Thermooxidative degradation of blends based on poly(3-Hydroxybutyrate). Specifics of the process

The relationship between the structure and the kinetics of the thermal oxidation of the poly(3-hydroxybutyrate) — ethylene propylene rubber and polyethylene — poly(3-hydroxybutyrate) systems is studied. For the first system containing 30–50 wt % poly(3-hydroxybutyrate), phase inversion is observed, which affects its reactivity. For the compositions with polyethylene, two stages of oxidation manifest themselves: before and after poly(3-hydroxybutyrate) degradation.     

A Study of ibuprofen solubility in supercritical carbon dioxide by Fourier-transform infrared spectroscopy

In the work, a method of study of solubility of pharmaceutical substances in high-pressure gases and supercritical media with Fourier-transform IR spectroscopy has been developed. An investigation of the process of ibuprofen dissolution in supercritical carbon dioxide (SC CO₂) in a real-time scale has been performed. On the basis of analysis of the time dependences of the integral intensities of the selected IR-absorption bands of ibuprofen on the value of the initial weighed portion the value of solubility (molar fraction) of ibuprofen in SC CO₂ at a temperature of 35°C and pressure of 15.0 MPa was obtained, being equal to (8.9 ± 1.6) × 10^?3.     

Conducting polymeric composites based on butadiene-acrylonitrile latex

The possibility of controlling the physicochemical and electric properties of conducting latex composites based on butadiene-acrylonitrile latex and carbon fillers, using data on the content of active centers on the filler surface and their distribution with respect to donor-acceptor properties, was examined. To make the fillers compatible with the latexes and prevent their coagulation, the fillers were modified with Leukanol.     

A review of normalization techniques in analytical atomic spectrometry with laser sampling: From single to multivariate correction

Despite many advantages of laser sampling in analytical atomic spectrometry, the signal intensity of these hyphenated methods suffers from the specific influences resulting from the laser ablation process of a sample. The problems that arise affect the accuracy and precision of analytical results. Different techniques of analytical signal normalization which improve figures-of-merit for atomic spectrometry with laser sampling are considered in this review. The characteristics and application of these approaches including the use of internal standards, single or several reference signals and multivariate correction of analytical signal are discussed.     

High-power laser diodes of the spectral region of 808 nm and 980 nm

A technique for assembling high-power laser diodes emitting at 808 and 980 nm was developed, which stably provides high radiation parameters when using one of the standard types of heat sinks for assembling high-power laser diodes, i.e., the C-mount. The maximum achievable power of laser diodes with a stripe contact width of 150 µm in the cw lasing mode was 25 W at a temperature of 20 °C.     

Non-destructive NIR-FT-Raman analyses in practice. Part 1. Analyses of plants and historic textiles

Non-destructive analysis of natural substances in plants as well as of old dyed textiles by Raman spectroscopy has not been possible using conventional techniques. Exciting lines from the visible part of the spectrum produced photochemical and thermal decomposition of the objects as well as strong fluorescence. Using Nd:YAG laser excitation at 1,064 nm together with a special sample arrangement and interferometric recording, various polyacetylenes in Aethusa cynapium and in chamomile (Chamomilla recutita) and the main valuable substances in gentian species (Gentiana lutea and G. punctata), curcuma roots (Curcuma longa), cinnamon (Cinnamomum zeylanicum), fennel (Foeniculum vulgare), clove (Caryophyllus aromaticus), and ginger (Zingiber officinale) were analyzed non-destructively and discussed in comparison with the corresponding pure standard compounds. We further analyzed non-destructively the FT Raman spectra of collections of historical textiles and lakes used for dyeing. It is possible to distinguish the main dye component non-destructively by using Raman bands.