INTRODUCTION It is now recognized that to adequately protect skin from sun damage, sunscreens require a photostable combination of ultraviolet (UV) filters with a suitable level of UVA protection. The total amount of UV filters should be as low as possible to avoid adverse skin reactions, potential environmental impact, and to ensure acceptable texture for better application and usage. METHOD...

A semi-analytical method is used to study the effects of the multi vibration absorbers on the nonlinear functionally graded (FG) Euler-Bernoulli beam subjected to periodic load. The material properties of the beam are assumed to be continuously graded in the thickness direction. The governing equations of functionally graded beam are obtained based on the Hamilton's principle and these equation...

BACKGROUND Several chemical UV filters/absorbers ('UV filters' hereafter) have endocrine-disrupting properties in vitro and in vivo. Exposure to these chemicals, especially during prenatal development, is of concern. OBJECTIVES To examine maternal exposure to UV filters, associations with maternal thyroid hormone, with growth factor concentrations as well as to birth outcomes. METHODS Prosp...

A statistical study is presented of (a) the frequency of narrow C iv λ1549 absorption lines in 1.5 < ∼ z < ∼ 3.6 radio-quiet and radio-loud quasars, and of (b) the UV and radio properties of the absorbed quasars. The quasar sample is unbiased with respect to absorption properties and the radio-quiet and radio-loud subsamples are well matched in redshift and luminosity. A similarly high incidenc...

Abstract: The stability of aqueous and non-aqueous papaverine hydrochloride solutions exposed to the UV radiation is poor. In order to enhance its photo-stability suitable light absorbers may be used. There werefour photo-protectors considered in this work: 4-aminobenzoic acid, sodium benzoate, methyl 4-hydroxybenzoate and propyl 4-hydroxybenzoate, whose UV absorption spectra characteristics ma...

The synthesis of vitamin D in skin is a two-stage process that begins with the production of previtamin D after irradiation of 7-dehydrocholesterol by ultraviolet (UV) radiation. A number of personal and environmental factors control the probability of a suitable UV photon reaching a molecule of 7-dehydrocholesterol in the skin. These are astronomical factors that govern the solar zenith angle ...

We present computations of the metals photoionization structures of pressure supported gas clouds in gravitationally dominant dark-matter mini-halos in the extended Galactic halo or Local Group environment. We consider low-metallicity (0.1−0.3 solar) clouds that are photoionized by the present-day metagalactic radiation field, and which are also pressure-confined by a hot external medium. We st...

We have examined the physical conditions in intrinsic UV-absorbing gas in the Seyfert galaxy NGC 4151, using echelle spectra obtained with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) on 1999 July 19. We confirm the presence of the kinematic components detected in earlier Goddard High Resolution Spectrograph (GHRS) observations, all of which appear to be o...

This paper provides a general reference for deriving the ionizations and metal abundances for absorption-line clouds in photoionization equilibrium with a QSO spectrum. The results include a quantitative assessment of the theoretical uncertainties and Ðrm lower limits on the metallicities when no ionization constraints are available. The calculations applied to the best available column densiti...

This paper provides a general reference for deriving the ionizations and metal abundances for absorption-line clouds in photoionization equilibrium with a QSO spectrum. The results include a quantitative assessment of the theoretical uncertainties and firm lower limits on the metallicities when no ionization constraints are available. The calculations applied to the best available column densit...