Helsinki University of Technology

About: Helsinki University of Technology is a based out in . It is known for research contribution in the topics: Thin film & Vortex. The organization has 8962 authors who have published 20136 publications receiving 723787 citations. The organization is also known as: TKK & Teknillinen korkeakoulu.

The water absorption of sapwood and heartwood of Scots pine and Norway spruce heat-treated at 170 ◦ C, 190 ◦ C, 210 ◦ C and 230 ◦ C

Abstract: Heat-treatment changes the chemical and physical properties of wood. Wood polymers are degraded, dimensional stability is enhanced, equilibrium moisture content is lowered, colour darkens and biological durability is increased. The properties of heat-treated wood have been researched considerably, but the differences between sapwood and heartwood have not been reported separately. In this research, water absorption differences between sapwood and heartwood of Scots pine and Norway spruce heat-treated at temperatures 170 °C, 190 °C, 210 °C and 230 °C were investigated. The results were compared to industrially kiln-dried reference samples. Water absorption was determined with a floating test based on the EN 927-5 standard. The heartwood of both wood species absorbed less water than sapwood. Heat-treatment evidently decreased the water absorption of spruce and pine heartwood. The higher the heat-treating temperature, the lower the amount of absorbed moisture. However, a very interesting exception was pine sapwood, whose water absorption actually increased with heat-treatment after the three lowest heat-treatment temperatures compared to the reference material. Water absorption did not decrease until the heat-treatment temperature was 230 °C.

Superhydrophobic tracks for low-friction, guided transport of water droplets.

Abstract: anti-fogging, [ 6 ] anti-icing, [ 7 ] buoyancy [ 8 ] and drag reduction. [ 9 ] By defi nition, a surface is superhydrophobic if the contact angle between a water drop and the surface at the solid/liquid/air interface is larger than 150 ° , and the contact angle hysteresis is small, i.e., drops readily slide or roll off when the surface is tilted slightly. [ 10–12 ] Here we explore the feasibility of using superhydrophobicity for guided transport of water droplets. We demonstrate a simple yet effi cient approach for droplet transport, in which the droplet is moving on a superhydrophobic surface, using gravity or electrostatic forces as the driving force for droplet transportation and using tracks with vertical walls as gravitational potential barriers to design trajectories. Although the slope of the platform is as small as a few degrees, the drops move at a considerable speed up to 14 cm s − 1 , even in highly curved trajectories. We further demonstrate splitting of a droplet using a superhydrophobic knife and drop-size selection using superhydrophobic tracks. These concepts may fi nd applications in droplet microfl uidics and lab-on-a-chip systems where single droplets with potential analytes are manipulated. [ 13–16 ]

Measurement and evaluation of technology transfer: review of technology transfer mechanisms and indicators

Abstract: The locus of industrial innovation is shifting toward industrial networks, in which parallel development processes in individual interconnected actors frequently dominate. This development presents new challenges for the measurement and evaluation of technology transfer. In this paper, various technology transfer mechanisms and indicators are classified and discussed. Technology transfer mechanisms and indicators are found to be phase, interface and component dependent. It is argued that process indicators should be further developed to complement the picture given by traditional input–output indicators of technology transfer.

Profiling multilayer structures with monoenergetic positrons.

Abstract: Variable-energy (0--25 keV) positron stopping and annihilation behavior is studied in a multilayer structure, which has subsequent (\ensuremath{\sim}3000-A\r{}-thick) ZnS and ${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ layers on a glass substrate. Direct information on positron slowing-down properties is obtained. The positron implantation profile is shown to possess the shape of a derivative of a Gaussian function, in contrast to the more commonly used exponential profile. The mean positron penetration depth varies with incident positron energy E (in keV) as z\ifmmode\bar\else\textasciimacron\fi{}=[4.0(3) \ensuremath{\mu}g/${\mathrm{cm}}^{2}$](E${)}^{1.62(5)}$. The feasibility of the present technique for depth profiling of heterogeneous samples is considered. The accuracy of determining the positions of the interfaces is typically less than 100 A\r{} in the present system. The mobility of positrons in ZnS and ${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ layers is observed to be very low. This corresponds to positron trapping into structural defects with a relatively high concentration.