Protective effects of extracts and flavonoids isolated from Scutia buxifolia Reissek against chromosome damage in human lymphocytes exposed to hydrogen peroxide

Flavonoids are claimed to protect against cardiovascular disease, certain forms of cancer and ageing, possibly by preventing initial DNA damage. Therefore, we investigated the protective effects of crude extract, ethyl acetate fraction and flavonoids (quercetin, quercitrin, isoquercitrin and rutin) isolated from the leaves from Scutia buxifolia against chromosome damage induced by H?O? in human lymphocytes by analyzing cellular growth rate, cell viability, mitotic index and chromosomal instability. We found a differential response among the compounds tested, with the ethyl acetate fraction being more effective than the crude extract, a difference perhaps related to the presence of the antioxidants identified and quantified by HPLC/DAD. In general, quercetin, isoquercitrin and rutin recovered the mitotic index and chromosomal instability more than quercitrin after treatment with hydrogen peroxide.     

Repulsive van der Waals forces in soft matter: why bubbles do not stick to walls

Measurements of nonequilibrium hydrodynamic interactions between bubbles and solid surfaces in water provide direct evidence that repulsive van der Waals forces of quantum origin control the behavior of liquid films on solids in air. In addition to being the simplest and most universal 3-phase system, the deformable air-water interface greatly enhances the sensitivity of force measurements compared with rigid systems. The strength of the repulsive interaction, controlled by the choice of solid, is sufficient to prevent coalescence (sticking) on separation due to hydrodynamic interactions.     

Finite element error analysis of a zeroth order approximate deconvolution model based on a mixed formulation

A suitable discretization for the Zeroth Order Model in Large Eddy Simulation of turbulent flows is sought. This is a low order model, but its importance lies in the insight that it provides for the analysis of the higher order models actually used in practice by the pioneers Stolz and Adams [N.A. Adams, S. Stolz, On the approximate deconvolution procedure for LES, Phys. Fluids 2 (1999) 1699-1701; N.A. Adams, S. Stolz, Deconvolution methods for subgrid-scale approximation in large eddy simulation, in: B.J. Geurts (Ed.), Modern Simul. Strategies for Turbulent Flow, Edwards, Philadelphia, 2001, pp. 21-44] and others. The higher order models have proven to be of high accuracy. However, stable discretizations of them have proven to be tricky and other stabilizations, such as time relaxation and eddy viscosity, are often added. We propose a discretization based on a mixed variational formulation that gives the correct energy balance. We show it to be unconditionally stable and prove convergence.     

Phycornyces: TURGOR PRESSURE BEHAVIOR DURING THE LIGHT AND AVOIDANCE GROWTH RESPONSES

Abstract— The turgor pressure of the stage 4b sporangiophore of Phycomyces blakesleeanus was continuously measured with a pressure probe before and during a period of increased elongational growth rate elicited by a step-up in blue light fiuence rate (a positive light growth response) or by a double-barrier stimulus (avoidance growth response). In these and other experiments it was found that a step-up in turgor pressure between 0.02 and 0.05 MPa may elicit an increase in growth rate that is comparable to those of the light and avoidance growth responses. The results of the present work demonstrate that the turgor pressure does not increase during these growth responses, indicating that the increased growth rate is solely the result of altered cell wall mechanical properties. Furthermore, very small decreases in turgor pressure could be detected during the period of increased growth rate. This turgor pressure depression is predicted by the Growth Equations, and provides further support for the conclusion that the light and avoidance growth responses are solely the result of changes in cell wall mechanical properties.