Detecting exponential dichotomy on the real line: SVD and QR algorithms

In this paper we propose and implement numerical methods to detect exponential dichotomy on the real line. Our algorithms are based on the singular value decomposition and the QR factorization of a fundamental matrix solution. The theoretical justification for our methods was laid down in the companion paper: “Exponential Dichotomy on the real line: SVD and QR methods.”     

Strategies for improving the water solubility of new antitumour nitronaphthylbutadiene derivatives

Different nitronaphthylbutadienes have been previously proved to have antitumour activity. The main drawback of these derivatives is their low water solubility. With the aim of facilitating the administration of these new drugs we have synthesized the hexyl (2Z,4E)-2-methylsulfanyl-5-(1-naphthyl)-4-nitro-2,4-pentadienoate analogue (1-Naph-NHCB) which is demonstrated to be easily included into cyclodextrins and/or entrapped into liposomes. Its antitumour activity was revealed to be almost comparable with that of the previously studied methyl analogue ester (1-Naph-NMCB). On the other hand, in vitro studies with different cancer cell lines showed that the cytotoxic activity of both 1-Naph-NMCB and 1-Naph-NHCB were fully preserved and in some cases also enhanced when entrapped into liposomal carriers.     

Relevance of Sb(III), Sb(V), and Sb-containing nano-particles in urban atmospheric particulate matter

A quick and reliable analytical method for the separation and quantification of extractable Sb(III) and Sb(V) in atmospheric particulate matter (PM) by ion chromatography(IC)-inductively coupled plasma-mass spectrometry (ICP-MS) has been optimized, validated on pairs of real, equivalent PM₁₀ samples and applied to a field monitoring campaign in a urban site. Both Sb(III) and Sb(V) forms were detected in real samples with Sb(III)/Sb(V) ratios up to 1.5. These two Sb species accounts only for a portion, of variable magnitude, of the total extractable Sb (10–70%); anyway, no other soluble Sb species were detected in the samples. The analysis of size-segregated samples collected by a 13-stage impactor showed that the recovery of [Sb(III) + Sb(V)] versus total extractable Sb is almost quantitative in the coarse fraction while it is below than 10% in the fine fraction. In the extracted solution from particles below 1 μm we could highlight the presence of Sb-containing suspended solid nano-particles, which probably constitute the missing fraction. The contribution of nano-particles can be estimated as the difference between ICP-MS and IC-ICP-MS data, as small size solid bodies are able to pass through the nebulizer and reach the plasma torch, while they are retained by the chromatographic column. The aggregation state of these nano-particles seems to be easily altered when they are suspended in a water solution; a similar behavior could be hypothesized when in contact with biological fluids. It has been confirmed that brake pad abrasion is the prevalent source of Sb(III) in PM and that Sb(V) may be formed by oxidation during the braking processes. Differing from other environmental matrices, there is no evidence of any spontaneous oxidative conversion within the two species.     

Molecular aspects of milk allergens and their role in clinical events

Milk allergy is the most frequent food allergy in childhood. Even though cases of newly developed milk allergy in adulthood are known, this allergy is less frequent in adults since it is normally outgrown by children during the first years of life. One of the reasons why allergy to cow’s milk shows its highest prevalence in children is its early introduction into the diets of babies when breast feeding is not possible. The major allergens are caseins and β-lactoglobulin, but allergies to other minor proteins (immunoglobulins, bovine serum albumin) have also been reported. Milk allergenicity can be reduced by various treatments (mainly hydrolysis), meaning that formulas based on cow’s milk can often be safely fed to children allergic to milk proteins. Cross-reactivity has been described between different mammalian milks and between milk and meat or animal dander. Cross-contamination can result from inadequate cleaning of industrial equipment and constitutes a hidden danger for allergic subjects who unknowingly ingest milk proteins. Figure Involvement (expressed as percentage of total subjects) of the most abundant milk proteins in the sensitization of 80 children allergic to cow’s milk. The upper panel includes all positive responses, even minor ones; data in the lower panel are restricted to the most severe positive responses (see text for details). SPT, skin prick test; CAP, CAP test; IMM, immunoblotting; alpha-LA, α-lactalbumin; beta-LG, β-lactoglobulin; cas, caseins; BSA, bovine serum albumin     

Binding behaviour of pyrimethanil-imprinted polymers prepared in the presence of polar co-monomers

Here, we report the evaluation of the molecular recognition properties of a small library of pyrimethanil-imprinted pellicular beads prepared in the presence of several co-monomers of decreasing hydrophobicity, namely N-methacrylamidopiperidine, methylmethacrylate, N-methacrylamidopyrrolidine, N-vinylpyrrolidone, 2-hydroxyethylmethacrylate, acrylonitrile, N-methacrylamidomorpholine, and N,N-dimethylacrylamide. The effect of the presence of these co-monomers on the molecular recognition properties of the beads were studied by eluting the pyrimethanil/Sudan Orange G pair, in the presence of acetonitrile/water mobile phases of increasing polarity. The pyrimethanil was used to probe the specific interactions due to the presence of binding sites. The Sudan Orange G (that is greatly different from the template but with comparable hydrophobicity and molecular mass) was instead used to probe the non-specific interactions due to the bulk of the polymer. The experimental results show that the polymers prepared in the presence of polar co-monomers are characterised by a marked increase of the analytes retention if compared with the imprinted polymer prepared without these co-monomers. The increase of retention is more pronounced for pyrimethanil compared to Sudan Orange G with polymers prepared in the presence of the more hydrophilic co-monomers N-vinylpyrrolidone, acrylonitrile and N-methacrylamidomorpholine, while N,N-dimethylacrylamide is the only co-monomer that does not significantly influence the retention of analytes. Increasing the amount of water in the mobile phase progressively diminishes this effect.     

Dual CD system-modified MEEKC method for the determination of clemastine and its impurities

A dual system of CDs was used for the first time in MEEKC with the aim of determining clemastine and its three main related impurities in both drug substances and tablets. The addition of methyl-β-cyclodextrin and heptakis(2,6-di-O-methyl)-β-cyclodextrin to the microemulsion pseudo-stationary phase was essential to increase the resolving power of the system to obtain a baseline separation among the compounds. The best microemulsion composition was identified by mixture design and the effects of the factors concentrations of CDs and voltage were investigated by a response surface study applying a Central Composite Design. In both cases, Derringer's desirability function made it possible to find the global optimum, which corresponded to the following combination: microemulsion, 89.8% 10 mM borate buffer pH 9.2, 1.5% n-heptane and 8.7% of SDS/n-butanol in 1:2 ratio; 18 mM methyl-β-cyclodextrin, 38 mM heptakis(2,6-di-O-methyl)-β-cyclodextrin, 17 kV. By applying these conditions, the separation was completed in about 5.5 min. The method was validated following International Conference on Harmonisation guidelines and was applied to a real sample of clemastine tablets.     

Biosensors for effective environmental and agrifood protection and commercialization: from research to market

Biosensors are projected to find many applications due to their high selectivity and sensitivity, rapid reaction, economy and ease of handling in field measurements. Even though biosensors for a wide range of environmental pollutants have been extensively reported in the literature, the decision to develop a suitable biosensing system that can be approved by a regulatory perspective for environmental applications is fraught with technical issues. These issues mainly concern the biological recognition element, the physico-chemical transducer and the interfaces between the biological and the physical components, but also aspects of fluidics, electronics, and software for data processing. This article reviews methods together with a process to move biosensor technology from research laboratories to market, focusing as a case in point on challenges and possible opportunities in the development of photosynthetic-based biosensors for environmental applications.     

Unusual cytotoxic sulfated cadinene-type sesquiterpene glycosides from cottonseed (Gossypium hirsutum)

Two new sulfated cadinene-type sesquiterpene glycosides, 13-hydroxy-7-O-(6′-O-sulfate-β-d-glucopyranosyl)-desoxyhemigossypol (1) and 13,15-dihydroxy-7-O-(6′-O-sulfate-β-d-glucopyranosyl)-desoxyhemigossypol (2), have been isolated from whole cottonseed (Gossypium hirsutum). Their structures, which possess an unusual 6-O-sulfate-glucopyranosyl moiety, were determined through the interpretation of 2D NMR spectral data and H/D exchange ESI-MS experiments. Compounds 1 and 2 were screened for their toxicity on Jurkat cells. Both compounds inhibited cellular proliferation with IC₅₀ values of 8.1 and 4.2 μg, respectively.