4,717 research outputs found
Colloidal stability of tannins: astringency, wine tasting and beyond
Tannin-tannin and tannin-protein interactions in water-ethanol solvent
mixtures are studied in the context of red wine tasting. While tannin
self-aggregation is relevant for visual aspect of wine tasting (limpidity and
related colloidal phenomena), tannin affinities for salivary proline-rich
proteins is fundamental for a wide spectrum of organoleptic properties related
to astringency. Tannin-tannin interactions are analyzed in water-ethanol
wine-like solvents and the precipitation map is constructed for a typical grape
tannin. The interaction between tannins and human salivary proline-rich
proteins (PRP) are investigated in the framework of the shell model for
micellization, known for describing tannin-induced aggregation of beta-casein.
Tannin-assisted micellization and compaction of proteins observed by SAXS are
described quantitatively and discussed in the case of astringency
Modelling food sourcing decisions under climate change: A data-driven approach
Changes in climate conditions are expected to pose signi cant challenges to the food industry, as it is very
likely that they will a ect the production of various crops. As a consequence, decisions associated with the
sourcing of food items will need to be reconsidered in the years to come. In this paper, we investigate how
environmental changes are likely to a ect the suitability and risk of di erent regions |in terms of growing
certain food items| and whether companies should adapt their sourcing decisions due to these changes. In
particular, we propose a three-stage approach that guides food sourcing decisions by incorporating climate
change data. The methodology utilises environmental data from several publicly available databases and
models weather uncertainties to calculate the suitability and risk indices associated with growing a crop in
a particular geographical area. The estimated suitability and risk parameters are used in a mean-variance
analysis to calculate the optimal sourcing decision. Results from a case example indicate that sourcing
decisions of popular food items are likely to require signi cant adaptations due to changes to the suitability
of certain regions
Histolocalization and physico-chemical characterization of dihydrochalcones: Insight into the role of apple major flavonoids
Flavonoids, like other metabolites synthesized via the phenylpropanoid pathway, possess a wide range of biological activities including functions in plant development and its interaction with the environment. Dihydrochalcones (mainly phloridzin, sieboldin, trilobatin, phloretin) represent the major flavonoid subgroup in apple green tissues. Although this class of phenolic compounds is found in very large amounts in some tissues (≈200 mg/g of leaf DW), their physiological significance remains unclear. In the present study, we highlight their tissue-specific localization in young growing shoots suggesting a specific role in important physiological processes, most notably in response to biotic stress. Indeed, dihydrochalcones could constitute a basal defense, in particular phloretin which exhibits a strong broad-range bactericidal and fungicidal activity. Our results also indicate that sieboldin forms complexes with iron with strong affinity, reinforcing its antioxidant properties and conferring to this dihydrochalcone a potential for iron seclusion and/or storage. The importance of localization and biochemical properties of dihydrochalcones are discussed in view of the apple tree defense strategy against both biotic and abiotic stresses
Regional hydrological impacts of climatic change : hydroclimatic variability : proceedings of symposium S6 held during the seventh IAHS scientific assembly
Consumers of organic products in France: first results of the Nutrinet-Santé cohort
Lifestyle, dietary patterns and nutritional status of organic food consumers have rarely been described, while interest for a sustainable diet is markedly increasing. Consumer attitude and frequency of use of 18 organic products were assessed in 54,311 adult participants in the Nutrinet-Santé cohort. Cluster analysis was performed to identify behaviors associated with organic product consumption. Cross-sectional association with overweight/obesity was estimated using polytomous logistic regression. Five clusters were identified: 3 clusters of non-consumers (35%) whose reasons differed, occasional (OCOP, 51%) and regular (RCOP, 14%) organic product consumers. RCOP were more highly educated and physically active than others. They exhibited dietary patterns with more plant foods and less sweet and alcoholic beverages, processed meat or milk. Their nutrient intake profiles (fatty acids, most minerals and vitamins, fibers) were healthier and closer to dietary guidelines. In multivariate models (after accounting for confounders, including level of adherence to nutritional guidelines), compared to those not interested in organic products, RCOP participants showed a markedly lower probability of overweight (excluding obesity) and obesity :-36% and -62% in men and -42% and -48% in women, respectively (P<0.0001). OCOP participants generally showed intermediate figures. In conclusion, regular consumers of organic products exhibit specific socio-demographic characteristics, and an overall healthy profile
Surface Magnetization of Aperiodic Ising Quantum Chains
We study the surface magnetization of aperiodic Ising quantum chains. Using
fermion techniques, exact results are obtained in the critical region for
quasiperiodic sequences generated through an irrational number as well as for
the automatic binary Thue-Morse sequence and its generalizations modulo p. The
surface magnetization exponent keeps its Ising value, beta_s=1/2, for all the
sequences studied. The critical amplitude of the surface magnetization depends
on the strength of the modulation and also on the starting point of the chain
along the aperiodic sequence.Comment: 11 pages, 6 eps-figures, Plain TeX, eps
Dihydrochalcones: Implication in resistance to oxidative stress and bioactivities against advanced glycation end-products and vasoconstriction
Flavonoids are a group of polyphenol compounds with known antioxidant activities. Among them, dihydrochalcones are mainly found in apple leaves (Malus domestica). Glycosylated dihydrochalcones were previously found in large amounts in leaves of two genotypes of Malus with contrasting resistance to fire blight, a bacterial disease caused by Erwinia amylovora. In the present study we demonstrate that soluble polyphenol patterns comprised phloridzin alone or in combination with two additional dihydrochalcones, identified as sieboldin and trilobatin. Presence of sieboldin in young leaves correlated well with a high 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity. Moreover, these leaves displayed enhanced tolerance to paraquat, a photooxidative-stress generating herbicide. Interestingly, phloridzin had a high activity in the oxygen radical absorbance capacity (ORAC) assay, but its presence alone in leaves did not correlate with tolerance to paraquat. In order to further characterise the activity of these compounds, we tested their ability to prevent oxidative-dependent formation of advanced glycation end-products (AGEs) and phenylephrine-induced contraction of isolated rat mesenteric arteries. The antioxidant capacity of sieboldin was clearly demonstrated by showing that this compound (i) prevented vasoconstriction and (ii) inhibited AGEs formation. Both assays provided interesting information concerning a potential use of sieboldin as a therapeutic. Hence, our results strongly argue for a bioactivity of dihydrochalcones as functional antioxidants in the resistance of Malus leaves to oxidative stress. In addition, we demonstrate for the first time that sieboldin is a powerful multipotent antioxidant, effective in preventing physiopathological processes. Further work should aim at demonstrating the potential use of this compound as a therapeutic in treating free radical-involving diseases
The melting curve of iron at extreme pressures: implications for planetary cores
Exoplanets with masses similar to that of Earth have recently been discovered
in extrasolar systems. A first order question for understanding their dynamics
is to know whether they possess Earth like liquid metallic cores. However, the
iron melting curve is unknown at conditions corresponding to planets of several
times the Earth's mass (over 1500 GPa for planets with 10 times the Earth's
mass (ME)). In the density-temperature region of the cores of those
super-Earths, we calculate the iron melting curve using first principle
molecular dynamics simulations based on density functional theory. By comparing
this melting curve with the calculated thermal structure of Super Earths, we
show that planets heavier than 2ME, have solid cores, thus precluding the
existence of an internal metallic-core driven magnetic field. The iron melting
curve obtained in this study exhibits a steeper slope than any calculated
planetary adiabatic temperature profile rendering the presence of molten
metallic cores less likely as sizes of terrestrial planets increase
Multiexcitons confined within a sub-excitonic volume: Spectroscopic and dynamical signatures of neutral and charged biexcitons in ultrasmall semiconductor nanocrystals
The use of ultrafast gating techniques allows us to resolve both spectrally
and temporally the emission from short-lived neutral and negatively charged
biexcitons in ultrasmall (sub-10 nm) CdSe nanocrystals (nanocrystal quantum
dots). Because of forced overlap of electronic wave functions and reduced
dielectric screening, these states are characterized by giant interaction
energies of tens (neutral biexcitons) to hundreds (charged biexcitons) of meV.
Both types of biexcitons show extremely short lifetimes (from sub-100
picoseconds to sub-picosecond time scales) that rapidly shorten with decreasing
nanocrystal size. These ultrafast relaxation dynamics are explained in terms of
highly efficient nonradiative Auger recombination.Comment: 5 pages, 4 figures, to be published in Phys. Rev.
First principles theory of inelastic currents in a scanning tunneling microscope
A first principles theory of inelastic tunneling between a model probe tip
and an atom adsorbed on a surface is presented, extending the elastic tunneling
theory of Tersoff and Hamann. The inelastic current is proportional to the
change in the local density of states at the center of the tip due to the
addition of the adsorbate. We use the theory to investigate the vibrational
heating of an adsorbate below an STM tip. We calculate the desorption rate of H
from Si(100)-H(21) as function of the sample bias and tunnel current,
and find excellent agreement with recent experimental data.Comment: 5 pages, RevTeX, epsf file
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