14 research outputs found
Characterizing the pulsations of the ZZ Ceti star KUV 02464+3239
We present the results on period search and modeling of the cool DAV star KUV
02464+3239. Our observations resolved the multiperiodic pulsational behaviour
of the star. In agreement with its position near the red edge of the DAV
instability strip, it shows large amplitude, long period pulsation modes, and
has a strongly non-sinusoidal light curve. We determined 6 frequencies as
normal modes and revealed remarkable short-term amplitude variations. A
rigorous test was performed for the possible source of amplitude variation:
beating of modes, effect of noise, unresolved frequencies or rotational
triplets. Among the best-fit models resulting from a grid search, we selected 3
that gave l=1 solutions for the largest amplitude modes. These models had
masses of 0.645, 0.650 and 0.680 M_Sun. The 3 `favoured' models have M_H
between 2.5x10^-5 - 6.3x10^-6 M_* and give 14.2 - 14.8 mas seismological
parallax. The 0.645 M_Sun (11400 K) model also matches the spectroscopic log g
and T_eff within 1 sigma. We investigated the possibility of mode trapping and
concluded that while it can explain high amplitude modes, it is not required.Comment: 11 pages, 8 figures, accepted for publication in MNRA
Profluorescent nitroxides as sensitive probes of oxidative change and free radical reactions
This paper presents a review on the use of tethered nitroxide–fluorophore molecules as probes of oxidative change and free radical generation and reaction. The proximity of the nitroxide free radical to the fluorophore suppresses the normal fluorescence emission process. Nitroxide free radical scavenging, metabolism or redox chemistry return the system to its natural fluorescent state and so these tethered nitroxide–fluorophore molecules are described as being profluorescent. A survey of profluorescent nitroxides found in the literature is provided as well as background on the mechanism of action and applications of these compounds as fluorometric probes within the fields of biological, materials and environmental sciences