10,052 research outputs found
Metabolic interactions between vitamin A and conjugated linoleic acid
Lipid-soluble molecules share several aspects of their physiology due to their common adaptations to a hydrophilic environment, and may interact to regulate their action in a tissue-specific manner. Dietary conjugated linoleic acid (CLA) is a fatty acid with a conjugated diene structure that is found in low concentrations in ruminant products and available as a nutritional supplement. CLA has been shown to increase tissue levels of retinol (vitamin A alcohol) and its sole specific circulating carrier protein retinol-binding protein (RBP or RBP4). However, the precise mechanism of this action has not been elucidated yet. Here, we provide a summary of the current knowledge in this specific area of research and speculate that retinol and CLA may compete for catabolic pathways modulated by the activity of PPAR- and RXR heterodimer. We also present preliminary data that may position PPAR- at the crossroads between the metabolism of lipids and vitamin
Nonlinear elasticity of monolayer graphene
By combining continuum elasticity theory and tight-binding atomistic
simulations, we work out the constitutive nonlinear stress-strain relation for
graphene stretching elasticity and we calculate all the corresponding nonlinear
elastic moduli. Present results represent a robust picture on elastic behavior
of one-atom thick carbon sheets and provide the proper interpretation of recent
experiments. In particular, we discuss the physical meaning of the effective
nonlinear elastic modulus there introduced and we predict its value in good
agreement with available data. Finally, a hyperelastic softening behavior is
observed and discussed, so determining the failure properties of graphene.Comment: 4 page
Epidemics of Meloidogyne brasilensis on processing tomato hybrids carrying the Mi (Root-knot nematode resistance) gene in Central Brazil.
Resumo 176. Trabalho apresentado no 27º Congresso Paulista de Fitopatologia, 2003, Botucatu
Elastic properties of hydrogenated graphene
There exist three conformers of hydrogenated graphene, referred to as chair-,
boat-, or washboard-graphane. These systems have a perfect two-dimensional
periodicity mapped onto the graphene scaffold, but they are characterized by a
orbital hybridization, have different crystal symmetry, and otherwise
behave upon loading. By first principles calculations we determine their
structural and phonon properties, as well as we establish their relative
stability. Through continuum elasticity we define a simulation protocol
addressed to measure by a computer experiment their linear and nonlinear
elastic moduli and we actually compute them by first principles. We argue that
all graphane conformers respond to any arbitrarily-oriented extention with a
much smaller lateral contraction than the one calculated for graphene.
Furthermore, we provide evidence that boat-graphane has a small and negative
Poisson ratio along the armchair and zigzag principal directions of the carbon
honeycomb lattice (axially auxetic elastic behavior). Moreover, we show that
chair-graphane admits both softening and hardening hyperelasticity, depending
on the direction of applied load.Comment: submitted on Phys.Rev.
Componentes de resistência à mancha-bacteriana e crescimento de Xantonomas campestris pv. vesicatoria, raça T2, em genótipos de tomateiro.
Seleção de linhagens com tolerância ao calor em germoplasma de tomateiro coletado na região Norte do Brasil.
Are ring galaxies the ancestors of giant low surface brightness galaxies?
We simulate the collisional formation of a ring galaxy and we integrate its evolution up to 1.5 Gyr after the interaction. About 100-200 Myr after the collision, the simulated galaxy is very similar to observed ring galaxies (e.g. Cartwheel). After this stage, the ring keeps expanding and fades. Approximately 0.5-1 Gyr after the interaction, the disc becomes very large (∼100 kpc) and flat. Such extended discs have been observed only in giant low surface brightness galaxies (GLSBs). We compare various properties of our simulated galaxies (surface brightness profile, morphology, H i spectrum and rotation curve) with the observations of four well-known GLSBs (UGC 6614, Malin 1, Malin 2 and NGC 7589). The simulations match quite well the observations, suggesting that ring galaxies could be the progenitors of GLSBs. This result is crucial for the cold dark matter (CDM) model, as it was very difficult, so far, to explain the formation of GLSBs within the CDM scenari
Resposta de cultivares de tomateiro para processamento industrial a fertirrigacao por gotejamento subterraneo.
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