Experimental study of interzonal natural convection through an aperture

The work was concerned with measuring natural convection through an aperture between two zones in an environmental chamber. Airflow rates between the two zones were measured using a tracer-gas decay technique, and the temperature at the centre of each zone was measured using thermocouples. Zone 1 was heated to various temperatures in the range 18-38°C using thermostatically controlled heaters. Zone 2 was unheated. A multipoint sampling unit was used to collect a tracer-gas sample from each zone. The concentration of SF6 tracer was measured using an infra-red gas analyzer. The heat and mass flow rates between the two zones were calculated from the tracer-gas concentrations and temperature differences. Results were compared with values predicted by existing algorithms for two-zone enclosures. The mass flow rate through the aperture was found to be a function of the temperature difference between the two zones.

Structure and in vitro cytocompatibility of the gastropod shell of Helix pomatia

Distinguishing features of biological constructions are high stability and adaptation to their environment. Beside biocompatibility, nontoxicity and degradability these characteristics are demanded for new biomaterials in the field of tissue engineering. This study investigated the chemical composition, the organization and the in vitro osteoconductive potential of the terrestrial gastropod shell (Helix pomatia) on CAL72 and human osteoblast-like cells. Chemical composition of the biomaterial was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) was performed to analyze the architecture of the snail shell and the morphology of the seeded cells. A double staining procedure (FDA/PI) and a proliferation test (EZ4U) assessed the viability of the cells. Microscopical images showed the multilayered architecture of the aragonite shell with hexagonal crystals on the inner side. The cells spread well on the biomaterial and the highest proliferation rate could be measured with CAL72 cells on the inner shell surface. The osteoconductive effects of this natural biomaterial could encourage further experiments in the field of tissue engineering