Separation of 23 dansylated amino acids by micellar electrokinetic chromatography at low temperature

Summary The baseline separation of 23 dansylated amino acids (including 3 didansylated species) is reported. Lowering of the analysis temperature and fine control of the surfactant concentration were essential in obtaining this result. Calibration graphs with good linearity were obtained.     

Kinetics of self-condensation of acetone over heterogeneous Ba(OH)2 and Sr(OH)2 catalysts

Catalytic performance of Ba(OH)₂ and Sr(OH)₂ in self-condensation of acetone was examined in the temperature range from 273 to 303 K. A kinetic model of second order with respect to acetone was used for interpretation of the results obtained for the diacetone alcohol formation.This revised version was published online in December 2005 with corrections to the Cover Date.     

Influence of the overall pressure on electrical conductivity of the amorphous semiconductor Ge15Te81S2As2

The experimental results obtained with the chalcogenide glass Ge₁₅Te₈₁S₂As₂ with imposed overall pressure up to 700 MPa are presented. The material exhibits the switching effect and the memory effect. It is shown that the overall pressure changes remarkably d.c. electrical conductivity of the amorphous semiconductor. It is assumed that the changes in conductivity are caused by changes in activation energy. The changes in activation energy within the range of considered pressures are, as follows from our measurements, E/p–10·95×10^–5 eV/MPa +p × 10·41 W 10^–7 eV/MPa². The assumption of the activation energy dependence on pressurep are confirmed also by measurements of dependence In vs. 1/T at various pressures.     

Targeted Hybrid Nanocarriers as a System Enhancing the Skin Structure

The skin is constantly exposed to external and internal factors that disturb its function. In this work, two nanosystems-levan nanoparticles and a surfactin-stabilized nanoemulsion were preserved (tested for microbial growth) and characterized (size, polydispersity, Zeta potential, and stability). The nanosystems were introduced in the model formulations-cream, tonic, and gel, and confirmed by TEM. The analysis showed that nanoemulsion has a spherical morphology and size 220–300 nm, while levan nanoparticles had irregular shapes independently of the use of matrix and with particle size (130–260 nm). Additionally, we examined the antiradical effect of levan nanoparticles and nanoemulsion in the prototype of formulations by scavenging DPPH (2,2-diphenyl-1-picrylhydrazyl; EPR spectroscopy). The model cream with both nanosystems and the whole range of products with nanosystems were evaluated in vivo for hydration, elasticity, smoothness, wrinkles and vascular lesions, discoloration, respectively. The cream improved skin condition in all tested parameters in at least 50% of volunteers. The use of more comprehensive care, additionally consisting of a tonic and gel, reduced the previously existing skin discoloration to 10.42 ± 0.58%. The presented prototype formulations are promising in improving skin conditions.     

Morphology and molecular organisation of liquid-crystalline perylene-3,4,9,10-tetra-(n-hexylester) deposited on a solid substrate

Liquid-crystalline perylene-3,4,9,10-tetra-(n-hexylester) forms characteristic dendritic or flower-like structures at room temperature when it is deposited on a hydrophilic glass substrate using the zone-casting technique. It was found that such unique structures were not possible to be created simply by recrystallisation of this dye from a liquid-crystalline columnar phase. On the basis of the observations using a confocal microscope and the study of wide angle X-ray scattering (WAXS) as well as the analysis of the absorption and fluorescence spectra, some conclusions, concerning the molecular organisation in the dendritic structure, are drawn. Based on the research, one can assume that the dendrites are formed by columnar molecular aggregates with the column axes parallel to the substrate. Such an organisation of the molecules can be interesting from the point of view of organic electronics.     

Heptametallic,Octupolar Nonlinear Optical Chromophores with Six Ferrocenyl Substituents

New complexes with six ferrocenyl (Fc) groups connected to Zn^II or Cd^II tris(2,2′‐bipyridyl) cores are described. A thorough characterisation of their BPh₄^? salts includes two single‐crystal X‐ray structures, highly unusual for such species with multiple, extended substituents. Intense, visible d(Fe^II)→π* metal‐to‐ligand charge‐transfer (MLCT) bands accompany the π→π* intraligand charge‐transfer absorptions in the near UV region. Each complex shows a single, fully reversible Fe^III/II wave when probed electrochemically. Molecular quadratic nonlinear optical (NLO) responses are determined by using hyper‐Rayleigh scattering and Stark spectroscopy. The latter gives static first hyperpolarisabilities β₀ reaching as high as approximately 10^?27 esu and generally increasing with π‐conjugation extension. Z‐scan cubic NLO measurements reveal high two‐photon absorption cross‐sections σ₂ of up to 5400 GM in one case. DFT calculations reproduce the π‐conjugation dependence of β₀, and TD‐DFT predicts three transitions close in energy contributing to the MLCT bands. The lowest energy transition has octupolar character, whereas the other two are degenerate and dipolar in nature.     

Influence of Extraction Solvent on the Phenolic Profile and Bioactivity of Two Achillea Species

The phenolic composition, as well as the antioxidant and antimicrobial activities of two poorly investigated Achillea species, Achillea lingulata Waldst. and the endemic Achillea abrotanoides Vis., were studied. To obtain a more detailed phytochemical profile, four solvents with different polarities were used for the preparation of the plant extracts whose phenolic composition was analyzed using UHPLC-MS/MS (ultra-high performance liquid chromatography-tandem mass spectrometry). The results indicate that both of the investigated Achillea species are very rich in both phenolic acids and flavonoids, but that their profiles differ significantly. Chloroform extracts from both species had the highest yields and were the most chemically versatile. The majority of the examined extracts showed antimicrobial activity, while ethanolic extracts from both species were potent against all tested microorganisms. Furthermore, the antioxidant activity of the extracts was evaluated. It was found that the ethanolic extracts possessed the strongest antioxidant activities, although these extracts did not contain the highest amounts of detected phenolic compounds. In addition, several representatives of phenolic compounds were also assayed for these biological activities. Results suggest that ethanol is a sufficient solvent for the isolation of biologically active compounds from both Achillea species. Moreover, it was shown that the flavonoids naringenin and morin are mainly responsible for these antimicrobial activities, while caffeic, salicylic, chlorogenic, p-coumaric, p-hydroxybenzoic, and rosmarinic acid are responsible for the antioxidant activities of the Achillea extracts.     

Copper and Zinc as Potential Biomarkers of Mood Disorders and Pandemic Syndrome

The diagnosis of affective disorders has been the subject of constant research by clinicians from all over the world for many years. Making an appropriate diagnosis among patients suffering from mood disorders is sometimes problematic due to the personality-changing nature of patients and the similarity in the clinical picture of episodes in affective disorders. For this reason, there is a need to develop rapid and effective methods of determining biological markers that differentiate these diseases. The research was carried out with blood taken from 15 patients and 15 volunteers. The analysis of biological material for trace concentrations of zinc and copper was carried out with the use of ultrasensitive triple-quadrupole inductively coupled plasma mass spectrometry (TQ ICP-MS). The obtained results prove that the concentration of copper in the test group was lower than in the control group. For the zinc concentrations, the inverse relationship was observed. The group of patients was characterized by a higher concentration of this element than the group of healthy volunteers. Summarizing the obtained results and comparing them with the results of studies by other authors, it was found that zinc and copper may be potential biomarkers of affective disorders and pandemic syndrome.