A suspended system for measuring the thermal properties of membranes is presented. The sensitive thermal measurement is based on the 3ω dynamic method coupled to a Völklein geometry. The device obtained using micro-machining processes allows the measurement of the in-plane thermal conductivity of a membrane with a sensitivity of less than 10nW/K (+/-5×10 −3 Wm −1 K −1 at room temperature) and a very high resolution (∆K/K = 10 −3 ). A transducer (heater/thermometer) centered on the membrane is used to create an oscillation of the heat flux and to measure the temperature oscillation at the third harmonic using a Wheatstone bridge set-up. Power as low as 0.1nanoWatt has been measured at room temperature. The method has been applied to measure thermal properties of low stress silicon nitride and polycrystalline diamond membranes with thickness ranging from 100 nm to 400 nm. The thermal conductivity measured on the polycrystalline diamond membrane support a significant grain size effect on the thermal transport.

We installed a source for ultracold neutrons at a new, dedicated spallation target at TRIUMF. The source was originally developed in Japan and uses a superfluid-helium converter cooled to 0.9 K. During an extensive test campaign in November 2017, we extracted up to 325 000 ultracold neutrons after a one-minute irradiation of the target, over three times more than previously achieved with this source. The corresponding ultracold-neutron density in the whole production and guide volume is 5.3 cm −3 . The storage lifetime of ultracold neutrons in the source was initially 37 s and dropped to 24 s during the eighteen days of operation. During continuous irradiation of the spallation target, we were able to detect a sustained ultracold-neutron rate of up to 1500 s −1 .Simulations of UCN production, UCN transport, temperature-dependent UCN yield, and temperature-dependent storage lifetime show excellent agreement with the experimental data and confirm that the ultracold-neutron-upscattering rate in superfluid helium is proportional to T 7 .

Comparative study between erbium and erbium oxide-doped diamondlike carbon films deposited by pulsed laser deposition technique

As a complementary tool to nanofluidics, biomolecular-based transport is envisioned for nanotechnological devices. We report a new method for guiding microtubule shuttles on multi-walled carbon nanotube tracks, aligned by dielectrophoresis on a functionalized surface. In the absence of electric field and in fluid flow, alignment is maintained. The directed translocation of kinesin propelled microtubules has been investigated using fluorescence microscopy. To our knowledge, this is the first demonstration of microtubules gliding along carbon nanotubes.

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We report the observation of kinesin driven quantum dots (QDs) trapped in a microtubule loop, allowing the investigation of moving QDs for a long time and an unprecedented long distance. The QD conjugates did not depart from our observational field of view, enabling the tracking of specific conjugates for more than 5 min. The unusually long run length and the periodicity caused by the loop track allow comparing and studying the trajectory of the kinesin driven QDs for more than 2 full laps, i.e., about 70 μm, enabling a statistical analysis of interactions of the same kinesin driven object with the same obstacle. The trajectories were extracted and analyzed from kymographs with a newly developed algorithm. Despite dispersion, several repetitive trajectory patterns can be identified. A method evaluating the similarity is introduced allowing a quantitative comparison between the trajectories. The velocity variations appear strongly correlated to the presence of obstacles. We discuss the reasons making this long continuous travel distances on the loop track possible.

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