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Polycyclic aromatic hydrocarbons (PAHs) are a group of significant contaminants in the occupational and living environment. In addition to the inhalation route of exposure in the occupational environment, there is also significant the dermal route of exposure. Existing experimental data on the intensity and rate of penetration of these substances into systemic circulation are still limited. The presented paper is focused on methodological and interpretative issues of trans-epidermal absorption of PAHs in vitro. In this study, we assessed the intensity (Flux) and rate (Lag time) of penetration of naphthalene, phenanthrene, pyrene and benzo[ a]pyrene through the epidermal membrane derived from a pig ear. The experiment was performed using static vertical Franz diffusion cells (n = 32) and isopropyl myristate was used as a solvent. Flux (nmol/cm2/hour) reached 95.7 ± 45.5 in the case of naphthalene, 19.5 ± 8.7 of phenanthrene, 4.38 ± 1.98 of pyrene and 0.21 ± 0.08 of benzo[a]pyrene. Lag time (hour) was 0.26 ± 0.17 in the case of naphthalene, 2.12 ± 0.41 of phenanthrene, 3.25 ± 0.50 of pyrene and 11.2 ± 4.08 of benzo[a]pyrene. The Flux value decreased with the molecular weight of PAHs, while the Lag time increased with the molecular weight of PAHs. The amount of PAHs that penetrated through the epidermal membrane in a given time period ranged between 0.24% (benzo[a]pyrene) and 0.84% (phenanthrene) of the applied dose. The penetration of PAHs through the epidermal membrane showed a lower degree of data variability compared to full thickness skin experiments. The results suggest that the use of the epidermal membrane could define more accurately both the estimation of the internal dose of PAHs after dermal exposure and the estimation of the associated health risk within a conservative exposure scenario. However, experiments with using the epidermal membrane are time consuming and experimentally demanding, with no option of an objective control of the integrity of the epidermal membrane, which can lead to costly testing, loss of samples and, finally, an increase in the differences in data values obtained in different laboratories. [ABSTRACT FROM AUTHOR]

The present paper summarizes theoretical background, practical notes and design of two experiments on plant phototropism to be conducted at high schools. Theoretical introduction describes different types of plant tropisms, e.g. gravitropism, heliotropism and phototropism, and different types of nastic movements not directionally oriented. Phototropism is a type of plant growth reaction oriented towards or against the direction of the source of irradiation, called positive phototropism or negative phototropism, respectively. The Experiment 1 is aimed at the effect of the different irradiation wavelength on the growth of plant shoot of Lepidium sativum. It is demonstrated there that blue light and, thus, blue photoreceptors are determining stem positive phototropic reaction. The use of LED light source to induce irradiation of a narrow wavelength is recommended. The Experiment 2 then demonstrates negative phototropism of plant roots. An important part constitutes the experience gained during the design, accomplishment and verification process for the presented experimentation. Both experiments were designed in cost-effective way for application of scientific approaches and protocols at high schools. [ABSTRACT FROM AUTHOR]

Emerging adulthood is considered to be a transitional developmental period between adolescence and adulthood. The paper focuses on key features of this period which are exploration of identity, experimentation, instability, self-focus and focus on others. The scope of their subjective experience and relations of these features to coping strategies with stressful situations were studied in an empirical research. The research sample involved 486 university students of Masaryk University in Brno (237 males, 249 females) with mean age 21.8. The features of emerging adulthood were measured by The IDEA Scale; coping strategies were measured by The Brief COPE. The results especially emphasized the importance of experimentation, self-focus and exploration of identity. The significant connections between features of emerging adulthood and coping strategies were gained. Experimentation and self-focus strongly correlated with orientation to problem solving, identity exploration particularly correlated with support seeking. Substantial differences between males and females were not observed. [ABSTRACT FROM AUTHOR]