Radial difference distribution functions were calculated for PC and a-PS in a temperature range from 293 K to 455 K using wide angle X-ray scattering. Corrections of experimental scattering curves were examined. An assignment for some distances to intra-and intermolecular correlations was made. Next neighbour distances obtained from RDDFs are in good agreement with theoretically computed distances. ZusammenfassungRadiale Dichtedifferenzfunktionen ffir PC and a-PS werden im Temperaturbereich zwischen 393 K und 563 K aus R6ntgenweitwinkel-Messungen berechnet. Die erforderlichen Korrekturen der experimentellen Intensit~itsverteilung werden sorgf{iltig iiberpriift. Fiir einige Abst~inde kann eine erste Zuordnung ihres inter-und intramolekularen Ursprungs gegeben werden. Die Abstandswerte fiir die n~ichsten Nachbarn aus der RDDF stimmen mit den theoretisch berechneten Werten sehr gut iiberein.

The thermal degradation of some starch based materials was investigated using XRD method. The samples were obtained by thermal extrusion of mixtures of different proportions of starch, glycerol, and water. Such materials are suitable for the manufacturing of low pollutant packaging. Thermal degradation is one of the simplest ways to destroy such materials and this process is followed by structural modification of the local ordering of samples, water evaporation, crystallization, oxidation, or destruction of the chemical bonds. These modifications need to be studied in order to reduce to the minimum production of pollutant residues by burning process. XRD measurements show modification of the local ordering of the starch molecules depending on the temperature and initial composition of the samples. The molecular ordering perturbation is more pronounced in samples with low content of starch.

No abstract

Heavy metals are among the most common types of contaminants in agricultural soils, especially those bordering the cities, due to the uncontrolled use of sewage sludge, compost, mining waste and chemical fertilizers. Excessive accumulation of heavy metals, which do not degrade over time, adversely affects crop yields by decreasing microbial activity and fertility of contaminated soils. Also, excess of heavy metals in the soil poses a serious threat to plant and animal health and, through their entry into the food chain, to human health. For this reason, the decontamination of soils contaminated with heavy metals has become a necessity. This review presents the current state of phytoremediation research as the most cost-effective method of in-situ environmental decontamination of soils contaminated with heavy metals.

No abstract