Original paper application of cyclodextrins as modifiers in electrophoretic separation of metalloporphyrins

Several metallocomplexes of tetrakis-carboxyphenylporphyrin (TCPP) were separated on fused-silica capillary using CZE with UV-VIS detection. Metalloporphyrins of Co(II), Cu(II), Mn(II), Ni(II), and Zn(II) were formed directly in TCPP solution with addition of Cd(II) to increase the formation reaction rate. The composition of BGE, its concentration, and pH were optimized to ensure the stability of complexes and proper resolution. In particular, the problem of signals' shape was investigated and discussed. The presence of beta-CD in borate buffer significantly improved separation efficiency and signal shapes due to formation of inclusion complexes. Under the best separation conditions (50 mM borate running buffer at pH 9 with addition of 2 mM beta-CD, 30 kV applied voltage) a separation of metal complexes with TCPP was accomplished in 16 min.     

Thermally stimulated currents as a measure of degradation of zinc oxide varistors

ZnO varistor degradation phenomena was studied using thermally stimulated current (TSC) method. It is believed that asymmetrical degradation of V-I characteristics caused by DC biasing is due to charge accumulation on the reverse biased side of ZnO grain barrier. The TSCs' measuring system and cryostat apparatus used in experiment were described. The thermally stimulated currents observed in this study for varistor samples doped with different amounts of Co, due to their recovery from asymmetrical electric stress, could not be controlled by movement of Zn interstitials with activation energy 0.55 v eV, as it is widely believed, for the TSC activation energy determined in this experiment was 0.39 v eV.     

Histochemical and Phytochemical Analysis of Lamium album subsp. album L. Corolla: Essential Oil,Triterpenes, and Iridoids

The aim of this study was to conduct a histochemical analysis to localize lipids, terpenes, essential oil, and iridoids in the trichomes of the L. album subsp. album corolla. Morphometric examinations of individual trichome types were performed. Light and scanning electron microscopy techniques were used to show the micromorphology and localization of lipophilic compounds and iridoids in secretory trichomes with the use of histochemical tests. Additionally, the content of essential oil and its components were determined using gas chromatography-mass spectrometry (GC-MS). Qualitative analyses of triterpenes carried out using high-performance thin-layer chromatography (HPTLC) coupled with densitometric detection, and the iridoid content expressed as aucubin was examined with spectrophotometric techniques. We showed the presence of iridoids and different lipophilic compounds in papillae and glandular and non-glandular trichomes. On average, the flowers of L. album subsp. album yielded 0.04 mL/kg of essential oil, which was dominated by aldehydes, sesquiterpenes, and alkanes. The extract of the L. album subsp. album corolla contained 1.5 × 10⁻³ ± 4.3 × 10⁻⁴ mg/mL of iridoid aucubin and three triterpenes: oleanolic acid, β-amyrin, and β-amyrin acetate. Aucubin and β-amyrin acetate were detected for the first time. We suggest the use of L. album subsp. album flowers as supplements in human nutrition.     

An approximation theorem of wong-zakai type for nonlinear stochastic partial differential equations

We present an extension of the Wong-Zakai approximation theorem for nonlinear 984 given by the Wiener process and a martingale. By approximating these disturbances we obtain in the limit equation the Ito correction term for the infinite dimensional case. Such form of the correction term connected with the Wiener process was proved in the author's papers [21] and [22], where the approximation theorem for semilinear stochastic evolution equations in Hilbert spaces was studied. Our model here is similar as the one considered by Pardoux [17]     

Conformational Dynamics in the Core of Human Y145Stop Prion Protein Amyloid Probed by Relaxation Dispersion NMR

Microsecond to millisecond timescale backbone dynamics of the amyloid core residues in Y145Stop human prion protein (PrP) fibrils were investigated by using ¹⁵N rotating frame (R_1ρ) relaxation dispersion solid-state nuclear magnetic resonance spectroscopy over a wide range of spin-lock fields. Numerical simulations enabled the experimental relaxation dispersion profiles for most of the fibril core residues to be modelled by using a two-state exchange process with a common exchange rate of 1000 s⁻¹, corresponding to protein backbone motion on the timescale of 1 ms, and an excited-state population of 2 %. We also found that the relaxation dispersion profiles for several amino acids positioned near the edges of the most structured regions of the amyloid core were better modelled by assuming somewhat higher excited-state populations (∼5–15 %) and faster exchange rate constants, corresponding to protein backbone motions on the timescale of ∼100–300 μs. The slow backbone dynamics of the core residues were evaluated in the context of the structural model of human Y145Stop PrP amyloid.     

Separation and purification of scandium: From industry to medicine

Scandium and its compounds are used in many modern industrial fields due to its unique chemical and physical properties. It is mainly recovered from residues and wastes in the production of other metals. The exploitation of the ores and wastes could contaminate water and soil creating environmental problems. This paper discusses recent developments and tendencies in scandium separation, purification and preconcentration from different wastes, residues, environmental samples as well as in the production of radiopharmaceuticals for nuclear medicine, both in the laboratory and on the industrial scale. The period reviewed here mainly includes publications that have appeared, since 2010.     

Preprocessed barley,rye, and triticale as a feedstock for an integrated fuel ethanol-feedlot plant

Rye, triticale, and barley were evaluated as starch feedstock to replace wheat for ethanol production. Preprocessing of grain by abrasion on a Satake mill reduced fiber and increased starch concentrations in feedstock for fermentations. Higher concentrations of starch in flours from preprocessed cereal grains would increase plant throughput by 8–23% since more starch is processed in the same weight of feedstock. Increased concentrations of starch for fermentation resulted in higher concentrations of ethanol in beer. Energy requirements to produce one L of ethanol from preprocessed grains were reduced, the natural gas by 3.5–11.4%, whereas power consumption was reduced by 5.2–15.6%.     

Crystal structure and thermoanalytical study of a manganese(II) complex with 1-allylimidazole

The crystal structure of a manganese(II) 1-allylimidazole complex ([Mn(1-AIm)₃(NO₃)₂], where 1-Aim=1-allylimidazole), was characterized by X-ray diffraction (XRD) using SHELX-97. The thermal behaviour of the complex was investigated by thermogravimetry (TG) coupled with an FTIR unit. The complex showed a multi-step decomposition related to the release of the ligand molecules, followed by oxidation. The final residue at 1073 K was found to be manganese(II) oxide. Evolved gas analysis allowed to prove the oxidative decomposition pattern of the examined complex, initially proposed by the percentage mass loss data. Finally, a kinetic analysis of the oxidative decomposition steps was made using the Kissinger equation, while the complex nature of the decomposition kinetics was revealed by the isoconversional Ozawa-Flynn-Wall method.     

Pd electrodeposited from membrane-separated thin layer cell

Polycarbonate (PC) membranes of different porosity (from 50 nm to 400 nm pore size) were used as separators in a thin layer cell for palladium electrodeposition. Atomic force microscopy (AFM) confirmed the formation of Pd layer between the cathode and porous membrane, with subsequent growth inside the pores induced by space limitations of further growth of initial layer. Our estimates confirm that at this stage Pd deposit feels the pronounced mechanical pressure and consider it as a possible reason of specific hydrogen sorption behaviour in the region of β-phase hydride formation. Up to c.a. 1.0 H/Pd atomic ratio is observed for some samples. We consider possible (nano)structural peculiarities responsible for this behaviour.