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Sample records for psoralens potentiate ultraviolet

  1. Psoralen-ultraviolet A treatment with Psoralen-ultraviolet B therapy in the treatment of psoriasis.

    Science.gov (United States)

    Ahmed Asim, Sadaf; Ahmed, Sitwat; Us-Sehar, Najam

    2013-05-01

    To compare the conventional psoralen-ultraviolet A treatment with psoralen-ultraviolet B therapy in the treatment of psoriasis. We studied 50 patients of plaque type psoriasis who were selected to receive either conventional psoralen-ultraviolet A or psoralen-ultraviolet B treatment. There was no significant difference between the two treatment groups in the number of patients whose skin cleared of psoriasis or the number of exposures required for clearance. Profile of side effects and disease status was also similar after three months of follow up. Psoralen-ultraviolet B treatment is as effective as conventional psoralen-ultraviolet A in the treatment of psoriasis. Further long term studies are needed to assess the safety of psoralen-ultraviolet B.

  2. Sensitivity of Escherichia coli acrA Mutants to Psoralen plus Near-Ultraviolet Radiation

    DEFF Research Database (Denmark)

    Hansen, M. Trier

    1982-01-01

    The sensitivity to psoralen plus near-ultraviolet radiation (PUVA) was compared in a pair of E. coli strains differing at the acrA locus. Survival was determined for both bacteria and phage λ. AcrA mutant cells were 40 times more sensitive than wild type to the lethal effect of PUVA. Free λ phage...... of radiolabelled psoralens in the mutant. Binding was increased specifically to DNA rather than to nucleic acids in general. The difference in psoralen-binding ability determined by the acrA gene persisted after permeabilizing treatment of the cells. The results suggest that the acrA mutation causes an alteration...

  3. Narrow-band ultraviolet B phototherapy versus broad-band ultraviolet B or psoralen-ultraviolet A photochemotherapy for psoriasis.

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    Chen, Xiaomei; Yang, Ming; Cheng, Yan; Liu, Guan J; Zhang, Min

    2013-10-23

    The most commonly used types of phototherapy for treating psoriasis are narrow-band ultraviolet B (NB-UVB); broad-band ultraviolet B (BB-UVB), which includes selective (delivering radiation with a wavelength range of 305 to 325 nm) and conventional BB-UVB (280 to 320 nm); and psoralen ultraviolet A photochemotherapy (oral or bath PUVA). There is substantial controversy regarding their efficacy when compared with each other. To assess the effects of narrow-band ultraviolet B phototherapy versus broad-band ultraviolet B or psoralen ultraviolet A photochemotherapy for psoriasis. We searched the following databases up to August 2013: the Cochrane Skin Group Specialised Register, CENTRAL in The Cochrane Library (2013, Issue 7), MEDLINE (from 1946), and EMBASE (from 1974). We searched the following databases up to November 2012: CNKI (from 1974) and CBM (from 1978). We also searched trials registers and the OpenGrey database. We included all randomised controlled trials (RCTs) that compared NB-UVB phototherapy with BB-UVB or PUVA for treating psoriasis, which included chronic plaque psoriasis (CPP), guttate psoriasis (GP), and palmoplantar psoriasis (PPP). Two review authors independently conducted the study selection, 'Risk of bias' assessment, and data extraction. We included 13 RCTs, with a total of 662 participants. We report the results of intention-to-treat analyses (ITT) here. Our primary outcomes of interest were as follows: Participant-rated global improvement, Percentage of participants reaching Psoriasis Area and Severity Index (PASI) 75 (which meant equal to or more than 75% reduction in PASI score), Withdrawal due to side-effects, and Clearance rate.In one RCT of NB-UVB compared with oral PUVA in participants with CPP, the difference in PASI 75 was not statistically significant (risk ratio (RR) 0.91, 95% confidence interval (CI) 0.63 to 1.32; N = 51; low quality). In three other RCTs of CPP, the clearance rates were inconsistent because in one, there was no

  4. Isolation and characterization of pyrimidine-psoralen-pyrimidine photodiadducts from DNA. [Ultraviolet radiation

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    Kanne, D.; Straub, K.; Hearst, J.E.; Rapoport, H.

    1982-12-01

    The isolation and characterization of pyrimidine-psoralen-pyrimidine photodiadducts from DNA are reported for the first time. For each of the four psoralens studied, a single pair of diastereomeric thymidine-psoralen-thymidine photodiadducts, each with cis-syn stereochemistry, was found to account for > 90% of the diadducts formed. Additionally, pulse-chase experiments that establish that these photo cross-links are formed by cycloaddition of a second thymidine residue to the 3,4 double bond (pyrone side) of an initially formed 4',5' (furan-side) psoralen-thymidine photomonoadduct have been carried out.

  5. Psoralen plus ultraviolet A (PUVA soaks and UVB TL01 treatment for chronic hand dermatoses

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    Lisbeth Jensen

    2012-02-01

    Full Text Available Chronic eczematous hand dermatoses with and without contact allergies are complex diseases, which makes it a challenge to select the best treatment and obtain an optimal patient experience and a satisfactory treatment result. The aim of this study was to evaluate retrospectively the clinical effect and patient experience of local treatment with psoralen plus ultraviolet A (PUVA soaks and TL01 phototherapy for severe chronic hand dermatoses, and also to evaluate the quality of life for the subgroup of patients with allergic contact dermatitis including Compositae allergy. A retrospective evaluation of results for 94 consecutive patients having received a total of 121 treatment courses with local PUVA soaks or TL01 phototherapy for one of the following diagnoses (n=number of treatment courses: psoriasis (n=19, hyperkeratotic hand eczema (n=27, Pustulosis Palmoplantaris (PPP (n=22, vesicular eczema (n=16, Compositae dermatitis (n=24, and allergic contact dermatitis (n=13. Moreover, semi-structured interviews with 6 selected patients having multiple contact allergies including Compositae allergy were used to evaluate quality of life. As a result, we found that PUVA soaks has good effect in patients with psoriasis and hyperkeratotic hand eczema and local phototherapy for chronic hand dermatoses is a useful treatment option in selected cases.

  6. Spectral effects in activation of the human immunodeficiency virus promoter by psoralens plus ultraviolet A treatment.

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    Miller, S A; Beer, J Z; Strickland, A G; Zmudzka, B Z

    The effects of PUVA treatment on HIV promoter activation and cell killing in HIV cat/HeLa cells were studied using two UV sources, a UVASUN sunlamp and a UVAR Photoactivation Chamber. A 4 to 5 times higher dose of ultraviolet radiation was required from the UVASUN lamp than from the UVAR lamps: 1) to activate the HIV promoter in the presence of 0.1 or 1.0 microgram/ml 8-MOP and 2) to reduce cell survival to a level of 10%, in the presence of 0.1 or 1.0 microgram/ml 8-MOP. In addition, exposures performed with a fixed dose of 20 kJ/m2 at varying concentrations of 8-MOP, required a 4.7 times higher combined PUVA dose from the UVASUN lamp than from the UVAR lamps. Two possible sources of these differences were analyzed: (1) the presence of UVB + UVA2 (280-340 nm) in the radiation emitted by the UVAR, but not the UVASUN lamp, and its potential biological activity independent of 8-MOP, and (2) the difference in the overlap of the emission spectra of the two lamps with the absorption spectrum of 8-MOP. The area of overlap was higher for the UVAR lamp than for the UVASUN lamp by a factor of 4.6, which is close to the difference between these two lamps in induction of the HIV promoter and killing HeLa cells. This indicates that the effectiveness of a particular UVA source used in combination with 8-MOP can be predicted by its congruence to the absorption spectrum of the photosensitizing drug.

  7. Determination of the minimal phototoxic dose and colorimetry in psoralen plus ultraviolet A radiation therapy.

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    Kraemer, Cristine Kloeckner; Menegon, Dóris Baratz; Cestari, Tania Ferreira

    2005-10-01

    The use of an adequate initial dose of ultraviolet A (UVA) radiation for photochemotherapy is important to prevent burns secondary to overdosage, meanwhile avoiding a reduced clinical improvement and long-term risks secondary to underdosage. The ideal initial dose of UVA can be achieved based on the phototype and the minimal phototoxic dose (MPD). The objective measurement of constitutive skin color (colorimetry) is another method commonly used to quantify the erythematous skin reaction to ultraviolet radiation exposure. The aim of this study was to determine variations in MPD and constitutional skin color (coordinate L(*)) within different phototypes in order to establish the best initial dose of UVA radiation for photochemotherapy patients. Thirty-six patients with dermatological conditions and 13 healthy volunteers were divided into five groups according to phototype. Constitutional skin color of the infra-axillary area was assessed by colorimetry. The infra-axillary area was subsequently divided into twelve 1.5 cm(2) regions to determine the MPD; readings were performed 72 h after oral administration of 8-methoxypsoralen (MOP) followed by exposure of the demarcated regions to increasing doses of UVA. The majority of the participants were women (73.5%) and their mean age was 38.8 years. The MPD ranged from 4 to 12 J/cm(2) in phototypes II and III; from 10 to 18 J/cm(2) in type IV; from 12 to 24 J/cm(2) in type V and from 18 to 32 J/cm(2) in type VI. The analysis of colorimetric values (L(*) coordinate) and MPD values allowed the definition of three distinctive groups of individuals composed by phototypes II and III (group 1), types IV and V (group 2), and phototype VI (group 3). MPD and L(*) coordinate showed variation within the same phototype and superposition between adjacent phototypes. The values of the L(*) coordinate and the MPD lead to the definition of three distinct sensitivity groups: phototypes II and III, IV and V and type VI. Also, the MPD values

  8. Psoralen loaded liposomal nanocarriers for improved skin penetration and efficacy of topical PUVA in psoriasis.

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    Doppalapudi, Sindhu; Jain, Anjali; Chopra, Dhiraj Kumar; Khan, Wahid

    2017-01-01

    Psoralen in combination with ultraviolet A radiation (PUVA) is an FDA recommended therapy for clinical application in the management of severe recalcitrant psoriasis. Psoralen acts by intercalation of DNA and upon exposure to UV-A, it forms monoadducts which in turn induce apoptosis. Poor skin deposition, weak percutaneous permeability of psoralen and adverse effects of severe burning, blisters, pigmentation associated with conventional topical psoralen vehicles hinders the therapeutic efficacy and safety of topical PUVA. The aim of the present study is to formulate psoralen loaded liposomal nanocarriers for enhanced skin penetration, safety and efficacy of topical PUVA in psoriasis. Two different liposomal compositions i.e., cationic liposomes composed of DC-Chol, cholesterol and anionic liposomes composed of egg lecithin, cholesterol, tetramyristoyl cardiolipin were prepared for the topical delivery of psoralen. Liposomal carriers were characterized with respect to size, zeta potential, entrapment efficiency, stability, in vitro drug release and in vivo studies. Both liposomes were prepared with particle size of nearly 100nm. Zeta potential and entrapment efficiency of cationic liposomes were +25.8mV, 75.12% and anionic liposomes were -28.5mV, 60.08% respectively. Liposomal dermal distribution demonstrated higher penetration of both liposomal carriers over solution. Similarly, skin permeation study indicated 5 fold increase in permeation of psoralen with liposomal carriers. Topical application of psoralen liposomal gels on imiquimod induced psoriatic plaque model reduced the symptoms of psoriasis and levels of key psoriatic cytokines such as tumor necrosis factor-α, IL-17 and IL-22. In conclusion, the developed liposomal carriers of psoralen were found to be promising and can find application for optimal safety and efficacy of topical PUVA in psoriasis. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Inactivation of viruses in platelet suspensions that retain their in vitro characteristics: Comparison of psoralen-ultraviolet A and merocyanine 540-visible light methods

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    Dodd, R.Y.; Moroff, G.; Wagner, S.; Dabay, M.H.; Dorfman, E.; George, V.; Ribeiro, A.; Shumaker, J.; Benade, L.E. (Jerome H. Holland Laboratory, American Red Cross, Rockville, MD (USA))

    1991-07-01

    The ability of two fundamentally different photochemical procedures to inactivate model viruses in platelet suspensions was compared. Merocyanine 540 (MC 540) with visible light was used as an example of an oxygen-dependent chemical-directed at the viral membrane, and aminomethyl trimethyl psoralen (AMT) with ultraviolet A light (UVA) was used as an example of a nucleic acid-directed system. Antiviral conditions in petri dishes were identified and the effects of these procedures on platelet suspensions in plastic storage containers were studied. Concentrations of photochemicals in the 10 to 150 mumol range with 30 to 60 minutes of visible light (MC 540) or 1 to 2 minutes of UVA (AMT) readily inactivated 5 to 6 log10 of vesicular stomatitis virus (VSV) and other model viruses in platelet suspensions, provided the plasma concentration was reduced to about 15 percent by the use of a synthetic platelet storage medium. Extracellular pH, morphology scores, and aggregation response dropped markedly when platelets were treated with MC 540 and visible light. However, treatment with 136 mumol per L of AMT and 1 to 3 minutes of UVA could inactivate 5 log10 of VSV in platelet suspensions with retention of platelet characteristics for 4 days, particularly if oxygen levels were reduced during treatment. These studies demonstrate that AMT-UVA treatment meets the initial requirements for virus inactivation in platelet suspensions.

  10. Comparison of ethosomes and liposomes for skin delivery of psoralen for psoriasis therapy.

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    Zhang, Yong-Tai; Shen, Li-Na; Wu, Zhong-Hua; Zhao, Ji-Hui; Feng, Nian-Ping

    2014-08-25

    Recent reports have indicated that psoriasis may be caused by malfunctioning dermal immune cells, and psoralen ultraviolet A (PUVA) is an effective treatment for this chronic disease. However, conventional topical formulations achieve poor drug delivery across patches of psoriasis to their target sites. The present study describes the development of a novel psoralen transdermal delivery system employing ethosomes, flexible vesicles that can penetrate the stratum corneum and target deep skin layers. An in vitro skin permeation study showed that the permeability of psoralen-loaded ethosomes was superior to that of liposomes. Using ethosomes, psoralen transdermal flux and skin deposition were 38.89±0.32 μg/cm(2)/h and 3.87±1.74 μg/cm(2), respectively, 3.50 and 2.15 times those achieved using liposomes, respectively. The ethosomes and liposomes were found to be safe following daily application to rat skin in vivo, for 7 days. The ethosomes showed better biocompatibility with human embryonic skin fibroblasts than did an equivalent ethanol solution, indicating that the phosphatidylcholine present in ethosome vesicles improved their biocompatibility. These findings indicated that ethosomes could potentially improve the dermal and transdermal delivery of psoralen and possibly of other drugs requiring deep skin delivery. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Development and in vitro assessment of psoralen and resveratrol co-loaded ultradeformable liposomes for the treatment of vitiligo.

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    Doppalapudi, Sindhu; Mahira, Shaheen; Khan, Wahid

    2017-09-01

    Vitiligo is a de-pigmenting skin disorder characterized by white patches on skin due to partial or complete loss of melanocytes. Psoralen in combination with ultraviolet-A (PUVA) acts by stimulation of melanin content and tyrosinase activity in melanocytes. Resveratrol, a sirtuin activator and a potential anti-oxidant reduce oxidative stress which is one of the triggering factors for initiation of vitiligo. Despite their therapeutic activity, weak percutaneous permeability of psoralen and poor solubility of resveratrol hinders their effective topical administration. The aim of present study is to formulate ultradeformable liposomes (UDL) co-loaded with psoralen and resveratrol for evaluation of PUVA and anti-oxidant combination in vitiligo treatment. For this purpose, UDL composed of DC-Chol, cholesterol and sodium deoxy cholate were prepared for their co-delivery. Liposomal carriers were characterized and evaluated for their efficacy using B16F10 cell line. Free radical scavenging potential was also determined for these carriers by in vitro anti-oxidant assays. Optimal co-loaded UDL with particle size ranging from 120 to 130nm, zeta potential of +46.2mV, entrapment efficiency of 74.09% (psoralen) and 76.91% (resveratrol) were obtained. Compared to control, co-loaded UDL showed significant stimulation of melanin and tyrosinase activity with major contribution of psoralen. Further, co-loaded UDL also exhibited potential free radical scavenging activity where resveratrol played a key role. Hence, psoralen and resveratrol co-loaded UDL acts in vitiligo through dual mechanisms of action viz., stimulation of melanin and tyrosinase activity as well as by anti-oxidant activity. These findings indicate that psoralen and resveratrol co-loaded UDL has the promising therapeutic potential for the treatment of vitiligo. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Hypertrichosis by Topical Psoralen

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    K Pavithran

    1984-01-01

    Full Text Available Two cases in which topical psoralen induced hypertrichosis in the depigmented patches of vitiligo are being reported. -The possible mechanisms for this hypertrichosis are briefly discussed.

  13. Psoralen-containing sunscreen is tumorigenic in hairless mice

    Energy Technology Data Exchange (ETDEWEB)

    Cartwright, L.E.; Walter, J.F.

    1983-06-01

    Sunscreens containing 5-methoxypsoralen (5-MOP) are currently being marketed to promote tanning by inducing psoralen-mediated ultraviolet (UV) A (320-400 nm) melanogenesis. The rationale is that this may prevent UVB (290-320 nm) radiation-induced skin damage. However, mouse studies have shown that 5-MOP has the same cutaneous photocarcinogenic potential as 8-methoxypsoralen. In addition, the 5-MOP--containing sunscreen Sun System III (SS III), when combined with UVA, induces epidermal ornithine decarboxylase activity, an enzyme associated with tumor promotion. Therefore, we investigated whether SS III had sufficient psoralen concentration to be tumorigenic in hairless mice exposed to chronic, intermittent UVA radiation. SS III was applied to hairless mice 5 days per week for 20 weeks. After each application the mice were exposed to 2.5 to 10 joules/cm2 UVA radiation. All test groups developed atypical squamous papillomas in direct proportion to the dosage of UVA radiation received. A shorter latency period for tumor development was seen with larger UVA doses. Test animals followed up to 1 year developed invasive squamous cell tumors. Control groups (SS III without UVA and UVA without SS III) remained free of tumors. Animals receiving SS III plus UVA developed persistent skin thickening and increased dermal cyst formation similar to that reported with chronic exposure to UVB, a known carcinogenic wavelength.

  14. Psoralens and coumarins for receptor targeting on epidermal cells

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    Jetter, M.M.

    1989-01-01

    Specific binding sites have been identified for the psoralens, discrete from DNA, in different epidermal cell lines. These receptors are saturable and are alkylated by the action of psoralens + UVA light. A psoralen receptor has been partially purified and established to be a protein of approximately 20,000 daltons. Inhibition of the binding of epidermal growth factor to its receptor and inhibition of the tyrosine kinase activity of the EGF receptor has been associated with PUVA treatment. These findings conflict with the general assumption that the biological effects of psoralens as photoactive compounds are associated with their ability to covalently bind to and crosslink DNA. In collaboration with Laskin's,laboratory, several classes of psoralen agonists were synthesized. These compounds include coumarins, furocoumarin and benzodipyran-2-one derivatives. The methods of preparation were varied and include variants of the Claisen rearrangement, acid and base-catalyzed condensations. The synthesized compounds were tested for their potential inhibition of {sup 125}I-EGF receptor binding. It was discovered that many of these agents showed potent inhibition activity similar to the psoralens. This data offers the possibility that sites of action, other than DNA, are involved in the mechanism by which photoactivated psoralens modulate epidermal cell lines.

  15. X-Ray Psoralen Activated Cancer Therapy (X-PACT.

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    Mark Oldham

    Full Text Available This work investigates X-PACT (X-ray Psoralen Activated Cancer Therapy: a new approach for the treatment of solid cancer. X-PACT utilizes psoralen, a potent anti-cancer therapeutic with current application to proliferative disease and extracorporeal photopheresis (ECP of cutaneous T Cell Lymphoma. An immunogenic role for light-activated psoralen has been reported, contributing to long-term clinical responses. Psoralen therapies have to-date been limited to superficial or extracorporeal scenarios due to the requirement for psoralen activation by UVA light, which has limited penetration in tissue. X-PACT solves this challenge by activating psoralen with UV light emitted from novel non-tethered phosphors (co-incubated with psoralen that absorb x-rays and re-radiate (phosphoresce at UV wavelengths. The efficacy of X-PACT was evaluated in both in-vitro and in-vivo settings. In-vitro studies utilized breast (4T1, glioma (CT2A and sarcoma (KP-B cell lines. Cells were exposed to X-PACT treatments where the concentrations of drug (psoralen and phosphor and radiation parameters (energy, dose, and dose rate were varied. Efficacy was evaluated primarily using flow cell cytometry in combination with complimentary assays, and the in-vivo mouse study. In an in-vitro study, we show that X-PACT induces significant tumor cell apoptosis and cytotoxicity, unlike psoralen or phosphor alone (p<0.0001. We also show that apoptosis increases as doses of phosphor, psoralen, or radiation increase. Finally, in an in-vivo pilot study of BALBc mice with syngeneic 4T1 tumors, we show that the rate of tumor growth is slower with X-PACT than with saline or AMT + X-ray (p<0.0001. Overall these studies demonstrate a potential therapeutic effect for X-PACT, and provide a foundation and rationale for future studies. In summary, X-PACT represents a novel treatment approach in which well-tolerated low doses of x-ray radiation are delivered to a specific tumor site to generate UVA

  16. Cavamax W7 composite psoralen ethosomal gel versus cavamax W7 psoralen solid complex gel for topical delivery: A comparative evaluation

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    Kumari, Smriti; Pathak, Kamla

    2013-01-01

    Aim: The present research work was aimed to formulate and characterize psoralen-encapsulated cavamax W7 composite ethosomal gel and compare its in vitro and ex vivo behavior against psoralen-cavamax W7-complex reference gel. Materials and Methods: A total of nine formulations of composite ethosomes were prepared by injection method using 32 factorial design and entrapment efficiency was designated as dependent variable. Concomitantly, psoralen was complexed with cavamax W7 (1:1 molar ratio) by kneading method and formation of complex was confirmed by Diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). Results: F9 with vesicle size of 183 ± 2.8 nm, and highest % entrapment efficiency of 98.12 ± 1.15 was selected as optimized formulation. Transmission electron microscopy (TEM) revealed uniform and spherical shaped vesicles. The optimized formulation F9 was formulated as carbapol gel and compared against ethosomal gel, psoralen gel, and psoralen cavamax W7 complex gel. The gels were evaluated for permeation characteristics and the rank order was composite ethosomal gel > ethosomal gel > psoralen-cavamax W7 complex gel > psoralen gel. The ethosomal gel (G5) with highest in vitro permeation of 82.48 ± 2.23% was subjected to in vivo Confocal laser scanning microscopy (CLSM) studies using rhodamine B as tracer. The penetration of rhodamine B was uniform, deeper, and two times faster into epidermis than control gel. Conclusion: Conclusively, cavamax W7 composite ethosomes present themselves as efficient carrier for superior topical delivery of psoralen and have potential for clinical applications in minimizing side effects associated with photosensitivity of psoralen. PMID:24350036

  17. Possible mechanism of psoralen phototoxicity not involving direct interaction with DNA

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    Laskin, J.D.; Lee, E.; Yurkow, E.J.; Laskin, D.L.; Gallo, M.A.

    1985-09-01

    Psoralens in combination with ultraviolet light (UVA; 320-400 nm) are used in the photochemical treatment of a variety of skin diseases including vitiligo, a skin depigmentational disorder, and psoriasis, a disease of accelerated epidermal cell proliferation. Although it is generally assumed that the major site of action of the psoralens is DNA, the authors have obtained evidence that another site may be the primary target for these compounds. They have identified specific, saturable, high-affinity binding sites for 8-methoxypsoralen on HeLa cells and have detected specific binding of 8-methoxypsoralen to four other human cell lines and five mouse cell lines. In HeLa cells, specific binding is reversible and independent of the ability of the compound to intercalate into DNA. In addition, binding sites become covalently modified by the psoralen after UVA exposure. Specific binding of 8-(methyoxy-/sup 3/H)methoxypsoralen constitutes 79% of the label bound to the cells. Scatchard analysis indicated two classes of psoralen binding sites. Based on these findings, the authors hypothesize that specific binding sites for psoralens on mammalian cells mediate, at least in part, psoralen-induced phototoxicity.

  18. In vitro acetylcholinesterase inhibition by psoralen using molecular docking and enzymatic studies

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    Gauresh Somani

    2015-01-01

    Full Text Available Introduction: Alzheimer′s disease (AD has increased at an alarming rate and is now a worldwide health problem. Inhibitors of acetylcholinesterase (AChE leading to inhibition of acetylcholine breakdown constitute the main therapeutic strategy for AD. Psoralen was investigated as inhibitor of AChE enzyme in an attempt to explore its potential for the management of AD. Materials and Methods: Psoralen was isolated from powdered Psoralea corylifolia fruits. AChE enzyme inhibitory activity of different concentrations of psoralen was investigated by use of in vitro enzymatic and molecular docking studies. Further, the enzyme kinetics were studied using Lineweaver-Burk plot. Results: Psoralen was found to inhibit AChE enzyme activity in a concentration-dependent manner. Kinetic studies showed psoralen inhibits AChE in a competitive manner. Molecular docking study revealed that psoralen binds well within the binding site of the enzyme showing interactions such as π-π stacking and hydrogen bonding with residues present therein. Conclusion: The result of AChE enzyme inhibitory activity of the psoralen in this study is promising. It could be further explored as a potential candidate for further development of new drugs against AD.

  19. Anthracene with near ultraviolet light inhibiting epidermal proliferation.

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    Walter, J F; DeQuoy, P R

    1978-10-01

    Anthracene plus near ultraviolet (UV) light (UV-A, 320 to 400 nm) suppresses DNA synthesis and mitosis in mouse epidermis. Ultraviolet-A light or anthracene alone does not have any effect. There is no photoactivation of anthracene to enhance depression of DNA synthesis by either UV-B (290 to 320 nm) or UV-C (254 nm) light. While methoxsalen with UV-A light inhibits DNA synthesis, the phototoxic drugs chlorpromazine hydrochloride and demethylchlortetracycline do not. The combination of anthracene plus UV-A light may have therapeutic effectiveness for psoriasis with less potential for photocarcinogenesis than psoralens plus UV-A light.

  20. The application of psoralens to the study of DNA structure, function and dynamics

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    Spielmann, Peter Hans [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

    1991-04-01

    A series of six nitroxide spin-labeled psoralens were designed, synthesized and tested as probes for DNA dynamics. The synthesis of these spin-labeled psoralen derivatives and their photoreactivity with double-stranded DNA fragments is described. The spin labels (nitroxides) were demonstrated to survive the uv irradiation required to bind the probe to the target DNA. EPR spectra of the photobound spin-labels indicate that they do not wobble with respect to the DNA on the time-scales investigated. The author has used psoralen modified DNA as a model for the study of DNA repair enzyme systems in human cell free extracts. He has shown that damage-induced DNA synthesis is associated with removal of psoralen adducts and therefore is "repair synthesis" and not an aberrant DNA synthesis reaction potentiated by deformation of the DNA by adducts. He has found that all DNA synthesis induced by psoralen monoadducts is the consequence of removal of these adducts. By the same approach he has obtained evidence that this in vitro system is capable of removing psoralen cross-links as well. Reported here are synthetic methods that make use of high intensity lasers coupled with HPLC purification to make homogeneous and very pure micromole quantities of furan-side monoadducted, cross-linked, and pyrone-side monoadducted DNA oligonucleotide. These molecules are currently being studied by NMR and X-ray crystallography. The application of the site-specifically psoralen modified oligonucleotide synthesized by these methods to the construction of substrates for the investigation of DNA repair is also discussed.

  1. Reaction of the psoralens with deoxyribonucleic acid

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    Hearst, J.E.; Isaacs, S.T.; Kanne, D.; Rapoport, H.; Straub, K.

    1984-01-01

    This review has been limited to DNA reactions, and methods for radiolabelling psoralens, which have played an essential role in the isolation and purification of the photoproducts of the reaction between psoralens and nucleic acids, are reviewed herein. High-performance liquid chromatography procedures used for the separation of the photoadducts either as the nucleic adducts or as the free base adducts are discussed. Conclusions drawn from high-resolution proton magnetic resonance and high-resolution mass spectrometric studies of the structural determination of the isolated and purified adducts presented here have led to the assignment of the stereochemistry of the products and leave no doubt that the DNA helix influences both the kinetics and the stereospecificity of the photochemical reaction. The optical properties of the reactants and the photoproducts are catalogued. The kinetics of the photochemistry and its relationship to the fundamental properties of the various psoralen derivatives are discussed. 41 references, 19 figures, 8 tables.

  2. Photochemistry of psoralen-DNA adducts, biological effects of psoralen-DNA adducts, applications of psoralen-DNA photochemistry

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    Shi, Yun-bo

    1988-03-01

    This thesis consists of three main parts and totally eight chapters. In Part I, The author will present studies on the photochemistry of psoralen-DNA adducts, specifically, the wavelength dependencies for the photoreversals of thymidine-HMT (4'-hydroxymethyl-4, 5', 8-trimenthylpsoralen) monoadducts and diadduct and the same adducts incorporated in DNA helices and the wavelength dependecies for the photocrossslinking of thymidine-HMT monoadducts in double-stranded helices. In Part II, The author will report some biological effects of psoralen-DNA adducts, i.e., the effects on double-stranded DNA stability, DNA structure, and transcription by E. coli and T7 RNA polymerases. Finally, The author will focus on the applications of psoralen-DNA photochemistry to investigation of protein-DNA interaction during transcription, which includes the interaction of E. coli and T7 RNA polymerases with DNA in elongation complexes arrested at specific psoralen-DNA adduct sites as revealed by DNase I footprinting experiments. 123 refs., 52 figs., 12 tabs.

  3. Mechanisms Underlying the Antiproliferative and Prodifferentiative Effects of Psoralen on Adult Neural Stem Cells via DNA Microarray

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    You Ning

    2013-01-01

    Full Text Available Adult neural stem cells (NSCs persist throughout life to replace mature cells that are lost during turnover, disease, or injury. The investigation of NSC creates novel treatments for central nervous system (CNS injuries and neurodegenerative disorders. The plasticity and reparative potential of NSC are regulated by different factors, which are critical for neurological regenerative medicine research. We investigated the effects of Psoralen, which is the mature fruit of Psoralea corylifolia L., on NSC behaviors and the underlying mechanisms. The self-renewal and proliferation of NSC were examined. We detected neuron- and/or astrocyte-specific markers using immunofluorescence and Western blotting, which could evaluate NSC differentiation. Psoralen treatment significantly inhibited neurosphere formation in a dose-dependent manner. Psoralen treatment increased the expression of the astrocyte-specific marker but decreased neuron-specific marker expression. These results suggested that Psoralen was a differentiation inducer in astrocyte. Differential gene expression following Psoralen treatment was screened using DNA microarray and confirmed by quantitative real-time PCR. Our microarray study demonstrated that Psoralen could effectively regulate the specific gene expression profile of NSC. The genes involved in the classification of cellular differentiation, proliferation, and metabolism, the transcription factors belonging to Ets family, and the hedgehog pathway may be closely related to the regulation.

  4. Treatment of necrobiosis lipoidica with topical psoralen plus ultraviolet A

    NARCIS (Netherlands)

    de Rie, M. A.; Sommer, A.; Hoekzema, R.; Neumann, H. A. M.

    2002-01-01

    Background Necrobiosis lipoidica (NL) is a rare skin disease, mostly seen on the legs and often occurring in patients with diabetes mellitus. The disease belongs to the idiopathic cutaneous palisading granulomatous dermatitides associated with a degeneration of collagen, thus leading to skin

  5. Potential of herbs in skin protection from ultraviolet radiation

    Science.gov (United States)

    Korać, Radava R.; Khambholja, Kapil M.

    2011-01-01

    Herbs have been used in medicines and cosmetics from centuries. Their potential to treat different skin diseases, to adorn and improve the skin appearance is well-known. As ultraviolet (UV) radiation can cause sunburns, wrinkles, lower immunity against infections, premature aging, and cancer, there is permanent need for protection from UV radiation and prevention from their side effects. Herbs and herbal preparations have a high potential due to their antioxidant activity, primarily. Antioxidants such as vitamins (vitamin C, vitamin E), flavonoids, and phenolic acids play the main role in fighting against free radical species that are the main cause of numerous negative skin changes. Although isolated plant compounds have a high potential in protection of the skin, whole herbs extracts showed better potential due to their complex composition. Many studies showed that green and black tea (polyphenols) ameliorate adverse skin reactions following UV exposure. The gel from aloe is believed to stimulate skin and assist in new cell growth. Spectrophotometer testing indicates that as a concentrated extract of Krameria triandra it absorbs 25 to 30% of the amount of UV radiation typically absorbed by octyl methoxycinnamate. Sesame oil resists 30% of UV rays, while coconut, peanut, olive, and cottonseed oils block out about 20%. A “sclerojuglonic” compound which is forming from naphthoquinone and keratin is the reaction product that provides UV protection. Traditional use of plant in medication or beautification is the basis for researches and making new trends in cosmetics. This review covers all essential aspects of potential of herbs as radioprotective agents and its future prospects. PMID:22279374

  6. Ultraviolet A1 phototherapy for mycosis fungoides

    DEFF Research Database (Denmark)

    Olek-Hrab, K; Silny, W; Dańczak-Pazdrowska, A

    2013-01-01

    Background.  Mycosis fungoides (MF) is the most common form of primary cutaneous lymphoma, and is characterized by a malignant proliferation of CD4+ cells. Psoralen ultraviolet A (PUVA) irradiation is the most common treatment for cutaneous lesions. However, PUVA carries the risk of adverse...

  7. Isolation and purification of psoralen and isopsoralen and their ...

    African Journals Online (AJOL)

    Nude rat model of osteosarcoma was established; the rats were randomized into: normal saline group, psoralen low- and high-dose groups, isopsoralen low- and high-dose groups, and cisplatin group. Osteosarcoma volume and weight inhibition rates in nude rats in each group were observed; radioimmunoassay was ...

  8. Isolation and purification of psoralen and isopsoralen and their ...

    African Journals Online (AJOL)

    into: normal saline group, psoralen low- and high-dose groups, isopsoralen low- and high-dose groups, and cisplatin group. Osteosarcoma volume and weight inhibition rates in nude rats in each group were observed; radioimmunoassay was used to determine the serum alkaline phosphatase activity; peripheral blood cell ...

  9. Isolation and purification of psoralen and isopsoralen and their ...

    African Journals Online (AJOL)

    Isolation and purification of psoralen and isopsoralen and their efficacy and safety in the treatment of osteosarcoma in nude rats. Honghui Lu¥ , Lihai Zhang¥, Daohong Liu, Peifu Tang2, Feixiang Song. Orthopaedic Department , People's Liberation Army General Hospital, Beijing 100000, China. ¥Authors Contributed ...

  10. Topical or oral administration with an extract of Polypodium leucotomos prevents acute sunburn and psoralen-induced phototoxic reactions as well as depletion of Langerhans cells in human skin

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, S.; Pathak, M.A.; Fitzpatrick, T.B. [Massachusetts General Hospital, Harvard Medical School, Dept. of Dermatology, Boston, MA (United States); Cuevas, J. [Hospital Universitario de Guadalajara, Dept. of Pathology, Guadalajara (Spain); Villarrubia, V.G. [I.F. Cantabria SA, Medical Dept., Immunology Sect., Madrid (Spain)

    1997-12-31

    Sunburn, immune suppression, photo-aging, and skin cancers result from uncontrolled overexposure of human skin to solar ultraviolet radiation (UVR). Preventive measures, including photo-protection, are helpful and can be achieved by topical sun-screening agents. Polypodium leucotomos (PL) has been used for the treatment of inflammatory diseases and has shown some in vitro and in vivo immunomodulating properties. Its beneficial photo-protective effects in the treatment of vitiligo and its antioxidant properties encouraged us to evaluate in vivo the potentially useful photo-protective property of natural extract of PL after topical application or oral ingestion. Twenty-one healthy volunteers [either untreated or treated with oral psoralens (8-MOP or 5-MOP)] were enrolled in this study and exposed to solar radiation for evaluation of the following clinical parameters: immediate pigment darkening (IPD), minimal erythema dose (MED), minimal melanogenic dose (MMD), and minimal phototoxic dose (MPD) before and after topical or oral administration of PL. Immunohistochemical assessment of CD1a-expressing epidermal cells were also performed. PL was found to be photo-protective after topical application as well as oral administration. PL increased UV dose required for IPD (P<0.01), MED (P<0.001) and MPD (P<0.001). After oral administration of PL, MED increased 2.,8{+-}0.59 times and MPD increased 2.75{+-}0.5 and 6.8{+-}1.3 times depending upon the type of psoralen used. Immunohistochemical study revealed photo-protection of Langherhans cells by oral as well as topical PL. The observed photo-protective activities of oral or topical PL reveal a new avenue in examining the potentially useful field of systemic photo-protection and suggests that PL can be used as adjunct treatment and can make photochemotherapy and phototherapy possibly safe and effective when the control of cutaneous phototoxicity to PUVA or UVB is a limiting factor in such photo-therapies. (au). 50 refs.

  11. Phototoxic effects of Hypericum extract in cultures of human keratinocytes compared with those of psoralen.

    Science.gov (United States)

    Bernd, A; Simon, S; Ramirez Bosca, A; Kippenberger, S; Diaz Alperi, J; Miquel, J; Villalba Garcia, J F; Pamies Mira, D; Kaufmann, R

    1999-02-01

    Extracts of Hypericum perforatum (St. John's wort) are used in the treatment of depression. They contain the plant pigment hypericin and hypericin derivates. These compounds have light-dependent activities. In order to estimate the potential risk of phototoxic skin damage during antidepressive therapy, we investigated the phototoxic activity of hypericin extract using cultures of human keratinocytes and compared it with the effect of the well-known phototoxic agent psoralen. The absorbance spectrum of our Hypericum extract revealed maxima in the whole UV range and in parts of the visible range. We cultivated human keratinocytes in the presence of different Hypericum concentrations and irradiated the cells with 150 mJ/cm2 UVB, 1 J/cm2 UVA or 3 h with a white light of photon flux density 2.6 mumol m-2 s-1. The determination of the bromodeoxyuridine incorporation rate showed a concentration- and light-dependent decrease in DNA synthesis with high hypericin concentrations (> or = 50 micrograms/mL) combined with UVA or visible light radiation. In the case of UVB irradiation a clear phototoxic cell reaction was not detected. We found phototoxic effects even with 10 ng/mL psoralen using UVA with the same study design as in the case of the Hypericum extract. These results confirm the phototoxic activity of Hypericum extract on human keratinocytes. However, the blood levels that are to be expected during antidepressive therapy are presumably too low to induce phototoxic skin reactions.

  12. Site specificity of psoralen-DNA interstrand cross-linking determined by nuclease Bal31 digestion

    DEFF Research Database (Denmark)

    Zhen, W P; Buchardt, O; Nielsen, Henrik

    1986-01-01

    was analyzed, and these two psoralens showed identical site specificity. The 5'-TA preference is rationalized on the basis of the local DNA structure in terms of the pi-pi electronic interaction between the thymines and the intercalated psoralens, as well as on the base tilt angles of the DNA....

  13. Effects of nuclear isolation on psoralen affinity for chromatin

    Energy Technology Data Exchange (ETDEWEB)

    Inadomi, T.; Ross, P.M. (Rockefeller Univ., New York, NY (USA))

    1989-09-29

    We have tested the effects of nuclear isolation on intercalation of TMP (a psoralen) at specific sequences and in total DNA of cultured human cells. DNA in nuclei photobound about 20% more TMP than in cells and about 10% as much as purified DNA. In contrast, a transcribed ras gene and a randomly selected polymorphic sequence each bound about 20% more TMP than total DNA in cells. However, in nuclei, as in purified DNA, both sequences were just as sensitive as total DNA. Apparently, chromatin in cells exists within diverse TMP-binding environments and some of this diversity was lost upon nuclear isolation.

  14. Evaluation of psoralen ethosomes for topical delivery in rats by using in vivo microdialysis.

    Science.gov (United States)

    Zhang, Yong-Tai; Shen, Li-Na; Zhao, Ji-Hui; Feng, Nian-Ping

    2014-01-01

    This study aimed to improve skin permeation and deposition of psoralen by using ethosomes and to investigate real-time drug release in the deep skin in rats. We used a uniform design method to evaluate the effects of different ethosome formulations on entrapment efficiency and drug skin deposition. Using in vitro and in vivo methods, we investigated skin penetration and release from psoralen-loaded ethosomes in comparison with an ethanol tincture. In in vitro studies, the use of ethosomes was associated with a 6.56-fold greater skin deposition of psoralen than that achieved with the use of the tincture. In vivo skin microdialysis showed that the peak concentration and area under the curve of psoralen from ethosomes were approximately 3.37 and 2.34 times higher, respectively, than those of psoralen from the tincture. Moreover, it revealed that the percutaneous permeability of ethosomes was greater when applied to the abdomen than when applied to the chest or scapulas. Enhanced permeation and skin deposition of psoralen delivered by ethosomes may help reduce toxicity and improve the efficacy of long-term psoralen treatment.

  15. Induction of mixed-function oxidases in mouse liver by psoralens.

    Science.gov (United States)

    Mandula, B B; Pathak, M A; Nakayama, Y; Davidson, S J

    1978-12-01

    8-methoxypsoralen, the most widely used psoralen in photochemotherapy, was shown to induce mixed-function oxidases. Induction of mixed-function oxidases in mouse liver was examined after mice were given a single dose of one of three psoralens. 8-methoxypsoralen clearly induced p-nitroanisole O-demethylase and slightly induced aryl hydrocarbon hydroxylase. Psoralen and 4,5',8-trimethylpsoralen failed to induce either enzyme. These results represent the first enzyme induction studies on these clinically useful compounds. The studies may have relevance in understanding the clinical differences in skin photosensitizing activity and photochemotherapeutic effectiveness of the compounds in such diseases as psoriasis and vitiligo.

  16. A method for fast determination of psoralens in oral solutions of phytomedicines using liquid chromatography.

    Science.gov (United States)

    Pires, Adriana Elias; Honda, Neli Kiko; Cardoso, Cláudia Andréa Lima

    2004-10-29

    A method for sample preparation and analysis by high performance liquid chromatography with UV detection (HPLC-UV) has been developed for routine analysis of psoralen and bergapten, photosensitizing compounds, in oral solutions of phytomedicines employed in Brazil for some illnesses. The linearity, accuracy, the inter- and intra-day precision of the procedure were evaluated. Calibration curves for psoralen and bergapten were linear in the range of 1.0-600.0 microg ml(-1) and 1.0-400.0 microg ml(-1) respectively. The recoveries of the psoralens in the oral solutions analysed were 94.43-99.97%. The percentage coefficient of variation (CV) of the quantitative analysis of the psoralens in the products analysis was within 5%. In inter-equipment study was employed gas chromatography-flame ionization (CG-FID) detection.

  17. Isolation and characterization of pyrimidine-psoralen photoadducts from DNA

    Energy Technology Data Exchange (ETDEWEB)

    Straub, K.; Kanne, D.; Hearst, J.E.; Rapoport, H.

    1981-05-06

    We have examined the photoadducts of 4'-hydroxymethyl-4,5',8-trimethylpsoralen (HMT) and native DNA. Five nucleoside-HMT monoaddition products have been isolated and characterized, corresponding to three deoxythymidine-HMT and two deoxyuridine (derived from deoxycytidine)-HMT adducts. Structural assignments are based on high resolution mass spectrometry and /sup 1/H NMR studies, including homonuclear spin decoupling and nuclear Overhauser effect (NOE) experiments. The results of this study indicate that (1) a limited number of nucleoside-psoralen adducts are formed with native, double-stranded DNA, and (2) the sterochemistry of the adducts is apparently determined by the geometry of the noncovalent intercalative complex formed by HMT and DNA prior to irradiation. 8 figures, 8 tables.

  18. Psoralen-mediated virus photoinactivation in platelet concentrates: enhanced specificity of virus kill in the absence of shorter UVA wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Margolis-Nunno, Henrietta; Robinson, Richard; Horowitz, Bernard; Ben-Hur, Ehud [New York Blood Center, NY (United States); Geacintov, N.E. [New York Univ., NY (United States). Dept. of Chemistry

    1995-11-01

    Treatments with psoralens and long-wavelength ultraviolet radiation (UVA, 320-400 nm; PUVA) have shown efficacy for virus sterilization of platelet concentrates (PC). We have employed the psoralen derivative 4`-aminomethyl-4,5`,8-trimethylpsoralen (AMT), and have found that platelet integrity is best preserved when rutin, a flavonoid that quenches multiple reactive oxygen species, is present during AMT/UVA treatment of PC. In this report, we examine the effects of different UVA spectra under our standard PC treatment conditions (i.e. 50 {mu}g/mL AMT, 0.35 mM rutin and 38 J/cm{sup 2} UVA). Added vesicular stomatitis virus (VSV; {>=} 5.5 log{sub 10}) was completely inactivated with the simultaneous maintenance of the platelet aggregation response (> 90% of control) when a UVA light source with transmission mainly between 360 and 370 nm (narrow UVA1) was used. In contrast, with a broad-band UVA (320-400 nm; broad UVA) light source, the aggregation response was greatly compromised (< 50% of control) with only a minor increase in the rate of VSV kill. With this lamp, platelet function could be improved to about 75% of the control by adding a long-pass filter, which reduced the transmission of shorter ({<=} 345 nm) UVA wavelengths (340-400 nm; UVA1). At equivalent levels of virus kill, aggregation function was always best preserved when narrow UVA1 was used for PUVA treatment. Even in the absence of AMT, and with or without rutin present, narrow UVA1 irradiation was better tolerated by platelets than was broad UVA. (author).

  19. Evaluation of skin viability effect on ethosome and liposome-mediated psoralen delivery via cell uptake.

    Science.gov (United States)

    Zhang, Yong-Tai; Shen, Li-Na; Wu, Zhong-Hua; Zhao, Ji-Hui; Feng, Nian-Ping

    2014-10-01

    This study investigated the effect of skin viability on its permeability to psoralen delivered by ethosomes, as compared with liposomes. With decreasing skin viability, the amount of liposome-delivered psoralen that penetrated through the skin increased, whereas skin deposition of psoralen from both ethosomes and liposomes reduced. Psoralen delivery to human-immortalized epidermal cells was more effective using liposomes, whereas delivery to human embryonic skin fibroblast cells was more effective when ethosomes were used. These findings agreed with those of in vivo studies showing that skin psoralen deposition from ethosomes and liposomes first increased and then plateaued overtime, which may indicate gradual saturation of intracellular drug delivery. It also suggested that the reduced deposition of ethosome- or liposome-delivered psoralen in skin with reduced viability may relate to reduced cellular uptake. This work indicated that the effects of skin viability should be taken into account when evaluating nanocarrier-mediated drug skin permeation. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  20. Psoralen-deoxyribonucleic acid photoreaction. Characterization of the monoaddition products from 8-methoxypsoralen and 4,5',8-trimethylpsoralen

    Energy Technology Data Exchange (ETDEWEB)

    Kanne, D.; Straub, K.; Rapoport, H.; Hearst, J.E.

    1982-01-01

    The isolation and structural characterization are described of the major monoaddition products formed in the photoreaction of two naturally occurring psoralens, 8-methoxypsoralen and 4,5',8-trimethylpsoralen, with high molecular weight, double-stranded DNA. Hydrolysis of the psoralen-modified DNA and subsequent chromatography resulted in the isolation of four modified nucleosides from each psoralen. Structural characterization was accomplished by mass spectrometry and /sup 1/H NMR analysis. The major products, accounting for 44 to 52% of the covalently bound psoralen, are two diastereomeric thymidine adducts formed by cycloaddition between the 5,6 double bond of the pyrimidine and the 4',5' (furan) double bond of the psoralen. All of the isolated adducts have cis-syn stereochemistry. The stereochemistry and product distribution of the adducts are determined in part by the constraints imposed by the DNA helix on the geometry of the noncovalent intercalation complex formed by psoralen and DNA prior to irradiation.

  1. Potential of ultraviolet widefield imaging and multiphoton microscopy for analysis of dehydroergosterol in cellular membranes

    DEFF Research Database (Denmark)

    Wüstner, Daniel; Brewer, Jonathan R.; Bagatolli, Luis

    2011-01-01

    ) excitation microscopy to monitor DHE in living cells. Significantly reduced photobleaching in MP microscopy of DHE enabled us to acquire three-dimensional z-stacks of DHE-stained cells and to obtain high-resolution maps of DHE in surface ruffles, nanotubes, and the apical membrane of epithelial cells. We......Dehydroergosterol (DHE) is an intrinsically fluorescent sterol with absorption/emission in the ultraviolet (UV) region and biophysical properties similar to those of cholesterol. We compared the potential of UV-sensitive low-light-level wide-field (UV-WF) imaging with that of multiphoton (MP...... be resolved by MP time-lapse microscopy. Diffusion coefficients of 0.25-μm-diameter endocytic vesicles containing DHE were determined by MP spatiotemporal image correlation spectroscopy. The requirement of extremely high laser power for visualization of DHE by MP microscopy made this method less potent...

  2. Assessing the effects of ultraviolet radiation on the photosynthetic potential in Archean marine environments

    Science.gov (United States)

    Avila-Alonso, Dailé; Baetens, Jan M.; Cardenas, Rolando; de Baets, Bernard

    2017-07-01

    In this work, the photosynthesis model presented by Avila et al. in 2013 is extended and more scenarios inhabited by ancient cyanobacteria are investigated to quantify the effects of ultraviolet (UV) radiation on their photosynthetic potential in marine environments of the Archean eon. We consider ferrous ions as blockers of UV during the Early Archean, while the absorption spectrum of chlorophyll a is used to quantify the fraction of photosynthetically active radiation absorbed by photosynthetic organisms. UV could have induced photoinhibition at the water surface, thereby strongly affecting the species with low light use efficiency. A higher photosynthetic potential in early marine environments was shown than in the Late Archean as a consequence of the attenuation of UVC and UVB by iron ions, which probably played an important role in the protection of ancient free-floating bacteria from high-intensity UV radiation. Photosynthetic organisms in Archean coastal and ocean environments were probably abundant in the first 5 and 25 m of the water column, respectively. However, species with a relatively high efficiency in the use of light could have inhabited ocean waters up to a depth of 200 m and show a Deep Chlorophyll Maximum near 60 m depth. We show that the electromagnetic radiation from the Sun, both UV and visible light, could have determined the vertical distribution of Archean marine photosynthetic organisms.

  3. Probing the binding mode of psoralen to calf thymus DNA.

    Science.gov (United States)

    Zhou, Xiaoyue; Zhang, Guowen; Wang, Langhong

    2014-06-01

    The binding properties between psoralen (PSO) and calf thymus DNA (ctDNA) were predicted by molecular docking, and then determined with the use of UV-vis absorption, fluorescence, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy, coupled with DNA melting and viscosity measurements. The data matrix obtained from UV-vis spectra was resolved by multivariate curve resolution-alternating least squares (MCR-ALS) approach. The pure spectra and the equilibrium concentration profiles for PSO, ctDNA and PSO-ctDNA complex extracted from the highly overlapping composite response were obtained simultaneously to evaluate the PSO-ctDNA interaction. The intercalation mode of PSO binding to ctDNA was supported by the results from the melting studies, viscosity measurements, iodide quenching and fluorescence polarization experiments, competitive binding investigations and CD analysis. The molecular docking prediction showed that the specific binding most likely occurred between PSO and adenine bases of ctDNA. FT-IR spectra studies further confirmed that PSO preferentially bound to adenine bases, and this binding decreased right-handed helicity of ctDNA and enhanced the degree of base stacking with the preservation of native B-conformation. The calculated thermodynamic parameters indicated that hydrogen bonds and van der Waals forces played a major role in the binding process. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Psoralen Inactivation of Viruses: A Process for the Safe Manipulation of Viral Antigen and Nucleic Acid

    Directory of Open Access Journals (Sweden)

    Katherine Schneider

    2015-11-01

    Full Text Available High consequence human pathogenic viruses must be handled at biosafety level 2, 3 or 4 and must be rendered non-infectious before they can be utilized for molecular or immunological applications at lower biosafety levels. Here we evaluate psoralen-inactivated Arena-, Bunya-, Corona-, Filo-, Flavi- and Orthomyxoviruses for their suitability as antigen in immunological processes and as template for reverse transcription PCR and sequencing. The method of virus inactivation using a psoralen molecule appears to have broad applicability to RNA viruses and to leave both the particle and RNA of the treated virus intact, while rendering the virus non-infectious.

  5. The RecQ helicase RECQL5 participates in psoralen-induced interstrand cross-link repair

    Science.gov (United States)

    Bohr, Vilhelm A.

    2013-01-01

    Interstrand cross-links (ICLs) are very severe lesions as they are absolute blocks of replication and transcription. This property of interstrand cross-linking agents has been exploited clinically for the treatment of cancers and other diseases. ICLs are repaired in human cells by specialized DNA repair pathways including components of the nucleotide excision repair pathway, double-strand break repair pathway and the Fanconi anemia pathway. In this report, we identify the role of RECQL5, a member of the RecQ family of helicases, in the repair of ICLs. Using laser-directed confocal microscopy, we demonstrate that RECQL5 is recruited to ICLs formed by trioxalen (a psoralen-derived compound) and ultraviolet irradiation A. Using single-cell gel electrophoresis and proliferation assays, we identify the role of RECQL5 in the repair of ICL lesions. The domain of RECQL5 that recruits to the site of ICL was mapped to the KIX region between amino acids 500 and 650. Inhibition of transcription and of topoisomerases did not affect recruitment, which was inhibited by DNA-intercalating agents, suggesting that the DNA structure itself may be responsible for the recruitment of RECQL5 to the sites of ICLs. PMID:23715498

  6. Targeted gene correction using psoralen, chlorambucil and camptothecin conjugates of triplex forming peptide nucleic acid (PNA)

    DEFF Research Database (Denmark)

    Birkedal, Henrik; Nielsen, Peter E

    2011-01-01

    Gene correction activation effects of a small series of triplex forming peptide nucleic acid (PNA) covalently conjugated to the DNA interacting ligands psoralen, chlorambucil and camptothecin targeted proximal to a stop codon mutation in an EGFP reporter gene were studied. A 15-mer homopyrimidine...

  7. Isolation and purification of psoralen and isopsoralen and their efficacy and safety in the treatment of osteosarcoma in nude rats.

    Science.gov (United States)

    Lu, Honghui; Zhang, Lihai; Liu, Daohong; Tang, Peifu; Song, Feixiang

    2014-09-01

    Modern studies have shown that psoralen has a significant inhibitory effect on tumor growth in a variety of animals and humans. To obtain coumarin compounds - psoralen and isopsoralen - from traditional Chinese medicine Psoralea corylifolia L. using chromatographic techniques and isolation and purification methods, and to observe the transplanted tumor growth inhibitory effects and adverse reactions of psoralen and isopsoralen in nude rats with osteosarcoma. Dried ripe fruits of Psoralea corylifolia L. were taken as the raw material to prepare crude extract of Psoralea corylifolia L. by ethanol reflux method. Column chromatography was used to isolate the crude extract; compounds were structurally identified based on (1)H-NMR, (13)C-NMR spectra, the two compounds were identified as psoralen andisopsoralen, and their contents were 99.7% and 99.6, respectively. Nude rat model of osteosarcoma was established; the rats were randomized into: normal saline group, psoralen low- and high-dose groups, isopsoralen low- and high-dose groups, and cisplatin group. Osteosarcoma volume and weight inhibition rates in nude rats in each group were observed; radioimmunoassay was used to determine the serum alkaline phosphatase activity; peripheral blood cell and bone marrow nucleated cell counts were determined; light microscopy was used to observe heart, liver, spleen, lung, kidney, and tumor histopathology; and electron microscopy was used to observe the fine structure of tumor cells. Tumor volume inhibition rates were 43.75% and 40.18%, respectively, in the psoralen and isopsoralen low-dose groups, and tumor weight inhibition rates were 38.83% and 37.77%. Tumor volume inhibition rates were 67.86% and 66.96%, respectively, in the psoralen and isopsoralen high-dose groups, and tumor weight inhibition rates were 49.47% and 47.87%. Psoralen and ispsoralen markedly lowered serum AKP level. Psoralen and isopsoralen induced apoptosis or necrosis of osteosarcoma. After administration of

  8. Effects of long-term ultraviolet radiation: the white form of Metridium senile (Anthozoa: Actiniaria) as a potential biological indicator for ultraviolet

    Science.gov (United States)

    Westholt, R.; Kestler, P.; Sicken, O.; Westheide, W.

    2001-03-01

    Genetically identical individuals of the white form of Metridium senile were kept in the laboratory for 40 months, during almost 2 years of which they were irradiated with ultraviolet (UV) radiation simulating the shape of the solar UV spectrum. The living and experimental conditions were largely matched to the conditions in the sea anemones' natural habitat on the North Sea coast. Controls were shielded from direct radiation or irradiated with only the visible range of the spectrum; for the UV tests, the UV component corresponded either to the conditions in the natural habitat or to twice or 4 times this dose. All experiments were preceded by a several-month settling-in period, and UV irradiation was always begun at a low intensity. Under these conditions UV was not lethal but produced many parameter changes, of which only those that were irreversible for the entire duration of the experiment, from September 1992 to August 1994, are described here. The body mass fell significantly in all three UV-radiation modes. All irradiated animals positioned themselves so as to be less exposed to the radiation, and all changed colour from white to brown. These responses are discussed with reference to the potential of M. senile as an indicator or monitor for UV in the northern European coastal region. Field analyses are currently being conducted to demonstrate the extent to which the present results apply to field conditions.

  9. UVB-activated psoralen reduces luminal narrowing after balloon dilation because of inhibition of constrictive remodeling

    NARCIS (Netherlands)

    Perrée, Jop; van Leeuwen, Ton G.; Velema, Evelyn; Smeets, Mirjam; de Kleijn, Dominique; Borst, Cornelius

    2002-01-01

    In this study we have explored the potential of PUVB (8-MOP + UVB) therapy for the reduction of luminal narrowing after arterial injury. In 15 rabbits, balloon dilation of iliac arteries was performed. In 20 arteries, dilation was combined with the delivery of pulsed ultraviolet light B (UVB)

  10. Potential effects of ultraviolet radiation reduction on tundra nitrous oxide and methane fluxes in maritime Antarctica.

    Science.gov (United States)

    Bao, Tao; Zhu, Renbin; Wang, Pei; Ye, Wenjuan; Ma, Dawei; Xu, Hua

    2018-02-27

    Stratospheric ozone has begun to recover in Antarctica since the implementation of the Montreal Protocol. However, the effects of ultraviolet (UV) radiation on tundra greenhouse gas fluxes are rarely reported for Polar Regions. In the present study, tundra N 2 O and CH 4 fluxes were measured under the simulated reduction of UV radiation in maritime Antarctica over the last three-year summers. Significantly enhanced N 2 O and CH 4 emissions occurred at tundra sites under the simulated reduction of UV radiation. Compared with the ambient normal UV level, a 20% reduction in UV radiation increased tundra emissions by an average of 8 μg N 2 O m -2 h -1 and 93 μg CH 4 m -2 h -1 , whereas a 50% reduction in UV radiation increased their emissions by an average of 17 μg N 2 O m -2 h -1 and 128 μg CH 4 m -2 h -1 . No statistically significant correlation (P > 0.05) was found between N 2 O and CH 4 fluxes and soil temperature, soil moisture, total carbon, total nitrogen, NO 3 - -N and NH 4 + -N contents. Our results confirmed that UV radiation intensity is an important factor affecting tundra N 2 O and CH 4 fluxes in maritime Antarctica. Exclusion of the effects of reduced UV radiation might underestimate their budgets in Polar Regions with the recovery of stratospheric ozone.

  11. Ultraviolet Waves

    Science.gov (United States)

    Molde, Trevor

    1973-01-01

    Outlines the discovery and nature of ultraviolet light, discusses some applications for these wavelengths, and describes a number of experiments with ultraviolet radiation suitable for secondary school science classes. (JR)

  12. Molecular analysis by electron microscopy of the removal of psoralen-photoinduced DNA cross-links in normal and Fanconi's anemia fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Rousset, S.; Nocentini, S.; Revet, B.; Moustacchi, E. (Institut Curie, Biologie, Paris (France))

    1990-04-15

    The induction and fate of psoralen-photoinduced DNA interstrand cross-links in the genome of Fanconi's anemia (FA) fibroblasts of complementation groups A and B, and of normal human fibroblasts, were investigated by quantitative analysis of totally denatured DNA fragments visualized by electron microscopy. 8-Methoxypsoralen (5 x 10(-5) M) interstrand cross-links were induced as a function of the near ultraviolet light dose. With time of postexposure incubation, a fraction of interstrand cross-links disappeared in all cell lines. However, 24 h after treatment, this removal was significantly lower in the two FA group A cell lines examined (34-39%) than in the FA group B and normal cell lines (43-53 and 47-57%, respectively). These data indicate that FA cells are at least able to recognize and incise interstrand cross-links, as normal cells do, although group A cells seem somewhat hampered in this process. This is in accord with data obtained on the same cell lines using another biochemical assay. Since the fate of cross-links in FA constituted a controversial matter, it is important to stress that two different methodologies applied to genetically well defined cell lines led to the same conclusions.

  13. NASA's Potential Contributions for Remediation of Retention Ponds Using Solar Ultraviolet Radiation and Photocatalysis

    Science.gov (United States)

    Underwood, Lauren W.; Ryan, Robert E.

    2007-01-01

    This Candidate Solution uses NASA Earth science research on atmospheric ozone and aerosols data (1) to help improve the prediction capabilities of water runoff models that are used to estimate runoff pollution from retention ponds, and (2) to understand the pollutant removal contribution and potential of photocatalytically coated materials that could be used in these ponds. Models (the EPA's SWMM and the USGS SLAMM) exist that estimate the release of pollutants into the environment from storm-water-related retention pond runoff. UV irradiance data acquired from the satellite mission Aura and from the OMI Surface UV algorithm will be incorporated into these models to enhance their capabilities, not only by increasing the general understanding of retention pond function (both the efficacy and efficiency) but additionally by adding photocatalytic materials to these retention ponds, augmenting their performance. State and local officials who run pollution protection programs could then develop and implement photocatalytic technologies for water pollution control in retention ponds and use them in conjunction with existing runoff models. More effective decisions about water pollution protection programs could be made, the persistence and toxicity of waste generated could be minimized, and subsequently our natural water resources would be improved. This Candidate Solution is in alignment with the Water Management and Public Health National Applications.

  14. Orally administered Polypodium leucotomos extract decreases psoralen-UVA-induced phototoxicity, pigmentation, and damage of human skin

    NARCIS (Netherlands)

    Middelkamp-Hup, Maritza A.; Pathak, Madhu A.; Parrado, Concepcion; Garcia-Caballero, Tomas; Rius-Díaz, Francisca; Fitzpatrick, Thomas B.; González, Salvador

    2004-01-01

    BACKGROUND: The use of psoralen-UVA (PUVA) in patients of skin phototype I to II is limited by side effects of acute phototoxicity and possible long-term carcinogenesis. OBJECTIVE: We sought to assess oral Polypodium leucotomos (PL) extract in decreasing PUVA-induced phototoxicity of human skin on a

  15. Effects of 8-methoxypsoralen and ultraviolet light A on EGF receptor (HER-1) expression.

    Science.gov (United States)

    Yang, X Y; Ronai, Z A; Santella, R M; Weinstein, I B

    1988-12-15

    Activation of psoralens by ultraviolet light irradiation at 308-400 nm (UVA) is used in the photochemical treatment of psoriasis. While the major effect of this activation is the formation of DNA adducts, it was recently demonstrated that psoralens can also bind to specific saturable high affinity cellular receptors, and that this is associated with inhibition of epidermal growth factor (EGF)-receptor binding. In view of these findings, we have examined whether 8-methoxy-psoralen (8-MOP) itself, or in combination with UVA, influences expression of the human EGF-receptor gene ("HER-1") in a human keratinocyte cell line. We have found that 8 MOP alone, and to a lesser extent UVA, induce a striking increase in cellular levels of HER-1 RNA. The combination of 8-MOP with UVA produces less induction of HER-1 RNA than that obtained with 8-MOP alone. We suggest, therefore, that this effect of 8-MOP is not due to DNA damage, but may reflect a separate effect of this compound on receptor-mediated signal transduction.

  16. NASA's Potential Contributions for Using Solar Ultraviolet Radiation in Conjunction with Photocatalysis for Urban Air Pollution Mitigation

    Science.gov (United States)

    Ryan, robert E.; Underwood, Lauren W.

    2007-01-01

    More than 75 percent of the U.S. population lives in urban communities where people are exposed to levels of smog or pollution that exceed the EPA (U.S. Environmental Protection Agency) safety standards. Urban air quality presents a unique problem because of a number of complex variables, including traffic congestion, energy production, and energy consumption activities, all of which can contribute to and affect air pollution and air quality in this environment. In environmental engineering, photocatalysis is an area of research whose potential for environmental clean-up is rapidly developing popularity and success. Photocatalysis, a natural chemical process, is the acceleration of a photoreaction in the presence of a catalyst. Photocatalytic agents are activated when exposed to near UV (ultraviolet) light (320-400 nm) and water. In recent years, surfaces coated with photocatalytic materials have been extensively studied because pollutants on these surfaces will degrade when the surfaces are exposed to near UV light. Building materials, such as tiles, cement, glass, and aluminum sidings, can be coated with a thin film of a photocatalyst. These coated materials can then break down organic molecules, like air pollutants and smog precursors, into environmentally friendly compounds. These surfaces also exhibit a high affinity for water when exposed to UV light. Therefore, not only are the pollutants decomposed, but this superhydrophilic nature makes the surface self-cleaning, which helps to further increase the degradation rate by allowing rain and/or water to wash byproducts away. According to the Clean Air Act, each individual state is responsible for implementing prevention and regulatory programs to control air pollution. To operate an air quality program, states must adopt and/or develop a plan and obtain approval from the EPA. Federal approval provides a means for the EPA to maintain consistency among different state programs and ensures that they comply with the

  17. Using Limes and Synthetic Psoralens to Enhance Solar Disinfection of Water (SODIS): A Laboratory Evaluation with Norovirus, Escherichia coli, and MS2

    OpenAIRE

    Harding, Alexander S.; Schwab, Kellogg J.

    2012-01-01

    We investigated the use of psoralens and limes to enhance solar disinfection of water (SODIS) using an UV lamp and natural sunlight experiments. SODIS conditions were replicated using sunlight, 2 L polyethylene terephthalate (PET) bottles, and tap water with Escherichia coli, MS2 bacteriophage, and murine norovirus (MNV). Psoralens and lime acidity both interact synergistically with UV radiation to accelerate inactivation of microbes. Escherichia coli was ablated > 6.1 logs by SODIS + Lime Sl...

  18. Dermal toxicity of 8-methoxypsoralen administered (by gavage) to hairless mice irradiated with long-wave ultraviolet light

    Energy Technology Data Exchange (ETDEWEB)

    Langner, A.; Wolska, H.; Marzulli, F.N.; Jablonska, S.; Jarzabek-Chorzelska, M.; Glinski, W.; Pawinska, M.

    1977-11-01

    Hairless mice were administered various amounts of 8-methoxypsoralen (8-MOP) by gavage, followed by irradiation with ultraviolet light (UVA) two or more times per week for periods ranging from 1 to 12 months. The minimum phototoxic dose was 20 mg/kg body weight by this route of administration and potential for serious organ toxicity in long-term exposures was investigated. No histologic features of cutaneous malignancy were encountered under test conditions which produced prolonged phototoxicity, deep ulceration, cicatrization, and other deformities. Repeated daily gavaged doses of 20 mg psoralen/Kg body weight in conjunction with twice weekly irradiation for 10 min with UVA elicited an erythematous phototoxic reaction, but did not give rise to subsequent skin lesions. 8-MOP in repeated daily gavage doses of 30 mg and 40 mg/kg body weight combined with twice weekly UVA irradiation for 10 min caused severe burning with subsequent scarring, but did not induce malignant tumors in experiments lasting 8 months. No organ toxicity was seen except for toxic liver changes when severe cutaneous burn and pronounced ulcerations were produced. Limited immunologic studies disclosed no abnormalities in this system.

  19. Rescue of Mitomycin C- or Psoralen-Inactivated Micrococcus Radiodurans by Additional Exposure to Radiation or Alkylating Agents

    DEFF Research Database (Denmark)

    Hansen, M. Trier

    1982-01-01

    The processing of damaged DNA was altered in a mitomycin C-sensitive mutant (mtcA) of Micrococcus radiodurans. Even though the mutant retained resistance to 254-nm UV radiation, it did not, in contrast to the wild-type strain, show any excessive DNA degradation or cell death when incubated...... in the mtcA background. In this strain, additional damage infficted upon the cellular DNA effected a massive rescue of cells previously inactivated by mitomycin C. Rescue was provoked by ionizing radiation, by UV light, or by simple alkylating agents. Cells treated with psoralen plus near-UV radiation could...... interstrand cross-links produced by mitomycin C or psoralen plus near-UV light, but induced only by the more abundant number of damages produced by radiation or simple alkylating agents....

  20. Ultraviolet and visible light penetration of epidermis

    Energy Technology Data Exchange (ETDEWEB)

    Eggset, G.; Kavli, G.; Volden, G. (Tromsoe Univ. (Norway). Dept. of Dermatology); Krokan, H. (Tromsoe Univ. (Norway). Inst. of Medical Biology)

    1984-10-01

    Light penetration in untanned skin and skin tanned with UVB (middlewave ultraviolet light) or PUVA (Psoralen photochemotherapy) was compared. Transmission at different wavelengths was measured through sheets of intact epidermis isolated by a suction blister technique. Thick epidermis was collected from a newly formed palmar friction bulla. For these studies a monochromator was used and the range of wavelengths examined was 280-700 nm. The transmission was considerably lower in tanned skin and the difference was most pronounced in the UV range. In the UVB range (290-320 nm), transmission was 13-43% for untanned epidermis, 8-12% for UVB tanned and slightly lower for PUVA tanned epidermis. At wavelengths below 325 nm only a few per cent of light penetrate through thick palmar epidermis. Both UVB and PUVA induce increased melanin content and thickening of the epidermis. Our results indicate that melanin is the most efficient protection against UVA while thickening of epidermis may be as important as the increased melanin content for the protection of living basal cells against the harmful UVB rays.

  1. The direct observation of a psoralen-thymine UVA induced solid-state cycloaddition reaction product by single-crystal x-ray diffractometry.

    Science.gov (United States)

    Pfluger, C E; Ostrander, R L

    1989-04-01

    Single-crystal x-ray diffraction methods have been used to directly observe and simultaneously determine the molecular structure of the UVA induced cis-syn photocycloaddition product in a partially photolyzed single crystal of a psoralen(pyrone ring side)-DNA(thymine) interaction model compound, 1'-(8-oxypsoralen)-8'(thym-1"yl)3',6'-dioxaoctane.

  2. Peroxide scavenging potential of ultraviolet-B-absorbing mycosporine-like amino acids isolated from a marine red alga Bryocladia sp.

    Directory of Open Access Journals (Sweden)

    Vinod K Kannaujiya

    2014-06-01

    Full Text Available Ultraviolet-B (UV-B; 280-315 nm-absorbing mycosporine-like amino acids (MAAs were extracted and purified from a marine red alga Bryocladia sp. by using high performance liquid chromatography. We have detected four MAAs having retention times 3.23, 2.94, 3.56 and 2.67 min with absorbance maxima (λmax at 323, 328, 335 and 340 nm respectively. The effect of UV-B on the induction of these MAAs was studied. In comparison to control, there was 3 - 22 % induction of MAAs after 12 and 24 h of UV-B exposure. Apart from MAAs, other pigments such as chl a, carotenoids and total proteins were inversely affected by UV-B irradiation. In addition, peroxide scavenging potential of these MAAs were also investigated. With 2 mM hydrogen peroxide (H2O2 concentration, only <5 % of MAAs were found to be affected. However, with the increased H2O2, 40-60 % decline in the MAAs concentration with a corresponding peak shifting towards the blue wavelength was recorded. In addition, most of the MAAs were found to be reacting slowly with increasing H2O2 (upto 10 mM concentration after an incubation period of 5 and 30 min, which indicates the remarkable scavenging potential and stability of MAAs against oxidative stress. Thus, the isolated MAAs from marine red alga Bryocladia sp. may act as an efficient peroxide scavenger.

  3. Effects of salinity and temperature on inactivation and repair potential of Enterococcus faecalis following medium- and low-pressure ultraviolet irradiation.

    Science.gov (United States)

    Chen, P-Y; Chu, X-N; Liu, L; Hu, J-Y

    2016-03-01

    To investigate the medium-pressure (MP) and low-pressure (LP) Ultraviolet (UV) susceptibility and the repair potential of Enterococcus faecalis (DSM 20478) after UV treatment. A range of UV doses from 4 to 19 mJ cm(-2) was selected in this study. Photoreactivation and dark repair performance were investigated under fluorescent light or in the dark respectively. The inactivation and repair performance of UV disinfection under a range of salinities (0, 1%, 3%) and temperature (4 and 25°C) were compared. Results indicated that MP UV exposure resulted in higher inactivation efficiency against Ent. faecalis than LP UV exposure. For repair potential, LP UV resulted in a greater level of light repair than MP UV. Effect of salinity on the inactivation and repair of Ent. faecalis was correlated with UV sources, whereas low temperature generally adversely affected the inactivation efficiency and final repair levels after both MP and LP UV exposure. Both salinity and temperature demonstrated to play an important role in the inactivation and repair capability when UV light was used to treat ballast water. Considering that UV-treated ballast water is exposed or discharged to marine water environment in many countries with various temperature and salinity conditions, results of this study provide significant implications for the management of public health associated with ballast water treatment and discharge. © 2015 The Society for Applied Microbiology.

  4. Inactivated human platelet lysate with psoralen: a new perspective for mesenchymal stromal cell production in Good Manufacturing Practice conditions.

    Science.gov (United States)

    Castiglia, Sara; Mareschi, Katia; Labanca, Luciana; Lucania, Graziella; Leone, Marco; Sanavio, Fiorella; Castello, Laura; Rustichelli, Deborah; Signorino, Elena; Gunetti, Monica; Bergallo, Massimiliano; Bordiga, Anna Maria; Ferrero, Ivana; Fagioli, Franca

    2014-06-01

    Mesenchymal stromal cells (MSC) are ideal candidates for regenerative and immunomodulatory therapies. The use of xenogeneic protein-free Good Manufacturing Practice-compliant growth media is a prerequisite for clinical MSC isolation and expansion. Human platelet lysate (HPL) has been efficiently implemented into MSC clinical manufacturing as a substitute for fetal bovine serum (FBS). Because the use of human-derived blood materials alleviates immunologic risks but not the transmission of blood-borne viruses, the aim of our study was to test an even safer alternative than HPL to FBS: HPL subjected to pathogen inactivation by psoralen (iHPL). Bone marrow samples were plated and expanded in α-minimum essential medium with 10% of three culture supplements: HPL, iHPL and FBS, at the same time. MSC morphology, growth and immunophenotype were analyzed at each passage. Karyotype, tumorigenicity and sterility were analyzed at the third passage. Statistical analyses were performed. The MSCs cultivated in the three different culture conditions showed no significant differences in terms of fibroblast colony-forming unit number, immunophenotype or in their multipotent capacity. Conversely, the HPL/iHPL-MSCs were smaller, more numerous, had a higher proliferative potential and showed a higher Oct-3/4 and NANOG protein expression than did FBS-MSCs. Although HPL/iHPL-MSCs exhibit characteristics that may be attributable to a higher primitive stemness than FBS-MSCs, no tumorigenic mutations or karyotype modifications were observed. We demonstrated that iHPL is safer than HPL and represents a good, Good Manufacturing Practice-compliant alternative to FBS for MSC clinical production that is even more advantageous in terms of cellular growth and stemness. Copyright © 2014 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

  5. Altmetric: 165More detailArticle | OPENClimate change-induced increases in precipitation are reducing the potential for solar ultraviolet radiation to inactivate pathogens in surface waters

    Science.gov (United States)

    Climate change is accelerating the release of dissolved organic matter (DOM) to inland and coastal waters through increases in precipitation, thawing of permafrost, and changes in vegetation. Our modeling approach suggests that the selective absorption of ultraviolet radiation (U...

  6. Using limes and synthetic psoralens to enhance solar disinfection of water (SODIS): a laboratory evaluation with norovirus, Escherichia coli, and MS2.

    Science.gov (United States)

    Harding, Alexander S; Schwab, Kellogg J

    2012-04-01

    We investigated the use of psoralens and limes to enhance solar disinfection of water (SODIS) using an UV lamp and natural sunlight experiments. SODIS conditions were replicated using sunlight, 2 L polyethylene terephthalate (PET) bottles, and tap water with Escherichia coli, MS2 bacteriophage, and murine norovirus (MNV). Psoralens and lime acidity both interact synergistically with UV radiation to accelerate inactivation of microbes. Escherichia coli was ablated > 6.1 logs by SODIS + Lime Slurry and 5.6 logs by SODIS + Lime Juice in 30-minute solar exposures, compared with a 1.5 log reduction with SODIS alone (N = 3; P 3.9 logs by SODIS + Lime Slurry, 1.9 logs by SODIS + Lime Juice, and 1.4 logs by SODIS in 2.5-hour solar exposures (N = 3; P SODIS, with SODIS against human norovirus should be investigated further.

  7. Allelism of Saccharomyces cerevisiae gene PSO10, involved in error-prone repair of psoralen-induced DNA damage, with SUMO ligase-encoding MMS21.

    Science.gov (United States)

    Hoch, Nícolas C; Santos, Rafael S; Rosa, Renato M; Machado, Roseane M; Saffi, Jenifer; Brendel, Martin; Henriques, João A P

    2008-06-01

    In order to extend the understanding of the genetical and biochemical basis of photo-activated psoralen-induced DNA repair in the yeast Saccharomyces cerevisiae we have identified and cloned 10 pso mutants. Here, we describe the phenotypic characterization and molecular cloning of the pso10-1 mutant which is highly sensitive to photoactivated psoralens, UV(254) (nm) radiation and the alkylating agent methylmethane sulphonate. The pso10-1 mutant allele also confers a block in the mutagenic response to photoactivated psoralens and UV(254) (nm) radiation, and homoallelic diploids do not sporulate. Molecular cloning using a yeast genomic library, sequence analysis and genetic complementation experiments proved pso10-1 to be a mutant allele of gene MMS21 that encodes a SUMO ligase involved in the sumoylation of several DNA repair proteins. The ORF of pso10-1 contains a single nucleotide C-->T transition at position 758, which leads to a change in amino acid sequence from serine to phenylalanine [S253F]. Pso10-1p defines a leaky mutant phenotype of the essential MMS21 gene, and as member of the Smc5-Smc6 complex, still has some essential functions that allow survival of the mutant. DNA repair via translesion synthesis is severely impaired as the pso10-1 mutant allele confers severely blocked induced forward and reverse mutagenesis and shows epistatic interaction with a rev3Delta mutant allele. By identifying the allelism of PSO10 and MMS21 we demonstrate the need of a fully functional Smc5-Smc6 complex for a WT-like adequate repair of photoactivated psoralen-induced DNA damage in yeast.

  8. SU-E-T-93: Activation of Psoralen at Depth Using Kilovoltage X-Rays: Physics Considerations in Implementing a New Teletherapy Paradigm

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, J; Yoon, P; Liu, L; Alcorta, D; Spector, N; Oldham, M [Duke University Medical Center, Durham, NC (United States); Nolan, M; Gieger, T [North Carolina State University, Raleigh, NC (United States); Walder, H; Fathi, Z; Beyer, W [Immunolight LLC, Detroit, MI (United States)

    2015-06-15

    Purpose: Psoralen is a UV-light activated anti-cancer biotherapeutic used for treating skin lesions (PUVA) and advanced cutaneous T-cell lymphoma (ECP). To date psoralen has not been used to treat deep seated tumors due to difficulty in generating UV-light at depth. We recently demonstrated psoralen activation at depth by introducing energy converting particles that absorb kV x-ray radiation and re-emit UV-light. Our in-vitro work found that 0.2–1Gy using 40–100kVp x-rays combined with psoralen and particles can induce a substantial apoptotic response beyond that expected from the sum of individual components. In preparation for a phase I clinical trial of canine companion animals, we address the physics and dosimetry considerations for applying this new teletherapy paradigm to an in-vivo setting. Methods: The kV on-board imaging (OBI) system mounted on a medical linear accelerator (Varian) was commissioned to deliver the prescribed dose (0.6Gy) using 80 and 100kVp. Dosimetric measurements included kVp, HVL, depth dose, backscatter factors, collimator and phantom scatter factors, field size factors, and blade leakage. Absolute dosimetry was performed following AAPM TG61 recommendations and verified with an independent kV dose meter. We also investigated collimated rotational delivery to minimize skin dose using simple dose calculations on homogeneous cylindrical phantoms. Results: Single beam delivery is feasible for shallow targets (<5cm) without exceeding skin tolerance, while a rotational delivery may be utilized for deeper targets; skin dose is ∼75% of target dose for 80kVp collimated rotational delivery to a 3cm target within a 20cm phantom. Heat loading was tolerable; 0.6Gy to 5cm can be delivered before the anode reaches 75% capacity. Conclusion: KV teletherapy for Psoralen activation in deep seated tissue was successfully commissioned for a Varian OBI machine for use in a phase I clinical trial in canines. Future work will use Monte Carlo dosimetry to

  9. Effect of rutin on virus inactivation by AMT in combination with ultraviolet-A irradiation in platelet concentrates

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Yoshiko; Abe, Hideki; Ikebuchi, Kenji; Sekiguchi, Sadayoshi [Hokkaido Red Cross Blood Center, Sapporo (Japan)

    1999-10-01

    Treatment with psoralens and ultraviolet-A (UVA) irradiation have been found to be effective for virus sterilization of platelet concentrates (PCs). We report here a virus inactivation method using a combination of psoralen derivative 4'-aminomethyl-4,5', 8-trimethylpsoralen (AMT) and UVA irradiation (AMT/UVA). Further, we also investigated the effect of rutin, a radical scavenger, on the inactivation of vesicular stomatitis virus (VSV) as a model virus administered in PCs and platelet functions were investigated. Spiked VSV (about 5log{sub 10}) in PCs was inactivated by a combination of AMT (50 {mu}g/ml) and 5.2 J/cm{sup 2} UVA irradiation in the absence of rutin. To obtain equivalent levels of VSV kill in the presence of 0.35 mM rutin, treatment with 13.0 J/cm{sup 2} of UVA irradiation with AMT was performed. When PCs were treated under each condition in which 5log{sub 10} VSV was inactivated by AMT/UVA with or without rutin, platelet aggregation function was maintained for more than 80% of untreated platelets. These findings indicate that the presence of rutin during AMT/UVA treatment conferred no beneficial effect. In addition, overnight storage of PCs with AMT induced 40% loss of platelet aggregation in response to 10{mu}M ADP. The findings suggest that UVA irradiation is required immediately after the addition of AMT. (author)

  10. Ultraviolet Spectrophotometry

    Directory of Open Access Journals (Sweden)

    Shahabuddin N. Alvi

    2013-01-01

    Full Text Available Two simple, accurate, and precise UV derivative spectrophotometric methods for the simultaneous determination of Prasugrel and Aspirin in synthetic mixture form have been developed. The first method involves measurement of second order derivative spectra of Prasugrel and Aspirin. The zero crossing wavelengths 267.62 nm and 252.40 nm were selected for estimation of Prasugrel and Aspirin, respectively. In the second method, the first order derivatives of ratio spectra were calculated and used for the determination of Prasugrel and Aspirin by measuring the peak intensity at 268 nm and 290 nm, respectively. The methods were validated as per the ICH guideline Q2 (R1. Beer’s law is followed in the range of 5–45 μg/mL for Prasugrel and 25–150 μg/mL for Aspirin by second order derivative method and 6–22 μg/mL for Prasugrel and 45–165 μg/mL for Aspirin by ratio first order derivative method. The recovery studies confirmed the accuracy of the methods. Relative standard deviations for repeatability and inter- and intraday assays were less than 2%. Hence, the described derivative spectrophotometric methods are simple, accurate, precise, and excellent alternatives to sophisticated chromatographic techniques and can be potentially used for the simultaneous determination of Prasugrel and Aspirin in combined dosage form.

  11. Aluminum nanostructures for ultraviolet plasmonics

    Science.gov (United States)

    Martin, Jérôme; Khlopin, Dmitry; Zhang, Feifei; Schuermans, Silvère; Proust, Julien; Maurer, Thomas; Gérard, Davy; Plain, Jérôme

    2017-08-01

    An electromagnetic field is able to produce a collective oscillation of free electrons at a metal surface. This allows light to be concentrated in volumes smaller than its wavelength. The resulting waves, called surface plasmons can be applied in various technological applications such as ultra-sensitive sensing, Surface Enhanced Raman Spectroscopy, or metal-enhanced fluorescence, to name a few. For several decades plasmonics has been almost exclusively studied in the visible region by using nanoparticles made of gold or silver as these noble metals support plasmonic resonances in the visible and near-infrared range. Nevertheless, emerging applications will require the extension of nano-plasmonics toward higher energies, in the ultraviolet range. Aluminum is one of the most appealing metal for pushing plasmonics up to ultraviolet energies. The subsequent applications in the field of nano-optics are various. This metal is therefore a highly promising material for commercial applications in the field of ultraviolet nano-optics. As a consequence, aluminum (or ultraviolet, UV) plasmonics has emerged quite recently. Aluminium plasmonics has been demonstrated efficient for numerous potential applications including non-linear optics, enhanced fluorescence, UV-Surface Enhanced Raman Spectroscopy, optoelectronics, plasmonic assisted solid-state lasing, photocatalysis, structural colors and data storage. In this article, different preparation methods developed in the laboratory to obtain aluminum nanostructures with different geometries are presented. Their optical and morphological characterizations of the nanostructures are given and some proof of principle applications such as fluorescence enhancement are discussed.

  12. Increased prevalence of human papillomavirus in hairs plucked from patients with psoriasis treated with psoralen-UV-A.

    Science.gov (United States)

    Wolf, Peter; Seidl, Hannes; Bäck, Barbara; Binder, Barbara; Höfler, Gerald; Quehenberger, Franz; Hoffmann, Christine; Kerl, Helmut; Stark, Sabine; Pfister, Herbert J; Fuchs, Pawel G

    2004-03-01

    Patients with psoriasis treated with psoralen-UV-A (PUVA) are at increased risk of skin cancer; however, the exact causes of this increased incidence are not well understood. It has been suggested that PUVA may increase expression of the tumorigenic agent human papillomavirus (HPV) in skin by directly stimulating virus replication, immune suppression, or both, thereby leading to skin cancer formation. To determine whether HPV DNA prevalence in the skin is increased after long-term PUVA treatment. Screening for the presence of HPV sequences in DNA isolated from plucked body hairs of patients with psoriasis with a history of PUVA exposure and a history of skin cancer (group A), PUVA exposure and no history of skin cancer (group B), and no PUVA exposure and no history of skin cancer (group C). University hospital. Hair samples were obtained from 81 patients with psoriasis (56 men and 25 women; mean age, 52 years), including 16 in group A (mean number of PUVA exposures, 702), 35 in group B (mean number of PUVA exposures, 282), and 30 in group C. DNA was isolated from the hair samples and analyzed by polymerase chain reaction with the use of 2 nested primer systems specific for epidermodysplasia verruciformis-associated or related and genital or mucosal virus types, respectively. The rate of HPV DNA positivity was significantly higher in groups A (73% [11/15]) and B (69% [24/35]) than in group C (36% [10/28]) (A + B vs C, P =.009; chi(2) test; age adjusted). Conclusion The prevalence of HPV in the skin (hair follicles) is increased in patients with psoriasis who have a history of PUVA exposure.

  13. Mutant pso8-1 of Saccharomyces cerevisiae, sensitive to photoactivated psoralens, UV radiation, and chemical mutagens, contains a rad6 missense mutant allele.

    Science.gov (United States)

    Rolla, H; Grey, M; Schmidt, C L; Niegemann, E; Brendel, M; Henriques, J A P

    2002-07-01

    A novel mutant isolate of Saccharomyces cerevisiae, sensitive to photoactivated mono- and bi-functional psoralens, to UV at 254 nm (UVC), and to nitrosoguanidine, was found to complement the photoactivated psoralen-sensitivity phenotype conferred by the pso1- pso7 mutations and was therefore named pso8-1. A constructed pso8-1 rad4-4 double mutant was super-sensitive to UVC, thus indicating a synergistic interaction of the two mutant alleles. Molecular cloning via complementation of the pso8 mutant's sensitivity phenotype and genetic studies revealed that pso8 is allelic to RAD6. While a pso8-1 mutant had low mutagen-induced mutability, homoallelic diploids showed nearly wild-type sporulation. Sequence analysis of the mutant allele showed pso8-1 to contain a novel, hitherto undescribed T-->C transition in nucleotide position 191, leading to a substitution by leucine of a highly conserved proline at position 64, Rad6-[P64L], which may have severe consequences for the tertiary structure (and hence binding to Rad18p) of the mutant protein.

  14. Tumor necrosis factor-alpha-converting enzyme as a potential mediator of the influence of smoking on the response to treatment with narrowband ultraviolet B in psoriasis patients.

    Science.gov (United States)

    Serwin, Agnieszka Beata; Sokolowska, Marianna; Chodynicka, Bozena

    2010-02-01

    The aim of the study was to analyze the relationship between smoking and the treatment with narrowband ultraviolet B (NB-UVB) in psoriasis patients and to examine the role of the soluble tumor necrosis factor-alpha receptor type one (sTNF-R1) in plasma and that of TNF-alpha-converting enzyme (TACE) released from peripheral blood mononuclear cells (PBMC) in this relationship. The study has been conducted among 45 inpatients with plaque-type psoriasis vulgaris and 36 inpatients with other chronic inflammatory skin disorders from similar social background (controls). Taking into account the number of cigarettes smoked daily and the duration of smoking, subjects were classified as mild, moderate and heavy smokers. The severity of psoriasis was assessed using psoriasis area and severity index (PASI) score, concentrations of sTNF-R1 and TACE (expressed in ng/ml)--with quantitative sandwich enzyme immunoassays before (T(0)) and after 20 NB-UVB irradiations (T(20)). The pretreatment concentration of sTNF-R1 was 2.55+/-0.17 in patients and 1.79+/-0.13 in controls (Psmoking and with TACE concentration (R=0.50 and R=0.47, Ppredicting the response to the treatment with NB-UVB in smoking psoriasis patients. Smoking may adversely influence this treatment and TACE may be one of mediators in this influence.

  15. Alterations of nitric-oxide synthase and xanthine-oxidase activities of human keratinocytes by ultraviolet-B radiation -potential role for peroxynitrite in skin inflammation

    Energy Technology Data Exchange (ETDEWEB)

    Deliconstantinos, G.; Villiotou, V.; Stavrides, J.C. [Athens Univ. (Greece). School of Medicine

    1996-06-28

    In the present study, we demonstrated that NO synthase (cNOS) and xanthine oxidase (XO) of human keratinocytes can be activated to release NO, superoxide (O-2(-)) and peroxynitrite (ONOO-) following exposure to ultraviolet B (UVB) radiation. We defined that this photo induced response may be involved in the pathogenesis of sunburn erythema and inflammation. Treatment of human keratinocytes with UVB (290-320 nm) radiation (up to 200 mJ/cm(2)) resulted in a dose-dependent increase in NO and ONOO-release that was inhibited by N-monomethyl-L-arginine (L-NMMA). NO and ONOO- release from keratinocytes was accompanied by an increase in intracellular cGMP levels. Treatment of human keratinocyte cytosol with various doses of UVB (up to 100 mJ/cm(2)) resulted in an increase in XO activity that was inhibited by oxypurinol. In in vivo experiments, when experimental animals were subjected to UVB radiation, a protection factor (PF) of 6.5 {+-} 1.8 was calculated when an emulsified cream formulation containing nitro-L-arginine (L-NA) (2%) and L-NMMA (2%) was applied to their skin. The present study indicates that UVB radiation acts as a potent stimulator of cNOS and XO activities in human keratinocytes. NO and ONOO- may exert cytotoxic effects in keratinocytes themselves, as well as in their neighbouring endothelial and smooth muscle cells. This may be a major part of the integrated response leading to erythema production and the inflammation process. (UK).

  16. Nature and possible mechanisms of formation of potential mutations arising at emerging of thymine dimers after irradiation of double-stranded DNA by ultraviolet light

    Science.gov (United States)

    Grebneva, H. A.

    2003-01-01

    The mutagenesis under ultraviolet (UV)-irradiation is discussed. It is assumed, that the basic damages resulting in transitions, transversions, mutations of the frameshift and complex mutations are changes of the tautomeric state of the bases. The bases may be a part of dimers or may be not the dimer components. We consider such rare tautomeric states, which may influence the character of base pairing. A model of the formation of the above rare tautomeric forms of nucleotide bases under the UV-irradiation of the DNA is proposed. In the case of a radiation deexcitation of the DNA, which has absorbed the UV-quantum of the triplet energy level, there occur strong forced oscillations. They may result in changes of the lengths of hydrogen bonds between DNA bases. As a result, at H-bond shortening, the hydrogen atom may be almost in the center of H-bond. In the case of H-bond elongation, it may remain near the partner atom. Because of the H-bond breaking, during the formation of dimers, rare tautomeric forms of bases influencing the character of pairing can be realized. If a pair of the bases is not a part of dimer, then the only new stable configuration of the hydrogen atoms is the one that occurred at double-proton phototautomerism. It is shown that only those dimers are mutational, in which the change of a tautomeric state of the DNA bases have taken place. This is one of the differences between the proposed model and the standard one. The latter assumes, that from the point of view of ability of forming the mutations all the dimers are identical, and the DNA-polymerase is sometimes mistaken, incidentally building uncomplementary bases in. The consideration is only of qualitative character, it needs experimental verification, subsequent study by methods of quantum chemistry and theoretical physics. A list of problems to be studied in this respect is given.

  17. Psoriasis, Psoralen and Sunlight

    Directory of Open Access Journals (Sweden)

    R.P.C Naik

    1979-01-01

    Full Text Available Topical or oral administration of photoactive furocumarins followed by exposure to ultra violet light from artificial sources has been shown previously to clear psoriatic lesions. Sunlight has been chosen as the source of UVL m two separate paired comparison studies using topical and, oral 4,5, 8 trimethylpsoralen. Two out of 21 on topical therapy and none out of 6 patients on oral paired-comparison study showed faster clearance of the drug treated lesions compared to control sites.

  18. Ultraviolet radiation and immunosuppression.

    LENUS (Irish Health Repository)

    Murphy, G M

    2009-11-01

    Ultraviolet (UV) radiation is a complete carcinogen. The effects of UV radiation are mediated via direct damage to cellular DNA in the skin and suppression of image surveillance mechanisms. In the context of organ transplantation, addiction of drugs which suppress the immune system add greatly to the carcinogenicity of UV radiation. This review considers the mechanisms of such effects.

  19. Ultraviolet fire detector

    Science.gov (United States)

    Turnage, J. E.; Linford, R. M. F.; Cornish, S. D.

    1976-01-01

    System is capable of detecting ultraviolet light emitted by match size flame at distance of 10 ft. System is not affected by high energy or particulate radiation and is therefore particularly suited for applications around nuclear plants and X-ray equipment.

  20. Ultraviolet radiation therapy and UVR dose models.

    Science.gov (United States)

    Grimes, David Robert

    2015-01-01

    Ultraviolet radiation (UVR) has been an effective treatment for a number of chronic skin disorders, and its ability to alleviate these conditions has been well documented. Although nonionizing, exposure to ultraviolet (UV) radiation is still damaging to deoxyribonucleic acid integrity, and has a number of unpleasant side effects ranging from erythema (sunburn) to carcinogenesis. As the conditions treated with this therapy tend to be chronic, exposures are repeated and can be high, increasing the lifetime probability of an adverse event or mutagenic effect. Despite the potential detrimental effects, quantitative ultraviolet dosimetry for phototherapy is an underdeveloped area and better dosimetry would allow clinicians to maximize biological effect whilst minimizing the repercussions of overexposure. This review gives a history and insight into the current state of UVR phototherapy, including an overview of biological effects of UVR, a discussion of UVR production, illness treated by this modality, cabin design and the clinical implementation of phototherapy, as well as clinical dose estimation techniques. Several dose models for ultraviolet phototherapy are also examined, and the need for an accurate computational dose estimation method in ultraviolet phototherapy is discussed.

  1. Far ultraviolet instrument technology

    Science.gov (United States)

    Paxton, Larry J.; Schaefer, Robert K.; Zhang, Yongliang; Kil, Hyosub

    2017-02-01

    The far ultraviolet (FUV) spectral range (from about 115 nm to 180 nm) is one of the most useful spectral regions for characterizing the upper atmosphere (thermosphere and ionosphere). The principal advantages are that there are FUV signatures of the major constituents of the upper atmosphere as well as the signatures of the high-latitude energy inputs. Because of the absorption by thermospheric O2, the FUV signatures are seen against a "black" background, i.e., one that is not affected by ground albedo or clouds and, as a consequence, can make useful observations of the aurora during the day or when the Moon is above the horizon. In this paper we discuss the uses of FUV remote sensing, summarize the various techniques, and discuss the technological challenges. Our focus is on a particular type of FUV instrument, the scanning imaging spectrograph or SIS: an instrument exemplified by the Defense Meteorological Satellite Program Special Sensor Ultraviolet Imager and Thermosphere Ionosphere Mesosphere Energetics and Dynamics Global Ultraviolet Imager. The SIS combines spatial imaging of the disk with limb profiles as well as spectral information at each point in the scan.

  2. Reversed-phase high-performance Liquid Chromatography-ultraviolet Photodiode Array Detector Validated Simultaneous Quantification of six Bioactive Phenolic Acids in Roscoea purpurea Tubers and their In vitro Cytotoxic Potential against Various Cell Lines

    Science.gov (United States)

    Srivastava, Sharad; Misra, Ankita; Kumar, Dharmesh; Srivastava, Amit; Sood, Anil; Rawat, AKS

    2015-01-01

    Background: Roscoea purpurea or Roscoea procera Wall. (Zingiberaceae) is traditionally used for nutrition and in the treatment of various ailments. Objective: Simultaneous reversed-phase high-performance liquid chromatography-ultraviolet (RP-HPLC) photodiode array detector identification of phenolic acids (PA's) was carried out in whole extract of tuber and their cytotoxic potential was estimated along with radical scavenging action. Bioactivity guided fractionation was also done to check the response potential against the same assay. Materials and Methods: Identification and method validation was performed on RP-HPLC column and in vitro assays were used for bioactivity. Results: Protocatechuic acid, syringic acid, ferulic acid, rutin, apigenin, and kaempferol were quantified as 0.774%, 0.064%, 0.265%, 1.125%, 0.128%, and 0.528%, respectively. Validated method for simultaneous determination of PA's was found to be accurate, reproducible, and linearity was observed between peak area response and concentration. Recovery of identified PA's was within the acceptable limit of 97.40–104.05%. Significant pharmacological response was observed in whole extract against in vitro cytotoxic assay, that is, Sulforhodamine B assay, however, fractionation results in decreased action potential. Similar pattern of results were observed in the antioxidant assay, as total phenolic content and total flavonoid content were highest in whole extract and decreases with fractionation. Radical scavenging activity was prominent in chloroform fraction, exhibiting IC50 at 0.25 mg/mL. Conclusion: Study, thus, reveals that R. purpurea exhibit significant efficacy in cytotoxic activity with the potentiality of scavenging free radicals due the presence of PA's as reported through RP-HPLC. SUMMARY Proto-catechuic acid, syringic acid, ferulic acid, rutin, apigenin and kaempferol were quantified as 0.774, 0.064, 0.265, 1.125, 0.128 and 0.528 %Preliminary cytotoxic activity revealed that whole

  3. Ultraviolet Communication for Medical Applications

    Science.gov (United States)

    2015-06-01

    AWARD NUMBER: W81XWH-12-C-0043 TITLE: Ultraviolet Communication for Medical Applications PRINCIPAL INVESTIGATOR: Lee Cross CONTRACTING...5a. CONTRACT NUMBER W81XWH-12-C-0043 Ultraviolet Communication for Medical Applications 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...contains color. 14. ABSTRACT Under this Phase II SBIR effort, Directed Energy Inc.’s (DEI) proprietary ultraviolet (UV) emitters and the best

  4. Transparent ultraviolet photovoltaic cells.

    Science.gov (United States)

    Yang, Xun; Shan, Chong-Xin; Lu, Ying-Jie; Xie, Xiu-Hua; Li, Bing-Hui; Wang, Shuang-Peng; Jiang, Ming-Ming; Shen, De-Zhen

    2016-02-15

    Photovoltaic cells have been fabricated from p-GaN/MgO/n-ZnO structures. The photovoltaic cells are transparent to visible light and can transform ultraviolet irradiation into electrical signals. The efficiency of the photovoltaic cells is 0.025% under simulated AM 1.5 illumination conditions, while it can reach 0.46% under UV illumination. By connecting several such photovoltaic cells in a series, light-emitting devices can be lighting. The photovoltaic cells reported in this Letter may promise the applications in glass of buildings to prevent UV irradiation and produce power for household appliances in the future.

  5. Vacuum ultraviolet spectroscopy I

    CERN Document Server

    Samson, James A; Lucatorto, Thomas

    1998-01-01

    This volume is for practitioners, experimentalists, and graduate students in applied physics, particularly in the fields of atomic and molecular physics, who work with vacuum ultraviolet applications and are in need of choosing the best type of modern instrumentation. It provides first-hand knowledge of the state-of-the-art equipment sources and gives technical information on how to use it, along with a broad reference bibliography.Key Features* Aimed at experimentalists who are in need of choosing the best type of modern instrumentation in this applied field* Contains a detailed chapter on la

  6. Toward quantifying the abuse liability of ultraviolet tanning: A behavioral economic approach to tanning addiction.

    Science.gov (United States)

    Reed, Derek D; Kaplan, Brent A; Becirevic, Amel; Roma, Peter G; Hursh, Steven R

    2016-07-01

    Many adults engage in ultraviolet indoor tanning despite evidence of its association with skin cancer. The constellation of behaviors associated with ultraviolet indoor tanning is analogous to that in other behavioral addictions. Despite a growing literature on ultraviolet indoor tanning as an addiction, there remains no consensus on how to identify ultraviolet indoor tanning addictive tendencies. The purpose of the present study was to translate a behavioral economic task more commonly used in substance abuse to quantify the "abuse liability" of ultraviolet indoor tanning, establish construct validity, and determine convergent validity with the most commonly used diagnostic tools for ultraviolet indoor tanning addiction (i.e., mCAGE and mDSM-IV-TR). We conducted a between-groups study using a novel hypothetical Tanning Purchase Task to quantify intensity and elasticity of ultraviolet indoor tanning demand and permit statistical comparisons with the mCAGE and mDSM-IV-TR. Results suggest that behavioral economic demand is related to ultraviolet indoor tanning addiction status and adequately discriminates between potential addicted individuals from nonaddicted individuals. Moreover, we provide evidence that the Tanning Purchase Task renders behavioral economic indicators that are relevant to public health research. The present findings are limited to two ultraviolet indoor tanning addiction tools and a relatively small sample of high-risk ultraviolet indoor tanning users; however, these pilot data demonstrate the potential for behavioral economic assessment tools as diagnostic and research aids in ultraviolet indoor tanning addiction studies. © 2016 Society for the Experimental Analysis of Behavior.

  7. ULTRAVIOLET PROTECTIVE COMPOUNDS AS A RESPONSE TO ULTRAVIOLET RADIATION EXPOSURE

    Science.gov (United States)

    Life on Earth has evolved adaptations to many environmental stresses over the epochs. One consistent stress has been exposure to ultraviolet radiation. In response to UVR organisms have adapted myriad responses; behavioral, morphological and physiological. Behaviorally, some orga...

  8. 21 CFR 872.6350 - Ultraviolet detector.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultraviolet detector. 872.6350 Section 872.6350...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6350 Ultraviolet detector. (a) Identification. An ultraviolet detector is a device intended to provide a source of ultraviolet light which is used...

  9. Ultraviolet photovoltaics: Share the spectrum

    Science.gov (United States)

    Milliron, Delia J.

    2017-08-01

    Electrically controlled windows require power to switch between transparent and tinted states. Now, an ultraviolet light-harvesting solar cell can power smart windows without compromising their control over heat and light.

  10. Ultraviolet radiation in Finland

    Energy Technology Data Exchange (ETDEWEB)

    Taalas, P.; Koskela, T.; Damski, J.; Supperi, A. [Finnish Meteorological Inst., Helsinki (Finland). Section of Ozone and UV Research; Kyroe, E. [Finnish Meteorological Inst., Sodankylae (Finland). Sodankylae Observatory

    1996-12-31

    Solar ultraviolet radiation is damaging for living organisms due to its high energy pro each photon. The UV radiation is often separated into three regions according to the wavelength: UVC (200-280 nm), UVB (280-320 nm) and UVA (320-400 nm). The most hazardous part, UVC is absorbed completely in the upper atmosphere by molecular oxygen. UVB radiation is absorbed by atmospheric ozone partly, and it is reaching Earth`s surface, as UVA radiation. Besides atmospheric ozone, very important factors in determining the intensity of UVB radiation globally are the solar zenith angle and cloudiness. It may be calculated from global ozone changes that the clear-sky UVB doses may have enhanced by 10-15 % during spring and 5-10 % during summer at the latitudes of Finland, following the decrease of total ozone between 1979-90. The Finnish ozone and UV monitoring activities have become a part of international activities, especially the EU Environment and Climate Programme`s research projects. The main national level effort has been the Finnish Academy`s climatic change programme, SILMU 1990-95. This presentation summarises the scientific results reached during the SILMU project

  11. Solar ultraviolet radiation cataract.

    Science.gov (United States)

    Löfgren, Stefan

    2017-03-01

    Despite being a treatable disease, cataract is still the leading cause for blindness in the world. Solar ultraviolet radiation is epidemiologically linked to cataract development, while animal and in vitro studies prove a causal relationship. However, the pathogenetic pathways for the disease are not fully understood and there is still no perfect model for human age related cataract. This non-comprehensive overview focus on recent developments regarding effects of solar UV radiation wavebands on the lens. A smaller number of fundamental papers are also included to provide a backdrop for the overview. Future studies are expected to further clarify the cellular and subcellular mechanisms for UV radiation-induced cataract and especially the isolated or combined temporal and spatial effects of UVA and UVB in the pathogenesis of human cataract. Regardless of the cause for cataract, there is a need for advances in pharmaceutical or other treatment modalities that do not require surgical replacement of the lens. Copyright © 2016. Published by Elsevier Ltd.

  12. Translating ultraviolet autofluorescence microscopy toward clinical endomicroscopy

    Science.gov (United States)

    Lin, Bevin; Urayama, Shiro; Saroufeem, Ramez M. G.; Matthews, Dennis L.; Demos, Stavros G.

    2011-03-01

    The potential of autofluorescence microscopy under ultraviolet excitation is investigated as a method to visualize superficial epithelial microstructures and their modification with progression of disease. This method does not require the use of contrast agents, sectioning methods, or tissue preparation. Imaging of esophagus tissue is the focus of this study and deals with three main issues: a) What is the origin of the signal; b) How the gradual microstructure modification associated with various stages of esophageal disease is visualized; c) What are the designing parameters for in vivo implementation.

  13. SU-C-204-06: Monte Carlo Dose Calculation for Kilovoltage X-Ray-Psoralen Activated Cancer Therapy (X-PACT): Preliminary Results

    Energy Technology Data Exchange (ETDEWEB)

    Mein, S [Duke University Medical Physics Graduate Program (United States); Gunasingha, R [Department of Radiation Safety, Duke University Medical Center (United States); Nolan, M [Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University (United States); Oldham, M; Adamson, J [Department of Radiation Oncology, Duke University Medical Center (United States)

    2016-06-15

    promise for accurate quantification of dose for this novel psoralen X-ray therapy. Funding Support, Disclosures, & Conflict of Interest: The Monte Carlo simulation work was not funded; Drs. Adamson & Oldham have received funding from Immunolight LLC for X-PACT research.

  14. Ultraviolet-radiation-curable paints

    Energy Technology Data Exchange (ETDEWEB)

    Grosset, A M; Su, W F.A.; Vanderglas, E

    1981-09-30

    In product finishing lines, ultraviolet radiation curing of paints on prefabricated structures could be more energy efficient than curing by natural gas fired ovens, and could eliminate solvent emission. Diffuse ultraviolet light can cure paints on three dimensional metal parts. In the uv curing process, the spectral output of radiation sources must complement the absorption spectra of pigments and photoactive agents. Photosensitive compounds, such as thioxanthones, can photoinitiate unsaturated resins, such as acrylated polyurethanes, by a free radical mechanism. Newly developed cationic photoinitiators, such as sulfonium or iodonium salts (the so-called onium salts) of complex metal halide anions, can be used in polymerization of epoxy paints by ultraviolet light radiation. One-coat enamels, topcoats, and primers have been developed which can be photoinitiated to produce hard, adherent films. This process has been tested in a laboratory scale unit by spray coating these materials on three-dimensional objects and passing them through a tunnel containing uv lamps.

  15. Luminescent properties of Li2 (Ca0.99, Eu0.01) SiO4: B3+ particles as a potential bluish green phosphor for ultraviolet light-emitting diodes

    Science.gov (United States)

    Yao, Shanshan; Chen, Donghua

    2007-12-01

    In our study, the 1% mol Eu2+ doped Li2CaSiO4: B3+ phosphors were prepared by the combustion method as fluorescent material for ultraviolet, light-emitting diodes (UV-LEDs) used as a light source. The properties of Li2 (Ca0.99, Eu0.01) SiO4: B3+ phosphors with urea concentration, doping boric acid and a series of initiating combustion temperature were investigated. The crystallization and particle sizes of Li2 (Ca0.99, Eu0.01) SiO4: B3+ has been investigated by using powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). Luminescence measurements showed that the phosphors can be efficiently excited by UV to the visible region, and exhibited bluish green light with a peak of 480 nm. The results showed that the boric acid was effective in improving the luminescence intensity of Li2 (Ca0.99, Eu0.01) SiO4: B3+ and the optimum molar ratio of boric acid to calcium nitrate was about 0.06. The optimized phosphors Li2 (Ca0.99, Eu0.01) SiO4: B0.063+ showed 180% improved emission intensity compared with that of the Li2 (Ca0.99, Eu0.01) SiO4 phosphors under ultraviolet (λex =287 nm) excitation.

  16. Ultraviolet light and cutaneous lupus

    NARCIS (Netherlands)

    Bijl, Marc; Kallenberg, Cees G. M.

    2006-01-01

    Exposure to ultraviolet (UV) light is one of the major factors known to trigger cutaneous disease activity in (systemic) lupus erythematosus patients. UV light, UVB in particular, is a potent inducer of apoptosis. Currently, disturbed clearance of apoptotic cells is one of the concepts explaining

  17. Individual- and scattered-tree influences on ultraviolet irradiance

    Science.gov (United States)

    Gordon M. Heisler; Richard H. Gao, Wei Grant

    2003-01-01

    Many of the potential effects of ultraviolet radiation (UVR--damage to materials, altered herbivory of insects and activity of microbes, modified growth of vegetation, and adverse or beneficial effects on human health?are modified by the presence of trees that influence UVR exposure to various degrees. Though tree effects on total solar irradiance have been...

  18. Protective effect of (-)-epigallocatechin gallate on ultraviolet b ...

    African Journals Online (AJOL)

    ultraviolet B (UV-B)-induced skin damages in hairless mice in order to develop a natural sunscreen compound ... Thus, the plant compound can potentially be used as an ... UV-B is a form of electromagnetic radiation with a wavelength ranging from 280 nm to 320 nm [1]. UV-B triggers generation of cyclobutane pyrimidine.

  19. Vacuum ultraviolet radiometry of xenon positive column discharges

    Science.gov (United States)

    Doughty, D. A.; Fobare, D. F.

    1995-10-01

    In order to judge the potential fluorescent lamp applications of various low-pressure positive column discharges it is necessary to measure the absolute power emitted in the ultraviolet region of the spectrum. For rare-gas discharges the principle emission occurs in the vacuum ultraviolet so that it is difficult to measure the radiant emittance (power per unit area) of the resonance radiation by standard methods. Two independent techniques are discussed for measuring the radiant emittance of positive column discharges in the vacuum ultraviolet. These techniques are used to study xenon positive column discharges at the resonance wavelength of 147 nm. The first method relies on the measurement of the resonance level density by absorption techniques. The effective decay rate of the resonance level is then determined by the simulation of resonance radiation transport. These two quantities are combined to yield the radiant emittance at 147 nm without implementing vacuum ultraviolet techniques. The second method uses a measurement of the resonance radiation normal to the positive column axis made with a calibrated vacuum ultraviolet detector. The angular distribution of the resonance radiation leaving the tube is determined by the simulation of resonance radiation transport. The detector measurement places the angular distribution of the radiance on an absolute scale, which can then be integrated to yield the radiant emittance. These two techniques are compared for pure xenon discharges at various pressures and currents.

  20. Two ultraviolet radiation datasets that cover China

    Science.gov (United States)

    Liu, Hui; Hu, Bo; Wang, Yuesi; Liu, Guangren; Tang, Liqin; Ji, Dongsheng; Bai, Yongfei; Bao, Weikai; Chen, Xin; Chen, Yunming; Ding, Weixin; Han, Xiaozeng; He, Fei; Huang, Hui; Huang, Zhenying; Li, Xinrong; Li, Yan; Liu, Wenzhao; Lin, Luxiang; Ouyang, Zhu; Qin, Boqiang; Shen, Weijun; Shen, Yanjun; Su, Hongxin; Song, Changchun; Sun, Bo; Sun, Song; Wang, Anzhi; Wang, Genxu; Wang, Huimin; Wang, Silong; Wang, Youshao; Wei, Wenxue; Xie, Ping; Xie, Zongqiang; Yan, Xiaoyuan; Zeng, Fanjiang; Zhang, Fawei; Zhang, Yangjian; Zhang, Yiping; Zhao, Chengyi; Zhao, Wenzhi; Zhao, Xueyong; Zhou, Guoyi; Zhu, Bo

    2017-07-01

    Ultraviolet (UV) radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization's measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes.

  1. Ultraviolet extensions of particle physics

    DEFF Research Database (Denmark)

    Berthier, Laure Gaëlle

    The discovery of the Higgs boson in 2012 at the Large Hadron Collider completed the Standard Model field content. Many questions though remain unanswered by the Standard Model triggering a search for new physics. New physics could manifest itself at the Large Hadron Collider by the discovery of new...... particles. However, the lack of new resonances might suggest that these new particles are still out of reach which leaves us with few options. Two possibilities are explored in this thesis. The first is to study precision measurements which might indicate new physics as small deviations from the Standard...... are expressed as power series with missing higher order terms. We also show how to connect ultraviolet models of new physics to the Standard Model effective field theory and calculate bounds on them using the Standard Model effective field theory fit results. Finally, we study a nonrelativistic ultraviolet...

  2. Treating Water Contamination using Ultraviolet Radiation to Control Cryptosporidium and E.Coli

    OpenAIRE

    Kennedy, David; O'Hehir, Michael; Dunphy, Thomas

    2007-01-01

    Concerns about the quality of drinking water in Ireland have come into sharp focus with the recent Cryptosporidium outbreak in Galway City. This article looks at how ultraviolet radiation can offer a potential solution in the control of Cryptosporidium contamination.

  3. Ultraviolet Protection by Fabric Engineering

    Directory of Open Access Journals (Sweden)

    Mukesh Kumar Singh

    2013-01-01

    Full Text Available Background. The increasing emission of greenhouse gases has evoked the human being to save the ozone layer and minimize the risk of ultraviolet radiation (UVR. Various fabric structures have been explored to achieve desired ultraviolet protection factor (UPF in various situations. Objective. In this study, the effect of various filament configurations like twisted, flat, intermingled, and textured in multifilament yarns on fabric in different combinations is assessed in order to engineer a fabric of better ultraviolet protection factor (UPF. Methods. In order to engineer a fabric having optimum UV protection with sufficient comfort level in multifilament woven fabrics, four different yarn configurations, intermingled, textured, twisted, and flat, were used to develop twelve different fabric samples. The most UV absorbing and most demanding fibre polyethylene terephthalate (PET was considered in different filament configuration. Results. The combinations of intermingled warp with flat, intermingled, and textured weft provided excellent UVR protection comparatively at about 22.5 mg/cm2 fabric areal density. The presence of twisted yarn reduced the UV protection due to enhanced openness in fabric structure. Conclusion. The appropriate combination of warp and weft threads of different configuration should be selected judiciously in order to extract maximum UV protection and wear comfort attributes in multifilament woven PET fabrics.

  4. Ultraviolet laser technology and applications

    CERN Document Server

    Elliott, David L

    1995-01-01

    Ultraviolet Laser Technology and Applications is a hands-on reference text that identifies the main areas of UV laser technology; describes how each is applied; offers clearly illustrated examples of UV opticalsystems applications; and includes technical data on optics, lasers, materials, and systems. This book is unique for its comprehensive, in-depth coverage. Each chapter deals with a different aspect of the subject, beginning with UV light itself; moving through the optics, sources, and systems; and concluding with detailed descriptions of applications in various fields.The text enables pr

  5. Ultraviolet divergences and supersymmetric theories

    Energy Technology Data Exchange (ETDEWEB)

    Sagnotti, A.

    1984-09-01

    This article is closely related to the one by Ferrara in these same Proceedings. It deals with what is perhaps the most fascinating property of supersymmetric theories, their improved ultraviolet behavior. My aim here is to present a survey of the state of the art as of August, 1984, and a somewhat more detailed discussion of the breakdown of the superspace power-counting beyond N = 2 superfields. A method is also described for simplifying divergence calculations that uses the locality of subtracted Feynman integrals. 74 references.

  6. Ultraviolet luminescence from latent fingerprints.

    Science.gov (United States)

    Bramble, S K; Creer, K E; Qiang, W G; Sheard, B

    1993-04-01

    Illumination of latent fingerprints on white paper using 266-nm radiation from a Nd:YAG laser and photographic detection of their ultraviolet fluorescence, produces images with good ridge detail. The detection rate was 69% in a survey of fingerprints from 34 people compared with only 23% using an argon-ion laser at 514 nm. Prolonged exposure to UV light decreased the inherent UV fluorescence intensity but no adverse effects were observed on subsequent treatment with 1,8-diazafluoren-9-one or ninhydrin.

  7. Ultraviolet light and ocular diseases.

    Science.gov (United States)

    Yam, Jason C S; Kwok, Alvin K H

    2014-04-01

    The objective of this study is to review the association between ultraviolet (UV) light and ocular diseases. The data are sourced from the literature search of Medline up to Nov 2012, and the extracted data from original articles, review papers, and book chapters were reviewed. There is a strong evidence that ultraviolet radiation (UVR) exposure is associated with the formation of eyelid malignancies [basal cell carcinoma (BCC) and squamous cell carcinoma (SCC)], photokeratitis, climatic droplet keratopathy (CDK), pterygium, and cortical cataract. However, the evidence of the association between UV exposure and development of pinguecula, nuclear and posterior subcapsular cataract, ocular surface squamous neoplasia (OSSN), and ocular melanoma remained limited. There is insufficient evidence to determine whether age-related macular degeneration (AMD) is related to UV exposure. It is now suggested that AMD is probably related to visible radiation especially blue light, rather than UV exposure. From the results, it was concluded that eyelid malignancies (BCC and SCC), photokeratitis, CDK, pterygium, and cortical cataract are strongly associated with UVR exposure. Evidence of the association between UV exposure and development of pinguecula, nuclear and posterior subcapsular cataract, OSSN, and ocular melanoma remained limited. There is insufficient evidence to determine whether AMD is related to UV exposure. Simple behaviural changes, appropriate clothing, wearing hats, and UV blocking spectacles, sunglasses or contact lens are effective measures for UV protection.

  8. The ultraviolet spectrum of OCS from first principles

    DEFF Research Database (Denmark)

    Schmidt, Johan Albrecht; Johnson, Matthew Stanley; McBane, G.C.

    2012-01-01

    Global three dimensional potential energy surfaces and transition dipole moment functions are calculated for the lowest singlet and triplet states of carbonyl sulfide at the multireference configuration interaction level of theory. The first ultraviolet absorption band is then studied by means...... absorption with decreasing energy (35,000 cm(-1)) and eventually exceeds it. Direct excitation of the repulsive triplet states is negligible except at photon energies E(ph) ... and the temperature dependence of the cross section is well reproduced....

  9. Near-ultraviolet laser diodes for brilliant ultraviolet fluorophore excitation.

    Science.gov (United States)

    Telford, William G

    2015-12-01

    Although multiple lasers are now standard equipment on most modern flow cytometers, ultraviolet (UV) lasers (325-365 nm) remain an uncommon excitation source for cytometry. Nd:YVO4 frequency-tripled diode pumped solid-state lasers emitting at 355 nm are now the primary means of providing UV excitation on multilaser flow cytometers. Although a number of UV excited fluorochromes are available for flow cytometry, the cost of solid-state UV lasers remains prohibitively high, limiting their use to all but the most sophisticated multilaser instruments. The recent introduction of the brilliant ultraviolet (BUV) series of fluorochromes for cell surface marker detection and their importance in increasing the number of simultaneous parameters for high-dimensional analysis has increased the urgency of including UV sources in cytometer designs; however, these lasers remain expensive. Near-UV laser diodes (NUVLDs), a direct diode laser source emitting in the 370-380 nm range, have been previously validated for flow cytometric analysis of most UV-excited probes, including quantum nanocrystals, the Hoechst dyes, and 4',6-diamidino-2-phenylindole. However, they remain a little-used laser source for cytometry, despite their significantly lower cost. In this study, the ability of NUVLDs to excite the BUV dyes was assessed, along with their compatibility with simultaneous brilliant violet (BV) labeling. A NUVLD emitting at 375 nm was found to excite most of the available BUV dyes at least as well as a UV 355 nm source. This slightly longer wavelength did produce some unwanted excitation of BV dyes, but at sufficiently low levels to require minimal additional compensation. NUVLDs are compact, relatively inexpensive lasers that have higher power levels than the newest generation of small 355 nm lasers. They can, therefore, make a useful, cost-effective substitute for traditional UV lasers in multicolor analysis involving the BUV and BV dyes. Published 2015 Wiley Periodicals Inc. on

  10. Development of Ultraviolet Spectrophotometric Method for Analysis ...

    African Journals Online (AJOL)

    HP

    Purpose: An ultraviolet spectrophotometric system was developed and validated for the quantitative determination of lornoxicam in solid dosage forms. Methods: Lornoxicam was dissolved in 0.01M NaOH and analysed using ultraviolet (UV) spectrophotometry. Various analytical parameters such as linearity, precision, ...

  11. Pen Ink as an Ultraviolet Dosimeter

    Science.gov (United States)

    Downs, Nathan; Turner, Joanna; Parisi, Alfio; Spence, Jenny

    2008-01-01

    A technique for using highlighter ink as an ultraviolet dosimeter has been developed for use by secondary school students. The technique requires the students to measure the percentage of colour fading in ink drawn onto strips of paper that have been exposed to sunlight, which can be calibrated to measurements of the ultraviolet irradiance using…

  12. Hand protection from ultraviolet exposure

    Energy Technology Data Exchange (ETDEWEB)

    Khazova, M.; O' Hagan, J.B. [Health Protection Agency, Radiation Protection Division, Chilton, Did cot (United Kingdom)

    2006-07-01

    Full text of publication follows: A number of industrial applications and public services involve exposure to ultraviolet radiation (U.V.R.) from a variety of lamps and lasers, for example, in forensic examination, biological trans-illuminators, dentistry, laser material processing, microelectronics, etc. The proposed European Union Directive on Optical Radiation would place specific requirements on employers to provide adequate safety measures to reduce exposure to U.V.R., including gloves for hand protection. The selection of gloves should be based on a risk assessment and on the performance characteristics of the gloves for the task. However, current International and national standards do not describe evaluation procedures of disposable gloves for hand protection against non-ionising radiation. A methodology for assessment of the UV protection level for disposable gloves and a simple measurement protocol are proposed, based on a common approach with UV protection by clothing and sunscreens. Glove Ultraviolet Protection Factor is defined as a time-scale increase in exposure permitted for the hand protected by a glove with respect to an unprotected hand. However, the wide variety of U.V.R. sources and the real-life conditions of glove use (stretching and wetting the surface by liquids) bring substantial challenges to the assessment method. Our study of {approx} 50 samples of widely used disposable gloves made of different materials (nitrile, vinyl, latex and chloroprene) showed that for all tested gloves a change in U.V.R. attenuation with stretching is characteristic for the type of glove material and can be included as a scaling factor in the definition of U.V.R. protection. Glove material has a bigger effect on U.V.R. protection level than variations in the glove thickness or its colour. The following approaches are suggested to overcome the problem of variable U.V.R. sources: - Worst case scenario minimal protection level, most restrictive case - Application

  13. Vinegar identification by ultraviolet spectrum technology and pattern recognition method

    National Research Council Canada - National Science Library

    Huali, Zhao; Zhixi, Li; Xuemei, Yang; Baoan, Chen

    2009-01-01

    Some kinds of vinegars are studied for identification. First, their ultraviolet spectrum curves are obtained by evaporation and ultraviolet spectrum scanning under the conditions of wavelength at 245...

  14. The Ultraviolet Albedo of Ganymede

    Science.gov (United States)

    McGrath, Melissa; Hendrix, Amanda

    2013-01-01

    A large set of ultraviolet images of Ganymede have been acquired with the Hubble Space Telescope over the last 15 years. These images have been used almost exclusively to study Ganymede's stunning auroral emissions (Feldman et al. 2000; Eviatar et al. 2001; McGrath et al. 2004; Saur et al. 2011; McGrath et al. 2013), and even the most basic information about Ganymede's UV albedo has yet to be gleaned from these data. We will present a first-cut analysis of both disk-averaged and spatially-resolved UV albedos of Ganymede, with focus on the spatially-resolved Lyman-alpha albedo, which has never been considered previously for this satellite. Ganymede's visibly bright regions are known to be rich in water ice, while the visibly dark regions seem to be more carbonaceous (Carlson et al., 1996). At Lyman-alpha, these two species should also have very different albedo values.

  15. Ultraviolet, Visible, and Fluorescence Spectroscopy

    Science.gov (United States)

    Penner, Michael H.

    Spectroscopy in the ultraviolet-visible (UV-Vis) range is one of the most commonly encountered laboratory techniques in food analysis. Diverse examples, such as the quantification of macrocomponents (total carbohydrate by the phenol-sulfuric acid method), quantification of microcomponents, (thiamin by the thiochrome fluorometric procedure), estimates of rancidity (lipid oxidation status by the thiobarbituric acid test), and surveillance testing (enzyme-linked immunoassays), are presented in this text. In each of these cases, the analytical signal for which the assay is based is either the emission or absorption of radiation in the UV-Vis range. This signal may be inherent in the analyte, such as the absorbance of radiation in the visible range by pigments, or a result of a chemical reaction involving the analyte, such as the colorimetric copper-based Lowry method for the analysis of soluble protein.

  16. Galactic Astronomy in the Ultraviolet

    Science.gov (United States)

    Rastorguev, A. S.; Sachkov, M. E.; Zabolotskikh, M. V.

    2017-12-01

    We propose a number of prospective observational programs for the ultraviolet space observatory WSO-UV, which seem to be of great importance to modern galactic astronomy. The programs include the search for binary Cepheids; the search and detailed photometric study and the analysis of radial distribution of UV-bright stars in globular clusters ("blue stragglers", blue horizontal-branch stars, RR Lyrae variables, white dwarfs, and stars with UV excesses); the investigation of stellar content and kinematics of young open clusters and associations; the study of spectral energy distribution in hot stars, including calculation of the extinction curves in the UV, optical and NIR; and accurate definition of the relations between the UV-colors and effective temperature. The high angular resolution of the observatory allows accurate astrometric measurements of stellar proper motions and their kinematic analysis.

  17. Extreme ultraviolet capillary discharge lasers

    Science.gov (United States)

    Wilson, Sarah; West, Andrew; Tallents, Greg

    2017-10-01

    An extreme ultraviolet capillary discharge laser has recently been installed at the University of York. The laser produces EUV radiation of wavelength 46.9nm, with pulse durations of approximately 1.2ns and energies of up to 50 μJ. A population inversion is produced by a high voltage electrical discharge passing through an argon filled capillary tube. Within the capillary, radial pinching of the argon plasma through JxB force causes the pressure and temperature of the plasma to increase which causes amplification between 3p -3s (J = 0-1) transitions producing EUV radiation. Laser optimisation, calibration of detectors and designs for initial experiments to produce warm dense matter by focusing onto solid targets are presented. The plasmas formed by the EUV laser irradiation of solid targets can be shown to produce warm dense matter in a regime where the ionization equilibrium is dominated by radiative ionization.

  18. Ultraviolet damage in solar cell assemblies with various UV filters

    Science.gov (United States)

    Meulenberg, A., Jr.

    1977-01-01

    Ultraviolet damage to the new violet and non-reflective type solar cell assemblies, was studied, and potential advantages of using coverslides with no filters or filters with cut-off wavelengths below 0.35 micron were determined. The experiments consisted of three types of tests on fused silica coverslides with 0.35- and 0.30-micron cut-off filters and no cut-off filters, as well as on ceria-doped microsheet coverslides. Ultraviolet irradiation for over 1500 hours at one sun conditions (AMO) was carried out under vacuum of about 1 million torr. Nearly identical results for non-reflective type cells with 0.35-micro cut-off filters or ceria-doped coverslides were obtained. The 0.30-um filtered cell shows greater than average degradation. The unfiltered cell shows an abrupt drop in the first 20 UVSH and very little subsequent degradation.

  19. Ultraviolet radiation and blue-light emissions from spotlights incorporating tungsten halogen lamps

    CERN Document Server

    MacKinlay, Alistair F; Whillock, M J

    1989-01-01

    This report summarises measurements of the ultraviolet radiation and blue-light emissions from eleven 'desk-top' tungsten halogen (quartz) lamps and one 'floor-standing' tungsten halogen (quartz) lamp available in the UK. Values of occupational hazard weighted and erythemally weighted ultraviolet radiation irradiance and measurements and relevant calculations of blue-light hazards are presented. It is concluded that the safety design of some desk-top tungsten halogen lamps is inadequate to prevent unnecessary exposure of the skin to potentially harmful ultraviolet radiation. It is recommended that all tungsten halogen lamps should have sufficient filtration to reduce their ultraviolet emissions to an acceptably low level. As long as the comfort aversion responses of the eye are respected, direct viewing of the lamps examined should not constitute a retinal hazard.

  20. Some aspects of vacuum ultraviolet radiation physics

    CERN Document Server

    Damany, Nicole; Vodar, Boris

    2013-01-01

    Some Aspects of Vacuum Ultraviolet Radiation Physics presents some data on the state of research in vacuum ultraviolet radiation in association with areas of physics. Organized into four parts, this book begins by elucidating the optical properties of solids in the vacuum ultraviolet region (v.u.v.), particularly the specific methods of determination of optical constants in v.u.v., the properties of metals, and those of ionic insulators. Part II deals with molecular spectroscopy, with emphasis on the spectra of diatomic and simple polyatomic molecules, paraffins, and condensed phases. Part III

  1. Melanoma induction by ultraviolet A but not ultraviolet B radiation requires melanin pigment.

    Science.gov (United States)

    Noonan, Frances P; Zaidi, M Raza; Wolnicka-Glubisz, Agnieszka; Anver, Miriam R; Bahn, Jesse; Wielgus, Albert; Cadet, Jean; Douki, Thierry; Mouret, Stephane; Tucker, Margaret A; Popratiloff, Anastas; Merlino, Glenn; De Fabo, Edward C

    2012-06-06

    Malignant melanoma of the skin (CMM) is associated with ultraviolet radiation exposure, but the mechanisms and even the wavelengths responsible are unclear. Here we use a mammalian model to investigate melanoma formed in response to precise spectrally defined ultraviolet wavelengths and biologically relevant doses. We show that melanoma induction by ultraviolet A (320-400 nm) requires the presence of melanin pigment and is associated with oxidative DNA damage within melanocytes. In contrast, ultraviolet B radiation (280-320 nm) initiates melanoma in a pigment-independent manner associated with direct ultraviolet B DNA damage. Thus, we identified two ultraviolet wavelength-dependent pathways for the induction of CMM and describe an unexpected and significant role for melanin within the melanocyte in melanomagenesis.

  2. 21 CFR 878.4630 - Ultraviolet lamp for dermatologic disorders.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultraviolet lamp for dermatologic disorders. 878... Ultraviolet lamp for dermatologic disorders. (a) Identification. An ultraviolet lamp for dermatologic disorders is a device (including a fixture) intended to provide ultraviolet radiation of the body to...

  3. Fiber-Based Ultraviolet Laser System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The purpose of this program is to develop a compact and efficient ultraviolet laser system for use in space-based uv-Raman instruments. The basis for this system...

  4. Vacuum-Ultraviolet Photovoltaic Detector.

    Science.gov (United States)

    Zheng, Wei; Lin, Richeng; Ran, Junxue; Zhang, Zhaojun; Ji, Xu; Huang, Feng

    2018-01-23

    Over the past two decades, solar- and astrophysicists and material scientists have been researching and developing new-generation semiconductor-based vacuum ultraviolet (VUV) detectors with low power consumption and small size for replacing traditional heavy and high-energy-consuming microchannel-detection systems, to study the formation and evolution of stars. However, the most desirable semiconductor-based VUV photovoltaic detector capable of achieving zero power consumption has not yet been achieved. With high-crystallinity multistep epitaxial grown AlN as a VUV-absorbing layer for photogenerated carriers and p-type graphene (with unexpected VUV transmittance >96%) as a transparent electrode to collect excited holes, we constructed a heterojunction device with photovoltaic detection for VUV light. The device exhibits an encouraging VUV photoresponse, high external quantum efficiency (EQE) and extremely fast tempera response (80 ns, 10 4 -10 6 times faster than that of the currently reported VUV photoconductive devices). This work has provided an idea for developing zero power consumption and integrated VUV photovoltaic detectors with ultrafast and high-sensitivity VUV detection capability, which not only allows future spacecraft to operate with longer service time and lower launching cost but also ensures an ultrafast evolution of interstellar objects.

  5. Ultraviolet asymptotics of glueball propagators

    Science.gov (United States)

    Bochicchio, Marco; Muscinelli, Samuele P.

    2013-08-01

    We point out that perturbation theory in conjunction with the renormalization group ( RG) puts a severe constraint on the structure of the large- N non-perturbative glueball propagators in SU( N) pure Y M, in QCD and in = 1 SU SY QCD with massless quarks, or in any confining asymptotically-free gauge theory massless in perturbation theory. For the scalar and pseudoscalar glueball propagators in pure Y M and QCD with massless quarks we check in detail the RG-improved estimate to the order of the leading and next-to-leading logarithms by means of a remarkable three-loop computation by Chetyrkin et al. We investigate as to whether the aforementioned constraint is satisfied by any of the scalar or pseudoscalar glueball propagators computed in the framework of the AdS String/ large- N Gauge Theory correspondence and of a recent proposal based on a Topological Field Theory underlying the large- N limit of Y M . We find that none of the proposals for the scalar or the pseudoscalar glueball propagators based on the AdS String/large- N Gauge Theory correspondence satisfies the constraint, actually as expected, since the gravity side of the correspondence is in fact strongly coupled in the ultraviolet. On the contrary, the Topological Field Theory satisfies the constraint that follows by the asymptotic freedom.

  6. Ultraviolet vision may be widespread in bats

    Science.gov (United States)

    Gorresen, P. Marcos; Cryan, Paul; Dalton, David C.; Wolf, Sandy; Bonaccorso, Frank

    2015-01-01

    Insectivorous bats are well known for their abilities to find and pursue flying insect prey at close range using echolocation, but they also rely heavily on vision. For example, at night bats use vision to orient across landscapes, avoid large obstacles, and locate roosts. Although lacking sharp visual acuity, the eyes of bats evolved to function at very low levels of illumination. Recent evidence based on genetics, immunohistochemistry, and laboratory behavioral trials indicated that many bats can see ultraviolet light (UV), at least at illumination levels similar to or brighter than those before twilight. Despite this growing evidence for potentially widespread UV vision in bats, the prevalence of UV vision among bats remains unknown and has not been studied outside of the laboratory. We used a Y-maze to test whether wild-caught bats could see reflected UV light and whether such UV vision functions at the dim lighting conditions typically experienced by night-flying bats. Seven insectivorous species of bats, representing five genera and three families, showed a statistically significant ‘escape-toward-the-light’ behavior when placed in the Y-maze. Our results provide compelling evidence of widespread dim-light UV vision in bats.

  7. Ultraviolet Behavior of N = 8 supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, Lance J.; /SLAC

    2010-06-07

    In these lectures the author describes the remarkable ultraviolet behavior of N = 8 supergravity, which through four loops is no worse than that of N = 4 super-Yang-Mills theory (a finite theory). I also explain the computational tools that allow multi-loop amplitudes to be evaluated in this theory - the KLT relations and the unitarity method - and sketch how ultraviolet divergences are extracted from the amplitudes.

  8. Recent advances and applications of gas chromatography vacuum ultraviolet spectroscopy.

    Science.gov (United States)

    Santos, Inês C; Schug, Kevin A

    2017-01-01

    The vacuum ultraviolet spectrophotometer was developed recently as an alternative to existing gas chromatography detectors. This detector measures the absorption of gas-phase chemical species in the range of 120-240 nm, where all chemical compounds present unique absorption spectra. Therefore, qualitative analysis can be performed and quantification follows standard Beer-Lambert law principles. Different fields of application, such as petrochemical, food, and environmental analysis have been explored. Commonly demonstrated is the capability for facile deconvolution of co-eluting analytes. The concept of additive absorption for co-eluting analytes has also been advanced for classification and speciation of complex mixtures using a data treatment procedure termed time interval deconvolution. Furthermore, pseudo-absolute quantitation can be performed for system diagnosis, as well as potentially calibrationless quantitation. In this manuscript an overview of these features, the vacuum ultraviolet spectrophotometer instrumentation, and performance capabilities are given. A discussion of the applications of the vacuum ultraviolet detector is provided by describing and discussing the papers published thus far since 2014. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Plasmonic metamaterials at visible and ultraviolet frequencies (Conference Presentation)

    Science.gov (United States)

    Lezec, Henri J.

    2017-05-01

    Artificial metamaterials - metallo-dielectric composites tailored on deep-subwavelength scale - enable implementation of electromagnetic responses not found in nature, leading to potentially useful applications as well as yielding new insights into the fundamental nature of light. Here we show how we have leveraged ultrasmooth planar nanoplasmonic waveguides deposited by ion-beam-assisted sputter deposition to implement easy-to-fabricate bulk metamaterials operating at visible and ultra-violet wavelengths and having refractive indices ranging from highly anisotropic and positive [1] to quasi-isotropic and negative [2]. Exploiting these structures to tailor the flow of light in exotic ways, we realize devices ranging from high-contrast, near-field nanoparticle optical sensors working in the visible, to the first implementation of a Veselago flat lens [3] functioning in the near ultraviolet. Substituting Al for Ag as the constituent plasmonic metal of choice, we investigate the extension of bulk metamaterial operation into the mid-ultraviolet, for lithographic applications beyond the diffraction limit. [1] T. Xu and H.J. Lezec, Nat. Comm. 5, 4141 (2014). [2] T. Xu, A. Agrawal, M. Abashin, K.J. Chau, and H.J. Lezec, Nature 497, 470 (2013). [3] V.G. Veselago, Sov. Phys. Usp. 10, 509 (1968).

  10. Dynamic properties of ultraviolet-exposed polyurea

    Science.gov (United States)

    Youssef, George; Whitten, Ian

    2017-08-01

    Polyurea is used in military and civilian applications, where exposure to the sun in long durations is imminent. Extended exposure to ultraviolet radiation from the sun can deteriorate its mechanical performance to suboptimal levels. This study reports on the dynamic mechanical properties of polyurea as a function of ultraviolet radiation exposure duration. Six sets of samples were continuously exposed to ultraviolet radiation for different durations up to 18 weeks. Control samples were also tested that did not receive ultraviolet exposure. The dynamic properties were measured using a dynamic mechanical analyzer. Exposed samples exhibited significant color changes from transparent yellow to opaque tan after 18 weeks of exposure. Changes of color were observed as early as 3 weeks of exposure. The dynamic properties showed an initial increase in the dynamic modulus after 3 weeks of exposure, with no further significant change in the stiffness thereafter. The ultraviolet exposure had a significant impact at relatively short loading times or low temperature, for example, up to 6 decades of time. As loading time increases or polyurea operates at high temperature, the effect of ultraviolet exposure and temperature on the performance become highly coupled.

  11. Ultraviolet observations of comet Hale-Bopp

    Science.gov (United States)

    Feldman, Paul D.

    1997-09-01

    Ultraviolet spectroscopy and imaging of comet Hale-Bopp (C/1995 O1) were obtained from a variety of space platforms from shortly after the discovery of the comet through perihelion passage. Observations with the International Ultraviolet Explorer (IUE) and the Hubble Space Telescope (HST) spanned the range of 6.8 to 2.7 AU pre-perihelion, but IUE was decommissioned in September 1996 and HST was precluded from near-perihelion observations because of its solar avoidance constraint. In September 1996, observations were made by the Extreme Ultraviolet Explorer (EUVE) that showed the presence of soft X-rays offset from the optical center of the coma and provided a sensitive spectroscopic upper limit to the Ne/O abundance ratio. During the perihelion period NASA mounted a successful campaign of four sounding rockets that were launched at the White Sands Missile Range, New Mexico, between March 25 and April 8, 1997. The payloads included long-slit spectroscopy and ultraviolet imaging polarimetry. In addition, Hale-Bopp was observed near perihelion by ultraviolet instruments on orbiting spacecraft that were designed for solar or terrestrial observations. Observations with HST, using the Space Telescope Imaging Spectrograph (STIS), installed during the February 1997 servicing mission, resumed in August 1997. Intercomparison of the ultraviolet observations and comparison with the results on gas composition and activity from ground-based visible, infrared and radio observations may permit the resolution of many discrepant results present in the literature.

  12. Modeling Ultraviolet Emissions Near Io

    Science.gov (United States)

    Linker, Jon A.

    2000-01-01

    In this report, we describe work awarded to Science Applications International Corporation, for the period 6/l/99 to 5/31/00. During this time period, we have investigated the interaction of Io, Jupiter's innermost Galilean satellite, with the Io plasma torus, and the role this interaction plays in producing ultraviolet (UV) emissions from neutral oxygen and sulfur. Io, the innermost of Jupiter's Galilean satellites, plays a unique role in the jovian magnetosphere. Neutral material that escapes from Io is ionized to form the lo torus, a dense, heavy-ion plasma that corotates with Jupiter and interacts with Io. Io supplies not only the torus, but is a major source of plasma for the entire magnetosphere. Ionization and charge-exchange of neutrals near lo strongly influences the plasma interaction, and Io's neutral atmosphere plays an important role in the generation of currents that couple Io to Jupiter. There have been no in situ measurements of the neutral density near Io, but remote observations of neutrals near lo have been performed for many years. Recent observations from the Hubble Space Telescope (HST) have shown detailed structure in UV emissions from neutral species near Io. Electron-impact of the neutrals by the Io torus plasma is the primary mechanism responsible for exciting these emissions. Previously, we have modeled the Io plasma environment using three-dimensional magnetohydrodynamic (MHD) simulations, and we have shown that the interaction between Io and the plasma torus plays an important role in producing the morphology of the observed emissions. In the past year, we have extended these studies to use both UV observations and Galileo particle and field measurements to investigate the Io interaction.

  13. Ultraviolet Fluorescence Spectra of Fingerprints

    Directory of Open Access Journals (Sweden)

    Naoki Saitoh

    2005-01-01

    Full Text Available We have studied inherent fluorescence spectra and imaging of fingerprints in the deep ultraviolet (UV region with a nanosecond-pulsed Nd-YAG laser system that consists of a tunable laser, a cooled CCD camera, and a grating spectrometer. In this paper, we have studied UV fluorescence spectra of fingerprints under 266-nm illumination. Fluorescence spectra of fingerprints have two main peaks, around 330 nm (peak A and 440 nm (peak B. At first, when a fingerprint has just been pressed, peak A is dominant. However, its intensity reduces as the total illumination time increases. On the other hand, peak B is weak at first. It appears after enough 266-nm illumination and its intensity increases as time elapses. After 3 h of illumination, peak A almost diminishes and peak B becomes dominant. By leaving the fingerprint under a fluorescent lamp in a room without laser illumination, peak A can be restored partly, while the intensity of peak B still increases.Time-resolved fluorescence spectra were also measured for these two peaks. The lifetime of each peak is 2.0 nsec (peak A and 6.2 nsec (peak B on average. Both peaks seem to consist of several components with different lifetimes. In the case of peak A, the 330-nm peak decays fast and a new component at 360 nm becomes dominant when the delay time exceeds 20 nsec. In the case of peak B, unlike peak A, no clear peak separation is observed, but the peak position seems to move from 440 to 460 nm when the delay time becomes larger.

  14. COS Ultraviolet Baryon Survey (CUBS)

    Science.gov (United States)

    Chen, Hsiao-Wen

    2017-08-01

    The cosmic star-formation-rate density declines rapidly from z 1.5 to the present day. Observing the co-evolution of galaxies and their surrounding gas during this epoch provides key insights into how galaxy growth is regulated by accretion and outflows. We propose the COS Ultraviolet Baryon Survey (CUBS) project to map gas flows in and out of the circumgalactic medium at intermediate redshifts using absorption line spectroscopy of 15 QSOs at zqso=0.8-1.3. CUBS will bridge the gap between existing efforts at z4 studies in the JWST era, and greatly enhance HST's UV spectroscopic legacy with a three-fold increase in high-quality UV absorption spectra at zqso>0.8. Over the range of z=0.4-0.8, absorption measurements of both low- and high-ions (i.e. C, O, Si, Ne), together with accurate measurements of HI column density from multiple Lyman series transitions, enable robust measurements of the ionization state and metallicity of the gas. All of the proposed QSOs are in the Dark Energy Survey, providing deep, multi-color images of the galactic environments of the absorption systems. We will obtain follow-up spectroscopy of the QSOs and complete spectroscopic redshift surveys of the galaxies in the foreground volume. CUBS will 1) provide a census of the chemical enrichment of the CGM/IGM over cosmic time, 2) assess its relationship to galaxies at various stages of evolution, and 3) inform and refine galactic feedback prescriptions in cosmological simulations. This project exploits a synergy between UV spectroscopy, parallel slitless grism spectroscopy, and ground-based wide-field survey data to advance our understanding of the cosmic evolution of baryonic structures.

  15. Ultraviolet Spectroscopy of Asteroid(4) Vesta

    Science.gov (United States)

    Li, Jian-Yang; Bodewits, Dennis; Feaga, Lori M.; Landsman, Wayne; A'Hearn, Michael F.; Mutchler, Max J.; Russell, Christopher T.; McFadden, Lucy A.; Raymond, Carol A.

    2011-01-01

    We report a comprehensive review of the UV-visible spectrum and rotational lightcurve of Vesta combining new observations by Hubble Space Telescope and Swift with archival International Ultraviolet Explorer observations. The geometric albedos of Vesta from 220 nm to 953 nm arc derived by carefully comparing these observations from various instruments at different times and observing geometries. Vesta has a rotationally averaged geometric albedo of 0.09 at 250 nm, 0.14 at 300 nm, 0.26 at 373 nm, 0.38 at 673 nm, and 0.30 at 950 nm. The linear spectral slope in the ultraviolet displays a sharp minimum ncar sub-Earth longitude of 20deg, and maximum in the eastern hemisphere. This is completely consistent with the distribution of the spectral slope in the visible wavelength. The uncertainty of the measurement in the ultraviolet is approx.20%, and in the visible wavelengths better than 10%. The amplitude of Vesta's rotational lightcurves is approx.10% throughout the range of wavelengths we observed, but is smaller at 950 nm (approx.6%) ncar the 1-micron mafic band center. Contrary to earlier reports, we found no evidence for any difference between the phasing of the ultraviolet and visible/ncar-infrared lightcurves with respect to sub-Earth longitude. Vesta's average spectrum between 220 and 950 nm can well be described by measured reflectance spectra of fine particle howardite-like materials of basaltic achondrite meteorites. Combining this with the in-phase behavior of the ultraviolet, visible. and ncar-infrared lightcurves, and the spectral slopes with respect to the rotational phase, we conclude that there is no global ultraviolet/visible reversal on Vesta. Consequently, this implies lack of global space weathering on Vesta. Keyword,: Asteroid Vesta; Spectrophotometry; Spectroscopy; Ultraviolet observations; Hubble Space Telescope observations

  16. Stratospheric ozone fluctuation and ultraviolet radiation over Serbia

    Directory of Open Access Journals (Sweden)

    Nikolić Jugoslav L.

    2011-01-01

    Full Text Available Increased ultraviolet radiation potentially detrimental to health is a direct effect of the reduced ozone layer of the Earth’s atmosphere. Stratospheric ozone over the territory of Serbia and immediate surrounding depleted in the considered period of 1979-2008; its amount reduced by 7.6%. Solar and volcanic activities have significant effect on the interannual variability of the stratospheric ozone. Ozone layer over Serbia is 13.8% thicker than the planetary layer, with the ozone hole forming once in five years on average without serious health implications.

  17. Ultraviolet Extinction and Visible Transparency by Ivy Nanoparticles

    Directory of Open Access Journals (Sweden)

    Li Quanshui

    2010-01-01

    Full Text Available Abstract Though much research has been conducted for nanoparticles, naturally occurring nanoparticles have not yet been well explored for their diverse properties and potential applications. This paper reports the optical absorption and scattering properties of nanoparticles secreted by English ivy. Both experimental and theoretical studies have been conducted. Strong ultraviolet extinction and excellent visible transparency are observed, compared to the inorganic TiO2 and ZnO nanoparticles at similar concentrations. The contributions of absorption and scattering to the total extinction are quantified by simulation of the Mie scattering theory.

  18. Red tattoos, ultraviolet radiation and skin cancer in mice

    DEFF Research Database (Denmark)

    Lerche, Catharina M; Heerfordt, Ida M; Serup, Jørgen

    2017-01-01

    cell carcinoma (SCC) was measured. All UV-irradiated mice developed SCCs. The time to the onset of the first and second tumor was identical in the red-tattooed group compared with the control group (182 vs 186 days and 196 vs 203 days, P=ns). Statistically, the third tumor appeared slightly faster......Ultraviolet radiation (UVR) induces skin cancer. The combination of UVR and red tattoos may be associated with increased risk of skin cancer due to potential carcinogens in tattoo inks. This combination has not been studied previously. Immunocompetent C3.Cg/TifBomTac hairless mice (n=99) were...

  19. The Evaluation of Saturated Amines as Potential Ultraviolet Laser Sources.

    Science.gov (United States)

    1982-02-25

    2.2.2)octane ( ABCO ) -- both in the vapor phase. TMA was usually studied at pressures between 5 and 50 Torr, while the ABCO pressure was set by its par...in either the MPI or OPA spectrum. Because of the presence of rich vibronic detail in the MPI and OPA spectrum of ABCO , this molecule lent itself to...hiI, 1.to - ~ ~ o ttl -4- The intensity alterations in the vibronic features in the TPFE spectrum of ABCO are interpreted *by Halpern et al. as

  20. Ultraviolet Emission from Rocket Motor Plumes

    Science.gov (United States)

    1994-06-01

    blind ultraviolet, SBUV. Ultraviolet environmental effects on biological or physical systems are of:en considered for the ranges LVA, 400 to 315 nm, UVB...and surface destruction of ozore. Ir. remote unpolluted environments there is a lower surface level, about __ -2 aý Gx-op’ 13 ppb for the Amazonian...Climatic Bawline Observatories’ J. Geophys Res 91(D4). 522.-5236 (14󈨤) 14. Hough, A. M. and Denvent, R G. "Changes in the globil concentration of

  1. Ultraviolet Free Electron Laser Facility preliminary design report

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Zvi, I. [ed.

    1993-02-01

    This document, the Preliminary Design Report (PDR) for the Brookhaven Ultraviolet Free Electron Laser (UV FEL) facility, describes all the elements of a facility proposed to meet the needs of a research community which requires ultraviolet sources not currently available as laboratory based lasers. Further, for these experiments, the requisite properties are not extant in either the existing second or upcoming third generation synchrotron light sources. This document is the result of our effort at BNL to identify potential users, determine the requirements of their experiments, and to design a facility which can not only satisfy the existing need, but have adequate flexibility for possible future extensions as need dictates and as evolving technology allows. The PDR is comprised of three volumes. In this, the first volume, background for the development of the proposal is given, including descriptions of the UV FEL facility, and representative examples of the science it was designed to perform. Discussion of the limitations and potential directions for growth are also included. A detailed description of the facility design is then provided, which addresses the accelerator, optical, and experimental systems. Information regarding the conventional construction for the facility is contained in an addendum to volume one (IA).

  2. Ultraviolet radiation, sun and tanning salons

    CERN Document Server

    1999-01-01

    The pamphlet gives some information about ultraviolet radiation (UV), UV-sources and health effects, tanning in artificial and natural sun. It also includes some sun protection advice. It is intended mainly for persons inspecting artificial tanning units and for the owners of tanning salons. (Author)

  3. Quantum interference spectroscopy in the vacuum ultraviolet

    NARCIS (Netherlands)

    Eikema, K. S E; Zinkstok, R. Th; Witte, S.; Hogervorst, W.; Ubachs, W.

    2006-01-01

    With two experiments on respectively krypton at 2 x 212 nm and xenon at 125 nm we have demonstrated the method of quantum interference spectroscopy in the deep- and vacuum-ultraviolet. Multiple pulses from a frequency comb laser are amplified and frequency converted and used in a Ramsey-like direct

  4. Widely tunable extreme ultraviolet frequency comb generation

    NARCIS (Netherlands)

    Pinkert, T. J.; Kandula, D. Z.; Gohle, Ch; Morgenweg, J.; Barmes, I.; Ubachs, W.; Eikema, K. S E

    2011-01-01

    Frequency comb lasers [1] have led to great advances in fields such as precision spectroscopy, optical atomic clocks, and attosecond science. We transfer the remarkable precision of frequency combs to extreme ultraviolet (XUV) wavelengths by parametric amplification and high-harmonic generation

  5. Solar ultraviolet radiation in a changing climate

    Science.gov (United States)

    The projected large increases in damaging ultraviolet radiation as a result of global emissions of ozone-depleting substances have been forestalled by the success of the Montreal Protocol. New challenges are now arising in relation to climate change. We highlight the complex inte...

  6. Ultraviolet spectroscopic evaluation of bioactive saponin fraction ...

    African Journals Online (AJOL)

    Ultraviolet spectroscopic evaluation of bioactive saponin fraction from the aqueous extract of Vernonia amygdalina [Esteraeceae] leaf. Paul Chukwuemeka ADIUKWU 1*, Martina BONSU 1, Inemesit OKON-BEN 1,. Paul PEPRAH 1, Paapa MENSAH-KANE 1, Jonathan JATO 1 and Grace NAMBATYA 2. 1School of Pharmacy ...

  7. Ultraviolet Spectrophotometric Determination of Simvastain in ...

    African Journals Online (AJOL)

    This study is aimed at describing an accurate, robust and reproducible ultraviolet spectrophotometric technique for the determination of simvastain in bulk and pharmaceutical dosage formulations. Samples from three different brands of simvastatin 10mg were selected for the study. Different aliquots were taken from the ...

  8. Photodiode-Based, Passive Ultraviolet Dosimeters

    Science.gov (United States)

    Vaughn, Jason A.; Gray, Perry

    2004-01-01

    Simple, passive instruments have been developed for measuring the exposure of material specimens to vacuum ultraviolet (VUV) radiation from the Sun. Each instrument contains a silicon photodiode and a coulometer. The photocharge generated in the photodiode is stored in the coulometer. The accumulated electric charge measured by use of the coulometer is assumed to be proportional to the cumulative dose of VUV radiation expressed in such convenient units as equivalent Sun hours (ESH) [defined as the number of hours of exposure to sunlight at normal incidence]. Intended originally for use aboard spacecraft, these instruments could also be adapted to such terrestrial uses as monitoring the curing of ultraviolet-curable epoxies. Each instrument includes a photodiode and a coulometer assembly mounted on an interface plate (see figure). The photodiode assembly includes an aluminum housing that holds the photodiode, a poly(tetrafluoroehylene) cosine receptor, and a narrow-band optical filter. The cosine receptor ensures that the angular response of the instrument approximates the ideal angular response (proportional to the cosine of the angle of incidence). The filter is chosen to pass the ultraviolet wavelength of interest in a specific experiment. The photodiode is electrically connected to the coulometer. The factor of proportionality between the charge stored in the coulometer and ultraviolet dosage (in units of ESH) is established, prior to use, in calibration experiments that involve the use of lamps and current sources traceable to the National Institute of Standards and Technology.

  9. Urban tree influences on ultraviolet irradiance

    Science.gov (United States)

    Gordon M. Heisler; Richard H. Grant; Wei Gao

    2002-01-01

    Many of the effects of ultraviolet radiation (UVR) on people and their environment - damage to various materials, survival of insects and microbial pathogens, growth of vegetation, and adverse or beneficial effects on human health - are modified by the presence of trees. Human epidemiological investigations generally consider exposure as given by indices of UVR...

  10. Ultraviolet-Visible Spectroscopic Evaluation of Complexation ...

    African Journals Online (AJOL)

    Some complexes of crude methanol extract of Loranthus micranthus Linn parasitic on Kola acuminata were evaluated using ultraviolet-visible absorption spectrophotometry. The crude methanol extract was complexed with ferric chloride solution, borate mixture, methanolic aluminum nitrate and aluminum chloride solutions ...

  11. Ultraviolet Radiation: Human Exposure and Health Risks.

    Science.gov (United States)

    Tenkate, Thomas D.

    1998-01-01

    Provides an overview of human exposure to ultraviolet radiation and associated health effects as well as risk estimates for acute and chronic conditions resulting from such exposure. Demonstrates substantial reductions in health risk that can be achieved through preventive actions. Also includes a risk assessment model for skin cancer. Contains 36…

  12. Fine Forecasts: Encouraging the Media to Include Ultraviolet Radiation Information in Summertime Weather Forecasts

    Science.gov (United States)

    Richards, R.; Reeder, A. I.; Bulliard, J.-L.

    2004-01-01

    Melanoma and skin cancer are largely attributable to over-exposure to solar ultraviolet radiation (UVR). Reports of UVR levels within media weather forecasts appear to be well received by the public and have good potential to communicate the need for appropriate sun protection to a broad audience. This study describes provision of UVR messages by…

  13. Ultraviolet radiation and primary productivity in temperate aquatic environments of Patagonia (Argentina)

    NARCIS (Netherlands)

    Villafañe, Virginia

    2004-01-01

    Numerous studies carried out since the discovery of the ozone “hole” over the Antarctic continent have motivated photobiological research to determine the potential effects of increased solar ultraviolet radiation – UV-B (280-315 nm) on organisms and ecosystems. Since then, the amount of literature

  14. Ultraviolet Light Emitting Diodes Employing Nanoscale Compositional Inhomogeneities: A New Approach for Transforming Army Ultraviolet Applications

    National Research Council Canada - National Science Library

    Sampath, A. V; Garrett, G. A; Reed, M. L; Readinger, E. D; Wraback, M; Chua, C; Johnson, N. M

    2006-01-01

    Nitride semiconductor ultraviolet optical sources offer the possibility of compact, light-weight, low-cost, low-power-consumption optoelectronic sensors that would enable a new generation of fieldable...

  15. New advances in protection against solar ultraviolet radiation in textiles for summer clothing.

    Science.gov (United States)

    Aguilera, José; de Gálvez, María Victoria; Sánchez-Roldán, Cristina; Herrera-Ceballos, Enrique

    2014-01-01

    Clothing is considered one of the most important tools for photoprotection against harmful solar ultraviolet radiation (UVR). The standard for sun-protective clothing is based on erythema despite other biological effects of UVR on the skin. We analyzed the potential protection against UVR in fabrics destined for summer clothing based on several action spectra. We examined 50 garments classified by type of fabric composition, structure of the fiber yarn and color. The ultraviolet protection factor was calculated based on fabric ultraviolet transmittance corrected for erythema according to the EU standard E-13758 as well as the UVA transmittance of fabrics. UVR protection was also analyzed in base of different action spectra as for previtamin D3, nonmelanoma skin cancer, photoimmunosuppression and photoaging. Most knitted fabrics used for sports T-shirts offered excellent ratings for ultraviolet protection while normal shirts showed very low ratings, particularly against photoaging. The cover is the most influential variable in fabric photoprotection, having an exponential relationship with the UPF. The relation between cover and UVA protection was linearly negative. Information about ultraviolet protection in textiles used for summer clothing should be included in labeling as some types of fabrics, especially those used for shirts, offer very low UVR protection. © 2014 The American Society of Photobiology.

  16. 40 CFR 1065.272 - Nondispersive ultraviolet analyzer.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Nondispersive ultraviolet analyzer. 1065.272 Section 1065.272 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Nondispersive ultraviolet analyzer. (a) Application. You may use a nondispersive ultraviolet (NDUV) analyzer to...

  17. 21 CFR 872.6070 - Ultraviolet activator for polymerization.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultraviolet activator for polymerization. 872.6070... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6070 Ultraviolet activator for polymerization. (a) Identification. An ultraviolet activator for polymerization is a device that produces...

  18. Ultraviolet Keratitis: From the Pathophysiological Basis to Prevention and Clinical Management.

    Science.gov (United States)

    Willmann, Gabriel

    2015-12-01

    Ultraviolet keratitis is caused by the toxic effects of acute high-dose ultraviolet radiation (UVR) reflecting the sensitivity of the ocular surface to photochemical injury. The clinical syndrome presents with ocular pain, tearing, conjunctival chemosis, blepharospasm, and deterioration of vision typically several hours after exposure, lasting up to 3 days. Mountaineers, skiers, and beach recreationalists are particularly at risk to suffer from ultraviolet (UV) keratitis as the reflectivity of UVR in these environments is extremely high. The aim of this review is to raise awareness about the potential of UV damage on the eye with an emphasis on UV keratitis, to highlight the pathophysiological basis of corneal phototoxicity, and to provide practical guidance for the prevention and clinical management of UV keratitis commonly known as snow blindness.

  19. Pollen and spores as a passive monitor of ultraviolet radiation

    Directory of Open Access Journals (Sweden)

    Wesley Toby Fraser

    2014-04-01

    Full Text Available Sporopollenin is the primary component of the outer walls of pollen and spores. The chemical composition of sporopollenin is responsive to levels of ultraviolet (UV radiation exposure, via a concomitant change in the concentration of phenolic compounds. This relationship offers the possibility of using fossil pollen and spore chemistry as a novel proxy for past UV flux. Phenolic compounds in sporopollenin can be quantified using Fourier Transform infrared spectroscopy. The high potential for preservation of pollen and spores in the geologic record, and the conservative nature of sporopollenin chemistry across the land plant phylogeny, means that this new proxy has the potential to reconstruct UV flux over much longer timescales than has previously been possible. This new tool has important implications for understanding the relationship between UV flux, solar insolation and climate in the past, as well as providing a possible means of assessing paleoaltitude, and ozone thickness.

  20. Photochemoprevention of ultraviolet B signaling and photocarcinogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Afaq, Farrukh [Department of Dermatology, University of Wisconsin, Medical Sciences Center, Room B25, 1300 University Avenue, Madison, WI 53706 (United States); Adhami, Vaqar M. [Department of Dermatology, University of Wisconsin, Medical Sciences Center, Room B25, 1300 University Avenue, Madison, WI 53706 (United States); Mukhtar, Hasan [Department of Dermatology, University of Wisconsin, Medical Sciences Center, Room B25, 1300 University Avenue, Madison, WI 53706 (United States)]. E-mail: hmukhtar@wisc.edu

    2005-04-01

    Exposure to solar radiation, particularly its ultraviolet (UV) B component, has a variety of harmful effects on human health. Some of these effects include sunburn cell formation, basal and squamous cell cancers, melanoma, cataracts, photoaging of the skin, and immune suppression. Amongst these various adverse effects of UV radiation, skin cancer is of the greatest concern. Over the years, changes in lifestyle has led to a significant increase in the amount of UV radiation that people receive, and this consequently has led to a surge in the incidence of skin cancer. The development of skin cancer is a complex multistage phenomenon involving three distinct stages exemplified by initiation, promotion and progression stages. Each of these stages is mediated via alterations in various cellular, biochemical, and molecular changes. Initiation, the first step in the carcinogenesis process is essentially an irreversible step in which genetic alterations occur in genes that ultimately leads to DNA modification and fixation of mutation. Tumor promotion is the essential process in cancer development involving clonal expansion of initiated cells giving rise to pre-malignant and then to malignant lesions, essentially by alterations in signal transduction pathways. Tumor progression involves the conversion of pre-malignant and malignant lesions into an invasive and potentially metastatic malignant tumor. All these processes for skin cancer development involve stimulation of DNA synthesis, DNA damage and proliferation, inflammation, immunosuppression, epidermal hyperplasia, cell cycle dysregulation, depletion of antioxidant defenses, impairment of signal transduction pathways, induction of cyclooxygenase, increase in prostaglandin synthesis, and induction of ornithine decarboxylase. Photochemoprevention has been appreciated as a viable approach to reduce the occurrence of skin cancer and in recent years, the use of agents, especially botanical antioxidants, present in the common

  1. Seeing Core-Collapse Supernovae in the Ultraviolet

    Science.gov (United States)

    Brown, Peter

    Core-collapse supernovae are the catastrophic deaths of massive stars. Ultraviolet observations are needed to understand the energy of the explosion through the study of the bolometric light curves. Early-time ultraviolet observations constrain the size of the progenitor. Ultraviolet spectra can break the degeneracies between temperature/ionization, reddening, and metallicity which hinder our understanding of ultraviolet photometry. Optical observations of high-redshift supernovae probe rest-frame ultraviolet wavelengths, requiring space-based observations of nearby supernovae against which to compare. Ultraviolet observations of core-collapse supernovae can also help distinguish them from type Ia supernovae, enabling cleaner photometric type Ia supernova samples for cosmological measurements. The Ultraviolet/Optical Telescope (UVOT) on the Swift satellite has observed over two hundred core-collapse supernovae in the ultraviolet, including sixty-nine ultraviolet grism spectra of twenty core-collapse SNe. Additional ultraviolet spectra have been obtained by the International Ultraviolet Explorer, Hubble Space Telescope, and Galaxy Evolution Explorer. We propose a project to reduce the Swift grism spectra and combine with the other ultraviolet and groundbased optical/NIR spectra to create time-series bolometric spectra. We will use these bolometric spectra to better understand temperature, reddening, and metallicity and create bolometric light curves of these core collapse SNe. We will also use early time ultraviolet photometry and spectroscopy to constrain the progenitors of core collapse SNe. The ultraviolet observations fill a critical niche in our understanding of core collapse supernovae, and this program will enhance the scientific use of this important dataset from multiple space missions. Beyond core-collapse supernovae, the templates will allow studies of the dust properties around the progenitor systems (including the wavelength dependence of the extinction

  2. Effective polycrystalline sensor of ultraviolet radiation

    Directory of Open Access Journals (Sweden)

    S.Yu. Pavelets

    2017-10-01

    Full Text Available Deposition of special thin layers with high and low resistance in space charge region of surface barrier photoconverters based on the p-Cu1.8S/n-CdS structure leads to a sufficient increase in photosensitivity and decrease in dark tunneling-recombination current. Highly efficient and stable polycrystalline photoconverters of ultraviolet radiation based on polycrystalline CdS have been obtained. Electrical and photoelectric properties have been investigated, and the main operational parameters of ultraviolet sensors have been adduced. The reasons for high stability of the parameters inherent to the p-Cu1.8S/n-CdS sensors are as follows: the absence of impurity components additionally doped to the barrier structure and stability of the photocurrent photoemission component.

  3. Contact lens disinfection by ultraviolet light

    Energy Technology Data Exchange (ETDEWEB)

    Dolman, P.J.; Dobrogowski, M.J. (Univ. of British Columbia, Vancouver (Canada))

    1989-12-15

    A 253.7-nm ultraviolet light with an intensity of 1,100 microW/cm2 was tested for its germicidal activity against contact lenses and storage solutions contaminated with various corneal pathogens. The exposure time necessary to reduce a concentration of organisms from 10(6)/ml to less than 10/ml was 30 seconds for Staphylococcus aureus, 60 seconds for Pseudomonas aeruginosa, and 84 seconds for Candida albicans. The time necessary to sterilize a suspension of 10(4)/ml Acanthamoeba polyphaga was less than three minutes with this technique. Four brands of soft contact lenses were exposed to ultraviolet light for over eight hours without changing their appearance, comfort, or refraction.

  4. Knowledge about Ultraviolet Radiation Hazards and Tanning Behavior of Cosmetology and Medical Students.

    Science.gov (United States)

    Zuba, Ewelina Bogumiła; Francuzik, Wojciech; Malicki, Przemysław; Osmola-Mańkowska, Agnieszka; Jenerowicz, Dorota

    2016-04-01

    Dear Editor, Ultraviolet (UV) radiation is a well-known physical hazard responsible for photoaging, photoallergic, and phototoxic reactions as well as carcinogenesis, including life-threatening melanomas (1,2). Overexposure to both natural and artificial UV radiation is a public health concern. 30% of cancers diagnosed worldwide are skin cancers. Approximately three million non-melanoma skin cancers and 132 000 new cases of melanomas are diagnosed globally each year (3). Sunburns, especially in childhood, are a very important risk factor for melanomas. Several studies demonstrated a positive association between sunbed use and an increased incidence of malignant melanoma (4). Current medical and cosmetology students will soon be knowledge providers about the risks of excessive exposure to UV radiation and prophylaxis of its consequences. Our aim was to evaluate their knowledge about the side effects of ultraviolet radiation and tanning behaviors. Details on the knowledge and habits of students were obtained during classes at the Poznan University of Medical Sciences. With approval from the Institutional Bioethical Committee, a 41-question anonymous survey was conducted in the spring of 2012 among 190 medical (1-6 year) and cosmetology students (1-5 year). The mean age of the study group was 22.3 years (standard deviation (SD) = 2.4 years), range 19-28 years. The survey was composed of closed and open-ended questions prepared by the authors. The first part of the form included demographic data: gender, age, degree course, and school year. The students were also asked about their reaction to sunlight, sunburns in childhood, and personal and family history of skin cancers or dysplastic nevus syndrome. The factual section of the survey contained questions evaluating responder knowledge about sunbeds and risk of UV radiation as well as their personal tanning habits. The open-ended questions asked responders to provide definitions of: skin phototype, sun protection factor

  5. Diagnosis of Dentin Caries – Ultraviolet Fluorescence

    OpenAIRE

    Uzunov Ts.; Uzunov T.; Grozdanova R.; Kosturkov D.

    2014-01-01

    The technology advance in recent years determines the need of construction of modern appliances for early diagnosis of dental caries, which are categorized by great precision, non-invasiveness, easy usage and wide availability. Such non-invasive and accurate tool for diagnostics of caries is Caries Detector (LED), Bulgarian product by “Optica Laser”. The detector emits a specific wavelength of near ultraviolet light, which causes fluorescence to porphyrins - metabolic products of the life cyc...

  6. Large-Area Vacuum Ultraviolet Sensors

    Science.gov (United States)

    Aslam, Shahid; Franz, David

    2012-01-01

    Pt/(n-doped GaN) Schottky-barrier diodes having active areas as large as 1 cm square have been designed and fabricated as prototypes of photodetectors for the vacuum ultraviolet portion (wavelengths approximately equal 200 nm) of the solar spectrum. In addition to having adequate sensitivity to photons in this wavelength range, these photodetectors are required to be insensitive to visible and infrared components of sunlight and to have relatively low levels of dark current.

  7. Photoprotection of human skin beyond ultraviolet radiation.

    Science.gov (United States)

    Grether-Beck, Susanne; Marini, Alessandra; Jaenicke, Thomas; Krutmann, Jean

    2014-01-01

    Photoprotection of human skin by means of sunscreens or daily skin-care products is traditionally centered around the prevention of acute (e.g. sunburn) and chronic (e.g. skin cancer and photoaging) skin damage that may result from exposure to ultraviolet rays (UVB and UVA). Within the last decade, however, it has been appreciated that wavelengths beyond the ultraviolet spectrum, in particular visible light and infrared radiation, contribute to skin damage in general and photoaging of human skin in particular. As a consequence, attempts have been made to develop skin care/sunscreen products that not only protect against UVB or UVA radiation but provide photoprotection against visible light and infrared radiation as well. In this article, we will briefly review the current knowledge about the mechanisms responsible for visible light/infrared radiation-induced skin damage and then, based on this information, discuss strategies that have been successfully used or may be employed in the future to achieve photoprotection of human skin beyond ultraviolet radiation. In this regard we will particularly focus on the use of topical antioxidants and the challenges that result from the task of showing their efficacy. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  8. Ultraviolet television data from the orbiting astronomical observatory. II - Stellar ultraviolet colors and interstellar extinction

    Science.gov (United States)

    Peytremann, E.; Davis, R. J.

    1974-01-01

    The results from the Celescope Catalog of Ultraviolet Stellar Observations (Davis, Deutschman, and Haramundanis 1973) are studied, emphasizing statistical groups and subgroups of stars. In spite of the rather large observational errors, the great number of Celescope observations make it possible to do that kind of study with reasonable accuracy. Some stars have ultraviolet colors that differ significantly from those of the group to which they have been assigned on the basis of ground-based observations. An attempt is made to describe the general properties of the ultraviolet colors of the stars as observed by the Celescope experiment on board NASA's Orbiting Astronomical Observatory (OAO-2). Besides the direct applicability of these results to the general study of stellar atmospheres and of interstellar extinction, they are also considered as a frame of reference for further studies of individual stars and groups of stars.

  9. Far-ultraviolet spectral changes of titanium dioxide with gold nanoparticles by ultraviolet and visible light.

    Science.gov (United States)

    Tanabe, Ichiro; Kurawaki, Yuji

    2017-11-07

    Attenuated total reflectance spectra including the far-ultraviolet (FUV, ≤200nm) region of titanium dioxide (TiO2) with and without gold (Au) nanoparticles were measured. A newly developed external light-irradiation system enabled to observe spectral changes of TiO2 with Au nanoparticles upon light irradiations. Absorption in the FUV region decreased and increased by the irradiation with ultraviolet and visible light, respectively. These spectral changes may reflect photo-induced electron transfer from TiO2 to Au nanoparticles under ultraviolet light and from Au nanoparticles to TiO2 under visible light, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Inactivation of Pseudomonas aeruginosa biofilm after ultraviolet light-emitting diode treatment: a comparative study between ultraviolet C and ultraviolet B

    DEFF Research Database (Denmark)

    Argyraki, Aikaterini; Markvart, Merete; Bjørndal, Lars

    2017-01-01

    The objective of this study was to test the inactivation efficiency of two different light-based treatments, namely ultraviolet B (UVB) and ultraviolet C (UVC) irradiation, on Pseudomonas aeruginosa biofilms at different growth stages (24, 48, and 72 h grown). In our experiments, a type of Al...

  11. Ultraviolet light absorption of an ophthalmic formulation with Aloe extracts.

    Science.gov (United States)

    Ji, Yimei; Jia, Jicheng

    2009-09-01

    Aloin and polysaccharide present in extracts of Aloe arborescens Miller were formulated into a binary solution to protect eyes from bacterial infection and ultraviolet radiation (UVR). The UVR absorption spectrum was recorded from 190 to 440 nm using a UV spectrometer. The physical properties of the product were examined in terms of its appearance, odor, pH, viscosity, density, refractive index, and stability. The binary solution exhibited three absorption peaks in the UVA, B and C regions, respectively. Such UV absorption capability was attributed to the phenolic chromophores pertaining to aloin. The present study suggested that the formulated binary solution has potential application as an UV absorption agent with built-in antimicrobial activity.

  12. Disinfection Effect of Film Cassettes by Ultraviolet Irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kweon, Dae Cheol; Park, Peom [Ajou Univ., Suwon (Korea, Republic of)

    2001-12-15

    A bacteria infection on film cassette contact surface was examined at the diagnostic radiology department. Studies have demonstrated a bactericidal effect of ultraviolet irradiation, and to assess the contamination level on film cassette contact surface as a predictor of patient prevent from nosocomial infection. The study showed that the laboratory result was identified non-pathologic and pathologic bacterial in the five different cassette size of the contact surface. Film cassettes were exposed to ultraviolet light for 1, 2 and 3 minutes. Ultraviolet light disinfection practices suitable for bacteria. The study concludes that presence of a bacterial infection will prevent a using antiseptic technique on film cassette contact surface. In conclusion, ultraviolet irradiate on film cassette over the surface more than 2 minutes. Ultraviolet dose of 1565 {mu}W {center_dot} s/cm{sup 2}Win in 30 second relative to ultraviolet dose in time.

  13. Femtosecond Amplifiers and Microlasers in the Deep Ultraviolet

    Science.gov (United States)

    2013-11-19

    the ultraviolet (UV) and visible regions of the spectrum, as well as their applications in photochemistry and medical therapeutics. We believe that...FEMTOSECOND AMPLIFIERS AND MICROLASERS IN DEEP ULTRAVIOLET J GARY EDEN UNIVERSITY OF ILLINOIS 11/19/2013 Final Report DISTRIBUTION A: Distribution...Performance Report 15/08/2010 - 14/08/2013 Femtosecond Amplifiers and Microlasers in the Deep Ultraviolet FA9550-10-1-0456 Eden, James Gary Professor

  14. Nanophase iron oxides as a key ultraviolet sunscreen for ancient photosynthetic microbes

    Science.gov (United States)

    Bishop, Janice L.; Louris, Stephanie K.; Rogoff, Dana A.; Rothschild, Lynn J.

    2006-07-01

    We propose that nanophase iron-oxide-bearing materials provided important niches for ancient photosynthetic microbes on the Earth that ultimately led to the oxygenation of the Earth's atmosphere and the formation of iron-oxide deposits. Atmospheric oxygen and ozone attenuate ultraviolet radiation on the Earth today providing substantial protection for photosynthetic organisms. With ultraviolet radiation fluxes likely to have been even higher on the early Earth than today, accessing solar radiation was particularly risky for early organisms. Yet, we know that photosynthesis arose early and played a critical role in subsequent evolution. Of primary importance was protection below 290 nm, where peak nucleic acid (~260 nm) and protein (~280 nm) absorptions occur. Nanophase ferric oxide/oxyhydroxide minerals absorb, and thus block, the lethal ultraviolet radiation, while transmitting light through much of the visible and near-infrared regions of interest to photosynthesis (400 to 1100 nm). Furthermore, they were available in early environments, and are synthesized by many organisms. Based on experiments using nanophase ferric oxide/oxyhydroxide minerals as a sunscreen for photosynthetic microbes, we suggest that iron, an abundant element widely used in biological mechanisms, may have provided the protection that early organisms needed in order to be able to use photosynthetically active radiation while being protected from ultraviolet-induced damage. The results of this study are broadly applicable to astrobiology because of the abundance of iron in other potentially habitable bodies and the evolutionary pressure to utilize solar radiation when available as an energy source. This model could apply to a potential life form on Mars or other bodies where liquid water and ultraviolet radiation could have been present at significant levels. Based on ferric oxide/oxyhydroxide spectral properties, likely geologic processes, and the results of experiments with the

  15. The Hopkins Ultraviolet Telescope: The Final Archive

    Science.gov (United States)

    Dixon, William V.; Blair, William P.; Kruk, Jeffrey W.; Romelfanger, Mary L.

    2013-01-01

    The Hopkins Ultraviolet Telescope (HUT) was a 0.9 m telescope and moderate-resolution (Delta)lambda equals 3 A) far-ultraviolet (820-1850 Å) spectrograph that flew twice on the space shuttle, in 1990 December (Astro-1, STS-35) and 1995 March (Astro-2, STS-67). The resulting spectra were originally archived in a nonstandard format that lacked important descriptive metadata. To increase their utility, we have modified the original datareduction software to produce a new and more user-friendly data product, a time-tagged photon list similar in format to the Intermediate Data Files (IDFs) produced by the Far Ultraviolet Spectroscopic Explorer calibration pipeline. We have transferred all relevant pointing and instrument-status information from locally-archived science and engineering databases into new FITS header keywords for each data set. Using this new pipeline, we have reprocessed the entire HUT archive from both missions, producing a new set of calibrated spectral products in a modern FITS format that is fully compliant with Virtual Observatory requirements. For each exposure, we have generated quicklook plots of the fully-calibrated spectrum and associated pointing history information. Finally, we have retrieved from our archives HUT TV guider images, which provide information on aperture positioning relative to guide stars, and converted them into FITS-format image files. All of these new data products are available in the new HUT section of the Mikulski Archive for Space Telescopes (MAST), along with historical and reference documents from both missions. In this article, we document the improved data-processing steps applied to the data and show examples of the new data products.

  16. In-orbit Calibrations of the Ultraviolet Imaging Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Tandon, S. N. [Inter-University Center for Astronomy and Astrophysics, Pune (India); Subramaniam, Annapurni; Sankarasubramanian, K.; Sriram, S.; Stalin, C. S.; Mondal, C.; Sahu, S.; Joseph, P.; Barve, I. V.; George, K.; Kamath, P. U.; Kathiravan, S.; Kumar, A.; Lancelot, J. P.; Mahesh, P. K. [Indian Institute of Astrophysics, Koramangala II Block, Bangalore-560034 (India); Girish, V. [ISRO Satellite Centre, HAL Airport Road, Bangalore 560017 (India); Postma, J.; Leahy, D. [University of Calgary, 2500 University Drive NW, Calgary, Alberta Canada (Canada); Hutchings, J. [National Research Council of Canada, Herzberg Astronomy and Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Ghosh, S. K., E-mail: purni@iiap.res.in [National Centre for Radio Astrophysics, Pune (India); and others

    2017-09-01

    The Ultra-Violet Imaging Telescope (UVIT) is one of the payloads in ASTROSAT, the first Indian Space Observatory. The UVIT instrument has two 375 mm telescopes: one for the far-ultraviolet (FUV) channel (1300–1800 Å), and the other for the near-ultraviolet (NUV) channel (2000–3000 Å) and the visible (VIS) channel (3200–5500 Å). UVIT is primarily designed for simultaneous imaging in the two ultraviolet channels with spatial resolution better than 1.″8, along with provisions for slit-less spectroscopy in the NUV and FUV channels. The results of in-orbit calibrations of UVIT are presented in this paper.

  17. Ultraviolet spectrophotometer for measuring columnar atmospheric ozone from aircraft

    Science.gov (United States)

    Hanser, F. A.; Sellers, B.; Briehl, D. C.

    1978-01-01

    An ultraviolet spectrophotometer (UVS) to measure downward solar fluxes from an aircraft or other high altitude platform is described. The UVS uses an ultraviolet diffuser to obtain large angular response with no aiming requirement, a twelve-position filter wheel with narrow (2-nm) and broad (20-nm) bandpass filters, and an ultraviolet photodiode. The columnar atmospheric ozone above the UVS (aircraft) is calculated from the ratios of the measured ultraviolet fluxes. Comparison with some Dobson station measurements gives agreement to 2%. Some UVS measured ozone profiles over the Pacific Ocean for November 1976 are shown to illustrate the instrument's performance.

  18. Effect and mechanism of microwave-activated ultraviolet-advanced oxidation technology for adsorbent regeneration.

    Science.gov (United States)

    Sun, Yanlong; Zheng, Tong; Zhang, Guangshan; Zheng, Yunli; Wang, Peng

    2017-10-15

    To decrease the secondary pollution of volatile organic compounds (VOCs) during adsorbent regeneration by microwave, electrodeless lamp was added in the microwave field to oxidize VOCs in the gas phase. Ultraviolet has a significant improvement on mineralization of VOCs generated from adsorbate during adsorbent regeneration. However, the mechanism and main influence factors on the degradation of VOCs are not clear. The effect of microwave power, regeneration time, airflow rate, and humidity content on the mineralization of adsorbed tetracycline during adsorbent regeneration was studied. Ozone concentration and ultraviolet irradiation intensity were also measured to analyze the mechanism of the microwave-ultraviolet adsorbent regeneration method. Although the electrodeless lamp adsorbed microwave and competed with the regenerated adsorbent, the mineralization percentage of tetracycline increased about 10% with the presence of electrodeless lamp at the same microwave power supply. Besides, humidity content also takes an important role on enhancing the mineralization of tetracycline. The mineralization of tetracycline in the microwave-ultraviolet field consists of three major parts: pyrolysis, ozone oxidation, and free radical oxidation. More than 50% adsorbed tetracycline can be oxidized into H2O and CO2 during regeneration in 5 min. These results support the potential use of electrodeless lamp to treat VOCs in the gas phase to decrease the risk of secondary pollution during adsorbent regeneration.

  19. Lowered ultraviolet minimal erythema dose in hemiplegia.

    Science.gov (United States)

    Cox, N. H.; Williams, S. J.

    1985-01-01

    In view of recent reports of increased tanning in hemiplegic limbs, we have investigated ultraviolet (u.v.) minimal erythema dose (MED) in hemiplegia using the bilateral comparison technique. Seven of 10 patients had a lower MED in the hemiplegic arm compared to the normal side, the mean reduction being 16% (range 0-33%, P = 0.003). No patients had a higher MED in the hemiplegic arm. We review the literature regarding other non-neurological features of hemiplegia, in particular asymmetry of temperature, oedema, and finger clubbing, and we propose a vasomotor or trophic aetiology for these findings. PMID:4022889

  20. Far ultraviolet spectrophotometry of BD +28 4211

    Science.gov (United States)

    Cook, Timothy A.; Cash, Webster; Green, James C.

    1991-01-01

    The results are reported of a November 1989 rocket flight which recorded a flux-calibrated spectrum of BD +28 4211 from 912 to 1150 A with 1A resolution. BD +28 4211, an SdO-type star, is commonly used as an ultraviolet calibration source in the IUE wavelength band. The present work extends the useful range of this standard shortward of Lyman-alpha. Since previous experiments show marked disparity, this study can be useful in determining a standard in the 912 to 1216 A band.

  1. Ultraviolet radiation, vitamin D and multiple sclerosis.

    Science.gov (United States)

    Lucas, Robyn M; Byrne, Scott N; Correale, Jorge; Ilschner, Susanne; Hart, Prue H

    2015-10-01

    There is compelling epidemiological evidence that the risk of developing multiple sclerosis is increased in association with low levels of sun exposure, possibly because this is associated with low vitamin D status. Recent work highlights both vitamin D and non-vitamin D effects on cellular immunity that suggests that higher levels of sun exposure and/or vitamin D status are beneficial for both MS risk and in ameliorating disease progression. Here we review this recent evidence, focusing on regulatory cells, dendritic cells, and chemokines and cytokines released from the skin following exposure to ultraviolet radiation.

  2. Jupiter in blue, ultraviolet and near infrared

    Science.gov (United States)

    2000-01-01

    These three images of Jupiter, taken through the narrow angle camera of NASA's Cassini spacecraft from a distance of 77.6 million kilometers (48.2 million miles) on October 8, reveal more than is apparent to the naked eye through a telescope.The image on the left was taken through the blue filter. The one in the middle was taken in the ultraviolet. The one on the right was taken in the near infrared.The blue-light filter is within the part of the electromagnetic spectrum detectable by the human eye. The appearance of Jupiter in this image is, consequently, very familiar. The Great Red Spot (below and to the right of center) and the planet's well-known banded cloud lanes are obvious. The brighter bands of clouds are called zones and are probably composed of ammonia ice particles. The darker bands are called belts and are made dark by particles of unknown composition intermixed with the ammonia ice.Jupiter's appearance changes dramatically in the ultraviolet and near infrared images. These images are near negatives of each other and illustrate the way in which observations in different wavelength regions can reveal different physical regimes on the planet.All gases scatter sunlight efficiently at short wavelengths; this is why the sky appears blue on Earth. The effect is even more pronounced in the ultraviolet. The gases in Jupiter's atmosphere, above the clouds, are no different. They scatter strongly in the ultraviolet, making the deep banded cloud layers invisible in the middle image. Only the very high altitude haze appears dark against the bright background. The contrast is reversed in the near infrared, where methane gas, abundant on Jupiter but not on Earth, is strongly absorbing and therefore appears dark. Again the deep clouds are invisible, but now the high altitude haze appears relatively bright against the dark background. High altitude haze is seen over the poles and the equator.The Great Red Spot, prominent in all images, is obviously a feature whose

  3. ULTRAVIOLET PROTECTIVE PIGMENTS AND DNA DIMER INDUCTION AS RESPONSES TO ULTRAVIOLET RADIATION

    Science.gov (United States)

    Life on Earth has evolved adaptations to many environmental stresses over the epochs. One consistent stress has been exposure to ultraviolet (UV) radiation. The most basic effect of UV radiation on biological systems is damage to DNA. In response to UV radiation organisms have ad...

  4. The Ultraviolet Spectrograph on NASA's Juno Mission

    Science.gov (United States)

    Gladstone, G. Randall; Persyn, Steven C.; Eterno, John S.; Walther, Brandon C.; Slater, David C.; Davis, Michael W.; Versteeg, Maarten H.; Persson, Kristian B.; Young, Michael K.; Dirks, Gregory J.; Sawka, Anthony O.; Tumlinson, Jessica; Sykes, Henry; Beshears, John; Rhoad, Cherie L.; Cravens, James P.; Winters, Gregory S.; Klar, Robert A.; Lockhart, Walter; Piepgrass, Benjamin M.; Greathouse, Thomas K.; Trantham, Bradley J.; Wilcox, Philip M.; Jackson, Matthew W.; Siegmund, Oswald H. W.; Vallerga, John V.; Raffanti, Rick; Martin, Adrian; Gérard, J.-C.; Grodent, Denis C.; Bonfond, Bertrand; Marquet, Benoit; Denis, François

    2017-11-01

    The ultraviolet spectrograph instrument on the Juno mission (Juno-UVS) is a long-slit imaging spectrograph designed to observe and characterize Jupiter's far-ultraviolet (FUV) auroral emissions. These observations will be coordinated and correlated with those from Juno's other remote sensing instruments and used to place in situ measurements made by Juno's particles and fields instruments into a global context, relating the local data with events occurring in more distant regions of Jupiter's magnetosphere. Juno-UVS is based on a series of imaging FUV spectrographs currently in flight—the two Alice instruments on the Rosetta and New Horizons missions, and the Lyman Alpha Mapping Project on the Lunar Reconnaissance Orbiter mission. However, Juno-UVS has several important modifications, including (1) a scan mirror (for targeting specific auroral features), (2) extensive shielding (for mitigation of electronics and data quality degradation by energetic particles), and (3) a cross delay line microchannel plate detector (for both faster photon counting and improved spatial resolution). This paper describes the science objectives, design, and initial performance of the Juno-UVS.

  5. Ultraviolet Resonant Raman Enhancements in the Detection of Explosives

    Energy Technology Data Exchange (ETDEWEB)

    Short Jr., Billy Joe [Naval Postgraduate School, Monterey, CA (United States)

    2009-06-01

    Raman-based spectroscopy is potentially militarily useful for standoff detection of high explosives. Normal (non-resonance) and resonance Raman spectroscopies are both light scattering techniques that use a laser to measure the vibrational spectrum of a sample. In resonance Raman, the laser is tuned to match the wavelength of a strong electronic absorbance in the molecule of interest, whereas, in normal Raman the laser is not tuned to any strong electronic absorbance bands. The selection of appropriate excitation wavelengths in resonance Raman can result in a dramatic increase in the Raman scattering efficiency of select band(s) associated with the electronic transition. Other than the excitation wavelength, however, resonance Raman is performed experimentally the same as normal Raman. In these studies, normal and resonance Raman spectral signatures of select solid high explosive (HE) samples and explosive precursors were collected at 785 nm, 244 nm and 229 nm. Solutions of PETN, TNT, and explosive precursors (DNT & PNT) in acetonitrile solvent as an internal Raman standard were quantitatively evaluated using ultraviolet resonance Raman (UVRR) microscopy and normal Raman spectroscopy as a function of power and select excitation wavelengths. Use of an internal standard allowed resonance enhancements to be estimated at 229 nm and 244 nm. Investigations demonstrated that UVRR provided ~2000-fold enhancement at 244 nm and ~800-fold improvement at 229 nm while PETN showed a maximum of ~25-fold at 244 nm and ~190-fold enhancement at 229 nm solely from resonance effects when compared to normal Raman measurements. In addition to the observed resonance enhancements, additional Raman signal enhancements are obtained with ultraviolet excitation (i.e., Raman scattering scales as !4 for measurements based on scattered photons). A model, based partly on the resonance Raman enhancement results for HE solutions, is presented for estimating Raman enhancements for solid HE samples.

  6. Inactivation of Zika virus in platelet components using amotosalen and ultraviolet A illumination.

    Science.gov (United States)

    Santa Maria, Felicia; Laughhunn, Andrew; Lanteri, Marion C; Aubry, Maite; Musso, Didier; Stassinopoulos, Adonis

    2017-08-01

    Concerned over the risk of Zika virus (ZIKV) transfusion transmission, public health agencies recommended the implementation of mitigation strategies for its prevention. Those strategies included the use of pathogen inactivation for the treatment of plasma and platelets. The efficacy of amotosalen/ultraviolet A to inactivate ZIKV in plasma had been previously demonstrated, and the efficacy of inactivation in platelets with the same technology was assumed. These studies quantify ZIKV inactivation in platelet components using amotosalen/ultraviolet A. Platelet components were spiked with ZIKV, and ZIKV infectious titers and RNA loads were measured by cell culture-based assays and real-time polymerase chain reaction in spiked platelet components before and after photochemical treatment using amotosalen/ultraviolet A. The mean ZIKV infectivity titers and RNA loads in platelet components before inactivation were either 4.9 log10 plaque forming units per milliliter, or 4.4 log10 50% tissue culture infective dose per milliliter and 7.5 log10 genome equivalents per milliliter, respectively. No infectivity was detected immediately after amotosalen/ultraviolet A treatment. No replicative virus remained after treatment, as demonstrated by multiple passages on Vero cell cultures; and ZIKV RNA was not detected from the first passage after inactivation. Additional experiments in this study demonstrated efficient inactivation to the limit of detection in platelets manufactured in 65% platelet additive solution, 35% plasma, or 100% plasma. As previously demonstrated for plasma, robust levels of ZIKV inactivation were achieved in platelet components. With inactivation of higher levels of ZIKV than those reported in asymptomatic, RNA-reactive blood donors, the pathogen-inactivation system using amotosalen/ultraviolet A offers the potential to mitigate the risk of ZIKV transmission by plasma and platelet transfusion. © 2017 The Authors Transfusion published by Wiley Periodicals, Inc

  7. Ultraviolet Spectroscopic Study of BY Circini and V 1425 Aquilae ...

    Indian Academy of Sciences (India)

    Ultraviolet Spectroscopic Study of BY Circini and V 1425 Aquilae from IUE Satellite. M. R. Sanad. National Research Institute of Astronomy and Geophysics, Astronomy Department, Helwan,. Cairo, Egypt. e-mail: mrsanad1@yahoo.com. Received 7 July 2014; accepted 24 November 2014. Abstract. We present the ultraviolet ...

  8. Ultraviolet irradiation initiates ectopic foot formation in regenerating ...

    Indian Academy of Sciences (India)

    We have studied the effects of ultraviolet-C (UVC) and Ultraviolet-B (UVB) on growth and pattern formation in Pelmatohydra oligactis. UVC brings about a significant increase in budding in intact hydra while UVB does not exhibit such an effect. Excessive budding could be a response for survival at wavelengths that damage ...

  9. Ultraviolet Spectroscopic Study of BY Circini and V 1425 Aquilae ...

    Indian Academy of Sciences (India)

    We present the ultraviolet spectra of two classical novae, BY Circini 1995 and V1425 Aquilae 1995, using observations obtained with the International Ultraviolet Explorer (IUE). The outflow velocity of the ionized ejecta was calculated to be 2100–2700 km s-1 and 1600–1900 km s-1 (FWHM) for BY Cir and V1425 Aql, ...

  10. Ultraviolet Spectrum And Chemical Reactivity Of CIO Dimer

    Science.gov (United States)

    Demore, William B.; Tschuikow-Roux, E.

    1992-01-01

    Report describes experimental study of ultraviolet spectrum and chemical reactivity of dimer of chlorine monoxide (CIO). Objectives are to measure absorption cross sections of dimer at near-ultraviolet wavelengths; determine whether asymmetrical isomer (CIOCIO) exists at temperatures relevant to Antarctic stratosphere; and test for certain chemical reactions of dimer. Important in photochemistry of Antarctic stratosphere.

  11. Ultraviolet radiation, human health, and the urban forest

    Science.gov (United States)

    Gordon M. Heisler; Richard H. Grant

    2000-01-01

    Excess exposure to ultraviolet (UV) radiation from the sun, particularly the ultraviolet B (UVB) portion, has been linked with adverse effects on human health ranging from skin cancers to eye diseases such as cataracts. Trees may prevent even greater disease rates in humans by reducing UV exposure. Tree shade greatly reduces UV irradiance when both the sun and sky are...

  12. Effect of aerosols and NO2 concentration on ultraviolet actinic flux near Mexico City during MILAGRO: measurements and model calculations

    OpenAIRE

    G. G. Palancar; B. L. Lefer; Hall, S.R.; Shaw, W. J.; Corr, C. A.; S. C. Herndon; J. R. Slusser; Madronich, S.

    2013-01-01

    Urban air pollution absorbs and scatters solar ultraviolet (UV) radiation, and thus has a potentially large effect on tropospheric photochemical rates. We present the first detailed comparison between actinic fluxes (AF) in the wavelength range 330–420 nm measured in highly polluted conditions and simulated with the Tropospheric UltravioletVisible (TUV) model. Measurements were made during the MILAGRO campaign near Mexico City in March 2006, at a ground-based station near Mexico City (the T1 ...

  13. Photoluminescence performance of thulium doped Li{sub 4}SrCa(SiO{sub 4}){sub 2} under irradiation of ultraviolet and vacuum ultraviolet lights

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhaofeng [Department of Science Teaching, Gansu University of Traditional Chinese Medicine, Lanzhou 730000 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Li, Yezhou, E-mail: leelienzoey@gmail.com [Department of Science Teaching, Gansu University of Traditional Chinese Medicine, Lanzhou 730000 (China); Liu, Xiong; Wei, Xingmin; Chen, Yueling; Zhou, Fei [Department of Science Teaching, Gansu University of Traditional Chinese Medicine, Lanzhou 730000 (China); Wang, Yuhua [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)

    2014-11-15

    Highlights: • A novel blue-emitting phosphor Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} was reported. • Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} exhibited excellent thermal and irradiation stability. • Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} was found to possess high color purity. - Abstract: In this work, we synthesized Tm{sup 3+} doped Li{sub 4}SrCa(SiO{sub 4}){sub 2} phosphors and investigated their photoluminescence properties under the excitation of ultraviolet and vacuum ultraviolet lights. The crystal structure analysis and variation of cell parameters confirm that Tm{sup 3+} ions have been successfully doped in the structure of Li{sub 4}SrCa(SiO{sub 4}){sub 2} host by occupying the sites of Ca{sup 2+} with the coordination number of 6. The luminescence results suggest that Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} is a good blue-emitting phosphor when excited by ultraviolet and vacuum ultraviolet irradiations. In addition, it is observed that there is nearly no degradation for Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} after undergoing thermal and irradiation treatments. Possible mechanisms for the luminescence processes are proposed on the basis of the discussion of excitation and emission spectra. In particular, the emission color of Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} by excitation of 147 and 172 nm irradiations is very close to the standard blue color, suggesting that it could be potentially applied in plasma display panels and mercury-free fluorescence lamps.

  14. Photoresists in extreme ultraviolet lithography (EUVL)

    Science.gov (United States)

    De Simone, Danilo; Vesters, Yannick; Vandenberghe, Geert

    2017-06-01

    The evolutionary advances in photosensitive material technology, together with the shortening of the exposure wavelength in the photolithography process, have enabled and driven the transistor scaling dictated by Moore's law for the last 50 years. Today, the shortening wavelength trend continues to improve the chips' performance over time by feature size miniaturization. The next-generation lithography technology for high-volume manufacturing (HVM) is extreme ultraviolet lithography (EUVL), using a light source with a wavelength of 13.5 nm. Here, we provide a brief introduction to EUVL and patterning requirements for sub-0-nm feature sizes from a photomaterial standpoint, discussing traditional and novel photoresists. Emphasis will be put on the novel class of metal-containing resists (MCRs) as well as their challenges from a manufacturing prospective.

  15. SUMER: Solar Ultraviolet Measurements of Emitted Radiation

    Science.gov (United States)

    Wilhelm, K.; Axford, W. I.; Curdt, W.; Gabriel, A. H.; Grewing, M.; Huber, M. C. E.; Jordan, M. C. E.; Lemaire, P.; Marsch, E.; Poland, A. I.

    1988-01-01

    The SUMER (solar ultraviolet measurements of emitted radiation) experiment is described. It will study flows, turbulent motions, waves, temperatures and densities of the plasma in the upper atmosphere of the Sun. Structures and events associated with solar magnetic activity will be observed on various spatial and temporal scales. This will contribute to the understanding of coronal heating processes and the solar wind expansion. The instrument will take images of the Sun in EUV (extreme ultra violet) light with high resolution in space, wavelength and time. The spatial resolution and spectral resolving power of the instrument are described. Spectral shifts can be determined with subpixel accuracy. The wavelength range extends from 500 to 1600 angstroms. The integration time can be as short as one second. Line profiles, shifts and broadenings are studied. Ratios of temperature and density sensitive EUV emission lines are established.

  16. Ultraviolet-visible spectroscopy of graphene oxides

    Directory of Open Access Journals (Sweden)

    Qi Lai

    2012-09-01

    Full Text Available Dispersions of few-layer (1-3 layers, multi-layer (4-10 layers and thick-layer (>10 layers graphene oxide (GO were prepared by a modified Hummers method with different mass ratios of KMnO4 to graphite. Ultraviolet-visible (UV-vis spectroscopic data show that few-layer GO dispersions can be distinguished from multi- and thick-layer dispersions by a more intense peak at 230 nm. Atomic force microscopy (AFM images of few-layer GO contain a single peak, those of multi-layer GO exhibit a shoulder and those of thick-layer GO do not contain a peak or shoulder. These findings allow qualitative analysis of GO dispersions. X-ray photoelectron spectra (XPS show that the change of UV-vis absorption intensity of GO is caused by a conjugative effect related to chromophore aggregation that influences the π-π* plasmon peak.

  17. Graded nanowire ultraviolet LEDs by polarization engineering

    Science.gov (United States)

    Carnevale, Santino D.; Kent, Thomas F.; Phillips, Patrick J.; Sarwar, A. T. M. Golam; Klie, Robert F.; Rajan, Siddharth; Myers, Roberto C.

    2012-10-01

    Given the large thermal activation energy of acceptors in high %Al AlGaN, a new approach is needed to control p-type conductivity in this material. One promising alternative to using impurity doping with thermal activation is using the intrinsic characteristics of the III-nitrides to activate dopants with polarization-induced charge in graded heterostructures. In this work polarization-induced activation of dopants is used in graded AlGaN nanowires grown by plasma-assisted molecular beam epitaxy to form ultraviolet light-emitting diodes. Electrical and optical characterization is provided, showing clear diode behavior and electroluminescent emission at 336nm. Variable temperature electrical measurements show little change in device performance at cryogenic temperatures, proving that dopant ionization is polarizationinduced rather than thermally activated.

  18. Ultraviolet bestråling i stalde

    DEFF Research Database (Denmark)

    Pedersen, J.

    Den intensive husdyrproduktion er bl.a. kendetegnet ved, at husdyrene normalt opholder sig indendørs hele året. Fra gammel tid har man kendt og værdsat solens gavnlige indvirkning på husdyrenes trivsel og sunhedstilstand, men denne indvirkning går man altså nu glip af. Det er måske derfor kun nat...... naturligt, at man i stedet har forsøgt ad kunstig vej at fremskaffe "solstråler" inde i stalden. Man har såvel i forsøg som i praksis forsøgt sig med ultraviolet bestråling, idet den gavnlig virkning især skyldes sollysets indhold og ultraviolette stråler....

  19. Vacuum Ultraviolet Photoionization of Complex Chemical Systems.

    Science.gov (United States)

    Kostko, Oleg; Bandyopadhyay, Biswajit; Ahmed, Musahid

    2016-05-27

    Tunable vacuum ultraviolet (VUV) radiation coupled to mass spectrometry is applied to the study of complex chemical systems. The identification of novel reactive intermediates and radicals is revealed in flame, pulsed photolysis, and pyrolysis reactors, leading to the elucidation of spectroscopy, reaction mechanisms, and kinetics. Mass-resolved threshold photoelectron photoion coincidence measurements provide unprecedented access to vibrationally resolved spectra of free radicals present in high-temperature reactors. Photoionization measurements in water clusters, nucleic acid base dimers, and their complexes with water provide signatures of proton transfer in hydrogen-bonded and π-stacked systems. Experimental and theoretical methods to track ion-molecule reactions and fragmentation pathways in intermolecular and intramolecular hydrogen-bonded systems in sugars and alcohols are described. Photoionization of laser-ablated molecules, clusters, and their reaction products inform thermodynamics and spectroscopy that are relevant to astrochemistry and catalysis. New directions in coupling VUV radiation to interrogate complex chemical systems are discussed.

  20. Tautomerization of Thymine Using Ultraviolet Light.

    Science.gov (United States)

    Vinje, Jakob; Falck, Merete; Mazzola, Federico; Cooil, Simon Phillip; Koch, Henrik; Høyvik, Ida-Marie; Wells, Justin

    2017-09-26

    Ultraviolet-light-induced changes to the nucleobase thymine deposited onto a MoS2 surface were studied using photoelectron spectroscopy and first-principles calculations. These measurements suggest changes in the molecular structure indicated by changes in core electron binding energies. The experimental work has been interpreted by means of ab initio calculations using coupled cluster singles and doubles (CCSD) linear response theory. Contrary to the expected behavior, i.e., the dimerization of two thymine molecules into a pyrimidine dimer, a shift between two tautomeric forms was observed upon UV-exposure. Exposure to ionizing radiation is known to induce damage in many biological molecules, and the present work gives additional insight into its effects on thymine, the interactions of the molecules, and finally how certain UV photoproducts may be avoided.

  1. Solar ultraviolet radiation measurements at South African and Reunion Island Coastal Sites: An indicator of public sun protection

    CSIR Research Space (South Africa)

    Wright, CY

    2013-09-01

    Full Text Available Solar ultraviolet radiation (UVR) has the potential to cause biological harm to humans. Intensity of solar UVR at the Earth’s surface depends on several factors, such as total column ozone and cloud cover, and temporal trends are usually dependent...

  2. Protection from solar ultraviolet radiation by clothing

    Energy Technology Data Exchange (ETDEWEB)

    Pailthorpe, M. [New South Wales Univ., Kensington, NSW (Australia)

    1996-12-31

    The recently published Australia/New Zealand Standard AS/NZS 4399: l996 `Sun Protective Clothing - Evaluation and Classification` specifies an in vitro spectrophotometric method for the measurement of the ultraviolet (WR) transmission of textiles. Ultraviolet Protection Factors (UPF) are then calculated by convolving the UVR transmission data with standard CIE erythemal response data and ARL solar irradiance data. At the present time the scope of the standard is limited to loose fitting dry clothing. Virtually every textile parameter has an influence on the UPF of the finished garment and hence on the protection afforded to skin from the harmful effects of solar UVR radiation. Textile parameters such as fibre type, the method of spinning the yarn, fabric structure, cover factor, colorant, UVR absorbers and finishing methods determine the UPF of the fabric and hence must be controlled from batch to batch. Since garments generally shrink when washed, multiple wearing and washing cycles usually cause an increase in fabric UPF. Adventitious soiling of fabrics and the absorption of certain components of domestic laundry formulations, e g fluorescent whitening agents, increase fabric UPF ratings. Garments with a high degree of elasticity, e g nylon/lycra sportswear, that are stretched on to fit, will obviously have lower UPFs when stretched than when relaxed. In general fabrics worn in a wet state provide lower protection than when worn dry. On Australia`s most extreme summer day it has been estimated that there are 30 MEDs (minimal erythemal doses) in a dawn to dusk exposure. Thus outdoor workers should be provided with UPF 30 clothing, or better. Results from recent experiments using SK-II hairless mice dressed in UPF 50 `sunsuits` have shown that the mice developed no sun induced skin cancers on the skin areas protected by the UPF 50 fabric whereas multiple tumours developed on the unprotected skin.

  3. Diagnosis of Dentin Caries – Ultraviolet Fluorescence

    Directory of Open Access Journals (Sweden)

    Uzunov Ts.

    2014-12-01

    Full Text Available The technology advance in recent years determines the need of construction of modern appliances for early diagnosis of dental caries, which are categorized by great precision, non-invasiveness, easy usage and wide availability. Such non-invasive and accurate tool for diagnostics of caries is Caries Detector (LED, Bulgarian product by “Optica Laser”. The detector emits a specific wavelength of near ultraviolet light, which causes fluorescence to porphyrins - metabolic products of the life cycle of caries-inducing bacteria. The purpose of the study is piloting a new diagnostic tool for detection and monitoring of caries excavation based on fluorescence - LED UV caries detector of company “Optica laser”. Subjected to examination by caries indicator dye and UV caries detector were sixty permanent teeth with deep dentine caries. Two methods were used to assess the dentin caries - UV fluorescence detector of “Optica Laser” and staining with caries indicator - dye (Sable ™ Seek®. It was found that among all sixty teeth, the fields, closed by margins of carious process overlap. Fifty-four of tested teeth has shown bigger field of images with staining method and six - smaller in comparison to the fluorescent method. Ultraviolet fLuorescence caries detector of “Optica Laser” company is affordable and easy applicable method for controlled excavation of dentine caries. The detector can be used in daily dental practice equally with other methods. The unit has a number of advantages - non-invasiveness, lack of interaction with tooth structures, speed, reliability, efficiency, predictability and repeatability of results.

  4. Ultraviolet Echoes of Quasar Accretion Disks

    Science.gov (United States)

    Trump, Jonathan

    2017-08-01

    We propose a novel ultraviolet monitoring campaign with WFC3/UVIS to measure quasar accretion disk structure. The bulk of supermassive black hole growth occurs in luminous quasar phases of rapid accretion, yet the governing physics remains poorly understood. Continuum reverberation mapping (RM) measures the accretion disk size via the time lag between short- and long-wavelength emission: the proposed UV monitoring forms the foundation for simultaneous optical observations (expected to continue for our quasars through 2019). Currently only 4 Seyfert AGNs have UV/optical RM accretion-disk sizes, all low-luminosity and at z<0.02. We propose to monitor 5 new quasars, spanning an order of magnitude higher accretion rate and out to z 1. The 5 quasar targets are drawn from SDSS-RM, a pioneering multi-object spectroscopic RM campaign, and have been monitored with optical photometry and spectroscopy since 2014. The higher luminosity and accurate RM masses of our sample enable the first measurements of accretion-rate effects on accretion-disk size, with UV monitoring directly probing changes in the inner disk suggested by theory and previous indirect observations. Our proposed HST monitoring campaign is unusually efficient, targeting 5 quasars per orbit using the DASH method with UVIS subarray readouts. We use simulations to demonstrate that our 2-day cadence over 32 epochs will accurately measure continuum lags and accretion-disk structure. Ultraviolet monitoring of these 5 quasars will enable critical new measurements of accretion-disk structure during the rapid accretion mode that dominates black hole growth.

  5. Protection from acute exposure to ultraviolet radiation by ultraviolet-absorbing RGP contact lenses.

    Science.gov (United States)

    Dumbleton, K A; Cullen, A P; Doughty, M J

    1991-07-01

    One eye in each of 12 female pigmented rabbits was irradiated with UVB while wearing an EqualensR I rigid gas-permeable contact lens. The other eye served as a control. The irradiance level was 625 microW cm-2 (285-315 nm total bandpass) with exposure times up to 2364 s. Eyes were evaluated 24 h and 48 h after exposure by biomicroscopy and pachometry, and later by scanning electron microscopy (SEM). The contact lens was found to protect the central cornea from radiant exposures up to 60 times threshold. The exposed areas of cornea showed characteristic ultraviolet damage with an arc of demarcation indicating the position of the lens. With time the area formed a ridge of damaged cells (confirmed by SEM). At radiant exposure over 0.75 J cm-2 some oedema was seen in the 'protected' region, apparently by extension rather than as a direct effect. These findings suggest that in the human being exposed to ultraviolet radiation this ultraviolet-absorbing RGP lens would permit nasal and temporal photoketatitis with sparing of the central cornea and provide some protection of more posterior ocular structures.

  6. Nonthermal combined ultraviolet and vacuum-ultraviolet curing process for organosilicate dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, H.; Guo, X.; Pei, D.; Li, W.; Blatz, J.; Hsu, K.; Benjamin, D.; Shohet, J. L., E-mail: shohet@engr.wisc.edu [Plasma Processing and Technology Laboratory and Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Lin, Y.-H.; Fung, H.-S.; Chen, C.-C. [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Nishi, Y. [Stanford University, Stanford, California 94305 (United States)

    2016-06-13

    Porous SiCOH films are of great interest in semiconductor fabrication due to their low-dielectric constant properties. Post-deposition treatments using ultraviolet (UV) light on organosilicate thin films are required to decompose labile pore generators (porogens) and to ensure optimum network formation to improve the electrical and mechanical properties of low-k dielectrics. The goal of this work is to choose the best vacuum-ultraviolet photon energy in conjunction with vacuum ultraviolet (VUV) photons without the need for heating the dielectric to identify those wavelengths that will have the most beneficial effect on improving the dielectric properties and minimizing damage. VUV irradiation between 8.3 and 8.9 eV was found to increase the hardness and elastic modulus of low-k dielectrics at room temperature. Combined with UV exposures of 6.2 eV, it was found that this “UV/VUV curing” process is improved compared with current UV curing. We show that UV/VUV curing can overcome drawbacks of UV curing and improve the properties of dielectrics more efficiently without the need for high-temperature heating of the dielectric.

  7. Final LDRD report :ultraviolet water purification systems for rural environments and mobile applications.

    Energy Technology Data Exchange (ETDEWEB)

    Banas, Michael Anthony; Crawford, Mary Hagerott; Ruby, Douglas Scott; Ross, Michael P.; Nelson, Jeffrey Scott; Allerman, Andrew Alan; Boucher, Ray

    2005-11-01

    We present the results of a one year LDRD program that has focused on evaluating the use of newly developed deep ultraviolet LEDs in water purification. We describe our development efforts that have produced an LED-based water exposure set-up and enumerate the advances that have been made in deep UV LED performance throughout the project. The results of E. coli inactivation with 270-295 nm LEDs are presented along with an assessment of the potential for applying deep ultraviolet LED-based water purification to mobile point-of-use applications as well as to rural and international environments where the benefits of photovoltaic-powered systems can be realized.

  8. Water Treatment Using Advanced Ultraviolet Light Sources Final Report CRADA No. TC02089.0

    Energy Technology Data Exchange (ETDEWEB)

    Hoppes, W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Oster, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-08-15

    This was a collaborative effort between Lawrence Livermore National Security, LLC as manager and operator of Lawrence Livermore National Laboratory (LLNL) and Teknichal Services, LLC (TkS), to develop water treatment systems using advanced ultraviolet light sources. The Russian institutes involved with this project were The High Current Electronics Institute (HCEI) and Russian Institute of Technical Physics-Institute of Experimental Physics (VNIIEF). HCEI and VNIIEF developed and demonstrated the potential commercial viability of short-wavelength ultraviolet excimer lamps under a Thrust 1 Initiatives for Proliferation Prevention (IPP) Program. The goals of this collaboration were to demonstrate both the commercial viability of excilampbased water disinfection and achieve further substantial operational improvement in the lamps themselves; particularly in the area of energy efficiency.

  9. The Ultraviolet Radiation Environment around M Dwarf Exoplanet Host Stars

    Science.gov (United States)

    France, Kevin; Froning, Cynthia S.; Linsky, Jeffrey L.; Roberge, Aki; Stocke, John T.; Tian, Feng; Bushinsky, Rachel; Desert, Jean-Michel; Mauas, Pablo; Mauas, Pablo; hide

    2013-01-01

    The spectral and temporal behavior of exoplanet host stars is a critical input to models of the chemistry and evolution of planetary atmospheres. Ultraviolet photons influence the atmospheric temperature profiles and production of potential biomarkers on Earth-like planets around these stars. At present, little observational or theoretical basis exists for understanding the ultraviolet spectra of M dwarfs, despite their critical importance to predicting and interpreting the spectra of potentially habitable planets as they are obtained in the coming decades. Using observations from the Hubble Space Telescope, we present a study of the UV radiation fields around nearby M dwarf planet hosts that covers both far-UV (FUV) and near-UV (NUV) wavelengths. The combined FUV+NUV spectra are publicly available in machine-readable format. We find that all six exoplanet host stars in our sample (GJ 581, GJ 876, GJ 436, GJ 832, GJ 667C, and GJ 1214) exhibit some level of chromospheric and transition region UV emission. No "UV-quiet" M dwarfs are observed. The bright stellar Lyman-alpha emission lines are reconstructed, and we find that the Lyman-alpha line fluxes comprise approximately 37%-75% of the total 1150-3100 A flux from most M dwarfs; approximately greater than 10(exp3) times the solar value. We develop an empirical scaling relation between Lyman-alpha and Mg II emission, to be used when interstellar H I attenuation precludes the direct observation of Lyman-alpha. The intrinsic unreddened flux ratio is F(Lyman-alpha)/F(Mg II) = 10(exp3). The F(FUV)/F(NUV) flux ratio, a driver for abiotic production of the suggested biomarkers O2 and O3, is shown to be approximately 0.5-3 for all M dwarfs in our sample, greather than 10(exp3) times the solar ratio. For the four stars with moderate signal-to-noise Cosmic Origins Spectrograph time-resolved spectra, we find UV emission line variability with amplitudes of 50%.500% on 10(exp2)-10(exp3) s timescales. This effect should be taken

  10. Biological applications of ultraviolet free-electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Sutherland, J.C.

    1997-10-01

    This review examines the possibilities for biological research using the three ultraviolet free-electron lasers that are nearing operational status in the US. The projected operating characteristics of major interest in biological research of the free-electron lasers at Brookhaven National Laboratory, the Thomas Jefferson National Accelerator Facility, and Duke University are presented. Experimental applications in the areas of far- and vacuum ultraviolet photophysics and photochemistry, structural biology, environmental photobiology, and medical research are discussed and the prospects for advances in these areas, based upon the characteristics of the new ultraviolet free-electron lasers, are evaluated.

  11. Extreme ultraviolet spectral irradiance measurements since 1946

    Science.gov (United States)

    Schmidtke, G.

    2015-03-01

    In the physics of the upper atmosphere the solar extreme ultraviolet (EUV) radiation plays a dominant role controlling most of the thermospheric/ionospheric (T/I) processes. Since this part of the solar spectrum is absorbed in the thermosphere, platforms to measure the EUV fluxes became only available with the development of rockets reaching altitude levels exceeding 80 km. With the availability of V2 rockets used in space research, recording of EUV spectra started in 1946 using photographic films. The development of pointing devices to accurately orient the spectrographs toward the sun initiated intense activities in solar-terrestrial research. The application of photoelectric recording technology enabled the scientists placing EUV spectrometers aboard satellites observing qualitatively strong variability of the solar EUV irradiance on short-, medium-, and long-term scales. However, as more measurements were performed more radiometric EUV data diverged due to the inherent degradation of the EUV instruments with time. Also, continuous recording of the EUV energy input to the T/I system was not achieved. It is only at the end of the last century that there was progress made in solving the serious problem of degradation enabling to monitore solar EUV fluxes with sufficient radiometric accuracy. The data sets available allow composing the data available to the first set of EUV data covering a period of 11 years for the first time. Based on the sophisticated instrumentation verified in space, future EUV measurements of the solar spectral irradiance (SSI) are promising accuracy levels of about 5% and less. With added low-cost equipment, real-time measurements will allow providing data needed in ionospheric modeling, e.g., for correcting propagation delays of navigation signals from space to earth. Adding EUV airglow and auroral emission monitoring by airglow cameras, the impact of space weather on the terrestrial T/I system can be studied with a spectral terrestrial

  12. Polymer filters for ultraviolet-excited integrated fluorescence sensing

    Science.gov (United States)

    Dandin, Marc; Abshire, Pamela; Smela, Elisabeth

    2012-09-01

    Optical filters for blocking ultraviolet (UV) light were fabricated by doping various polymer hosts with a UV absorbing chromophore. The polymers were polydimethylsiloxane (PDMS), a silicone elastomer frequently used in microfluidics, SU-8, a photopatternable epoxy, and Humiseal 1B66, an acrylic coating used for moisture protection of integrated circuits. The chromophore was 2-(2‧-hydroxy-5‧-methylphenyl) benzotriazole (BTA), which has a high extinction coefficient between 300 nm and 400 nm. We demonstrate filters 5 µm thick that exhibit high ultraviolet rejection (nearly -40 dB at 342 nm) yet pass visible light (near 0 dB above 400 nm), making them ideal for ultraviolet-excited fluorescence sensing within microsystems. The absorbance of the BTA depended on the host polymer. These filters are promising for integrated fluorescence spectroscopy in bioanalytical platforms because they can be patterned by dry etching, molding or exposure to ultraviolet light.

  13. Development of a Selectable Output Ultraviolet Laser System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Here, we propose to develop a breadboard laser system that is capable of producing radiation in two UV wavelengths.  This Selectable Output Ultraviolet Laser...

  14. Effects of Ultraviolet (UV) Radiations at Different Wave Lengths on ...

    African Journals Online (AJOL)

    Prof. Ogunji

    biotechsocietynigeria.org. Short Communication. Effects of Ultraviolet (UV) Radiations at Different Wave Lengths on the Microbial Load ... stained blue while the living cells reduced the stain and remained colourless. The viability of the yeast ...

  15. Solar ultraviolet irradiance measurements, instrumentation, intercomparisons and interpretations

    Energy Technology Data Exchange (ETDEWEB)

    Thorseth, Trond Morten

    2000-07-01

    The thesis reports studies of stabile instruments that are capable of detecting small alterations in ultraviolet irradiation over a long period. A central theme in the work has been to improve the measuring systems for continuous research based monitoring of natural variations in the ultraviolet irradiation from the sun. Methods for controlling the stability and continually secure the quality of the collected data. The causes of measuring errors are mapped and methods for the correction of collected data are developed. The methods and measuring systems for collecting the data have been adapted to the Norwegian climate and geography. The work has lead to an increased understanding of the natural variation in the ultraviolet radiation from the sun and what factors in the atmosphere that influences the process. The collected data and the developed methods for the quality control have increased the understanding of the ultraviolet irradiation climate in Europe.

  16. Compact and efficient ultraviolet laser for astrobiology Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The purpose of this program is to develop a compact and efficient ultraviolet laser for use in space-based uv-Raman instruments. The basis for this system will be a...

  17. Ultraviolet photographic pyrometer used in rocket exhaust analysis

    Science.gov (United States)

    Levin, B. P.

    1966-01-01

    Ultraviolet photographic pyrometer investigates the role of carbon as a thermal radiator and determines the geometry, location, and progress of afterburning phenomena in the exhaust plume of rocket engines using liquid oxygen/RP-1 as propellant.

  18. Study of asphalt performance impact with ultraviolet aging

    Science.gov (United States)

    Luo, Min

    2017-09-01

    To solve the problem of strong ultraviolet radiation on the road asphalt aging, ultraviolet aging environment box analog wild aging condition to be used to experiment, Through dynamic shear rheometer respectively to study the effect of SBS modified asphalt and asphalt matrix high temperature, low temperature and fatigue performance with the aging time to change. The results show that SBS modified asphalt can produce serious aging under strong ultraviolet light, the Main aspects is fatigue performance and low temperature performance greatly reduced, high temperature performance is further improved, They have a closer relationship with aging time; At the same time, along with the test temperature, aging time on the influence of G*/sinδ, G*sinδ of amplitude decreases. That ultraviolet on SBS modified asphalt aging has temperature sensitivity. The research conclusion can choose the light aging resistance of airport pavement asphalt to provide good technical support.

  19. Coherence techniques at extreme ultraviolet wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chang [Univ. of California, Berkeley, CA (United States)

    2002-01-01

    The renaissance of Extreme Ultraviolet (EUV) and soft x-ray (SXR) optics in recent years is mainly driven by the desire of printing and observing ever smaller features, as in lithography and microscopy. This attribute is complemented by the unique opportunity for element specific identification presented by the large number of atomic resonances, essentially for all materials in this range of photon energies. Together, these have driven the need for new short-wavelength radiation sources (e.g. third generation synchrotron radiation facilities), and novel optical components, that in turn permit new research in areas that have not yet been fully explored. This dissertation is directed towards advancing this new field by contributing to the characterization of spatial coherence properties of undulator radiation and, for the first time, introducing Fourier optical elements to this short-wavelength spectral region. The first experiment in this dissertation uses the Thompson-Wolf two-pinhole method to characterize the spatial coherence properties of the undulator radiation at Beamline 12 of the Advanced Light Source. High spatial coherence EUV radiation is demonstrated with appropriate spatial filtering. The effects of small vertical source size and beamline apertures are observed. The difference in the measured horizontal and vertical coherence profile evokes further theoretical studies on coherence propagation of an EUV undulator beamline. A numerical simulation based on the Huygens-Fresnel principle is performed.

  20. Intense ultraviolet perturbations on aquatic primary producers

    CERN Document Server

    Guimarais, Mayrene; Horvath, Jorge

    2010-01-01

    During the last decade, the hypothesis that one or more biodiversity drops in the Phanerozoic eon, evident in the geological record, might have been caused by the most powerful kind of stellar explosion so far known (Gamma Ray Bursts) has been discussed in several works. These stellar explosions could have left an imprint in the biological evolution on Earth and in other habitable planets. In this work we calculate the short-term lethality that a GRB would produce in the aquatic primary producers on Earth. This effect on life appears as a result of ultraviolet (UV) re-transmission in the atmosphere of a fraction of the gamma energy, resulting in an intense UV flash capable of penetrating ~ tens of meters in the water column in the ocean. We focus on the action of the UV flash on phytoplankton, as they are the main contributors to global aquatic primary productivity. Our results suggest that the UV flash could cause an hemispheric reduction of phytoplankton biomass in the upper mixed layer of the World Ocean o...

  1. Vacuum ultraviolet detector for gas chromatography.

    Science.gov (United States)

    Schug, Kevin A; Sawicki, Ian; Carlton, Doug D; Fan, Hui; McNair, Harold M; Nimmo, John P; Kroll, Peter; Smuts, Jonathan; Walsh, Phillip; Harrison, Dale

    2014-08-19

    Analytical performance characteristics of a new vacuum ultraviolet (VUV) detector for gas chromatography (GC) are reported. GC-VUV was applied to hydrocarbons, fixed gases, polyaromatic hydrocarbons, fatty acids, pesticides, drugs, and estrogens. Applications were chosen to feature the sensitivity and universal detection capabilities of the VUV detector, especially for cases where mass spectrometry performance has been limited. Virtually all chemical species absorb and have unique gas phase absorption cross sections in the approximately 120-240 nm wavelength range monitored. Spectra are presented, along with the ability to use software for deconvolution of overlapping signals. Some comparisons with experimental synchrotron data and computed theoretical spectra show good agreement, although more work is needed on appropriate computational methods to match the simultaneous broadband electronic and vibronic excitation initiated by the deuterium lamp. Quantitative analysis is governed by Beer-Lambert Law relationships. Mass on-column detection limits reported for representatives of different classes of analytes ranged from 15 (benzene) to 246 pg (water). Linear range measured at peak absorption for benzene was 3-4 orders of magnitude. Importantly, where absorption cross sections are known for analytes, the VUV detector is capable of absolute determination (without calibration) of the number of molecules present in the flow cell in the absence of chemical interferences. This study sets the stage for application of GC-VUV technology across a wide breadth of research areas.

  2. Biological Sensors for Solar Ultraviolet Radiation

    Directory of Open Access Journals (Sweden)

    André P. Schuch

    2011-04-01

    Full Text Available Solar ultraviolet (UV radiation is widely known as a genotoxic environmental agent that affects Earth ecosystems and the human population. As a primary consequence of the stratospheric ozone layer depletion observed over the last decades, the increasing UV incidence levels have heightened the concern regarding deleterious consequences affecting both the biosphere and humans, thereby leading to an increase in scientific efforts to understand the role of sunlight in the induction of DNA damage, mutagenesis, and cell death. In fact, the various UV-wavelengths evoke characteristic biological impacts that greatly depend on light absorption of biomolecules, especially DNA, in living organisms, thereby justifying the increasing importance of developing biological sensors for monitoring the harmful impact of solar UV radiation under various environmental conditions. In this review, several types of biosensors proposed for laboratory and field application, that measure the biological effects of the UV component of sunlight, are described. Basically, the applicability of sensors based on DNA, bacteria or even mammalian cells are presented and compared. Data are also presented showing that on using DNA-based sensors, the various types of damage produced differ when this molecule is exposed in either an aqueous buffer or a dry solution. Apart from the data thus generated, the development of novel biosensors could help in evaluating the biological effects of sunlight on the environment. They also emerge as alternative tools for using live animals in the search for protective sunscreen products.

  3. Reflective masks for extreme ultraviolet lithography

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Khanh Bao [Univ. of California, Berkeley, CA (United States)

    1994-05-01

    Extreme ultraviolet lithographic masks are made by patterning multilayer reflective coatings with high normal incidence reflectivity. Masks can be patterned by depositing a patterned absorber layer above the coating or by etching the pattern directly into the coating itself. Electromagnetic simulations showed that absorber-overlayer masks have superior imaging characteristics over etched masks (less sensitive to incident angles and pattern profiles). In an EUVL absorber overlayer mask, defects can occur in the mask substrate, reflective coating, and absorber pattern. Electromagnetic simulations showed that substrate defects cause the most severe image degradation. A printability study of substrate defects for absorber overlayer masks showed that printability of 25 nm high substrate defects are comparable to defects in optical lithography. Simulations also indicated that the manner in which the defects are covered by multilayer reflective coatings can affect printability. Coverage profiles that result in large lateral spreading of defect geometries amplify the printability of the defects by increasing their effective sizes. Coverage profiles of Mo/Si coatings deposited above defects were studied by atomic force microscopy and TEM. Results showed that lateral spread of defect geometry is proportional to height. Undercut at defect also increases the lateral spread. Reductions in defect heights were observed for 0.15 μm wide defect lines. A long-term study of Mo/Si coating reflectivity revealed that Mo/Si coatings with Mo as the top layer suffer significant reductions in reflectivity over time due to oxidation.

  4. Nonlinear optics in the extreme ultraviolet.

    Science.gov (United States)

    Sekikawa, Taro; Kosuge, Atsushi; Kanai, Teruto; Watanabe, Shuntaro

    2004-12-02

    Nonlinear responses to an optical field are universal in nature but have been difficult to observe in the extreme ultraviolet (XUV) and soft X-ray regions owing to a lack of coherent intense light sources. High harmonic generation is a well-known nonlinear optical phenomenon and is now drawing much attention in attosecond pulse generation. For the application of high harmonics to nonlinear optics in the XUV and soft X-ray regime, optical pulses should have both large pulse energy and short pulse duration to achieve a high optical electric field. Here we show the generation of intense isolated pulses from a single harmonic (photon energy 27.9 eV) by using a sub-10-femtosecond blue laser pulse, producing a large dipole moment at the relatively low (ninth) harmonic order nonadiabatically. The XUV pulses with pulse durations of 950 attoseconds and 1.3 femtoseconds were characterized by an autocorrelation technique, based on two-photon above-threshold ionization of helium atoms. Because of the small cross-section for above-threshold ionization, such an autocorrelation measurement of XUV pulses with photon energy larger than the ionization energy of helium has not hitherto been demonstrated. The technique can be extended to the characterization of higher harmonics at shorter wavelengths.

  5. Extreme ultraviolet-induced photoionized plasmas

    Science.gov (United States)

    Bartnik, Andrzej; Wachulak, Przemyslaw; Fiedorowicz, Henryk; Fok, Tomasz; Jarocki, Roman; Szczurek, Miroslaw

    2014-05-01

    In this work photoionized plasmas were created by irradiation of He or Ne gases with a focused extreme ultraviolet (EUV) beam from one of two laser-plasma sources employing Nd:YAG laser systems. The first of them was a 10 Hz laser-plasma EUV source, based on a double-stream gas-puff target, irradiated with a 3 ns per 0.8 J laser pulse. EUV radiation in this case was focused using a gold-plated grazing incidence ellipsoidal collector. The second source was based on a 10 ns per 10 J per 10 Hz laser system. In this case EUV radiation was focused using a gold-plated grazing incidence multifoil collector. Gases were injected into the interaction region, perpendicularly to an optical axis of the irradiation system, using an auxiliary gas puff valve. Spectral measurements in the EUV range were performed. In all cases the most intense emission lines were assigned to singly charged ions. The other emission lines belong to atoms or doubly charged ions.

  6. Hermite scatterers in an ultraviolet sky

    Science.gov (United States)

    Parker, Kevin J.

    2017-12-01

    The scattering from spherical inhomogeneities has been a major historical topic in acoustics, optics, and electromagnetics and the phenomenon shapes our perception of the world including the blue sky. The long wavelength limit of ;Rayleigh scattering; is characterized by intensity proportional to k4 (or λ-4) where k is the wavenumber and λ is the wavelength. With the advance of nanotechnology, it is possible to produce scatterers that are inhomogeneous with material properties that are functions of radius r, such as concentric shells. We demonstrate that with proper choice of material properties linked to the Hermite polynomials in r, scatterers can have long wavelength scattering behavior of higher powers: k8, k16, and higher. These ;Hermite scatterers; could be useful in providing unique signatures (or colors) to regions where they are present. If suspended in air under white light, the back-scattered spectrum would be shifted from blue towards violet and then ultraviolet as the higher order Hermite scatterers were illuminated.

  7. Far Ultraviolet Remote Sensing: Challenges and Opportunities

    Science.gov (United States)

    Paxton, L. J.

    2004-12-01

    The far ultraviolet is commonly taken to be that spectral range from 115 nm to 185 nm. This definition reflects the practical nature and origin of the measurement technique. The short wavelength cut-off is defined by the transmittance cut-off of window materials (about 115 nm). The long wavelength end of the region is defined by the desire to exclude the orders-of-magnitude brighter signal at around 195 nm, which, happily, coincides with the fall-off in CsI photocathode efficiency at around 185 nm. The FUV allows us to probe the atmosphere down to about 130 km (as low as 80 km in H Lyman alpha). In this paper I will discuss what we have learned by using a novel imager, GUVI, on TIMED to study the ionosphere-thermosphere (IT) system, how we see the IT coupled to geospace and the solar input, and what we can learn from a future FUV system. In particular, I want to stress that FUV remote sensing is an important COMPONENT of a complete system for exploring the connections between the Sun, geospace, and the IT system. To that end, I will briefly discuss how those data need to be integrated into a virtual observatory that will enable new investigations into the near-Earth environment.

  8. The ultraviolet spectra of the Jovian aurora

    Energy Technology Data Exchange (ETDEWEB)

    Liu, W.; Dalgarno, A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138 (United States)

    1996-08-01

    The ultraviolet spectra of molecular hydrogen H{sub 2} due to electron impact excitation are calculated and compared with the high-resolution (0.56 A) spectra of the Jovian aurora obtained with the {ital Hubble} {ital Space} {ital Telescope} Goddard High-Resolution Spectrograph. All the observed features are reproduced by electron impact excitation emissions of H{sub 2}, and the predicted intensities agree well with the observed intensities. Accurate molecular parameters are used, and effects of secondary electrons are included. The auroral emissions are reproduced by energetic electron impact excitation of H{sub 2} with a temperature of 400{endash}600 K. Large temperature gradients occur with respect to altitude within the auroral emission regions. The auroral spectra contain a cascade contribution to the Lyman band emission from high-lying {ital E} and {ital F} states that are populated by the low-energy secondary electrons produced as the energetic auroral electrons slow down. {copyright} {ital 1996 The American Astronomical Society.}

  9. Ultraviolet Light Source Using Electrodeless Microwave Discharge

    Science.gov (United States)

    Nishikawa, Taku; Toyoda, Hirotaka

    2015-09-01

    Surface treatment technologies using ultraviolet (UV) light, such as organic residue removal, surface modification or sterilization, are widely used. So far, UV lamps using DC discharge with electrodes inside the lamp tube is commonly used. However, sputtering of electrode materials sometimes causes deposition on the inner tube surface as well as degradation of the electrodes, resulting in short life time of the lamp tube. In this study, we propose an electrodeless UV mercury (Hg) lamp source using microwave power. 2.45 GHz Microwave power (<4 kW) from a power supply is divided into four power lines using branch waveguides. A mercury lamp tube (diameter: 9.6 mm, length: 42 cm, Hg: 13.5 mg, Ar: 1 Torr) is inserted into the branch waveguides and microwave power is coupled to the plasma. Emission from the lamp is monitored by a monochromator and an 254 nm UV monitor. Lamp temperature is also measured by a thermography camera and tube temperature up to 900 K with good uniformity along ~ 30 cm was observed. Uniformity of the 254 nm UV light intensity was +15 % along the lamp tube. The maximum UV light intensity of 64 mW/cm2 was observed at a microwave power of 4 kW.

  10. Ultraviolet eye radiation: the problem and solutions.

    Science.gov (United States)

    Sheedy, James E; Edlich, Richard F

    2004-01-01

    Ultraviolet radiation (UVR) can cause damage to the eyes. Some of the damage is acute, with immediate signs and symptoms, while some of the damage is the result of cumulative or long-term UVR exposure. Because the most common source of UVR is the sun, individuals who are exposed to sunny environments should be advised to protect themselves properly. Individuals should be counseled about proper eye protection from UVR in sunlight. It is important to know when eye protection is indicated. Protection involves wearing a wide-brimmed hat or cap and well-designed sunglasses. The advisable sunglass features include the following: large eye size with side protection, less than 1% UV-B transmittance, less than 1% UV-A transmittance, gray or near-neutral colored lenses, good optical quality, and visible transmittance selected for visual comfort. Some clear spectacles or contact lenses also provide good levels of UV protection. When selecting sunglasses, it is always helpful to consult your eye care specialist.

  11. Ultraviolet radiation and echinoderms: past, present and future perspectives.

    Science.gov (United States)

    Lamare, Miles; Burritt, David; Lister, Kathryn

    2011-01-01

    There is general consensus that solar ultraviolet radiation (UVR) negatively impacts many marine species. Echinoderms are ubiquitous within the marine environment, with members of the phyla often long-lived and numerically dominant within the benthic macrofauna, consequently the impact of UVR on the population dynamics of these organisms will influence marine communities and ecosystems. Research to date has shown that exposure of echinoderms to solar UVR can, affect reproduction and development, change behaviour, cause numerous biochemical and physiological changes and potentially cause increased mutation rates, by causing DNA damage. There is also considerable evidence that echinoderms utilise several different mechanisms to protect themselves against excessive UVR and subsequent UVR-induced damage. However, these protective mechanisms may pose conflicting selection pressures on echinoderms, as UVR is an additional stressor in oceans subjected to anthropogenic-induced climate change. This review summarises our knowledge of the effects of UVR on the Echinodermata. We outline the research conducted to date, highlight key studies on UVR that have utilised echinoderms and look to the future of UVR research in a rapidly changing ocean. 2011 Elsevier Ltd. All rights reserved.

  12. Daily tropical cyclone intensity response to solar ultraviolet radiation

    Science.gov (United States)

    Elsner, J. B.; Jagger, T. H.; Hodges, R. E.

    2010-05-01

    An inverse relationship between hurricane activity over the Caribbean and the number of sunspots has recently been identified. Here we investigate this relationship using daily observations and find support for the hypothesis that changes in ultraviolet (UV) radiation rather than changes in other concomitant solar and cosmic variations are the cause. The relationship is statistically significant after accounting for annual variation in ocean heat and the El Niño cycle. A warming response in the upper troposphere to increased solar UV forcing as measured by the Mg II index (core-to-wing ratio) decreases the atmosphere's convective available potential energy leading to a weaker cyclone. The response amplitude at a cyclone intensity of 44 m s-1 is 6.7 ± 2.56 m s-1 per 0.01 Mg II units (s.d.), which compares with 4.6 m s-1 estimated from the heat-engine theory using a temperature trend derived from observations. The increasing hurricane response sensitivity with increasing strength is found in the observations and in an application of the theory.

  13. [Analysis of the cumulative solar ultraviolet radiation in Mexico].

    Science.gov (United States)

    Castanedo-Cázares, Juan Pablo; Torres-Álvarez, Bertha; Portales-González, Bárbara; Martínez-Rosales, Karla; Hernández-Blanco, Diana

    2016-01-01

    The incidence of skin cancer has increased in Mexico in recent years. Ultraviolet radiation is the main risk factor associated. Due to the need to develop strategies to prevent skin cancer, the aim of the study was to estimate the UV intensity in several representative regions of Mexico, the average annual UV dose of these populations, and the potential benefit of applying sunscreen at different ages. The intensity of UV radiation was quantified by remote and terrestrial radiometry. The dose of UV exposure was measured in minimal erythema doses using validated models for face and arms. The benefit of using a sunscreen was calculated with the use of a sunscreen with SPF 15 from birth to age 70. The UV radiation is lower in December and greater in the period from May to July. The region with a lower annual dose is Tijuana; and the higher annual dose is in the Mexico City area. The annual difference between these regions was 58 %. Through life, a low SPF sunscreen can reduce up to 66 % of the received UV dose. The geographical location is a risk factor for accumulation of UV radiation in Mexico. Since childhood, people receive high amounts of it; however, most of this dose can be reduced using any commercially available sunscreen, if applied strategically.

  14. The Extreme Ultraviolet (EUV) Instrument for the MAVEN Mission

    Science.gov (United States)

    Chamberlin, Phillip C.

    2012-01-01

    The Mars Atmosphere and Volatile Evolution Mission (MAVEN) will explore the variability in the planet's upper atmosphere and ionosphere that is dominated by interactions with the sun, specifically the high-energy photons in the soft X-ray and extreme ultraviolet wavelengths as well as interactions with the solar wind. Scientists will use MAVEN data to determine the current loss rate of volatile compounds from the Mars atmosphere, then extrapolate back in time in order to give historical estimations of state of the Mars atmosphere and climate, its ability to sustain liquid water, and the potential for the Martian habitability. The EUV instrument is critical in measuring the Space Weather driver of this atmospheric variability. It will directly observe a three EUV wavelength ranges and their variability due to solar flares (time scales of seconds to hours) as well as active region evolution (months), which will then act as proxies for a model to determine the entire 0.1-200 nm solar spectrum at all times during the MAVEN mission. These EUV measurements and models results will compliment the other instruments that will provide direct in-situ as well as remote sensing observations of the Martian atmospheric response to this solar driver. This presentation will be an introduction of this instrument and its science measurements and goals to the larger community, as well as a status report on its progress.

  15. Insights into the deactivation of 5-bromouracil after ultraviolet excitation

    Science.gov (United States)

    Peccati, Francesca; Mai, Sebastian; González, Leticia

    2017-03-01

    5-Bromouracil is a nucleobase analogue that can replace thymine in DNA strands and acts as a strong radiosensitizer, with potential applications in molecular biology and cancer therapy. Here, the deactivation of 5-bromouracil after ultraviolet irradiation is investigated in the singlet and triplet manifold by accurate quantum chemistry calculations and non-adiabatic dynamics simulations. It is found that, after irradiation to the bright ππ* state, three main relaxation pathways are, in principle, possible: relaxation back to the ground state, intersystem crossing (ISC) and C-Br photodissociation. Based on accurate MS-CASPT2 optimizations, we propose that ground-state relaxation should be the predominant deactivation pathway in the gas phase. We then employ different electronic structure methods to assess their suitability to carry out excited-state dynamics simulations. MRCIS (multi-reference configuration interaction including single excitations) was used in surface hopping simulations to compute the ultrafast ISC dynamics, which mostly involves the 1nOπ* and 3ππ* states. This article is part of the themed issue 'Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces'.

  16. Coupled exposure to ingredients of cosmetic products: III. Ultraviolet filters.

    Science.gov (United States)

    Uter, Wolfgang; Gonçalo, Margarida; Yazar, Kerem; Kratz, Eva-Maria; Mildau, Gerd; Lidén, Carola

    2014-09-01

    The use of cosmetics exposes consumers to mixtures of ingredients, many of which are potential allergens. Ultraviolet (UV) filters are used not just in sunscreens, but also in other products. Many UV filters are known contact allergens and photoallergens. To examine the pattern of co-exposure to UV filters in cosmetics. A survey of products marketed in Germany, conducted in 2006-2009 by the Chemical and Veterinary Investigation Office in Karlsruhe, identified 4447 products (of all 5667 cosmetic products examined) (i) that were categorizable according to Annex I to the Cosmetics Directive, and (ii) with information on the presence of UV filters or zinc oxide. The occurrence and co-occurrence of UV filters were analysed and presented in tabular and graphical format. UV filters or zinc oxide were present in 22.5% of all 4447 products, ranging from almost 100% in sunscreens to a few per cent in, for example, some hair products; they were absent in two product categories. Frequently, several different UV filters were included in one product, for example in sunscreens (median 4) and in perfumes (median 3). The overall most frequent UV filters were butyl methoxydibenzoylmethane and titanium dioxide, combined mostly with octocrylene in sunscreens and with ethylhexyl methoxycinnamate in creams. The frequent co-occurrence of UV filters in cosmetic products possibly facilitates sensitization, and may explain why patients often react to chemically unrelated UV filters. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Ocular ultraviolet radiation exposure of welders.

    Science.gov (United States)

    Tenkate, Thomas D

    2017-05-01

    I read with interest a recent paper in your journal by Slagor et al on the risk of cataract in relation to metal arc welding (1). The authors highlight that even though welders are exposed to substantial levels of ultraviolet radiation (UVR), "no studies have reported data on how much UVR welders' eyes are exposed to during a working day. Thus, we do not know whether welders are more or less exposed to UVR than outdoor workers" (1, p451). Undertaking accurate exposure assessment of UVR from welding arcs is difficult, however, two studies have reported ocular/facial UVR levels underneath welding helmets (2, 3). In the first paper, UVR levels were measured using polysulphone film dosimeters applied to the cheeks of a patient who suffered from severe facial dermatitis (2). UVR levels of four times the American Conference of Governmental Industrial Hygienists (ACGIH) maximum permissible exposure (MPE) (4) were measured on the workers left cheek and nine times the MPE on the right cheek. The authors concluded that the workers dermatitis was likely to have been due to the UVR exposure received during welding. In the other paper, a comprehensive exposure assessment of personal UVR exposure of workers in a welding environment was reported (3). The study was conducted at a metal fabrication workshop with participants being welders, boilermakers and non-welders (eg, supervisors, fitters, machinists). Polysulphone film dosimeters were again used to measure UVR exposure of the workers, with badges worn on the clothing of workers (in the chest area), on the exterior of welding helmets, attached to 11 locations on the inside of welding helmets, and on the bridge and side-shields of safety spectacles. Dosimeters were also attached to surfaces throughout the workshop to measure ambient UVR levels. For welding subjects, mean 8-hour UVR doses within the welding helmets ranged from around 9 mJ/cm 2 (3×MPE) on the inside of the helmets to around 15 mJ/cm 2 (5×MPE) on the headband (a

  18. Making Ultraviolet Spectro-Polarimetry Polarization Measurements with the MSFC Solar Ultraviolet Magnetograph Sounding Rocket

    Science.gov (United States)

    West, Edward; Cirtain, Jonathan; Kobayashi, Ken; Davis, John; Gary, Allen

    2011-01-01

    This paper will describe the Marshall Space Flight Center's Solar Ultraviolet Magnetograph Investigation (SUMI) sounding rocket program. This paper will concentrate on SUMI's VUV optics, and discuss their spectral, spatial and polarization characteristics. While SUMI's first flight (7/30/2010) met all of its mission success criteria, there are several areas that will be improved for its second and third flights. This paper will emphasize the MgII linear polarization measurements and describe the changes that will be made to the sounding rocket and how those changes will improve the scientific data acquired by SUMI.

  19. Vacuum Ultraviolet Laser Probe of Chemical Dynamics of Aerospace Relevance

    Science.gov (United States)

    2012-09-12

    RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (Include area code) 09/12/12 01/15/09-11/30/11 VACUUM ULTRAVIOLET LASER PROBES OF CHEMICAL DYNAMICS PF...is to be limited. Standard Form 298 Back (Rev. 8/98) FINAL AFOSR REPORT (Dec. 1, 2008-Nov. 30, 2011) I. Grant Title: Vacuum Ultraviolet ...goal of this research program is to provide pertinent information about the energetics, photochemistry , and chemical dynamics of spacecraft effluents

  20. Luminescence enhancement of near ultraviolet light-emitting diodes

    DEFF Research Database (Denmark)

    Lin, Li; Jensen, Flemming; Herstrøm, Berit

    2016-01-01

    Nanopillars were applied on the p-GaN layer of the InGaN-based near ultraviolet epiwafer to improve the light extraction efficiency. A photoluminescence enhancement of 74 % is reported with a nanopillar height of around 105 nm.......Nanopillars were applied on the p-GaN layer of the InGaN-based near ultraviolet epiwafer to improve the light extraction efficiency. A photoluminescence enhancement of 74 % is reported with a nanopillar height of around 105 nm....

  1. Resistance of a lizard (the green anole, Anolis carolinensis; Polychridae) to ultraviolet radiation-induced immunosuppression

    Science.gov (United States)

    Cope, R.B.; Fabacher, D.L.; Lieske, C.; Miller, C.A.

    2001-01-01

    The green anole (Anolis carolinensis) is the most northerly distributed of its Neotropical genus. This lizard avoids a winter hibernation phase by the use of sun basking behaviors. Inevitably, this species is exposed to high doses of ambient solar ultraviolet radiation (UVR). Increases in terrestrial ultraviolet-B (UV-B) radiation secondary to stratospheric ozone depletion and habitat perturbation potentially place this species at risk of UVR-induced immunosuppression. Daily exposure to subinflammatory UVR (8 kJ/m2/day UV-B, 85 kJ/m2/day ultraviolet A [UV-A]), 6 days per week for 4 weeks (total cumulative doses of 192 kJ/m2 UV-B, 2.04 × 103 kJ/m2 UV-A) did not suppress the anole's acute or delayed type hypersensitivity (DTH) response to horseshoe crab hemocyanin. In comparison with the available literature UV-B doses as low as 0.1 and 15.9 kJ/m2 induced suppression of DTH responses in mice and humans, respectively. Exposure of anoles to UVR did not result in the inhibition of ex vivo splenocyte phagocytosis of fluorescein labeled Escherichia coli or ex vivo splenocyte nitric oxide production. Doses of UV-B ranging from 0.35 to 45 kJ/m2 have been reported to suppress murine splenic/peritoneal macrophage phagocytosis and nitric oxide production. These preliminary studies demonstrate the resistance of green anoles to UVR-induced immunosuppression. Methanol extracts of anole skin contained two peaks in the ultraviolet wavelength range that could be indicative of photoprotective substances. However, the resistance of green anoles to UVR is probably not completely attributable to absorption by UVR photoprotective substances in the skin but more likely results from a combination of other factors including absorption by the cutis and absorption and reflectance by various components of the dermis.

  2. Far-Ultraviolet Bidirectional Photometry of Apollo Soil 10084: Laboratory Studies in the Southwest Ultraviolet Reflectance Chamber (SwURC)

    Science.gov (United States)

    Raut, U.; Karnes, P. L.; Retherford, K. D.; Davis, M. W.; Patrick, E. L.; Liu, Y.; Mokashi, P.

    2017-10-01

    We present new far-ultraviolet bidirectional reflectance spectra of Apollo soil 10084. The FUV spectra this mare soil is featureless, though with a small blue slope. Increased reflectance at high phase imply the grains forward-scatter FUV photons.

  3. Inactivation of Pseudomonas aeruginosa biofilm after ultraviolet light-emitting diode treatment: a comparative study between ultraviolet C and ultraviolet B

    DEFF Research Database (Denmark)

    Argyraki, Aikaterini; Markvart, Merete; Bjørndal, Lars

    2017-01-01

    GaN light-emitting diodes (LEDs) was used to deliver UV irradiation on the biofilms. The effectiveness of the UVB at 296 nm and UVC at 266 nm irradiations was quantified by counting colony-forming units. The survival of less mature biofilms (24 h grown) was studied as a function of UV-radiant exposure. All......The objective of this study was to test the inactivation efficiency of two different light-based treatments, namely ultraviolet B (UVB) and ultraviolet C (UVC) irradiation, on Pseudomonas aeruginosa biofilms at different growth stages (24, 48, and 72 h grown). In our experiments, a type of Al...

  4. Rapid modulation of ultraviolet shielding in plants is influenced by solar ultraviolet radiation and linked to alterations in flavonoids.

    Science.gov (United States)

    Barnes, Paul W; Tobler, Mark A; Keefover-Ring, Ken; Flint, Stephan D; Barkley, Anne E; Ryel, Ronald J; Lindroth, Richard L

    2016-01-01

    The accumulation of ultraviolet (UV)-absorbing compounds (flavonoids and related phenylpropanoids) and the resultant decrease in epidermal UV transmittance (TUV ) are primary protective mechanisms employed by plants against potentially damaging solar UV radiation and are critical components of the overall acclimation response of plants to changing solar UV environments. Whether plants can adjust this UV sunscreen protection in response to rapid changes in UV, as occurs on a diurnal basis, is largely unexplored. Here, we use a combination of approaches to demonstrate that plants can modulate their UV-screening properties within minutes to hours, and these changes are driven, in part, by UV radiation. For the cultivated species Abelmoschus esculentus, large (30-50%) and reversible changes in TUV occurred on a diurnal basis, and these adjustments were associated with changes in the concentrations of whole-leaf UV-absorbing compounds and several quercetin glycosides. Similar results were found for two other species (Vicia faba and Solanum lycopersicum), but no such changes were detected in Zea mays. These findings reveal a much more dynamic UV-protection mechanism than previously recognized, raise important questions concerning the costs and benefits of UV-protection strategies in plants and have practical implications for employing UV to enhance crop vigor and quality in controlled environments. © 2015 John Wiley & Sons Ltd.

  5. A Far-Ultraviolet Study of the Cygnus Loop Using the VOYAGER Ultraviolet Spectrometers

    Science.gov (United States)

    Vancura, Olaf; Blair, William P.; Long, Knox S.; Raymond, John C.; Holberg, J. B.

    1993-01-01

    We have used the Voyager 1 and 2 Ultraviolet Spectrometers to study the far-ultraviolet emissions from different types of shock waves in the Cygnus Loop. In the southeast and northern parts of the supernova remnant (SNR), we have measured the O(VI) lambda1035 surface brightness from the main blast wave. This value is several times below the average and more than one order of magnitude below the peak O(VI) brightness in the SNR as measured with Voyager. A simple blast wave model appears able to reproduce the observations in the southeast and the northern parts of the Cygnus Loop but can only account for 10%-15% of the total O(VI) emission from the Cygnus Loop. The brightest O(VI) and C(III) lambda977 emission is found coincident with optical filamentation and X-ray enhancements in the northeast. We interpret the observations in the northeast in terms of nonradiative and incomplete shocks whose surface area rises in the optical filamentary regions. We conclude that the bulk of the O(VI) emission from the Cygnus Loop arises from optically bright clouds within which intermediate-velocity (200 + 50 km/s) nonradiative and incomplete shocks are widespread.

  6. The influence of the environment and clothing on human exposure to ultraviolet light.

    Science.gov (United States)

    Liu, Jin; Zhang, Wei

    2015-01-01

    The aim of this study is to determine the effect of clothing and the environment on human exposure to ultraviolet light. The ultraviolet (ultraviolet A and ultraviolet B) light intensity was measured, and air quality parameters were recorded in 2014 in Beijing, China. Three types of clothing (white polyester cloth, pure cotton white T-shirt, and pure cotton black T-shirt) were individually placed on a mannequin. The ultraviolet (ultraviolet A and ultraviolet B) light intensities were measured above and beneath each article of clothing, and the percentage of ultraviolet light transmission through the clothing was calculated. (1) The ultraviolet light transmission was significantly higher through white cloth than through black cloth; the transmission was significantly higher through polyester cloth than through cotton. (2) The weather significantly influenced ultraviolet light transmission through white polyester cloth; transmission was highest on clear days and lowest on overcast days (ultraviolet A: P=0.000; ultraviolet B: P=0.008). (3) Air quality parameters (air quality index and particulate matter 2.5 and 10) were inversely related to the ultraviolet light intensity that reached the earth's surface. Ultraviolet B transmission through white polyester cloth was greater under conditions of low air pollution compared with high air pollution. Clothing color and material and different types of weather affected ultraviolet light transmission; for one particular cloth, the transmission decreased with increasing air pollution.

  7. The influence of the environment and clothing on human exposure to ultraviolet light.

    Directory of Open Access Journals (Sweden)

    Jin Liu

    Full Text Available The aim of this study is to determine the effect of clothing and the environment on human exposure to ultraviolet light.The ultraviolet (ultraviolet A and ultraviolet B light intensity was measured, and air quality parameters were recorded in 2014 in Beijing, China. Three types of clothing (white polyester cloth, pure cotton white T-shirt, and pure cotton black T-shirt were individually placed on a mannequin. The ultraviolet (ultraviolet A and ultraviolet B light intensities were measured above and beneath each article of clothing, and the percentage of ultraviolet light transmission through the clothing was calculated.(1 The ultraviolet light transmission was significantly higher through white cloth than through black cloth; the transmission was significantly higher through polyester cloth than through cotton. (2 The weather significantly influenced ultraviolet light transmission through white polyester cloth; transmission was highest on clear days and lowest on overcast days (ultraviolet A: P=0.000; ultraviolet B: P=0.008. (3 Air quality parameters (air quality index and particulate matter 2.5 and 10 were inversely related to the ultraviolet light intensity that reached the earth's surface. Ultraviolet B transmission through white polyester cloth was greater under conditions of low air pollution compared with high air pollution.Clothing color and material and different types of weather affected ultraviolet light transmission; for one particular cloth, the transmission decreased with increasing air pollution.

  8. Atomic Oscillator Strengths In The Vacuum Ultraviolet

    Science.gov (United States)

    Nave, Gillian; Sansonetti, C. J.; Szabo, C. I.

    2008-05-01

    Transitionsin singly-ionized and doubly-ionized iron-group elements give rise to prominent emission lines from a wide variety of astrophysical objects. Although the database of experimental oscillator strengths of Fe II has also been greatly extended by the FERRUM project, few experimental oscillator strengths are available in the region below 1600 Å, where many levels that give rise to emission lines at longer wavelengths have their dominant decays. The established way to measure accurate oscillator strengths for atomic lines combines the measurement of a lifetime of an upper energy level with a separate measurement of the branching fractions of all the lines emitted from that level. This technique relies on being able to observe all the spectral lines emitted by the upper level, which range down to Ly-α or below for many fluorescence lines. We have developed techniques to measure branching fractions in the vacuum ultraviolet using our 10.7-m normal incidence grating spectrograph. For this we use phosphor image plates as replacements for the photographic plates previously used on this instrument. Image plates are sensitive to wavelengths from the X-ray region to 2200 Å, and have a linear intensity response with a dynamic range of at least 10000. We have recorded spectra of iron-neon hollow cathode and Penning discharges, using a deuterium standard lamp for radiometric calibration. We will present the first measurements of oscillator strengths using this technique. We are also investigating methods of radiometric calibration below 1150 Å using hollow cathode standard lamps. This will enable us to measure branching ratios down to 800 Å or below. This work is partially funded by NASA under the inter-agency agreement W-10,255.

  9. Interstellar Silicon Depletion and the Ultraviolet Extinction

    Science.gov (United States)

    Mishra, Ajay; Li, Aigen

    2018-01-01

    Spinning small silicate grains were recently invoked to account for the Galactic foreground anomalous microwave emission. These grains, if present, will absorb starlight in the far ultraviolet (UV). There is also renewed interest in attributing the enigmatic 2175 Å interstellar extinction bump to small silicates. To probe the role of silicon in the UV extinction, we explore the relations between the amount of silicon required to be locked up in silicates [Si/H]dust and the 2175 Å bump or the far-UV extinction rise, based on an analysis of the extinction curves along 46 Galactic sightlines for which the gas-phase silicon abundance [Si/H]gas is known. We derive [Si/H]dust either from [Si/H]ISM - [Si/H]gas or from the Kramers- Kronig relation which relates the wavelength-integrated extinction to the total dust volume, where [Si/H]ISM is the interstellar silicon reference abundance and taken to be that of proto-Sun or B stars. We also derive [Si/H]dust from fi�tting the observed extinction curves with a mixture of amorphous silicates and graphitic grains. We fi�nd that in all three cases [Si/H]dust shows no correlation with the 2175 Å bump, while the carbon depletion [C/H]dust tends to correlate with the 2175 Å bump. This supports carbon grains instead of silicates as the possible carrier of the 2175 Å bump. We also �find that neither [Si/H]dust nor [C/H]dust alone correlates with the far-UV extinction, suggesting that the far-UV extinction is a combined effect of small carbon grains and silicates.

  10. Red tattoos, ultraviolet radiation and skin cancer in mice.

    Science.gov (United States)

    Lerche, Catharina M; Heerfordt, Ida M; Serup, Jørgen; Poulsen, Thomas; Wulf, Hans Christian

    2017-11-01

    Ultraviolet radiation (UVR) induces skin cancer. The combination of UVR and red tattoos may be associated with increased risk of skin cancer due to potential carcinogens in tattoo inks. This combination has not been studied previously. Immunocompetent C3.Cg/TifBomTac hairless mice (n=99) were tattooed on their back with a popular red tattoo ink. This often used ink is banned for use on humans because of high content of the potential carcinogen 2-anisidine. Half of the mice were irradiated with three standard erythema doses UVR thrice weekly. Time to induction of first, second and third squamous cell carcinoma (SCC) was measured. All UV-irradiated mice developed SCCs. The time to the onset of the first and second tumor was identical in the red-tattooed group compared with the control group (182 vs 186 days and 196 vs 203 days, P=ns). Statistically, the third tumor appeared slightly faster in the red-tattooed group than in the controls (214 vs 224 days, P=.043). For the second and third tumor, the growth rate was faster in the red-tattooed group compared with the control (31 vs 49 days, P=.009 and 30 vs 38 days, P=.036). In conclusion, no spontaneous cancers were observed in skin tattooed with a red ink containing 2-anisidine. However, red tattoos exposed to UVR showed faster tumor onset regarding the third tumor, and faster growth rate of the second and third tumor indicating red ink acts as a cocarcinogen with UVR. The cocarcinogenic effect was weak and may not be clinically relevant. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Ultraviolet analysis of Eta Carinae using observations from the InternationalUltraviolet Explorer

    Science.gov (United States)

    Durofchalk, Nicholas C.; Gimar, Caleb J.; Gull, Theodore R.

    2015-01-01

    Presented here is an examination of data on the Eta Carinae binary star system obtained by the International Ultraviolet Explorer (IUE) satellite that was in operation from 1978 to 1996. The data were searched for (1) evidence of an ultraviolet flux increase over the time period of IUE's operation and (2) additional evidence for the 5.54-year cycle observed by A. Daminelli et al. This investigation focused on the emission lines of [N III] at 1750Å, Fe II at 1786Å, Si III at 1893Å, Fe III at 1914Å, and Fe II at 2507/2509Å. Through the examination of emission line profiles from IUE ultraviolet spectra, quantitative values for integrated and continuum flux were measured in roughly eighty observations. The fluxes for individual emission line profiles were compared over time and at different phases of the superimposed 5.54 year cycle. In addition, values for emission flux were plotted against time so as to visualize the system's behavior over a multi-cycle time interval. Observations recorded during the brief low-state, periastron event, while few in number, were consistent with the 5.54 period. Fluxes of the [N III], Si III, and Fe III emission features noted previously had increased across the 18-year interval. However, the Fe II emission lines did not show significant long-term flux increases. Examination of the Grotian diagram for Fe+ demonstrated that hydrogen Lyman alpha can excite the outer electron from the ground state to upper levels, leading to population inversion and over-intensity of the Fe II emissions (Johansson & Letokhov, 2003). Likely, the different 'long-term' behaviors of the [N III], Si III, and Fe III emission lines and the Fe II emission lines arose from the very different physical phenomena that lead to each particular emission lines' existence. The consistency of the Fe II emission fluxes indicated that Eta Carinae's secondary stellar Lyman continuum flux was constant, leading to the conclusion that there was little change, if any, in the

  12. Ultraviolet-B Protective Effect of Flavonoids from Eugenia caryophylata on Human Dermal Fibroblast Cells.

    Science.gov (United States)

    Patwardhan, Juilee; Bhatt, Purvi

    2015-10-01

    The exposure of skin to ultraviolet-B (UV-B) radiations leads to deoxyribonucleic acid (DNA) damage and can induce production of free radicals which imbalance the redox status of the cell and lead to increased oxidative stress. Clove has been traditionally used for its analgesic, anti-inflammatory, anti-microbial, anti-viral, and antiseptic effects. To evaluate the UV-B protective activity of flavonoids from Eugenia caryophylata (clove) buds on human dermal fibroblast cells. Protective ability of flavonoid-enriched (FE) fraction of clove was studied against UV-B induced cytotoxicity, anti-oxidant regulation, oxidative DNA damage, intracellular reactive oxygen species (ROS) generation, apoptotic morphological changes, and regulation of heme oxygenase-1 (HO-1) gene through nuclear factor E2-related factor 2 antioxidant response element (Nrf2 ARE) pathway. FE fraction showed a significant antioxidant potential. Pretreatment of cells with FE fraction (10-40 μg/ml) reversed the effects of UV-B induced cytotoxicity, depletion of endogenous enzymatic antioxidants, oxidative DNA damage, intracellular ROS production, apoptotic changes, and overexpression of Nrf2 and HO-1. The present study demonstrated for the first time that the FE fraction from clove could confer UV-B protection probably through the Nrf2-ARE pathway, which included the down-regulation of Nrf2 and HO-1. These findings suggested that the flavonoids from clove could potentially be considered as UV-B protectants and can be explored further for its topical application to the area of the skin requiring protection. Pretreatment of human dermal fibroblast with flavonoid-enriched fraction of Eugenia caryophylata attenuated effects of ultraviolet-B radiationsIt also conferred protection through nuclear factor E2-related factor 2-antioxidant response pathway and increased tolerance of cells against oxidative stressFlavonoid-enriched fraction can be explored further for topical application to the skin as a

  13. A Role for Lsm1p in Response to Ultraviolet-Radiation Damage in Saccharomyces cerevisiae

    OpenAIRE

    Spicakova, Tatiana; McCann, Kelly; Brown, J. Martin

    2008-01-01

    A genome-wide screen in Saccharomyces cerevisiae identified LSM1 as a new gene affecting sensitivity to ultraviolet (UV) radiation. Lsm1p is a member of a cytoplasmic complex composed of Lsm1p–7p that interacts with the yeast mRNA degradation machinery. To investigate the potential role of Lsm1p in response to UV radiation, we constructed double mutant strains in which LSM1 was deleted in combination with a representative gene from each of three known yeast DNA repair pathways. Our results sh...

  14. End-to-End Assessment of a Large Aperture Segmented Ultraviolet Optical Infrared (UVOIR) Telescope Architecture

    Science.gov (United States)

    Feinberg, Lee; Bolcar, Matt; Liu, Alice; Guyon, Olivier; Stark,Chris; Arenberg, Jon

    2016-01-01

    Key challenges of a future large aperture, segmented Ultraviolet Optical Infrared (UVOIR) Telescope capable of performing a spectroscopic survey of hundreds of Exoplanets will be sufficient stability to achieve 10-10 contrast measurements and sufficient throughput and sensitivity for high yield Exo-Earth spectroscopic detection. Our team has collectively assessed an optimized end to end architecture including a high throughput coronagraph capable of working with a segmented telescope, a cost-effective and heritage based stable segmented telescope, a control architecture that minimizes the amount of new technologies, and an Exo-Earth yield assessment to evaluate potential performance.

  15. Detoxification of Jatropha curcas oil by ultraviolet irradiation combined with ethanol washing

    OpenAIRE

    Xiao, JH; Mao, X.; Zhang, H.; Niu, L

    2015-01-01

    Jatropha curcas oil (JCO) is non-edible due to the content of phorbolesters (PEs) which are very toxic. The aim of this study was to evaluate the potential of JCO, treated by ultraviolet irradiation combined with ethanol washing, as an edible oil. The results showed that PEs can be significantly decreased by 100% (p < 0.05), but the treatments produced no significant changes (p < 0.05) in the fatty acids composition (FAC) and triacylglycerols (TAGs) in the detoxified Jatropha curcas oil (DJCO...

  16. Vacuum ultraviolet light source utilizing rare gas scintillation amplification sustained by photon positive feedback

    Science.gov (United States)

    Aprile, Elena (Inventor); Chen, Danli (Inventor)

    1995-01-01

    A source of light in the vacuum ultraviolet (VUV) spectral region includes a reflective UV-sensitive photocathode supported in spaced parallel relationship with a mesh electrode within a rare gas at low pressure. A high positive potential applied to the mesh electrode creates an electric field which causes drifting of free electrons occurring between the electrodes and producing continuous VUV light output by electric field-driven scintillation amplification sustained by positive photon feedback mediated by photoemission from the photocathode. In one embodiment the lamp emits a narrow-band continuum peaked at 175 nm.

  17. Ultraviolet-Fluorescent Tattoo Facilitates Accurate Identification of Biopsy Sites.

    Science.gov (United States)

    Russell, Kathryn; Schleichert, Rachel; Baum, Bertha; Villacorta, Miguel; Hardigan, Patrick; Thomas, Jacqueline; Weiss, Eduardo

    2015-11-01

    Cutaneous biopsy sites are often difficult to discern or are frequently misidentified when patients present for the treatment of skin cancers. This frustrating situation can lead to delays in treatment and wrong site surgeries. Current methods aiming to prevent this situation are not perfect. This study seeks to determine the efficacy of ultraviolet-fluorescent tattoos in facilitating the correct identification of suspected nonmelanoma skin cancer biopsy sites. In this prospective cohort, 51 shave biopsy sites were tattooed with ultraviolet-fluorescent ink in a series of 31 patients suspected of having a cutaneous malignancy. At the time of follow-up, the ability of the patient and the physician to identify the correct site with and without ultraviolet illumination of the tattoo was recorded. Visibility of the tattoo was graded before and after treatment. Patients could not positively identify their biopsy site in 35% of cases. In 7% of cases, physicians could not confidently identify the site without the aid of ultraviolet illumination. In conjunction with tattoo illumination, physicians confidently identified the site in 100% of the cases. No adverse events occurred. Ultraviolet-fluorescent tattoos offer a safe and reliable means of accurately marking cutaneous biopsy sites.

  18. Cockayne syndrome with delayed recovery of RNA synthesis after ultraviolet irradiation but normal ultraviolet survival

    Energy Technology Data Exchange (ETDEWEB)

    Sugita, K.; Suzuki, N.; Kojima, T.; Tanabe, Y.; Nakajima, H.; Hayashi, A.; Arima, M.

    1987-01-01

    We report a girl with Cockayne syndrome (CS) with atypical cellular features. We studied the ultraviolet (UV)-sensitivity of cultured fibroblast cells derived from this case and male CS siblings as positive controls. Cells from this female with CS displayed normal unscheduled DNA synthesis and repair replication capacity. However, the cells also displayed a less depressed level of RNA synthesis after UV irradiation, compared to control CS cells, and showed normal UV survival. This CS case with early onset of abnormalities had more serious clinical manifestations than the control CS siblings. These cytological results suggest that there is considerable clinical and cellular heterogeneity in CS and that cellular sensitivity to UV might not be as essential for the diagnosis of CS as previously thought.

  19. Solar ultraviolet radiation from cancer induction to cancer prevention: solar ultraviolet radiation and cell biology.

    Science.gov (United States)

    Tuorkey, Muobarak J

    2015-09-01

    Although decades have elapsed, researchers still debate the benefits and hazards of solar ultraviolet radiation (UVR) exposure. On the one hand, humans derive most of their serum 25-hydroxycholecalciferol [25(OH)D3], which has potent anticancer activity, from solar UVB radiation. On the other hand, people are more aware of the risk of cancer incidence associated with harmful levels of solar UVR from daily sunlight exposure. Epidemiological data strongly implicate UV radiation exposure as a major cause of melanoma and other cancers, as UVR promotes mutations in oncogenes and tumor-suppressor genes. This review highlights the impact of the different mutagenic effects of solar UVR, along with the cellular and carcinogenic challenges with respect to sun exposure.

  20. The LUVOIR Ultraviolet Multi-Object Spectrograph (LUMOS): instrument definition and design

    Science.gov (United States)

    France, Kevin; Fleming, Brian; West, Garrett; McCandliss, Stephan R.; Bolcar, Matthew R.; Harris, Walter; Moustakas, Leonidas; O'Meara, John M.; Pascucci, Ilaria; Rigby, Jane; Schiminovich, David; Tumlinson, Jason

    2017-08-01

    arcminute field-of-view) that will employ a complement of narrow- and medium-band filters. The instrument definition, design, and development are being carried out by an instrument study team led by the University of Colorado, Goddard Space Flight Center, and the LUVOIR Science and Technology Definition Team. LUMOS has recently completed a preliminary design in Goddard's Instrument Design Laboratory and is being incorporated into the working LUVOIR mission concept. In this proceeding, we describe the instrument requirements for LUMOS, the instrument design, and technology development recommendations to support the hardware required for LUMOS. We present an overview of LUMOS' observing modes and estimated performance curves for effective area, spectral resolution, and imaging performance. Example "LUMOS 100-hour Highlights" observing programs are presented to demonstrate the potential power of LUVOIR's ultraviolet spectroscopic capabilities.

  1. How does radiative feedback from an ultraviolet background impact reionization?

    Science.gov (United States)

    Sobacchi, Emanuele; Mesinger, Andrei

    2013-07-01

    An ionizing ultraviolet background (UVB) inhibits gas accretion and photoevaporates gas from the shallow potential wells of small, dwarf galaxies. During cosmological reionization, this effect can result in negative feedback: suppressing star formation inside H II regions, thus impeding their continued growth. It is difficult to model this process, given the enormous range of scales involved. We tackle this problem using a tiered approach: combining parametrized results from single-halo collapse simulations with large-scale models of reionization. In the resulting reionization models, the ionizing emissivity of galaxies depends on the local values of the reionization redshift and the UVB intensity. We present a physically motivated analytic expression for the average minimum mass of star-forming galaxies, Mmin, which can be readily used in modelling galaxy formation. We find that UVB feedback: (i) delays the end stages of reionization by Δz ≲ 0.5; (ii) results in a more uniform distribution of H II regions, peaked on smaller scales (with large-scale ionization power suppressed by 10s of per cent) and (iii) suppresses the global photoionization rate per baryon by a factor of ≲2 towards the end of reionization. However, the impact is modest, since the hydrodynamic response of the gas to the UVB occurs on a time-scale comparable to reionization. In particular, the popular approach of modelling UVB feedback with an instantaneous transition in Mmin, dramatically overestimates its importance. UVB feedback on galaxies does not significantly affect reionization unless: (i) molecularly cooled galaxies contribute significantly to reionization; or (ii) internal feedback processes strongly couple with UVB feedback in the early Universe. Since both are considered unlikely, we conclude that there is no significant self-regulation of reionization by UVB feedback.

  2. Ultraviolet and radio flares from UX Arietis and HR 1099

    Science.gov (United States)

    Lang, Kenneth R.; Willson, Robert F.

    1988-01-01

    Simultaneous observations of the RS CVn systems UX Ari and HR 1099 with the IUE satellite and the VLA are presented. Flaring activity is observed at ultraviolet wavelengths with the IUE when none is detected at radio wavelengths with the VLA. Radio flares with no detectable ultraviolet activity have also been observed. Thus, flares in the two spectral regions are either uncorrelated or weakly correlated. The flaring emission probably originates in different regions at the two wavelengths. Radio flares from RS CVn stars may originate in sources that are larger than, or comparable to, a star in size. This is in sharp contrast to compact, coherent radio flares from dwarf M stars. The ultraviolet flares from RS CVn stars probably originate in sources that are smaller than a component star.

  3. Application of Ultraviolet Light in Dental Identification of Avalanche Victims.

    Science.gov (United States)

    Agrawal, Nitin Kumar; Dahal, Samarika; Wasti, Harihar; Soon, Alistair

    2017-09-08

    In any disaster, it becomes important to identify the deceased for ethical, social and legal causes.Out of the numerous methods of identification, dental comparison is considered to be one of the scientific methods in a Disaster Victim Identification process. The two victims of avalanche in Nepal were identified using dental comparison. The two bodies brought for examination were unidentifiable visually. To aid identification of tooth coloured restorations, ultraviolet light was used. The ultraviolet light made the tooth coloured restorations appear distinct from the adjacent tooth structure in one of the cases. This helped in post-mortem charting of dental examination with greater accuracy. When the ante-mortem dental records and the post-mortem dental findings were compared, positive identification was made for both the cases. The bodies were then handed over to their respective kin. These cases highlighted the importance of ultraviolet light in post-mortem dental examination and the significance of forensic dentistry in identification process.

  4. Measurement and analysis of near ultraviolet solar radiation

    Science.gov (United States)

    Mehos, M. S.; Pacheco, K. A.; Link, H. F.

    1991-12-01

    The photocatalytic detoxification of organic contaminants is currently being investigated by a number of laboratories, universities, and institutions throughout the world. The photocatalytic oxidation process requires that contaminants come in contact with a photocatalyst such as titanium dioxide, under illumination of ultraviolet (UV) radiation in order for the decomposition reaction to take place. Researches from the National Renewable Energy Laboratory (NREL) and Sandia National Laboratories are currently investigating the use of solar energy as a means of driving this photocatalytic process. Measurements of direct-normal and global horizontal ultraviolet (280 to 385 nm) and full spectrum (280 to 4000 nm) solar radiation taken in Golden, Colorado over a one-year period are analyzed, and comparisons are made with data generated from a clear sky solar radiation model (BRITE) currently in use for predicting the performance of solar detoxification processes. Analysis of the data indicates a ratio of global horizontal ultraviolet to full spectrum radiation of 4 to 6 pct. that is weakly dependent on air mass. Conversely, data for direct normal ultraviolet radiation indicate a much larger dependence on air mass, with a ratio of approx. 5 pct. at low air mass to 1 pct. at higher masses. Results show excellent agreement between the measured data and clear sky predictions for both the ultraviolet and the full spectrum global horizontal radiation. For the direct normal components, however, the tendency is for the clear sky model to underpredict the measured data. Averaged monthly ultraviolet radiation available for the detoxification process indicates that the global horizontal component of the radiation exceeds the direct normal component throughout the year.

  5. Measurement and analysis of near ultraviolet solar radiation

    Energy Technology Data Exchange (ETDEWEB)

    Mehos, M.S.; Pacheco, K.A.; Link, H.F.

    1991-12-01

    The photocatalytic detoxification of organic contaminants is currently being investigated by a number of laboratories, universities, and institutions throughout the world. The photocatalytic oxidation process requires that contaminants come in contact with a photocatalyst such as titanium dioxide, under illumination of ultraviolet (UV) radiation in order for the decomposition reaction to take place. Researches from the National Renewable Energy Laboratory (NREL) and Sandia National Laboratories are currently investigating the use of solar energy as a means of driving this photocatalytic process. Measurements of direct-normal and global-horizontal ultraviolet (280--385 nm) and full-spectrum (280--4000 nm) solar radiation taken in Golden, Colorado over a one-year period are analyzed, and comparisons are made with data generated from a clear-sky solar radiation model (BRITE) currently in use for predicting the performance of solar detoxification processes. Analysis of the data indicates a ratio of global-horizontal ultraviolet to full-spectrum radiation of 4%--6% that is weakly dependent on air mass. Conversely, data for direct-normal ultraviolet radiation indicate a much large dependence on air mass, with a ratio of approximately 5% at low air mass to 1% at higher at masses. Results show excellent agreement between the measured data and clear-sky predictions for both the ultraviolet and the full-spectrum global-horizontal radiation. For the direct-normal components, however, the tendency is for the clear-sky model to underpredict the measured that. Averaged monthly ultraviolet radiation available for the detoxification process indicates that the global-horizontal component of the radiation exceeds the direct-normal component throughout the year. 9 refs., 7 figs.

  6. Ultraviolet Phototherapy Management of Moderate-to-Severe Plaque Psoriasis

    Science.gov (United States)

    2009-01-01

    Executive Summary Objective The purpose of this evidence based analysis was to determine the effectiveness and safety of ultraviolet phototherapy for moderate-to-severe plaque psoriasis. Research Questions The specific research questions for the evidence review were as follows: What is the safety of ultraviolet phototherapy for moderate-to-severe plaque psoriasis? What is the effectiveness of ultraviolet phototherapy for moderate-to-severe plaque psoriasis? Clinical Need: Target Population and Condition Psoriasis is a common chronic, systemic inflammatory disease affecting the skin, nails and occasionally the joints and has a lifelong waning and waxing course. It has a worldwide occurrence with a prevalence of at least 2% of the general population, making it one of the most common systemic inflammatory diseases. The immune-mediated disease has several clinical presentations with the most common (85% - 90%) being plaque psoriasis. Characteristic features of psoriasis include scaling, redness, and elevation of the skin. Patients with psoriasis may also present with a range of disabling symptoms such as pruritus (itching), pain, bleeding, or burning associated with plaque lesions and up to 30% are classified as having moderate-to-severe disease. Further, some psoriasis patients can be complex medical cases in which diabetes, inflammatory bowel disease, and hypertension are more likely to be present than in control populations and 10% also suffer from arthritis (psoriatic arthritis). The etiology of psoriasis is unknown but is thought to result from complex interactions between the environment and predisposing genes. Management of psoriasis is related to the extent of the skin involvement, although its presence on the hands, feet, face or genitalia can present challenges. Moderate-to-severe psoriasis is managed by phototherapy and a range of systemic agents including traditional immunosuppressants such as methotrexate and cyclospsorin. Treatment with modern

  7. An Empirical Ultraviolet Iron Spectrum Template Applicable to Active Galaxies

    DEFF Research Database (Denmark)

    Vestergaard, Marianne; Wilkes, B. J.

    2001-01-01

    Iron emission is often a severe contaminant in optical-ultraviolet spectra of active galaxies. Its presence complicates emission line studies. A viable solution, already successfully applied at optical wavelengths, is to use an empirical iron emission template. We have generated FeII and Fe......III templates for ultraviolet active galaxy spectra based on HST archival 1100 - 3100 A spectra of IZw1. Their application allows fitting and subtraction of the iron emission in active galaxy spectra. This work has shown that in particular CIII] lambda 1909 can be heavily contaminated by other line emission...

  8. Enhancements in biologically effective ultraviolet radiation following volcanic eruptions.

    Science.gov (United States)

    Vogelmann, A M; Ackerman, T P; Turco, R P

    1992-09-03

    Aerosols injected into the stratosphere by large volcanic eruptions may induce ozone destruction through processes including heterogeneous chemical reactions. The effect of ozone reductions on surface ultraviolet irradiation is not obvious, however, because aerosols also increase the reflection of sunlight. Here we use a radiative transfer model to estimate the changes in biologically effective ultraviolet radiation (UV-BE) at the Earth's surface produced by the El Chichón (1982) and Mount Pinatubo (1991) eruptions. We find that in both cases surface UV-BE intensity can increase because the effect of ozone depletion outweighs the increased scattering.

  9. Calibration of the Swift-UVOT ultraviolet and visible grisms

    OpenAIRE

    Kuin, N. P. M.; Landsman, W.; Breeveld, A. A.; Page, M. J.; Lamoureux, H.; James, C.; Mehdipour, M.; Still, M.; Yershov, V.; Brown, P.J.; Carter, M; Mason, K. O.; Kennedy, T.; Marshall, F.; Roming, P. W. A.

    2015-01-01

    We present the calibration of the Swift Ultraviolet and Optical Telescope (UVOT ) grisms, of which there are two, providing low-resolution field spectroscopy in the ultraviolet and optical bands, respectively. The UV grism covers the range λ1700–5000 Å with a spectral resolution (λ/Δλ) of 75 at λ2600 Å for source magnitudes of u=10–16 mag, while the visible grism covers the range λ2850–6600 Å with a spectral resolution of 100 at λ4000 Å for source magnitudes of b=12–17 mag. This calibration e...

  10. Disease: H01663 [KEGG MEDICUS

    Lifescience Database Archive (English)

    Full Text Available o be first-line therapies for those with GPP. Adalimumab, etanercept, and psoralen plus ultraviolet A are second-line moda...rms alter which agents are first-line modalities as concerns such as teratogenici

  11. CHIH-DFT determination of the molecular structure and infrared and ultraviolet spectra of gamma-solanine.

    Science.gov (United States)

    Glossman-Mitnik, Daniel

    2007-01-01

    Glycoalkaloids are toxic secondary plant metabolites found in potatoes, tomatoes, and eggplants and they are considered potential precursors of steroids for applications in bionanotechnology. In this work, we make use of a new model chemistry within density functional theory, which is called CHIH-DFT, to calculate the molecular structure of gamma-solanine, as well to predict its infrared (IR) and ultraviolet (UV-vis) spectra, and some other electronic parameters.

  12. CHIH-DFT determination of the molecular structure and infrared and ultraviolet spectra of γ-solanine

    Science.gov (United States)

    Glossman-Mitnik, Daniel

    2007-01-01

    Glycoalkaloids are toxic secondary plant metabolites found in potatoes, tomatoes, and eggplants and they are considered potential precursors of steroids for applications in bionanotechnology. In this work, we make use of a new model chemistry within density functional theory, which is called CHIH-DFT, to calculate the molecular structure of γ-solanine, as well to predict its infrared (IR) and ultraviolet (UV-vis) spectra, and some other electronic parameters.

  13. The ultraviolet detection component based on Te-Cs image intensifier

    Science.gov (United States)

    Qian, Yunsheng; Zhou, Xiaoyu; Wu, Yujing; Wang, Yan; Xu, Hua

    2017-05-01

    Ultraviolet detection technology has been widely focused and adopted in the fields of ultraviolet warning and corona detection for its significant value and practical meaning. The component structure of ultraviolet ICMOS, imaging driving and the photon counting algorithm are studied in this paper. Firstly, the one-inch and wide dynamic range CMOS chip with the coupling optical fiber panel is coupled to the ultraviolet image intensifier. The photocathode material in ultraviolet image intensifier is Te-Cs, which contributes to the solar blind characteristic, and the dual micro-channel plates (MCP) structure ensures the sufficient gain to achieve the single photon counting. Then, in consideration of the ultraviolet detection demand, the drive circuit of the CMOS chip is designed and the corresponding program based on Verilog language is written. According to the characteristics of ultraviolet imaging, the histogram equalization method is applied to enhance the ultraviolet image and the connected components labeling way is utilized for the ultraviolet single photon counting. Moreover, one visible light video channel is reserved in the ultraviolet ICOMS camera, which can be used for the fusion of ultraviolet and visible images. Based upon the module, the ultraviolet optical lens and the deep cut-off solar blind filter are adopted to construct the ultraviolet detector. At last, the detection experiment of the single photon signal is carried out, and the test results are given and analyzed.

  14. Modeling Ultraviolet (UV) Light Emitting Diode (LED) Energy Propagation in Reactor Vessels

    Science.gov (United States)

    2014-03-27

    concern is through Advanced Oxidation Processes (AOP). One such process uses ultraviolet (UV) energy to decompose hydrogen peroxide ( H2O2 ) to create...MODELING ULTRAVIOLET (UV) LIGHT EMITTING DIODE (LED) ENERGY PROPAGATION IN REACTOR VESSELS THESIS...

  15. Pengaruh Iradiasi Ultraviolet Terhadap Multiplikasi Tunas Aksiler Dan Kadar Klorofil Anyelir (Dianthus Caryophyllus L.)

    OpenAIRE

    Afza, Higa; Iriawati, nFN

    2015-01-01

    Ultraviolet (UV) is one of the lights spectrum that causes plant cell to damage. The use of ultraviolet irradiation in combination with tissue culture techniques has not been widely used in somaclonal variation method for carnation breeding, whereas the source of ultraviolet irradiation is more easily obtained compared to other sources of irradiation such as gamma rays, x-rays and neutron rays. The purpose of this study was to determine effect of ultraviolet irradiation on the multiplication ...

  16. An assessment of ultraviolet radiation components of light emitted ...

    African Journals Online (AJOL)

    The study of Ultraviolet Radiation has of recent become interesting because of the health hazards it poses to human. Apart from its intensity reaching the earth from the sun, other man-made sources have been identified. We have undertaken the measurement of UV radiation from electric arc welding light generated by 240 ...

  17. Ultraviolet Curable Powder Coatings With Robotic Curing for Aerospace Applications

    Science.gov (United States)

    2011-02-01

    hazardous diisocyanates Contains or requires volatile solvent use Significant hazardous waste costs Hazardous materials pose risks to human health and...24 January 2011. ESTCP Project WP-0801 The WP-0801 Objectives are: Demonstrate a VOC/HAP-free, diisocyanate free, Ultraviolet cure powder coating

  18. High power AlGaN ultraviolet light emitters

    Science.gov (United States)

    Shatalov, Max; Sun, Wenhong; Jain, Rakesh; Lunev, Alex; Hu, Xuhong; Dobrinsky, Alex; Bilenko, Yuri; Yang, Jinwei; Garrett, Gregory A.; Rodak, Lee E.; Wraback, Michael; Shur, Michael; Gaska, Remis

    2014-06-01

    We present the analysis of the external quantum efficiency in AlGaN deep ultraviolet (DUV) light-emitting diodes (LEDs) on sapphire substrates and discuss factors affecting the output power of DUV LEDs. Performance of the LED is related to optimization of the device structure design and improvements of the epitaxial material quality.

  19. Ultraviolet B radiation therapy for psoriasis: Pursuing the optimal regime

    NARCIS (Netherlands)

    Matos, Tiago R.; Ling, Tsui C.; Sheth, Vaneeta

    2016-01-01

    Psoriasis is a chronic and common disease mediated by resident memory T cells that negatively affects a broad range of people worldwide. One of the oldest and most commonly used treatments is phototherapy. We reviewed the existing literature on the four main ultraviolet B (UVB) modalities of

  20. Ultraviolet and environmental stresses involved in the induction and ...

    African Journals Online (AJOL)

    Ultraviolet takes up 7% of sunlight and it stimulates distinct responses in plant. Both UV-A and low influence of UV-B can induce the accumulation of anthocyanin via induction of the expression of anthocyanin biosynthesis genes. Besides, the modulation of anthocyanin by environmental and developmental factors has been ...

  1. Elastic modulus of Extreme Ultraviolet exposed single-layer graphene

    NARCIS (Netherlands)

    Mund, Baibhav Kumar; Gao, An; Sturm, Jacobus Marinus; Lee, Christopher James; Bijkerk, Frederik

    2015-01-01

    Highly transparent membranes are required for a number of applications, such as protective coatings for components in Extreme Ultraviolet (EUV) lithography, beam splitters (EUV pump-probe experiments), transmission gratings, and reticles. Graphene is an excellent candidate due to its high tensile

  2. Determination of Levan from Bacillus licheniformis by Ultraviolet ...

    African Journals Online (AJOL)

    the furfural intermediates [1]. Derivative ultraviolet-visible absorption spectrophotometry. (DS) method has been widely used to enhance the signal and decrease the interference of impurities with closely adjacent peaks in complex mixtures for determining drugs, food and other compounds [7]. DS, however, found few.

  3. A Rayleigh-Brillouin scattering spectrometer for ultraviolet wavelengths

    NARCIS (Netherlands)

    Gu, Z.Y.; Vieitez, M.O.; van Duijn, E.J.; Ubachs, W.M.G.

    2012-01-01

    A spectrometer for the measurement of spontaneous Rayleigh-Brillouin (RB) scattering line profiles at ultraviolet wavelengths from gas phase molecules has been developed, employing a high-power frequency-stabilized UV-laser with narrow bandwidth (2 MHz). The UV-light from a frequency-doubled

  4. Deep-ultraviolet quantum interference metrology with ultrashort laser pulses

    NARCIS (Netherlands)

    Witte, S.; Zinkstok, R.T.; Ubachs, W.M.G.; Hogervorst, W.; Eikema, K.S.E.

    2005-01-01

    Precision spectroscopy at ultraviolet and shorter wavelengths has been hindered by the poor access of narrow-band lasers to that spectral region. We demonstrate high-accuracy quantum interference metrology on atomic transitions with the use of an amplified train of phase-controlled pulses from a

  5. Frequency comb laser spectroscopy in the vacuum-ultraviolet region

    NARCIS (Netherlands)

    Zinkstok, R.T.; Witte, S.; Ubachs, W.M.G.; Hogervorst, W.; Eikema, K.S.E.

    2006-01-01

    We demonstrate that the output of a frequency comb laser can be amplified and upconverted to the vacuum ultraviolet (vuv) in a gaseous medium while its phase coherence is maintained to a high degree (< 1 30 of a vuv cycle). The produced vuv pulses are well suited to perform frequency comb

  6. Ultraviolet Spectroscopic Observations of Coronal Streamers in the ...

    Indian Academy of Sciences (India)

    Measurements made with the Ultraviolet Coronagraph Spectrometer (UVCS) on the Solar and Heliospheric Observatory can be used to determine physical parameters in the solar corona such as hydrogen and ion kinetic temperatures, electron densities, and absolute elemental abundances. Hydrogen and ion outflow ...

  7. Effect of ultraviolet-B radiation on biochemical and antioxidant ...

    African Journals Online (AJOL)

    The stratospheric ozone depletion and enhanced solar ultraviolet-B (UV-B) irradiance may have adverse impact on living organisms. The impact of UV-B radiation (UV-B, 280~320nm) on growth, biochemical and antioxidant enzyme activity was studied in Indigofera tinctoria (L.) seedling, commonly used as a green manure.

  8. Distinguishability of Biological Material Using Ultraviolet Multi-Spectral Fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Gray, P.C.; Heinen, R.J.; Rigdon, L.D.; Rosenthal, S.E.; Shokair, I.R.; Siragusa, G.R.; Tisone, G.C.; Wagner, J.S.

    1998-10-14

    Recent interest in the detection and analysis of biological samples by spectroscopic methods has led to questions concerning the degree of distinguishability and biological variability of the ultraviolet (W) fluorescent spectra from such complex samples. We show that the degree of distinguishability of such spectra is readily determined numerically.

  9. Ultraviolet irradiation initiates ectopic foot formation in regenerating ...

    Indian Academy of Sciences (India)

    Unknown

    [Ghaskadbi S S, Shetye L, Chiplonkar S and Ghaskadbi S 2005 Ultraviolet irradiation initiates ectopic foot formation in regenerating hydra and promotes budding; J. Biosci. 30 177–182]. 1. Introduction. Hydra, a member of the phylum Cnidaria, has an oral- aboral body axis and exhibits a remarkable ability to re- generate.

  10. Vacuum ultraviolet photoabsorption spectroscopy of crystalline and amorphous benzene

    DEFF Research Database (Denmark)

    Dawes, Anita; Pascual, Natalia; Hoffmann, Soren V.

    2017-01-01

    We present the first high resolution vacuum ultraviolet photoabsorption study of amorphous benzene with com parisons to annealed crystalline benzene and the gas phase. Vapour deposited benzene layers w ere grow n at 25 K and annealed to 90 K under conditions pertinent to interstellaricy dust grains...

  11. Highly efficient deep ultraviolet generation by sum-frequency mixing ...

    Indian Academy of Sciences (India)

    Generation of deep ultraviolet radiation at 210 nm by Type-I third harmonic generation is achieved in a pair of BBO crystals with conversion efficiency as high as 36%. The fundamental source is the dye laser radiation pumped by the second harmonic of a Q-switched Nd : YAG laser. A walk-off compensated configuration ...

  12. Carbonyl Sulfide Isotopologues: Ultraviolet Absorption Cross Sections and Stratospheric Photolysis

    DEFF Research Database (Denmark)

    Danielache, Sebastian Oscar; Nanbu, Shinkoh; Eskebjerg, Carsten

    2009-01-01

    Ultraviolet absorption cross sections of the main and substituted carbonyl sulfide isotopologues were calculated using wavepacket dynamics. The calculated absorption cross section of 16O12C32S is in very good agreement with the accepted experimental spectrum between 190 and 250 nm. Relative to 16O...

  13. Protective effect of (-)-epigallocatechin gallate on ultraviolet b ...

    African Journals Online (AJOL)

    Purpose: To investigate the protective effect of green tea (-)-epigallocatechin gallate (EGCg) on ultraviolet B (UV-B)-induced skin damages in hairless mice in order to develop a natural sunscreen compound for use in skin care products and cosmetics. Methods: EGCg was dissolved in acetone at concentrations of 1.0, 10.0 ...

  14. A comparison of ultraviolet radiometers' long-term performance ...

    African Journals Online (AJOL)

    In this paper we present a comparison of the performance characteristics of two types of broad-band ultraviolet radiometers. The first type of instrument is manufactured by Eppley Laboratories of the USA and the second type is manufactured by Kipp and Zonen of Holland. The results presented in this paper are for a ...

  15. Protective role of Aspergillus fumigatus melanin against ultraviolet ...

    African Journals Online (AJOL)

    Melanin content increased in Aspergillus fumigatus mycelium exposed to ultraviolet for 10 min but gradually decreased after 60 min of UV exposure. So, it can be concluded that melanin protects fungus for survival until 60 min which was obvious after studying conidia and mycelia by transmission electron microscope (TEM).

  16. Wavelength separation from extreme ultraviolet mirrors using phaseshift reflection

    NARCIS (Netherlands)

    van den Boogaard, Toine; van den Boogaard, A.J.R.; van Goor, F.A.; Louis, Eric; Bijkerk, Frederik

    2012-01-01

    A generic design and fabrication scheme of Mo/Si multilayer-grating phaseshift reflector systems is reported. Close to optimized extreme ultraviolet (EUV, λ=13.5  nm ) reflectance values up to 64% are demonstrated, while the diffractive properties can be exploited in spectral filtering applications.

  17. Wavelength separation from extreme ultraviolet mirrors using phaseshift reflection

    NARCIS (Netherlands)

    van den Boogaard, A. J. R.; van Goor, F. A.; E. Louis,; F. Bijkerk,

    2012-01-01

    A generic design and fabrication scheme of Mo/Si multilayer-grating phaseshift reflector systems is reported. Close to optimized extreme ultraviolet (EUV, lambda = 13.5 nm) reflectance values up to 64% are demonstrated, while the diffractive properties can be exploited in spectral filtering

  18. Effects of x- and ultraviolet radiation on egg albumin solutions

    Energy Technology Data Exchange (ETDEWEB)

    Buturlakin, M.S.; Bolycheva, E.V.

    1978-01-01

    The changes in amino acid radicals of tyrosine and tryptophan under the influence of different forms of radiation with change in medium pH were investigated. Acid and neutral egg albumin solutions were exposed to x radiation and ultraviolet radiation and the absorbed doses were determined. The changes in solvent perturbation absorption spectra were discussed.

  19. Bragg reflectors with IR suppression for Extreme Ultraviolet Lithography

    NARCIS (Netherlands)

    Medvedev, Viacheslav; Yakshin, Andrey; van de Kruijs, Robbert Wilhelmus Elisabeth; Krivtsun, V.M.; Yakunin, A.M.; Koshelev, K.; Bijkerk, Frederik

    2012-01-01

    The most promi¬sing next generation lithography technology is extreme ultraviolet lithography (EUVL). To fulfill the demands of high productivity, EUVL requires high power EUV radiation sources, with a promising technology for such sources being based on the emission of dense plasmas produced by

  20. Graphene defect formation by extreme ultraviolet generated photoelectrons

    NARCIS (Netherlands)

    Gao, An; Lee, Christopher James; Bijkerk, Frederik

    2014-01-01

    We have studied the effect of photoelectrons on defect formation in graphene during extreme ultraviolet (EUV) irradiation. Assuming the major role of these low energy electrons, we have mimicked the process by using low energy primary electrons. Graphene is irradiated by an electron beam with energy

  1. Ultraviolet-light-induced processes in germanium-doped silica

    DEFF Research Database (Denmark)

    Kristensen, Martin

    2001-01-01

    A model is presented for the interaction of ultraviolet (UV) light with germanium-doped silica glass. It is assumed that germanium sites work as gates for transferring the excitation energy into the silica. In the material the excitation induces forbidden transitions to two different defect states...

  2. A Novel Derivatization Ultraviolet Spectrophotometric Method for the ...

    African Journals Online (AJOL)

    Purpose: To develop a novel ultraviolet (UV)–spectrophotometric method for the determination of dihydroartemisinin (DHA) in tablets using ... The method used for analysis was validated and a linear calibration curve constructed in the .... methanol and absorbance reading taken at 290 nm. The test was also carried out in ...

  3. Pollen and spores as a passive monitor of ultraviolet radiation

    NARCIS (Netherlands)

    Fraser, W.T.; Lomax, B.H.; Jardine, P.E.; Gosling, W.D.; Sephton, M.A.

    2014-01-01

    Sporopollenin is the primary component of the outer walls of pollen and spores. The chemical composition of sporopollenin is responsive to levels of ultraviolet (UV) radiation exposure, via a concomitant change in the concentration of phenolic compounds. This relationship offers the possibility of

  4. Solar photocatalytic generation of hydrogen under ultraviolet-visible ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 33; Issue 1. Solar photocatalytic generation of hydrogen under ultraviolet-visible light irradiation on (CdS/ZnS)/Ag2S + (RuO2/TiO2) photocatalysts. R Priya S Kanmani. Catalysis ... Keywords. Hydrogen; hydrogen sulfide; solar photocatalysis; composite; photocatalysts.

  5. Photoprotective Effect of Tea and its Extracts against Ultraviolet ...

    African Journals Online (AJOL)

    Ultraviolet (UV) exposure induces photodamage of skin. It is a matter of concern that the level of UV radiation reaching the earth surface is increasing as a result of depletion of the stratospheric ozone, and climate change. It is urgently necessary to develop strategies to protect the skin from UV-induced injuries. Tea extracts ...

  6. High-resolution extreme ultraviolet laser spectroscopy of H2 and D2 in the range from 91 to 98 nm

    NARCIS (Netherlands)

    Hinnen, P. C.; Hogervorst, W.; Stolte, S.; Ubachs, W.

    1994-01-01

    The present study shows that a coherent laser-based source in the region of the extreme ultraviolet offers great spectroscopic potential and is now applied in various spectroscopic investigations with a resolution and accuracy superior to the best classical spectrographs.

  7. INTEGRATED HUMAN AND ECOLOIGCAL RISK ASSESSMENT: A CASE STUDY OF ULTRAVIOLET RADIATION EFFECTS ON AMPHIBIANS, CORAL, HUMANS, AND OCEANIC PRIMARY PRODUCTIVITY

    Science.gov (United States)

    Ultraviolet radiation (UVR) is a naturally occurring stressor to most forms of life. The sole relevant source of this stressor is the sun. The Earth's stratospheric ozone layer reduces the amount of UVR that reaches the Earth's surface. The potential for continued depletion of th...

  8. Ultraviolet (UV) Disinfection for Drinking Water Systems

    Science.gov (United States)

    UV disinfection is an effective process for inactivating many microbial pathogens in water with potential to serve as stand-alone treatment or in combination with other disinfectants. USEPA provided guidance on the validation of UV reactors nearly a decade ago. Since then, lesson...

  9. Herbal Cosmeceuticals for Photoprotection from Ultraviolet B ...

    African Journals Online (AJOL)

    By quenching free radicals, antioxidants may aid photoprotection effect. This review focuses on photoprotection from UVB radiation and discusses potential herbal candidates with antioxidant properties that can serve as a strong barrier in cosmeceuticals to protect skin against harmful UVB rays. Keywords: Cosmeceutials ...

  10. Superhydrophobic Polyimide via Ultraviolet Photooxidation: The Evolution of Surface Morphology and Hydrophobicity under Different Ultraviolet Intensities

    Directory of Open Access Journals (Sweden)

    Hongyu Gu

    2015-01-01

    Full Text Available Ultraviolet (UV photooxidation has recently been developed to fabricate superhydrophobic polyimide (PI films in combination with fluoroalkylsilane modification. However, it remains unclear whether the surface morphology and hydrophobicity are sensitive to technical parameters such as UV intensity and radiation environment. Herein, we focus on the effects of UV intensity on PI surface structure and wettability to gain comprehensive understanding and more effective control of this technology. Scanning electron microscopy (SEM and atomic force microscopy (AFM results showed that UV intensity governed the evolutionary pattern of surface morphology: lower UV intensity (5 mW/cm2 facilitated in-plane expansion of dendritic protrusions while stronger UV (10 and 15 mW/cm2 encouraged localized growth of protrusions in a piling-up manner. Surface roughness and hydrophobicity maximized at the intensity of 10 mW/cm2, as a consequence of the slowed horizontal expansion and preferred vertical growth of the protrusions when UV intensity increased. Based on these results, the mechanism that surface micro/nanostructures developed in distinct ways when exposed to different UV intensities was proposed. Though superhydrophobicity (water contact angle larger than 150° can be achieved at UV intensity not less than 10 mW/cm2, higher intensity decreased the effectiveness. Therefore, the UV photooxidation under 10 mW/cm2 for 72 h is recommended to fabricate superhydrophobic PI films.

  11. Zinc Selenide-Based Schottky Barrier Detectors for Ultraviolet-A and Ultraviolet-B Detection

    Directory of Open Access Journals (Sweden)

    V. Naval

    2010-01-01

    Full Text Available Wide-bandgap semiconductors such as zinc selenide (ZnSe have become popular for ultraviolet (UV photodetectors due to their broad UV spectral response. Schottky barrier detectors made of ZnSe in particular have been shown to have both low dark current and high responsivity. This paper presents the results of electrical and optical characterization of UV sensors based on ZnSe/Ni Schottky diodes fabricated using single-crystal ZnSe substrate with integrated UV-A (320–400 nm and UV-B (280–320 nm filters. For comparison, characteristics characterization of an unfiltered detector is also included. The measured photoresponse showed good discrimination between the two spectral bands. The measured responsivities of the UV-A and UV-B detectors were 50 mA/W and 10 mA/W, respectively. A detector without a UV filter showed a maximum responsivity of about 110 mA/W at 375 nm wavelength. The speed of the unfiltered detector was found to be about 300 kHz primarily limited by the RC time constant determined largely by the detector area.

  12. Demethoxycurcumin in combination with ultraviolet radiation B induces apoptosis through the mitochondrial pathway and caspase activation in A431 and HaCaT cells.

    Science.gov (United States)

    Xin, Yong; Huang, Qian; Zhang, Pei; Guo, Wen Wen; Zhang, Long Zhen; Jiang, Guan

    2017-06-01

    Photodynamic therapy is widely used in the clinical treatment of tumors, especially skin cancers. It has been reported that the photosensitizer curcumin, in combination with ultraviolet radiation B, induces HaCaT cell apoptosis, and this effect may be due to the activation of caspase pathways. In this study, we examined the photodynamic effects of demethoxycurcumin, a more stable analogue of curcumin, to determine whether it could induce apoptosis in skin cancer cells. We investigated the effects of a combination of ultraviolet radiation B and demethoxycurcumin on apoptotic cell death in A431 and HaCaT cells and determined the molecular mechanism of action. Our results showed increased apoptosis with a combination of ultraviolet radiation B with demethoxycurcumin, as compared to ultraviolet radiation B or demethoxycurcumin alone. The combination of ultraviolet radiation B irradiation with demethoxycurcumin synergistically induced apoptotic cell death in A431 and HaCaT cells through activation of p53 and caspase pathways, as well as through upregulation of Bax and p-p65 expression and downregulation of Bcl-2, Mcl-1, and nuclear factor-κB expression. In addition, we found that reactive oxygen species significantly increased with treatment, and mitochondrial membrane potential depolarization was remarkably enhanced. In conclusion, our data indicate that demethoxycurcumin may be a promising photosensitizer for use in photodynamic therapy to induce apoptosis in skin cancer cells.

  13. Harm of ultraviolet rays and sun care cosmetics. Care of ultraviolet rays for comfortable life; Shigaisen no gai to sankea keshohin. Kaiteki raifu no tameno shigaisen kea

    Energy Technology Data Exchange (ETDEWEB)

    Kurosawa, Takafumi.; Matsumoto, Takashi. [Shiseido Corp. Tokyo (Japan)

    1999-06-01

    Ultraviolet rays are the electromagnetic waves from 10 to 400nm. Ultraviolet rays related to the practical life are UV B and UV A from 290 to 400nm. These ultraviolet rays caused various harms to human skin. In order to maintain healthy and beautiful skin, the protection of ultraviolet rays is one of important skin care. In this paper, concerning sunscreen that is a comfortable cosmetic to protect the skin from ultraviolet rays, technical points were explained from a viewpoint of improvement on transparency. A petal shape zinc oxide was the zinc oxide obtained from shape control of secondary particles to petal by controlling mixed alkali kinds and neutralization conditions in the wet method. By the application of this petal shape zinc oxide on a basic agent, a sunscreen was successfully developed that transparency could be improved to sustain the high protection effect of ultraviolet rays, whiteness after making up could not be found. (NEDO)

  14. Ultraviolet germicidal irradiation and its effects on elemental distributions in mouse embryonic fibroblast cells in x-ray fluorescence microanalysis.

    Directory of Open Access Journals (Sweden)

    Qiaoling Jin

    Full Text Available Rapidly-frozen hydrated (cryopreserved specimens combined with cryo-scanning x-ray fluorescence microscopy provide an ideal approach for investigating elemental distributions in biological cells and tissues. However, because cryopreservation does not deactivate potentially infectious agents associated with Risk Group 2 biological materials, one must be concerned with contamination of expensive and complicated cryogenic x-ray microscopes when working with such materials. We employed ultraviolet germicidal irradiation to decontaminate previously cryopreserved cells under liquid nitrogen, and then investigated its effects on elemental distributions under both frozen hydrated and freeze dried states with x-ray fluorescence microscopy. We show that the contents and distributions of most biologically important elements remain nearly unchanged when compared with non-ultraviolet-irradiated counterparts, even after multiple cycles of ultraviolet germicidal irradiation and cryogenic x-ray imaging. This provides a potential pathway for rendering Risk Group 2 biological materials safe for handling in multiuser cryogenic x-ray microscopes without affecting the fidelity of the results.

  15. Favorable ultraviolet photoelectric effects in TbMnO3/Nb-SrTiO3 heterostructures

    KAUST Repository

    Jin, Kexin

    2014-12-01

    The rectifying properties and ultraviolet photoelectric effects in TbMnO3/Nb-doped SrTiO3 heterostructures have been investigated. The ideality factors and the diffusion voltages obtained from the current-voltage curves nonlinearly decrease with increasing the temperature. It is observed that the maximum photovoltaic values of the heterostructure irradiated by the 365 nm (2.6 mW/mm2) and 248 nm (0.71 mJ/mm2) lights are about 0.121 V and 0.119 V at T=300 K, respectively. The relations between the relaxation of photovoltages after the irradiation and the power intensity are revealed. These results suggest the potential applications in the development of ultraviolet detectors using oxides-based heterostructures.

  16. End-to-End Assessment of a Large Aperture Segmented Ultraviolet Optical Infrared (UVOIR) Telescope Architecture

    Science.gov (United States)

    Feinberg, Lee; Rioux, Norman; Bolcar, Matthew; Liu, Alice; Guyon, Oliver; Stark, Chris; Arenberg, Jon

    2016-01-01

    Key challenges of a future large aperture, segmented Ultraviolet Optical Infrared (UVOIR) Telescope capable of performing a spectroscopic survey of hundreds of Exoplanets will be sufficient stability to achieve 10^-10 contrast measurements and sufficient throughput and sensitivity for high yield Exo-Earth spectroscopic detection. Our team has collectively assessed an optimized end to end architecture including a high throughput coronagraph capable of working with a segmented telescope, a cost-effective and heritage based stable segmented telescope, a control architecture that minimizes the amount of new technologies, and an Exo-Earth yield assessment to evaluate potential performance. These efforts are combined through integrated modeling, coronagraph evaluations, and Exo-Earth yield calculations to assess the potential performance of the selected architecture. In addition, we discusses the scalability of this architecture to larger apertures and the technological tall poles to enabling it.

  17. The effects of cerium doping on the size, morphology, and optical properties of α-hematite nanoparticles for ultraviolet filtration

    Energy Technology Data Exchange (ETDEWEB)

    Cardillo, Dean [Institute for Superconducting and Electronic Materials, AIIM Facility, University of Wollongong Innovation Campus, Squires Way, North Wollongong, NSW 2500 (Australia); Konstantinov, Konstantin, E-mail: konstan@uow.edu.au [Institute for Superconducting and Electronic Materials, AIIM Facility, University of Wollongong Innovation Campus, Squires Way, North Wollongong, NSW 2500 (Australia); Devers, Thierry [Centre de Recherche sur la Matière Divisée, Institut de Physique, site de Chartres, Université d’Orléans (France)

    2013-11-15

    Highlights: • Possible application of cerium-doped α-hematite as ultraviolet filter. • Nanoparticles obtained through co-precipitation technique using various cerium doping levels followed by annealing. • Comprehensive materials characterisation utilizing XRD, DSC/TGA, STEM, UV–vis spectroscopy. • Increasing cerium content reduces particle sizing and alters morphology. • Solubility of cerium in hematite seen between 5 and 10% doping, 10% cerium doping greatly enhances attenuation in ultraviolet region and increases optical bandgap. - Abstract: Metal oxide nanoparticles have potential use in energy storage, electrode materials, as catalysts and in the emerging field of nanomedicine. Being able to accurately tailor the desirable properties of these nanoceramic materials, such as particle size, morphology and optical bandgap (E{sub g}) is integral in the feasibility of their use. In this study we investigate the altering of both the structure and physical properties through the doping of hematite (α-Fe{sub 2}O{sub 3}) nanocrystals with cerium at a range of concentrations, synthesised using a one-pot co-precipitation method. This extremely simple synthesis followed by thermal treatment results in stable Fe{sub 2−x}Ce{sub x}O{sub y} nanoceramics resulting from the burning of any unreacted precursors and transformation of goethite-cerium doped nanoparticle intermediate. The inclusion of Ce into the crystal lattice of these α-Fe{sub 2}O{sub 3} nanoparticles causes a significantly large reduction in mean crystalline size and alteration in particle morphology with increasing cerium content. Finally we report an increase optical semiconductor bandgap, along with a substantial increase in the ultraviolet attenuation found for a 10% Ce-doping concentration which shows the potential application of cerium-doped hematite nanocrystals to be used as a pigmented ultraviolet filter for cosmetic products.

  18. Implementation of Deep Ultraviolet Raman Spectroscopy

    DEFF Research Database (Denmark)

    Liu, Chuan

    – is a DUV laser in which the line is achieved by a highly complex frequency quadrupling device. Such a laser is obtainable as a product from TOPTICA Photonics. With respect to the solid-state laser possibility, we devoted ourselves to distinguish between wavelength tuneable and un-tuneable lasers...... excitation because of fluorescence interferences. Raman spectra of Sudan I - without fluorescence interferences - could be achieved by use of the 244.0 nm excitation. The DUV Raman spectrometry could thus be a potential detection method for Sudan I, as an illegal food colorant. The fluorescence-free DUV...

  19. Effect of Ultraviolet Aging on Rheology and Chemistry of LDH-Modified Bitumen

    Directory of Open Access Journals (Sweden)

    Xing Liu

    2015-08-01

    Full Text Available Layered double hydroxides (LDHs are an ultravioletlight (UV-resistant material. In this study, two types of LDHs (Mg-Al-LDHs and Zn-Al-LDHs were applied to modify bitumen by melt-blending. The effect of ultraviolet aging on the rheology and chemistry of LDH-modified bitumen was studied by means of dynamic shear rheometer (DSR, thin-layer chromatography with flame ionization detection (TLC-FID, Fourier transform infrared spectroscopy (FTIR, and Ultraviolet-Visible (UV-Vis spectrophotometry to reveal the mechanisms of action for LDHs and bitumen. The results showed that within the UV spectra (220–400 nm, the reflectance of Zn-Al-LDHs was larger than that of Mg-Al-LDHs. These two LDHs have different influences on the performance of bitumen. Mg-Al-LDHs had a more obvious influence on the physical and dynamic rheological properties of bitumen than Zn-Al-LDHs. Zn-Al-LDHs improved the UV-aging resistance of bitumen more. The reason can be that the reflectance of the Zn-Al-LDHs to the UV light is larger than that of the Mg-Al-LDHs. The Zn-Al-LDH-modified bitumen had more potential to improve the UV-aging resistance during the service life of asphalt pavement.

  20. Fabrication and performances of microencapsulated paraffin composites with polymethylmethacrylate shell based on ultraviolet irradiation-initiated

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yi, E-mail: wangyi@lut.cn [State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050 (China); College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050 (China); Shi Huan [College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050 (China); Xia Tiandong [State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050 (China); Zhang Ting; Feng Huixia [College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050 (China)

    2012-07-16

    In order to identify the validity of fabricating microencapsulated phase change material by ultraviolet irradiation-initiated method, the paraffin wax/polymethyl methacrylate microcapsules were prepared. The structural characteristics and thermal properties of the microcapsules were also determined by various techniques. The results of differential scanning calorimetry analyses indicate that the melting and freezing temperatures and latent heats of the microcapsules are 55.8 Degree-Sign C, 50.1 Degree-Sign C and 106.9 J g{sup -1}, 112.3 J g{sup -1}, respectively. Morphology and chemical characteristic analysis indicate that the spherical microcapsules were formed with average diameter of 0.21 {mu}m and maximum microencapsulation ratio of 66 wt.% without leakage of core materials. The results of accelerated thermal cyclic test show that the microcapsules have good thermal reliability and chemical stability although they were subjected 3000 melting/freezing cycles. Based on all these results, it can be concluded that the microencapsulated paraffin composites have good potential for thermal energy storage purposes and ultraviolet irradiation-initiated method is a prominent candidate for preparing microencapsulated PCMs. - Highlights: Black-Right-Pointing-Pointer Microencapsulated paraffin with PMMA shell was synthesized via self-assembly. Black-Right-Pointing-Pointer Microcapsules with excellent properties can be prepared by UV initiated method. Black-Right-Pointing-Pointer The microencapsulation ratio is as high as 66 wt.%. Black-Right-Pointing-Pointer Thermal properties are as high as comparable with microcapsules in the literature.

  1. Evaluation of a pulsed xenon ultraviolet disinfection system to decrease bacterial contamination in operating rooms.

    Science.gov (United States)

    El Haddad, Lynn; Ghantoji, Shashank S; Stibich, Mark; Fleming, Jason B; Segal, Cindy; Ware, Kathy M; Chemaly, Roy F

    2017-10-10

    Environmental cleanliness is one of the contributing factors for surgical site infections in the operating rooms (ORs). To decrease environmental contamination, pulsed xenon ultraviolet (PX-UV), an easy and safe no-touch disinfection system, is employed in several hospital environments. The positive effect of this technology on environmental decontamination has been observed in patient rooms and ORs during the end-of-day cleaning but so far, no study explored its feasibility between surgical cases in the OR. In this study, 5 high-touch surfaces in 30 ORs were sampled after manual cleaning and after PX-UV intervention mimicking between-case cleaning to avoid the disruption of the ORs' normal flow. The efficacy of a 1-min, 2-min, and 8-min cycle were tested by measuring the surfaces' contaminants by quantitative cultures using Tryptic Soy Agar contact plates. We showed that combining standard between-case manual cleaning of surfaces with a 2-min cycle of disinfection using a portable xenon pulsed ultraviolet light germicidal device eliminated at least 70% more bacterial load after manual cleaning. This study showed the proof of efficacy of a 2-min cycle of PX-UV in ORs in eliminating bacterial contaminants. This method will allow a short time for room turnover and a potential reduction of pathogen transmission to patients and possibly surgical site infections.

  2. A Convenient Ultraviolet Irradiation Technique for Synthesis of Antibacterial Ag-Pal Nanocomposite

    Science.gov (United States)

    Han, Shuai; Zhang, He; Kang, Lianwei; Li, Xiaoliang; Zhang, Chong; Dong, Yongjie; Qin, Shenjun

    2016-09-01

    In the present work, palygorskite (Pal) was initially subjected to an ion-exchange reaction with silver ions (Pal-Ag+). Subsequently, Ag-Pal nanocomposites were assembled by a convenient ultraviolet irradiation technique, using carbon dots (CDs) derived from wool fiber as the reducing agent. The obtained nanocomposites were characterized by powder X-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy. The XRD patterns and UV-vis absorption spectra confirmed the formation of the Ag nanoparticles (NPs). Meanwhile, the TEM images showed that the Ag NPs, which exhibited sizes in the range of 3-7 nm, were located on the surface of the Pal nanofiber structures. Furthermore, the antibacterial activity of the nanocomposites was evaluated against Gram-positive ( Staphylococcus aureus) and Gram-negative ( Escherichia coli) bacteria by applying the disc diffusion method and minimum inhibitory concentration test. Owing to their good antibacterial properties, the Ag-Pal nanocomposites are considered to be a promising bactericide with great potential applications.

  3. Egg colour matching in an African cuckoo, as revealed by ultraviolet-visible reflectance spectrophotometry.

    Science.gov (United States)

    Cherry, M I; Bennett, A T

    2001-01-01

    Despite major differences between human and avian colour vision, previous studies of cuckoo egg mimicry have used human colour vision (or standards based thereon) to assess colour matching. Using ultraviolet-visible reflectance spectrophotometry (300-700 nm), we measured museum collections of eggs of the red-chested cuckoo and its hosts. The first three principal components explained more than 99% of the variance in spectra, and measures of cuckoo host egg similarity derived from these transformations were compared with measures of cuckoo host egg similarity estimated by human observers unaware of the hypotheses we were testing. Monte Carlo methods were used to simulate laying of cuckoo eggs at random in nests. Results showed that host and cuckoo eggs were very highly matched for an ultraviolet versus greenness component, which was not detected by humans. Furthermore, whereas cuckoo and host were dissimilar in achromatic brightness, humans did not detect this difference. Our study thus reveals aspects of cuckoo-host egg colour matching which have hitherto not been described. These results suggest subtleties and complexities in the evolution of host-cuckoo egg mimicry that were not previously suspected. Our results also have the potential to explain the longstanding paradox that some host species accept cuckoo eggs that are non-mimetic to the human eye. PMID:11297172

  4. Optical Response of Metakaolin after Ultraviolet and High Energy Electron Exposure

    Directory of Open Access Journals (Sweden)

    B. T. Cesul

    2014-01-01

    Full Text Available Metakaolin, which is part of a class of inorganic polymers called geopolymers, is being tested currently for its use as a lightweight mirror material in spacecraft applications. Metakaolin, as with most geopolymers, has the advantages of low initial coefficient of thermal expansion, easy preparation at room temperature and pressure, and high specific strength. Even though metakaolin has been known as a structural material for millennia, it has not been properly vetted for use as a material in spacecraft applications, especially with respect to exposure to its environments. This research highlights one particular aspect of response to the space environment; that is, how do the optical properties of metakaolin change after subjugation to bombardment by ultraviolet and high energy electron radiation? These two radiation sources are common in low earth orbit and a primary cause of degradation of organic polymers in space. Photospectroscopic analysis showed that ultraviolet in combination with high energy electrons causes changes in the metakaolin which need to be accounted for due to their potential impacts on the thermal management of a spacecraft and during application in composite mirror structures.

  5. Daily and annual variations of erythemal ultraviolet radiation in Southwestern Spain

    Directory of Open Access Journals (Sweden)

    A. Serrano

    2006-03-01

    Full Text Available The potential danger of ultraviolet (UV radiation and its increasing levels at the Earth's surface due to ozone depletion have demanded worldwide representative measurements of UV radiation. This study presents four and one-half years of original records of high temporal resolution ultraviolet erythemal radiation (UVER measured in Badajoz, Spain. Its principal aim is to statistically characterize the UVER magnitude and temporal variations, but also to address the interesting special cases of cloud-free and cloudy skies. In particular, the study reports reliable values of fundamental statistical indices, which can serve as relevant values for comparison with other studies and model results. Moreover, the daily and annual evolution of the main central moments of the distribution function are analyzed and interpreted in terms of the forcing and attenuation sources.

    The analysis focuses on two different temporal scales: hourly and daily values. Integrated hourly and daily data allow for the study of daily and annual variations of the fundamental statistical indices. All of them exhibit high symmetry with respect to solar noon and to certain dates near summer and winter solstices. The analysis shows the great influence of cloudiness in the distribution of UVER values. Thus, both daily and hourly UVER data present a slightly asymmetrical, left tailed, mesokurtic distribution for all months, except for summer, when the lack of clouds produces a leptokurtic distribution which is skewed to the left.

  6. High extraction efficiency ultraviolet light-emitting diode

    Science.gov (United States)

    Wierer, Jonathan; Montano, Ines; Allerman, Andrew A.

    2015-11-24

    Ultraviolet light-emitting diodes with tailored AlGaN quantum wells can achieve high extraction efficiency. For efficient bottom light extraction, parallel polarized light is preferred, because it propagates predominately perpendicular to the QW plane and into the typical and more efficient light escape cones. This is favored over perpendicular polarized light that propagates along the QW plane which requires multiple, lossy bounces before extraction. The thickness and carrier density of AlGaN QW layers have a strong influence on the valence subband structure, and the resulting optical polarization and light extraction of ultraviolet light-emitting diodes. At Al>0.3, thinner QW layers (<2.5 nm are preferred) result in light preferentially polarized parallel to the QW plane. Also, active regions consisting of six or more QWs, to reduce carrier density, and with thin barriers, to efficiently inject carriers in all the QWs, are preferred.

  7. High-power extreme ultraviolet source based on gas jets

    Energy Technology Data Exchange (ETDEWEB)

    Kubiak, G.D.; Bernardez, L.J.; Krenz, K.

    1998-03-01

    The authors report on the development of a high power laser plasma Extreme Ultraviolet (EUV) source for Extreme Ultraviolet Lithography. The source is based on the plasma emission of a recycled jet beam of large Xe clusters and produces no particulate debris. The source will be driven by a pulsed laser delivering 1,500 W of focused average power to the cluster jet target. To develop condensers and to optimize source performance, a low power laboratory cluster jet prototype has been used to study the spectroscopy, angular distributions, and EUV source images of the cluster jet plasma emission. In addition, methods to improve the reflectance lifetimes of nearby plasma facing condenser mirrors have been developed. The resulting source yields EUV conversion efficiencies up to 3.8% and mirror lifetimes of 10{sup 9} plasma pulses.

  8. Optics of the ultraviolet reflecting scales of a jumping spider

    Science.gov (United States)

    Land, Michael F; Horwood, Julia; Lim, Matthew L.M; Li, Daiqin

    2007-01-01

    The jumping spider Cosmophasis umbratica from Singapore is strongly sexually dimorphic. The males, but not the females, reflect ultraviolet as well as green–orange light. The scales responsible for this are composed of a chitin–air–chitin sandwich in which the chitin layers are three-quarters of a wavelength thick and the air gap a quarter wavelength (where λ=600 nm, the peak wavelength of the principal reflection maximum). It is shown that this configuration produces a second reflectance peak at approximately 385 nm, accounting for the observed reflection in the ultraviolet. Other scales have a similar thickness of chitin but lack the air gap and thus produce a dull purple reflection. This novel mechanism provides the spiders with two colour signals, both of which are important in mating displays. PMID:17456453

  9. Ultraviolet irradiation disrupts somatic pili structure and function

    Energy Technology Data Exchange (ETDEWEB)

    Silverblatt, F.J.

    1979-09-01

    Three piliated bacterial species were exposed to ultraviolet light and the effect of increasing duration of irradiation on the integrity of the somatic pili was quantitated by negative-stain electron microscopy. Heavily piliated Proteus mirabilis became devoid of pili after 20 min of irradiation, but Escherichia coli and Neisseria gonorrhoeae required 40 min for complete depiliation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that new, small molecular weight fragments appeared after irradiation of purified E. coli pili, suggesting that cleavage of the peptide chain rather than dissociation of pilin monomers accounted for the loss of pili structure. These observations indicate that the ultrastructural integrity and function of pili can be disrupted by ultraviolet light.

  10. Aerosol scattering of ultraviolet sunlight in the tropical maritime atmosphere

    Science.gov (United States)

    Ghazi, A.; Krueger, A. J.; Fraser, R. S.

    1973-01-01

    The effects of atmospheric aerosol scattering on the vertical profile of solar ultraviolet radiation are investigated. Measurements of diffuse and total ultraviolet radiation were made using a rocketborne optical sonde in the marine atmosphere of Antigua. During observations, the sun was at zenith. Vertical profiles of directly transmitted solar radiation were calculated by subtraction of the diffuse component from the total radiance. Using these values of direct downward solar UV-flux, the optical thickness of the atmosphere was derived as a function of altitude. Absorption by ozone was also considered. In the troposphere the values of observed optical thickness were in general equal to or lower than those expected theoretically from Rayleigh scattering alone. The measured radiation profiles were compared with those computed for a multiple scattering model atmosphere. Some computations regarding the interaction of UV-sunlight with maritime aerosols are presented.

  11. The ultraviolet extinction properties of the 30 Dor Nebula

    Science.gov (United States)

    De Marchi, Guido; Panagia, Nino

    2018-01-01

    Recent investigation of the extinction law in 30 Dor and the Tarantula Nebula, at optical and near infrared wavelengths, has revealed a ratio of total to selective extinction RV=AV/E(B-V) of about 4.5. This indicates a larger proportion of large grains than in the Galactic diffuse interstellar medium. Possible origins include coalescence of small grains, grain growth, selective destruction of small grains, and fresh injection of large grains. From a study of the ultraviolet extinction properties of three Wolf-Rayet stars in 30 Dor (R 139, R 140, R 145), observed with the International Ultraviolet Explorer, we show that the excess of large grains does not come at the expense of small grains, which are still present. Fresh injection of large grains by supernova explosions appears to be the dominant mechanism.

  12. Ultraviolet laser deposition of graphene thin films without catalytic layers

    KAUST Repository

    Sarath Kumar, S. R.

    2013-01-09

    In this letter, the formation of nanostructured graphene by ultraviolet laser ablation of a highly ordered pyrolytic graphite target under optimized conditions is demonstrated, without a catalytic layer, and a model for the growth process is proposed. Previously, graphene film deposition by low-energy laser (2.3 eV) was explained by photo-thermal models, which implied that graphene films cannot be deposited by laser energies higher than the C-C bond energy in highly ordered pyrolytic graphite (3.7 eV). Here, we show that nanostructured graphene films can in fact be deposited using ultraviolet laser (5 eV) directly over different substrates, without a catalytic layer. The formation of graphene is explained by bond-breaking assisted by photoelectronic excitation leading to formation of carbon clusters at the target and annealing out of defects at the substrate.

  13. Use of germicidal ultraviolet radiations in air conditionning systems

    Energy Technology Data Exchange (ETDEWEB)

    Hillebrecht, J.; Kohler, N.

    1989-02-01

    Hygienical risks appear in air conditionning plants in humid parts, at the interface between clean and unclean zones and in heat recovery systems. Ultraviolet radiations with a wavelength of 254 etam disactivate germs in a purely physical way. They can be successfully used in air conditionning systems: in air ducts, over doors and in transition spaces, in humidifiers and cooling towers and as direct irradiation in clean rooms. The efficiency can be proven by calculations or experimentally.

  14. Magnetic fluorescent lamp having reduced ultraviolet self-absorption

    Science.gov (United States)

    Berman, Samuel M.; Richardson, Robert W.

    1985-01-01

    The radiant emission of a mercury-argon discharge in a fluorescent lamp assembly (10) is enhanced by providing means (30) for establishing a magnetic field with lines of force along the path of electron flow through the bulb (12) of the lamp assembly, to provide Zeeman splitting of the ultraviolet spectral line. Optimum results are obtained when the magnetic field strength causes a Zeeman splitting of approximately 1.7 times the thermal line width.

  15. Amplitudes and Ultraviolet Behavior of N=8 Supergravity

    CERN Document Server

    Bern, Zvi; Dixon, Lance; Johansson, Henrik; Roiban, Radu

    2011-01-01

    In this contribution we describe computational tools that permit the evaluation of multi-loop scattering amplitudes in N=8 supergravity, in terms of amplitudes in N=4 super-Yang-Mills theory. We also discuss the remarkable ultraviolet behavior of N=8 supergravity, which follows from these amplitudes, and is as good as that of N=4 super-Yang-Mills theory through at least four loops.

  16. Ultraviolet absorption spectrum of hydrogen peroxide vapor. [for atmospheric abundances

    Science.gov (United States)

    Molina, L. T.; Schinke, S. D.; Molina, M. J.

    1977-01-01

    The ultraviolet absorption cross sections of hydrogen peroxide vapor have been determined over the wavelength range 210 to 350 nm at 296 K. At the longer wavelengths, the gas phase absorptivities are significantly larger than the corresponding values in condensed phase. The atmospheric H2O2 photodissociation rate for overhead sun at the earth's surface is estimated to be about 1.3 x 10 to the -5th/sec.

  17. Environmentally stable/self-powered ultraviolet photodetectors with high sensitivity

    Science.gov (United States)

    Yang, Shengxue; Tongay, Sefaattin; Li, Shu-Shen; Xia, Jian-Bai; Wu, Junqiao; Li, Jingbo

    2013-09-01

    Here, we demonstrate self-powered ultraviolet photodetectors that are capable of generating opposite current flow when illuminated at different wavelengths. The photodetectors are composed of n-ZnO/Polyaniline (PANI) p-n and PANI/ZnGa2O4 type-II heterojunctions and operate without any need for external power source. Devices display superior stability in ambient conditions within months. Results provide opportunities for developing devices for optical recognition.

  18. Immunization of mice with Trypanosoma rhodesiense exposed to ultraviolet irradiation.

    Science.gov (United States)

    Charoenvit, Y; Campbell, G H

    1981-11-01

    Exposure time of Trypanosoma rhodesiense as short as 1 minute to ultraviolet (U.V.) light prevents the organisms from causing infection. Live trypanosome challenge of mice immunized with U.V.-irradiated trypanosomes results in sterile immunity. This allows a method for the induction of protective immunity to experimental trypanosomiasis which can be performed in most laboratories using U.V. germicidal lamps found in sterile hoods.

  19. Thin film solar cell inflatable ultraviolet rigidizable deployment hinge

    Science.gov (United States)

    Simburger, Edward J. (Inventor); Matsumoto, James H. (Inventor); Giants, Thomas W. (Inventor); Garcia, III, Alec (Inventor); Perry, Alan R. (Inventor); Rawal, Suraj (Inventor); Marshall, Craig H. (Inventor); Lin, John K. H. (Inventor); Day, Jonathan Robert (Inventor); Kerslake, Thomas W. (Inventor)

    2010-01-01

    A flexible inflatable hinge includes curable resin for rigidly positioning panels of solar cells about the hinge in which wrap around contacts and flex circuits are disposed for routing power from the solar cells to the power bus further used for grounding the hinge. An indium tin oxide and magnesium fluoride coating is used to prevent static discharge while being transparent to ultraviolet light that cures the embedded resin after deployment for rigidizing the inflatable hinge.

  20. Amplitudes and Ultraviolet Behavior of N = 8 Supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Bern, Zvi; /UCLA; Carrasco, John Joseph; /Stanford U., Phys. Dept.; Dixon, Lance J.; /SLAC /CERN; Johansson, Henrik; /Saclay, SPhT; Roiban, Radu; /Penn State U.

    2011-05-20

    In this contribution we describe computational tools that permit the evaluation of multi-loop scattering amplitudes in N = 8 supergravity, in terms of amplitudes in N = 4 super-Yang-Mills theory. We also discuss the remarkable ultraviolet behavior of N = 8 supergravity, which follows from these amplitudes, and is as good as that of N = 4 super-Yang-Mills theory through at least four loops.

  1. The solar ultraviolet heating efficiency of the midlatitude thermosphere

    Science.gov (United States)

    Torr, M. R.; Torr, D. G.; Richards, P. G.

    1980-01-01

    In this paper we quantify the major channels by which solar UV energy is transferred to the atmosphere, and determine the UV heating efficiency for the thermosphere. Current knowledge of the solar ultraviolet fluxes, thermospheric chemistry and neutral atmosphere is used in a steady state, interhemispheric solution of the ionospheric continuity, momentum and energy equations. The heating efficiency is found to be a strong function of altitude, and peaks near the altitude of maximum EUV deposition at a value of approximately 50%.

  2. Visible and ultraviolet light sources based nonlinear interaction of lasers

    DEFF Research Database (Denmark)

    Andersen, Martin Thalbitzer; Tidemand-Lichtenberg, Peter; Jain, Mayank

    Different light sources can be used for optically stimulated luminescence measurements and usually a halogen lamp in combination with filters or light emitting diodes (LED’s) are used to provide the desired stimulation wavelength. However lasers can provide a much more well-defined beam, very...... for synthesizing any wavelength in the visible and ultraviolet light based sum frequency generation between two lasers is presented....

  3. Madecassoside Inhibits Melanin Synthesis by Blocking Ultraviolet-Induced Inflammation

    OpenAIRE

    Eunsun Jung; Jung-A Lee; Seoungwoo Shin; Kyung-Baeg Roh; Jang-Hyun Kim; Deokhoon Park

    2013-01-01

    Madecassoside (MA), a pentacyclic triterpene isolated from Centella asitica (L.), is used as a therapeutic agent in wound healing and also as an anti-inflammatory and anti-aging agent. However, the involvement of MA in skin-pigmentation has not been reported. This study was conducted to investigate the effects of MA on ultraviolet (UV)-induced melanogenesis and mechanisms in a co-culture system of keratinocytes and melanocytes. MA significantly inhibited UVR-induced melanin synthesis and mel...

  4. Ultra-violet Behavior of Bosonic Quantum Membranes

    OpenAIRE

    Kaku, Michio

    1999-01-01

    We treat the action for a bosonic membrane as a sigma model, and then compute quantum corrections by integrating out higher membrane modes. As in string theory, where the equations of motion of Einstein's theory emerges by setting $\\beta = 0$, we find that, with certain assumptions, we can recover the equations of motion for the background fields. Although the membrane theory is non-renormalizable on the world volume by power counting, the investigation of the ultra-violet behavior of membran...

  5. Null bactericidal effect of ultraviolet radiation emitted by LEDs.

    Directory of Open Access Journals (Sweden)

    Francisco Alcántara Muñoz

    2016-11-01

    Full Text Available This research has aimed to assess the bactericidal effect of ultraviolet light emitted by LEDS on the growth on Petri dishes of microorganisms whose legal limits in foods have been established. An electrically fed apparatus has been designed with precise timing and a camera to prevent light spillage, in which two ultraviolet radiation emission devices were connected by LED technology at different wavelengths: through an array of LEDS emitting at around 350nm, and a single specific emission LED at 280nm. 1000 cfu of E. Coli and S. aureus sown on PCA were used as prototypes of gram negative and positive bacteria, respectively, onto which ultraviolet light was radiated at different time intervals, by means of both devices, with the whole experiment being carried out in triplicate . In none of the three series of treatments at the two wavelengths were reductions in microbial growth observed. The series of sowings on PCA were done on unseeded plates in order to be able to discard the likelihood of subsequent recontamination.

  6. Global modeling of thermospheric airglow in the far ultraviolet

    Science.gov (United States)

    Solomon, Stanley C.

    2017-07-01

    The Global Airglow (GLOW) model has been updated and extended to calculate thermospheric emissions in the far ultraviolet, including sources from daytime photoelectron-driven processes, nighttime recombination radiation, and auroral excitation. It can be run using inputs from empirical models of the neutral atmosphere and ionosphere or from numerical general circulation models of the coupled ionosphere-thermosphere system. It uses a solar flux module, photoelectron generation routine, and the Nagy-Banks two-stream electron transport algorithm to simultaneously handle energetic electron distributions from photon and auroral electron sources. It contains an ion-neutral chemistry module that calculates excited and ionized species densities and the resulting airglow volume emission rates. This paper describes the inputs, algorithms, and code structure of the model and demonstrates example outputs for daytime and auroral cases. Simulations of far ultraviolet emissions by the atomic oxygen doublet at 135.6 nm and the molecular nitrogen Lyman-Birge-Hopfield bands, as viewed from geostationary orbit, are shown, and model calculations are compared to limb-scan observations by the Global Ultraviolet Imager on the TIMED satellite. The GLOW model code is provided to the community through an open-source academic research license.

  7. Extreme-Ultraviolet Vortices from a Free-Electron Laser

    Directory of Open Access Journals (Sweden)

    Primož Rebernik Ribič

    2017-08-01

    Full Text Available Extreme-ultraviolet vortices may be exploited to steer the magnetic properties of nanoparticles, increase the resolution in microscopy, and gain insight into local symmetry and chirality of a material; they might even be used to increase the bandwidth in long-distance space communications. However, in contrast to the generation of vortex beams in the infrared and visible spectral regions, production of intense, extreme-ultraviolet and x-ray optical vortices still remains a challenge. Here, we present an in-situ and an ex-situ technique for generating intense, femtosecond, coherent optical vortices at a free-electron laser in the extreme ultraviolet. The first method takes advantage of nonlinear harmonic generation in a helical undulator, producing vortex beams at the second harmonic without the need for additional optical elements, while the latter one relies on the use of a spiral zone plate to generate a focused, micron-size optical vortex with a peak intensity approaching 10^{14}  W/cm^{2}, paving the way to nonlinear optical experiments with vortex beams at short wavelengths.

  8. Ultraviolet Observations of Phoebe from the Cassini UVIS

    Science.gov (United States)

    Hendrix, Amanda R.; Hansen, Candice J.

    2007-01-01

    Observations of Saturn's distant moon Phoebe were made at far-ultraviolet (FUV) (1100-1900 A) and extreme-ultraviolet (EUV) (600-1100 A) wavelengths by the Cassini Ultraviolet Imaging Spectrograph (UVIS) during the Cassini spacecraft flyby on June 11, 2004. These are the first UV spectra of Phoebe and the first detection of water ice on a Solar System surface using FUV wavelengths. The characteristics of water ice in the FUV are presented, and Hapke models are used to interpret the spectra in terms of composition and grain size; the use of both areal and intimate mixing models is explored. Non-ice species used in these models include carbon, ice tholin, Triton tholin, poly-HCN and kerogen. Satisfactory disk-integrated fits are obtained for intimate mixtures of approx.10% H2O plus a non-ice species. Spatially resolved regions of higher (approx.20%) and lower (approx.5%) H2O ice concentrations are also detected. Phoebe does not display any evidence of volatile activity. Upper limits on atomic oxygen and carbon are 5 x 10(exp 11) and 2 x 10(exp 12) atoms/sq. cm, respectively, for solar photon scattering. The UVIS detection of water ice on Phoebe, and the ice amounts detected, are consistent with IR measurements and contribute to the evidence for a Phoebe origin in the outer Solar System rather than in the main asteroid belt.

  9. The Space Weather and Ultraviolet Solar Variability (SWUSV) Microsatellite Mission.

    Science.gov (United States)

    Damé, Luc

    2013-05-01

    We present the ambitions of the SWUSV (Space Weather and Ultraviolet Solar Variability) Microsatellite Mission that encompasses three major scientific objectives: (1) Space Weather including the prediction and detection of major eruptions and coronal mass ejections (Lyman-Alpha and Herzberg continuum imaging); (2) solar forcing on the climate through radiation and their interactions with the local stratosphere (UV spectral irradiance from 180 to 400 nm by bands of 20 nm, plus Lyman-Alpha and the CN bandhead); (3) simultaneous radiative budget of the Earth, UV to IR, with an accuracy better than 1% in differential. The paper briefly outlines the mission and describes the five proposed instruments of the model payload: SUAVE (Solar Ultraviolet Advanced Variability Experiment), an optimized telescope for FUV (Lyman-Alpha) and MUV (200-220 nm Herzberg continuum) imaging (sources of variability); UPR (Ultraviolet Passband Radiometers), with 64 UV filter radiometers; a vector magnetometer; thermal plasma measurements and Langmuir probes; and a total and spectral solar irradiance and Earth radiative budget ensemble (SERB, Solar irradiance & Earth Radiative Budget). SWUSV is proposed as a small mission to CNES and to ESA for a possible flight as early as 2017-2018.

  10. Extreme-Ultraviolet Vortices from a Free-Electron Laser

    Science.gov (United States)

    Rebernik Ribič, Primož; Rösner, Benedikt; Gauthier, David; Allaria, Enrico; Döring, Florian; Foglia, Laura; Giannessi, Luca; Mahne, Nicola; Manfredda, Michele; Masciovecchio, Claudio; Mincigrucci, Riccardo; Mirian, Najmeh; Principi, Emiliano; Roussel, Eléonore; Simoncig, Alberto; Spampinati, Simone; David, Christian; De Ninno, Giovanni

    2017-07-01

    Extreme-ultraviolet vortices may be exploited to steer the magnetic properties of nanoparticles, increase the resolution in microscopy, and gain insight into local symmetry and chirality of a material; they might even be used to increase the bandwidth in long-distance space communications. However, in contrast to the generation of vortex beams in the infrared and visible spectral regions, production of intense, extreme-ultraviolet and x-ray optical vortices still remains a challenge. Here, we present an in-situ and an ex-situ technique for generating intense, femtosecond, coherent optical vortices at a free-electron laser in the extreme ultraviolet. The first method takes advantage of nonlinear harmonic generation in a helical undulator, producing vortex beams at the second harmonic without the need for additional optical elements, while the latter one relies on the use of a spiral zone plate to generate a focused, micron-size optical vortex with a peak intensity approaching 1014 W /cm2 , paving the way to nonlinear optical experiments with vortex beams at short wavelengths.

  11. Tiny Ultraviolet Polarimeter for Earth Stratosphere from Space Investigation

    Science.gov (United States)

    Nevodovskyi, P. V.; Morozhenko, O. V.; Vidmachenko, A. P.; Ivakhiv, O.; Geraimchuk, M.; Zbrutskyi, O.

    2015-09-01

    One of the reasons for climate change (i.e., stratospheric ozone concentrations) is connected with the variations in optical thickness of aerosols in the upper sphere of the atmosphere (at altitudes over 30 km). Therefore, aerosol and gas components of the atmosphere are crucial in the study of the ultraviolet (UV) radiation passing upon the Earth. Moreover, a scrupulous study of aerosol components of the Earth atmosphere at an altitude of 30 km (i.e., stratospheric aerosol), such as the size of particles, the real part of refractive index, optical thickness and its horizontal structure, concentration of ozone or the upper border of the stratospheric ozone layer is an important task in the research of the Earth climate change. At present, the Main Astronomical Observatory of the National Academy of Sciences (NAS) of Ukraine, the National Technical University of Ukraine "KPI"and the Lviv Polytechnic National University are engaged in the development of methodologies for the study of stratospheric aerosol by means of ultraviolet polarimeter using a microsatellite. So fare, there has been created a sample of a tiny ultraviolet polarimeter (UVP) which is considered to be a basic model for carrying out space experiments regarding the impact of the changes in stratospheric aerosols on both global and local climate.

  12. UIT: Ultraviolet observations of the small Magellanic cloud

    Science.gov (United States)

    Cornett, Robert H.; Hill, J. K.; Bohlin, Ralph C.; O'Connell, Robert W.; Roberts, Morton S.; Smith, Andrew M.; Strecher, Theodore P.

    1994-01-01

    Ultraviolet Imaging Telescope (UIT) far-ultraviolet (FUV) and near-ultraviolet (NUV) images are presented for a 40' field at the southwest end of the SMC centered near the H alpha emission object Henize 19. Photometry is obtained for 1309 stars common to the FUV (lambda (sub eff) = 1620 A) and NUV (lambda (sub eff) = 2490 A) images. We use UIT photometry and imagery to derive a UV color-magnitude diagram for hot field stars; confirm the consistency of low-metal-abundance stellar evolutionary models with the observations; study dust distribution in the field, finding an increase in E(B--V) from the northeast to the southwest; confirm for a large number of stars an extinction curve, like that derived by Hutchings for the SMC, which rises steeply from NUV to FUV; and derive a mass function for SMC field stars and its lack of dependence on assumed extinction curve characteristics. The mass function has a slope within the accepted range (Gamma = -1.7 +/- 0.5) over a wide range of assumed extinction parameters, including variations of the size (+/- approximately 1.5 mag x E(B--V) in the FUV) seen in the Galaxy.

  13. The Space Weather and Ultraviolet Solar Variability (SWUSV Microsatellite Mission

    Directory of Open Access Journals (Sweden)

    Luc Damé

    2013-05-01

    Full Text Available We present the ambitions of the SWUSV (Space Weather and Ultraviolet Solar Variability Microsatellite Mission that encompasses three major scientific objectives: (1 Space Weather including the prediction and detection of major eruptions and coronal mass ejections (Lyman-Alpha and Herzberg continuum imaging; (2 solar forcing on the climate through radiation and their interactions with the local stratosphere (UV spectral irradiance from 180 to 400 nm by bands of 20 nm, plus Lyman-Alpha and the CN bandhead; (3 simultaneous radiative budget of the Earth, UV to IR, with an accuracy better than 1% in differential. The paper briefly outlines the mission and describes the five proposed instruments of the model payload: SUAVE (Solar Ultraviolet Advanced Variability Experiment, an optimized telescope for FUV (Lyman-Alpha and MUV (200–220 nm Herzberg continuum imaging (sources of variability; UPR (Ultraviolet Passband Radiometers, with 64 UV filter radiometers; a vector magnetometer; thermal plasma measurements and Langmuir probes; and a total and spectral solar irradiance and Earth radiative budget ensemble (SERB, Solar irradiance & Earth Radiative Budget. SWUSV is proposed as a small mission to CNES and to ESA for a possible flight as early as 2017–2018.

  14. How does solar ultraviolet-B radiation improve drought tolerance of silver birch (Betula pendula Roth.) seedlings?

    Science.gov (United States)

    Robson, T Matthew; Hartikainen, Saara M; Aphalo, Pedro J

    2015-05-01

    We hypothesized that solar ultraviolet (UV) radiation would protect silver birch seedlings from the detrimental effects of water stress through a coordinated suite of trait responses, including morphological acclimation, improved control of water loss through gas exchange and hydraulic sufficiency. To better understand how this synergetic interaction works, plants were grown in an experiment under nine treatment combinations attenuating ultraviolet-A and ultraviolet-B (UVB) from solar radiation together with differential watering to create water-deficit conditions. In seedlings under water deficit, UV attenuation reduced height growth, leaf production and leaf length compared with seedlings receiving the full spectrum of solar radiation, whereas the growth and morphology of well-watered seedlings was largely unaffected by UV attenuation. There was an interactive effect of the treatment combination on water relations, which was more apparent as a change in the water potential at which leaves wilted or plants died than through differences in gas exchange. This suggests that changes occur in the cell wall elastic modulus or accumulation of osmolites in cells under UVB. Overall, the strong negative effects of water deficit are partially ameliorated by solar UV radiation, whereas well-watered silver birch seedlings are slightly disadvantaged by the solar UV radiation they receive. © 2014 John Wiley & Sons Ltd.

  15. Amorphous InGaMgO Ultraviolet Photo-TFT with Ultrahigh Photosensitivity and Extremely Large Responsivity.

    Science.gov (United States)

    Zhang, Yiyu; Qian, Ling-Xuan; Wu, Zehan; Liu, Xingzhao

    2017-02-13

    Recently, amorphous InGaZnO ultraviolet photo thin-film transistors have exhibited great potential for application in future display technologies. Nevertheless, the transmittance of amorphous InGaZnO (~80%) is still not high enough, resulting in the relatively large sacrifice of aperture ratio for each sensor pixel. In this work, the ultraviolet photo thin-film transistor based on amorphous InGaMgO, which processes a larger bandgap and higher transmission compared to amorphous InGaZnO, was proposed and investigated. Furthermore, the effects of post-deposition annealing in oxygen on both the material and ultraviolet detection characteristics of amorphous InGaMgO were also comprehensively studied. It was found that oxygen post-deposition annealing can effectively reduce oxygen vacancies, leading to an optimized device performance, including lower dark current, higher sensitivity, and larger responsivity. We attributed it to the combined effect of the reduction in donor states and recombination centers, both of which are related to oxygen vacancies. As a result, the 240-min annealed device exhibited the lowest dark current of 1.7 × 10-10 A, the highest photosensitivity of 3.9 × 10⁶, and the largest responsivity of 1.5 × 10⁴ A/W. Therefore, our findings have revealed that amorphous InGaMgO photo thin-film transistors are a very promising alternative for UV detection, especially for application in touch-free interactive displays.

  16. Amorphous InGaMgO Ultraviolet Photo-TFT with Ultrahigh Photosensitivity and Extremely Large Responsivity

    Directory of Open Access Journals (Sweden)

    Yiyu Zhang

    2017-02-01

    Full Text Available Recently, amorphous InGaZnO ultraviolet photo thin-film transistors have exhibited great potential for application in future display technologies. Nevertheless, the transmittance of amorphous InGaZnO (~80% is still not high enough, resulting in the relatively large sacrifice of aperture ratio for each sensor pixel. In this work, the ultraviolet photo thin-film transistor based on amorphous InGaMgO, which processes a larger bandgap and higher transmission compared to amorphous InGaZnO, was proposed and investigated. Furthermore, the effects of post-deposition annealing in oxygen on both the material and ultraviolet detection characteristics of amorphous InGaMgO were also comprehensively studied. It was found that oxygen post-deposition annealing can effectively reduce oxygen vacancies, leading to an optimized device performance, including lower dark current, higher sensitivity, and larger responsivity. We attributed it to the combined effect of the reduction in donor states and recombination centers, both of which are related to oxygen vacancies. As a result, the 240-min annealed device exhibited the lowest dark current of 1.7 × 10−10 A, the highest photosensitivity of 3.9 × 106, and the largest responsivity of 1.5 × 104 A/W. Therefore, our findings have revealed that amorphous InGaMgO photo thin-film transistors are a very promising alternative for UV detection, especially for application in touch-free interactive displays.

  17. Inactivation of Pseudomonas aeruginosa biofilm after ultraviolet light-emitting diode treatment: a comparative study between ultraviolet C and ultraviolet B

    Science.gov (United States)

    Argyraki, Aikaterini; Markvart, Merete; Bjørndal, Lars; Bjarnsholt, Thomas; Petersen, Paul Michael

    2017-06-01

    The objective of this study was to test the inactivation efficiency of two different light-based treatments, namely ultraviolet B (UVB) and ultraviolet C (UVC) irradiation, on Pseudomonas aeruginosa biofilms at different growth stages (24, 48, and 72 h grown). In our experiments, a type of AlGaN light-emitting diodes (LEDs) was used to deliver UV irradiation on the biofilms. The effectiveness of the UVB at 296 nm and UVC at 266 nm irradiations was quantified by counting colony-forming units. The survival of less mature biofilms (24 h grown) was studied as a function of UV-radiant exposure. All treatments were performed on three different biological replicates to test reproducibility. It was shown that UVB irradiation was significantly more effective than UVC irradiation in inactivating P. aeruginosa biofilms. UVC irradiation induced insignificant inactivation on mature biofilms. The fact that the UVB at 296 nm exists in daylight and has such disinfection ability on biofilms provides perspectives for the treatment of infectious diseases.

  18. Optical properties and electronic transitions of zinc oxide, ferric oxide, cerium oxide, and samarium oxide in the ultraviolet and extreme ultraviolet

    DEFF Research Database (Denmark)

    Pauly, N; Yubero, F; Espinós, J P

    2017-01-01

    Optical properties and electronic transitions of four oxides, namely zinc oxide, ferric oxide, cerium oxide, and samarium oxide, are determined in the ultraviolet and extreme ultraviolet by reflection electron energy loss spectroscopy using primary electron energies in the range 0.3-2.0 keV. This...

  19. Ultraviolet Spectroscopy of Tidal Disruption Flares

    Science.gov (United States)

    Cenko, Stephen B.

    2017-08-01

    When a star passes within the sphere of disruption of a massive black hole, tidal forces will overcome self-gravity and unbind the star. While approximately half of the stellar debris is ejected at high velocities, the remaining material stays bound to the black hole and accretes, resulting in a luminous, long-lived transient known as a tidal disruption flare (TDF). In addition to serving as unique laboratories for accretion physics,TDFs offer the hope of measuring black hole masses in galaxies much too distant for resolved kinematic studies.In order to realize this potential, we must better understand the detailed processes by which the bound debris circularizes and forms an accretion disk. Spectroscopy is critical to this effort, as emission and absorption line diagnostics provide insight into the location and physical state (velocity, density, composition) of the emitting gas (in analogy with quasars). UV spectra are particularly critical, as most strong atomic features fall in this bandpass, and high-redshift TDF discoveries from LSST will sample rest-frame UV wavelengths.Here I present recent attempts to obtain UV spectra of tidal disruption flares. I describe the UV spectrum of ASASSN-14li, in which we detect three classes of features: narrow absorption from the Milky Way (probably a high-velocity cloud), and narrow absorption and broad (2000-8000 km s-1) emission lines at or near the systemic host velocity. The absorption lines are blueshifted with respect to the emission lines by 250-400 km s-1. Due both to this velocity offset and the lack of common low-ionization features (Mg II, Fe II), we argue these arise from the same absorbing material responsible for the low-velocity outflow discovered at X-ray wavelengths. The broad nuclear emission lines display a remarkable abundance pattern: N III], N IV], and He II are quite prominent, while the common quasar emission lines of C III] and Mg II are weak or entirely absent. Detailed modeling of this spectrum will

  20. Ultraviolet laser-induced lateral photovoltaic response in anisotropic black shale

    Science.gov (United States)

    Miao, Xinyang; Zhu, Jing; Zhao, Kun; Yue, Wenzheng

    2017-12-01

    The anisotropy of shale has significant impact on oil and gas exploration and engineering. In this paper, a-248 nm ultraviolet laser was employed to assess the anisotropic lateral photovoltaic (LPV) response of shale. Anisotropic angle-depending voltage signals were observed with different peak amplitudes ( V p) and decay times. We employed exponential models to explain the charge carrier transport in horizontal and vertical directions. Dependences of the laser-induced LPV on the laser spot position were observed. Owing to the Dember effect and the layered structure of shale, V p shows an approximately linear dependence with the laser-irradiated position for the 0° shale sample but nonlinearity for the 45° and 90° ones. The results demonstrate that the laser-induced voltage method is very sensitive to the structure of materials, and thus has a great potential in oil and gas reservoir characterization.

  1. Ultraviolet light induced white light emission in Ag and Eu3+ co-doped oxyfluoride glasses.

    Science.gov (United States)

    Guo, Hai; Wang, Xiaofeng; Chen, Jindeng; Li, Fang

    2010-08-30

    Transparent Ag and Eu(3+) co-doped oxyfluoride glasses with composition 50SiO(2)-20Al(2)O(3)-30CaF(2) were prepared by melt-quenching technique. The structural and luminescent properties of glasses, energy transfer mechanism between luminescent centers were systematically investigated. The missing nanoparticles signals in absorption spectra, XRD patterns and TEM images, the additional broad excitation band at 325-375 nm indicate that the broad emission band at 400-700 nm is originated from very small molecule-like, non-plasmonic Ag particles (ML-Ag-particles). A perfect white light emission was realized by combining intense red emission of Eu(3+) with broad band emission of ML-Ag-particles. These results suggest that Ag and Eu(3+) co-doped oxyfluoride glasses could be potentially applied as white light-emitting phosphors for ultra-violet LED chips.

  2. Allergic contact dermatitis due to urethane acrylate in ultraviolet cured inks.

    Science.gov (United States)

    Nethercott, J R; Jakubovic, H R; Pilger, C; Smith, J W

    1983-08-01

    Seven workers exposed to ultraviolet printing inks developed contact dermatitis. Six cases were allergic and one irritant. A urethane acrylate resin accounted for five cases of sensitisation, one of which was also sensitive to pentaerythritol triacrylate and another also to an epoxy acrylate resin. One instance of allergy to trimethylpropane triacrylate accounted for the sixth case of contact dermatitis in this group of workers. An irritant reaction is presumed to account for the dermatitis in the individual not proved to have cutaneous allergy by patch tests. In this instance trimethylpropane triacrylate was thought to be the most likely irritating agent. Laboratory investigation proved urethane acrylate to be an allergen. The results of investigations of the sensitisation potentials of urethane acrylate, methylmethacrylate, epoxy acrylate resins, toluene-2,4-diisocyanate, and other multifunctional acrylic monomers in the albino guinea pig are presented. The interpretation of such predictive tests is discussed.

  3. Tunable orbital angular momentum beams in the extreme ultraviolet/soft x-ray regimes

    Science.gov (United States)

    Turpin, Alex; Rego, Laura; San Román, Julio; Picón, Antonio; Plaja, Luis; Hernández-García, Carlos

    2017-05-01

    High-order harmonic generation (HHG) has been recently proven to produce harmonic vortices carrying orbital angular momentum (OAM) in the extreme-ultraviolet (XUV) region from the nonlinear up-conversion of infrared vortex beams. In this work we present two methods to control and extend the OAM content of the harmonic vortices. First, we show that when a driver combination of different vortex modes is used, HHG leads to the production of harmonic vortices with a broad OAM content due to its nonperturbative nature. Second, we show that harmonic vortices with two discrete OAM contributions -so called fractional OAM modes- are generated when HHG is driven by conical refraction beams. Our work offers the possibility of generating tunable OAM beams in the XUV regime, potentially extensible to the soft x rays, overcoming the state of the art limitations for the generation of OAM beams far from the visible domain.

  4. Determination of Nicotine in Smoke Condensate by Ion Chromatography Coupled to Ultraviolet Detection

    Directory of Open Access Journals (Sweden)

    Geiss O

    2014-12-01

    Full Text Available A new method for the determination of the nicotine content of tobacco smoke condensate is described. The smoke condensate of the mainstream smoke was collected in a glass fibre filter trap and dissolved in isopropanol. The nicotine content of an aliquot of this solution was determined by ion chromatography (IC coupled with ultraviolet (UV detection against external calibration and the nicotine content of the whole smoke condensate was calculated. The nicotine content determined in each run by IC was compared with the results obtained by gas chromatography (GC according to the International Standard (ISO method 10315. The present method represents a potential alternative to the GC method. A sensitive and rapid method for the determination of nicotine in smoke condensate using IC with a standard ion chromatography column was developed.

  5. Disinfection of Pseudomonas aeruginosa biofilm contaminated tube lumens with ultraviolet C light emitting diodes

    DEFF Research Database (Denmark)

    Bak, Jimmy; Ladefoged, S.D.; Tvede, M.

    2010-01-01

    , however, be applied to obtain 99.9% disinfection rates. The major reason was that besides cells the mature biofilm contained absorbing and scattering particulates, which made the biofilm opaque. The potential of UVC light emitting diodes ( LED) for disinfection purposes in catheter-like tubes contaminated...... with biofilm was investigated. It was shown that UVC light propagation was possible through both Teflon and catheter tubes ( silicone). The disinfection efficiency of the diodes was demonstrated on tubes contaminated artificially with a Pseudomonas aeruginosa biofilm. The tubes were connected to a flow system......Bacterial biofilms on long-term catheters are a major source of infection. Exposure to ultraviolet C (UVC - 265 nm) light was shown in an earlier study to reduce the number of bacteria substantially on ex vivo treated urinary patient catheters. Very large doses ( long treatment times) should...

  6. Disinfection of Pseudomonas aeruginosa biofilm contaminated tube lumens with ultraviolet C light emitting diodes

    DEFF Research Database (Denmark)

    Bak, Jimmy; Ladefoged, Søren D; Tvede, Michael

    2010-01-01

    , however, be applied to obtain 99.9% disinfection rates. The major reason was that besides cells the mature biofilm contained absorbing and scattering particulates, which made the biofilm opaque. The potential of UVC light emitting diodes (LED) for disinfection purposes in catheter-like tubes contaminated...... with biofilm was investigated. It was shown that UVC light propagation was possible through both Teflon and catheter tubes (silicone). The disinfection efficiency of the diodes was demonstrated on tubes contaminated artificially with a Pseudomonas aeruginosa biofilm. The tubes were connected to a flow system......Bacterial biofilms on long-term catheters are a major source of infection. Exposure to ultraviolet C (UVC - 265 nm) light was shown in an earlier study to reduce the number of bacteria substantially on ex vivo treated urinary patient catheters. Very large doses (long treatment times) should...

  7. Endocrine-disrupting effect of the ultraviolet filter benzophenone-3 in zebrafish, Danio rerio

    DEFF Research Database (Denmark)

    Kinnberg, Karin Lund; Petersen, Gitte I.; Albrektsen, Mette

    2015-01-01

    The chemical ultraviolet (UV) filter benzophenone-3 (BP-3) is suspected to be an endocrine disruptor based on results from in vitro and in vivo testing. However, studies including endpoints of endocrine adversity are lacking. The present study investigated the potential endocrine-disrupting effects...... not affect the vitellogenin concentration in TG 234. After 12 d exposure of adult male zebrafish, a slight but yet significant increase in the vitellogenin concentration was observed at 268 µg/L but not at 63 µg/L and 437 µg/l BP-3. Skewing of the sex ratio is a marker of an endocrine mediated mechanism...... as well as a marker of adversity and therefore the conclusion of the investigation is that BP-3 is an endocrine-disrupting chemical in accordance with the World Health Organization's definition....

  8. Two-dimensional vacuum ultraviolet images in different MHD events on the EAST tokamak

    Science.gov (United States)

    Zhijun, WANG; Xiang, GAO; Tingfeng, MING; Yumin, WANG; Fan, ZHOU; Feifei, LONG; Qing, ZHUANG; EAST Team

    2018-02-01

    A high-speed vacuum ultraviolet (VUV) imaging telescope system has been developed to measure the edge plasma emission (including the pedestal region) in the Experimental Advanced Superconducting Tokamak (EAST). The key optics of the high-speed VUV imaging system consists of three parts: an inverse Schwarzschild-type telescope, a micro-channel plate (MCP) and a visible imaging high-speed camera. The VUV imaging system has been operated routinely in the 2016 EAST experiment campaign. The dynamics of the two-dimensional (2D) images of magnetohydrodynamic (MHD) instabilities, such as edge localized modes (ELMs), tearing-like modes and disruptions, have been observed using this system. The related VUV images are presented in this paper, and it indicates the VUV imaging system is a potential tool which can be applied successfully in various plasma conditions.

  9. Effectiveness of automated ultraviolet-C light for decontamination of textiles inoculated with Enterococcus faecium.

    Science.gov (United States)

    Smolle, C; Huss, F; Lindblad, M; Reischies, F; Tano, E

    2018-01-01

    Healthcare textiles are increasingly recognized as potential vehicles for transmission of hospital-acquired infections. This study tested the ability of an automated ultraviolet-C (UV-C) room disinfection device (Tru-D Smart UV-C) to decontaminate textiles inoculated with Enterococcus faecium in a clinical setting. Contaminated polycotton (50/50 polyester/cotton) swatches were distributed to predefined locations in a ward room and exposed to UV-C light. UV-C decontamination reduced E. faecium counts by a mean log10 reduction factor of 1.37 (all P = 0.005, Wilcoxon signed rank test). UV-C decontamination may be a feasible adjunctive measure to conventional laundering to preserve the cleanliness of healthcare textiles in ward rooms. Copyright © 2017 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  10. Isorhamnetin Protects Human Keratinocytes against Ultraviolet B-Induced Cell Damage

    Science.gov (United States)

    Han, Xia; Piao, Mei Jing; Kim, Ki Cheon; Madduma Hewage, Susara Ruwan Kumara; Yoo, Eun Sook; Koh, Young Sang; Kang, Hee Kyoung; Shin, Jennifer H; Park, Yeunsoo; Yoo, Suk Jae; Chae, Sungwook; Hyun, Jin Won

    2015-01-01

    Isorhamnetin (3-methylquercetin) is a flavonoid derived from the fruits of certain medicinal plants. This study investigated the photoprotective properties of isorhamnetin against cell damage and apoptosis resulting from excessive ultraviolet (UV) B exposure in human HaCaT keratinocytes. Isorhamnetin eliminated UVB-induced intracellular reactive oxygen species (ROS) and attenuated the oxidative modification of DNA, lipids, and proteins in response to UVB radiation. Moreover, isorhamnetin repressed UVB-facilitated programmed cell death in the keratinocytes, as evidenced by a reduction in apoptotic body formation, and nuclear fragmentation. Additionally, isorhamnetin suppressed the ability of UVB light to trigger mitochondrial dysfunction. Taken together, these results indicate that isorhamnetin has the potential to protect human keratinocytes against UVB-induced cell damage and death. PMID:26157553

  11. IUE's treasure-chest of the ultraviolet Universe

    Science.gov (United States)

    1997-11-01

    IUE was the most long-lived and (by a wide margin) the most productive satellite so far, in the history of space astronomy. After going into orbit on 26 January 1978, as a NASA-ESA-UK project, IUE was meant to operate for three years. More than eighteen years later, IUE still worked 24 hours a day, harvesting new knowledge for astronomers. The last observations were made from ESA's ground station at Villafranca, Spain, on 26 September 1996, and IUE was switched off four days later. Since then, team members at Villafranca and at NASAs Goddard Space Flight Center have used modern data-processing and information technology to recycle 100,000 ultraviolet spectra of comets, planets, stars, galaxies and quasars, acquired by IUE during its 18.5 years of operations. As a result, the IUE Final Archive is already available on-line via the Internet to hundreds of users who have registered to work with the data. The last few items (about 2 per cent of the total) will be added before the end of November. Also to be presented at the Sevilla conference is ESA's system called INES ("IUE Newly Extracted Spectra") which offers access, selection and distribution of data products, in a thoroughly user-friendly fashion. The IUE Final Archive is the third massive compendium made available to the worlds astronomers by ESA in 1997. The Hipparcos and Tycho Catalogues, released earlier in the year, give the positions of stars with unprecedented accuracy, thanks to ESA's Hipparcos satellite. "Space astronomy has set the example in providing a high standard of data quality and making the data accessible to the scientific community through archives", says Roger Bonnet, ESA's Scientific Director. "Now, ground-based observatories are following suit. The data legacy of IUE will be distributed to he community so that research on IUE data can continue long after the end of IUE's lifetime in space". Wonders of ultraviolet spectroscopy IUE analysed ultraviolet light, in a wavelength range from 1150

  12. Permanent hydrophilic modification of polypropylene and poly(vinyl alcohol) films by vacuum ultraviolet radiation

    Energy Technology Data Exchange (ETDEWEB)

    Belmonte, Guilherme Kretzmann [Instituto de Química, Universidade Federal do Rio Grande do Sul (UFRGS), Avenida Bento Gonçalves 9500, 91501-970 Porto Alegre, RS (Brazil); Charles, German [Centro de Química Aplicada (CEQUIMAP), Facultad de Ciencias Químicas, Unversidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Edificio de Ciencias II, Ciudad Universitaria, Córdoba 5000 (Argentina); Strumia, Miriam Cristina [Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, IPQA-Conicet, Haya de la Torre y Medina Allende, Edificio de Ciencias II, Ciudad Universitaria, Córdoba 5000 (Argentina); Weibel, Daniel Eduardo, E-mail: danielw@iq.ufrgs.br [Instituto de Química, Universidade Federal do Rio Grande do Sul (UFRGS), Avenida Bento Gonçalves 9500, 91501-970 Porto Alegre, RS (Brazil)

    2016-09-30

    Highlights: • Polypropylene and Poly(vinyl alcohol) were surface modified by vacuum ultraviolet (VUV) irradiation. • The hydrophilicity of the treated films was permanent and resisted aging for several months. • Grafting of styrene monomer was only observed in the VUV irradiated regions. • The obtained results showed the potential in the use of VUV treatment for surface modification and processing of polymers which lack chromophores in the UV region. - Abstract: Polypropylene (PP) and Poly(vinyl alcohol) (PVA) both synthetics polymers but one of them biodegradable, were surface modified by vacuum ultraviolet (VUV) irradiation. After VUV irradiation in an inert nitrogen atmosphere, the films were exposed to oxygen gas. The treated films were characterized by water contact angle measurements (WCA), optical profilometry, FTIR-ATR, XPS, UPS and NEXAFS techniques. PP and PVA VUV-treated films reached superhydrophilic conditions (WCAs <10°) in about 30 min of irradiation under our experimental conditions. It was observed that when the WCAs reached about 35–40° the hydrophilicity was permanent in both polymers. These results contrasted with typical plasma treatments were a rapid hydrophobic recovery with aging time is usually observed. UPS and XPS data showed the presence of new functionalities on the PP and PVA surfaces that were assigned to COO, C=O, C−O and C=C functional groups. Finally, grafting of styrene (ST) as a typical monomer was tested on PP films. It was confirmed that only in the VUV irradiated region an efficient grafting of ST or polymerized ST was found. Outside the irradiated regions no ST grafted was observed. Our results showed the potential use of VUV treatment for surface modification and processing of polymers which lack chromophores in the UV region.

  13. Suppression of experimental autoimmune encephalomyelitis by ultraviolet light is not mediated by isomerization of urocanic acid.

    Science.gov (United States)

    Irving, Amy A; Marling, Steven J; Plum, Lori A; DeLuca, Hector F

    2017-01-05

    Ultraviolet B irradiation confers strong resistance against experimental autoimmune encephalomyelitis, a model of multiple sclerosis. This protection by ultraviolet B is independent of vitamin D production but causes isomerization of urocanic acid, a naturally occurring immunosuppressant. To determine whether UCA isomerization from trans to cis is responsible for the protection against experimental autoimmune encephalomyelitis afforded by ultraviolet B, trans- or cis-urocanic acid was administered to animals and their disease progression was monitored. Disease incidence was reduced by 74% in animals exposed to ultraviolet B, and skin cis-urocanic acid levels increased greater than 30%. However, increasing skin cis-urocanic acid levels independent of ultraviolet B was unable to alter disease onset or progression. It is unlikely that urocanic acid isomerization is responsible for the ultraviolet B-mediated suppression of experimental autoimmune encephalomyelitis. Additional work is needed to investigate alternative mechanisms by which UVB suppresses disease.

  14. [Study on ultraviolet-screening effect of extracts from mangosteen (Garcinia mangostana Linn.) pericarp].

    Science.gov (United States)

    Zhang, Chengzhong; Bu, Qitao; Zheng, Yi'nan; Song, Bo; Li, Wei

    2011-07-01

    To analyze the ultraviolet-screening of the n-butanol extracts of mangosteen pericarp and alpha-mangostin, compare the ultraviolet-screening effect of the extracts with rutin and ultramicro-titanium dioxide (TiO2). The samples (n-butanol extract from mangosteen pericarp, alpha-mangostin, rutin and TiO2) were scanned at different wavelength and Pan-wavelength by ultraviolet spectrophotometry. The n-butanol extracts and alpha-mangostin had relatively satisfactory effects on ultraviolet-screening when the concentration was over 0.40 mg/ml and the effects on ultraviolet-screening was better than TiO2. The n-butanol extracts and alpha-mangostin had a positive ultraviolet-screening activity which was better than TiO2.

  15. Ultraviolet 320 nm laser excitation for flow cytometry.

    Science.gov (United States)

    Telford, William; Stickland, Lynn; Koschorreck, Marco

    2017-04-01

    Although multiple lasers and high-dimensional analysis capability are now standard on advanced flow cytometers, ultraviolet (UV) lasers (usually 325-365 nm) remain an uncommon excitation source for cytometry. This is primarily due to their cost, and the small number of applications that require this wavelength. The development of the Brilliant Ultraviolet (BUV fluorochromes, however, has increased the importance of this formerly niche excitation wavelength. Historically, UV excitation was usually provided by water-cooled argon- and krypton-ion lasers. Modern flow cytometers primary rely on diode pumped solid state lasers emitting at 355 nm. While useful for all UV-excited applications, DPSS UV lasers are still large by modern solid state laser standards, and remain very expensive. Smaller and cheaper near UV laser diodes (NUVLDs) emitting at 375 nm make adequate substitutes for 355 nm sources in many situations, but do not work as well with very short wavelength probes like the fluorescent calcium chelator indo-1. In this study, we evaluate a newly available UV 320 nm laser for flow cytometry. While shorter in wavelength that conventional UV lasers, 320 is close to the 325 nm helium-cadmium wavelength used in the past on early benchtop cytometers. A UV 320 nm laser was found to excite almost all Brilliant Ultraviolet dyes to nearly the same level as 355 nm sources. Both 320 nm and 355 nm sources worked equally well for Hoechst and DyeCycle Violet side population analysis of stem cells in mouse hematopoetic tissue. The shorter wavelength UV source also showed excellent excitation of indo-1, a probe that is not compatible with NUVLD 375 nm sources. In summary, a 320 nm laser module made a suitable substitute for conventional 355 nm sources. This laser technology is available in a smaller form factor than current 355 nm units, making it useful for small cytometers with space constraints. © 2017 International Society for Advancement of Cytometry. © 2017 International

  16. An Ultraviolet Spectral Legacy of Polluted White Dwarfs

    Science.gov (United States)

    Farihi, Jay

    2016-10-01

    Polluted white dwarfs represent the best path to empirically measure the bulk chemical compositions and limiting masses of extrasolar planetesimals. A wealth of data now firmly link metal-enriched white dwarfs with circumstellar debris that derives from rocky planetary building blocks or fragments of larger parent bodies. Ultraviolet spectroscopy is the only way to detect critical elements such as carbon and oxygen, and the small handful of stars studied in this way have yielded spectacular results. Our recent HST successes demonstrate the power of this technique, and we wish to take the next logical step with a large survey. In the same way that planetary scientists utilize diverse meteorite classes to understand the formation and composition of the terrestrial planets, we need a statistical census of extrasolar planetesimal compositions to fully understand their physical and chemical role as exoplanet precursors. A large (N 40) dataset of detailed metal abundances in polluted white dwarfs is essential to our understanding of the assembly and chemistry of Earth-like exoplanets.We propose to observe a brightness-limited sample of metal-rich white dwarfs, by selecting 31 targets that can be observed in a single COS / STIS visit, and thereby making the most efficient use of HST time for any sample of this size. This will increase the number of polluted white dwarfs observed in the far ultraviolet by a factor of five, and thereby perform the most robust and statistically meaningful study that is currently possible. This is a legacy that HST should leave to future planet formation modelers and cosmochemists, and it requires the ultraviolet capacity of HST.

  17. Elastomeric Seal Performance after Terrestrial Ultraviolet Radiation Exposure

    Science.gov (United States)

    Daniels, Christopher C.; Oravec, Heather A.; Mather, Janice L.; Taylor, Shawn C.; Dunlap, Patrick H.

    2015-01-01

    Ultraviolet radiation was evaluated to determine its negative effects on the performance of elastomeric gas pressure seals. The leak rates of the silicone elastomer S0383-70 O-ring test articles were used to quantify the degradation of the seals after exposure to vacuum-ultraviolet and/or middle-to-near-ultraviolet wavelength radiation. Three groups of seals were exposed in terrestrial facilities to 115-165 nm wavelength radiation, 230-500 nm wavelength radiation, or both spectrums, for an orbital spaceflight equivalent of 125 hours. The leak rates of the silicone elastomer S0383-70 seals were quantified and compared to samples that received no radiation. Each lot contained six samples and statistical t-tests were used to determine the separate and combined influences of exposure to the two wavelength ranges. A comparison of the mean leak rates of samples exposed to 115-165 nm wavelength radiation to the control specimens showed no difference, suggesting that spectrum was not damaging. The 230-500 nm wavelength appeared to be damaging, as the mean leak rates of the specimens exposed to that range of wavelengths, and those exposed to the combined 115-165 nm and 230-500 nm spectrums, were significantly different from the leak rates of the control specimens. Most importantly, the test articles exposed to both wavelength spectrums exhibited mean leak rates two orders of magnitude larger than any other exposed specimens, which suggested that both wavelength spectrums are important when simulating the orbital environment.

  18. Ultraviolet modification of Chlamydomonas reinhardtii for carbon capture

    Directory of Open Access Journals (Sweden)

    Gopal NS

    2016-04-01

    Full Text Available Nikhil S Gopal,1 K Sudhakar2 1The Lawrenceville School, Lawrenceville, NJ, USA; 2Bioenergy Laboratory, Malauna Azad National Institute of Technology, Bhopal, India Purpose: Carbon dioxide (CO2 levels have been rising rapidly. Algae are single-cell organisms with highly efficient CO2 uptake mechanisms. Algae yield two to ten times more biomass versus terrestrial plants and can grow nearly anywhere. Large scale CO2 sequestration is not yet sustainable due to high amounts of nitrogen (N and phosphate (P needed to grow algae in media. Methods: Mutant strains of Chlamydomonas reinhardtii were created using ultraviolet light (2.2–3 K J/m2 and natural selection using media with 20%–80% lower N and P compared to standard Sueoka's high salt medium. Strains were selected based upon growth in media concentrations varying from 20% to 80% less N/P compared to control. Biomass was compared to wild-type control (CC-125 using direct counts, optical density dry weight, and mean doubling time. Results: Mean doubling time was 20 and 25 hours in the low N and N/P strains, respectively (vs 66 hours in control. Using direct counts, growth rates of mutant strains of low N and N/P cultures were not statistically different from control (P=0.37 and 0.70, respectively. Conclusion: Two new strains of algae, as well as wild-type control, were able to grow while using 20%–40% less N and P. Ultraviolet light-based modification of algae is an inexpensive and alternative option to genetic engineering techniques. This technique might make larger scale biosequestration possible. Keywords: biosequestration, ultraviolet, carbon sequestration, carbon capture, algae

  19. [Effect of long-wave ultraviolet light (UV-A) and medium-wave ultraviolet rays (UV-B) on human skin. Critical comparison].

    Science.gov (United States)

    Raab, W

    1980-04-15

    When discussing the effects of ultraviolet radiation on human skin, one should carefully distinguish between the long wave ultraviolet light (UV-A) and the short wave radiations (UV-B and UV-C). Ultraviolet A induces immediate pigmentation but, if high energies are applied, a permanent pigmentation is elicited. This type of ultraviolet A-induced pigmentation has been called "spontaneous" pigmentation as no erythematous reaction is necessary to induce or accelerate melanine formation. Ultraviolet B provokes erythema and consecutive pigmentation. Upon chronic exposure, ultraviolet B causes the wellknown actinic damage of the skin and even provokes carcinoma. With exposures to the sunlight (global radiation), one should be most careful. The public must be informed extensively about the dangers of excessive sunbaths. The use of artificial "suns" with spectra between 260 and 400 nm is limited as it may cause the same type of damage as the global radiation. An exact schedule for use of artificial lamps is strongly recommended. After one cycle of exposures, an interruption is necessary until the next cycle of irradiations may start. Upon continual use for tanning of the skin, artificial lamps may provoke irreversible damage of the skin. Radiation sources with emission spectra of wavelengths between 315 and 400 nm exclusively are well suited for the induction of skin pigmentation (cosmetic use). Potent radiation such as UVASUN systems provoke a "pleasant" permanent pigmentation after exposures for less than one hour. The use of ultraviolet A (UV-A) does not carry any risk for the human skin.

  20. Photochemical Cyclopolymerization of Polyimides in Ultraviolet Ridgidizing Composites for Use in Inflatable Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This innovation uses photochemical cyclopolymerization of polyimides to manufacture ultraviolet rigidizable composites for use in RIS (ridgidizing inflatable)...

  1. A vision physiological estimation of ultraviolet window marking visibility to birds

    Directory of Open Access Journals (Sweden)

    Olle Håstad

    2014-10-01

    Full Text Available Billions of birds are estimated to be killed in window collisions every year, worldwide. A popular solution to this problem may lie in marking the glass with ultraviolet reflective or absorbing patterns, which the birds, but not humans, would see. Elegant as this remedy may seem at first glance, few of its proponents have taken into consideration how stark the contrasts between ultraviolet and human visible light reflections or transmissions must be to be visible to a bird under natural conditions. Complicating matters is that diurnal birds differ strongly in how their photoreceptors absorb ultraviolet and to a lesser degree blue light. We have used a physiological model of avian colour vision to estimate the chromatic contrasts of ultraviolet markings against a natural scene reflected and transmitted by ordinary window glass. Ultraviolets markings may be clearly visible under a range of lighting conditions, but only to birds with a UVS type of ultraviolet vision, such as many passerines. To bird species with the common VS type of vision, ultraviolet markings should only be visible if they produce almost perfect ultraviolet contrasts and are viewed against a scene with low chromatic variation but high ultraviolet content.

  2. Improved photoresponse performance of a self-powered Si/ZnO heterojunction ultraviolet and visible photodetector by the piezo-phototronic effect

    Science.gov (United States)

    Yin, Bing; Qiu, Yu; Zhang, Heqiu; Luo, Yingmin; Zhao, Yu; Yang, Dechao; Hu, Lizhong

    2017-06-01

    In this work, we report the fabrication of self-powered Si/ZnO heterojunction ultraviolet and visible photodetectors (PDs) with different doping concentrations. The PDs have a fast response time (shorter than 0.13 s) to the ultraviolet and visible illumination at 0 V bias. The photocurrent of Sample A (high doping concentration) is more than 20 times larger than Sample B (low doping concentration) under 365 nm illumination and more than 150 times larger than Sample B under 450 nm illumination. The larger photoresponse is attributed to the stronger built-in electric field of Si/ZnO heterojunction. Furthermore, we demonstrate the impact of the piezo-phototronic effect for the self-powered Si/ZnO heterojunction ultraviolet and visible photodetector. Under a 0.7N compressive strain, the maximal UV and visible photocurrents are enhanced by about 33.7% and 13.9% for sample A (high doping concentration), about 67.3% and 74.5% for sample B (low doping concentration), respectively. The possible working principle is that the positive piezoelectric charges at the Si/ZnO interface lower the local energy band level of ZnO, thus strengthening the built-in electric field and shift the depletion region to the Si side leading to an increase in the photon-absorption volume. This work may provide a potential approach to enhance the performance of the self-powered Si/ZnO heterojunction ultraviolet and visible photodetector.

  3. Large area, surface discharge pumped, vacuum ultraviolet light source

    Science.gov (United States)

    Sze, Robert C.; Quigley, Gerard P.

    1996-01-01

    Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source. A contamination-free VUV light source having a 225 cm.sup.2 emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm.sup.2 at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing.

  4. Characteristics of extreme ultraviolet emission from high-Z plasmas

    Science.gov (United States)

    Ohashi, H.; Higashiguchi, T.; Suzuki, Y.; Kawasaki, M.; Suzuki, C.; Tomita, K.; Nishikino, M.; Fujioka, S.; Endo, A.; Li, B.; Otsuka, T.; Dunne, P.; O'Sullivan, G.

    2016-03-01

    We demonstrate the extreme ultraviolet (EUV) and soft x-ray sources in the 2 to 7 nm spectral region related to the beyond EUV (BEUV) question at 6.x nm and the water window source based on laser-produced high-Z plasmas. Resonance emission from multiply charged ions merges to produce intense unresolved transition arrays (UTAs), extending below the carbon K edge (4.37 nm). An outline of a microscope design for single-shot live cell imaging is proposed based on high-Z plasma UTA source, coupled to multilayer mirror optics.

  5. Ultraviolet Radiation-induced Alteration of Martian Surface Materials

    Science.gov (United States)

    Yen, A. S.

    1999-01-01

    The nature and origin of martian surface materials cannot be fully characterized without addressing the unusual reactivity of the soil and the effects of exposure to the unique martian environment. Our laboratory experiments show that ultraviolet radiation at the martian surface can result in the oxidation of metal atoms and the creation of reactive oxygen species on grain surfaces. This process is important in understanding the nature and evolution of martian soils. It can explain the reactivity discovered by the Viking Landers and possibly the origin of the ferric component of the soil.

  6. Cockayne syndrome: a cellular sensitivity to ultraviolet light.

    Science.gov (United States)

    Schmickel, R D; Chu, E H; Trosko, J E; Chang, C C

    1977-08-01

    Two unrelated children, a boy 2 1/2 years old and a girl 4 years old, were affected with the cachectic dwarfism of Cockayne syndrome. Fibroblast cultures derived from these patients exhibited increased sensitivity to ultraviolet (UV) light, but not to x-irradiation, as measured by colony-forming ability. In both Cockayne fibroblast cultures, the rate of removal of thymidine dimer from the irradiated cellular DNA was normal. This demonstration of a cellular defect in Cockayne cells suggests that there may be an enzymatic defect in the repair of UV light-induced damage.

  7. Portable Deep-Ultraviolet (DUV) Raman for Standoff Detection.

    Science.gov (United States)

    Hopkins, Adam J; Cooper, Justin L; Profeta, Luisa T M; Ford, Alan R

    2016-05-01

    Alakai Defense Systems has recently developed a man-portable ultraviolet Raman spectrometer system. The portable Raman improvised explosives detector was designed to provide rapid, standoff detection of chemicals of interest to the end user, including, but not limited to explosives, narcotics, toxic industrial chemicals, and toxic industrial materials. In this paper, we discuss general aspects of the system design and user interface. Spectral and instrument performance data are shown for several common materials involved in narcotics manufacture, as well as cocaine and heroin, with comparisons to currently marketed handheld Raman instruments. © The Author(s) 2016.

  8. Angle-insensitive and solar-blind ultraviolet bandpass filter.

    Science.gov (United States)

    Kim, Sangsik; Man, Mengren; Qi, Minghao; Webb, Kevin J

    2014-10-01

    We present a metal-dielectric stack ultraviolet (UV) bandpass filter that rejects the longer wavelength, visible spectrum and is thin and relatively insensitive to the angle of incidence. Parametric evaluations of the reflection phase shift at the metal-dielectric interface provide insight and design information. This nontrivial phase shift allows coupled Fabry-Perot resonances with subwavelength dielectric film thickness. Furthermore, the total phase shift, with contributions from wave propagation and nontrivial reflection phase shift, is insensitive to the angle of incidence. Filter passbands in the UV can be shifted to visible or longer wavelengths by engineering the dielectric thickness and selecting a metal with an appropriate plasma frequency.

  9. Extreme Ultraviolet Stokesmeter for Pulsed Magneto-Optics

    Directory of Open Access Journals (Sweden)

    Mabel Ruiz-Lopez

    2015-02-01

    Full Text Available Several applications in material science and magnetic holography using extreme ultraviolet (EUV radiation require the measurement of the degree and state of polarization. In this work, an instrument to measure simultaneously both parameters from EUV pulses is presented. The instrument determines the Stokes parameters after a reflection on an array of multilayer mirrors at the Brewster angle. The Stokesmeter was tested at Swiss Light Source at different EUV wavelengths. The experimental Stokes patterns of the source were compared with the simulated pattern.

  10. Oxidation of graphene in ozone under ultraviolet light

    KAUST Repository

    Cheng, Yingchun

    2012-08-17

    Based on first-principles calculations, the process of grapheneoxidation in ozone under ultraviolet light is explored by studying the effects of O(3P) on the structural and electronic properties of a graphene sheet. On initial absorption of O(3P), an epoxy group is formed on the graphene sheet and the Dirac cone is shifted away from the Brillouin zone corners without carrier doping. When the oxidation progresses, an adjacent C-C bond is broken, a vacancy is formed, and CO and/or CO2 molecules are released.

  11. Calibration of windowless photodiode for extreme ultraviolet pulse energy measurement.

    Science.gov (United States)

    Kolacek, Karel; Schmidt, Jiri; Straus, Jaroslav; Frolov, Oleksandr

    2015-12-10

    For energy measurement of extreme ultraviolet pulses, no universal commercially available device is available. Therefore, a co-axial setup of a vacuum photodiode was developed and tested. First its unsuccessful calibration at the National Institute of Standards and Technology (USA) is mentioned. Then our own single-wavelength (46.9 nm) calibration procedure is described in detail. It is based on tabulated photoemission efficiency and on measured (1) anode collection efficiency, (2) attenuation of Al filters, and (3) attenuation of measuring cables. Some other relevant attenuating factors are also taken into account.

  12. THE DENATURATION OF EGG ALBUMIN BY ULTRA-VIOLET RADIATION

    Science.gov (United States)

    Clark, Janet Howell

    1935-01-01

    The coagulation of isoelectric egg albumin solutions, on exposure to ultraviolet radiation, involves three distinct processes, (1) the light denaturation of the albumin molecule, (2) a reaction between the light denatured molecule and water which may be similar to heat denaturation but occurs at a lower temperature, and (3), the flocculation of the denatured molecules to form a coagulum. The light denaturation is unimolecular, independent of temperature, and occurs over a wide pH range. The reaction between the light denatured molecule and water has a temperature coefficient of 10+ and occurs rapidly at 40°C., a temperature at which heat denaturation is inappreciable. PMID:19872919

  13. Vacuum ultraviolet electronic properties of liquids. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Painter, L.R.

    1980-06-01

    A program to study the electronic structure of liquids over the energy range from 2 to 25 eV was carried out from November, 1968 to October 1980. These studies basically consisted of measuring the reflectance, transmittance, photoionization, and photoemission of liquids in the vacuum ultraviolet spectral region as a function of angle of incidence and photon energy. Such measurements are analyzed to yield the optical and dielectric functions of the liquid as functions of photon energy. A summary of the progress in the program is presented. (GHT)

  14. CIV Polarization Measurements Using a Vacuum Ultraviolet Fabry Perot

    Science.gov (United States)

    West, Edward A.

    2009-01-01

    Marshall Space Flight Center's (MSFC) is developing a Vacuum Ultraviolet (VUV) Fabry Perot that will be launched on a sounding rocket for high throughput, high-cadence, extended field of view CIV (155nm) measurements. These measurements will provide (i) Dopplergrams for studies of waves, oscillations, explosive events, and mass motions through the transition region, and, (ii), polarization measurements to study the magnetic field in the transition region. This paper will describe the scientific goals of the instrument, a brief description of the optics and the polarization characteristics of the VUV Fabry Perot.

  15. Plasmonic tunable metamaterial absorber as ultraviolet protection film

    Science.gov (United States)

    Hedayati, M. K.; Zillohu, A. U.; Strunskus, T.; Faupel, F.; Elbahri, M.

    2014-01-01

    Plasmonic metamaterials designed for optical frequency have to be shrunk down to few 10th of nanometer which turns their manufacturing cumbersome. Here, we shift the performance of metamaterial down to ultraviolet (UV) by using ultrathin nanocomposite as a tunable plasmonic metamaterial fabricated with tandem co-deposition. It provides the possibility to realize a plasmonic metamaterial absorber for UV frequency with marginal angle sensitivity. Its resonance frequency and intensity can be adjusted by changing thickness and filling factor of the composite. Presented approach for tunable metamaterials for high frequency could pave the way for their application for thermo-photovoltaic, stealth technology, and UV-protective coating.

  16. Effect of ultraviolet illumination on metal oxide resistive memory

    KAUST Repository

    Duran Retamal, Jose Ramon

    2014-12-22

    We investigate the photoelectrical and resistive switching properties of Pt/ZnO/Pt capacitor operated in unipolar mode under ultraviolet (UV) illumination. The oxygen photodesorption under UV illumination explains the photoconduction observed in initial and high resistance states. Meanwhile, oxygen readsorption at surface-related defects justifies the different photoresponses dynamics in both states. Finally, UV illumination significantly reduces the variations of resistance in high resistance state, set voltage and reset voltage by 58%, 33%, and 25%, respectively, stabilizing Pt/ZnO/Pt capacitor. Our findings in improved switching uniformity via UV light give physical insight into designing resistive memory devices.

  17. The Swift-UVOT ultraviolet and visible grism calibration

    OpenAIRE

    Kuin, N. P. M.; Landsman, W.; Breeveld, A. A.; Page, M. J.; James, C.; Lamoureux, H.; Mehdipour, M.; Still, M.; Yershov, V.; Brown, P.J.; Carter, M; Mason, K. O.; Kennedy, T.; Marshall, F.; Roming, P. W. A.

    2015-01-01

    We present the calibration of the Swift UVOT grisms, of which there are two, providing low-resolution field spectroscopy in the ultraviolet and optical bands respectively. The UV grism covers the range 1700-5000 Angstrom with a spectral resolution of 75 at 2600 Angstrom for source magnitudes of u=10-16 mag, while the visible grism covers the range 2850-6600 Angstrom with a spectral resolution of 100 at 4000 Angstrom for source magnitudes of b=12-17 mag. This calibration extends over all detec...

  18. Lack of ultraviolet mutagenesis in radiation-resistant bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Tempest, P.R.; Moseley, B.E.B. (Edinburgh Univ. (UK). Dept. of Microbiology)

    1982-01-01

    Ultraviolet (UV) radiation did not induce rifampicin-resistant mutants in populations of the taxonomically-related radiation-resistant bacteria Deinococcus radiodurans, D. radiopugnans, D. radiophilus and D. proteolyticus, although such mutants arose spontaneously at a low frequency and at a high frequency after treatment of cultures with N-nitroso compounds. The radiation-resistant bacteria Arthrobacter radiotolerans and P-30-A were also UV-mutable. We conclude that the radiation-resistant bacteria repair UV-induced DNA damage accurately and lack an error-prone pathway for the repair of such damage.

  19. Absolute photon-flux measurements in the vacuum ultraviolet

    Science.gov (United States)

    Samson, J. A. R.; Haddad, G. N.

    1974-01-01

    Absolute photon-flux measurements in the vacuum ultraviolet have extended to short wavelengths by use of rare-gas ionization chambers. The technique involves the measurement of the ion current as a function of the gas pressure in the ion chamber. The true value of the ion current, and hence the absolute photon flux, is obtained by extrapolating the ion current to zero gas pressure. Examples are given at 162 and 266 A. The short-wavelength limit is determined only by the sensitivity of the current-measuring apparatus and by present knowledge of the photoionization processes that occur in the rate gases.

  20. Ultraviolet light induced refractive index structures in germanosilica

    DEFF Research Database (Denmark)

    Svalgaard, Mikael

    1997-01-01

    The focus of the research presented in this ph.d. thesis is refractive index structures photoinduced in germanonsilica waveguides with ultra-violet (UV) radiation. The physical mechanisms involved in photosensitivity and applications of a wide range of UV induced refractive index structures in both...... application of a scanning near-field optical microscope to obtain high resolution images of UV induced refractive index structures and by monitoring the dynamics of UV induced index changes and luminescence. During part of my ph.d. project I have worked at the National Institute of Standards and Technolgy...

  1. Effects of ultraviolet light on Hymenolepis diminuta ova and cysticercoids

    Energy Technology Data Exchange (ETDEWEB)

    McGavock, W.D.; Howard, K.E.

    1980-07-01

    The ova and cysticercoids of Hymenolepis diminuta were exposed to a 2537 A wave length of ultraviolet light for various time periods. Development was extremely impaired in the cysts which had been irradiated for 30 and 60 minutes. When these were administered to the final host no tapeworms developed. From 113 intermediate host beetle larvae fed with irradiated ova, only three cysticercoids were recovered. Development was impaired in both cases and the infective rate of irradiated ova and cysts of the least exposed groups was lower than that of the controls.

  2. Recycling of laser and plasma radiation energy for enhancement of extreme ultraviolet sources for nanolithography

    Science.gov (United States)

    Sizyuk, V.; Sizyuk, T.; Hassanein, A.; Johnson, K.

    2018-01-01

    We have developed comprehensive integrated models for detailed simulation of laser-produced plasma (LPP) and laser/target interaction, with potential recycling of the escaping laser and out-of-band plasma radiation. Recycling, i.e., returning the escaping laser and plasma radiation to the extreme ultraviolet (EUV) generation region using retroreflective mirrors, has the potential of increasing the EUV conversion efficiency (CE) by up to 60% according to our simulations. This would result in significantly reduced power consumption and/or increased EUV output. Based on our recently developed models, our High Energy Interaction with General Heterogeneous Target Systems (HEIGHTS) computer simulation package was upgraded for LPP devices to include various radiation recycling regimes and to estimate the potential CE enhancement. The upgraded HEIGHTS was used to study recycling of both laser and plasma-generated radiation and to predict possible gains in conversion efficiency compared to no-recycling LPP devices when using droplets of tin target. We considered three versions of the LPP system including a single CO2 laser, a single Nd:YAG laser, and a dual-pulse device combining both laser systems. The gains in generating EUV energy were predicted and compared for these systems. Overall, laser and radiation energy recycling showed the potential for significant enhancement in source efficiency of up to 60% for the dual-pulse system. Significantly higher CE gains might be possible with optimization of the pre-pulse and main pulse parameters and source size.

  3. A study of the directional response of ultraviolet radiometers: I. Practical evaluation and implications for ultraviolet measurement standards.

    Science.gov (United States)

    Pye, S D; Martin, C J

    2000-09-01

    The directional responses of a range of ultraviolet radiometers commonly used for irradiance measurements of UVB and UVC have been studied. Radiometers with 24 diffuser/filter combinations were assessed using a deuterium source, and three different diffuser/filter designs were assessed using a monochromatic source. The directional responses of the radiometers have been calculated and expressed in terms of figures of merit similar to those described for (photopic) illuminance meters in BS 667 and CIE 69. Those radiometers that performed best for the measurement of both small and extended sources of UVB and UVC had raised PTFE diffusers. We conclude that UV radiometers with a directional response error f2 radiometer.

  4. Ultraviolet C Light for Acinetobacter baumannii Wound Infections in Mice: Potential Use for Battlefield Wound Decontamination?

    Science.gov (United States)

    2012-01-01

    access to food and water ad libitum. They were maintained on a 12-hour light and dark cycle at room temperature. For skin abrasion infections, 19 mice...deparaffinized, and rehydrated with distilled water . Skin sections were incubated for 30 minutes at room temperature with antithymine dimer monoclonal anti...by in vivo bioluminescence imaging. Photochem Photobiol. 2002;75:51 57. 15. Jett BD, Hatter KL, Huycke MM, et al. Simplified agar plate method for

  5. Ultraviolet radiation in the Arctic - The impact of potential ozone depletions and cloud effects

    Science.gov (United States)

    Tsay, Si-Chee; Stamnes, Knut

    1992-01-01

    The combined effects of ozone depletions/redistributions and particulate clouds on atmospheric cheating/photolysis rates and UV radiation reaching the biosphere are investigated by means of an atmospheric radiation model. Consideration is given to four types of particulate clouds prevalent in the summertime Arctic: stratospheric aerosols, tropospheric aerosols (Arctic haze), cirrus clouds, and stratus clouds. The effects of ozone depletion and vertical redistributions of ozone are also examined. Stratus clouds are found to provide significant protection from UV radiation exposure, but while stratospheric aerosols imply increased UVB exposure, Arctic haze results in a decrease. A redistribution of ozone from the stratosphere to the troposphere tends to decrease UV exposure, but for low solar elevations an increase may occur. A 20-percent ozone depletion leads to about 0.4 K/d cooling in the lower stratosphere, while redistribution of ozone from the stratosphere to the troposphere implies a warming of about 0.015 K/d in the upper troposphere.

  6. Disinfection and regrowth potential of bacillus subtilis spores by ozone, ultraviolet rays and gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hae Yeon; Lee, O Mi; Kim, Tae Hun; Lee, Myun Joo; Yu, Seung Ho [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2009-06-15

    Chlorination has been the most commonly adopted disinfection process for the treatment of drinking water. However, Cryptosporidium parvum oocysts and Giardia lamblia cysts were not treated effectively by the common chlorine-based disinfectants. Additionally the regrowth of pathogenic microorganisms is associated with hygienic and aesthetic problems for the consumers of drinking water. Study on alternative disinfection processes such as ozone, UV-C, VUV and gamma irradiation were conducted. Bacillus subtilis spores have been used as a surrogate microorganism for Cryptosporidium parvum oocysts and Giardia lamblia cyst. Inactivation efficiency by ozone was from 30% to 96% within the range of 5 min to 120 min exposures. Inactivation efficiencies by UV-C and VUV were 95.18%, 95.07% at 30 sec, respectively. Inactivation efficiency at gamma irradiation dose of 2 kGy was 99.4%. Microbial regrowths after ozone, UV-C, VUV and gamma irradiation disinfections were also evaluated for 4 days. Bacillus subtilis spores after ozone treatment for 120 min exposure at the rate of 1.68 mg {center_dot} min{sup -1} showed 96.02% disinfection efficiency and significant microbial regrowth. Bacillus subtilis spores after UV-C (99.25% disinfection efficiency) and VUV (99.67% disinfection efficiency) treatments for 5 min showed gradual regrowth. However, inactivation efficiency of gamma irradiation at dose of 1 kGy was 98.8% and the disinfected sample showed no microbial regrowth for 4 days. Therefore, gamma irradiation is the most effective process for the disinfection of pathogenic microorganisms such as oocysts of protozoan parasites among four disinfection process.

  7. Non-Destructive Evaluation of Materials via Ultraviolet Spectroscopy

    Science.gov (United States)

    Pugel, Betsy

    2008-01-01

    A document discusses the use of ultraviolet spectroscopy and imaging for the non-destructive evaluation of the degree of cure, aging, and other properties of resin-based composite materials. This method can be used in air, and is portable for field use. This method operates in reflectance, absorbance, and luminescence modes. The ultraviolet source is used to illuminate a composite surface of interest. In reflectance mode, the reflected response is acquired via the imaging system or via the spectrometer. The spectra are analyzed for organic compounds (conjugated organics) and inorganic compounds (semiconducting band-edge states; luminescing defect states such as silicates, used as adhesives for composite aerospace applications; and metal oxides commonly used as thermal coating paints on a wide range of spacecraft). The spectra are compared with a database for variation in conjugation, substitution, or length of molecule (in the case of organics) or band edge position (in the case of inorganics). This approach is useful in the understanding of material quality. It lacks the precision in defining the exact chemical structure that is found in other materials analysis techniques, but it is advantageous over methods such as nuclear magnetic resonance, infrared spectroscopy, and chromatography in that it can be used in the field to assess significant changes in chemical structure that may be linked to concerns associated with weaknesses or variations in structural integrity, without disassembly of or destruction to the structure of interest.

  8. The Far-Ultraviolet Spectra of "Cool" PG1159 Stars

    Science.gov (United States)

    Werner, K.; Rauch, T.; Kruk, J. W.

    2015-01-01

    We present a comprehensive study of Far Ultraviolet Spectroscopic Explorer (FUSE) spectra (912-1190 A) of two members of the PG1159 spectral class, which consists of hydrogen-deficient (pre-) white dwarfs with effective temperatures in the range T(sub eff) = 75000-200000 K. As two representatives of the cooler objects, we have selected PG1707+427 (T(sub eff) = 85000 K) and PG1424+535 (T(sub eff) = 110000 K), complementing a previous study of the hotter prototype PG1159-035 (T(sub eff) = 140000 K). The helium-dominated atmospheres are strongly enriched in carbon and oxygen, therefore, their spectra are dominated by lines from C III-IV and O III-VI, many of which were never observed before in hot stars. In addition, lines of many other metals (N, F, Ne, Si, P, S, Ar, Fe) are detectable, demonstrating that observations in this spectral region are most rewarding when compared to the near-ultraviolet and optical wavelength bands. We perform abundance analyses of these species and derive upper limits for several undetected light and heavy metals including iron-group and trans-iron elements. The results are compared to predictions of stellar evolution models for neutron-capture nucleosynthesis and good agreement is found.

  9. High resolution ultraviolet imaging spectrometer for latent image analysis.

    Science.gov (United States)

    Lyu, Hang; Liao, Ningfang; Li, Hongsong; Wu, Wenmin

    2016-03-21

    In this work, we present a close-range ultraviolet imaging spectrometer with high spatial resolution, and reasonably high spectral resolution. As the transmissive optical components cause chromatic aberration in the ultraviolet (UV) spectral range, an all-reflective imaging scheme is introduced to promote the image quality. The proposed instrument consists of an oscillating mirror, a Cassegrain objective, a Michelson structure, an Offner relay, and a UV enhanced CCD. The finished spectrometer has a spatial resolution of 29.30μm on the target plane; the spectral scope covers both near and middle UV band; and can obtain approximately 100 wavelength samples over the range of 240~370nm. The control computer coordinates all the components of the instrument and enables capturing a series of images, which can be reconstructed into an interferogram datacube. The datacube can be converted into a spectrum datacube, which contains spectral information of each pixel with many wavelength samples. A spectral calibration is carried out by using a high pressure mercury discharge lamp. A test run demonstrated that this interferometric configuration can obtain high resolution spectrum datacube. The pattern recognition algorithm is introduced to analyze the datacube and distinguish the latent traces from the base materials. This design is particularly good at identifying the latent traces in the application field of forensic imaging.

  10. Ultraviolet Thomson Scattering from Direct-Drive Coronal Plasmas

    Science.gov (United States)

    Henchen, R. J.; Goncharov, V. N.; Michel, D. T.; Follett, R. K.; Katz, J.; Froula, D. H.

    2013-10-01

    Ultraviolet (λ4 ω = 263 nm) Thomson scattering (TS) was used to probe ion-acoustic waves (IAW's) and electron plasma waves (EPW's) from direct-drive coronal plasmas. Fifty-nine drive beams (λ3 ω = 351 nm) illuminate a spherical target with a radius of ~860 μm. Advances in the ultraviolet (UV) TS diagnostic at the Omega Laser Facility provide the ability to detect deep UV photons (~190 nm) and allow access to scattered light from EPW's propagating near the 3 ω quarter-critical surface (~2.5 × 1021 cm-3) . A series of experiments studied the effects of ablator materials on coronal plasma conditions. Electron temperatures and densities were measured from 150 μm to 400 μm from the initial target surface. Standard CH shells were compared to three-layered shells consisting of Si doped CH, Si, and Be. Early analysis indicates that these multilayered targets have less hot-electron energy as a result of higher electron temperature in the coronal plasma. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  11. Photoreactions of Porphyrins Initiated by Deep Ultraviolet Single Photons.

    Science.gov (United States)

    Chen, Jing; Luo, Zhixun; Fu, Hongbing; Yao, Jiannian

    2017-06-22

    The newly built 177 nm all-solid-state deep ultraviolet (DUV) laser photoionization mass spectrometer finds a unique advantage to identify porphyrins that bear ionization energies close to 7.0 eV. We observed dramatic selectivity of tetraphenylporphyrins (TPPs) pertaining to varied photochemical processes initiated by the DUV laser excitation. Single-photon ionization was found dominant for 2H-TPP resulting in a fragmentation-free mass spectrum; photoinduced dehydrogenation was observed for zinc TPP, but both dehydrogenation and demetalation are noted for copper TPP. Along with first-principle calculations, we demonstrate how the photoinduced reactions vary with residual energies of photoionization, highest occupied molecular orbital-lowest unoccupied molecular orbital gaps, donor-acceptor orbital overlaps, single-step barriers, and whether or not there is a major process of structural rearrangement. It is demonstrated that the rotation of benzene ring under proper laser radiation prompts dehydrogenation process; also, metallo-TPPs do not support direct demetalation, but it is selectively accomplishable along with dehydrogenation and successive hydrogenation processes. These findings not only provide insights into the hydrogen atom transfer in porphyrins initiated by ultraviolet laser but also suggest promising applications of the DUV laser in designed synthesis and chemical modification of porphyrins.

  12. International Conference “Ultraviolet Properties of Evolved Stellar Populations

    CERN Document Server

    Chavez Dagostino, Miguel

    2009-01-01

    This book presents an up-to-date collection of reviews and contributed articles in the field of ultraviolet astronomy. Its content has been mainly motivated by the recent access to the rest frame UV light of distant red galaxies, gained through large optical facilities. This driveway has derived in a renewed interest on the stars that presumably dominate or have important effects on the integrated UV properties of evolved systems of the nearby and faraway Universe. The topics included in this volume extend from the fresh spectroscopic analyses of high redshift early-type galaxies observed with the 8-10m class telescopes to the fundamental outcomes from various satellites, from the long-lived International Ultraviolet Explorer to current facilities, such as the Galaxy Evolution Explorer. This is one of the few volumes published in recent years devoted to UV astronomical research and the only one dedicated to the properties of evolved stellar populations at these wavelengths. This contemporary panorama will be ...

  13. Riboflavin/ultraviolet a crosslinking of the paracentral cornea.

    Science.gov (United States)

    Koller, Tobias; Schumacher, Silvia; Fankhauser, Franz; Seiler, Theo

    2013-02-01

    The depth of corneal crosslinking (CXL) does not seem homogeneous within the treatment area but shows a reduction toward the periphery of the cornea. This study was undertaken to investigate this reduction effect and to look for possible solutions. Ten corneas were investigated by means of an optical coherence tomography system (SS-100; Tomey, Nagoya, Japan) 1 month after standard CXL (epithelium off, 0.1% riboflavin for 30 minutes, ultraviolet A radiation 365 nm, 3 mW/cm). The depth of the demarcation line was measured as a function of the radial distance from the apex. These curves were compared with a theoretical curve derived from a standard model of photopolymerization. The CXL depth 3 mm away from the center decreases on average to 65% of the central depth (range: 52%-78%). Polymerization theory predicts this decay, however, underestimates the effect. The intended depth of CXL using current light sources is achieved only within the central area of the cornea. To provide CXL to the peripheral cornea, the ultraviolet beam either should have an improved intensity profile or may have to be decentered.

  14. Spectral signature of ultraviolet solar irradiance in Zacatecas

    Energy Technology Data Exchange (ETDEWEB)

    Pinedo V, J. L; Mireles G, F; Rios M, C; Quirino T, L. L; Davila R, J. I [Universidad Autonoma de Zacatecas, Zacatecas, Zacatecas (Mexico)

    2006-10-15

    This study presents an analysis of the global ultraviolet spectral irradiance (290-400 nm) registered in Zacatecas, a city near the Tropic of Cancer, located at 2500 m above sea level, latitude of 22 degrees N and longitude of 102 degrees W. The spectra have been measured using a Bentham radiometer with a 0.5 nm step in wavelength. The measurements show relatively high levels of ultraviolet irradiance (UV), which may be characteristic of areas close to the Tropic of Cancer. Faced with an increase of the incidence of skin cancer among the population of Zacatecas, these measurements highlight that a damage prevention plan is required. [Spanish] En este trabajo se presenta un analisis de la radiacion espectral global ultravioleta (290-400 nm) registrada en Zacatecas, una ciudad vecina al tropico de cancer, situada a 2500 m sobre el nivel del mar, latitud de 22 grados N y longitud de 102 grados O. Los espectros correspondientes han sido medidos mediante un espectroradiometro Bentham con un paso de 0.5 nm de longitud de onda. Las mediciones muestran niveles de radiacion ultravioleta (UV) relativamente elevados, que pueden ser caracteristicos de las zonas vecinas al tropico de cancer. Frente al aumento de incidencia de cancer en la piel en la poblacion del estado de Zacatecas, estas mediciones ponen en relieve la necesidad de formular un plan preventivo de danos.

  15. The Far-Ultraviolet Imaging Spectrograph on KAISTAT-4

    Science.gov (United States)

    Min, K. W.; Edelstein, J.; Korpela, E.; Dixon, W. V.; Seon, J. H.; Han, W. Y.; Nam, U. W.

    1999-12-01

    The Far-ultraviolet Imaging Spectrograph (FIMS), a joint project of the University of California, Berkeley, The Korea Aerospace Institute of Science and Technology, and the Korea Astronomy Observatory, will conduct observations of diffuse far ultra-violet (900 - 1800 /AA) cosmic emission. FIMS observations will: 1) trace the energy flow through the hot plasmas found on scales ranging from SN bubbles to galaxies and galactic coronae; 2) map the distribution of the local and global structures of 104.5 - 106 K plasma; and 3) Measure the nature, distribution and life cycle of galactic H2 and dust. FIMS's broad band-pass and 1 - 2 /AA spectral resolution provide the diagnostics necessary to disentangle the effects of both abundance variations and ionization equilibrium. The instrument's imaging and background-rejection will yield far-UV emission-line sensitivity that is an order of magnitude fainter than any previous detection. FIMS is the primary payload on the KAITSAT-4 satellite, a 3-axis stabilized platform that will provide both an all-sky survey and a target-pointing program. The mission is scheduled for launch in 2002. The development of FIMS has supported to date by KAIST, KAO and SSL, UCB.

  16. Effects of ultraviolet-B radiation on fungal disease development in Cucumis sativus

    Energy Technology Data Exchange (ETDEWEB)

    Orth, A.B.; Teramura, A.H.; Sisler, H.D. (Univ. of Maryland, College Park (USA))

    1990-09-01

    Stratospheric ozone depletion due to increased atmospheric pollutants has received considerable attention because of the potential increase in ultraviolet-B (UV-B, 280-320 nm) radiation that will reach the earth's surface. Three cucumber (Cucumis sativus L.) cultivars were exposed to a daily dose of 11.6 kJ m{sup {minus}2} biologically effective ultraviolet-B (UV-B{sub BE}) radiation in an unshaded greenhouse before and/or after injection by Colletotrichum lagenarium (Pass.) Ell. and Halst. or Cladosporium cucumerinum Ell. and Arth. and analyzed for disease development. Two of these cultivars, Poinsette and Calypso Hybrid, were disease resistant, while the third cultivar, Straight-8, was disease susceptible. Preinfectional treatment of 1 to 7 days with UV-B{sub BE} in Straight-8 led to greater severity of both diseases. Postinfectional UV treatment did not lead to increased disease severity caused by C. lagenarium, while preinfectional UV treatment in both Straight-8 and Poinsette substantially increased disease severity. Although resistant cultivars Poinsette and Calypso Hybrid showed increased anthracnose disease severity when exposed to UV-B, this effect was apparent only on the cotyledons. Both higher spore concentration and exposure to UV-B radiation resulted in greater disease severity. Of the cucumber cultivars tested for UV-B sensitivity, growth in Poinsette was most sensitive and Calypso Hybrid was least sensitive. These preliminary results indicate that the effects of UV-B radiation on disease development in cucumber vary depending on cultivar, timing and duration of UV-B exposure, inoculation level, and plant age.

  17. Real-time measurement of outdoor worker's exposure to solar ultraviolet radiation in Pretoria, South Africa

    Directory of Open Access Journals (Sweden)

    Mmathapelo Makgabutlane

    2015-05-01

    Full Text Available The city of Pretoria in South Africa receives considerable solar ultraviolet radiation (UVR because of its low latitude (22–35°S and relatively clear skies. Certain meteorological factors affect the amount of solar UVR that reaches the ground; the most dominant factors being stratospheric ozone, cloud cover and solar zenith angle. It is known that overexposure to solar UVR may lead to the development of adverse health conditions, the most significant being skin cancer. Outdoor workers spend a significant amount of time outside and are thus susceptible to this risk. In this case study, we estimated, for the first time, the real-time solar UVR exposure of an outdoor worker in Pretoria. Measurements were made on 27 and 28 May 2013 using a handheld ultraviolet index (UVI meter calibrated against a science-grade biometer at the South African Weather Service in Pretoria. Personal exposure estimation was used to discern the pattern in diurnal and annual sunburn risk for the outdoor worker. Ambient UVR levels ranged from 0 UVI to 4.66 UVI and the outdoor worker’s potential exposure estimates regularly exceeded 80% of these levels depending on the time of day. The risk of sunburn was evident; however, actual incidents would depend on individual skin photosensitivity and melanin content, as well as sun protection used. Further research is needed to determine the personal exposure estimations of outdoor workers in other provinces in which solar UVR levels may be equally high, or higher than those in Pretoria.

  18. Performance of ultraviolet photocatalytic oxidation for indoor air applications: Systematic experimental evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Lexuan [Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, Quebec H3G 1M8 (Canada); Haghighat, Fariborz, E-mail: fariborz.haghighat@concordia.ca [Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, Quebec H3G 1M8 (Canada); Lee, Chang-Seo [Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, Quebec H3G 1M8 (Canada); Lakdawala, Ness [DECTRON International Inc., Montreal, Quebec (Canada)

    2013-10-15

    Highlights: • An innovative experimental set-up was designed and constructed for testing UV-PCO. • Test methodologies were developed to examine UV-PCO air cleaners for VOCs removal. • VOCs type, inlet concentration, flow rate, irradiance, and RH have influence on PCO. • Gas-phase ozonation with a variety of compounds was examined in a duct system. • Formation of by-products generated from incomplete conversion was investigated. -- Abstract: Photocatalytic oxidation (PCO) is a promising technology that has potential to be applied in mechanically ventilated buildings to improve indoor air quality (IAQ). However, the major research studies were done in bench-top scale reactors under ideal reaction conditions. In addition, no study has been carried out on the investigation of the ozonation and photolysis effect using a pilot duct system. The objective of this study is the development of methodologies to evaluate the performance of PCO systems. A systematic parametric evaluation of the effects of various kinetic parameters, such as compound's type, inlet concentration, airflow rate, light intensity, and relative humidity, was conducted, and new interpretations were provided from a fundamental analysis. In addition, the photolysis effect under vacuum ultraviolet (VUV) irradiation for a variety of volatile organic compounds (VOCs) was examined for the first time in a pilot duct system. The performance comparison of ultraviolet C (UVC)-PCO and VUV-PCO was also discussed due to the presence of ozone. Moreover, the formation of by-products generated with or without ozone generation was fully compared to evaluate the PCO technology.

  19. "Parallel factor analysis of multi-excitation ultraviolet resonance Raman spectra for protein secondary structure determination".

    Science.gov (United States)

    Oshokoya, Olayinka O; JiJi, Renee D

    2015-09-10

    Protein secondary structural analysis is important for understanding the relationship between protein structure and function, or more importantly how changes in structure relate to loss of function. The structurally sensitive protein vibrational modes (amide I, II, III and S) in deep-ultraviolet resonance Raman (DUVRR) spectra resulting from the backbone C-O and N-H vibrations make DUVRR a potentially powerful tool for studying secondary structure changes. Experimental studies reveal that the position and intensity of the four amide modes in DUVRR spectra of proteins are largely correlated with the varying fractions of α-helix, β-sheet and disordered structural content of proteins. Employing multivariate calibration methods and DUVRR spectra of globular proteins with varying structural compositions, the secondary structure of a protein with unknown structure can be predicted. A disadvantage of multivariate calibration methods is the requirement of known concentration or spectral profiles. Second-order curve resolution methods, such as parallel factor analysis (PARAFAC), do not have such a requirement due to the "second-order advantage." An exceptional feature of DUVRR spectroscopy is that DUVRR spectra are linearly dependent on both excitation wavelength and secondary structure composition. Thus, higher order data can be created by combining protein DUVRR spectra of several proteins collected at multiple excitation wavelengths to give multi-excitation ultraviolet resonance Raman data (ME-UVRR). PARAFAC has been used to analyze ME-UVRR data of nine proteins to resolve the pure spectral, excitation and compositional profiles. A three factor model with non-negativity constraints produced three unique factors that were correlated with the relative abundance of helical, β-sheet and poly-proline II dihedral angles. This is the first empirical evidence that the typically resolved "disordered" spectrum represents the better defined poly-proline II type structure

  20. Limits to the salience of ultraviolet: lessons from colour vision in bees and birds.

    Science.gov (United States)

    Kevan, P G; Chittka, L; Dyer, A G

    2001-07-01

    Ultraviolet is an important component of the photic environment. It is used by a wide variety of animals and plants in mutualistic communication, especially in insect and flower inter-relationships. Ultraviolet reflections and sensitivity are also becoming well considered in the relationships between vertebrates and their environment. The relative importance of ultraviolet vis à vis other primary colours in trichromatic or tetrachromatic colour spaces is discussed, and it is concluded that ultraviolet is, in most cases, no more important that blue, green or red reflections. Some animals may use specific wavebands of light for specific reactions, such as ultraviolet in escape or in the detection of polarised light, and other wavebands in stimulating feeding, oviposition or mating. When colour vision and, thus, the input from more than a single spectral receptor type are concerned, we point out that even basic predictions of signal conspicuousness require knowledge of the neuronal wiring used to evaluate the signals from all receptor types, including the ultraviolet. Evolutionary analyses suggest that, at least in arthropods, ultraviolet sensitivity is phylogenetically ancient and undergoes comparatively little evolutionary fine-tuning. Increasing amounts of ultraviolet in the photic environment, as caused by the decline of ozone in the atmosphere, are not likely to affect colour vision. However, a case for which ultraviolet is possibly unique is in the colour constancy of bees. Theoretical models predict that bees will perform poorly at identifying pure ultraviolet signals under conditions of changing illumination, which may explain the near absence of pure ultraviolet-reflecting flowers in nature.

  1. Ultraviolet radiation influences perch selection by a neotropical poison-dart frog.

    Directory of Open Access Journals (Sweden)

    Lee B Kats

    Full Text Available Ambient ultraviolet-B radiation can harm amphibian eggs, larvae and adults. However, some amphibians avoid UV-B radiation when given the opportunity. The strawberry poison dart frog, Oophaga pumilio, is diurnal and males vocalize throughout the day in light gaps under forest canopies that expose them to solar radiation. Previous studies have demonstrated that males calling from high perches are more successful at mating than those at lower perches. We investigated whether frogs at higher perches receive more ultraviolet-B than those calling from lower perches. We also investigated whether frogs on perches receiving relatively low ultraviolet-B levels maintained their positions for longer compared to individuals calling from perches receiving higher levels of ultraviolet-B. Finally, since it has been hypothesized that some animals utilize levels of UV-A as a visual cue to avoid UV-B damage, we artificially elevated ultraviolet-A levels to examine whether males exposed to artificially elevated ultraviolet-A abandoned their perches sooner compared to males exposed to visible light. We found that frogs called from perches receiving low ultraviolet-B regardless of perch height, and that frogs maintain their positions longer on perches receiving low ultraviolet-B compared to perches receiving even slightly higher ultraviolet-B levels. Exposing the frogs to artificially elevated levels of ultraviolet-A radiation caused males to move off of their perches faster than when they were exposed to a control light source. These experiments suggest that ultraviolet radiation plays an important role in frog behavior related to perch selection, even in rainforests where much of the solar radiation is shielded by the forest canopy.

  2. Radiosensitization of human breast cancer cells to ultraviolet light by 5-fluorouracil

    Science.gov (United States)

    SASAKI, KAZUHITO; TSUNO, NELSON H.; SUNAMI, EIJI; KAWAI, KAZUSHIGE; SHUNO, YASUTAKA; HONGO, KUMIKO; HIYOSHI, MASAYA; KANEKO, MANABU; MURONO, KOJI; TADA, NORIKO; NIREI, TAKAKO; KITAYAMA, JOJI; TAKAHASHI, KOKI; NAGAWA, HIROKAZU

    2011-01-01

    Ultraviolet light B (UVB) phototherapy is widely used to treat dermatological diseases and therefore may be a potential optional strategy in the treatment of a skin lesion infiltrated by a malignant tumor. Currently, little is known regarding the effect of UVB phototherapy on human breast cancer cells. The present study aimed to investigate the effect of UVB phototherapy, as well as the potential effect of 5-fluorouracil (5-FU), the first-line anticancer drug for breast cancer, on radiosensitizing MCF-7 human breast cancer cells, in an attempt to develop new therapeutic strategies for the treatment of locoregional recurrence of breast cancer. MCF-7 cells were incubated in the presence of 5-FU for 48 h, and UVB irradiation at 750 mJ/cm2 was administered in the midterm of 5-FU treatment. The viability of MCF-7 cells was analyzed by the trypan blue staining method. Apoptosis was quantified by flow cytometry and Hoechst 33258 staining. The cell cycle was evaluated by flow cytometry after the staining of cells with propidium iodide. The combination treatment of 5-FU and UVB resulted in a strong potentiation of the inhibitory effect of MCF-7 cell growth, dependent on the intra-S phase cell cycle arrest and induction of apoptosis, when compared to treatment with 5-FU or UVB alone. In conclusion, 5-FU sensitized human breast cancer cells to UVB phototherapy, and this combination therapy is an effective and promising strategy for the treatment of breast cancer, particularly for locoregional recurrence. PMID:22866105

  3. An empirical model of erythemal ultraviolet radiation in the city of Valencia, Spain.

    Science.gov (United States)

    Moreno, J C; Serrano, M A; Lorente, M; Cañada, J; Utrillas, M P

    2013-09-01

    This paper presents an improved empirical model that predicts ultraviolet erythemal radiation (UVER) and considers all aspects of atmospheric conditions in Valencia, Spain. The analyzed model is a potential function whose dependent variable is UVER radiation and independent variables are the clearness index and slant ozone column. A potential regression function with all the information contributed a small coefficient of determination and one chose to use a regression potential-exponential mathematical form which improved the coefficient of similar determination. A study was carried out on the influence of season on the regression parameters. This was found to be considerable due to the clearness index. The convergence between the values calculated by the model and the experimental values was analyzed using the mean bias error (MBE) and mean absolute bias error (MABE) statistical parameters. The clearness index and ozone column intervals were analyzed and found to give an improved prediction of the UVER clearness index using regression analysis. Also, a sensitivity analysis was performed on the regression coefficients and parameters. It is important to study the effects of UVER radiation predicted by the model on human health or on agriculture crop growth and yield.

  4. [Ultraviolet A-induced DNA damage: role in skin cancer].

    Science.gov (United States)

    Beani, Jean-Claude

    2014-02-01

    Skin cancer is the most common human malignancy, and sunlight exposure is known to play a role in its genesis. Ultraviolet B (UVB) (300-320 nm) has long been considered responsible for the skin damage underlying these cancers, whereas the toxicity of UVA (320-400 nm) has been largely overlooked The intimate mechanisms of photocarcinogenicity remain poorly understood, but UV-induced DNA damage appears to be a major initiating event. Cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6-4) photoproducts (6-4PPs) are the main dimeric lesions induced by UVB, whereas the genotoxic effects of UVA have long been attributed to oxidative damage, the main lesion being the oxidized base 8-oxo-7,8dihydroguanine (8-oxoGua). However; powerful new techniques for analyzing DNA damage (the Comet assay, and especially HPLC-MSIMS) have demonstrated that UVA irradiation mainly triggers the formation of CPDs, especially CPD-TT both in cell models and in total human skin. A direct photochemical process is currently thought to account for CPD induction by UVA. The multilayer structure of the epidermis protects against UVB-induced dipyrimidine lesions in total skin but offers only weak protection against UVA. In addition, repair efficiency is undermined by UVA. CPDs, the main DNA lesions induced by UVA in total skin (which is more permeable to UVA), are inefficiently repaired CPDs have strong mutagenic potential, and recent studies clearly show that CPDs, rather than 8-Oxo-Gua, are the main mutagenic photoproducts induced by UVA. The UV signature of induced mutations is characterized by transitions from C to T or CC to TT in dipyrimidine sequences. These mutations target the p53, patched 1 and SMO genes in carcinomas, and the PTEN RAC1, PPP6C, STK19 and PPP6C genes in melanomas of exposed skin. UVA also mainly induces CPDs in melanocytes, in amounts similar to those observed in keratinocytes, demonstrating that melanin does not prevent CPD formation. In contrast, UVA induces far more

  5. Extreme ultraviolet observations of G191-B2B and the local interstellar medium with the Hopkins Ultraviolet Telescope

    Science.gov (United States)

    Kimble, Randy A.; Davidsen, Arthur F.; Blair, William P.; Bowers, Charles W.; Van Dyke Dixon, W.; Durrance, Samuel T.; Feldman, Paul D.; Ferguson, Henry C.; Henry, Richard C.; Kriss, Gerard A.

    1993-01-01

    During the Astro-l mission in 1990 December, the Hopkins Ultraviolet Telescope (HUT) was used to observe the extreme ultraviolet spectrum (415-912 A) of the hot DA white dwarf GI91-B2B. Absorption by neutral helium shortward of the 504 A He I absorption edge is clearly detected in the raw spectrum. Model fits to the observed spectrum require interstellar neutral helium and neutral hydrogen column densities of 1.45 +/- 0.065 x 10 exp 17/sq cm and 1.69 +/- 0.12 x 10 exp 18/sq cm, respectively. Comparison of the neutral columns yields a direct assessment of the ionization state of the local interstellar cloud surrounding the Sun. The neutral hydrogen to helium ratio of 11.6 +/- 1.0 observed by HUT strongly contradicts the widespread view that hydrogen is much more ionized than helium in the local interstellar medium, a view which has motivated some exotic theoretical explanations for the supposed high ionization.

  6. Suppressive action of near-ultraviolet light on ouabain resistance induced by far-ultraviolet light in Chinese hamster cells.

    Science.gov (United States)

    Suzuki, F; Han, A; Hill, C K; Elkind, M M

    1983-03-01

    The interaction between ultraviolet light (UV-C) from germicidal lamps (254 nm) and near-ultraviolet light (UV-B) from Westinghouse Sun Lamps (290-345 nm) was studied in Chinese hamster V79 cells by measuring the effectiveness of combined exposures to induce the resistance to 6-thioguanine or to ouabain. Exposure of cells to a conditioning dose of UV-B (approximately 70% survival) results in significant inhibition of the induction by UV-C of cells resistant to ouabain. The inhibition is lost, however, if cells are incubated for 12 h at 37 degrees C between exposures. Inhibition is also observed when cells are preirradiated with a dose of UV-B filtered with polystyrene (300-345 nm) which, in itself, has no effect on cell killing. Conditioning exposures of unfiltered or filtered UV-B light do not inhibit the induction of 6-thioguanine-resistant cells by UV-C light, and the effects of UV-B and UV-C light are largely independent.

  7. Assessment of health consequences of occupational exposure to ultraviolet radiation in steel industry welders

    Directory of Open Access Journals (Sweden)

    E Asmand

    2014-10-01

    Conclusion: Duration of ultraviolet rays in welders was above the threshold limit of the contact in Iran. Considering the prevalence of eye and skin disorders in welders, reducing the duration of exposure to ultraviolet radiation control and the use of proper personal protective equipment is necessary.

  8. The relation between sunscreen layer thickness and vitamin D production after ultraviolet B exposure

    DEFF Research Database (Denmark)

    Faurschou, A; Beyer, D M; Schmedes, A

    2012-01-01

    Sunscreens absorb ultraviolet B (UVB) and it is a major concern that sunscreen use may lead to vitamin D deficiency.......Sunscreens absorb ultraviolet B (UVB) and it is a major concern that sunscreen use may lead to vitamin D deficiency....

  9. The effect of solar ultraviolet radiation (UVR) on induction of skin cancers

    National Research Council Canada - National Science Library

    Pacholczyk, Marta; Czernicki, Jan; Ferenc, Tomasz

    2016-01-01

    Ultraviolet radiation is a physical mutagenic and cancerogenic factor. About 95% of ultraviolet A (UVA) (320–400 nm) and 5% of UVB (280–320 nm) reach the Earth’s surface. Melanin is a natural skin protective factor against UV radiation...

  10. The World Space Observatory - Ultraviolet (WSO-UV Space Telescope; Status Update in 2013

    Directory of Open Access Journals (Sweden)

    Ana I. Gómez de Castro

    2014-12-01

    Full Text Available This is a short primer and a brief update on the status of the World Space Observatory-Ultraviolet (WSO-UV project dated in May 2013. WSO-UV is a 170m primary space telescope equipped for ultraviolet imaging and spectroscopy that will be operational in 2017 hosting an open science program for the world-wide scientic community.

  11. Comparative profiling of biomarker psoralen in antioxidant active ...

    African Journals Online (AJOL)

    Materials and Methods: HPTLC studies were carried out using CAMAG HPTLC system on Glass-backed silica gel 60F254 HPTLC pre-coated plates using selected mobile phase toluene: methanol (9:1). The antioxidant activity was carried out, using DPPH free radical method. Results: Among all the five species of genus ...

  12. Diagnosis of clear sky ultraviolet radiation for Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Lemus Deschamps, L. [Bureau of Meteorology Research Centre (Australia); Galindo, I.; Solano, R.; Elizalde, A.T.; Fonseca, J. [Centro Universitario de Investigaciones en Ciencias del Ambiente, University of Colima (Mexico)

    2002-07-01

    A discrete-ordinate radiative transfer model is employed to develop a regional clear sky ultraviolet (UV) diagnosis system. The clear sky UV radiation, weighted by the spectral sensitivity of human skin is calculated using the Total Ozone Mapping Spectrometer (TOMS) data sets. Examples of the geographical clear sky UV Index distributions are presented and the model results are compared with surface UV measurements from University of Colima for 1999. [Spanish] Utilizando un modelo de transferencia de radiacion de ordenadas discretas se desarrolla un sistema para el diagnostico de la distribucion de radiacion ultravioleta para cielo despejado en la Republica Mexicana. La radiacion para cielo despejado se obtiene utilizando la respuesta espectral de la piel humana y los datos de satelite de ozono total registrados por el espectrometro TOMS. Se presentan ejemplos del Indice de radiacion ultravioleta (UV Index) calculados con el modelo y se comparan con las mediciones en superficie obtenidas en la Universidad de Colima durante 1999.

  13. Recherche et Analyse de Galaxies Brilliantes EN Exces EN Ultraviolet

    Science.gov (United States)

    Coziol, Roger

    Dans ce travail, nous decrivons et presentons les resultats du sondage Montreal Blue Galaxy (MBG) visant la recherche de galaxies emettant en exces en ultraviolet. Cette recherche utilise le materiel photographique du sondage MCT (Montreal-Cambridge-Tololo) qui par son etendue correspond a un des plus importants sondages de l'hemisphere austral. Le sondage MBG est presentement le seul dans cet hemisphere a employer la technique de poses multiples pour la selection de ses candidats. Grace a cette technique, nous avons l'occasion d'etudier un echantillon de galaxies ayant des caracteristiques quelque peu differentes de celles des echantillons analyses auparavant. Deux phenomenes peuvent expliquer l'exces d'ultraviolet observe dans ces galaxies. Le premier suppose la presence dans leur noyau d'un trou noir massif. Toutes les galaxies sujettes a ce type d'activite sont regroupees sous le nom de galaxies avec noyau actif (AGN). Le deuxieme phenomene est relie a une periode de formation intense d'etoiles, ou sursaut de formation d'etoiles ("starburst"). L'exces d'ultraviolet trahit ici la presence d'un grand nombre d'etoiles massives recemment creees au sein de ces galaxies. En plus d'augmenter le nombre d'AGN connues, les sondages de galaxies brillantes en ultraviolet permettent aussi d'approfondir les questions specifiques suivantes: combien y a-t'il de galaxies starbursts differentes? Quelle est l'origine possible de leur activite? Quel est le role des sursauts de formation d'etoiles dans la vie d'une galaxie? Quel est le lien entre les galaxies starbursts et les AGN?. L'analyse de notre echantillon de galaxies se fait par l'entremise de plusieurs methodes. La premiere consiste a obtenir des spectres optiques de nos candidats. L'etude de ces spectres nous permet de distinguer entre les AGN et les galaxies starbursts et de deduire plusieurs parametres physiques importants. Notre deuxieme methode consiste a obtenir des images. Ceci nous permet d'avoir une idee de la

  14. Method for the protection of extreme ultraviolet lithography optics

    Science.gov (United States)

    Grunow, Philip A.; Clift, Wayne M.; Klebanoff, Leonard E.

    2010-06-22

    A coating for the protection of optical surfaces exposed to a high energy erosive plasma. A gas that can be decomposed by the high energy plasma, such as the xenon plasma used for extreme ultraviolet lithography (EUVL), is injected into the EUVL machine. The decomposition products coat the optical surfaces with a protective coating maintained at less than about 100 .ANG. thick by periodic injections of the gas. Gases that can be used include hydrocarbon gases, particularly methane, PH.sub.3 and H.sub.2S. The use of PH.sub.3 and H.sub.2S is particularly advantageous since films of the plasma-induced decomposition products S and P cannot grow to greater than 10 .ANG. thick in a vacuum atmosphere such as found in an EUVL machine.

  15. Visualization of Aged Fingerprints with an Ultraviolet Laser.

    Science.gov (United States)

    Akiba, Norimitsu; Kuroki, Kenro; Kurosawa, Kenji; Tsuchiya, Ken'ichi

    2017-07-10

    Detection of aged fingerprints is difficult because they can degrade over time with exposure to light, moisture, and temperature. In this study, aging fingerprints were visualized by time-resolved spectroscopy with an ultraviolet-pulsed laser. Fingerprints were prepared on glass slides and paper and then stored under three lighting conditions and two humidity conditions for up to a year. The fluorescence intensities of the fingerprints decreased with time. Samples were stored in the dark degraded less than in sunlight or under a fluorescent lamp. Samples were stored under low humidity degraded less than under moderate humidity. As the storage period increased, a fluorescence emission peak appeared that was at a longer wavelength than the peak visible in earlier spectra. This peak was used for visualization of an aged fingerprint over time. An image of the fingerprint was not initially visible, but an image appeared as the time since deposition of the fingerprint increased. © 2017 American Academy of Forensic Sciences.

  16. Review of photokeratitis: Corneal response to ultraviolet radiation (UVR exposure*

    Directory of Open Access Journals (Sweden)

    L A. Moore

    2010-12-01

    Full Text Available The development of photokeratitis in response to natural solar ultraviolet radiation (UVR is prevalent in individuals participating in outdoor recreational activities in environments with high reflective surfaces, such as beach activities, water sports and snow skiing. Eye care practitioners (ECPs are frequently encouraged by manufacturers and researchers to recommend UVR-blocking eyewear in the form of sunglasses and contact lenses. However, little is known about the precise nature of the corneal tissue response in the development of photokeratitis. This paper reviews the mechanisms responsible for the development of photokeratitis. Clinical signs and symptoms of photokeratitis, UVR corneal threshold and action spectra, corneal cellular changes and ocular protection from corneal UVR exposure are discussed. The content of this article will be useful to ECPs in making appropriate recommendations when prescribing UVR-protec-tive eyewear. (S Afr Optom 2010 69(3 123-131

  17. The extra-terrestrial vacuum-ultraviolet wavelength range

    Science.gov (United States)

    Timothy, J. Gethyn; Wilhelm, Klaus; Xia, Lidong

    Electromagnetic radiation in the vacuum-ultraviolet (VUV) and extra-terrestrial range at wavelengths from 10 nm to 300 nm is absorbed in the upper atmosphere by ozone, molecular and atomic oxygen, and molecular nitrogen. Observations at wavelengths down to ≈ 200 nm can be carried out from stratospheric balloons, and observations below 200 nm require space platforms operating at altitudes above 250 km. The VUV spectral region contains emission lines and continua arising from plasma at formation temperatures ranging from about 104 K to more than 107 K. This chapter describes the wide range of plasma diagnostic techniques available at VUV wavelengths, and the development of instrumentation for studies of the high-temperature solar outer atmosphere and astrophysical plasmas. Finally, the prospects for future studies are briefly discussed.

  18. Effect of extracorporeal ultraviolet blood irradiation on blood cholesterol level

    Science.gov (United States)

    Zalesskaya, G. A.; Laskina, O. V.; Mitkovskaya, N. P.; Kirkovsky, V. V.

    2012-07-01

    We have studied the effect of extracorporeal ultraviolet blood irradiation on cholesterol metabolism in patients with cardiovascular diseases. We have carried out a comprehensive analysis of the spectral characteristics of blood and plasma, gas-exchange and oximetry parameters, and the results of a complete blood count and chemistry panel before and after UV blood irradiation. We have assessed the changes in concentrations of cholesterols (total cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides) in the blood of the patients in response to a five-day course of UV blood irradiation. The changes in the spectral characteristics of blood and plasma, the chemistry panel, the gas composition, and the fractional hemoglobin composition initiated by absorption of UV radiation are used to discuss the molecular mechanisms for the effect of therapeutic doses of UV radiation on blood cholesterols.

  19. Optical proximity correction for anamorphic extreme ultraviolet lithography

    Science.gov (United States)

    Clifford, Chris; Lam, Michael; Raghunathan, Ananthan; Jiang, Fan; Fenger, Germain; Adam, Kostas

    2017-10-01

    The change from isomorphic to anamorphic optics in high numerical aperture (NA) extreme ultraviolet (EUV) scanners necessitates changes to the mask data preparation flow. The required changes for each step in the mask tape out process are discussed, with a focus on optical proximity correction (OPC). When necessary, solutions to new problems are demonstrated, and verified by rigorous simulation. Additions to the OPC model include accounting for anamorphic effects in the optics, mask electromagnetics, and mask manufacturing. The correction algorithm is updated to include awareness of anamorphic mask geometry for mask rule checking (MRC). OPC verification through process window conditions is enhanced to test different wafer scale mask error ranges in the horizontal and vertical directions. This work will show that existing models and methods can be updated to support anamorphic optics without major changes. Also, the larger mask size in the Y direction can result in better model accuracy, easier OPC convergence, and designs which are more tolerant to mask errors.

  20. Time dependent degradation of photovoltaic modules by ultraviolet light

    Science.gov (United States)

    Zimmermann, Claus G.

    2008-06-01

    For high efficiency silicone encapsulated solar modules for concentrator photovoltaic systems or space applications, the question of performance degradation due to long term exposure to ultraviolet (UV) light is addressed. The transparent silicones DC93-500 and Elastosil S690 and S695 were subjected to a time and wavelength resolved UV test with a total accumulated dose of 10 000 equivalent sun hours. Based on a model for the kinetics of photodegradation, it is shown that the measured decrease in transmittance translates into a universal logarithmic time dependence for the module short circuit current. The UV related performance impact over 15years under the AM0 spectrum in space and the terrestrial AM1.5 spectrum with 500× concentration is quantified.

  1. Ultraviolet Observations of the Hubble Ultra Deep Field

    Science.gov (United States)

    Rafelski, Marc; Teplitz, H.; Grogin, N.; Koekemoer, A.; Siana, B.; Atek, H.; Bond, N. A.; Brown, T. M.; Coe, D.; Colbert, J.; Ferguson, H. C.; Finkelstein, S. L.; Gardner, J. P.; Gawiser, E.; Giavalisco, M.; Gronwall, C.; Hanish, D.; Kurczynski, P.; Lee, K.; Ravindranath, S.; Scarlata, C.; Voyer, E.; Wolfe, A.; de Mello, D. F.

    2012-05-01

    We present details of a 90-orbit HST treasury program to obtain Ultraviolet (UV) imaging of the Hubble Ultra Deep Field (UDF) using the WFC3-UVIS detector with the F225W, F275W, and F336W filters. These UV images will reach point source detection limits of AB=29 at 10 sigma. This survey is designed to: (i) Investigate the episode of peak star formation activity in galaxies at 1 < z < 2.5. (ii) Study the star formation properties of moderate redshift starburst galaxies. (iii) Probe the evolution of massive galaxies by resolving sub-galactic units (clumps). (iv) Examine the escape fraction of ionizing radiation from galaxies at z 2-3. (v) Measure the star formation rate efficiency of neutral atomic-dominated hydrogen gas at z 1-3. We will present preliminary results from the UVUDF team based on the first observations (beginning March 2012).

  2. Assessment and comparison of methods for solar ultraviolet radiation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Leszczynski, K.

    1995-06-01

    In the study, the different methods to measure the solar ultraviolet radiation are compared. The methods included are spectroradiometric, erythemally weighted broadband and multi-channel measurements. The comparison of the different methods is based on a literature review and assessments of optical characteristics of the spectroradiometer Optronic 742 of the Finnish Centre for Radiation and Nuclear Safety (STUK) and of the erythemally weighted Robertson-Berger type broadband radiometers Solar Light models 500 and 501 of the Finnish Meteorological Institute and STUK. An introduction to the sources of error in solar UV measurements, to methods for radiometric characterization of UV radiometers together with methods for error reduction are presented. Reviews on experiences from world-wide UV monitoring efforts and instrumentation as well as on the results from international UV radiometer intercomparisons are also presented. (62 refs.).

  3. Multifunctional optical correlator for picosecond ultraviolet laser pulse measurement.

    Science.gov (United States)

    Rakhman, Abdurahim; Wang, Yang; Garcia, Frances; Long, Cary; Huang, Chunning; Takeda, Yasuhiro; Liu, Yun

    2014-11-01

    A compact multifunctional optical correlator system for pulse width measurement of ultrashort ultraviolet (UV) pulses has been designed and experimentally demonstrated. Both autocorrelation and cross-correlation functions are measured using a single nonlinear crystal, and the switching between two measurements requires no adjustment of phase matching and detector. The system can measure UV pulse widths from sub-picoseconds to 100 ps, and it involves no auxiliary pulse in the measurement. The measurement results on a burst-mode picosecond UV laser show a high-quality performance on speed, accuracy, resolution, and dynamic range. The proposed correlator can be applied to measure any ultrashort UV pulses produced through sum-frequency generation or second-harmonic generation.

  4. Issues in Quantitative Analysis of Ultraviolet Imager (UV) Data: Airglow

    Science.gov (United States)

    Germany, G. A.; Richards, P. G.; Spann, J. F.; Brittnacher, M. J.; Parks, G. K.

    1999-01-01

    The GGS Ultraviolet Imager (UVI) has proven to be especially valuable in correlative substorm, auroral morphology, and extended statistical studies of the auroral regions. Such studies are based on knowledge of the location, spatial, and temporal behavior of auroral emissions. More quantitative studies, based on absolute radiometric intensities from UVI images, require a more intimate knowledge of the instrument behavior and data processing requirements and are inherently more difficult than studies based on relative knowledge of the oval location. In this study, UVI airglow observations are analyzed and compared with model predictions to illustrate issues that arise in quantitative analysis of UVI images. These issues include instrument calibration, long term changes in sensitivity, and imager flat field response as well as proper background correction. Airglow emissions are chosen for this study because of their relatively straightforward modeling requirements and because of their implications for thermospheric compositional studies. The analysis issues discussed here, however, are identical to those faced in quantitative auroral studies.

  5. Ultraviolet fluorescence identification of protein, DNA, and bacteria

    Science.gov (United States)

    Hargis, Philip J., Jr.; Sobering, T. J.; Tisone, Gary C.; Wagner, John S.; Young, Steve A.; Radloff, R. J.

    1995-02-01

    Recent food poisoning incidents have highlighted the need for inexpensive instrumentation that can detect food pathogens. Instrumentation that detects the relatively strong ultraviolet (UV) fluorescence signal from the aromatic protein amino acids in bacteria could provide a solution to the problem of real-time pathogen measurements. The capabilities of UV fluorescence measurements have, however, been largely ignored because of the difficulty in identifying pathogens in the presence of interfering backgrounds. Implementation of fluorescence measurements thus requires methodologies that can distinguish fluorescence features associated with pathogens from those associated with proteins, harmless bacteria, skin, blood, hair follicles, pesticide residue, etc. We describe multispectral UV fluorescence measurements that demonstrate the feasibility of detecting and identifying protein, DNA, and bacteria using a relatively simple UV imaging fluorometer and a unique multivariate analysis algorithm.

  6. Viability of quantum-gravity induced ultraviolet completions for matter

    Science.gov (United States)

    Eichhorn, Astrid; Held, Aaron

    2017-10-01

    We highlight how the existence of an ultraviolet completion for interacting standard-model type matter puts constraints on the viable microscopic dynamics of asymptotically safe quantum gravity within truncated Renormalization Group flows. A first constraint—the weak-gravity bound—is rooted in the destruction of quantum scale-invariance in the matter system by strong quantum-gravity fluctuations. A second constraint arises by linking Planck-scale dynamics to the dynamics at the electroweak scale. Specifically, we delineate how to extract a prediction of the top quark mass from asymptotically safe gravity and stress that a finite top mass could be difficult to accommodate in a significant part of the gravitational coupling space.

  7. Improved Lyman Ultraviolet Astronomy Capabilities through Enhanced Coatings

    Science.gov (United States)

    Quijada, Manuel A.; del Hoyo, Javier; Boris, David; Walton, Scott

    2017-01-01

    This paper will describe efforts at developing broadband mirror coatings with high performance that will extend from infrared wavelengths down to the Far-Ultraviolet (FUV) spectral region. These mirror coatings would be realized by passivating the surface of freshly made aluminum coatings with XeF2 gas in order to form a thin AlF$_3$ overcoat that will protect the aluminum from oxidation and, hence, realize the high-reflectance of this material down to its intrinsic cut-off wavelength of 90 nm. Improved reflective coatings for optics, particularly in the FUV region (90-120 nm), could yield dramatically more sensitive instruments and permit more instrument design freedom.

  8. The Extreme-ultraviolet Emission from Sun-grazing Comets

    Science.gov (United States)

    Bryans, Paul; Pesnell, William D.

    2012-01-01

    The Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory has observed two Sun-grazing comets as they passed through the solar atmosphere. Both passages resulted in a measurable enhancement of extreme-ultraviolet (EUV) radiance in several of the AIA bandpasses.We explain this EUV emission by considering the evolution of the cometary atmosphere as it interacts with the ambient solar atmosphere. Molecules in the comet rapidly sublimate as it approaches the Sun. They are then photodissociated by the solar radiation field to create atomic species. Subsequent ionization of these atoms produces a higher abundance of ions than normally present in the corona and results in EUV emission in the wavelength ranges of the AIA telescope passbands.

  9. 3m vacuum ultraviolet spectrometer with optical multichanel detector

    Energy Technology Data Exchange (ETDEWEB)

    Marin, P.; Peraza, C. [Instituto Investigacion Basica. CIEMAT (Spain); Blanco, F.; Campos, J. [Universidad Complutense de Madrid (Spain). Facultad de Ciencias Fisicas

    1993-08-01

    This paper, describes the design and the performance of a normal incidence vacuum ultraviolet spectrometer, for the 300-2400 A spectral range. It is provided with a multichannel detection system. The monochromator is original design and it has been built at CIEMAT: It is equipped with a 3 m concave holographic grating with 2400 grooves/mm. The multichannel detector consists of a windowless double microchannel plate/phosphor screen image intensifier, coupled by fiber optic to a 1024 elements self-scanning linear photodiode array. The output from the arrays is digitized by a 12-bit analog to digital converter and stored in a computer for its later analysis. The necessary software to store and display data has been developed. (Author)

  10. 3m vacuum ultraviolet spectrometer with optical multichanel detector

    Energy Technology Data Exchange (ETDEWEB)

    Marin, P.; Peraza, C. (Instituto Investigacion Basica. CIEMAT (Spain)); Blanco, F.; Campos, J. (Universidad Complutense de Madrid (Spain). Facultad de Ciencias Fisicas)

    1993-01-01

    This paper, describes the design and the performance of a normal incidence vacuum ultraviolet spectrometer, for the 300-2400 A spectral range. It is provided with a multichannel detection system. The monochromator is original design and it has been built at CIEMAT: It is equipped with a 3 m concave holographic grating with 2400 grooves/mm. The multichannel detector consists of a windowless double microchannel plate/phosphor screen image intensifier, coupled by fiber optic to a 1024 elements self-scanning linear photodiode array. The output from the arrays is digitized by a 12-bit analog to digital converter and stored in a computer for its later analysis. The necessary software to store and display data has been developed. (Author)

  11. Solution processable organic/inorganic hybrid ultraviolet photovoltaic detector

    Directory of Open Access Journals (Sweden)

    Xiaopeng Guo

    2016-05-01

    Full Text Available Ultraviolet (UV photodetector is a kind of important optoelectronic device which can be widely used in scientific and engineering fields including astronomical research, environmental monitoring, forest-fire prevention, medical analysis, and missile approach warning etc. The development of UV detector is hindered by the acquirement of stable p-type materials, which makes it difficult to realize large array, low-power consumption UV focal plane array (FPA detector. Here, we provide a novel structure (Al/Poly(9,9-di-n-octylfuorenyl-2,7-diyl(PFO/ZnO/ITO to demonstrate the UV photovoltaic (PV response. A rather smooth surface (RMS roughness: 0.28 nm may be reached by solution process, which sheds light on the development of large-array, light-weight and low-cost UV FPA detectors.

  12. Ultraviolet radiation effects on pigmentation in the cyanobacterium ``Phormidium uncinatum``

    Energy Technology Data Exchange (ETDEWEB)

    Donkor, V.A.; Haeder, D.P. [Inst. fuer Botanik und Pharmaceutische Biologie, Friedrich-Alexander-Universitaet, Erlangen (Germany)

    1997-12-31

    The Baikal strain of the cyanobacterium Phormidium uncinatum was found to possess the photosynthetic pigments chlorophyll a, carotenoids, phycocyanin and allophycocyanin, while the Tuebingen strain of Phormidium contained, in addition to these, the biliprotein phycoerythrin. Sucrose gradient centrifugation of the pigment extracts resulted in a separation of the phycobiliproteins into several bands, which according to their absorption and fluorescence properties, were identified as monomers, trimers and hexamers. With increasing UV-B irradiation the heavier aggregates were broken down into smaller components. Photobleaching of these accessory pigments also occurred. FPLC gel filtration analyses of the pigments also showed loss of heavier aggregates of the phycobilins and bleaching of the pigments. SDS-polyacrylamide gel electrophoresis of the sucrose gradient and FPLC fractions indicated loss of the biliproteins with increasing UV-B irradiation. The loss of the {beta}- were more rapid than that of the {alpha}- subunits. Increasing levels of ultraviolet irradiation is therefore deleterious to these organism. (author). 41 refs, 7 figs.

  13. Laser plasma formation assisted by ultraviolet pre-ionization

    Energy Technology Data Exchange (ETDEWEB)

    Yalin, Azer P., E-mail: ayalin@engr.colostate.edu; Dumitrache, Ciprian [Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523 (United States); Wilvert, Nick [Sandia Laboratory, Albuquerque, New Mexico 87123 (United States); Joshi, Sachin [Cummins Inc., Columbus, Indiana 47201 (United States); Shneider, Mikhail N. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

    2014-10-15

    We present experimental and modeling studies of air pre-ionization using ultraviolet (UV) laser pulses and its effect on laser breakdown of an overlapped near-infrared (NIR) pulse. Experimental studies are conducted with a 266 nm beam (fourth harmonic of Nd:YAG) for UV pre-ionization and an overlapped 1064 nm NIR beam (fundamental of Nd:YAG), both having pulse duration of ∼10 ns. Results show that the UV beam produces a pre-ionized volume which assists in breakdown of the NIR beam, leading to reduction in NIR breakdown threshold by factor of >2. Numerical modeling is performed to examine the ionization and breakdown of both beams. The modeled breakdown threshold of the NIR, including assist by pre-ionization, is in reasonable agreement with the experimental results.

  14. Tolerance of an albino fish to ultraviolet-B radiation

    Science.gov (United States)

    Fabacher, David L.; Little, Edward E.; Ostrander, Gary K.

    1999-01-01

    We exposed albino and pigmented medakaOryzias latipes to simulated solar ultraviolet-B (UVB) radiation to determine if albino medaka were less tolerant of UVB radiation than medaka pigmented with melanin. There was no difference in the number of albino and pigmented medaka that died during the exposure period. Spectrophotometric analyses of the outer dorsal skin layers from albino and pigmented medaka indicated that, prior to exposure, both groups of fish had similar amounts of an apparent colorless non-melanin photoprotective substance that appears to protect other fish species from UVB radiation. Our results indicate that albino medaka were as tolerant of UVB radiation as pigmented medaka because they had similar amounts of this photoprotective substance in the outer layers of the skin.

  15. An improved outdoor calibration procedure for broadband ultraviolet radiometers.

    Science.gov (United States)

    Cancillo, M L; Serrano, A; Antón, M; García, J A; Vilaplana, J M; de la Morena, B

    2005-01-01

    This article aims at improving the broadband ultraviolet radiometer's calibration methodology. For this goal, three broadband radiometers are calibrated against a spectrophotometer of reference. Three different one-step calibration models are tested: ratio, first order and second order. The latter is proposed in order to adequately reproduce the high dependence on the solar zenith angle shown by the other two models and, therefore, to improve the calibration performance at high solar elevations. The proposed new second-order model requires no additional information and, thus, keeps the operational character of the one-step methodology. The models are compared in terms of their root mean square error and the most qualified is subsequently validated by comparing its predictions with the spectrophotometer measurements within an independent validation data subset. Results show that the best calibration is achieved by the second-order model, with a mean bias error and mean absolute bias error lower than 2.2 and 6.7%, respectively.

  16. Evolution of phytoplankton cultures after ultraviolet light treatment.

    Science.gov (United States)

    Martínez, L F; Mahamud, M M; Lavín, A G; Bueno, J L

    2012-03-01

    Introducing invasive species in new environments through ballast water is a specific problem of contamination and has recently become one of the main concerns of Maritime Organizations. Ultraviolet-C radiation (UV-C) is a technological alternative to prevent this maritime pollution. This study addresses the effect of UV-C on different phytoplankton cultures and also the ability to recover following exposure to damage. A UV-C low-pressure lamp irradiates the cultures. The distance from the source and the thickness of the layer prevent part of the energy from reaching the culture and the disinfective process is diminished. Some cultures such as Chlorella autotrophica and Chaetoceros calcitrans can easily recover from UV-C damage. However, Phaeocystis globosa does not have this ability. C. calcitrans forms cysts and exhibits two different behaviours depending on the dose applied. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Ultraviolet Emission from Oxygen Precipitating into Jovian Aurora

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Weihong; Schultz, D. R.

    2000-02-10

    The ultraviolet emission-line spectra of precipitating oxygen atoms and ions excited by charge transfer interaction with the molecular hydrogen in the auroral atmosphere of Jupiter are calculated using our computed cross sections of state-selective charge transfer. The charge transfer processes preferentially populate the ground states of neutral oxygen and low-charge ions and the highly excited states of high-charge ions, yielding low UV and high X-ray efficiencies, respectively. Much weaker than the underlying emission spectrum of H2 excited by energetic electron precipitation, the UV emission from oxygen is not expected to be discernible in the Jovian auroral spectrum. This reconciles the absence of UV emission with the presence of X-ray emission from the heavy ions precipitating in the Jovian aurora. (c) (c) 2000. The American Astronomical Society.

  18. Extreme ultraviolet mask substrate surface roughness effects on lithography patterning

    Energy Technology Data Exchange (ETDEWEB)

    George, Simi; Naulleau, Patrick; Salmassi, Farhad; Mochi, Iacopo; Gullikson, Eric; Goldberg, Kenneth; Anderson, Erik

    2010-06-21

    In extreme ultraviolet lithography exposure systems, mask substrate roughness induced scatter contributes to LER at the image plane. In this paper, the impact of mask substrate roughness on image plane speckle is explicitly evaluated. A programmed roughness mask was used to study the correlation between mask roughness metrics and wafer plane aerial image inspection. We find that the roughness measurements by top surface topography profile do not provide complete information on the scatter related speckle that leads to LER at the image plane. We suggest at wavelength characterization by imaging and/or scatter measurements into different frequencies as an alternative for a more comprehensive metrology of the mask substrate/multilayer roughness effects.

  19. Standoff ultraviolet raman scattering detection of trace levels of explosives.

    Energy Technology Data Exchange (ETDEWEB)

    Kulp, Thomas J.; Bisson, Scott E.; Reichardt, Thomas A.

    2011-10-01

    Ultraviolet (UV) Raman scattering with a 244-nm laser is evaluated for standoff detection of explosive compounds. The measured Raman scattering albedo is incorporated into a performance model that focused on standoff detection of trace levels of explosives. This model shows that detection at {approx}100 m would likely require tens of seconds, discouraging application at such ranges, and prohibiting search-mode detection, while leaving open the possibility of short-range point-and-stare detection. UV Raman spectra are also acquired for a number of anticipated background surfaces: tile, concrete, aluminum, cloth, and two different car paints (black and silver). While these spectra contained features in the same spectral range as those for TNT, we do not observe any spectra similar to that of TNT.

  20. Skin Pigmentation Kinetics after Exposure to Ultraviolet A

    DEFF Research Database (Denmark)

    Ravnbak, M.H.; Philipsen, P.A.; Wiegell, S.R.

    2009-01-01

    Scandinavians and 12 Indians/Pakistanis after 6 and 12 exposures on the back using broadband UVA and UVA1 with equal sub-minimal melanogenic doses (individually predetermined). Pigmentation was measured by skin reflectance at 555 and 660 urn. The UV dose to minimal pigmentation was higher in dark......Multiple exposures to ultraviolet radiation (UVR) are the norm in nature and phototherapy. However, studies of the kinetics of pigmentation following UVA exposure have included only fair-skinned persons. The aim of this study was to investigate steady-state pigmentation and fading in 12......-fold, respectively. The absolute increase in pigmentation was independent of pre-exposure pigmentation; therefore the percentage increase in pigmentation was higher in fair-skinned subjects. The absolute increase in pigmentation was higher and it took 2-3 days longer to reach steady-state after 12 UV exposures...

  1. Effects of sunscreen on human skin's ultraviolet radiation tolerance.

    Science.gov (United States)

    Yuan, Chao; Wang, Xue-min; Tan, Yi-mei; Yang, Li-jie; Lin, Yin-fen; Wu, Pei-lan

    2010-12-01

    To observe the alteration ultraviolet radiation (UVR) of skin's tolerance after its exposure to the small dose of UVR under the protection of sunscreen. Eleven subjects who applied sunscreen were exposed to 0.75 dose minimal persistent pigment darkening (MPPD) and minimal erythema dose (MED) by the Phototherapy Unit for 4 weeks. Each week their MPPDs and MEDs were measured by solar simulator. Meanwhile, SPECTCOLOMETER® and VISIOSCAN VC98® were used to detect the test areas and control areas. The values of MPPD and MED increased significantly after the exposure to UVR. But there were no visible changes on the surface of skin's texture. With the protection of sunscreen, the UVR tolerance of skin was greatly increased after the skin's exposure to the small dose UV. © 2010 Wiley Periodicals, Inc.

  2. Curvature-Restored Gauge Invariance and Ultraviolet Naturalness

    Directory of Open Access Journals (Sweden)

    Durmuş Ali Demir

    2016-01-01

    Full Text Available It is shown that (aΛ2+b|H|2R in a spacetime of curvature R is a natural ultraviolet (UV completion of (aΛ4+bΛ2|H|2 in the flat-spacetime Standard Model (SM with Higgs field H, UV scale Λ, and loop factors a and b. This curvature completion rests on the fact that Λ-mass gauge theory in flat spacetime turns, on the cut view R=4Λ2, into a massless gauge theory in curved spacetime. It provides a symmetry reason for curved spacetime, wherein gravity and matter are both low-energy effective phenomena. Gravity arises correctly if new physics exists with at least 63 more bosons than fermions, with no need to interact with the SM and with dark matter as a natural harbinger. It can source various cosmological, astrophysical, and collider phenomena depending on its spectrum and couplings to the SM.

  3. Effective ultraviolet irradiation of platelet concentrates in teflon bags

    Energy Technology Data Exchange (ETDEWEB)

    Capon, S.M.; Sacher, R.A.; Deeg, H.J. (Georgetown Univ., Washington, DC (USA))

    1990-10-01

    Several plastic materials used in blood storage were evaluated for their ability to transmit ultraviolet B (UVB) light. A plastic bag manufactured from sheets of transparent Teflon efficiently (78-86%) transmitted UVB light and was employed in subsequent functional studies of lymphocytes and platelets exposed to UVB light while contained in these bags. In vitro experiments showed a UVB dose-dependent abrogation of lymphocyte responder and stimulator functions, with concurrent preservation of platelet aggregation responses. In a phase I pilot study, UVB-treated platelet concentrates were administered to four bone marrow transplant recipients. Adverse effects attributable to the transfusions were not observed, and patients showed clinically effective transfusion responses. No patient developed lymphocytotoxic HLA or platelet antibodies. These studies suggest that platelets can be effectively irradiated with UVB light in a closed system. However, numerous variables, including container material, volume and composition of contents, steady exposure versus agitation, and exact UV wavelength, must be considered.

  4. Wide-Field Ultraviolet Spectrometer for Planetary Exospheres and Thermospheres

    Science.gov (United States)

    Fillingim, M. O.; Wishnow, E. H.; Miller, T.; Edelstein, J.; Lillis, R. J.; Korpela, E.; England, S.; Shourt, W. V.; Siegmund, O.; McPhate, J.; Courtade, S.; Curtis, D. W.; Deighan, J.; Chaffin, M.; Harmoul, A.; Almatroushi, H. R.

    2016-12-01

    Understanding the composition, structure, and variability of a planet's upper atmosphere - the exosphere and thermosphere - is essential for understanding how the upper atmosphere is coupled to the lower atmosphere, magnetosphere and near-space environment, and the Sun. Ultraviolet spectroscopy can directly observe emissions from constituents in the exosphere and thermosphere. From such observations, the structure, composition, and variability can be determined.We will present the preliminary design for a wide field ultraviolet imaging spectrometer for remote sensing of planetary atmospheres. The imaging spectrometer achieves an extremely large instantaneous 110 degree field of view with no moving scanning mirror. The imaging resolution is very appropriate for extended atmospheric emission studies, with a resolution of better than 0.3 degrees at the center to 0.4 degrees at the edges of the field. The spectral range covers 120 - 170 nm, encompassing emissions from H, O, C, N, CO, and N2, with an average spectral resolution of 1.5 nm. The instrument is composed of a 2-element wide-field telescope, a 3-element Offner spectrometer, and a sealed MCP detector system contained within a compact volume of about 40 x 25 x 20 cm. We will present the optical and mechanical design as well as the predicted optical performance.The wide instantaneous FOV simplifies instrument and spacecraft operations by removing the need for multiple scans (either from a scan mirror or spacecraft slews) to cover the regions of interest. This instrumentation can allow for two-dimensional spectral information to be built up with simple spacecraft operation or just using spacecraft motion. Applications to the terrestrial geocorona and thermosphere will be addressed as well as applications to the upper atmospheres of other planetary objects.

  5. Outdoor Exposure to Solar Ultraviolet Radiation and Legislation in Brazil.

    Science.gov (United States)

    Silva, Abel A

    2016-06-01

    The total ozone column of 265 ± 11 Dobson Units in the tropical-equatorial zones and 283 ± 16 Dobson Units in the subtropics of Brazil are among the lowest on Earth, and as a result, the prevalence of skin cancer due to solar ultraviolet radiation is among the highest. Daily erythemal doses in Brazil can be over 7,500 J m. Erythemal dose rates on cloudless days of winter and summer are typically about 0.147 W m and 0.332 W m, respectively. However, radiation enhancement events yielded by clouds have been reported with erythemal dose rates of 0.486 W m. Daily doses of the diffuse component of erythemal radiation have been determined with values of 5,053 J m and diffuse erythemal dose rates of 0.312 W m. Unfortunately, Brazilians still behave in ways that lead to overexposure to the sun. The annual personal ultraviolet radiation ambient dose among Brazilian youths can be about 5.3%. Skin cancer in Brazil is prevalent, with annual rates of 31.6% (non-melanoma) and 1.0% (melanoma). Governmental and non-governmental initiatives have been taken to increase public awareness of photoprotection behaviors. Resolution #56 by the Agência Nacional de Vigilância Sanitária has banned tanning devices in Brazil. In addition, Projects of Law (PL), like PL 3730/2004, propose that the Sistema Único de Saúde should distribute sunscreen to members of the public, while PL 4027/2012 proposes that employers should provide outdoor workers with sunscreen during professional outdoor activities. Similar laws have already been passed in some municipalities. These are presented and discussed in this study.

  6. Extreme ultraviolet high-harmonic spectroscopy of solids.

    Science.gov (United States)

    Luu, T T; Garg, M; Kruchinin, S Yu; Moulet, A; Hassan, M Th; Goulielmakis, E

    2015-05-28

    Extreme ultraviolet (EUV) high-harmonic radiation emerging from laser-driven atoms, molecules or plasmas underlies powerful attosecond spectroscopy techniques and provides insight into fundamental structural and dynamic properties of matter. The advancement of these spectroscopy techniques to study strong-field electron dynamics in condensed matter calls for the generation and manipulation of EUV radiation in bulk solids, but this capability has remained beyond the reach of optical sciences. Recent experiments and theoretical predictions paved the way to strong-field physics in solids by demonstrating the generation and optical control of deep ultraviolet radiation in bulk semiconductors, driven by femtosecond mid-infrared fields or the coherent up-conversion of terahertz fields to multi-octave spectra in the mid-infrared and optical frequencies. Here we demonstrate that thin films of SiO2 exposed to intense, few-cycle to sub-cycle pulses give rise to wideband coherent EUV radiation extending in energy to about 40 electronvolts. Our study indicates the association of the emitted EUV radiation with intraband currents of multi-petahertz frequency, induced in the lowest conduction band of SiO2. To demonstrate the applicability of high-harmonic spectroscopy to solids, we exploit the EUV spectra to gain access to fine details of the energy dispersion profile of the conduction band that are as yet inaccessible by photoemission spectroscopy in wide-bandgap dielectrics. In addition, we use the EUV spectra to trace the attosecond control of the intraband electron motion induced by synthesized optical transients. Our work advances lightwave electronics in condensed matter into the realm of multi-petahertz frequencies and their attosecond control, and marks the advent of solid-state EUV photonics.

  7. Far-ultraviolet observation of the globular cluster NGC 6397

    Science.gov (United States)

    Dieball, A.; Rasekh, A.; Knigge, C.; Shara, M.; Zurek, D.

    2017-07-01

    We present an observational far-ultraviolet (FUV) and near-ultraviolet (NUV) study of the core region of the globular cluster (GC) NGC 6397. The observations were obtained with the Space Telescope Imaging Spectrograph (STIS, FUV) and the Wide Field Camera 3 (NUV) on board the Hubble Space Telescope. Here, we focus on the UV-bright stellar populations such as blue stragglers (BSs), white dwarfs (WDs) and cataclysmic variables (CVs). We present the first FUV - NUV colour-magnitude diagram (CMD) for this cluster. To support our classification of the stellar populations, we compare our FUV - NUV CMD with optical data from the ACS Survey of Galactic Globular Clusters. The FUV - NUV CMD indicates 16 sources located in the WD area, and 10 BSs within the 25 × 25 arcsec2 of the STIS FUV data. 18 Chandra X-ray sources are located within the FUV field of view. 13 of those have an NUV counterpart, of which 9 sources also have an FUV counterpart. Out of those, five sources are previously suggested CVs, and indeed, all five are located in the WD/CV region in our FUV - NUV CMD. Another CV has only an FUV but no NUV counterpart. We also detect an NUV (but no FUV) counterpart to the millisecond pulsar (MSP) located in the core of this cluster. The NUV light curves of the CVs and MSP show flickering behaviour typical of CVs. We found that the BSs and CVs are the most centrally concentrated populations. This might be an effect of mass segregation or it might indicate the preferred birth place of BSs and CVs via dynamical interactions in the dense core region of GCs. Horizontal branch stars are the least centrally concentrated population and absent in the innermost area of the core.

  8. Summary of Quantitative Interpretation of Image Far Ultraviolet Auroral Data

    Science.gov (United States)

    Frey, H. U.; Immel, T. J.; Mende, S. B.; Gerard, J.-C.; Hubert, B.; Habraken, S.; Span, J.; Gladstone, G. R.; Bisikalo, D. V.; Shematovich, V. I.; hide

    2002-01-01

    Direct imaging of the magnetosphere by instruments on the IMAGE spacecraft is supplemented by simultaneous observations of the global aurora in three far ultraviolet (FUV) wavelength bands. The purpose of the multi-wavelength imaging is to study the global auroral particle and energy input from thc magnetosphere into the atmosphere. This paper describes provides the method for quantitative interpretation of FUV measurements. The Wide-Band Imaging Camera (WIC) provides broad band ultraviolet images of the aurora with maximum spatial and temporal resolution by imaging the nitrogen lines and bands between 140 and 180 nm wavelength. The Spectrographic Imager (SI), a dual wavelength monochromatic instrument, images both Doppler-shifted Lyman alpha emissions produced by precipitating protons, in the SI-12 channel and OI 135.6 nm emissions in the SI-13 channel. From the SI-12 Doppler shifted Lyman alpha images it is possible to obtain the precipitating proton flux provided assumptions are made regarding the mean energy of the protons. Knowledge of the proton (flux and energy) component allows the calculation of the contribution produced by protons in the WIC and SI-13 instruments. Comparison of the corrected WIC and SI-13 signals provides a measure of the electron mean energy, which can then be used to determine the electron energy fluxun-. To accomplish this reliable modeling emission modeling and instrument calibrations are required. In-flight calibration using early-type stars was used to validate the pre-flight laboratory calibrations and determine long-term trends in sensitivity. In general, very reasonable agreement is found between in-situ measurements and remote quantitative determinations.

  9. Ultraviolet light exposure, skin cancer risk and vitamin D production

    Science.gov (United States)

    RIVAS, MIGUEL; ROJAS, ELISA; ARAYA, MARÍA C.; CALAF, GLORIA M.

    2015-01-01

    The danger of overexposure to solar ultraviolet radiation has been widely reviewed since the 1980s due to the depletion of the ozone layer. However, the benefits of mild exposure of the skin to ultraviolet (UV) light have not been widely investigated. Numerous reports have demonstrated that an association exists between low light exposure to the sun, non-melanoma skin cancer and a lack of vitamin D synthesis. As vitamin D synthesis in the body depends on skin exposure to UVB radiation from the sun (wavelength, 290–320 nm), experimental measurements for this type of solar radiation are important. The present study analyzed data obtained from a laboratory investigating UV radiation from the sun at the University of Tarapacá (Arica, Chile), where systematic experimental UVB measurements had been performed using a calibrated biometer instrument since 2006. These data were compared with skin cancer data from the local population. The results demonstrated that the incidence of skin cancer systematically increased from 7.4 to 18.7 in men and from 10.0 to 21.7 in women between 2000 and 2006 in Arica, respectively; this increase may be due to multiple factors, including the lack of adequate levels of vitamin D in risk groups such as post-menopausal women and senior age. This marked increase may also be due to the high levels of UV radiation measured in this region throughout the year. However, it is not certain that the local population has adequate vitamin D levels, nor that their skin has been predominantly exposed to artificial light that does not allow adequate vitamin D synthesis. Thus, the current study presents the association between skin type IV, the time to induce solar erythema and the time required to produce 1,000 international units of vitamin D. PMID:26622830

  10. LEMUR: Large European Module for Solar Ultraviolet Research

    Science.gov (United States)

    Teriaca, Luca; Vincenzo, Andretta; Auchere, Frederic; Brown, Charles M.; Buchlin, Eric; Cauzzi, Gianna; Culhane, J. Len; Curdt, Werner; Davila, Joseph M.; Del Zanna, Giulio; hide

    2012-01-01

    The solar outer atmosphere is an extremely dynamic environment characterized by the continuous interplay between the plasma and the magnetic field that generates and permeates it. Such interactions play a fundamental role in hugely diverse astrophysical systems, but occur at scales that cannot be studied outside the solar system. Understanding this complex system requires concerted, simultaneous solar observations from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at high spatial resolution (between 0.1'' and 0.3''), at high temporal resolution (on the order of 10 s, i.e., the time scale of chromospheric dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the chromosphere to the flaring corona), and the capability of measuring magnetic fields through spectropolarimetry at visible and near-infrared wavelengths. Simultaneous spectroscopic measurements sampling the entire temperature range are particularly important. These requirements are fulfilled by the Japanese Solar-C mission (Plan B), composed of a spacecraft in a geosynchronous orbit with a payload providing a significant improvement of imaging and spectropolarimetric capabilities in the UV, visible, and near-infrared with respect to what is available today and foreseen in the near future. The Large European Module for solar Ultraviolet Research (LEMUR), described in this paper, is a large VUV telescope feeding a scientific payload of high-resolution imaging spectrographs and cameras. LEMUR consists of two major components: a VUV solar telescope with a 30 cm diameter mirror and a focal length of 3.6 m, and a focal-plane package composed of VUV spectrometers covering six carefully chosen wavelength ranges between 170 Angstrom and 1270 Angstrom. The LEMUR slit covers 280'' on the Sun with 0.14'' per pixel sampling. In addition, LEMUR is capable of measuring mass flows velocities (line shifts) down to 2 km s - 1 or better. LEMUR has been proposed to ESA as the European contribution

  11. Mass transfer ways of ultraviolet printing ink ingredients into foodstuffs.

    Science.gov (United States)

    Jung, T; Simat, T J; Altkofer, W

    2010-07-01

    The case of isopropylthioxanthone (ITX) showed conclusively that the ingredients of ultraviolet printing inks may migrate into packaged foodstuffs. For multilayered materials like beverage cartons, the only way that mass transfer can occur is by the so-called set-off effect. In contrast, in the case of rigid plastics like yoghurt cups, two other methods of mass transfer, permeation and gas phase, have to be considered. In cooperation with producers of ink, plastic cups and yoghurt, a project was conducted in order to elucidate the mass transfer of ink ingredients. In addition, the influence of storage time and the age of ultraviolet lamps on the migration level was examined. The suitability of 50% ethanol as a simulant for yoghurt was also tested. ITX was chosen as a model migrant, as it is easily detectable. Furthermore, the migration of two other substances, the photo-initiator 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (MTMP) and the amine synergist ethyl-4-(dimethylamino)benzoate (EDAB), which may be used in combination with ITX, was studied. Before being filled with yoghurt or 50% ethanol, the printed cups were stored under different contact conditions, with and without contact between the inner layer and the printed surfaces, in order to distinguish between the possible mass transfer ways. All analyses were performed by means of high performance liquid chromatography with diode array and fluorescence detection (HPLC-DAD/FLD). It was shown that contamination with ITX and EDAB occurs via set-off and that the degree of migration increases with lamp age and storage time of the unfilled cups. Migration of MTMP was not detectable. The results show that besides the careful selection of the appropriate raw materials for printing ink, a close monitoring of the process also plays a major role in migration control. In addition, the results proved that 50% ethanol is a suitable simulant for yoghurt.

  12. Far Ultraviolet Spectroscopy of Saturn's Icy Moon Rhea

    Science.gov (United States)

    Elowitz, Mark; Hendrix, Amanda; Mason, Nigel J.; Sivaraman, Bhalamurugan

    2018-01-01

    We present an analysis of spatially resolved, far-UV reflectance spectra of Saturn’s icy satellite Rhea, collected by the Cassini Ultraviolet Imaging Spectrograph (UVIS). In recent years ultraviolet spectroscopy has become an important tool for analysing the icy satellites of the outer solar system (1Hendrix & Hansen, 2008). Far-UV spectroscopy provides unique information about the molecular structure and electronic transitions of chemical species. Many molecules that are suspected to be present in the icy surfaces of moons in the outer solar system have broad absorption features due to electronic transitions that occur in the far-UV portion of the spectrum. The studies show that Rhea, like the other icy satellites of the Saturnian system are dominated by water-ice as evident by the 165-nm absorption edge, with minor UV absorbing contaminants. Far-UV spectra of several Saturnian icy satellites, including Rhea and Dione, show an unexplained weak absorption feature centered near 184 nm. To carry out the geochemical survey of Rhea’s surface, the UVIS observations are compared with vacuum-UV spectra of thin-ice samples measured in laboratory experiments. Thin film laboratory spectra of water-ice and other molecular compounds in the solid phase were collected at near-vacuum conditions and temperatures identical to those at the surface of Rhea. Comparison between the observed far-UV spectra of Rhea’s surface ice and modelled spectra based on laboratory absorption measurements of different non-water-ice compounds show that two possible chemical compounds could explain the 184-nm absorption feature. The two molecular compounds include simple chlorine molecules and hydrazine monohydrate. Attempts to explain the source(s) of these compounds on Rhea and the scientific implications of their possible discovery will be summarized.[1] Hendrix, A. R. & Hansen, C. J. (2008). Icarus, 193, pp. 323-333.

  13. Ultraviolet damage to the eye revisited: eye-sun protection factor (E-SPF®), a new ultraviolet protection label for eyewear

    Science.gov (United States)

    Behar-Cohen, Francine; Baillet, Gilles; de Ayguavives, Tito; Garcia, Paula Ortega; Krutmann, Jean; Peña-García, Pablo; Reme, Charlotte; Wolffsohn, James S

    2014-01-01

    Ultraviolet (UV) radiation potentially damages the skin, the immune system, and structures of the eye. A useful UV sun protection for the skin has been established. Since a remarkable body of evidence shows an association between UV radiation and damage to structures of the eye, eye protection is important, but a reliable and practical tool to assess and compare the UV-protective properties of lenses has been lacking. Among the general lay public, misconceptions on eye-sun protection have been identified. For example, sun protection is mainly ascribed to sunglasses, but less so to clear lenses. Skin malignancies in the periorbital region are frequent, but usual topical skin protection does not include the lids. Recent research utilized exact dosimetry and demonstrated relevant differences in UV burden to the eye and skin at a given ambient irradiation. Chronic UV effects on the cornea and lens are cumulative, so effective UV protection of the eyes is important for all age groups and should be used systematically. Protection of children’s eyes is especially important, because UV transmittance is higher at a very young age, allowing higher levels of UV radiation to reach the crystalline lens and even the retina. Sunglasses as well as clear lenses (plano and prescription) effectively reduce transmittance of UV radiation. However, an important share of the UV burden to the eye is explained by back reflection of radiation from lenses to the eye. UV radiation incident from an angle of 135°–150° behind a lens wearer is reflected from the back side of lenses. The usual antireflective coatings considerably increase reflection of UV radiation. To provide reliable labeling of the protective potential of lenses, an eye-sun protection factor (E-SPF®) has been developed. It integrates UV transmission as well as UV reflectance of lenses. The E-SPF® compares well with established skin-sun protection factors and provides clear messages to eye health care providers and to

  14. Ultraviolet B decreases DNA methylation level of CD4+ T cells in patients with systemic lupus erythematosus.

    Science.gov (United States)

    Zhang, Min; Fang, Xuan; Wang, Guo-Sheng; Ma, Yan; Jin, Li; Li, Xiao-Mei; Li, Xiang-Pei

    2017-04-01

    In the present study, DNA methylation level of CD4+ T cells exposed to ultraviolet B (UVB) was investigated and its potential mechanisms were also explored. CD4+ T cells from 12 cases of healthy subjects and 33 cases of SLE patients were isolated and exposed to different dosages (0, 50, 100 mJ/cm2) of UVB. Further, SLE patients were divided into two groups: active SLE group (22 cases, SLEDAI scores >4) and inactive SLE group (11 cases, SLEDAI scores ≤4). DNA methylation was evaluated by the Methylamp™ Global DNA Methylation Quantification Ultra Kit. The mRNA and protein expression levels of DNA methyltransferases (DNMT1 and DNMT3A) were detected by real-time PCR and western blot, respectively. The levels of DNA methylation and DNMT3A mRNA in SLE patients were significantly decreased compared with those in healthy subjects at baseline. After different dosages of ultraviolet irradiation (0, 50 and 100 mJ/cm2), DNA methylation levels of CD4+ T cells were all reduced in a dose-dependent manner in three subgroups. Additionally, 100 mJ/cm2 ultraviolet irradiation in active SLE group contributed to a significant decrease of both DNA methylation and DNMT3A mRNA levels in CD4+ T cells. UVB exposure had no significant effects on expression levels of DNMT1 mRNA and protein and DNMT3A protein. UVB decreases DNA methylation level of CD4+ T cells in SLE patients probably via inhibiting DNMT3A mRNA expression level, which needs to be further explored.

  15. PREDICTING Lyα AND Mg II FLUXES FROM K AND M DWARFS USING GALAXY EVOLUTION EXPLORER ULTRAVIOLET PHOTOMETRY

    Energy Technology Data Exchange (ETDEWEB)

    Shkolnik, Evgenya L.; Rolph, Kristina A. [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Peacock, Sarah; Barman, Travis S., E-mail: shkolnik@lowell.edu, E-mail: kristina.rolph@fandm.edu, E-mail: speacock@lpl.arizona.edu, E-mail: barman@lpl.arizona.edu [Department of Planetary Sciences and Lunar and Planetary Laboratory University of Arizona, Tucson AZ 85721 (United States)

    2014-11-20

    A star's ultraviolet (UV) emission can greatly affect the atmospheric chemistry and physical properties of closely orbiting planets with the potential for severe mass loss. In particular, the Lyα emission line at 1216 Å, which dominates the far-ultraviolet (FUV) spectrum, is a major source of photodissociation of important atmospheric molecules such as water and methane. The intrinsic flux of Lyα, however, cannot be directly measured due to the absorption of neutral hydrogen in the interstellar medium and contamination by geocoronal emission. To date, reconstruction of the intrinsic Lyα line based on Hubble Space Telescope spectra has been accomplished for 46 FGKM nearby stars, 28 of which have also been observed by the Galaxy Evolution Explorer (GALEX). Our investigation provides a correlation between published intrinsic Lyα and GALEX far- and near-ultraviolet (NUV) chromospheric fluxes for K and M stars. The negative correlations between the ratio of the Lyα to the GALEX fluxes reveal how the relative strength of Lyα compared to the broadband fluxes weakens as the FUV and NUV excess flux increase. We also correlate GALEX fluxes with the strong NUV Mg II h+k spectral emission lines formed at lower chromospheric temperatures than Lyα. The reported correlations provide estimates of intrinsic Lyα and Mg II fluxes for the thousands of K and M stars in the archived GALEX all-sky surveys. These will constrain new stellar upper atmosphere models for cool stars and provide realistic inputs to models describing exoplanetary photochemistry and atmospheric evolution in the absence of UV spectroscopy.

  16. A Powerful Mitochondria-Targeted Iron Chelator Affords High Photoprotection against Solar Ultraviolet A Radiation.

    Science.gov (United States)

    Reelfs, Olivier; Abbate, Vincenzo; Hider, Robert C; Pourzand, Charareh

    2016-08-01

    Mitochondria are the principal destination for labile iron, making these organelles particularly susceptible to oxidative damage on exposure to ultraviolet A (UVA, 320-400 nm), the oxidizing component of sunlight. The labile iron-mediated oxidative damage caused by UVA to mitochondria leads to necrotic cell death via adenosine triphosphate depletion. Therefore, targeted removal of mitochondrial labile iron via highly specific tools from these organelles may be an effective approach to protect the skin cells against the harmful effects of UVA. In this work, we designed a mitochondria-targeted hexadentate (tricatechol-based) iron chelator linked to mitochondria-homing SS-like peptides. The photoprotective potential of this compound against UVA-induced oxidative damage and cell death was evaluated in cultured primary skin fibroblasts. Our results show that this compound provides unprecedented protection against UVA-induced mitochondrial damage, adenosine triphosphate depletion, and the ensuing necrotic cell death in skin fibroblasts, and this effect is fully related to its potent iron-chelating property in the organelle. This mitochondria-targeted iron chelator has therefore promising potential for skin photoprotection against the deleterious effects of the UVA component of sunlight. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  17. Ratio images and ultraviolet C excitation in autofluorescence imaging of neoplasms of the human colon

    Science.gov (United States)

    Renkoski, Timothy E.; Banerjee, Bhaskar; Graves, Logan R.; Rial, Nathaniel S.; Reid, Sirandon A. H.; Tsikitis, Vassiliki Liana; Nfonsam, Valentine N.; Tiwari, Piyush; Gavini, Hemanth; Utzinger, Urs

    2013-01-01

    The accepted screening technique for colon cancer is white light endoscopy. While most abnormal growths (lesions) are detected by this method, a significant number are missed during colonoscopy, potentially resulting in advanced disease. Missed lesions are often flat and inconspicuous in color. A prototype ultraviolet spectral imager measuring autofluorescence (AF) and reflectance has been developed and applied in a study of 21 fresh human colon surgical specimens. Six excitation wavelengths from 280 to 440 nm and formulaic ratio imaging were utilized to increase lesion contrast and cause neoplasms to appear bright compared to normal tissue. It was found that in the subset of lesions which were most difficult to visualize in standard color photographs [low contrast lesions, (LCLs)] a ratio image (F340/F440) of AF images excited at 340 and 440 nm produced extraordinary images and was effective in about 70% of these difficult cases. Contrast may be due to increased levels of reduced nicotinamide adenine dinucleotide, increased hemoglobin absorption, and reduced signal from submucosal collagen. A second successful ratio image (R480/R555) combined two reflectance images to produce exceptional images especially in particular LCLs where F340/F440 was ineffective. The newly discovered ratio images can potentially improve detection rate in screening with a novel AF colonoscope.

  18. Effect of tumor promoters on ultraviolet light-induced mutation and mitotic recombination in Saccharomyces cerevisiae.

    Science.gov (United States)

    Kunz, B A; Hannan, M A; Haynes, R H

    1980-07-01

    Recently, it has been suggested that mitotic recombination is involved in tumor promotion. On this basis, one might expect tumor promoters to be recombinagenic. D7 is a diploid strain of yeast in which both mutation and mitotic recombination can be measured. We have used this strain to assay the known tumor promoters, iodoacetate, anthralin, and 12-O-tetradecanoylphorbol-13-acetate, and the cocarcinogen, catechol, for mutagenicity, recombinagenicity, and the ability to enhance ultraviolet light (UV)-induced genetic events. In the absence of preirradiation with UV, iodoacetate was found to be recombinagenic whereas catechol was mutagenic; however, in both cases, the effects were small. Iodoacetate, anthralin, and catechol potentiated UV-induced mitotic crossing-over, aberrant colony formation, and mutation, while catechol also increased UV-induced gene conversion. We were unable to detect any mutagenic or recombinagenic effect of 12-O-tetradecanoyl-phorbol-13-acetate in either whole cells or spheroplasts. Our results do not indicate any consistent correlation between tumor-promoting activity and the ability of an agent to induce mitotic recombination in yeast. However, the ability to potentiate UV-induced mutation and mitotic recombination may reflect the cocarcinogenic activity of certain promoters.

  19. Need for a well-balanced sunscreen to protect human skin from both Ultraviolet A and Ultraviolet B damage

    Directory of Open Access Journals (Sweden)

    Dominique Moyal

    2012-01-01

    Full Text Available Skin exposure to sunlight can cause many adverse effects. It is now recognized that both Ultraviolet A (UVA and UVB wavelengths are responsible for the detrimental effects of solar radiation on skin. With our increasing knowledge on the harmful effects of UVA, the need for effective, well-balanced photoprotection has become more crucial. Numerous clinical studies showed that well-balanced sunscreen, with a SPF/UVAPF ratio ≤ 3, provide the most effective protection against pigmentation (especially on dark skin, DNA damage, UV-induced skin immunosuppression and photodermatoses. The calculation of UVA protection required in Asia revealed its particular importance in India, and gives clear evidence that the SPF value alone is not sufficient to evaluate the efficacy of a sunscreen.

  20. Demonstration test and evaluation of ultraviolet/ultraviolet catalyzed peroxide oxidation for groundwater remediation at Oak Ridge K-25 Site

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-12-31

    In the UItraviolet/Ultraviolet Catalyzed Groundwater Remediation program, W.J. Schafer Associates, Inc. (WJSA) demonstrated, tested and evaluated a new ultraviolet (UV) lamp integrated with an existing commercial technology employing UV catalyzed peroxide oxidation to destroy organics in groundwater at an Oak Ridge K-25 site. The existing commercial technology is the perox-pure{trademark} process of Peroxidation Systems Incorporated (PSI) that employs standard UV lamp technology to catalyze H{sub 2}O{sub 2} into OH radicals, which attack many organic molecules. In comparison to classical technologies for remediation of groundwater contaminated with organics, the perox-pure{trademark} process not only is cost effective but also reduces contaminants to harmless by-products instead of transferring the contaminants from one medium to another (such as in activated carbon or air stripping). Although the perox-pure{trademark} process is cost effective against many organics, it is not effective for some organic contaminants of interest to DOE such as TCA, which has the highest concentration of the organics at the K-25 test site. Contaminants such as TCA are treated more readily by direct photolysis using short wavelength UV light. WJSA has been developing a unique UV lamp which is very efficient in the short UV wavelength region. Consequently, combining this UV lamp with the perox-pure{trademark} process results in a means for treating essentially all organic contaminants. In the program reported here, the new UV lamp lifetime was improved and the lamp integrated into a PSI demonstration trailer. Even though this UV lamp operated at less than optimum power and UV efficiency, the destruction rate for the TCA was more than double that of the commercial unit. An optimized UV lamp may double again the destruction rate; i.e., a factor of four greater than the commercial system.

  1. Aluminium nitrate ceramics: A potential UV dosemeter material

    DEFF Research Database (Denmark)

    Trinkler, L.; Bøtter-Jensen, L.; Berzina, B.

    2002-01-01

    The ceramic material AIN-Y2O3 is proposed as a potential ultraviolet radiation (UVR) dosemeter using optically stimulated luminescence (OSL) and thermally stimulated luminescence (TL). Experimental studies have shown that AIN ceramics exhibit attractive characteristics suitable for practical UV d...

  2. Waste to wealth: Industrial raw materials potential of peels of ...

    African Journals Online (AJOL)

    Waste to wealth: Industrial raw materials potential of peels of Nigerian sweet orange ( Citrus sinensis. ... Ultraviolet-visible spectrophotometric scan of the extract, revealed a single prominent peak at a wavelength of 300 nm, as was also the case with paper chromatography which showed one major band separation.

  3. UV-irradiation enhances rice allelopathic potential in rhizosphere soil

    DEFF Research Database (Denmark)

    Mahmood, Khalid; Khan, Muhammad Bismillah; Song, Yuan Yuan

    2013-01-01

    Ultraviolet-B radiation is rising continuously due to stratospheric ozone depletion over temperate latitudes. This study investigated effects of UV exposure on rice allelopathic potentials. For this purpose, two rice (Oryza sativa L.) cultivars BR-41 (high allelopathic = able to inhibit neighbori...

  4. Evaluation of Sclerotinia sclerotiorum as a potential mycotoxin producer on soybeans.

    Science.gov (United States)

    Ciegler, A; Burbridge, K A; Ciegler, J; Hesseltine, C W

    1978-01-01

    Solvent extracts of Sclerotinia sclerotiorum sclerotia were nontoxic to mice and chicken embryos; psoralens were not detected. Solvent extracts of soybeans inoculated with 10 strains of S. sclerotiorum were toxic on injection but nontoxic on per os administration to mice. The presence of chlorinated hydrocarbons in the soybeans may partially help explain toxicity by intraperitineal injection. PMID:569464

  5. Effect of open ultraviolet germicidal irradiation lamps on functionality of excimer lasers used in cornea surgery.

    Science.gov (United States)

    Belovickis, Jaroslavas; Kurylenka, Aliaksei; Murashko, Vadim

    2017-01-01

    We report on the impact of direct ultraviolet germicidal irradiation (UVGI) on reflective optics, used in the excimer laser system Allegretto Eye-Q. The aim of our work was to confirm our hypothesis based on long-rate observations of obtained anomalies in post-operative results that are attributed to degradation of reflective optics upon ultraviolet radiation. The presence of direct UVGI coupled with humidity in the operating environment caused merging anomalies and unwanted post-operative correction values. Ultraviolet-A radiation caused a similar effect on the reflective cover of the mirrors.

  6. Simultaneous Removal of MTBE and Benzene from Contaminated Groundwater Using Ultraviolet-Based Ozone and Hydrogen Peroxide

    Directory of Open Access Journals (Sweden)

    Bassam S. Tawabini

    2014-01-01

    Full Text Available Efficiency of ultraviolet-ozone (UV/O3 and ultraviolet-hydrogen peroxide (UV/H2O2 processes was investigated for simultaneous removal of methyl tertiary butyl ether (MTBE and benzene from contaminated ground water. The photoreactor employed housed 15-watt low pressure (LP and 150-watt medium pressure (MP mercury UV lamps. Oxidation of contaminants was studied at two different levels of ozone and hydrogen peroxide. Brackish groundwater samples were spiked with MTBE and benzene up to a concentration of 500 μg L−1. Removal potential was evaluated at different parameters such as UV type and intensity and peroxide and ozone dosages, as well as contact time. Results indicated that no removal of the contaminants was attained when treated with hydrogen peroxide or ozone alone. However, about 50% and 30% removal of MTBE were achieved in 30 minutes when irradiated with MP-UV and LP-UV lamps, respectively. On the other hand, UV/H2O2 process was found to be superior in removal of MTBE (90% in 10 min. and benzene (95% in 5 min. compared to UV/O3 process. Furthermore, removal of benzene was comparatively easier than MTBE in both approaches. It is hence concluded that higher UV intensities and elevated doses of H2O2 accelerate simultaneous removal of MTBE and benzene from water.

  7. Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

    Science.gov (United States)

    Jablonowski, H.; Bussiahn, R.; Hammer, M. U.; Weltmann, K.-D.; von Woedtke, Th.; Reuter, S.

    2015-12-01

    Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100-400 nm) and, in particular, vacuum ultraviolet (VUV, 10-200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH2O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stable reactive oxygen species, hydrogen peroxide (H2O2) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O2•-) and hydroxyl radicals (•OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.

  8. Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

    Energy Technology Data Exchange (ETDEWEB)

    Jablonowski, H.; Hammer, M. U.; Reuter, S. [Center for Innovation Competence plasmatis, Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany); Leibniz Institute for Plasma Science and Technology, INP Greifswald e.V. Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany); Bussiahn, R.; Weltmann, K.-D.; Woedtke, Th. von [Leibniz Institute for Plasma Science and Technology, INP Greifswald e.V. Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany)

    2015-12-15

    Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100–400 nm) and, in particular, vacuum ultraviolet (VUV, 10–200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH{sub 2}O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stable reactive oxygen species, hydrogen peroxide (H{sub 2}O{sub 2}) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O{sub 2}{sup •−}) and hydroxyl radicals ({sup •}OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.

  9. Solar CIV Vacuum-Ultraviolet Fabry-Perot Interferometers

    Science.gov (United States)

    Gary, G. Allen; West, Edward A.; Rees, David; McKay, Jack A.; Zukic, Maumer; Herman, Peter

    2006-01-01

    Aims: A tunable, high spectral resolution, high effective finesse, vacuum ultraviolet (VUV) Fabry-Perot interferometer (PPI) is designed for obtaining narrow-passband images, magnetograms, and Dopplergrams of the transition region emission line of CIV (155 nm). Methods: The integral part of the CIV narrow passband filter package (with a 2-10 pm FWHM) consists of a multiple etalon system composed of a tunable interferometer that provides high-spectral resolution and a static low-spectral resolution interferometer that allows a large effective free spectral range. The prefilter for the interferometers is provided by a set of four mirrors with dielectric high-reflective coatings. A tunable interferometer, a VUV piezoelectric-control etalon, has undergone testing using the surrogate F2 eximer laser line at 157 nm for the CIV line. We present the results of the tests with a description of the overall concept for a complete narrow-band CIV spectral filter. The static interferometer of the filter is envisioned as being hudt using a set of fixed MgF2 plates. The four-mirror prefilter is designed to have dielectric multilayer n-stacks employing the design concept used in the Ultraviolet Imager of NASA's Polar Spacecraft. A dual etalon system allows the effective free spectral range to be commensurate with the prefilter profile. With an additional etalon, a triple etalon system would allow a spectrographic resolution of 2 pm. The basic strategy has been to combine the expertise of spaceflight etalon manufacturing with VUV coating technology to build a VUV FPI which combines the best attributes of imagers and spectrographs into a single compact instrument. Results. Spectro-polarimetry observations of the transition region CIV emission can be performed to increase the understanding of the magnetic forces, mass motion, evolution, and energy release within the solar atmosphere at the base of the corona where most of the magnetic field is approximately force-free. The 2D imaging

  10. High Data Rate Optical Wireless Communications Based on Ultraviolet Band

    KAUST Repository

    Sun, Xiaobin

    2017-10-01

    Optical wireless communication systems based on ultraviolet (UV)-band has a lot inherent advantages, such as low background solar radiation, low device dark noise. Besides, it also has small restrictive requirements for PAT (pointing, acquisition, and tracking) because of its high atmospheric scattering with molecules and aerosols. And these advantages are driving people to explore and utilize UV band for constructing and implementing a high-data-rate, less PAT communication links, such as diffuse-line-of-sight links (diffuse-LOS) and non-line-of-sight (NLOS). The responsivity of the photodetector at UV range is far lower than that of visible range, high power UV transmitters which can be easily modulated are under investigation. These factors make it is hard to realize a high-data-rate diffuse-LOS or NLOS UV communication links. To achieve a UV link mentioned above with current devices and modulation schemes, this thesis presents some efficient modulation schemes and available devices for the time being. Besides, a demonstration of ultraviolet-B (UVB) communication link is implemented utilizing quadrature amplitude modulation (QAM) orthogonal frequency-division multiplexing (OFDM). The demonstration is based on a 294-nm UVB-light-emitting-diode (UVB-LED) with a full-width at half-maximum (FWHM) of 9 nm, and according to the measured L-I-V curve, we set the bias voltage as 7V for maximum the ac amplitude and thus get a high signal-noise-ratio (SNR) channel, and the light output power is 190 μW with such bias voltage. Besides, there is a unique silica gel lens on top of the LED to concentrate the beam. A -3-dB bandwidth of 29 MHz was measured and a high-speed near-solar-blind communication link with a data rate of 71 Mbit/s was achieved using 8-QAM-OFDM at perfect alignment, and 23.6 Mbit/s using 2-QAM-OFDM when the angle subtended by the pointing direction of the UVB-LED and photodetector (PD) is 12 degrees, thus establishing a diffuse-line-of-sight (LOS) link

  11. The Far Ultra-Violet Imager on the Icon Mission

    Science.gov (United States)

    Mende, S. B.; Frey, H. U.; Rider, K.; Chou, C.; Harris, S. E.; Siegmund, O. H. W.; England, S. L.; Wilkins, C.; Craig, W.; Immel, T. J.; Turin, P.; Darling, N.; Loicq, J.; Blain, P.; Syrstad, E.; Thompson, B.; Burt, R.; Champagne, J.; Sevilla, P.; Ellis, S.

    2017-08-01

    ICON Far UltraViolet (FUV) imager contributes to the ICON science objectives by providing remote sensing measurements of the daytime and nighttime atmosphere/ionosphere. During sunlit atmospheric conditions, ICON FUV images the limb altitude profile in the shortwave (SW) band at 135.6 nm and the longwave (LW) band at 157 nm perpendicular to the satellite motion to retrieve the atmospheric O/N2 ratio. In conditions of atmospheric darkness, ICON FUV measures the 135.6 nm recombination emission of O+ ions used to compute the nighttime ionospheric altitude distribution. ICON Far UltraViolet (FUV) imager is a Czerny-Turner design Spectrographic Imager with two exit slits and corresponding back imager cameras that produce two independent images in separate wavelength bands on two detectors. All observations will be processed as limb altitude profiles. In addition, the ionospheric 135.6 nm data will be processed as longitude and latitude spatial maps to obtain images of ion distributions around regions of equatorial spread F. The ICON FUV optic axis is pointed 20 degrees below local horizontal and has a steering mirror that allows the field of view to be steered up to 30 degrees forward and aft, to keep the local magnetic meridian in the field of view. The detectors are micro channel plate (MCP) intensified FUV tubes with the phosphor fiber-optically coupled to Charge Coupled Devices (CCDs). The dual stack MCP-s amplify the photoelectron signals to overcome the CCD noise and the rapidly scanned frames are co-added to digitally create 12-second integrated images. Digital on-board signal processing is used to compensate for geometric distortion and satellite motion and to achieve data compression. The instrument was originally aligned in visible light by using a special grating and visible cameras. Final alignment, functional and environmental testing and calibration were performed in a large vacuum chamber with a UV source. The test and calibration program showed that ICON

  12. The Far Ultra-Violet Imager on the Icon Mission

    Science.gov (United States)

    Mende, S. B.; Frey, H. U.; Rider, K.; Chou, C.; Harris, S. E.; Siegmund, O. H. W.; England, S. L.; Wilkins, C.; Craig, W.; Immel, T. J.; Turin, P.; Darling, N.; Loicq, J.; Blain, P.; Syrstad, E.; Thompson, B.; Burt, R.; Champagne, J.; Sevilla, P.; Ellis, S.

    2017-10-01

    ICON Far UltraViolet (FUV) imager contributes to the ICON science objectives by providing remote sensing measurements of the daytime and nighttime atmosphere/ionosphere. During sunlit atmospheric conditions, ICON FUV images the limb altitude profile in the shortwave (SW) band at 135.6 nm and the longwave (LW) band at 157 nm perpendicular to the satellite motion to retrieve the atmospheric O/N2 ratio. In conditions of atmospheric darkness, ICON FUV measures the 135.6 nm recombination emission of O+ ions used to compute the nighttime ionospheric altitude distribution. ICON Far UltraViolet (FUV) imager is a Czerny-Turner design Spectrographic Imager with two exit slits and corresponding back imager cameras that produce two independent images in separate wavelength bands on two detectors. All observations will be processed as limb altitude profiles. In addition, the ionospheric 135.6 nm data will be processed as longitude and latitude spatial maps to obtain images of ion distributions around regions of equatorial spread F. The ICON FUV optic axis is pointed 20 degrees below local horizontal and has a steering mirror that allows the field of view to be steered up to 30 degrees forward and aft, to keep the local magnetic meridian in the field of view. The detectors are micro channel plate (MCP) intensified FUV tubes with the phosphor fiber-optically coupled to Charge Coupled Devices (CCDs). The dual stack MCP-s amplify the photoelectron signals to overcome the CCD noise and the rapidly scanned frames are co-added to digitally create 12-second integrated images. Digital on-board signal processing is used to compensate for geometric distortion and satellite motion and to achieve data compression. The instrument was originally aligned in visible light by using a special grating and visible cameras. Final alignment, functional and environmental testing and calibration were performed in a large vacuum chamber with a UV source. The test and calibration program showed that ICON

  13. Oxidation of Polyethylene: A Comparison of Plasma and Ultraviolet Ozone Processing Techniques

    National Research Council Canada - National Science Library

    Zander, Nicole; Pappas, Daphne; Stein, Ben

    2009-01-01

    Plasma and ultraviolet (UV) ozone treatments were compared as methods to functionalize ultrahigh molecular weight polyethylene films in order to make them more compatible with materials or reactive for subsequent surface chemistry...

  14. UARS Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) Level 3BS V001

    Data.gov (United States)

    National Aeronautics and Space Administration — The Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) Level 3BS data product consists of daily, 1 nm resolution, solar spectral irradiances and selected solar...

  15. Nanoimprint Resist Material Containing Ultraviolet Reactive Fluorine Surfactant for Defect Reduction in Lithographic Fabrication

    National Research Council Canada - National Science Library

    Takei, Satoshi; Sekiguchi, Atsushi

    2012-01-01

    ... in nanoimprint patterning replication. The developed acrylate type nanoimprint resist material containing 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoro-2-hydroxyundecyl acrylate as an ultraviolet reactive fluorine surfactant...

  16. Effects of ultraviolet-B exposure on the resistance to Listeria monocytogenes in the rat

    NARCIS (Netherlands)

    Goettsch W; Garssen J; de Klerk A; Herremans MMPT; Dortant P; de Gruijl FR; van Loveren H; LPI; VIR; UU

    1996-01-01

    Een Listeria monocytogenes infectiemodel in de rat werd gebruikt om de immuunsuppressieve activiteit van ultraviolet-B straling (UVB) te onderzoeken. Ratten werden dagelijks blootgesteld aan suberythemale hoeveelheden UVB straling gedurende 5 of 7 opeenvolgende dagen. Twee verschillende UV bronnen

  17. Spares and repair parts support plan for the ultraviolet spectrometer experiment S169

    Science.gov (United States)

    Vinson, W. W.

    1971-01-01

    The spares and repair parts program for the ultraviolet spectrometer experiment is outlined. The plan includes information on the selection, purchase, acceptance, and storage of spare parts, and on repair procedures.

  18. VG2 NEPTUNE ULTRAVIOLET SPECTROMETER SUBSYSTEM 3 RDR V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains reformatted records derived from data returned by the Voyager Ultraviolet Spectrometer Subsystem on board Voyager 2 during the Neptune...

  19. VG2 URANUS ULTRAVIOLET SPECTROMETER SUBSYSTEM 3 RDR V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains reformatted records derived from data returned by the Voyager Ultraviolet Spectrometer Subsystem on board Voyager 2 during the Uranus...

  20. Short-term antioxidative responses of 15 microalgae exposed to excessive irradiance including ultraviolet radiation

    NARCIS (Netherlands)

    Janknegt, Paul J.; De Graaff, C. Marco; Van De Poll, Willem H.; Visser, Ronald J. W.; Rijstenbil, Jan W.; Buma, Anita G. J.

    2009-01-01

    Short-term photosensitivity and oxidative stress responses were compared for three groups of marine microalgae: Antarctic microalgae, temperate diatoms and temperate flagellates. In total, 15 low-light-acclimated species were exposed to simulated surface irradiance including ultraviolet radiation