Profile, antioxidant potential, and applicability of phenolic compounds extracted from Spirulina platensis

This work aimed at an investigation of the profile of free phenolic compounds (PC) of Spirulina platensis and assesses their antioxidant potential, applying them as a natural conservative in minimally processed apples. The phenolic extract showed 396 &µg g-1 gallic acid, 347 µg g-1 of caffeic acid, 54 µg g-1 salicylic acid and 3.5 µg g-1 trans-1-cinmamic a total of 608 µg PC g-1 of S. platensis. With the use of PC, it was possible to inhibit the radical DPPH over 180 min with IC50 of PC 202 µg mL-1. The inhibition of polyphenol oxidase and peroxidase of PC were 19.9 and 9.7%. In addition, verifying the constants Km and Vmax, it was concluded that  inhibition of the peroxidase and polyphenol occurs in an uncompetitive manner. Application of crude extract of PC under minimally processed apples showed  inhibition of browning by 40%. The general acceptance of apples was not affected by the addition of PC.Key words: Apple, enzymatic browning, peroxidase, phenols, polyphenol oxidase

Transition from Persistent to Anti-Persistent Correlations in Postural Sway Indicates Velocity-Based Control

The displacement of the center-of-pressure (COP) during quiet stance has often been accounted for by the control of COP position dynamics. In this paper, we discuss the conclusions drawn from previous analyses of COP dynamics using fractal-related methods. On the basis of some methodological clarification and the analysis of experimental data using stabilogram diffusion analysis, detrended fluctuation analysis, and an improved version of spectral analysis, we show that COP velocity is typically bounded between upper and lower limits. We argue that the hypothesis of an intermittent velocity-based control of posture is more relevant than position-based control. A simple model for COP velocity dynamics, based on a bounded correlated random walk, reproduces the main statistical signatures evidenced in the experimental series. The implications of these results are discussed

The behaviour of a fibre-reinforced cemented soil

Triaxial compression tests with internal measurement of deformation and scanning electron microscopy were carried out to evaluate the effect of randomly distributed glass fibre reinforcement and cement content on the response of a sandy soil to load. Cemented specimens were prepared with cement contents varying from 0 to 5% by weight of dry soil and cured for 7 days. The fibre length was 12·8 mm, varying in a content from 0 to 3% by weight of dry soil. The cementation itself notably increased in stiffness and peak strength, while fibre inclusion increased both residual and peak strength and reduced stiffness, changing the behaviour of the cemented soil from brittle to more ductile. Peak strength envelopes indicated that the friction angle was increased from 35 to 41° as a result of cementation and 46° as a consequence of fibre inclusion. However, the peak cohesion intercept was unchanged after fibre addition, being a function only of cementation. </jats:p