Microwave-Assisted Extraction of Anthocyanins from Black Currant Marc

This paper reports on the process optimization study of anthocyanin extraction from black currant marc by microwave-assisted extraction (MAE) using acidic solvents. Maximum yields of anthocyanins were achieved at pH?2 with an extraction time of 10 min with a microwave power of 700 W. The anthocyanin yields in MAE were compared with those obtained by conventional solvent extraction (CE) using citric or hydrochloric acids, and citric acid and water with a sulfur concentration of 50 ppm. A significant reduction of extraction time was achieved using MAE; maximum anthocyanin yield was obtained after 10 min using MAE, while using CE only after 300 min. Furthermore, the amount of solvent used halved; the mass ratio of marc to solvent was 1:40 in CE and 1:20 in MAE. Additionally, the final anthocyanin concentration in the solvent phase of MAE increased by 20 % compared to the conventional extraction with hydrochloric acid at pH?2 and temperature of 80 °C. The results suggest that microwave-assisted extraction is a more efficient technique for the extraction of valuable compounds from black currant residue.     

Aggregation functions: Construction methods, conjunctive, disjunctive and mixed classes

In this second part of our state-of-the-art overview on aggregation theory, based again on our recent monograph on aggregation functions, we focus on several construction methods for aggregation functions and on special classes of aggregation functions, covering the well-known conjunctive, disjunctive, and mixed aggregation functions. Some fields of applications are included.     

Grafting maleic anhydride and comonomers onto polyethylene

Grafting dicarboxylic anhydrides onto polyolefins has great practical importance. The process of grafting maleic anhydride onto high-density polyethylene in the presence of various comonomers in an intermeshing corotating twin-screw extruders was studied. Three types of comonomers were investigated: (i) vinyl monomers, including styrene and methacrylic acid; (ii) esters of dicarboxylic acids forming succinic groups after grafting, such as fumaric acid; and (iii) esters of fumaric and maleic acid and ethylenically unsaturated cyclic dicarboxylic anhydrides, such as Diels–Alder adducts of maleic anhydride; and (iv) dienes and dodecenyl succinic anhydride. © 1995 John Wiley & Sons, Inc.     

Mixtures of vegetable oils and di‐2‐ethylhexyl‐sebacate as lubricants

Lubricants based on vegetable oils are growing in popularity in various applications. Environmentally friendly, vegetable oils and their derivatives constitute alternatives to mineral‐based lubricants. Soybean oil, sunflower oil and rapeseed oil have better viscosity indices than mineral oils and even some synthetic oils, are biodegradable and have low production costs. However, vegetable oils have disadvantages, such as poor thermo‐oxidative stability due to the carbon–carbon double bonds and poor low‐temperature properties, which limit their use as lubricant base stocks. This study describes new base‐stock oils obtained from mixture of vegetable oils and di‐2‐ethylhexyl‐sebacate synthetic oil, which become lubricants when additives are introduced. These mixtures offer a large range of kinematic viscosities, while their pour points are under −33°C and their flash points over 240°C. The copper strip corrosion test result is 1a. The diameters of wear scars measured under four‐ball testing (40dyn) are less than 1mm. A differential scanning calorimetry study and a thermo‐gravimetric study under a nitrogen atmosphere for the mixed oils are reported. In the former study two‐endothermic processes were observed between −15°C and −50°C. In the thermo‐gravimetric analysis curve the weight loss is specific for each vegetable and synthetic oil component. From these studies a higher thermal stability was observed for vegetable oils than for ester oils, and it was concluded that the mixtures of vegetable and synthetic oils of diester type are physically homogeneous mixtures. The low production cost of lubricants based on vegetable oils makes them attractive alternatives for mineral oil based lubricants. Overall the mixtures of vegetable and ester oils can be competitive base oils for environmentally friendly lubricants. Copyright © 2006 John Wiley & Sons, Ltd.     

Atomicity via regularity for non-additive set multifunctions

In this paper, an approach of atomicity problems is presented by means of regularity. Characterizations and physical interpretations of atoms and non-atomicity for set multifunctions taking values in the family of all nonempty subsets of a topological space are given.     

Synthesis of conformationally constrained glutamic acid homologues and investigation of their pharmacological profiles

Homologation of the glutamic acid chain together with conformational constraint is a commonly used strategy to achieve selectivity towards different types of glutamate receptors. We investigated the effects of a further increase in the distance between the amino acid moiety and the distal carboxylate group of model compounds (+/-)-1 and (+/-)-2 on their activity/selectivity profiles. We therefore synthesized new derivatives (+/-)-3-(+/-)-6, which are homologues of glutamic acid containing three additional carbon units. Moreover, because the potency of NMDA antagonists can be markedly increased by replacing the distal carboxylate with the bioisosteric phosphonate group, we also prepared the corresponding phosphonate derivatives (+/-)-7-(+/-)-10. All new compounds were submitted to binding assays with iGluRs, and derivatives (+/-)-3-(+/-)-6 were also tested in second messenger assays at representative mGluR subtypes. All the applied structural modifications were detrimental to the interaction with NMDA receptors. Conversely, structural variation of the nonselective mGluR ligand (+/-)-2 led to derivative (+/-)-5, which behaved as a selective group I metabotropic receptor antagonist. Notably, upon i.c.v. administration in DBA/2 mice, amino acid (+/-)-5 produced a significant protection against audiogenic seizures, whereas it was inactive after i.p. administration.     

General interference analysis of M-QAM and M-PSK wireless communications

This work includes an accurate and general technique, which has been developed to analyze the symbol-error-rate (SER) of coherent M-Quadrature Amplitude Modulation (QAM) and Phase Shift Keying (PSK) schemes for various conditions of the transmission. A calculation scheme has been presented dealing with Additive White Gaussian Noise and different fading effects influencing the analyzed M-ary QAM or PSK signals. Furthermore, the authors have considered the effects of multiple interference signals embedded into a stochastic model having numerous parameters, which can be assumed as random variables with adjustable distributions. The resulted M-QAM and M-PSK SER expressions have been extended for multi-carrier transmission based on the analytical calculation of the stochastic interference model.     

Molecular and electronic structure of a trinuclear oxo-centred Iron(III) complex with trigonal bipyramidal metal sites

A μ₃-oxotriiron(III) complex with isovalent ferric sites was synthesized in the reaction of iron(II) triflate and the new ligand, 1,4-di-(2′-N-methylbenzimidazolyl)aminophthalazine (H₂L). The [Fe₃OL₃]⁺ cluster is formed in a one-pot, self-assembly reaction when the inert reaction mixture is exposed to dioxygen. The complex exhibits a triple-helical ligand arrangement and unprecedented homochiral trigonal bipyramidal iron-ligand framework. X-ray structural analysis shows typical isosceles distortion of the Fe₃ triangle with Fe–Fe distances of 3.330 and 3.305 Å. Spectroscopic, magnetic and electrochemical properties of the [Fe₃OL₃]⁺ compound is discussed in the article.