2,119 research outputs found
New technologies in general aviation
This research explored the technological needs of GA pilots at international
levels. Overall, single pilot operators tend to value costs as the most important feature of
any technology, followed by technology that helps with pre-flight tasks as well as during
flight. Remote monitoring, post-flight analysis and 3-D displays are technological
features of lesser importance
Synthesis, resolution, and absolute configuration determination of a vicinal amino alcohol with axial chirality. Application to the synthesis of new box and pybox ligands
New racemic vicinal amino alcohol derivatives with 4-benzylidenecyclohexane skeleton and axial chirality have been prepared. A preparatively easy and efficient protocol for resolution of the N-benzoylamino alcohol is described. Using a 250 x 20 mm (L x ID) Chiralpak (R) IA column, and the appropriate mixture of n-hexane/ethanol/chloroform as eluent, both enantiomers of N-benzoylamino alcohol 3 are obtained with >99% enantiomeric excess (ee) by successive injections of a solution of the racemic sample in chloroform. The obtained axially chiral vicinal amino alcohol is used to synthesize structurally novel bisoxazoline ligands in high yields
Properties of aluminium nodules foamed with concentrated solar energy
Commercial aluminium foam filled structures and sandwich panels are available for structural applications. As alternative to these materials, small granular foamed pieces are proposed to fill structures as well as sandwich panels. On the present work, foam precursors are obtained by Powder Metallurgy (PM) route, using natural calcium carbonate as foaming agent instead of titanium hydride. Extruded precursor bars were cut into small pieces (around 4.5 mm long and 5mm in diameter). Foaming treatment was carried out on two different ways: electrical preheated furnace and by solar furnace. Foamed nodules presented a low cell size, density e.g. 0.67 g/cm3 to 0.88 g/cm3 and a height/diameter ratio between 0.72 and 0.84 as a function of precursor size. These properties depend on the foaming particle size, foaming cycle and precursor dimensions. Carbonate precursors are easily foamed by concentrated solar energy, due to the lower risk of cell collapse than with hydride precursors, resulting from cell stabilization by oxide skin formation into cells and a low degree of foamed nodules bonding
Tratamiento térmico de espumación de precursores de aluminio-silicio en horno solar de lecho fluidificado
La fabricación de espumas de aluminio de poro cerrado mediante técnicas pulvimetalúrgias, conlleva una etapa de calentamiento del material (precursor) hasta su fusión y la formación de la espuma. En el presente trabajo, como continuación de los trabajos con energía solar concentrada aplicada directamente a la espumación de precursores Al10Si+0.8%TiH2, se han sometido al tratamiento de espumación en un horno solar de lecho fluidificado con el objetivo de obtener un tratamiento en volumen más homogéneo y uniforme, de manera que se puedan determinar la viabilidad del tratamiento, el procedimiento y los tiempos de residencia necesarios para llevar a cabo este proceso de manera discontinua o preindustrial. Así se han obtenido espumas 0,68 g/cm3 de densidad sin colapso de poros o decantación de aluminio, si bien como consecuencia del calentamiento preferencial por la base del molde, las espumas obtenidas presentan un tamaño de poro ligeramente más grande en la base de la espuma
Millimagnitude Photometry for Transiting Extrasolar Planetary Candidates IV: The Puzzle of the Extremely Red OGLE-TR-82 Primary Solved
We present precise new V, I, and K-band photometry for the planetary transit
candidate star OGLE-TR-82. Good seeing V-band images acquired with VIMOS
instrument at ESO VLT allowed us to measure V=20.6+-0.03 mag star in spite of
the presence of a brighter neighbour about 1" away. This faint magnitude
answers the question why it has not been possible to measure radial velocities
for this object. One transit of this star has been observed with GMOS-S
instrument of GEMINI-South telescope in i and g-bands. The measurement of the
transit allows us to verify that this is not a false positive, to confirm the
transit amplitude measured by OGLE, and to improve the ephemeris. The transit
is well defined in i-band light curve, with a depth of A_i=0.034 mag. It is
however, less well defined, but deeper (A_g=0.1 mag) in the g-band, in which
the star is significantly fainter. The near-infrared photometry obtained with
SofI array at the ESO-NTT yields K=12.2+-0.1 and V-K=8.4+-0.1, so red that it
is unlike any other transit candidate studied before. Due to the extreme nature
of this object, we have not yet been able to measure velocities for this star,
but based on the new data we consider two different possible configurations:(1)
a nearby M7V star, or (2) a blend with a very reddened distant red giant. The
nearby M7V dwarf hypothesis would give a radius for the companion of
R_p=0.3+-0.1 R_J, i.e. the size of Neptune. Quantitative analysis of near-IR
spectroscopy finally shows that OGLE-TR-82 is a distant, reddened metal poor
early K giant. This result is confirmed by direct comparison with stellar
templates that gives the best match for a K3III star. Therefore, we discard the
planetary nature of the companion. Based on all the new data, we conclude that
this system is a main-sequence binary blended with a background red giant.Comment: 26 pages, 9 figures, ApJ accepte
Osteoarthritis:Mechanistic Insights, Senescence, and Novel Therapeutic Opportunities
Osteoarthritis (OA) is the most common joint disease. In the last years, the research community has focused on understanding the molecular mechanisms that led to the pathogenesis of the disease, trying to identify different molecular and clinical phenotypes along with the discovery of new therapeutic opportunities. Different types of cell-to-cell communication mechanisms have been proposed to contribute to OA progression, including mechanisms mediated by connexin43 (Cx43) channels or by small extracellular vesicles. Furthermore, changes in the chondrocyte phenotype such as cellular senescence have been proposed as new contributors of the OA progression, changing the paradigm of the disease. The use of different drugs able to restore chondrocyte phenotype, to reduce cellular senescence and senescence-associated secretory phenotype components, and to modulate ion channel activity or Cx43 appears to be promising therapeutic strategies for the different types of OA. In this review, we aim to summarize the current knowledge in OA phenotypes related with aging and tissue damage and the new therapeutic opportunities currently available
Embryonic Amygdalar Transplants in Adult Rats with Motor Cortex Lesions: A Molecular and Electrophysiological Analysis
Transplants of embryonic nervous tissue ameliorate motor deficits induced by motor cortex lesions in adult animals. Restoration of lost brain functions has been recently shown in grafts of homotopic cortical origin, to be associated with a functional integration of the transplant after development of reciprocal host–graft connections. Nevertheless little is known about physiological properties or gene expression profiles of cortical implants with functional restorative capacity but no cortical origin. In this study, we show molecular and electrophysiological evidence supporting the functional development and integration of heterotopic transplants of embryonic amygdalar tissue placed into pre-lesioned motor cortex of adult rats. Grafts were analyzed 3 months post-transplantation. Using reverse transcriptase quantitative polymerase chain reaction, we found that key glutamatergic, GABAergic, and muscarinic receptors transcripts were expressed at different quantitative levels both in grafted and host tissues, but were all continuously present in the graft. Parallel sharp electrode recordings of grafted neurons in brain slices showed a regular firing pattern of transplanted neurons similar to host amygdalar pyramidal neurons. Synaptic connections from the adjacent host cortex on grafted neurons were electrophysiologically investigated and confirmed our molecular results. Taken together, our findings indicate that grafted neurons from a non-cortical, non-motor-related, but ontogenetical similar source, not only received functionally effective contacts from the adjacent motor cortex, but also developed electrophysiological and gene expression patterns comparable to host pyramidal neurons; suggesting an interesting tool for the field of neural repair and donor tissue in adults
- …