Electrostrictive properties of ceramics obtained on the basis of ferroelectrk relaxors

We present the results for search of the best ceramic materials for electrostrictive transducers. We performed the following investigations: (1) investigation of different types of ferroelectric, antiferroelectric and non-polar complex oxides with perovskite (OPS) and tetragonal tungsten bronze (TBS) structures; (2) the investigations of the OPS with different degrees of the cations ordering; (3) the measurements of the electrostrictive coefficient Q, Curie-Weiss constant C_W, coefficient of linear thermal expansion λ, polarization P and dielectric permittivity ^σ_r; (4) the X-ray analysis of the structure. The electrostrictive deformation may be very high and the relative strain can be of the order 10^-3 in such materials.     

UNIQUENESS OF DISPLACEMENT-HEAT FLUX AND STRESS-TEMPERATURE PROBLEMS IN THERMOELASTICITY WITH ONE RELAXATION TIME

Two uniqueness theorems of linear thermoelasticity with one relaxation time corresponding to natural initial boundary value problems described in terms of two different pairs of thermoelastic variables: displacement-heat flux and stress-temperature are proved.     

Determination of selenomethionine and selenocysteine in human serum using speciated isotope dilution-capillary HPLC-inductively coupled plasma collision cell mass spectrometry

A method for the accurate determination of selenoamino acids in human serum by HPLC-ICPMS was developed using the species-specific isotope dilution analysis principle. A serum sample was enzymatically digested with a mixture of lipase and protease after derivatization of the selenocysteine residues with iodoacetamide. The selenoamino acid fraction was isolated by size exclusion LC followed by the separation of selenomethionine and the carboxymethylated selenocysteine by capillary HPLC. The isotope-specific determination of 77Se and 80Se was achieved on-line by ICP collision cell MS allowing the removal of polyatomic interferences. Quantification was carried out by isotope dilution using a 77Se-labeled selenomethionine spike and the determination of the 77Se/80Se ratio in the cHPLC selenomethionine peak. The accurately determined selenomethionine was used as an internal standard for the selenocysteine determination from the same chromatogram. The modification of the previously developed cHPLC-ICPMS interface allowed the reduction of the absolute detection limits twice (down to the 75-fg level), which resulted in the lowest ever reported procedural detection limits (below 0.5 ng g(-1) for a 450-mg serum sample). The precision was less than 5% RSD. The method was validated by the mass balance of selenium (amino acid incorporated vs total).     

Identification of water-soluble selenium-containing proteins in selenized yeast by size-exclusion-reversed-phase HPLC/ICPMS followed by MALDI-TOF and electrospray Q-TOF mass spectrometry

An approach to speciation of selenium incorporated in yeast proteins was developed. The tryptic digest of a water-soluble protein fraction isolated by size-exclusion chromatography was analyzed by reversed-phase HPLC/ICPMS. The selenopeptides selected owing to the detector's elemental specificity were then analyzed by MALDI-TOFMS in order to select target ions for collision-induced dissociation MS. The latter, carried out with an electrospray Q-TOF spectrometer, enabled the sequencing of the selenopeptides detected by HPLC/ICPMS. The approach allowed for the first time the identification of a family of Se-containing proteins resulting from the replacement by selenomethionine of 2-9 methionine residues in a salt-stress-induced protein SIP18 (Mr 8874). The presence of these proteins was confirmed by MALDI-TOFMS of the original (nondigested) protein fraction. Another selenium protein identified was a heat-shock protein HSP12 (Mr 11693) in which the only methionine residue was replaced by selenomethionine. These two Se-containing proteins accounted for more than 95% of selenium in the water-soluble protein fraction.     

Development of a sheathless interface between reversed-phase capillary HPLC and ICPMS via a microflow total consumption nebulizer for selenopeptide mapping

A sheathless interface based on a total consumption micronebulizer operating at flow rates in the range 0.5-7.5 microL min(-1) was developed between capillary HPLC and ICPMS. It allowed the efficient nebulization and transport into the plasma of mobile phases containing up to 100% organic solvent without either cooling the spray chamber or oxygen addition. The coupled system was applied to selenopeptide mapping in a protein fraction isolated from a selenized yeast extract. The detection limits were 150 (80Se) and 200 fg (82Se) for a quadrupole instrument with and without a collision cell, respectively, which is a factor 100-150 less than that reported elsewhere for HPLC-ICPMS. The minimal peak broadening ( approximately 5 s at the half-height) allowed baseline resolution of a mixture containing more than 30 selenopeptides, many of which could not be separated using the conventional HPLC-ICPMS coupling.     

Computer-aided design of a factor Xa inhibitor by using MCSS functionality maps and a CAVEAT linker search

We have investigated a new approach to efficiently find a novel inhibitor against a serine protease (i.e. an activated coagulation factor X, FXa) by using de novo design programs and the X-ray crystal structure of the target enzyme. FXa is a coagulant enzyme that generates thrombin (a serine protease) and participates in both intrinsic and extrinsic coagulation pathways. We adopted multiple copy simultaneous search (MCSS) and CAVEAT linker search techniques, which disclosed a novel FXa inhibitor (T01312) consisting of two binding moieties (the benzamidinyl and adamantyl groups) and a linker unit (the carboxybenzylamine group). The inhibitory activity of T01312 against FXa was determined to be a small K(i)-value of 48nM, which is two orders of magnitude smaller than that against thrombin. An X-ray crystal analysis of T01312 complexed with trypsin (an analogue of FXa) and docking studies of T01312 with trypsin and FXa showed that: (i) the benzamidinyl group is a predominant binding moiety in the anionic pocket (S1 site) with an asparatic acid residue; (ii) a hydrophobic pocket (S4 site) is the binding site of the adamantyl group; (iii) the carboxylate group of the linker contributes to the selectivity for FXa against thrombin. Thus, the combination of the knowledge of the X-ray crystal structure of the target molecule with MCSS and CAVEAT linker search techniques proved to be an effective hit-finding method that does not require the screening of huge compound libraries.     

Carbon materials modified by plasma treatment as electrodes for supercapacitors

The carbon material was modified by RF plasma with various reactive gases: O₂, Ar and CO₂. Physicochemical properties of the final carbon products were characterized using different techniques such as gas adsorption method and XPS. Plasma modified materials enriched in oxygen functionalities were investigated as electrodes for supercapacitors in acidic medium. The electrochemical measurements have been carried out using cyclic voltammetry, galvanostatic charge/discharge and impedance spectroscopy. The electrochemical measurements have confirmed that capacity characteristics are closely connected with a type of plasma exposition. Modification processes have an influence on the kind and amount of surface functional groups in the carbon matrix. The moderate increase of capacity of carbon materials modified by plasma has been observed using symmetric two-electrode systems. Whereas investigations made in three-electrode system proved that the suitable selection of plasma modification parameters allows to obtain promising negative and positive electrode materials for supercapacitor application.     

Chemical composition of Pinus sibirica nut oils

The chemical composition of oil obtained from Pinus sibirica was investigated. The nonpolar lipids were the predominant lipid fraction while the triacylglycerols were the major component of this fraction. α‐ and γ‐tocopherols were the dominant tocopherols in pine oils. Eleven fatty acids (FA) were identified in pine nut oil. The unsaturated FA comprised over 90% of the total FA. Of these, polyunsaturated FA accounted for 66% of the total FA. 18:2 and 18:3 acids were the dominant unsaturated FA, while palmitic and stearic acids were the major saturated FA. Three unusual FA, namely 10,13‐octadecadienoic, gorlic and 11,13‐eicosadienoic acid, were tentatively identified in pine nut oil.