Chemical composition of the essential oils from the flower, leaf and stem of Lonicera japonica

The essential oils from different aerial parts of Lonicera japonica have been extracted by hydro-distillation and analyzed by gas chromatography and gas chromatography coupled with mass spectrometry. Quantitative and qualitative differences were found between the analyzed plant parts. A total of eighty-nine compounds were identified. The main constituents were (Z,Z)-farnesole (16.2%) and linalool (11.0%) for the flowers fraction, hexadecanoic acid (16.0%) and linalool (8.7%) for the leaves fraction, and hexadecanoic acid (31.4%) for the stems. Monoterpene hydrocarbons were absent from all the oils, and oxygenated sesquiterpenes were not identified in the essential oil of the stem.     

Coating of zinc ferrite particles with a conducting polymer, polyaniline

Particles of zinc ferrite, ZnOFe2O3, were coated with polyaniline (PANI) phosphate during the in situ polymerization of aniline in an aqueous solution of phosphoric acid. The PANI-ferrite composites were characterized by FTIR spectroscopy. X-ray photoelectron spectroscopy was used to determine the degree of coating with a conducting polymer. Even a low content of PANI, 1.4 wt%, resulted in the 45% coating of the particles' surface. On the other hand, even at high PANI content, the coating of ferrite surface did not exceeded 90%. This is explained by the clustering of hydrophobic aniline oligomers at the hydrophilic ferrite surface and the consequent irregular PANI coating. The conductivity increased from 2 x 10(-9) to 6.5 S cm(-1) with increasing fraction of PANI phosphate in the composite. The percolation threshold was located at 3-4 vol% of the conducting component. In the absence of any acid, a conducting product, 1.4 x 10(-2) Scm(-1), was also obtained. As the concentration of phosphoric acid increased to 3 M, the conductivity of the composites reached 1.8 S cm(-1) at 10-14 wt% of PANI. The ferrite alone can act as an oxidant for aniline; a product having a conductivity 0.11 S cm(-1) was obtained after a one-month immersion of ferrite in an acidic solution of aniline.     

On partially null and pseudo null curves in the semi-euclidean space R^{4}_{2}

In this paper, we obtain the Frenet equations of a pseudo null and a partially null curves, lying fully in the semi–Euclidean space , and classify all such curves with constant curvatures.     

Electroosmotic flow changes due to interactions of background electrolyte counter-ions with polyethyleneimine coating in capillary zone electrophoresis of proteins

The properties and behavior of polyethyleneimine (PEI) covalently coated capillaries with respect to different background electrolytes used in capillary zone electrophoresis (CZE) are described. The coating stability and changes of inner surface charge in the capillary were followed by measurement of electroosmotic flow (EOF). Interest was focused mainly on conjugate bases of carboxylic acids as anionic background electrolyte components (acetate, citrate, malate, malonate, tartrate, and succinate). An interesting phenomenon was observed in PEI-coated capillaries: The direction (and the magnitude) of EOF depends on the composition of the background electrolyte and at a certain pH it can undergo reversible change. Ionic complex formation was suggested as a hypothesis to explain this behavior. With this knowledge, the PEI-coated capillary was used for the separation of basic proteins in the above-mentioned background electrolytes. A standard protein mixture of cytochrome c, ribonuclease A, and lysozyme at a concentration of 0.25 mg/mL each was chosen as model sample.     

Effect of support on activity of palladium catalysts in nitrobenzene hydrogenation

The effect of two types of catalysts on the activity of the catalytic hydrogenation of nitrobenzene was studied. Catalysts were prepared by the surface deposition of palladium hydroxide with a simultaneous reduction with formaldehyde in a basic environment and were characterised by X-ray powder diffraction, transmission electron microscopy, adsorption-desorption, and catalytic tests — hydrogenation of nitrobenzene in methanol. The influence of the supports’ (activated carbon and a mixture of activated carbon and multi-walled carbon nanotubes) surface area is discussed. Despite having a size comparable (4–5 nm) to crystallites of metallic palladium, the catalyst prepared on a mixture of activated carbon and nanotubes (Pd/C/CNT) was significantly less active than the catalyst prepared on pure activated carbon (Pd/C); the rate of this reaction was approximately 30 % lower than the initial reaction rate. This feature could be attributed to the lower specific surface area of the Pd/C/CNT (531 m² g^?1) in comparison with the Pd/C (692 m² g^?1).     

Protein Separation and Enzyme Purification by Preparative Capillary Isotachophoresis

The use of preparative capillary isotachophoresis (CITP), operating in a discontinuous fractionation mode, for separation and fast purification of the enzyme uridine diphosphate galactopyranose mutase (UGM) from the cell extract of Escherichia coli overproducing the recombinant enzyme is presented in this feasibility study. UGM is required to produce galactofuranose for the cell wall biosynthesis of many pathogenic microorganisms and represents a very attractive candidate for the development of new antimicrobial drugs. CITP separations were carried out under slightly alkaline pH conditions (8.7), in which UGM enzyme is negatively charged. Significantly simplified proteinous matrix isolated in several fractions by employed preparative CITP procedure with the aid of properly selected discrete spacers was subsequently confirmed by SDS PAGE with Coomassie staining. It was shown that preparative CITP is very effective tool for fast purification of the target enzyme from other proteinous matrix constituents when purification and isolation step lasted 20 min. The enzymatic activity of UGM was confirmed in the sample after the preparative CITP purification step, which is a crucial requirement for further biochemical applications.     

Continuous flow electrophoretic separation — Recent developments and applications to biological sample analysis

Continuous flow electrophoretic separation with continuous sample loading provides the advantage of processing volumes of any sizes, as well as the benefit of a real-time monitoring and optimization of the separation process. In addition, the spatial separation of the sample enables collecting multiple separated components simultaneously and in a continuous manner. The separation is usually performed in mild buffers without organic solvents and detergents (sample biological activity is retained) and it is carried out without usage of a solid support in the separation space preventing the interaction of the sample with it (high sample recovery). The method is used for the separation of proteins/peptides in proteomic applications, and its great applicability is to the separation of the cells, cellular organelles, vesicles, membrane fragments, and DNA. This review focuses on the electrophoretic separation performed in a continuous flow and it describes various electrophoretic modes and instrumental setups. Recent developments in methodology and instrumentation, the integration with other techniques, and the application to the biological sample analysis are discussed as well.     

Electrorheology of aniline oligomers

Aniline oligomers were prepared by the oxidation of aniline with p-benzoquinone in aqueous solutions of methanesulfonic acid (MSA) of various concentrations. Their molecular structures were assessed by Fourier transform infrared spectroscopy. The electrorheological (ER) behavior of their silicone oil suspensions under applied electric field has been investigated. Shear stress at a low shear rate, τ _0.9, was used as a criterion of the rigidity of internal structures created by the application of an electric field. It was established from the fitting of the dielectric spectra of the suspensions with the Havriliak–Negami model that dielectric relaxation strength, as a degree of polarization induced by an external field contributing to the enhanced ER effect, increases and relaxation time, i.e., the response of the particle to the application of the field, decreases when a higher molar concentration of MSA is used. The best values were observed for suspensions of the sample prepared in the presence of 0.5 M of MSA. This suspension creates stiff internal structures under an applied electric field strength of 2 kV mm^?1 with τ _0.9 of nearly 50 Pa, which is even slightly of higher value than that obtained for standard polyaniline base ER suspension measured at the same conditions. The concentration of the MSA used in the preparation of oligomers seems to be a crucial factor influencing the conductivity, dielectric properties and, consequently, rheological behavior, and finally ER activity of their suspensions.     

Total synthesis of N,O,O,O-tetraacetyl-d-ribo-phytosphingosine and its 2-epi-congener

Total synthesis of the natural d-ribo-phytosphingosine I and its 2-epimer III in the protected form was achieved through a common strategy. The aza-Claisen rearrangement of allylic thiocyanate (Z)-V incorporated the new stereogenic centre with nitrogen and the subsequent Wittig olefination constructed a non-polar side chain. Hydrogenation, followed by removal of protecting groups, completed the syntheses of I and III.