Antioxidant activity of aryltetralone lignans and derivatives from Virola sebifera (Aubl.)

Aryltetralone lignans bearing methylenedioxy groups (1a-b; 2a-b) were isolated from seeds of Virola sebifera. Their antioxidant activities were evaluated by inhibition of lipid peroxidation as indicated by TBARS and chemiluminescence emission (CL) assays. The lignan 1c, 'having a 2'-hydroxy-4',5'-methylenedioxyphenyl group, was the most active compound with TBARS/CL Q 1/2 values of 0.89 and 0.10 microg/mL, respectively. The catechol derivatives 3 and 4, obtained by demethylenation of lignans 1a and 2a, were of similar activity to 1c, and all were much more effective as antioxidants than alpha-tocopherol.     

Separation ofcis andtrans isomers of naturally occurring hydroxycinnamic acids by high-pressure liquid chromatography

Summary The separation of hydroxycinnamic acids has been investigated by high-pressure liquid chromatography using a micro C₁₈ bonded phase. Irradiation oftrans-ferulic and sinapic acids readily gave a mixture ofcis-trans isomers which can be also separated with the system described.     

The piezo-magnetic parameters of Terfenol-D: An experimental viewpoint

Magnetostrictive and all multifunctional materials have experienced in the last decades a growing technological interest. Several contributions, in the literature, propose the above-mentioned materials in innovative sensors and actuators both for bulk and MEMS devices. More recently, magnetostrictive materials have been proposed for energy harvesting applications by exploiting the so-called Villari effect. In this case, the behavior and the amplitude of the piezo-magnetic coefficients are an important element to evaluate the conversion efficiency. Aim of this paper is to study the experimental behavior of the piezo-magnetic coefficients of a commercial Terfenol-D rod under controlled conditions.     

Effects of hysteresis and eddy currents in magnetostrictive harvesting devices

The paper tackles the analysis of the magnetostrictive energy harvesting phenomena by formulating a model where the hysteretic static characteristic of the material and eddy currents induced by Villari effect are taken into account. The study aims to analyze the main loss mechanisms involved in this kind of devices, highlighting the impact of the hysteretic material behavior with respect to the linear and non-linear memoryless approaches.     

On the coupling impedance for particles with opposite velocities

As already shown by several authors, the reciprocity theorem can be rewritten as a simple formula connecting the longitudinal coupling impedances of a particle travelling in the positive and negative directions of an infinitely long vacuum chamber crossing a scattering structure (cavity, step junction, iris, etc.) of general shape. The formula is valid for any particle velocity. As an example, we consider the case of two semi-infinite circular vacuum chambers with different radii; for this case we give the explicit difference between the coupling impedances and the wake potentials. Received: 27 March 2002 / Revised version: 5 December 2002 / Published online: 26 February 2003     

On the use of quantile regression to deal with heterogeneity: the case of multi-block data

Advances in Data Analysis and Classification - The aim of the paper is to propose a quantile regression based strategy to assess heterogeneity in a multi-block type data structure. Specifically,...     

Inside the failure mechanism of tin oxide as anode for sodium ion batteries

Journal of Solid State Electrochemistry - The conversion-alloying compounds have been identified as promising anode materials for sodium ion batteries (SIBs). One of them, SnO2, with an enormous...     

Quantile composite-based path modeling

The paper aims at introducing a quantile approach in the Partial Least Squares path modeling framework. This is a well known composite-based method for the analysis of complex phenomena measurable through a network of relationships among observed and unobserved variables. The proposal intends to enhance potentialities of the Partial Least Squares path models overcoming the classical exploration of average effects. The introduction of Quantile Regression and Correlation in the estimation phases of the model allows highlighting how and if the relationships among observed and unobserved variables change according to the explored quantile of interest. The proposed method is applied to two real datasets in the customer satisfaction measurement and in the sensory analysis framework but it proves to be useful also in other applicative contexts.     

Quantile composite-based path modeling: algorithms,properties and applications

Advances in Data Analysis and Classification - Composite-based path modeling aims to study the relationships among a set of constructs, that is a representation of theoretical concepts. Such...