Ultraviolet light

About: Ultraviolet light is a research topic. Over the lifetime, 49494 publications have been published within this topic receiving 843151 citations.

Generalized pustular psoriasis. A review of 63 cases.

Abstract: • Background.— Sixty-three patients with generalized pustular psoriasis were hospitalized during a 29-year period. They were classified into four subgroups on the basis of onset and morphologic pattern of disease: acute (von Zumbusch), subacute annular, chronic (acral), and mixed. This division provides a better understanding of the variability of the disease and helps in choosing treatment. Observations.— The average age at onset was 50 years; male and female patients were affected about equally. In 11 patients, flares were precipitated by localized infections. Approximately one fourth of the patients had complications; most were superinfections. The average stay in the hospital was 30 days; factors correlating with a long hospitalization were hypocalcemia, female sex, and a previous history of psoriasis vulgaris or pustular psoriasis. Conclusions.— Whereas topical therapy was helpful, systemic medications were often needed. Coal tar, ultraviolet light, and psoralen—ultraviolet A may be effective; however, they must be used with caution, because they may exacerbate the disease. (Arch Dermatol.1991;127:1339-1345)

Wafer-Level Artificial Photosynthesis for CO2 Reduction into CH4 and CO Using GaN Nanowires

Abstract: We report on the first demonstration of high-conversion-rate photochemical reduction of carbon dioxide (CO2) on gallium nitride (GaN) nanowire arrays into methane (CH4) and carbon monoxide (CO). It was observed that the reduction of CO2 to CO dominates on as-grown GaN nanowires under ultraviolet light irradiation. However, the production of CH4 is significantly increased by using the Rh/Cr2O3 core/shell cocatalyst, with an average rate of ∼3.5 μmol gcat–1 h–1 in 24 h. In this process, the rate of CO2 to CO conversion is suppressed by nearly an order of magnitude. The rate of photoreduction of CO2 to CH4 can be further enhanced and can reach ∼14.8 μmol gcat–1 h–1 by promoting Pt nanoparticles on the lateral m-plane surfaces of GaN nanowires, which is nearly an order of magnitude higher than that measured on as-grown GaN nanowire arrays. This work establishes the potential use of metal-nitride nanowire arrays as a highly efficient photocatalyst for the direct photoreduction of CO2 into chemical fuels. It al...

Ultraviolet light sensitivity and delayed DNA-chain maturation in Bloom's syndrome fibroblasts

Abstract: BLOOM'S syndrome (BS) is a rare, autosomal recessive condition of pre-natal and post-natal growth retardation, sun-induced telangiectatic erythema, impaired immunological function and predisposition to cancer1,2. BS cells show a high incidence of chromosome breakage and rearrangement often with abnormal nuclear morphology. Chromosome exchanges appear mainly to involve homologous chromosomes, while sister chromatid exchanges are abnormally frequent3. These features suggest a defect of DNA replication or repair. In particular, the high incidence of sister chromatid exchanges may be explained if free ends in the DNA, resulting from abnormalities of DNA synthesis and/or repair, act as initiation points for exchange4. We report here that BS fibroblasts are abnormally sensitive to ultraviolet irradiation in vitro and show a rate of DNA synthesis and DNA chain maturation lower than controls. They do not, however, have defective bypass of ultraviolet light-induced lesions during DNA replication as xeroderma pigmentosum (XP) variants5.