Thermal drift compensation method for microbolometer thermal cameras

We propose a new method of compensation for drifts in thermal cameras using a filter in place of a shutter. The latter method requires periodically closing the camera, thus causing the images to appear frozen frequently. Our technique of replacing the shutter with a filter eliminates this frozen image problem. In this paper we discuss the principles of the new method and present the obtained results.     

Chiral analysis of chloro intermediates of methylamphetamine by one-dimensional and multidimentional NMR and GC/MS

Impurity profiling and classification of abused drugs using chiral analytical techniques is of particular interest and importance because of the additional information obtained from this approach. When these methods are applied to the synthesis of illicitly used substances, they can supply valuable information about the conditions/chemicals used in the synthesis. We have applied GC and NMR methods to the study of intermediates found in methylamphetamine manufacture with the aim of linking the intermediates to the ephedrine/pseudoephedrine starting materials. Therefore, determination of the stereochemical makeup within samples of forensic interest is important giving further specific information to the analyst. This study investigates the stereochemical course of the Emde synthesis of methylamphetamine with particular focus on intermediate formation via the chlorination of ephedrine and pseudoephedrine enantiomers. The configurations of these chloro-phenethylamines were determined by 1D and 2D NMR analysis, and thereafter, the GC/MS analysis was carried out. We have shown here that chlorination of the ephedrine/pseudoephedrine compounds occurs via inversion (S(N)2) and retention (S(N)i) of configuration around the α carbon and mixture of diastereoisomers (chloroephedrine and chloropseudoephedrine) were formed, with the ratio of the resulting compounds dependent on the precursors used. The preparation and analytical properties of these intermediate standards provide data for laboratories interested in the stereochemical analysis of methylamphetamine intermediates such as forensic/law enforcement, and illustrate the value of using a combination of analytical methodology.     

Factors affecting usefulness of triticale grain for bioethanol production

BACKGROUND: Triticale grain could be a useful material for bioethanol production. The aim of this study was to examine how grain cultivar, nitrogen fertilisation level, location and year affect the starch content in triticale grain and which method of starch determination, polarimetric, enzymatic or near‐infrared transmission (NIT), gives the best prediction of real bioethanol productivity from triticale grain. RESULTS: It was found that the starch content in triticale grain was correlated positively with test weight and 1000‐kernel weight but negatively with falling number and protein content. All factors, i.e. cultivar, nitrogen fertilisation level, location and year, as well as the intrinsic interaction between these factors, had a significant effect on the starch level in triticale grain. The NIT procedure of starch determination gave the best results in predicting the real yield of ethanol obtained on the basis of classic fermentation (95% match), while the enzymatic and polarimetric methods corresponded with the real results at levels of 89–90 and 78–82% respectively. CONCLUSION: Grain growth conditions related to location and nitrogen fertilisation level had the most noticeable effect on grain starch content, while grain yield per hectare had the most significant effect on ethanol productivity. Copyright © 2010 Society of Chemical Industry     

Antioxidants in thermally treated buckwheat groats

The seeds of buckwheat (Fagopyrum esculentum Moench L.) were dehulled and then, following milling, extruded on a counter rotating, twin-screw extruder with the different barrel temperature profiles: 120, 160, and 200 degrees C. After extrusion cooking process, the following compounds were analyzed: free and conjugated phenolic acids, total polyphenols (TPC), tocopherols (T) and tocotrienols (T3), inositol phosphates (IP), reduced glutathione (GSH), and melatonin (MLT). The antioxidant capacity and superoxide dismutase-like activity (SOD-like activity) were determined in the groats and extrudates. Extrusion caused a significant decrease in all the compounds tested, except for phenolic acids. The content of IP decreased by 13%, that of GSH by 42%, and that of T + T3 by 62%. A three-fold lower level of MLT and TPC was noted whereas the SOD-like activity disappeared when compared to the nonextruded material. A two-fold higher content of phenolic acids (free and released from ester bonds) was observed. In spite of the clear decrease in the investigated antioxidants, the extruded dehulled buckwheat seeds contained still significant content of bioactive compounds, which resulted in as little as an average 10% decrease of the antioxidant capacity.     

Kinetics of reduction of gold(III) complexes using H2O2

In this article, the effect of different kinetic parameters, namely, temperature, pH, and reductant concentration, on the rate of Au(III) reduction from aqueous chloride solutions by H₂O₂ was investigated. The possible mechanism of complex [Au(OH)₄]⁻ ion reduction by hydrogen dioxide is also discussed and the model mechanism based on experimental data is postulated. On the basis of the suggested mechanism, the rate equation for Au precipitation is given in the form , in which respective rate constants k ₁, k ₃, and k ₅ were determined experimentally and are given in the text.     

Properties of branched polymer chains adsorbed on a patterned surface

The aim of this study was to investigate the properties of polymer chains strongly adsorbed on a planar surface. Model macromolecules were constructed of identical segments, the positions of which were restricted to nodes of a simple cubic lattice. The chains were in good solvent conditions, thus, the excluded volume was the only interaction between the polymer segments. The polymer model chain interacted via a simple contact potential with an impenetrable flat surface with two kinds of points: attractive and repulsive (the latter being arranged into narrow strips). The properties of the macromolecular system were determined by means of Monte Carlo simulations with a sampling algorithm based on the local conformational changes of the chain. The structure of adsorbed chains was found to be strongly dependent on the distance between the repulsive strips, whenever this distance was very short. The mobility of the chains was also studied and it was found that diffusion across repulsive strips was suppressed for large distances between the strips.     

The Reversal of the Local Magnetic Field Profile at the Surface of Superconducting Sample Caused by the Thermomagnetic Avalanche

It was found experimentally, that after a thermomagnetic avalanche the local surface self-field of a conventional NbTi superconductor may change its sign. To explain this phenomenon it is necessary to assume a break of the symmetry of the screening currents, caused by the thermomagnetic avalanche. A simple theoretical model was developed to explain quantitatively the observed phenomena.     

The photochemical behaviour of naphthoylenebenzimidazolone dyes in 1-methyl-2-pyrrolidone

The photochemical behaviour of selected naphthoylenebenzimidazolone dyes is discussed in terms of the photobleaching of the dyes in the presence of electron donors (phenylthioacetic acid, N-phenylglycine, ethyl 4-N,N-dimethylaminobenzoate) as well as an electron acceptor (1-methoxy-4-phenylpyridinium tetrafluoroborate) that are used in photoredox systems for light-induced polymerization. The fluorescence quenching of the dyes in the presence of the electron donors and the electron acceptor was also examined.