57 research outputs found
Phytochemical and biological studies on volatiles and essential oils from plants of agri-food, ecological and ornamental interest
Plants are a rich source of valuable, cost effective and easily available natural products. Essential Oils (EOs) in particular are commercially important for many industrial applications, especially in pharmaceutical, agronomic, food, cosmetic and perfume industries. For their antiseptic, antimicrobial, analgesic, sedative, anti-inflammatory, spasmolytic properties, their pharmaceutical and food uses are widespread as alternatives to synthetic chemical products to protect the ecological equilibrium of environment and to decrease the utilization of synthetic drugs as antibiotics.
The object of this PhD project was the extraction and evaluation of many Essential Oils (EOs) and volatile compounds extracted from various plant species, with the aim to contribute to their chemical characterization especially for plants never studied before, or to exploit their industrial and biological use.
During the project were characterized the chemical compositions of essential oils and volatiles of Rhus coriaria, Anthemis maritima, Lavandula spp., Rosmarinus spp., Helichrysum spp., Citrus spp., Cinnamomum zeylanicum, and Salvia spp.. Statistical analysis were performed on the results obtained and then some biological tests were performed to find new applications for the essential oils
ALFALFA HI Data Stacking III. Comparison of environmental trends in HI gas mass fraction and specific star formation rate
It is well known that both the star formation rate and the cold gas content
of a galaxy depend on the local density out to distances of a few Megaparsecs.
In this paper, we compare the environmental density dependence of the atomic
gas mass fractions of nearby galaxies with the density dependence of their
central and global specific star formation rates. We stack HI line spectra
extracted from the Arecibo Legacy Fast ALFA survey centered on galaxies with UV
imaging from GALEX and optical imaging/spectroscopy from SDSS. We use these
stacked spectra to evaluate the mean atomic gas mass fraction of galaxies in
bins of stellar mass and local density. For galaxies with stellar masses less
than 10^10.5 M_sun, the decline in mean atomic gas mass fraction with density
is stronger than the decline in mean global and central specific star formation
rate. The same conclusion does not hold for more massive galaxies. We interpret
our results as evidence for ram-pressure stripping of atomic gas from the outer
disks of low mass satellite galaxies. We compare our results with the
semi-analytic recipes of Guo et al. (2011) implemented on the Millennium II
simulation. These models assume that only the diffuse gas surrounding satellite
galaxies is stripped, a process that is often termed "strangulation". We show
that these models predict relative trends in atomic gas and star formation that
are in disagreement with observations. We use mock catalogues generated from
the simulation to predict the halo masses of the HI-deficient galaxies in our
sample. We conclude that ram-pressure stripping is likely to become effective
in dark matter halos with masses greater than 10^13 M_sun.Comment: 12 pages, 10 figures. Accepted for publication in MNRA
Biobanking in the Year 2007
Biobanking is an emerging specialty in which competencies in cellular and molecular biology, medicine, genetics, cryobiology, bioengineering, information technology and ethics merge into a servic
ALFALFA HI Data Stacking I. Does the Bulge Quench Ongoing Star Formation in Early-Type Galaxies?
We have carried out an HI stacking analysis of a volume-limited sample of
~5000 galaxies with imaging and spectroscopic data from GALEX and the Sloan
Digital Sky Survey, which lie within the current footprint of the Arecibo
Legacy Fast ALFA (ALFALFA) Survey. Our galaxies are selected to have stellar
masses greater than 10^10 Msun and redshifts in the range 0.025<z<0.05. We
extract a sub-sample of 1833 "early-type" galaxies with inclinations less than
70deg, with concentration indices C>2.6 and with light profiles that are well
fit by a De Vaucouleurs model. We then stack HI line spectra extracted from the
ALFALFA data cubes at the 3-D positions of the galaxies from these two samples
in bins of stellar mass, stellar mass surface density, central velocity
dispersion, and NUV-r colour. We use the stacked spectra to estimate the
average HI gas fractions M_HI/M_* of the galaxies in each bin.
Our main result is that the HI content of a galaxy is not influenced by its
bulge. The average HI gas fractions of galaxies in both our samples correlate
most strongly with NUV-r colour and with stellar surface density. The relation
between average HI fraction and these two parameters is independent of
concentration index C. We have tested whether the average HI gas content of
bulge-dominated galaxies on the red sequence, differs from that of late-type
galaxies on the red sequence. We find no evidence that galaxies with a
significant bulge component are less efficient at turning their available gas
reservoirs into stars. This result is in contradiction with the "morphological
quenching" scenario proposed by Martig et al. (2009).Comment: 21 pages, 15 figures. Accepted for publication in MNRAS. Version with
high resolution figures available at
http://www.mpa-garching.mpg.de/GASS/pubs.ph
Evaluation of volatile constituents of Cochlospermum angolense.
The chemical composition of the essential oils obtained from the leaves and roots of Cochlospermum angolense (Welw) growing wild in Angola was analyzed for the first time by capillary gas chromatography (GC) and gas chromatography/mass spectrometry (GC-MS). The investigation led to the identification of 67 and 130 compounds from the leaves and roots, respectively. Both oils were strongly characterized by the presence of sesquiterpenoids (68.8% in the leaves and 53.2% in the roots), while monoterpenoids were present in minor percentages (9.8% in the leaves and 26.2% in the root). The main constituents of the leaves were germacrene D (9.4%), α-cadinol (7.4%) and 10- epi-cubenol (6.2%), while the most abundant compounds in the root essential oil were the sesquiterpenes β-caryophyllene (19.7%) and isoborneol (6.6%). The analysis by HS-SPME of the roots, leaves, fruits and seeds were also reported for the first time. Different volatile profiles were detected
Qualitative and quantitative determination of water in airborne particulate matter
Abstract. This paper describes the optimization and validation of a new simple method for the quantitative determination of water in atmospheric particulate matter (PM). The analyses are performed by using a coulometric Karl-Fisher system equipped with a controlled heating device; different water contributions are separated by the application of an optimized thermal ramp (three heating steps: 50–120 °C, 120–180 °C, 180–250 °C). The analytical performance of the method was verified by using standard materials containing 5.55% and 1% by weight of water. The recovery was greater than 95%; the detection limit was about 20 μg. The method was then applied to NIST Reference Materials (NIST1649a, urban particulate matter) and to real PM10 samples collected in different geographical areas. In all cases the repeatability was satisfactory (10–15%). When analyzing the Reference Material, the separation of four different types of water was obtained. In real PM10 samples the amount of water and its thermal profile differed as a function of the chemical composition of the dust. Mass percentages of 3–4% of water were obtained in most samples, but values up to about 15% were reached in areas where the chemical composition of PM is dominated by secondary inorganic ions and organic matter. High percentages of water were also observed in areas where PM is characterized by the presence of desert dust. A possible identification of the quality of water released from the samples was tried by applying the method to some hygroscopic compounds that are likely contained in PM (pure SiO2, Al2O3, ammonium salts, carbohydrates and dicarboxylic acids) and by comparing the results with those obtained from field samples
Activity of Salvia dolomitica and Salvia somalensis Essential Oils against Bacteria, Molds and Yeasts
Essential oils (EOs) fromSalvia dolomiticaandSalvia somalensis, widely employed in the cosmetic and perfume industry, were analyzed for composition and tested against bacterial and fungal pathogens isolated from clinical and environmental specimens. The analyses were carried out againstStaphylococcus aureus,Staphylococcus pseudointermedius,Pseudomonas aeruginosa,Escherichia coli,Streptococcus canis,Streptococcus pyogenes,Klebsiella pneumoniae,Proteus mirabilis,Microsporum canis,Microsporum gypseum,Trichophyton mentagrophytes,Aspergillus niger,Aspergillus flavus,Candida albicans,Candida krusei,Mucorsp. andTrichothecium roseum. Both EOs showed similar percentages of total monoterpenes and sesquiterpene hydrocarbons. The main constituents were 1,8-cineole andβ-caryophyllene inS.dolomiticaand bornyl acetate and camphor inS.somalensis. The selected EOs have no relevant antifungal or antibacterial activities if compared to conventional drugs
Gas-Bearing Early-Type Dwarf Galaxies in Virgo: Evidence for Recent Accretion
We investigate the dwarf (M_B> -16) galaxies in the Virgo cluster in the
radio, optical, and ultraviolet regimes. Of the 365 galaxies in this sample, 80
have been detected in HI by the Arecibo Legacy Fast ALFA survey. These
detections include 12 early-type dwarfs which have HI and stellar masses
similar to the cluster dwarf irregulars and BCDs. In this sample of 12, half
have star-formation properties similar to late type dwarfs, while the other
half are quiescent like typical early-type dwarfs. We also discuss three
possible mechanisms for their evolution: that they are infalling field galaxies
that have been or are currently being evolved by the cluster, that they are
stripped objects whose gas is recycled, and that the observed HI has been
recently reaccreted. Evolution by the cluster adequately explains the
star-forming half of the sample, but the quiescent class of early-type dwarfs
is most consistent with having recently reaccreted their gas.Comment: 18 pages, 9 figure
The GALEX Arecibo SDSS Survey. I. Gas Fraction Scaling Relations of Massive Galaxies and First Data Release
We introduce the GALEX Arecibo SDSS Survey (GASS), an on-going large program
that is gathering high quality HI-line spectra using the Arecibo radio
telescope for an unbiased sample of ~1000 galaxies with stellar masses greater
than 10^10 Msun and redshifts 0.025<z<0.05, selected from the SDSS
spectroscopic and GALEX imaging surveys. The galaxies are observed until
detected or until a low gas mass fraction limit (1.5-5%) is reached. This paper
presents the first Data Release, consisting of ~20% of the final GASS sample.
We use this data set to explore the main scaling relations of HI gas fraction
with galaxy structure and NUV-r colour. A large fraction (~60%) of the galaxies
in our sample are detected in HI. We find that the atomic gas fraction
decreases strongly with stellar mass, stellar surface mass density and NUV-r
colour, but is only weakly correlated with galaxy bulge-to-disk ratio (as
measured by the concentration index of the r-band light). We also find that the
fraction of galaxies with significant (more than a few percent) HI decreases
sharply above a characteristic stellar surface mass density of 10^8.5 Msun
kpc^-2. The fraction of gas-rich galaxies decreases much more smoothly with
stellar mass. One of the key goals of GASS is to identify and quantify the
incidence of galaxies that are transitioning between the blue, star-forming
cloud and the red sequence of passively-evolving galaxies. Likely transition
candidates can be identified as outliers from the mean scaling relations
between gas fraction and other galaxy properties. [abridged]Comment: 25 pages, 12 figures. Accepted for publication in MNRAS. Version with
high resolution figures available at
http://www.mpa-garching.mpg.de/GASS/pubs.ph
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