Science.gov

Sample records for 280-320 nm radiation

  1. Immunosuppressive effects of ultraviolet (280-320 nm) radiation and psoralen plus ultraviolet (320-400 nm) radiation in mice.

    PubMed

    Kripke, M L

    1982-07-01

    Contact hypersensitivity (CHS), a cell-mediated immunologic reaction, can be induced in mice by application of a contact-sensitizing chemical to the shaved skin. Exposing the animals to UV radiation from FS40 sunlamps inhibits this immune response. This inhibition is systemic, since the sensitizer need not be applied to the irradiated site of the animal. The mechanism whereby UV radiation prevents CHS appears to involve the production of suppressor T-lymphocytes. Recent evidence suggests that UV exposure of mice alters the way in which certain antigens are processed, and this altered processing or presentation of antigen results in the activation of the suppressor cell pathway, rather than leading to immunization. Treatment of mice with a photosensitizer, psoralen, plus UV (320-400 nm) radiation also suppresses CHS systemically, but whether the cellular mechanisms are the same as those underlying the suppression from the shorter UV wavelengths remains to be determined. The possible role of these immunosuppressive events in photocarcinogenesis is discussed. PMID:6212709

  2. Carnosine (beta-alanylhistidine) protects from the suppression of contact hypersensitivity by ultraviolet B (280-320 nm) radiation or by cis urocanic acid.

    PubMed

    Reeve, V E; Bosnic, M; Rozinova, E

    1993-01-01

    Carnosine is a naturally occurring histidine-containing dipeptide in mammalian tissues for which a physiological role has not been defined. It has antioxidant properties, but has also been shown to be related metabolically to histidine and histamine, and to have immunopotentiating properties in vivo. It is shown here that carnosine presented topically or in the diet, potentiated the contact hypersensitivity reaction in hairless mice. Carnosine also prevented the systemic suppression of this reaction following exposure of the dorsal skin to ultraviolet B (UVB) radiation. Furthermore, carnosine prevented the systemic suppression caused by a topically applied lotion containing cis urocanic acid, indicating that it may act in competition with this UVB photoproduct which is believed to initiate many of the suppressive effects of UVB radiation.

  3. Solar ultraviolet radiation exclusion increases soybean internode lengths and plant height

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybean [Glycine max (L.) Merr.] cultivars Williams-82 and Maverick were grown in a polycarbonate greenhouse, a glass greenhouse, and outdoors (during daytime) to investigate the effect of (i) exclusion of both solar UV-B radiation (280-320 nm) and UV-A radiation (320-400 nm), (ii) exclusion of sola...

  4. RESPONSE OF OXIDATIVE STRESS DEFENSE SYSTEMS IN RICE (ORYZA SATIVA) LEAVES WITH SUPPLEMENTAL UV-B RADIATION

    EPA Science Inventory

    The impact of elevated ultraviolet-B radiation (UV-B, 280-320 nm) on membrane systems and lipid peroxidation, and possible involvement of active oxygen radicals was investigated in leaves of two UV-B susceptible rice cultivars (Oryza sativa L. cvs IR74 and Dular). Rice seedlings ...

  5. Radiation Status of Sub-65 nm Electronics

    NASA Technical Reports Server (NTRS)

    Pellish, Jonathan A.

    2011-01-01

    Ultra-scaled complementary metal oxide semiconductor (CMOS) includes commercial foundry capabilities at and below the 65 nm technology node Radiation evaluations take place using standard products and test characterization vehicles (memories, logic/latch chains, etc.) NEPP focus is two-fold: (1) Conduct early radiation evaluations to ascertain viability for future NASA missions (i.e. leverage commercial technology development). (2) Uncover gaps in current testing methodologies and mechanism comprehension -- early risk mitigation.

  6. Radiation Tolerance of 65nm CMOS Transistors

    DOE PAGES

    Krohn, M.; Bentele, B.; Christian, D. C.; Cumalat, J. P.; Deptuch, G.; Fahim, F.; Hoff, J.; Shenai, A.; Wagner, S. R.

    2015-12-11

    We report on the effects of ionizing radiation on 65 nm CMOS transistors held at approximately -20°C during irradiation. The pattern of damage observed after a total dose of 1 Grad is similar to damage reported in room temperature exposures, but we observe less damage than was observed at room temperature.

  7. Radiation Failures in Intel 14nm Microprocessors

    NASA Technical Reports Server (NTRS)

    Bossev, Dobrin P.; Duncan, Adam R.; Gadlage, Matthew J.; Roach, Austin H.; Kay, Matthew J.; Szabo, Carl; Berger, Tammy J.; York, Darin A.; Williams, Aaron; LaBel, K.; Ingalls, James D.

    2016-01-01

    In this study the 14 nm Intel Broadwell 5th generation core series 5005U-i3 and 5200U-i5 was mounted on Dell Inspiron laptops, MSI Cubi and Gigabyte Brix barebones and tested with Windows 8 and CentOS7 at idle. Heavy-ion-induced hard- and catastrophic failures do not appear to be related to the Intel 14nm Tri-Gate FinFET process. They originate from a small (9 m 140 m) area on the 32nm planar PCH die (not the CPU) as initially speculated. The hard failures seem to be due to a SEE but the exact physical mechanism has yet to be identified. Some possibilities include latch-ups, charge ion trapping or implantation, ion channels, or a combination of those (in biased conditions). The mechanism of the catastrophic failures seems related to the presence of electric power (1.05V core voltage). The 1064 nm laser mimics ionization radiation and induces soft- and hard failures as a direct result of electron-hole pair production, not heat. The 14nm FinFET processes continue to look promising for space radiation environments.

  8. Effects of solar ultraviolet photons on mammalian cell DNA. [UVA (320-400 nm):a2

    SciTech Connect

    Peak, M.J.; Peak, J.G.

    1991-01-01

    This document presents information on the possible mechanisms of carcinogenesis caused by UVA (ultraviolet radiation in the 320--400 nm region). Most studies showing the carcinogenic effects of ultraviolet light have concentrated on UVB (280--320 nm). UVA had been considered harmless even though it penetrates biological tissues better than UVB. Recently, it has become apparent that UVA is also capable of causing damage to cellular DNA. This was unexpected because the DNA UV absorption spectrum indicates a negligible probability that photons of wavelengths longer than 320 nm will be directly absorbed. The most common defects induced in DNA by UVB are pyrimidine photoproducts, such as thymidine dimers. UVA photons produce defects resembling those caused by ionizing radiations: single- and double-strand breaks, and DNA-protein crosslinks. This paper also discusses the role of DNA repair mechanisms in UVA-induced defects and the molecular mechanisms of UVA damage induction. 38 refs. (MHB)

  9. Partial inhibition of in vitro pollen germination by simulated solar ultraviolet-B radiation

    SciTech Connect

    Flint, S.D.; Caldwell, M.M.

    1984-01-01

    Pollen from four temperate-latitude taxa were treated with UV radiation in a portion of the UV-B (280-320 nm) waveband during in vitro germination. Inhibition of germination was noted in this pollen compared to samples treated identically except for the exclusion of the UV-B portion of the spectrum. Levels similar to maximum solar UV-B found in temperate-latitude areas failed to inhibit pollen germination significantly, while levels similar to maximum solar UV-B found in equatorial alpine locations caused partial inhibition of germination in three of the four taxa examined.

  10. Generation and use of high power 213 nm and 266 nm laser radiation and tunable 210-400 nm laser radiation with BBO crystal matrix array

    DOEpatents

    Gruen, Dieter M.

    2000-01-01

    A 213 nm laser beam is capable of single photon ablative photodecomposition for the removal of a polymer or biological material substrate. Breaking the molecular bonds and displacing the molecules away from the substrate in a very short time period results in most of the laser photon energy being carried away by the displaced molecules, thus minimizing thermal damage to the substrate. The incident laser beam may be unfocussed and is preferably produced by quintupling the 1064 nm radiation from a Nd:YAG solid state laser, i.e., at 213 nm. In one application, the 213 nm laser beam is expanded in cross section and directed through a plurality of small beta barium borate (BBO) crystals for increasing the energy per photon of the laser radiation directed onto the substrate. The BBO crystals are arranged in a crystal matrix array to provide a large laser beam transmission area capable of accommodating high energy laser radiation without damaging the BBO crystals. The BBO crystal matrix array may also be used with 266 nm laser radiation for carrying out single or multi photon ablative photodecomposition. The BBO crystal matrix array may also be used in an optical parametric oscillator mode to generate high power tunable laser radiation in the range of 210-400 nm.

  11. Morphological responses of crop and weed species of different growth forms to ultraviolet-B radiation

    SciTech Connect

    Barnes, P.W.; Flint, S.D.; Caldwell, M.M. )

    1990-10-01

    Recent evidence of a general, global decline of stratospheric ozone has heightened concern about possible ecological consequences of increases in solar ultraviolet-B (UV-B, 280-320 nm) radiation resulting from ozone depletion. The influence of UV-B radiation (280-320 nanometers) on the morphology of 12 common dicot and monocot crop or weed species was examined to determine whether any common responses could be found that might, in turn, be useful in predicting possible changes in competitive balance under solar UV-B enhancement. Under glasshouse conditions, UV-B exposure (simulating a 20% reduction in stratospheric ozone at Logan, Utah) was found to reduce leaf blade and internode lengths and increase leaf and axillary shoot production in several species. Overall, the directions of these trends were similar in the majority of species that exhibited a significant response. These morphological changes occurred without any significant reduction in total shoot dry matter production. There was no clear distinction in the response of crops and weeds, though monocots were found to be generally more responsive than dicots. Previous work in dense canopies has shown that the photomorphogenetic effects of UV-B alter leaf placement and thereby influence competition for light. Our results suggest that, under these conditions, changes in competitive balance resulting from increased UV-B might be expected more frequently when monocots are involved in mixtures, rather than mixtures of only dicots.

  12. [Effects of enhanced UV-B radiation on terrestrial ecosystem carbon cycle: a review].

    PubMed

    Liu, Shu-Rong; Hu, Rong-Gui; Cai, Gao-Chao

    2012-07-01

    As one of the most important phenomena of global climate change, the enhancement of ultraviolet-B radiation (UV-B, 280-320 nm) could have critical impact on the carbon cycle in terrestrial ecosystem. Through the impacts on plant photosynthesis, litter decomposition, and soil respiration, the enhanced UV-B radiation can affect the carbon input, turnover, and output of terrestrial ecosystem. Other climatic factors (ambient CO2 concentration, air temperature, and precipitation) may promote or mitigate the impact of enhanced UV-B radiation on terrestrial ecosystem carbon cycle. This paper introduced the background of UV-B radiation enhancement, reviewed the impacts of enhanced UV-B radiation and its interactions with other climatic factors on terrestrial ecosystem carbon cycle, summarized the existing problems in related researches, and discussed the priorities and directions of future researches.

  13. [UV-radiation--sources, wavelength, environment].

    PubMed

    Hölzle, Erhard; Hönigsmann, Herbert

    2005-09-01

    The UV-radiation in our environment is part of the electromagnetic radiation, which emanates from the sun. It is designated as optical radiation and reaches from 290-4,000 nm on the earth's surface. According to international definitions UV irradiation is divided into short-wave UVC (200-280 nm), medium-wave UVB (280-320 nm), and long-wave UVA (320-400 nm). Solar radiation which reaches the surface of the globe at a defined geographical site and a defined time point is called global radiation. It is modified quantitatively and qualitatively while penetrating the atmosphere. Besides atmospheric conditions, like ozone layer and air pollution, geographic latitude, elevation, time of the season, time of the day, cloudiness and the influence of indirect radiation resulting from stray effects in the atmosphere and reflection from the underground play a role in modifying global radiation, which finally represents the biologically effective radiation. The radiation's distribution on the body surface varies according to sun angle and body posture. The cumulative UV exposure is mainly influenced by outdoor profession and recreational activities. The use of sun beds and phototherapeutic measures additionally may contribute to the cumulative UV dose.

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

    PubMed

    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.

  15. Radiation trapping of the Hg 185 nm resonance line

    NASA Astrophysics Data System (ADS)

    Menningen, K. L.; Lawler, J. E.

    2000-09-01

    The decay rate of the Hg 61P1 level was measured as a function of cold spot temperature (Hg density) and buffer gas pressure in cylindrical, sealed fused silica cells. The decay rates were obtained using a time-resolved laser-induced 185 nm fluorescence experiment with multi-step excitation. Cold spot temperatures from 25 to 100 °C were studied. The Hg densities for this temperature range and with no buffer gas yield the lowest possible decay rates due to radiation trapping with partial frequency redistribution. Decay rates with argon buffer gas pressures of 3 and 30 Torr were also studied. The results are in agreement with published data from a discharge afterglow experiment. Monte Carlo simulations of radiation transport in the cells, including the effects of hyperfine and isotope structure, the effects of foreign gas broadening, and partial frequency redistribution are compared to the experimental data. Reasonably good agreement is obtained, however there is evidence of quenching of Hg 61P1 atoms in collisions with ground state Hg and Ar atoms. An analytic formula for the fundamental mode trapped decay rate of the 61P1 level, which is applicable over a substantial region of parameter space, was devised from the Monte Carlo results.

  16. Gracilaria bursa-pastoris (Gmelin) Silva extract attenuates ultraviolet B radiation-induced oxidative stress in human keratinocytes.

    PubMed

    Piao, M J; Kim, K C; Zheng, J; Yao, C W; Cha, J W; Kang, H K; Yoo, E S; Koh, Y S; Ko, M H; Lee, N H; Hyun, Jin Won

    2014-01-01

    The purpose of this study was to assess the protective effects of an ethanol extract derived from the red alga Gracilaria bursa-pastoris (Gmelin) Silva (GBE) on ultraviolet B (UVB)-irradiated human HaCaT keratinocytes. GBE exhibited scavenging activity against intracellular reactive oxygen species that were induced by either hydrogen peroxide or UVB radiation. In addition, both the superoxide anion and the hydroxyl radical were scavenged by GBE in cell-free systems. GBE absorbed light in the UVB range (280-320 nm) of the electromagnetic spectrum and lessened the extent of UVB-induced oxidative damage to cellular lipids, proteins, and DNA. Finally, GBE-treated keratinocytes showed a reduction in UVB-induced apoptosis, as exemplified by fewer apoptotic bodies. These results suggest that GBE exerts cytoprotective actions against UVB-stimulated oxidative stress by scavenging ROS and absorbing UVB rays, thereby attenuating injury to cellular constituents and preventing cell death.

  17. Ultraviolet radiation absorbing compounds in marine organisms

    SciTech Connect

    Chalker, B.E.; Dunlap, W.C. )

    1990-01-09

    Studies on the biological effects of solar ultraviolet radiations are becoming increasingly common, in part due to recent interest in the Antarctic ozone hole and in the perceived potential for global climate change. Marine organisms possess many strategies for ameliorating the potentially damaging effects of UV-B (280-320 nm) and the shorter wavelengths of UV-A (320-400nm). One mechanism is the synthesis of bioaccumulation of ultraviolet radiation absorbing compounds. Several investigators have noted the presence of absorbing compounds in spectrophotometer scans of extracts from a variety of marine organisms, particularly algae and coelenterates containing endosymbiotic algae. The absorbing compounds are often mycosporine-like amino acids. Thirteen mycosporine-like amino acids have already been described, and several others have recently been detected. Although, the mycosporine-like amino acids are widely distributed. these compounds are by no means the only type of UV-B absorbing compounds which has been identified. Coumarins from green algae, quinones from sponges, and indoles from a variety of sources are laternative examples which are documented in the natural products literature. When the biological impact of solar ultraviolet radiation is assessed, adequate attention must be devoted to the process of photoadaptation, including the accumulation of ultraviolet radiation absorbing compounds.

  18. Brain lesion induced by 1319nm laser radiation

    NASA Astrophysics Data System (ADS)

    Yang, Zaifu; Chen, Hongxia; Wang, Jiarui; Chen, Peng; Ma, Ping; Qian, Huanwen

    2010-11-01

    The laser-tissue interaction has not been well defined at the 1319 nm wavelength for brain exposure. The goal of this research effort was to identify the behavioral and histological changes of brain lesion induced by 1319 nm laser. The experiment was performed on China Kunming mice. Unilateral brain lesions were created with a continuous-wave Nd:YAG laser (1319nm). The brain lesions were identified through behavioral observation and histological haematoxylin and eosin (H&E) staining method. The behavior change was observed for a radiant exposure range of 97~773 J/cm2. The histology of the recovery process was identified for radiant exposure of 580 J/cm2. Subjects were sacrificed 1 hour, 1 week, 2 weeks, 3 months, 7 months and 13 months after laser irradiation. Results showed that after laser exposure, behavioral deficits, including kyphosis, tail entasia, or whole body paralysis could be noted right after the animals recovered from anesthesia while gradually disappeared within several days and never recurred again. Histologically, the laser lesion showed a typical architecture dependent on the interval following laser treatment. The central zone of coagulation necrosis is not apparent right after exposure but becomes obvious within several days. The nerotic tissue though may persist for a long time, will finally be completely resorbed. No carbonization granules formed under our exposure condition.

  19. Sum frequency generation of UV laser radiation at 266  nm in LBO crystal.

    PubMed

    Nikitin, D G; Byalkovskiy, O A; Vershinin, O I; Puyu, P V; Tyrtyshnyy, V A

    2016-04-01

    We report experimental results of generation at 266 nm in LBO crystal by frequency mixing of the fundamental (1064 nm) and third harmonic (355 nm) of ytterbium pulsed fiber laser radiation. Deep ultraviolet (DUV) output power of 3.3 W at 266 nm was achieved with 14% IR-to-DUV conversion efficiency. UV-induced bulk degradation of LBO crystals was observed and visualized by the dark field method. PMID:27192312

  20. Generation of Coherent 19- and 38-nm Radiation at a Free-Electron Laser Directly Seeded at 38 nm

    NASA Astrophysics Data System (ADS)

    Ackermann, S.; Azima, A.; Bajt, S.; Bödewadt, J.; Curbis, F.; Dachraoui, H.; Delsim-Hashemi, H.; Drescher, M.; Düsterer, S.; Faatz, B.; Felber, M.; Feldhaus, J.; Hass, E.; Hipp, U.; Honkavaara, K.; Ischebeck, R.; Khan, S.; Laarmann, T.; Lechner, C.; Maltezopoulos, Th.; Miltchev, V.; Mittenzwey, M.; Rehders, M.; Rönsch-Schulenburg, J.; Rossbach, J.; Schlarb, H.; Schreiber, S.; Schroedter, L.; Schulz, M.; Schulz, S.; Tarkeshian, R.; Tischer, M.; Wacker, V.; Wieland, M.

    2013-09-01

    Initiating the gain process in a free-electron laser (FEL) from an external highly coherent source of radiation is a promising way to improve the pulse properties such as temporal coherence and synchronization performance in time-resolved pump-probe experiments at FEL facilities, but this so-called “seeding” suffers from the lack of adequate sources at short wavelengths. We report on the first successful seeding at a wavelength as short as 38.2 nm, resulting in GW-level, coherent FEL radiation pulses at this wavelength as well as significant second harmonic emission at 19.1 nm. The external seed pulses are about 1 order of magnitude shorter compared to previous experiments allowing an ultimate time resolution for the investigation of dynamic processes enabling breakthroughs in ultrafast science with FELs. The seeding pulse is the 21st harmonic of an 800-nm, 15-fs (rms) laser pulse generated in an argon medium. Methods for finding the overlap of seed pulses with electron bunches in spatial, longitudinal, and spectral dimensions are discussed and results are presented. The experiment was conducted at FLASH, the FEL user facility at DESY in Hamburg, Germany.

  1. Vacuum-UV radiation at 185 nm in water treatment--a review.

    PubMed

    Zoschke, Kristin; Börnick, Hilmar; Worch, Eckhard

    2014-04-01

    The vacuum-UV radiation of water results in the in situ generation of hydroxyl radicals. Low-pressure mercury vapor lamps which emit at 185 nm are potential sources of VUV radiation. The scope of this article is to give an overview of the application of VUV radiation at 185 nm for water treatment including the transformation of inorganic and organic water constituents, and the disinfection efficiency. Another focus is on the generation of ozone by VUV radiation from oxygen or air and the application of the produced ozone in combination with VUV irradiation of water in the VUV/O3 process. The advantages and limitation of the VUV process at 185 nm as well as possible applications in water treatment are outlined.

  2. Association of amphibians with attenuation of ultraviolet-b radiation in montane ponds

    USGS Publications Warehouse

    Adams, M.J.; Schindler, D.E.; Bury, B.R.

    2001-01-01

    Ambient ultraviolet-b (UV-B) radiation (280-320 nm) has increased at north-temperate latitudes in the last two decades. UV-B can be detrimental to amphibians, and amphibians have shown declines in some areas during this same period. We documented the distribution of amphibians and salmonids in 42 remote, subalpine and alpine ponds in Olympic National Park, Washington, United States. We inferred relative exposure of amphibian habitats to UV-B by estimating the transmission of 305- and 320-nm radiation in pond water. We found breeding Ambystoma gracile, A. macrodactylum and Rana cascadae at 33%, 31%, and 45% of the study sites, respectively. Most R. cascadae bred in fishless shallow ponds with relatively low transmission of UV-B. The relationship with UV-B exposure remained marginally significant even after the presence of fish was included in the model. At 50 cm water depth, there was a 55% reduction in incident 305-nm radiation at sites where breeding populations of R. cascadae were detected compared to other sites. We did not detect associations between UV-B transmission and A. gracile or A. macrodactylum. Our field surveys do not provide evidence for decline of R. cascadae in Olympic National Park as has been documented in Northern California, but are consistent with the hypothesis that the spatial distribution of R. cascadae breeding sites is influenced by exposure to UV-B. Substrate or pond depth could also be related to the distribution of R. cascadae in Olympic National Park.

  3. Inhibition of denitrification by ultraviolet radiation.

    PubMed

    Mancinelli, R L; White, M R

    2000-01-01

    It has been shown that UV-A (lambda=320-400 nm) and UV-B (lambda=280-320 nm) inhibit photosynthesis, nitrogen fixation and nitrification. The purpose of this study was to determine the effects, if any, on denitrification in a microbial community inhabiting the intertidal. The community studied is the microbial mat consisting primarily of Lyngbya that inhabits the Pacific marine intertidal, Baja California, Mexico. Rates of denitrification were determined using the acetylene blockage technique. Pseudomonas fluorescens (ATCC #17400) was used as a control organism, and treated similarly to the mat samples. Samples were incubated either beneath a PAR transparent, UV opaque screen (OP3), or a mylar screen to block UV-B, or a UV transparent screen (UVT) for 2 to 3 hours. Sets of samples were also treated with nitrapyrin to inhibit nitrification, or DCMU to inhibit photosynthesis and treated similarly. Denitrification rates were greater in the UV protected samples than in the UV exposed samples the mat samples as well as for the Ps fluorescens cultures. Killed controls exhibited no activity. In the DCMU and nitrapyrin treated samples denitrification rates were the same as in the untreated samples. These data indicate that denitrification is directly inhibited by UV radiation.

  4. Inhibition of denitrification by ultraviolet radiation

    NASA Astrophysics Data System (ADS)

    Mancinelli, R. L.; White, M. R.

    It has been shown that UV-A (λ = 320- 400 nm) and UV-B (λ = 280 - 320 nm) inhibit photosynthesis, nitrogen fixation and nitrification. The purpose of this study was to determine the effects, if any, on denitrification in a microbial community inhabiting the intertidal. The community studied is the microbial mat consisting primarily of Lyngbya that inhabits the Pacific marine intertidal, Baja California, Mexico. Rates of denitrification were determined using the acetylene blockage technique. Pseudomonas fluorescens (ATCC # 17400) was used as a control organism, and treated similarly to the mat samples. Samples were incubated either beneath a PAR transparent, UV opaque screen (OP3), or a mylar screen to block UV-B, or a UV transparent screen (UVT) for 2 to 3 hours. Sets of samples were also treated with nitrapyrin to inhibit nitrification, or DCMU to inhibit photosynthesis and treated similarly. Denitrification rates were greater in the UV protected samples than in the UV exposed samples the mat samples as well as for the Ps. fluorescens cultures. Killed controls exhibited no activity. In the DCMU and nitrapyrin treated samples denitrification rates were the same as in the untreated samples. These data indicate that denitrification is directly inhibited by UV radiation.

  5. Inhibition of denitrification by ultraviolet radiation.

    PubMed

    Mancinelli, R L; White, M R

    2000-01-01

    It has been shown that UV-A (lambda=320-400 nm) and UV-B (lambda=280-320 nm) inhibit photosynthesis, nitrogen fixation and nitrification. The purpose of this study was to determine the effects, if any, on denitrification in a microbial community inhabiting the intertidal. The community studied is the microbial mat consisting primarily of Lyngbya that inhabits the Pacific marine intertidal, Baja California, Mexico. Rates of denitrification were determined using the acetylene blockage technique. Pseudomonas fluorescens (ATCC #17400) was used as a control organism, and treated similarly to the mat samples. Samples were incubated either beneath a PAR transparent, UV opaque screen (OP3), or a mylar screen to block UV-B, or a UV transparent screen (UVT) for 2 to 3 hours. Sets of samples were also treated with nitrapyrin to inhibit nitrification, or DCMU to inhibit photosynthesis and treated similarly. Denitrification rates were greater in the UV protected samples than in the UV exposed samples the mat samples as well as for the Ps fluorescens cultures. Killed controls exhibited no activity. In the DCMU and nitrapyrin treated samples denitrification rates were the same as in the untreated samples. These data indicate that denitrification is directly inhibited by UV radiation. PMID:12038490

  6. Application of XeCl308 nm excimer laser radiation to mutagenesis of industrial microorganisms

    NASA Astrophysics Data System (ADS)

    Alifano, P.; Lorusso, A.; Nassisi, V.; Talà, A.; Tredici, S. M.

    (UV) lamps are widely used in mutagenesis-selection protocols. Nevertheless, since the eighties, due to the development of excimer lasers, new frontiers in the study of UV applications have been opened. It has been established that the presence of an intact SOS response system is required for the mutagenic effect of UV254 nm. The exposure to UV254 nm radiation is not mutagenic for Escherichia coli mutants lacking the RecA protein, the regulator of the SOS response. We have recently demonstrated that at variance with the UV254 nm mutagenesis, the UV308 nm mutagenesis by XeCl308 nm excimer laser is RecA-independent. This suggests that the UV308 nm might be mutagenic also in microorganisms naturally lacking the SOS response. In this study, we have developed an innovative mutagenesis protocol based on a homemade XeCl308 nm excimer laser and have demonstrated its efficiency on mutagenesis of Nonomuraea American type culture collection 39727, an industrial strain producing an antibiotic, which is relatively refractory to UV254 nm radiation-induced mutagenesis.

  7. Nonthermal radiative transfer of oxygen 98.9 nm ultraviolet emission: Solving an old mystery

    NASA Astrophysics Data System (ADS)

    Hubert, B.; Gérard, J.-C.; Shematovich, V. I.; Bisikalo, D. V.; Chakrabarti, S.; Gladstone, G. R.

    2015-12-01

    Sounding rocket measurements conducted in 1988 under high solar activity conditions revealed that the intensity of thermospheric OI emissions at 98.9 nm presents an anomalous vertical profile, showing exospheric intensities much higher than expected from radiative transfer model results, which included the known sources of excited oxygen. All attempts based on modeling of the photochemical processes and radiative transfer were unable to account for the higher than predicted brightnesses. More recently, the SOHO-Solar Ultraviolet Measurements of Emitted Radiation instrument measured the UV solar flux at high-spectral resolution, revealing the importance of a significant additional source of oxygen emission at 98.9 nm that had not been accounted for before. In this study, we simulate the radiative transfer of the OI-98.9 nm multiplet, including the photochemical sources of excited oxygen, the resonant scattering of solar photons, and the effects of nonthermal atoms, i.e., a population of fast-moving oxygen atoms in excess of the Maxwellian distribution. Including resonance scattering of the 98.9 nm solar multiplet, we find good agreement with the previous sounding rocket observation. The inclusion of a nonthermal oxygen population with a consistent increase of the total density produces a larger intensity at high altitude that apparently better accounts for the observation, but such a correction cannot be demonstrated given the uncertainties of the observations. A good agreement between model and sounding rocket observation is also found with the triplet at 130.4 nm. We further investigate the radiative transfer of the OI-98.9 nm multiplet and the oxygen emissions at 130.4 and 135.6 nm using observations from the STP78-1 satellite. We find a less satisfying agreement between the model and the STP78-1 data that can be accounted for by scaling the modeled intensity within a range acceptable given the uncertainties on the STP78-1 absolute calibration.

  8. DNA repair synthesis in the rat retina following in vivo exposure to 300-nm radiation

    SciTech Connect

    Rapp, L.M.; Jose, J.G.; Pitts, D.G.

    1985-03-01

    Quantitative autoradiography was used to study the incorporation of /sup 3/H-thymidine into the retina of albino rats following in vivo exposure to 300-nm radiation. Relative to background labeling in unexposed eyes, there was 8-20 times as much label per unit area in the outer nuclear layer, inner nuclear layer, and ganglion cells of 300-nm exposed retinas. The photoreceptor inner segments also showed thymidine labeling in both control and exposed retinas.

  9. New apparatus with high radiation energy between 320 to 460 nm: physical description and dermatological applications

    SciTech Connect

    Mutzhas, M.F.; Holzle, E.; Hofmann, C.; Plewig, G.

    1981-01-01

    A new apparatus (UVASUN 5000) is presented with high radiation energy between 320 to 460 nm. The radiator is a specially developed source for high uv-A intensity, housing a quartz bulb with a mixture of argon, mercury and metal-halides. The uv-A energy in the range of 320 to 400 nm is about 84% of the total radiation energy. Effects of very high doses of uv-A on human skin were studied. Following single uv-A applications the minimal tanning dose uv-A (MTD) and the immediate pigment darkening (IPD) dose of uv-A were established. Repeated exposure to this uv-A delivering system yields long lasting dark brown skin pigmentation without any clinical or histological signs of sunburn (uv-B) damage, epidermal hyperplasia or thickening of the stratum corneum. Minimal therapeutic results were seen in the phototherapy of vitiligo and inflammatory acne.

  10. Effects of solar ultraviolet radiation on antarctic phytoplankton during springtime ozone depletion

    SciTech Connect

    Villafane, V.E.; Helbling, E.W.; Holm-Hansen, O.

    1994-12-31

    In recent years, much attention has been given to the formation of the seasonal ozone {open_quotes}hole{close_quotes} over Antarctica, with the concomitant increase in ultraviolet-B [UV-B, 280-320-nanometer (nm)] radiation levels. The enhanced UV-B radiation can be very damaging to biological systems and has been shown to cause a significant decrease in rates of primary production. This paper describes the impact of {open_quotes}normal{close_quotes} ultraviolet radiation (UVR), as well as enhanced UV-B radiation, on natural assemblages of phytoplankton as well as on just the nanoplankton fraction cells less than 20 micrometers ({mu}m). The studies also included estimation of the impact of UVR as influenced by the taxonomic composition of the phytoplankton and the mitigating effect of cellular UV-absorbing compounds. All studies were carried out at Palmer Station (64.7{degrees}S 64.1{degrees}W) on Anvers Island from early October to the end of December 1993. This period provided excellent opportunities to document the impact of enhanced UV-B radiation on phytoplankton because the ozone hole was very well developed over Palmer Station in the month of October; column ozone concentrations ranged from 140 to 220 Dobson units (DU). 10 refs, 3 figs.

  11. Response of five tropical plant species to natural solar ultraviolet-B radiation

    SciTech Connect

    Searles, P.S.; Caldwell, M.M. ); Winter, K. )

    1994-06-01

    The tropical latitudes currently receive high solar ultraviolet-B radiation (UV-B, 280-320 nm) even without ozone depletion. Thus, the influence of natural, present-day UV-B irradiance was examined for three native rainforest tree species and two economically important species on Barro Colorado Island, Panama (9[degrees] N). Solar UV-B radiation conditions were obtained using a UV-B excluding plastic film or a near-ambient UV-B transmitting film over potted plants in a small clearing. Significant differences were often exhibited as increased foliar UV-B absorbing compounds, increased leaf mass pre area, and reduced leaf blade length for plants receiving solar UV-B radiation. Plant height was typically reduced under solar UV-B, but some variation among species in response was seen. Biomass and photosystem II function were generally unaffected. The results provide evidence that tropical vegetation responds to the present level of Solar UV-B radiation. This suggests even a small increase in UV-B radiation with ozone depletion may have biological implications.

  12. Hypersensitivity of skin fibroblasts from basal cell nevus syndrome patients to killing by ultraviolet B but not by ultraviolet C radiation

    SciTech Connect

    Applegate, L.A.; Goldberg, L.H.; Ley, R.D.; Ananthaswamy, H.N. )

    1990-02-01

    Basal cell nevus syndrome (BCNS) is an autosomal dominant genetic disorder in which the afflicted individuals are extremely susceptible to sunlight-induced skin cancers, particularly basal cell carcinomas. However, the cellular and molecular basis for BCNS is unknown. To ascertain whether there is any relationship between genetic predisposition to skin cancer and increased sensitivity of somatic cells from BCNS patients to killing by UV radiation, we exposed skin fibroblasts established from unexposed skin biopsies of several BCNS and age- and sex-matched normal individuals to either UV-B (280-320 nm) or UV-C (254 nm) radiation and determined their survival. The results indicated that skin fibroblasts from BCNS patients were hypersensitive to killing by UV-B but not UV-C radiation as compared to skin fibroblasts from normal individuals. DNA repair studies indicated that the increased sensitivity of BCNS skin fibroblasts to killing by UV-B radiation was not due to a defect in the excision repair of pyrimidine dimers. These results indicate that there is an association between hypersensitivity of somatic cells to killing by UV-B radiation and the genetic predisposition to skin cancer in BCNS patients. In addition, these results suggest that DNA lesions (and repair processes) other than the pyrimidine dimer are also involved in the pathogenesis of sunlight-induced skin cancers in BCNS patients. More important, the UV-B sensitivity assay described here may be used as a diagnostic tool to identify presymptomatic individuals with BCNS.

  13. Development of Nighttime OI 135.6nm emission and radiative transfer model

    NASA Astrophysics Data System (ADS)

    Jiang, F.

    2013-12-01

    Characterizing the nighttime ionosphere using 135.6nm emission is one of the most used ionosphere monitoring means. An optical instrument using nighttime 135.6nm emission to study the column electron content(TEC) and F-region peak electron density(NmF2) will be launched on FY-3 satellite in China. The prerequisite to carry out retrieving and data processing is to develop the nighttime 135.6nm emission and radiative transfer calculation model. The model used an iterative scheme to determine the radiative transfer question including multiple scattering of atom oxygen and absorption of molecule oxygen.The volume emisson and the column emission were derived by the model. Results confirmed that the model could well describe the distribution of the volume emission rate through radiative transfer with the height,local time,season,latitude and longitude. The column emission rates calculated by the model were comparied with similar model and the results show the calculated column rates are believalbe.

  14. Photocatalytic reactive oxygen species production and phototoxicity of titanium dioxide nanoparticles are dependent on the solar ultraviolet radiation spectrum.

    PubMed

    Ma, Hongbo; Brennan, Amanda; Diamond, Stephen A

    2012-09-01

    Generation of reactive oxygen species (ROS) by titanium dioxide nanoparticles (nano-TiO(2)) and its consequent phototoxicity to Daphnia magna were measured under different solar ultraviolet (UV) spectra by applying a series of optical filters in a solar simulator. Removing UV-B (280-320 nm) from solar radiation had no significant impact on photocatalytic ROS production of nano-TiO(2), whereas removal of UV-A (320-400 nm) decreased ROS production remarkably. Removal of wavelengths below 400 nm resulted in negligible ROS production. A linear correlation between ROS production and D. magna immobilization suggests that photocatalytic ROS production may be a predictor of phototoxicity for nano-TiO(2). Intracellular ROS production within D. magna was consistent with the immobilization of the organism under different solar UV spectra, indicating that oxidative stress was involved in phototoxicity. The dependence of nano-TiO(2) phototoxicity on environmentally realistic variations in solar radiation suggests that risk assessment of these nanomaterials requires careful evaluation of exposure conditions in the environment.

  15. In vitro investigations on the effect of dermal fibroblasts on keratinocyte responses to ultraviolet B radiation.

    PubMed

    Fernandez, Tara L; Van Lonkhuyzen, Derek R; Dawson, Rebecca A; Kimlin, Michael G; Upton, Zee

    2014-01-01

    Exposure to ultraviolet radiation is closely linked to the development of skin cancers in humans. The ultraviolet B (UVB) radiation wavelength (280-320 nm), in particular, causes DNA damage in epidermal keratinocytes, which are linked to the generation of signature premalignant mutations. Interactions between dermal fibroblasts and keratinocytes play a role in epidermal repair and regeneration after UVB-induced damage. To investigate these processes, established two and three-dimensional culture models were utilized to study the impact of fibroblast-keratinocyte crosstalk during the acute UVB response. Using a coculture system it was observed that fibroblasts enhanced keratinocyte survival and the repair of cyclobutane pyrimidine dimers (CPDs) after UVB radiation exposure. These findings were also mirrored in irradiated human skin coculture models employed in this study. Fibroblast coculture was shown to play a role in the expression and activation of members of the apoptotic cascade, including caspase-3 and Bad. Interestingly, the expression and phosphorylation of p53, a key player in the regulation of keratinocyte cell fate postirradiation, was also shown to be influenced by fibroblast-produced factors. This study highlights the importance of synergistic interactions between fibroblasts and keratinocytes in maintaining a functional epidermis while promoting repair and regeneration following UVB radiation-induced damage.

  16. Picosecond laser texturization of mc-silicon for photovoltaics: A comparison between 1064 nm, 532 nm and 355 nm radiation wavelengths

    NASA Astrophysics Data System (ADS)

    Binetti, Simona; Le Donne, Alessia; Rolfi, Andrea; Jäggi, Beat; Neuenschwander, Beat; Busto, Chiara; Frigeri, Cesare; Scorticati, Davide; Longoni, Luca; Pellegrino, Sergio

    2016-05-01

    Self-organized surface structures were produced by picosecond laser pulses on multi-crystalline silicon for photovoltaic applications. Three different laser wavelengths were employed (i.e. 1064 nm, 532 nm and 355 nm) and the resulting morphologies were observed to effectively reduce the reflectivity of the samples after laser irradiation. Besides, a comparative study of the laser induced subsurface damage generated by the three different wavelengths was performed by confocal micro-Raman, photoluminescence and transmission electron microscopy. The results of both the structural and optical characterization showed that the mc-Si texturing performed with the laser at 355 nm provides surface reflectivity between 11% and 8% over the spectral range from 400 nm to 1 μm, while inducing the lowest subsurface damage, located above the depletion region of the p-n junction.

  17. New apparatus with high radiation energy between 320-460 nm: physical description and dermatological applications

    SciTech Connect

    Mutzhas, M.F.; Holzle, E.; Hofmann, C.; Plewig, G.

    1981-01-01

    A new apparatus (UVASUN 5000) is presented with high-radiation energy between 320 to 460 nm. The measureable energy below 320 nm was shown to be many orders of magnitude too low to produce erythema. The radiator is a specially developed source for high uv-A intensity, housing a quartz bulb with a mixture of argon, mercury and metal-halides. At a skin-target distance of 0.2 m the size of the irradiated area is 0.35 x 0.35 m, and the measured mean uv-A intensity is about 1400 W. m-2 (140 mW . cm-2). The uv-A energy in the range of 320 to 400 nm is about 84% of the total radiation energy. Effects of very high doses of uv-A on human skin were studied. Following single uv-a applications the minimal tanning dose uv-A (MTD) and the immediate pigment darkening (IPD) dose of uv-A were established. The calculated IPD threshold time was 1.8 min at 0.2 m. Repeated exposure to this uv-A delivering system yields long lasting dark brown skin pigmentation without any clinical or histological signs of sunburn (uv-B) damage, epidermal hyperplasia or thickening of the stratum corneum. The instrument was also successfully used for photo-patch testing and reproduction of skin lesions of polymorphous light eruption. Minimal therapeutic results were seen in the phototherapy of vitiligo and inflammatory acne.

  18. A cesium bromide photocathode excited by 405 nm radiation

    SciTech Connect

    Maldonado, J. R.; Cheng, Y. T.; Pease, Fabian W.; Hesselink, L.; Pianetta, P.

    2014-07-14

    In several applications, such as electron beam lithography and X-ray differential phase contrast imaging, there is a need for a free electron source with a current density at least 10 A/cm{sup 2} yet can be shaped with a resolution down to 20 nm and pulsed. Additional requirements are that the source must operate in a practical demountable vacuum (>1e-9 Torr) and be reasonably compact. In prior work, a photocathode comprising a film of CsBr on metal film on a sapphire substrate met the requirements except it was bulky because it required a beam (>10 W/cm{sup 2}) of 257 nm radiation. Here, we describe an approach using a 405 nm laser which is far less bulky. The 405 nm laser, however, is not energetic enough to create color centers in CsBr films. The key to our approach is to bombard the CsBr film with a flood beam of about 1 keV electrons prior to operation. Photoelectron efficiencies in the range of 100–1000 nA/mW were demonstrated with lifetimes exceeding 50 h between electron bombardments. We suspect that the electron bombardment creates intraband color centers whence electrons can be excited by the 405 nm photons into the conduction band and thence into the vacuum.

  19. DNA damage and altered gene expression in cultured human skin fibroblasts exposed to 193-nm excimer laser radiation

    NASA Astrophysics Data System (ADS)

    Samid, Dvorit; Flessate, Denise M.; Miller, Alexandra C.; Rimoldi, Donata

    1990-06-01

    Tissue ablation using 193nm excimer lasers is being considered for a variety of surgical procedures, yet little is known regarding the potential mutagenic risk to human cells. The effects of sublethal doses of radiation on cellular DNA and gene expression have been examined in cultured human skin fibroblasts. Northern blot analysis of mRNA revealed an increase in the levels of the c-f. proto-oncogene, interstitial collagenase, and metallothionein transcripts after laser radiation at either 193nm or 248nm. Similar changes in gene expression have been previously observed in cells treated with different carcinogens, including classical UV light (254nm) and phorbol esters. In contrast to the conventional UV light or laser radiation at 248nm, the 193nm radiation did not cause significant pyrimidine dimer formation, as determined by measurements of unscheduled DNA synthesis. However, both 193nm and 248nm radiation induced micronuclei formation, indicative of chromosome breakage. These data indicate that exposure of actively replicating human skin cells to sublethal doses of 193nm laser radiation may result in molecular changes associated with carcinogenesis.

  20. Radiation tolerance study of a commercial 65 nm CMOS technology for high energy physics applications

    NASA Astrophysics Data System (ADS)

    Ding, Lili; Gerardin, Simone; Bagatin, Marta; Bisello, Dario; Mattiazzo, Serena; Paccagnella, Alessandro

    2016-09-01

    This paper reports the radiation tolerance study of a commercial 65 nm technology, which is a strong candidate for the Large Hadron Collider applications. After exposure to 3 MeV protons till 1 Grad dose, the 65 nm CMOS transistors, especially the pMOSFETs, showed severe long-term degradation mainly in the saturation drain currents. There were some differences between the degradation levels in the nMOSFETs and the pMOSFETs, which were likely attributed to the positive charges trapped in the gate spacers. After exposure to heavy ions till multiple strikes, the pMOSFETs did not show any sudden loss of drain currents, the degradations in the characteristics were negligible.

  1. Core level photoionization on free sub-10-nm nanoparticles using synchrotron radiation

    SciTech Connect

    Meinen, Jan; Leisner, Thomas; Khasminskaya, Svetlana; Eritt, Markus; Antonsson, Egill; Langer, Burkhard; Ruehl, Eckart

    2010-08-15

    A novel instrument is presented, which permits studies on singly charged free nanoparticles in the diameter range from 1 to 30 nm using synchrotron radiation in the soft x-ray regime. It consists of a high pressure nanoparticle source, a high efficiency nanoparticle beam inlet, and an electron time-of-flight spectrometer suitable for probing surface and bulk properties of free, levitated nanoparticles. We show results from x-ray photoelectron spectroscopy study near the Si L{sub 3,2}-edge on 8.2 nm SiO{sub 2} particles prepared in a nanoparticle beam. The possible use of this apparatus regarding chemical reactions on the surface of nanometer-sized particles is highlighted. This approach has the potential to be exploited for process studies on heterogeneous atmospheric chemistry.

  2. Different oxidative stress response in keratinocytes and fibroblasts of reconstructed skin exposed to non extreme daily-ultraviolet radiation.

    PubMed

    Marionnet, Claire; Pierrard, Cécile; Lejeune, François; Sok, Juliette; Thomas, Marie; Bernerd, Françoise

    2010-08-10

    Experiments characterizing the biological effects of sun exposure have usually involved solar simulators. However, they addressed the worst case scenario i.e. zenithal sun, rarely found in common outdoor activities. A non-extreme ultraviolet radiation (UV) spectrum referred as "daily UV radiation" (DUVR) with a higher UVA (320-400 nm) to UVB (280-320 nm) irradiance ratio has therefore been defined. In this study, the biological impact of an acute exposure to low physiological doses of DUVR (corresponding to 10 and 20% of the dose received per day in Paris mid-April) on a 3 dimensional reconstructed skin model, was analysed. In such conditions, epidermal and dermal morphological alterations could only be detected after the highest dose of DUVR. We then focused on oxidative stress response induced by DUVR, by analyzing the modulation of mRNA level of 24 markers in parallel in fibroblasts and keratinocytes. DUVR significantly modulated mRNA levels of these markers in both cell types. A cell type differential response was noticed: it was faster in fibroblasts, with a majority of inductions and high levels of modulation in contrast to keratinocyte response. Our results thus revealed a higher sensitivity in response to oxidative stress of dermal fibroblasts although located deeper in the skin, giving new insights into the skin biological events occurring in everyday UV exposure.

  3. Stationary radiator in the 130 - 190 nm range based on a water vapour plasma

    SciTech Connect

    Shuaibov, Aleksandr K; Dashchenko, Arkadii I; Shevera, Igor V

    2001-06-30

    The characteristics of a continuous radiation source pumped by a longitudinal glow He - H{sub 2}O mixture discharge are presented. For a water vapour pressure of {approx}50 - 300 Pa and helium pressure of 1.0 - 8.0 kPa, the discharge under study was shown to emit radiation primarily in the 130 - 190 nm range. The optimal water vapour pressure lies in the range from 50 Pa to 150 Pa and the optimal partial helium pressure is 1.0 kPa. In the 3-50 mA range of the discharge current, the brightness of the main emission bands was observed to increase linearly with current. (laser applications and other topics in quantum electronics)

  4. Dissociative Fragmentation of Polyciclic Aromatic Hydrocarbons with 532 nm Laser Radiation

    NASA Astrophysics Data System (ADS)

    Cisneros, Carmen; Poveda, Juan Carlos; Combes, Manuel; Guerrero, Alfonso; Alvarez, Ignacio

    2007-06-01

    A pulsed supersonic jet of polyaromatic hydrocarbons mixed with noble gases was produced by adiabatic expansion in a high vacuum chamber (2x10-8 torr). The PAH's were heated in order to obtain their vapors. The pulsed mixtures interacted at 90 degrees with the 532 nm laser radiation from second harmonic of a Nd:YAG laser at intensities of 10^11-10^12 W.cm-2. The produced ions from photodissociation-photoionization processes were extracted, accelerated at 3.5 keV and analyzed in a time of flight mass spectrometer. In previous work (1) with 355 nm, only low mass ions were detected. At the present wave length, single charged ions were observed with compositional arrangements of the type CnHm^+1 with 3nm photodissociation. The carrier gas effect was also analyzed and differences in the ion currents were present as a consequence of the solvatation effectiveness of the van der Waals interaction. (1) Poveda J.C., Guerrero A., Alvarez I., Cisneros C. 17 Th Int. Mass Spectr. Conference. MoP -- 062 Prague Aug. 27 -- Sept. 1 2006

  5. Response of Two Legumes to Two Ultraviolet-B Radiation Regimes

    NASA Technical Reports Server (NTRS)

    Levy, Daniel L.; Skiles, J. W.

    2000-01-01

    Depletion of the stratospheric ozone layer has been directly linked to increased levels of UV radiation at the earth's surface. The purpose of this study was to evaluate the responses of soybean (Glycine max) and alfalfa (Medicago sativa) to increased UV-B radiation (280-320 nm). Soybean and alfalfa were grown successively in a growth chamber that provided UV-B intensities 45% above nominal summer field levels. Mylar-D (UVB opaque) and mono-acetate (UV-B transparent) films were used to establish the two UV-B treatments. Soybean grown under increased UV showed 21% smaller internodal lengths and higher concentrations of UV-B absorbing pigments (i.e. flavonoids) compared to plants grown under no UV. Significant results for alfalfa included 22% greater leaf flavonoid concentration under increased UV, 14% greater leaf chlorophyll concentration under no UV, and 32% greater above-ground biomass with no UV. These leguminous species possess mechanisms that protect against UV-B damage as indicated by increases in foliar concentrations of UV-B absorbing compounds. Alfalfa appears to be more sensitive to UV-B damage than soybean. Remote sensing of chlorophyll fluorescence may offer a means of monitoring UV-induced plant stress and damage.

  6. Kinetics of avoidance of simulated solar uv radiation by two arthropods

    SciTech Connect

    Barcelo, J.A.; Calkins, J.

    1980-12-01

    There is an increasing likelihood that the solar uv-B radiation (lambda = 280-320 nm) reaching the earth's surface will increase due to depletion of the stratospheric ozone layer. It is recognized that many organisms are insufficiently resistant to solar uv-B to withstand full summer sunlight and thus mechanisms which facilitate avoidance of solar uv-B exposure may have significance for the survival of sensitive species. There are many alternative pathways which would lead to avoidance of solar uv-B. We have investigated the dynamics of biological reactions to simulated solar uv-B radiation in two small arthropods, the two-spotted spider mite Tetranychus urticae Koch and the aquatic copepod Cyclops serrulatus. Observations of positioning and rate of movement were made; a mathematical formalism was developed which assisted in interpretation of the observations. Our observations suggest that, although avoidance would mitigate increased solar uv-B effects, even organisms which specifically reduce their uv-B exposure would encounter additional stress if ozone depletion does occur.

  7. A model for inactivation of microbes suspended in the atmosphere by solar ultraviolet radiation.

    PubMed

    Ben-David, Avishai; Sagripanti, Jose-Luis

    2010-01-01

    Solar ultraviolet (UV) light within 280-320 nm (UVB) is the primary cause for virus inactivation in the atmosphere. Only the effect of the direct component has been previously evaluated. We developed a simple regression model to estimate the inactivation of a virus due to direct (unscattered), diffuse (scattered) and total (direct + diffuse) components of solar UV (daily integrated irradiances). The model predicts the maximum number of radiation-days a virus will survive at a given altitude above the ground in rural and urban environments under clear skies. We explored the effect of several environmental variables: visibility, altitude and ground reflectivity. We found that the effect of diffuse radiation on virus inactivation was larger than the direct component. The diffuse irradiance increased with ground albedo (mainly due to reflection of the direct attenuated solar off the ground) and decreased with increased visibility (proportional to aerosol loading in the atmosphere). The diffuse component increased with altitude, but the ratio of diffuse to the total decreased with increased altitude, highlighting the importance of the diffuse component of UV near the ground. Our model may help public health studies in predicting and understanding the effect of environmental parameters on the survival of germs.

  8. The kinetics of avoidance of simulated solar UV radiation by two arthropods.

    PubMed

    Barcelo, J A; Calkins, J

    1980-12-01

    There is an increasing likelihood that the solar UV-B radiation (lambda = 280-320 nm) reaching the earth's surface will increase due to depletion of the stratospheric ozone layer. It is recognized that many organisms are insufficiently resistant to solar UV-B to withstand full summer sunlight and thus mechanisms which facilitate avoidance of solar UV-B exposure may have significance for the survival of sensitive species. There are many alternative pathways which would lead to avoidance of solar UV-B. We have investigated the dynamics of biological reactions to stimulated solar UV-B radiation in two small arthropods, the two-spotted spider mite Tetranychus urticae Koch and the aquatic copepod Cyclops serrulatus. Observations of positioning and rate of movement were made; a mathematical formalism was developed which assisted in interpretation of the observations. Our observations suggest that, although avoidance would mitigate increased solar UV-B effects, even organisms which specifically reduce their UV-B exposure would encounter additional stress if ozone depletion does occur.

  9. A Monolithic Active Pixel Sensor for ionizing radiation using a 180 nm HV-SOI process

    NASA Astrophysics Data System (ADS)

    Hemperek, Tomasz; Kishishita, Tetsuichi; Krüger, Hans; Wermes, Norbert

    2015-10-01

    An improved SOI-MAPS (Silicon On Insulator Monolithic Active Pixel Sensor) for ionizing radiation based on thick-film High Voltage SOI technology (HV-SOI) has been developed. Similar to existing Fully Depleted SOI-based (FD-SOI) MAPS, a buried silicon oxide inter-dielectric (BOX) layer is used to separate the CMOS electronics from the handle wafer which is used as a depleted charge collection layer. FD-SOI MAPS suffers from radiation damage such as transistor threshold voltage shifts due to charge traps in the oxide layers and charge states created at the silicon oxide boundaries (back gate effect). The X-FAB 180-nm HV-SOI technology offers an additional isolation by deep non-depleted implant between the BOX layer and the active circuitry which mitigates this problem. Therefore we see in this technology a high potential to implement radiation-tolerant MAPS with fast charge collection property. The design and measurement results from a first prototype are presented including charge collection in neutron irradiated samples.

  10. Response of Two Plant Species to Two Ultraviolet-B Radiation Regimes

    NASA Technical Reports Server (NTRS)

    Levy, Daniel L.; Skiles, J. W.; Peterson, David (Technical Monitor)

    1996-01-01

    The depleted stratospheric ozone layer has been directly linked to increased levels of ultraviolet radiation at the earth's surface. It is important to understand what effect this will have on plants. We tested the hypothesis that in response to increased UV-B radiation (280-320 man), soybean (Glycine max Merrill) and alfalfa (Mercado Saliva L.) would produce higher concentrations of flavonoids than plants screened from UV-B. Soybean and alfalfa plants were grown successively in a growth chamber that provided UV-B radiation intensities 45% above summer field levels. A wooden frame was used to suspend mylar-D film over one group of plants and mono-acetate film over another group. Mylar is opaque in the 280-316 nm range, and acetate absorbs most radiation from 280-290 nm and then reduces intensities in the 290-320 nm range by roughly 15%. Leaf chlorophyll concentration was determined with a Minolta SPAD-502 chlorophyll meter; the BRAD meter was calibrated with N,N- extractions. Flavonoids were extracted with an acidified methanol/water solution. Soybean grown under the acetate treatment showed 26% smaller internodal lengths and higher concentrations of flavonoids compared to plants grown under mylar. Significant results for alfalfa included 22% greater leaf flavonoid concentration under acetate, 14% greater leaf chlorophyll concentration under mylar, and 32% greater above-ground biomass under mylar. We found that increased UV-B radiation leads to increased production of UV-B absorbing compounds (i.e. flavonoids) in soybean and alfalfa leaves. This suggests that a protective mechanism in these plants is triggered by UV-B. In response, flavonoids are produced that absorb UV-B, and consequently decrease potentially damaging effects to the plants. In addition, we hypothesize that this flavonoid protection mechanism saturates at certain UV-B intensities.

  11. Sunlight suppressing rejection of 280- to 320-nm UV-radiation-induced skin tumors in mice

    SciTech Connect

    Morison, W.L.; Kelley, S.P.

    1985-02-01

    Repeated exposure of female C3H/HeNCR- mice to sunlight prevented the normal immunologic rejection of a UV-induced tumor. This systemic immunologic alteration was transferred to syngeneic lethally X-irradiated animals with lymphoid cells from mice exposed to sunlight. The lymphoid cells also were able to suppress the capacity of lymphoid cells from normal animals to reject a UV-induced tumor. The 295- to 320-nm wave band appeared to be responsible for this immunosuppressive effect of sunlight because suppression was prevented by filtration of the radiation through Mylar and by application of a sunscreen containing para-aminobenzoic acid. These observations may have importance in understanding the pathogenesis of sunlight-induced skin cancer in humans.

  12. Precision drilling of fused silica with 157-nm excimer laser radiation

    NASA Astrophysics Data System (ADS)

    Temme, Thorsten; Ostendorf, Andreas; Kulik, Christian; Meyer, Klaus

    2003-07-01

    μFor drilling fused silica, mechanical techniques like with diamond drills, ultrasonic machining, sand blasting or water jet machining are used. Also chemical techniques like laser assisted wet etching or thermal drilling with CO2-lasers are established. As an extension of these technologies, the drilling of micro-holes in fused silica with VUV laser radiation is presented here. The high absorption of the 157 nm radiation emitted by the F2 excimer laser and the short pulse duration lead to a material ablation with minimised impact on the surrounding material. Contrary to CO2-laser drilling, a molten and solidified phase around the bore can thus be avoided. The high photon energy of 7.9 eV requires either high purity nitrogen flushing or operation in vacuum, which also effects the processing results. Depending on the required precision, the laser can be used for percussion drilling as well as for excimer laser trepanning, by applying rotating masks. Rotating masks are especially used for high aspect ratio drilling with well defined edges and minimised debris. The technology is suitable particularly for holes with a diameter below 200 μm down to some microns in substrates with less than 200 μm thickness, that can not be achieved with mechanical methods. Drilling times in 200 μm fused silica substrates are in the range of ten seconds, which is sufficient to compete with conventional methods while providing similar or even better accuracy.

  13. Animal model for evaluation of topical photoprotection against ultraviolet A (320-380 nm) radiation

    SciTech Connect

    Chew, S.; DeLeo, V.A.; Harber, L.C.

    1987-10-01

    Recent studies reporting UVA (ultraviolet A radiation 320-380 nm) as an integral part of the cumulative sun-induced damage in human skin have prompted an interest in developing effective UVA photoprotective agents. The development of such compounds has been impeded by the absence of a clinically relevant animal model for evaluating their efficacy. This report describes the development and use of such a laboratory animal system. Selected concentrations of oxybenzone (2-hydroxy-4-methoxybenzophenone) in vehicle (0.1% to 6%) or vehicle alone were applied to the depilated dorsal skin of 30 Hartley strain female albino guinea pigs. The skin was irradiated with solar simulated UVA from a xenon light source. Acute radiation-induced damage was assayed by erythema grading and inhibition of (/sup 3/H)thymidine incorporation into epidermal DNA. Data from erythema grading studies indicated that a significant degree of photoprotection was achieved with 6%, 3%, and 1% solutions of benzophenone compared with the control vehicle; the 6% solution was significantly more photoprotective than the 3% and 1% solutions. A 6% solution afforded significant photoprotection when assayed by (/sup 3/H)thymidine incorporation.

  14. Generation of Terahertz Radiation from Fe-doped InGaAsP Using 800 nm to 1550 nm Pulsed Laser Excitation

    NASA Astrophysics Data System (ADS)

    Hatem, O.; Freeman, J. R.; Cunningham, J. E.; Cannard, P. J.; Robertson, M. J.; Linfield, E. H.; Davies, A. G.; Moodie, D. G.

    2016-05-01

    We demonstrate efficient generation of terahertz (THz) frequency radiation by pulsed excitation, at wavelengths between 800 and 1550 nm, of photoconductive (PC) switches fabricated using Fe-doped InGaAsP wafers, grown by metal organic chemical vapor deposition (MOCVD). Compared to our previous studies of Fe-doped InGaAs wafers, Fe:InGaAsP wafers exhibited five times greater dark resistivity to give a value of 10 kΩ cm, and Fe:InGaAsP PC switches produced five times higher THz power emission. The effect of Fe-doping concentration (between 1E16 and 1.5E17 cm-3) on optical light absorption (between 800 and 1600 nm), on resistivity, and on THz emission is also discussed.

  15. Cytomorphological changes in buccal mucosa of patients treated with low-level 1,064-nm laser radiation.

    PubMed

    Sezer, Ufuk; Aras, Mutan Hamdi; Aktan, Ali Murat; Cengiz, Beyhan; Ozkul, Nadide; Ay, Sinan

    2012-01-01

    The aim of this study was to examine the cytomorphological changes occurring in the buccal mucosa in patients treated with low-level 1,064-nm laser radiation. Seventeen individuals (12 males, five females) 18-24 years of age were included in the study. Low-level 1,064-nm laser radiation was applied to the right buccal mucosa near the premolar region; this therapy was repeated for 10 days. Buccal epithelial cells were collected from the right and left premolar regions of the individuals with a brush before and after therapy. The specimens collected from the left side were measured cytomorphometrically and used for the control group. Student's t test was used for statistical comparison of the values of the buccal epithelial cells collected from individuals; a p value < 0.05 was considered statistically significant. None of the patients showed any adverse reactions to the low-level 1,064-nm laser radiation therapy during application. There was no cytogenetic damage to the therapied or non-therapied regions in the buccal mucosa cells, as determined cytomorphologically. The results suggest that low-level 1,064-nm laser radiation therapy has no genotoxic potential. Within the limitations of this study, it can be concluded that low-level 1,064-nm laser radiation therapy may be used safely in dental treatments.

  16. UVB radiation as a potential selective factor favoring microcystin producing bloom forming Cyanobacteria.

    PubMed

    Ding, Yi; Song, Lirong; Sedmak, Bojan

    2013-01-01

    Due to the stratospheric ozone depletion, several organisms will become exposed to increased biologically active UVB (280-320 nm) radiation, not only at polar but also at temperate and tropical latitudes. Bloom forming cyanobacteria are exposed to UVB radiation on a mass scale, particularly during the surface bloom and scum formation that can persist for long periods of time. All buoyant species of cyanobacteria are at least periodically exposed to higher irradiation during their vertical migration to the surface that usually occurs several times a day. The aim of this study is to assess the influence on cyanobacteria of UVB radiation at realistic environmental intensities. The effects of two UVB intensities of 0.5 and 0.99 W/m(2) in up to 0.5 cm water depth were studied in vitro on Microcystis aeruginosa strains, two microcystin producing and one non-producing. After UVB exposure their ability to proliferate was estimated by cell counting, while cell fitness and integrity were evaluated using light microscopy, autofluorescence and immunofluorescence. Gene damage was assessed by TUNEL assay and SYBR Green staining of the nucleoide area. We conclude that UVB exposure causes damage to the genetic material, cytoskeletal elements, higher sedimentation rates and consequent cell death. In contrast to microcystin producers (PCC7806 and FACHB905), the microcystin non-producing strain PCC7005 is more susceptible to the deleterious effects of radiation, with weak recovery ability. The ecological relevance of the results is discussed using data from eleven years' continuous UVB radiation measurements within the area of Ljubljana city (Slovenia, Central Europe). Our results suggest that increased solar radiation in temperate latitudes can have its strongest effect during cyanobacterial bloom formation in spring and early summer. UVB radiation in this period may significantly influence strain composition of cyanobacterial blooms in favor of microcystin producers. PMID:24058503

  17. An ethanol extract derived from Bonnemaisonia hamifera scavenges ultraviolet B (UVB) radiation-induced reactive oxygen species and attenuates UVB-induced cell damage in human keratinocytes.

    PubMed

    Piao, Mei Jing; Hyun, Yu Jae; Cho, Suk Ju; Kang, Hee Kyoung; Yoo, Eun Sook; Koh, Young Sang; Lee, Nam Ho; Ko, Mi Hee; Hyun, Jin Won

    2012-12-14

    The present study investigated the photoprotective properties of an ethanol extract derived from the red alga Bonnemaisonia hamifera against ultraviolet B (UVB)-induced cell damage in human HaCaT keratinocytes. The Bonnemaisonia hamifera ethanol extract (BHE) scavenged the superoxide anion generated by the xanthine/xanthine oxidase system and the hydroxyl radical generated by the Fenton reaction (FeSO₄ + H₂O₂), both of which were detected by using electron spin resonance spectrometry. In addition, BHE exhibited scavenging activity against the 1,1-diphenyl-2-picrylhydrazyl radical and intracellular reactive oxygen species (ROS) that were induced by either hydrogen peroxide or UVB radiation. BHE reduced UVB-induced apoptosis, as shown by decreased apoptotic body formation and DNA fragmentation. BHE also attenuated DNA damage and the elevated levels of 8-isoprostane and protein carbonyls resulting from UVB-mediated oxidative stress. Furthermore, BHE absorbed electromagnetic radiation in the UVB range (280-320 nm). These results suggest that BHE protects human HaCaT keratinocytes against UVB-induced oxidative damage by scavenging ROS and absorbing UVB photons, thereby reducing injury to cellular components.

  18. [Methylene blue as a supressor of the genotoxic effect of ultraviolet radiation with a wavelength of 300-400 nm].

    PubMed

    Chistiakov, V A; Sazykina, M A; Kolenko, M A; Cherviakov, G G; Usatov, A V

    2009-03-01

    Ultraviolet radiation with a wavelength of 300-400 nm is characteristic of sunlight at the earth surface and causes DNA damage mediated by energy transfer to O2 with the transformation of the latter in the singlet state. In connection with this, scavengers of reactive oxygen species (ROSs) are potential protectors against the genotoxic effect of this kind of radiation. It was found that the methylene blue dye at doses differing by several orders of magnitude from those that are toxic for humans is able to suppress completely the SOS response induced by UV with a wavelength of 300--400 nm in Escherichia coli.

  19. [The effect of solar ultraviolet radiation (UVR) on induction of skin cancers].

    PubMed

    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. Skin cancers associated with long-term exposure to UV radiation are: basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and cutaneous malignant melanoma (CMM). The high risk of BCC development is related to acute and repeated exposure to UV causing sunburn. Molecular studies of BBC demonstrated disorders in sonic hedgehog (SHH) cell signaling regulation pathway, associated with the suppressor protein patched homolog 1 gene (PTCH1) mutations. The risk of the BCC development is related to the polymorphism of melanokortin-1 receptor gene (MC1R). Tumor P53 gene mutations observed in BCC cells has been classified as secondary genetic changes. In SCC cells UV-induced mutations were mostly related to P53 gene. Increased expression of cyclooxigenase- 2 gene (COX-2) plays a significant role in the development of SCC. Other pathogenetic factors include intensification of the synthesis of pro-inflammatory cytokines (tumor necrosis factor α (TNF-α), interleukin-1 α (IL-1α), IL-1β and IL-6). Currently, the role of UVB has been recognized in the pathogenesis of CMM. In CMM cells the following gene mutations were noted: cyclindependent kinase inhibitor 2A INK4A (p16INK4A), cyclin-dependent kinase 4 (CDK4), Ras, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and proto-oncogene B-Raf (BRAF). The BRAF gene mutations were observed in ~50% of CMM cases. Mutations of P53 gene are not characteristic of CMM cells. Med Pr 2016;67(2):255-266.

  20. [The effect of solar ultraviolet radiation (UVR) on induction of skin cancers].

    PubMed

    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. Skin cancers associated with long-term exposure to UV radiation are: basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and cutaneous malignant melanoma (CMM). The high risk of BCC development is related to acute and repeated exposure to UV causing sunburn. Molecular studies of BBC demonstrated disorders in sonic hedgehog (SHH) cell signaling regulation pathway, associated with the suppressor protein patched homolog 1 gene (PTCH1) mutations. The risk of the BCC development is related to the polymorphism of melanokortin-1 receptor gene (MC1R). Tumor P53 gene mutations observed in BCC cells has been classified as secondary genetic changes. In SCC cells UV-induced mutations were mostly related to P53 gene. Increased expression of cyclooxigenase- 2 gene (COX-2) plays a significant role in the development of SCC. Other pathogenetic factors include intensification of the synthesis of pro-inflammatory cytokines (tumor necrosis factor α (TNF-α), interleukin-1 α (IL-1α), IL-1β and IL-6). Currently, the role of UVB has been recognized in the pathogenesis of CMM. In CMM cells the following gene mutations were noted: cyclindependent kinase inhibitor 2A INK4A (p16INK4A), cyclin-dependent kinase 4 (CDK4), Ras, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and proto-oncogene B-Raf (BRAF). The BRAF gene mutations were observed in ~50% of CMM cases. Mutations of P53 gene are not characteristic of CMM cells. Med Pr 2016;67(2):255-266. PMID:27221301

  1. Researchers lack data on trends in UV radiation at Earth's surface

    SciTech Connect

    Zurer, P.S.

    1993-07-26

    Current anxiety about depletion of stratospheric ozone stems from the expected resulting increase in biologically damaging ultraviolet (UV) radiation at Earth's surface. Atmospheric ozone absorbs sunlight with wavelengths shorter than 320 nm--the highest-energy UV-B wavelengths (280-320 nm) that can damage DNA in living systems. But surprisingly, despite firm evidence the ozone layer is being eroded by chlorine and bromine from man-made compounds, very little information exists on how UV light intensity is changing. Solid data from Antarctica reveal that UV radiation soars under the ozone hole, where fully half of the atmospheric ozone is destroyed each spring. But elsewhere on the globe, where ozone has been thinning at a rate of a few percent per decade, the corresponding trends in UV intensity are not at all clear. In the late 1970s and early 1980s the problem of ozone depletion seemed solved. The US had banned the use of chlorofluorocarbons (CFCs) in aerosols. Model calculations were predicting CFCs would cause only a small loss of ozone by the second half of the 21st century. Costly monitoring of UV radiation commanded little attention. Attitudes began to change with the 1985 discovery of the Antarctic ozone hole. The National Science Foundation (NSF) established UV monitoring stations in the Antarctic in 1988, adding an Alaskan station in 1990. Both the Department of Agriculture (USDA) and the Environmental Protection Agency (EPA) have programs in the works that will eventually place monitoring stations across the US, but it will be many years before researchers have access to the kind of extensive database necessary to reliably evaluation long-term trends in UV intensity.

  2. Studies on the mechanism of systemic suppression of contact hypersensitivity by UVB radiation. II. Differences in the suppression of delayed and contact hypersensitivity in mice.

    PubMed

    Kripke, M L; Morison, W L

    1986-05-01

    Exposing mice to UV radiation in the UVB range (280-320 nm) causes a selective immune suppression that contributes to the development of UVB-induced skin cancers. Among the immune responses suppressed by UVB irradiation are contact and delayed hypersensitivity reactions to haptens administered at unexposed sites. In these studies we provide evidence that delayed and contact hypersensitivity to the same hapten are not equivalent reactions and that they are suppressed in UVB-irradiated mice by 2 different mechanisms. This conclusion is based on the findings that: suppression of contact hypersensitivity could not be overcome by immunizing UVB-irradiated mice with hapten-coupled antigen-presenting cells derived from normal donors; and treatment of UVB-irradiated mice with methylprednisolone before immunization prevented the suppression of delayed hypersensitivity but had no effect on the suppression of contact hypersensitivity. The decreased ability to induce contact hypersensitivity in UVB-irradiated mice could be transferred to x-irradiated mice by reconstituting them with spleen cells from UVB-irradiated donors. The induction of hapten-specific suppressor cells, however, required both UVB irradiation and priming with hapten. Based on these results, we postulate that UVB irradiation induces a population of suppressor-inducer cells with specificity for a modified skin antigen and that this antigen serves as a carrier molecule for haptens that induce contact hypersensitivity and for tumor-specific transplantation antigens on UVB-induced tumors. PMID:3745963

  3. Responses of antioxidant enzyme and photosynthesis in rape seedling to the combined stresses of acid rain and ultraviolet-B radiation.

    PubMed

    Liang, Chan-juan; Huang, Xiao-hua; Tao, Wen-yi; Zhou, Qing

    2005-01-01

    Effects of the simulated acid rain (AR) and ultraviolet-B (UV-B, 280-320 nm) radiation with a single or two ways simultaneously (AR + UV-B) on the antioxidant enzyme and photosynthesis of the rape seedlings were investigated by the hydroponic culture. The results of static experiment indicated that the tolerance of rape seedling to single stress (AR or UV-B) is stronger than that to dual stresses (AR + UV-B). Furthermore, the dual stresses had additive effect on catalase activity, and a synergistic effect on MDA content, net photosynthesis rate, water use efficiency as well as intercellular CO2 concentration. Meanwhile, it has an independent effect on chlorophyll content, stomatal conductance, and transpiration rate as well as membrane permeability. During 64 h restoration course, the dynamic change in the curves of physiological and biochemical indices were not identical, and none of them show a simple linear variation. According to the static and dynamic experiments, it was found that a responsive sequence of catalase activity, membrane permeability, MDA content and photosynthetic characteristics to the above-mentioned stresses was as follows: AR + UV-B > UV-B > AR.

  4. Radiation Performance of 1 Gbit DDR SDRAMs Fabricated in the 90 nm CMOS Technology Node

    NASA Technical Reports Server (NTRS)

    Ladbury, Raymond L.; Gorelick, Jerry L.; Berg, M. D.; Kim, H.; LaBel, K.; Friendlich, M.; Koga, R.; George, J.; Crain, S.; Yu, P.; Reed, R. A.

    2006-01-01

    We present Single Event Effect (SEE) and Total Ionizing Dose (TID) data for 1 Gbit DDR SDRAMs (90 nm CMOS technology) as well as comparing this data with earlier technology nodes from the same manufacturer.

  5. Effects of ultraviolet-B radiation on fungal disease development in Cucumis sativus

    SciTech Connect

    Orth, A.B.; Teramura, A.H.; Sisler, H.D. )

    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.

  6. ED50 determination of corneal lesions produced by 1318-nm laser radiation pulses

    NASA Astrophysics Data System (ADS)

    Ketzenberger, Bryan K.; Johnson, Thomas E.; Wild, Steven P.; Pletcher, Kenneth B.; Roach, William P.

    2001-05-01

    High-energy use of 1318 nm laser systems is becoming more prevalent in military and industrial settings. Threshold, ED50, exposure data and mechanism of laser-tissue interaction need to be determined for this wavelength using appropriate animal models that allow for extrapolation to control human exposures. Threshold, ED50, exposure data at 1318 nm for retinal and corneal injury have previously been undertaken and reported for rhesus monkeys. Using comparable methods, we examine exposure data at 1318 nm to determine the ED50 and laser-tissue interaction in the rabbit model to evaluate cornea. We present preliminary data for the ED50 threshold on the cornea from exposure to 1318 nm single laser pulses. Delivery of laser energy is accomplished using an Nd:YAG system producing 1318 nm light in the 0.5 millisecond time exposure regime and in the range of 0 to 500 mJ. Results from this work will aid in the establishment of safety standards for near infrared laser systems.

  7. Photoinduced absorption and refractive-index induction in phosphosilicate fibres by radiation at 193 nm

    SciTech Connect

    Rybaltovsky, A A; Sokolov, V O; Plotnichenko, V G; Lanin, Aleksei V; Semenov, S L; Dianov, Evgenii M; Gur'yanov, A N; Khopin, V F

    2007-04-30

    The photoinduced room-temperature-stable increase in the refractive index by {approx}5x10{sup -4} at a wavelength of 1.55 {mu}m was observed in phosphosilicate fibres without their preliminary loading with molecular hydrogen. It is shown that irradiation of preliminary hydrogen-loaded fibres by an ArF laser at 193 nm enhances the efficiency of refractive-index induction by an order of magnitude. The induced-absorption spectra of preforms with a phosphosilicate glass core and optical fibres fabricated from them are studied in a broad spectral range from 150 to 5000 nm. The intense induced-absorption band ({approx}800 cm{sup -1}) at 180 nm is found, which strongly affects the formation of the induced refractive index. The quantum-chemical model of a defect related to this band is proposed. (optical fibres)

  8. Frequency conversion concepts for the efficient generation of high power 935 - 942 nm laser radiation

    NASA Astrophysics Data System (ADS)

    Rhee, H.; Riesbeck, T.; Kallmeyer, F.; Strohmaier, S.; Eichler, H. J.; Treichel, R.; Petermann, K.

    2006-02-01

    The three-dimensional measurement of the global water vapor distribution in the atmosphere considerably improves the reliability of the weather forecast and climate modeling. A spaceborne Differential Absorption Lidar (DIAL) is able to per-form this task by use of suitable absorption lines of the broad absorption spectrum of water vapor. Because no interference with the absorption of other molecules exists, the range of 935/936 nm, 942/943 nm are the most preferred wavelength ranges for a water vapor DIAL. The challenge is to develop a dedicated efficient high power laser source emitting at these wavelengths. The comparison between frequency converters based on stimulated Raman scattering (SRS) and Ti:Sapphire and the directly generated Mixed Garnet laser shows the favorable properties of each concept and helps to evaluate the most suitable concept. Development of Raman frequency converters for high pulse energies concentrates on linear resonator de-signs and seeding using the Raman material as a direct amplifier based on Raman four-wave-mixing. In addition a seeded and frequency stabilized pulsed Ti:Sapphire laser system with output pulses up to 22 mJ injection-seeded at the water vapor absorption line at 935.684 nm with a spectral purity up to 99.9 % has been developed. Direct generation of the wavelengths 935/936 nm and 942/943 nm required for water vapor detection is possible with diode-pumped, Nd-doped YGG- and GSAG-crystals. First experiments resulted in pulse energies of 18 mJ in Q-switched and 86 mJ in free-running operation at 942 nm wavelength.

  9. NM23 deficiency promotes metastasis in a UV radiation-induced mouse model of human melanoma.

    PubMed

    Jarrett, Stuart G; Novak, Marian; Harris, Nathan; Merlino, Glenn; Slominski, Andrezj; Kaetzel, David M

    2013-01-01

    Cutaneous malignant melanoma is the most lethal form of skin cancer, with 5-year survival rates of <5 % for patients presenting with metastatic disease. Mechanisms underlying metastatic spread of UVR-induced melanoma are not well understood, in part due to a paucity of animal models that accurately recapitulate the disease in its advanced forms. We have employed a transgenic mouse strain harboring a tandem deletion of the nm23-m1 and nm23-m2 genes to assess the combined contribution of these genes to suppression of melanoma metastasis. Crossing of the nm23-h1/nm23-h2 knockout in hemizygous-null form ([m1m2](+/-)) to a transgenic mouse strain (hepatocyte growth factor/scatter factor-overexpressing, or HGF(+) strain) vulnerable to poorly-metastatic, UVR-induced melanomas resulted in UVR-induced melanomas with high metastatic potential. Metastasis to draining lymph nodes was seen in almost all cases of back skin melanomas, while aggressive metastasis to lung, thoracic cavity, liver and bone also occurred. Interestingly, no differences were observed in the invasive characteristics of primary melanomas of HGF(+) and HGF(+) × [m1m2](+/-) strains, with both exhibiting invasion into the dermis and subcutis, indicating factors other than simple invasive activity were responsible for metastasis of HGF(+) × [m1m2](+/-) melanomas. Stable cell lines were established from the primary and metastatic melanoma lesions from these mice, with HGF(+) × [m1m2](+/-) lines exhibiting increased single cell migration and genomic instability. These studies demonstrate for the first time in vivo a potent metastasis suppressor activity of NM23 in UVR-induced melanoma, and have provided new tools for identifying molecular mechanisms that underlie melanoma metastasis.

  10. Formation of Micro and Nano Structures Using VUV 157 nm Laser Radiation

    SciTech Connect

    Walton, C. D.; Cockcroft, S.

    2010-10-08

    We report on laser ablation experiments on micro and nano size composite structures. The surface of CR-39 and polycarbonate has been intentionally seeded with silicon carbide and silver nanowires and subsequently laser irradiated at a wavelength of 157 nm. We show scanning electron micrograph images of prismatic and conical structures produced by laser ablation and discuss a shape transformation from a prismatic to a conical structure.

  11. Carcinogenesis induced by UVA (365-nm) radiation: the dose-time dependence of tumor formation in hairless mice.

    PubMed

    de Laat, A; van der Leun, J C; de Gruijl, F R

    1997-05-01

    Although ultraviolet B (UVB wavelengths 280-315 nm) dominates the carcinogenic effect of sunlight, ultraviolet A (UVA 315-400 nm) is estimated to contribute 10-20% to the carcinogenic dose; a substantial background that is not affected by a depletion of the ozone layer. Furthermore, certain high-power modern tanning lamps emit mainly long wave UVA (UVA1; 340-400 nm). For a proper risk estimate of UVA exposure its carcinogenicity relative to that of UVB exposure needs to be determined more accurately. To this end we determined the dose-time relationship for skin tumor induction in hairless mice that were irradiated daily with custom-made Philips 365-nm sources. Irradiation of the group exposed to the highest of the four daily doses (430, 240, 140 and 75 kJ/m2) had to be discontinued because severe scratching set in after 3 months (no tumors). In the lower dose-groups the prevalence curves for skin carcinomas (percentage of tumor-bearing mice versus logarithm of time) ran virtually parallel, and were similar to those found with daily UVB exposure. However, the relationship between the daily dose (D) and the median tumor induction time (t50) appeared to differ: with UVB we found that t50 D(r) = constant, with r = 0.6, whereas with UVA1 we found r approximately 0.4. This would imply that 365-nm carcinogenesis shows less of a dose-dependency than UVB carcinogenesis, and that 365-nm radiation becomes more carcinogenic, relative to UVB, as the daily doses are lowered. This relative shift at low doses complicates extrapolation of UVB to UVA risks in humans. Based on the t50 from the lowest dose-group we found that the carcinogenicity at 365 nm (per J/m2) is 0.9 x 10(-4) times that at 293 nm, the wavelength of maximum carcinogenicity in hairless mice. This result for 365-nm carcinogenicity falls well within the margins of error of the wavelength dependency that was estimated earlier from experiments with broadband UV sources.

  12. Corneal thermal damage threshold dependence on the exposure duration for near-infrared laser radiation at 1319 nm

    NASA Astrophysics Data System (ADS)

    Wang, Jiarui; Jiao, Luguang; Chen, Hongxia; Yang, Zaifu; Hu, Xiangjun

    2016-01-01

    The corneal damage effects induced by 1319-nm transitional near-infrared laser have been investigated for years. However, the damage threshold dependence on exposure duration has not been revealed. The in vivo corneal damage thresholds (ED50s) were determined in New Zealand rabbits for 1319-nm laser radiation for exposure durations from 75 ms to 10 s. An additional corneal ED50 was determined at 1338 nm for a 5-ms exposure. The incident corneal irradiance diameter was fixed at 2 mm for all exposure conditions to avoid the influence of spot size on threshold. The ED50s given in terms of the corneal radiant exposure for exposure durations of 5 ms, 75 ms, 0.35 s, 2 s, and 10 s were 39.4, 51.5, 87.2, 156.3, and 311.1 J/cm2, respectively. The 39.4 J/cm2 was derived from the ED50 for 1338 nm (27.0 J/cm2). The ED50s for exposure durations of 75 ms to 10 s were correlated by a power law equation, ED50=128.9t0.36 in J/cm2, where t was the input in the unit of second, with correlation coefficient (R) of 0.997. Enough safe margins existed between the ED50s and the maximum permitted exposures from current laser safety standard.

  13. Comparison of Mg-based multilayers for solar He II radiation at 30.4 nm wavelength

    SciTech Connect

    Zhu Jingtao; Zhou Sika; Li Haochuan; Huang Qiushi; Wang Zhanshan; Le Guen, Karine; Hu, Min-Hui; Andre, Jean-Michel; Jonnard, Philippe

    2010-07-10

    Mg-based multilayers, including SiC/Mg, Co/Mg, B4C/Mg, and Si/Mg, are investigated for solar imaging and a He II calibration lamp at a 30.4 nm wavelength. These multilayers were fabricated by a magnetron sputtering method and characterized by x-ray reflection. The reflectivities of these multilayers were measured by synchrotron radiation. Near-normal-incidence reflectivities of Co/Mg and SiC/Mg multilayer mirrors are as high as 40.3% and 44.6%, respectively, while those of B4C/Mg and Si/Mg mirrors are too low for application. The measured results suggest that SiC/Mg, Co/Mg multilayers are promising for a 30.4 nm wavelength.

  14. Comparison of radiation degradation induced by x-ray and 3-MeV protons in 65-nm CMOS transistors

    NASA Astrophysics Data System (ADS)

    Ding, Lili; Gerardin, Simone; Bagatin, Marta; Bisello, Dario; Mattiazzo, Serena; Paccagnella, Alessandro

    2016-09-01

    The total ionizing dose (TID) response of 65-nm CMOS transistors is studied by 10-keV x-ray and 3-MeV protons up to 1 Grad (SiO2) total dose. The degradation levels induced by the two radiation sources are different to some extent. The main reason is the interface dose enhancement due to the thin gate oxide and the low energy photons. The holes’ recombination also contributes to the difference. Compared to these two mechanisms, the influence of the dose rate is negligible.

  15. Radiation-enhanced gate-induced-drain-leakage current in the 130 nm partially-depleted SOI pMOSFET

    NASA Astrophysics Data System (ADS)

    Peng, Chao; Hu, Zhiyuan; Ning, Bingxu; Dai, Lihua; Bi, Dawei; Zhang, Zhengxuan

    2015-04-01

    The total ionizing dose (TID) effect of the pMOSFET from 130 nm partially-depleted silicon-on-insulator (PDSOI) is investigated. The data obtained from 60Co γ-ray irradiation experiments indicate that input/output (I/O) device is more susceptible to TID effect than the core device. An anomalous off-state leakage increase is observed for I/O pMOSFET when drain is biased at a high voltage after irradiation. It is proved that this radiation-induced leakage relates to the enhanced gate-induce-drain-leakage (GIDL). Both the radiation-induced interface traps at the gate-oxide/body interface and the oxide trapped charges in the buried oxide (BOX) are responsible for the growth of the leakage current. These conclusions are also verified by the TCAD simulations. The isothermal annealing can recover the leakage current to the pre-irradiation level.

  16. Intraspecific variations in growth, yield and photosynthesis of sorghum varieties to ambient UV (280-400 nm) radiation.

    PubMed

    Kataria, Sunita; Guruprasad, K N

    2012-11-01

    A field study was conducted to investigate the impact of ambient solar UV on the various growth, physiological and yield parameters of four sorghum (Sorghum bicolor L.) varieties-Indore-12, Indore-26, CSV-23 and Indore-27 by excluding either UV-B (<315 nm) or UV-A/B (<400 nm) components of solar spectrum. Exclusion of UV significantly enhanced plant height, area and specific leaf weight of flag leaf, biomass accumulation, yield parameters and harvest index in all the sorghum varieties. Chlorophyll b was significantly enhanced and chlorophyll a increased to a lesser extent, UV-B absorbing substances and chlorophyll a/b ratio were significantly decreased by the exclusion of solar UV. The enhancement in the vegetative growth and yield by UV exclusion might be linked to the remarkable increase in rate of photosynthesis in sorghum varieties. The magnitude of the response was high in I-26 and I-27 as compared to CSV-23 and I-12 after exclusion of solar UV. All the varieties of sorghum had a negative cumulative stress response index (CSRI), the sensitivity of the sorghum varieties was in the following sequence I-12>CSV-23>I-26>I-27. Thus I-27 was the most sensitive and I-12 the least sensitive variety to present level of solar UV radiation. The differences in UV sensitivity identified among sorghum varieties might be useful in breeding programs for increased tolerance to UV-B radiation.

  17. Impact of ultraviolet-B radiation on planktonic fish larvae: alteration of the osmoregulatory function.

    PubMed

    Sucré, Elliott; Vidussi, Francesca; Mostajir, Behzad; Charmantier, Guy; Lorin-Nebel, Catherine

    2012-03-01

    Coastal marine ecosystems are submitted to variations of several abiotic and biotic parameters, some of them related to global change. Among them the ultraviolet-B (UV-B) radiation (UVBR: 280-320 nm) may strongly impact planktonic fish larvae. The consequences of an increase of UVBR on the osmoregulatory function of Dicentrarchus labrax larvae have been investigated in this study. In young larvae of D. labrax, as in other teleosts, osmoregulation depends on tegumentary ion transporting cells, or ionocytes, mainly located on the skin of the trunk and of the yolk sac. As early D. labrax larvae passively drift in the top water column, ionocytes are exposed to solar radiation. The effect of UVBR on larval osmoregulation in seawater was evaluated through nanoosmometric measurements of the blood osmolality after exposure to different UV-B treatments. A loss of osmoregulatory capability occured in larvae after 2 days of low (50 μWcm(-2): 4 h L/20 h D) and medium (80 μWcm(-2): 4 h L/20 h D) UVBR exposure. Compared to control larvae kept in the darkness, a significant increase in blood osmolality, abnormal behavior and high mortalities were detected in larvae exposed to UVBR from 2 days on. At the cellular level, an important decrease in abundance of tegumentary ionocytes and mucous cells was observed after 2 days of exposure to UVBR. In the ionocytes, two major osmoeffectors were immunolocalized, the Na+/K(+)-ATPase and the Na+/K+/2Cl- cotransporter. Compared to controls, the fluorescent immunostaining was lower in UVBR-exposed larvae. We hypothesize that the impaired osmoregulation in UVBR-exposed larvae originates from the lower number of tegumentary ionocytes and mucous cells. This alteration of the osmoregulatory function could negatively impact the survival of young larvae at the surface water exposed to UVBR.

  18. Analysis of the efficiency of using 1265-nm cw laser radiation for initiating oxidative stress in the tissue of a solid malignant tumour

    SciTech Connect

    Gening, T P; Voronova, O S; Dolgova, D R; Abakumova, T V; Zolotovskii, Igor' O; Sholokhov, E M; Kurkov, Andrei S; Gening, S O

    2012-09-30

    The possibility of laser initiation of oxidative stress was studied by the example of the tumour tissue of cervix. The laser facility with the operating wavelength 1265 nm that falls within the region of resonance absorption of molecular oxygen was used for initiation. The source of radiation in the experiments was a fibre SRS laser with the repeated cascade conversion of radiation of a 1125-nm ytterbium laser. (optical fibres, lasers and amplifiers. properties and applications)

  19. Near ultraviolet radiation (280-400 nm): Direct and indirect effects on microbial pathogens

    SciTech Connect

    Asthana, A.

    1993-01-01

    Responses of pigmented pathogenic fungi and E. coli strains differing in DNA repair and catalase proficiency to direct and indirect effects of ultraviolet radiation were evaluated. Pigments in the four fungal pathogens of Citrus differed in their ability to protect against direct UV and damage by UV-A -mediated phototoxins of both host and non-host origin. UV-A and UV-B did not inactivate the fungal species. Differential protection in wild type strains of the two Fusarium spp. and in the wild type strains of the two Penicilium spp. against UV-C was observed. Wild type and mutants with altered coloration in Penicilium spp. protected to varying extent against both [alpha]-T and 8-MOP in the presence of UV-A. UV-B irradiation of E. coli resulted in inactivation of strains deficient in DNA excision repair. Plasmid DNA damaged in vitro by UV-B from lamp systems as well as by sunlight, and transformed in vivo into bacterial cells lacking specific nucleases showed reduced transformation in DNA excision repair strains. UV-B enriched wavelengths isolated from a solar simulator affected plasmid DNA in a similar manner as UV-B from lamp systems. Sunlight, however affected the membrane of whole cells. Concentration of foliar furanocoumarins of Citrus jambhiri decreased with UV-B irradiation. Phototoxicity to Fusarium spp. was accounted for, in part, by furanocoumarins, psoralen and bergapten (5-MOP) and others. Pure psoralen and 5-MOP affected both Fusarium spp. similarly and carotenoids protected only partially in the wild type strains. Citrus targetted the cell membrane in Fusarium spp.l and in E. coli strains; carotenoids in both of which protected against such damage. Loss in structural integrity of plasmid DNA when treated with citral and UV-A correlated with loss in transforming activity. Biological damage to membrane and DNA was due to the production of hydrogen peroxide. Fruit-rot pathogens Penicilium spp. were not affected by either furanocoumarins or citrals.

  20. Ultraviolet radiation and immunology: something new under the sun--presidential address.

    PubMed

    Kripke, M L

    1994-12-01

    The carcinogenic activity of solar radiation has been known for nearly a century. However, within the past few years, we have realized that exposing the skin to sunlight also has profound immunological effects on the host and that these immunological changes can contribute to the development of skin cancer and alter host resistance to infectious diseases. These findings have led to the development of a new field of research, termed photoimmunology, which is concerned with the effects of UV radiation on immunological processes. Our interest in this field arose from studies on the antigenic properties of skin cancers induced in mice by chronic exposure to UV-B (280-320 nm) radiation. These cancers are highly antigenic and many are immunologically rejected upon transplantation to normal syngeneic recipients. In studying how these cancers were able to survive and grow in the primary host, we discovered that exposing the skin to UV radiation altered some types of immune responses, including the immune response against skin cancers. Studies on the nature and mechanism of the immunological alterations brought about by exposure to UV radiation suggested that UV-induced DNA damage triggers a cascade of events, leading ultimately to a state of antigen-specific, systemic T lymphocyte-mediated immunosuppression. Key components of this cascade are epidermal cytokines, which modulate the immune response to antigens introduced into the UV-irradiated host and divert the response toward a state of specific immunosuppression. The finding that UV radiation can redirect the immune response from an effector to a suppressor pathway has raised the possibility that immune responses to infectious diseases might also be influenced by exposure of the host to UV radiation. Interest in the health consequences of stratospheric ozone depletion, with its attendant increase in solar UV-B radiation, has stimulated recent investigations on the effects of UV radiation on the pathogenesis of

  1. Ultraviolet radiation and immunology: something new under the sun--presidential address.

    PubMed

    Kripke, M L

    1994-12-01

    The carcinogenic activity of solar radiation has been known for nearly a century. However, within the past few years, we have realized that exposing the skin to sunlight also has profound immunological effects on the host and that these immunological changes can contribute to the development of skin cancer and alter host resistance to infectious diseases. These findings have led to the development of a new field of research, termed photoimmunology, which is concerned with the effects of UV radiation on immunological processes. Our interest in this field arose from studies on the antigenic properties of skin cancers induced in mice by chronic exposure to UV-B (280-320 nm) radiation. These cancers are highly antigenic and many are immunologically rejected upon transplantation to normal syngeneic recipients. In studying how these cancers were able to survive and grow in the primary host, we discovered that exposing the skin to UV radiation altered some types of immune responses, including the immune response against skin cancers. Studies on the nature and mechanism of the immunological alterations brought about by exposure to UV radiation suggested that UV-induced DNA damage triggers a cascade of events, leading ultimately to a state of antigen-specific, systemic T lymphocyte-mediated immunosuppression. Key components of this cascade are epidermal cytokines, which modulate the immune response to antigens introduced into the UV-irradiated host and divert the response toward a state of specific immunosuppression. The finding that UV radiation can redirect the immune response from an effector to a suppressor pathway has raised the possibility that immune responses to infectious diseases might also be influenced by exposure of the host to UV radiation. Interest in the health consequences of stratospheric ozone depletion, with its attendant increase in solar UV-B radiation, has stimulated recent investigations on the effects of UV radiation on the pathogenesis of

  2. Ocular temperature elevation induced by threshold in vivo exposure to 1090-nm infrared radiation and associated heat diffusion

    NASA Astrophysics Data System (ADS)

    Yu, Zhaohua; Schulmeister, Karl; Talebizadeh, Nooshin; Kronschläger, Martin; Söderberg, Per G.

    2014-10-01

    An in vivo exposure to 197 W/cm2 1090-nm infrared radiation (IRR) requires a minimum 8 s for cataract induction. The present study aims to determine the ocular temperature evolution and the associated heat flow at the same exposure conditions. Two groups of 12 rats were unilaterally exposed within the dilated pupil with a close to collimated beam between lens and retina. Temperature was recorded with thermocouples. Within 5 min after exposure, the lens light scattering was measured. In one group, the temperature rise in the exposed eye, expressed as a confidence interval (0.95), was 11±3°C at the limbus, 16±6°C in the vitreous behind lens, and 16±7°C on the sclera next to the optic nerve, respectively. In the other group, the temperature rise in the exposed eye was 9±1°C at the limbus and 26±11°C on the sclera next to the optic nerve, respectively. The difference of forward light scattering between exposed and contralateral not exposed eye was 0.01±0.09 tEDC. An exposure to 197 W/cm2 1090-nm IRR for 8 s induces a temperature increase of 10°C at the limbus and 26°C close to the retina. IRR cataract is probably of thermal origin.

  3. Ocular temperature elevation induced by threshold in vivo exposure to 1090-nm infrared radiation and associated heat diffusion.

    PubMed

    Yu, Zhaohua; Schulmeister, Karl; Talebizadeh, Nooshin; Kronschläger, Martin; Söderberg, Per G

    2014-01-01

    An in vivo exposure to 197  W/cm 2 1090-nm infrared radiation (IRR) requires a minimum 8 s for cataract induction. The present study aims to determine the ocular temperature evolution and the associated heat flow at the same exposure conditions. Two groups of 12 rats were unilaterally exposed within the dilated pupil with a close to collimated beam between lens and retina. Temperature was recorded with thermocouples. Within 5 min after exposure, the lens light scattering was measured. In one group, the temperature rise in the exposed eye, expressed as a confidence interval (0.95), was 11±3°C at the limbus, 16±6°C in the vitreous behind lens, and 16±7°C on the sclera next to the optic nerve, respectively. In the other group, the temperature rise in the exposed eye was 9±1°C at the limbus and 26±11°C on the sclera next to the optic nerve, respectively. The difference of forward light scattering between exposed and contralateral not exposed eye was 0.01±0.09 tEDC. An exposure to 197  W/cm 2 1090-nm IRR for 8 s induces a temperature increase of 10°C at the limbus and 26°C close to the retina. IRR cataract is probably of thermal origin.

  4. Dual calibrated dosimeter for simultaneous measurements of erythemal and vitamin D effective solar ultraviolet radiation.

    PubMed

    Wainwright, L; Parisi, A V; Downs, N

    2016-04-01

    A miniaturized ultraviolet radiation (UV) dosimeter based on polyphenylene oxide (PPO) has been dual calibrated for both erythemal and vitamin D effective exposures (UVB 280 - 320 nm) over extended periods up to five days. Optimal human health requires a balanced amount of UVB exposure as both too much and too little have different but serious potential health consequences. Dosimetry is an established method of measuring specific UV exposures to an object or subject. PPO dosimeters have previously been used to measure the erythemally effective UV exposure. An extension of this use is to dual calibrate the miniaturized dosimeter which will also enable measurement of vitamin D effective exposures. By calibration to the erythemal and vitamin D effective action spectra, PPO dosimeters were able to record both types of biologically effective exposure as both are active within the UVB waveband. Dose response tests were conducted in each season by exposure to solar UV with the corresponding dual calibrations made for each season. The calibration provided an R(2) of 0.95-0.99 for erythemal UV and an R(2) of 0.99 for vitamin D effective UV. The successful outcome of this testing has established that PPO is suitable for use as a long term, dual calibrated dosimeter provided the film is seasonally calibrated. This enables one dosimeter to provide two sets of exposure results. The combination of dual calibration and the long term exposure potential of PPO makes the PPO dosimeter more versatile and increases the scope of UV field research on erythemal UV and vitamin D effective UV in the future. PMID:26878218

  5. Generation of 1.5 W average power, 18 kHz repetition rate coherent mid-ultraviolet radiation at 271.2 nm.

    PubMed

    Biswal, Ramakanta; Agrawal, Praveen K; Dixit, Sudhir K; Nakhe, Shankar V

    2015-11-10

    This paper presents to our knowledge a first time study on the generation of 1.5 W average power, 18 kHz repetition rate coherent mid-ultraviolet (UV) radiation at 271.2 nm. The work is based on frequency summing of coherent green (G: 510.6 nm) and yellow (Y: 578.2 nm) radiations of a copper-HBr laser in a β-barium borate crystal. Average and peak sum frequency conversion efficiencies of about 13% and 16%, respectively, are obtained. The sum frequency results are experimentally analyzed in terms of the extent of matching of green and yellow pump radiations in space, time, and frequency domains. The result is of high significance for many applications in photonics components fabrication, semiconductor technology, and spectroscopy. PMID:26560794

  6. A dual-wavelength amplifier that enables the simultaneous chirped-pulse amplification of femtosecond 1562 nm pulses and continuous wave 1064 nm radiation for applications in difference frequency generation

    NASA Astrophysics Data System (ADS)

    Krzempek, Karol; Sobon, Grzegorz; Sotor, Jaroslaw; Abramski, Krzysztof

    2016-10-01

    We present the first demonstration of a chirped-pulse amplification system that enables the simultaneous amplification of femtosecond pulses from the erbium band and continuous wave radiation centered at 1064 nm. The setup generated 470 fs laser pulses, centered at 1562 nm, with an average output power of 590 mW. By exploiting the unique dual-wavelength design an additional gain of 18.08 dB was achieved for the auxiliary 1064 nm seed signal required in the frequency conversion part of the setup. The usability of the constructed source was verified by setting up a difference frequency generation experiment in which the unique characteristics of the mode-locked laser pulses were transferred into the mid-infrared wavelength region.

  7. Protection against ultraviolet-B radiation-induced local and systemic suppression of contact hypersensitivity and edema responses in C3H/HeN mice by green tea polyphenols.

    PubMed

    Katiyar, S K; Elmets, C A; Agarwal, R; Mukhtar, H

    1995-11-01

    Exposure of skin to UV radiation can cause diverse biological effects, including induction of inflammation, alteration in cutaneous immune cells and impairment of contact hypersensitivity (CHS) responses. Our laboratory has demonstrated that oral feeding as well as topical application of a polyphenolic fraction isolated from green tea (GTP) affords protection against the carcinogenic effects of UVB (280-320 nm) radiation. In this study, we investigated whether GTP could protect against UVB-induced immunosuppression and cutaneous inflammatory responses in C3H mice. Immunosuppression was assessed by contact sensitization with 2,4-dinitrofluorobenzene applied to UVB-irradiated skin (local suppression) or to a distant site (systemic suppression), while double skin-fold swelling was used as the measure of UVB-induced inflammation. Topical application of GTP (1-6 mg/animal), 30 min prior to or 30 min after exposure to a single dose of UVB (2 kJ/m2) resulted in significant protection against local (25-90%) and systemic suppression (23-95%) of CHS and inflammation in mouse dorsal skin (70-80%). These protective effects were dependent on the dose of GTP employed; increasing the dose (1-6 mg/animal) resulted in an increased protective effect (25-93%). The protective effects were also dependent on the dose of UVB (2-32 kJ/m2). Among the four major epicatechin derivatives present in GTP, (-)-epigallocatechin-3-gallate, the major constituent in GTP, was found to be the most effective in affording protection against UVB-caused CHS and inflammatory responses. Our study suggests that green tea, specifically polyphenols present therein, may be useful against inflammatory dermatoses and immunosuppression caused by solar radiation.

  8. Sea ice protects the embryos of the Antarctic sea urchin Sterechinus neumayeri from oxidative damage due to naturally enhanced levels of UV-B radiation.

    PubMed

    Lister, Kathryn N; Lamare, Miles D; Burritt, David J

    2010-06-01

    The 'ozone hole' has caused an increase in ultraviolet B radiation (UV-B, 280-320 nm) penetrating Antarctic coastal marine ecosystems, however the direct effect of this enhanced UV-B on pelagic organisms remains unclear. Oxidative stress, the in vivo production of reactive oxygen species to levels high enough to overcome anti-oxidant defences, is a key outcome of exposure to solar radiation, yet to date few studies have examined this physiological response in Antarctic marine species in situ or in direct relation to the ozone hole. To assess the biological effects of UV-B, in situ experiments were conducted at Cape Armitage in McMurdo Sound, Antarctica (77.06 degrees S, 164.42 degrees E) on the common Antarctic sea urchin Sterechinus neumayeri Meissner (Echinoidea) over two consecutive 4-day periods in the spring of 2008 (26-30 October and 1-5 November). The presence of the ozone hole, and a corresponding increase in UV-B exposure, resulted in unequivocal increases in oxidative damage to lipids and proteins, and developmental abnormality in embryos of S. neumayeri growing in open waters. Results also indicate that embryos have only a limited capacity to increase the activities of protective antioxidant enzymes, but not to levels sufficient to prevent severe oxidative damage from occurring. Importantly, results show that the effect of the ozone hole is largely mitigated by sea ice coverage. The present findings suggest that the coincidence of reduced stratospheric ozone and a reduction in sea ice coverage may produce a situation in which significant damage to Antarctic marine ecosystems may occur. PMID:20472784

  9. Monopersulfate photocatalysis under 365 nm radiation. Direct oxidation and monopersulfate promoted photocatalysis of the herbicide tembotrione.

    PubMed

    Solís, Rafael R; Rivas, F Javier; Tierno, Mercedes

    2016-10-01

    Oxone(®) (potassium monopersulfate, MPS) has been used to oxidize the herbicide tembotrione in aqueous solution. Tembotrione elimination kinetics by MPS direct oxidation has been studied. The influence of the main operating variables affecting the process (MPS concentration, temperature and pH) has been evaluated. The process follows 2/3 and first orders in MPS and tembotrione concentrations, respectively. Optimal pH is located around circumneutral conditions. MPS decomposition in the presence of 365 nm UVA radiation and titanium dioxide has also been studied. A kinetic mechanism that simulates MPS decomposition has been proposed, showing the positive effect of titania load and MPS concentration. The system MPS/UVA/TiO2 significantly improves tembotrione and mineralization rate abatement if compared to runs conducted in the absence of MPS. Tembotrione total abatement was achieved in 20 min when 0.05 g L(-1) of titania and 10(-4) M of Oxone(®) were used. TOC conversion was roughly 70% in 90 min under similar operating conditions. An experimental design (Plackett-Burman) has been considered to study the influence of the main variables affecting tembotrione photocatalytic oxidation promoted by MPS.

  10. Retinal thermal damage threshold dependence on exposure duration for the transitional near-infrared laser radiation at 1319 nm

    PubMed Central

    Wang, Jiarui; Jiao, Luguang; Jing, Xiaomin; Chen, Hongxia; Hu, Xiangjun; Yang, Zaifu

    2016-01-01

    The retinal damage effects induced by transitional near-infrared (NIR) lasers have been investigated for years. However, the damage threshold dependence on exposure duration has not been revealed. In this paper, the in-vivo retinal damage ED50 thresholds were determined in chinchilla grey rabbits for 1319 nm laser radiation for exposure durations from 0.1 s to 10 s. The incident corneal irradiance diameter was fixed at 5 mm. The ED50 thresholds given in terms of the total intraocular energy (TIE) for exposure durations of 0.1, 1 and 10 s were 1.36, 6.33 and 28.6 J respectively. The ED50 thresholds were correlated by a power law equation, ED50 = 6.31t0.66 [J] where t is time [s], with correlation coefficient R = 0.9999. There exists a sufficient safety margin (factor of 28~60) between the human ED50 thresholds derived from the rabbit and the maximum permissible exposure (MPE) values in the current laser safety standards. PMID:27231639

  11. Retinal thermal damage threshold dependence on exposure duration for the transitional near-infrared laser radiation at 1319 nm.

    PubMed

    Wang, Jiarui; Jiao, Luguang; Jing, Xiaomin; Chen, Hongxia; Hu, Xiangjun; Yang, Zaifu

    2016-05-01

    The retinal damage effects induced by transitional near-infrared (NIR) lasers have been investigated for years. However, the damage threshold dependence on exposure duration has not been revealed. In this paper, the in-vivo retinal damage ED50 thresholds were determined in chinchilla grey rabbits for 1319 nm laser radiation for exposure durations from 0.1 s to 10 s. The incident corneal irradiance diameter was fixed at 5 mm. The ED50 thresholds given in terms of the total intraocular energy (TIE) for exposure durations of 0.1, 1 and 10 s were 1.36, 6.33 and 28.6 J respectively. The ED50 thresholds were correlated by a power law equation, ED50 = 6.31t (0.66) [J] where t is time [s], with correlation coefficient R = 0.9999. There exists a sufficient safety margin (factor of 28~60) between the human ED50 thresholds derived from the rabbit and the maximum permissible exposure (MPE) values in the current laser safety standards. PMID:27231639

  12. Monopersulfate photocatalysis under 365 nm radiation. Direct oxidation and monopersulfate promoted photocatalysis of the herbicide tembotrione.

    PubMed

    Solís, Rafael R; Rivas, F Javier; Tierno, Mercedes

    2016-10-01

    Oxone(®) (potassium monopersulfate, MPS) has been used to oxidize the herbicide tembotrione in aqueous solution. Tembotrione elimination kinetics by MPS direct oxidation has been studied. The influence of the main operating variables affecting the process (MPS concentration, temperature and pH) has been evaluated. The process follows 2/3 and first orders in MPS and tembotrione concentrations, respectively. Optimal pH is located around circumneutral conditions. MPS decomposition in the presence of 365 nm UVA radiation and titanium dioxide has also been studied. A kinetic mechanism that simulates MPS decomposition has been proposed, showing the positive effect of titania load and MPS concentration. The system MPS/UVA/TiO2 significantly improves tembotrione and mineralization rate abatement if compared to runs conducted in the absence of MPS. Tembotrione total abatement was achieved in 20 min when 0.05 g L(-1) of titania and 10(-4) M of Oxone(®) were used. TOC conversion was roughly 70% in 90 min under similar operating conditions. An experimental design (Plackett-Burman) has been considered to study the influence of the main variables affecting tembotrione photocatalytic oxidation promoted by MPS. PMID:27393945

  13. Impact of ultraviolet radiation on cell structure, UV-absorbing compounds, photosynthesis, DNA damage, and germination in zoospores of Arctic Saccorhiza dermatodea.

    PubMed

    Roleda, Michael Y; Wiencke, Christian; Lüder, Ulrike H

    2006-01-01

    Stratospheric ozone depletion leads to enhanced UV-B radiation. Therefore, the capacity of reproductive cells to cope with different spectral irradiance was investigated in the laboratory. Zoospores of the upper sublittoral kelp Saccorhiza dermatodea were exposed to varying fluence of spectral irradiance consisting of photosynthetically active radiation (PAR, 400-700 nm; =P), PAR+UV-A radiation (UV-A, 320-400 nm; =PA), and PAR+UV-A+UV-B radiation (UV-B, 280-320 nm; =PAB). Structural changes, localization of phlorotannin-containing physodes, accumulation of UV-absorbing phlorotannins, and physiological responses of zoospores were measured after exposure treatments as well as after 2-6 d recovery in dim white light (8 mumol photon m(-2) s(-1)). Physodes increased in size under PAB treatment. Extrusion of phlorotannins into the medium and accumulation of physodes was induced not only under UVR treatment but also under PAR. UV-B radiation caused photodestruction indicated by a loss of pigmentation. Photosynthetic efficiency of spores was photoinhibited after 8 h exposure to 22 and 30 mumol photon m(-2) s(-1) of PAR, while supplement of UVR had a significant additional effect on photoinhibition. A relatively low recovery of photosystem II function was observed after 2 d recovery in spores exposed to 1.7 x 10(4) J m(-2) of UV-B, with a germination rate of only 49% of P treatment after 6 d recovery. The amount of UV-B-induced DNA damage measured as cyclobutane-pyrimidine dimers (CPDs) increased with the biologically effective UV-B dose (BED(DNA)). Significant removal of CPDs indicating repair of DNA damage was observed after 2 d in low white light. The protective function of phlorotannins has restricted efficiency for a single cell. Within a plume of zoospores, however, each cell can buffer each other and protect the lower layer of spores from excessive radiation. Exudation of phlorotannins into the water can also reduce the impact of UV-B radiation on UV-sensitive spores

  14. Photodynamic tumor therapy and on-line fluorescence spectroscopy after ALA administration using 633-nm light as therapeutic and fluorescence excitation radiation

    NASA Astrophysics Data System (ADS)

    Koenig, Karsten; Kienle, Alwin; Boehncke, Wolf-Henning; Kaufmann, Roland; Rueck, Angelika C.; Meier, Thomas H.; Steiner, Rudolf W.

    1994-09-01

    Photodynamic therapy (PDT) and on-line fluorescence spectroscopy were carried out on human tumors after 5-aminolevulinic acid (ALA) administration using 633-nm light of a dye laser as therapeutic radiation and as fluorescence excitation radiation. This has the advantages of (1) enabling use of one laser for PDT and fluorescence diagnosis only, (2) enabling the possibility of on-line fluorescence measurements, and (3) exciting protoporphyrin molecules in deep tissue layers. Monte Carlo calculations were carried out to determine excitation and fluorescence phonon distribution in case of red and violet excitation radiation. The results show the possibility of depth-resolved measurements on the fluorophore distribution by variation of excitation wavelength. The high penetration depth of 633-nm radiation results in a higher ratio of the 700-nm protoporphyrin fluorescence of the xenotransplanted tumor It to Is compared with 407-nm excitation. No values greater than 1 for the ratio I/Is were found, however, in case of intravenous ALA injection even for red excitation. Therefore, a large amount of ALA will be metabolized in the skin and can cause photosensitivity of the patient when applied systematically. In contrast, protoporphyrin fluorescence limited to the pretreated skin area was detected in case of topically applied ALA to patients with mycosis funcoides and erythroplasy of Queyrat. The influence of remitted excitation light and of the spontaneous radiation from the laser as well as the possible excitation of foodbased degradation products of chlorophyll has to be considered in high-sensitivity fluorescence measurements.

  15. Temperature-controlled in vivo ocular exposure to 1090-nm radiation suggests that near-infrared radiation cataract is thermally induced

    NASA Astrophysics Data System (ADS)

    Yu, Zhaohua; Schulmeister, Karl; Talebizadeh, Nooshin; Kronschläger, Martin; Söderberg, Per

    2015-01-01

    The damage mechanism for near-infrared radiation (IRR) induced cataract is unclear. Both a photochemical and a thermal mechanism were suggested. The current paper aims to elucidate a photochemical effect based on investigation of irradiance-exposure time reciprocity. Groups of 20 rats were unilaterally exposed to 96-W/cm2 IRR at 1090 nm within the dilated pupil accumulating 57, 103, 198, and 344 kJ/cm2, respectively. Temperature was recorded at the limbus of the exposed eye. Seven days after exposure, the lenses were macroscopically imaged and light scattering was quantitatively measured. The average maximum temperature increases for exposure times of 10, 18, 33, and 60 min were expressed as 7.0±1.1, 6.8±1.1, 7.6±1.3, and 7.4±1.1°C [CI (0.95)] at the limbus of the exposed eye. The difference of light scattering in the lenses between exposed and contralateral not-exposed eyes was 0.00±0.02, 0.01±0.03, -0.01±0.02, and -0.01±0.03 transformed equivalent diazepam concentration (tEDC), respectively, and no apparent morphological changes in the lens were observed. An exposure to 96-W/cm2 1090-nm IRR projected on the cornea within the dilated pupil accumulating radiant exposures up to 344 kJ/cm2 does not induce cataract if the temperature rise at the limbus is <8°C. This is consistent with a thermal damage mechanism for IRR-induced cataract.

  16. Temperature-controlled in vivo ocular exposure to 1090-nm radiation suggests that near-infrared radiation cataract is thermally induced.

    PubMed

    Yu, Zhaohua; Schulmeister, Karl; Talebizadeh, Nooshin; Kronschläger, Martin; Söderberg, Per

    2015-01-01

    The damage mechanism for near-infrared radiation (IRR) induced cataract is unclear. Both a photochemical and a thermal mechanism were suggested. The current paper aims to elucidate a photochemical effect based on investigation of irradiance-exposure time reciprocity. Groups of 20 rats were unilaterally exposed to 96-W/cm(2) IRR at 1090 nm within the dilated pupil accumulating 57, 103, 198, and 344 kJ/cm(2), respectively. Temperature was recorded at the limbus of the exposed eye. Seven days after exposure, the lenses were macroscopically imaged and light scattering was quantitatively measured. The average maximum temperature increases for exposure times of 10, 18, 33, and 60 min were expressed as 7.0 ± 1.1, 6.8 ± 1.1, 7.6 ± 1.3, and 7.4 ± 1.1 °C [CI (0.95)] at the limbus of the exposed eye. The difference of light scattering in the lenses between exposed and contralateral not-exposed eyes was 0.00 ± 0.02, 0.01 ± 0.03, -0.01 ± 0.02, and -0.01 ± 0.03 transformed equivalent diazepam concentration (tEDC), respectively, and no apparent morphological changes in the lens were observed. An exposure to 96-W/cm(2) 1090-nm IRR projected on the cornea within the dilated pupil accumulating radiant exposures up to 344 kJ/cm(2) does not induce cataract if the temperature rise at the limbus is <8 °C. This is consistent with a thermal damage mechanism for IRR-induced cataract.

  17. Spaced sensor measurements of artificial airglow emission at 630 nm of ionosphere caused by ``Sura'' facility radiation in November 2013

    NASA Astrophysics Data System (ADS)

    Nasyrov, Igor; Grach, Savely; Gumerov, Rustam; Shindin, Alexey; Kogogin, Denis; Dementiev, Vladislav

    Some first results on simultaneous observation artificial airglow emission at 630 nm during HF pumping of the ionosphere by “Sura” facility from two spatial situated experimental sites are reported. The measurements of artificial airglow are usually conducted in red and green lines of atomic oxygen (the radiation of levels O((1) D) and O((1) S) under their excitation by electronic impact) with wave lengths of 630 and 557.7 nm and excitation energy of 1.96 and 4.17 eV accordingly. An enhancement of airglow intensity in the red line is related at present to the electron heating by powerful radio waves. The idea of the experiment was to estimate the heated volume three-dimensional structure and drift motion one. The experiment was carried out in November 2013 at the “Sura” radio facility, situated near Nizhny Novgorod, Russia (geographical coordinates 56.13(o) N, 46.10(o) E, geomagnetic field declination and inclination are ˜ 10.0(o) east and ˜ 71.5(o) , respectively). Conditions of ionosphere were checked by means of "Cady" ionosonde during “Sura” runs. According to the ionospheric conditions, on the 7(th) of November the “Sura” facility operated at frequency 4.540 MHz. At this frequency the effective radiated power was about 120MW. The HF beam width at the “Sura” facility is ˜ 12(o) . A square wave pump modulation of 5 min on, 5 min off, was used. Measurements were carried out in the period from 14:40 to 17:30 UTC. Optical imaging was performed on two spatial experimental sites: “Vasilsursk” (situated about 500 m from antenna system of “Sura” facility); “Raifa” (situated about 170 km from “Sura” facility at the Magnetic Observatory of Kazan Federal University, geographical coordinates 55.93(o) N, 48.75(o) E). They both were fitted out Peltier-cooled front-illuminated bare CCD cameras with 16-bit slow-scan read-out (S1C3). On “Vasilsursk” site the images were binned down to 256× 256 pixels in addition to cooling, in order

  18. The effect of the operation modes of a gas discharge low-pressure amalgam lamp on the intensity of generation of 185 nm UV vacuum radiation

    SciTech Connect

    Vasilyak, L. M.; Drozdov, L. A. Kostyuchenko, S. V.; Sokolov, D. V.; Kudryavtsev, N. N.; Sobur, D. A.

    2011-12-15

    The effect of the discharge current, mercury vapor pressure, and the inert gas pressure on the intensity and efficiency of the 185 nm line generation are considered. The spectra of the UV radiation (vacuum ultraviolet) transmission by protective coatings from the oxides of rare earth metals and aluminum are investigated.

  19. Visible optical radiation generates bactericidal effect applicable for inactivation of health care associated germs demonstrated by inactivation of E. coli and B. subtilis using 405-nm and 460-nm light emitting diodes

    NASA Astrophysics Data System (ADS)

    Hönes, Katharina; Stangl, Felix; Sift, Michael; Hessling, Martin

    2015-07-01

    The Ulm University of Applied Sciences is investigating a technique using visible optical radiation (405 nm and 460 nm) to inactivate health-hazardous bacteria in water. A conceivable application could be point-of-use disinfection implementations in developing countries for safe drinking water supply. Another possible application field could be to provide sterile water in medical institutions like hospitals or dental surgeries where contaminated pipework or long-term disuse often results in higher germ concentrations. Optical radiation for disinfection is presently mostly used in UV wavelength ranges but the possibility of bacterial inactivation with visible light was so far generally disregarded. One of the advantages of visible light is, that instead of mercury arc lamps, light emitting diodes could be used, which are commercially available and therefore cost-efficient concerning the visible light spectrum. Furthermore they inherit a considerable longer life span than UV-C LEDs and are non-hazardous in contrast to mercury arc lamps. Above all there are specific germs, like Bacillus subtilis, which show an inactivation resistance to UV-C wavelengths. Due to the totally different deactivation mechanism even higher disinfection rates are reached, compared to Escherichia coli as a standard laboratory germ. By 460 nm a reduction of three log-levels appeared with Bacillus subtilis and a half log-level with Escherichia coli both at a dose of about 300 J/cm². By the more efficient wavelength of 405 nm four and a half log-levels are reached with Bacillus subtilis and one and a half log-level with Escherichia coli also both at a dose of about 300 J/cm². In addition the employed optical setup, which delivered a homogeneous illumination and skirts the need of a stirring technique to compensate irregularities, was an important improvement compared to previous published setups. Evaluated by optical simulation in ZEMAX® the designed optical element provided proven

  20. Inactivation of avirulent Yersinia pestis in Butterfield's phosphate buffer and frankfurters by UVC (254 nm) and gamma radiation.

    PubMed

    Sommers, Christopher H; Cooke, Peter H

    2009-04-01

    Yersinia pestis is the causative agent of plague. Although rare, pharyngeal plague in humans has been associated with consumption or handling of meat prepared from infected animals. The risks of contracting plague from consumption of deliberately contaminated food are currently unknown. Gamma radiation is a penetrating form of electromagnetic radiation, and UVC radiation is used for decontamination of liquids or food surfaces. Gamma radiation D10-values (the radiation dose needed to inactivate 1 log unit pathogen) were 0.23 (+/-0.01) and 0.31 (+/-0.03) kGy for avirulent Y. pestis inoculated into Butterfield's phosphate buffer and onto frankfurter surfaces, respectively, at 0 degree C. A UVC radiation dose of 0.25 J/cm2 inactivated avirulent Y. pestis suspended in Butterfield's phosphate buffer. UVC radiation doses of 0.5 to 4.0 J/cm2 inactivated 0.97 to 1.20 log units of the Y. pestis surface inoculated onto frankfurters. A low gamma radiation dose of 1.6 kGy could provide a 5-log reduction and a UVC radiation dose of 1 to 4 J/cm2 would provide a 1-log reduction of Y. pestis surface inoculated onto frankfurters. Y. pestis was capable of growth on frankfurters during refrigerated storage (10 degrees C). Gamma radiation of frankfurters inhibited the growth of Y. pestis during refrigerated storage, and UVC radiation delayed the growth of Y. pestis.

  1. DNA breaks caused by monochromatic 365 nm ultraviolet-A radiation or hydrogen peroxide and their repair in human epithelioid and xeroderma pigmentosum cells.

    PubMed

    Peak, J G; Pilas, B; Dudek, E J; Peak, M J

    1991-08-01

    The induction and repair of DNA single-strand breaks (SSB) assayed by alkaline filter elution was compared in human epithelioid P3 and xeroderma pigmentosum (XP) cells exposed to monochromatic 365-nm UV-A radiation and H2O2. Initial yields of SSB were measured with the cells held at 0.5 degrees C during exposure. The yield from exposure to 365-nm radiation was slightly greater in XP than in P3 cells, whereas H2O2 produced more than three times as many SSB in P3 compared with XP cells. o-Phenanthroline (50 mM) markedly inhibited the yields of SSB induced in XP cells by H2O2, but had no effect on those produced by 365-nm UV-A. These results are consistent with the fact that P3 cells, unlike XP cells, have undetectable levels of catalase. The measured production of trace amounts of H2O2 by the actual 365-nm UV-A exposures was not sufficient to account for the numbers of breaks that were observed. Single-strand breaks produced by both agents were completely repaired after 50 min in P3 cells, as were H2O2-induced SSB in XP cells. However, 25% of the 365-nm UV-A-induced SSB in XP cells remained refractory to repair after 60 min. The results show that SSB produced by these two agents are different and that 365 nm radiation produces most SSB in cells by mechanisms other than by production of H2O2. PMID:1780357

  2. Generation of tunable 187.9-196-nm radiation in beta-BaB(2)O(4): errata.

    PubMed

    Bhar, G C; Chatterjee, U; Rudra, A M; Kumbhakar, P; Route, R K; Feigelson, R S

    1998-02-15

    In Ref. 1, the first full sentence in the right-hand column of p. 1608 should read as: 'Although BBO is phase matchable down to 187 nm and shorter in this configuration without a very large (2-4 degrees ) change in theta (and hence in d(eff)), and B2 is also suitable to accommodate the phase matching, tunability below 187.9 nm becomes limited by the exponential increase in crystal absorption.'

  3. Estimation of sea surface solar radiation at 400-700 nm using satellite ocean color data, and its validation by ship data.

    PubMed

    Vazyulya, S V; Kopelevich, O V; Sheberstov, S V; Artemiev, V A

    2016-03-21

    We present results of validating the algorithms used to estimate sea surface solar radiation at 400-700 nm, photosynthetically available radiation (PAR), from satellite ocean color data and an appropriate validation procedure when data are collected using a moving ship. The validation was performed using field measurements of PAR during a transit cruise from the Baltic to the White Sea during the summer of 2014. The PAR was measured at 10-minute intervals using a deck radiometer throughout the daylight hours. The satellite estimate of daily surface PAR with an acceptable error, on the scale of 1 day-102 km, is shown. PMID:27136880

  4. Interactive Effects of Temperature and UV Radiation on Photosynthesis of Chlorella Strains from Polar, Temperate and Tropical Environments: Differential Impacts on Damage and Repair.

    PubMed

    Wong, Chiew-Yen; Teoh, Ming-Li; Phang, Siew-Moi; Lim, Phaik-Eem; Beardall, John

    2015-01-01

    Global warming and ozone depletion, and the resulting increase of ultraviolet radiation (UVR), have far-reaching impacts on biota, especially affecting the algae that form the basis of the food webs in aquatic ecosystems. The aim of the present study was to investigate the interactive effects of temperature and UVR by comparing the photosynthetic responses of similar taxa of Chlorella from Antarctic (Chlorella UMACC 237), temperate (Chlorella vulgaris UMACC 248) and tropical (Chlorella vulgaris UMACC 001) environments. The cultures were exposed to three different treatments: photosynthetically active radiation (PAR; 400-700 nm), PAR plus ultraviolet-A (320-400 nm) radiation (PAR + UV-A) and PAR plus UV-A and ultraviolet-B (280-320 nm) radiation (PAR + UV-A + UV-B) for one hour in incubators set at different temperatures. The Antarctic Chlorella was exposed to 4, 14 and 20°C. The temperate Chlorella was exposed to 11, 18 and 25°C while the tropical Chlorella was exposed to 24, 28 and 30°C. A pulse-amplitude modulated (PAM) fluorometer was used to assess the photosynthetic response of microalgae. Parameters such as the photoadaptive index (Ek) and light harvesting efficiency (α) were determined from rapid light curves. The damage (k) and repair (r) rates were calculated from the decrease in ΦPSIIeff over time during exposure response curves where cells were exposed to the various combinations of PAR and UVR, and fitting the data to the Kok model. The results showed that UV-A caused much lower inhibition than UV-B in photosynthesis in all Chlorella isolates. The three isolates of Chlorella from different regions showed different trends in their photosynthesis responses under the combined effects of UVR (PAR + UV-A + UV-B) and temperature. In accordance with the noted strain-specific characteristics, we can conclude that the repair (r) mechanisms at higher temperatures were not sufficient to overcome damage caused by UVR in the Antarctic Chlorella strain

  5. Interactive Effects of Temperature and UV Radiation on Photosynthesis of Chlorella Strains from Polar, Temperate and Tropical Environments: Differential Impacts on Damage and Repair.

    PubMed

    Wong, Chiew-Yen; Teoh, Ming-Li; Phang, Siew-Moi; Lim, Phaik-Eem; Beardall, John

    2015-01-01

    Global warming and ozone depletion, and the resulting increase of ultraviolet radiation (UVR), have far-reaching impacts on biota, especially affecting the algae that form the basis of the food webs in aquatic ecosystems. The aim of the present study was to investigate the interactive effects of temperature and UVR by comparing the photosynthetic responses of similar taxa of Chlorella from Antarctic (Chlorella UMACC 237), temperate (Chlorella vulgaris UMACC 248) and tropical (Chlorella vulgaris UMACC 001) environments. The cultures were exposed to three different treatments: photosynthetically active radiation (PAR; 400-700 nm), PAR plus ultraviolet-A (320-400 nm) radiation (PAR + UV-A) and PAR plus UV-A and ultraviolet-B (280-320 nm) radiation (PAR + UV-A + UV-B) for one hour in incubators set at different temperatures. The Antarctic Chlorella was exposed to 4, 14 and 20°C. The temperate Chlorella was exposed to 11, 18 and 25°C while the tropical Chlorella was exposed to 24, 28 and 30°C. A pulse-amplitude modulated (PAM) fluorometer was used to assess the photosynthetic response of microalgae. Parameters such as the photoadaptive index (Ek) and light harvesting efficiency (α) were determined from rapid light curves. The damage (k) and repair (r) rates were calculated from the decrease in ΦPSIIeff over time during exposure response curves where cells were exposed to the various combinations of PAR and UVR, and fitting the data to the Kok model. The results showed that UV-A caused much lower inhibition than UV-B in photosynthesis in all Chlorella isolates. The three isolates of Chlorella from different regions showed different trends in their photosynthesis responses under the combined effects of UVR (PAR + UV-A + UV-B) and temperature. In accordance with the noted strain-specific characteristics, we can conclude that the repair (r) mechanisms at higher temperatures were not sufficient to overcome damage caused by UVR in the Antarctic Chlorella strain

  6. [Physiological responses of 2-year-old Acer davidii seedings to short-term enhanced UV-B radiation].

    PubMed

    Zuo, Yuanyuan; Liu, Qing; Lin, Bo; He, Hai

    2005-09-01

    At the Maoxian Ecological Experimental Station of Chinese Academy of Sciences in northwest Sichuan Province, 2-year-old native maple(Acer davidii) seedlings were potted outdoors with enhanced UV-B radiation(280 - 320 nm) of 0.27 W x m(-2) (7.7 kJ x m(-2) x d(-1)), which was approximated to the predicted enhanced UV-B reaching the earth surface when stratosphere ozone was depleted by 15% in the local area, with the control plant received ambient UV-B. The gas exchange index and chlorophyll fluorescence, and the contents of chlorophyll and UV-absorbing compounds were examined after 50 days of the radiation. The results showed that enhanced UV-B radiation significantly lowered the maximal net photosynthetic rate (CK = 6.214, TR = 4.452), raised the dark respiration rate(CK = 0.413, TR = 1.295) and light compensation point (CK = 21.629, TR = 59.861), but had little effect on quantum yield (CK = 0.021, TR = 0.032). Under enhanced UV-B radiation, the diurnal changes in net photosynthetic rate, water use efficiency, quantum efficiency of photosystem II centers (Fv/Fm), and quantum yield of photosystem II photochemistry (phi(pspi)) were reduced, chlorophyll a, total chlorophylls, and chlorophyll a/b (CK= 16.23, 5.39, TR = 13.17, 4.93) were also markedly reduced, but chlorophyll b remained nearly unchanged. Contrary to the previous studies, enhanced UV-B radiation decreased the content of UV-absorbing compounds (CK = 0.87, TR = 0.79) in 2-year-old Acer davidii seedling leaves, indicating that the measurement of leaf UV-B absorbing compounds didn't necessarily provide a good indicator of plant tolerance to UV-B. It could be concluded that enhanced UV-B radiation had some inhibitory effects on the photosynthesis of Acer davidii seedlings. Long-term researches are necessary to confirm this conclusion.

  7. Synchrotron X-ray phase contrast imaging of leaf venation in soybean (Glycine max) after exclusion of solar UV (280-400 nm) radiation.

    PubMed

    Fatima, A; Kataria, S; Guruprasad, K N; Agrawal, A K; Singh, B; Sarkar, P S; Shripathi, T; Kashyap, Y; Sinha, A

    2016-05-01

    The hydraulic efficiency of a leaf depends on its vascular structure as this is responsible for transport activities. To investigate the effect of exclusion of UVAB and UVB radiation from the solar spectrum on the micro-structure of leaves of soybean (Glycine max, variety JS-335), a field experiment was conducted using synchrotron-based phase contrast imaging (PCI). Plants were grown in specially designed UV exclusion chambers, and wrapped with filters that excluded UVB (280-315 nm) or UVAB (280-400 nm), or transmitted all the ambient solar UV (280-400 nm) radiation (filter control). Qualitative observation of high-resolution X-ray PCI images obtained at 10 keV has shown the differences in major and minor vein structures of the leaves. The mid-rib width of the middle leaflet of third trifoliate leaves, for all treatments, were obtained using quantitative image analysis. The width of the mid-rib of the middle leaflet of third trifoliate leaves of UVB excluded plants was found to be more compared to leaves of filter control plants, which are exposed to ambient UV. The mid-rib or the main conducting vein transports water and sugars to the whole plant; therefore, mid-rib enhancement by the exclusion of solar UV radiation possibly implies enhancement in the leaf area which in turn causes an increased rate of photosynthesis.

  8. Synchrotron X-ray phase contrast imaging of leaf venation in soybean (Glycine max) after exclusion of solar UV (280-400 nm) radiation.

    PubMed

    Fatima, A; Kataria, S; Guruprasad, K N; Agrawal, A K; Singh, B; Sarkar, P S; Shripathi, T; Kashyap, Y; Sinha, A

    2016-05-01

    The hydraulic efficiency of a leaf depends on its vascular structure as this is responsible for transport activities. To investigate the effect of exclusion of UVAB and UVB radiation from the solar spectrum on the micro-structure of leaves of soybean (Glycine max, variety JS-335), a field experiment was conducted using synchrotron-based phase contrast imaging (PCI). Plants were grown in specially designed UV exclusion chambers, and wrapped with filters that excluded UVB (280-315 nm) or UVAB (280-400 nm), or transmitted all the ambient solar UV (280-400 nm) radiation (filter control). Qualitative observation of high-resolution X-ray PCI images obtained at 10 keV has shown the differences in major and minor vein structures of the leaves. The mid-rib width of the middle leaflet of third trifoliate leaves, for all treatments, were obtained using quantitative image analysis. The width of the mid-rib of the middle leaflet of third trifoliate leaves of UVB excluded plants was found to be more compared to leaves of filter control plants, which are exposed to ambient UV. The mid-rib or the main conducting vein transports water and sugars to the whole plant; therefore, mid-rib enhancement by the exclusion of solar UV radiation possibly implies enhancement in the leaf area which in turn causes an increased rate of photosynthesis. PMID:27140160

  9. The Radiation Enhancement of 15 nm Citrate-Capped Gold Nanoparticles Exposed to 70 keV/μm Carbon Ions.

    PubMed

    Liu, Yan; Liu, Xi; Jin, Xiaodong; He, Pengbo; Zheng, Xiaogang; Ye, Fei; Chen, Weiqiang; Li, Qiang

    2016-03-01

    Radiotherapy is an important modality for tumor treatment. The central goal of radiotherapy is to deliver a therapeutic dose to the tumor as much as possible whilst sparing the surrounding normal tissues. On one hand, heavy ion radiation induces maximum damage at the end of the track (called the Bragg Peak). Hadron therapy based on heavy ions is considered superior to conventional X-rays and γ-rays radiations for tumors sited in sensitive tissues, childhood cases and radioresistant cancers. On the other hand, radiation sensitizers enhanced the radiation effects in tumors by increasing the dose specifically to the tumor cells. Recently, the use of gold nanoparticles as potential tumor selective radio-sensitizers has been proposed as a breakthrough in radiotherapy with conventional radiations. The enhanced radiation effect of heavy ions in tumor by using gold nanoparticles as radio-sensitizer may provide alternative in hadron therapy. In this study, we investigated the radiosensitizing effects of carbon ions with a linear energy transfer of 70 keV/μm in the presence of 15 nm citrate-capped AuNPs. The existing of AuNPs resulted in 5.5-fold enhancement in hydroxyl radical production and 24.5% increment in relative biological effectiveness (RBE) values for carbon-ion-irradiated HeLa cells. The study indicated gold nanoparticles can be used as potential radio-sensitizer in carbon ions therapy.

  10. The Radiation Enhancement of 15 nm Citrate-Capped Gold Nanoparticles Exposed to 70 keV/μm Carbon Ions.

    PubMed

    Liu, Yan; Liu, Xi; Jin, Xiaodong; He, Pengbo; Zheng, Xiaogang; Ye, Fei; Chen, Weiqiang; Li, Qiang

    2016-03-01

    Radiotherapy is an important modality for tumor treatment. The central goal of radiotherapy is to deliver a therapeutic dose to the tumor as much as possible whilst sparing the surrounding normal tissues. On one hand, heavy ion radiation induces maximum damage at the end of the track (called the Bragg Peak). Hadron therapy based on heavy ions is considered superior to conventional X-rays and γ-rays radiations for tumors sited in sensitive tissues, childhood cases and radioresistant cancers. On the other hand, radiation sensitizers enhanced the radiation effects in tumors by increasing the dose specifically to the tumor cells. Recently, the use of gold nanoparticles as potential tumor selective radio-sensitizers has been proposed as a breakthrough in radiotherapy with conventional radiations. The enhanced radiation effect of heavy ions in tumor by using gold nanoparticles as radio-sensitizer may provide alternative in hadron therapy. In this study, we investigated the radiosensitizing effects of carbon ions with a linear energy transfer of 70 keV/μm in the presence of 15 nm citrate-capped AuNPs. The existing of AuNPs resulted in 5.5-fold enhancement in hydroxyl radical production and 24.5% increment in relative biological effectiveness (RBE) values for carbon-ion-irradiated HeLa cells. The study indicated gold nanoparticles can be used as potential radio-sensitizer in carbon ions therapy. PMID:27455642

  11. Evaluating Ultraviolet Radiation Exposures Determined from TOMS Satellite Data at Sites of Amphibian Declines in Central and South America

    NASA Technical Reports Server (NTRS)

    Middleton, Elizabeth M.; Smith, David E. (Technical Monitor)

    2000-01-01

    Many amphibian species have experienced substantial population declines, or have disappeared altogether, during the last several decades at a number of amphibian census sites in Central and South America. This study addresses the use of satellite-derived trends in solar ultraviolet-B (UV-B; 280-320 nm) radiation exposures at these sites over the last two decades, and is intended to demonstrate a role for satellite observations in determining whether UV-B radiation is a contributing factor in amphibian declines. UV-B radiation levels at the Earth's surface were derived from the Total Ozone Mapping Spectrometer (TOMS) satellite data, typically acquired daily since 1979. These data were used to calculate the daily erythemal (sunburning) UV-B, or UV-B(sub ery), exposures at the latitude, longitude, and elevation of each of 20 census sites. The annually averaged UV-B(sub ery) dose, as well as the maximum values, have been increasing in both Central and South America, with higher levels received at the Central American sites. The annually averaged UV-B(sub ery) exposures increased significantly from 1979-1998 at all 11 Central American sites examined (r(exp 2) = 0.60 - 0.79; P<=0.015), with smaller but significant increases at five of the nine South American sites (r(exp 2) = 0.24-0.42; P<=0.05). The contribution of the highest UV-B(sub ery) exposure levels (>= 6750 J/sq m*d) to the annual UV-B(sub ery) total has increased from approx. 5% to approx. 15% in Central America over the 19 year period, but actual daily exposures for each species are unknown. Synergy among UV-B radiation and other factors, especially those associated with alterations of water chemistry (e.g., acidification) in aqueous habitats is discussed. These findings justify further research concerning whether UV-B(sub ery) radiation plays a role in amphibian population declines and extinctions.

  12. Comparison of theory with atomic oxygen 130.4 nm radiation data from the Bow Shock ultraviolet 2 rocket flight

    NASA Technical Reports Server (NTRS)

    Levin, Deborah A.; Candler, Graham V.; Collins, Robert J.; Howlett, Carl L.; Espy, Patrick; Whiting, Ellis; Park, Chul

    1993-01-01

    Comparison is made between the results obtained from a state-of-the-art flow and radiative model and bow shock vacuum ultraviolet (VUV) data obtained the recent Bow Shock 2 Flight Experiment. An extensive data set was obtained from onboard rocket measurements at a reentry speed of 5 km/sec between the altitudes of approximately 65-85 km. A description of the NO photoionization cell used, the data, and the interpretation of the data will be presented. The primary purpose of the analyses is to assess the utility of the data and to propose a radiation model appropriate to the flight conditions of Bow Shock 2. Theoretical predictions based on flow modeling discussed in earlier work and a new radiation model are compared with data.

  13. Preliminary Radiation Testing of a State-of-the-Art Commercial 14nm CMOS Processor - System-on-a-Chip

    NASA Technical Reports Server (NTRS)

    Szabo, Carl M., Jr.; Duncan, Adam; LaBel, Kenneth A.; Kay, Matt; Bruner, Pat; Krzesniak, Mike; Dong, Lei

    2015-01-01

    Hardness assurance test results of Intel state-of-the-art 14nm Broadwell U-series processor System-on-a-Chip (SoC) for total dose are presented, along with first-look exploratory results from trials at a medical proton facility. Test method builds upon previous efforts by utilizing commercial laptop motherboards and software stress applications as opposed to more traditional automated test equipment (ATE).

  14. Preliminary Radiation Testing of a State-of-the-Art Commercial 14nm CMOS Processor/System-on-a-Chip

    NASA Technical Reports Server (NTRS)

    Szabo, Carl M., Jr.; Duncan, Adam; LaBel, Kenneth A.; Kay, Matt; Bruner, Pat; Krzesniak, Mike; Dong, Lei

    2015-01-01

    Hardness assurance test results of Intel state-of-the-art 14nm “Broadwell” U-series processor / System-on-a-Chip (SoC) for total ionizing dose (TID) are presented, along with exploratory results from trials at a medical proton facility. Test method builds upon previous efforts [1] by utilizing commercial laptop motherboards and software stress applications as opposed to more traditional automated test equipment (ATE).

  15. Focusing and photon flux measurements of the 2.88-nm radiation at the sample plane of the soft x-ray microscope, based on capillary discharge source

    NASA Astrophysics Data System (ADS)

    Nawaz, M. Fahad; Jancarek, Alexandr; Nevrkla, Michal; Wachulak, Przemyslaw; Limpouch, Jiri; Pina, Ladislav

    2015-05-01

    Feasibility measurements leading to the development of a Soft X-ray (SXR) microscopy setup, based on capillary discharge XUV source is presented. Here the Z-pinching plasma is acting as a source of XUV radiation, emitting incoherent radiation in the "water-window" (λ = 2.3 - 4.4 nm) region of interest (natural contrast between the carbon and oxygen edges).This soft X-ray microscopy setup will realize imaging of the biological objects with high spatial resolution. The 2.88 nm radiation line is filtered out from the water-window band, and is focused by an axi-symmetric ellipsoidal mirror, coated with nickle. The focussed spot size is measured and reported. Flux measurements for the available number of photons (photons/pulse) at the sample plane has been carried out with AXUV PIN diode at the sample plane (slightly out of focus). For imaging, a fresnel zone plate lens will be used as an objective. The overall compact transmission SXR microscopy setup design is presented.

  16. Quasi-continuous-wave 589-nm radiation based on intracavity frequency-doubled Nd:GGG/BaWO4 Raman laser

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Liu, Zhaojun; Cong, Zhenhua; Men, Shaojie; Rao, Han; Xia, Jinbao; Zhang, Sasa; Zhang, Huaijin

    2016-07-01

    Quasi-continuous-wave (QCW) 589-nm radiation was realized based on a frequency-doubled crystalline Raman laser. The fundamental wave with macro-micro-pulse trains was generated from an acousto-optically Q-switched QCW diode side-pumped Nd:GGG laser. Intracavity Raman conversion was accomplished by a BaWO4 crystal and the second harmonic generation was finished by a KTP crystal. Under a pumping power of 126.0 W with a macro-pulse frequency of 300 Hz and duration of 300 μs, the maximum 589 nm output power of 4.2 W was obtained at a micro-pulse frequency of 33.3 kHz. The micro-pulse width was 13.6 ns.

  17. Effects of UV radiation on phytoplankton

    NASA Astrophysics Data System (ADS)

    Smith, Raymond C.; Cullen, John J.

    1995-07-01

    It is now widely documented that reduced ozone will result in increased levels of ultraviolet (UV) radiation, especially UV-B (280-320nm), incident at the surface of the earth [Watson, 1988; Anderson et al., 1991; Schoeberl and Hartmann, 1991; Frederick and Alberts, 1991; WMO, 1991; Madronich, 1993; Kerr and McElroy, 1993], and there is considerable and increasing evidence that these higher levels of UV-B radiation may be detrimental to various forms of marine life in the upper layers of the ocean. With respect to aquatic ecosystems, we also know that this biologically- damaging mid-ultraviolet radiation can penetrate to ecologically- significant depths in marine and freshwater systems [Jerlov, 1950; Lenoble, 1956; Smith and Baker, 1979; Smith and Baker, 1980; Smith and Baker, 1981; Kirk et al., 1994]. This knowledge, plus the dramatic decline in stratospheric ozone over the Antarctic continent each spring, now known to be caused by anthropogenically released chemicals [Solomon, 1990; Booth et al., 1994], has resulted in increased UV-environmental research and a number of summary reports. The United Nations Environmental Program (UNEP) has provided recent updates with respect to the effects of ozone depletion on aquatic ecosystems (Hader, Worrest, Kumar in UNEP 1989, 1991, Hader, Worrest, Kumar and Smith UNEP 1994) and the Scientific Committee on Problems of the Environment (SCOPE) has provided [SCOPE, 1992] a summary of the effects of increased UV radiation on biological systems. SCOPE has also reported [SCOPE, 1993] on the effects of increased UV on the biosphere. In addition, several books have recently been published reviewing various aspects of environmental UV photobiology [Young et al., 1993], UV effects on humans, animals and plants [Tevini, 1993], the biological effects of UV radiation in Antarctica [Weiler and Penhale, 1994], and UV research in freshwater ecosystems [Williamson and Zagarese, 1994]. Several other reviews are relevant [NAS, 1984; Caldwell

  18. Surface modification of Sylgard 184 polydimethylsiloxane by 254 nm excimer radiation and characterization by contact angle goniometry, infrared spectroscopy, atomic force and scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Waddell, Emanuel A.; Shreeves, Stephen; Carrell, Holly; Perry, Christopher; Reid, Branden A.; McKee, James

    2008-06-01

    The modification of polydimethylsiloxane (PDMS) by narrow band 254 nm excimer radiation under a nitrogen atmosphere was characterized by contact angle goniometry, attenuated total reflectance infrared spectroscopy, atomic force and scanning electron microscopy. UV irradiation results in the formation of the carboxylic acids that influences the wettability of the surface. Continued exposure results in the formation of an inorganic surface (SiO x (1 < x < 2)) which hinders the ability to continually increase the wettability. The continuity of this inorganic layer is disrupted by the formation of surface cracks. These results have implications in the fabrication and chemical modification of microfluidic or micro-electro-mechanical systems.

  19. Effect of UV-B Radiation (290-320nm) on the Nitrogen Metabolism of Several Marine Diatoms.

    PubMed

    Döhler, G

    1985-04-01

    The marine diatoms Bellerochea yucatanensis, Biddulphia sinensis, Ditylum brightwellii, Lauderia annulata and Thalassiosira rotula were grown for 2 days under different levels of UV-B radiation (439, 717, and 1230J · m (-2) ·d(-1)). UV-B stress depressed the growth rates of all species. A low UV-B dose (439 J · m (-2) · d (-1), weighted), usually caused a slight increase in biomass production (dry weight} in comparison to nontreated cells. Enhanced UV-B reduced the dry matter productivity of all diatoms. All marine diatoms exposed to UV-B showed a diminution of protein and pigment content (chlorophyll a, chlorophyll c(1) + C(2), and carotenoids). Algae grown in 20 %o or 35 %o salt concentrations were more sensitive to UV-B radiation than those grown in 45%o. S. The effect of higher UV-B dose (717J · m (-2) · d(-1), weighted) upon the pools of free amino acids was species-dependent. Aspartate and asparagine levels were reduced in all diatoms. A marked increase in glutamine levels was found in Bellerochea, Biddulphia, Ditylum and Lauderia. Thalassiosira cells exposed to UV-B showed a significant increase in glutamate levels and a reduction of glutamine levels. (15)N and (14)C incorporation into several amino acids was reduced by exposure to UV-B. The results are discussed with reference to the inhibition of the enzymes for carbon and nitrogen metabolism. PMID:23196172

  20. Accurate Quantification of Ionospheric State Based on Comprehensive Radiative Transfer Modeling and Optimal Inversion of the OI 135.6-nm Emission

    NASA Astrophysics Data System (ADS)

    Qin, J.; Kamalabadi, F.; Makela, J. J.; Meier, R. J.

    2015-12-01

    Remote sensing of the nighttime OI 135.6-nm emission represents the primary means of quantifying the F-region ionospheric state from optical measurements. Despite its pervasive use for studying aeronomical processes, the interpretation of these emissions as a proxy for ionospheric state remains ambiguous in that the relative contributions of radiative recombination and mutual neutralization to the production and, especially, the effects of scattering and absorption on the transport of the 135.6-nm emissions have not been fully quantified. Moreover, an inversion algorithm, which is robust to varying ionospheric structures under different geophysical conditions, is yet to be developed for statistically optimal characterization of the ionospheric state. In this work, as part of the NASA ICON mission, we develop a comprehensive radiative transfer model from first principle to investigate the production and transport of the nighttime 135.6-nm emissions. The forward modeling investigation indicates that under certain conditions mutual neutralization can contribute up to ~38% to the 135.6-nm emissions. Moreover, resonant scattering and pure absorption can reduce the brightness observed in the limb direction by ~40% while enhancing the brightness in the nadir direction by ~25%. Further analysis shows that without properly addressing these effects in the inversion process, the peak electron density in the F-region ionosphere (NmF2) can be overestimated by up to ~24%. To address these issues, an inversion algorithm that properly accounts for the above-mentioned effects is proposed for accurate quantification of the ionospheric state using satellite measurements. The ill-posedness due to the intrinsic presence of noise in real data is coped with by incorporating proper regularizations that enforce either global smoothness or piecewise smoothness of the solution. Application to model-generated data with different signal-to-noise ratios show that the algorithm has achieved

  1. Transmission of 1064 nm laser radiation during ablation with an ultra-short pulse laser (USPL) system

    NASA Astrophysics Data System (ADS)

    Schelle, Florian; Meister, Jörg; Oehme, Bernd; Frentzen, Matthias

    2012-01-01

    During ablation of oral hard tissue with an USPL system a small amount of the incident laser power does not contribute to the ablation process and is being transmitted. Partial transmission of ultra-short laser pulses could potentially affect the dental pulp. The aim of this study was to assess the transmission during ablation and to deduce possible risks for the patient. The study was performed with an Nd:YVO4 laser, emitting pulses with a duration of 8 ps at a wavelength of 1064 nm. A repetition rate of 500 kHz and an average power of 9 W were chosen to achieve high ablation efficiency. A scanner system created square cavities with an edge length of 1 mm. Transmission during ablation of mammoth ivory and dentin slices with a thickness of 2 mm and 5 mm was measured with a power meter, placed directly beyond the samples. Effects on subjacent blood were observed by ablating specimens placed in contact to pork blood. In a separate measurement the temperature increase during ablation was monitored using an infrared camera. The influence of transmission was assessed by tuning down the laser to the corresponding power and then directly irradiating the blood. Transmission during ablation of 2 mm specimens was about 7.7% (ivory) and 9.6% (dentin) of the incident laser power. Ablation of specimens directly in contact to blood caused coagulation at longer irradiation times (t~18s). Direct irradiation of blood with the transmitted power provoked bubbling and smoke formation. Temperature measurements identified heat generation as the main reason for the observed coagulation.

  2. Mutagenic and lethal effects of near-ultraviolet radiation (290-400 nm) on bacteria and phage

    SciTech Connect

    Eisenstark, A.

    1987-01-01

    Despite decades of study of the effect of near-ultraviolet radiation (NUV) on bacterial cells, insights into mechanisms of deleterious alterations and subsequent recovery are just now emerging. These insights are based on observations that 1) damage by NUV may be caused by a reactive oxygen molecule, since H/sub 2/O/sub 2/ may be a photoproduct of NUV; 2) some, but not all, of the effects of NUV and H/sub 2/O/sub 2/ are interchangeable; 3) there is an inducible regulon (oxyR) that responds to oxidative stress and is involved in protection against NUV; 4) a number of NUV-sensitive mutants are defective either in the capacity to detoxify reactive oxygen molecules or to repair DNA damage caused by NUV; and 5) recovery from NUV damage may not directly involve induction of the SOS response. Since several distinctly different photoreceptors and targets are involved, it is unknown whether NUV lethality and mutagenesis result from an accumulation of damages or whether there is a particularly critical photoeffect. To fully understand the mechanisms involved, it is important to identify the chromophore(s) of NUV, the mechanism of toxic oxygen species generation, the role of the oxidative defense regulon (oxyR), the specific lesions in the DNA, and the enzymatic events of subsequent repair. 131 references.

  3. Mutagenic and lethal effects of near-ultraviolet radiation (290-400 nm) on bacteria and phage.

    PubMed

    Eisenstark, A

    1987-01-01

    Despite decades of study of the effect of near-ultraviolet radiation (NUV) on bacterial cells, insights into mechanisms of deleterious alterations and subsequent recovery are just now emerging. These insights are based on observations that 1) damage by NUV may be caused by a reactive oxygen molecule, since H2O2 may be a photoproduct of NUV; 2) some, but not all, of the effects of NUV and H2O2 are interchangeable; 3) there is an inducible regulon (oxyR) that responds to oxidative stress and is involved in protection against NUV; 4) a number of NUV-sensitive mutants are defective either in the capacity to detoxify reactive oxygen molecules or to repair DNA damage caused by NUV; and 5) recovery from NUV damage may not directly involve induction of the SOS response. Since several distinctly different photoreceptors and targets are involved, it is unknown whether NUV lethality and mutagenesis result from an accumulation of damages or whether there is a particularly critical photoeffect. To fully understand the mechanisms involved, it is important to identify the chromophore(s) of NUV, the mechanism of toxic oxygen species generation, the role of the oxidative defense regulon (oxyR), the specific lesions in the DNA, and the enzymatic events of subsequent repair. PMID:3315655

  4. Autonomous portable solar ultraviolet spectroradiometer (APSUS) - a new CCD spectrometer system for localized, real-time solar ultraviolet (280-400 nm) radiation measurement.

    PubMed

    Hooke, Rebecca; Pearson, Andy; O'Hagan, John

    2014-01-01

    Terrestrial solar ultraviolet (UV) radiation has significant implications for human health and increasing levels are a key concern regarding the impact of climate change. Monitoring solar UV radiation at the earth's surface is therefore of increasing importance. A new prototype portable CCD (charge-coupled device) spectrometer-based system has been developed that monitors UV radiation (280-400 nm) levels at the earth's surface. It has the ability to deliver this information to the public in real time. Since the instrument can operate autonomously, it is called the Autonomous Portable Solar Ultraviolet Spectroradiometer (APSUS). This instrument incorporates an Ocean Optics QE65000 spectrometer which is contained within a robust environmental housing. The APSUS system can gather reliable solar UV spectral data from approximately April to October inclusive (depending on ambient temperature) in the UK. In this study the new APSUS unit and APSUS system are presented. Example solar UV spectra and diurnal UV Index values as measured by the APSUS system in London and Weymouth in the UK in summer 2012 are shown. PMID:24483759

  5. Autonomous portable solar ultraviolet spectroradiometer (APSUS) - a new CCD spectrometer system for localized, real-time solar ultraviolet (280-400 nm) radiation measurement.

    PubMed

    Hooke, Rebecca; Pearson, Andy; O'Hagan, John

    2014-01-01

    Terrestrial solar ultraviolet (UV) radiation has significant implications for human health and increasing levels are a key concern regarding the impact of climate change. Monitoring solar UV radiation at the earth's surface is therefore of increasing importance. A new prototype portable CCD (charge-coupled device) spectrometer-based system has been developed that monitors UV radiation (280-400 nm) levels at the earth's surface. It has the ability to deliver this information to the public in real time. Since the instrument can operate autonomously, it is called the Autonomous Portable Solar Ultraviolet Spectroradiometer (APSUS). This instrument incorporates an Ocean Optics QE65000 spectrometer which is contained within a robust environmental housing. The APSUS system can gather reliable solar UV spectral data from approximately April to October inclusive (depending on ambient temperature) in the UK. In this study the new APSUS unit and APSUS system are presented. Example solar UV spectra and diurnal UV Index values as measured by the APSUS system in London and Weymouth in the UK in summer 2012 are shown.

  6. Transient radiation-induced absorption at 1061 nm in LiNiO[sub 3] and MgO:LiNbO[sub 3

    SciTech Connect

    Brannon, P.J. )

    1994-06-01

    The transient radiation-induced 1061 nm absorption in pure and MgO doped lithium niobate has been measured using Sandia National Laboratories' SPR 3 pulsed nuclear reactor. The samples are subjected to neutron fluences up to 10[sup 13]/cm[sup 2] (1 MeV Si) and total doses up to 7.5 krad. By using various shields, it has been found that gamma rays are the major contributors to the induced absorption at this wavelength. A plot of the natural logarithm of the transmittance versus time is given along with the peak induced absorption coefficient versus dose. The data indicate color centers with different time dependencies. A log-log plot of the transmission loss in dB/cm versus time indicates a 1/t[sup 1/4] time dependence initially.

  7. Solar Electromagnetic Radiation Study for Solar Cycle 22: Solar Ultraviolet Irradiance, 120 to 300 NM: Report of Working Groups 2 and 3 of SOLERS 22

    NASA Technical Reports Server (NTRS)

    Rottman, G. J.; Cebula, R. P.; Gillotay, D.; Simon, P. A.

    1996-01-01

    This report summarizes the activities of Working Group 2 and Working Group 3 of the SOLax Electromagnetic Radiation Study for Solar Cycle 22 (SOLERS22) Program. The international (SOLERS22) is Project 1.2 of the Solar-Terrestrial Energy Program (STEP) sponsored by SCOSTEP, a committee of the International Council of Scientific Unions). SOLERS22 is comprised of five Working Groups, each concentrating on a specific wave-length range: WG-1 - visible and infrared, WG-2 - mid-ultraviolet (200 < A < 300 nm), WG-3 - Far-ultraviolet (lambda greater than 100 and lambda less than 200 nanometers), WG-4 - extreme-ultraviolet (lambda greater than 10 and lambda less than 100 nm), and WG-5 - X-ray (lambda greater than 1 and lambda less than 10 nano meters). The overarching goals of SOLERS22 are to: 1) establish daily solar irradiance values in the specified wavelength ranges, 2) consider the evolving solar structures as the cause of temporal variations, and 3) understand the underlying physical processes driving these changes.

  8. Photoacclimation to long-term ultraviolet radiation exposure of natural sub-Antarctic phytoplankton communities: Fixed surface incubations versus mixed mesocosms.

    PubMed

    Hernando, Marcelo; Schloss, Irene; Roy, Suzanne; Ferreyra, Gustavo

    2006-01-01

    Solar UVB radiation (280-320 nm) is known to have detrimental effects on marine phytoplankton. Associated with the seasonal ozone hole in Antarctica, stratospheric ozone depletion occasionally influences the sub-Antarctic (Beagle Channel, Argentina) region, enhancing levels of UVB. The primary objective of this work was to study the effects of several (i.e. 6-10) days of exposure to UVB on the taxonomic composition and photosynthetic inhibition of local phytoplankton communities. For different light treatments, fixed-depth incubations placed in an outdoors water tank were compared with incubations in 1900 L mesocosms, where vertical mixing was present. Phytoplankton growth was inhibited by UV radiation (UVR) in fixed-depth experiments but not in the mixed mesocosms. Under fixed and mixed conditions alike, photosynthesis was significantly inhibited by UVB at the beginning of the experiment but no longer after several days of exposure, suggesting that cells had acclimated to radiation conditions. There was a change in species composition in response to UVR exposure in both experiments, which likely explained acclimation. In the community exposed to fixed conditions this change was from a phytoflagellate-dominated assemblage to a community with high relative abundance of diatoms after 6 days of exposure. UVA was responsible for most of the observed growth inhibition; however, the reduction in photosynthesis was produced by UVB. The reasons behind this variability in responses to UVR are associated with species-specific sensitivity and acclimation, and the previous light history of cells. In the community exposed in mesocosms, an assemblage codominated by phytoflagellates and diatoms was observed at the beginning of the experiments. After 10 days of exposure, green algae (Eutreptiella sp.) had increased, and phytoflagellates were the dominant group. The synthesis of mycosporine-like amino acids (MAAs), antioxidant enzymes and photosynthetic antenna pigments, in

  9. The formation of DNA single-strand breaks and alkali-labile sites in human blood lymphocytes exposed to 365-nm UVA radiation.

    PubMed

    Osipov, Andreyan N; Smetanina, Nadezhda M; Pustovalova, Margarita V; Arkhangelskaya, Ekaterina; Klokov, Dmitry

    2014-08-01

    The potency of UVA radiation, representing 90% of solar UV light reaching the earth's surface, to induce human skin cancer is the subject of continuing controversy. This study was undertaken to investigate the role of reactive oxygen species in DNA damage produced by the exposure of human cells to UVA radiation. This knowledge is important for better understanding of UV-induced carcinogenesis. We measured DNA single-strand breaks and alkali-labile sites in human lymphocytes exposed ex vivo to various doses of 365-nm UV photons compared to X-rays and hydrogen peroxide using the comet assay. We demonstrated that the UVA-induced DNA damage increased in a linear dose-dependent manner. The rate of DNA single-strand breaks and alkali-labile sites after exposure to 1J/cm(2) was similar to the rate induced by exposure to 1 Gy of X-rays or 25 μM hydrogen peroxide. The presence of either the hydroxyl radical scavenger dimethyl sulfoxide or the singlet oxygen quencher sodium azide resulted in a significant reduction in the UVA-induced DNA damage, suggesting a role for these reactive oxygen species in mediating UVA-induced DNA single-strand breaks and alkali-labile sites. We also showed that chromatin relaxation due to hypertonic conditions resulted in increased damage in both untreated and UVA-treated cells. The effect was the most significant in the presence of 0.5M Na(+), implying a role for histone H1. Our data suggest that the majority of DNA single-strand breaks and alkali-labile sites after exposure of human lymphocytes to UVA are produced by reactive oxygen species (the hydroxyl radical and singlet oxygen) and that the state of chromatin may substantially contribute to the outcome of such exposures.

  10. Effect of enhanced UV-B radiation on pollen quantity, quality, and seed yield in Brassica rapa (Brassicaceae)

    SciTech Connect

    Demchik, S.M.; Day, T.A.

    1996-05-01

    Three experiments examined the influence of ultraviolet-B radiation (UV-B; 280-320 nm) exposure on reproduction in Brassica rapa (Brassicacaeae). Plants were grown in a greenhouse under three biologically effective UV-B levels that stimulated either an ambient stratospheric ozone level (control), 16% ({open_quotes}low enhanced{close_quotes}), or 32% ({open_quotes}high enhanced{close_quotes}) ozone depletion levels at Morgantown, WV, USA in mid-March. In the first experiment,pollen production and viability per flower were reduced by {approx}50% under both enhanced UV-B levels relative to ambient controls. While plants under high-enhanced UV-B produced over 40% more flowers than plants under the two lower UV-B treatments, whole-plant production of viable pollen was reduced under low-enhanced UV-B to 34% of ambient controls. In the second experiment, the influence of source-plant UV-B exposure on in vitro pollen from plants was examined and whether source-plant UV-B exposure influenced in vitro pollen germination and viability. Pollen from plants under both enhanced-UV-B was reduced from 65 to 18%. Viability of the pollen from plants grown under both enhanced UV-B treatments was reduced to a much lesser extent: only from {approx}43 to 22%. Thus, ambient source-plant pollen was more sensitive to enhanced UV-B levels to fertilize plants growing under ambient-UV-B levels, and assessed subsequent seed production and germination. Seed abortion rates were higher in plants pollinated with pollen from the enhanced UV-B treatments, than from ambient UV-B. Despite this, seed yield (number and mass) per plant was similar, regardless of the UV-B exposure of their pollen source. Our findings demonstrate that enhanced UV-B levels associated with springtime ozone depletion events have the capacity to substantially reduce viable pollen production, and could ultimately reduce reproductive success of B. rapa. 37 refs., 4 figs., 2 tabs.

  11. Ultraviolet-B radiation effects on the structure and function of lower trophic levels of the marine planktonic food web.

    PubMed

    Ferreyra, Gustavo A; Mostajir, Behzad; Schloss, Irene R; Chatila, Khaled; Ferrario, Martha E; Sargian, Peggy; Roy, Suzanne; Prod'homme, Johann; Demers, Serge

    2006-01-01

    The impact of UV-B radiation (UVBR; 280-320 nm) on lower levels of a natural plankton assemblage (bacteria, phytoplankton and microzooplankton) from the St. Lawrence Estuary was studied during 9 days using several immersed outdoor mesocosms. Two exposure treatments were used in triplicate mesocosms: natural UVBR (N treatment, considered as the control treatment) and lamp-enhanced UVBR (H treatment, simulating 60% depletion of the ozone layer). A phytoplankton bloom developed after day 3, but no significant differences were found between treatments during the entire experiment for phytoplankton biomass (chlorophyll a and cell carbon) nor for phytoplankton cell abundances from flow cytometry and optical microscopy of three phytoplankton size classes (picoplankton, nanoplankton and microplankton). In contrast, bacterial abundances showed significantly higher values in the H treatment, attributed to a decrease in predation pressure due to a dramatic reduction in ciliate biomass (approximately 70-80%) in the H treatment relative to the N treatment. The most abundant ciliate species were Strombidinium sp., Prorodon ovum and Tintinnopsis sp.; all showed significantly lower abundances under the H treatment. P. ovum was the less-affected species (50% reduction in the H treatment compared with that of the N control), contrasting with approximately 90% for the other ones. Total specific phytoplanktonic and bacterial production were not affected by enhanced UVBR. However, both the ratio of primary to bacterial biomass and production decreased markedly under the H treatment. In contrast, the ratio of phytoplankton to bacterial plus ciliate carbon biomass showed an opposite trend than the previous results, with higher values in the H treatment at the end of the experiment. These results are explained by the changes in the ciliate biomass and suggest that UVBR can alter the structure of the lower levels of the planktonic community by selectively affecting key species. On the

  12. The effects of UV radiation, litter chemistry, and drought on desert litter decomposition

    NASA Astrophysics Data System (ADS)

    Lee, H.; Nieto, B.; Hewins, D. B.; Barnes, P. W.; McDowell, N. G.; Pockman, W.; Rahn, T.; Throop, H. L.

    2011-12-01

    Recent studies suggest that photodegradation by solar UV radiation can be a major driver of litter decomposition in dryland ecosystems. The importance of photodegradation in litter decomposition appears to decline with precipitation, suggesting that the relative importance of photodegradation may increase given current projections of future increases in drought severity in the southwestern USA. Several previous studies indicate that UV-B radiation (280-320 nm) is the most effective waveband in breaking chemical bonds forming organic material, but whether UV-B exposure may facilitate subsequent decomposition by microbes (i.e., photo-priming) has received little attention. In this study, we tested the effects of pre-exposure UV radiation (photo-priming), litter chemistry (lignin and cellulose content and nitrogen content), and drought on the rate of litter decomposition in a semi-arid ecosystem. To understand the effects of UV radiation on litter decomposition, we pre-exposed litter to three radiation treatments: control (no radiation), UV-A+visible, UV-A+UV-B+visible. Litter was exposed to the equivalent of three months' solar radiation of southern New Mexico prior to microbial decomposition. There were three litter types: basswood sheets (high lignin content), pure cellulose filter paper, and mesquite (Prosopis glandulosa) leaflets. Following radiation treatment, litter was placed in mesh litterbags that were buried within a large-scale precipitation manipulation experiment at the Sevilleta Long-Term Ecological Research site: control (ambient precipitation), elevated precipitation (x2 ambient precipitation), and drought (x0.5 ambient precipitation). We collected a subset of bags at 0, 1, 3, and 6 months and measured mass remaining and carbon (C) and nitrogen (N) content. After 6 months, mass remaining of filter paper and basswood sheets did not differ from the initial mass, but mesquite mass remaining declined over 30%. The pre-exposure UV effects had minimal

  13. Repair of non-dimer DNA damages in ICB 2A frog cells exposed to solar-ultraviolet radiation in the UVB (290-320 nm) range

    SciTech Connect

    Chao, C.C.K.

    1985-01-01

    The purpose of the research described in this dissertation was to investigate the repair and cellular consequences of non-dimer DNA damages induced by solar-UV irradiation of cultured I CR 2A (Rana pipiens) frog cells. Because this cell line is proficient in enzymatic photoreactivation, it was possible to induce a relatively pure population of non-dimer DNA photoproducts by exposure of cells to the Mylar-filtered solar-UV wavelengths produced by a fluorescent sunlamp followed by treatment with photoreactivating light. With a modification of bromodeoxyuridine photolysis assay, it was found that the solar-UV-induced non-dimer DNA damages were repaired by a short-patch repair mechanism in which less than 20 nucleotides were inserted into a repaired region. Similar results were also obtained for ..gamma..-irradiated cells. In contrast, excision repair of 254 nm-induced dimers was accomplished by a long-patch process in which an average of about 180 nucleotides were inserted into the repaired sites. A mutant cell line, DRP 36, hypersensitive to non-dimer DNA damages, was isolated from I CR 2A cells. It was found that the DRP 36 cells performed a significantly lower level of excision repair following the induction of non-dimer DNA damages. The results are consistent with the conclusion that the DRP 36 cells are deficient in the repair of at least one type of solar-UV-induced non-dimer DNA lesion. These experiments indicate that solar-UV-induced non-dimer DNA photoproducts behave more like the photoproducts of ..gamma..-rays than those of far-UV radiation, which are primarily pyrimidine dimers.

  14. Photosynthesis, Growth, and Ultraviolet Irradiance Absorbance of Cucurbita pepo L. Leaves Exposed to Ultraviolet-B Radiation (280-315 nm) 1

    PubMed Central

    Sisson, William B.

    1981-01-01

    Net photosynthesis, growth, and ultraviolet (UV) radiation absorbance were determined for the first leaf of Cucurbita pepo L. exposed to two levels of UV-B irradiation and a UV-B radiation-free control treatment. Absorbance by extracted flavonoid pigments and other UV-B radiation-absorbing compounds from the first leaves increased with time and level of UV-B radiation impinging on leaf surfaces. Although absorbance of UV-B radiation by extracted pigments increased substantially, UV-B radiation attenuation apparently was insufficient to protect completely the photosynthetic apparatus or leaf growth processes. Leaf expansion was repressed by daily exposure to 1365 Joules per meter per day of biologically effective UV-B radiation but not by exposure to 660 Joules per meter per day. Photosynthesis measured through ontogenesis of the first leaf was depressed by both UV-B radiation treatments. Repression of photosynthesis by UV-B radiation was especially evident during the ontogenetic period of maximum photosynthetic activity. PMID:16661610

  15. Generation of high power 200 mW laser radiation at 177.3 nm in KBe2BO3F2 crystal

    NASA Astrophysics Data System (ADS)

    Xu, Bo; Liu, Lijuan; Wang, Xiaoyang; Chen, Chuangtian; Zhang, Xin; Lin, Shujie

    2015-12-01

    With a newly developed diffusion-bonded KBe2BO3F2 prism-coupled device and by temperature stabilization of the device, we have achieved an average power of 200 mW at 177.3 nm through the sixth harmonic generation of a picosecond Nd:YAG laser. This is the highest power at 177.3 nm ever generated in any nonlinear optical crystals. A stable average power of 72.2 mW at 177.3 nm was also obtained with a small fluctuation of 3.2 % over a period of 30 min. Moreover, both the angle and temperature acceptances for the 177.3 nm generation were reported for the first time in this paper.

  16. Measuring nonlinear reflectance of laser radiation with a wavelength of 2940 nm from silica glass – water and silica glass – ethanol interfaces

    NASA Astrophysics Data System (ADS)

    Gulyamova, E. S.; Il'ichev, N. N.; Pashinin, P. P.; Polyanskii, V. I.; Sidorin, A. V.

    2016-07-01

    We have measured the reflectance of an Er3+ : YAG laser pulse from silica glass – water and silica glass – ethanol interfaces at high (0.9 J cm-2) and low (5 mJ cm-2) energy densities of incident radiation. The nonlinearity of reflectance dynamics is found for high-power radiation during the laser pulse action.

  17. Induction of pyrimidine dimers and unscheduled DNA synthesis in cultured mouse epithelial cells exposed to 254-nm- and u. v. -B radiation

    SciTech Connect

    Yotti, L.P.; Ley, R.D.

    1983-01-01

    The induction and fate of pyrimidine dimers and unscheduled DNA synthesis were measured in u.v.-irradiated primary, newborn SENCAR mouse epithelial cells. Unscheduled DNA synthesis was induced in a dose responsive manner by two u.v. sources, a germicidal lamp (254 nm) and an FS40 sunlamp (280--400 nm). Using the endonuclease-sensitive site assay to detect pyrimidine dimer production and excision, we examined the response of the newborn mouse cells to both u.v. sources. We were unable to detect the removal of pyrimidine dimers with either of the two sources of u.v. The speculation is made that primary, newborn mouse epidermal cells excise u.v.-induced pyrimidine dimers to an extent below the level of detection of the endonuclease-sensitive site assay but to an extent sufficient to induce unscheduled DNA synthesis.

  18. Comparative study of the application of microcurrent and AsGa 904 nm laser radiation in the process of repair after calvaria bone excision in rats

    NASA Astrophysics Data System (ADS)

    Mendonça, J. S.; Neves, L. M. G.; Esquisatto, M. A. M.; Mendonça, F. A. S.; Santos, G. M. T.

    2013-03-01

    This study evaluated the effects of microcurrent stimulation (10 μA/5 min) and 904 nm GaAs laser irradiation (3 J cm-2 for 69 s/day) on excisional lesions created in the calvaria bone of Wistar rats. The results showed significant responses in the reduction of inflammatory cells and an increase in the number of new blood vessels, number of fibroblasts and deposition of birefringent collagen fibers when these data were compared with those of samples of the untreated lesions. Both applications, microcurrent and laser at 904 nm, favored tissue repair in the region of bone excisions during the study period and these techniques can be used as coadjuvantes in the repair of bone tissue.

  19. Low-intensity LED (625 and 405 nm) and laser (805 nm) killing of Propionibacterium acnes and Staphylococcus epidermidis

    NASA Astrophysics Data System (ADS)

    Tuchina, Elena S.; Tuchin, Valery V.

    2009-02-01

    In the present work we have investigated in vitro sensitivity of microorganisms P. acnes and S. epidermidis to action of red (625 nm and 405 nm) and infrared (805 nm) radiations in combination with photosensitizes Methylene Blue and Indocyanine Green.

  20. SOLAR RADIATION AND INDUCTION OF DNA DAMAGE, MUTATIONS AND SKIN CANCERS.

    SciTech Connect

    SETLOW,R.B.

    2007-05-10

    An understanding of the effects of sunlight on human skin begins with the effects on DNA and extends to cells, animals and humans. The major DNA photoproducts arising from UVB (280-320 nm) exposures are cyclobutane pyrimidine dimers. If unrepaired, they may kill or mutate cells and result in basal and squamous cell carcinomas. Although UVA (320-400 nm) and visible wavelengths are poorly absorbed by DNA, the existing data indicate clearly that exposures to these wavelengths are responsible, in an animal model, for {approx}95 % of the incidence of cutaneous malignant melanoma (CMM). Six lines of evidence, to be discussed in detail, support the photosensitizing role of melanin in the induction of this cancer. They are: (1) Melanomas induced in backcross hybrids of small tropical fish of the genus Xiphophorus, exposed to wavelengths from 302-547 nm, indicate that {approx}95% of the cancers induced by exposure to sunlight would arise from UVA + visible wavelengths; (2) The action spectrum for inducing melanin-photosensitized oxidant production is very similar to the spectrum for inducing melanoma; (3) Albino whites and blacks, although very sensitive to sunburn and the sunlight induction of non-CMM, have very low incidences of CMM; (4) The incidence of CMM as a function of latitude is very similar to that of UVA, but not UVB; (5) Use of UVA-exposing sun-tanning parlors by the young increases the incidence rate of CMM and (6) Major mutations observed in CMM are not UVB-induced.

  1. Porcine skin damage thresholds for 0.6 to 9.5 cm beam diameters from 1070-nm continuous-wave infrared laser radiation.

    PubMed

    Vincelette, Rebecca; Noojin, Gary D; Harbert, Corey A; Schuster, Kurt J; Shingledecker, Aurora D; Stolarski, Dave; Kumru, Semih S; Oliver, Jeffrey W

    2014-03-01

    There is an increasing use of high-power fiber lasers in manufacturing and telecommunications industries operating in the infrared spectrum between 1000 and 2000 nm, which are advertised to provide as much as 10 kW continuous output power at 1070 nm. Safety standards have traditionally been based on experimental and modeling investigations with scant data available for these wavelengths. A series of studies using 1070-nm infrared lasers to determine the minimum visible lesion damage thresholds in skin using the Yucatan miniature pig (Sus scrofa domestica) for a range of beam diameters (0.6, 1.1, 1.9, 2.4, 4.7, and 9.5 cm) and a range of exposure durations (10 ms to 10 s) is presented. Experimental peak temperatures associated with each damage threshold were measured using thermal imaging. Peak temperatures at damage threshold for the 10-s exposures were ∼10°C lower than those at shorter exposures. The lowest and highest experimental minimum visible lesion damage thresholds were found to have peak radiant exposures of 19 and 432  J/cm2 for the beam diameter-exposure duration pairs of 2.4 cm, 25 ms and 0.6 cm, 10 s, respectively. Thresholds for beam diameters >2.5  cm had a weak to no effect on threshold radiant exposure levels for exposure times ≤0.25  s, but may have a larger effect on thresholds for exposures ≥10  s.

  2. Design of a 10-bit segmented current-steering digital-to-analog converter in CMOS 65 nm technology for the bias of new generation readout chips in high radiation environment

    NASA Astrophysics Data System (ADS)

    De Robertis, G.; Loddo, F.; Mattiazzo, S.; Pacher, L.; Pantano, D.; Tamma, C.

    2016-01-01

    A new pixel front end chip for HL-LHC experiments in CMOS 65nm technology is under development by the CERN RD53 collaboration together with the Chipix65 INFN project. This work describes the design of a 10-bit segmented current-steering Digital-to-Analog Converter (DAC) to provide a programmable bias current to the analog blocks of the circuit. The main requirements are monotonicity, good linearity, limited area consumption and radiation hardness up to 10 MGy. The DAC was prototyped and electrically tested, while irradiation tests will be performed in Autumn 2015.

  3. Interaction of wide band gap single crystals with 248 nm excimer laser radiation. XII. The emission of negative atomic ions from alkali halides

    SciTech Connect

    Kimura, Kenichi; Langford, S. C.; Dickinson, J. T.

    2007-12-01

    Many wide band gap materials yield charged and neutral emissions when exposed to sub-band-gap laser radiation at power densities below the threshold for optical breakdown and plume formation. In this work, we report the observation of negative alkali ions from several alkali halides under comparable conditions. We observe no evidence for negative halogen ions, in spite of the high electron affinities of the halogens. Significantly, the positive and negative alkali ions show a high degree of spatial and temporal overlap. A detailed study of all the relevant particle emissions from potassium chloride (KCl) suggests that K{sup -} is formed by the sequential attachment of two electrons to K{sup +}.

  4. Sub-10 nm nanopantography

    NASA Astrophysics Data System (ADS)

    Tian, Siyuan; Donnelly, Vincent M.; Ruchhoeft, Paul; Economou, Demetre J.

    2015-11-01

    Nanopantography, a massively parallel nanopatterning method over large areas, was previously shown to be capable of printing 10 nm features in silicon, using an array of 1000 nm-diameter electrostatic lenses, fabricated on the substrate, to focus beamlets of a broad area ion beam on selected regions of the substrate. In the present study, using lens dimensional scaling optimized by computer simulation, and reduction in the ion beam image size and energy dispersion, the resolution of nanopantography was dramatically improved, allowing features as small as 3 nm to be etched into Si.

  5. Radiation

    NASA Video Gallery

    Outside the protective cocoon of Earth's atmosphere, the universe is full of harmful radiation. Astronauts who live and work in space are exposed not only to ultraviolet rays but also to space radi...

  6. Irradiation of human skin by short wavelength ultraviolet radiation (100--290 nm) (u.v.C): increased concentrations of arachidonic acid and prostaglandines E2 and F2alpha.

    PubMed

    Camp, R D; Greaves, M W; Hensby, C N; Plummer, N A; Warin, A P

    1978-08-01

    1. Human abdominal skin was irradiated with six times the minimal erythema dose of ultraviolet C (100--290 nm) radiation. Erythema appeared at 3 h, was of moderate degree by 6 h and was maximal at 12--24 h. It was reduced at 48 h and by 72 h had disappeared. 2. A suction bulla technique was used for the recovery of exudate from normal and inflamed skin at 6, 18, 24 and 48 h after irradiation. 3. Prostaglandin-like activity, estimated by bioassay, showed maximum increase at 18 h, when erythema was also maximum. PGF 2alpha, measured by both radioimmunoassay and by combined gas-liquid chromatography--gas spectrometry, followed a similar time course then fell to normal, or near normal, levels at 48 h. 4. Prostaglandin E2 and arachidonic acid concentrations, measured by gas chromatography--mass spectrometry, were maximally raised at 18--24 h. At 48 h, when some erythema was still present, though reduced, prostaglandin E2 concentrations were still raised above control values. 5. The results provide direct evidence in support of the view that the erythma following irradiation of human skin by u.v.C involves activation of arachidonic acid metabolism. However, the relationship between the erythema and increased prostaglandin activity is not fully understood.

  7. The eCDR, a Radiation-Hard 40/80/160/320 Mbit/s CDR with internal VCO frequency calibration and 195 ps programmable phase resolution in 130 nm CMOS

    NASA Astrophysics Data System (ADS)

    Tavernier, F.; Francisco, R.; Bonacini, S.; Poltorak, K.; Moreira, P.

    2013-12-01

    A clock and data recovery IP, the eCDR, is presented which is intended to be implemented on the detector front-end ASICs that need to communicate with the GBTX by means of e-links. The programmable CDR accepts data at 40, 80, 160 or 320Mbit/s and generates retimed data as well as 40, 80, 160 and 320MHz clocks that are aligned to the retimed data. Moreover, all the outputs have a programmable phase with a resolution of 195ps. An internal calibration mechanism enables the eCDR to lock on incoming data even without the availability of any form of reference clock. The radiation-hard design, integrated in a 130nm CMOS technology, operates at a supply voltage between 1.2V and 1.5V. The power consumption is between 28.5mW and 34.5mW, depending on the settings. The eCDR can achieve a very low RMS jitter below 10ps.

  8. Albuquerque, NM, USA

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Albuquerque, NM (35.0N, 106.5W) is situated on the edge of the Rio Grande River and flood plain which cuts across the image. The reddish brown surface of the Albuquerque Basin is a fault depression filled with ancient alluvial fan and lake bed sediments. On the slopes of the Manzano Mountains to the east of Albuquerque, juniper and other timber of the Cibola National Forest can be seen as contrasting dark tones of vegetation.

  9. In vitro germination characteristics of maize pollen to detect biological activity of environmental pollutants

    SciTech Connect

    Pfahler, P.L.

    1981-01-01

    In vitro pollen germination in maize was evaluated as a method of assessing the mutagenic and physiological effects of environmental pollutants on higher organisms. The extent of mutations was effectively determined by testing sporophytes homozygous for the mutated allele. Physiological effects were effectively determined when chemical agents were added directly into the in vitro medium. Exposure of pollen grains during in vitro germination to ultraviolet radiation in the range 280-320 nm produced little or no change in the germination or rupture percentage but a sharp decrease in pollen tube growth after 1 hr.

  10. Hazards of urocanic acid as a cosmetic ingredient.

    PubMed

    Reeve, V E; Mitchell, L E

    1991-08-01

    Certain commercially available cosmetic products have been found to contain the ingredient urocanic acid. We have shown that the solar irradiation in vitro of one such lotion resulted in the formation of cis urocanic acid. The irradiated lotion, when applied topically to the skin of hairless mice, systemically suppressed the normal contact hypersensitivity reaction to 2,4-dinitrofluorobenzene by 68%. In addition, mice exposed to a minimally erythemal dose of ultraviolet B (280-320 nm) radiation, normally sub-immunosuppressive, showed a 56% suppression of the contact hypersensitivity reaction if they were irradiated through the topically applied cosmetic lotion.

  11. Reduction of sunburn damage to skin by topical application of vitamin E acetate following exposure to ultraviolet B radiation: effect of delaying application or of reducing concentration of vitamin E acetate applied.

    PubMed

    Trevithick, J R; Shum, D T; Redae, S; Mitton, K P; Norley, C; Karlik, S J; Groom, A C; Schmidt, E E

    1993-12-01

    The skin of the skh-1 mouse after ultraviolet B (280-320 nm, UVB) irradiation shows the pathological changes typical of sunburn damage: spongiosis (edematous spaces) around some cells, necrosis of keratinocytes, giving rise to sunburn cells, inflammatory infiltration of polymorphonuclear leucocytes, etc. In our previous study, these were accompanied by erythema, increased skin sensitivity, and edematous swelling. The topical application of tocopherol acetate (TA) immediately after the UVB exposure decreased these changes. In this paper, multiple measurements of the skin thickness were made at different locations along the magnetic resonance imaging (MRI) cross-sectional image of the skin. This permits effects to be quantified with (if desired) the contralateral half of the back serving as an internal control, either exposed (positive control) or unexposed (negative control). Topical application of TA resulted in an increase in the concentration of free tocopherol in the skin. No qualitative differences in ultrastructural appearance of the UVB-irradiated, TA-treated skin could be discerned by careful examination. In vivo high resolution video microscopy of blood flow in venules of the irradiated mouse ear revealed a large (tenfold) but not statistically significant decrease in stationary lymphocytes adhering to the venule walls. The delaying of the application of TA up to 8 hours after the termination of UVB irradiation still offered statistically significant protection as did immediate application of 5% TA in diluent Myritol 318 (Delios S, Henkel).

  12. Optically pumped cerium-doped LiSrAlF.sub.6 and LiCaAlF.sub.6

    DOEpatents

    Marshall, Christopher D.; Payne, Stephen A.; Krupke, William F.

    1996-01-01

    Ce.sup.3+ -doped LiSrAlF.sub.6 crystals are pumped by ultraviolet light which is polarized along the c axis of the crystals to effectively energize the laser system. In one embodiment, the polarized fourth harmonic light output from a conventional Nd:YAG laser operating at 266 nm is arranged to pump Ce:LiSrAlF.sub.6 with the pump light polarized along the c axis of the crystal. The Ce:LiSrAlF.sub.6 crystal may be placed in a laser cavity for generating tunable coherent ultraviolet radiation in the range of 280-320 nm. Additionally, Ce-doped crystals possessing the LiSrAlF.sub.6 type of chemical formula, e.g. Ce-doped LiCaAlF.sub.6 and LiSrGaF.sub.6, can be used. Alternative pump sources include an ultraviolet-capable krypton or argon laser, or ultraviolet emitting flashlamps. The polarization of the pump light will impact operation. The laser system will operate efficiently when light in the 280-320 nm gain region is injected or recirculated in the system such that the beam is also polarized along the c axis of the crystal. The Ce:LiSrAlF.sub.6 laser system can be configured to generate ultrashort pulses, and it may be used to pump other devices, such as an optical parametric oscillator.

  13. Optically pumped cerium-doped LiSrAlF{sub 6} and LiCaAlF{sub 6}

    DOEpatents

    Marshall, C.D.; Payne, S.A.; Krupke, W.F.

    1996-05-14

    Ce{sup 3+}-doped LiSrAlF{sub 6} crystals are pumped by ultraviolet light which is polarized along the c axis of the crystals to effectively energize the laser system. In one embodiment, the polarized fourth harmonic light output from a conventional Nd:YAG laser operating at 266 nm is arranged to pump Ce:LiSrAlF{sub 6} with the pump light polarized along the c axis of the crystal. The Ce:LiSrAlF{sub 6} crystal may be placed in a laser cavity for generating tunable coherent ultraviolet radiation in the range of 280-320 nm. Additionally, Ce-doped crystals possessing the LiSrAlF{sub 6} type of chemical formula, e.g. Ce-doped LiCaAlF{sub 6} and LiSrGaF{sub 6}, can be used. Alternative pump sources include an ultraviolet-capable krypton or argon laser, or ultraviolet emitting flashlamps. The polarization of the pump light will impact operation. The laser system will operate efficiently when light in the 280-320 nm gain region is injected or recirculated in the system such that the beam is also polarized along the c axis of the crystal. The Ce:LiSrAlF{sub 6} laser system can be configured to generate ultrashort pulses, and it may be used to pump other devices, such as an optical parametric oscillator. 10 figs.

  14. Inhibition of Violaxanthin Deepoxidation by Ultraviolet-B Radiation in Isolated Chloroplasts and Intact Leaves 1

    PubMed Central

    Pfündel, Erhard E.; Pan, Run-Sun; Dilley, Richard A.

    1992-01-01

    The effect of pretreatment with ultraviolet-B (UV-B) light (280-320 nanometers) on the enzymatic conversion of the diepoxyxanthophyll violaxanthin to the epoxy-free zeaxanthin occurring in thylakoid membranes was investigated. When isolated chloroplasts of pea (Pisum sativum) were exposed to UV-B, a biologically effective fluence of 7000 joules per square meter caused about 50% inhibition of the activity of the violaxanthin deepoxidase, measured as the first order rate constant of the absorbance change at 505 nanometers. The dose requirement for the inhibition of the deepoxidase in intact leaves, however, was about 2 orders of magnitude higher. The inhibition of the rate constant was observed for both the dark deepoxidation at pH 5, and for the light-driven deepoxidation induced by the lumen acidification due to electron transport from H2O to methylviologen or due to a photosystem I partial reaction with duroquinol as the electron donor. The availability of violaxanthin was not directly affected by UV-B radiation, as shown for UV-B-treated chloroplasts by the final extent of the 505 nanometer change measured in the dark at pH 5 or by the partial photosystem I reaction. A significant decrease in the violaxanthin availability was observed when lumen acidification was caused by electron transport from H2O to methylviologen. That effect was probably caused by the wellknown UV-B inhibition of photosystem II with a subsequent decreased ability to reduce the plastoquinone pool, the redox state of which is believed to regulate the final amount of converted violaxanthin. PMID:16668802

  15. The interaction of 193 nm excimer laser radiation with single-crystal zinc oxide: Generation of long lived highly excited particles with evidence of Zn Rydberg formation

    SciTech Connect

    Khan, Enamul H.; Langford, S. C.; Dickinson, J. T.; Boatner, L. A.

    2014-08-28

    In past studies, we have observed copious emissions of ionic and atomic Zn from single-crystal ZnO accompanying irradiation of single-crystal ZnO with 193-nm excimer laser irradiation at fluences below the onset of optical breakdown. The Zn{sup +} and ground state Zn° are studied using time-of-flight techniques and are mass selected using a quadrupole mass spectrometer. Simultaneously, we have observed emitted particles that are detectable with a Channeltron electron multiplier but cannot be mass selected. It is a reasonable hypothesis that these particles correspond to a neutral atom or molecule in highly excited long lived states. We provide strong evidence that they correspond to high lying Rydberg states of atomic Zn. We propose a production mechanism involving laser excitation via a two photon resonance excitation of Zn°.

  16. 469nm Fiber Laser Source

    SciTech Connect

    Drobshoff, A; Dawson, J W; Pennington, D M; Payne, S A; Beach, R

    2005-01-20

    We have demonstrated 466mW of 469nm light from a frequency doubled continuous wave fiber laser. The system consisted of a 938nm single frequency laser diode master oscillator, which was amplified in two stages to 5 Watts using cladding pumped Nd{sup 3+} fiber amplifiers and then frequency doubled in a single pass through periodically poled KTP. The 3cm long PPKTP crystal was made by Raicol Crystals Ltd. with a period of 5.9 {micro}m and had a phase match temperature of 47 degrees Centigrade. The beam was focused to a 1/e{sup 2} diameter in the crystal of 29 {micro}m. Overall conversion efficiency was 11% and the results agreed well with standard models. Our 938nm fiber amplifier design minimizes amplified spontaneous emission at 1088nm by employing an optimized core to cladding size ratio. This design allows the 3-level transition to operate at high inversion, thus making it competitive with the 1088nm 4-level transition. We have also carefully chosen the fiber coil diameter to help suppress propagation of wavelengths longer than 938 nm. At 2 Watts, the 938nm laser had an M{sup 2} of 1.1 and good polarization (correctable with a quarter and half wave plate to >10:1).

  17. A contribution toward understanding the biospherical significance of Antarctic ozone depletion

    NASA Technical Reports Server (NTRS)

    Lubin, Dan; Mitchell, Greg; Frederick, John E.; Alberts, Amy D.; Booth, C. R.; Lucas, Timothy; Neuschuler, David

    1992-01-01

    The paper presents and compares measurements of biologically active UV radiation made by the NSF scanning spectroradiometer (UV-monitor) at Palmer Station, Antarctica, during the Austral springs of 1988, 1989, and 1990. Column ozone abundance above Palmer Station is computed from these measurements using a multiple wavelength algorithm. Two contrasting action spectra are employed to estimate the biologically relevant dose from the spectral measurements: a standard weighting function for damage to DNA, and a new action spectrum representing the potential for photosynthesis inhibition in Antarctic phytoplankton. The former weights only UV-B wavelengths (280-320 nm) and gives the most weight to wavelengths shorter than 300 nm, while the latter includes large contributions out to 355 nm. Ozone abundances and dose-weighted irradiances provided by the NSF UV-monitor are used to derive the radiation amplification factors for both DNA- and phytoplankton-effective irradiance.

  18. Histogenesis and progression of ultraviolet light-induced tumors in hairless mice

    SciTech Connect

    Kligman, L.H.; Kligman, A.M.

    1981-12-01

    Tumor histogenesis and progression were studied in UV-irradiated albino (Skh:hairless-1) and lightly pigmented (Skh:hairless-2) hairless mice. A strongly carcinogenic dose of UV light was used, producing 100% tumor incidence by 35 weeks. The light source emitted mainly UV radiation in the range of 280-320 nm and the less energetic UV radiation up to 400 nm. The resulting epidermal changes and neoplasms resembled those seen in the actinically damaged skin of humans. Microscopic lesions included benign hyperplasia, actinic keratoses, and squamous cell carcinoma in situ and with microinvasion. Clinical tumors were epithelial papillomas, fibropapillomas, keratoacanthomas, cystic keratomas, benign pigmented macules, cutaneous hornlike growths, exophytic and endophytic squamous cell carcinomas of several cytologic types, and fibrosarcomas. Even with this high dose of UV radiation, not all of the small tumors progressed to cancer. Many regressed, including some keratoacanthomas, whereas others remained small and benign for the lifetime of the mouse.

  19. Histogenesis and progression in ultraviolet light-induced tumors in hairless mice

    SciTech Connect

    Kligman, L.H.; Kligman, A.M.

    1981-12-01

    Tumor histogenesis and progression were studied in UV-irradiated albino (Skh:hairless-1) and lightly pigmented (Skh:hairless-2) hairless mice. A strongly carcinogenic dose of UV light was used, producing 100% tumor incidence by 35 weeks. The light source emitted mainly UV radiation in the range of 280-320 nm and the less energetic UV radiation up to 400 nm. The resulting epidermal changes and neoplasms resembled those seen in the actinically damaged skin of humans. Microscopic lesions included benign hyperplasia, actinic keratoses, and squamous cell carcinoma in situ and with microinvasion. Clinical tumors were epithelial papillomas, fibropapillomas, keratoacanthomas, cystic keratomas, benign pigmented macules, cutaneous hornlike growth, exophytic and endophytic squamous cell carcinomas of several cytologic types, and fibrosarcomas. Even with this high dose of UV radiation, not all of the small tumors progressed to cancer. Many regressed, including some keratoacanthomas, whereas others remained small and benign for the lifetime of the mouse.

  20. Nanobumps on silicon created with polystyrene spheres and 248 or 308 nm laser pulses

    SciTech Connect

    Piparia, Reema; Rothe, Erhard W.; Baird, R. J.

    2006-11-27

    Huang et al. [Appl. Phys. Lett. 86, 161911 (2005)] formed arrays of nanobumps on a silicon substrate. They applied a 248 nm laser pulse to a surface monolayer of 1-{mu}m-diameter polystyrene spheres. The authors first replicated their experiment with 248 nm light. But when 308 nm pulses were applied instead, the nanobumps had a different shape and composition. At 248 nm, much of the laser light is absorbed in the polystyrene, which serves to quickly distort, melt, and ablate the sphere. At 308 nm, very little light is absorbed. The nanobumps from 248 nm radiation are organic polymers, while those formed with 308 nm pulses are silicon based.

  1. Pulsed blue laser at 491 nm by nonlinear cavity dumping.

    PubMed

    Herault, Emilie; Lelek, Mickaël; Balembois, François; Georges, Patrick

    2008-11-24

    A nonlinear cavity dumping process is applied for the first time to generate kW peak power pulses at 491 nm. The system is based on efficient sum-frequency mixing of 1063 nm and 912 nm radiations in a BiBO nonlinear crystal placed inside a Nd:GdVO4 laser oscillator with a high finesse cavity at 912 nm. The nonlinear cavity dumping process is triggered by high peak power nanosecond pulses from a 1063 nm Q-switched Nd:GdVO4 laser operating at 10 kHz. To reach the kW range at 491 nm a key point is to Q-switch the high finesse 912 nm cavity instead of continuous wave operation. Thus, the peak power (9.3 kW for 3 ns pulses) and the average power (280 mW) obtained at 491 nm are 14 times higher than the one obtained when the 912 nm laser operated in continuous wave. PMID:19030029

  2. Photoionization of Nitromethane at 355nm and 266nm

    NASA Astrophysics Data System (ADS)

    Martínez, Denhi; Betancourt, Francisco; Poveda, Juan Carlos; Guerrero, Alfonso; Cisneros, Carmen; Álvarez, Ignacio

    2014-05-01

    Nitromethane is one of the high-yield clean liquid fuels, i.e., thanks to the oxygen contained in nitromethane, much less atmospheric oxygen is burned compared to hydrocarbons such as gasoline, making the nitromethane an important prototypical energetic material, the understanding of its chemistry is relevant in other fields such as atmospheric chemistry or biochemistry. In this work we present the study of photoionization dynamics by multiphoton absorption with 355 nm and 266 nm wavelength photons, using time of flight spectrometry in reflectron mode (R-TOF). Some of the observed ion products appear for both wavelength and other only in one of them; both results were compared with preview observations and new ions were detected. This work is supported by CONACYT grant 165410 and DGAPA-UNAM grants IN-107-912 and IN-102-613.

  3. Generation of continuous-wave 194 nm laser for mercury ion optical frequency standard

    NASA Astrophysics Data System (ADS)

    Zou, Hongxin; Wu, Yue; Chen, Guozhu; Shen, Yong; Liu, Qu; Precision measurement; atomic clock Team

    2015-05-01

    194 nm continuous-wave (CW) laser is an essential part in mercury ion optical frequency standard. The continuous-wave tunable radiation sources in the deep ultraviolet (DUV) region of the spectrum is also serviceable in high-resolution spectroscopy with many atomic and molecular lines. We introduce a scheme to generate continuous-wave 194 nm radiation with SFM in a Beta Barium Borate (BBO) crystal here. The two source beams are at 718 nm and 266 nm, respectively. Due to the property of BBO, critical phase matching (CPM) is implemented. One bow-tie cavity is used to resonantly enhance the 718 nm beam while the 266 nm makes a single pass, which makes the configuration easy to implement. Considering the walk-off effect in CPM, the cavity mode is designed to be elliptical so that the conversion efficiency can be promoted. Since the 266 nm radiation is generated by a 532 nm laser through SHG in a BBO crystal with a large walk-off angle, the output mode is quite non-Gaussian. To improve mode matching, we shaped the 266 nm beam into Gaussian modes with a cylindrical lens and iris diaphragm. As a result, 2.05 mW 194 nm radiation can be generated. As we know, this is the highest power for 194 nm CW laser using SFM in BBO with just single resonance. The work is supported by the National Natural Science Foundation of China (Grant No. 91436103 and No. 11204374).

  4. Efficient generation of 1096 nm and 1572 nm by simultaneous stimulated Raman scattering and optical parametric oscillation in one KTiOPO4 crystal

    NASA Astrophysics Data System (ADS)

    Huang, H. T.; He, J. L.; Liu, S. D.; Yang, J. F.; Zhang, B. T.; Liu, F. Q.

    2011-04-01

    The simultaneous stimulated Raman scattering (SRS) and optical parametric oscillation (OPO) for the 1064 nm radiation were realized in one KTP crystal for the first time. At an incident diode laser power of 8.6 W, the maximum average output powers at 1096 nm and 1572 nm were 1.1 W and 0.36 W, respectively. The conversion efficiency to Stokes with respect to the incident diode power was as high as 12.8%. The corresponding minimum pulse widths at 1096 nm and 1572 nm were 2.8 and 1.1 ns, respectively.

  5. Generation of Thermospheric OI 845 nm Emission by Bowen Fluorescence

    NASA Astrophysics Data System (ADS)

    Huestis, D. L.; Sharpee, B. D.; Cosby, P. C.; Slanger, T. G.

    2006-12-01

    777 and 845 nm emissions from the 3p-3s multiplets of atomic oxygen are commonly observed at non-auroral latitudes in the terrestrial nightglow. By studying the relative strengths of these emissions we can learn something about the mechanisms that produce them and what they can teach us about the atmosphere. Recently [1] we have used intensity-calibrated sky spectra from the Keck telescopes to investigate the relative strengths of a wide range of O-atom Rydberg lines and have confirmed that electron-ion radiative recombination is a primary source of excitation for both the triplet and quintet systems. Following the intensity of the 777 and 845 nm lines during the night, we find that for most of the night the quintet 777 nm line is consistently stronger than the triplet 845 nm line, with a nearly constant intensity ratio I(777)/I(845) near 2.3, although both intensities fall rapidly as the night progresses. However, late in the night the 845 nm intensity levels off, while the 777 nm intensity continues to fall, and the I(777)/I(845) ratio plunges by a factor of 5-10. We interpret these observations as indicating that the O-atom quintet states are still being excited by the same mechanism as earlier in the night, i.e. radiative recombination, but some triplet states are also being excited by an additional mechanism. Such a mechanism has been proposed before [2-6] but not previously observed directly in the terrestrial nightglow. The oxygen triplet 3d-2p transition at 102.576 nm is in close coincidence with the solar hydrogen Lyman-β line at 102.572 nm. Radiative transport in the hydrogen geocorona will deliver Lyman-β intensity into the Earth's shadow and will produce triplet O(3d 3D) high in the atmosphere, even prior to direct solar illumination. The result is observable in a radiative cascade sequence 3d-3p(1129 nm) → 3p- 3s(845 nm) → 3s-2p(130 nm). A similar effect is observed in the H-α emission, which is also excited by Lyman-β absorption. This process

  6. High-efficiency high-brightness diode lasers at 1470 nm/1550 nm for medical and defense applications

    NASA Astrophysics Data System (ADS)

    Gallup, Kendra; Ungar, Jeff; Vaissie, Laurent; Lammert, Rob; Hu, Wentao

    2012-03-01

    Diode lasers in the 1400 nm to 1600 nm regime are used in a variety of applications including pumping Er:YAG lasers, range finding, materials processing, aesthetic medical treatments and surgery. In addition to the compact size, efficiency, and low cost advantages of traditional diode lasers, high power semiconductor lasers in the eye-safe regime are becoming widely used in an effort to minimize the unintended impact of potentially hazardous scattered optical radiation from the laser source, the optical delivery system, or the target itself. In this article we describe the performance of high efficiency high brightness InP laser bars at 1470nm and 1550nm developed at QPC Lasers for applications ranging from surgery to rangefinding.

  7. 32nm overlay improvement capabilities

    NASA Astrophysics Data System (ADS)

    Eichelberger, Brad; Huang, Kevin; O'Brien, Kelly; Tien, David; Tsai, Frank; Minvielle, Anna; Singh, Lovejeet; Schefske, Jeffrey

    2008-03-01

    The industry is facing a major challenge looking forward on the technology roadmap with respect to overlay control. Immersion lithography has established itself as the POR for 45nm and for the next few nodes. As the gap closes between scanner capability and device requirements new methodologies need to be taken into consideration. Double patterning lithography is an approach that's being considered for 32 and below, but it creates very strict demands for overlay performance. The fact that a single layer device will need to be patterned using two sequential single processes creates a strong coupling between the 1st and 2nd exposure. The coupling effect during the double patterning process results in extremely tight tolerances for overlay error and scanner capabilities. The purpose of this paper is to explore a new modeling method to improve lithography performance for the 32nm node. Not necessarily unique for double patterning, but as a general approach to improve overlay performance regardless of which patterning process is implemented. We will achieve this by performing an in depth source of variance analysis of current scanner performance and project the anticipated improvements from our new modeling approach. Since the new modeling approach will involve 2nd and 3rd order corrections we will also provide and analysis that outlines current metrology capabilities and sampling optimizations to further expand the opportunities of an efficient implementation of such approach.

  8. Mechanistic comparison of pulse laser induced phase separation of particulates from cellulose paper at 213 nm and 532 nm

    NASA Astrophysics Data System (ADS)

    Arif, S.; Forster, M.; Bushuk, S.; Kouzmouk, A.; Tatur, H.; Batishche, S.; Kautek, W.

    2013-02-01

    The laser-induced phase separation of charcoal particles on additive-free cotton linters cellulose paper was investigated by electron and optical microscopy, colorimetry, and diffuse reflectance FT-IR. The fibre bundles were vaporised in depth of several 10 μm above destruction fluence thresholds using visible 532 nm radiation. This is in contrast to mid-ultraviolet 213 nm radiation, where only the top fibre bundles were modified and partially evaporated. The colorimetric lightness results generally represented the cleaning status, whereas the colorimetric yellowing data represented irreversible chemical and/or photochemical changes. Charcoal-contaminated paper treated with visible and mid-ultraviolet radiation exhibited yellowing, whereas uncontaminated did not. This suggests that the electron-rich plasma generated by the evaporation of the particles heats the adjacent substrate and also excludes oxygen. Mid-ultraviolet, in contrast to visible radiation, shows particle removal always accompanied by paper destruction. IR spectroscopy results suggest cross-linking by ether bonds near the destruction threshold, but do not prove the formation of oxidation products and double bonds as the basis of the yellowing. A "cleaning window" between the cleaning threshold (0.1 J/cm2) and the paper destruction threshold (2.9 J/cm2) with a pulse number of 2 is provided by visible 532 nm laser treatment.

  9. Induction of photolyase activity in wood frog (Rana sylvatica) embryos.

    PubMed

    Smith, M A; Kapron, C M; Berrill, M

    2000-10-01

    Rising ultraviolet-B (UVB, 280-320 nm) radiation has been proposed as a factor which may explain nonnormal amphibian population declines. Accordingly research has been directed toward estimating the photolyase activity of several amphibian species in order to predict a species' resilience to UV damage. Unfortunately, in spite of published research which demonstrated that the activity of one of the principal photorepair enzymes, photolyase, can be induced, these estimates did not address the potential for in vivo induction by environmental factors present in situ. We show here that wood frog (Rana sylvatica) embryos exposed to periods of ambient solar radiation (1) displayed significantly different photolyase activities from embryos exposed to equivalent periods of dark; and (2) were positively correlated with the UVB fluence received in vivo. Such results suggest that previous conclusions regarding the relationship between photorepair and population decline must be reevaluated. Estimating amphibian photorepair is a complicated process, and caution must be exercised when interpreting such data. PMID:11045732

  10. Defect inspection of imprinted 32 nm half pitch patterns

    NASA Astrophysics Data System (ADS)

    Selinidis, Kosta; Thompson, Ecron; McMackin, Ian; Perez, Joseph; Sreenivasan, S. V.; Resnick, Douglas J.

    2008-10-01

    Step and Flash Imprint Lithography redefines nanoimprinting. This novel technique involves the field-by-field deposition and exposure of a low viscosity resist deposited by jetting technology onto the substrate. The patterned mask is lowered into the fluid which then quickly flows into the relief patterns in the mask by capillary action. Following this filling step, the resist is crosslinked under UV radiation, and then the mask is removed leaving a patterned solid on the substrate. Compatibility with existing CMOS processes requires a mask infrastructure in which resolution, inspection and repair are all addressed. The purpose of this paper is to understand the limitations of inspection at half pitches of 32 nm and below. A 32 nm programmed defect mask was fabricated. Patterns included in the mask consisted of an SRAM Metal 1 cell, dense lines, and dense arrays of pillars. Programmed defect sizes started at 4 nm and increased to 48 nm in increments of 4 nm. Defects in both the mask and imprinted wafers were characterized scanning electron microscopy and the measured defect areas were calculated. These defects were then inspected using a KLA-T eS35 electron beam wafer inspection system. Defect sizes as small as 12 nm were detected, and detection limits were found to be a function of defect type.

  11. Electron beam inspection methods for imprint lithography at 32 nm

    NASA Astrophysics Data System (ADS)

    Selinidis, Kosta; Thompson, Ecron; Sreenivasan, S. V.; Resnick, Douglas J.

    2009-01-01

    Step and Flash Imprint Lithography redefines nanoimprinting. This novel technique involves the field-by-field deposition and exposure of a low viscosity resist deposited by jetting technology onto the substrate. The patterned mask is lowered into the fluid which then quickly flows into the relief patterns in the mask by capillary action. Following this filling step, the resist is crosslinked under UV radiation, and then the mask is removed leaving a patterned solid on the substrate. Compatibility with existing CMOS processes requires a mask infrastructure in which resolution, inspection and repair are all addressed. The purpose of this paper is to understand the limitations of inspection at half pitches of 32 nm and below. A 32 nm programmed defect mask was fabricated. Patterns included in the mask consisted of an SRAM Metal 1 cell, dense lines, and dense arrays of pillars. Programmed defect sizes started at 4 nm and increased to 48 nm in increments of 4 nm. Defects in both the mask and imprinted wafers were characterized scanning electron microscopy and the measured defect areas were calculated. These defects were then inspected using a KLA-T eS35 electron beam wafer inspection system. Defect sizes as small as 12 nm were detected, and detection limits were found to be a function of defect type.

  12. The polarization properties of Fe II 614.9 nm

    NASA Technical Reports Server (NTRS)

    Lites, Bruce W.

    1993-01-01

    The anomalous Zeeman splitting of the Fe II line at 614.9 nm results in four unusual properties of the polarization signature of this line in the presence of magnetic fields: the absence of linear polarization, no magnetooptical effect, the independence of intensity at line center from the inclination of the field, and a depolarizing self-absorption. The origin of these properties is illustrated in terms of the transfer of line radiation in an idealized solar atmosphere.

  13. Electro-optically Q-switched dual-wavelength Nd:YLF laser emitting at 1047 nm and 1053 nm

    NASA Astrophysics Data System (ADS)

    Men, Shaojie; Liu, Zhaojun; Cong, Zhenhua; Li, Yongfu; Zhang, Xingyu

    2015-05-01

    A flash-lamp pumped electro-optically Q-switched dual-wavelength Nd:YLF laser is demonstrated. Two Nd:YLF crystals placed in two cavities are employed to generate orthogonally polarized 1047 nm and 1053 nm radiations, respectively. The two cavities are jointed together by a polarizer and share the same electro-optical Q-switch. Two narrow-band pass filters are used to block unexpected oscillations at the hold-off state of the electro-optical Q-switch. In this case, electro-optical Q-switching is able to operate successfully. With pulse synchronization realized, the maximum output energy of 66.2 mJ and 83.9 mJ are obtained for 1047 nm and 1053 nm lasers, respectively. Correspondingly, the minimum pulse width is both 17 ns for 1047 nm and 1053 nm lasers. Sum frequency generation is realized. This demonstrates the potential of this laser in difference-frequency generations to obtain terahertz wave.

  14. A nanosecond regenerative Ti:Sapphire amplifier for the simultaneous generation of 940 nm and of 320 nm pulses

    NASA Astrophysics Data System (ADS)

    Talluto, Vincenzo; Blochowicz, Thomas; Walther, Thomas

    2016-05-01

    Narrowband cw radiation at 940 and 960 nm is used to seed a Nd:YAG-pumped regenerative Ti:Sapphire amplifier. A Pockels cell traps a slice of the seed radiation inside the amplifier cavity, generating two synchronized pulses and releasing them after amplification. The total pulse energy is as high as 9 mJ at a pulse duration of 6.5 ns and a Fourier-transform-limited bandwidth. The timing jitter between the two pulses at the two wavelengths is less than ±300 ps. The relative pulse energy can be controlled by the relative seed laser power. Up to 1 mJ pulse energy at 320 nm was achieved by third-harmonic generation.

  15. High-power 467-nm passively locked signal-resonant sum-frequency laser

    SciTech Connect

    Wigley, P.G.; Zhang, Q.; Miesak, E.; Dixon, G.J.

    1995-12-01

    We have generated more than 120 mW of TEM{sub 00} radiation at 467 nm by summing the resonantly enhanced output of an 845-nm GaAlAs tapered semiconductor amplifier with the intracavity field of a 1047-nm diode-pumped Nd:YLF laser, using a KTP crystal. Optical feedback was used to lock the frequency of the tapered amplifier to a cavity resonance. {copyright} {ital 1995 Optical Society of America.}

  16. Broadband terahertz generation and detection at 10 nm scale.

    PubMed

    Ma, Yanjun; Huang, Mengchen; Ryu, Sangwoo; Bark, Chung Wung; Eom, Chang-Beom; Irvin, Patrick; Levy, Jeremy

    2013-06-12

    Terahertz (0.1-30 THz) radiation reveals a wealth of information that is relevant for material, biological, and medical sciences with applications that span chemical sensing, high-speed electronics, and coherent control of semiconductor quantum bits. To date, there have been no methods capable of controlling terahertz (THz) radiation at molecular scales. Here we report both generation and detection of broadband terahertz field from 10 nm scale oxide nanojunctions. Frequency components of ultrafast optical radiation are mixed at these nanojunctions, producing broadband THz emission. These same devices detect THz electric fields with comparable spatial resolution. This unprecedented control, on a scale of 4 orders of magnitude smaller than the diffraction limit, creates a pathway toward THz-bandwidth spectroscopy and control of individual nanoparticles and molecules.

  17. Baicalin Scavenged Reactive Oxygen Species and Protected Human Keratinocytes Against UVB-induced Cytotoxicity.

    PubMed

    Chang, Wen-Shin; Lin, En-Yuan; Hsu, Shih-Wei; Hu, Pei-Shin; Chuang, Chin-Liang; Liao, Cheng-Hsi; Fu, Chun-Kai; Su, Chung-Hao; Gong, Chi-Li; Hsiao, Chieh-Lun; Bau, DA-Tian; Tsai, Chia-Wen

    Ultraviolet B (UVB), with a wavelength of 280-320 nm, represents one of the most important environmental factors for skin disorders, including sunburn, hyperpigmentation, solar keratosis, solar elastosis and skin cancer. Therefore, protection against excessive UVA-induced damage is useful for prevention of sunburn and other human diseases. Baicalin, a major component of traditional Chinese medicine Scutellaria baicalensis, has been reported to possess antioxidant and cytostatic capacities. In this study, we examined whether baicalin is also capable of protecting human keratinocytes from UVB irradiation. The results showed that baicalin effectively scavenged reactive oxygen species (ROS) elevated within 4 h after UVB radiation and reversed the UVB-suppressed cell viability and UVB-induced apoptosis after 24 h. Our results demonstrated the utility of baicalin to complement the contributions of traditional Chinese medicine in UVB-induced damage to skin and suggested their potential application as pharmaceutical agents in long-term sun-shining injury prevention. PMID:27566079

  18. Performance of Thin Borosilicate Glass Sheets at 351-nm

    SciTech Connect

    Whitman, P K; Hahn, D; Soules, T; Norton, M; Dixit, S; Donohue, G; Folta, J; Hollingsworth, W; Mainschein-Cline, M

    2004-11-11

    Previously, we reported preliminary results for commercial thin borosilicate glass sheets evaluated for use as a frequently-replaced optic to separate the radiation and contamination produced by the inertial confinement fusion experiments in the National Ignition Facility target chamber from the expensive precision laser optics which focus and shape the 351-nm laser beam. The goal is identification of low cost substrates that can deliver acceptable beam energy and focal spots to the target. The two parameters that dominate the transmitted beam quality are the transmitted wave front error and 351-nm absorption. Commercial materials and fabrication processes have now been identified which meet the beam energy and focus requirements for all of the missions planned for the National Ignition Facility. We present the first data for use of such an optic on the National Ignition Facility laser.

  19. Performance of Thin Borosilicate Glass Sheets at 351-nm

    SciTech Connect

    Whitman, P K; Staggs, M; Carr, W; Dixit, S; Sell, W; Milam, D

    2001-11-01

    Commercial thin borosilicate glass sheets have been evaluated for use as a single-shot optic ''debris shield'' to separate the radiation and contamination produced by the inertial confinement fusion (ICF) experiment from the expensive precision laser optics which focus and shape the 351-nm laser beam which irradiates the target. The goal of this work is identification of low cost materials that can deliver acceptable beam energy and focal spots to the target. The two parameters that dominate the transmitted beam quality are the transmitted wave front error and bulk absorption. This paper focuses on the latter. To date, the materials with the lowest linear 351-nm absorption have also generally demonstrated the lowest non-linear absorption. Commercial materials have been identified which approach the beam energy and focus requirements for many ICF missions.

  20. Wavelength Dependence in the Analysis of Carbon Content in Coal by Nanosecond 266 nm and 1064 nm Laser Induced Breakdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Xiongwei; Wang, Zhe; Fu, Yangting; Li, Zheng; Ni, Weidou

    2015-08-01

    The wavelength dependence of laser induced breakdown spectroscopy (LIBS) in the analysis of the carbon contents of coal was studied using 266 nm and 1064 nm laser radiations. Compared with the 1064 nm wavelength laser ablation, the 266 nm wavelength laser ablation has less thermal effects, resulting in a better crater morphology on the coal pellets. Besides, the 266 nm wavelength laser ablation also provides better laser-sample coupling and less plasma shielding, resulting in a higher carbon line intensity and better signal reproducibility. The carbon contents in the bituminous coal samples have better linearity with the line intensities of atomic carbon measured by the 266 nm wavelength than those measured by the 1064 nm wavelength. The partial least square (PLS) model was established for the quantitative analysis of the carbon content in coal samples by LIBS. The results show that both of the 266 nm and 1064 nm wavelengths are capable of achieving good performance for the quantitative analysis of carbon content in coal using the PLS method. supported by National Natural Science Foundation of China (No. 51276100) and National Basic Research Program of China (973 Program) (No. 2013CB228501)

  1. Diode-pumped doubly resonant all-intracavity continuous-wave ultraviolet laser at 336 nm

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Sun, G. C.; Fu, X. H.; Liu, Z. T.; Chen, J. F.

    2010-08-01

    We report for the first time a coherent ultraviolet radiation at 336 nm by intracavity sum-frequency generation of a 912 nm Nd:GdVO4 laser and a 532 nm frequency doubling Nd:YVO4 laser. The ultraviolet laser is obtained by using a doubly resonator, type-I critical phase matching CsLiB6O10 (CLBO) crystal sum-frequency mixing. With a total diode pump power of 31.8 W (13.1 W pump power for 912 nm Nd:GdVO4 laser and 18.7 W pump power for 532 nm Nd:YVO4 frequency doubling laser), TEM00 mode ultraviolet laser at 336 nm of 93 mW is obtained. The power stability is better than 3.4% and laser beam quality M2 factors are 1.52 and 1.27 in both horizontal and vertical dimensions respectively.

  2. UV Generation of 25 mJ/pulse at 289 nm for Ozone Lidar

    NASA Technical Reports Server (NTRS)

    Storm, Mark E.; Marsh, Waverly; Barnes, James C.

    1998-01-01

    Our paper describes a technique for generating tunable UV laser radiation between 250-300 nm capable of energies up to 30-5O mJ/pulse. The tunability of this source is attractive for selecting ozone absorption cross sections which are optimal for ozone DIAL detection throughout the troposphere. A Nd:YAG laser is used to pump a pulsed titanium sapphire laser which is then frequency tripled into the UV. Titanium sapphire (TiS) lases robustly between 750-900 nm. In initial experiments we have converted 110 mJ of 867 nm from a TiS laser into 28 mJ at 289 nm. The energy conversion efficiency was 62% for doubling into 433 nm and 25% into 289 nm.

  3. Simultaneous triple 914 nm, 1084 nm, and 1086 nm operation of a diode-pumped Nd:YVO4 laser

    NASA Astrophysics Data System (ADS)

    Lü, Yanfei; Xia, Jing; Liu, Huilong; Pu, Xiaoyun

    2014-10-01

    We report a diode-pumped continuous-wave (cw) triple-wavelength Nd:YVO4 laser operating at 914, 1084, and 1086 nm. A theoretical analysis has been introduced to determine the threshold conditions for simultaneous triple-wavelength laser. Using a T-shaped cavity, we realized an efficient triple-wavelength operation at 4F3/2→4I9/2 and 4F3/2→4I11/2 transitions for Nd:YVO4 crystal, simultaneously. At an absorbed pump power of 16 W (or 25 W of incident pump power), the maximum output power was 2.3 W, which included 914 nm, 1084 nm, and 1086 nm three wavelengths, and the optical conversion efficiency with respect to the absorbed pump power was 14.4%.

  4. Deposition of robust multilayer mirror coatings for storage ring FEL lasing at 176nm

    NASA Astrophysics Data System (ADS)

    Günster, St.; Ristau, D.; Trovó, M.; Danailov, M.; Gatto, A.; Kaiser, N.; Sarto, F.; Piegari, A.

    2005-09-01

    Progress was achieved in the last years in the development of multilayer mirrors used in storage ring Free Electron Lasers (FEL) operating in the vacuum ultraviolet spectral range. Based on dense oxide coatings deposited by Ion Beam Sputtering, a stable lasing at 190 nm was demonstrated. The extension towards shorter wavelengths had to overcome severe problems connected to the radiation resistance and the necessary reflectivity of the resonator mirrors. In this context, radiation resistance can be considered as the ability of the mirror materials to withstand the high power laser radiation and the intense energetic background radiation generated in the synchrotron source. The bombardment with high energetic photons leads to irreversible changes and a coloration on the specimen. Reflectivity requirements can be evaluated from the tolerable losses of FEL systems. At ELETTRA FEL the resonator mirror reflectivity must be above 95 %. Evaporated fluoride multilayer mirrors provide sufficient reflectivity, but they do not exhibit an adequate radiation resistance. Pure oxide multilayers show a sufficient radiation resistance, but they cannot reach the necessary reflectivity below 190 nm. A successful approach combines evaporated fluoride multilayer stack with a dense protection layer of silicon dioxide deposited by Ion Beam Sputtering. Such mirror systems were produced reaching a reflectivity of approximately 99 % at 180 nm. Lasing in the storage ring FEL at ELETTRA was realised in the range between 176 - 179 nm. The mirror reflectivity shows only a slight degradation after lasing, which could be fully restored after the lasing experiment.

  5. Sub-10 nm nanopantography

    SciTech Connect

    Tian, Siyuan Donnelly, Vincent M. E-mail: economou@uh.edu; Economou, Demetre J. E-mail: economou@uh.edu; Ruchhoeft, Paul

    2015-11-09

    Nanopantography, a massively parallel nanopatterning method over large areas, was previously shown to be capable of printing 10 nm features in silicon, using an array of 1000 nm-diameter electrostatic lenses, fabricated on the substrate, to focus beamlets of a broad area ion beam on selected regions of the substrate. In the present study, using lens dimensional scaling optimized by computer simulation, and reduction in the ion beam image size and energy dispersion, the resolution of nanopantography was dramatically improved, allowing features as small as 3 nm to be etched into Si.

  6. Fabrication of 10nm diameter carbon nanopores

    SciTech Connect

    Radenovic, Aleksandra; Trepagnier, Eliane; Csencsits, Roseann; Downing, Kenneth H; Liphardt, Jan

    2008-09-25

    The addition of carbon to samples, during imaging, presents a barrier to accurate TEM analysis, the controlled deposition of hydrocarbons by a focused electron beam can be a useful technique for local nanometer-scale sculpting of material. Here we use hydrocarbon deposition to form nanopores from larger focused ion beam (FIB) holes in silicon nitride membranes. Using this method, we close 100-200nm diameter holes to diameters of 10nm and below, with deposition rates of 0.6nm per minute. I-V characteristics of electrolytic flow through these nanopores agree quantitatively with a one dimensional model at all examined salt concentrations.

  7. Laser Damage Growth in Fused Silica with Simultaneous 351 nm and 1053 nm irradiation

    SciTech Connect

    Norton, M A; Carr, A V; Carr, C W; Donohue, E E; Feit, M D; Hollingsworth, W G; Liao, Z; Negres, R A; Rubenchik, A M; Wegner, P J

    2008-10-24

    Laser-induced growth of optical damage often determines the useful lifetime of an optic in a high power laser system. We have extended our previous work on growth of laser damage in fused silica with simultaneous 351 nm and 1053 nm laser irradiation by measuring the threshold for growth with various ratios of 351 nm and 1053 nm fluence. Previously we reported that when growth occurs, the growth rate is determined by the total fluence. We now find that the threshold for growth is dependent on both the magnitude of the 351 nm fluence as well as the ratio of the 351 nm fluence to the 1053 nm fluence. Furthermore, the data suggests that under certain conditions the 1053 nm fluence does not contribute to the growth.

  8. Coherent quasi-CW 153-nm light source at high repetition rate

    NASA Astrophysics Data System (ADS)

    Nomura, Yutaka; Ito, Yoshiaki; Ozawa, Akira; Wang, Xiaoyang; Chen, Chuangtian; Shin, Shik; Watanabe, Shuntaro; Kobayashi, Yohei

    2012-02-01

    We present a quasi-cw laser in vacuum ultraviolet region at megahertz repetition rate. The narrowband pulses generated from an ytterbium-fiber laser system at 33 MHz repetition rate at the central wavelength of 1074 nm is frequency-converted by successive stages of LBO crystals and KBBF crystals. The generated radiation at 153 nm has the shortest wavelength achieved through phase-matched frequency conversion processes in nonlinear optical crystals to our knowledge.

  9. A 4 to 0.1 nm FEL Based on the SLAC Linac

    SciTech Connect

    Pellegrini, C.; /UCLA

    2012-06-05

    The author show that using existing electron gun technology and a high energy linac like the one at SLAC, it is possible to build a Free Electron Laser operating around the 4 nm water window. A modest improvement in the gun performance would further allow to extend the FEL to the 0.1 nm region. Such a system would produce radiation with a brightness many order of magnitude above that of any synchrotron radiation source, existing or under construction, with laser power in the multigawatt region and subpicosecond pulse length.

  10. Passive Fraunhofer-wavelength atomic filter at 422.7 nm.

    PubMed

    Gelbwachs, J A; Chan, Y C

    1991-03-01

    We have demonstrated 25% internal photon conversion efficiency of a new passive atomic filter. The signal wavelength matches an intense Fraunhofer line at 422.7 nm, thereby offering enhanced sunlight rejection. A quasimolecular interaction promotes rapid energy transfer between the 4p (1)P(1) level and the 4p (3)P(J) level of neutral calcium for wavelength shifting of 422.7-nm light into 657.3-nm emission. We discuss augmentation of the photon conversion efficiency by radiation trapping.

  11. Sum-frequency generation of continuous-wave light at 194 nm.

    PubMed

    Berkeland, D J; Cruz, F C; Bergquist, J C

    1997-06-20

    Over 2 mW of continuous-wave tunable 194-nm light is produced by sum-frequency mixing approximately 500 mW of 792-nm and 500 mW of 257-nm radiation in beta-barium borate (BBO). The powers in both fundamental beams are enhanced in separate ring cavities whose optical paths overlap in the Brewster-cut BBO crystal. Due to the higher circulating fundamental powers, the sum-frequency-generated power is nearly 2 orders of magnitude greater than previously reported values.

  12. Compact 498-nm light source based on intracavity sum-frequency Nd:GGG laser

    NASA Astrophysics Data System (ADS)

    Wang, A. G.; Li, Y. L.

    2011-08-01

    We report a coherent cyan radiation at 498 nm by intracavity sum-frequency generation of the 937 and 1062 nm laser-lines of the Nd:GGG crystal. With a diode pump power of 18.2 W, the maximum cyan output power of 186 mW is obtained. The beam quality M2 value is 1.22 in the horizontal plane. The output power stability over 30 min is better than 5%. To the best of our knowledge, this is first work on intracavity sum-frequency generation of a diode pumped Nd:GGG laser at 498 nm.

  13. 810nm, 980nm, 1470nm and 1950nm diode laser comparison: a preliminary "ex vivo" study on oral soft tissues

    NASA Astrophysics Data System (ADS)

    Fornaini, Carlo; Merigo, Elisabetta; Sozzi, Michele; Selleri, Stefano; Vescovi, Paolo; Cucinotta, Annamaria

    2015-02-01

    The introduction of diode lasers in dentistry has several advantages, mainly consisting on the reduced size, reduced cost and possibility to beam delivering by optical fibers. At the moment the two diode wavelengths normally utilized in the dental field are 810 and 980 nm for soft tissues treatments. The aim of this study was to compare the efficacy of four different diode wavelengths: 810, 980, 1470 and 1950 nm diode laser for the ablation of soft tissues. Several samples of veal tongue were exposed to the four different wavelengths, at different fluences. The internal temperature of the soft tissues, in the area close to the beam, was monitored with thermocouple during the experiment. The excision quality of the exposed samples have been characterized by means of an optical microscope. Tissue damages and the cut regularity have been evaluated on the base of established criteria. The lowest thermal increase was recorded for 1950 nm laser. Best quality and speed of incision were obtained by the same wavelength. By evaluating epithelial, stromal and vascular damages for all the used wavelengths, the best result, in terms of "tissue respect", have been obtained for 1470 and 1950 nm exposures. From the obtained results 1470 and 1950 nm diode laser showed to be the best performer wavelengths among these used in this "ex vivo" study, probably due to their greatest affinity to water.

  14. 494 nm blue laser based on sum-frequency mixing of diode pumped Nd3+ lasers

    NASA Astrophysics Data System (ADS)

    Zou, J.; Wang, L. R.

    2012-02-01

    We report for the first time a continuous-wave (CW) blue radiation at 494 nm by intracavity sumfrequency generation of 912 nm Nd:GdVO4 laser and 1079 nm Nd:YAlO3 (Nd:YAP) laser. Using type-I critical phase matching LiB3O5 (LBO) crystal, 494 nm blue laser was obtained by 912 and 1079 nm intra-cavity sum-frequency mixing, and output power of 179 mW was demonstrated. At the output power level of 179 mW, the output power stability is better than 3.5% and laser beam quality M 2 factor is 1.21.

  15. Solid state ultraviolet laser (213 nm) ablation of the cornea and synthetic collagen lenticules.

    PubMed

    Gailitis, R P; Ren, Q S; Thompson, K P; Lin, J T; Waring, G O

    1991-01-01

    We used a Q-switched Nd:YAG laser with non-linear optical crystals to produce the 5th (213 nm) and the 4th (266 nm) harmonic frequencies. Using these two wavelengths, we ablated fresh porcine corneas and type I collagen synthetic epikeratoplasty lenticules. For the 213-nm ablation, radiant exposure was 1.3 J/cm2. The ablation rate was 0.23 micron per pulse for the epikeratoplasty lenticules. We examined all tissues with light microscopy, transmission electron microscopy, and scanning electron microscopy. Histology for the 213-nm ablation showed a clean ablation crater with minimal collagen lamellae disruption and a damage zone less than 1 micron. In comparison, the 266 nm radiation showed more charring at the edges with a damage zone approximately 25 microns deep with disruption of the stromal lamella. Our results show that this solid state UV laser is a potential alternative to the excimer laser for cornea surgery.

  16. Diode laser (980nm) cartilage reshaping

    NASA Astrophysics Data System (ADS)

    El Kharbotly, A.; El Tayeb, T.; Mostafa, Y.; Hesham, I.

    2011-03-01

    Loss of facial or ear cartilage due to trauma or surgery is a major challenge to the otolaryngologists and plastic surgeons as the complicated geometric contours are difficult to be animated. Diode laser (980 nm) has been proven effective in reshaping and maintaining the new geometric shape achieved by laser. This study focused on determining the optimum laser parameters needed for cartilage reshaping with a controlled water cooling system. Harvested animal cartilages were angulated with different degrees and irradiated with different diode laser powers (980nm, 4x8mm spot size). The cartilage specimens were maintained in a deformation angle for two hours after irradiation then released for another two hours. They were serially measured and photographed. High-power Diode laser irradiation with water cooling is a cheep and effective method for reshaping the cartilage needed for reconstruction of difficult situations in otorhinolaryngologic surgery. Key words: cartilage,diode laser (980nm), reshaping.

  17. Resist materials for 157-nm lithography

    NASA Astrophysics Data System (ADS)

    Toriumi, Minoru; Ishikawa, Seiichi; Miyoshi, Seiro; Naito, Takuya; Yamazaki, Tamio; Watanabe, Manabu; Itani, Toshiro

    2001-08-01

    Fluoropolymers are key materials for single layer resists of 157nm lithography. We have been studying fluoropolymers to identify their potential for base resins of 157nm photoresist. Many fluoropolymers showed high optical transparencies, with absorption coefficients of 0.01micrometers -1 to 2micrometers -1 at 157nm, and dry- etching resistance comparable to an ArF resist, and non- swelling solubility in the standard developer. Positive- tone resists were formulated using fluoropolymers that fulfill practical resist requirements. They showed good sensitivities, from 1 mJ/cm(superscript 2 to 10 mJ/cm2, and contrast in the sensitivity curves. They were able to be patterned using a F2 laser microstepper.

  18. Comparative study of Nd:KGW lasers pumped at 808 nm and 877 nm

    NASA Astrophysics Data System (ADS)

    Huang, Ke; Ge, Wen-Qi; Zhao, Tian-Zhuo; He, Jian-Guo; Feng, Chen-Yong; Fan, Zhong-Wei

    2015-10-01

    The laser performance and thermal analysis of Nd:KGW laser continuously pumped by 808 nm and 877 nm are comparatively investigated. Output power of 670 mW and 1587 mW, with nearly TEM00 mode, are achieved respectively at 808 nm pump and 877 nm pump. Meanwhile, a high-power passively Q-switched Nd:KGW/Cr4+:YAG laser pumped at 877 nm is demonstrated. An average output power of 1495 mW is obtained at pump power of 5.22 W while the laser is operating at repetition of 53.17 kHz. We demonstrate that 877 nm diode laser is a more potential pump source for Nd:KGW lasers.

  19. UV RADIATION EFFECTS ON MICROBES AND MICROBIAL PROCESSES

    EPA Science Inventory

    The ultraviolet (UV) region of solar radiation is defined as wavelengths in the range of 200 to 400 nm. In contrast to visible radiation (400 - 800 nm), which has a well-defined role as the energy source for most of the Earth's primary production, the effects of UV radiation on b...

  20. Sub-10 nm carbon nanotube transistor.

    PubMed

    Franklin, Aaron D; Luisier, Mathieu; Han, Shu-Jen; Tulevski, George; Breslin, Chris M; Gignac, Lynne; Lundstrom, Mark S; Haensch, Wilfried

    2012-02-01

    Although carbon nanotube (CNT) transistors have been promoted for years as a replacement for silicon technology, there is limited theoretical work and no experimental reports on how nanotubes will perform at sub-10 nm channel lengths. In this manuscript, we demonstrate the first sub-10 nm CNT transistor, which is shown to outperform the best competing silicon devices with more than four times the diameter-normalized current density (2.41 mA/μm) at a low operating voltage of 0.5 V. The nanotube transistor exhibits an impressively small inverse subthreshold slope of 94 mV/decade-nearly half of the value expected from a previous theoretical study. Numerical simulations show the critical role of the metal-CNT contacts in determining the performance of sub-10 nm channel length transistors, signifying the need for more accurate theoretical modeling of transport between the metal and nanotube. The superior low-voltage performance of the sub-10 nm CNT transistor proves the viability of nanotubes for consideration in future aggressively scaled transistor technologies.

  1. White Sands, Carrizozo Lava Beds, NM

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A truly remarkable view of White Sands and the nearby Carrizozo Lava Beds in southeast NM (33.5N, 106.5W). White Sands, site of the WW II atomic bomb development and testing facility and later post war nuclear weapons testing that can still be seen in the cleared circular patterns on the ground.

  2. Negative-tone 193-nm resists

    NASA Astrophysics Data System (ADS)

    Cho, Sungseo; Vander Heyden, Anthony; Byers, Jeff D.; Willson, C. Grant

    2000-06-01

    A great deal of progress has been made in the design of single layer positive tone resists for 193 nm lithography. Commercial samples of such materials are now available from many vendors. The patterning of certain levels of devices profits from the use of negative tone resists. There have been several reports of work directed toward the design of negative tones resists for 193 nm exposure but, none have performed as well as the positive tone systems. Polymers with alicyclic structures in the backbone have emerged as excellent platforms from which to design positive tone resists for 193 nm exposure. We now report the adaptation of this class of polymers to the design of high performance negative tone 193 nm resists. New systems have been prepared that are based on a polarity switch mechanism for modulation of the dissolution rate. The systems are based on a polar, alicyclic polymer backbone that includes a monomer bearing a glycol pendant group that undergoes the acid catalyzed pinacol rearrangement upon exposure and bake to produce the corresponding less polar ketone. This monomer was copolymerized with maleic anhydride and a norbornene bearing a bis-trifluoromethylcarbinol. The rearrangement of the copolymer was monitored by FT-IR as a function of temperature. The synthesis of the norbornene monomers will be presented together with characterization of copolymers of these monomers with maleic anhydride. The lithographic performance of the new resist system will also be presented.

  3. MEPHISTO spectromicroscope reaches 20 nm lateral resolution

    NASA Astrophysics Data System (ADS)

    De Stasio, Gelsomina; Perfetti, Luca; Gilbert, B.; Fauchoux, O.; Capozi, M.; Perfetti, P.; Margaritondo, G.; Tonner, B. P.

    1999-03-01

    The recently described tests of the synchrotron imaging photoelectron spectromicroscope MEPHISTO (Microscope à Emission de PHotoélectrons par Illumination Synchrotronique de Type Onduleur) were complemented by further resolution improvements and tests, which brought the lateral resolution down to 20 nm. Images and line plot profiles demonstrate such performance.

  4. 1541nm GmAPD LADAR system

    NASA Astrophysics Data System (ADS)

    Kutteruf, Mary R.; Lebow, Paul

    2014-06-01

    The single photon sensitivity of Geiger-mode avalanche photo diodes (GmAPDs) has facilitated the development of LADAR systems that operate at longer stand-off distances, require lower laser pulse powers and are capable of imaging through a partial obscuration. In this paper, we describe a GmAPD LADAR system which operates at the eye-safe wavelength of 1541 nm. The longer wavelength should enhance system covertness and improve haze penetration compared to systems using 1064 nm lasers. The system is comprised of a COTS 1541 nm erbium fiber laser producing 4 ns pulses at 80 kHz to 450 kHz and a COTS camera with a focal plane of 32x32 InGaAs GmAPDs band-gap optimized for 1550 nm. Laboratory characterization methodology and results are discussed. We show that accurate modeling of the system response, allows us to achieve a depth resolution which is limited by the width of the camera's time bin (.25 ns or 1.5 inches) rather than by the duration of the laser pulse (4 ns or 2 ft.). In the presence of obscuration, the depth discrimination is degraded to 6 inches but is still significantly better than that dictated by the laser pulse duration. We conclude with a discussion of future work.

  5. Generation of femtosecond laser pulses tunable from 380 nm to 465 nm via cascaded nonlinear optical mixing in a noncollinear optical parametric amplifier with a type-I phase matched BBO crystal.

    PubMed

    Lee, Chao-Kuei; Zhang, Jing-Yuan; Huang, J; Pan, Ci-Ling

    2003-07-14

    We report the generation of tunable femtosecond pulses from 380nm to 465nm near the degenerate point of a 405-nm pumped type-I BBO noncollinearly phase-matched optical parametric amplifier (NOPA). The tunable UV/blue radiation is obtained from sum frequency generation (SFG) between the OPA output and the residual fundamental beam at 810-nm and cascaded second harmonic generation (SHG) of OPA. With a fixed seeding angle, the generated SFG and SHG covers from 385 nm to 465-nm. With a pumping energy of 75 J at 405 nm, the optical conversion efficiency from the pump to the tunable SFG is more than 5% and the efficiency of SHG of the OPA is about 2%.

  6. VizieR Online Data Catalog: Thorium spectrum from 250nm to 5500nm (Redman+, 2014)

    NASA Astrophysics Data System (ADS)

    Redman, S. L.; Nave, G.; Sansonetti, C. J.

    2014-04-01

    We observed the spectrum of a commercial sealed Th/Ar HCL running at 25mA for almost 15hr starting on 2011 November 2. The region of observation was limited to between 8500/cm and 28000/cm (360nm and 1200nm) by the sensitivity of the silicon photodiode detector. (5 data files).

  7. Total dose responses and reliability issues of 65 nm NMOSFETs

    NASA Astrophysics Data System (ADS)

    Dezhao, Yu; Qiwen, Zheng; Jiangwei, Cui; Hang, Zhou; Xuefeng, Yu; Qi, Guo

    2016-06-01

    In this paper, total dose responses and reliability issues of MOSFETs fabricated by 65 nm CMOS technology were examined. “Radiation-induced narrow channel effect” is observed in a narrow channel device. Similar to total dose responses of NMOSFETs, narrow channel NMOSFEs have larger hot-carrier-induced degradation than wide channel devices. Step Time-Dependent Dielectric Breakdown (TDDB) stresses are applied, and narrow channel devices have higher breakdown voltage than wide channel devices, which agree with “weakest link” theory of TDDB. Experimental results show that linear current, transconductance, saturated drain current and subthreshold swing are superposed degenerated by total dose irradiation and reliability issues, which may result in different lifetime from that considering total dose irradiation reliability issues separately. Project supported by “Light of West China” Program of CAS (No. XBBS201219).

  8. Hexafluoroisopropyl and trifluoromethyl carbinols in an acrylate platform for 157-nm chemically amplified resists

    NASA Astrophysics Data System (ADS)

    Jakubek, Vladimir; Robertson, Eric A., III; Abdourazak, Atteye H.; Markley, Thomas J.; Marsella, John A.; Ober, Christopher K.

    2004-05-01

    Electromagnetic radiation in the vacuum-ultraviolet (VUV) region is needed for imaging of very fine features at the 65 nm and 45 nm nodes. Photolithography using 157-nm radiation, emitted from an F2 excimer laser, is a candidate for next generation lithography. Only chemically amplified resists containing fluorinated hydrocarbons and siloxanes have the required transparency at this wavelength. We have identified hexafluoroisopropanol units as a building block for our 157-nm resist polymers. This paper reports our progress on the most recent research development for this platform. The hexafluoroisopropanol functionality, which has a pKa similar to phenol, has been used to increase the transparency of 157-nm single-layer acrylate-based resists. Our recent effort has been focused on the syntheses of new acrylate monomers with highly transparent building blocks based on trifluoroacetone. The first example, a homopolymer derived from trifluoroacetone bearing a fluorinated hemiacetal unit, has moderate transparency at 157 nm (A = 1.9 μm-1). We have also introduced a new acrylate monomer containing a trimer based on trifluoroacetone, where the 6-hydroxy group in the hemiacetal unit is substituted by a fluorine atom, with an acceptable transparency at 157 nm (A = 2.1 μm-1). Copolymers of the former monomer, derived from trifluoroacetone, and tert-butyl α-fluoroacrylate have also been prepared and showed good 248-nm lithographic performance suggesting suitability for 157-nm lithography. This paper will discuss the transparency, etch resistance and chemical properties of several fluorinated acrylate-based resists, synthesized from groups containing pendent hexafluoroisopropanol units and trimers derived from trifluoroacetone.

  9. 120 nm resolution and 55 nm structure size in STED-lithography.

    PubMed

    Wollhofen, Richard; Katzmann, Julia; Hrelescu, Calin; Jacak, Jaroslaw; Klar, Thomas A

    2013-05-01

    Two-photon direct laser writing (DLW) lithography is limited in the achievable structure size as well as in structure resolution. Adding stimulated emission depletion (STED) to DLW allowed overcoming both restrictions. We now push both to new limits. Using visible light for two-photon DLW (780 nm) and STED (532 nm), we obtain lateral structure sizes of 55 nm, a Sparrow limit of around 100 nm and we present two clearly separated lines spaced only 120 nm apart. The photo-resist used in these experiments is a mixture of tri- and tetra-acrylates and 7-Diethylamino-3-thenoylcoumarin as a photo-starter which can be readily quenched via STED.

  10. Photoresist outgassing at 157 nm exposure

    NASA Astrophysics Data System (ADS)

    Hien, Stefan; Angood, Steve; Ashworth, Dominic; Basset, Steve; Bloomstein, Theodore M.; Dean, Kim R.; Kunz, Roderick R.; Miller, Daniel A.; Patel, Shashikant; Rich, Georgia K.

    2001-08-01

    Contamination of optical elements during photoresist exposure is a serious issue in optical lithography. The outgassing of photoresist has been identified as a problem at 248nm and 193nm in production because the organic films that can be formed on an exposure lens can cause transmission loss and sever image distortion. At these exposure energies, the excitation of the photo acid generator, formation of acid, and cleavage of the protecting group are highly selective processes. At 157nm, the exposure energy is much higher (7.9 eV compared to 6.4 eV at 193nm) and it is known from laser ablation experiments that direct laser cleavage of sigma bonds occurs. The fragments formed during this irradiation can be considered as effective laser deposition precursors even in the mid ppb level. In this study, methods to quantify photoresist outgassing at 157 nm are discussed. Three criteria have been set up at International SEMATECH to protect lens contamination and to determine the severity of photoresist outgassing. First, we measured film thickness loss as a function of exposure dose for a variety of materials. In a second test we studied the molecular composition of the outgassing fragments with an exposure chamber coupled to a gas chromatograph and a mass spectrometer detector. Our third method was a deposition test of outgassing vapors on a CaF2 proof plate followed by analysis using VUV and X-ray photoelectron spectroscopies (XPS). With this technique we found deposits for many different resists. Our main focus is on F- and Si- containing resists. Both material classes form deposits especially if these atoms are bound to the polymer side chains. Whereas the F-containing films can be cleaned off under 157nm irradiation, cleaning of Si-containing films mainly produces SiO2. Our cleaning studies of plasma deposited F-containing organic films on SiO2 did not indicate damage of this surface by the possible formation of HF. Despite that we strongly recommend engineering

  11. Generation of third harmonic picosecond pulses at 355 nm by sum frequency mixing in periodically poled MgSLT crystal

    NASA Astrophysics Data System (ADS)

    Kaltenbach, André; Schönau, Thomas; Lauritsen, Kristian; Tränkle, Günther; Erdmann, Rainer

    2015-02-01

    Third harmonic 355nm picosecond pulses are generated by sum frequency mixing in a periodically poled magnesium doped stoichiometric lithium tantalate (PPMgSLT) crystal. The third harmonic generation is based on the 1064nm radiation of a gain-switched distributed feedback (DFB) diode laser which is amplified by a two-stage fiber amplifier. The diode laser is freely triggerable at variable repetition rates up to 80MHz and provides optical pulses of 65 ps FWHM duration and pulse energies in the range of 5 pJ. The 355nm third harmonic generation is realized in a two-step conversion process. First, the 1064nm fundamental radiation is frequency-doubled to 532 nm, afterwards both frequencies are mixed in the PPMgSLT crystal to 355 nm. The UV-radiation shows a pulse width of 60 ps, a good beam profile and stable pulse energy over a wide range of repetition rates by proprietary pump power management. At 355nm a pulse peak power of 5.3W was achieved with 192W pulse peak power of the fundamental radiation.

  12. Infrared Radiative Properties of Food Materials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Precisely, infrared radiation is electromagnetic radiation whose wavelength is longer than that of visible light, but shorter than that of terahertz radiation and microwaves. The infrared portion of the electromagnetic spectrum spans roughly three orders of magnitude (750 nm to 100 µm) and has been...

  13. 1125-nm quantum dot laser for tonsil thermal therapy

    NASA Astrophysics Data System (ADS)

    McMillan, Kathleen

    2011-03-01

    Thermal therapy has the potential to provide a nonexcisional alternative to tonsillectomy. Clinical implementation requires that the lymphoid tissue of tonsils is heated homogeneously to produce an amount of primary thermal injury that corresponds to gradual postoperative tonsil shrinkage, with minimal risk of damage to underlying critical blood vessels. Optical constants are derived for tonsils from tissue components and used to calculate the depth of 1/e of irradiance. The 1125 nm wavelength is shown to correspond to both deep penetration and minimal absorption by blood. A probe for tonsil thermal therapy that comprises two opposing light emitting, temperature controlled surfaces is described. For ex vivo characterization of tonsil heating, a prototype 1125 nm diode laser is used in an experimental apparatus that splits the laser output into two components, and delivers the radiation to sapphire contact window surfaces of two temperature controlled cells arranged to irradiate human tonsil specimens from opposing directions. Temperatures are measured with thermocouple microprobes at located points within the tissue during and after irradiation. Primary thermal damage corresponding to the recorded thermal histories are calculated from Arrhenius parameters for human tonsils. Results indicate homogeneous heating to temperatures corresponding to the threshold of thermal injury and above can be achieved in advantageously short irradiation times.

  14. Depth of penetration of an 850nm wavelength low level laser in human skin.

    PubMed

    Esnouf, Alan; Wright, Philip A; Moore, Joan C; Ahmed, Salim

    2007-01-01

    Low Level Laser Therapy is used for a wide variety of conditions including superficial skin sores, musculoskeletal and joint problems, and dentistry. Knowledge of the penetration depth of laser radiation in human skin is an essential prerequisite to identifying its method of action. Mathematical simulations and estimates from the literature suggest that the depth of penetration of laser radiation using wavelengths from 630nm up to 1100nm may be up to 50mm. The aim of this study is to directly measure the penetration depth of a Low Level Laser in human tissue. Human abdominal skin samples up to 0.784mm thickness were harvested by dermatome following abdominoplasty procedures. These samples were irradiated by a Gallium Aluminium Arsenide Laser (Wavelength 850nm near infra-red invisible light, 100mW, 24kHz, 0.28mm diameter probe) and the transmitted radiation measured with an Ophir Optronics 'Nova' external energy meter. The intensity of laser radiation reduced by 66% after being transmitted through a 0.784mm sample of human abdominal tissue. In this study most laser radiation was absorbed within the first 1mm of skin.

  15. Laser damage database at 1064 nm

    SciTech Connect

    Rainer, F.; Gonzales, R.P.; Morgan, A.J.

    1990-03-01

    In conjunction with our diversification of laser damage testing capabilities, we have expanded upon a database of threshold measurements and parameter variations at 1064 nm. This includes all tests at low pulse-repetition frequencies (PRF) ranging from single shots to 120 Hz. These tests were conducted on the Reptile laser facility since 1987 and the Variable Pulse Laser (VPL) facility since 1988. Pulse durations ranged from 1 to 16 ns. 10 refs., 14 figs.

  16. High power terahertz generation using 1550 nm plasmonic photomixers

    SciTech Connect

    Berry, Christopher W.; Hashemi, Mohammad R.; Jarrahi, Mona; Preu, Sascha; Lu, Hong; Gossard, Arthur C.

    2014-07-07

    We present a 1550 nm plasmonic photomixer operating under pumping duty cycles below 10%, which offers significantly higher terahertz radiation power levels compared to previously demonstrated photomixers. The record-high terahertz radiation powers are enabled by enhancing the device quantum efficiency through use of plasmonic contact electrodes, and by mitigating thermal breakdown at high optical pump power levels through use of a low duty cycle optical pump. The repetition rate of the optical pump can be specifically selected at a given pump duty cycle to control the spectral linewidth of the generated terahertz radiation. At an average optical pump power of 150 mW with a pump modulation frequency of 1 MHz and pump duty cycle of 2%, we demonstrate up to 0.8 mW radiation power at 1 THz, within each continuous wave radiation cycle.

  17. Radiation enteritis

    MedlinePlus

    Radiation enteropathy; Radiation-induced small bowel injury; Post-radiation enteritis ... Radiation therapy uses high-powered x-rays, particles, or radioactive seeds to kill cancer cells. The therapy ...

  18. Mode-locked Nd:YAG laser with output at 1052, 1061, 1064, and 1074 nm

    SciTech Connect

    Badalian, A.A.; Sapondzhian, S.O.; Sarkisian, D.G.; Torosian, G.A.

    1985-10-01

    The picosecond Nd:YAG laser with an output radiation at 1064 nm is currently widely used. However, in connection with many applications, picosecond pulses at other wavelengths are also needed. The present study is, therefore, concerned with the development of a picosecond laser which provides pulses at 1052, 1061.5, and 1073.7 nm. Lasing at 1052, 1061.5, 1064, and 1073.7 nm was achieved by varying the angle between the resonator axis and the normal to the etalon by four degrees. Attention is given to the measurement of the lengths of the ultrashort pulses, and the transverse distribution of the energy in the second harmonic for the wavelength 1052 nm. The discretely tunable picosecond Nd:YAG laser described appears to be a promising tool for many research applications. 9 references.

  19. Quantitative photoabsorption and fluorescence spectroscopy of benzene, naphthalene, and some derivatives at 106-295 nm

    NASA Technical Reports Server (NTRS)

    Suto, Masako; Wang, Xiuyan; Shan, Jun; Lee, L. C.

    1992-01-01

    Photoabsorption and fluorescence cross sections of benzene, (o-, m-, p-) xylenes, naphthalene, 1-methylnaphthalene, and 2-ethylnaphthalene in the gas phase are measured at 106-295 nm using synchrotron radiation as a light source. Fluorescences are observed from the photoexcitation of benzene and xylenes at 230-280 nm and from naphthalene and its derivatives at 190-295 nm. The absolute fluorescence cross section is determined by calibration with respect to the emission intensity of the NO(A-X) system, for which the fluorescence quantum yield is equal to 1. To cross-check the current calibration method, the quantum yield of the SO2(C-X) system at 220-230 nm was measured since it is about equal to 1. The current quantum-yield data are compared with previously published values measured by different methods.

  20. Patterning polymeric structures with 2 nm resolution at 3 nm half pitch in ambient conditions.

    PubMed

    Martínez, R V; Losilla, N S; Martinez, J; Huttel, Y; Garcia, R

    2007-07-01

    The miniaturization limits of electronic and mechanical devices depend on the minimum pattern periodicity that is stable in ambient conditions. Here we demonstrate an atomic force microscopy lithography that enables the patterning of 2 nm organic structures with 6 nm periodicities in air. We also demonstrate that the lithography can be up-scaled for parallel patterning. The method is based on the formation of a nanoscale octane meniscus between a sharp conductive protrusion and a silicon (100) surface. The application of a high electrical field ( approximately 10 V/nm) produces the polymerization and cross-linking of the octane molecules within the meniscus followed by their deposition. The resulting pattern periodicities are very close to the ultimate theoretical limits achievable in air ( approximately 3 nm). The chemical composition of the patterns has been characterized by photoemission spectroscopy.

  1. 981 nm Yb:KYW laser intracavity pumped at 912 nm and frequency-doubling for an emission at 490.5 nm

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Zhang, X. H.; Xia, J.; Chen, R.; Jin, G. Y.; Wang, J. G.; Li, C. L.; Ma, Z. Y.

    2010-05-01

    We present an Yb:KY(WO4)2 (Yb:KYW) laser emitting at 981 nm intracavity pumped by a 912 nm diode-pumped Nd:GdVO4 laser. A 808 nm diode laser is used to pump the Nd:GdVO4 crystal emitting at 912 nm, and the Yb:KYW laser emitting at 981 nm intracavity pumped at 912 nm. This configuration enabled us to indirectly diode-pump this ytterbium doped crystal, and to obtain 1.12 W output power at 981 nm for 19.6 W of incident pump power at 808 nm. Furthermore, intracavity second harmonic generation has also been demonstrated with a power of 106 mW at 490.5 nm by using a LBO nonlinear crystal.

  2. Deep ultraviolet (254 nm) focal plane array

    NASA Astrophysics Data System (ADS)

    Cicek, Erdem; Vashaei, Zahra; McClintock, Ryan; Razeghi, Manijeh

    2011-10-01

    We report the synthesis, fabrication and testing of a 320 × 256 focal plane array (FPA) of back-illuminated, solarblind, p-i-n, AlxGa1-xN-based detectors, fully realized within our research laboratory. We implemented a novel pulsed atomic layer deposition technique for the metalorganic chemical vapor deposition (MOCVD) growth of crackfree, thick, and high Al composition AlxGa1-xN layers. Following the growth, the wafer was processed into a 320 × 256 array of 25 μm × 25 μm pixels on a 30 μm pixel-pitch and surrounding mini-arrays. A diagnostic mini-array was hybridized to a silicon fan-out chip to allow the study of electrical and optical characteristics of discrete pixels of the FPA. At a reverse bias of 1 V, an average photodetector exhibited a low dark current density of 1.12×10-8 A/cm2. Solar-blind operation is observed throughout the array with peak detection occurring at wavelengths of 256 nm and lower and falling off three orders of magnitude by 285 nm. After indium bump deposition and dicing, the FPA is hybridized to a matching ISC 9809 readout integrated circuit (ROIC). By developing a novel masking technology, we significantly reduced the visible response of the ROIC and thus the need for external filtering to achieve solar- and visible-blind operation is eliminated. This allowed the FPA to achieve high external quantum efficiency (EQE): at 254 nm, average pixels showed unbiased peak responsivity of 75 mA/W, which corresponds to an EQE of ~37%. Finally, the uniformity of the FPA and imaging properties are investigated.

  3. Quantitative comparison of the OCT imaging depth at 1300 nm and 1600 nm

    PubMed Central

    Kodach, V. M.; Kalkman, J.; Faber, D. J.; van Leeuwen, T. G.

    2010-01-01

    One of the present challenges in optical coherence tomography (OCT) is the visualization of deeper structural morphology in biological tissues. Owing to a reduced scattering, a larger imaging depth can be achieved by using longer wavelengths. In this work, we analyze the OCT imaging depth at wavelengths around 1300 nm and 1600 nm by comparing the scattering coefficient and OCT imaging depth for a range of Intralipid concentrations at constant water content. We observe an enhanced OCT imaging depth for 1600 nm compared to 1300 nm for Intralipid concentrations larger than 4 vol.%. For higher Intralipid concentrations, the imaging depth enhancement reaches 30%. The ratio of scattering coefficients at the two wavelengths is constant over a large range of scattering coefficients and corresponds to a scattering power of 2.8 ± 0.1. Based on our results we expect for biological tissues an increase of the OCT imaging depth at 1600 nm compared to 1300 nm for samples with high scattering power and low water content. PMID:21258456

  4. Photolysis of formic acid at 355 nm

    NASA Astrophysics Data System (ADS)

    Martinez, Denhi; Bautista, Teonanacatl; Guerrero, Alfonso; Alvarez, Ignacio; Cisneros, Carmen

    2015-05-01

    Formic acid is well known as a food additive and recently an application on fuel cell technology has emerged. In this work we have studied the dissociative ionization process by multiphoton absorption of formic acid molecules at 355nm wavelength photons, using TOF spectrometry in reflectron mode (R-TOF). Some of the most abundant ionic fragments produced are studied at different settings of the laser harmonic generator. The dependence of the products on these conditions is reported. This work was supported by CONACYT Project 165410 and PAPIIT IN102613 and IN101215.

  5. 248nm silicon photoablation: Microstructuring basics

    SciTech Connect

    Poopalan, P.; Najamudin, S. H.; Wahab, Y.; Mazalan, M.

    2015-05-15

    248nm pulses from a KrF excimer laser was used to ablate a Si wafer in order to ascertain the laser pulse and energy effects for use as a microstructuring tool for MEMS fabrication. The laser pulses were varied between two different energy levels of 8mJ and 4mJ while the number of pulses for ablation was varied. The corresponding ablated depths were found to range between 11 µm and 49 µm, depending on the demagnified beam fluence.

  6. Metastasis suppressor NM23-H1 promotes repair of UV-induced DNA damage and suppresses UV-induced melanomagenesis.

    PubMed

    Jarrett, Stuart G; Novak, Marian; Dabernat, Sandrine; Daniel, Jean-Yves; Mellon, Isabel; Zhang, Qingbei; Harris, Nathan; Ciesielski, Michael J; Fenstermaker, Robert A; Kovacic, Diane; Slominski, Andrzej; Kaetzel, David M

    2012-01-01

    Reduced expression of the metastasis suppressor NM23-H1 is associated with aggressive forms of multiple cancers. Here, we establish that NM23-H1 (termed H1 isoform in human, M1 in mouse) and two of its attendant enzymatic activities, the 3'-5' exonuclease and nucleoside diphosphate kinase, are novel participants in the cellular response to UV radiation (UVR)-induced DNA damage. NM23-H1 deficiency compromised the kinetics of repair for total DNA polymerase-blocking lesions and nucleotide excision repair of (6-4) photoproducts in vitro. Kinase activity of NM23-H1 was critical for rapid repair of both polychromatic UVB/UVA-induced (290-400 nm) and UVC-induced (254 nm) DNA damage, whereas its 3'-5' exonuclease activity was dominant in the suppression of UVR-induced mutagenesis. Consistent with its role in DNA repair, NM23-H1 rapidly translocated to sites of UVR-induced (6-4) photoproduct DNA damage in the nucleus. In addition, transgenic mice hemizygous-null for nm23-m1 and nm23-m2 exhibited UVR-induced melanoma and follicular infundibular cyst formation, and tumor-associated melanocytes displayed invasion into adjacent dermis, consistent with loss of invasion-suppressing activity of NM23 in vivo. Taken together, our data show a critical role for NM23 isoforms in limiting mutagenesis and suppressing UVR-induced melanomagenesis.

  7. Electrically-pumped 850-nm micromirror VECSELs.

    SciTech Connect

    Geib, Kent Martin; Peake, Gregory Merwin; Serkland, Darwin Keith; Keeler, Gordon Arthur; Mar, Alan

    2005-02-01

    Vertical-external-cavity surface-emitting lasers (VECSELs) combine high optical power and good beam quality in a device with surface-normal output. In this paper, we describe the design and operating characteristics of an electrically-pumped VECSEL that employs a wafer-scale fabrication process and operates at 850 nm. A curved micromirror output coupler is heterogeneously integrated with AlGaAs-based semiconductor material to form a compact and robust device. The structure relies on flip-chip bonding the processed epitaxial material to an aluminum nitride mount; this heatsink both dissipates thermal energy and permits high frequency modulation using coplanar traces that lead to the VECSEL mesa. Backside emission is employed, and laser operation at 850 nm is made possible by removing the entire GaAs substrate through selective wet etching. While substrate removal eliminates absorptive losses, it simultaneously compromises laser performance by increasing series resistance and degrading the spatial uniformity of current injection. Several aspects of the VECSEL design help to mitigate these issues, including the use of a novel current-spreading n type distributed Bragg reflector (DBR). Additionally, VECSEL performance is improved through the use of a p-type DBR that is modified for low thermal resistance.

  8. DNA charge transport over 34 nm

    NASA Astrophysics Data System (ADS)

    Slinker, Jason D.; Muren, Natalie B.; Renfrew, Sara E.; Barton, Jacqueline K.

    2011-03-01

    Molecular wires show promise in nanoscale electronics, but the synthesis of uniform, long conductive molecules is a significant challenge. Deoxyribonucleic acid (DNA) of precise length, by contrast, is synthesized easily, but its conductivity over the distances required for nanoscale devices has not been explored. Here we demonstrate DNA charge transport (CT) over 34 nm in 100-mer monolayers on gold. Multiplexed gold electrodes modified with 100-mer DNA yield sizable electrochemical signals from a distal, covalent Nile Blue redox probe. Significant signal attenuation upon incorporation of a single base-pair mismatch demonstrates that CT is DNA-mediated. Efficient cleavage of these 100-mers by a restriction enzyme indicates that the DNA adopts a native conformation accessible to protein binding. Similar electron-transfer rates measured through 100-mer and 17-mer monolayers are consistent with rate-limiting electron tunnelling through the saturated carbon linker. This DNA-mediated CT distance of 34 nm surpasses that of most reports of molecular wires.

  9. Photodissociation of Methyl Iodide at 193 NM

    NASA Astrophysics Data System (ADS)

    Xu, Hong; Pratt, Stephen

    2014-05-01

    A new measurement of the photodissociation of CH3I at 193 nm is reported in which we use a combination of vacuum ultraviolet photoionization and velocity map ion imaging. The iodine photofragments are probed by single-photon ionization at photon energies above and below the photoionization threshold of I(2P3/2) . The relative I(2P3/2) and I*(2P1/2) photoionization cross sections are determined at these wavelengths by using the known branching fractions for the photodissociation at 266 nm. Velocity map ion images indicate that the branching fraction for I(2P3/2) atoms is non-zero, and yield a value of 0.07 +/- 0.01. Interestingly, the translational energy distribution extracted from the image shows that the translational energy of the I(2P3/2) fragments is significantly smaller than that of the I*(2P1/2) atoms. This observation indicates the internal rotational/vibrational energy of the CH3 co-fragment is very high in the I(2P3/2) channel. The results can be interpreted in a manner consistent with the previous measurements, and provide a more complete picture of the dissociation dynamics of this prototypical molecule. This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences under contract No. DE-AC02-06CH11357.

  10. [Carbonization in endovasal laser obliteration by radial light guide with wavelength of 1470 and 970 nm].

    PubMed

    Shaidakov, E V; Ilyukhin, E A; Grigoryan, A G; Bulatov, V L; Rosukhovsky, D A; Shonov, O A

    2015-01-01

    The authors assessed the effect of carbonization and its influence on the parameters of endovasal laser obliteration (EVLO) depending on wavelength of laser radiation (970 and 1470 nm) using a light guide with radial emission. They also analysed the value of drop of radiation power of the light guide after performing EVLO and visually assessed the degree of damage of the glass tip of the radial fibre by means of ultra-close-up photography. The study comprised a total of 20 patients with varicose disease. A total of ten procedures of EVLO were performed in two modes: mode one - W-laser 1470 nm, mode two - H-laser 970 nm, using fibre with radial emission, an automatic retractor of the light guide. It was determined that the median of power loss after EVLO with W-laser amounted to 0.6 W, and that for H-laser - 3.15 W (p=0.002). Ultra-close-up photography showed pronounced damage of the glass tip of the radial light guide while using H-laser and no damages while using the W-laser. It was proved that using laser radiation with wavelength of 970 nm using the light guide with radial emission leads to pronounced carbonization on the surface of the glass tip of the light guide, its damage, a decrease in radiation power and risk of mechanical destruction of the flask. Using the laser with wavelength of 1470 nm with the use of radial light guide did not result in the development of such negative effects, which increases the service life of laser fibre and makes it possible to use it for obliteration of several segments in one patient. PMID:26355929

  11. Diode-pumped quasi-three-level Nd:GdV O4-Nd:YAG sum-frequency laser at 464 nm

    NASA Astrophysics Data System (ADS)

    Lu, Jie

    2014-04-01

    We report a laser architecture to obtain continuous-wave (cw) blue radiation at 464 nm. A 808 nm diode pumped a Nd:GdV O4 crystal emitting at 912 nm. A part of the pump power was then absorbed by the Nd:GdV O4 crystal. The remainder was used to pump a Nd:YAG crystal emitting at 946 nm. Intracavity sum-frequency mixing at 912 and 946 nm was then realized in a LiB3O5 (LBO) crystal to produce blue radiation. We obtained a cw output power of 1.52 W at 464 nm with a pump laser diode emitting 18.4 W at 808 nm.

  12. Ultraviolet-induced photodegradation of cucumber (Cucumis sativus L. ) microsomal and soluble protein tryptophanyl residues in vitro

    SciTech Connect

    Caldwell, C.R. )

    1993-03-01

    The in vitro effects of ultraviolet B (280--320 nm) radiation on microsomal membrane proteins and partially purified ribulose bisphosphate carboxylase (Rubisco) from cucumber (Cucumis sativus L.) was investigated by measuring the direct photolytic reduction of tryptophan fluorescence and the formation of fluorescent photooxidation products. Exposure of microsomes and Rubisco to monochromatic 300-nm radiation resulted in the loss of intrinsic tryptophan fluorescence and the production of blue-emitting fluorophores. The major product of tryptophan photolysis was tentatively identified as N-formylkynurenine (N-FK). Even though the rates of tryptophan photodegradation and N-FK formation were similar, the amount of blue fluorescence produced was significantly higher in the microsomes relative to Rubisco. Studies with various free radical scavengers and other modifiers indicated that tryptophan photodegradation requires oxygen species. The optimum wavelengths for loss of tryptophan fluorescence were 290 nm for the microsomes and 280 nm for Rubisco. The temperature dependence of tryptophan fluorescence and rate of tryptophan photodegradation indicated an alteration in the cucumber microsomal membranes at about 24[degrees]C, which influenced protein structure and tryptophan photosensitivity. 29 refs., 6 figs., 1 tab.

  13. Comparison of 980-nm and 1070-nm in endovenous laser treatment (EVLT)

    NASA Astrophysics Data System (ADS)

    Topaloglu, Nermin; Tabakoglu, Ozgur; Ergenoglu, Mehmet U.; Gülsoy, Murat

    2009-07-01

    The use of endovenous laser treatment for varicose veins has been increasing in recent years. It is a safer technique than surgical vein stripping. Its complications (e.g. bruising, pain) are less than the complications of surgical vein stripping. But best parameters such as optimum wavelength, power, and application duration are still under investigation to clarify uncertainties about this technique. To prevent its complications and improve its clinical outcomes, the exact mechanism of it has to be known. The aim of this study is to investigate the effect of different laser wavelengths on endovenous laser therapy. In this study 980-nm diode laser and 1070-nm fiber laser were used. Human veins were irradiated with 980-nm and 1070-nm lasers at 8 W and 10 W to find the optimal power and wavelength. After laser application, remarkable shrinkage was observed. Inner and outer diameters of the veins also narrowed for both of the laser types. 10 W of 980-nm laser application led to better shrinkage results.

  14. Dual illumination OCT at 1050nm and 840nm for whole eye segment imaging

    NASA Astrophysics Data System (ADS)

    Fan, Shanhui; Qin, Lin; Dai, Cuixia; Zhou, Chuanqing

    2014-11-01

    We presented an improved dual channel dual focus spectral domain optical coherence tomography (SD-OCT) with two illuminations at 840 nm and 1050 nm for whole eye segment imaging and biometry in vivo. The two light beams were coupled and optically optimized to scan the anterior and posterior segment of the eye simultaneously. This configuration with dichroic mirrors integrated in the sample arm enables us to acquire images from the anterior segment and retina effectively with minimum loss of sample signal. In addition, the full resolved complex (FRC) method was applied to double the imaging depth for the whole anterior segment imaging by eliminating the mirror image. The axial resolution for 1050 nm and 840 nm OCT was 14 μm and 8 μm in air, respectively. Finally, the system was successfully tested in imaging the unaccommodated and accommodated eyes. The preliminary results demonstrated the significant improvements comparing with our previous dual channel SD-OCT configuration in which the two probing beams had the same central wavelength of 840 nm.

  15. TCSPC FLIM in the wavelength range from 800 nm to 1700 nm (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Becker, Wolfgang; Shcheslavsky, Vladislav

    2016-03-01

    Excitation and detection in the wavelength range above 800nm is a convenient and relatively inexpensive way to increase the penetration depth in optical microscopy. Moreover, detection at long wavelength avoids the problem that tissue autofluorescence contaminates the signals from endogenous fluorescence probes. FLIM at NIR wavelength may therefore be complementary to multiphoton microscopy, especially if the lifetimes of NIR fluorophores report biological parameters of the tissue structures they are bound to. Unfortunately, neither the excitation sources nor the detectors of standard confocal and multiphoton laser scanning systems are directly suitable for excitation and detection of NIR fluorescence. Most of these problems can be solved, however, by using ps diode lasers or Ti:Sapphire lasers at their fundamental wavelength, and NIR-sensitive detectors. With NIR-sensitive PMTs the detection wavelength range can be extended up to 900 nm, with InGaAs SPAD detectors up to 1700 nm. Here, we demonstrate the use of a combination of laser scanning, multi-dimensional TCSPC, and advanced excitation sources and detectors for FLIM at up to 1700 nm. The performance was tested at tissue samples incubated with NIR dyes. The fluorescence lifetimes generally get shorter with increasing absorption and emission wavelengths of the dyes. For the cyanine dye IR1061, absorbing around 1060 nm, the lifetime was found to be as short as 70 ps. Nevertheless the fluorescence decay could still be clearly detected. Almost all dyes showed clear lifetime changes depending on the binding to different tissue constituents.

  16. Design and implementation of a vacuum compatible laser-basedsub-nm resolution absolute distance measurement gauge

    SciTech Connect

    Naulleau, Patrick P.; Denham, Paul E.; Rekawa, Senajith

    2004-02-16

    We describe the design and implementation of a vacuum compatible laser-based absolute distance measurement gauge with sub-nm resolution. The present system is compatible with operation in the 10{sup -8} Torr range and with some minor modifications could be used in the 10{sup -9} Torr range. The system is based on glancing incidence reflection and dual segmented diode detection. The system has been implemented as a focus sensor for extreme ultraviolet interferometry and microlithography experiments at Lawrence Berkeley National Laboratory's Advanced Light Source synchrotron radiation facility and 1{sigma} operational measurement noise floor of 0.26 nm has been demonstrated.

  17. 11 W single gain-chip dilute nitride disk laser emitting around 1180 nm.

    PubMed

    Korpijärvi, Ville-Markus; Leinonen, Tomi; Puustinen, Janne; Härkönen, Antti; Guina, Mircea D

    2010-12-01

    We report power scaling experiments of a GaInNAs/GaAs-based semiconductor disk laser operating at ~1180 nm. Using a single gain chip cooled to mount temperature of ~10 °C we obtained 11 W of output power. For efficient thermal management we used a water-cooled microchannel mount and an intracavity diamond heat spreader. Laser performance was studied using different spot sizes of the pump beam on the gain chip and different output couplers. Intracavity frequency-doubling experiments led to generation of ~6.2 W of laser radiation at ~590 nm, a wavelength relevant for the development of sodium laser guide stars.

  18. Absorption coefficients for water vapor at 193 nm from 300 to 1073 K

    NASA Technical Reports Server (NTRS)

    Kessler, W. J.; Carleton, K. L.; Marinelli, W. J.

    1993-01-01

    Measurements of the water absorption coefficient at 193 nm from 300 to 1073 K are reported. The measurements were made using broadband VUV radiation and a monochromator-based detection system. The water vapor was generated by a saturator and metered into a flowing, 99 cm absorption cell via a water vapor mass flow meter. The 193 nm absorption coefficient measurements are compared to room temperature and high temperature shock tube measurements with good agreement. The absorption can be parameterized by a nu3 vibrational mode reaction coordinate and the thermal population of the nu3 mode.

  19. Two-photon-excited fluorescence spectroscopy of atomic fluorine at 170 nm

    NASA Technical Reports Server (NTRS)

    Herring, G. C.; Dyer, Mark J.; Jusinski, Leonard E.; Bischel, William K.

    1988-01-01

    Two-photon-excited fluorescence spectroscopy of atomic fluorine is reported. A doubled dye laser at 286-nm is Raman shifted in H2 to 170 nm (sixth anti-Stokes order) to excite ground-state 2P(0)J fluorine atoms to the 2D(0)J level. The fluorine atoms are detected by one of two methods: observing the fluorescence decay to the 2PJ level or observing F(+) production through the absorption of an additional photon by the excited atoms. Relative two-photon absorption cross sections to and the radiative lifetimes of the 2D(0)J states are measured.

  20. 308-nm excimer laser in endodontics

    NASA Astrophysics Data System (ADS)

    Liesenhoff, Tim

    1992-06-01

    Root canal preparation was performed on 20 extracted human teeth. After opening the coronal pulp, the root canals were prepared by 308 nm excimer laser only. All root canals were investigated under SEM after separation in the axial direction. By sagittal separation of the mandibles of freshly slaughtered cows, it was possible to get access to the tissues and irradiate under optical control. Under irradiation of excimer laser light, tissue starts to fluoresce. It was possible to demonstrate that each tissue (dentin, enamel, bone, pulpal, and connective tissue) has a characteristic spectral pattern. The SEM analyses showed that it is well possible to prepare root canals safely. All organic soft tissue has been removed by excimer laser irradiation. There was no case of via falsa. The simultaneous spectroscopic identification of the irradiated tissue provides a safe protection from overinstrumentation. First clinical trials on 20 patients suffering of chronical apical parodontitis have been carried out successfully.

  1. 1064-nm Nd:YAG laser nucleotomy

    NASA Astrophysics Data System (ADS)

    Vari, Sandor G.; Pergadia, Vani R.; Shi, Wei-Qiang; Snyder, Wendy J.; Fishbein, Michael C.; Grundfest, Warren S.

    1993-07-01

    The high incidence of patients with clinical and neurological symptoms of lumbar disc herniation has spurred the development of less invasive and more cost efficient methods to treat patients. In this study we evaluated pulsed and continuous wave (cw) 1064 nm Nd:YAG laser ablation and induced thermal damage in sheep intervertebral disc. We used the Heraeus LaserSonics Hercules 5040 (Nd:YAG) laser system and 400 micrometers bare and 600 micrometers ball-tipped fibers in cw and pulsed mode. For the laser parameters and fibers used in this study, ablation of the intervertebral disc was successful and thermal damage did not exceed 0.5 mm. Varying beam diameters and focusing abilities (i.e., bare and ball) did not produce any difference in the coagulation thermal effect.

  2. Optical properties of root canal irrigants in the 300-3,000-nm wavelength region.

    PubMed

    Meire, Maarten A; Poelman, Dirk; De Moor, Roeland J

    2014-09-01

    In root canal therapy, irrigating solutions are essential to assist in debridement and disinfection. Their spread and action is often restricted by canal anatomy, requiring some form of activation. Lasers have been shown to be promising tools for this purpose (laser-activated irrigation (LAI)). For LAI to be effective, high absorption of radiation in the irrigant is essential. Although the absorption spectrum of water is well established, little is known about the optical properties of other irrigating solutions. Therefore, root canal irrigants (sodium hypochlorite (NaOCl), citric acid (CA), chlorhexidine (CHX), ethylenediaminetetraacetate (EDTA), water) were subjected to UV/Vis spectrophotometry in the 300-3,000-nm region using synthetic quartz cells with an optical path length of 1 mm. Transmission data were used to plot the transmission spectrum and calculate the absorption coefficient (α) of each irrigant. The transmission spectra of the tested solutions proved to follow the spectrum of pure water to a large extent. All tested solutions displayed absorption peaks around 1,450 nm (α ≈ 14 cm(-1)), 1,950 nm (α > 30 cm(-1)), and above 2,500 nm (α > 30 cm(-1)). NaOCl showed higher absorption than water in the UV region. Slightly higher absorption than water was noted for CHX (Corsodyl) around 513 nm and for CA between 1,600 and 1,800 nm and around 2,200 nm. The absorption in all tested solutions for wavelengths greater than 2,500 nm is very high, meaning a great potential for laser-activated irrigation. Other wavelengths eligible for LAI are located around 1,450 and 2,000 nm but require further investigation.

  3. Measurements of Soot Mass Absorption Coefficients from 300 to 660 nm

    NASA Astrophysics Data System (ADS)

    Renbaum-Wolff, Lindsay; Fisher, Al; Helgestad, Taylor; Lambe, Andrew; Sedlacek, Arthur; Smith, Geoffrey; Cappa, Christopher; Davidovits, Paul; Onasch, Timothy; Freedman, Andrew

    2016-04-01

    Soot, a product of incomplete combustion, plays an important role in the earth's climate system through the absorption and scattering of solar radiation. In particular, the assumed mass absorption coefficient (MAC) of soot and its variation with wavelength presents a significant uncertainty in the calculation of radiative forcing in global climate change models. As part of the fourth Boston College/Aerodyne soot properties measurement campaign, we have measured the mass absorption coefficient of soot produced by an inverted methane diffusion flame over a spectral range of 300-660 nm using a variety of optical absorption techniques. Extinction and absorption were measured using a dual cavity ringdown photoacoustic spectrometer (CRD-PAS, UC Davis) at 405 nm and 532 nm. Scattering and extinction were measured using a CAPS PMssa single scattering albedo monitor (Aerodyne) at 630 nm; the absorption coefficient was determined by subtraction. In addition, the absorption coefficients in 8 wavelength bands from 300 to 660 nm were measured using a new broadband photoacoustic absorption monitor (UGA). Soot particle mass was quantified using a centrifugal particle mass analyzer (CPMA, Cambustion), mobility size with a scanning mobility particle sizer (SMPS, TSI) and soot concentration with a CPC (Brechtel). The contribution of doubly charged particles to the sample mass was determined using a Single Particle Soot Photometer (DMT). Over a mass range of 1-8 fg, corresponding to differential mobility diameters of ~150 nm to 550 nm, the value of the soot MAC proved to be independent of mass for all wavelengths. The wavelength dependence of the MAC was best fit to a power law with an Absorption Ångstrom Coefficient slightly greater than 1.

  4. Micromachining with femtosecond 250-nm laser pulses

    NASA Astrophysics Data System (ADS)

    Li, C.; Argument, Michael A.; Tsui, Ying Y.; Fedosejevs, Robert

    2000-12-01

    Laser micromachining is a flexible technique for precision patterning of surfaces in microelectronics, microelectromechanical devices and integrated optical devices. Typical applications include drilling of holes, cutting of conducting lines or shaping of micro component surfaces. The resolution, edge finish and residual damage to the surrounding and underlying structures depend on a variety of parameters including laser energy, intensity, pulse width and wavelength. Femtosecond pulses are of particular interest because the limited time of interaction limits the lateral expansion of the plasma and the inward propagation of the heat front. Thus, very small spot size can be achieved and minimal heating and damage of underlying layers can be obtained. An additional advantage of femtosecond pulses is that multiphoton absorption leads to efficient coupling of energy to many materials independent of the linear reflectivity of the surface. Thus metals and transmitting dielectrics, which are difficult to micromachine, may be machined with such pulses. The coupling is improved further by employing ultraviolet wavelength laser pulses where the linear absorption typically is much higher than for visible and infrared laser pulses. To explore these advantages, we have initiated a study of the interaction of 250nm femtosecond laser pulses with metals. The laser pulses are obtained by generating the third harmonic from a femtosecond Ti:sapphire laser operating at 750nm. The pulses are focused to various intensities in the range of 1010Wcm2 to 1015 Wcm2 using reflective and refractive microscope objectives and ablation thresholds and ablation rates have been determined for a few metals. In addition the ability to control feature size and produce submicron holes and lines have been investigated. The results are presented and compared to results obtained using infrared and visible femtosecond laser pulses.

  5. The cause of spatial structure in solar He i 1083 nm multiplet images

    NASA Astrophysics Data System (ADS)

    Leenaarts, Jorrit; Golding, Thomas; Carlsson, Mats; Libbrecht, Tine; Joshi, Jayant

    2016-10-01

    Context. The He i 1083 nm is a powerful diagnostic for inferring properties of the upper solar chromosphere, in particular for the magnetic field. The basic formation of the line in one-dimensional models is well understood, but the influence of the complex three-dimensional structure of the chromosphere and corona has however never been investigated. This structure must play an essential role because images taken in He i 1083 nm show structures with widths down to 100 km. Aims: We aim to understand the effect of the three-dimensional temperature and density structure in the solar atmosphere on the formation of the He i 1083 nm line. Methods: We solved the non-LTE radiative transfer problem assuming statistical equilibrium for a simple nine-level helium atom that nevertheless captures all essential physics. As a model atmosphere we used a snapshot from a 3D radiation-MHD simulation computed with the Bifrost code. Ionising radiation from the corona was self-consistently taken into account. Results: The emergent intensity in the He i 1083 nm is set by the source function and the opacity in the upper chromosphere. The former is dominated by scattering of photospheric radiation and does not vary much with spatial location. The latter is determined by the photonionisation rate in the He i ground state continuum, as well as the electron density in the chromosphere. The spatial variation of the flux of ionising radiation is caused by the spatially-structured emissivity of the ionising photons from material at T ≈ 100 kK in the transition region. The hotter coronal material produces more ionising photons, but the resulting radiation field is smooth and does not lead to small-scale variation of the UV flux. The corrugation of the transition region further increases the spatial variation of the amount of UV radiation in the chromosphere. Finally we find that variations in the chromospheric electron density also cause strong variation in He i 1083 nm opacity. We compare our

  6. Evaluation of a high exposure solar UV dosimeter for underwater use.

    PubMed

    Schouten, Peter W; Parisi, Alfio V; Turnbull, David J

    2007-01-01

    Solar ultraviolet radiation (UV) is known to have a significant effect upon the marine ecosystem. This has been documented by many previous studies using a variety of measurement methods in aquatic environments such as oceans, streams and lakes. Evidence gathered from these investigations has shown that UVB radiation (280-320 nm) can negatively affect numerous aquatic life forms, while UVA radiation (320-400 nm) can both damage and possibly even repair certain types of underwater life. Chemical dosimeters such as polysulphone have been tested to record underwater UV exposures and in turn quantify the relationship between water column depth and dissolved organic carbon levels to the distribution of biologically damaging UV underwater. However, these studies have only been able to intercept UV exposures over relatively short time intervals. This paper reports on the evaluation of a high exposure UV dosimeter for underwater use. The UV dosimeter was fabricated from poly 2,6-dimethyl-1,4-phenylene oxide (PPO) film. This paper presents the dose response, cosine response, exposure additivity and watermarking effect relating to the PPO dosimeter as measured in a controlled underwater environment and will also detail the overnight dark reaction and UVA and visible radiation response of the PPO dosimeter, which can be used for error correction to improve the reliability of the UV data measured by the PPO dosimeters. These results show that this dosimeter has the potential for long-term underwater UV exposure measurements. PMID:17645666

  7. Lasing at 300 nm and below: Optical challenges and perspectives

    SciTech Connect

    Garzella, D.; Couprie, M.E. |; Billardon, M.

    1995-12-31

    The FEL experiment in the visible and near UV on the Super ACO storage ring has given, since 1989, important informations on the SRFEL dynamics and, furthermore, a very good beam stability has been achieved. In addition, the operation at 350 nm with this good stability and a long beam lifetime allowed us to perform the first user experiment in biology and to start with a campaign for using the laser as photons source for experiments in other domains, coupling FEL light and the Synchrotron Radiation. For this, FEL starts to be very competitive with respect to the other conventional laser sources, provided that it could oscillate further in the UV, say at 300 nm and below. So, the real challenge is now given by the lasing at shorter wavelengths and, for this, by the optical technology existing nowadays. Since 1992 the efforts have been concentrating to look for every kind of solution allowing us to overcome the problem of having a very low gain. From an optical point of view, in the range of wavelengths explored, there is a lack of transparents dielectric materials for substrates and coatings. Substrates are required at the same time to be relatively not absorbing (a few tens 10{sup -6}), to have a very good surface quality (RMS roughness below 10 {Angstrom}) because of scattering losses dramatically increasing in this spectral range and, due to the thermal load of the undulator emission, to have adequate thermal characteristics. In order to fulfill all these requirements, a good characterisation and modelisation of the substrates is needed, especially to correlate thermal loading and mechanical deformations from one hand, and roughness and scattering losses from the other hand. Coatings must be not absorbing too and, above all, the most amorphous as possible (this could be obtained with IBS deposition technique), in order to insure a good reproduction of the substrate roughness at the interfaces and on the top layer and an higher resistance to the XUV photons load.

  8. Design and study of resist materials for 157-nm lithography

    NASA Astrophysics Data System (ADS)

    Yamada, Shintaro; Cho, Sungseo; Zampini, Anthony

    2003-06-01

    We investigated the structure-property relationships of several polymer platforms containing hexafluoroisopropanol (HFIP) and tertiary alkyl ester functionalities in order to identify and develop fluorine-containing polymers suitable for 157nm lithography. We observed that the aqueous base solubility of homopolymers containing HFIP was highly dependent on the monomer structure, number of HFIP group per monomer unit, substituent on the alcohol and the polymer architecture. Copolymers of tert-butyl acrylate (TBA), tert-butyl 2-fluoroacrylate (TBFA) and tert-butyl 2-trifluoromethylacrylate (TBTFMA) with styrene hexafluoroisopropanol (STYHFIP) or norborene hexafluoro-isopropanol (NBHFIP) were also investigated to determine the effect of substitution at the acrylate α-position. Under the same ration of STYHFIP, the transparency of the co-polymers improved in the or der of CF3>F>H while the dry etch stability decreased in the order of CF3>F>H. When exposed to 157 nm radiation, photoresists of P(STYHFIP-TBA), P(STYHFIP-TBFA) and P(STYHFIP-TBTFMA) showed an increase in E0 ni the order of H

  9. 1.86 W cw single-frequency 1319 nm ring laser pumped at 885 nm.

    PubMed

    Li, M L; Zhao, W F; Zhang, S B; Guo, L; Hou, W; Li, J M; Lin, X C

    2012-03-20

    A 1.86 W cw single-frequency 1319 nm laser was produced by using an 885 nm-pumped Nd:YAG crystal with a compact four-mirror ring cavity, for the first time to our knowledge. The Nd:YAG produced a slope efficiency of 21% and an optical-to-optical efficiency of 18% with respect to the absorbed diode pump power. A near-diffraction-limited beam with M(2)=1.2 was achieved under the maximum output power. PMID:22441467

  10. Measurement of 100 nm and 60 nm Particle Standards by Differential Mobility Analysis

    PubMed Central

    Mulholland, George W.; Donnelly, Michelle K.; Hagwood, Charles R.; Kukuck, Scott R.; Hackley, Vincent A.; Pui, David Y. H.

    2006-01-01

    The peak particle size and expanded uncertainties (95 % confidence interval) for two new particle calibration standards are measured as 101.8 nm ± 1.1 nm and 60.39 nm ± 0.63 nm. The particle samples are polystyrene spheres suspended in filtered, deionized water at a mass fraction of about 0.5 %. The size distribution measurements of aerosolized particles are made using a differential mobility analyzer (DMA) system calibrated using SRM® 1963 (100.7 nm polystyrene spheres). An electrospray aerosol generator was used for generating the 60 nm aerosol to almost eliminate the generation of multiply charged dimers and trimers and to minimize the effect of non-volatile contaminants increasing the particle size. The testing for the homogeneity of the samples and for the presence of multimers using dynamic light scattering is described. The use of the transfer function integral in the calibration of the DMA is shown to reduce the uncertainty in the measurement of the peak particle size compared to the approach based on the peak in the concentration vs. voltage distribution. A modified aerosol/sheath inlet, recirculating sheath flow, a high ratio of sheath flow to the aerosol flow, and accurate pressure, temperature, and voltage measurements have increased the resolution and accuracy of the measurements. A significant consideration in the uncertainty analysis was the correlation between the slip correction of the calibration particle and the measured particle. Including the correlation reduced the expanded uncertainty from approximately 1.8 % of the particle size to about 1.0 %. The effect of non-volatile contaminants in the polystyrene suspensions on the peak particle size and the uncertainty in the size is determined. The full size distributions for both the 60 nm and 100 nm spheres are tabulated and selected mean sizes including the number mean diameter and the dynamic light scattering mean diameter are computed. The use of these particles for calibrating DMAs and for

  11. The Doubling of 846 nm Light to Produce 423 nm Light for use in Atom Interferometry

    NASA Astrophysics Data System (ADS)

    Archibald, James; Birrell, Jeremey; Tang, Rebecca; Erickson, Chris; Goggins, Landon; Durfee, Dallin

    2009-10-01

    We present progress on a 423 nm fluorescence probe/cooling laser for use in our neutral calcium atom interferometer. The finished system will include an 846 nm diode laser that is coupled to a tapered amplifier. This light will be sent to a buildup cavity where we will achieve second-harmonic generation (SHG) using either a BBO non-linear crystal or a periodically-poled KTP crystal. We will discuss the theoretical considerations relating to the doubling of light in a crystal and the construction of our buildup cavity. We will also discuss its proposed application for use in atom interferometry.

  12. Absorption Measurements of Periodically Poled Potassium Titanyl Phosphate (PPKTP) at 775 nm and 1550 nm

    PubMed Central

    Steinlechner, Jessica; Ast, Stefan; Krüger, Christoph; Singh, Amrit Pal; Eberle, Tobias; Händchen, Vitus; Schnabel, Roman

    2013-01-01

    The efficient generation of second-harmonic light and squeezed light requires non-linear crystals that have low absorption at the fundamental and harmonic wavelengths. In this work the photo-thermal self-phase modulation technique is exploited to measure the absorption coefficient of periodically poled potassium titanyl phosphate (PPKTP) at 1,550 nm and 775 nm. The measurement results are (84±40) ppm/cm and (127±24) ppm/cm, respectively. We conclude that the performance of state-of-the-art frequency doubling and squeezed light generation in PPKTP is not limited by absorption. PMID:23291574

  13. Laser-Matter Interactions with a 527 nm Drive

    SciTech Connect

    Glenzer, S; Niemann, C; Witman, P; Wegner, P; Mason, D; Haynam, C; Parham, T; Datte, P

    2007-02-16

    The primary goal of this Exploratory Research is to develop an understanding of laser-matter interactions with 527-nm light (2{omega}) for studies of interest to numerous Laboratory programs including inertial confinement fusion (ICF), material strength, radiation transport, and hydrodynamics. In addition, during the course of this work we will develop the enabling technology and prototype instrumentation to diagnose a high fluence laser beam for energy, power, and near field intensity profile at 2{omega}. Through this Exploratory Research we have established an extensive experimental and modeling data base on laser-matter interaction with 527 nm laser light (2{omega}) in plasma conditions of interest to numerous Laboratory programs. The experiments and the laser-plasma interaction modeling using the code pF3D have shown intensity limits and laser beam conditioning requirements for future 2{omega} laser operations and target physics experiments on the National Ignition Facility (NIF). These findings have set requirements for which present radiation-hydrodynamic simulations indicate the successful generation of relevant pressure regimes in future 2{omega} experiments. To allow these experiments on the NIF, optics and optical mounts were prepared for the 18mm Second Harmonic Generation Crystal (SHG crystal) that would provide the desired high conversion efficiency from 1{omega} to 2{omega}. Supporting experimental activities on NIF included high-energy 1{omega} shots at up to 22kJ/beamline (4MJ full NIF 1{omega} equivalent energy) that demonstrated, in excess, the 1{omega} drive capability of the main laser that is required for 2{omega} operations. Also, a very extensive 3{omega} campaign was completed (see ''The National Ignition Facility Laser Performance Status'' UCRL-JRNL-226553) that demonstrated that not only doubling the laser, but also tripling the laser (a much more difficult and sensitive combination) met our model predictions over a wide range of laser

  14. Radiation Therapy

    MedlinePlus

    Radiation therapy is a cancer treatment. It uses high doses of radiation to kill cancer cells and stop them from ... half of all cancer patients receive it. The radiation may be external, from special machines, or internal, ...

  15. Radiation Therapy

    MedlinePlus

    ... people who have radiation therapy may feel more tired than usual, not feel hungry, or lose their ... of radiation therapy include: Fatigue. Fatigue, or feeling tired, is the most common side effect of radiation ...

  16. Radiation therapy

    MedlinePlus

    ... Because radiation is most harmful to quickly growing cells, radiation therapy damages cancer cells more than normal cells. ... cells from growing and dividing, and leads to cell death. Radiation therapy is used to fight many types of ...

  17. 1064 nm Nd:YVO4 laser intracavity pumped at 912 nm and sum-frequency mixing for an emission at 491 nm.

    PubMed

    Herault, Emilie; Balembois, François; Georges, Patrick; Georges, Thierry

    2008-07-15

    We present for the first time a Nd:YVO(4) laser emitting at 1064 nm intracavity pumped at 912 nm by a Nd:GdVO(4) laser. We carried out a model to design the system properly, and laser performance was experimentally investigated. Intracavity sum-frequency mixing at 912 and 1064 nm was then realized in a BiBO crystal to reach the blue range. We obtained a cw output power of 155 mW at 491 nm with a pump laser diode emitting 20 W at 808 nm. PMID:18628821

  18. 65nm RadSafe™ Technology for RC64 and Advanced SOCs

    NASA Astrophysics Data System (ADS)

    Liran, Tuvia; Ginosar, Ran; Lange, Fredy; Mandler, Alberto; Aviely, Peleg; Meirov, Henri; Goldberg, Michael; Meister, Zeev; Oliel, Mickey

    2015-09-01

    The trend of scaling of microelectronic provides certain advantages for space components, as well as some challenges. It enables implementing highly integrated and high performance ASICs, reducing power, area and weight. Scaling also improves the immunity to TID and SEL in most cases, but increases soft error rate significantly. Ramon Chips adopted the 65nm technology for implementing RC64 [1,2], a 64 core DSP for space applications, and for making other future products. The 65nm process node is widely used, very mature, and supported by wide range of IP providers. Thus the need for full custom design of cores and IPs is minimized, and radiation hardening is achievable by mitigating the radiation effects on the available IPs, and developing proprietary IPs only for complementing the available IPs. The RadSafe_65TM technology includes hardened standard cells and I/O libraries, methods for mitigation of radiation effects in COTS IP cores (SRAM, PLL, SERDES, DDR2/3 interface) and adding unique cores for monitoring radiation effects and junction temperature. We had developed RADIC6, a technology development vehicle, for verification of all hard cores and verification of the methodologies and design flow required for RC64. RADIC6 includes the test structures for characterizing the IP cores for immunity to all radiation effects. This paper describes the main elements and IP cores of RadSafe_65TM, as well as the contents of RADIC6 test chip.

  19. Inspection and repair for imprint lithography at 32 nm and below

    NASA Astrophysics Data System (ADS)

    Selinidis, Kosta; Thompson, Ecron; Sreenivasan, S. V.; Resnick, Douglas J.; Pritschow, Marcus; Butschke, Joerg; Irmscher, Mathias; Sailer, Holger; Dobberstein, Harald

    2009-04-01

    Step and Flash Imprint involves the field-by-field deposition and exposure of a low viscosity resist deposited by jetting technology onto the substrate. The patterned mask is lowered into the fluid which then quickly flows into the relief patterns in the mask by capillary action. Following this filling step, the resist is crosslinked under UV radiation, and then the mask is removed leaving a patterned solid on the substrate. Compatibility with existing CMOS processes requires a mask infrastructure in which resolution, inspection and repair are all addressed. The purpose of this paper is to understand the progress made in inspection and repair of 1X imprint masks A 32 nm programmed defect mask was fabricated. Patterns included in the mask consisted of an SRAM Metal 1 cell, dense lines, and dense arrays of pillars. Programmed defect sizes started at 4 nm and increased to 48 nm in increments of 4 nm. These defects were then inspected using three different electron beam inspection systems. Defect sizes as small as 8 nm were detected, and detection limits were found to be a function of defect type. Both subtractive and additive repairs were attempted on SRAM Metal 1 cells. Repairs as small as 32nm were demonstrated, and the repair process was successfully tested for several hundreds of imprints.

  20. Near infrared imaging of teeth at wavelengths between 1200 and 1600 nm

    NASA Astrophysics Data System (ADS)

    Chung, Soojeong; Fried, Daniel; Staninec, Michal; Darling, Cynthia L.

    2011-03-01

    Near-IR (NIR) imaging is a new technology that is currently being investigated for the detection and assessment of dental caries without the use of ionizing radiation. Several papers have been published on the use of transillumination and reflectance NIR imaging to detect early caries in enamel. The purpose of this study was to investigate alternative near infrared wavelengths besides 1300-nm in the range from 1200- 1600-nm to determine the wavelengths that yield the highest contrast in both transmission and reflectance imaging modes. Artificial lesions were created on thirty tooth sections of varying thickness for transillumination imaging. NIR images at wavelengths from the visible to 1600-nm were also acquired for fifty-four whole teeth with occlusal lesions using a tungsten halogen lamp with several spectral filters and a Ge-enhanced CMOS image sensor. Cavity preparations were also cut into whole teeth and Z250 composite was used as a restorative material to determine the contrast between composite and enamel at NIR wavelengths. Slightly longer NIR wavelengths are likely to have better performance for the transillumination of occlusal caries lesions while 1300-nm appears best for the transillumination of proximal surfaces. Significantly higher performance was attained at wavelengths that have higher water absorption, namely 1460-nm and wavelengths greater than 1500-nm and these wavelength regions are likely to be more effective for reflectance imaging. Wavelengths with higher water absorption also provided higher contrast of composite restorations.

  1. 491 nm generation by sum-frequency mixing of diode pumped neodymium lasers

    NASA Astrophysics Data System (ADS)

    Herault, Emilie; Balembois, François; Georges, Partick

    2005-07-01

    We present three different dual-wavelength laser architectures to obtain cw blue radiations. They are based on diode-pumped Nd-doped crystals lasing on the 4F3/2-4I11/2 and 4F3/2-4I9/2 transitions. Blue radiations were achieved by intracavity sum frequency operation in a BiB3O6 crystal. We report a maximum output blue power of 303 mW at 491 nm for a pump power of 10 W.

  2. Collateral damage-free debridement using 193nm ArF laser

    NASA Astrophysics Data System (ADS)

    Wynne, James J.; Felsenstein, Jerome M.; Trzcinski, Robert; Zupanski-Nielsen, Donna; Connors, Daniel P.

    2011-03-01

    Burn eschar and other necrotic areas of the skin and soft tissue are anhydrous compared to the underlying viable tissue. A 193 nm ArF excimer laser, emitting electromagnetic radiation at 6.4 eV at fluence exceeding the ablation threshold, will debride such necrotic areas. Because such radiation is strongly absorbed by aqueous chloride ions through the nonthermal process of electron photodetachment, debridement will cease when hydrated (with chloride ions) viable tissue is exposed, avoiding collateral damage to this tissue. Such tissue will be sterile and ready for further treatment, such as a wound dressing and/or a skin graft.

  3. Emission in argon and krypton at 147 nm excited by runaway-electron-induced diffusion discharge

    SciTech Connect

    Gerasimov, Gennadii N; Krylov, B E; Lomaev, Mikhail I; Rybka, D V; Tarasenko, Viktor F

    2010-05-26

    Plasma emission of a pulsed diffuse discharge produced at increased pressures due to the preionisation of the gap by runaway electrons is studied in argon, krypton, and xenon. Nanosecond voltage pulses with the amplitude {approx}220 kV were applied to the discharge gap. It is shown that the presence of xenon ({approx}0.01%) in argon and krypton leads to the emergence of high-power narrowband radiation at awavelength of 147 nm. It is assumed that this radiation belongs to the bands of heteronuclear molecules Xe*Ar and Xe*Kr.

  4. Atmospheric radiation

    SciTech Connect

    Harshvardhan, M.R. )

    1991-01-01

    Studies of atmospheric radiative processes are summarized for the period 1987-1990. Topics discussed include radiation modeling; clouds and radiation; radiative effects in dynamics and climate; radiation budget and aerosol effects; and gaseous absorption, particulate scattering and surface reflection. It is concluded that the key developments of the period are a defining of the radiative forcing to the climate system by trace gases and clouds, the recognition that cloud microphysics and morphology need to be incorporated not only into radiation models but also climate models, and the isolation of a few important unsolved theoretical problems in atmospheric radiation.

  5. All solid-state 191.7 nm deep-UV light source by seventh harmonic generation of an 888 nm pumped, Q-switched 1342 nm Nd:YVO₄ laser with excellent beam quality.

    PubMed

    Koch, Peter; Bartschke, Juergen; L'huillier, Johannes A

    2014-06-01

    In this paper we report on the realization of a deep-UV light source using the 1.3 μm transition of neodymium as pumping wavelength. The 191.7 nm radiation was obtained by generating the seventh harmonic of a high-power Q-switched 1342 nm Nd:YVO4 laser. A cesium lithium borate crystal was used for sum frequency mixing of the sixth harmonic and the fundamental. With a total of four conversion stages, up to 240 mW were achieved, with excellent beam quality at 155 mW (M2 < 1.7) and 190 mW (M2 < 1.9).

  6. Photodissociation of the Propargyl (C3D3) Radicals at 248 nm and 193 nm

    SciTech Connect

    Neumark., D.M.; Crider, P.E.; Castiglioni, L.; Kautzman, K.K.

    2009-01-21

    The photodissociation of perdeuterated propargyl (D{sub 2}CCCD) and propynyl (D{sub 3}CCC) radicals was investigated using fast beam photofragment translational spectroscopy. Radicals were produced from their respective anions by photodetachment at 540 nm and 450 nm (below and above the electron affinity of propynyl). The radicals were then photodissociated by 248 nm or 193 nm light. The recoiling photofragments were detected in coincidence with a time- and position-sensitive detector. Three channels were observed: D{sub 2} loss, CD + C{sub 2}D{sub 2}, and CD{sub 3} + C{sub 2}. Obervation of the D loss channel was incompatible with this experiment and was not attempted. Our translational energy distributions for D{sub 2} loss peaked at nonzero translational energy, consistent with ground state dissociation over small (< 1 eV) exit barriers with respect to separated products. Translational energy distributions for the two heavy channels peaked near zero kinetic energy, indicating dissociation on the ground state in the absence of exit barriers.

  7. Evaluation of the Diode laser (810nm,980nm) on dentin tubule diameter following internal bleaching

    PubMed Central

    Kiomarsi, Nazanin; Salim, Soheil; Sarraf, Pegah; Javad-Kharazifard, Mohammad

    2016-01-01

    Background The aim of this study was to evaluate the effect of diode laser irradiation and bleaching materials on the dentinal tubule diameter after laser bleaching. Material and Methods The dentin discs of 40 extracted third molar were used in this experiment. Each disc surface was divided into two halves by grooving. Half of samples were laser bleached at different wavelengths with two different concentrations of hydrogen peroxide. Other half of each disc with no laser bleaching remained as a negative control. Dentin discs were assigned randomly into four groups (n=10) with following hydrogen peroxide and diode laser wavelength specifications; Group 1 (30% - 810 nm), group 2 (30% - 980 nm), group 3 (46% - 810 nm) and group 4 (46% - 980 nm). All specimens were sent for scanning electron microscopic (SEM) analysis in order to measure tubular diameter in laser treated and control halves. Data were analyzed by ANOVA and Tukey test (p<0.05). Results A significant reduction in dentin tubule diameter was observed in groups 1, 2 and 4. There was no significant difference between groups 1 and 2 and between groups 3 and 4 after bleaching. Conclusions The SEM results showed that diode laser was able to reduce dentin tubule diameter and its effect on dentin was dependent on chemical action of bleaching material. Key words:Laser, diode, dentin, tubule, diameter. PMID:27398172

  8. NXT:1980Di immersion scanner for 7nm and 5nm production nodes

    NASA Astrophysics Data System (ADS)

    de Graaf, Roelof; Weichselbaum, Stefan; Droste, Richard; McLaren, Matthew; Koek, Bert; de Boeij, Wim

    2016-03-01

    Immersion scanners remain the critical lithography workhorses in semiconductor device manufacturing. When progressing towards the 7nm device node for logic and D18 device node for DRAM production, pattern-placement and layer-to-layer overlay requirements keep progressively scaling down and consequently require system improvements in immersion scanners. The on-product-overlay requirements are approaching levels of only a few nanometers, imposing stringent requirements on the scanner tool design in terms of reproducibility, accuracy and stability. In this paper we report on the performance of the NXT:1980Di immersion scanner. The NXT:1980Di builds upon the NXT:1970Ci, that is widely used for 16nm, 14nm and 10nm high-volume manufacturing. We will discuss the NXT:1980Di system- and sub-system/module enhancements that drive the scanner overlay, focus and productivity performance. Overlay, imaging, focus, productivity and defectivity data will be presented for multiple tools. To further reduce the on-product overlay system performance, alignment sensor contrast improvements as well as active reticle temperature conditioning are implemented on the NXT:1980Di. Reticle temperature conditioning will reduce reticle heating overlay and the higher contrast alignment sensor will improve alignment robustness for processed alignment targets. Due to an increased usage of multiple patterning techniques, an increased number of immersion exposures is required. NXT:1980Di scanner design modifications raised productivity levels from 250wph to 275wph. This productivity enhancement provides lower cost of ownership (CoO) for customers using immersion technology.

  9. THE SPECTRUM OF THORIUM FROM 250 nm TO 5500 nm: RITZ WAVELENGTHS AND OPTIMIZED ENERGY LEVELS

    SciTech Connect

    Redman, Stephen L.; Nave, Gillian; Sansonetti, Craig J.

    2014-03-01

    We have made precise observations of a thorium-argon hollow cathode lamp emission spectrum in the region between 350 nm and 1175 nm using a high-resolution Fourier transform spectrometer. Our measurements are combined with results from seven previously published thorium line lists to re-optimize the energy levels of neutral, singly, and doubly ionized thorium (Th I, Th II, and Th III). Using the optimized level values, we calculate accurate Ritz wavelengths for 19, 874 thorium lines between 250 nm and 5500 nm (40, 000 cm{sup –1} to 1800 cm{sup –1}). We have also found 102 new thorium energy levels. A systematic analysis of previous measurements in light of our new results allows us to identify and propose corrections for systematic errors in Palmer and Engleman and typographical errors and incorrect classifications in Kerber et al. We also found a large scatter with respect to the thorium line list of Lovis and Pepe. We anticipate that our Ritz wavelengths will lead to improved measurement accuracy for current and future spectrographs that make use of thorium-argon or thorium-neon lamps as calibration standards.

  10. Multilayer X-ray mirrors for the (4.4-5)-nm carbon-window spectral region

    SciTech Connect

    Andreev, S. S.; Barysheva, M. M.; Vainer, Yu. A.; Gaikovich, P. K.; Pariev, D. E. Pestov, A. E.; Salashchenko, N. N.; Chkhalo, N. I.

    2013-05-15

    Cr/C-based multilayer X-ray mirrors intended for the reflection of X-ray radiation in the 'carbon-window' spectral region ({lambda} = 4.4-5 nm) are fabricated and studied. The structures are formed by magnetron sputtering at different deposition parameters. Under normal incidence, record reflection coefficients up to 15% are reached. The structural parameters of the mirrors are investigated by reflectometry at wavelengths of 0.154 and 4.47 nm.

  11. Faster qualification of 193-nm resists for 100-nm development using photo cell monitoring

    NASA Astrophysics Data System (ADS)

    Jones, Chris M.; Kallingal, Chidam; Zawadzki, Mary T.; Jeewakhan, Nazneen N.; Kaviani, Nazila N.; Krishnan, Prakash; Klaum, Arthur D.; Van Ess, Joel

    2003-05-01

    The development of 100-nm design rule technologies is currently taking place in many R&D facilities across the world. For some critical alyers, the transition to 193-nm resist technology has been required to meet this leading edge design rule. As with previous technology node transitions, the materials and processes available are undergoing changes and improvements as vendors encounter and solve problems. The initial implementation of the 193-nm resits process did not meet the photolithography requirements of some IC manufacturers due to very high Post Exposure Bake temperature sensitivity and consequently high wafer to wafer CD variation. The photoresist vendors have been working to improve the performance of the 193-nm resists to meet their customer's requirements. Characterization of these new resists needs to be carried out prior to implementation in the R&D line. Initial results on the second-generation resists evaluated at Cypress Semicondcutor showed better CD control compared to the aelrier resist with comparable Depth of Focus (DOF), Exposure Latitute, Etch Resistance, etc. In addition to the standard lithography parameters, resist characterization needs to include defect density studies. It was found that the new resists process with the best CD control, resulted in the introduction of orders of magnitude higher yield limiting defects at Gate, Contact adn Local Interconnect. The defect data were shared with the resists vendor and within days of the discovery the resist vendor was able to pinpoint the source of the problem. The fix was confirmed and the new resists were successfully released to production. By including defect monitoring into the resist qualification process, Cypress Semiconductor was able to 1) drive correction actions earlier resulting in faster ramp and 2) eliminate potential yield loss. We will discuss in this paper how to apply the Micro Photo Cell Monitoring methodology for defect monitoring in the photolithogprhay module and the

  12. 34 nm Charge Transport through DNA

    NASA Astrophysics Data System (ADS)

    Slinker, Jason; Muren, Natalie; Renfrew, Sara; Barton, Jacqueline

    2011-03-01

    Long-range charge transport through DNA has broad-reaching implications due to its inherent biological recognition capabilities and unmatched capacity to be patterned into precise, nanoscale shapes. We have observed charge transport through 34 nm DNA monolayers (100 base pairs) using DNA-mediated electrochemistry. Cyclic voltammetry of multiplexed gold electrodes modified with 100mer DNAs reveal sizable peaks from distally-bound Nile Blue redox probes for well matched duplexes but highly attenuated redox peaks from 100mer monolayers containing a single base pair mismatch, demonstrating that the charge transfer is DNA-mediated. The 100mers on the gold surface are efficiently cleaved by the restriction enzyme RsaI. The 100mers in the DNA film thus adopt conformations that are readily accessible to protein binding and restriction. The ability to assemble well-characterized DNA films with these 100mers permits the demonstration of charge transport over distances surpassing most reports of molecular wires. Supported by funding from the NIH/NIBIB.

  13. Illumination optimization for 65nm technology node

    NASA Astrophysics Data System (ADS)

    Wang, Ching-Heng; Liu, Qingwei; Zhang, Liguo; Hung, Chi-Yuan

    2006-10-01

    The most important task of the microlithography process is to make the manufacturable process latitude/window, including dose latitude and Depth of Focus, as wide as possible. Thus, to perform a thorough source optimization during process development is becoming more critical as moving to high NA technology nodes. Furthermore, Optical proximity correction (OPC) are always used to provide a common process window for structures that would, otherwise, have no overlapping windows. But as the critical dimension of the IC design shrinks dramatically, the flexibility for applying OPC also decreases. So a robust microlithography process should also be OPC-friendly. This paper demonstrates our work on the illumination optimization during the process development. The Calibre ILO (Illumination Optimization) tool was used to perform the illumination optimization and provided plots of DOF vs. various parametric illumination settings. This was used to screen the various illumination settings for the one with optimum process margins. The resulting illumination conditions were then implemented and analyzed at a real wafer level on our 90/65nm critical layers, such as Active, Poly, Contact and Metal. In conclusion, based on these results, a summary is provided highlighting how OPC can get benefit from proper illumination optimization.

  14. Sub-500  nm hard x ray focusing by compound long kinoform lenses.

    PubMed

    Liao, Keliang; Liu, Jing; Liang, Hao; Wu, Xuehui; Zhang, Kai; Yuan, Qingxi; Yi, Futing; Sheng, Weifan

    2016-01-01

    The focusing performance of polymethyl methacrylate compound long kinoform lenses with 70 μm aperture and 19.5 mm focal length was characterized with 8 keV x rays using the knife-edge scan method at the 4W1A transmission x-ray microscope beamline of Beijing Synchrotron Radiation Facility. The experiment result shows a best FWHM focus size of 440 nm with 31% diffraction efficiency. PMID:26835618

  15. Imaging at high spatial resolution: Soft x-ray microscopy to 15nm

    SciTech Connect

    Attwood, D.; Chao, W.; Anderson, E.; Liddle, J.A.; Harteneck, B.; Fischer, P.; Schneider, G.; Le Gros, M.; Larabell, C.

    2006-04-05

    Soft x-ray microscopy has now achieved 15 nm spatial resolution with new zone plates and bending magnet radiation. Combined with elemental sensitivity and flexible sample environment (applied magnetic or electric fields, wet samples, windows, overcoatings) this emerges as a valuable tool for nanoscience and nanotechnology, complimenting common electron and scanning tip microscopies. In this presentation we describe recent advances in spatial resolution, expectations for the near future, and applications to magnetic materials, bio-tomography, etc.

  16. Gd plasma source modeling at 6.7 nm for future lithography

    SciTech Connect

    Li Bowen; Dunne, Padraig; O'Sullivan, Gerry; Higashiguchi, Takeshi; Yugami, Noboru; Otsuka, Takamitsu; Jiang, Weihua; Endo, Akira

    2011-12-05

    Plasmas containing gadolinium have been proposed as sources for next generation lithography at 6.x nm. To determine the optimum plasma conditions, atomic structure calculations have been performed for Gd{sup 11+} to Gd{sup 27+} ions which showed that n = 4 - n = 4 resonance transitions overlap in the 6.5-7.0 nm region. Plasma modeling calculations, assuming collisional-radiative equilibrium, predict that the optimum temperature for an optically thin plasma is close to 110 eV and that maximum intensity occurs at 6.76 nm under these conditions. The close agreement between simulated and experimental spectra from laser and discharge produced plasmas indicates the validity of our approach.

  17. Continuous-wave coherent ultraviolet source at 326 nm based on frequency trippling of fiber amplifiers.

    PubMed

    Kim, Jae-Ihn; Meschede, Dieter

    2008-07-01

    We have demonstrated a tunable single frequency source of continuous-wave (CW) coherent ultraviolet (UV) radiation at lambda (3omega) = 326 nm. Laser light of a tunable diode laser at lambda(omega) = 977 nm was split and injected into two independent fiber amplifiers yielding 1 W and 0.4 W, respectively. The 1 W branch was resonantly frequency doubled, resulting in 120 mW of useful power at lambda(2omega) = 488 nm. The third harmonic was generated by summation of the second branch of lambda(omega) and lambda(2omega) which were enhanced by a doubly resonant cavity. This light source has TEM(00) character and can be continuously tuned over more than 18 GHz. It is of interest for efficient laser cooling of In and potentially other applications.

  18. 10{times} reduction imaging at 13.4nm

    SciTech Connect

    Tichenor, D.A.; Kubiak, G.D.; Malinowski, M.E.

    1994-08-01

    A Schwarzschild imaging system has been designed to achieve 0.1 {mu}m resolution in a 0.4 mm diameter field of view when operated at a center wavelength of 13.4 nm. A decentered aperture is located on the convex primary resulting in an unobstructed numerical aperture of 0.08 and a corresponding depth of field of {plus_minus} 1 {mu}m. The Schwarzschild imaging objective is part of a five-reflection system containing the laser plasma source (LPS), condensing optics, turning mirror and reflection mask as shown in Figure 1. Extreme ultraviolet (EUV) radiation is generated by impinging a laser beam onto a copper target. The plasma source is driven by a Lambda Physik PLX 250 KrF excimer laser emitting 0.6 Joule, 20 ns pulses at a 200 Hz maximum repetition rate. Measurements of the source indicate that the full-width-half-maximum diameter is less than 100 {mu}m.

  19. Photorefractive keratectomy at 193 nm using an erodible mask

    NASA Astrophysics Data System (ADS)

    Gordon, Michael; Brint, Stephen F.; Durrie, Daniel S.; Seiler, Theo; Friedman, Marc D.; Johnsson, N. M. F.; King, Michael C.; Muller, David F.

    1992-08-01

    Clinical experience with more than ten thousand sighted eyes has demonstrated great promise for correcting myopia with photorefractive keratectomy (PRK). Previously reported techniques have incorporated computer-controlled irises, diaphragms, and apertures to regulate the desired distribution of 193 nm radiation onto the eye. This paper reports on an entirely new approach for performing PRK which utilizes an erodible mask to control the shape transfer process. Compared to the more traditional techniques, the erodible mask offers promise of correcting a broad range of refractive errors. In this paper the erodible mask and associated hardware are described in detail. We describe the shape transfer experiments used to predict the functional relationship between the desired refractive correction and the mask shape. We report on early clinical results from five patients with myopic astigmatism. We conclude that the early shape transfer experiments overestimated the spherical component of the correction by 1.25 diopters and underestimated the cylindrical component by approximately 0.85 diopters. The data suggest there may be biological effects which evoke different healing responses when myopic PRK corrections are performed with and without astigmatism. Clinical trials are proceeding with the mask shapes adjusted for these observations.

  20. Pelvic radiation - discharge

    MedlinePlus

    Radiation of the pelvis - discharge; Cancer treatment - pelvic radiation; Prostate cancer - pelvic radiation; Ovarian cancer - pelvic radiation; Cervical cancer - pelvic radiation; Uterine cancer - pelvic radiation; Rectal cancer - ...

  1. Analysis of the UV-B Regime and Potential Effects on Alfalfa

    NASA Technical Reports Server (NTRS)

    Seitz, Jeffery C.

    1998-01-01

    Life at the surface of the Earth, over the last 400 m.y., evolved under conditions of decreased short-wave radiation (i.e., ultraviolet) relative to solar output due to absorption and scattering by constituents (e.g., ozone, water vapor, aerosols) in the upper atmosphere. However, a significant amount of ultraviolet radiation in the range from 280-320 nm, known as ultraviolet-B radiation, reaches the Earth's surface and has sufficient energy to be damaging to biologic tissue. Natural fluctuations in atmospheric constituents (seasonal variation, volcanic eruptions, etc.), changes in the orbital attitude of the Earth (precession, axial tilt, orbital eccentricity), and long-term solar variability contribute to changes in the total amount of ultraviolet radiation reaching the surface of the Earth, and thus, the biosphere. More recently, the atmospheric release of commercial propellants and refrigerants, known as chlorofluorocarbons (CFCs), has contributed to a significant depletion in naturally occurring ozone in the stratosphere. Thus, decreased stratospheric ozone has resulted in an increased UV-B flux at the Earth's surface which may have profound effects on terrestrial and marine organisms. In this study, we are investigating the effects of differing solar UV-B fluxes on alfalfa (Medicago sativa L.), an important agricultural crop. A long-term goal of this research is to develop spectral signatures to detect plant response to increased UV-B radiation from remote sensor platforms.

  2. OPC structures for maskshops qualification for the CMOS65nm and CMOS45nm nodes

    NASA Astrophysics Data System (ADS)

    Sundermann, Frank; Trouiller, Yorick; Urbani, Jean-Christophe; Couderc, Christophe; Belledent, Jérôme; Borjon, Amandine; Foussadier, Franck; Gardin, Christian; LeCam, Laurent; Rody, Yves; Saied, Mazen; Yesilada, Emek; Martinelli, Catherine; Wilkinson, Bill; Vautrin, Florent; Morgana, Nicolo; Robert, Frederic; Montgomery, Patrick; Kerrien, Gurwan; Planchot, Jonathan; Farys, Vincent; Di Maria, Jean-Luc

    2007-02-01

    Several qualification stages are required for new maskshop tools, first step is done by the maskshop internally. Taking a new writer for example, the maskshop will review the basic factory and site acceptance tests, including CD uniformity, CD linearity, local CD errors and registration errors. The second step is to have dedicated OPC (Optical Proximity Correction) structures from the wafer fab. These dedicated OPC structures will be measured by the maskshop to get a reticle CD metrology trend line. With this trend line, we can: - ensure the stability at reticle level of the maskshop processes - put in place a matching procedure to guarantee the same OPC signature at reticle level in case of any internal maskshop process change or new maskshop evaluation. Changes that require qualification could be process changes for capacity reasons, like introducing a new writer or a new manufacturing line, or for capability reasons, like a new process (new developer tool for example) introduction. Most advanced levels will have dedicated OPC structures. Also dedicated maskshop processes will be monitored with these specific OPC structures. In this paper, we will follow in detail the different reticle CD measurements of dedicated OPC structures for the three advanced logic levels of the 65nm node: poly level, contact level and metal level. The related maskshop's processes are - for poly: eaPSM 193nm with a nega CAR (Chemically Amplified Resist) process for Clear Field L/S (Lines & Space) reticles - for contact: eaPSM 193nm with a posi CAR process for Dark Field Holes reticles - for metal1: eaPSM 193nm with a posi CAR process for Dark Field L/S reticles. For all these structures, CD linearity, CD through pitch, length effects, and pattern density effects will be monitored. To average the metrology errors, the structures are placed twice on the reticle. The first part of this paper will describe the different OPC structures. These OPC structures are close to the DRM (Design Rule

  3. Tunable UV generation at 286 nm by frequency tripling of a high-power mode-locked semiconductor laser

    SciTech Connect

    Goldberg, L.; Kliner, D.A.V.

    1995-08-01

    We produced ultraviolet radiation by frequency tripling the mode-locked emission of an external cavity laser containing a tapered GaAlAs amplifier gain element. The 429-nm second harmonic produced by a KNbO{sub 3} crystal was sum-frequency mixed with the 858-nm fundamental in a Li{sub 3}BO{sub 5} crystal, generating as much as 50{mu}W of power at 286 nm. {copyright} {ital 1995} {ital Optical} {ital Society} {ital of} {ital America}.

  4. Multi-watt 589nm fiber laser source

    SciTech Connect

    DAWSON, J W; DROBSHOFF, A D; BEACH, R J; MESSERLY, M J; PAYNE, S A; BROWN, A; PENNINGTON, D M; BAMFORD, D J; SHARPE, S J; COOK, D J

    2006-01-19

    We have demonstrated 3.5W of 589nm light from a fiber laser using periodically poled stoichiometric Lithium Tantalate (PPSLT) as the frequency conversion crystal. The system employs 938nm and 1583nm fiber lasers, which were sum-frequency mixed in PPSLT to generate 589nm light. The 938nm fiber laser consists of a single frequency diode laser master oscillator (200mW), which was amplified in two stages to >15W using cladding pumped Nd{sup 3+} fiber amplifiers. The fiber amplifiers operate at 938nm and minimize amplified spontaneous emission at 1088nm by employing a specialty fiber design, which maximizes the core size relative to the cladding diameter. This design allows the 3-level laser system to operate at high inversion, thus making it competitive with the competing 1088nm 4-level laser transition. At 15W, the 938nm laser has an M{sup 2} of 1.1 and good polarization (correctable with a quarter and half wave plate to >15:1). The 1583nm fiber laser consists of a Koheras 1583nm fiber DFB laser that is pre-amplified to 100mW, phase modulated and then amplified to 14W in a commercial IPG fiber amplifier. As a part of our research efforts we are also investigating pulsed laser formats and power scaling of the 589nm system. We will discuss the fiber laser design and operation as well as our results in power scaling at 589nm.

  5. Abiogenic synthesis of oligopeptides in solid state under action of vacuum ultraviolet light (100-200 nm)

    NASA Astrophysics Data System (ADS)

    Simakov, M. B.; Kuzicheva, E. A.; Mal'Ko, I. L.; Dodonova, N. Ya.

    Thin films containing a mixture of aliphatic (glycine) and aromatic (tryptophan or tyrosine) amino acids were exposed to a vacuum ultraviolet radiation (VUV) with wavelengths 100-200 nm. Dipeptides (glycyl-tryptophan and glycyltyrosine) were synthesized in these conditions. We compared the actions of VUV and gamma-radiation. Polymerization is an essential step in prebiological evolution and we have shown that this stage probably occured over an early Solar system history.

  6. Polarization properties of lidar scattering from clouds at 347 nm and 694 nm.

    PubMed

    Pal, S R; Carswell, A I

    1978-08-01

    The polarization characteristics of lidar scattering from cumulus and low-lying shower clouds have been measured with a system operating at 694 nm (red) and 347 nm (blue). The backscatter profiles of the polarization components as well as of the total intensity of the return are presented and discussed for the two wavelengths. The linear depolarization ratio delta, which can be used as a measure of the unpolarized multiple scattering, has been obtained at both wavelengths. This quantity has a very low value at cloud base for both wavelengths and increases with pulse penetration. The blue registers generally higher values of a within the cloud. The measured total intensity backscatter functions for both wavelengths are presented and discussed in relation to theoretical calculations of cloud models.

  7. Optical breakdown threshold investigation of 1064 nm laser induced air plasmas

    SciTech Connect

    Thiyagarajan, Magesh; Thompson, Shane

    2012-04-01

    We present the theoretical and experimental measurements and analysis of the optical breakdown threshold for dry air by 1064 nm infrared laser radiation and the significance of the multiphoton and collisional cascade ionization process on the breakdown threshold measurements over pressures range from 10 to 2000 Torr. Theoretical estimates of the breakdown threshold laser intensities and electric fields are obtained using two distinct theories namely multiphoton and collisional cascade ionization theories. The theoretical estimates are validated by experimental measurements and analysis of laser induced breakdown processes in dry air at a wavelength of 1064 nm by focusing 450 mJ max, 6 ns, 75 MW max high-power 1064 nm IR laser radiation onto a 20 {mu}m radius spot size that produces laser intensities up to 3 - 6 TW/cm{sup 2}, sufficient for air ionization over the pressures of interest ranging from 10 to 2000 Torr. Analysis of the measured breakdown threshold laser intensities and electric fields are carried out in relation with classical and quantum theoretical ionization processes, operating pressures. Comparative analysis of the laser air breakdown results at 1064 nm with corresponding results of a shorter laser wavelength (193 nm) [M. Thiyagarajan and J. E. Scharer, IEEE Trans. Plasma Sci. 36, 2512 (2008)] and a longer microwave wavelength (10{sup 8} nm) [A. D. MacDonald, Microwave Breakdown in Gases (Wiley, New York, 1966)]. A universal scaling analysis of the breakdown threshold measurements provided a direct comparison of breakdown threshold values over a wide range of frequencies ranging from microwave to ultraviolet frequencies. Comparison of 1064 nm laser induced effective field intensities for air breakdown measurements with data calculated based on the collisional cascade and multiphoton breakdown theories is used successfully to determine the scaled collisional microwave portion. The measured breakdown threshold of 1064 nm laser intensities are then

  8. Analysis of multi-mode to single-mode conversion at 635 nm and 1550 nm

    NASA Astrophysics Data System (ADS)

    Zamora, Vanessa; Bogatzki, Angelina; Arndt-Staufenbiel, Norbert; Hofmann, Jens; Schröder, Henning

    2016-03-01

    We propose two low-cost and robust optical fiber systems based on the photonic lantern (PL) technology for operating at 635 nm and 1550 nm. The PL is an emerging technology that couples light from a multi-mode (MM) fiber to several single-mode (SM) fibers via a low-loss adiabatic transition. This bundle of SM fibers is observed as a MM fiber system whose spatial modes are the degenerate supermodes of the bundle. The adiabatic transition allows that those supermodes evolve into the modes of the MM fiber. Simulations of the MM fiber end structure and its taper transition have been performed via functional mode solver tools in order to understand the modal evolution in PLs. The modelled design consists of 7 SM fibers inserted into a low-index capillary. The material and geometry of the PLs are chosen such that the supermodes match to the spatial modes of the desired step-index MM fiber in a moderate loss transmission. The dispersion of materials is also considered. These parameters are studied in two PL systems in order to reach a spectral transmission from 450 nm to 1600 nm. Additionally, an analysis of the geometry and losses due to the mismatching of modes is presented. PLs are typically used in the fields of astrophotonics and space photonics. Recently, they are demonstrated as mode converters in telecommunications, especially focusing on spatial division multiplexing. In this study, we show the use of PLs as a promising interconnecting tool for the development of miniaturized spectrometers operating in a broad wavelength range.

  9. TUNABLE DIODE LASER MEASUREMENTS OF NO2 NEAR 670 NM AND 395 NM. (R823933)

    EPA Science Inventory

    Two single-mode diode lasers were used to record high-resolution absorption spectra of NO2 (dilute in Ar) near 670.2 and 394.5 nm over a range of temperatures (296 to 774 K) and total pressures (2.4 x 10(-2) to 1 atm). A commercial InGaAsP laser was tuned 1.3 cm(-1) at a repetiti...

  10. Performance comparison of bismuth/erbium co-doped optical fibre by 830 nm and 980 nm pumping

    NASA Astrophysics Data System (ADS)

    Yan, Binbin; Luo, Yanhua; Zareanborji, Amirhassan; Xiao, Gui; Peng, Gang-Ding; Wen, Jianxiang

    2016-10-01

    The performance of bismuth/erbium co-doped fibre (BEDF) by 830 nm and 980 nm pumping has been studied in detail, including the small signal absorption, pump absorption, emission, gain and excited state absorption (ESA). Based on the study, energy transition diagrams of BEDF under 830 nm or 980 nm pumping are proposed to clarify the spectroscopic properties. The results demonstrate the advantages of 830 nm pumping for BEDF over 980 nm pumping when considering the absorption, pumping efficiency, excited state absorption and optical amplification.

  11. Electron-induced single event upsets in 28 nm and 45 nm bulk SRAMs

    DOE PAGES

    Trippe, J. M.; Reed, R. A.; Austin, R. A.; Sierawski, B. D.; Weller, R. A.; Funkhouser, E. D.; King, M. P.; Narasimham, B.; Bartz, B.; Baumann, R.; et al

    2015-12-01

    In this study, we present experimental evidence of single electron-induced upsets in commercial 28 nm and 45 nm CMOS SRAMs from a monoenergetic electron beam. Upsets were observed in both technology nodes when the SRAM was operated in a low power state. The experimental cross section depends strongly on both bias and technology node feature size, consistent with previous work in which SRAMs were irradiated with low energy muons and protons. Accompanying simulations demonstrate that δ-rays produced by the primary electrons are responsible for the observed upsets. Additional simulations predict the on-orbit event rates for various Earth and Jovian environmentsmore » for a set of sensitive volumes representative of current technology nodes. The electron contribution to the total upset rate for Earth environments is significant for critical charges as high as 0.2 fC. This value is comparable to that of sub-22 nm bulk SRAMs. Similarly, for the Jovian environment, the electron-induced upset rate is larger than the proton-induced upset rate for critical charges as high as 0.3 fC.« less

  12. Electron-induced single event upsets in 28 nm and 45 nm bulk SRAMs

    SciTech Connect

    Trippe, J. M.; Reed, R. A.; Austin, R. A.; Sierawski, B. D.; Weller, R. A.; Funkhouser, E. D.; King, M. P.; Narasimham, B.; Bartz, B.; Baumann, R.; Schrimpf, R. D.; Labello, R.; Nichols, J.; Weeden-Wright, S. L.

    2015-12-01

    In this study, we present experimental evidence of single electron-induced upsets in commercial 28 nm and 45 nm CMOS SRAMs from a monoenergetic electron beam. Upsets were observed in both technology nodes when the SRAM was operated in a low power state. The experimental cross section depends strongly on both bias and technology node feature size, consistent with previous work in which SRAMs were irradiated with low energy muons and protons. Accompanying simulations demonstrate that δ-rays produced by the primary electrons are responsible for the observed upsets. Additional simulations predict the on-orbit event rates for various Earth and Jovian environments for a set of sensitive volumes representative of current technology nodes. The electron contribution to the total upset rate for Earth environments is significant for critical charges as high as 0.2 fC. This value is comparable to that of sub-22 nm bulk SRAMs. Similarly, for the Jovian environment, the electron-induced upset rate is larger than the proton-induced upset rate for critical charges as high as 0.3 fC.

  13. Improved performance 1590 nm Er:YLF laser

    SciTech Connect

    Marchbanks, R.D.; Petrin, R.R.; Cockroft, N.J.

    1994-12-01

    We present an improvement in the performance of a 1590 nm ER:YLF laser through simultaneous laser operation at 2717 nm. A slope efficiency of 7.0% with an output of 13.2 mW has been achieved with 971 nm pumping.

  14. Method for radiation detection and measurement

    DOEpatents

    Miller, S.D.

    1993-12-21

    Dose of radiation to which a body of crystalline material has been exposed is measured by exposing the body to optical radiation at a first wavelength, which is greater than about 540 nm, and measuring optical energy emitted from the body by luminescence at a second wavelength, which is longer than the first wavelength. 9 figures.

  15. Method for radiation detection and measurement

    DOEpatents

    Miller, Steven D.

    1993-01-01

    Dose of radiation to which a body of crystalline material has been exposed is measured by exposing the body to optical radiation at a first wavelength, which is greater than about 540 nm, and measuring optical energy emitted from the body by luminescence at a second wavelength, which is longer than the first wavelength.

  16. EUV light source with high brightness at 13.5 nm

    SciTech Connect

    Borisov, V M; Prokof'ev, A V; Khristoforov, O B; Koshelev, K N; Khadzhiyskiy, F Yu

    2014-11-30

    The results of the studies on the development of a highbrightness radiation source in the extreme ultraviolet (EUV) range are presented. The source is intended for using in projection EUV lithography, EUV mask inspection, for the EUV metrology, etc. Novel approaches to creating a light source on the basis of Z-pinch in xenon allowed the maximal brightness [130 W(mm{sup 2} sr){sup -1}] to be achieved in the vicinity of plasma for this type of radiation sources within the 2% spectral band centred at the wavelength of 13.5 nm that corresponds to the maximal reflection of multilayer Mo/Si mirrors. In this spectral band the radiation power achieves 190 W in the solid angle of 2π at a pulse repetition rate of 1.9 kHz and an electric power of 20 kW, injected into the discharge. (laser applications and other topics in quantum electronics)

  17. Continuous-wave simultaneous dual-wavelength operation at 912 nm and 1063 nm in Nd:GdVO4

    NASA Astrophysics Data System (ADS)

    Lünstedt, K.; Pavel, N.; Petermann, K.; Huber, G.

    2007-01-01

    A continuous-wave, diode-pumped Nd:GdVO4 thin disk laser with simultaneous dual-wavelength emission at the 912 nm 4 F 3/2→4 I 9/2 quasi-three-level transition and the 1063 nm 4 F 3/2→4 I 11/2 four-level transition is demonstrated and analyzed. Output powers of 1.7 W at 912 nm and of 1.6 W at 1063 nm were achieved simultaneously from a 0.3-at.%, 300-μm thick Nd:GdVO4 crystal that was multi-pass excited with 26.8 W of available diode pump power. Second harmonic generation to 456 nm with LiB3O5 yielded 0.96 W in 912 nm single-wavelength operation and 0.73 W in 912 nm/1063 nm dual-wavelength operation.

  18. UV 380 nm Reflectivity of the Earth's Surface

    NASA Technical Reports Server (NTRS)

    Herman, J. R.; Celarier, E.; Larko, D.

    2000-01-01

    The 380 nm radiance measurements of TOMS (Total Ozone Mapping Spectrometer) have been converted into a global data set of daily (1979 to 1992) Lambert equivalent reflectivities R of the Earth's surface and boundary layer (clouds, aerosols, surface haze, and snow/ice). Since UV surface reflectivity is between 2 and 8% for both land and water during all seasons of the year (except for ice and snow cover), reflectivities larger than the surface value indicates the presence of clouds, haze, or aerosols in the satellite field of view. Statistical analysis of 14 years of daily data show that most snow/ice-free regions of the Earth have their largest fraction of days each year when the reflectivity is low (R less than 10%). The 380 nm reflectivity data shows that the true surface reflectivity is 2 to 3% lower than the most frequently occurring reflectivity value for each TOMS scene. The most likely cause of this could be a combination of frequently occurring boundary-layer water or aerosol haze. For most regions, the observation of extremely clear conditions needed to estimate the surface reflectivity from space is a comparatively rare occurrence. Certain areas (e.g., Australia, southern Africa, portions of northern Africa) are cloud-free more than 80% of the year, which exposes these regions to larger amounts of UV radiation than at comparable latitudes in the Northern Hemisphere. Regions over rain-forests, jungle areas, Europe and Russia, the bands surrounding the Arctic and Antarctic regions, and many ocean areas have significant cloud cover (R greater than 15%) more than half of each year. In the low to middle latitudes, the areas with the heaviest cloud cover (highest reflectivity for most of the year) are the forest areas of northern South America, southern Central America, the jungle areas of equatorial Africa, and high mountain regions such as the Himalayas or the Andes. The TOMS reflectivity data show the presence of large nearly clear ocean areas and the effects

  19. From the nm to the Mm

    NASA Astrophysics Data System (ADS)

    Villa, I. M.

    2003-12-01

    Tectonic models for the evolution of an orogen start at the Mm scale, and use field work on smaller subunits at the km scale and rocks collected at the m scale. At the mm scale, minerals are identified, analyzed by mass spectrometry, their "cooling ages" assigned to a specific closure temperature, a cooling rate attributed to a particular tectonic regime, and a large body of self-referential literature is the product of an oiled machinery. Problems become apparent if one attempts to harmonize mm-scale science with the nasty little details at even smaller scales. Atoms are invisible to the naked eye (unlike the minerals mentioned above) and their actual behavior is, or was, only accessible to indirect argumentations and simplified calculations. Increased computing power now allows calculating the transport of atoms in a crystal from the Schr”dinger equation: results do not fit 19th century continuum physics for infinitely dilute solutions (Fick's and Arrhenius' "laws"). Moreover, improved nanochemical analyses allow characterizing the supposedly homogeneous mineral matrix. TEM images show how layers or chains in pristine minerals are substituted in a non-periodic way by alteration products. EMP analyses show the almost ubiquitous presence of razor-sharp boundaries rather than Erf profiles. Disequilibrium recrystallization textures thus prevail over diffusive reequilibration; diffusion sensu stricto is shown to be a much slower process than heterochemical replacement. Alterability sequences are well known to surface scientists: e.g. halite, olivine, biotite, muscovite, zircon. Such sequences are reflected in the isotopic retentivity. The link only becomes clear at the nm scale: isotopic exchange occurs during the replacement reactions that affect all rocks on their retrograde P-T evolution. This is sufficient to explain why zircons record higher isotopic ages than muscovites, which in turn undergo less isotope exchange than biotites etc. While there is a vague

  20. Space Radiation

    NASA Technical Reports Server (NTRS)

    Wu, Honglu

    2006-01-01

    Astronauts receive the highest occupational radiation exposure. Effective protections are needed to ensure the safety of astronauts on long duration space missions. Increased cancer morbidity or mortality risk in astronauts may be caused by occupational radiation exposure. Acute and late radiation damage to the central nervous system (CNS) may lead to changes in motor function and behavior, or neurological disorders. Radiation exposure may result in degenerative tissue diseases (non-cancer or non-CNS) such as cardiac, circulatory, or digestive diseases, as well as cataracts. Acute radiation syndromes may occur due to occupational radiation exposure.

  1. Effects of radiation on laser diodes.

    SciTech Connect

    Phifer, Carol Celeste

    2004-09-01

    The effects of ionizing and neutron radiation on the characteristics and performance of laser diodes are reviewed, and the formation mechanisms for nonradiative recombination centers, the primary type of radiation damage in laser diodes, are discussed. Additional topics include the detrimental effects of aluminum in the active (lasing) volume, the transient effects of high-dose-rate pulses of ionizing radiation, and a summary of ways to improve the radiation hardness of laser diodes. Radiation effects on laser diodes emitting in the wavelength region around 808 nm are emphasized.

  2. On Helium 1083 nm Line Polarization during the Impulsive Phase of an X1 Flare

    NASA Astrophysics Data System (ADS)

    Judge, Philip G.; Kleint, Lucia; Sainz Dalda, Alberto

    2015-12-01

    We analyze spectropolarimetric data of the He i 1083 nm multiplet (1s2s{}3{S}1-1s2p{}3{P}2,1,0o) during the X1 flare SOL2014-03-29T17:48, obtained with the Facility Infrared Spectrometer (FIRS) at the Dunn Solar Telescope. While scanning active region NOAA 12017, the FIRS slit crossed a flare ribbon during the impulsive phase, when the helium line intensities turned into emission at ≲twice the continuum intensity. Their linear polarization profiles are of the same sign across the multiplet including 1082.9 nm, intensity-like, at ≲5% of the continuum intensity. Weaker Zeeman-induced linear polarization is also observed. Only the strongest linear polarization coincides with hard X-ray (HXR) emission at 30-70 keV observed by RHESSI. The polarization is generally more extended and lasts longer than the HXR emission. The upper J = 0 level of the 1082.9 nm component is unpolarizable thus, lower-level polarization is the culprit. We make non-LTE radiative transfer calculations in thermal slabs optimized to fit only intensities. The linear polarizations are naturally reproduced, through a systematic change of sign with wavelength of the radiation anisotropy when slab optical depths of the 1082.9 component are ≲1. Neither are collisions with beams of particles needed, nor can they produce the same sign of polarization of the 1082.9 and 1083.0 nm components. The He i line polarization merely requires heating sufficient to produce slabs of the required thickness. Widely different polarizations of Hα, reported previously, are explained by different radiative anisotropies arising from slabs of different optical depths.

  3. Interference patterning of gratings with a period of 150 nm at a wavelength of 157 nm

    NASA Astrophysics Data System (ADS)

    Fuetterer, Gerald; Herbst, Waltraud; Rottstegge, Joerg; Ferstl, Margit; Sebald, Michael; Schwider, Johannes

    2002-07-01

    A system producing an optical pattern with a high spatial frequency at (lambda) equals 157 nm has been built to be used as a photoresist tool for the 157 nm lithography. In order to generate a test pattern with a high spatial frequency, two-beam interference was used to overcome the limits of existing mask-projection systems using numerical apertures up to 0.65. In order to work without phase lock techniques a e-beam phase grating was used for providing the two interfering wave fronts for the generation of 150 nm-structures. The phase grating is illuminated under the Bragg-angle. Only two diffraction orders propagate and the other orders are evanescent. The interference pattern resulting in the region of the overlap of the propagated orders is a true two-beam pattern of the same period as the e-beam mask. The photoresist coated wafer is placed in the plane of the interference pattern and is rigidly held by a mechanical fixture. The contrast of the interference pattern depends on the degree of spatial coherence of the excimer laser, on the coherence length, the polarization state of the beam used to illuminate the surface relief phase grating, and on the distance between the wafer and the surface relief phase grating. The degree of spatial coherence was increased by a restriction of the plane wave spectrum which has been attained at the cost of energy throughput. In addition, the TM-polarization was blocked. This was done by a polarizer and a spatial filter. The theoretical background of the experiment will be discussed as well as practical problems.

  4. Quantifying the inversion accuracy of simplified physical models for the nighttime OI 135.6 nm emission

    NASA Astrophysics Data System (ADS)

    Qin, Jianqi; Kamalabadi, Farzad; Makela, Jonathan J.

    2016-06-01

    A comprehensive statistical analysis is performed to investigate the effects of plasma and neutral density variability on the OI 135.6 nm emission in the nighttime ionosphere. Typical and extreme cases obtained from climatological models are incorporated into a radiative transfer model recently developed by Qin et al. (2015) to systematically quantify the production and loss of the nighttime 135.6 nm emission, as well as to understand their dependence on the ionospheric and thermospheric conditions. It is shown that mutual neutralization can contribute ˜8%-40% of the 135.6 nm emission. Radiative transfer effects due to scattering and absorption reduce the peak brightness measured from a satellite platform in the limb direction by ˜0.3% to 22%. The reduction is more significant for a larger observing zenith angle, typically by ˜45% for lines of sight that go through altitudes below ˜150 km. Furthermore, inversion results show that ignoring radiative transfer effects lead to a maximum ˜12% underestimation of the NmF2, while ignoring mutual neutralization leads to a maximum ˜30% overestimation of the NmF2. In the presence of measurement noise, the estimation accuracy decreases with a decreasing signal-to-noise ratio, and the errors introduced by simplified physical models lead to a significant bias in the inversion results.

  5. An efficient continuous-wave 591 nm light source based on sum-frequency mixing of a diode pumped Nd:GdVO4-Nd:CNGG laser

    NASA Astrophysics Data System (ADS)

    Zhao, Y. D.; Liu, J. H.

    2013-08-01

    We report a laser architecture to obtain continuous-wave (CW) yellow-orange light sources at the 591 nm wavelength. An 808 nm diode pumped a Nd:GdVO4 crystal emitting at 1063 nm. A part of the pump power was then absorbed by the Nd:CNGG crystal. The remaining pump power was used to pump a Nd:CNGG crystal emitting at 1329 nm. Intracavity sum-frequency mixing at 1063 and 1329 nm was then realized in a LiB3O5 (LBO) crystal to reach the yellow-orange radiation. We obtained a CW output power of 494 mW at 591 nm with a pump laser diode emitting 17.8 W at 808 nm.

  6. SASE free electron lasers as short wavelength coherent sources. From first results at 100 nm to a 1 Å X-ray laser

    NASA Astrophysics Data System (ADS)

    Treusch, R.; Feldhaus, J.

    2003-10-01

    During the last few years free electron lasers (FELs) based on self-amplified spontaneous emission (SASE) have been demonstrated at wavelengths of 12 μm [CITE], 830 nm [CITE], 530 nm [CITE] and 385 nm [CITE], and around 100 nm [CITE]. Recently, saturation has been observed in the vacuum ultraviolet (VUV) spectral region between 82 nm and 125 nm at the TESLA Test Facility (TTF) at DESY. The radiation pulses have been characterized with respect to pulse energy, statistical fluctuations, angular divergence and spectral distribution, both in the linear gain and in the saturation regime of the FEL [CITE]. The results are in good agreement with theoretical simulations, providing a solid basis for other projects aiming at still shorter wavelengths down to the 0.1 nm range [CITE].

  7. Row orientation effect on UV-B, UV-A and PAR solar irradiation components in vineyards at Tuscany, Italy

    NASA Astrophysics Data System (ADS)

    Grifoni, D.; Carreras, G.; Zipoli, G.; Sabatini, F.; Dalla Marta, A.; Orlandini, S.

    2008-11-01

    Besides playing an essential role in plant photosynthesis, solar radiation is also involved in many other important biological processes. In particular, it has been demonstrated that ultraviolet (UV) solar radiation plays a relevant role in grapevines ( Vitis vinifera) in the production of certain important chemical compounds directly responsible for yield and wine quality. Moreover, the exposure to UV-B radiation (280-320 nm) can affect plant-disease interaction by influencing the behaviour of both pathogen and host. The main objective of this research was to characterise the solar radiative regime of a vineyard, in terms of photosynthetically active radiation (PAR) and UV components. In this analysis, solar spectral UV irradiance components, broadband UV (280-400 nm), spectral UV-B and UV-A (320-400 nm), the biological effective UVBE, as well as the PAR (400-700 nm) component, were all considered. The diurnal patterns of these quantities and the UV-B/PAR and UV-B/UV-A ratios were analysed to investigate the effect of row orientation of the vineyard in combination with solar azimuth and elevation angles. The distribution of PAR and UV irradiance at various heights of the vertical sides of the rows was also studied. The results showed that the highest portion of plants received higher levels of daily radiation, especially the UV-B component. Row orientation of the vines had a pronounced effect on the global PAR received by the two sides of the rows and, to a lesser extent, UV-A and UV-B. When only the diffused component was considered, this geometrical effect was greatly attenuated. UV-B/PAR and UV-A/PAR ratios were also affected, with potential consequences on physiological processes. Because of the high diffusive capacity of the UV-B radiation, the UV-B/PAR ratio was significantly lower on the plant portions exposed to full sunlight than on those in the shade.

  8. High performance spectrograph for solar UV 250-400 band

    NASA Astrophysics Data System (ADS)

    Di Menno, I.; Rafanelli, C.; De Simone, S.; Di Menno, M.

    2007-09-01

    The solar electromagnetic radiation flux is one of the important factors to evaluate the energy balance of the planet. It is important in the studies on the properties of the atmosphere and its components as AOD, on the energy requirements for anthropogenic activities as agriculture, industry and so on. The ever-increasing interest about the effects on the biosphere as consequence of anthropogenic activities has contributed to develop further studies about the solar radiation and in particular the UV band, 280-320 nm. The consequence has been a growing of instrumental site and radiometric networks. Many decisions affecting on civil society are taken using the data of these nets and consequently it is very important to study the effect of the environmental factors on the instrument output. The classical electromechanical equipments have good sensibility and resolution but their handicap is the time of the measure, generally some minutes. In this time, the sun is moved and the clouds in the sky too. The new generation of spectrometer based on solid state technology avoid the long time measurements. The paper show a new radiograph (fast spectroradiometer) for solar UV band 250-400 nm. It is based on CCD array and optical fiber. The performance are compared with a Brewer spectrophotometer during a comparison campaign close to Rome, Italy.

  9. 9nm node wafer defect inspection using three-dimensional scanning, a 405nm diode laser, and a broadband source

    NASA Astrophysics Data System (ADS)

    Zhou, Renjie; Edwards, Chris; Bryniarski, Casey A.; Popescu, Gabriel; Goddard, Lynford L.

    2015-03-01

    We recently built a 405nm laser based optical interferometry system for 9nm node patterned wafer defect inspection. Defects with volumes smaller than 15nm by 90nm by 35nm have been detected. The success of defect detection relied on accurate mechanical scanning of the wafer and custom engineered image denoising post-processing. To further improve the detection sensitivity, we designed a higher precision XYZ scanning stage and replaced the laser source with an incoherent LED to remove the speckle noise. With these system modifications, we successfully detected both defects and surface contamination particles in bright-field imaging mode. Recently, we have upgraded this system for interferometric defect inspection.

  10. Polymer and Material Design for Lithography From 50 nm Node to the sub-16 nm Node

    NASA Astrophysics Data System (ADS)

    Trefonas, Peter

    2012-02-01

    Microlithography is one of the technologies which enabled the Information Age. Developing at the intersection of optical physics, polymer science and photochemistry, the need for ever smaller high fidelity patterns to build integrated circuits is currently pushing the technology evolution from 193 nm immersion lithography to extreme ultraviolet lithography (13.5 nm) to alternate patterning technologies such as directed self assembly (DSA) of block copolymers. Essential to the success of this progression is a rapid application of new concepts and materials in polymer science. We will discuss the requirements for 193 immersion lithography and how advanced acrylic random polymers are being designed with chemical amplification functionality to meet these needs. The special requirements of a water immersion lithography led to the invention and rapid commercial application of surface assembled embedded barrier layer polymers. Design of polymers for EUV lithography is having to respond to much different challenges, prominent being the dearth of photons in the exposure step, and the other being how to maximize the efficiency of photoacid production. In parallel, alternative lithographic approaches are being developed using directed self assembly of block copolymers which realize pattern frequency multiplication. We will update with our progress in the applications of polymers designed for DSA.

  11. Radiation Exposure

    MedlinePlus

    Radiation is energy that travels in the form of waves or high-speed particles. It occurs naturally in sunlight. Man-made radiation is used in X-rays, nuclear weapons, nuclear power plants and cancer treatment. If you are exposed to small amounts of radiation over a ...

  12. Complementary UV-absorption of mycosporine-like amino acids and scytonemin is responsible for the UV-insensitivity of photosynthesis in Nostoc flagelliforme.

    PubMed

    Ferroni, Lorenzo; Klisch, Manfred; Pancaldi, Simonetta; Häder, Donat-Peter

    2010-01-20

    Mycosporine-like amino acids (MAAs) and scytonemin are UV-screening compounds that have presumably appeared early in the history of life and are widespread in cyanobacteria. Natural colonies of the UV-insensitive Nostoc flagelliforme were found to be especially rich in MAAs (32.1 mg g DW(-1)), concentrated in the glycan sheath together with scytonemin. MAAs are present in the form of oligosaccharide-linked molecules. Photosystem II activity, measured using PAM fluorescence and oxygen evolution, was used as a most sensitive physiological parameter to analyse the effectiveness of UV-protection. Laboratory experiments were performed under controlled conditions with a simulated solar radiation specifically deprived of UV-wavebands with cut-off filters (295, 305, 320, 345 and 395 nm). The UV-insensitivity of N. flagelliforme was found to cover the whole UV-A (315-400 nm) and UV-B (280-320 nm) range and is almost certainly due to the complementary UV-absorption of MAAs and scytonemin. The experimental approach used is proposed to be suitable for the comparison of the UV-protection ability in organisms that differ in their complement of UV-sunscreen compounds. Furthermore, this study performed with a genuinely terrestrial organism points to the relevance of marine photoprotective compounds for life on Earth, especially for the colonization of terrestrial environments.

  13. Ultraviolet A (320-400 nm) modulation of ultraviolet B (290-320 nm)-induced immune suppression is mediated by carbon monoxide.

    PubMed

    Allanson, Munif; Reeve, Vivienne E

    2005-03-01

    Accumulating evidence suggests that suberythemogenic ultraviolet A (UVA) (320-400 nm) exposure protects against the immunosuppressive effect of ultraviolet B (290-320 nm) radiation or its epidermal photoproduct, cis-urocanic acid (cis-UCA). In skin, UVA photoimmunoprotection is mediated by the inducible antioxidant stress enzyme, heme oxygenase-1 (HO-1), which degrades heme into carbon monoxide (CO), iron, and biliverdin (reduced to bilirubin), and is important for cell survival under conditions of oxidative stress. The identity of the HO enzymatic product(s) that provide the immunoprotection is unknown. Here we examine the potential of CO to fulfill this role in hairless mouse skin, utilizing a novel CO-releasing molecule (CO-RM) to deliver CO to the skin topically. The CO-RM released CO gradually from the lotion vehicle during 3 h following its preparation, and between 50 and 500 microM, concentration-dependently protected mice against the suppression of contact hypersensitivity by either solar-simulated UV radiation (SSUVR) or cis-UCA, whereas aged CO-depleted CO-RM was inactive. Thus, the CO-RM treatment mimicked UVA-photoimmunoprotection, and identified HO-released CO as the protective mediator, providing evidence that the murine cutaneous immune system is modulated by this gaseous messenger. Preliminary evidence for involvement of guanylyl cyclase was obtained by treatment of the mouse with its specific inhibitor 1H-(1,2,4)oxadiazolo-(4,3-1)quinoxaline-1-one, which abrogated UVA photoimmunoprotection.

  14. Comparison between HMME mediated photodynamic therapy using 413nm and 532nm for port wine stains: a mathematical simulation study

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Gu, Y.; Chen, R.; Xu, L. Q.; Liao, X. H.; Huang, N. Y.; Wang, Y. Y.

    2007-11-01

    Introduction: As it is always difficult to find the optimal combination of photosensitizer and of laser wavelength to achieve selective vascular damage in PWS-PDT, the selective vascular effects of HMME (Hematoporphyrin monomethyl ether) mediated PDT with 413 nm and with 532 nm were compared by mathematical simulation in this study. Materials & Methods: Firstly, distribution of 413 nm, 532 nm light in PWS tissue was simulated by Monte Carlo model. Two energy density groups were set, one is 80mW/cm2x40min for both 413 nm and 532 nm, the other is 80mW/cm2x40min for 532 nm while 80mW/cm2x20min in for 413 nm. Secondly, the productivity of reactive oxygen species (ROS) in target vessels and normal tissue were simulated using a simulation system for PDT of PWS established in our lab, which considering the amount of light and photosensitizer in tissue, the molar extinction coefficient of photosensitizer, and quantum yield of ROS. Concentration of HMME for each wavelength were same. Finally, the productivity of ROS n in target vessels and normal tissue were compared between 413 nm PDT and 532 nm PDT under different energy density. Result: Under the same energy density, ROS productivity in target vessels of 413 nm PDT was significantly higher than that of 532 nm PDT. Moreover, it was still higher at low energy density than that of 532nm PDT with high energy density. Conclusion: HMME mediated PDT using 413 nm has the potential to increase the selective vascular effect of PDT for PWS by shortening treatment time.

  15. Radiation in controlled environments: influence of lamp type and filter material

    NASA Technical Reports Server (NTRS)

    Bubenheim, D. L.; Bugbee, B.; Salisbury, F. B.

    1988-01-01

    Radiation in controlled environments was characterized using fluorescent and various high-intensity-discharge (HID) lamps, including metal halide, low-pressure sodium, and high-pressure sodium as the radiation source. The effects of water, glass, or Plexiglas filters on radiation were determined. Photosynthetic photon flux (PPF, 400 to 700 nm), spectra (400 to 1000 nm), shortwave radiation (285-2800 nm), and total radiation (300 to 100,000 nm) were measured, and photosynthetically active radiation (PAR, 400 to 700 nm) and longwave radiation (2800 to 100,000 nm) were calculated. Measurement of PPF alone was not an adequate characterization of the radiation environment. Total radiant flux varied among lamp types at equal PPF. HID lamps provided a lower percentage of longwave radiation than fluorescent lamps, but, when HID lamps provided PPF levels greater than that possible with fluorescent lamps, the amount of longwave radiation was high. Water was the most effective longwave radiation filter. Glass and Plexiglas similarly filtered longwave more than shortwave radiation, but transmission of nonphotosynthetic shortwave radiation was less with Plexiglas than glass. The filter materials tested would not be expected to influence photomorphogenesis because radiation in the action spectrum of phytochrome was not altered, but this may not be the only pigment involved.

  16. The vegetative arctic freshwater green alga Zygnema is insensitive to experimental UV exposure.

    PubMed

    Holzinger, Andreas; Roleda, Michael Y; Lütz, Cornelius

    2009-12-01

    The physiological performance and ultrastructural integrity of the vegetative freshwater green alga Zygnema sp., growing under ambient polar day solar radiation and after exposure to experimentally low radiation, but with high UVR:PAR ratio were investigated. In the laboratory, algae were exposed to low photosynthetic active radiation (PAR=P, 400-700 nm, 20 micromol m(-2) s(-1)), PAR + UV-A = PA (320-400 nm, 4.00 W m(-2) = UV-A) and PAR + UV-A + UV-B = PAB (280-320 nm, 0.42 W m(-2) = UV-B) for 24 h at 7 degrees C. Photosynthetic performance and ultrastructure of ambient solar radiation-exposed (field control) and experimentally treated Zygnema samples were assessed using chlorophyll fluorescence, and transmission electron microscopy (TEM). No significant treatment effect was observed in the photosynthesis-irradiance curve parameters. Exclusion of the UV-B spectrum in the laboratory treatment caused significantly lower effective photosynthetic quantum yield compared to samples exposed to the whole radiation spectrum. TEM revealed no obvious differences in the ultrastructure of field control and laboratory P-, PA- and PAB-exposed samples. Substantial amounts of lipid bodies, visualized by Sudan IV staining, were observed in all samples. Chloroplasts contained numerous plastoglobules. Organelles like mitochondria, Golgi bodies and the nucleus remained unaffected by the radiation exposures. Zygnema is well adapted to ambient solar radiation, enabling the alga to cope with experimental UV exposure and it is expected to persist in a scenario with enhanced UV radiation caused by stratospheric ozone depletion.

  17. Radiation Proctopathy

    PubMed Central

    Grodsky, Marc B.; Sidani, Shafik M.

    2015-01-01

    Radiation therapy is a widely utilized treatment modality for pelvic malignancies, including prostate cancer, rectal cancer, and cervical cancer. Given its fixed position in the pelvis, the rectum is at a high risk for injury secondary to ionizing radiation. Despite advances made in radiation science, up to 75% of the patients will suffer from acute radiation proctitis and up to 20% may experience chronic symptoms. Symptoms can be variable and include diarrhea, bleeding, incontinence, and fistulization. A multitude of treatment options exist. This article summarizes the latest knowledge relating to radiation proctopathy focusing on the vast array of treatment options. PMID:26034407

  18. Radiation proctopathy.

    PubMed

    Grodsky, Marc B; Sidani, Shafik M

    2015-06-01

    Radiation therapy is a widely utilized treatment modality for pelvic malignancies, including prostate cancer, rectal cancer, and cervical cancer. Given its fixed position in the pelvis, the rectum is at a high risk for injury secondary to ionizing radiation. Despite advances made in radiation science, up to 75% of the patients will suffer from acute radiation proctitis and up to 20% may experience chronic symptoms. Symptoms can be variable and include diarrhea, bleeding, incontinence, and fistulization. A multitude of treatment options exist. This article summarizes the latest knowledge relating to radiation proctopathy focusing on the vast array of treatment options. PMID:26034407

  19. 9nm node wafer defect inspection using visible light

    NASA Astrophysics Data System (ADS)

    Zhou, Renjie; Edwards, Chris; Popescu, Gabriel; Goddard, Lynford L.

    2014-04-01

    Over the past 2 years, we have developed a common optical-path, 532 nm laser epi-illumination diffraction phase microscope (epi-DPM) and successfully applied it to detect different types of defects down to 20 by 100 nm in a 22nm node intentional defect array (IDA) wafer. An image post-processing method called 2DISC, using image frame 2nd order differential, image stitching, and convolution, was used to significantly improve sensitivity of the measured images. To address 9nm node IDA wafer inspection, we updated our system with a highly stable 405 nm diode laser. By using the 2DISC method, we detected parallel bridge defects in the 9nm node wafer. To further enhance detectability, we are exploring 3D wafer scanning, white-light illumination, and dark-field inspection.

  20. Segmentation of the macular choroid in OCT images acquired at 830nm and 1060nm

    NASA Astrophysics Data System (ADS)

    Lee, Sieun; Beg, Mirza F.; Sarunic, Marinko V.

    2013-06-01

    Retinal imaging with optical coherence tomography (OCT) has rapidly advanced in ophthalmic applications with the broad availability of Fourier domain (FD) technology in commercial systems. The high sensitivity afforded by FD-OCT has enabled imaging of the choroid, a layer of blood vessels serving the outer retina. Improved visualization of the choroid and the choroid-sclera boundary has been investigated using techniques such as enhanced depth imaging (EDI), and also with OCT systems operating in the 1060-nm wavelength range. We report on a comparison of imaging the macular choroid with commercial and prototype OCT systems, and present automated 3D segmentation of the choroid-scleral layer using a graph cut algorithm. The thickness of the choroid is an important measurement to investigate for possible correlation with severity, or possibly early diagnosis, of diseases such as age-related macular degeneration.

  1. UV-Induced cell death in plants.

    PubMed

    Nawkar, Ganesh M; Maibam, Punyakishore; Park, Jung Hoon; Sahi, Vaidurya Pratap; Lee, Sang Yeol; Kang, Chang Ho

    2013-01-14

    Plants are photosynthetic organisms that depend on sunlight for energy. Plants respond to light through different photoreceptors and show photomorphogenic development. Apart from Photosynthetically Active Radiation (PAR; 400-700 nm), plants are exposed to UV light, which is comprised of UV-C (below 280 nm), UV-B (280-320 nm) and UV-A (320-390 nm). The atmospheric ozone layer protects UV-C radiation from reaching earth while the UVR8 protein acts as a receptor for UV-B radiation. Low levels of UV-B exposure initiate signaling through UVR8 and induce secondary metabolite genes involved in protection against UV while higher dosages are very detrimental to plants. It has also been reported that genes involved in MAPK cascade help the plant in providing tolerance against UV radiation. The important targets of UV radiation in plant cells are DNA, lipids and proteins and also vital processes such as photosynthesis. Recent studies showed that, in response to UV radiation, mitochondria and chloroplasts produce a reactive oxygen species (ROS). Arabidopsis metacaspase-8 (AtMC8) is induced in response to oxidative stress caused by ROS, which acts downstream of the radical induced cell death (AtRCD1) gene making plants vulnerable to cell death. The studies on salicylic and jasmonic acid signaling mutants revealed that SA and JA regulate the ROS level and antagonize ROS mediated cell death. Recently, molecular studies have revealed genes involved in response to UV exposure, with respect to programmed cell death (PCD).

  2. Detection limits of 405 nm and 633 nm excited PpIX fluorescence for brain tumor detection during stereotactic biopsy

    NASA Astrophysics Data System (ADS)

    Markwardt, Niklas; Götz, Marcus; Haj-Hosseini, Neda; Hollnburger, Bastian; Sroka, Ronald; Stepp, Herbert; Zelenkov, Petr; Rühm, Adrian

    2016-04-01

    5-aminolevulinic-acid-(5-ALA)-induced protoporphyrin IX (PpIX) fluorescence may be used to improve stereotactic brain tumor biopsies. In this study, the sensitivity of PpIX-based tumor detection has been investigated for two potential excitation wavelengths (405 nm, 633 nm). Using a 200 μm fiber in contact with semi-infinite optical phantoms containing ink and Lipovenös, PpIX detection limits of 4.0 nM and 200 nM (relating to 1 mW excitation power) were determined for 405 nm and 633 nm excitation, respectively. Hence, typical PpIX concentrations in glioblastomas of a few μM should be well detectable with both wavelengths. Additionally, blood layers of selected thicknesses were placed between fiber and phantom. Red excitation was shown to be considerably less affected by blood interference: A 50 μm blood layer, for instance, blocked the 405- nm-excited fluorescence completely, but reduced the 633-nm-excited signal by less than 50%. Ray tracing simulations demonstrated that - without blood layer - the sensitivity advantage of 405 nm rises for decreasing fluorescent volume from 50-fold to a maximum of 100-fold. However, at a tumor volume of 1 mm3, which is a typical biopsy sample size, the 633-nm-excited fluorescence signal is only reduced by about 10%. Further simulations revealed that with increasing fiber-tumor distance, the signal drops faster for 405 nm. This reduces the risk of detecting tumor tissue outside the needle's coverage, but diminishes the overlap between optically and mechanically sampled volumes. While 405 nm generally offers a higher sensitivity, 633 nm is more sensitive to distant tumors and considerably superior in case of blood-covered tumor tissue.

  3. Self-frequency-doubled BaTeMo2O9 Raman laser emitting at 589 nm.

    PubMed

    Gao, Z L; Liu, S D; Zhang, J J; Zhang, S J; Zhang, W G; He, J L; Tao, X T

    2013-03-25

    In this paper, the spontaneous Raman spectra and second harmonic generation (SHG) properties at 589 nm of a novel Raman crystal BaTeMo(2)O(9) (BTM) were investigated. The BTM crystal was cut along the type-II SHG phase-matching direction for the first-order Raman shift at 1178 nm to realize the SRS and SHG simultaneously. Pumped by a nanosecond 1064 nm laser source, a self-frequency-doubled BTM Raman laser operating at 589 nm has been demonstrated for the first time. At the pump pulse energy of 48 mJ, the maximum yellow laser output pulse energy of 5.6 mJ was obtained with an optical-to-optical conversion efficiency of 11.7%. Our results show that BTM crystal is one of the promising candidate Raman materials to generate yellow laser radiation.

  4. 500.5-nm blue-green laser based on sum-frequency mixing of diode pumped neodymium lasers

    NASA Astrophysics Data System (ADS)

    Wang, S. F.; Na, Y. X.

    2011-07-01

    We report for the first time a continuous-wave (CW) coherent radiation at 500.5 nm by intracavity sum-frequency generation of 1063 nm Nd:GdVO4 laser and 946 nm Nd:YAG laser. Blue-green laser is obtained by using a doubly cavity, type-II critical phase matching KTiOPO4 (KTP) crystal sum-frequency mixing. With total pump power of 27.8 W, TEM00 mode blue-green laser at 500.5 nm of 421 mW is obtained. At the output power level of 421 mW, the blue-green power stability is better than 2.8% and laser beam quality M 2 factor is 1.37.

  5. Spectral emission properties of a LPP light source in the sub-200nm range for wafer inspection applications

    NASA Astrophysics Data System (ADS)

    Gambino, Nadia; Rollinger, Bob; Hudgins, Duane; Abhari, Reza; Abreau, F.

    2015-03-01

    In this work, the spectral emission proprieties of a droplet-based laser-produced plasma are investigated in the VUV range. These studies are performed with a spectrograph operating from 30 nm to 180 nm at a spectral resolution of 0.1 nm. The emission spectra are recorded for different droplet-based metal fuels such as tin, indium and gallium in the presence of different background gas pressure levels. The experimental results are relevant for alternative light sources that would be needed for future wafer inspection tools. In addition, the experimental results help to determine the Out- Of-Band (OOB) radiation emission of the EUV source. By tuning the type of fuel, the laser energies and the background gas, the LPP light source shows good capabilities to be operated as a tunable light source that covers a spectral emission range from the EUV to the sub-200 nm range.

  6. Joint Effect of Solar UVB and Heat Stress on the Seasonal Change of Egg Hatching Success in the Herbivorous False Spider Mite (Acari: Tenuipalpidae).

    PubMed

    Sudo, M; Osakabe, M

    2015-12-01

    Seasonal population dynamics of an herbivorous mite has been documented in terms of the relationship between thermoresponses and temporal biological factors such as resource availability or predation risk. Although recent studies emphasize the deleterious effects of solar ultraviolet-B (UVB; 280-320nm wavelengths) radiation on plant-dwelling mites, how UVB affects mite population remains largely unknown. On a wild shrub Viburnum erosum var. punctatum in Kyoto, an herbivorous false spider mite, Brevipalpus obovatus Donnadieu, occurs only in autumn. Females of this species lay one-third of their eggs on upper leaf surfaces. Oviposition on upper surfaces is beneficial for avoiding predation by phytoseiids, but exposes eggs to solar UVB and heat stress. To test the hypothesis that the seasonal occurrence of this mite is determined by interactions between solar UVB radiation and temperature, we examined variation in egg hatching success under near-ambient and UV-attenuated sunlight conditions from spring to autumn. The UV-attenuation significantly improved hatching success. However, most eggs died under heat stress regardless of UV treatments in July and August. We established a deterministic heat stress-cumulative UVB dose-egg hatching success response model, which we applied to meteorological data. The model analyses illustrated lower and higher survivability peaks in late May and October, respectively, which partly corresponded to data for annual field occurrence, indicating the importance of solar UVB radiation and heat stress as determinants of the seasonal occurrence of this mite.

  7. Effector and suppressor circuits of the immune response are activated in vivo by different mechanisms.

    PubMed

    Okamoto, H; Kripke, M L

    1987-06-01

    The application of fluorescein isothiocyanate (FITC) onto the skin of mice induces a contact hypersensitivity immune response. Lymph nodes draining the skin painted with FITC contain fluorescent cells that induce contact hypersensitivity to FITC when injected into normal mice. The antigen-presenting cells responsible for activating the effector pathway of the contact hypersensitivity response express Ia histocompatibility determinants and are resistant to inactivation with gamma-radiation. Exposing the skin to low doses of UV radiation (280-320 nm) before the application of FITC suppresses the contact hypersensitivity response to FITC. Cells present in the draining lymph nodes of these mice induce suppressor T lymphocytes when injected into normal recipients. The inducer cells in the draining lymph nodes are Thy 1+, Ia- and are inactivated by gamma-radiation. These studies demonstrate that different mechanisms are involved in the in vivo activation of effector and suppressor immune responses, and they suggest that the mode of initial antigen presentation determines which immunologic circuit will be activated in response to a contact-sensitizing antigen. PMID:2884661

  8. Joint Effect of Solar UVB and Heat Stress on the Seasonal Change of Egg Hatching Success in the Herbivorous False Spider Mite (Acari: Tenuipalpidae).

    PubMed

    Sudo, M; Osakabe, M

    2015-12-01

    Seasonal population dynamics of an herbivorous mite has been documented in terms of the relationship between thermoresponses and temporal biological factors such as resource availability or predation risk. Although recent studies emphasize the deleterious effects of solar ultraviolet-B (UVB; 280-320nm wavelengths) radiation on plant-dwelling mites, how UVB affects mite population remains largely unknown. On a wild shrub Viburnum erosum var. punctatum in Kyoto, an herbivorous false spider mite, Brevipalpus obovatus Donnadieu, occurs only in autumn. Females of this species lay one-third of their eggs on upper leaf surfaces. Oviposition on upper surfaces is beneficial for avoiding predation by phytoseiids, but exposes eggs to solar UVB and heat stress. To test the hypothesis that the seasonal occurrence of this mite is determined by interactions between solar UVB radiation and temperature, we examined variation in egg hatching success under near-ambient and UV-attenuated sunlight conditions from spring to autumn. The UV-attenuation significantly improved hatching success. However, most eggs died under heat stress regardless of UV treatments in July and August. We established a deterministic heat stress-cumulative UVB dose-egg hatching success response model, which we applied to meteorological data. The model analyses illustrated lower and higher survivability peaks in late May and October, respectively, which partly corresponded to data for annual field occurrence, indicating the importance of solar UVB radiation and heat stress as determinants of the seasonal occurrence of this mite. PMID:26314033

  9. Effector and suppressor circuits of the immune response are activated in vivo by different mechanisms

    SciTech Connect

    Okamoto, H.; Kripke, M.L.

    1987-06-01

    The application of fluorescein isothiocyanate (FITC) onto the skin of mice induces a contact hypersensitivity immune response. Lymph nodes draining the skin painted with FITC contain fluorescent cells that induce contact hypersensitivity to FITC when injected into normal mice. The antigen-presenting cells responsible for activating the effector pathway of the contact hypersensitivity response express Ia histocompatibility determinants and are resistant to inactivation with gamma-radiation. Exposing the skin to low doses of UV radiation (280-320 nm) before the application of FITC suppresses the contact hypersensitivity response to FITC. Cells present in the draining lymph nodes of these mice induce suppressor T lymphocytes when injected into normal recipients. The inducer cells in the draining lymph nodes are Thy 1+, Ia- and are inactivated by gamma-radiation. These studies demonstrate that different mechanisms are involved in the in vivo activation of effector and suppressor immune responses, and they suggest that the mode of initial antigen presentation determines which immunologic circuit will be activated in response to a contact-sensitizing antigen.

  10. 7nm logic optical lithography with OPC-Lite

    NASA Astrophysics Data System (ADS)

    Smayling, Michael C.; Tsujita, Koichiro; Yaegashi, Hidetami; Axelrad, Valery; Nakayama, Ryo; Oyama, Kenichi; Yamauchi, Shohei; Ishii, Hiroyuki; Mikami, Koji

    2015-03-01

    The CMOS logic 22nm node was the last one done with single patterning. It used a highly regular layout style with Gridded Design Rules (GDR). Smaller nodes have required the same regular layout style but with multiple patterning for critical layers. A "line/cut" approach is being used to achieve good pattern fidelity and process margin.[1] As shown in Fig. 1, even with "line" patterns, pitch division will eventually be necessary. For the "cut" pattern, Design-Source-Mask Optimization (DSMO) has been demonstrated to be effective at the 20nm node and below.[2,3,4] Single patterning was found to be suitable down to 16nm, while double patterning extended optical lithography for cuts to the 10-12nm nodes. Design optimization avoided the need for triple patterning. Lines can be patterned with 193nm immersion with no complex OPC. The final line dimensions can be achieved by applying pitch division by two or four.[5] In this study, we extend the scaling using simplified OPC to the 7nm node for critical FEOL and BEOL layers. The test block is a reasonably complex logic function with ~100k gates of combinatorial logic and flip-flops, scaled from previous experiments. Simulation results show that for cuts at 7nm logic dimensions, the gate layer can be done with single patterning whose minimum pitch is 53nm, possibly some of the 1x metal layers can be done with double patterning whose minimum pitch is 53nm, and the contact layer will require triple patterning whose minimum pitch is 68nm. These pitches are less than the resolution limit of ArF NA=1.35 (72nm). However these patterns can be separated by a combination of innovative SMO for less than optical resolution limit and a process trick of hole-repair technique. An example of triple patterning coloring is shown in Fig 3. Fin and local interconnect are created by lines and trims. The number of trim patterns are 3 times (min. pitch=90nm) and twice (min. pitch=120nm), respectively. The small number of masks, large pitches, and

  11. 40nm tunable multi-wavelength fiber laser

    NASA Astrophysics Data System (ADS)

    Jia, Qingsong; Wang, Tianshu; Zhang, Peng; Dong, Keyan; Jiang, Huilin

    2014-12-01

    A Brillouin-Erbium multi-wavelength tunable fiber laser at C-band is demostrated. A 10 km long singlemode fiber(SMF), a 6 m long Erbium-doped fiber, two couplers, a wavelength division multiplexer, a isolator, an optical circulator, a 980nm pump laser and a narrow linewidth tunable laser are included in the structure. A segment of 10 km-long single-mode fiber (SMF) between the two ports of a 1×2 coupler is used as Brillouin gain. Ebiumdoped fiber amplifier (EDFA) consists of a segment of 6m er-doped fiber pumped by 980nm laser dioder . A narrow linewidth tunable laser from 1527 to 1607 nm as Brillouin bump, At the Brillouin pump power of 8mW and the 980 nm pump power of 400 mw, 16 output channels with 0.08 nm spacing and tuning range of 40 nm from 1527 nm to 1567 nm are achieved. We realize the tunable output of wavelength by adjusting the 980 nm pump power and the Brillouin pump wavelength. Stability of the multiwavelength fiber laser is also observed.

  12. Leaf Level Chlorophyll Fluorescence Emission Spectra: Narrow Band versus Full 650-800 nm Retrievals

    NASA Astrophysics Data System (ADS)

    Middleton, E.; Zhang, Q.; Campbell, P. K.; Huemmrich, K. F.; Corp, L.; Cheng, Y.

    2012-12-01

    Recently, chlorophyll fluorescence (ChlF) retrievals in narrow spectral regions (< 1 nm, between 750-770 nm) of the near infrared (NIR) region of Earth's reflected radiation have been achieved from satellites, including the Japanese GOSAT and the European Space Agency's Sciamachy/Envisat. However, these retrievals sample the total full-spectrum ChlF and are made at non-optimal wavelengths since they are not located at the peak fluorescence emission features. We wish to estimate the total full-spectrum ChlF based on emissions obtained at selected wavelengths. For this, we drew upon leaf emission spectra measured on corn leaves obtained from a USDA experimental cornfield in MD (USA). These emission spectra were determined for the adaxial and abaxial (i.e., top and underside) surfaces of leaves measured throughout the 2008 and 2011 growing seasons (n>400) using a laboratory instrument (Fluorolog-3, Horiba Scientific, USA), recorded in either 1 nm or 5 nm increments with monochromatic excitation wavelengths of either 532 or 420 nm. The total ChlF signal was computed as the area under the continuous spectral emission curves, summing the emission intensities (counts per second) per waveband. The individual narrow (1 or 5 nm) waveband emission intensities were linearly related to full emission values, with variable success across the spectrum. Equations were developed to estimate total ChlF from these individual wavebands. Here, we report the results for the average adaxial/abaxial emissions. Very strong relationships were achieved for the relatively high fluorescence intensities at the red chlorophyll peak, centered at 685 nm (r2= 0.98, RMSE = 5.53 x 107 photons/s) and in the nearby O2-B atmospheric absorption feature centered at 688 nm (r2 = 0.94, RMSE = 4.04 x 107), as well as in the far-red peak centered at 740 nm (r2=0.94, RMSE = 5.98 x107). Very good retrieval success occurred for the O2-A atmospheric absorption feature on the declining NIR shoulder centered at 760

  13. Electric Field-Assisted Photochemical Water Splitting Should Operate with 287 nm Light.

    PubMed

    Bachler, Vinzenz; Gärtner, Wolfgang

    2016-05-01

    The major photoreaction of water is the homolytic splitting of one O-H bond starting from the 1(1) B1 excited state (λmax = 167 nm). This reaction produces H• and •OH radicals. The combination of two H• atoms leads to the potential energy carrier dihydrogen. However, the energy required to obtain the photoreactive 1(1) B1 electronic state is about 7.4 eV, which cannot be effectively provided by solar radiation. The sun light spectrum on earth comprises the visible and ultraviolet region, but shows vanishing intensity near 7 eV (177.1 nm). This work provides theoretical evidence that the photoreactive 1(1) B1 state of water can be shifted into the ultraviolet (UV-B) light region (≈287 nm) by including explicitly an electric field in the calculations of the water absorption spectrum. To accomplish such bathochromic shift, a large field strength of 3.08 VÅ(-1) is required. The field-dependent excitation energies were calculated by applying the symmetry-adapted cluster configuration interaction (SAC-CI) procedure. Based on this theoretical analysis, we propose that photochemical water splitting can be accomplished by means of 287 nm light provided the water molecule is favorably oriented by an external electric field and is subsequently activated by a reversal of the field orientation.

  14. OSIRIS Detections of a Tropospheric Aerosol that Absorbs at Wavelengths Near 350 nm - Black Carbon?

    NASA Astrophysics Data System (ADS)

    Degenstein, D. A.; Roth, C.; Bourassa, A. E.; Lloyd, N.

    2014-12-01

    The Canadian built OSIRIS instrument has been in operation onboard the Swedish spacecraft Odin since the autumn of 2001. During this 13 year period OSIRIS has recorded millions of spectra of the limb-scattered radiance in the wavelength range from 280 nm to 810 nm with approximately 1 nm spectral resolution. These measurements that scan tangents altitudes from 10 km to 65 km have primarily been used to retrieve stratospheric composition including vertical profiles of ozone, nitrogen dioxide, sulphate aerosol and bromine monoxide. The ozone retrieval is done is such a way that it uses the vertical radiance profile at 350 nm as a non-ozone absorbing reference measurement and it is these measurements that have serendipitously indicated the presence of an absorbing aerosol at tropospheric altitudes. At this time there is no indication of the exact composition of this absorber but it has characteristics that are curiously like those of black carbon. This poster will outline: the technique used to detect the black carbon from OSIRIS measurements; the wavelength dependence of a pseudo absorber used in the SASKTARN radiative transfer model to accurately simulate the OSIRIS measurements; and the geographical distribution of the detections of this pseudo absorber.

  15. Electric Field-Assisted Photochemical Water Splitting Should Operate with 287 nm Light.

    PubMed

    Bachler, Vinzenz; Gärtner, Wolfgang

    2016-05-01

    The major photoreaction of water is the homolytic splitting of one O-H bond starting from the 1(1) B1 excited state (λmax = 167 nm). This reaction produces H• and •OH radicals. The combination of two H• atoms leads to the potential energy carrier dihydrogen. However, the energy required to obtain the photoreactive 1(1) B1 electronic state is about 7.4 eV, which cannot be effectively provided by solar radiation. The sun light spectrum on earth comprises the visible and ultraviolet region, but shows vanishing intensity near 7 eV (177.1 nm). This work provides theoretical evidence that the photoreactive 1(1) B1 state of water can be shifted into the ultraviolet (UV-B) light region (≈287 nm) by including explicitly an electric field in the calculations of the water absorption spectrum. To accomplish such bathochromic shift, a large field strength of 3.08 VÅ(-1) is required. The field-dependent excitation energies were calculated by applying the symmetry-adapted cluster configuration interaction (SAC-CI) procedure. Based on this theoretical analysis, we propose that photochemical water splitting can be accomplished by means of 287 nm light provided the water molecule is favorably oriented by an external electric field and is subsequently activated by a reversal of the field orientation. PMID:26876336

  16. Solar Spectral Irradiance at 782 nm as Measured by the SES Sensor Onboard Picard

    NASA Astrophysics Data System (ADS)

    Meftah, M.; Hauchecorne, A.; Irbah, A.; Cessateur, G.; Bekki, S.; Damé, L.; Bolsée, D.; Pereira, N.

    2016-04-01

    Picard is a satellite dedicated to the simultaneous measurement of the total and solar spectral irradiance, the solar diameter, the solar shape, and to the Sun's interior through the methods of helioseismology. The satellite was launched on June 15, 2010, and pursued its data acquisitions until March 2014. A Sun Ecartometry Sensor (SES) was developed to provide the stringent pointing requirements of the satellite. The SES sensor produced an image of the Sun at 782 ± 2.5 nm. From the SES data, we obtained a new time series of the solar spectral irradiance at 782 nm from 2010 to 2014. During this period of Solar Cycle 24, the amplitude of the changes has been of the order of ± 0.08 %, corresponding to a range of about 2× 10^{-3} W m^{-2} nm^{-1}. SES observations provided a qualitatively consistent evolution of the solar spectral irradiance variability at 782 nm. SES data show similar amplitude variations with the semi-empirical model Spectral And Total Irradiance REconstruction for the Satellite era (SATIRE-S), whereas the Spectral Irradiance Monitor instrument (SIM) onboard the SOlar Radiation and Climate Experiment satellite (SORCE) highlights higher amplitudes.

  17. Ultraviolet radiation effects

    NASA Technical Reports Server (NTRS)

    Slemp, Wayne S.

    1989-01-01

    Solar ultraviolet testing was not developed which will provide highly accelerated (20 to 50X) exposures that correlate to flight test data. Additional studies are required to develop an exposure methodology which will assure that accelerated testing can be used for qualification of materials and coatings for long duration space flight. Some conclusions are listed: Solar UV radiation is present in all orbital environments; Solar UV does not change in flux with orbital altitude; UV radiation can degrade most coatings and polymeric films; Laboratory UV simulation methodology is needed for accelerated testing to 20 UV solar constants; Simulation of extreme UV (below 200 nm) is needed to evaluate requirements for EUV in solar simulation.

  18. Radiation Chemistry

    NASA Astrophysics Data System (ADS)

    Wojnárovits, L.

    Ionizing radiation causes chemical changes in the molecules of the interacting medium. The initial molecules change to new molecules, resulting in changes of the physical, chemical, and eventually biological properties of the material. For instance, water decomposes to its elements H2 and O2. In polymers, degradation and crosslinking take place. In biopolymers, e.g., DNS strand breaks and other alterations occur. Such changes are to be avoided in some cases (radiation protection), however, in other cases they are used for technological purposes (radiation processing). This chapter introduces radiation chemistry by discussing the sources of ionizing radiation (radionuclide sources, machine sources), absorption of radiation energy, techniques used in radiation chemistry research, and methods of absorbed energy (absorbed dose) measurements. Radiation chemistry of different classes of inorganic (water and aqueous solutions, inorganic solids, ionic liquids (ILs)) and organic substances (hydrocarbons, halogenated compounds, polymers, and biomolecules) is discussed in concise form together with theoretical and experimental backgrounds. An essential part of the chapter is the introduction of radiation processing technologies in the fields of polymer chemistry, food processing, and sterilization. The application of radiation chemistry to nuclear technology and to protection of environment (flue gas treatment, wastewater treatment) is also discussed.

  19. Hard X-ray Microscopy with sub 30 nm Spatial Resolution

    NASA Astrophysics Data System (ADS)

    Tang, Mau-Tsu; Song, Yen-Fang; Yin, Gung-Chian; Chen, Fu-Rong; Chen, Jian-Hua; Chen, Yi-Ming; Liang, Keng S.; Duewer, F.; Yun, Wenbing

    2007-01-01

    A transmission X-ray microscope (TXM) has been installed at the BL01B beamline at National Synchrotron Radiation Research Center in Taiwan. This state-of-the-art TXM operational in a range 8-11 keV provides 2D images and 3D tomography with spatial resolution 60 nm, and with the Zernike-phase contrast mode for imaging light materials such as biological specimens. A spatial resolution of the TXM better than 30 nm, apparently the best result in hard X-ray microscopy, has been achieved by employing the third diffraction order of the objective zone plate. The TXM has been applied in diverse research fields, including analysis of failure mechanisms in microelectronic devices, tomographic structures of naturally grown photonic specimens, and the internal structure of fault zone gouges from an earthquake core. Here we discuss the scope and prospects of the project, and the progress of the TXM in NSRRC.

  20. Hard X-ray Microscopy with sub 30 nm Spatial Resolution

    SciTech Connect

    Tang, M.-T.; Song, Y.-F.; Yin, G.-C.; Chen, J.-H.; Chen, Y.-M.; Liang, Keng S.; Chen, F.-R.; Duewer, F.; Yun Wenbing

    2007-01-19

    A transmission X-ray microscope (TXM) has been installed at the BL01B beamline at National Synchrotron Radiation Research Center in Taiwan. This state-of-the-art TXM operational in a range 8-11 keV provides 2D images and 3D tomography with spatial resolution 60 nm, and with the Zernike-phase contrast mode for imaging light materials such as biological specimens. A spatial resolution of the TXM better than 30 nm, apparently the best result in hard X-ray microscopy, has been achieved by employing the third diffraction order of the objective zone plate. The TXM has been applied in diverse research fields, including analysis of failure mechanisms in microelectronic devices, tomographic structures of naturally grown photonic specimens, and the internal structure of fault zone gouges from an earthquake core. Here we discuss the scope and prospects of the project, and the progress of the TXM in NSRRC.

  1. Laser-plasma source parameters for Kr, Gd, and Tb ions at 6.6 nm

    SciTech Connect

    Masnavi, Majid; Szilagyi, John; Parchamy, Homaira; Richardson, Martin C.

    2013-04-22

    There is increasing interest in extreme-ultraviolet (EUV) laser-based lamps for sub-10-nm lithography operating in the region of 6.6 nm. A collisional-radiative model is developed as a post-processor of a hydrodynamic code to investigate emission from resonance lines in Kr, Gd, and Tb ions under conditions typical for mass-limited EUV sources. The analysis reveals that maximum conversion efficiencies of Kr occur at 5 Multiplication-Sign 10{sup 10}W/cm{sup 2}, while for Gd and Tb it was Asymptotically-Equal-To 0.9%/2{pi}sr for laser intensities of (2-5) Multiplication-Sign 10{sup 12}W/cm{sup 2}.

  2. Demonstration of a GaAs-based 1550-nm continuous wave photomixer

    SciTech Connect

    Zhang, W.-D. Brown, E. R.; Middendorf, J. R.

    2015-01-12

    An Er:GaAs-based 1550-nm CW photomixer is demonstrated. The related mechanism is extrinsic photoconductivity with optical absorption between the localized deep levels created by the Er and the extended states above the conduction band edge of GaAs. With the power boost made possible by a fiber-coupled erbium-doped-fiber amplifier, the Er:GaAs photomixers, operating at 1550 nm, radiate THz power levels easily measured by a Golay cell, and display a power spectrum having a −3 dB roll-off frequency of 307 GHz. This corresponds to a photocarrier lifetime of 520 fs, in good agreement with a previous measurement of the bandwidth of the same material in a photoconductive switch.

  3. Release of P and K from yeast cells irradiated by vacuum UV below 170 nm.

    PubMed

    Matsumoto, S; Ito, T; Ito, A; Tsuchiya, K; Chiba, R; Kitao, K

    1984-01-01

    Yeast cells were irradiated with monochromatic synchrotron radiation (SR) under wet conditions in the wavelength region from 160 to 185 nm at INS-SOR, Tokyo. By the particle-induced X-ray emission (PIXE) method applied to whole cells several elements were found to be released from the irradiated cells at the wavelengths shorter than 170 nm. The most drastic release occurred with phosphorus, followed potassium. Sulphur and calcium were not released over the whole wavelength region studied. It was also revealed that the release of these elements paralleled the cell inactivation. The cause of these element releases upon vaccuum-UV irradiation was inferred in relation to the dissociation of H2O molecules located in the vicinity of the cell surface region. PMID:6387774

  4. Laser trapping dynamics of 200 nm-polystyrene particles at a solution surface

    NASA Astrophysics Data System (ADS)

    Yuyama, Ken-ichi; Sugiyama, Teruki; Masuhara, Hiroshi

    2013-09-01

    We present laser trapping behaviors of 200 nm-polystyrene particles in D2O solution and at its surface using a focused continuous-wave laser beam of 1064 nm. Upon focusing the laser beam into the solution surface, the particles are gathered at the focal spot, and their assembly is expanded to the outside and becomes much larger than the focal volume. The resultant assembly is observed colored under halogen lamp illumination, which is due to a periodic structure like a colloidal crystal. This trapping behavior is much different compared to the laser irradiation into the inside of the solution where a particle-like assembly with a size similar to that of the focal volume is prepared. These findings provide us new insights to consider how radiation pressure of a focused laser beam acts on nanoparticles at a solution surface.

  5. Demonstration of miniaturized 20mW CW 280nm and 266nm solid-state UV laser sources

    NASA Astrophysics Data System (ADS)

    Landru, Nicolas; Georges, Thierry; Beaurepaire, Julien; Le Guen, Bruno; Le Bail, Guy

    2015-02-01

    Visible 561 nm and 532 nm laser emissions from 14-mm long DPSS monolithic cavities are frequency converted to deep UV 280 nm and 266 nm in 16-mm long monolithic external cavities. Wavelength conversion is fully insensitive to mechanical vibrations and the whole UV laser sources fit in a miniaturized housing. More than 20 mW deep UV laser emission is demonstrated with high power stability, low noise and good beam quality. Aging tests are in progress but long lifetimes are expected thanks to the cavity design. Protein detection and deep UV resonant Raman spectroscopy are applications that could benefit from these laser sources.

  6. Evaluation of dental pulp repair using low level laser therapy (688 nm and 785 nm) morphologic study in capuchin monkeys

    NASA Astrophysics Data System (ADS)

    Pretel, H.; Oliveira, J. A.; Lizarelli, R. F. Z.; Ramalho, L. T. O.

    2009-02-01

    The aim of this study was to evaluate the hypothesis that low-level laser therapy (LLLT) 688 nm and 785 nm accelerate dentin barrier formation and repair process after traumatic pulp exposure. The sample consisted of 45 premolars of capuchin monkeys (Cebus apella) with pulp exposure Class V cavities. All premolars were treated with calcium hydroxide (Ca(OH)2), divided in groups of 15 teeth each, and analyzed on 7th, 25th, and 60th day. Group GI - only Ca(OH)2, GII - laser 688 nm, and GIII - laser 785 nm. Laser beam was used in single and punctual dose with the parameters: continuous, 688 nm and 785 nm wavelength, tip's area of 0.00785 cm2, power 50 mW, application time 20 s, dose 255 J/cm2, energy 2 J. Teeth were capped with Ca(OH)2, Ca(OH)2 cement and restored with amalgam. All groups presented pulp repair. On 25th day the thickness of the formed dentin barrier was different between the groups GI and GII (p < 0.05) and between groups GI and GIII (p < 0.01). On 60th day there was difference between GI and GIII (p < 0.01). It may be concluded that, LLLT 688 nm and 785 nm accelerated dentin barrier formation and consequently pulp repair process, with best results using infrared laser 785 nm.

  7. 1319 nm and 1356 nm dual-wavelength operation of diode-side-pumped Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Chen, Ming; Wang, Zhi-chao; Zhang, Shen-jin; Yang, Feng; Zhang, Feng-feng; Yuan, Lei; He, Miao; Li, Jia-jia; Zhang, Xiao-wen; Zong, Nan; Wang, Zhi-min; Bo, Yong; Peng, Qin-jun; Cui, Da-fu; Xu, Zu-yan

    2016-05-01

    We report the first demonstration on a diode-side-pumped quasi continuous wave (QCW) dual-wavelength Nd:YAG laser operating at 1319 nm and 1356 nm. The resonator adopts symmetrical L-shaped flat-flat structure working in a thermally near unstable cavity. By precise coating on the cavity mirrors, the simultaneous oscillation at 1319 nm and 1356 nm is delivered. A maximum dual-wavelength output power of 9.4 W is obtained. The beam quality factor M2 is measured to be 1.9.

  8. Lead extraction by selective operation of a nanosecond-pulsed 355nm laser

    NASA Astrophysics Data System (ADS)

    Herzog, Amir; Bogdan, Stefan; Glikson, Michael; Ishaaya, Amiel A.; Love, Charles

    2016-03-01

    Lead extraction (LE) is necessary for patients who are suffering from a related infection, or in opening venous occlusions that prevent the insertion of additional lead. In severe cases of fibrous encapsulation of the lead within a vein, laser-based cardiac LE has become one of the foremost methods of removal. In cases where the laser radiation (typically at 308 nm wavelength) interacts with the vein wall rather than with the fibrotic lesion, severe injury and subsequent bleeding may occur. Selective tissue ablation was previously demonstrated by a laser operating in the UV regime; however, it requires the use of sensitizers (e.g.: tetracycline). In this study, we present a preliminary examination of efficacy and safety aspects in the use of a nanosecond-pulsed solid-state laser radiation, at 355 nm wavelength, guided in a catheter consisting of optical fibers, in LE. Specifically, we demonstrate a correlation between the tissue elasticity and the catheter advancement rate, in ex-vivo experiments. Our results indicate a selectivity property for specific parameters of the laser radiation and catheter design. The selectivity is attributed to differences in the mechanical properties of the fibrotic tissue and a normal vein wall, leading to a different photomechanical response of the tissue's extracellular matrix. Furthermore, we performed successful in-vivo animal trials, providing a basic proof of concept for using the suggested scheme in LE. Selective operation using a 355 nm laser may reduce the risk of blood vessel perforation as well as the incidence of major adverse events.

  9. Development of a 266 nm Raman lidar for profiling atmospheric water vapor

    NASA Astrophysics Data System (ADS)

    Uesugi, T.; Tsuda, T.; Yabuki, M.; Liu, Y.

    2014-12-01

    It is projected that localized extreme weather events could increase due to the effects of global warming, resulting in severe weather disasters, such as a torrential rain, floods, and so on. Understanding water vapor's behavior in the atmosphere is essen- tial to understand a fundamental mechanism of these weather events. Therefore, continuous monitoring system to measure the atmospheric water vapor with good spatio-temporal resolution is required. We have developed several water vapor Raman lidar systems employing the laser wavelengths of 355 and 532 nm. However, the signal-to-noise ratio of the Raman lidar strongly depends on the sky background because of the detection of the weak inelastic scattering of light by molecules. Therefore, these systems were mainly used during nighttime. Hence, we have newly developed a water vapor Raman lidar using a quadrupled Nd:YAG laser at a wavelength of 266 nm. This wavelength is in the ultraviolet (UV) range below 300 nm known as the "solar-blind" region, because practically all radiation at these wavelengths is absorbed by the ozone layer in the stratosphere. It has the advantage of having no daytime solar background radiation in the system. The lidar is equipped with a 25 cm receiving telescope and is used for measuring the light separated into an elastic backscatter signal and vibrational Raman signals of nitrogen and water vapor at wavelengths of 266.1, 283.6, and 294.6 nm, respectively. This system can be used for continuous water vapor measurements in the lower troposphere. This study introduces the design of the UV lidar system and shows the preliminary results of water vapor profiles.

  10. Evaluation of a 345 nm Femtosecond Laser for Corneal Surgery with Respect to Intraocular Radiation Hazard

    PubMed Central

    Tourtas, Theofilos; Polisetti, Naresh; Klenke, Jörg; Skerl, Katrin; Wüllner, Christian; Donitzky, Christof; Kruse, Friedrich E.; Kremers, Jan; Hammer, Christian M.

    2015-01-01

    Purpose We report our findings from a preclinical safety study designed to assess potential side effects of corneal ultraviolet femtosecond laser treatment on lens and retina. Methods Refractive lenticules (-5 dpt) with a diameter of 6 mm were created in the right cornea of eight Dutch Belted rabbits. Radiant exposure was 0.5 J/cm² in two animals and 18 J/cm² in six animals. The presence of lens opacities was assessed prior to and up to six months following laser application using Scheimpflug images (Pentacam, Oculus) and backscatter analysis (Opacity Lensmeter 702, Interzeag). Ganzfeld flash and flicker electroretinogram (ERG) recordings were obtained from both eyes prior to and up to six weeks following laser application. At the study endpoint, retinas were examined by light microscopy. Results Independent of energy dose applied, no cataract formation could be observed clinically or with either of the two objective methods used. No changes in ERG recordings over time and no difference between treated and untreated eye were detected. Histologically, retinal morphology was preserved and retinal pigment epithelium as well as photoreceptor inner and outer segments appeared undamaged. Quantitative digital image analysis did not reveal cell loss in inner or outer nuclear layers. Conclusions Our analysis confirms theoretical considerations suggesting that ultraviolet femtosecond laser treatment of the cornea is safe for intraocular tissues. Transmitted light including stray light induces no photochemical effects in lens or retina at energy levels much higher than required for the clinical purpose. These conclusions cannot be applied to eyes with pre-existing retinal damage, as these may be more vulnerable to light. PMID:26361228

  11. Histological study of the thyroid gland following 904-nm laser radiation

    NASA Astrophysics Data System (ADS)

    Perez de Vargas, I.; Parrado, C.; Gonzalez, V.; Vidal, Lourdes; Rius, F.

    1993-06-01

    The present histological and stereological studies are on thyroid glands of Wistar rats irradiated with an IR laser. The animals were exposed to total doses of 46,80 J/cm2, and sacrificed at 1, 40, and 180 days after the last treatment. A morphological and stereological study was made on follicular epithelium, follicle, stroma, and capillary. The laser beam produced an increase of follicular epithelial volume and hyperplasia of follicular cells in the animals sacrificed at 1, 40, and 180 days after the last treatment. Capillary dilation underwent a progressive decrease as time passed. It was higher in the animals sacrificed after 24 hours, then it decreased after 40 days and finally disappeared after 180 days.

  12. Radiator technology

    NASA Technical Reports Server (NTRS)

    Juhasz, Albert J.

    1993-01-01

    Radiator technology is discussed in the context of the Civilian Space Technology Initiative's (CSTI's) high capacity power-thermal management project. The CSTI project is a subset of a project to develop a piloted Mars nuclear electric propulsion (NEP) vehicle. The following topics are presented in vugraph form: advanced radiator concepts; heat pipe codes and testing; composite materials; radiator design and integration; and surface morphology.

  13. Hawking radiation

    NASA Astrophysics Data System (ADS)

    Parentani, Renaud; Spindel, Philippe

    2011-12-01

    Hawking radiation is the thermal radiation predicted to be spontaneously emitted by black holes. It arises from the steady conversion of quantum vacuum fluctuations into pairs of particles, one of which escaping at infinity while the other is trapped inside the black hole horizon. It is named after the physicist Stephen Hawking who derived its existence in 1974. This radiation reduces the mass of black holes and is therefore also known as black hole evaporation.

  14. Next-generation 193-nm laser for sub-100-nm lithography

    NASA Astrophysics Data System (ADS)

    Duffey, Thomas P.; Blumenstock, Gerry M.; Fleurov, Vladimir B.; Pan, Xiaojiang; Newman, Peter C.; Glatzel, Holger; Watson, Tom A.; Erxmeyer, J.; Kuschnereit, Ralf; Weigl, Bernhard

    2001-09-01

    The next generation 193 nm (ArF) laser has been designed and developed for high-volume production lithography. The NanoLithTM 7000, offering 20 Watts average output power at 4 kHz repetition rates is designed to support the highest exposure tool scan speeds for maximum productivity and wafer throughput. Fundamental design changes made to the laser core technologies are described. These advancements in core technology support the delivery of highly line-narrowed light with

  15. Applications of the 308-nm excimer laser in dermatology

    NASA Astrophysics Data System (ADS)

    Farkas, A.; Kemeny, L.

    2006-05-01

    Excimer lasers contain a mixture of a noble inert gas and a halogen, which form excited dimers only in the activated state. High-energy current is used to produce these dimers, which have a very short lifetime, and after their fast dissociation they release the excitation energy through ultraviolet photons. The application of these lasers proved to be successful in medicine, including the field of ophthalmology, cardiology, angiology, dentistry, orthopaedics, and, in recent years, dermatology. For medical purposes, the 193-nm argon fluoride, the 248-nm krypton fluoride, the 351-nm xenon fluoride, and the 308-nm xenon chloride lasers are used. Recently, the 308-nm xenon chloride laser has gained much attention as a very effective treatment modality in dermatological disorders. It was successfully utilized in psoriasis; later, it proved to be useful in handling other lightsensitive skin disorders and even in the treatment of allergic rhinitis. This review summarizes the possible applications of this promising tool in dermatology.

  16. Evidence for high-efficiency laser-heated hohlraum performance at 527 nm.

    PubMed

    Stevenson, R M; Oades, K; Thomas, B R; Schneider, M; Slark, G E; Suter, L J; Kauffman, R; Hinkel, D; Miller, M C

    2005-02-11

    A series of experiments conducted on the HELEN laser system [M. J. Norman, Appl. Opt.4120023497], into thermal x-ray generation from hohlraum targets using 527 nm (2omega) wavelength laser light, has shown that it is possible to exceed radiation temperatures previously thought limited by high levels of superthermal or hot electron production or stimulated backscatter. This Letter questions whether the assumptions traditionally applied to hohlraum design with respect to hot plasma filling and the use of 2omega light are too conservative.

  17. Stacked optical antennas for plasmon propagation in a 5 nm-confined cavity.

    PubMed

    Saeed, A; Panaro, S; Zaccaria, R Proietti; Raja, W; Liberale, C; Dipalo, M; Messina, G C; Wang, H; De Angelis, F; Toma, A

    2015-06-09

    The sub-wavelength concentration and propagation of electromagnetic energy are two complementary aspects of plasmonics that are not necessarily co-present in a single nanosystem. Here we exploit the strong nanofocusing properties of stacked optical antennas in order to highly concentrate the electromagnetic energy into a 5 nm metal-insulator-metal (MIM) cavity and convert free radiation into guided modes. The proposed nano-architecture combines the concentration properties of optical nanoantennas with the propagation capability of MIM systems, paving the way to highly miniaturized on-chip plasmonic waveguiding.

  18. Robust near-infrared light bullet in 800-nm femtosecond light filaments in air

    NASA Astrophysics Data System (ADS)

    Panov, Nikolay A.; Shipilo, Daniil E.; Andreeva, Vera A.; Uryupina, Daria S.; Savel'ev, Andrei B.; Kosareva, Olga G.; Chin, See Leang

    2015-09-01

    Systematic numerical study of near-infrared radiation formed during filamentation in air revealed the formation of robust light bullet first registered in the experiment (Chen et al. in Appl Phys B 91:219, 2008). The near-infrared light bullet propagates along the filament axis with the divergence <1 mrad and the quasi-constant duration of ~30 fs. The central wavelength of the bullet gradually increases from 860 to 900 nm during the propagation. The results of our numerical simulation are in agreement with the experiments (Chen et al. in Appl Phys B 91:219, 2008; Uryupina et al. in Appl Phys B 110:123, 2013).

  19. Temperature-dependent 780-nm laser absorption by engineering grade aluminum, titanium, and steel alloy surfaces

    SciTech Connect

    Rubenchik, Alexander M.; Wu, Sheldon S. Q.; Kanz, V. Keith; LeBlanc, Mary M.; Lowdermilk, W. Howard; Rotter, Mark D.; Stanley, Joel R.

    2014-07-17

    When modeling laser interaction with metals for various applications it requires a knowledge of absorption coefficients for real, commercially available materials with engineering grade (unpolished, oxidized) surfaces. But, most currently available absorptivity data pertain to pure metals with polished surfaces or vacuum-deposited thin films in controlled atmospheres. A simple laboratory setup is developed for the direct calorimetric absorptivity measurements using a diode-array laser emitting at 780 nm. A scheme eliminating the effect of convective and radiative losses is implemented. Futhermore, the obtained absorptivity results differ considerably from existing data for polished pure metals and are essential for the development of predictive laser-material interaction models.

  20. Evidence for high-efficiency laser-heated hohlraum performance at 527 nm.

    PubMed

    Stevenson, R M; Oades, K; Thomas, B R; Schneider, M; Slark, G E; Suter, L J; Kauffman, R; Hinkel, D; Miller, M C

    2005-02-11

    A series of experiments conducted on the HELEN laser system [M. J. Norman, Appl. Opt.4120023497], into thermal x-ray generation from hohlraum targets using 527 nm (2omega) wavelength laser light, has shown that it is possible to exceed radiation temperatures previously thought limited by high levels of superthermal or hot electron production or stimulated backscatter. This Letter questions whether the assumptions traditionally applied to hohlraum design with respect to hot plasma filling and the use of 2omega light are too conservative. PMID:15783658

  1. Phase-matched frequency conversion below 150 nm in KBe2BO3F2.

    PubMed

    Nakazato, Tomoharu; Ito, Isao; Kobayashi, Yohei; Wang, Xiaoyang; Chen, Chuangtian; Watanabe, Shuntaro

    2016-07-25

    Sum frequency mixing has been demonstrated below 150 nm in KBeBO3F2 by using the fundamental with its fourth harmonic of a 6 kHz Ti: sapphire laser system. The wavelength of 149.8 nm is the shortest ever obtained to our knowledge by phase matching in nonlinear crystals. The output powers were 3.6 μW at 149.8 nm and 110 μW at 154.0 nm, respectively. The phase matching angles measured from 149.8 to 158.1 nm are larger by 3-4 degrees than those expected from the existing Sellmeier equation. The measured transmission spectra of KBeBO3F2 crystals support the generation of coherent radiation below 150 nm. PMID:27464165

  2. FBG inscription in non-hydrogenated SMF28 fiber with a ns Q-switched Nd:VO4 laser at 213 nm

    NASA Astrophysics Data System (ADS)

    Berrang, Bianca; Polz, Leonhard; Kuttler, Rolf; Bartschke, Jürgen; Roths, Johannes

    2013-05-01

    Fiber Bragg grating (FBG) inscription efficiencies with a nanosecond (ns) KrF-Excimer laser source at 248 nm and with a ns Q-switched, 5th-harmonic Nd:VO4 laser source at 213 nm were compared. With both laser sources the phase mask method was used for FBG inscription. The growth process of the refractive index change during UV-exposure is presented as a function of cumulated fluence for inscription in standard non-hydrogenated SMF28 fibers. The inscription efficiency was found to be significantly higher for the 213 nm than for the 248 nm radiation, indicating a higher photosensitivity at 213 nm compared to 248 nm in low Ge-doped fibers.

  3. Shot noise startup of the 6 NM SASE FEL at the Tesla Test Facility

    SciTech Connect

    Pierini, P.; Fawley, W.M.

    1995-12-31

    We present here an analysis of the shot noise startup of the 6 nm SASE FEI proposal at the TESLA Test Facility in DESY The statistical of the saturation length and output power due to the intrinsic randomness of the noise startup are investigated with the use of the 2D time dependent code GINGER, that takes into account propagation effects and models shot noise. We then provide estimates for the spectral contents and linewidth of the emitted radiation and describe its spiking characteristics. The output radiation will develop superradiant spikes seeded by the shot noise in the electron beam, which can entrance the average emitted power at the expense of some spectral broadening.

  4. Quantifying solar spectral irradiance in aquatic habitats for the assessment of photoenhanced toxicity

    USGS Publications Warehouse

    Barron, M.G.; Little, E.E.; Calfee, R.; Diamond, S.

    2000-01-01

    The spectra and intensity of solar radiation (solar spectral irradiance [SSI]) was quantified in selected aquatic habitats in the vicinity of an oil field on the California coast. Solar spectral irradiance measurements consisted of spectral scans (280-700 rim) and radiometric measurements of ultraviolet (UV): UVB (280-320 nm) and UVA (320-400 nm). Solar spectral irradiance measurements were taken at the surface and at various depths in two marsh ponds, a shallow wetland, an estuary lagoon, and the intertidal area of a high-energy sandy beach. Daily fluctuation in SSI showed a general parabolic relationship with time; maximum structure-activity relationship (SAR) was observed at approximate solar noon. Solar spectral irradiance measurements taken at 10-cm depth at approximate solar noon in multiple aquatic habitats exhibited only a twofold variation in visible light and UVA and a 4.5-fold variation in UVB. Visible light ranged from 11,000 to 19,000 ??W/cm2, UVA ranged from 460 to 1,100 ??W/cm2, and UVB ranged from 8.4 to 38 ??W/cm2. In each habitat, the attenuation of light intensity with increasing water depth was differentially affected over specific wavelengths of SSI. The study results allowed the development of environmentally realistic light regimes necessary for photoenhanced toxicity studies.

  5. At what time should one go out in the sun?

    PubMed

    Moan, Johan; Dahlback, Arne; Porojnicu, Alina Carmen

    2008-01-01

    To get an optimal vitamin D supplement from the sun at a minimal risk of getting cutaneous malignant melanoma (CMM), the best time of sun exposure is noon. Thus, common health recommendations given by authorities in many countries, that sun exposure should be avoided for three to five hours around noon and postponed to the afternoon, may be wrong and may even promote CMM. The reasons for this are (1) The action spectrum for CMM is likely to be centered at longer wavelengths (UVA, ultraviolet A, 320-400 nm) than that of vitamin D generation (UVB, ultraviolet B, 280-320 nm). (2) Scattering of solar radiation on clear days is caused by small scattering elements, Rayleigh dominated and increases with decreasing wavelengths. A larger fraction of UVA than of UVB comes directly and unscattered from the sun. (3) The human body can be more realistically represented by a vertical cylinder than by a horizontal, planar surface, as done in almost all calculations in the literature. With the cylinder model, high UVA fluence rates last about twice as long after noon as high UVB fluence rates do. In view of this, short, nonerythemogenic exposures around noon should be recommended rather than longer nonerythemogenic exposures in the afternoon. This would give a maximal yield of vitamin D at a minimal CMM risk. PMID:18348449

  6. Absolute frequency measurement for the emission transitions of molecular iodine in the 982 - 985 nm range

    SciTech Connect

    Matyugin, Yu A; Ignatovich, S M; Kuznetsov, Sergei A; Nesterenko, M I; Okhapkin, M V; Pivtsov, V S; Skvortsov, Mikhail N; Bagaev, Sergei N

    2012-03-31

    We report high-precision frequency measurements of the separate hyperfine structure (HFS) components of the emission B - X system transitions of {sup 127}I{sub 2} molecules in the 982 - 985 nm range. To resolve the HFS of the emission lines, advantage was taken of the method of three-level laser spectroscopy. The function of exciting radiation was fulfilled by the second harmonic of a cw Nd : YAG laser, and the probe radiation in the 968 - 998 nm range was generated by an external-cavity diode laser. The output Nd : YAG laser frequency was locked to an HFS component of the absorption transition and the probing laser radiation to the emission transition component. When both frequencies were locked to HFS components with a common upper level, the output diode laser frequency was precisely equal to the emission transition frequency. The output frequency of the thus stabilised diode laser was measured with the help of a femtosecond optical frequency synthesiser based on a Ti : sapphire laser. We present the results of the absolute frequency measurements of 20 HFS components belonging to six vibrational - rotational transitions of the B - X system of iodine [R56(32 - 48)a1, P58(32 - 48)a1, P85(33 - 48)a1, R87(33 - 48a1, R88(33 - 48)a10] and all 15 components of the R86(33 - 48) line. The relative measurement uncertainty is equal to 7 Multiplication-Sign 10{sup -10} and is determined by the frequency instability of the diode laser radiation.

  7. 1064 nm laser emission of highly doped Nd: Yttrium aluminum garnet under 885 nm diode laser pumping

    NASA Astrophysics Data System (ADS)

    Lupei, V.; Pavel, N.; Taira, T.

    2002-06-01

    Highly efficient 1064 nm continuous-wave laser emission under 885 nm diode pumping in concentrated Nd: Yttrium aluminum garnet (YAG) crystals (up to 3.5 at. % Nd) and ceramics (up to 3.8 at. % Nd) is reported. A highly doped (2.4 at. %) Nd:YAG laser, passively Q switched by a Cr4+:YAG saturable absorber, is demonstrated.

  8. Wavelength dependence on the forensic analysis of glass by nanosecond 266 nm and 1064 nm laser induced breakdown spectroscopy

    SciTech Connect

    Cahoon, Erica M.; Almirall, Jose R.

    2010-05-01

    Laser induced breakdown spectroscopy can be used for the chemical characterization of glass to provide evidence of an association between a fragment found at a crime scene to a source of glass of known origin. Two different laser irradiances, 266 nm and 1064 nm, were used to conduct qualitative and quantitative analysis of glass standards. Single-pulse and double-pulse configurations and lens-to-sample-distance settings were optimized to yield the best laser-glass coupling. Laser energy and acquisition timing delays were also optimized to result in the highest signal-to-noise ratio corresponding to the highest precision and accuracy. The crater morphology was examined and the mass removed was calculated for both the 266 nm and 1064 nm irradiations. The analytical figures of merit suggest that the 266 nm and 1064 nm wavelengths are capable of good performance for the forensic chemical characterization of glass. The results presented here suggest that the 266 nm laser produces a better laser-glass matrix coupling, resulting in a better stoichiometric representation of the glass sample. The 266 nm irradiance is therefore recommended for the forensic analysis and comparison of glass samples.

  9. Ultrastructure: effects of melanin pigment on target specificity using a pulsed dye laser (577 nm)

    SciTech Connect

    Tong, A.K.; Tan, O.T.; Boll, J.; Parrish, J.A.; Murphy, G.F.

    1987-06-01

    It has been shown recently that brief pulses of 577 nm radiation from the tunable dye laser are absorbed selectively by oxyhemoglobin. This absorption is associated with highly specific damage to superficial vascular plexus blood vessels in those with lightly pigmented (type I-II) skin. To determine whether pigmentary differences in the overlying epidermis influence this target specificity, we exposed both type I (fair) and type V (dark) normal human skin to varying radiant exposure doses over 1.5-microsecond pulse durations from the tunable dye laser at a wavelength of 577 nm. Using ultrastructural techniques, we found in type I skin that even clinical subthreshold laser exposures caused reproducible alterations of erythrocytes and adjacent dermal vascular endothelium without comparable damage to the overlying epidermis. In contrast, degenerated epidermal basal cells represented the predominant form of cellular damage after laser exposure of type V skin at comparable doses. We conclude that epidermal melanin and vascular hemoglobin are competing sites for 577 nm laser absorption and damage, and that the target specificity of the 577 nm tunable dye laser is therefore influenced by variations in epidermal pigmentation. This finding is relevant to the clinical application of the tunable dye laser in the ablative treatment of vascular lesions. We also found on ultrastructure that the presence of electron-lucent circular structures of approximately 800 A in diameter were observed only at and above clinical threshold doses in those with type I skin and at the highest dose of 2.75 J/cm2 in type V skin. It has been proposed that these structures might be heat-fixed molds of water vapor. Both this and ultrastructural changes of epidermal basal cells demonstrate mechanisms responsible for alteration of tissue after exposure to 577 nm, which are discussed.

  10. Imaging spectrometer measurement of water vapor in the 400 to 2500 nm spectral region

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Roberts, Dar A.; Conel, James E.; Dozier, Jeff

    1995-01-01

    The Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) measures the total upwelling spectral radiance from 400 to 2500 nm sampled at 10 nm intervals. The instrument acquires spectral data at an altitude of 20 km above sea level, as images of 11 by up to 100 km at 17x17 meter spatial sampling. We have developed a nonlinear spectral fitting algorithm coupled with a radiative transfer code to derive the total path water vapor from the spectrum, measured for each spatial element in an AVIRIS image. The algorithm compensates for variation in the surface spectral reflectance and atmospheric aerosols. It uses water vapor absorption bands centered at 940 nm, 1040 nm, and 1380 nm. We analyze data sets with water vapor abundances ranging from 1 to 40 perceptible millimeters. In one data set, the total path water vapor varies from 7 to 21 mm over a distance of less than 10 km. We have analyzed a time series of five images acquired at 12 minute intervals; these show spatially heterogeneous changes of advocated water vapor of 25 percent over 1 hour. The algorithm determines water vapor for images with a range of ground covers, including bare rock and soil, sparse to dense vegetation, snow and ice, open water, and clouds. The precision of the water vapor determination approaches one percent. However, the precision is sensitive to the absolute abundance and the absorption strength of the atmospheric water vapor band analyzed. We have evaluated the accuracy of the algorithm by comparing several surface-based determinations of water vapor at the time of the AVIRIS data acquisition. The agreement between the AVIRIS measured water vapor and the in situ surface radiometer and surface interferometer measured water vapor is 5 to 10 percent.

  11. EUV reticle inspection with a 193nm reticle inspector

    NASA Astrophysics Data System (ADS)

    Broadbent, William; Inderhees, Gregg; Yamamoto, Tetsuya; Lee, Isaac; Lim, Phillip

    2013-06-01

    The prevailing industry opinion is that EUV Lithography (EUVL) will enter High Volume Manufacturing (HVM) in the 2015 - 2017 timeframe at the 16nm HP node. Every year the industry assesses the key risk factors for introducing EUVL into HVM - blank and reticle defects are among the top items. To reduce EUV blank and reticle defect levels, high sensitivity inspection is needed. To address this EUV inspection need, KLA-Tencor first developed EUV blank inspection and EUV reticle inspection capability for their 193nm wavelength reticle inspection system - the Teron 610 Series (2010). This system has become the industry standard for 22nm / 3xhp optical reticle HVM along with 14nm / 2xhp optical pilot production; it is further widely used for EUV blank and reticle inspection in R and D. To prepare for the upcoming 10nm / 1xhp generation, KLA-Tencor has developed the Teron 630 Series reticle inspection system which includes many technical advances; these advances can be applied to both EUV and optical reticles. The advanced capabilities are described in this paper with application to EUV die-to-database and die-to-die inspection for currently available 14nm / 2xhp generation EUV reticles. As 10nm / 1xhp generation optical and EUV reticles become available later in 2013, the system will be tested to identify areas for further improvement with the goal to be ready for pilot lines in early 2015.

  12. Understanding Radiation.

    ERIC Educational Resources Information Center

    Department of Energy, Washington, DC. Nuclear Energy Office.

    Radiation is a natural energy force that has been a part of the environment since the Earth was formed. It takes various forms, none of which can be smelled, tasted, seen, heard, or felt. Nevertheless, scientists know what it is, where it comes from, how to measure and detect it, and how it affects people. Cosmic radiation from outer space and…

  13. Evolution of the gate current in 32 nm MOSFETs under irradiation

    NASA Astrophysics Data System (ADS)

    Palumbo, F.; Debray, M.; Vega, N.; Quinteros, C.; Kalstein, A.; Guarin, F.

    2016-05-01

    Radiation induced currents on single 32 nm MOSFET transistors have been studied using consecutive runs of 16O at 25 MeV. The main feature is the generation of current peaks - in the gate and channel currents - due to the collection of the electro-hole pairs generated by the incident radiation runs. It has been observed that the incident ions cause damage in the dielectric layer and in the substrate affecting the collection of carriers, and hence the radiation-induced current peaks. It has been find out a decrease of the current peak due to the increase of the series resistance by non-ionizing energy loss in the semiconductor substrate, and an increase of the leakage current due to defects in the gate oxide by ionizing energy loss. For low levels of damage in the gate oxide, the main feature is the shift of the VTH. Hot carriers heated by the incident radiation in the depletion region and injected in the gate oxide cause the change of the VTH due to electron or hole trapping for n- or p-channel respectively. The overall results illustrate that these effects must be taken into consideration for an accurate reliability projection.

  14. Radiation detector

    DOEpatents

    Fultz, B.T.

    1980-12-05

    Apparatus is provided for detecting radiation such as gamma rays and x-rays generated in backscatter Moessbauer effect spectroscopy and x-ray spectrometry, which has a large window for detecting radiation emanating over a wide solid angle from a specimen and which generates substantially the same output pulse height for monoenergetic radiation that passes through any portion of the detection chamber. The apparatus includes a substantially toroidal chamber with conductive walls forming a cathode, and a wire anode extending in a circle within the chamber with the anode lying closer to the inner side of the toroid which has the least diameter than to the outer side. The placement of the anode produces an electric field, in a region close to the anode, which has substantially the same gradient in all directions extending radially from the anode, so that the number of avalanche electrons generated by ionizing radiation is independent of the path of the radiation through the chamber.

  15. Radiation detector

    DOEpatents

    Fultz, Brent T.

    1983-01-01

    Apparatus is provided for detecting radiation such as gamma rays and X-rays generated in backscatter Mossbauer effect spectroscopy and X-ray spectrometry, which has a large "window" for detecting radiation emanating over a wide solid angle from a specimen and which generates substantially the same output pulse height for monoenergetic radiation that passes through any portion of the detection chamber. The apparatus includes a substantially toroidal chamber with conductive walls forming a cathode, and a wire anode extending in a circle within the chamber with the anode lying closer to the inner side of the toroid which has the least diameter than to the outer side. The placement of the anode produces an electric field, in a region close to the anode, which has substantially the same gradient in all directions extending radially from the anode, so that the number of avalanche electrons generated by ionizing radiation is independent of the path of the radiation through the chamber.

  16. Diffuse radiation

    NASA Technical Reports Server (NTRS)

    1981-01-01

    A diffuse celestial radiation which is isotropic at least on a course scale were measured from the soft X-ray region to about 150 MeV, at which energy the intensity falls below that of the galactic emission for most galactic latitudes. The spectral shape, the intensity, and the established degree of isotropy of this diffuse radiation already place severe constraints on the possible explanations for this radiation. Among the extragalactic theories, the more promising explanations of the isotropic diffuse emission appear to be radiation from exceptional galaxies from matter antimatter annihilation at the boundaries of superclusters of galaxies of matter and antimatter in baryon symmetric big bang models. Other possible sources for extragalactic diffuse gamma radiation are discussed and include normal galaxies, clusters of galaxies, primordial cosmic rays interacting with intergalactic matter, primordial black holes, and cosmic ray leakage from galaxies.

  17. All-fibre ytterbium laser tunable within 45 nm

    SciTech Connect

    Abdullina, S R; Babin, S A; Vlasov, A A; Kablukov, S I; Shelemba, I S; Kurkov, A S

    2007-12-31

    A tunable ytterbium-doped fibre laser is fabricated. The laser is tuned by using a tunable fibre Bragg grating (FBG) as a selecting intracavity element. The laser is tunable within 45 nm (from 1063 to 1108 nm) and emits {approx}6 W in the line of width {approx}0.15 nm, the output power and linewidth being virtually invariable within the tuning range. The method is proposed for synchronous tuning the highly reflecting and output FBGs, and a tunable ytterbium all-fibre laser is built. (lasers)

  18. Spectropolarimetry of Atomic and Molecular Lines near 4135 nm

    NASA Astrophysics Data System (ADS)

    Penn, Matthew James; Uitenbroek, Han; Clark, Alan; Coulter, Roy; Goode, Phil; Cao, Wenda

    2016-10-01

    New spatially scanned spectropolarimetry sunspot observations are made of photospheric atomic and molecular absorption lines near 4135 nm. The relative splittings among several atomic lines are measured and shown to agree with values calculated with configuration interaction and intermediate coupling. Large splitting is seen in a line identified with Fe i at 4137 nm, showing multiple Stokes V components and an unusual linear polarization. This line will be a sensitive probe of quiet-Sun magnetic fields, with a magnetic sensitivity of 2.5 times higher than that of the well-known 1565 nm Fe i line.

  19. Spectropolarimetry of Atomic and Molecular Lines near 4135 nm

    NASA Astrophysics Data System (ADS)

    Penn, Matthew James; Uitenbroek, Han; Clark, Alan; Coulter, Roy; Goode, Phil; Cao, Wenda

    2016-09-01

    New spatially scanned spectropolarimetry sunspot observations are made of photospheric atomic and molecular absorption lines near 4135 nm. The relative splittings among several atomic lines are measured and shown to agree with values calculated with configuration interaction and intermediate coupling. Large splitting is seen in a line identified with Fe uc(i) at 4137 nm, showing multiple Stokes V components and an unusual linear polarization. This line will be a sensitive probe of quiet-Sun magnetic fields, with a magnetic sensitivity of 2.5 times higher than that of the well-known 1565 nm Fe uc(i) line.

  20. 80 nm tunable DBR-free semiconductor disk laser

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Albrecht, A. R.; Cederberg, J. G.; Sheik-Bahae, M.

    2016-07-01

    We report a widely tunable optically pumped distributed Bragg reflector (DBR)-free semiconductor disk laser with 6 W continuous wave output power near 1055 nm when using a 2% output coupler. Using only high reflecting mirrors, the lasing wavelength is centered at 1034 nm and can be tuned up to a record 80 nm by using a birefringent filter. We attribute such wide tunability to the unique broad effective gain bandwidth of DBR-free semiconductor disk lasers achieved by eliminating the active mirror geometry.

  1. The preventive effect of linalool on acute and chronic UVB-mediated skin carcinogenesis in Swiss albino mice.

    PubMed

    Gunaseelan, Srithar; Balupillai, Agilan; Govindasamy, Kanimozhi; Muthusamy, Ganesan; Ramasamy, Karthikeyan; Shanmugam, Mohana; Prasad, N Rajendra

    2016-07-01

    In this study, we evaluated the role of linalool in acute ultraviolet-B (UVB; 280-320 nm) radiation-induced inflammation and chronic UVB-mediated photocarcinogenesis in mouse skin. Acute UVB-irradiation (180 mJ cm(-2)) causes hyperplasia, edema formation, lipid peroxidation, antioxidant depletion, and overexpression of cyclooxygenase-2 (COX-2) and ornithine decarboxylase (ODC) in mouse skin. Topical or intraperitoneal (i.p.) treatment of linalool prevented acute UVB-induced hyperplasia, edema formation, lipid peroxidation, and antioxidant depletion in mouse skin. Further, linalool treatment prevented UVB-induced overexpression of COX-2 and ODC in mouse skin. In the chronic study, mice were subjected to UVB-exposure thrice weekly for 30 weeks. Chronic UVB-exposure induced tumor incidence and expression of proliferative markers such as NF-κB, TNF-α, IL-6, COX-2, VEGF, TGF-β1, Bcl-2 and mutated p53 in mouse skin. Treatment with linalool before each UVB-exposure significantly prevented the expression of these proliferative markers and subsequently decreased the tumor incidence in mice skin. Histopathological studies confirmed the development of dysplasia and squamous cell carcinoma (SCC) in the chronic UVB-exposed mouse skin; and this was prevented by both topical and i.p. linalool treatment. Therefore, linalool may be considered as a photochemopreventive agent against UVB radiation induced skin carcinogenesis.

  2. Absorption of ultraviolet radiation by antarctic phytoplankton

    SciTech Connect

    Vernet, M.; Mitchell, B.G. )

    1990-01-09

    Antarctic phytoplankton contain UV-absorbing compounds that may block damaging radiation. Compounds that absorb from 320-340 nm were observed in spectral absorption of both particulates and in methanol extracts of the particulates. The decrease in the total concentration of these UV compounds with respect to chlorophyll a, as measured by the ratio of in vitro absorption at 335 nm to absorption at 665 nm is variable and decreases with depth. We observed up to 5-fold decrease in this ratio for samples within the physically mixes surface layer. The absorption of UV radiation in methanol extracts, which peaks from 320 to 340 nm, may be composed of several compounds. Shifts in peak absorption with depth (for example, from 331 nm at surface to 321 nm at 75 m), may be interpreted as a change in composition. Ratios of protective yellow xanthophylls (diadinoxanthin + diatoxanthin) to photosynthetic fucoxanthin-like pigments have highest values in surface waters. As these pigments also absorb in the near UV, their function might extend to protection as well as utilization of UV radiation for photosynthesis. We document strong absorption in the UV from 320-330 nm for Antarctic marine particulates. Below this region of the solar energy spectrum, absolute energy levels of incident radiation drop off dramatically. Only wavelengths shorter than about 320 nm will be significantly enhanced due to ozone depletion. If the absorption we observed serves a protective role for phytoplankton photosynthesis, it appears the peak band is in the region where solar energy increases rapidly, and not in the region where depletion would cause significant variations in absolute flux.

  3. Efficient laser operation of Nd3+:Lu2O3 at various wavelengths between 917 nm and 1463 nm

    NASA Astrophysics Data System (ADS)

    von Brunn, P.; Heuer, A. M.; Fornasiero, L.; Huber, G.; Kränkel, C.

    2016-08-01

    Even though the first Nd3+-doped sesquioxide lasers have been realized more than 50 years ago, up to now no reports on efficient laser operation of Nd3+:doped sesquioxides can be found. In this work, we review the favorable spectroscopic properties of the sesquioxide Nd3+:Lu2O3 in terms of ground state absorption, stimulated emission, and excited state absorption cross sections as well as the upper level lifetime. Making use of these properties, we achieved efficient laser performance on eight different laser transitions in the wavelength range between 917 nm and 1463 nm under Ti:sapphire laser pumping using state-of-the-art HEM-grown Nd3+:Lu2O3 crystals with good optical quality. At the strongest transition around 1076 nm we determined a slope efficiency of 69%, which represents the highest efficiency ever obtained for a Nd3+-doped sesquioxide. Furthermore, we could generate watt level output powers and high slope efficiencies for seven other transitions. Lasers at 917 nm, 1053 nm, 1108 nm and 1463 nm were realized for the first time and the latter represents one of the longest laser wavelengths obtained on the 4F3/2  →  4I13/2 transition in Nd3+-doped materials.

  4. Absolute absorption cross sections of ozone at 300 K, 228 K and 195 K in the wavelength region 185-240 nm

    NASA Technical Reports Server (NTRS)

    Yoshino, K.; Parkinson, W. H.; Freeman, D. E.

    1992-01-01

    An account is given of progress of work on absorption cross section measurements of ozone at 300 K, 228 K and 195 K in the wavelength region 185-240 nm. In this wavelength region, the penetration of solar radiation into the Earth's atmosphere is controlled by O2 and O3. The transmitted radiation is available to dissociate trace species such as halocarbons and nitrous oxide. We have recently measured absolute absorption cross sections of O3 in the wavelength region 240-350 nm (Freeman et al., 1985; Yoshino et al., 1988). We apply these proven techniques to the determination of the absorption cross section of O3 at 300 K, 228 K and 195 K throughout the wavelength region 185-240 nm. A paper titled 'Absolute Absorption Cross Section Measurements of Ozone in the Wavelength Region 185-254 nm and the Temperature Dependence' has been submitted for publication in the Journal of Geophysical Research.

  5. Compact frequency-quadrupled pulsed 1030nm fiber laser

    NASA Astrophysics Data System (ADS)

    McIntosh, Chris; Goldberg, Lew; Cole, Brian; DiLazaro, Tom; Hays, Alan D.

    2016-03-01

    A compact 1030nm fiber laser for ultraviolet generation at 257.5nm is presented. The laser employs a short length of highly-doped, large core (20μm), coiled polarization-maintaining ytterbium-doped double-clad fiber pumped by a wavelength-stabilized 975nm diode. It is passively Q-switched via a Cr4+:YAG saturable absorber and generates 2.4W at 1030nm in a 110μJ pulse train. Lithium triborate (LBO) and beta-barium borate (BBO) are used to achieve 325mW average power at the fourth harmonic. The laser's small form factor, narrow linewidth and modest power consumption are suitable for use in a man-portable ultraviolet Raman explosives detection system.

  6. 980 nm narrow linewidth Yb-doped phosphate fiber laser

    NASA Astrophysics Data System (ADS)

    Li, Pingxue; Yao, Yifei; Hu, Haowei; Chi, Junjie; Yang, Chun; Zhao, Ziqiang; Zhang, Guangju

    2014-12-01

    A narrow-linewidth ytterbium (Yb)-doped phosphate fiber laser based on fiber Bragg grating (FBG) operating around 980 nm is reported. Two different kinds of cavity are applied to obtain the 980 nm narrow-linewidth output. One kind of the cavity consists of a 0.35 nm broadband lindwidth high-reflection FBG and the Yb-doped phosphate fiber end with 0° angle, which generates a maximum output power of 25 mW. The other kind of resonator is composed of a single mode Yb-doped phosphate fiber and a pair of FBGs. Over 10.7 mW stable continuous wave are obtained with two longitudinal modes at 980 nm. We have given a detailed analysis and discussion for the results.

  7. Absolute measurement of F2-laser power at 157 nm

    SciTech Connect

    Kueck, Stefan; Brandt, Friedhelm; Kremling, Hans-Albert; Gottwald, Alexander; Hoehl, Arne; Richter, Mathias

    2006-05-10

    We report a comparison of laser power measurements at the F2-laser wavelength oaf nm made at two facilities of the Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute. At the PTB laboratory at the electron storage ring BESSY II in Berlin, the scale for laser power was directly traced to a cryogenic radiometer operating at 157 nm, whereas at the PTB laser radiometry facility in Braunschweig the calibration of transfer detectors was performed with a newly developed standard for laser power at 157 nm, which is traceable in several steps to a cryogenic radiometer operating at 633 nm. The comparison was performed under vacuum conditions with laser pulse energies of?10 {mu}J, however with different average powers because different primary standard radiometers were used. The relative deviation for the responsivity of the transfer detector was 4.8% and thus within the combined standard uncertainty.

  8. Immersion and 32nm lithography: now and future

    NASA Astrophysics Data System (ADS)

    Kameyama, Masaomi; McCallum, Martin

    2007-12-01

    The amazing growth of the semiconductor industry over the past decades has been supported, and in many cases driven, by miniaturization of devices. Behind this has been one strong backbone - lithography. In the 1970's, devices had geometries of several micrometers, but now we are about to enter 45nm device pre-production and shortly after move it into volume-production. Immersion lithography, although having a short development time, is already in production and will become the primary technology driver. What we need to do now is identify the solutions for 32nm lithography. There are several candidates for 32nm lithography, such as EUVL, High Index Immersion and Double Patterning / Double Exposure. Other more esoteric technologies such as nanoimprint and maskless lithography have also been mentioned. In this paper, the present status of Immersion lithography will be reviewed and each of the 32nm candidates are reviewed.

  9. Determination of complex index of immersion liquids at 193 nm

    NASA Astrophysics Data System (ADS)

    Stehle, Jean-Louis; Piel, Jean-Philippe; Campillo-Carreto, Jose

    2006-03-01

    The next nodes in immersion lithography will require the scanners to use the 193 nm ArF* laser line with a very large numerical aperture and a liquid between the optics and the resist. (1) Immersion lithography at 193 nm requests very specific parameters for the fluid. The first generation is using the deionized Water (DIW) very pure and not recycled, but when a new optical material for the last lens will be available with a refractive index (RI) larger than 1.85, a higher refractive index fluid could be used, enabling second and maybe third generation of immersion lithography at 193 nm. So the 45 and maybe the 32 nm nodes could be covered with this high Index fluids (HIF).

  10. The Missing Solar Irradiance Spectrum: 1 to 7 nm

    NASA Astrophysics Data System (ADS)

    Sojka, J. J.; Lewis, M.; David, M.; Schunk, R. W.; Woods, T. N.; Eparvier, F. G.; Warren, H. P.

    2015-12-01

    During large X-class flares the Earth's upper atmospheric E-region responds immediately to solar photons in the 1 to 7 nm range. The response can change the E-region density by factors approaching 10, create large changes in conductivity, and plague HF communications. GOES-XRS provide 0.1 to 0.8 nm and a 0.05 to 0.4 nm integral channels; SOHO-SEM provided a 0 to 50 nm irradiance; TIMED and SORCE-XPS diode measurements also integrated down to 0.1 nm; and most recently SDO-EVE provided a 0.1 to 7 nm irradiance. For atmospheric response to solar flares the cadence is also crucial. Both GOES and SDO provided integral measurements at 10 seconds or better. Unfortunately these measurements have failed to capture the 1 to 7 nm spectral changes that occur during flares. It is these spectral changes that create the major impact since the ionization cross-section of the dominant atmospheric species, N2 and O2, both contain step function changes in the cross-sections. Models of the solar irradiance over this critical wavelength regime have suffered from the need to model the spectral variability based on incomplete measurements. The most sophisticated empirical model FISM [Chamberlin et al., 2008] used 1 nm spectral binning and various implementations of the above integral measurements to describe the 1 to 7 nm irradiance. Since excellent solar observations exist at other wavelengths it is possible to construct an empirical model of the solar atmosphere and then use this model to infer the spectral distribution at wavelengths below 5 nm. This differential emission measure approach has been used successfully in other contexts [e.g., Warren, 2005, Chamberlin et al., 2009]. This paper contrasts the broadband versus spectrally resolved descriptions of the incoming irradiance that affects the upper atmospheric E-layer. The results provide a prescription of what wavelength resolution would be needed to adequately measure the incoming solar irradiance in the 1 to 7 nm range.

  11. Low-k/copper integration scheme suitable for ULSI manufacturing from 90nm to 45nm nodes

    NASA Astrophysics Data System (ADS)

    Nogami, T.; Lane, S.; Fukasawa, M.; Ida, K.; Angyal, M.; Chanda, K.; Chen, F.; Christiansen, C.; Cohen, S.; Cullinan, M.; Dziobkowski, C.; Fitzsimmons, J.; Flaitz, P.; Grill, A.; Gill, J.; Inoue, K.; Klymko, N.; Kumar, K.; Labelle, C.; Lane, M.; Li, B.; Liniger, E.; Madon, A.; Malone, K.; Martin, J.; McGahay, V.; McLaughlin, P.; Melville, I.; Minami, M.; Molis, S.; Nguyen, S.; Penny, C.; Restaino, D.; Sakamoto, A.; Sankar, M.; Sherwood, M.; Simonyi, E.; Shimooka, Y.; Tai, L.; Widodo, J.; Wildman, H.; Ono, M.; McHerron, D.; Nye, H.; Davis, C.; Sankaran, S.; Edelstein, D.; Ivers, T.

    2005-11-01

    This paper discusses low-k/copper integration schemes which has been in production in the 90 nm node, have been developed in the 65 nm node, and should be taken in the 45 nm node. While our baseline 65 nm BEOL process has been developed by extension and simple shrinkage of our PECVD SiCOH integration which has been in production in the 90 nm node with our SiCOH film having k=3.0, the 65 nm SiCOH integration has two other options to go to extend to lower capacitance. One is to add porosity to become ultra low-k (ULK). The other is to stay with low-k SiCOH, which is modified to have a "lower-k". The effective k- value attained with the lower-k (k=2.8) SiCOH processed in the "Direct CMP" scheme is very close to that with an ULK (k=2.5) SiCOH film built with the "Hard Mask Retention" scheme. This paper first describes consideration of these two damascene schemes, whose comparison leads to the conclusion that the lower-k SiCOH integration can have more advantages in terms of process simplicity and extendibility of our 90 nm scheme under certain assumptions. Then describing the k=2.8 SiCOH film development and its successful integration, damascene schemes for 45nm nodes are discussed based on our learning from development of the lower-k 65nm scheme. Capability of modern dry etchers to define the finer patterns, non-uniformity of CMP, and susceptibility to plasma and mechanical strength and adhesion of ULK are discussed as factors to hamper the applicability of ULK.

  12. A Compact "Water Window" Microscope with 60 nm Spatial Resolution for Applications in Biology and Nanotechnology.

    PubMed

    Wachulak, Przemyslaw; Torrisi, Alfio; Nawaz, Muhammad F; Bartnik, Andrzej; Adjei, Daniel; Vondrová, Šárka; Turňová, Jana; Jančarek, Alexandr; Limpouch, Jiří; Vrbová, Miroslava; Fiedorowicz, Henryk

    2015-10-01

    Short illumination wavelength allows an extension of the diffraction limit toward nanometer scale; thus, improving spatial resolution in optical systems. Soft X-ray (SXR) radiation, from "water window" spectral range, λ=2.3-4.4 nm wavelength, which is particularly suitable for biological imaging due to natural optical contrast provides better spatial resolution than one obtained with visible light microscopes. The high contrast in the "water window" is obtained because of selective radiation absorption by carbon and water, which are constituents of the biological samples. The development of SXR microscopes permits the visualization of features on the nanometer scale, but often with a tradeoff, which can be seen between the exposure time and the size and complexity of the microscopes. Thus, herein, we present a desk-top system, which overcomes the already mentioned limitations and is capable of resolving 60 nm features with very short exposure time. Even though the system is in its initial stage of development, we present different applications of the system for biology and nanotechnology. Construction of the microscope with recently acquired images of various samples will be presented and discussed. Such a high resolution imaging system represents an interesting solution for biomedical, material science, and nanotechnology applications.

  13. High-resolution defect inspection of step-and-flash imprint lithography for 32-nm half-pitch patterning

    NASA Astrophysics Data System (ADS)

    Selinidis, Kosta; Thompson, Ecron; McMackin, Ian; Sreenivasan, S. V.; Resnick, Douglas J.

    2009-03-01

    Step and Flash Imprint involves the field-by-field deposition and exposure of a low viscosity resist deposited by jetting technology onto the substrate. The patterned mask is lowered into the fluid which then quickly flows into the relief patterns in the mask by capillary action. Following this filling step, the resist is crosslinked under UV radiation, and then the mask is removed leaving a patterned solid on the substrate. Compatibility with existing CMOS processes requires a mask infrastructure in which resolution, inspection and repair are all addressed. The purpose of this paper is to understand the limitations of inspection at half pitches of 32 nm and below. A 32 nm programmed defect mask was fabricated. Patterns included in the mask consisted of an SRAM Metal 1 cell, dense lines, and dense arrays of pillars. Programmed defect sizes started at 4 nm and increased to 48 nm in increments of 4 nm. Defects in both the mask and imprinted wafers were characterized scanning electron microscopy and the measured defect areas were calculated. These defects were then inspected using KLA-T eS35 and NGR2100 electron beam wafer inspection systems. Defect sizes as small as 8 nm were detected, and detection limits were found to be a function of defect type.

  14. Laser Imprint Reduction Using a Low-Density Foam Buffer as a Thermal Smoothing Layer at 351-nm Wavelength

    NASA Astrophysics Data System (ADS)

    Watt, R. G.; Duke, J.; Fontes, C. J.; Gobby, P. L.; Hollis, R. V.; Kopp, R. A.; Mason, R. J.; Wilson, D. C.; Verdon, C. P.; Boehly, T. R.; Knauer, J. P.; Meyerhofer, D. D.; Smalyuk, V.; Town, R. P.; Iwase, A.; Willi, O.

    1998-11-01

    Laser-nonuniformity-induced perturbation growth has been measured on planar foam-buffered plastic (CH) targets irradiated with 351-nm laser radiation. The maximum observed perturbation growth was reduced by about 50% by the foam buffer. Rayleigh-Taylor unstable growth of intentional mass modulations was minimally changed by the addition of the foam buffer. We conclude that the reduction of laser-induced perturbation growth is a result of a reduction in the perturbation seed amplitude rather than any changes in the growth rate in the solid due to preheating by radiation or shocks caused by the presence of the foam buffer.

  15. Photoionization branching ratios and vibrational intensity distribution for N2, CO; and CO2 between 53 and 75 nm

    NASA Technical Reports Server (NTRS)

    Samson, J. A. R.; Gardner, J. L.

    1973-01-01

    The probability of radiation producing ions in specific electronic and vibrational levels was documented. For example, when a narrow band-pass of solar ionizing photons is incident on an atmospheric species it is now possible to describe, accurately, how the radiant energy is shared among the various electronic states of the ions produced. The molecules studied were N2, CO, and CO2. These molecules were photoionized by radiation between 53 and 75 nm. The effects of autoionization are discussed and continuum vibrational intensities are tabulated and compared with theoretical Franck-Condon factors where available. The branching ratios and partial cross sections for ionization into various electronic states are tabulated.

  16. High efficiency 1341 nm Nd:GdVO4 laser in-band pumped at 912 nm

    NASA Astrophysics Data System (ADS)

    Li, Y. L.; Liu, J. Y.; Zhang, Y. C.

    2012-03-01

    A high-efficiency 1341 nm Nd:GdVO4 laser in-band pumped at 912 nm is demonstrated for the first time. Using an all-solid-state Nd:GdVO4 laser operating at 912 nm as pump source, 542 mW output was obtained with 1.14 W absorbed pump power. The slope efficiency with respect to the absorbed pump power was 56.6%, and the fluctuation of the output power was better than 2.6% in the given 30 min. The beam quality factor M 2 is 1.15.

  17. Revisit pattern collapse for 14nm node and beyond

    NASA Astrophysics Data System (ADS)

    Yoshimoto, Kenji; Higgins, Craig; Raghunathan, Ananthan; Hartley, John G.; Goldfarb, Dario L.; Kato, Hirokazu; Petrillo, Karen; Colburn, Matthew E.; Schefske, Jeffrey; Wood, Obert; Wallow, Thomas I.

    2011-04-01

    In this study, we have analyzed new data sets of pattern collapse obtained from 300 mm wafers which were coated with a process-of-record (POR) EUV resist and exposed by an EUV Alpha-Demo tool (ADT) and a Vistec VB300 e-beam exposure tool. In order to minimize any processing effects on pattern collapse, the same POR EUV track process was applied to both exposures. A key metric of our analysis is the critical aspect ratio of collapse (CARC)1. We found that CARC of POR EUV resist decreases monotonically with spacing, in the range of ~1.8-2.2 at ~32-54 nm space (60-80 nm pitch) for EUV, and ~1.5-2.1 at ~16-50 nm space (~46-80 nm pitch) for e-beam. We also estimated an apparent Young's modulus of POR EUV resist by fitting a collapse model2 to the CARC data. The resulting modulus ~0.30 GPa was much smaller than the modulus of typical polymer glasses (~1.0-5.0 GPa). Our findings suggest that due to a significant decrease of resist mechanical properties and a sharp increase in capillary force, it will be challenging to maintain aspect ratios above 2.0 for sub-30 nm resist spacing (sub-60 nm pitches). For patterning at these dimensions, alternate processes and materials will become increasingly necessary, e.g. surfactant-based rinse solutions3 and other approaches.

  18. Magneto-optical trap for metastable helium at 389 nm

    SciTech Connect

    Koelemeij, J.C.J.; Stas, R.J.W.; Hogervorst, W.; Vassen, W.

    2003-05-01

    We have constructed a magneto-optical trap (MOT) for metastable triplet helium atoms utilizing the 2 {sup 3}S{sub 1}{yields}3 {sup 3}P{sub 2} line at 389 nm as the trapping and cooling transition. The far-red-detuned MOT (detuning {delta}=-41 MHz) typically contains few times 10{sup 7} atoms at a relatively high ({approx}10{sup 9} cm{sup -3}) density, which is a consequence of the large momentum transfer per photon at 389 nm and a small two-body loss rate coefficient (2x10{sup -10} cm{sup 3}/s<{beta}<1.0x10{sup -9} cm{sup 3}/s). The two-body loss rate is more than five times smaller than in a MOT on the commonly used 2 {sup 3}S{sub 1}{yields}2 {sup 3}P{sub 2} line at 1083 nm. Furthermore, laser cooling at 389 nm results in temperatures somewhat lower than those achieved using 1083 nm. The 389-nm MOT exhibits small losses due to two-photon ionization, which have been investigated as well.

  19. Alternatives to chemical amplification for 193nm lithography

    NASA Astrophysics Data System (ADS)

    Baylav, Burak; Zhao, Meng; Yin, Ran; Xie, Peng; Scholz, Chris; Smith, Bruce; Smith, Thomas; Zimmerman, Paul

    2010-04-01

    Research has been conducted to develop alternatives to chemically amplified 193 nm photoresist materials that will be able to achieve the requirements associated with sub-32 nm device technology. New as well as older photoresist design concepts for non-chemically amplified 193 nm photoresists that have the potential to enable improvements in line edge roughness while maintaining adequate sensitivity, base solubility, and dry etch resistance for high volume manufacturing are being explored. The particular platforms that have been explored in this work include dissolution inhibitor photoresist systems, chain scissioning polymers, and photoresist systems based on polymers incorporating formyloxyphenyl functional groups. In studies of two-component acidic polymer/dissolution inhibitor systems, it was found that compositions using ortho-nitrobenzyl cholate (NBC) as the dissolution inhibitor and poly norbornene hexafluoro alcohol (PNBHFA) as the base resin are capable of printing 90 nm dense line/space patterns upon exposure to a 193 nm laser. Studies of chain scission enhancement in methylmethacrylate copolymers showed that incorporating small amounts of absorptive a-cleavage monomers significantly enhanced sensitivity with an acceptable increase in absorbance at 193 nm. Specifically, it was found that adding 3 mol% of α-methyl styrene (α-MS) reduced the dose to clear of PMMA-based resist from 1400 mJ/cm2 to 420 mJ/cm2. Preliminary data are also presented on a direct photoreactive design concept based on the photo-Fries reaction of formyloxyphenyl functional groups in acrylic copolymers.

  20. Application of atomic force microscope to 65-nm node photomasks

    NASA Astrophysics Data System (ADS)

    Tanaka, Yoshiyuki; Itou, Yasutoshi; Yoshioka, Nobuyuki; Matsuyama, Katsuhiro; Dawson, Dean J.

    2004-08-01

    The technology node of semiconductor device production is progressing to 65nm generation. For the 65nm photomasks, the target specifications of defect size and repair accuracy are 52nm and 7nm, respectively. Especially, real defects on photomasks are not only simple two-dimensional patterns but also three-dimensional shapes such as phase shift defects and contamination, thus we need to recognize defect shapes accurately. Additionally, AAPSM's Cr patterns overhang, and we have to measure defects on three-dimensional shapes. To evaluate them, we use an AFM metrology system, Dimension X3D (Veeco), having both precise CD measurement repeatability (2nm) and high resolution for defects. In this report, we show the performance of the AFM metrology system. First, we evaluated CD metrology performance, CD repeatbility about four type photomasks: NEGA-BIM, POSI-BIM, KrF-HT and ArF-HT, and all masks met specifications. Next, we evaluated defect pattern shapes and AAPSM and CPL mask patterns. Consequently, we have confirmed that the AFM metrology system has high performance for 65nm photomasks.

  1. Radiation dosimeter

    DOEpatents

    Fox, Richard J.

    1983-01-01

    A radiation detector readout circuit is provided which produces a radiation dose-rate readout from a detector even though the detector output may be highly energy dependent. A linear charge amplifier including an output charge pump circuit amplifies the charge signal pulses from the detector and pumps the charge into a charge storage capacitor. The discharge rate of the capacitor through a resistor is controlled to provide a time-dependent voltage which when integrated provides an output proportional to the dose-rate of radiation detected by the detector. This output may be converted to digital form for readout on a digital display.

  2. Radiation dosimeter

    DOEpatents

    Fox, R.J.

    1981-09-01

    A radiation detector readout circuit is provided which produces a radiation dose-rate readout from a detector even through the detector output may be highly energy dependent. A linear charge amplifier including an output charge pump circuit amplifies the charge signal pulses from the detector and pumps the charge into a charge storage capacitor. The discharge rate of the capacitor through a resistor is controlled to provide a time-dependent voltage which when integrated provides an output proportional to the dose-rate of radiation detected by the detector. This output may be converted to digital form for readout on a digital display.

  3. Radiation Hydrodynamics

    SciTech Connect

    Castor, J I

    2003-10-16

    The discipline of radiation hydrodynamics is the branch of hydrodynamics in which the moving fluid absorbs and emits electromagnetic radiation, and in so doing modifies its dynamical behavior. That is, the net gain or loss of energy by parcels of the fluid material through absorption or emission of radiation are sufficient to change the pressure of the material, and therefore change its motion; alternatively, the net momentum exchange between radiation and matter may alter the motion of the matter directly. Ignoring the radiation contributions to energy and momentum will give a wrong prediction of the hydrodynamic motion when the correct description is radiation hydrodynamics. Of course, there are circumstances when a large quantity of radiation is present, yet can be ignored without causing the model to be in error. This happens when radiation from an exterior source streams through the problem, but the latter is so transparent that the energy and momentum coupling is negligible. Everything we say about radiation hydrodynamics applies equally well to neutrinos and photons (apart from the Einstein relations, specific to bosons), but in almost every area of astrophysics neutrino hydrodynamics is ignored, simply because the systems are exceedingly transparent to neutrinos, even though the energy flux in neutrinos may be substantial. Another place where we can do ''radiation hydrodynamics'' without using any sophisticated theory is deep within stars or other bodies, where the material is so opaque to the radiation that the mean free path of photons is entirely negligible compared with the size of the system, the distance over which any fluid quantity varies, and so on. In this case we can suppose that the radiation is in equilibrium with the matter locally, and its energy, pressure and momentum can be lumped in with those of the rest of the fluid. That is, it is no more necessary to distinguish photons from atoms, nuclei and electrons, than it is to distinguish

  4. Electromagnetic radiation emitted from video computer terminals.

    PubMed

    Weiss, M M; Petersen, R C

    1979-04-01

    There has been a developing concern about potential health hazards attributable to electromagnetic radiation from video computer terminals. Since users of these devices typically spend many hours daily in close proximity, they would be subject to chronic long-term exposures to any emitted radiation. Radiation was detected at frequencies ranging from 1.5 kHz to 1,420 MHz in the RF portion of the EM spectrum and from 350 nm to 600 nm in the ultraviolet and visible region. However, the levels were far less than the most restrictive permissible exposure levels established by any agency or government of any nation. There is no experimental or epidemiological evidence presently available to indicate that these levels of RF radiation have any deleterious effects on the human biological system.

  5. Surface modification of polyhedral oligomeric silsesquioxane block copolymer films by 157 nm laser light

    NASA Astrophysics Data System (ADS)

    Sarantopoulou, Evangelia; Kollia, Zoe; Cefalas, Alkiviadis Constantinos; Siokou, Ageliki Elina; Argitis, Panagiotis; Bellas, Vassilios; Kobe, Spomenka

    2009-06-01

    Thin films of ethyl polyhedral oligomeric silsesquioxane (ethyl-POSS) containing polymers at different compositions were chemically modified using laser irradiation at 157 nm. The irradiation caused photodissociation of C-O and C-H bonds followed by the formation of new chemical bonds. The content of Si-O and C-O bonds increased, as did the surface hardness. Vacuum ultraviolet (VUV) absorption, mass spectrometry, x-ray photoelectron spectroscopy, and atomic force microscopy imaging and indentation were used to evaluate the effects of the 157 nm irradiation. The chemical modification was restricted to a thin surface layer. The layer depth was determined by the penetration depth of the 157 nm VUV photons inside the thin copolymer layer. With prolonged VUV irradiation, the absorbance of the polymers increased, eventually becoming saturated. The chemical changes were accompanied by surface hardening, as evidenced by the increase in the Young's modulus from 4 to 24 GPa due to glassification of the irradiated parts. The chemically modified layer acts as a shield against photodissociation and degradation of the deeper portion of the POSS polymer by VUV radiation. Applications include the protection of solar cells on low orbit satellites from solar VUV photons.

  6. Ocular aberrations up to the infrared range: from 632.8 to 1070 nm.

    PubMed

    Fernández, Enrique J; Artal, Pablo

    2008-12-22

    Ocular aberrations were measured by using a Hartmann-Shack wavefront sensor in the visible and infrared portions of the spectrum. In the latter, wavelengths 1030, 1050 and 1070 nm were used for the first time for the study of the optical quality of the eye. In this spectral range the retinal photoreceptors barely respond, so the radiation is virtually invisible for the subject. The results were confronted with those obtained by the same system at 780 and 632.8 nm. Monochromatic aberrations were found to be similar from the visible to the infrared. Longitudinal chromatic aberration was experimentally obtained, being approximately 1 D from 632.8 to 1070 nm. The feasibility of using the infrared for studying the eye was demonstrated. The employment of the infrared has an enormous potential for the better understanding of the impact and influence of the aberrations in vision with adaptive optics. It allows for measuring and controlling aberrations whilst the subject might eventually perform visual tests, with no interference from the beacon light.

  7. Performance of multilayer optical coatings under long-term 532nm laser exposure

    NASA Astrophysics Data System (ADS)

    Poulios, D.; Konoplev, O.; Chiragh, F.; Vasilyev, A.; Stephen, M.; Strickler, K.

    2013-11-01

    The effects of long-term exposure to high intensity 532 nm radiation on various dielectric-coated optics are studied. To investigate potential photodarkening effects on optical surfaces, an accelerated life test platform was constructed where optics were exposed to 532 nm radiation from a short-pulse, high repetition rate fiber amplifier at total doses up to 1 trillion shots. The first run of trillion-shot tests were conducted on e-beam deposited and ion beam sputtering (IBS) coated high reflecting mirrors with onsurface intensities ranging from 1.0-1.4 GW/cm2. It was found that the e-beam coated mirrors failed catastrophically at less than 150 billion shots, while the IBS coated mirror was able to complete the trillionshot test with no measurable loss of reflectivity. Profiling the IBS mirror surface with a high-resolution white light interferometer post-irradiation revealed a ~10 nm high photocontamination deposit at the irradiation site that closely matched the intensity profile of the laser spot. Trillion-shot surface exposure tests were also conducted at multiple surface sites of an LBO frequency doubling crystal at ~1.5 GW/cm2 at multiple surface sites. The transmitted power and on-surface beam size were monitored throughout the tests, and periodic measurements of the beam quality and waist location of the transmitted light were also made using an M2 meter. No changes in transmitted power or M2 were observed in any of the tests, but 3D surface profiling revealed laser-induced contamination deposits at each site tested.

  8. Healthful radiation.

    PubMed

    Agard, E T

    1997-01-01

    This title of this article sounds paradoxical to most people because the general public is not fully aware of the many benefits radiation has brought to people's healthcare. Radiation has provided the most effective means of noninvasive diagnosis of many diseases, thus reducing the need for exploratory surgery, at significantly reduced risks. Furthermore, radiotherapy has been effective in treating many diseases without surgical removal of the diseased part. The breast is one excellent example of the benefits of radiation in both diagnosis and treatment with preservation. Yet the public still regards radiation as mysterious and dangerous, while trained experts regard it as beneficial with manageable risks. This article suggests ways of presenting this material to the public in a manner that is interesting and informative. PMID:8972833

  9. Radiation sickness

    MedlinePlus

    ... process so that they do not cause radiation injury to others. This may complicate the first aid and resuscitation process. Check the person's breathing and pulse. Start CPR , if necessary. Remove the person's clothing and place ...

  10. Healthful radiation

    SciTech Connect

    Agard, E.T.

    1997-01-01

    This title of this article sounds paradoxical to most people because the general public is not fully aware of the many benefits radiation has brought to people`s healthcare. Radiation has provided the most effective means of noninvasive diagnosis of many diseases, thus reducing the need for exploratory surgery, at significantly reduced risks. Furthermore, radiotherapy has been effective in treating many diseases without surgical removal of the diseased part. The breast is one excellent example of the benefits of radiation in both diagnosis and treatment with preservation. Yet the public still regards radiation as mysterious and dangerous, while trained experts regard it as beneficial with manageable risks. This article suggests ways of presenting this material to the public in a manner that is interesting and informative. 11 refs.

  11. Radiation Therapy

    MedlinePlus

    ... Radiation (also called x-rays, gamma rays, or photons) either kills tumor cells directly or interferes with ... treatment per day, five days a week, for two to seven weeks. Potiential Side Effects Most people ...

  12. Highly efficient continuous-wave 912 nm Nd:GdVO4 laser emission under direct 880 nm pumping

    NASA Astrophysics Data System (ADS)

    Lü, Y. F.; Zhang, X. H.; Xia, J.; Zhang, A. F.; Yin, X. D.; Bao, L.

    2009-11-01

    The quasi-three-level 912 nm continuous-wave laser emission under direct diode laser pumping at 880 nm into emitting level 4F3/2 of Nd:GdVO4 have been demonstrated. An end-pumped Nd:GdVO4 crystal yielded 8.1 W of output power for 13.9 W of absorbed pump power. The slope efficiency with respect to the absorbed pump power was 0.679. To the best of our knowledge this is the first demonstration of such a laser system. Comparative results obtained for the pump with diode laser at 808 nm, into the highly-absorbing 4F5/2 level, are given in order to prove the advantages of the 880 nm wavelength pumping.

  13. 750 nm 1.5 W frequency-doubled semiconductor disk laser with a 44 nm tuning range.

    PubMed

    Saarinen, Esa J; Lyytikäinen, Jari; Ranta, Sanna; Rantamäki, Antti; Sirbu, Alexei; Iakovlev, Vladimir; Kapon, Eli; Okhotnikov, Oleg G

    2015-10-01

    We demonstrate 1.5 W of output power at the wavelength of 750 nm by intracavity frequency doubling a wafer-fused semiconductor disk laser diode-pumped at 980 nm. An optical-to-optical efficiency of 8.3% was achieved using a bismuth borate crystal. The wavelength of the doubled emission could be tuned from 720 to 764 nm with an intracavity birefringent plate. The beam quality parameter M2 of the laser output was measured to be below 1.5 at all pump powers. The laser is a promising tool for biomedical applications that can take advantage of the large penetration depth of light in tissue in the 700-800 nm spectral range.

  14. The Spectrum of Th-Ar Hollow Cathode Lamps in the 691nm to 5804nm region Database

    National Institute of Standards and Technology Data Gateway

    SRD 161 The Spectrum of Th-Ar Hollow Cathode Lamps in the 691nm to 5804nm region Database (Web, free access)   This atlas presents observations of the infra-red (IR) spectrum of a low current Th-Ar hollow cathode lamp with the 2-m Fourier transform spectrometer (FTS) at NIST. These observations establish more than 2400 lines that are suitable for use as wavelength standards in the range 691 nm to 5804 nm. The observations were made in collaboration with the European Southern Observatory (ESO), in order to provide calibration reference data for new high-resolution Echelle spectrographs, such as the Cryogenic High-Resolution IR Echelle Spectrograph ([CRIRES]), ESO's new IR spectrograph at the Very Large Telescope in Chile.

  15. 750 nm 1.5 W frequency-doubled semiconductor disk laser with a 44 nm tuning range.

    PubMed

    Saarinen, Esa J; Lyytikäinen, Jari; Ranta, Sanna; Rantamäki, Antti; Sirbu, Alexei; Iakovlev, Vladimir; Kapon, Eli; Okhotnikov, Oleg G

    2015-10-01

    We demonstrate 1.5 W of output power at the wavelength of 750 nm by intracavity frequency doubling a wafer-fused semiconductor disk laser diode-pumped at 980 nm. An optical-to-optical efficiency of 8.3% was achieved using a bismuth borate crystal. The wavelength of the doubled emission could be tuned from 720 to 764 nm with an intracavity birefringent plate. The beam quality parameter M2 of the laser output was measured to be below 1.5 at all pump powers. The laser is a promising tool for biomedical applications that can take advantage of the large penetration depth of light in tissue in the 700-800 nm spectral range. PMID:26421536

  16. Difference-frequency mixing in AgGaS(2) by use of a high-power GaAlAs tapered semiconductor amplifier at 860 nm.

    PubMed

    Simon, U; Tittel, F K; Goldberg, L

    1993-11-15

    As much as 47 microW of cw infrared radiation and 89 microW of pulsed infrared radiation, tunable near 4.3 microm, have been generated by mixing the outputs of a high-power tapered semiconductor amplifier at 858 nm (signal wave) and a Ti:Al(2)O(3) laser at 715 nm (pump wave) in AgGaS(2). The GaAlAs tapered traveling-wave amplifier delivered as much as 1.5 W of diffraction-limited cw power into the nonlinear crystal. Output powers, conversion efficiencies, and spectral characteristics of this novel midinfrared source are discussed. PMID:19829451

  17. Radiation Transport

    SciTech Connect

    Urbatsch, Todd James

    2015-06-15

    We present an overview of radiation transport, covering terminology, blackbody raditation, opacities, Boltzmann transport theory, approximations to the transport equation. Next we introduce several transport methods. We present a section on Caseology, observing transport boundary layers. We briefly broach topics of software development, including verification and validation, and we close with a section on high energy-density experiments that highlight and support radiation transport.

  18. Radiation Sensor

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Claypack is a cost-effective portable system developed by Barringer Research Ltd. for rapid on-site analysis of clay minerals. It is an adaptation of a hand-held rationing radiometer. By measuring the intensity of reflected radiation, the device discriminates among different minerals present in a sample. It simultaneously analyzes radiation intensities in two separate bands of the spectrum, and calculates the ratio of one to the other. The "reflectance ratio" is computer processed and displayed in digital form.

  19. Compact Fiber Laser for 589nm Laser Guide Star Generation

    NASA Astrophysics Data System (ADS)

    Pennington, D.; Drobshoff, D.; Mitchell, S.; Brown, A.

    Laser guide stars are crucial to the broad use of astronomical adaptive optics, because they facilitate access to a large fraction of possible locations on the sky. Lasers tuned to the 589 nm atomic sodium resonance can create an artificial beacon at altitudes of 95-105 km, thus coming close to reproducing the light path of starlight. The deployment of multiconjugate adaptive optics on large aperture telescopes world-wide will require the use of three to nine sodium laser guide stars in order to achieve uniform correction over the aperture with a high Strehl value. Current estimates place the minimum required laser power at > 10 W per laser for a continuous wave source, though a pulsed format, nominally 6?s in length at ~ 16.7 kHz, is currently preferred as it would enable tracking the laser through the Na layer to mitigate spot elongation. The lasers also need to be compact, efficient, robust and turnkey. We are developing an all-fiber laser system for generating a 589 nm source for laser-guided adaptive optics. Fiber lasers are more compact and insensitive to alignment than their bulk laser counterparts, and the heat-dissipation characteristics of fibers, coupled with the high efficiencies demonstrated and excellent spatial mode characteristics, make them a preferred candidate for many high power applications. Our design is based on sum-frequency mixing an Er/Yb:doped fiber laser operating at 1583 nm with a 938 nm Nd:silica fiber laser in a periodically poled crystal to generate 589 nm. We have demonstrated 14 W at 1583 nm with an Er/Yb:doped fiber laser, based on a Koheras single frequency fiber oscillator amplified in an IPG Photonics fiber amplifier. The Nd:silica fiber laser is a somewhat more novel device, since the Nd3+ ions must operate on the resonance transition (i.e. 4F3/2-4I9/2), while suppressing ASE losses at the more conventional 1088 nm transition. Optimization of the ratio of the fiber core and cladding permits operation of the laser at room

  20. Measurements of Photoabsorpton Cross Sections and their Temperature Dependence for CO2 in the 170nm to 200nm Region

    NASA Astrophysics Data System (ADS)

    Parkinson, W. H.; Yoshino, K.

    2001-11-01

    All the photochemical models for the predominately CO2 Martian atmosphere ar e very sensitive to the amount of CO2 and to the values and spectral details of the absorpton cross sections of CO2 in the region 170nm-200nm. Earlier we had measured and published absolute cross sections of CO2 in the region 118.0 nm-175.5 nm at 295K and 195K. We have recently extended these measurements from 170 nm to 200 nm at 300K and 1 95K. The new measurements have been carried out at high resolution with our 6.65 -m normal incidence , photoelectric spectrometer. To measure the weak photoabsorption of the CO2 bands in the wavelength region 170 --200 nm, we required a high column density of the gas. We obtained this by using a multi pass technique, a White cell. The White cell was designed to have a distance of 1.50 m between two main mirrors, and was set for four, double pas ses making a path length of 12.0 m. CO2 gas was frozen in a stainless cylinder immersed in liquid nitrogen, and t he frozen product (dryice) was pumped by the diffusion pump for purification. The CO2 was warmed up slowly and kept in the cylinder at high pressure. The CO2 pressure used in the White cell was varied from 1 to 1000 Torr depend ing on the wavelength region, and was measured with a a capacitance manometer (M KS Baratron, 10 Torr and 1000 Torr). We divided the spectral region into twenty sections of about 1.5 nm extent. At each scan range, another scan was obtained from the emission spectrum of the fourth positive bands of CO for wavelength calibration. We acknowledge funding from NASA, grant NAGS-7859 to Harvard College Observatory.

  1. Imaging performance and challenges of 10nm and 7nm logic nodes with 0.33 NA EUV

    NASA Astrophysics Data System (ADS)

    van Setten, Eelco; Schiffelers, Guido; Psara, Eleni; Oorschot, Dorothe; Davydova, Natalia; Finders, Jo; Depre, Laurent; Farys, Vincent

    2014-10-01

    The NXE:3300B is ASML's third generation EUV system and has an NA of 0.33 and is positioned at a resolution of 22nm, which can be extended down to 18nm and below with off-axis illumination at full transmission. Multiple systems have been qualified and installed at customers. The NXE:3300B succeeds the NXE:3100 system (NA of 0.25), which has allowed customers to gain valuable EUV experience. It is expected that EUV will be adopted first for critical Logic layers at 10nm and 7nm nodes, such as Metal-1, to avoid the complexity of triple patterning schemes using ArF immersion. In this paper we will evaluate the imaging performance of (sub-)10nm node Logic M1 on the NXE:3300B EUV scanner. We will show the line-end performance of tip-to-tip and tip-to-space test features for various pitches and illumination settings and the performance enhancement obtained by means of a 1st round of OPC. We will also show the magnitude of local variations. The Logic M1 cell is evaluated at various critical features to identify hot spots. A 2nd round OPC model was calibrated of which we will show the model accuracy and ability to predict hot spots in the Logic M1 cell. The calibrated OPC model is used to predict the expected performance at 7nm node Logic using off-axis illumination at 16nm minimum half pitch. Initial results of L/S exposed on the NXE:3300B at 7nm node resolutions will be shown. An outlook is given to future 0.33 NA systems on the ASML roadmap with enhanced illuminator capabilities to further improve performance and process window.

  2. A self-Q-switched all-fiber erbium laser at 1530 nm using an auxiliary 1570-nm erbium laser.

    PubMed

    Tsai, Tzong-Yow; Fang, Yen-Cheng

    2009-11-23

    We demonstrate a self-Q-switched, all-fiber, tunable, erbium laser at 1530 nm with high pulse repetition rates of 0.9-10 kHz. Through the use of an auxiliary 10-mW, 1570 nm laser that shortened the relaxation time of erbium, sequentially Q-switched pulses with pulse energies between 4 and 6 microJ and pulse widths of 40 ns were steadily achieved. A peak pulse power of 165 W was obtained.

  3. Importance of ultraviolet radiation in photoinhibition of microalgal growth

    SciTech Connect

    Jokiel, P.L.; York, R.H. Jr.

    1984-01-01

    Algae vary greatly in their long term ability to adapt to levels of natural solar ultraviolet radiation encountered near the surface of the sea. Photosynthetically active radiation (where PAR is defined as quantum flux between 400 and 700 nm) produced little or no growth inhibition even at full surface intensity. In some species the capacity to tolerate intense PAR did not carry into the range of UV-A (315-400 nm) or of UV-B radiation (280-315 nm) or both. Photo-inhibition became increasingly severe above 20% of surface intensity among the species sensitive to UV radiation. PAR flux in excess of that required for maximum growth was not inhibitory, but rather the higher levels of associated UV radiation reduced growth rate. These results support a previous suggestion that other molecules besides chlorophyll sensitize or shield algae in the UV portion of the solar spectrum.

  4. Radiation enteritis.

    PubMed

    Harb, Ali H; Abou Fadel, Carla; Sharara, Ala I

    2014-01-01

    Radiation enteritis continues to be a major health concern in recipients of radiation therapy. The incidence of radiation enteritis is expected to continue to rise during the coming years paralleling the unprecedented use of radiotherapy in pelvic cancers. Radiation enteritis can present as either an acute or chronic syndrome. The acute form presents within hours to days of radiation exposure and typically resolves within few weeks. The chronic form may present as early as 2 months or as long as 30 years after exposure. Risk factors can be divided into patient and treatment-related factors. Chronic radiation enteritis is characterized by progressive obliterative endarteritis with exaggerated submucosal fibrosis and can manifest by stricturing, formation of fistulae, local abscesses, perforation, and bleeding. In the right clinical context, diagnosis can be confirmed by cross-sectional imaging, flexible or video capsule endoscopy. Present treatment strategies are directed primarily towards symptom relief and management of emerging complications. Recently, however, there has been a shift towards rational drug design based on improved understanding of the molecular basis of disease in an effort to limit the fibrotic process and prevent organ damage.

  5. Considerations for fine hole patterning for the 7nm node

    NASA Astrophysics Data System (ADS)

    Yaegashi, Hidetami; Oyama, Kenichi; Hara, Arisa; Natori, Sakurako; Yamauchi, Shohei; Yamato, Masatoshi; Koike, Kyohei

    2016-03-01

    One of the practical candidates to produce 7nm node logic devices is to use the multiple patterning with 193-immersion exposure. For the multiple patterning, it is important to evaluate the relation between the number of mask layer and the minimum pitch systematically to judge the device manufacturability. Although the number of the time of patterning, namely LE(Litho-Etch) ^ x-time, and overlay steps have to be reduced, there are some challenges in miniaturization of hole size below 20nm. Various process fluctuations on contact hole have a direct impact on device performance. According to the technical trend, 12nm diameter hole on 30nm-pitch hole will be needed on 7nm node. Extreme ultraviolet lithography (EUV) and Directed self-assembly (DSA) are attracting considerable attention to obtain small feature size pattern, however, 193-immersion still has the potential to extend optical lithography cost-effectively for sub-7nm node. The objective of this work is to study the process variation challenges and resolution in post-processing for the CD-bias control to meet sub-20nm diameter contact hole. Another pattern modulation is also demonstrated during post-processing step for hole shrink. With the realization that pattern fidelity and pattern placement management will limit scaling long before devices and interconnects fail to perform intrinsically, the talk will also outline how circle edge roughness (CER) and Local-CD uniformity can correct efficiency. On the other hand, 1D Gridded-Design-Rules layout (1D layout) has simple rectangular shapes. Also, we have demonstrated CD-bias modification on short trench pattern to cut grating line for its fabrication.

  6. High-brightness 800nm fiber-coupled laser diodes

    NASA Astrophysics Data System (ADS)

    Berk, Yuri; Levy, Moshe; Rappaport, Noam; Tessler, Renana; Peleg, Ophir; Shamay, Moshe; Yanson, Dan; Klumel, Genadi; Dahan, Nir; Baskin, Ilya; Shkedi, Lior

    2014-03-01

    Fiber-coupled laser diodes have become essential sources for fiber laser pumping and direct energy applications. Single emitters offer reliable multi-watt output power from a 100 m lateral emission aperture. By their combination and fiber coupling, pump powers up to 100 W can be achieved from a low-NA fiber pigtail. Whilst in the 9xx nm spectral range the single emitter technology is very mature with <10W output per chip, at 800nm the reliable output power from a single emitter is limited to 4 W - 5 W. Consequently, commercially available fiber coupled modules only deliver 5W - 15W at around 800nm, almost an order of magnitude down from the 9xx range pumps. To bridge this gap, we report our advancement in the brightness and reliability of 800nm single emitters. By optimizing the wafer structure, laser cavity and facet passivation process we have demonstrated QCW device operation up to 19W limited by catastrophic optical damage to the 100 μm aperture. In CW operation, the devices reach 14 W output followed by a reversible thermal rollover and a complete device shutdown at high currents, with the performance fully rebounded after cooling. We also report the beam properties of our 800nm single emitters and provide a comparative analysis with the 9xx nm single emitter family. Pump modules integrating several of these emitters with a 105 μm / 0.15 NA delivery fiber reach 35W in CW at 808 nm. We discuss the key opto-mechanical parameters that will enable further brightness scaling of multi-emitter pump modules.

  7. Analysis of Cervical Supernatant Samples Luminescence Using 355 nm Laser

    NASA Astrophysics Data System (ADS)

    Vaitkuviene, A.; Gegzna, V.; Kurtinaitiene, R.; Stanikunas, R.; Rimiene, J.; Vaitkus, J.

    2010-05-01

    The biomarker discovery for accurate detection and diagnosis of cervical carcinoma and its malignant precursors represents one of the current challenges in clinical medicine. Laser induced autofluorescence spectra in cervical smear content were fitted to predict the cervical epithelium diagnosis as a lab off "optical biopsy" method. Liquid PAP supernatant sediment dried on Quartz plate spectroscopy was performed by 355 nm Nd YAG microlaser STA-1 (Standa, Ltd). For comparison a liquid supernatant spectroscopy was formed by laboratory "Perkin Elmer LS 50B spetrometer at 290, 300, 310 nm excitations. Analysis of spectrum was performed by approximation using the multi-peaks program with Lorentz functions for the liquid samples and with Gaussian functions for the dry samples. Ratio of spectral components area to the area under whole experimental curve (SPP) was calculated. The spectral components were compared by averages of SPP using Mann-Whitney U-test in histology groups. Results. Differentiation of Normal and HSIL/CIN2+ cases in whole supernatant could be performed by stationary laboratory lamp spectroscopy at excitation 290 nm and emission >379 nm with accuracy AUC 0,69, Sens 0,72, Spec 0,65. Differentiation Normal versus HSIL/CIN2+ groups in dried enriched supernatant could be performed by 355 nm microlaser excitation at emission 405-424 nm with accuracy (AUC 0,96, Sens 0,91, Spec 1.00). Diagnostic algorithm could be created for all histology groups differentiation under 355 nm excitation. Microlaser induced "optical biopsy "looks promising method for cervical screening at the point of care.

  8. All-fiber wavelength-tunable Tm/Ho-codoped laser between 1727 nm and 2030 nm

    NASA Astrophysics Data System (ADS)

    Xue, Guanghui; Zhang, Bin; Yin, Ke; Yang, Weiqiang; Hou, Jing

    2015-02-01

    Lasers in the eye-safe 2 μm spectral region are attracting significant interest due to a variety of applications such as atmospheric lidar sensing and medical treatment, which require laser sources matching the absorption lines of various molecules in the 2 μm wavelength region. We demonstrate an all-fiber Tm/Ho-codoped laser operating in the 2 μm wavelength region with a wide wavelength tuning range of more than 300 nm. The Tm/Ho-codoped fiber laser (THFL) was built in a ring cavity configuration with a fiberized grating-based tunable filter to select the operating wavelength. The tunable wavelength range of the THFL was from 1727 nm to 2030 nm. To the best of our knowledge, this is the widest tuning range that has been reported for an all-fiber rare-earth-doped laser to date. Efficient short wavelength operation was also achieved. The output power of the THFL was further scaled up from 1810 nm to 2010 nm by using a stage of Tm/Ho-codoped fiber amplifier (THFA), which exhibited the maximum slope efficiency of 42.6% with output power of 408 mW at 1910 nm.

  9. Optical coherence tomography based imaging of dental demineralisation and cavity restoration in 840 nm and 1310 nm wavelength regions

    NASA Astrophysics Data System (ADS)

    Damodaran, Vani; Rao, Suresh Ranga; Vasa, Nilesh J.

    2016-08-01

    In this paper, a study of in-house built optical coherence tomography (OCT) system with a wavelength of 840 nm for imaging of dental caries, progress in demineralisation and cavity restoration is presented. The caries when imaged with the 840 nm OCT system showed minute demineralisation in the order of 5 μm. The OCT system was also proposed to study the growth of lesion and this was demonstrated by artificially inducing caries with a demineralisation solution of pH 4.8. The progress of carious lesion to a depth of about 50-60 μm after 60 hours of demineralisation was clearly observed with the 840 nm OCT system. The tooth samples were subjected to accelerated demineralisation condition at pH of approximately 2.3 to study the adverse effects and the onset of cavity formation was clearly observed. The restoration of cavity was also studied by employing different restorative materials (filled and unfilled). In the case of restoration without filler material (unfilled), the restoration boundaries were clearly observed. Overall, results were comparable with that of the widely used 1310 nm OCT system. In the case of restoration with filler material, the 1310 nm OCT imaging displayed better imaging capacity due to lower scattering than 840 nm imaging.

  10. A 1.5-W frequency doubled semiconductor disk laser tunable over 40 nm at around 745 nm

    NASA Astrophysics Data System (ADS)

    Saarinen, Esa J.; Lyytikäinen, Jari; Ranta, Sanna; Rantamäki, Antti; Saarela, Antti; Sirbu, Alexei; Iakovlev, Vladimir; Kapon, Eli; Okhotnikov, Oleg G.

    2016-03-01

    We report on a semiconductor disk laser emitting 1.5 W of output power at the wavelength of 745 nm via intracavity frequency doubling. The high power level and the < 40 nm tuning range make the laser a promising tool for medical treatments that rely on photosensitizing agents and biomarkers in the transmission window of tissue between 700 and 800 nm. The InP-based gain structure of the laser was wafer-fused with a GaAs-based bottom mirror and thermally managed with an intracavity diamond heat spreader. The structure was pumped with commercial low-cost 980 nm laser diode modules. Laser emission at 1490 nm was frequency-doubled with a bismuth borate crystal that was cut for type I critical phase matching. At the maximum output power, we achieved an optical-to-optical efficiency of 8.3% with beam quality parameter M2 below 1.5. The laser wavelength could be tuned with an intracavity birefringent plate from 720 to 764 nm.

  11. ESTIMATION OF UV RADIATION DOSE IN NORTHERN MINNESOTA WETLANDS

    EPA Science Inventory

    The ultraviolet (UV) B wavelength range (280 nm to 320 nm) of solar radiation can be a significant biological stressor, and has been hypothesized to be partially responsible for amphibian declines and malformation. This hypothesis has been difficult to evaluate, in part, because ...

  12. Research of the Additional Losses Occurring in Optical Fiber at its Multiple Bends in the Range Waves 1310nm, 1550nm and 1625nm Long

    NASA Astrophysics Data System (ADS)

    Yurchenko, A. V.; Gorlov, N. I.; Alkina, A. D.; Mekhtiev, A. D.; Kovtun, A. A.

    2016-01-01

    Article is devoted to research of the additional losses occurring in the optical fiber at its multiple bends in the range waves of 1310 nanometers, 1550 nanometers and 1625 nanometers long. Article is directed on creation of the external factors methods which allow to estimate and eliminate negative influence. The automated way of calculation of losses at a bend is developed. Results of scientific researches are used by engineers of “Kazaktelekom” AS for practical definition of losses service conditions. For modeling the Wolfram|Alpha environment — the knowledge base and a set of computing algorithms was chosen. The greatest losses are noted on wavelength 1310nm and 1625nm. All dependences are nonlinear. Losses with each following excess are multiplicative.

  13. Observation of Quiet Limb in He I 1083.0 nm, H Paschen alpha1281.8 nm and H Brackett gamma 2166.1 nm lines

    NASA Astrophysics Data System (ADS)

    Prasad Choudhary, Debi

    2016-05-01

    In this paper, we shall present the results of an observational study of the quiet solar limb in the near infrared lines using the New IR Array Camera (NAC) and the vertical spectrograph at the focal plane of McMath-Pierce telescope. The NAC, at the exit port of the spectrograph, was used to record the limb spectrum in HeI 1083.0 nm, Hydrogen Paschen 1281.8 nm and Brackett 2165.5 nm wavelength regions. The NAC is a 1024x1024 InSb Alladin III Detector operating over 1-5 micron range with high density sampling at 0.018 arc second/pixel. The all-reflective optical train minimizes number of surfaces and eliminates ghosts leading to low scatter, ghost-free optics. The close-cycle cryogenic provides a stable cooling environment over six hour period with an accuracy of 0.01K leading to low dark current. The low read out noise combined with low scattered light and dark current makes NAC an ideal detector for making high quality infrared spectral observations of solar limb. The limb spectrums were obtained by placing the spectrograph slit perpendicular to the limb at an interval of 10 degrees around the solar disk. We shall report the intensity profile, line-of-sight velocity and line width distribution around the sun derived from the spectra along the slit.

  14. Improving vacuum-UV (VUV) photolysis of organic compounds in water with a phosphor converted xenon excimer lamp emitting at 193 nm.

    PubMed

    Schulze-Hennings, U; Pötschke, L; Wietor, C; Bringmann, S; Braun, N; Hayashi, D; Linnemann, V; Pinnekamp, J

    2016-01-01

    A novel vacuum ultraviolet excimer lamp emitting light at 193 nm was used to investigate the degradation of organic micropollutants in ultrapure water and wastewater treatment plant (WWTP) effluent. Overall, light at 193 nm proved to be efficient to degrade the investigated micropollutants (diclofenac, diatrizoic acid, sulfamethoxazole). Experiments with WWTP effluent proved the ability of radiation at 193 nm to degrade micropollutants which are hardly removed with commonly used oxidation technologies like ozonation (diatrizoic acid, ethylenediaminetetraacetic acid, perfluorooctanoic acid, and perfluorooctanesulfonic acid). PMID:27533863

  15. [In vitro antimycobacterial activity of a new quinolone, NM394].

    PubMed

    Tomioka, H; Sato, K; Saito, H

    1993-08-01

    We evaluated the in vitro antimicrobial activity of NM394 and ofloxacin (OFLX) against representative pathogenic mycobacteria by the agar dilution method, using 7H11 agar medium. NM394 showed appreciable antimicrobial activity against Mycobacterium tuberculosis (MIC90 = 0.78 micrograms/ml), M. kansasii (MIC90 = 6.25 micrograms/ml), M. marinum (MIC90 = 3.13 micrograms/ml) and M. fortuitum (MIC90 = 3.13 micrograms/ml), whereas the agent was not active against M. scrofulaceum (MIC90 = > 100 micrograms/ml), M. avium (MIC90 = 50 micrograms/ml), M. intracellulare (MIC90 = > 100 micrograms/ml), M. chelonae subsp. abscessus (MIC90 = > 100 micrograms/ml) and M. chelonae subsp. chelonae (MIC90 = 25 micrograms/ml). The in vitro antimicrobial activity of the agent against M. fortuitum was a little more active than that of OFLX, whereas the activity of NM394 against the other mycobacteria was slightly inferior to that of OFLX. The antimycobacterial activity of NM394 against M. tuberculosis H37Rv (MIC:NM394 = 0.78 micrograms/ml, OFLX = 0.78 micrograms/ml) phagocytosed in murine peritoneal macrophages was less active than that of OFLX, when the macrophages were cultured in RPMI-1640 medium containing 1 microgram/ml or 10 micrograms/ml of these agents for up to 5 days. PMID:8397311

  16. Taking the X Architecture to the 65-nm technology node

    NASA Astrophysics Data System (ADS)

    Sarma, Robin C.; Smayling, Michael C.; Arora, Narain; Nagata, Toshiyuki; Duane, Michael P.; Shah, Santosh; Keston, Harris J.; Oemardani, Shiany

    2004-05-01

    The X Architecture is a new way of orienting the interconnect on an integrated circuit using diagonal pathways, as well as the traditional right-angle, or Manhattan, configuration. By enabling designs with significantly less wire and fewer vias, the X Architecture can provide substantial improvements in chip performance, power consumption and cost. Members of the X Initiative semiconductor supply chain consortium have demonstrated the production worthiness of the X Architecture at the 130-nm and 90-nm process technology nodes. This paper presents an assessment of the manufacturing readiness of the X Architecture for the 65-nm technology node. The extent to which current production capabilities in mask writing, lithography, wafer processing, inspection and metrology can be used is discussed using the results from a 65-nm test chip. The project was a collaborative effort amongst a number of companies in the IC fabrication supply chain. Applied Materials fabricated the 65-nm X Architecture test chip at its Maydan Technology Center and leveraged the technology of other X Initiative members. Cadence Design Systems provided the test structure design and chip validation tools, Dai Nippon Printing produced the masks and Canon"s imaging system was employed for the photolithography.

  17. Coronal Diagnostics from Narrowband Images Around 30.4 nm

    NASA Astrophysics Data System (ADS)

    Andretta, V.; Telloni, D.; Del Zanna, G.

    2012-07-01

    Images taken in the band centered at 30.4 nm are routinely used to map the radiance of the He ii Ly α line on the solar disk. That line is one of the strongest, if not the strongest, line in the EUV observed in the solar spectrum, and one of the few lines in that wavelength range providing information on the upper chromosphere or lower transition region. However, when observing the off-limb corona, the contribution from the nearby Si xi 30.3 nm line can become significant. In this work we aim at estimating the relative contribution of those two lines in the solar corona around the minimum of solar activity. We combine measurements from CDS taken in August 2008 with temperature and density profiles from semiempirical models of the corona to compute the radiances of the two lines, and of other representative coronal lines ( e.g. Mg x 62.5 nm, Si xii 52.1 nm). Considering both diagnosed quantities from line ratios (temperatures and densities) and line radiances in absolute units, we obtain a good overall match between observations and models. We find that the Si xi line dominates the He ii line from just above the limb up to ≈ 2 R ⊙ in streamers, while its contribution to narrowband imaging in the 30.4 nm band is expected to become smaller, even negligible in the corona beyond ≈ 2 - 3 R ⊙, the precise value being strongly dependent on the coronal temperature profile.

  18. Ultraviolet radiation cataract: dose dependence

    NASA Astrophysics Data System (ADS)

    Soderberg, Per G.; Loefgren, Stefan

    1994-07-01

    Current safety limits for cataract development after acute exposure to ultraviolet radiation (UVR) are based on experiments analyzing experimental data with a quantal, effect-no effect, dose-response model. The present study showed that intensity of forward light scattering is better described with a continuous dose-response model. It was found that 3, 30 and 300 kJ/m2UVR300nm induces increased light scattering within 6 h. For all three doses the intensity of forward light scattering was constant after 6 h. The intensity of forward light scattering was proportional to the log dose of UVR300nm. There was a slight increase of the intensity of forward light scattering on the contralateral side in animals that received 300 kJ/m2. Altogether 72 Sprague-Dawley male rats were included. Half of the rats were exposed in vivo on one side to UVR300nm. The other half was kept as a control group, receiving the same treatment as exposed rats but without delivery of UVR300nm to the eye. Subgroups of the rats received either of the three doses. Rats were sacrificed at varying intervals after the exposure. The lenses were extracted and the forward light scattering was estimated. It is concluded that intensity of forward light scattering in the lens after exposure to UVR300nm should be described with a continuous dose-reponse model.

  19. Inhibition of semiconservative DNA synthesis in ICR 2A frog cells exposed to monochromatic uv wavelengths (252-313 nm) and photoreactivating light

    SciTech Connect

    Rosenstein, B.S.

    1982-06-01

    Exposure of ICR 2A frog cells to monochromatic uv wavelengths in the range 252-313 nm caused an inhibition of semiconservative DNA synthesis which was partially relieved in cells receiving a post irradiation treatment with photoreactivating light (>350 nm). Hence pyrimidine dimers acted as lesions blocking DNA synthesis in uv-irradiated cells based upon the specificity of photoreactivating enzyme for the light-dependent monomerization of dimers in DNA. Compared with the shorter wavelengths tested, however, this recovery of DNA synthesis was not as great in cells exposed to 302-nm radiation and was nearly absent in 313-nm-irradiated cells up to 12 hr after treatment. These results suggest that nondimer photoproducts also play an important role in causing DNA synthesis inhibition in cells exposed to wavelengths greater than 300 nm.

  20. Demonstration of long-term reliability of a 266-nm, continuous-wave, frequency-quadrupled solid-state laser using beta-BaB(2)O(4).

    PubMed

    Kondo, K; Oka, M; Wada, H; Fukui, T; Umezu, N; Tatsuki, K; Kubota, S

    1998-02-01

    We report what we believe to be the first operation of more than 1000 h of a 266-nm (cw) frequency-quadrupled solid-state laser with a 100-mW output. We used beta-BaB(2)O(4)(BBO) crystal grown by the Czochralski method to double the green-light (532-nm) wavelength, using an external resonant cavity. The green light was generated with an intracavity frequency-doubled Nd:YVO(4)laser pumped by a 4-W laser diode. When the incident 532-nm power on the external resonant doubler was 500 mW, we generated 100 mW of cw 266-nm radiation with the BBO crystal. The degradation rate seems to be proportional to the strength of the UV optical electric field. We also obtained a relative intensity noise of -130dB/Hz at frequencies of 2 to 10 MHz for 266-nm laser light.

  1. Radiation enteritis and radiation scoliosis

    SciTech Connect

    Shah, M.; Eng, K.; Engler, G.L.

    1980-09-01

    Any patient with radiation scoliosis should be suspected of having a visceral lesion as well. Chronic radiation enteritis may be manifested by intestinal obstruction, fistulas, perforation, and hemorrhage. Intestinal obstruction is the most common complication, and must be differentiated from postoperative cast or from spinal-traction syndrome. Obstruction that does not respond promptly to conservative measures must be treated surgically. Irradiated bowel is ischemic, and necrosis with spontaneous perforation can only be avoided with early diagnosis and surgical intervention.

  2. Radiation Oncology Treatment Team

    MedlinePlus

    ... Upper GI What is Radiation Therapy? Find a Radiation Oncologist Last Name: Facility: City: State: Zip Code: ... who specializes in using radiation to treat cancer . Radiation Oncologists Radiation oncologists are the doctors who will ...

  3. Radiation Therapy (For Parents)

    MedlinePlus

    ... 5 Things to Know About Zika & Pregnancy Radiation Therapy KidsHealth > For Parents > Radiation Therapy Print A A ... many questions and concerns about it. About Radiation Therapy In radiation therapy, high-energy radiation from X- ...

  4. Brain radiation - discharge

    MedlinePlus

    Radiation - brain - discharge; Cancer-brain radiation; Lymphoma - brain radiation; Leukemia - brain radiation ... Decadron) while you are getting radiation to the brain. It may make you hungrier, cause leg swelling ...

  5. Comparison of modeled NmE with NmE measured by the Boulder ionosonde near the spring equinox.

    NASA Astrophysics Data System (ADS)

    Pavlov, Anatoli; Pavlova, Nadezhda

    We present a comparison of the E-layer peak electron number densities, NmE, measured by the Boulder ionosonde during geomagnetically quiet conditions on 10 April 1996 at low solar activity, 2 April 1993 and 9 April 1978 during moderate solar activity conditions, and 10 April 1991 at high solar activity with numerical theoretical model calculations of NmE. Based on this comparison, the modified EUVAC model solar flux is necessary to increase by a factor of 2 at moderate and high solar activity in the wavelength range of 3.2-7.0 nm. If O (+) ( (4) S), O (+) ( (2) D), O (+) ( (2) P), and N (+) ions are not calculated, the value of NmE is decreased up to a factor of 1.12 at solar minimum and up to a factor of 1.23 for the moderate and high solar activity conditions. The production of N _{2} (+) ions by photoelectron-impact ionization of N _{2} increases the value of NmE up to a factor of 1.18 at low solar activity and up to a factor of 1.33 for the moderate and high solar activity levels. The increase in NmE due to the production of O _{2} (+) ions by photoelectron-impact ionization of O _{2} does not exceed 4 percent. A difference between the calculated electron, T _{e}, and neutral, T _{n}, temperatures is less than 1, 4, 20, 70, and 145 K at 105, 110, 120, 130, and 140 km altitude, respectively. Changes in NmE caused by this difference between T _{e} and T _{n} are negligible.

  6. [Health effects of ultraviolet radiation].

    PubMed

    Ohnaka, T

    1993-01-01

    Exposure to ultraviolet radiation (UVR) occurs from both natural and artificial sources. The main natural source is the sun. On the other hand, artificial UVR sources are widely used in industry and also used in hospitals, laboratories, etc. because of their germicidal properties. They are even used for cosmetic purposes. UVR can be classified into three regions according to its wavelength: as UVA (320-400nm), UVB (320-280nm) and UVC (280-200nm). The UVC has the greatest health effect on humans among the three. The sun radiates a wide range of spectrum of electromagnetic radiation including the UVR, however the radiation below 290 nm in wavelength does not reach the surface of the earth for effective absorption by the stratospheric ozone layer. As a result, UVR from a natural source consists of only UVA and a part of UVB. On the other hand, artificial UVR sources include UVC region and have serious effects on the human body, especially on the skin and eyes. The health effects of UVR on humans can be beneficial or detrimental, depending on the amount and form of UVR, as well as on the skin type of the individual exposed. It has been acknowledged that a long period of UVR deficiency may have harmful effects on the human body, such as the development of vitamin D deficiency and rickets in children due to a disturbance in the phosphorus and calcium metabolism. Appropriate measures to increase the amount of exposure to UVR, especially to UVB radiation by the use of sun bathing, the exposure to artificial UVR sources, etc. have shown to prevent disease states caused by UVR deficiency. The harmful effects of UVR consist of erythema, sunburn, photodamage (photoaging), photocarcinogenesis, damage to the eyes, alteration of the immune system of the skin, and chemical hypersensitivity. Skin cancer is commonly produced by UVR. In this review, various states of UV from solar radiation and the degree of exposure to UVR are introduced. The benefits and harmful health effects of

  7. Novel fluoro copolymers for 157-nm photoresists: a progress report

    NASA Astrophysics Data System (ADS)

    Hohle, Christoph; Hien, Stefan; Eschbaumer, Christian; Rottstegge, Joerg; Sebald, Michael

    2002-07-01

    Several fluoro-substituted polymers consisting of acid cleavable methacryoic or cinnamic acid tert.-butyl ester compounds copolymerized with maleic acid anhydride derivatives were synthesized by radical copolymerization. Vacuum ultraviolet transmission measurements of the samples reveal absorbances down to 5micrometers -1 despite of the strongly absorbing anhydride moiety which serves as silylation anchor for the application of the Chemical Amplification of Resist Lines (CARL) process, one of the promising approaches for sub-90nm pattern fabrication. Some of the samples exhibit resolutions down to 110nm dense at 157nm exposure using an alternating phase shift mask. The feasibility of the CARL principle including the silylation reaction after development has been demonstrated with selected fluorinated polymer samples.

  8. High power narrowband 589 nm frequency doubled fibre laser source.

    PubMed

    Taylor, Luke; Feng, Yan; Calia, Domenico Bonaccini

    2009-08-17

    We demonstrate high-power high-efficiency cavity-enhanced second harmonic generation of an in-house built ultra-high spectral density (SBS-suppressed) 1178 nm narrowband Raman fibre amplifier. Up to 14.5 W 589 nm CW emission is achieved with linewidth Delta nu(589) < 7 MHz in a diffraction-limited beam, with peak external conversion efficiency of 86%. The inherently high spectral and spatial qualities of the 589 nm source are particularly suited to both spectroscopic and Laser Guide Star applications, given the seed laser can be easily frequency-locked to the Na D(2a) emission line. Further, we expect the technology to be extendable, at similar or higher powers, to wavelengths limited only by the seed-pump-pair availability. PMID:19687946

  9. Guaranteed discovery of the NmSuGra model

    SciTech Connect

    Balazs, Csaba; Carter, Daniel

    2008-11-23

    We analyze the discovery potential of the next-to-minimal supergravity motivated model: NmSuGra. This model is an extension of mSuGra by a gauge singlet, and contains only one additional parameter: {lambda}, the Higgs-singlet-Higgs coupling. NmSuGra solves the {mu}-problem and reduces the fine tuning of mSuGra. After identifying parameter space regions preferred by present experimental data, we show that these regions of NmSuGra are amenable to detection by the combination of the Large Hadron Collider and an upgraded Cryogenic Dark Matter Search. This conclusion holds strictly provided that the more than three sigma discrepancy in the difference of the experimental and the standard theoretical values of the anomalous magnetic moment of the muon prevails in the future.

  10. High Power 938nm Cladding Pumped Fiber Laser

    SciTech Connect

    Dawson, J; Beach, R; Brobshoff, A; Liao, Z; Payne, S; Pennington, D; Taylor, L; Hackenberg, W; Bonaccini, D

    2002-12-26

    We have developed a Nd:doped cladding pumped fiber amplifier, which operates at 938nm with greater than 2W of output power. The core co-dopants were specifically chosen to enhance emission at 938nm. The fiber was liquid nitrogen cooled in order to achieve four-level laser operation on a laser transition that is normally three level at room temperature, thus permitting efficient cladding pumping of the amplifier. Wavelength selective attenuation was induced by bending the fiber around a mandrel, which permitted near complete suppression of amplified spontaneous emission at 1088nm. We are presently seeking to scale the output of this laser to 10W. We will discuss the fiber and laser design issues involved in scaling the laser to the 10W power level and present our most recent results.

  11. New 223-nm excimer laser surgical system for photorefractive keratectomy

    NASA Astrophysics Data System (ADS)

    Bagaev, Sergei N.; Razhev, Alexander M.; Zhupikov, Andrey A.

    1999-02-01

    The using of KrCl (223 nm) excimer laser in ophthalmic devices for Photorefractive Keratectomy (PRK) and phototherapeutic Keratectomy (PTK) is offered. The structure and functions of a new surgical UV ophthalmic laser systems Medilex using ArF (193 nm) or KrCl (223 nm) excimer laser for corneal surgery are presented. The systems Medilex with the new optical delivery system is used for photoablative reprofiling of the cornea to correct refraction errors (myopia, hyperopia and astigmatism) and to treat a corneal pathologies. The use of the 223 nanometer laser is proposed to have advantages over the 193 nanometer laser. The results of application of the ophthalmic excimer laser systems Medilex for treatment of myopia are presented.

  12. Developmental Function of Nm23/awd - A Mediator of Endocytosis

    PubMed Central

    Nallamothu, Gouthami; Dammai, Vincent; Hsu, Tien

    2009-01-01

    The metastasis suppressor gene Nm23 is highly conserved from yeast to human, implicating a critical developmental function. Studies in cultured mammalian cells have identified several potential functions, but many have not been directly verified in vivo. Here we summarize the studies on the Drosophila homologue of the Nm23 gene, named abnormal wing discs (awd), which shares 78% amino acid identity with the human Nm23-H1 and H2 isoforms. These studies confirmed that awd gene encodes a nucleoside diphosphate kinase, and provided strong evidence of a role for awd in regulating cell differentiation and motility via regulation of growth factor receptor signaling. The latter function is mainly mediated by control of endocytosis. This review provides a historical account of the discovery and subsequent analyses of the awd gene. We will also discuss the possible molecular function of the Awd protein that underlies the endocytic function. PMID:19373545

  13. High power narrowband 589 nm frequency doubled fibre laser source.

    PubMed

    Taylor, Luke; Feng, Yan; Calia, Domenico Bonaccini

    2009-08-17

    We demonstrate high-power high-efficiency cavity-enhanced second harmonic generation of an in-house built ultra-high spectral density (SBS-suppressed) 1178 nm narrowband Raman fibre amplifier. Up to 14.5 W 589 nm CW emission is achieved with linewidth Delta nu(589) < 7 MHz in a diffraction-limited beam, with peak external conversion efficiency of 86%. The inherently high spectral and spatial qualities of the 589 nm source are particularly suited to both spectroscopic and Laser Guide Star applications, given the seed laser can be easily frequency-locked to the Na D(2a) emission line. Further, we expect the technology to be extendable, at similar or higher powers, to wavelengths limited only by the seed-pump-pair availability.

  14. 11nm logic lithography with OPC-lite

    NASA Astrophysics Data System (ADS)

    Smayling, Michael C.; Tsujita, Koichiro; Yaegashi, Hidetami; Axelrad, Valery; Nakayama, Ryo; Oyama, Kenichi; Hara, Arisa

    2014-03-01

    CMOS logic at the 22nm node and below is being done with a highly regular layout style using Gridded Design Rules (GDR). Smaller nodes have been demonstrated using a "lines and cuts" approach with good pattern fidelity and process margin, with extendibility to ~7nm.[1] In previous studies, Design-Source-Mask Optimization (DSMO) has been demonstrated to be effective down to the 12nm node.[2,3,4,5,6] The transition from single- to double- and in some cases triple- patterning was evaluated for different layout styles, with highly regular layouts delaying the need for multiple-patterning compared to complex layouts. To address mask complexity and cost, OPC for the "cut" patterns was studied and relatively simple OPC was found to provide good quality metrics such as MEEF and DOF.[3,7,8] This is significant since mask data volumes of >500GB per layer are projected for pixelated masks created by complex OPC or inverse lithography; writing times for such masks are nearly prohibitive. In our present work, we extend the scaling using SMO with "OPC Lite" beyond 12nm. The focus is on the contact pattern since a "hole" pattern is similar to a "cut" pattern so a similar technique should be useful. The test block is a reasonably complex logic function with ~100k gates of combinatorial logic and flip-flops, scaled from previous studies. The contact pattern is a relatively dense layer since it connects two underlying layers - active and gate - to one overlying layer - metal-1. Several design iterations were required to get suitable layouts while maintaining circuit functionality. Experimental demonstration of the contact pattern using OPC-Lite will be presented. Wafer results have been obtained at a metal-1 half-pitch of 18nm, corresponding to the 11nm CMOS node. Additional results for other layers - FINs, local interconnect, and metal-1 - will also be discussed.

  15. 32 nm imprint masks using variable shape beam pattern generators

    NASA Astrophysics Data System (ADS)

    Selinidis, Kosta; Thompson, Ecron; Schmid, Gerard; Stacey, Nick; Perez, Joseph; Maltabes, John; Resnick, Douglas J.; Yeo, Jeongho; Kim, Hoyeon; Eynon, Ben

    2008-05-01

    Imprint lithography has been included on the ITRS Lithography Roadmap at the 32, 22 and 16 nm nodes. Step and Flash Imprint Lithography (S-FIL ®) is a unique method that has been designed from the beginning to enable precise overlay for creating multilevel devices. A photocurable low viscosity monomer is dispensed dropwise to meet the pattern density requirements of the device, thus enabling imprint patterning with a uniform residual layer across a field and across entire wafers. Further, S-FIL provides sub-100 nm feature resolution without the significant expense of multi-element, high quality projection optics or advanced illumination sources. However, since the technology is 1X, it is critical to address the infrastructure associated with the fabrication of templates. For sub-32 nm device manufacturing, one of the major technical challenges remains the fabrication of full-field 1x templates with commercially viable write times. Recent progress in the writing of sub-40 nm patterns using commercial variable shape e-beam tools and non-chemically amplified resists has demonstrated a very promising route to realizing these objectives, and in doing so, has considerably strengthened imprint lithography as a competitive manufacturing technology for the sub 32nm node. Here we report the first imprinting results from sub-40 nm full-field patterns, using Samsung's current flash memory production device design. The fabrication of the template is discussed and the resulting critical dimension control and uniformity are discussed, along with image placement results. The imprinting results are described in terms of CD uniformity, etch results, and overlay.

  16. Full-field imprinting of sub-40 nm patterns

    NASA Astrophysics Data System (ADS)

    Yeo, Jeongho; Kim, Hoyeon; Eynon, Ben

    2008-03-01

    Imprint lithography has been included on the ITRS Lithography Roadmap at the 32, 22 and 16 nm nodes. Step and Flash Imprint Lithography (S-FIL (R)) is a unique patterning method that has been designed from the beginning to enable precise overlay to enable multilevel device fabrication. A photocurable low viscosity resist is dispensed dropwise to match the pattern density requirements of the device, thus enabling patterning with a uniform residual layer thickness across a field and across multiple wafers. Further, S-FIL provides sub-50 nm feature resolution without the significant expense of multi-element projection optics or advanced illumination sources. However, since the technology is 1X, it is critical to address the infrastructure associated with the fabrication of imprint masks (templates). For sub-32 nm device manufacturing, one of the major technical challenges remains the fabrication of full-field 1x imprint masks with commercially viable write times. Recent progress in the writing of sub-40 nm patterns using commercial variable shape e-beam tools and non-chemically amplified resists has demonstrated a very promising route to realizing these objectives, and in doing so, has considerably strengthened imprint lithography as a competitive manufacturing technology for the sub-32nm node. Here we report the first imprinting results from sub-40 nm full-field patterns, using Samsung's current flash memory production device design. The fabrication of the imprint mask and the resulting critical dimension control and uniformity are discussed, along with image placement results. The imprinting results are described in terms of CD uniformity, etch results, and overlay.

  17. Radiation cataract.

    PubMed

    Kleiman, N J

    2012-01-01

    Until very recently, ocular exposure guidelines were based on the assumption that radiation cataract is a deterministic event requiring threshold doses generally greater than 2 Gy. This view was, in part, based on older studies which generally had short follow-up periods, failed to take into account increasing latency as dose decreased, had relatively few subjects with doses below a few Gy, and were not designed to detect early lens changes. Newer findings, including those in populations exposed to much lower radiation doses and in subjects as diverse as astronauts, medical workers, atomic bomb survivors, accidentally exposed individuals, and those undergoing diagnostic or radiotherapeutic procedures, strongly suggest dose-related lens opacification at significantly lower doses. These observations resulted in a recent re-evaluation of current lens occupational exposure guidelines, and a proposed lowering of the presumptive radiation cataract threshold to 0.5 Gy/year and the occupational lens exposure limit to 20 mSv/year, regardless of whether received as an acute, protracted, or chronic exposure. Experimental animal studies support these conclusions and suggest a role for genotoxicity in the development of radiation cataract. Recent findings of a low or even zero threshold for radiation-induced lens opacification are likely to influence current research efforts and directions concerning the cellular and molecular mechanisms underlying this pathology. Furthermore, new guidelines are likely to have significant implications for occupational and/or accidental exposure, and the need for occupational eye protection (e.g. in fields such as interventional medicine).

  18. A New Quantum Sensor for Measuring Photosynthetically Active Radiation

    NASA Astrophysics Data System (ADS)

    Johnson, D.; Thomas, T.; Heinicke, D.; Peterson, R.; Morgan, P.; McDermitt, D. K.; Burba, G. G.

    2015-12-01

    A quantum sensor measures photosynthetically active radiation (PAR, in μmol of photons m-2 s-1) in the 400 nm to 700 nm waveband. Plants utilize this radiation to drive photosynthesis, though individual plant responses to incident radiation may vary within this range. The new quantum sensor (model LI-190R, LI-COR Biosciences, Lincoln, NE), with an optical filter and silicon photodiode detector housed in a cosine-corrected head, is designed to provide a better response to incident radiation across the 400-700 nm range. The new design is expected to significantly improve spectral response due to uniformity across the PAR waveband, but particularly in the wavebands from 520 nm to 600 nm and 665 nm to 680 nm, and sharp cutoffs in the regions below and above the PAR waveband. Special care was taken to make sure that PAR sensor would not substantially respond to incident radiation above the 700 nm threshold because this can lead to errors when performing measurements in environments with a large proportion of near-infrared radiation, such as canopy understory. The physical housing of the sensor is designed to be weather-resistant, to effectively shed precipitation, provide protection at high temperature and high humidity conditions, and has a cosine-corrected response to 82° zenith angle. The latter is particularly important when measuring incident radiation at low elevation angles, diffuse light, or low light conditions. This presentation describes the principles of the new design, and shows the performance results from field experiments and laboratory tests.

  19. Determination of transition probability for the 655-nm Tl line.

    NASA Astrophysics Data System (ADS)

    Karabourniotis, D.; Couris, S.; Damelincourt, J. J.

    Studies of high-pressure Hg-Tl I a.c. (50 Hz) arc plasmas have been used to verify the validity of Boltzmann statistics at the moment of maximum electron density (5 ms) by applying LTE criteria. For a known plasma temperature, the transition probability of the optically-thin 655-nm line of Tl was derived from emission measurements by using the self-reversed 535-nm line of Tl as reference [A655 = (3.74±0.37)×106s-1].

  20. Extension of 193 nm dry lithography to 45-nm half-pitch node: double exposure and double processing technique

    NASA Astrophysics Data System (ADS)

    Biswas, Abani M.; Li, Jianliang; Hiserote, Jay A.; Melvin, Lawrence S., III

    2006-10-01

    Immersion lithography and multiple exposure techniques are the most promising methods to extend lithography manufacturing to the 45nm node. Although immersion lithography has attracted much attention recently as a promising optical lithography extension, it will not solve all the problems at the 45-nm node. The 'dry' option, (i.e. double exposure/etch) which can be realized with standard processing practice, will extend 193-nm lithography to the end of the current industry roadmap. Double exposure/etch lithography is expensive in terms of cost, throughput time, and overlay registration accuracy. However, it is less challenging compared to other possible alternatives and has the ability to break through the κ I barrier (0.25). This process, in combination with attenuated PSM (att-PSM) mask, is a good imaging solution that can reach, and most likely go beyond, the 45-nm node. Mask making requirements in a double exposure scheme will be reduced significantly. This can be appreciated by the fact that the separation of tightly-pitched mask into two less demanding pitch patterns will reduce the stringent specifications for each mask. In this study, modeling of double exposure lithography (DEL) with att-PSM masks to target 45-nm node is described. In addition, mask separation and implementation issues of optical proximity corrections (OPC) to improve process window are studied. To understand the impact of OPC on the process window, Fourier analysis of the masks has been carried out as well.

  1. Synchrotron radiation

    SciTech Connect

    Knotek, M.L.

    1987-01-01

    Synchrotron radiation has had a revolutionary effect on a broad range of scientific studies, from physics, chemistry and metallurgy to biology, medicine and geoscience. The situation during the last decade has been one of very rapid growth, there is a great vitality to the field and a capability has been given to a very broad range of scientific disciplines which was undreamed of just a decade or so ago. Here we will discuss some of the properties of synchrotron radiation that makes it so interesting and something of the sources in existence today including the National Synchrotron Light Source (NSLS). The NSLS is one of the new facilities built specifically for synchrotron radiation research and the model that was developed there for involvement of the scientific community is a good one which provides some good lessons for these facilities and others.

  2. RADIATION INTEGRATOR

    DOEpatents

    Glass, F.M.; Wilson, H.N.

    1959-02-17

    Radiation detecting and measuring systems, particularly a compact, integrating, background monitor, are discussed. One of the principal features of the system is the use of an electrometer tube where the input of the tube is directly connected to an electrode of the radiation detector and a capacitor is coupled to the tube input. When a predetermined quantity of radiation has been integrated, a trigger signal is fed to a recorder and a charge is delivered to the capacitor to render the tube inoperative. The capacitor is then recharged for the next period of operation. With this arrangement there is a substantial reduction in lead lengths and the principal components may be enclosed and hermetically sealed to insure low leakage.

  3. Changes in growth, leaf anatomy and pigment concentrations in pea under modulated UV-B field treatments

    SciTech Connect

    Day, T.A.; Howells, B.W.; Ruhland, C.T.

    1995-06-01

    In growth-chamber and greenhouse studies, garden pea is typically quite sensitive to enhanced UV-B radiation (280-320 nm). We assessed whether growth of pea was reduced under more ecologically relevant UV-B enhancements by employing modulated field lampbanks simulating 0, 16 or 24% ozone depletion. We also examined if these UV-B treatments altered leaf anatomy and concentrations of chlorophyll and UV-B-absorbing compounds, and whether this was dependent on leaf age. We used Pisum sativum mutant Argenteum which has an easily detachable epidermis that allowed us to compare concentrations in epidermal and mesophyll tissues. There were no significant UV-B effects on whole-plant growth. Of the 15 leaf-level parameters we examined, UV-B had a strong effect on only two parameters: the ratio of UV-B-absorbing compounds to chlorophyll (which increased with UV-B dose), and stomatal density of the adaxial surface (which decreased with UV-B dose). Chlorophyll concentrations tended to decrease, while the proportion of UV-B-absorbing compounds in the adaxial epidermis tended to increase with UV-B dose (p = 0.11 for both). In contrast to UV-B effects, we found strong leaf-age effects on nearly all parameters except the ratio of UV-B-absorbing compounds to chlorophyll, which remained relatively constant with leaf age.

  4. Interactions of photosynthesis with genome size and function.

    PubMed

    Raven, John A; Beardall, John; Larkum, Anthony W D; Sánchez-Baracaldo, Patricia

    2013-07-19

    Photolithotrophs are divided between those that use water as their electron donor (Cyanobacteria and the photosynthetic eukaryotes) and those that use a different electron donor (the anoxygenic photolithotrophs, all of them Bacteria). Photolithotrophs with the most reduced genomes have more genes than do the corresponding chemoorganotrophs, and the fastest-growing photolithotrophs have significantly lower specific growth rates than the fastest-growing chemoorganotrophs. Slower growth results from diversion of resources into the photosynthetic apparatus, which accounts for about half of the cell protein. There are inherent dangers in (especially oxygenic) photosynthesis, including the formation of reactive oxygen species (ROS) and blue light sensitivity of the water spitting apparatus. The extent to which photolithotrophs incur greater DNA damage and repair, and faster protein turnover with increased rRNA requirement, needs further investigation. A related source of environmental damage is ultraviolet B (UVB) radiation (280-320 nm), whose flux at the Earth's surface decreased as oxygen (and ozone) increased in the atmosphere. This oxygenation led to the requirements of defence against ROS, and decreasing availability to organisms of combined (non-dinitrogen) nitrogen and ferrous iron, and (indirectly) phosphorus, in the oxygenated biosphere. Differential codon usage in the genome and, especially, the proteome can lead to economies in the use of potentially growth-limiting elements.

  5. Protective effect of tropical highland blackberry juice (Rubus adenotrichos Schltdl.) against UVB-mediated damage in human epidermal keratinocytes and in a reconstituted skin equivalent model.

    PubMed

    Calvo-Castro, Laura; Syed, Deeba N; Chamcheu, Jean C; Vilela, Fernanda M P; Pérez, Ana M; Vaillant, Fabrice; Rojas, Miguel; Mukhtar, Hasan

    2013-01-01

    Solar ultraviolet (UV) radiation, particularly its UVB (280-320 nm) spectrum, is the primary environmental stimulus leading to skin carcinogenesis. Several botanical species with antioxidant properties have shown photochemopreventive effects against UVB damage. Costa Rica's tropical highland blackberry (Rubus adenotrichos) contains important levels of phenolic compounds, mainly ellagitannins and anthocyanins, with strong antioxidant properties. In this study, we examined the photochemopreventive effect of R. adenotrichos blackberry juice (BBJ) on UVB-mediated responses in human epidermal keratinocytes and in a three-dimensional (3D) reconstituted normal human skin equivalent (SE). Pretreatment (2 h) and posttreatment (24 h) of normal human epidermal keratinocytes (NHEKs) with BBJ reduced UVB (25 mJ cm(-2))-mediated (1) cyclobutane pyrimidine dimers (CPDs) and (2) 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) formation. Furthermore, treatment of NHEKs with BBJ increased UVB-mediated (1) poly(ADP-ribose) polymerase cleavage and (2) activation of caspases 3, 8 and 9. Thus, BBJ seems to alleviate UVB-induced effects by reducing DNA damage and increasing apoptosis of damaged cells. To establish the in vivo significance of these findings to human skin, immunohistochemistry studies were performed in a 3D SE model, where BBJ was also found to decrease CPDs formation. These data suggest that BBJ may be developed as an agent to ameliorate UV-induced skin damage. PMID:23711186

  6. How does the 'ancient' asexual Philodina roseola (Rotifera: Bdelloidea) handle potential UVB-induced mutations?

    PubMed

    Fischer, Claus; Ahlrichs, Wilko H; Buma, Anita G J; van de Poll, Willem H; Bininda-Emonds, Olaf R P

    2013-08-15

    Like other obligate asexuals, bdelloid rotifers are expected to suffer from degradation of their genomes through processes including the accumulation of deleterious mutations. However, sequence-based analyses in this regard remain inconclusive. Instead of looking for historical footprints of mutations in these ancient asexuals, we directly examined the susceptibility and ability to repair point mutations by the bdelloid Philodina roseola by inducing cyclobutane-pyrimidine dimers (CPDs) via exposure to UVB radiation (280-320 nm). For comparison, we performed analogous experiments with the facultative asexual monogonont rotifer Brachionus rubens. Different strategies were found for the two species. Philodina roseola appeared to shield itself from CPD induction through uncharacterized UV-absorbing compounds and, except for the genome reconstruction that occurs after desiccation, was largely unable to repair UVB-induced damage. By contrast, B. rubens was more susceptible to UVB irradiation, but could repair all induced damage in ~2 h. In addition, whereas UV irradiation had a significant negative impact on the reproductive output of P. roseola, and especially so after desiccation, that of B. rubens was unaffected. Although the strategy of P. roseola might suffice under natural conditions where UVB irradiation is less intense, the lack of any immediate CPD repair mechanisms in this species remains perplexing. It remains to be investigated how typical these results are for bdelloids as a group and therefore how reliant these animals are on desiccation-dependent genome repair to correct potential DNA damage given their obligate asexual lifestyle.

  7. Genome-wide analysis of gene expression reveals function of the bZIP transcription factor HY5 in the UV-B response of Arabidopsis.

    PubMed

    Ulm, Roman; Baumann, Alexander; Oravecz, Attila; Máté, Zoltán; Adám, Eva; Oakeley, Edward J; Schäfer, Eberhard; Nagy, Ferenc

    2004-02-01

    The light environment is a key factor that governs a multitude of developmental processes during the entire life cycle of plants. An important and increasing part of the incident sunlight encompasses a segment of the UV-B region (280-320 nm) that is not entirely absorbed by the ozone layer in the stratosphere of the earth. This portion of the solar radiation, which inevitably reaches the sessile plants, can act both as an environmental stress factor and an informational signal. To identify Arabidopsis genes involved in the UV response, we monitored the gene expression profile of UV-B-irradiated seedlings by using high-density oligonucleotide microarrays comprising almost the full Arabidopsis genome (>24,000 genes). A robust set of early low-level UV-B-responsive genes, 100 activated and 7 repressed, was identified. In all cases analyzed, UV-B induction was found to be independent of known photoreceptors. This group of genes is suggested to represent the molecular readout of the signaling cascade triggered by the elusive UV-B photoreceptor(s). Moreover, our analysis identified interactions between cellular responses to different UV-B ranges that led us to postulate the presence of partially distinct but interacting UV-B perception and signaling mechanisms. Finally, we demonstrate that the bZIP transcription factor HY5 is required for UV-B-mediated regulation of a subset of genes.

  8. In-situ measurements of tropospheric and stratospheric ozone over Hyderabad

    NASA Astrophysics Data System (ADS)

    Manchanda, R. K.; Sreenivasan, S.; Sinha, P. R.

    The Study of the ozone concentration and its variability is one of the key indexes for environmental and ecological degradation While the stratospheric ozone absorbs the harmful ultraviolet radiation between 280-320 nm band, the tropospheric ozone is formed in the elevated layers up to 10km above ground level through the photochemical decomposition of the precursor gases like NOx, VOCs and non-methane hydrocarbons (NMHCs) released from the earth surface. Ozone studies are also vital for the understanding of solar terrestrial coupling as well as the ozone chemistry on a given site and its surroundings. Continuous measurements of vertical profile of ozone and various meteorological parameters (i.e. temperature, pressure, humidity, wind speed and direction) over one year period were made over Hyderabad using high altitude plastic balloons, in order to investigate i. variations of ozone in the troposphere and stratosphere, ii. stratospheric warming iii. coupling between upper troposphere and lower stratosphere (UTLS) region. Ozonesonde (Electro Chemical Cell) coupled with GPS RS80-15N radiosonde was used for the measurement of Ozone and meteorological parameters.

  9. Radiation receiver

    DOEpatents

    Hunt, Arlon J.

    1983-01-01

    The apparatus for collecting radiant energy and converting same to alternate energy form includes a housing having an interior space and a radiation transparent window allowing, for example, solar radiation to be received in the interior space of the housing. Means are provided for passing a stream of fluid past said window and for injecting radiation absorbent particles in said fluid stream. The particles absorb the radiation and because of their very large surface area, quickly release the heat to the surrounding fluid stream. The fluid stream particle mixture is heated until the particles vaporize. The fluid stream is then allowed to expand in, for example, a gas turbine to produce mechanical energy. In an aspect of the present invention properly sized particles need not be vaporized prior to the entrance of the fluid stream into the turbine, as the particles will not damage the turbine blades. In yet another aspect of the invention, conventional fuel injectors are provided to inject fuel into the fluid stream to maintain the proper temperature and pressure of the fluid stream should the source of radiant energy be interrupted. In yet another aspect of the invention, an apparatus is provided which includes means for providing a hot fluid stream having hot particles disbursed therein which can radiate energy, means for providing a cooler fluid stream having cooler particles disbursed therein, which particles can absorb radiant energy and means for passing the hot fluid stream adjacent the cooler fluid stream to warm the cooler fluid and cooler particles by the radiation from the hot fluid and hot particles.

  10. Radiation receiver

    DOEpatents

    Hunt, A.J.

    1983-09-13

    The apparatus for collecting radiant energy and converting same to alternate energy form includes a housing having an interior space and a radiation transparent window allowing, for example, solar radiation to be received in the interior space of the housing. Means are provided for passing a stream of fluid past said window and for injecting radiation absorbent particles in said fluid stream. The particles absorb the radiation and because of their very large surface area, quickly release the heat to the surrounding fluid stream. The fluid stream particle mixture is heated until the particles vaporize. The fluid stream is then allowed to expand in, for example, a gas turbine to produce mechanical energy. In an aspect of the present invention properly sized particles need not be vaporized prior to the entrance of the fluid stream into the turbine, as the particles will not damage the turbine blades. In yet another aspect of the invention, conventional fuel injectors are provided to inject fuel into the fluid stream to maintain the proper temperature and pressure of the fluid stream should the source of radiant energy be interrupted. In yet another aspect of the invention, an apparatus is provided which includes means for providing a hot fluid stream having hot particles disbursed therein which can radiate energy, means for providing a cooler fluid stream having cooler particles disbursed therein, which particles can absorb radiant energy and means for passing the hot fluid stream adjacent the cooler fluid stream to warm the cooler fluid and cooler particles by the radiation from the hot fluid and hot particles. 5 figs.

  11. Measurements of the diffuse ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Fix, John D.; Craven, John D.; Frank, Louis A.

    1989-01-01

    The imaging instrumentation on the Dynamics Explorer 1 satellite has been used to measure the intensity of the diffuse ultraviolet radiation on two great circles about the sky. It is found that the isotropic component of the diffuse ultraviolet radiation (possibly of extragalactic origin) has an intensity of 530 + or - 80 units (a unit is 1 photon per sq cm s A sr) at a wavelength of 150 nm. The Galactic component of the diffuse ultraviolet radiation has a dependence on Galactic latitude which requires strongly forward scattering particles if it is produced by dust above the Galactic plane.

  12. Isolation of Enterococcus faecium NM113, Enterococcus faecium NM213 and Lactobacillus casei NM512 as novel probiotics with immunomodulatory properties.

    PubMed

    Mansour, Nahla M; Heine, Holger; Abdou, Sania M; Shenana, Mohamed E; Zakaria, Mohamed K; El-Diwany, Ahmed

    2014-10-01

    Probiotics, defined as living bacteria that are beneficial for human health, mainly function through their immunomodulatory abilities. Hence, these microorganisms have proven successful for treating diseases resulting from immune deregulation. The aim of this study was to find novel candidates to improve on and complement current probiotic treatment strategies. Of 60 lactic acid bacterial strains that were isolated from fecal samples of healthy, full-term, breast-fed infants, three were chosen because of their ability to activate human immune cells. These candidates were then tested with regard to immunomodulatory properties, antimicrobial effects on pathogens, required pharmacological properties and their safety profiles. To identify the immunomodulatory structures of the selected isolates, activation of specific innate immune receptors was studied. The three candidates for probiotic treatment were assigned Enterococcus faecium NM113, Enterococcus faecium NM213 and Lactobacillus casei NM512. Compared with the established allergy-protective strain Lactococcus lactis G121, these isolates induced release of similar amounts of IL-12, a potent inducer of T helper 1 cells. In addition, all three neonatal isolates had antimicrobial activity against pathogens. Analysis of pharmacological suitability showed high tolerance of low pH, bile salts and pancreatic enzymes. In terms of safe application in humans, the isolates were sensitive to three antibiotics (chloramphenicol, tetracycline and erythromycin). In addition, the Enterococcus isolates were free from the four major virulence genes (cylA, agg, efaAfs and ccf). Moreover, the isolates strongly activated Toll-like receptor 2, which suggests lipopeptides as their active immunomodulatory structure. Thus, three novel bacterial strains with great potential as probiotic candidates and promising immunomodulatory properties have here been identified and characterized.

  13. Self-frequency-doubled vibronic yellow Yb:YCOB laser at the wavelength of 570  nm.

    PubMed

    Fang, Qiannan; Lu, Dazhi; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang

    2016-03-01

    A watt-level self-frequency-doubled yellow laser at the 570 nm wavelength was realized by taking advantage of the vibronic emission of a Yb3+ doped calcium yttrium oxoborate (Yb:YCOB) crystal cut along the optimized direction out of the principal planes with the maximum effective nonlinear coefficient. Fluorescence spectroscopic properties of Yb:YCOB were studied, which showed that it had broad and anisotropic vibronic emission with a small peak at ∼1130  nm. By suppressing the electronic emission, the polarized vibronic Yb:YCOB radiation was realized with the fundamental wavelength shifting from 1130 nm to 1140 nm. By employing the self-frequency-doubling behavior of Yb:YCOB, the self-frequency-doubled yellow laser was achieved with a maximum output power of 1.08 W at 570 nm. This work provides an unprecedented and efficient way to generate yellow lasers with a compact microchip structure that may have promising applications in some regimes including medicine, entertainment, and scientific research. PMID:26974101

  14. Self-frequency-doubled vibronic yellow Yb:YCOB laser at the wavelength of 570  nm.

    PubMed

    Fang, Qiannan; Lu, Dazhi; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang

    2016-03-01

    A watt-level self-frequency-doubled yellow laser at the 570 nm wavelength was realized by taking advantage of the vibronic emission of a Yb3+ doped calcium yttrium oxoborate (Yb:YCOB) crystal cut along the optimized direction out of the principal planes with the maximum effective nonlinear coefficient. Fluorescence spectroscopic properties of Yb:YCOB were studied, which showed that it had broad and anisotropic vibronic emission with a small peak at ∼1130  nm. By suppressing the electronic emission, the polarized vibronic Yb:YCOB radiation was realized with the fundamental wavelength shifting from 1130 nm to 1140 nm. By employing the self-frequency-doubling behavior of Yb:YCOB, the self-frequency-doubled yellow laser was achieved with a maximum output power of 1.08 W at 570 nm. This work provides an unprecedented and efficient way to generate yellow lasers with a compact microchip structure that may have promising applications in some regimes including medicine, entertainment, and scientific research.

  15. X-ray optical system for imaging laser plumes with a spatial resolution of up to 70 nm

    NASA Astrophysics Data System (ADS)

    Nechai, A. N.; Pestov, A. E.; Polkovnikov, V. N.; Salashchenko, N. N.; Toropov, M. N.; Chkhalo, N. I.; Tsybin, N. N.; Shcherbakov, A. V.

    2016-04-01

    We consider an X-ray optical system which permits obtaining laser plume images at a wavelength of 13.5 nm with a resolution of up to 70 nm. The X-ray optical system comprises an X-ray Schwarzschild objective made up of two aspherical multilayer mirrors, a scintillator (YAG : Ce ceramics), which converts X-rays to the visible radiation, and a visible-optical system, which images the scintillator surface onto a CCD camera. The spatial resolution of the system is limited by the resolution of the optical system (0.7 μm) and the magnification (10×) of the X-ray objective and is as high as 70 nm. The effect of Schwarzschild objective mirror shapes on the spatial resolution is analysed. The profile of concave mirror aspherisation is considered, which provides the attainment of the diffraction-limited quality of the objective. Data are given for the quantum efficiency of the system at a wavelength of 13.5 nm. We describe the experimental test bench intended for studying the developed X-ray optical system and outline the first experimental data which illustrate its efficiency. Owing to the natural division into the 'X-ray' and 'visible' parts, the optical system under discussion permits an easy change of the magnification and the field of view without realigning the X-ray optical elements. The wavelength may be varied in a range between 3 and 40 nm by changing the multilayer mirrors.

  16. RADIATION SOURCES

    DOEpatents

    Brucer, M.H.

    1958-04-15

    A novel long-lived source of gamma radiation especially suitable for calibration purposes is described. The source of gamma radiation is denoted mock iodine131, which comprises a naixture of barium-133 and cesium-137. The barium and cesium are present in a barium-cesium ratio of approximately 5.7/1 to 14/1, uniformly dispersed in an ion exchange resin and a filter surrounding the resin comprised of a material of atomic number below approximately 51, and substantially 0.7 to 0.9 millimeter thick.

  17. Radiation dermatitis

    SciTech Connect

    Shack, R.B.; Lynch, J.B.

    1987-04-01

    Even in this era of modern radiotherapy, injuries associated with the medical and industrial use of radiation devices will continue to pose a difficult problem for the reconstructive surgeon. It must be borne in mind that the single most serious hazard to surgery in irradiated tissue is the lodgement of bacteria in tissue rendered avascular by the radiation and the secondary necrosis from the infection itself. The basic principles of wound management must be augmented by thorough knowledge of the use of well-vascularized muscle and musculocutaneous flap to provide adequate, blood-rich, soft-tissue coverage.

  18. Characterization of single 1.8-nm Au nanoparticle attachments on AFM tips for single sub-4-nm object pickup

    NASA Astrophysics Data System (ADS)

    Cheng, Hui-Wen; Chang, Yuan-Chih; Tang, Song-Nien; Yuan, Chi-Tsu; Tang, Jau; Tseng, Fan-Gang

    2013-11-01

    This paper presents a novel method for the attachment of a 1.8-nm Au nanoparticle (Au-NP) to the tip of an atomic force microscopy (AFM) probe through the application of a current-limited bias voltage. The resulting probe is capable of picking up individual objects at the sub-4-nm scale. We also discuss the mechanisms involved in the attachment of the Au-NP to the very apex of an AFM probe tip. The Au-NP-modified AFM tips were used to pick up individual 4-nm quantum dots (QDs) using a chemically functionalized method. Single QD blinking was reduced considerably on the Au-NP-modified AFM tip. The resulting AFM tips present an excellent platform for the manipulation of single protein molecules in the study of single protein-protein interactions.

  19. Periodic nanostructures on titanium dioxide film produced using femtosecond laser with wavelengths of 388 nm and 775 nm.

    PubMed

    Shinonaga, Togo; Tsukamoto, Masahiro; Miyaji, Godai

    2014-06-16

    Titanium dioxide (TiO2) film is an important biomaterial used to improve the biocompatibility of titanium (Ti). We have used a film coating method with an aerosol beam and femtosecond laser irradiation to form periodic structures on biomaterials for control of the cell spreading. The control of cell spreading on biomaterials is important for the development of advanced biomaterials. In this study, nanostructures with periods of 130 and 230 nm were formed on a film using a femtosecond laser with wavelengths of 388 and 775 nm, respectively. The nanostructure period on the film was 30% of the laser wavelengths. Periods produced with wavelengths of 388 and 775 nm were calculated using a surface plasmon polariton (SPP) model and the experimental results for both wavelengths were in the range of the calculated periods, which suggests that the mechanism for the formation of the periodic nanostructures on the film with a femtosecond laser was due to the excitation of SPPs.

  20. Imaging challenges in 20nm and 14nm logic nodes: hot spots performance in Metal1 layer

    NASA Astrophysics Data System (ADS)

    Timoshkov, V.; Rio, D.; Liu, H.; Gillijns, W.; Wang, J.; Wong, P.; Van Den Heuvel, D.; Wiaux, V.; Nikolsky, P.; Finders, J.

    2013-10-01

    The 20nm Metal1 layer, based on ARM standard cells, has a 2D design with minimum pitch of 64nm. This 2D design requires a Litho-Etch-Litho-Etch (LELE) double patterning. The whole design is divided in 2 splits: Me1A and Me1B. But solution of splitting conflicts needs stitching at some locations, what requires good Critical Dimension (CD) and overlay control to provide reliable contact between 2 stitched line ends. ASML Immersion NXT tools are aimed at 20 and 14nm logic production nodes. Focus control requirements become tighter, as existing 20nm production logic layouts, based on ARM, have about 50-60nm focus latitude and tight CD Uniformity (CDU) specifications, especially for line ends. IMEC inspected 20nm production Metal1 ARM standard cells with a Negative Tone Development (NTD) process using the Process Window Qualification-like technique experimentally and by Brion Tachyon LMC by simulations. Stronger defects were found thru process variations. A calibrated Tachyon model proved a good overall predictability capability for this process. Selected defects are likely to be transferred to hard mask during etch. Further, CDU inspection was performed for these critical features. Hot spots showed worse CD uniformity than specifications. Intra-field CDU contribution is significant in overall CDU budget, where reticle has major impact due to high MEEF of hot spots. Tip-to-Tip and tip-to-line hot spots have high MEEF and its variation over the field. Best focus variation range was determined by best focus offsets between hot spots and its variation within the field.

  1. High average power, narrow band 248 nm alexandrite laser system

    SciTech Connect

    Kuper, J.W.; Chin, T.C.; Papanestor, P.A.

    1994-12-31

    A compact line-narrowed 248 nm solid state laser source operating at 15 mJ {at} 100 Hz PRF was demonstrated. Constraints due to thermal loading of components were addressed. Tradeoffs between pulse energy and repetition rate were investigated. A method for overcoming thermal dephasing in the THG material was achieved by scanning a slab shaped crystal.

  2. 78 FR 67210 - Santa Clara Pueblo Disaster #NM-00038

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-08

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Santa Clara Pueblo Disaster NM-00038 AGENCY: U.S. Small Business Administration. ACTION: Notice...: Submit completed loan applications to: U.S. Small Business Administration, Processing and...

  3. 77 FR 62481 - Radio Broadcasting Services; Crownpoint, NM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-15

    ... COMMISSION 47 CFR Part 73 Radio Broadcasting Services; Crownpoint, NM AGENCY: Federal Communications....415 and 1.420. List of Subjects in 47 CFR Part 73 Radio, Radio broadcasting. Federal Communications... preamble, the Federal Communications Commission proposes to amend 47 CFR Part 73 as follows: PART...

  4. Gain measurements at 5 nm in nickel-like ytterbium

    SciTech Connect

    MacGowan, B.J.; Bourgade, J.L.; Combis, P.; Keane, C.J.; Louis-Jacquet, M.; Matthews, D.L.; Naccache, D.; Stone, G.; Thiell, G.; Whelan, D.A.

    1988-03-01

    Soft x-ray gain has been demonstrated at 5.03 nm within a laser produced plasma of Ni-like ytterbium. Experiments will also be described with higher Z Ni-like ions which can produce even shorter wavelength x-ray laser transition. 3 refs.

  5. Corneal injury from 1318-nm single laser pulses

    NASA Astrophysics Data System (ADS)

    Roach, William P.; Ketzenberger, Bryan K.; Burton, Margaret B.; Johnson, Thomas E.

    2002-06-01

    Threshold, median effective dose, and the mechanism of laser-tissue interaction are not well defined at the 1318-nm wavelength for human corneal exposures. The goals of this research effort are to identify at-risk groups, characterize the lesions imposed, and establish the ED50 for single pulse 1318-nm laser exposures on the cornea. A Neodymium: Yttrium Aluminum Garnet (Nd:YAG) laser was used to deliver 1318-nm wavelength pulses to the corneas of ten female Dutch Belted rabbits (Oryctolagus cuniculus). Single pulses of 0.5-ms duration and radiant beam energy ranging from 116 to 2250 joules/per square centimeter (J/cm2) were used. Exposure sites were clinically evaluated acutely, one hour and twenty-four hours post-exposure for the presence of a lesion. Results from the twenty-four hour evaluation were used to determine the ED50. Grossly, the lesions appeared as small, circular, well-demarcated, white, opaque lesions. Histologically, the lesions appeared as conical shaped coagulative necrosis with the base of the lesion at the epithelial surface of the cornea and extending to the apex at the endothelial border of the cornea. The ED50 for 1318-nm exposures to the rabbit cornea was determined to be 383 J/cm2 for a 0.1-mm spot size as measured at 1/e2.

  6. Pushing EUV lithography development beyond 22-nm half pitch

    SciTech Connect

    Naulleau, Patrick; Anderson, Christopher N.; Baclea-an, Lorie-Mae; Denham, Paul; George, Simi; Goldberg, Kenneth A.; Goldstein, Michael; Hoef, Brian; Jones, Gideon; Koh, Chawon; La Fontaine, Bruno; Montogomery, Warren; Wallow, Tom

    2009-06-30

    Microfield exposure tools (METs) have and continue to play a dominant role in the development of extreme ultraviolet (EUV) resists and masks. One of these tools is the SEMATECH Berkeley 0.3 numerical aperture (NA) MET. Here we investigate the possibilities and limitations of using the 0.3-NA MET for sub-22-nm half-pitch development. We consider mask resolution limitations and present a method unique to the centrally obscured MET allowing these mask limitations to be overcome. We also explore projection optics resolution limits and describe various illumination schemes allowing resolution enhancement. At 0.3-NA, the 0.5 k1 factor resolution limit is 22.5 nm meaning that conventional illumination is of limited utility for sub-22-nm development. In general resolution enhancing illumination encompasses increased coherence. We study the effect of this increased coherence on line-edge roughness, which along with resolution is another crucial factor in sub-22-nm resist development.

  7. Surface Photometry of the Southern Milky Way at 170 NM

    NASA Astrophysics Data System (ADS)

    Hansen, J.; Schlosser, W.; Schmidtobreick, L.; Koczet, P.

    As part of the D2-Space-Shuttle-Mission in 1993, the GAUSS-Camera has obtained photographic images of the Milky Way in various passbands in the Ultraviolet. Each film covers an area of the sky of about 140^\\circ. Six images were obtained at 170 nm, but only three of them could be used. The calibration has been done using the catalogued intensities of stars and transforming them into surface brightnesses. Then the stars on the images have been filtered out and the Shuttle-Glow has been eliminated. The images finally have been transformed into maps of the Milky Way in galactic coordinates l, b. These maps cover the Milky Way between the Galactic Center and Vela (360^\\circ <= l <= 270^\\circ, - -25^\\circ <= b <= 35^\\circ) and include dark clouds, reflection nebulae and bright open clusters. They are a perfect tool to investigate the distribution of these objects and therefore the global structure of the Milky Way. The image of the Milky Way at 170 nm is heavily dominated by interstellar extinction, leading to high intensity gradients all over the galactic plane. The images at 217 nm and 280 nm, also obtained by the GAUSS-Camera, and previous photometries taken in U, B, V and R have been used for comparison.

  8. 76 FR 18289 - New Mexico Disaster #NM-00020

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-01

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION New Mexico Disaster NM-00020 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY... State of New Mexico (FEMA- 1962-DR), dated 03/24/2011. Incident: Severe Winter Storm and Extreme...

  9. 77 FR 55523 - New Mexico Disaster #NM-00029

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-10

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION New Mexico Disaster NM-00029 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY... State of New Mexico (FEMA- 4079-DR), dated 08/24/2012. Incident: Flooding. Incident Period:...

  10. 75 FR 57538 - New Mexico Disaster # NM-00016

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-21

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION New Mexico Disaster NM-00016 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY... State of New Mexico (FEMA- 1936-DR), dated 09/13/2010. Incident: Severe Storms and Flooding....

  11. 77 FR 41874 - New Mexico Disaster #NM-00025

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-16

    ... ADMINISTRATION New Mexico Disaster NM-00025 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of New Mexico dated 07/09... adversely affected by the disaster: Primary Counties: Lincoln. Contiguous Counties: New Mexico: Chaves,...

  12. 78 FR 61999 - New Mexico Disaster #NM-00037

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-10

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION New Mexico Disaster NM-00037 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY... State of New Mexico (FEMA- 4148-DR), dated 09/30/2013. Incident: Severe Storms and Flooding....

  13. 77 FR 63409 - New Mexico Disaster Number NM-00029

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-16

    ... ADMINISTRATION New Mexico Disaster Number NM-00029 AGENCY: U.S. Small Business Administration. ACTION: Amendment... Assistance Only for the State of New Mexico (FEMA-4079-DR), dated 08/24/2012. Incident: Flooding. Incident... Non-Profit organizations in the State of NEW MEXICO, dated 08/24/2012, is hereby amended to...

  14. 76 FR 2431 - New Mexico Disaster #NM-00016

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-13

    ... ADMINISTRATION New Mexico Disaster NM-00016 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1... Only for the State of New Mexico (FEMA-1936-DR), dated 09/13/2010. Incident: Severe Storms and Flooding... Private Non-Profit organizations in the State of NEW MEXICO, dated 09/13/2010, is hereby amended...

  15. 78 FR 66982 - New Mexico Disaster #NM-00035

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-07

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION New Mexico Disaster NM-00035 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY... State of New Mexico (FEMA- 4152-DR), dated 10/29/2013. Incident: Severe storms, flooding, and...

  16. 78 FR 73581 - New Mexico Disaster Number NM-00035

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-06

    ... ADMINISTRATION New Mexico Disaster Number NM-00035 AGENCY: U.S. Small Business Administration. ACTION: Amendment... Assistance Only for the State of New Mexico (FEMA-4152-DR), dated 10/29/2013. Incident: Severe Storms... disaster declaration for Private Non-Profit organizations in the State of New Mexico, dated 10/29/2013,...

  17. 76 FR 76801 - New Mexico Disaster #NM-00024

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-08

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION New Mexico Disaster NM-00024 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY... State of New Mexico (FEMA- 4047-DR), dated 11/23/2011. Incident: Flooding. Incident Period:...

  18. 76 FR 81553 - New Mexico Disaster Number NM-00024

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-28

    ... ADMINISTRATION New Mexico Disaster Number NM-00024 AGENCY: U.S. Small Business Administration. ACTION: Amendment... Assistance Only for the State of New Mexico (FEMA-4047-DR), dated 11/23/2011. Incident: Flooding. Incident... Non-Profit organizations in the State of New Mexico, dated 11/23/2011, is hereby amended to...

  19. 77 FR 47907 - New Mexico Disaster #NM-00025

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-10

    ... ADMINISTRATION New Mexico Disaster NM-00025 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Administrative declaration of a disaster for the State of NEW MEXICO...'s declaration for the State of New Mexico, dated 07/09/2012 is hereby amended to establish...

  20. 78 FR 72141 - New Mexico Disaster Number NM-00037

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-02

    ... ADMINISTRATION New Mexico Disaster Number NM-00037 AGENCY: U.S. Small Business Administration. ACTION: Amendment... Assistance Only for the State of New Mexico (FEMA-4148-DR), dated 09/30/2013. Incident: Severe Storms and... Private Non-Profit organizations in the State of New Mexico, dated 09/30/2013, is hereby amended...