Biomedical and clinical applications of automated single cell electrophoresis

The automated single cell electrophoresis microscope Parmoquant has been used for the discrimination of lymphocytes and the study of the interaction of substances with cells and synthetic particles. Electrophoretic histograms allowed the determination of changes in the proportion of lymphocyte populations after kidney transplantation, during dialysis treatment, open heart surgery and during pregnancy. Discrimination of leukemic cells on the basis of electrophoresis was used as an additional parameter in diagnosis. In a mouse tumor model, histogram determination enabled the in vivo effect of the tumor necrosis factor on immune cells to be evaluated. Cell electrophoresis was shown to be suitable to detect the influence of antibodies, lectins and bacteria on the cell surface. Protein adsorption was studied on synthetic particles using cell electrophoresis. This method was applied to investigate the phenomena of blood interaction with biomaterials used in artificial organs and to determine differences in the protein composition of serum or other body fluids connected with diseases.     

Nonisothermal thermogravimetry of polymers

The model of weight loss taking place in each step of a scheme of consecutive reactions was applied to nonisothermal thermogravimetric records of bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide). The release of HBr was found to be faster in air than in nitrogen. A significant reduction in the apparent activation energy of dehydrobromination as compared with decomposition of the nonbrominated polymer was ascribed not only to a reduction in the activation energy of the initiation reaction, but also to an increase in the order of the termination reaction (from 1 for the nonbrominated polymer to 2 for the highly brominated polymer).     

Inhibited Oxidation of Cumene and Polymerization of Styrene Investigated by Solution Microcalorimetry

The application of solution microcalorimetry was demonstrated on two model examples – inhibited oxidation of cumene and radical polymerization of styrene.From the experimental dependences of the rate of heat release on time, the rate constants k ₇ of the interaction of an inhibitor with radicals of substrate (RO ₂ ^. or R^.) in oxidation or in polymerization were determined for the set of inhibitors of N-aryl N-(2-quinone) amine series. It was shown that these compounds are weak inhibitors of oxidation of cumene and rather efficient inhibitor of polymerization of styrene.This revised version was published online in November 2005 with corrections to the Cover Date.     

Nonisothermal thermogravimetry of polymers

The decomposition of polyethylene and ethylene-vinyl acetate copolymers in composites with Al(OH)₃ and Mg(OH)₂ (60% by wt.) has been estimated from the aspect of the extent of synchronization of the two fundamental processes, the release of water and flammable volatiles from a polymer and the effect of this on the resulting polymer flammability. An attempt has been made to implement the peculiarities of decomposition observed for each system to the fire behaviour of these materials.     

Effect of natural antioxidants on the stability of polypropylene films

A preliminary study on the efficiency of agri-food industry wastes as stabilizers for polypropylene (PP) films is reported. Several analytical techniques were employed to evaluate the stabilization effectiveness of the additives. DSC and CL analysis performed on unaged samples confirmed the antioxidant activity of natural additives, and provided the following order of efficiency: red grape seeds > white grape seeds > tomato extracts. The films were also artificially aged at 70 °C, and FTIR spectroscopy confirmed the stabilization trend obtained from the unaged films. Kinetic analysis of TG data alongside tensile tests indicated that the tomato extract is a good thermal and processing stabilizer, but it is sensitive to oxidation. In contrast, grape seeds provide long-term stabilization to PP under conditions of oxidative degradation. Our results show that tomato and wine processing by-products have good potential to be exploited as a low-cost source of value-added phytochemicals.     

Ignitability of Polymers Related to Polymer Properties and Different Steady States of Combustion Theoretical Approach

A mathematical model of ignition and burning of organic polymers was used for evaluation and quantification of the tendency of polymers to ignition. The model permits investigation of the influence of one parameter of the polymer on the others. It was found that the model could be used for the verification of the ignitability method developed by Miller et al. [1]. Different steady states of combustion were found when using the model proposed. There is a characteristic steady state for normal flaming combustion, another for non-flaming combustion, and there are also unstable steady states that have no real physical meaning. This revised version was published online in July 2006 with corrections to the Cover Date.     

Behcet brain tissue identified with increased levels of Si and Al

Behcet disease is a multi-system disorder with still uncertain chemical causality. Chemical composition of molecules and elements in a human brain tissue of Behcet diseased patient is of interest. Time-of-flight secondary ion mass spectrometry is used to provide complex composition in Behcet disease and control tissues. Determined organic compounds are represented by fragments of carbohydrates, phospholipids, amino acids, and peptides in both samples without any qualitative differences. Trace heavy elements as Fe, Zn, and Cu are identified in Behcet disease tissue with increased intensities by only an averaged factor of 2.2 in comparison to the control. The significant differences between the control and Behcet disease tissues are in the presence of Si and Al. These two elements have significantly higher intensities by an averaged factor of 10.0 in Behcet disease tissue. The origin of Al and Si occurrence and the chronology of their accumulation are not clear, moreover this observation supports a significance of chemical characterization in an early stage of disease.     

Chemiluminescence from the thermal oxidation of polyisoprene and polybutadiene I. Influence of oxygen pressure on the chemiluminescence of polyisoprene during its oxidation

The influence of oxygen pressure p (0.016-0.1 MPa) on polyisoprene thermal oxidation at 100 °C has been studied by chemiluminescence (CL). The maximum CL intensity was found to be almost proportional to p, whereas the induction time is influenced in the same way but to a lesser extent. Assuming that the classical mechanistic scheme with initiation by bimolecular hydroperoxide decomposition and termination by bimolecular radical combination, partially studied by Tobolsky and co-workers in the 1950s, is valid, it was established that chemiluminescence originates essentially from hydroperoxide decomposition. A theory which tries to reconcile this result with the most popular hypothesis according to which light is emitted by terminating peroxyl bimolecular combination is proposed.