Spontaneous mechanical oscillation of a DC driven single crystal

There is a large interest to decrease the size of mechanical oscillators since this can lead to miniaturization of timing and frequency referencing devices, but also because of the potential of small mechanical oscillators as extremely sensitive sensors. Here we show that a single crystal silicon resonator structure spontaneously starts to oscillate when driven by a constant direct current (DC). The mechanical oscillation is sustained by an electrothermomechanical feedback effect in a nanobeam, which operates as a mechanical displacement amplifier. The displacement of the resonator mass is amplified, because it modulates the resistive heating power in the nanobeam via the piezoresistive effect, which results in a temperature variation that causes a thermal expansion feedback-force from the nanobeam on the resonator mass. This self-amplification effect can occur in almost any conducting material, but is particularly effective when the current density and mechanical stress are concentrated in beams of nano-scale dimensions

State-of-the-art microscopy to understand islets of Langerhans:what to expect next?

The discovery of Langerhans and microscopic description of islets in the pancreas were crucial steps in the discovery of insulin. Over the past 150 years, many discoveries in islet biology and type 1 diabetes have been made using powerful microscopic techniques. In the past decade, combination of new probes, animal and tissue models, application of new biosensors and automation of light and electron microscopic methods and other (sub)cellular imaging modalities have proven their potential in understanding the beta cell under (patho)physiological conditions. The imaging evolution, from fluorescent jellyfish to real-time intravital functional imaging, the revolution in automation and data handling and the increased resolving power of analytical imaging techniques are now converging. Here, we review innovative approaches that address islet biology from new angles by studying cells and molecules at high spatiotemporal resolution and in live models. Broad implementation of these cellular imaging techniques will shed new light on cause/consequence of (mal)function in islets of Langerhans in the years to come

Corrosion protection of metallic waste packages using thermal sprayed ceramic coatings

Ceramic coated carbon steel coupons were corrosion tested in water with dissolved salts to simulate exposure to evaporation concentrated groundwater in an underground nuclear repository. Metallography revealed no corrosion at the ceramic metal interface of dense coatings, even though electrical measurements demonstrated that the coatings were slightly porous. Experimental results and a model to predict corrosion rates influenced by a porous ceramic coating and coating lifetimes are presente

An open microfluidic design for contact angle measurement

Spontaneous capillary flow in open microchannels is a phenomenon driven by surface energies. The contact angle that the liquid forms with the channel's substrate material and the cross-section of the microchannel decide whether liquid from a connected reservoir will automatically fill the channel or not. In this work we show how this behavior can be used to design a passive contact angle measurement device (CAMD) based on parabolic open microgrooves. To that end, we present a theory of open capillary flow in such microgrooves and compare the results to minimal energy surface simulations. Additionally, we discuss that the condition for capillary flow of curved microchannels is essentially equal to the condition for their straight counterparts having the same cross-section.Lastly, we present two demonstrators of our CAMD made out of micromilled poly(methyl methacrylate). The devices consist of five open microchannels with different cross-sections which are connected to a common liquid reservoir. We show how the behavior of a liquid placed into that reservoir can be used to evaluate the contact angle between the liquid and the substrate material. A comparison to conventional contact angle goniometry shows that our approach is able to successfully estimate contact angles with an accuracy of 10° by design which can be improved by employing a greater number of microchannels. Since our devices were automatically designed and can be tuned to specific applications, this provides an easy approach to include contact angle measurement into existing lab-on-a-chip devices

First negative halogen beams produced at PSBooster-ISOLDE

Chemically pure radioactive halogen beams have interesting potentials for solid state and nuclear physics, for instance for implantation studies or in precise -decay measurements. They can be produced as positive ions by the ISOL approach, with possible isobaric contaminations, or as pure negative ion beams, with a LaB6 negative surface ion source..

EURISOL High Power Oxide Target Tests at TRIUMF

Project proposal to test an oxide target at high power at TRIUM

Design and test of a two-body target unit for 100kW solid targets

Design and online tests at CERN-ISOLDE of a \\\"bivalve\\\" target unit with two CaO containers with merging lines an remotely actuated valves into a single MK7 cold FEBIAD ion source. Details on the development of the unit and online results are provided

Feasibility study for the 100kW direct targets

Tools and developments required to go from today\'s operating standards to the 100kW benchmark targets