New results on variants of covering codes in Sierpiński graphs

In this paper we study identifying codes, locating-dominating codes, and total-dominating codes in Sierpiński graphs. We compute the minimum size of such codes in Sierpiński graphs.     

A sonochemical method for the preparation of cadmium sulfide and cadmium selenide nanoparticles in aqueous solutions

Sonochemistry is a branch of chemistry where sound energy in the form of ultrasound is used to influence the course of reactions. A short-term, local increase in temperature occurs when the solutions and suspensions are irradiated by ultrasound. This happens because the substance absorbs the ultrasound waves. The purpose of this research was the synthesis of CdS and CdSe nanoparticles. We used cadmium sulfate hydrate (CdSO₄·8/3H₂O), elemental S and Se. Aqueous solutions of NaOH, Na₂SO₃ and EDTA were used as the solvents.During the syntheses, we used a direct immersion ultrasound probe by vibracell. The device operates with a constant frequency of 20 kHz, with the possibility to change the amplitude and with it the input of energy to the time unit. The products were characterized by X-ray powder diffraction (XRD), thermal analyses (TGA, SDTA) and TEM analyses.     

Influence of the specific surface area of secondary material on the solidification process and microstructure of aluminium alloy AA7075

Journal of Thermal Analysis and Calorimetry - Recycling activities are encouraged to conserve natural resources and reduce pollution. If waste is pre-treated and appropriately sorted, recycled...     

Maximal semigroups dominated by 0–1 matrices

Maximal semigroups dominated by a 0–1 matrix of a certain type are determined. The 0–1 matrices that dominate maximal bounded and maximal commuting semigroups are given. Also semigroup modules over maximal semigroups dominated by a 0–1 matrix are discussed.     

An open-source surface barrier discharge plasma pretreatment for reduced cracking of outdoor wood coatings

The development of a simple surface barrier discharge plasma device is presented to enable more widespread access to and utilization of plasma technology. The application of the plasma device was demonstrated for pretreatment of wood prior to application of protective coatings for outdoor usage. The coatings' overall performance was increased, showing a reduction or absence of cracking due to weathering on plasma-pretreated specimens. Moreover, after ten months of outdoor weathering, the plasma-pretreated specimens showed fewer infections with biotic factors and improved adhesion performance in cross-cut tests, while the surface gloss performed independently from plasma pretreatment. In contrast to that, plasma-pretreated specimens were slightly more prone to discoloration due to outdoor weathering, whereas the plasma pretreatment did not impact the initial color after coating application.

Graphic abstract

     

Synchronization and chimeras in a network of photosensitive FitzHugh–Nagumo neurons

Nonlinear Dynamics - Recently, a photosensitive model has been proposed that takes into account nonlinear encoding and responses of photosensitive neurons that are subject to optical signals. In...     

Improving the reliability of peak-evaluation results in gamma-ray spectrometry

In gamma-ray spectrometry the activities present in the samples are calculated from the areas of the peaks occurring in the spectra. Therefore, the utmost reliability of these input data must be maintained. To avoid systematic manual checks of the peak areas, the spectrum is analyzed consecutively by three peak-analysis programs. A comparative study was performed in which these peak-evaluation programs were tested to determine whether they yielded unbiased results. Only these programs can be used in a combined application. A consistency test of peak areas calculated by use of the three programs, for the same peak, was performed. Outlying results were discarded and the uncertainty of the best estimate for the area of a peak was calculated taking into account the dispersion of the peak-area results for this peak. The reliability of the computerized procedure has made manual checks of the peak areas unnecessary.     

Reversed phase monolithic analytical columns for the determination of HA1 subunit of influenza virus haemagglutinin

Monoliths are chromatographic stationary phases, which were specially designed for efficient purification of large biomolecules, like proteins, viruses and DNA. In this work, the small scale monolithic butyl (C4) and styrene-divinyl benzene (SDVB) columns were applied for reversed phase analyses of various degraded influenza viruses. The binding of the HA1 subunit of haemagglutinin to the monolithic columns was confirmed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and the Western blot. The working linear range was determined as 1.60 × 10¹⁰ viral particles/mL to at least 1.64 × 10¹¹ viral particles/mL, the limit of detection was found to be 2.56 × 10⁹ virus particles/mL and the limit of quantification was 5.12 × 10⁹ virus particles/mL. The analytical HPLC method developed with the H1N1 virus was also applicable for the analytics of the HA1 subunit of H3N2 influenza virus and the influenza B virus.     

Hydroxylammonium fluorometalate: synthesis and characterisation of a new fluorozincate

Abstract  

A new coordination compound of zinc fluoride and hydroxylammonium, (NH₃OH)₂ZnF₄, was obtained after dissolving zinc powder in hydrofluoric acid (40%) and adding solid hydroxylammonium fluoride. The colourless crystals were characterised chemically, magnetically, structurally by single-crystal X-ray diffraction analysis, and thermogravimetrically by TGA and DSC analysis. The structure consists of NH₃OH⁺ cations and ZnF₆ octahedra in which the metal ion lies on the inversion centre. Each of the ZnF₆ octahedra shares four of its vertices in a way that each vertex is shared between two octahedra. Oxygen and nitrogen atoms of hydroxylammonium cations are donors of hydrogen bonds. Hydroxylamonium fluorozincate crystallizes monoclinic, P21/c, with cell parameters a = 8.1604(4) ?, b = 5.8406(3) ?, c = 5.6586(2) ? and β = 94.745(3)°. The compound decomposes above 373 K in four steps, obtaining ZnO as the final residue. Magnetic properties of the compound were studied between 2 and 300 K, giving the prevailing diamagnetic behaviour with room temperature susceptibility of −9 × 10⁻⁵ emu mol⁻¹.