Sur les solutions d'une équation fonctionnelle,III

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Prestress for maximum strength

The problem of designing prestress to maximize elastic capacity is treated analytically. Our formulation models structures comprised of a one-material elastic continuum, subject to a single deterministic load configuration.The equations needed to predict the optimal prestress design are derived. They are shown to comprise necessary and sufficient conditions for global maximum strength in the unconstrained design problem. The theory is demonstrated on the design of prestress for a thick-walled cylinder.     

Multielemental Analysis of Bee Pollen,Propolis, and Royal Jelly Collected in West-Central Poland

Beehive products possess nutritional value and health-promoting properties and are recommended as so-called “superfoods”. However, because of their natural origin, they may contain relevant elemental contaminants. Therefore, to assess the quality of bee products, we examined concentrations of a broad range of 24 selected elements in propolis, bee pollen, and royal jelly. The quantitative analyses were performed with inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES) techniques. The results of our research indicate that bee products contain essential macronutrients (i.e., K, P, and S) and micronutrients (i.e., Zn and Fe) in concentrations depending on the products’ type. However, the presence of toxic heavy metals makes it necessary to test the quality of bee products before using them as dietary supplements. Bearing in mind that bee products are highly heterogenous and, depending on the environmental factors, differ in their elemental content, it is necessary to develop standards regulating the acceptable levels of inorganic pollutants. Furthermore, since bees and their products are considered to be an effective biomonitoring tool, our results may reflect the environment’s condition in west-central Poland, affecting the health and well-being of both humans and bees.     

Hyperexpansive completion problem via alternating sequences; an application to subnormality

Truncations of completely alternating sequences are entirely characterized. The completely hyperexpansive completion problem is solved for finite sequences of (positive) numbers in terms of positivity of attached matrices. Solutions to the problem are written explicitly for sequences of two, three, four, five and six numbers. As an application, an explicit solution of the subnormal completion problem for five numbers is given.     

Simultaneous Determination of Major Constituents of Honeybee Venom by LC-DAD

The aim of the study was to develop an LC method for honeybee venom analysis, using cytochrome c as an internal standard. The SynChropack C8 6.5 μm, 4.6 × 100 mm column was applied. The bee venom was separated by linear gradient 5–80% B at 30 min (eluent A—0.1% TFA in water, eluent B—0.1% TFA in acetonitrile:water (80:20)). The flow rate of mobile phase was maintained at 1 mL min⁻¹, injection volume: 40 μL, separation temperature: 25 °C. The analysis was monitored at 220 nm. Several honeybee venom constituents were separated and the content of four of them (apamine, mast cell degranulating peptide, phospholipase A₂ and melittin) were determined. By applying this methodology differences in chemical composition of honeybee venom were evaluated. In order to confirm the data obtained, the following steps and parameters were taken into account for the validation of the method: selectivity, precision (injection repeatability, analysis repeatability), accuracy (recovery), linearity and operating range, limit of detection and limit of quantitation. All steps of validation proved that the developed analytical procedure was suitable for its intended purpose (standardization). Due to its simplicity, the developed method can be easily automated and incorporated into routine operations both in the bee venom identification, quality control and assay tests.     

Inverse-voltammetric determination of cadmium, lead and copper in animal samples after solubilization

Summary The conditions for the inverse-voltammetric determination of cadmium, lead, and copper in various biological samples after solubilization with Texapon are described. The results of this procedure are compared with those obtained with conventional high- and low-pressure wet digestions. The advantages of the Hg-film electrode as compared to the stationary Hg-electrode are discussed.Dedicated to Prof. Dr. G. Schulze on the occasion of his 60th birthday Permanent address: Technical University of Poznan, Institute of Chemistry, Poznan, Poland     

Sur la stabilité de l'équation d'homomorphisme

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Dédié à M.le Professeur J. Aczél à l'occasion de son 60^eme anniversaire     

Sources of error in the determination of non-ionic surfactants in environmental samples

The analytical procedures for the determination of non-ionic surfactants (NS) consist of sampling, multistage separation and final determination. Each of these stages is a potential source of error. 33% of an initial amount of 100 g NS may be lost due to adsorption on the walls of glass vessels during storage or 55% in the case of polyethylene vessels. Ineffective preservation of samples leads to very quick biodegradation of NS and incorrect results. Chloroform, frequently used for this purpose, is ineffective, whereas formaldehyde gives satisfactory results. Also during the separation procedure substantial fractions of NS are lost. The currently used methods enable the determination of NS having 5–30 oxyethylene subunits only. In the extraction with ethyl acetate NS having long oxyethylene chain remain in the water phase or are caught at the interface. If looked at carefully these analytical procedures show serious drawbacks. The washing of the precipitate in the BiAS procedure causes a dramatic loss of precipitate. The recommended use of G4 glass filters also leads to loss of precipitate. Instead, the use of G5 gives satisfactory results. The choice of one surfactant as the standard, necessary for the determination of the total concentration of a mixture of unknown composition, possibly consisting of several hundred of individual compounds, can be also a serious source of error. The higher is the difference between the slopes of the calibration curves of the mixture components, the higher is the error. Two newly developed techniques, namely the indirect tensammetric method (ITM) and the BiAS procedures combined with the ITM give better results than the procedures currently recommended.