The effect of talc as an artificial nucleating agent in different concentrations on the crystallization of polypropylene (PP) has been studied. It is considered that the induction time should be taken into account in the Avrami evaluation of isothermal crystallization. From a study of nucleated PP samples prepared in different ways, it has been proved that the nucleating effect of talc slightly decreases with increasing time spent by the sample in the state of the polymer melt. It has been shown that crystallization of non-nucleated polypropylene strongly depends on the material of the sample pan. It has been established that dilatometry cannot be used to study the isothermal crystallization of nucleated polypropylene, since microcracks appear in the sample, partly compensating the volume decrease due to the crystallization process.
Mycotoxin-producing fungi may contaminate agricultural products in the field (preharvest spoilage), during storage (postharvest spoilage), or during processing. Mycotoxin contamination of foods and feeds poses serious health hazard to animals and humans. For lowering mycotoxin contamination of feeds and foods, several strategies have been investigated that can be divided into biological, chemical and physical methods. This paper gives an overview of strategies which are promising with regard to lowering the mycotoxin burden of animals and humans.
Blends were prepared from isotactic polypropylene (iPP) along with its b-nucleated form and poly(vinylidene-fluoride) (PVDF).
Melting, and crystallization characteristics as well as structure of the blends were studied by polarized light microscopy
(PLM) and differential scanning calorimetry. According to PLM studies, the phase structure of these blends is heterogeneous
in the molten state. The temperature range of crystallization of PVDF during cooling is higher than that of iPP. PVDF has
a strong α-nucleating effect on iPP. The crystallization of iPP starts on the surface of dispersed PVDF droplets and an α-transcrystalline
layer forms on the surface of the crystalline PVDF phase. The iPP matrix crystallizes predominantly in a-form in spite of
the presence of a highly active b-nucleating agent.
Our knowledge on the presence of mycotoxin producing fungi and mycotoxins in food commodities in the last decade in Hungary has been summarized in this review. Among the mycotoxin producing fungi, detailed data are available for Fusarium species in cereals, and mycotoxigenic Aspergillus species in different food commodities including coffee, raisins and spices. Ochratoxin concentrations above the tolerable limit have mostly been detected in imported products such as peanuts and coffee. Ochratoxin levels close to the tolerable limit have been observed in Hungarian red peppers. Besides, ochratoxin A has also been detected in Hungarian wine, beer and raisins. Aflatoxins are usually detected in considerable quantities only in imported agricultural products in Hungary, while patulin concentrations were usually below the allowable limit in Hungarian apple juice concentrates. In the future, continuous sampling and analysis of foods and feeds are required to ensure consumer safety in Hungary.