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UV Lamp (uv + lamp)
Selected AbstractsPhotocatalytic degradation of organic dyes in the presence of titanium dioxide under UV and solar light: Effect of operational parametersENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 3 2005Feryal Akbal The photocatalytic degradation of methylene blue and methyl orange have been studied in the presence of titanium dioxide powder illuminated with a 300-W UV lamp. The effect of hydrogen peroxide on the degradation process was also determined. It was found that the color removal efficiency was affected by the concentration of dye, amount of TiO2 added, and the pH of the solution. The degradation of dyes obeys first-order kinetics, with the apparent first-order rate constant increasing with decreasing dye concentration. The rate constants were evaluated as a function of the concentration of dye, amount of TiO2, and pH. © 2005 American Institute of Chemical Engineers Environ Prog, 2005 [source] Intercalating Dye Harnessed Cationic Conjugated Polymer for Real-Time Naked-Eye Recognition of Double-Stranded DNA in SerumADVANCED FUNCTIONAL MATERIALS, Issue 9 2009Kan-Yi Pu Abstract Thiazole orange (TO), an intercalating dye, is integrated into cationic poly(fluorene- alt -phenylene) (PFP) to develop a macromolecular multicolor probe (PFPTO) for double-stranded DNA (dsDNA) detection. This polymer design not only takes advantage of the high affinity between TO and dsDNA to realize dsDNA recognition in biological media, but also brings into play the light-harvesting feature of conjugated polymers to amplify the signal output of TO in situ. PFPTO differentiates dsDNA from single-stranded DNA (ssDNA) more effectively upon excitation of the conjugated backbone relative to that upon direct excitation of TO as a result of efficient fluorescence resonance energy transfer from the polymer backbone to the intercalated TO. In the presence of dsDNA, energy transfer within PFPTO is more efficient as compared to that for free TO/PFP system, which leads to better dsDNA discriminability for PFPTO in contrast to that for TO/PFP. The distinguishable fluorescent color for PFPTO solutions in the presence of dsDNA allows naked-eye detection of dsDNA with the assistance of a hand-held UV lamp. The significant advantage of this macromolecular fluorescent probe is that naked-eye detection of label-free dsDNA can be performed in biological media in real-time. [source] Synthesis and luminescent properties of a novel bluish-white afterglow phosphor, b -Zn3(PO4)2:Hf4+LUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 1 2008Zifei Peng Abstract A new bluish-white long-lasting phosphorescent material, Hf4+ -doped b-Zn3(PO4)2, was prepared by the conventional high-temperature solid-state method. The photoluminescence (PL) spectrum reveals that it exhibits a strong blue emission band centred at 470 nm, with asymmetry on the long wavelength side; this material emits bluish-white light and shows strong afterglow phosphorescence after it is excited with a 254 nm UV lamp. The phosphorescence lasts nearly 40 min in the light perception of the dark-adapted human eye (0.32 mcd/m2). The possible phosphorescence mechanism is also analysed. Copyright © 2008 John Wiley & Sons, Ltd. [source] UV photosynthesis of nickel carbonylAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 5 2004Xuming Guo Abstract In the presence of low-molecular-weight organic acids, such as formic, acetic, and propionic, inorganic nickel salts in aqueous solutions are converted to the volatile tetracarbonyl by UV irradiation. Experiments were performed using a flow-through photoreactor, consisting of a 6 m length polytetrafluoroethylene tubing wrapped around a low-pressure mercury vapor UV lamp (254 nm, 15 W). The efficiency of transformation was estimated to be 95%. As no carbon monoxide or external reductant is required, photochemical synthesis may prove to be useful in material chemistry and applicable to the extractive metallurgy of nickel, as well as its refining and recycling. Copyright © 2004 Crown in the right of Canada. Published by John Wiley & Sons, Ltd. [source] Photothermocatalytic Synergetic Effect Leads to High Efficient Detoxification of Benzene on TiO2 and Pt/TiO2 NanocompositeCHEMCATCHEM, Issue 9 2010Prof. Yuanzhi Li Photothermocatalyticexpialadocious: The highly efficient photothermocatalytic detoxification of benzene is realized by coating nano TiO2 on the surfaces of a UV lamp without using an additional heater. Its high photothermocatalytic efficiency can be significantly enhanced by supporting well-dispersed Pt nanoparticles on TiO2. The excellent photothermocatalytic performance of TiO2 and Pt/TiO2 is due to the existence of new photothermocatalytic synergetic effects. [source] Responses of plants in polar regions to UVB exposure: a meta-analysisGLOBAL CHANGE BIOLOGY, Issue 11 2009KEVIN K. NEWSHAM Abstract We report a meta-analysis of data from 34 field studies into the effects of ultraviolet B (UVB) radiation on Arctic and Antarctic bryophytes and angiosperms. The studies measured plant responses to decreases in UVB radiation under screens, natural fluctuations in UVB irradiance or increases in UVB radiation applied from fluorescent UV lamps. Exposure to UVB radiation was found to increase the concentrations of UVB absorbing compounds in leaves or thalli by 7% and 25% (expressed on a mass or area basis, respectively). UVB exposure also reduced aboveground biomass and plant height by 15% and 10%, respectively, and increased DNA damage by 90%. No effects of UVB exposure were found on carotenoid or chlorophyll concentrations, net photosynthesis, Fv/Fm or ,PSII, belowground or total biomass, leaf mass, leaf area or specific leaf area (SLA). The methodology adopted influenced the concentration of UVB absorbing compounds, with screens and natural fluctuations promoting significant changes in the concentrations of these pigments, but lamps failing to elicit a response. Greater reductions in leaf area and SLA, and greater increases in concentrations of carotenoids, were found in experiments based in Antarctica than in those in the Arctic. Bryophytes typically responded in the same way as angiosperms to UVB exposure. Regression analyses indicated that the percentage difference in UVB dose between treatment and control plots was positively associated with concentrations of UVB absorbing compounds and carotenoids, and negatively so with aboveground biomass and leaf area. We conclude that, despite being dominated by bryophytes, the vegetation of polar regions responds to UVB exposure in a similar way to higher plant-dominated vegetation at lower latitudes. In broad terms, the exposure of plants in these regions to UVB radiation elicits the synthesis of UVB absorbing compounds, reduces aboveground biomass and height, and increases DNA damage. [source] The Application of Ultraviolet Irradiation to Exogenous Sources of DNA in Plasticware and Water for the Amplification of Low Copy Number DNAJOURNAL OF FORENSIC SCIENCES, Issue 4 2006Jeannie Tamariz B.S. ABSTRACT: Using high sensitivity forensic STR polymerase chain reaction (PCR) typing procedures, we have found low concentrations of DNA contamination in plasticware and water assumed to be sterile, which is not detected by standard DNA procedures. One technique commonly used to eliminate the presence of DNA is ultraviolet (UV) irradiation; we optimized such a protocol used in the treatment of water, tubes, plates, and tips for low copy number DNA (LCN) amplification. UV light from a Stratalinker® 2400 was administered to 0.2, 1.5 mL tubes, and PCR plates contaminated with up to 500 pg of DNA. They were subsequently quantified with an ALU-based real-time PCR method using the Rotorgene 3000. Overall, there was a decrease in concentration of DNA recovered as the duration of treatment increased. Nonetheless, following 45 min of irradiating a PCR plate with 500 pg of DNA, nearly 6 pg were still detected. However, when the plate was raised within an inch of the UV source, less than 0.2 pg of DNA was detected. Additionally, lining the area around the samples with aluminum foil further reduced the amount of time necessary for irradiation, as only 30 min eliminated the presence DNA in the raised PCR plate. Similar experiments were conducted using tubes filled with a solution of DNA and water in equivalent concentrations for 50, 15, and 1.5 mL tubes with comparative results. It is plausible that the aluminum foil increased the amount of reflection in the area thereby enhancing penetration of UV rays through the walls of the plasticware. This protocol was tested for the possibility of inhibitors produced from irradiation of plastic tubes. As our protocols require less irradiation time than previous studies, PCR sensitivity was not affected. Moreover, the lifespan of the UV lamps was extended. Our findings demonstrate that this method is useful as an additional precautionary measure to prevent amplification of extraneous DNA from plasticware and water without compromising the sensitivity of LCN DNA amplifications. [source] Continuous surface modification process with ultraviolet/ozone for improving interfacial adhesion of poly(ethylene terephthalate)/epoxy compositesPOLYMER COMPOSITES, Issue 5 2006Paisan Khanchaitit This study proposed a continuous UV/ozone surface modification process for the production of polymeric fiber-reinforced polymer composite. A gas phase photoreactor using the conventional low-pressure mercury UV lamps and the economically made ozone generators were designed and constructed. Poly(ethylene terephthalate) (PET) fibers and epoxy resin were chosen as a reinforcement and a matrix, respectively. The synergistic effects of UV and various gas species (nitrogen, air, oxygen, air/ozone, and oxygen/ozone) exposure as well as the effects of exposure time, i.e., 2, 5, and 10 min, on the morphology and chemistry of PET-fiber surfaces were investigated by using a scanning electron microscope coupled with energy dispersive x-ray analysis (SEM/EDX). The tensile testing and analysis of fractography of the resulted composites were performed to evaluate the effectiveness of the process. The SEM/EDX results showed that the effects of the treatment were dependent on both the concentration of reactive species present in the gases and the exposure time. The PET fibers treated under UV/O2 + O3 exposure for 5 min yielded the resulting composite with the highest tensile strength value. Under this condition, the tensile strength of the composite can be increased up to 63% in comparison with that of the untreated PET fiber/epoxy composite. The results are of interest for application as an in-line surface modification for composite productions. POLYM. COMPOS., 27:484,490, 2006. © 2006 Society of Plastics Engineers [source] Oxidation of PCE with a UV LED Photocatalytic ReactorCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 1 2005D. H. Chen Abstract This paper is the first to investigate photocatalysis using a cutting-edge and energy-efficient solid-state light source: Ultraviolet (UV) Light Emitting Diodes (LED's). UV LED's do not involve mercury vapor, can be driven with direct current (DC), and have a long lifetime of 100,000 hours. UV LED's with a peak wavelength of 375,nm were tested for perchloroethylene (PCE) photocatalytic oxidation over Degussa P,25 TiO2. At a UV light output of only 49,,W/cm2, the designed reactor delivers a PCE conversion of up to 43,%. If the UV LED price continues to drop, it is very likely that UV LED's will replace UV lamps as the favored light source in photocatalysis applications. 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