Measurements of Surfactant Squeeze-out Using Magnetically-Levitated Liquid Bridges

Liquid bridges: Columns of liquid supported by two solid surfaces. These are generally opposing right circular cylinders in 0g. For a cylindrical bridge of length L and diameter d, in zero g, the maximum slenderness ratio Lambda [L/d] = pi [Rayleigh]. In the presence of gravity the cylindrical shape of an axisymmetric bridge tends to deform. Fluid has a volumetric magnetic susceptibility X. Magnetic levitation has numerous applications in studies of fluids, "soft" and "hard" condensed matter physics, and biophysic

The Appearance of Ferrielectric Phases in Confined Liquid Crystal Studied by Photon Correlation Spectroscopy

The influence of confinement on the dynamic properties and appearance of ferrielectric phases has been investigated by dynamic light scattering, performed in the bulk AFLC as well as confined in 200 8, and 2000 8, cylindrical pores. The analysis of the experimental results shows that the ferrielectric phases are not formed in 200 A pores, while they appear in 2000 8, pores as well as in bulk

A Birefringence Relaxation Determination of Rotational Diffusion of Magnetotactic Bacteria

The orientational relaxation of the magnetotactic bacterium Aquaspirillum magnetotacticum is observed by the decay of the optical birefringence upon switching off an aligning magnetic field. The data yield a rotational diffusion constant Dr ≅ 0.13 s1 and information about cell sizes that is consistent with optical microscopy data

Drone IV - The Final Chapter (Parasol Drone)

Project to create a controllable, aerial drone capable of providing shading from UVA/UVB radiation. Consumers will be able to participate in outdoor activities (run, walk, play sports, etc.) while being protected from the sun. Shading mechanism can open and close midflight with the press of a button. No prior experience necessary for operation. Appropriate for all weather conditions except rain or snow (electronics of drone should not get wet). Adult supervision is necessary for children under the age of twelve

Viscoelastic Properties of a Liquid-Crystalline Monomer and Its Dimer

Quasielastic-light-scattering measurements are reported for a dialkoxyphenylbenzoate monomer and its dimer in their respective nematic phases. The splay and twist elastic moduli of the dimer are found to be nearly independent of molecular length. The dimer\u27s bend modulus, however, shows an anomalous increase with decreasing temperature well below the nematic-isotropic phase transition. Monomer viscosities are consistent with typical literature values, although γ1/ηsplay and ηbend seem to be larger than expected for the dimer, where γ1 is the twist viscosity. The results are discussed in terms of viscoelastic properties of semiflexible rods. The elastic properties in particular are in good agreement with a recent model by Terentjev and Petschek (unpublished)

OPTICAL DETERMINATION OF SMECTIC A LAYER SPACING IN FREELY SUSPENDED THIN FILMS

Optical measurements of smectic A layer spacings in freely suspended thin films of three liquid crystals are reported. Although the measured spacings are close to those reported for the bulk, some anomalous behavior is noted. In addition, we report that the smectic A phase in the film can exist at unusually high temperatures

The long way to bilingualism: the peculiar case of multilingual South Tyrol

In the present contribution we discuss the challenges and the results of learning a second language in South Tyrol, the multilingual border region in northern Italy where the autochthonous German- and Ladinspeaking communities have cohabited with the Italian-speaking community since the end of the First World War. The picture resulting from the data collected in the Kolipsi project (Eurac/DiScoF), an extensive linguistic and psychosocial investigation about South Tyrolean secondary school pupils now in its second edition, gives precious inputs to all entities that intervene in the process of attitude formation and change, ranging from the family environment to politics.En el presente trabajo, debatimos los retos y los resultados del proceso de aprendizaje de segundas lenguas en el Tirol del Sur, la región fronteriza multilingüe del norte de Italia donde las comunidades autóctonas hablantes de alemán y ladino han convivido con la comunidad italohablante desde el fin de la Primera Guerra Mundial. La imagen resultante de los datos recogidos en el proyecto Kolipsi (Eurac/DiScoF), una investigación abarcadora tanto lingüística como psicosocial sobre alumnado de secundaria del Tirol del Sur, proporciona información muy valiosa a todas las entidades que intervienen en el proceso de la formación y el cambio de las actitudes, desde el entorno familiar hasta el ámbito de la política

Microaerobic Conditions Are Required for Magnetite Formation Within \u3ci\u3eAquaspirillum magnetotacticum\u3c/i\u3e

The amount of magnetite (Fe3O4) within magnetosomes of the microaerophilic bacterium Aquaspirillum magnetotacticum varies with oxygen and nitrogen supply. The development of optical methods for directly measuring cell magnetism in culture samples has enabled us to quantitate bacterial Fe3O4 yields. We measured final cell yields, average cell magnetic moments, and magnetosome yields of growing cells. Cultures were grown with NO3-, NH4+, or both, in sealed, unshaken vials with initial headspace Po2 values ranging from 0 (trace) to 21 kPa. More than 50% of cells had detectable magnetosomes only when grown in the range of 0.5-5.0 kPa O2. Optimum cell magnetism (and Fe3O4 formation) occurred under microaerobic conditions (initial headspace Po2 of 0.5-1 kPa) regardless of the N source. At optimal conditions for Fe3O4 formation, denitrifying cultures produced more of this mineral than those growing with O2 as the sole terminal electron acceptor. This suggests that competition for O2 exists between processes involving respiratory electron disposal and Fe3O4 formation. Oxygen may also be required for Fe3O4 formation by other species of magnetotactic bacteria. Bacterial Fe3O4 appears to persist in sediments after death and lysis of cells. The presence of bacterial Fe3O4 in the fossil and paleomagnetic records may be of use as a retrospective indicator of sedimentation that has occurred in microaerobic waters

Nematic electroclinic effect in a carbon nanotube-doped achiral liquid crystal

A small quantity of carbon nanotubes dispersed in an achiral liquid crystal matrix transmits chirality a short distance into the LC, and the LC+CNT mixture is found to exhibit a bulklike electroclinic effect in the nematic phase. The magnitude of the effect increases rapidly on cooling, showing significant pretransitional behavior on approaching the nematic -smectic-A transition temperature (T NA ) from above. The variation of the electroclinic coefficient is negligible over the frequency range 100 Hz -100 kHz in the in the nematic phase well above T NA and in the smectic-A phase, whereas the electroclinic coefficient falls off significantly with increasing frequency just above T NA

Contrôle magnétique d'interfaces statiques : application à l'instabilité de Rayleigh-Taylor

Déformer de manière statique l'interface entre deux fluides est susceptible de présenter un intérêt en dynamique des interfaces. A l'aide de champs magnétiques modulés spatialement, notre équipe a développé une méthode permettant de créer des interfaces non-planes et de forme arbitraire entre deux fluides non miscibles, l'un étant rendu paramagnétique. Nous présenterons ici l'application de cette technique au contrôle de l'interface initiale d'un empilement gravitationnellement instable (de l'eau paramagnétique sur de l'huile) dans le cadre d'une étude sur l'instabilité de Rayleigh-Taylor