48 research outputs found
Displacement Damage dose and DLTS Analyses on Triple and Single Junction solar cells irradiated with electrons and protons
Space solar cells radiation hardness is of fundamental importance in view of
the future missions towards harsh radiation environment (like e.g. missions to
Jupiter) and for the new spacecraft using electrical propulsion. In this paper
we report the radiation data for triple junction (TJ) solar cells and related
component cells. Triple junction solar cells, InGaP top cells and GaAs middle
cells degrade after electron radiation as expected. With proton irradiation, a
high spread in the remaining factors was observed, especially for the TJ and
bottom cells. Very surprising was the germanium bottom junction that showed
very high degradation after protons whereas it is quite stable against
electrons. Radiation results have been analyzed by means of the Displacement
Damage Dose method and DLTS spectroscopy.Comment: Abstract accepted for poster session at 2017 IEEE Nuclear and Space
Radiation Effects Conference, July 17-21, New Orlean
Wheat sprout extract induces changes on 20S proteasomes functionality.
Wheat sprouts contain a very high level of organic phosphates and a powerful cocktail of different molecules such as enzymes, reducing glycosides and polyphenols.
The antioxidant properties of wheat sprouts have been widely documented and it has been shown that they are able to protect DNA against free-radicals mediated oxidative damage. Furthermore, we have recently reported on the effects of several polyphenols on 20S proteasomes, underlying the dual role of epigallocatechin-3-gallate as an antioxidant and a proteasome effector in cancer cells.
The aim of this study was to investigate the effects of wheat sprout extracts on 20S proteasome functionality. Wheat sprout extracts have been analysed and characterized for their polyphenolic content using the Folin-Ciocalteau reagent and RP-HPLC technique. Comparing our data with a polyphenol standard mixture we identified five different polyphenols: gallic acid, epigallocatechin-3-gallate, epigallocatechin, epicatechin and catechin.
The treatment of isolated 20S proteasomes with the extract induced a gradual inhibition of all the tested components, ChT-L, T-L, PGPH and BrAAP, in both the complexes. At low extract concentration a slight activation of the enzyme was evident only for the BrAAP component of the constitutive enzyme and the ChT-L activity of the immunoproteasome. b-casein degradation rate decreased, particularly with the immunoproteasome.
Human Colon adenocarcinoma (Caco) cells, stimulated with 12-O-tetradecanoylphorbol-13-acetate, showed activation of the 20S proteasome activities at short incubation times and an increase in intracellular oxidative proteins. Cells treatment with wheat sprout extract led to proteasome inhibition in unstimulated cells and attenuated the effects mediated by TPA. Finally, exposure to the extract affected the expression levels of pro-apoptotic proteins
Smooth(er) Stellar Mass Maps in CANDELS: Constraints on the Longevity of Clumps in High-redshift Star-forming Galaxies
We perform a detailed analysis of the resolved colors and stellar populations
of a complete sample of 323 star-forming galaxies at 0.5 < z < 1.5, and 326
star-forming galaxies at 1.5 < z < 2.5 in the ERS and CANDELS-Deep region of
GOODS-South. Galaxies were selected to be more massive than 10^10 Msun and have
specific star formation rates above 1/t_H. We model the 7-band optical ACS +
near-IR WFC3 spectral energy distributions of individual bins of pixels,
accounting simultaneously for the galaxy-integrated photometric constraints
available over a longer wavelength range. We analyze variations in rest-frame
color, stellar surface mass density, age, and extinction as a function of
galactocentric radius and local surface brightness/density, and measure
structural parameters on luminosity and stellar mass maps. We find evidence for
redder colors, older stellar ages, and increased dust extinction in the nuclei
of galaxies. Big star-forming clumps seen in star formation tracers are less
prominent or even invisible on the inferred stellar mass distributions.
Off-center clumps contribute up to ~20% to the integrated SFR, but only 7% or
less to the integrated mass of all massive star-forming galaxies at z ~ 1 and z
~ 2, with the fractional contributions being a decreasing function of
wavelength used to select the clumps. The stellar mass profiles tend to have
smaller sizes and M20 coefficients, and higher concentration and Gini
coefficients than the light distribution. Our results are consistent with an
inside-out disk growth scenario with brief (100 - 200 Myr) episodic local
enhancements in star formation superposed on the underlying disk.
Alternatively, the young ages of off-center clumps may signal inward clump
migration, provided this happens efficiently on the order of an orbital
timescale.Comment: Accepted by The Astrophysical Journal, 27 pages, 1 table, 16 figure
Multi-Wavelength View of Kiloparsec-Scale Clumps in Star-Forming Galaxies at z~2
This paper studies the properties of kiloparsec-scale clumps in star-forming
galaxies at z~2 through multi-wavelength broad band photometry. A sample of 40
clumps is identified through auto-detection and visual inspection from 10
galaxies with 1.5<z<2.5 in the Hubble Ultra Deep Field, where deep and
high-resolution HST/WFC3 and ACS images enable us to resolve structures of z~2
galaxies down to kpc scale in the rest-frame UV and optical bands as well as to
detect clumps toward the faint end. The physical properties of clumps are
measured through fitting spatially resolved seven-band (BVizYJH) spectral
energy distribution to models. On average, the clumps are blue and have similar
median rest-frame UV--optical color as the diffuse components of their host
galaxies, but the clumps have large scatter in their colors. Although the star
formation rate (SFR)--stellar mass relation of galaxies is dominated by the
diffuse components, clumps emerge as regions with enhanced specific SFRs,
contributing individually ~10% and together ~50% of the SFR of the host
galaxies. However, the contributions of clumps to the rest-frame UV/optical
luminosity and stellar mass are smaller, typically a few percent individually
and ~20% together. On average, clumps are younger by 0.2 dex and denser by a
factor of 8 than diffuse components. Clump properties have obvious radial
variations in the sense that central clumps are redder, older, more extincted,
denser, and less active on forming stars than outskirts clumps. Our results are
broadly consistent with a widely held view that clumps are formed through
gravitational instability in gas-rich turbulent disks and would eventually
migrate toward galactic centers and coalesce into bulges. Roughly 40% of the
galaxies in our sample contain a massive clump that could be identified as a
proto-bulge, which seems qualitatively consistent with such a bulge-formation
scenario.Comment: Accepted by ApJ. This updated version matches the in-press one. 50
pages (single column), 10 figures, 3 table