5,103 research outputs found
Natural Polymers and Cosmeceuticals for a Healthy and Circular Life: The Examples of Chitin, Chitosan, and Lignin
The present review considers the design and introduction of new cosmeceuticals in the market, based on natural polymers and active molecules extracted from biomass, in a biomimetic strategy, starting with a consideration of the biochemical mechanisms, followed by natural precision biopolymer production. After introducing the contest of nanobiotechnology in relationship with its applicability for skin contact products and classifying the currently available sustainable polymers, some widely selected abundant biopolymers (chitin, chitosan, and lignin), showing specific functionalities (anti-microbial, anti-oxidant, anti-inflammatory, etc.), are described, especially considering the possibility to combine them in nanostructured tissues, powders, and coatings for producing new cosmeceuticals, but with potentialities in other sectors, such as biomedical, personal care, and packaging sectors. After observing the general increase in market wellness and beauty forecasts over the next few years, parallelisms between nano and macro scales have suggested that nanobiotechnology application expresses the necessity to follow a better way of producing, selecting, and consuming goods that will help to transform the actual linear economy in a circular economy, based on redesigning, reducing, recycling, and reusing
BeppoSAX observations of low power radio galaxies: possible detection of obscured nuclei
We present the first results of BeppoSAX observations of a small sample of
low brightness FRI radio galaxies. The flux of all the targets is consistent
with a thermal spectrum, as due to the presence of hot intracluster gas or
galactic corona. Moreover in three sources a non thermal absorbed spectrum can
be present in the MECS spectrum at energies larger than 7 keV, while for a
fourth object a high energy flux has been detected in the PDS instrument at
energies larger than 15 keV. This component could be related to the inner AGN
surrounded by an obscuring torus.Comment: 4 pages, LateX, 3 figures (included). Uses espcrc2.sty (included). To
appear in: "The Active X-ray Sky: Results from BeppoSAX and Rossi-XTE", Rome,
Italy, 21-24 October, 1997, Eds.: L. Scarsi, H. Bradt, P. Giommi and F. Fior
IC 4200: a gas-rich early-type galaxy formed via a major merger
We present the result of radio and optical observations of the S0 galaxy IC
4200. We find that the galaxy hosts 8.5 billion solar masses of HI rotating on
a ~90 deg warped disk extended out to 60 kpc from the centre of the galaxy.
Optical spectroscopy reveals a simple-stellar-population-equivalent age of 1.5
Gyr in the centre of the galaxy and V- and R-band images show stellar shells.
Ionised gas is observed within the stellar body and is kinematically decoupled
from the stars and characterised by LINER-like line ratios.We interpret these
observational results as evidence for a major merger origin of IC 4200, and
date the merger back to 1-3 Gyr ago.Comment: Accepted for publication in Astronomy & Astrophysics; 18 pages, 13
figures; the tables of Appendix C can be downloaded at
http://www.astro.rug.nl/~pserra/IC420
The lives of FR I radio galaxies
After a brief introduction to the morphological properties of FRI radio
sources, we discuss the possibility that FRI jets are relativistic at their
bases and decelerate quickly to non-relativistic velocities. From two-frequency
data we determine spectral index distributions and consequently the ages of FRI
sources. We show that in the large majority of cases synchrotron theory
provides unambiguous and plausible answers; in a few objects re-acceleration of
electrons may be needed. The derived ages are of the order 10^7-10^8 years, 2-4
times larger than the ages inferred from dynamical arguments and a factor 5-10
larger than the ages of FRII sources. The linear sizes of FRI and FRII sources
make it unlikely that many FRII's evolve into FRI's. A brief discussion is
given of the possibility that radio sources go through different cycles of
activity.Comment: 19 pages, including 13 figures, to appear in `Life Cycles of Radio
Galaxies', ed. J. Biretta et al., New Astronomy Review
Shock heating in the nearby radio galaxy NGC 3801
Original article can be found at: http://www.journals.uchicago.edu/ApJ/--Copyright American Astronomical SocietyPeer reviewe
Strong molecular hydrogen emission and kinematics of the multiphase gas in radio galaxies with fast jet-driven outflows
Observations of ionized and neutral gas outflows in radio-galaxies (RGs)
suggest that AGN radio jet feedback has a galaxy-scale impact on the host ISM,
but it is still unclear how the molecular gas is affected. We present deep
Spitzer IRS spectroscopy of 8 RGs that show fast HI outflows. All of these
HI-outflow RGs have bright H2 mid-IR lines that cannot be accounted for by UV
or X-ray heating. This suggests that the radio jet, which drives the HI
outflow, is also responsible for the shock-excitation of the warm H2 gas. In
addition, the warm H2 gas does not share the kinematics of the ionized/neutral
gas. The mid-IR ionized gas lines are systematically broader than the H2 lines,
which are resolved by the IRS (with FWHM up to 900km/s) in 60% of the detected
H2 lines. In 5 sources, the NeII line, and to a lesser extent the NeIII and NeV
lines, exhibit blue-shifted wings (up to -900km/s with respect to the systemic
velocity) that match the kinematics of the outflowing HI or ionized gas. The H2
lines do not show broad wings, except tentative detections in 3 sources. This
shows that, contrary to the HI gas, the H2 gas is inefficiently coupled to the
AGN jet-driven outflow of ionized gas. While the dissipation of a small
fraction (<10%) of the jet kinetic power can explain the dynamical heating of
the molecular gas, our data show that the bulk of the warm molecular gas is not
expelled from these galaxies.Comment: 26 pages, 15 figures, Accepted for ublication in Ap
Extended, regular HI structures around early-type galaxies
We discuss the morphology and kinematics of the HI of a sample of 30 southern
gas-rich early-type galaxies selected from the
HI Parkes All-Sky Survey (HIPASS). This is the largest collection of
high-resolution HI data of a homogeneously selected sample. Given the
sensitivity of HIPASS, these galaxies represent the most HI-rich early-type
galaxies. In two-thirds of the galaxies, we find the HI to be in a large,
regular disk- or ring-like structure that in some cases is strongly warped. In
the remaining cases we find the HI distributed in irregular tails or clouds
offset from the galaxy. The giant, regular HI structures can be up to ~200 kpc
in diameter and contain up to 10^10 M_sun of HI. The incidence of irregular HI
structures appears to be somewhat higher in elliptical galaxies, but the large,
regular structures are observed in both elliptical and S0 galaxies and are not
strictly connected to the presence of a stellar disk. If these two types of
galaxies are the result of different formation paths, this is not strongly
reflected in the characteristics of the HI. The size and the regular kinematics
of the HI structures imply that the neutral hydrogen must have settled in these
galaxies several Gyr ago. Merging as well as gas accretion from the IGM are
viable explanations for the origin of the gas in these galaxies. The average
column density of the HI is low so that little star formation is expected to
occur and these early-type galaxies can remain gas rich for very long periods
of time. The large HI structures likely represent key structures for tracing
the origin and evolution of these galaxies.Comment: Accepted for publication in A&A, 13 pages, 6 figures. A version with
full resolution figures is available at
http://www.astron.nl/~morganti/Papers/hipass.pd
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