Characterization and TLC-Bioautographic Detection of Essential Oils from Some Thymus Taxa. Determination of the Activity of the Oils and their Components Against Plant Pathogenic Bacteria

JPC – Journal of Planar Chromatography – Modern TLC - The chemical composition of the oils of four thyme (Lamiaceae) chemotypes (Thymus vulgaris L., Thymus serpyllum L., Thymus x...     

CP violation and the widthZ→b \bar b

We discuss the effect of CP-violatingZb $\bar b$ Zb $\bar b$ G andZb $\bar b$ γ couplings on the width Γ(Z→b $\bar b$ X). The presence of such couplings leads in a natural way to an increase of this width relative to the prediction of the standard model. Various strategies of a direct search for such CP-violating couplings by using CP-odd observables are outlined. The number ofZ bosons required to obtain significant information on the couplings in this way is well within the reach of present LEP experiments.     

Thiazonaphthalimide derivatives: Synthesis and interaction with DNA

The synthesis of several thiazonaphthalimide derivatives is described. The exclusive formation of angular rather than linear isomers was unequivocally demonstrated by NMR and single crystal X-ray diffraction. Their photophysical properties and ability to bind calf-Thymus DNA with affinities in the range of 10⁴ makes them interesting candidates to probe DNA by fluorescence.     

Optimization of Growth Conditions for Test Fungus Cultures used in Direct Bioautographic TLC Detection. 3. Test Fungus: Candida albicans

JPC – Journal of Planar Chromatography – Modern TLC - Optimum conditions have been established for culture of the fungus Candida albicans (ATCC 90028) for microbial detection of zones...     

Thin-layer chromatography-densitometry and liquid chromatography analysis of alkaloids in leaves of Papaver somniferum under stress conditions

The effect of stress conditions on the concentrations of secondary metabolites were examined during various developmental stages of Papaver somniferum plants. P. somniferum plants were grown in laboratory conditions (Budakalász). The experiment consisted of 22 treatments. Significantly different alkaloid contents can be observed under different stress conditions. In general, the alkaloid contents of plants are very low; therefore, a highly sensitive and reliable method has to be developed for analysis. The amount of alkaloids was measured by 2 separation and detection techniques. Accuracy of the thin-layer chromatography method for quantitative analysis is limited. Without purification of samples the background is too noisy. Column liquid chromatography is a sensitive and relatively inexpensive method that allows precise quantitative determination of the alkaloid content.     

Nanophase separation in segmented polyurethane elastomers: Effect of specific interactions on structure and properties

Polyurethanes were prepared from 4,4′-methylenebis (phenyl isocyanate) (MDI), 1,4-butanediol (BD) and poly (tetrahydrofurane) polyether polyol (PTHF). The -OH functional group ratio of polyol/total diol was kept constant at 0.4 in all experiments, while the ratio of the isocianate and hydroxyl groups (NCO/OH) changed between 0.940 and 1.150. Melt polymerization was carried out in an internal mixer. The polymers were characterized with a number of methods including GPC, FTIR, WAXS, DSC, DMA and tensile testing. Changing stoichiometry modifies molecular weight as expected, but the relative concentration of end-groups also changes at the same time. The respective end-groups preferentially associate with each other leading to phase separation. -OH end-groups enter into weaker interactions with each other than urethane and amine groups. The extent of phase separation, as well as the size and properties of the dispersed phase depend on composition. Each property of the polymer is affected differently by molecular weight and phase separation. Melt viscosity depends mostly on the length of the molecules, ultimate tensile properties are influenced also by interactions, while stiffness is determined almost exclusively by phase structure.     

HPTLC and HPLC Determination of Alkaloids in Poppies Subjected to Stress

JPC – Journal of Planar Chromatography – Modern TLC - Papaver somniferum produces secondary metabolites which have important roles in self-defense processes, in plant biochemistry, and...     

Soft photons in hadron-hadron collisions: synchrotron radiation from the QCD vacuum?

We discuss the production of soft photons in high energy hadron-hadron collisions. We present a model where quarks and antiquarks in the hadrons emit synchrotron light when being deflected by the chromomagnetic fields of the QCD vacuum, which we assume to have a nonperturbative structure. This gives a source of prompt soft photons with frequencies <~300 mev=" in=" the=" c.m.=" system=" of=" the=" collision=" in=" addition=" to=" hadronic=" bremsstrahlung.=" in=" comparing=" the=" frequency=" spectrum=" and=" rate=" of=">synchrotron photons to experimental results we find some supporting evidence for their existence. We make an exclusive-inclusive connection argument to deduce from the synchrotron effect a behaviour of the neutron electric formfactorG _E ⁿ (G ²) proportional to (Q ²)^1/6 forQ ²20 fm^–2. We find this to be consistent with available data. In our view, soft photon production in high energy hadron-hadron and lepton-hadron collisions as well as the behaviour of electromagnetic hadron formafactors for lowQ ² are thus sensitive probles of the nonperturbative structure of the QCD vacuum.     

A Sensitive Method for Thin-Layer Chromatographic Detection of Amphotericin B

JPC – Journal of Planar Chromatography – Modern TLC - Thin-layer chromatography with microbiological detection (direct bioautography) of amphotericin B. has never been reported. The...