Ability to determine the desferrioxamine‐chelatable iron fractions of nontransferrin‐bound iron using HPLC

Iron is an essential element in human development. It is imperative for oxygen and electron transport and also for DNA and neurotransmitters synthesis. On the other hand, this metal is able to participate in Fenton's reaction that in turn leads to free radical damage. The most toxic fraction of iron – nontransferrin‐bound iron and its part desferrioxamine‐chelatable iron – can serve as an exquisite biomarker in the identification of iron imbalance. The goal of the present study was to devise a simple, repeatable, and inexpensive method for the determination of desferrioxamine‐chelatable iron in serum blood samples. The assay procedure is based on desferrioxamine complex formation with iron ions followed to ferrioxamine and its quantitative measurement using RP‐HPLC method. The desferrioxamine‐chelatable iron was extracted from blood by centrifugation and SPE method. Chromatographic separation was performed at 40°C by step‐form gradient elution using Cadenza CD‐C18 column (150 × 4.6 mm id, particle size of 3.0 μm) connected with precolumn for contaminants removal. Gradient HPLC elution has been carried out with solvent A (10 mM Tris‐HCl, pH 5.5) and solvent B (ACN). The flow rate was 1.2 mL/min, and the total separation time was 5 min. The linear quantitation range was 2.5–500 μM (r = 0.9973), and the LOD and LOQ were 0.42 and 1.29 μM, respectively. Proposed HPLC method allowed for the determination of desferrioxamine‐chelatable iron fraction's of nontransferrin‐bound iron, both in the buffer and the serum supplemented with iron ions as well as in the patients’ serum samples with good results of precision and recovery. The developed method found to be sufficiently precise and reproducible for established conditions and after validation and may be used for routine assay of desferrioxamine‐chelatable iron in biological samples.     

A simplified implementation of the least squares solution for pairwise comparisons matrices

This is a follow up to “Solution of the least squares method problem of pairwise comparisons matrix” by Bozóki published by this journal in 2008. Familiarity with this paper is essential and assumed. For lower inconsistency and decreased accuracy, our proposed solutions run in seconds instead of days. As such, they may be useful for researchers willing to use the least squares method instead of the geometric means method.     

Absolute extensors and absolute neighborhood extensors in asymptotic categories

This paper deals with extending maps in asymptotic categories, i.e., in categories consisting of metric spaces and asymptotically Lipschitz coarsely proper maps. We demonstrate certain examples of absolute extensors and absolute neighborhood extensors. We give some conditions under which a version of Borsuk's homotopy extension theorem holds in these categories, and in answer to a problem posed by Dranishnikov in [Russian Math. Surveys 55 (2000) 1085] we show the failure of a general homotopy extension theorem. Finally, we show that a pair of an Hadamard space and its convex subspace has the homotopy extension property.     

Diastereoselective Pictet-Spengler condensation of tryptophan with α-amino aldehydes as chiral carbonyl components

The Pictet-Spengler reaction of Trp with α-amino aldehydes derived from l and d-amino acids was studied in terms of double stereodifferentiation. The results observed for d-amino aldehydes represent ‘matched’ situation (one diastereoisomer was formed) whereas with l-amino aldehydes ‘mismatched’ (two diastereoisomers were formed). The conformation of newly formed six-membered ring was analyzed. It was found that stable conformers were different for cis and trans isomers.     

Conductivity,morphology, interfacial chemistry,and stability of poly(3,4‐ethylene dioxythiophene)–poly(styrene sulfonate): A photoelectron spectroscopy study

X‐ray photoelectron spectroscopy (XPS) has been used to characterize poly(3,4‐ethylene dioxythiophene)–poly(styrene sulfonate) (PEDT/PSS), one of the most common electrically conducting organic polymers. A correlation has been established between the composition, morphology, and polymerization mechanism, on the one hand, and the electric conductivity of PEDT/PSS, on the other hand. XPS has been used to identify interfacial reactions occurring at the polymer‐on‐ITO and polymer‐on‐glass interfaces, as well as chemical changes within the polymer blend induced by electrical stress and exposure to ultraviolet light. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2561–2583, 2003     

On nonlinear Koopman''s construction

We show that there exists a possibility for a nonlinear variant of Koopman's construction. This gives a natural way for introducing nonlinear quantum maps. Applications to quantum chaos are indicated.     

An efficient direct method for fully conforming spectral collocation schemes

An efficient direct method is presented for the solution of the linear systems arising in the solution of second and fourth order problems by certain multidomain spectral collocation schemes. In it, the block structure of the global matrix is exploited. The performance of the method is examined for problems in two and three dimensions on an RS6000 workstation and a Cray J-916 supercomputer.     

Implicit Interval Methods for Solving the Initial Value Problem

Implicit interval methods of Runge–Kutta and Adams–Moulton type for solving the initial value problem are proposed. It can be proved that the exact solution of the problem belongs to interval-solutions obtained by the considered methods. Furthermore, it is possible to estimate the widths of interval-solutions.