The equidistant involution of the hyperbolic plane and two models of the Euclidean plane geometry

In this paper we define an involution of the hyperbolic plane corresponding to an equidistant curve and a point of its base line that keeps a certain subset of the equidistant curves invariant. Based on this mapping we present two models of the Euclidean geometry in the hyperbolic plane.     

Synthesis, spectral and solid state characterization of a new bioactive hydrazine bridged cyclic diphosphonium compound

The facile preparation of a racemic hydrazine bridged diphosphonium compound possessing a ring system analogous to bicyclo[3.3.2]decane is reported. Although the reaction yield is low, the structure of the compound, which possesses an eight-membered ring, two phosphonium cationic centers, a biimino bridge, molecular chirality and two fused aromatic rings locked into roughly perpendicular planes is unusual. The compound displays substantial biological activity in the brine shrimp test and cleaves plasmid DNA.     

Sensing mispaired thymines in DNA heteroduplexes using an electroactive osmium marker: towards electrochemical SNP probing

A complex OsO₄, 2,2′-bipyridine (Os,bipy), has been used for electroactive labeling of biopolymers as well as for probing of nucleic acids and protein structure and interactions. In DNA, Os,bipy forms electrochemically active adducts with pyrimidine nucleobases, exhibiting highly selective modification of thymine residues in single-stranded DNA. Here, we show that modification of rare thymine residues (one thymine among several tens of unreactive purine bases) can easily be detected by means of a simple ex situ voltammetric analysis using carbon electrodes. Based on this remarkable sensitivity of detection, Os,bipy has been used as an electroactive probe for unpaired and/or mismatched thymine residues within DNA heteroduplexes. Site-specific chemical modification of the DNA with the Os,bipy has allowed a clear distinction between perfectly base-paired DNA homoduplexes and mismatched heteroduplexes, as well as discrimination among heteroduplexes containing one or two mispaired thymines, a single thymine insertion, or combination of a mispair and an insertion.     

Effect of five different stages of ripening on chemical compounds in medlar (Mespilus germanica L.)

The study of changes of nutritional value of fruit during the ripening process can help estimate the optimal date for fruit harvesting to achieve the best quality for direct consumption and further utilization. The aim of this study was to monitor the changes of chemical composition of medlar fruit (Mespilus germanica L.) measured at five various ripening stages including 134, 144, 154, 164 and 174 days after full bloom (DAFB). Fruits were analyzed and ascorbic acid (AA) and total phenolic compound content with respect to the total antioxidant activity were determined. In addition, selected micronutrients and macronutrients were monitored. The results of our experiments demonstrate that ascorbic acid, total phenolic compound content and total antioxidant activity decreased significantly with increasing time of ripeness. The decreasing tendency in potassium, calcium and magnesium contents during the ripening stages was also determined. During the ripening period, the content of all micronutrients as well as phosphorus and sodium was balanced, with no statistically significant differences between the monitored ripening stages, which can be considered as a positive fact with respect to ideal consumption quality of fruit.     

Fully automated spectrometric protocols for determination of antioxidant activity: advantages and disadvantages

The aim of this study was to describe behaviour, kinetics, time courses and limitations of the six different fully automated spectrometric methods--DPPH, TEAC, FRAP, DMPD, Free Radicals and Blue CrO5. Absorption curves were measured and absorbance maxima were found. All methods were calibrated using the standard compounds Trolox? and/or gallic acid. Calibration curves were determined (relative standard deviation was within the range from 1.5 to 2.5%). The obtained characteristics were compared and discussed. Moreover, the data obtained were applied to optimize and to automate all mentioned protocols. Automatic analyzer allowed us to analyse simultaneously larger set of samples, to decrease the measurement time, to eliminate the errors and to provide data of higher quality in comparison to manual analysis. The total time of analysis for one sample was decreased to 10 min for all six methods. In contrary, the total time of manual spectrometric determination was approximately 120 min. The obtained data provided good correlations between studied methods (R=0.97-0.99).     

Glycoprofiling as a novel tool in serological assays of systemic sclerosis: A comparative study with three bioanalytical methods

Systemic sclerosis (SSc) is an autoimmune disease seriously affecting patient’s quality of life. The heterogeneity of the disease also means that identification and subsequent validation of biomarkers of the disease is quite challenging. A fully validated single biomarker for diagnosis, prognosis, disease activity and assessment of response to therapy is not yet available. The main aim of this study was to apply an alternative assay protocol to the immunoassay-based analysis of this disease by employment of sialic acid recognizing lectin Sambucus nigra agglutinin (SNA) to glycoprofile serum samples. To our best knowledge this is the first study describing direct lectin-based glycoprofiling of serum SSc samples. Three different analytical methods for glycoprofiling of serum samples relying on application of lectins are compared here from a bioanalytical point of view including traditional ELISA-like lectin-based method (ELLA), novel fluorescent lectin microarrays and ultrasensitive impedimetric lectin biosensors. Results obtained by all three bioanalytical methods consistently showed differences in the level of sialic acid present on glycoproteins, when serum from healthy people was compared to the one from patients having SSc. Thus, analysis of sialic acid content in human serum could be of a diagnostic value for future detection of SSc, but further work is needed to enhance selectivity of assays for example by glycoprofiling of a fraction of human serum enriched in antibodies for individual diagnostics.     

RAFT of sulfobetaine for modifying poly(glycidyl methacrylate) microspheres to reduce nonspecific protein adsorption

The minimization of nonspecific protein adsorption is a crucial step in the development of bioseparation processes, immunoassays, and affinity diagnostics. Among the numerous biomaterials, polyzwitterions are known to effectively suppress protein and cell adhesion. This article describes the formation of monodisperse polymer microspheres coated with polysulfobetaine with the aim to limit nonspecific adsorption of bovine serum albumin (BSA) as a model protein. In this process, 2‐μm poly(glycidyl methacrylate) (PGMA) microspheres were prepared by dispersion polymerization. To render the microspheres hydrophilic and biocompatible, [3‐(methacryloylamino)propyl]dimethyl(3‐sulfopropyl)ammonium hydroxide (MPDSAH) was grafted from the surface by reversible addition‐fragmentation chain transfer (RAFT) polymerization. Elemental analysis of the modified microspheres revealed up to 20 wt % of poly{[3‐(methacryloylamino)propyl]dimethyl(3‐sulfopropyl)ammonimum hydroxide} (PMPDSAH). The microspheres were characterized in terms of particle size, morphology, and zeta potential. The amount of BSA nonspecifically adsorbed on the PMPDSAH‐modified microspheres decreased to half of that captured on the unmodified PGMA microspheres. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2273–2284     

A General Version of the Retract Method for Discrete Equations

We study a problem concerning the compulsory behavior of the solutions of systems of discrete equations u（k ＋ 1） = F（k, u（k））, k ∈ N（a） = {a, a ＋ 1, a ＋ 2 }, a ∈ N,N= {0, 1,... } and F ： N（a） × R^n→R^n. A general principle for the existence of at least one solution with graph staying for every k ∈ N（a） in a previously prescribed domain is formulated. Such solutions are defined by means of the corresponding initial data and their existence is proved by means of retract type approach. For the development of this approach a notion of egress type points lying on the defined boundary of a given domain and with respect to the system considered is utilized. Unlike previous investigations, the boundary can contain points which are not points of egress type, too. Examples are inserted to illustrate the obtained result.     

Characterization of the generalized Calabi composition of affine hyperspheres

In this paper, continuing with Hu–Li–Vrancken and the recent work of Anti′c–DillenSchoels–Vrancken, we obtain a decomposition theorem which settled the problem of how to determine whether a given locally strongly convex affine hypersurface can be decomposed as a generalized Calabi composition of two affine hyperspheres, based on the properties of its difference tensor K and its affine shape operator S.