X-ray fluorescent method for the analysis of trace elements in bio-materials with correction of the matrix effect.

A method for correcting the matrix effect by measuring the intensity of fluorescent radiation and its absorption by the sample material in the same x-ray optical scheme is proposed. The use of a complex secondary Ag-Ge emitter as a primary radiation source provides a low detection limit for a wide range of chemical elements from Ca (Z = 20) to Mo (Z = 42) in the K-series and from Cd (Z = 48) to Bi (Z = 83) in the L-series. To measure the absorption, the radiation of an additional secondary emitter is used, of which the wavelength can be varied in the range from 0.

Effect of the Acid Medium on the Synthesis of Polybenzimidazoles Using Eaton's Reagent.

The influence of trifluoromethanesulfonic (TFSA) superacid on conditions of the synthesis of polybenzimidazoles, such as OPBI and CFPBI, was studied. It was shown that the polycondensations proceeded smoother and at lower temperatures in the presence of the TFSA in Eaton's Reagent and that polymers of high molecular weights, and readily soluble in organic solvents, were obtained. The effect was more pronounced for CFPBI, where the low reactivity monomer, 4,4' (hexafluoroisoproylidene)bis (benzoic acid), was used.

Trifluoromethyl-stabilized 2D nitrogen clusters: a theoretical study.

The stability of 2D all nitrogen clusters containing from 6 to 96 nitrogen atoms, terminated with CF groups, has been explored using two computational models: dispersion corrected B3LYP functional and scaled opposite spin Møller-Plesset perturbation theory (SOS-MP2). Single point domain-based local pair natural orbital coupled-cluster theory calculations (DLPNO-CCSD(T)) was used for further energy refinement. All systems were found to be minima, and their stability increases with CF/N ratio.

Analysis of Multiple Drug Resistance Mechanism in Different Types of Soft Tissue Sarcomas: Assessment of the Expression of ABC-Transporters, MVP, YB-1, and Analysis of Their Correlation with Chemosensitivity of Cancer Cells.

Chemotherapy of soft tissue sarcomas (STS) is restricted by low chemosensitivity and multiple drug resistance (MDR). The purpose of our study was the analysis of MDR mechanism in different types of STS. We assessed the expression of ABC-transporters, , , and analyzed their correlation with chemosensitivity of cancer cells.