A convenient method for the synthesis of 2-[(5-benzyl-1,3-thiazol-2-yl)imino]-1,3-thiazolidin-4-one derivatives

It was found that the reaction of 2-chloroacetamido/chloropropioamido-5-benzylthiazole with potassium thiocyanate gave, via rearrangement, 2-[(5-benzyl-1,3-thiazol-2-yl)imino]-1,3-thiazolidin-4-ones.     

Water-window microscopy using a compact, laser-plasma SXR source based on a double-stream gas-puff target

We report on a compact, desktop size, laboratory type microscopy setup, based on a short wavelength gas puff target soft X-ray source, which emits incoherent radiation in “water-window” spectral range. The microscope employs a Wolter type I reflective objective and allows capturing magnified images of objects with ~1-μm spatial resolution and exposure time as low as 5 s. A detailed characterization and optimization of both the source and the microscope setups are presented and discussed.     

Onsite hybridization between Ce 4f and 5d states as the indicator of the transition from Kondo insulator to metallic state in CeRhSb

We discuss and determine the conditions under which a Kondo-insulator phase is stable. We show for CeRhSb that the dependence of the onsite hybridization energy Vdf between the Ce 5d and Ce 4f states on the number of valence electrons or the unit cell volume is decisive for the hybridization Kondo gap formation. We also propose the method for determining the energy Vdf from the ab initio calculations. This approach supplies an accurate Kondo-insulator-metal transition in agreement with the recent experimental data.     

Application of ICP-MS and various computational methods for drinking water quality assessment from the Silesian District (Southern Poland)

In this study, more than 200 samples of drinking water from taps in the Silesian District (southern Poland) were analyzed. Concentrations of As, Bi, Cd, Co, Cr, Mo, Ni, Pb, Rb, Sb, Se, Te, Tl and V were measured using inductively coupled plasma-mass spectrometry technique (ICP-MS). The levels of the tested elements generally met European Union regulations. All analytical results were processed using computational methods, including the Pearson and Gini coefficients with the Lorenz curves, one-way ANOVA, the Kruskal-Wallis one-way analysis of variance, the Mann-Whitney U test, the variance correlation test and the Spearman’s test. In addition, Principal Component Analysis (PCA) with Varimax and Cluster Analysis with Ward’s Method were applied. It was shown, that some parameters (e.g. hardness and alkalinity) were highly correlated. The score plot described the degree of mineralization of water samples, so the origin of water could be easily determined. In turn, based on the created dendrogram, the division of samples into several groups (with soft, medium and highly mineralized water) could be deduced.     

Metal–insulator transition induced by non-stoichiometry of surface layer and molecular reactions on single crystal KTaO3

In the study we present results on topography, morphology, chemical composition, electronic structure and electrical properties of the (100) surface layer of KTaO₃ single crystal caused by sputtering with Ar⁺ ion beam with energy of 1 keV. Several surface sensitive techniques, i.e. X-ray photoelectron spectroscopy (XPS), local conductivity of atomic force microscopy (LC-AFM), and Kelvin Probe Force Microscopy (KPFM) were used. The observed changes in the electronic structure were explained as a result of the chemical decomposition of the surface layer. A correlation between the electronic states which appeared in the energy gap and the changes in charge state of Ta ions was found. The activation energy related to averaged local conductivity temperature dependence was estimated from Arrhenius plot. It was also found, that variations in the local contact potential difference (LCPD) indicated changes in the chemical composition in nano-scale. The chemical reconstruction of the KTaO₃ surface modified by Ar⁺ ion beam was deduced. This non-homogeneity corresponded to 2-D non-homogeneity of the local electric conduction (LC-AFM), which occurred within nano-areas after sputtering. Chemical reactivity of the modified surface with CO₂ and O₂ was observed. The reversibility of the Ar⁺ induced loss of oxygen non-stoichiometry was observed after the sample was exposed to various doses of O₂. The successful reversibility occurred after oxidation process at high temperature, i.e. 300 °C.     

Extremal graphs having no matching cuts

A graph G = (V, E) is matching immune if there is no matching cut in G. We show that for any matching immune graph G, |E|≥?3(|V|?1)/2?. This bound is tight, as we define operations that construct, from a given vertex, exactly the class of matching immune graphs that attain the bound. © 2011 Wiley Periodicals, Inc. J Graph Theory 69:206‐222, 2012 .