Absolute dimensions and apsidal motion of the eccentric binary V731 Cephei

A detailed analysis of new and existing photometric, spectroscopic and spatial distribution data of the eccentric binary V731 Cep was performed. Spectroscopic orbital elements of the system were obtained by means of cross-correlation technique. According to the solution of radial velocities with UBVRc and I-c light curves, V731 Cep consists of two main-sequence stars with masses M-1 = 2.577 (0.098) M-circle dot, M-2 = 2.017 (0.084) M-circle dot, radii R-1 = 1.823 (0.030) R-circle dot, R-2 = 1.717 (0.025) R-circle dot and temperatures T-eff1 = 10700 (200) K, T-eff2 = 9265 (220) K separated from each other by a = 23.27 (0.29) R-circle dot in an orbit with inclination of 88 degrees.70 (0.03). Analysis of the O-C residuals yielded a rather long apsidal motion period of U = 10000 (2500) yr compared to the observational history of the system. The relativistic contribution to the observed rates of apsidal motion for V731 Cep is significant (76 per cent). The combination of the absolute dimensions and the apsidal motion properties of the system yielded consistent observed internal structure parameter (log (k) over bar (2,obs) = -2.36) compared to the theory ( log (k) over bar (2,theo) = -2.32). Evolutionary investigation of the binary by two methods (Bayesian and evolutionary tracks) shows that the system is t = 133(26) Myr old and has a metallicity of [M/H] = -0.04(0.02) dex. The similarities in the spatial distribution and evolutionary properties of V731 Cep with the nearby (rho similar to 3 degrees.9) open cluster NGC 7762 suggest that V731 Cep could have been evaporated from NGC 7762

The growth of Staphylococcus aureus and Escherichia coli in low-direct current electric fields

Electrical potentials up to 800 mV can be observed between different metallic dental restorations. These potentials produce fields in the mouth that may interfere with microbial communities. The present study focuses on the impact of different electric field strengths (EFS) on the growth of Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922) in vitro. Cultures of S. aureus and E. coli in fluid and gel medium were exposed to different EFS. Effects were determined by calculation of viable counts and measurement of inhibition zones. In gel medium, anodic inhibition zones for S. aureus were larger than those for E. coli at all field strength levels. In fluid medium, the maximum decrease in the viable count of S. aureus cells was at 10 V center dot m(-1). Field-treated S. aureus cells presented ruptured cell walls and disintegrated cytoplasm. Conclusively, S. aureus is more sensitive to increasing electric field strength than E. coli