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Longer Exposure Times (longer + exposure_time)
Selected AbstractsComparison of ECR plasma pretreatment techniques for ZnO atomic layer epitaxy on the sapphire substratePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2004Kyoungchul Shin Abstract ZnO films were grown on sapphire substrates treated with ECR plasma by the atomic layer epitaxy (ALE) technique. ZnO nucleation enhancing effects of oxygen, hydrogen, and argon plasma treatments were compared. The incubation period for ZnO nucleation was measured by using scanning electron microscopy (SEM) and Auger electron emission spectrometric (AES) analysis. The incubation period for ZnO nucleation on the Al2O3 substrate not treated with plasma was more than 40 ALE cycles. The incubation period was shortened down to less than 35 cycles by argon or hydrogen ECR plasma pretreatment and to less than 30 cycles by oxygen ECR plasma pretreatment. It was found that a microwave power of 300W and a plasma exposure times of 10 min were appropriate for oxygen ECR plasma treatment of sapphire substrate surfaces to enhance ZnO nucleation. Higher power and longer exposure time would not be effective or would rather aggravate than enhance ZnO nucleation. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of Steam Velocity on the Hydrothermal Oxidation/Volatilization of Silicon NitrideJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2006B. Sudhir The hydrothermal oxidation behavior of silicon nitride was studied as a function of vapor velocity in the range of 1,35 cm/s, at atmospheric pressure and ,100% H2O, using a custom-designed hydrothermal apparatus. At lower velocities, silicon nitride showed a marginal weight gain during early exposure times followed by a linear weight loss at longer exposure times. At higher velocities only linear weight loss was seen. The linear weight loss rates were determined from the weight change studies and they showed a square root dependence on velocity at higher flow rates. At the low flow rates a threshold velocity of ,1 cm/s was observed for volatilization to initiate. The weight loss rates obtained in the apparatus at the higher steam velocities were comparable to those obtained in high pressure burner rigs, proving its viability as a good laboratory scale screening method for potential gas turbine materials. [source] Topical aminolaevulinic acid- and aminolaevulinic acid methyl ester-based photodynamic therapy with red and violet light: influence of wavelength on pain and erythemaBRITISH JOURNAL OF DERMATOLOGY, Issue 5 2009P. Mikolajewska Summary Background, Photodynamic therapy (PDT) is based on the combination of an exogenously administered precursor of photosensitizer [protoporphyrin IX (PpIX)] synthesis and exposure to light. Choosing the optimal wavelength is important. Red light penetrates deeper into tissue, while violet light is more efficient in activating PpIX but does not penetrate so deeply. Objectives, We studied PpIX formation and the PDT effect after application to human skin of creams containing aminolaevulinic acid (ALA) and aminolaevulinic acid methyl ester (MAL). The aim of the study was to investigate whether the wavelength of the light used has an influence on pain sensations during topical PDT with the different prodrugs. Methods, ALA cream (10%) and MAL cream (10%) were topically applied on the skin of 10 healthy volunteers. After 24 h the application site was exposed to 8 mW cm,2 violet laser or to 100 mW cm,2 red laser light. The erythema index was monitored up to 24 h after light exposure. For the first time the pain during topical ALA- and MAL-PDT was assessed by measuring the time taken for pain to occur. Also, for the first time, the intensities of the light sources were calibrated so as to have the same relative quantum efficiency. Results, The pain sensation during ALA-PDT with red light came 22 s sooner than during ALA-PDT with violet light, which is statistically significant (P < 0·05). Moreover, ALA-PDT with red light gave stronger and more persistent erythema than ALA-PDT with violet light. ALA induced about three times more PpIX than MAL. No statistically significant differences were found for erythema, or for the time for pain to occur, in the case of MAL-PDT with red vs. violet light. Conclusions, Topical ALA-PDT with violet light allows longer exposure times before pain is induced and gives less erythema as compared with topical ALA-PDT with red light. [source] 3243: In vivo quantitative measurement of oxidation repair of glutaredoxin-1ACTA OPHTHALMOLOGICA, Issue 2010PG SÖDERBERG Purpose Quantitative determination of the impact of glutaredoxin-1 on sensitivity to oxidative stress induced by in vivo exposure to ultraviolet radiation in the 300 nm wavelength region. Methods Altogether, 20 glutredoxin-1 knockout mice (Grx1 -/-) and 20 wild type C57BL/6, bred on the same background were in vivo exposed unilaterally to ultraviolet radiation in the 300 nm wavelength region (UVR-300 nm). For both the Grx1-/- and the Grx1+/+ groups, respectively, the animals were subdivided into 5 dose groups of four receiving 0.0, 2.1, 2.9, 3.6 or 4.1 kJ m^-2, depending on group belonging. At 48 hrs after exposure the animals were sacrificed, the lenses were extracted and measured for intensity of forward light scattering. The threshold dose for damage was estimated as the Maximum Tolerable Dose-2.3:16. The protection factor (PF), defined as the ratio between the threshold with protection and the threshold without protection was calculated. Results The MTD-2.3:16 was for the Grx1+/+ estimated to 3.81 kJ/m2 (95% CI, 2.82 , 6.37) and for the Grx1-/- estimated to 2.99 kJ/m2 (95% CI, 2.33 , 4.00). The PF factor for the Grx1 gene thus was 1.3. Conclusion The Grx-1 gene provides a higher tolerance to in vivo oxidative stress induced by in vivo exposure to ultraviolet radiation, allowing a 1.3 longer exposure times at the same intensity before cataract develops. [source] | ||||||||||