Carotenoids are lipophilic isoprenoid compounds synthesized by all photosynthetic organisms and some non-photosynthetic prokaryotes and fungi. With some notable exceptions, animals (including humans) ...do not produce carotenoids de novo but take them in their diets. In photosynthetic systems carotenoids are essential for photoprotection against excess light and contribute to light harvesting, but perhaps they are best known for their properties as natural pigments in the yellow to red range. Carotenoids can be associated to fatty acids, sugars, proteins, or other compounds that can change their physical and chemical properties and influence their biological roles. Furthermore, oxidative cleavage of carotenoids produces smaller molecules such as apocarotenoids, some of which are important pigments and volatile (aroma) compounds. Enzymatic breakage of carotenoids can also produce biologically active molecules in both plants (hormones, retrograde signals) and animals (retinoids). Both carotenoids and their enzymatic cleavage products are associated with other processes positively impacting human health. Carotenoids are widely used in the industry as food ingredients, feed additives, and supplements. This review, contributed by scientists of complementary disciplines related to carotenoid research, covers recent advances and provides a perspective on future directions on the subjects of carotenoid metabolism, biotechnology, and nutritional and health benefits.
Based on high-resolution spectra obtained with the MIKE spectrograph on the Magellan telescopes, we present detailed elemental abundances for 20 red giant stars in the outer Galactic disk, located at ...Galactocentric distances between 9 and 13 kpc. The outer disk sample is complemented with samples of red giants from the inner Galactic disk and the solar neighborhood, analyzed using identical methods. For Galactocentric distances beyond 10 kpc, we only find chemical patterns associated with the local thin disk, even for stars far above the Galactic plane. Our results show that the relative densities of the thick and thin disks are dramatically different from the solar neighborhood, and we therefore suggest that the radial scale length of the thick disk is much shorter than that of the thin disk. We make a first estimate of the thick disk scale length of L thick = 2.0 kpc, assuming L thin = 3.8 kpc for the thin disk. We suggest that radial migration may explain the lack of radial age, metallicity, and abundance gradients in the thick disk, possibly also explaining the link between the thick disk and the metal-poor bulge.
The atmospheric parameters of the components of the 16 Cygni binary system, in which the secondary has a gas giant planet detected, are measured accurately using high-quality observational data. ...Abundances relative to solar are obtained for 25 elements with a mean error of Delta *s(X/H) = 0.023 dex. The fact that 16 Cyg A has about four times more lithium than 16 Cyg B is normal considering the slightly different masses of the stars. The abundance patterns of 16 Cyg A and B, relative to iron, are typical of that observed in most of the so-called solar twin stars, with the exception of the heavy elements (Z > 30), which can, however, be explained by Galactic chemical evolution. Differential (A-B) abundances are measured with even higher precision ( Delta *s( Delta *DX/H) = 0.018 dex, on average). We find that 16 Cyg A is more metal-rich than 16 Cyg B by Delta *DM/H = +0.041 ? 0.007 dex. On an element-to-element basis, no correlation between the A-B abundance differences and dust condensation temperature (T C) is detected. Based on these results, we conclude that if the process of planet formation around 16 Cyg B is responsible for the observed abundance pattern, the formation of gas giants produces a constant downward shift in the photospheric abundance of metals, without a T C correlation. The latter would be produced by the formation of terrestrial planets instead, as suggested by other recent works on precise elemental abundances. Nevertheless, a scenario consistent with these observations requires the convective envelopes of 1 M stars to reach their present-day sizes about three times quicker than predicted by standard stellar evolution models.
We present a new set of oscillator strengths for 142 $\ion{Fe}{ii}$ lines in the wavelength range 4000–8000 Å. Our gf-values are both accurate and precise, because each multiplet was globally ...normalized using laboratory data (accuracy), while the relative gf-values of individual lines within a given multiplet were obtained from theoretical calculations (precision). Our line list was tested with the Sun and high-resolution ($R \approx 10^5$), high-S/N (≈700–900) Keck+HIRES spectra of the metal-poor stars HD 148816 and HD 140283, for which line-to-line scatter (σ) in the iron abundances from $\ion{Fe}{ii}$ lines as low as 0.03, 0.04, and 0.05 dex are found, respectively. For these three stars the standard error in the mean iron abundance from $\ion{Fe}{ii}$ lines is negligible ($\sigma_\mathrm{mean} \leq 0.01$ dex). The mean solar iron abundance obtained using our gf-values and different model atmospheres is $A_{\rm Fe} = 7.45 (\sigma = 0.02$).
There is an increasing trend in the consumption of olive oil, especially extra virgin olive oil, due to its health benefits. These health benefits are mainly correlated to health-promoting components ...of olive oil such as polyphenols, tocopherols, and carotenoids, positive effects of olive oil on the inhibition of foodborne pathogens, stimulation of the growth of beneficial microorganisms, and its antioxidant activity. These attributes make olive oil one of the leading healthy edible oils worldwide.
The current study overviews the recent findings on the health benefits of olive oil consumption including its effects on gut microbiota, its antioxidant activity, and its ability in preventing cardiovascular disease (CVD). In addition, the potential mechanism involved in these health-promoting effects are discussed.
Key findings and conclusions: This study showed that olive oils originated from various regions of the world can pose some positive effects on gut microbiota. Moreover, this edible oil (especially the extra virgin type) can prevent CVD due to the high levels of valuable bioactive components including phenolic compounds (e.g. oleocanthal, tyrosol, hydroxytyrosol, oleuropein, and oleuropein aglycone) and the presence of highly bioavailable health-promoting carotenoids such as provitamin A, β-carotene, and lutein. Furthermore, the oral intake of extra virgin olive oil can be beneficial in preventing cancer and type 2 diabetes. Therefore, the consumption of olive oil, especially the extra virgin type, can be recommended not only because of its healthy fatty acid profile (particularly oleic acid) but also due to valuable positive effects of its bioactive components on human health.
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•Olive oil, especially,extra virgin olive oil (EVOO), contains bioactive compounds (e.g., polyphenols).•Fatty acid profile of EVOO is rich in oleic acid which possess beneficial health effects.•EVOO could improve health through positive effects on gut microbiota.•EVOO could reduce the risk of cardiovascular diseases.•EVOO could reduce the risk of hypertension, type 2 diabetes, and cancer.
Carotenoids are fascinating compounds that can be converted into many others, including retinoids that also play key roles in many processes. Although carotenoids are largely known in the context of ...food science, nutrition, and health as natural colorants and precursors of vitamin A (VA), evidence has accumulated that even those that cannot be converted to VA may be involved in health‐promoting biological actions. It is not surprising that carotenoids (most notably lutein) are among the bioactives for which the need to establish recommended dietary intakes have been recently discussed. In this review, the importance of carotenoids (including apocarotenoids) and key derivatives (retinoids with VA activity) in agro‐food with relevance to health is summarized. Furthermore, the European Network to Advance Carotenoid Research and Applications in Agro‐Food and Health (EUROCAROTEN) is introduced. EUROCAROTEN originated from the Ibero‐American Network for the Study of Carotenoids as Functional Food Ingredients (IBERCAROT).
Carotenoids are versatile natural compounds that can be converted into a myriad of other compounds, including compounds with vitamin A activity. Carotenoids are also very important as natural colors and therefore in food acceptability. In recent decades, evidence has accumulated that carotenoids and their derivatives can help promote health and contribute to reducing the risk of a number of diseases.
Modelling the solar twin 18 Scorpii Bazot, M.; Creevey, O.; Christensen-Dalsgaard, J. ...
Astronomy and astrophysics (Berlin),
11/2018, Letnik:
619
Journal Article
Recenzirano
Odprti dostop
Context. Solar twins are objects of great interest in that they allow us to understand better how stellar evolution and structure are affected by variations of the stellar mass, age and chemical ...composition in the vicinity of the commonly accepted solar values. Aims. We aim to use the existing spectrophotometric, interferometric and asteroseismic data for the solar twin 18 Sco to constrain stellar evolution models. 18 Sco is the brightest solar twin and is a good benchmark for the study of solar twins. The goal is to obtain realistic estimates of its physical characteristics (mass, age, initial chemical composition, mixing-length parameter) and realistic associated uncertainties using stellar models. Methods. We set up a Bayesian model that relates the statistical properties of the data to the probability density of the stellar parameters. Special care is given to the modelling of the likelihood for the seismic data, using Gaussian mixture models. The probability densities of the stellar parameters are approximated numerically using an adaptive MCMC algorithm. From these approximate distributions we proceeded to a statistical analysis. We also performed the same exercise using local optimisation. Results. The precision on the mass is approximately 6%. The precision reached on X0 and Z0 and the mixing-length parameter are respectively 6%, 9%, and 35%. The posterior density for the age is bimodal, with modes at 4.67 Gyr and 6.95 Gyr, the first one being slightly more likely. We show that this bimodality is directly related to the structure of the seismic data. When asteroseismic data or interferometric data are excluded, we find significant losses of precision for the mass and the initial hydrogen-mass fraction. Our final estimates of the uncertainties from the Bayesian analysis are significantly larger than values inferred from local optimization. This also holds true for several estimates of the age encountered in the literature.
Halide perovskites are widely used as components of electronic and optoelectronic devices such as solar cells, light-emitting diodes (LEDs), optically pumped lasers, field-effect transistors, ...photodetectors, and γ-detectors. Despite this wide range of applications, the construction of an electrically pumped perovskite laser remains challenging. In this paper, we numerically justify that mixing two perovskite compounds with different halide elements can lead to optical properties suitable for electrical pumping. As a reference, the chosen model material was CsPbBr3, whose performance as a part of lasers has been widely recognised, with some Br atoms substituted by I at specific sites. In particular, a strong enhancement of the low-energy absorption peaks has been obtained using the
Bethe-Salpeter equation. Based on these results, we propose specific architectures of ordered doping that could be realised by epitaxial growth. Efficient light emission from the bottom of the conduction band is expected.
Context. The formation and evolution of the Galactic bulge and its relationship with the other Galactic populations is still poorly understood. Aims. To establish the chemical differences and ...similarities between the bulge and other stellar populations, we performed an elemental abundance analysis of α- (O, Mg, Si, Ca, and Ti) and Z-odd (Na and Al) elements of red giant stars in the bulge as well as of local thin disk, thick disk and halo giants. Methods. We use high-resolution optical spectra of 25 bulge giants in Baade's window and 55 comparison giants (4 halo, 29 thin disk and 22 thick disk giants) in the solar neighborhood. All stars have similar stellar parameters but cover a broad range in metallicity (-1.5 < Fe/H < +0.5). A standard 1D local thermodynamic equilibrium analysis using both Kurucz and MARCS models yielded the abundances of O, Na, Mg, Al, Si, Ca, Ti and Fe. Our homogeneous and differential analysis of the Galactic stellar populations ensured that systematic errors were minimized. Results. We confirm the well-established differences for α/Fe at a given metallicity between the local thin and thick disks. For all the elements investigated, we find no chemical distinction between the bulge and the local thick disk, in agreement with our previous study of C, N and O but in contrast to other groups relying on literature values for nearby disk dwarf stars. For -1.5 < Fe/H < -0.3 exactly the same trend is followed by both the bulge and thick disk stars, with a star-to-star scatter of only 0.03 dex. Furthermore, both populations share the location of the knee in the α/Fe vs. Fe/H diagram. It still remains to be confirmed that the local thick disk extends to super-solar metallicities as is the case for the bulge. These are the most stringent constraints to date on the chemical similarity of these stellar populations. Conclusions. Our findings suggest that the bulge and local thick disk stars experienced similar formation timescales, star formation rates and initial mass functions, confirming thus the main outcomes of our previous homogeneous analysis of O/Fe from infrared spectra for nearly the same sample. The identical α-enhancements of thick disk and bulge stars may reflect a rapid chemical evolution taking place before the bulge and thick disk structures we see today were formed, or it may reflect Galactic orbital migration of inner disk/bulge stars resulting in stars in the solar neighborhood with thick-disk kinematics.
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