Comparison of different injection modes in edible oil minor components analysis

Waxes and fatty acid alkyl esters are minor components used as official parameters to control the authenticity and quality of a high‐value olive oil product. A poor measurement can lead to a misleading classification of the oil. The official method requires their analysis together by capillary gas chromatography equipped with a flame ionization detector and an on‐column injector to avoid discrimination and thermal degradation. The degradation can occur to a different extent if different (and not properly optimized) injectors are used. However, other injection techniques, such as programmed‐temperature vaporizer, are much more versatile and more widespread. The aim of the present work was to compare the performance of a programmed‐temperature vaporizer injector, in on‐column and splitless mode, with the on‐column injector to analyze alkyl esters and waxes. Discrimination among high‐boiling compounds was evaluated, as well as the occurrence of thermal degradation, especially of sterols and diterpene alcohol (phytyl and geranylgeraniol) esters. A proper optimization of a programmed‐temperature vaporizer injection, with particular attention to the liner selection, was proven to provide comparable results to the traditional on‐column injection. A performance comparison was carried out both on standard mixtures and on real oil samples.     

Dynamics of pistachio oils by proton nuclear magnetic resonance relaxation dispersion

A number of pistachio oils were selected in order to test the efficacy of nuclear magnetic resonance relaxation dispersion (NMRD) technique in the evaluation of differences among oils (1) obtained from seeds subjected to different thermal desiccation processes, (2) retrieved from seeds belonging to the same cultivar grown in different geographical areas and (3) produced by using seed cultivars sampled in the same geographical region. NMRD measures relaxation rate values which are related to the dynamics of the chemical components of complex food systems. Results not only allowed to relate kinematic viscosity to relaxometry parameters but also were successful in the differentiation among the aforementioned oils. In fact, from the one hand, the larger the kinematic viscosity, the faster the rotational motions appeared as compared to the translational ones. On the other hand, relaxation rate curves (NMRD) varied according to the oxidative stresses and chemical composition of each sample. The present study showed for the first time that NMRD is a very promising technique for quick evaluations of pistachio oil quality without the need for time-consuming chemical manipulations.     

Cotype and absolutely summing linear operators

New applications of cotype to the theory of absolutely summing linear operators between Banach spaces are proved in this paper. Among other consequences we extend/complement some classical results of Bennett (Duke Math J 44:603?C639, 1977) on the existence of non-absolutely summing operators between ? _p spaces and of Davis and Johnson (Stud Math 51:81?C85, 1974) on the existence of compact non-absolutely summing linear operators. We also point out that some of our results are sharp.     

Solid-State 1H-NMR Relaxation Properties of the Fruit of a Wild Relative of Eggplant at Different Proton Larmor Frequencies

¹H longitudinal relaxation time profiles (T1) at different proton Larmor frequencies were registered for a solid-state plant tissue by using fast field cycling (FFC) nuclear magnetic resonance (NMR) spectroscopy. T1 distributions were obtained and the curves deconvoluted in order to differentiate among the different T1 components. Among the components, two were assigned to hydrophobic (e.g., fatty acid) and hydrophilic (e.g., saccharide) molecular systems, whereas the others were attributed to bulk and bound water. This paper shows for the first time solid-state FFC-NMR spectroscopy applied to plant tissue and reveals that relaxometry is a very promising technique for studying plant systems.     

Auto-bäcklund transformation and analytic solutions in one dimensional carrier flow equations

We consider the simplified one dimensional PDE's governing the carrier flow in semi-conductor devices via the Painlevé analysis approach, and obtain analytic solutions.     

Wood cellulignin as an alternative matrix for enzyme immobilization

The objective of this work was to select an efficient methodology for preparing active samples of Candida rugosa lipase immobilized in wood cellulignin, to be applied in hydrolysis and ester reactions. For this purpose, lipase was immobilized in the matrix by physical adsorption (pure cellulignin) and covalent binding (activated cellulignin with glutaraldeyde or carbonyldiimidazole [CDI]) in the presence or absence of polyethylene glycol (PEG) (Molecular mass of 1500 Daltons) as stabilizing agent. The activating agent and the presence of PEG-1500 in the immobilization procedure showed a strong influence on enzyme retention in the support. The values for enzyme retention ranged from 20 to 68%, and the highest yield was obtained when the enzyme was immobilized in cellulignin activated with CDI in the presence of PEG-1500. This immobilized derivative presented high hydrolytic (193.27 μM/[mg·min]) and synthetic (522.92 μM/[g·min]) activities when compared with those obtained by other techniques. The superiority of this immobilized system was confirmed by additional analyses, such as infrared spectroscopy and elemental analysis, which demonstrated an appropriate enzyme fixation and the highest level of protein incorporation in the support. Further information on the immobilized derivative was obtained by assessing the recycle potential in both aqueous and nonaqueous media.