First identification of biradicals during thermal [2π + 2π] cyclopolymerization of trifluorovinyl aromatic ethers

The thermal cyclopolymerization of three trifluorovinyl aromatic ether monomers 1,1,1‐tris (4‐trifluorovinyloxyphenyl)ethane (1), 4,4′‐bis(4‐trifluorovinyloxy)biphenyl (2) and 2,2‐bis(4‐trifluorovinyloxy‐ phenyl)‐1,1,1,3,3,3‐hexafluoropropane (3) were monitored in situ using time‐resolved electron paramagnetic resonance spectroscopy over a temperature range of 150–210 °C. The signals observed during the early stages of perfluorocyclobutyl polymer production suggest the formation of a triplet state corresponding to the proposed biradical intermediate with a strong dipole–dipole interaction. A doublet splitting shows the presence of hyperfine coupling due to fluorine. The characterization of radical species formed during the polymerization of monomer 1 using model compounds and polymerization kinetics of monomer 2 are also presented. Copyright © 2007 Society of Chemical Industry     

Signal strength based link sensing for mobile ad-hoc networks

Mobility causes frequent link failures in ad-hoc networks. This results in a severe degradation of performance specially in case of high mobility of nodes. This is because the routing protocols for ad-hoc networks are not equipped to handle high mobility. In this paper, we have presented a new link management algorithm to locally manage links. This new mechanism is based on signal strength measurements. Researchers over the years have presented approaches which use signal strength measurements but their focus has been on re-active protocols while our algorithm is aimed at pro-active protocols. Pro-active protocols are used since they provide greater flexibility to take advantage of the mesh configuration. We develop the hysteresis mechanism provided by OLSR, based on hello packets, to include signal strength measurements. The mechanism in OLSR uses Hello packets received/lost to decide to establish link or not. The problem with this approach arises when there is high mobility in which case the time to break the link and use a new path becomes significant. To overcome this, we propose to use signal strength to determine if the link-quality is improving or deteriorating. This combination of the two mechanisms, makes the link management more robust and also helps in anticipating link breakages thereby greatly improving performance.     

Meta-Level interpretation of constraint languages a case study: Logical primitives

This paper provides a detailed presentation of a Prolog-written meta-level interpreter for a constraint logic programming (CLP) language for expressing equalities and disequalities of finite trees, as well as non-negative integers (arities). The logical interpretation of the Prolog primitive functor (whose arguments are trees and arity) is used to illustrate the interactions among constraints pertaining to multiple domains. The paper’s objective is to provide insights about CLP language design and to present a modularized, incrementally-expandable meta-processor for this class of languages.     

Production of reduced-fat whipped toppings by solid fat-based W/O/W double emulsions: proof of concept

Water-in-oil-in-water (W/O/W) double emulsions present a reduced-fat alternative to conventional O/W food emulsions, as part of the dispersed oil phase is replaced with water. In this study, the concept of a reduced-fat whipped topping produced by W/O/W technology was proven. Whipping of a W/O/W emulsion, containing only 20% oil phase and a solid fat content of 78%, produced a superior whipped topping, in terms of firmness and overrun, compared to its whipped O/W emulsion counterparts. The presence of PGPR in the oil phase increased structure formation during whipping, while the additional dispersed-phase volume resulted in a better air inclusion. Two commercial monoacylglycerols (saturated and unsaturated) were investigated to improve the whipping properties of the produced W/O/W double emulsion. Both increased the susceptibility towards partial coalescence, thereby reducing whipping time and overrun, while increasing firmness of the produced whipped topping. Furthermore, the effect was stronger for the unsaturated than for the saturated monoacylglycerol.     

Genetic transformation of Brevibacterium linens strains producing high amounts of diverse sulphur compounds

By its numerous properties and importance in cheese technology (production of colour, flavour, bacteriocins and resistance to salt) Brevibacterium linens is a major cheese ripening bacteria. However, the genetic approach of such biological functions has been hindered, up to now, by the lack of tools necessary to realise genetic modifications in this species. Our objective was to demonstrate that it is possible to genetically modify several strains exhibiting interesting technological properties, especially the production of sulphur compounds. We worked with a phenotypically and genetically diverse collection of 11 strains. We genetically transformed several Brevi. linens with acceptable rates with plasmids classically used to transform lactic acid bacteria and other Gram+ bacteria. These results open up new prospects to investigate the most interesting Brevi. linens metabolic pathways both at the biochemical and genetic level.     

A food matrix reduces digestion and absorption of food allergens in vivo

Scope: Food allergy is caused by primary (class 1) food allergens, e.g. Bos d 5 (cow's milk) and Cor a 8 (hazelnut) or secondary (class 2) food allergens, e.g. Mal d 1 (apple). The latter cannot sensitize susceptible individuals but can cause allergy due to immunological cross‐reactivity with homologous respiratory allergens. Here, we studied the effects of food matrix on gastrointestinal proteolysis, epithelial transport and in vivo absorption of class 1 and class 2 food allergens. Methods and results: Mal d 1 lost its IgE‐reactivity immediately after simulated gastric digestion whereas Bos d 5 and Cor a 8 did not. Only Cor a 8 maintained IgE‐binding capacity after simulated intestinal proteolysis. The presence of hazelnut and peanut extracts, which served as protein‐rich model food matrices, delayed gastrointestinal degradation and reduced epithelial transport rates of all allergens through CaCo‐2 monolayers. Finally, IgE‐reactive allergens were assessed at different time points in sera from rats fed with all three allergens with or without hazelnut extract. The levels of all allergens peaked 2 h after animals were fed without matrix and increased over 8 h after feeding. Conclusions: A protein‐rich food matrix delays gastrointestinal digestion and epithelial transport of food allergens and thereby may affect their sensitizing capacity and clinical symptoms.     

Synthesis and Evaluation of Bombesin Analogues Conjugated to Two Different Triazolyl‐Derived Chelators for 99mTc Labeling

Overexpression of the gastrin‐releasing peptide receptor (GRPR) in a variety of human carcinomas has provided a means of diagnosis and treatment. Previously we reported a metabolically stable (N^αHis)Ac‐βAla‐βAla‐[Cha¹³,Nle¹⁴]BBS(7–14) analogue with high affinity for the GRPR. We have also shown that the biodistribution pattern of this fairly lipophilic, radiolabeled peptide can be enhanced by glycation, which is easily carried out by Cu^I‐catalyzed cycloaddition. Herein, we further elaborate this “click approach” in the synthesis of a new series of triazole‐based chelating systems as alternatives to the (N^αHis)Ac chelator for labeling with the ^99mTc(CO)₃ core. The bombesin analogues, containing these new chelating systems, were evaluated with regard to their synthesis and in vitro and in vivo properties, and were compared with their (N^αHis)Ac counterparts. The influence of the chelator on biodistribution properties was less than that of glycation, which clearly improved the tumor‐to‐background ratios.