The Galois lattice as a hierarchical structure for topological relations

This paper presents the construction and the comparison of Galois lattices of topological relations for qualitative spatial representation and reasoning. The lattices rely on a correspondence between computational operations working on quantitative data, on the one hand, and topological relations working on qualitative knowledge units, on the other hand. After introducing the context of the present research work, i.e. the RCC-8 model of topological relations, we present computational operations for checking topological relations on spatial regions. From these operations are derived two sets of computational conditions that can be associated to topological relations through a Galois connection. The associated Galois lattices are presented and compared. Elements on the practical use of the lattices for representing spatial knowledge and for reasoning are also introduced and discussed.     

Zero‐Depth Interfacial Nanopore Capillaries

High‐fidelity analysis of translocating biomolecules through nanopores demands shortening the nanocapillary length to a minimal value. Existing nanopores and capillaries, however, inherit a finite length from the parent membranes. Here, nanocapillaries of zero depth are formed by dissolving two superimposed and crossing metallic nanorods, molded in polymeric slabs. In an electrolyte, the interface shared by the crossing fluidic channels is mathematically of zero thickness and defines the narrowest constriction in the stream of ions through the nanopore device. This novel architecture provides the possibility to design nanopore fluidic channels, particularly with a robust 3D architecture maintaining the ultimate zero thickness geometry independently of the thickness of the fluidic channels. With orders of magnitude reduced biomolecule translocation speed, and lowered electronic and ionic noise compared to nanopores in 2D materials, the findings establish interfacial nanopores as a scalable platform for realizing nanofluidic systems, capable of single‐molecule detection.     

Soybean allergen detection methods--a comparison study

Soybean containing products are widely consumed, thus reliable methods for detection of soy in foods are needed in order to make appropriate risk assessment studies to adequately protect soy allergic patients. Six methods were compared using eight food products with a declared content of soy: a direct sandwich ELISA based on polyclonal rabbit antibody (ab) to raw soy flakes, a commercial and an in-house competitive ELISA both based on ab to denatured, 'renatured' soy protein, an enzyme-allergosorbent test (EAST) inhibition based on two sera from soy allergic patients, histamine release (HR) using basophils passively sensitized with patient serum and a PCR method detecting soy DNA. Eight food products were selected as model foods to test the performance of the methods. There was an overall good agreement between the methods in terms of ranks of soy content but not the quantity. The sandwich ELISA aimed at native soy proteins had the lowest detection limit of 0.05 ppm, but only identified soy in 5/8 products, and generally in lower amounts compared to other methods. The competitive ELISA had a higher detection limit of 21 ppm, but seemed more successful in detecting processed soy. Only HR, EAST inhibition and PCR detected soy in all eight products. In spite of a general good correlation in terms of ranks of soy content, more than a single method may be necessary to confirm the presence of soy in foods.     

High level expression, purification and physico- and immunochemical characterisation of recombinant Pen a 1: a major allergen of shrimp

Well-characterised and immunologically active recombinant allergens are of eminent importance for improvement of diagnostic tools and immunotherapy of allergic diseases. The use of recombinant allergens has several advantages such as the more precise quantification of the active substance compared to allergen extracts and the reduced risk of contamination with other allergenic proteins compared to purified natural allergens. Optimised standard protocols for expression and purification and a detailed physico-chemical characterisation of such recombinant allergens are necessary to ensure consistent quality and comparability of results obtained with recombinant material. In this study the major allergen Pen a 1 of brown shrimp (Penaeus aztecus) was expressed in E. coli and purified in two steps by immobilised metal chelate-affinity chromatography (IMAC) and size-exclusion chromatography. Identity and purity were verified with N-terminal sequencing and peptide mass fingerprinting. Circular dichroism and NMR-spectroscopy indicated an alpha-helical flexible structure of rPen a 1 which is in accordance with the known structure of tropomyosins. Finally, the recombinant allergen proved to be immunologically reactive in IgE Western blot analysis and ELISA. This study provides a protocol for the preparation of recombinant shrimp tropomyosin in standardised quality.     

S100B Protein concentration in milk-formulas for preterm and term infants. Correlation with industrial preparation procedures

Human milk S100B protein possesses important neurotrophic properties. However, in some conditions human milk is substituted by milk formulas. The aims of the present study were: to assess S100B concentrations in milk formulas, to verify any differences in S100B levels between preterm and term infant formulas and to evaluate the impact of industrial preparation at predetermined phases on S100B content. Two different set of samples were tested: (i) commercial preterm (n = 36) and term (n = 36) infant milk formulas; ii) milk preterm (n = 10) and term infant (n = 10) formulas sampled at the following predetermined industrial preparation time points: skimmed cow milk (Time 0); after protein sources supplementation (Time 1); after pasteurization (Time 2); after spray-drying (Time 3). Our results showed that S100B concentration in preterm formulas were higher than in term ones (p < 0.01). In addition, S100B concentrations during industrial preparation showed a significant increase (p < 0.001) at Time 1 followed by a slight decrease (p > 0.05) at Time 2, whereas a significant (p < 0.001) dip was observed at Time 3. In conclusion, S100B showed a sufficient thermostability to resist pasteurization but not spry-drying. New feeding strategies in preterm and term infants are therefore warranted in order to preserve S100B protein during industrial preparation.     

Co-digestion of Municipal Sewage Sludges and Pre-hydrolysed Woody Agricultural Wastes

Material balance has been used to evaluate the COD behaviour and the time required for fed-batch digestion of mixtures of domestic sludges and pre-hydrolysed agricultural wastes. Pre-hydrolysis of the feed materials has been used to penetrate the strong lignocellulosic structure of these wastes as well as to increase the fraction of soluble organic substances in the mixture. The influence of the organic loading rate on the main process parameters (methane, carbon dioxide, total biogas productions and their respective conversion yields) has also been investigated. The organic load has been varied from 0·8 up to 6·1 g_COD dm⁻³ day⁻¹, corresponding to a range of volatile solids load of 0·6–4·5 g_VS dm⁻³ day⁻¹ for the material under consideration. These values are slightly higher than those usually employed in conventional digester for domestic sewage sludges. However, methane production reached a maximum rate of only 5·6 mmol dm⁻³ day⁻¹ at an organic loading rate of 4·6 g_COD dm⁻³ day⁻¹, while both CH₄ content and production of biogas rapidly fell over 2·2 g_COD dm⁻³ day⁻¹. On the whole, these results suggest that removal of lignin is necessary in order to carry out the continuous anaerobic digestion of pre-hydrolysed agricultural wastes rich in woody materials. © 1997 SCI.     

Conjugated linoleic acid and oxidative stress

At the present time, conjugated linoleic acid (CLA) is the subject of a growing number of studies since it has been demonstrated to possess anticarcinogenic and antiatherogenic activities in experimental animal models and to increase in some pathological states in humans. In both situations, CLA has been claimed to be involved in oxidative stress, as an antioxidant in the first case and as a primary product of a free-radical attack on polyunsaturated fatty acids (PUFA) in the other. The controversial results are due mostly to a lack of a suitable methodology because the presence of conjugated dienes (CD) in lipid moiety has been taken for years as evidence of lipid peroxidation due to the occurrence of this structure in fatty acid hydroperoxides. We have recently developed a new methodology that consists of the extraction of fatty acids, including CD fatty acid hydroperoxides, by mild saponification and their separation and identification by high-performance liquid chromatography with diode array detector. Fatty acid analyses of liver homogenate, oxidized in vitro either with Fe-ADP or t-butyl hydroperoxide (t-ButylHP), of lamb and rats fed CLA at levels known to prevent carcinogenesis, showed that CLA and its metabolites steadily decreased during oxidative stress and that they are more prone to oxidation than their corresponding methylene-interrupted fatty acids. No significant antioxidant effect of CLA was detected in any model tested. However, CD fatty acid hydroperoxides increased in the t-ButylHP model but not in the Fe-ADP model, owing probably to the degradation of CD fatty acid hydroperoxides induced by this oxidative agent. In conclusion, CLA and its metabolites seem to behave, under oxidative stress, as regular PUFA. Thus, it is highly unlikely that the peculiar effects of CLA are directly related to interference in lipoperoxidative processes.     

Co-occurrence of aflatoxins,ochratoxin A and citrinin in “egusi” melon (Colocynthis citrullus L.) seeds consumed in Ireland and the United Kingdom

The natural co-occurrence of aflatoxins (AFs), ochratoxin A (OTA) and citrinin (CIT) in melon seed samples obtained from retailers and households in Ireland and the United Kingdom (UK) was evaluated. AFs and OTA were determined by HPLC with fluorescence detection while CIT was analysed by HPLC-MS/MS. AFB₁ was detected in all (100%) samples (mean = 9.7 μg kg^?1; range = 0.2–66.5 μg kg^?1). Mean total AFs was 12.0 μg kg^?1 (range = 0.3–82 μg kg^?1). Commercially retailed samples showed a significantly higher AFB₁ contamination (p < 0.05) than the household samples. OTA occurred in 3 (13.6%) samples, while 4 (18.2%) were contaminated with CIT at very low levels. In this study, 68% of the melon seed samples were contaminated above the 2 μg kg^?1 EU limit for AFB₁ in oilseeds. These results highlight the need for the development of strategies to reduce AF contamination in “egusi” for human consumption.