemistry: Cambridge, U.K., 2013; pp 65–71] rather than by cavitation. These results obtained due to the high-speed visualisation of the contact behavior at nanoscale-confined interfaces allow for a microscopic understanding of the underwater adhesion of MSAMSs and may aid in further development of artificial adhesive microstructures for applications in predominantly liquid environments.

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The Development of Friction Pairs for Intermediate to Very High Duty Railway Applications

Proceedings of the Institution of Mechanical Engineers Part F Journal of Rail and Rapid Transit ◽

10.1243/pime_proc_1994_208_240_02 ◽

1994 ◽

Vol 208 (2) ◽

pp. 109-113

Author(s):

K D Dolbear ◽

J C Watson

Keyword(s):

High Speed ◽

High Performance ◽

Point Of View ◽

Railway Vehicle ◽

Vehicle Design ◽

Large Spread ◽

Challenges And Opportunities ◽

Ceramic Interfaces ◽

Very High

Railway vehicle service speeds are set to increase from the present 300 km/h. These developments are being spearheaded by the French, German, Italian and Japanese railways. It is also clear in other less glamorous areas such as freight and suburban operations, that the trends in vehicle design are going to put severe burdens on the braking technology available today. These initiatives included the advanced suburban bogie for British Railways. While it will be possible to squeeze some further improvements out of conventional products, it has become essential to initiate work on new materials which not only meet the immediate demands but address the requirements of the middle- and long-term. Some proposals such as carbon/carbon may be impractical from a cost point of view on anything other than exotic high-speed vehicles but studies involving ceramic to ceramic interfaces are proving interesting with a real possibility of providing high performance at an economical cost for a large spread of applications. The paper will discuss some of the challenges and opportunities to be grasped and solved.

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High Resolution Measurement of Wall Temperature Distribution During Forced Convective Boiling in a Single Minichannel

ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels: Parts A and B ◽

10.1115/fedsm-icnmm2010-30273 ◽

2010 ◽

Cited By ~ 4

Author(s):

Nils Schweizer ◽

Martin Freystein ◽

Peter Stephan

Keyword(s):

Heat Transfer ◽

Flow Pattern ◽

High Speed ◽

Bubbly Flow ◽

Video Recording ◽

Bond Number ◽

Heat Fluxes ◽

Convective Boiling ◽

Transfer Mechanisms ◽

Very High

Cooling systems incorporating convective boiling in mini- and microchannels achieve very high thermal performance. Although many investigations related to the subject have already been conducted, the basic phenomena of the heat transfer mechanisms are not yet fully understood. The development of empirical correlations based only on flow pattern maps does not lead to a deeper knowledge of the mechanisms. In this study a comprehensive measurement technique that was successfully adapted in pool boiling experiments [8,9] was used for the investigation of forced convective boiling of FC-72 in a single rectangular minichannel. This technique allows the measurement of the local temperature with very high spatial and temporal resolution. High speed video recording was used to observe the flow inside the minichannel. The inlet Reynolds number was kept constant for the first measurements to Re = 200 corresponding to a hydraulic diameter of the minichannel of 800 μm. The Bond number for the proposed setup is about Bo ≈ 1.2. Several flow pattern regimes such as bubbly flow, slug flow and partially dryout were observed for heat fluxes up to 25 kW / m2. From an energy balance at each pixel element of the thermographic recordings the local transient heat flux could be calculated and compared to the flow pattern video recordings. The results of the first experiments already give an indication about the heat transfer mechanisms at different flow regimes.

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Structural changes in silicon-on-insulator material during post-implantation annealing

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100145054 ◽

1986 ◽

Vol 44 ◽

pp. 736-737

Author(s):

C. O. Jung ◽

S. J. Krause ◽

S.R. Wilson

Keyword(s):

Integrated Circuits ◽

Oxide Layer ◽

High Speed ◽

Structural Changes ◽

Device Fabrication ◽

Silicon On Insulator ◽

High Quality ◽

Radiation Hardened ◽

Post Implantation ◽

Very High

Silicon-on-insulator (SOI) structures have excellent potential for future use in radiation hardened and high speed integrated circuits. For device fabrication in SOI material a high quality superficial Si layer above a buried oxide layer is required. Recently, Celler et al. reported that post-implantation annealing of oxygen implanted SOI at very high temperatures would eliminate virtually all defects and precipiates in the superficial Si layer. In this work we are reporting on the effect of three different post implantation annealing cycles on the structure of oxygen implanted SOI samples which were implanted under the same conditions.

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Very High Speed Integrated Circuits/Gallium Arsenide Electronics for Aircraft Engine Controls

10.23919/acc.1988.4790024 ◽

1988 ◽

Author(s):

Mark A. Overstreet

Keyword(s):

Gallium Arsenide ◽

Integrated Circuits ◽

High Speed ◽

Aircraft Engine ◽

Very High

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PROBLEMS AND TRENDS OF DEVELOPMENT OF BRANCHES OF CRIMINALISTIC TECHNOLOGY

International scientific journal Internauka Series Juridical Sciences ◽

10.25313/2520-2308-2020-11-6538 ◽

2017 ◽

Author(s):

Vitaliy Elyotnov ◽

Keyword(s):

Forensic Science ◽

Video Recording ◽

Theory And Practice ◽

Controversial Issues ◽

Forensic Photography ◽

Forensic Research ◽

Forensic Scientists ◽

Further Development

The article examines the key provisions of traditional and developing branches of forensic technology as a branch of the forensic science. The article analyzes modern publications of domestic and foreign scientists dedicated to the problems of forensic technology. Discussion issues and gaps existing in the theory and practice of such branches of forensic technology as forensic photography and video recording, forensic phonoscopy, forensic traceology, forensic weapons science, forensic documentation, forensic research of substances, materials and products, forensic registration, etc. The opinions of individual forensic scientists on the resolution of controversial issues of forensic technology are given. The scientific directions that have not received at present recognition of independent branches of forensic technology are indicated. The promising areas of research in the framework of the branches of forensic technology are named, the main trends of its further development are formulated.

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YSS HAP72

Alloy Digest ◽

10.31399/asm.ad.ts0779 ◽

2019 ◽

Vol 68 (10) ◽

Keyword(s):

Wear Resistance ◽

High Temperature ◽

Powder Metallurgy ◽

Tool Steel ◽

High Speed ◽

High Wear Resistance ◽

Bend Strength ◽

Temperature Performance ◽

Very High

Abstract YSS HAP72 is a powder metallurgy high-speed tool steel with a very high wear resistance. This datasheet provides information on composition, hardness, and bend strength. It also includes information on high temperature performance. Filing Code: TS-779. Producer or source: Hitachi Metals America Ltd.

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