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Showing papers on "Ultraviolet light published in 2003"


Journal ArticleDOI
TL;DR: In this article, field effect transistors (FETs) based on single SnO2 and ZnO nanobelts of thicknesses between 10 and 30 nm have been fabricated.
Abstract: We have fabricated field-effect transistors (FETs) based on single SnO2 and ZnO nanobelts of thicknesses between 10 and 30 nm. Switching ratios as large as 6 orders of magnitude and conductivities as high as 15 (Ω cm)-1 are observed. Annealing SnO2 nanobelt FETs in an oxygen-deficient atmosphere produces a negative shift in gate threshold voltage, indicating doping by the generation of surface oxygen vacancies. This treatment provides an effective way of tuning the electrical performance of the nanobelt devices. The ability of SnO2 FETs to act as gas sensors is also demonstrated. SnO2 FETs with lengths of about 500 nm or less show an anomalous behavior where the conductance cannot be modulated by the gate. ZnO nanobelt FETs are sensitive to ultraviolet light. Both photogeneration of electron−hole pairs and doping by UV induced surface desorption contribute to the conductivity.

1,087 citations



Journal ArticleDOI
TL;DR: Multicolour photochromism of TiO2 films loaded with silver nanoparticles by photocatalytic means is reported, and the apparently uniform Ag–TiO2 film can be almost any colour.
Abstract: Photochromic materials, which change their colours reversibly in response to light, can be applied to smart windows, displays and memories1,2,3. Conventional photochromic materials respond in a monochromatic way, so that multicolour photochromism has required several different materials or filters combined appropriately. If multicolour photochromism could be achieved with a simple material, photochromic devices would be find a greater number of applications, including a rewritable colour copy paper or electronic paper4 and a high-density multi-wavelength optical memory. Here we report multicolour photochromism of TiO2 films loaded with silver nanoparticles by photocatalytic means. Its colour, initially brownish-grey, changes under monochromatic visible light to almost the same colour as that of the light; the apparently uniform Ag–TiO2 film can be almost any colour. Behaviour similar to persistent hole-burning effects5,6 is also observed. The colour reverts to brownish-grey under ultraviolet light, and these processes are repeatable.

592 citations


Journal ArticleDOI
TL;DR: The 3′ UTR of p53 was found to be a target of the RNA-binding protein HuR in a UVC-dependent manner in vitro and in vivo, and a role for HuR is demonstrated in binding to the p53 mRNA and enhancing its translation.
Abstract: Exposure to short-wavelength UV light (UVC) strongly induces p53 expression. In human RKO colorectal carcinoma cells, this increase was not due to elevated p53 mRNA abundance, cytoplasmic export of p53 mRNA, or UVC-triggered stabilization of the p53 protein. Instead, p53 translation was potently enhanced after UVC irradiation. The 3' UTR of p53 was found to be a target of the RNA-binding protein HuR in a UVC-dependent manner in vitro and in vivo. HuR-overexpressing RKO cells displayed elevated p53 levels, whereas cells expressing reduced HuR showed markedly diminished p53 abundance and p53 translation. Our results demonstrate a role for HuR in binding to the p53 mRNA and enhancing its translation.

435 citations


Patent
04 Mar 2003
TL;DR: In this paper, an organosilicate glass film is exposed to an ultraviolet light source wherein the film after exposure has an at least 10% or greater improvement in its mechanical properties compared to the as-deposited film.
Abstract: Low dielectric materials and films comprising same have been identified for improved performance when used as interlevel dielectrics in integrated circuits as well as methods for making same. In one aspect of the present invention, an organosilicate glass film is exposed to an ultraviolet light source wherein the film after exposure has an at least 10% or greater improvement in its mechanical properties (i.e., material hardness and elastic modulus) compared to the as-deposited film.

358 citations


Journal ArticleDOI
TL;DR: In this article, the authors used an AlGaN-based UV-LED as an excitation source at the 350-nm wavelength, measured fluorescence spectra of three-basal-color phosphors, and simulated the optimum phosphor mixture based on the Commission Internationale de l'Eclairage standard light sources D75, D65, D55, D50, C, and A, with HCR indexes (Ra) over 92.
Abstract: The high-color-rendering (HCR) potential of the light sources consisting of 350-nm ultraviolet light-emitting diodes (UV-LED) and three-basal-color phosphors was simulated and experimentally confirmed. By using an AlGaN-based UV-LED as an excitation source at the 350-nm wavelength, we measured fluorescence spectra of three-basal-color phosphors, and simulated the optimum phosphor mixture based on the Commission Internationale de l’Eclairage standard light sources D75, D65, D55, D50, C, and A, with HCR indexes (Ra) over 92. We confirmed the potential of HCR of this light source consisting of 350-nm UV-LED and three-basal-color phosphors, by obtaining Ra=86∼89 of the incandescent type of standard light source A experimentally. Such high Ra are due to the highly monochromatic UV-LED emission and the wide spectral separation between the UV excitation (350 nm) and visible fluorescences. This combination also provides a diffusive, nonglare light source with highly steady color independent of the emission orient...

348 citations


Journal ArticleDOI
TL;DR: Lifetime sun exposure appeared to be associated with a lower risk of malignant melanoma, despite the fact that lifetime sun exposure did not diminish the number of melanocytic nevi or atypical nevi, and painful sunburns nor lifetimeSun exposure were associated with an increased risk of seborrheic warts.

314 citations


Journal ArticleDOI
TL;DR: Histological examination has demonstrated an advanced granulation tissue formation, capillary formation and epithelialization in wounds treated with FGF-2-incorporated chitosan hydrogels in db/db mice.

304 citations


Journal ArticleDOI
TL;DR: The efficacy of a number of disinfection treatments was tested on in vitro cultures of the fungus Batrachochytrium dendrobatidis, the causative agent of chytridiomycosis in amphibians, finding the most effective products for field use were Path-X and the quaternary ammonium compound 128.
Abstract: The efficacy of a number of disinfection treatments was tested on in vitro cultures of the fungus Batrachochytrium dendrobatidis, the causative agent of chytridiomycosis in amphibians The aim was to evaluate the fungicidal effects of chemical disinfectants, sterilising ultraviolet (UV) light, heat and desiccation, using methods that were feasible for either disinfection in the field, in amphibian husbandry or in the laboratory The chemical disinfectants tested were: sodium chloride, household bleach (active ingredient: sodium hypochlorite), potassium permanganate, formaldehyde solution, Path-XTM agricultural disinfectant (active ingredient: didecyl dimethyl ammonium chloride, DDAC), quaternary ammonium compound 128 (DDAC), Dithane, Virkon, ethanol and benzalkonium chloride In 2 series of experiments using separate isolates of B dendrobatidis, the fungicidal effect was evaluated for various time periods and at a range of chemical concentrations The end point measured was death of 100% of zoospores and zoosporangia Nearly all chemical disinfectants resulted in 100% mortality for at least one of the concentrations tested However, concentration and time of exposure was critical for most chemicals Exposure to 70% ethanol, 1 mg Virkon ml–1 or 1 mg benzalkonium chloride ml–1 resulted in death of all zoosporangia after 20 s The most effective products for field use were Path-XTM and the quaternary ammonium compound 128, which can be used at dilutions containing low levels (eg 0012 or 0008%, respectively) of the active compound didecyl dimethyl ammonium chloride Bleach, containing the active ingredient sodium hypochlorite, was effective at concentrations of 1% sodium hypochlorite and above Cultures did not survive complete drying, which occurred after <3 h at room temperature B dendrobatidis was sensitive to heating, and within 4 h at 37°C, 30 min at 47°C and 5 min at 60°C, 100% mortality occurred UV light (at 1000 mW m–2 with a wavelength of 254 nm) was ineffective at killing B dendrobatidis in culture

283 citations


Journal ArticleDOI
TL;DR: The model predicts that H2O2 may enhance NDMA removal for short optical path lengths but that light-screening by H2 O2 may decrease the removal rates for Optical path lengths typical of those found in UV reactors.
Abstract: Both low- and medium-pressure Hg lamps (LP and MP, respectively) were used as ultraviolet light (UV) sources to destroy N-nitrosodimethylamine in a synthetic “natural” water. The lamp performances were directly compared via the UV fluence-based rate constants, which demonstrates that LP and MP have virtually identical photonic efficiencies (fluence-based rate constants of 2.29E-3 and 2.35E-3 cm2/mJ, respectively). This indicates that the quantum yield for NDMA photolysis is independent of wavelength in the UVC region: a value of 0.30 mol/einstein is found at pH 8.1. Addition of 100 mg/L of H2O2 leads to a 30% increase in the LP fluence-based rate constant but does not alter the MP rate constant, likely due to the tradeoff between light screening by H2O2 and additional radical based degradation. However, in terms of the time-based rate constant, this level of H2O2 slightly enhances the LP performance but hinders the MP performance, suggesting that H2O2 is of little or no economic benefit for NDMA removal ...

274 citations


Journal ArticleDOI
TL;DR: The results show that rpoB/Rif(r) is an accurate and easy to employ detection system, and offers the advantage of allowing analysis of mutations occurring on the chromosome rather than on an extrachromosomal element.

Journal ArticleDOI
TL;DR: In this article, the degradation of organic dyes by pulsed discharge plasma between needle-to-plane electrodes in contaminated water has been investigated in three discharge modes: (i) streamer, (ii) spark, and (iii) spark-streamer mixed mode.

Patent
Tomoko Ohtsuki1, Soichi Owa1
19 Feb 2003
TL;DR: In this paper, a single-wavelength oscillating laser was used to generate a single light having a single wavelength and a light dividing device for dividing or branching the amplified laser light into plural lights.
Abstract: An ultraviolet laser apparatus according to the present invention comprises a laser generating portion having a single-wavelength oscillating laser for generating laser light having a single wavelength falling within a wavelength range from an infrared band to a visible band, an optical amplifier having a fiber optical amplifier for amplifying the laser light generated by the laser generating portion, and a wavelength converting portion for wavelength-converting the amplified laser light into ultraviolet light by using a non-linear optical crystal, whereby ultraviolet light having a single wavelength is generated. Further, an exposure apparatus according to the present invention serves to transfer a pattern image of a mask onto a substrate and comprises a light source including a laser apparatus for emitting a laser light having a single wavelength, a first fiber optical amplifier for amplifying the laser light, a light dividing device for dividing or branching the amplified laser light into plural lights, and second fiber optical amplifiers for amplifying the plural divided or branched lights, respectively; and a transmission optical system for transmitting the laser light emitted from the light source to the exposure apparatus.

Journal ArticleDOI
TL;DR: The ability of ultraviolet irradiation to generate reactive oxygen species in human skin in vivo and genistein, which possesses both tyrosine kinase inhibitory and antioxidant activities, and n-acetyl cysteine, which can be converted into the endogenous antioxidant glutathione, to impair responses to ultraviolet light are investigated.

Patent
14 May 2003
Abstract: PROBLEM TO BE SOLVED: To solve the problem that the number of parts is made large and an entire projection type display device is not made small in size, light in weight and inexpensive because surface light sources emitting respective color light beams R, G and B and spatial optical modulators corresponding to the respective light sources are required in order to perform color display on the projection type display device SOLUTION: A light emitting diode emitting ultraviolet light is used for the light source, and a visible light reflection film having characteristic that the ultraviolet light is transmitted and visible light is reflected is formed on the surface of a color wheel on the light source side, and phosphor layers respectively emitting the visible light corresponding to the color light beams R, G and B by the radiation of the ultraviolet light are formed on the back surface side of the color wheel COPYRIGHT: (C)2005,JPO&NCIPI

Journal Article
TL;DR: Although the mechanisms by which immune regulatory suppressor T cells act still remain unclear, there is increasing evidence that apoptosis of epidermal LC or reactive T cells may play an important role through the Fas/FasL system.
Abstract: Ultraviolet radiation (UV) represents one of the most important environmental factors affecting human health, especially with regard to its hazardous effects on the generation of skin cancer, suppression of the immune system and premature skin aging. At molecular level, various chromophores have been identified, and DNA remains the major chromophore in the skin. Epidermal Langerhans cells (LC) are considered as the main targets of UV, as UV inhibits their antigen-presenting activity and their capacity to stimulate allogeneic type 1 T cells. Keratinocytes are also a target of UV light and they produce and release numerous soluble and immunosuppressive mediators. In human skin, IL-10 is mainly produced by dermis CD11b + macrophages and neutrophils that infiltrate epidermis after intense UV. UV-induced immunosuppression is transferable with suppressor T cells whose phenotype is still debated (Natural Killer T cells and T regulatory type 1 cells). Although the mechanisms by which immune regulatory suppressor T cells act still remain unclear, there is increasing evidence that apoptosis of epidermal LC or reactive T cells may play an important role through the Fas/FasL system.

Journal ArticleDOI
TL;DR: In this paper, the authors applied this property to the enhancement of boiling heat transfer and found that a surface coated with TiO2 exhibits an extremely high affinity for water when exposed to UV light and the contact angle decreases nearly to zero.
Abstract: Titanium Dioxide, TiO2, is a photocatalyst with a unique characteristic. A surface coated with TiO2 exhibits an extremely high affinity for water when exposed to UV light and the contact angle decreases nearly to zero. Inversely, the contact angle increases when the surface is shielded from UV. This superhydrophilic nature gives a self-cleaning effect to the coated surface and has already been applied to some construction materials, car coatings and so on. We applied this property to the enhancement of boiling heat transfer. An experiment involving the pool boiling of pure water has been performed to make clear the effect of high wettability on heat transfer characteristics. The heat transfer surface is a vertical copper cylinder of 17 mm in diameter and the measurement has been done at saturated temperature and in a steady state. Both TiO2-coated and non-coated surfaces were used for comparison. In the case of the TiO2-coated surface, it is exposed to UV light for a few hours before experiment and it is found that the maximum heat flux (CHF) is about two times larger than that of the uncoated surface. The temperature at minimum heat flux (MHF) for the superhydrophilic surface is higher by 100 K than that for the normal one. The superhydrophilic surface can be an ideal heat transfer surface. Copyright © 2002 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: The use of air as the purging gas, providing a stronger oxidising environment to both strains, gives a higher catalytic effect on bacteria inactivation than that of nitrogen.

Journal ArticleDOI
TL;DR: In this paper, a uniform coating and an optimized thickness of yellow phosphor layer on a gallium nitride (GaN) chip were necessary for achieving an efficient white light emitting diode.
Abstract: White light was obtained by mixing blue light from the emission of a gallium nitride (GaN) chip and yellow light from the fluorescence of a Y 3 Al 5 O 12 :Ce 0.05 yellow phosphor. A uniform coating and an optimized thickness of yellow phosphor layer on a GaN chip were necessary for achieving an efficient white light emitting diode. The phosphor particles were coated on a GaN chip or indium tin oxide by several methods including the slurry method, the settling method, and electrophoretic deposition (EPD). The properties of the phosphor layers prepared by these methods were examined using scanning electron microscope and photoluminescence. The chromaticity of white light was dependent upon the thickness of the phosphor layer. The properties of the phosphor layer prepared by EPD such as packing density, thickness, and uniformity could be more easily controlled than those by the slurry and settling methods. Further high packing density of the EPD could compensate for the typical thick phosphor layer, allowing the thin layer to be fabricated. To overcome the weak adhesion strength of phosphor particles by the EPD, an aqueous solution including poly(vinyl alcohol) + ammonium dichromate was coated on the phosphor layer and cured by exposure to ultraviolet light.

Journal ArticleDOI
01 Oct 2003-Cornea
TL;DR: Early reports on the efficacy of topical Iterferon alpha 2b indicate significant promise in providing another alternative for the treatment of some of these neoplasms and represent a minimally invasive and highly successful approach to the diagnosis and treatment of OSSN.
Abstract: Even though ocular surface squamous neoplasia (OSSN) has been recognized for well over a century, the past decade has witnessed advances that have helped rewrite many of the paradigms for the diagnosis and management of these lesions. OSSN occurs predominantly in the elderly for whom they are the third most common oculoorbital tumors after melanoma and lymphoma. In addition to advanced age and male sex, other major risk factors linked to its pathogenesis are ultraviolet light, cigarette smoking, and the human papilloma virus. Although the latter has been linked to OSSN for nearly 4 decades, its identification and role in the pathogenesis of these tumors has been elucidated recently and is addressed in detail in this review. Newer techniques of impression cytology represent a noninvasive and reliable method of diagnosing OSSN and monitoring treated cases. The efficacy of chemotherapeutic agents such as mitomycin C and 5-fluorouracil have been proven in the recent past, making them a clear alternative to the time-tested treatment of surgical excision and cryotherapy. Early reports on the efficacy of topical Iterferon alpha 2b indicate significant promise in providing another alternative for the treatment of some of these neoplasms. These advances thus represent a minimally invasive and highly successful approach to the diagnosis and treatment of OSSN.

Journal ArticleDOI
23 May 2003-Science
TL;DR: It is reported that constant light, which disrupts circadian clock function at both the behavioral and molecular levels in monarchs, also disrupts the time-compensated component of flight navigation and shown that ultraviolet light is important for flight navigation but is not required for photic entrainment of circadian rhythms.
Abstract: Migratory monarch butterflies use a time-compensated Sun compass to navigate to their overwintering grounds in Mexico. Here, we report that constant light, which disrupts circadian clock function at both the behavioral and molecular levels in monarchs, also disrupts the time-compensated component of flight navigation. We further show that ultraviolet light is important for flight navigation but is not required for photic entrainment of circadian rhythms. Tracing these distinct light-input pathways into the brain should aid our understanding of the clock-compass mechanisms necessary for successful migration.

Journal ArticleDOI
19 Feb 2003-Langmuir
TL;DR: In this article, a photo assisted sol−gel method was used to transform amorphous titania nanoparticles into crystalline anatase phase at lower calcination temperature compared to those prepared by a conventional sol-gel method, and the particle size distribution of anatase powder samples is also affected by UV illumination on the colloid.
Abstract: Titanium dioxide nanoparticles were prepared via a photoassisted sol−gel method in which ultraviolet light irradiation was used in the preparation process of TiO2 colloid. After characterization by X-ray diffraction, X-ray absorption near-edge structure (XANES) at the Ti K-edge, laser Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy, it was found that the amorphous titania nanoparticles prepared by a photoassisted sol−gel method can be transformed into crystalline anatase phase at lower calcination temperature compared to those prepared by a conventional sol−gel method. In addition, the particle size distribution of anatase powder samples is also affected by UV illumination on the colloid. It is suggested that UV illumination can induce the formation of oxygen vacancies on the colloid and this results in the accelerated phase transition from amorphous to anatase titania.

Patent
10 Nov 2003
TL;DR: In this paper, a low-temperature process to remove at least a portion of at least one pore-forming phase within a multiphasic film and forming a porous film is described.
Abstract: Low dielectric materials and films comprising same have been identified for improved performance when used as interlevel dielectrics in integrated circuits as well as methods for making same. In certain embodiments of the invention, there is provided a low-temperature process to remove at least a portion of at least one pore-forming phase within a multiphasic film thereby forming a porous film. The pore-forming phase may be removed via exposure to at least one energy source, preferably an ultraviolet light source, in a non-oxidizing atmosphere.

Journal ArticleDOI
TL;DR: In this paper, the effect of various sintering atmospheric conditions on the crystalline phases and luminescent properties of the products were investigated in detail, and red and orange long afterglow was observed after phosphors were excited with 365nm ultraviolet light.

Journal ArticleDOI
TL;DR: Findings suggest that beetroot, which is a regularly consumed natural product colorant is an effective cancer chemopreventive agent in mice, and warrants more attention for possible human applications in the control of malignancy.

Journal ArticleDOI
TL;DR: Copper-silver ionization is now the only disinfection modality to have fulfilled all four evaluation criteria and no cases of hospital-acquired legionnaires' disease have occurred in any hospital since 1995.
Abstract: Background and Objectives:Hospital-acquired legionnaires' disease can be prevented by disinfection of hospital water systems This study assessed the long-term efficacy of copper-silver ionization as a disinfection method in controlling Legionella in hospital water systems and reducing the incidence of hospital-acquired legionnaires' disease A standardized, evidence-based approach to assist hospitals with decision making concerning the possible purchase of a disinfection system is presentedDesign:The first 16 hospitals to install copper-silver ionization systems for Legionella disinfection were surveyed Surveys conducted in 1995 and 2000 documented the experiences of the hospitals with maintenance of the system, contamination of water with Legionella, and occurrence of hospital-acquired legionnaires' disease All were acute care hospitals with a mean of 435 bedsResults:All 16 hospitals reported cases of hospital-acquired legionnaires' disease prior to installing the copper-silver ionization system Seventy-five percent had previously attempted other disinfection methods including superheat and flush, ultraviolet light, and hyperchlorination By 2000, the ionization systems had been operational from 5 to 11 years Prior to installation, 47% of the hospitals reported that more than 30% of distal water sites yielded Legionella In 1995, after installation, 50% of the hospitals reported 0% positivity, and 43% still reported 0% in 2000 Moreover, no cases of hospital-acquired legionnaires' disease have occurred in any hospital since 1995Conclusions:This study represents the final step in a proposed 4-step evaluation process of disinfection systems that includes (1) demonstrated efficacy of Legionella eradication in vitro using laboratory assays, (2) anecdotal experiences in preventing legionnaires' disease in individual hospitals, (3) controlled studies in individual hospitals, and (4) validation in confirmatory reports from multiple hospitals during a prolonged time (5 to 11 years in this study) Copper-silver ionization is now the only disinfection modality to have fulfilled all four evaluation criteria

Journal ArticleDOI
TL;DR: Long‐term studies illustrate the effectiveness of topical treatment with celecoxib in reducing chronic inflammation and UVB‐induced papilloma/carcinoma formation and provide compelling evidence to explore the clinical efficacy of topically applied COX‐2 inhibitors for the prevention of human skin cancers.
Abstract: Inflammation, which includes the release of growth factors, proinflammatory cytokines and prostaglandins, the infiltration and activation of inflammatory cells, and the induction of oxidative DNA damage, is known to play a role in cancer development. The combination of damage to the skin resulting from chronic ultraviolet light B (UVB) exposure itself and the inflammatory response it induces is a major source of skin cancer development. Cyclooxygenase-2 (COX-2), an inflammatory enzyme responsible for the production of prostaglandins, is now implicated in the development of epithelial cancers, including squamous cell carcinoma in the skin. Previous work conducted in our laboratory has shown that topical treatment with celecoxib following UVB irradiation inhibits several parameters of acute inflammation, including vascular permeability, the infiltration and activation of neutrophils, and the production of prostaglandin E(2) (PGE(2)). The present studies expanded these observations, demonstrating the ability of topical celecoxib to inhibit acute oxidative damage. In addition, long-term studies illustrate the effectiveness of topical treatment with this drug in reducing chronic inflammation and UVB-induced papilloma/carcinoma formation. This data provides compelling evidence to explore the clinical efficacy of topically applied COX-2 inhibitors for the prevention of human skin cancers.

Journal ArticleDOI
TL;DR: In this article, a solid phase photocatalytic degradation of polystyrene (PS) plastic with TiO 2 as photocatalyst was investigated in the ambient air under ultraviolet light irradiation.

Journal ArticleDOI
TL;DR: In this article, two series of nano-sized N-containing MOx-ZnO (M: Fe, W) composite powders were synthesized by spray pyrolysis.
Abstract: Two series of nano-sized N-containing MOx–ZnO (M: Fe, W) composite powders were synthesized by spray pyrolysis. The nitrogen content was controlled from 500 to 2100 ppm by changing the powder ingredients and spray pyrolysis temperature. Ultraviolet-visible (UV-Vis) spectra indicated that the N-containing MOx–ZnO powders absorbed not only ultraviolet light (λ<387 nm) like pure ZnO powder, but also part of visible light (λ<650 nm). Acetaldehyde decomposition was used as a probe reaction to evaluate the photocatalysis of these composite powders. The photocatalytic activity of the N-containing ZnO powder was pronouncedly enhanced by the WO3 addition under both UV and visible-light irradiation. However, that of the N-containing ZnO powder was suppressed by the Fe2O3 addition. A model of the semiconductor energy-band structure is proposed to explain the enhancement and suppression of photocatalytic activity.

Journal ArticleDOI
TL;DR: The association between increasing age, sun exposure, and amount of telangiectasia was strong among men, but less apparent among women, and smoking was also associated with elastosis among both sexes, and with telang iectasia predominantly among men.