Phenolic Constituents of Lamium album L. subsp. album Flowers: Anatomical,Histochemical, and Phytochemical Study

Flos Lamii albi has a high biological activity and is widely used in herbal medicine. The aim of the study was to characterize the secretory structures present in Lamium album subsp. album corolla and the location of phenolic compounds. Additionally, we carried out qualitative phytochemical analyses of flavonoids and phenolic acids. Light, fluorescence, and scanning electron microscopy were used to analyze the structure of the floral organs. The main classes of phenolic compounds and their localization were determined histochemically. Phytochemical analyses were performed with high-performance thin-layer chromatography (HPTLC) and high-performance liquid chromatography (HPLC). Six types of glandular trichomes were found which contained flavonoids, phenolic acids, and tannins. The phytochemical studies demonstrated the presence of caffeic, chlorogenic, ferulic, gallic, p-coumaric, protocatechuic, syringic, gentisic, and vanillic phenolic acids as well as rutoside, isoquercetin, and quercetin flavonoids. The corolla in L. album subsp. album has antioxidant properties due to the presence of various polyphenols, as shown by the histo- and phytochemical analyses. The distribution and morphology of trichomes and the content of phenolic compounds in the corolla have taxonomic, pharmacognostic, and practical importance, facilitating the identification of the raw material.     

Hard X-ray photoelectron spectroscopy study of core level shifts at buried GaP/Si(001) interfaces

We present a study of buried GaP/Si(001) heterointerfaces by hard X-ray photoelectron spectroscopy. Well-defined thin (4–50 nm) GaP films were grown on Si(001) substrates with 2° miscut orientations by metalorganic vapor phase epitaxy. Core level photoelectron intensities and valence band spectra were measured on heterostructures as well as on the corresponding reference (bulk) substrates. Detailed analysis of core level peaks revealed line broadening and energetic shifts. Valence band offsets were derived for the films with different thickness. Based on the observed variation of the valence band offsets with the GaP film thickness and on the experimental evidence of line broadening, the existence of charge displacement at the GaP/Si(001) interface is suggested.     

Chemical and Pharmacological Properties of 3-(Thiophen-2-yl)-4-substituted-Δ 2-1,2,4-triazoline-5-thiones

Three 3-(thiophen-2-yl)-4-substituted-Δ ² -1,2,4-triazoline-5-thiones were synthesized by intramolecular cyclization of 1-(thiophen-2-ylcarbonyl)-4-substituted thiosemicarbazides in alkaline medium. Their effects on the central nervous system (CNS) of mice in some behavioral tests were investigated. All investigated compounds displayed antinociceptive activity. The correlation between the structural features and bioactivity has been discussed.     

Method of determination of low copper concentration in human hair and nails

A graphite furnace atomic absorption spectrometry (GF-AAS) method was developed for the determination of copper in selected alternative materials. The method is characterised by a low limit of detection, good accuracy and satisfactory precision, while the duration of a single measurement is approximately 80 s. It allowed an application of the developed method to determine copper in small samples of hair and nails with equipment available in most analytical laboratories. The developed GF-AAS method was successfully applied to routine analyses using samples collected from healthy humans. The study has shown similar concentration of copper in fingernails and toenails collected from women and men, which was 2–3 times lower than concentration of this element in hair of both genders. The correlation between concentration of copper in nails and hair allows one to use hair, fingernails and toenails as invariable materials for the evaluation of chronic exposure to copper.     

Thermal transformations of Cu–Mg (Zn)–Al(Fe) hydrotalcite-like materials into metal oxide systems and their catalytic activity in selective oxidation of ammonia to dinitrogen

Layered double hydroxides (LDHs) containing Mg²⁺, Cu²⁺ or Zn²⁺ cations in the Me^II positions and Al³⁺ and Fe³⁺ in the Me^III positions were synthesized by co-precipitation method. Detailed studies of thermal transformation of obtained LDHs into metal oxide systems were performed using high temperature X-ray diffraction in oxidising and reducing atmosphere, thermogravimetry coupled with mass spectrometry and temperature-programmed reduction. The LDH samples calcined at 600 and 900 °C were tested in the role of catalysts for selective oxidation of ammonia into nitrogen and water vapour. It was shown that all copper congaing samples presented high catalytic activity and additionally, for the Cu–Mg–Al and Cu–Mg–Fe hydrotalcite samples calcined at 600 °C relatively high stability and selectivity to dinitrogen was obtained. An increase in calcination temperature to 900 °C resulted in a decrease of their catalytic activity, possibly due to formation of well-crystallised metal oxide phases which are less catalytically active in the process of selective oxidation of ammonia.     

Kinetics of coal and char oxycombustion studied by TG–FTIR

Coal and char oxycombustion is a complex process because of very high reaction rate of oxygen with coals and chars carbon. Very important process during oxycombustion is diffusion of O₂ to surface of coal and char grain. This process can be minimized using small samples and high flow of the gas, but it is also dependent on temperature. For this reason, it is impossible to eliminate diffusion processes which cause significant impact on calculated kinetic parameters. This paper describes the results of thermogravimetric studies of oxycombustion process with evolved gas analysis by FTIR. Ultimate and proximate analysis of coal and char were made. Thermogravimetric experiments of coal and its char oxycombustion were conducted using five heating rates, namely 2.5, 5, 10, 20 and 40 K min^?1, and gas mixture composed of 20 % O₂ in CO₂. Activation energies of coal and char oxycombustion were calculated by isoconversional methods: integral Vyazovkin and differential Friedman. Activation energies for three ranges of heating rates were calculated. This paper shows influence of heating rate on calculated activation energy. The reason of this phenomenon is due to change of the mechanism of coal and char oxycombustion from the chemical kinetic control regime to mixed chemical kinetic–diffusion control regime.     

Potassium trans-[bis(oxalato)diaquacobaltate(II)] tetrahydrate: synthesis, structure, potentiometric and thermal studies

The title compound, trans-K₂[Co(C₂O₄)₂(H₂O)₂]·4H₂O, was synthesised, and characterised by elemental analysis. Acid dissociation constants for the complex were determined by potentiometric titration and calculated by STOICHIO program. The crystal structure of trans-K₂[Co(C₂O₄)₂(H₂O)₂]·4H₂O was determined by X-ray diffraction studies. The asymmetric part of the unit cell contains one symmetric anion of oxalate and water molecule bound with Co(II) ion in crystallographic special position, one potassium cation and two molecules of water. Thermal properties of the complex were examined by thermogravimetric analysis (TGA). A decomposition mechanism is proposed on the basis of the results.     

Application of dispersive liquid–liquid microextraction followed by HPLC–MS/MS for the trace determination of clotrimazole in environmental water samples

A method for the analysis of clotrimazole was developed with dispersive liquid–liquid microextraction for sample pre‐concentration and HPLC–MS/MS for analysis. A linear ion trap was used for the confirmation of clotrimazole identity in the samples. The developed method enables the analysis of clotrimazole in river water and sewage effluent from wastewater treatment plants with a LOQ of 0.7 ng/L. Environmental monitoring of clotrimazole was undertaken. Samples from river water and sewage effluents were analysed over a one‐year period. Clotrimazole was found in every tested sample with concentration range from 1 to 31 ng/L. The amount of clotrimazole in tested samples was highly dependent on sampling season. The highest results were obtained in summer and autumn.     

Comparison of different extraction methods for the determination of α‐ and β‐thujone in sage (Salvia officinalis L.) herbal tea

Salvia officinalis L. (sage) is an important industrial plant used both for food and pharmaceutical purposes. The terpene fraction of this plant is responsible for many of its therapeutic and culinary properties. We used different extraction methods Tenax TA® purge and trap, headspace (HS) solid‐phase microextraction, HS sorptive extraction, and stir bar sorptive extraction to analyze the terpene fraction extracted from sage tea by GC–MS. Twenty compounds were identified, including α‐, β‐thujone, and several other oxygenated monoterpenes (1,8‐cineole, linalool, camphor, boneol, and bornyl acetate) and oxygenated sesquiterpenes (caryophyllene oxide, viridiflorol, humulene epoxide I, II, and III). Tenax TA® and HS sorptive extraction extracted a lower number of identified compounds, whereas HS solid‐phase microextraction allowed the complete extraction of volatiles with particular reference to α‐ and β‐thujone. The importance of the determination of thujones content in sage herbal tea is also discussed.