our aim in this work is the synthesis and study optical and structural properties of gold nanoparticles.gold (iii) chloride trihydratewas taken as metal precursor, ascorbic acid at the presence of an appropriate amount of naoh as reducing agent and polyvinylpyrrolidonek-30 (pvp k-30) as a stabilizing and capping agent. the reaction was performed in high-speed stirring rate at room temperature.s...

We present Chandra observations of the radio-quiet Broad Absorption Line (BAL) QSO PG 1254+047. We find that it is a weak X-ray source, with a total of 44 ± 7 photons measured in 36 ksec across the observed energy range 0.7 − 6.0 keV. Its X-ray weakness is consistent with the known correlation between αox and the strength of the UV absorption lines. The spectral energy distribution suggests tha...

Two series of free-base and manganese N-methyl-pyridylethynyl-5,15-biphenyl porphyrins were synthesized, and their UV-Visible, electrochemical and spectro-electrochemical properties were studied. Cyclic voltammetry experiments showed positive shifts in the reduction potentials and the UV-Visible spectra showed significant red-shifts in the absorption wavelengths of these porphyrins, indicating ...

Southern pine specimens vacuum-treated with nano-zinc oxide (nano-ZnO) dispersions were evaluated for leach resistance and UV protection. Virtually, no leaching occurred in any of the nano-ZnO-treated specimens in a laboratory leach test, even at the highest retention of 13 kg/m(3). However, specimens treated with high concentrations of nano-ZnO showed 58-65% chemical depletion after 12 months ...

We present Chandra observations of the radio-quiet Broad Absorption Line (BAL) QSO PG 1254+047. We find that it is a weak X-ray source, with a total of 44 ± 7 photons measured in 36 ksec across the observed energy range 0.7 − 6.0 keV. Its X-ray weakness is consistent with the known correlation between αox and the strength of the UV absorption lines. The spectral energy distribution suggests tha...

We describe the results of a survey of the UV absorption properties of the Boroson & Green sample of AGN, which extends from the Seyfert (MV ≃ −21) to the luminous quasar (MV ≃ −27) level. The survey is based mostly on HST archival data available for > ∼ 1/2 of the 87 sample objects. Our main result is that soft X-ray weak quasars (SXWQs, 10 AGN with αox ≤ −2) show the strongest UV absorption a...

A generic assumption of ionization models of quasar absorption systems is that radiation from local sources is negligible compared with the cosmological background. We test this assumption and find that it is unlikely to hold for absorbers as rare as H I Lyman limit systems. Assuming that the absorption systems are gas clouds centered on sources of radiation, we derive analytic estimates for th...

UV cured epoxy systems represent complementary technology to the established heat cured epoxy systems for coating, adhesion and encapsulation of electronic devices. The UV cured epoxy systems offer significant benefits in terms of fast cure and thus very short production cycle time; low stress and better colour due to room temperature cure; process wise no mix ratio problem or anhydride handlin...

Experimental and theoretical absorption spectra of [2-[2-[4-(dimethylamino) phenyl]ethenyl]-6-methyl-4H- pyran-4-ylidene]-propanedinitrile (DCM) have been studied. UV-Visible (UV-Vis.) absorption spectrum of DCM has been reported after its synthesis. Two relatively intense peaks appeared at 473 and 362 nm respectively. A theoretical investigation on the electronic structure of DCM is presented ...

High birefringence (Dn 0.4) liquid crystals (LCs) are desirable for cholesteric displays, laser beam steering and optical switches for telecommunications [1]. A major concern for the high birefringence LCs is their ultraviolet (UV) stability. As the conjugation length increases, the LC absorption tail shifts toward k 1⁄4 365 nm, the major UV light used for curing sealant. The material degradati...