Carotenoid and fatty acid profiles of bilberries and cultivated blueberries from Romania

The worldwide consumption of blueberries has increased due to their potential health effects. They contain micronutrients, various phytochemicals and anti-oxidant pigments, represented especially by anthocyanins. In addition to these, carotenoids and fatty acids are also present. The aim of this study was the identification and quantification of carotenoids (by HPLC) and fatty acids (by GC with flame ionisation detection) in two bilberry genotypes (Wild 1 and 2) and three cultivars (BlueCrop, Elliot, and Duke). The main carotenoids identified were lutein, ??-cryptoxanthin, and ??-carotene, with the average total carotenoid content of 266 ??g per 100 g of fruit. The ratio of saturated fatty acids (SFAs) to polyunsaturated fatty acids (PUFAs) was 0.098 for Wild 1 and 0.11 for Wild 2 genotypes and ranged from 0.14 to 0.28 for cultivars. The main fatty acids identified were linoleic (18:2) and linolenic (18:3) acids in all the samples analysed. In Vaccinium myrtillus the amount of carotenoids and fatty acids was higher than in Vaccinium corymbosum species.     

Monolayer and aggregate formation of a modified phthalocyanine on mica determined by a delicate balance of surface interactions

An ordered layer of a phthalocyanine modified with ether tails can be formed on muscovite mica if removed from solution and dried. This ordered layer forms on potassium terminated as well as on sodium terminated mica, but not on a hydronium terminated surface. The molecules lie flat on the surface, as shown by AFM and X-ray diffraction, giving a layer thickness of approximately 1 nm. In solution, however, no in-plane ordering exists. The material is attracted to the substrate surface but instead of ordering, it aggregates in a liquid-like mobile fashion. This is likely caused by the fact that the water present in solution has a stronger interaction with the potassium ions on the mica surface than with the ether tails of the phthalocyanine.     

Homogeneity and local symmetry of complex (<Emphasis Type="Italic">κ</Emphasis>, µ)-spaces

We prove that a complex (κ, μ)-space with κ < 1 is a locally homogeneous complex contact metric manifold. Also, a complex (κ, μ)-space has either κ = 1 or is GH-locally symmetric.     

Theoretical assessment of the Ni–Sn system

Abstract  

A new theoretical assessment of the Ni–Sn system has been performed by use of the CALPHAD method. Recent experimental results were significantly different from older experimental data and, therefore, a new reassessment of older theoretical work was necessary. The theoretical models for some intermetallic phases were changed to make them consistent with other binary systems in the thermodynamic database developed in the scope of COST action MP0602. Very good agreement was reached both with new experimental phase equlibrium data and older thermodynamic data.     

Preconcentration and Voltammetric Determination of the Antihypertensive Doxazosin on a C8 Modified Carbon Paste Electrode

 An electrochemical study of the doxazosin oxidative process at carbon paste electrodes using different voltammetric techniques has been carried out. The process is irreversible and controlled by adsorption, giving rise to an oxidation wave around 1.0 V in citric acid-citrate buffer (pH 3.0). A mechanism based on the oxidation of the amine group is postulated. Two methods based on adsorptive stripping (AdS) of doxazosin at the C₈-modified carbon paste electrode (C₈-MCPE), before its voltammetric determination, are studied, using differential pulse voltammetry (DPV) and square wave voltammetry (SWV) as redissolution techniques. By means of AdS-DPV and C₈-MCPE, doxazosin can be determined over the 1.0 × 10⁻⁹ to 3.0 × 10⁻⁸ mol L⁻¹ range with a variation coefficient of 2.2% (2.0 × 10⁻⁸ mol L⁻¹) and a limit of detection of 7.4 ×10⁻¹⁰ mol L⁻¹. If AdS-SWV is used, a linear range from 1.0 × 10⁻⁹ to 4.0 × 10⁻⁸ mol L⁻¹ is obtained, the variation coefficient being 2.8% (2.0 × 10⁻⁸ mol L⁻¹, and the limit of detection reached 7.7 × 10⁻¹⁰ mol L⁻¹. The AdS-DPV procedure was applied to the determination of doxazosin in urine and formulations. Received March 13, 1999. Revision December 23, 1999.     

Anthocyanins as Key Phytochemicals Acting for the Prevention of Metabolic Diseases: An Overview

Anthocyanins are water-soluble pigments present in fruits and vegetables, which render them an extensive range of colors. They have a wide distribution in the human diet, are innocuous, and, based on numerous studies, have supposed preventive and therapeutical benefits against chronic affections such as inflammatory, neurological, cardiovascular, digestive disorders, diabetes, and cancer, mostly due to their antioxidant action. Despite their great potential as pharmaceutical applications, they have a rather limited use because of their rather low stability to environmental variations. Their absorption was noticed to occur best in the stomach and small intestine, but the pH fluctuation of the digestive system impacts their rapid degradation. Urine excretion and tissue distribution also occur at low rates. The aim of this review is to highlight the chemical characteristics of anthocyanins and emphasize their weaknesses regarding bioavailability. It also targets to deliver an update on the recent advances in the involvement of anthocyanins in different pathologies with a focus on in vivo, in vitro, animal, and human clinical trials.     

Tightly closed ideals of small type

We study the smallest possible type of tightly closed ideals that are cofinal with the powers of the maximal ideal; this numerical invariant yields information about the tight closure of arbitrary ideals in the ring.

     

Polarographic determination of the stability constants of binary and ternary lead(II) complexes and different organic ligands

The stability constants of complexes of different stoichiometries, formed by Pb(II) with oxalate, maleate, tartrate and citrate anions, have been determined. The polarographic methods originally used by DeFord and Hume were used for the binary complexes and those of Schaap and McMasters for the mixed complexes. The reliability of the results obtained was verified by applying the POLAG program. Finally, different statistical considerations were undertaken which confirm the results.     

Chemistry of N-Boc-N-tert-butylthiomethyl-protected alpha-aminoorganostannanes: diastereoselective synthesis of primary beta-amino alcohols from alpha-aminoorganostannanes

Reaction of N-Boc-N-tert-butylthiomethyl-protected alpha-aminoorganostannanes with n-BuLi generates the corresponding alpha-aminoorganolithiums. Reactions of these organolithiums with aromatic aldehydes provides N-protected beta-amino alcohols with diastereoselectivities up to >99:1 anti/syn; with aliphatic aldehydes, diastereoselectivities were typically 1:1. Diastereoselectivities varied depending on the amount of aldehyde used. The N-protected beta-amino alcohols could be deprotected to primary amines by treatment with NaH to generate oxazolidinones followed by basic hydrolysis. Alternatively, treatment of the protected amino alcohols with acid furnished cyclic acetals that could be deprotected to primary amines with BF(3).OEt(2) and HS(CH(2))(3)SH. Transmetalation of enantiomerically enriched organostannanes with n-BuLi at -95 degrees C provided organolithiums that, although less configurationally stable than N-Boc-N-methyl-protected alpha-aminoorganolithiums, could be trapped with aldehydes with near-complete retention of configuration.     

Characterisation of human metallothioneins from foetal liver and adult kidney using differential pulse polarography

The electrochemical behaviour of four human metallothioneins (MT) from foetal liver and adult kidney with respect to solution pH as well as the influence of the addition of cadmium and/or zinc were studied using differential pulse polarography. The complexation equilibrium of dissociation and the formation from their metal depleted form was investigated, going from basic to acid solution and vice versa. The stability of these human MTs with respect to changes in the pH of the solution is low. In fact, the complexation equilibrium is not reversible and consequently, the protein, at acid pH, is denatured and the metal binding capacity to complex the cations through the thiol groups is lost. In the case of some of these MTs two different electrochemical responses due to the reduction of complexed Cd(II), as well as to the Zn(II) complexes were distinguished. The predominance of each of these two species for both cations seems to depend on the total concentration, on the ratio between zinc and cadmium concentrations and on the solution pH. In each of the molecules studied, the addition of zinc provokes the transformation of the peak attributed to the Cd-Thionein complex CdT, initially found in the native MT, into another form, CdT′, having different characteristics to the initial one. The MTs are able to incorporate the added metal ions into their molecule. This implies a new reorganisation of the initial molecule in which both cadmium and zinc complexes are involved. The apparent stability constants of the Cd-MT, Zn-MT and Hg-MT complexes were estimated at different pH values.