Assessment of the In Vivo Release and Biocompatibility of Novel Vesicles Containing Zinc in Rats

This paper is focused on the in vivo release and biocompatibility evaluation in rats of some novel systems entrapping zinc chloride in lipid vesicles. The particles were prepared by zinc chloride immobilization inside lipid vesicles made using phosphatidylcholine, stabilized with 0.5% chitosan solution, and dialyzed for 10 h to achieve a neutral pH. The submicrometric systems were physico-chemically characterized. White Wistar rats, assigned into four groups of six animals each, were treated orally with a single dose, as follows: Group I (control): deionized water 0.3 mL/100 g body weight; Group II (Zn): 2 mg/kg body weight (kbw) zinc chloride; Group III (LV-Zn): 2 mg/kbw zinc chloride in vesicles; Group IV (LVC-Zn): 2 mg/kbw zinc chloride in vesicles stabilized with chitosan. Haematological, biochemical, and immune parameters were assessed after 24 h and 7 days, and then liver fragments were collected for histopathological examination. The use of zinc submicrometric particles—especially those stabilized with chitosan—showed a delayed zinc release in rats. No substantial changes to blood parameters, plasma biochemical tests, serum complement activity, or peripheral neutrophils phagocytic capacity were noted; moreover, the tested substances did not induce liver architectural disturbances. The obtained systems provided a delayed release of zinc, and showed good biocompatibility in rats.     

Periodical cicadas: A minimal automaton model

The Magicicada spp. life cycles with its prime periods and highly synchronized emergence have defied reasonable scientific explanation since its discovery. During the last decade several models and explanations for this phenomenon appeared in the literature along with a great deal of discussion. Despite this considerable effort, there is no final conclusion about this long standing biological problem. Here, we construct a minimal automaton model without predation/parasitism which reproduces some of these aspects. Our results point towards competition between different strains with limited dispersal threshold as the main factor leading to the emergence of prime numbered life cycles.     

Cellular instabilities of expanding hydrogen/propane spherical flames at elevated pressures: theory and experiment

An experimental and theoretical investigation of the onset of cellular instabilities on spherically expanding flames in mixtures of hydrogen and propane in air at elevated pressures was conducted. Critical conditions for the onset of instability were measured and mapped out over a range of pressures and mixture compositions. An asymptotic theory of hydrodynamic and diffusional-thermal cell development on flames in mixtures comprised of two scarce fuels burning in air was also formulated. Predicted values of Peclet number, defined as the flame radius at the onset of instability normalized by the flame thickness, were shown to compare favorably with the experimentally measured values.