Recent X-ray observations of Mrk 766 suggest that broad emission-line region clouds cross our line of sight and produce variable X-ray absorption. Here we investigate what optical/ultraviolet (UV) spectroscopic features would be produced by such ‘intervening broad-line region (BLR) clouds’ (IBC) crossing our line of sight to the accretion disc, the source of the optical/UV continuum. Although t...

We present a unified model of infrared (IR), optical, ultraviolet (UV), and X-ray light curves for the 1983 outburst of GQ Muscae (Nova Muscae 1983) and estimate its white dwarf (WD) mass. Based on an optically thick wind model of nova outbursts, we model the optical and IR light curves with free-free emission, and the UV 1455 Å and supersoft X-ray light curves with blackbody emission. The best...

Highly dispersed colloidal gold (Au) nanoparticles were synthesized at room temperature using glow discharge plasma within only 5 min. The prepared Au colloids were characterized with UV-visible absorption spectra (UV-vis), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) equipped with an energy dispersion X-ray spectrometer (EDX). UV-vis, XPS and EDX results c...

The synthesis of ZnO nanoparticles has attracted immense interest because of their unique properties and potential applications in optoelectronic devices. ZnO as a wide band gap semiconductor with large excitation energy becomes one of the most important functional material with near UV-emission, optical transparency, electric conductivity and piezoelectricity. ZnO nanoparticles were prepared b...

Recent observations strongly suggest that the millisecond pulsar binary PSR J1023+0038 has developed an accretion disk since 2013 June. We present a multi-wavelength analysis of PSR J1023+0038, which reveals that 1) its gamma-rays suddenly brightened within a few days in June/July 2013 and has remained at a high gamma-ray state for several months; 2) both UV and X-ray fluxes have increased by r...

The prompt optical flash recently detected accompanying GRB990123 suggests that, for at least some GRBs, γ-ray emission is accompanied by prompt optical-UV emission with luminosity L(1 − 7.5 eV) ≈ 1 × 10 49 (∆Ω/4π)erg/s, where ∆Ω is the solid angle into which γ-ray and optical-UV emission is beamed. Such an optical-UV flash can destroy dust in the beam by sublimation out to an appreciable dista...

Synthesis of deoxyribonucleic acid (DNA) has been measured as a function of ultraviolet (UV) radiation dose in wild-type and seven UV-sensitive strains of Haemophilus influenzae. At the UV doses used, all strains were able to resume DNA synthesis, even those which are unable to excise pyrimidine dimers from their DNA. These excisionless strains showed longer UV-induced delays in DNA synthesis t...

The ionizing continuum shape of quasars is generally not directly observable, but indirect arguments, based on photoionization models and thin accretion disk models suggest that it should peak in the extreme UV, and drop steeply into the soft X-ray regime. However, recent observations of very soft X-ray emission in low z quasars, and far UV emission of high z quasars, suggest that the ionizing ...

We report on UV/Visible transmission measurements of aluminum coated Lexan filters designed as UV blocking filters for soft x-ray detectors. Transmission of the filters in the 2300 8000 Å wavelength range is significantly higher than expected. It cannot be accounted for applying a simple slab model of the transmission and adopting material properties reported in the literature. We show that thi...