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Sample records for surface spectral uv

  1. UV spectral filtering by surface structured multilayer mirrors.

    Science.gov (United States)

    Huang, Qiushi; Paardekooper, Daniel Mathijs; Zoethout, Erwin; Medvedev, V V; van de Kruijs, Robbert; Bosgra, Jeroen; Louis, Eric; Bijkerk, Fred

    2014-03-01

    A surface structured extreme ultraviolet multilayer mirror was developed showing full band suppression of UV (λ=100-400  nm) and simultaneously a high reflectance of EUV light (λ=13.5  nm). The surface structure consists of Si pyramids, which are substantially transparent for EUV but reflective for UV light. The reflected UV is filtered out by blazed diffraction, interference, and absorption. A first demonstration pyramid structure was fabricated on a multilayer by using a straightforward deposition technique. It shows an average suppression of 14 times over the whole UV range and an EUV reflectance of 56.2% at 13.5 nm. This robust scheme can be used as a spectral purity solution for all XUV sources that emit longer wavelength radiation as well.

  2. UV spectral filtering by surface structured multilayer mirrors

    NARCIS (Netherlands)

    Huang, Q.; Paardekooper, Daniel Mathijs; Zoethout, E.; Medvedev, V. V.; van de Kruijs, Robbert; Bosgra, Jeroen; Louis, Eric; F. Bijkerk,

    2014-01-01

    A surface structured extreme ultraviolet multilayer mirror was developed showing full band suppression of UV (lambda = 100-400 nm) and simultaneously a high reflectance of EUV light (lambda = 13.5 nm). The surface structure consists of Si pyramids, which are substantially transparent for EUV but

  3. UV spectral filtering by surface structured multilayer mirrors

    NARCIS (Netherlands)

    Huang, Q.; Paardekooper, Daniel Mathijs; Zoethout, E.; Medvedev, V. V.; van de Kruijs, Robbert; Bosgra, Jeroen; Louis, Eric; F. Bijkerk,

    2014-01-01

    A surface structured extreme ultraviolet multilayer mirror was developed showing full band suppression of UV (lambda = 100-400 nm) and simultaneously a high reflectance of EUV light (lambda = 13.5 nm). The surface structure consists of Si pyramids, which are substantially transparent for EUV but ref

  4. Comparison of TOMS retrievals and UVMRP measurements of surface spectral UV radiation in the United States

    Directory of Open Access Journals (Sweden)

    M. Xu

    2010-09-01

    Full Text Available Surface noontime spectral ultraviolet (UV irradiances during May-September of 2000–2004 from the total ozone mapping spectrometer (TOMS satellite retrievals are systematically compared with the ground measurements at 27 climatological sites maintained by the USDA UV-B Monitoring and Research Program. The TOMS retrievals are evaluated by two cloud screening methods and local air quality conditions to determine their bias dependencies on spectral bands, cloudiness, aerosol loadings, and air pollution. Under clear-sky conditions, TOMS retrieval biases vary from −3.4% (underestimation to 23.6% (overestimation. Averaged over all sites, the relative mean biases for 305, 311, 325, and 368 nm are respectively 15.4, 7.9, 7.6, and 7.0% (overestimation. The bias enhancement for 305 nm by approximately twice that of other bands likely results from absorption by gaseous pollutants (SO2, O3, and aerosols that are not included in the TOMS algorithm. For all bands, strong positive correlations of the TOMS biases are identified with aerosol optical depth, which explains nearly 50% of the variances of TOMS biases. The more restrictive in-situ cloud screening method reduces the biases by 3.4–3.9% averaged over all sites. This suggests that the TOMS biases from the in-situ cloud contamination may account for approximately 25% for 305 nm and 50% for other bands of the total bias. The correlation coefficients between total-sky and clear-sky biases across 27 sites are 0.92, 0.89, 0.83, and 0.78 for 305, 311, 325, and 368 nm, respectively. The results show that the spatial characteristics of the TOMS retrieval biases are systematic, representative of both clear and total-sky conditions.

  5. Infrared spectral investigations of UV irradiated nucleobases adsorbed on mineral surfaces

    Science.gov (United States)

    Fornaro, Teresa; Brucato, John Robert; Pace, Emanuele; Guidi, Mariangela Cestelli; Branciamore, Sergio; Pucci, Amaranta

    2013-09-01

    The interaction between electromagnetic radiation and bio-molecules in heterogeneous environments is a prebiotically relevant process. Minerals may have a pivotal role in the prebiotic evolution of complex chemical systems, mediating the effects of electromagnetic radiation, influencing the photostability of bio-molecules, catalyzing important chemical reactions and/or protecting molecules against degradation. In particular, nucleobases are relevant bio-molecules to investigate both in the prebiotic context, because they are coding components of nucleic acids, and from the standpoint of the survival of biological systems in space conditions. Several studies on the photodynamics of nucleobases suggest that their structure could have been naturally selected for the ability to dissipate electronic energy through ultrafast photophysical decay. Considering the putative involvement of minerals in the prebiotic chemistry, it is necessary to study the photostability of nucleobases under space conditions in the presence of mineral matrices, to investigate both the prebiotic processes that might have had a role in the development of the first living entities on Earth and the physical and chemical processes occurring in extraterrestrial environments. We focused our study on the characterization of the nature of the interaction between nucleobases and the surface of the minerals magnesium oxide and forsterite by infrared vibrational spectroscopy. We observed that most of the characteristic bands of pure nucleobases vanished when adsorbed on magnesium oxide. On the contrary, in the case of adenine and uracil adsorbed on forsterite, very intense nucleobase absorption peaks appeared. This phenomenon pertains to the surface selection rules changes related to molecular orientation. Moreover, based on the vibrational shifts, we deduced the molecular interaction sites with the mineral surfaces. Furthermore, we investigated the photostability of nucleobases adsorbed on such minerals

  6. UV Spectral Synthesis of Vega

    CERN Document Server

    Fitzpatrick, E L

    2010-01-01

    We show that the UV spectrum (1280-3200 A) of the "superficially normal" A-star Vega, as observed by the IUE satellite at a resolution comparable to the star's rotational broadening width, can be fit remarkably well by a single-temperature synthetic spectrum based on LTE atmosphere models and a newly constructed UV line list. If Vega were a normal, equator-on, slow-rotating star, then its spectrum and our analysis would indicate a temperature of Teff ~ 9550 K, surface gravity of log g ~ 3.7, general surface metallicity of [m/H] ~ -0.5, and a microturbulence velocity of v(turb) ~ 2.0 km/s. Given its rapid rotation and nearly pole-on orientation, however, these parameters must be regarded as representing averages across the observed hemisphere. Modeling the complex UV line spectrum has allowed us to determine the specific surface abundances for 17 different chemical elements, including CNO, the light metals, and the iron group elements. The resultant abundance pattern agrees in general with previous results, al...

  7. UV properties of Galileons: Spectral Densities

    CERN Document Server

    Keltner, Luke

    2015-01-01

    We propose a picture for the UV properties of Galileon field theories. We conjecture that Galileons, and all theories incorporating the Vainshtein mechanism, fall into Jaffe's class of `non-localizable' field theories characterized by an exponential growth in their Kallen-Lehmann spectral densities. Similar properties have been argued to arise for Little String Theories and M-theory. For such theories, the notion of micro-causality and the time ordering used to define the S-matrix and correlation functions must be modified, and we give a Lorentz invariant prescription for how this can be achieved. In common with General Relativity (GR), the scattering amplitudes for Galileons are no longer expected to satisfy polynomial boundedness away from the forward scattering or fixed physical momentum transfer limits. This is a reflection of the fact that these theories are fundamentally gravitational and not local field theories. We attribute this to the existence of a locality bound for Galileons, analogous to the Gid...

  8. UV/EUV spectral synthesis in spherical symmetry

    Science.gov (United States)

    Haberreiter, M.; Fontenla, J.

    2009-04-01

    The Sun's varying output in the UV/EUV has strong effect on the Earth's ionosphere and e.g. satellite positioning. We present latest progress in modeling the solar UV/EUV irradiance spectrum based on physical principles. We use the Solar Radiation Physical Modeling (SRPM) system to calculate the solar UV/EUV spectrum for the wavelength range from 10 to 180 nm. We solve the full NLTE for the most abundant elements from H to Fe up to ion charge 2. For the higher ionization states we solve the statistical equation with an optically thin approach, i.e. using the collision strengths and spontaneous emission. Currently we account for a total number of 14 000 atomic levels and 170 000 spectral lines. For computing the optically thin coronal spectrum we use line of sight calculation in spherical symmetry, which allows us to correctly calculate the contribution of the corona to the irradiance spectrum. Inputs to our calculations are 1D atmosphere structures for the chromosphere and transition region for different solar surface features and different sets of coronal temperature structures for coronal features. We discuss the differences of the coronal structures and compare the synthetic UV/EUV spectra with observations such as the spectrum taken with the EVE rocket instrument on April 14, 2008 and the EUV spectrum taken with the SOLAR platform on the ISS.

  9. Spectral Measurements of Aerosol Absorption from UV to VISIBLE

    Science.gov (United States)

    Krotkov, N. A.; Labow, G.; Herman, J.; Bhartia, P. K.; Slusser, J.; Durham, B.; Janson, G.; Wilson, C.; Disterhoft, P.; Cede, A.; Abuhassan, N.; Eck, T. F.; Holben, B.; Bais, A.; Rapsomanikis, S.

    2007-05-01

    Amount of solar radiation reaching the Earth's surface can be strongly influenced by aerosol absorption. The aerosol absorption optical thickness (AAOT) in the visible and near IR (440 nm- 1020nm) is routinely produced from almucantar measurements made by the CIMEL instruments in the AERONET network. AAOT in the UV (300nm- 368nm) have been derived from the total and diffuse hemispherical flux measurements made by UV- Multifilter Rotating Shadowband Radiometer (UV-MFRSR, Yankee Environmental Systems, Inc.) instruments. However, no direct comparisons between these two methods exist because the CIMEL wavelengths (used in almucantar retrievals) do not overlap with the UV-MFRSR wavelengths. To enable direct comparisons between the two techniques, we have modified our UV-MFRSR, part of USDA UVB Monitoring and Research Network, by replacing standard 300nm filter with 440nm filter used in AERONET network. The instrument has been deployed at Mauna Loa Observatory, at NASA GSFC in Greenbelt, MD (July 2005 - June 2006) and during SCOUT-03 field campaign in Thessaloniki, Greece in July 2006. During these deployments the instrument's calibration was monitored daily using co-located AERONET and BREWER direct sun measurements of aerosol extinction optical thickness (AOT). Between the deployments the instrument was thoroughly calibrated at the NOAA Central UV Calibration Facility in Boulder, Colorado. We find that the UV-MSFRSR instrument is highly susceptible to calibration drifts. However, these drifts can be accurately assessed using AERONET and BREWER direct sun data. After correcting for these calibration changes, the AAOT was inferred by fitting the measurements of global and diffuse atmospheric transmittances with the forward RT model independently at each spectral channel. The AOT data and ancillary measurements of aerosol column particle size distribution and refractive index in the visible wavelengths (by CIMEL sun-sky almucantar inversions), direct -sun column NO2 and

  10. Different atmospheric parameters influence on spectral UV radiation (measurements and modelling)

    Energy Technology Data Exchange (ETDEWEB)

    Chubarova, N.Y. [Moscow State Univ. (Russian Federation). Meteorological Observatory; Krotkov, N.A. [Maryland Univ., MD (United States). JCESS/Meteorology Dept.; Geogdzhaev, I.V.; Bushnev, S.V.; Kondranin, T.V. [SUMGF/MIPT, Dolgoprudny (Russian Federation); Khattatov, V.U. [Central Aerological Observatory, Dolgoprudny (Russian Federation)

    1995-12-31

    The ultraviolet (UV) radiation plays a vital role in the biophysical processes despite its small portion in the total solar flux. UV radiation is subject to large variations at the Earth surface depending greatly on solar elevation, ozone and cloud amount, aerosols and surface albedo. The analysis of atmospheric parameters influence is based on the spectral archive data of three spectral instruments: NSF spectroradiometer (Barrow network) (NSF Polar Programs UV Spectroradiometer Network 1991-1992,1992), spectrophotometer (SUVS-M) of Central Aerological Observatory CAO, spectroradiometer of Meteorological Observatory of the Moscow State University (MO MSU) and model simulations based on delta-Eddington approximation

  11. 基于光谱分解的Clementine UV/VIS/NIR数据月表矿物填图%MINERAL MAPPING OF THE LUNAR SURFACE USING CLEMENTINE UV/VIS/NIR DATA BASED ON UNMIXING OF SPECTRAL

    Institute of Scientific and Technical Information of China (English)

    闫柏琨; 甘甫平; 王润生; 王振超; 杨苏明

    2009-01-01

    月表主要矿物的空间分布是研究月球起源演化等科学问题的重要基础信息之一.基于Hapke模型与光谱线性分解的矿物提取方法,利用Clementine UV/VIS/NIR数据提取月表单斜辉石、斜方辉石、橄榄石、斜长石及钛铁矿等5类主要矿物的体积百分含量分布,并基于阿波罗(Apollo)月岩(壤)矿物分析数据对提取结果进行评价,对方法和提取结果中存在的问题进行分析,提出了进一步改进的措施.%The distribution of mineral abundances on lunar surface is one of the basic kinds of information which contains important data such as the origin and evolution of the moon. In this paper, the distribution of clinopyroxene, orthopyroxene, olivine, plagioclase and ilmenite on lunar surface was mapped based on Hapke radioactive transfer model and linear unmixing of spectra using Clementine UV/VIS/NIR data. The result is compared with the results obtained by previous researchers and Apollo sample analysis, and the problems existing in mineral abundance mapping are analyzed preliminarily.

  12. Test and analysis of spectral response for UV image intensifier

    Science.gov (United States)

    Qian, Yunsheng; Liu, Jian; Feng, Cheng; Lv, Yang; Zhang, Yijun

    2015-10-01

    The UV image intensifier is one kind of electric vacuum imaging device based on principle of photoelectronic imaging. To achieve solar-blind detection, its spectral response characteristic is extremely desirable. A broad spectrum response measurement system is developed. This instrument uses EQ-99 laser-driven light source to get broad spectrum in the range of 200 nm to 1700 nm. A special preamplifier as well as a test software is work out. The spectral response of the image intensifier can be tested in the range of 200~1700 nm. Using this spectrum response measuring instrument, the UV image intensifiers are tested. The spectral response at the spectral range of 200 nm to 600 nm are obtained. Because of the quantum efficiency of Te-Cs photocathode used in image intens ifier above 280nm wavelength still exists, especially at 280 nm to 320nm.Therefore, high-performance UV filters is required for solar blind UV detection. Based on two sets of UV filters, the influence of solar radiation on solar blind detection is calculated and analyzed.

  13. 25 years of spectral UV measurements at Sodankylä

    Science.gov (United States)

    Lakkala, Kaisa; Heikkilä, Anu; Kärhä, Petri; Ialongo, Iolanda; Karppinen, Tomi; Karhu, Juha Matti; Lindfors, Anders Vilhelm; Meinander, Outi

    2017-02-01

    At Sodankylä (67°N), spectra of solar ultraviolet radiation (UVR) have been measured with a Brewer spectroradiometer since 1990. The time series is one of the longest in the European Arctic region. In this work, the time series 1990-2014 was homogenized, and the data were corrected with respect to known error sources using laboratory characterizations and theoretical approaches. Methods for cosine correction, temperature correction and determination of long-term changes in spectral responsivity were applied. Bad measurements were identified by using various quality assurance tools including comparisons with reconstructed UV dose rates, synchronous broadband UV dose rates, global radiation and clear sky model calculations. We calculated daily maximum UV indices from the spectral time series. The daily maxima reached on average a value of 5 in midsummer, whereas the maximum UV index value of 6 was measured only twice: in 2011 and in 2013. We calculated the relative spectral changes in measured UV irradiances. An anti-correlation with total ozone was found in April and June, but no statistically significant long-term changes were found. The effect of snow, enhancing the measured UVR due to high albedo, was important during late spring. Short-term variations were mostly due to changes in cloudiness, which was the dominant factor during summertime.

  14. New observation strategies for the solar UV spectral irradiance

    Directory of Open Access Journals (Sweden)

    Kretzschmar Matthieu

    2012-09-01

    Full Text Available Many applications in space weather and in space situational awareness require continuous solar spectral irradiance measurements in the UV, and to a lesser degree in the visible band. Most space-borne solar radiometers are made out of two different parts: (i a front filter that selects the passband and (ii a detector that is usually based on silicon technology. Both are prone to degradation, which may be caused either by the degradation of the filter coating due to local deposition or to structural changes, or by the degradation of the silicon detector by solar radiative and energetic particle fluxes. In this study, we provide a theoretical analysis of the filter degradation that is caused by structural changes such as pinholes; contamination-induced degradation will not be considered. We then propose a new instrumental concept, which is expected to overcome, at least partially, these problems. We show how most of the solar UV spectrum can be reconstructed from the measurement of only five spectral bands. This instrumental concept outperforms present spectrometers in terms of degradation. This new concept in addition overcomes the need for silicon-based detectors, which are replaced by wide band gap material detectors. Front filters, which can contribute to in-flight degradation, therefore are not required, except for the extreme-UV (EUV range. With a small weight and a low telemetry, this concept may also have applications in solar physics, in astrophysics and in planetology.

  15. UV/Ozone Cleaning of Surfaces

    Science.gov (United States)

    1986-05-01

    clean surfaces under UV radiation maintained the surface cleanliness indefinitely. Duting the period 1974-1976, Vig et al.( 3 - 5 ) described a series of...probably no other device of which the performance is so critically dependent upon surface cleanliness . For example, the aging requirement for one 5 MHz...such a device changes the frequency by about one part in 106. The surface cleanliness must therefore be such that the rate of contamination transfer

  16. Insulator Surface Flashover Due to UV Illumination

    Energy Technology Data Exchange (ETDEWEB)

    Javedani, J B; Houck, T L; Lahowe, D A; Vogtlin, G E; Goerz, D A

    2009-07-27

    The surface of an insulator under vacuum and under electrical charge will flashover when illuminated by a critical dose of ultra-violet (UV) radiation - depending on the insulator size and material, insulator cone angle, the applied voltage and insulator shot-history. A testbed comprised of an excimer laser (KrF, 248 nm, {approx}16 MW, 30 ns FWHM,), a vacuum chamber, and a negative polarity dc high voltage power supply ({le} -60 kV) were assembled to test 1.0 cm thick angled insulators for surface-flashover. Several candidate insulator materials, e.g. High Density Polyethylene (HDPE), Rexolite{reg_sign} 1400, Macor{trademark} and Mycalex, of varying cone angles were tested against UV illumination. Commercial energy meters were used to measure the UV fluence of the pulsed laser beam. In-house designed and fabricated capacitive probes (D-dots, >12 GHz bandwidth) were embedded in the anode electrode underneath the insulator to determine the time of UV arrival and time of flashover. Of the tested insulators, the +45 degree Rexolite insulator showed more resistance to UV for surface flashover; at UV fluence level of less than 13 mJ/cm{sup 2}, it was not possible to induce a flashover for up to -60 kV of DC potential across the insulator's surface. The probes also permitted the electrical charge on the insulator before and after flashover to be inferred. Photon to electron conversion efficiency for the surface of Rexolite insulator was determined from charge-balance equation. In order to understand the physical mechanism leading to flashover, we further experimented with the +45 degree Rexolite insulator by masking portions of the UV beam to illuminate only a section of the insulator surface; (1) the half nearest the cathode and subsequently, (2) the half nearest the anode. The critical UV fluence and time to flashover were measured and the results in each case were then compared with the base case of full-beam illumination. It was discovered that the time for the

  17. First Spectral Coverage of two regions on Ceres in the far-UV

    Science.gov (United States)

    Hendrix, Amanda R.; Vilas, Faith; Li, Jian-Yang

    2015-11-01

    We present the first spectral observations of Ceres in the far-ultraviolet, along with new measurements in the near-UV and visible, as measured by HST/STIS as part of Cycle 22, in August-September, 2015. The observations are motivated by early broad-band UV observations [1][2][3] suggesting a UV absorption centered near 260 nm along with a very strong increase in UV reflectance into the far-UV (~160 nm). We have observed two central longitudes of Ceres - near 0°W and 120°W (this latter area one of the regions in which Herschel detected water vapor) - using the G140L (~120-172 nm), G230L (~170-310 nm) and G430L (~300-570 nm) detectors. We use the data to test a prediction of graphitized carbon on the surface, and we look for signatures of water ice and/or water vapor.[1] Parker, J. W., S. A. Stern, P. C. Thomas, M. C. Festou, W. J. Merline, E. F. Young, R. P Binzel, L. A. Lebofsky (2002). Astron J. 123, 549[2] Li et al. (2006). Icarus 182: 143-160.[3] Rivkin, A. S., J.-Y. Li, R. E. Milliken, L. F. Lim, A. J. Lovell, B. E. Schmidt, L. A. McFadden, B. A. Cohen (2011). Space Sci Rev 163, 95.

  18. Exact Spectral Dimension of the Random Surface

    CERN Document Server

    Goncharenko, Igor

    2009-01-01

    We propose a new method of the analytical computation of the spectral dimension which is based on the equivalence of the random walk and the q-state Potts model with non-zero magnetic field in the limit $q\\to 0$. Calculating the critical exponent of the magnetization of this model on the dynamically triangulated random surface by means of a matrix model technique we obtain that the spectral dimension of this surface is equal to two.

  19. Transmittance, Reflectance, and Emission Spectroscopy of Meteorites from the UV to the IR Spectral Range

    Science.gov (United States)

    Maturilli, A.; Helbert, J.; Koulen, J. M.; Ferrari, S.; Martellato, E.

    2016-08-01

    Transmittance, reflectance, and emissivity Spectra of six meteorites have been collected at the Planetary Spectroscopy Laboratory (PSL) of DLR in Berlin in the whole spectral range from the UV to the IR.

  20. Spectral irradiance measurement and actinic radiometer calibration for UV water disinfection

    Science.gov (United States)

    Sperfeld, Peter; Barton, Bettina; Pape, Sven; Towara, Anna-Lena; Eggers, Jutta; Hopfenmüller, Gabriel

    2014-12-01

    In a joint project, sglux and PTB investigated and developed methods and equipment to measure the spectral and weighted irradiance of high-efficiency UV-C emitters used in water disinfection plants. A calibration facility was set up to calibrate the microbicidal irradiance responsivity of actinic radiometers with respect to the weighted spectral irradiance of specially selected low-pressure mercury and medium-pressure mercury UV lamps. To verify the calibration method and to perform on-site tests, spectral measurements were carried out directly at water disinfection plants in operation. The weighted microbicidal irradiance of the plants was calculated and compared to the measurements of various actinic radiometers.

  1. Data flow of spectral UV measurements at Sodankylä and Jokioinen

    Science.gov (United States)

    Sakari Mäkelä, Jakke; Lakkala, Kaisa; Koskela, Tapani; Karppinen, Tomi; Matti Karhu, Juha; Savastiouk, Vladimir; Suokanerva, Hanne; Kaurola, Jussi; Arola, Antti; Vilhelm Lindfors, Anders; Meinander, Outi; de Leeuw, Gerrit; Heikkilä, Anu

    2016-06-01

    The data flow involved in a long-term continuous solar spectral UV irradiance monitoring program is investigated and structured to provide an overall view on the multiphase process from data acquisition to the final products. The program employing Brewer spectrophotometers as measuring instruments is maintained by the Finnish Meteorological Institute (FMI) ever since the 1990s at two sites in Finland: Sodankylä (67° N) and Jokioinen (61° N). It is built upon rigorous operation routines, processing procedures, and tools for quality control (QC) and quality analysis (QA) under continuous development and evaluation. Three distinct levels of data emerge, each after certain phase in the data flow: Level 0 denoting raw data, Level 1 meaning calibrated data processed in near-real time, and Level 2 comprising of postprocessed data corrected for all distinguishable errors and known inaccuracies. The final products disseminated to the users are demonstrated to result from a process with a multitude of separate steps, each required in the production of high-quality data on solar UV radiation at the Earth's surface.

  2. Spectral emissivity of surface blackbody calibrators

    DEFF Research Database (Denmark)

    Clausen, Sønnik

    2007-01-01

    The normal spectral emissivity of commercial infrared calibrators is compared with measurements of anodized aluminum samples and grooved aluminum surfaces coated with Pyromark. Measurements performed by FTIR spectroscopy in the wavelength interval from 2 to 20 mu m and at temperatures between 5...... in emissivity using similar materials can be reduced to 0.5-1% by optimizing the coating process and the surface geometry. Results are discussed and an equation for calculation of the equivalent blackbody surface temperature from FTIR spectra is presented, including reflected ambient radiation. It is in most...... cases necessary to correct temperature calibration results for calibrators calibrated at 8-14 mu m to obtain absolute accuracies of 0.1-1 degrees C in other spectral regions depending on the temperature. Uncertainties are discussed and equations are given for the correction of measured radiation...

  3. 25 years of solar spectral UV measurements at 45° S

    Science.gov (United States)

    Liley, Ben; McKenzie, Richard; Johnston, Paul; Kotkamp, Michael

    2017-02-01

    We review 25 years of solar spectral UV at Lauder, measured to the exacting standards of the Network for the Detection of Atmospheric Composition Change (NDACC) with the best systems available at the time. Recent reanalysis of the alignment, calibration, and data processing from all nine of the UV spectroradiometers used at Lauder and other NDACC sites has better characterised the effects of changes in instrument technology. There has been no detectable trend in solar UV radiation other than that resulting from ozone variation.

  4. Laser Meter of Atmospheric Inhomogeneity Properties in UV Spectral Range

    Directory of Open Access Journals (Sweden)

    S. E. Ivanov

    2015-01-01

    Full Text Available Development of laser systems designed to operate in conditions of the terrestrial atmosphere demands reliable information about the atmosphere condition. The aerosol lidars for operational monitoring of the atmosphere allow us to define remotely characteristics of atmospheric aerosol and cloudy formations in the atmosphere.Today the majority of aerosol lidars run in the visible range. However, in terms of safety (first of all to eyes also ultra-violet (UF range is of interest. A range of the wavelengths of the harmful effect on the eye retina is from 0.38 to 1.4 mμ. Laser radiation with the wavelengths less than 0.38 mμ and over 1.4 mμ influences the anterior ambient of an eye and is safer, than laser radiation with the wavelengths of 0.38 – 1.4 mμ.The paper describes a laser meter to measure characteristics of atmospheric inhomogeneity propertis in UF spectral range at the wavelength of 0.355 mμ.As a radiation source, the meter uses a semiconductor-pumped pulse solid-state Nd:YAG laser. As a receiving lens, Kassegren's scheme-implemented mirror lens with a socket to connect optical fibre is used in the laser meter. Radiation from the receiving lens is transported through the optical fibre to the optical block. The optical block provides spectral selection of useful signal and conversion of optical radiation into electric signal.To ensure a possibility for alignment of the optical axes of receiving lens and laser radiator the lens is set on the alignment platform that enables changing lens inclination and turn with respect to the laser.The software of the laser meter model is developed in the NI LabVIEW 2012 graphic programming environment.The paper gives the following examples: a typical laser echo signal, which is back scattered by the atmosphere and spatiotemporal distribution of variation coefficient of the volumetric factor of the back scattered atmosphere. Results of multi-day measurements show that an extent of the recorded aerosol

  5. The UV Surface Environment on Young Planets: Implications for Prebiotic Chemistry & Life on Other Worlds

    Science.gov (United States)

    Ranjan, Sukrit; Simons Collaboration on the Origin of Life, Harvard Origins of Life Initiative

    2017-01-01

    Understanding the origin of life (abiogenesis) on Earth is key to understanding how it might start elsewhere. Recent laboratory studies suggest UV light may have played a critical role in the synthesis of molecules relevant to abiogenesis (prebiotic chemistry), such as RNA. I show that UV light interacts with prebiotic chemistry in ways that may be sensitive to the spectral shape and overall amplitude of irradiation. I use radiative transfer models to constrain the UV environment on early Earth (3.9 Ga). I find that the surface UV is insensitive to much of the considerable uncertainty in the atmospheric state, enabling me to constrain the UV environment for prebiotic chemistry on early Earth. Some authors have suggested Mars as a venue for prebiotic chemistry. Therefore, I explore plausible UV spectral fluences on Mars at 3.9 Ga. I find that the early Martian UV environment is comparable to Earth’s under conventional assumptions about the atmosphere. However, if the atmosphere was dusty or SO2 levels were high, UV fluence would have been strongly suppressed. Intriguingly, despite overall attenuation of UV fluence, SO2 preferentially attenuates destructive FUV radiation over prebiotically-useful NUV radiation, meaning high-SO2 epochs may have been more clement for the origin of life. Better measurements of the spectral dependence of prebiotic photoprocesses are required to constrain this hypothesis. Finally, I calculate the UV fluence on planets orbiting M-dwarfs. I find that UV irradiation on such planets is low compared to Earth. Laboratory studies are required to understand whether prebiotic photoprocesses that worked on Earth can function on low-UV M-dwarf planets. My work 1) provides initial conditions for laboratory studies of prebiotic chemistry, 2) constrains the inhabitability of Mars and planets orbiting M-dwarfs, and 3) demonstrates the need for laboratory studies to characterize the impact of variations in irradiating intensity and spectral shape on

  6. Tertiary structure and spectral tuning of UV and violet pigments in vertebrates

    Science.gov (United States)

    Yokoyama, Shozo; Starmer, William T.; Takahashi, Yusuke; Tada, Takashi

    2010-01-01

    Many vertebrate species use ultraviolet (UV) vision for such behaviors as mating, foraging, and communication. UV vision is mediated by UV-sensitive visual pigments, which have the wavelengths of maximal absorption (λmax) at ~360 nm, whereas violet (or blue) vision is mediated by orthologous pigments with λmax values of 390–440 nm. It is widely believed that amino acids in transmembrane (TM) I–III are solely responsible for the spectral tuning of these SWS1 pigments. Recent molecular analyses of SWS1 pigments, however, show that amino acids in TM IV–VII are also involved in the spectral tuning of these pigments through synergistic interactions with those in TM I–III. Comparisons of the tertiary structures of UV and violet pigments reveal that the distance between the counterion E113 in TM III and amino acid sites 87–93 in TM II is narrower for UV pigments than for violet pigments, which may restrict the access of water molecules to the Schiff base pocket and deprotonate the Schiff base nitrogen. Both mutagenesis analyses of E113Q and quantum chemical calculations strongly suggest that unprotonated Schiff base-linked chromophore is responsible for detecting UV light. PMID:16343816

  7. UV surface habitability of the TRAPPIST-1 system

    Science.gov (United States)

    O'Malley-James, Jack T.; Kaltenegger, L.

    2017-07-01

    With the discovery of rocky planets in the temperate habitable zone (HZ) of the close-by cool star TRAPPIST-1, the question of whether such planets could harbour life arises. Habitable planets around red dwarf stars can orbit in radiation environments that can be life-sterilizing. Ultraviolet (UV) flares from these stars are more frequent and intense than solar flares. Additionally, their temperate HZs are closer to the star. Here we present UV surface environment models for TRAPPIST-1's HZ planets and explore the implications for life. TRAPPIST-1 has high X-ray/extreme-ultraviolet activity, placing planetary atmospheres at risk from erosion. If a dense Earth-like atmosphere with a protective ozone layer existed on planets in the HZ of TRAPPIST-1, UV surface environments would be similar to the present-day Earth. However, an eroded or an anoxic atmosphere would allow more UV to reach the surface, making surface environments hostile even to highly UV tolerant terrestrial extremophiles. If future observations detect ozone in the atmospheres of any of the planets in the HZ of TRAPPIST-1, these would be interesting targets for the search for surface life. We anticipate our assay to be a starting point for in-depth exploration of stellar and atmospheric observations of the TRAPPIST-1 planets to constrain their UV surface habitability.

  8. Spectral properties and conformal type of surfaces

    Directory of Open Access Journals (Sweden)

    PHILIPPE CASTILLON

    2002-12-01

    Full Text Available In this short note, we announce a result relating the geometry of a riemannian surface to the positivity of some operators on this surface (the operators considered here are of the form surface Laplacian plus a scalar multiple of the curvature function. In particular we obtain a theorem "à la Huber'': under a spectral hypothesis we prove that the surface is conformally equivalent to a Riemann surface with a finite number of points removed. This problem has its origin in the study of stable minimal surfaces.Nesta comunicação, anunciamos um resultado que relaciona a geometria de uma superfície riemanniana com a positividade de certos operadores na superfície (os operadores considerados têm forma "Laplaciano mais um múltiplo da curvatura''. Em particular, obtemos um teorema "à la Huber'': usando uma condição espectral, provamos que a superfície é conformemente equivalente a uma superfície de Riemann menos um número finito de pontos. Este problema tem origem no estudo das superfícies mínimas estáveis.

  9. SURFACE ALBEDO AND SPECTRAL VARIABILITY OF CERES

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jian-Yang; Reddy, Vishnu; Corre, Lucille Le; Sykes, Mark V.; Prettyman, Thomas H. [Planetary Science Institute, 1700 E. Ft. Lowell Road, Suite 106, Tucson, AZ 85719 (United States); Nathues, Andreas; Hoffmann, Martin; Schaefer, Michael [Max Planck Institute for Solar System Research, Göttingen (Germany); Izawa, Matthew R. M.; Cloutis, Edward A. [University of Winnipeg, Winnipeg, Manitoba (Canada); Carsenty, Uri; Jaumann, Ralf; Krohn, Katrin; Mottola, Stefano; Schröder, Stefan E. [German Aerospace Center (DLR), Institute of Planetary Research, Berlin (Germany); Castillo-Rogez, Julie C. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Schenk, Paul [Lunar and Planetary Institute, Houston, TX 77058 (United States); Williams, David A. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Smith, David E. [Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Zuber, Maria T. [Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); and others

    2016-02-01

    Previous observations suggested that Ceres has active, but possibly sporadic, water outgassing as well as possibly varying spectral characteristics over a timescale of months. We used all available data of Ceres collected in the past three decades from the ground and the Hubble Space Telescope, as well as the newly acquired images by the Dawn  Framing Camera, to search for spectral and albedo variability on Ceres, on both a global scale and in local regions, particularly the bright spots inside the Occator crater, over timescales of a few months to decades. Our analysis has placed an upper limit on the possible temporal albedo variation on Ceres. Sporadic water vapor venting, or any possibly ongoing activity on Ceres, is not significant enough to change the albedo or the area of the bright features in the Occator crater by >15%, or the global albedo by >3% over the various timescales that we searched. Recently reported spectral slope variations can be explained by changing Sun–Ceres–Earth geometry. The active area on Ceres is less than 1 km{sup 2}, too small to cause global albedo and spectral variations detectable in our data. Impact ejecta due to impacting projectiles of tens of meters in size like those known to cause observable changes to the surface albedo on Asteroid Scheila cannot cause detectable albedo change on Ceres due to its relatively large size and strong gravity. The water vapor activity on Ceres is independent of Ceres’ heliocentric distance, ruling out the possibility of the comet-like sublimation process as a possible mechanism driving the activity.

  10. [Relationship between surface UV radiation and air pollution in Beijing].

    Science.gov (United States)

    An, Jun-lin; Wang, Yue-si; Li, Xin; Sun, Yang; Shen, Shuang-he

    2008-04-01

    Based on the data of solar radiation and air pollutants collected in Beijing, the relationship between surface ultraviolet (UV) radiation and the content of air pollutants were analyzed, using the radiative transfer model TUV4.4 (Tropospheric Ultraviolet Visible). The results show that average total ozone content is 329 DU and higher in winter and spring, lower in summer and autumn. The inverse relationship exists between ground level UV radiation and total ozone content. This study also shows that a substantial reduction (up to 50%) in the UV radiation on days with high levels of air pollution. Larger fluctuations are found in UV radiation in the summer. The effects of clouds and air pollution on UV are higher than on total solar radiation, and the reduction in UV is about twice as large as the total solar radiation values. Strong reduction in the UV radiation reaching the ground is associated with the increase of tropospheric ozone and nitrogen oxides in Beijing. The correlation coefficient between ozone concentration and decrease in UV radiation is 0.70 in the early afternoon.

  11. Hyperspectral Surface Analysis for Ripeness Estimation and Quick UV-C Surface Treatments for Preservation of Bananas

    Science.gov (United States)

    Zhao, W.; Yang, Zh.; Chen, Zh.; Liu, J.; Wang, W. Ch.; Zheng, W. Yu.

    2016-05-01

    This study aimed to determine the ripeness of bananas using hyperspectral surface analysis and how a rapid UV-C (ultraviolet-C light) surface treatment could reduce decay. The surface of the banana fruit and its stages of maturity were studied using a hyperspectral imaging technique in the visible and near infrared (370-1000 nm) regions. The vselected color ratios from these spectral images were used for classifying the whole banana into immature, ripe, half-ripe and overripe stages. By using a BP neural network, models based on the wavelengths were developed to predict quality attributes. The mean discrimination rate was 98.17%. The surface of the fresh bananas was treated with UV-C at dosages from 15-55 μW/cm2. The visual qualities with or without UV-C treatment were compared using the image, the chromatic aberration test, the firmness test and the area of black spot on the banana skin. The results showed that high dosages of UV-C damaged the banana skin, while low dosages were more efficient at delaying changes in the relative brightness of the skin. The maximum UV-C treatment dose for satisfactory banana preservation was between 21 and 24 μW/cm2. These results could help to improve the visual quality of bananas and to classify their ripeness more easily.

  12. Reflectance Spectral Characteristics of Lunar Surface Materials

    Institute of Scientific and Technical Information of China (English)

    Yong-Liao Zou; Jian-Zhong Liu; Jian-Jun Liu; Tao Xu

    2004-01-01

    Based on a comprehensive analysis of the mineral composition of major lunar rocks (highland anorthosite, lunar mare basalt and KREEP rock), we investigate the reflectance spectral characteristics of the lunar rock-forming minerals, including feldspar, pyroxene and olivine. The affecting factors, the variation of the intensity of solar radiation with wavelength and the reflectance spectra of the lunar rocks are studied. We also calculate the reflectivity of lunar mare basalt and highland anorthosite at 300 nm, 415 nm, 750 nm, 900 nm, 950 nm and 1000 nm.It is considered that the difference in composition between lunar mare basalt and highland anorthosite is so large that separate analyses are needed in the study of the reflectivity of lunar surface materials in the two regions covered by mare basalt and highland anorthosite, and especially in the region with high Th contents, which may be the KREEP-distributed region.

  13. The UV to FIR spectral energy distribution of star-forming galaxies in the redshift desert

    CERN Document Server

    Oteo, I; Magdis, G; Pérez-García, A M; Cepa, J; Cedrés, B; Sánchez, H Domínguez; Ederoclite, A; Sánchez-Portal, M; Pérez-Martínez, R; Pintos-Castro, I; Polednikova, J

    2013-01-01

    We analyze the rest-frame UV-to-near-IR spectral energy distribution (SED) of Lyman break galaxies (LBGs), star-forming (SF) BzK (sBzK), and UV-selected galaxies at 1.5 < z < 2.5 in the COSMOS, GOODS-North, and GOODS-South fields. Additionally, we complement the multi-wavelength coverage of the galaxies located in GOODS-North and GOODS-South fields with deep FIR data taken within the framework of the GOODS-Herschel project. According to their best-fitted SED-derived properties we find that, due to their selection criterion involving UV measurements, LBGs tend to be UV-brighter, bluer, have less prominent Balmer break (are younger), and have higher dust-corrected total SFR than sBzK galaxies. In a color versus stellar mass diagram, LBGs at z ~ 2 tend to be mostly located over the blue cloud of galaxies at their redshift, although galaxies with older ages, higher dust attenuation, and redder UV continuum slope deviate to the green valley and red sequence. We find PACS (100um or 160um) individual detection...

  14. On the correspondence between surface UV observations and TOMS determinations of surface UV: a potential method for quality evaluating world surface UV observations

    Directory of Open Access Journals (Sweden)

    C. Cornwall

    2003-06-01

    Full Text Available A comparison of erythemally weighted surface UV irradiance observations with similar NASA TOMS surface UV determinations is described. Comparisons are made for two observation periods: the Robertson-Berger (R-B meter period from 1974 to the late 1980s and the current period from 1996 to the present when more sophisticated UVB-1 instruments were used. The more primitive R-B meter observations that comprised the fi rst U.S. UV network are seen to drift downward with respect to those of the TOMS. While the UVB-1 observations did not appear to drift, a substantial bias is noted to exist between the TOMS and the UVB-1 stations collecting observations; the TOMS estimations tend to be higher. A portion of the bias may be attributed to errors in calibration, total ozone, and cosine response of the surface instrumentation. Unaccounted aerosol effects, although not considered to be large in the TOMS estimations, present another source of error. Comparisons are fi rst done for all sky conditions and then for clear sky conditions. The biases typically agree for all sky conditions within the uncertainties of the surface instruments' calibrations, liberally defi ned as ± 5%, implying that the TOMS cloud correction scheme performs reasonably well. Snow cover severely impacts the TOMS observations, giving considerably higher estimations. The biases for clear sky conditions ranged from 15% to 19% with no obvious drifts between the satellite and surface observations. The variation in the biases among stations is within the calibration uncertainties of the instruments, but the absolute bias is unexpectedly large. The standard deviations of the clear sky comparisons among all stations are steady at 4.8% ± 0.7%. A plot of the TOMS/UVB-1 ratio versus TOMS cloud refl ectivity observations is noisy, but qualitatively suggestive of a possible slight increase (~ 5% or greater over the range of clear to overcast skies. The results from these comparisons

  15. Spectral modeling for the Chelyabinsk meteorite at UV-Vis-NIR wavelengths

    Science.gov (United States)

    Martikainen, Julia; Penttilä, Antti; Kohout, Tomas; Suhonen, Heikki; Huotari, Simo; Muinonen, Karri

    2016-10-01

    Asteroids provide us information on the evolution of the Solar System. Meteorites and asteroids can be linked by matching their respective reflectance spectra. However, this is difficult because the spectral features depend strongly on the surface properties. To better interpret the spectra, we need to gain more knowledge of the light-scattering physics involved.We develop a new light-scattering code based on SIRIS-code (Muinonen et al., JQSRT 110, 2009), which simulates light scattering by Gaussian-random-sphere particles that are large compared to the wavelength of the incident light. SIRIS is able to simulate ray optics, diffraction, and geometric ray optics, which utilizes ray optics that accounts for diffuse scattering. The diffuse scatterers can be uniformly distributed inside or cover the surface of the particle. The new code uses inhomogeneous waves to simulate light scattering by absorbing particles.The University of Helsinki integrating-sphere spectrometer has been utilized to measure the reflectance spectra of three lithologies of the Chelyabinsk meteorite (light-colored, dark-colored, and impact-melt) at UV-Vis-NIR wavelengths (0.25-3.2 microns). Microtomography images of the light-colored and the dark-colored lithologies have also been taken. The light-colored lithology has the highest reflectance and shows broad absorption bands of olivine and pyroxene near 1.0 and 2.0 microns. The dark-colored lithology has a flat spectrum with diminished intensity. The impact-melt lithology is somewhere between the light-colored and dark-colored lithologies in terms of its spectrum (Kohout et al., Icarus 228, 2013). The differences in the spectra are caused by different patterns of iron and iron sulfides in the samples that can be seen in the microtomography and scanning electron microscope images. We utilize the new light-scattering code to model the effects of iron and iron sulfides in the spectra of the three lithologies of the Chelyabinsk meteorite by entering

  16. Spectral Radiative Properties of Two-Dimensional Rough Surfaces

    Science.gov (United States)

    Xuan, Yimin; Han, Yuge; Zhou, Yue

    2012-12-01

    Spectral radiative properties of two-dimensional rough surfaces are important for both academic research and practical applications. Besides material properties, surface structures have impact on the spectral radiative properties of rough surfaces. Based on the finite difference time domain algorithm, this paper studies the spectral energy propagation process on a two-dimensional rough surface and analyzes the effect of different factors such as the surface structure, angle, and polarization state of the incident wave on the spectral radiative properties of the two-dimensional rough surface. To quantitatively investigate the spatial distribution of energy reflected from the rough surface, the concept of the bidirectional reflectance distribution function is introduced. Correlation analysis between the reflectance and different impact factors is conducted to evaluate the influence degree. Comparison between the theoretical and experimental data is given to elucidate the accuracy of the computational code. This study is beneficial to optimizing the surface structures of optoelectronic devices such as solar cells.

  17. Galileo's Multiinstrument Spectral View of Europa's Surface Composition

    Science.gov (United States)

    Fanale, F.P.; Granahan, J.C.; McCord, T.B.; Hansen, G.; Hibbitts, C.A.; Carlson, R.; Matson, D.; Ocampo, A.; Kamp, L.; Smythe, W.; Leader, F.; Mehlman, R.; Greeley, R.; Sullivan, R.; Geissler, P.; Barth, C.; Hendrix, A.; Clark, B.; Helfenstein, P.; Veverka, J.; Belton, M.J.S.; Becker, K.; Becker, T.

    1999-01-01

    We have combined spectral reflectance data from the Solid State Imaging (SSI) experiment, the Near-Infrared Mapping Spectrometer (NIMS), and the Ultraviolet Spectrometer (UVS) in an attempt to determine the composition and implied genesis of non-H2O components in the optical surface of Europa. We have considered four terrains: (1) the "dark terrains" on the trailing hemisphere, (2) the "mottled terrain," (3) the linea on the leading hemisphere, and (4) the linea embedded in the dark terrain on the trailing hemisphere. The darker materials in these terrains exhibit remarkably similar spectra in both the visible and near infrared. In the visible, a downturn toward shorter wavelengths has been attributed to sulfur. The broad concentrations of dark material on the trailing hemisphere was originally thought to be indicative of exogenic sulfur implantation. While an exogenic cause is still probable, more recent observations by the UVS team at higher spatial resolution have led to their suggestions that the role of the bombardment may have primarily been to sputter away overlying ice and to reveal underlying endogenic non-H2O contaminants. If so, this might explain why the spectra in all these terrains are so similar despite the fact that the contaminants in the linea are clearly endogenic and those in the mottled terrain are almost certainly so. In the near infrared, all these terrains exhibit much more asymmetrical bands at 1.4 and 2.0 ??m at shorter wavelengths than spectra from elsewhere on Europa. It has been argued that this is because the water molecules are bound in hydrated salts. However, this interpretation has been challenged and it has also been argued that pure coarse ice can exhibit such asymmetric bands under certain conditions. The nature of this controversy is briefly discussed, as are theoretical and experimental studies bearing on this problem. ?? 1999 Academic Press.

  18. Measurements and estimation of the columnar optical depth of tropospheric aerosols in the UV spectral region

    Directory of Open Access Journals (Sweden)

    V. E. Cachorro

    Full Text Available We report values of the columnar tropospheric aerosol optical depth at UV wavelengths based on experimental measurements of the direct spectral irradiances carried out by a commercial spectroradiometer (Li1800 of Licor company covering the range from 300–1100 nm at two stations with different climate characteristics in Spain. The first station is located in a rural site in north central Spain with continental climate. The data extend from March to the end of October of 1995. The other station is a coastal site in the Gulf of Cádiz (southwest Spain of maritime climate type. This study is mainly focused on the capability of estimating aerosol optical depth values in the UV region based on the extracted information in the visible and near infrared ranges. A first method has been used based on the Ångström turbidity parameters. However, since this method requires detailed spectral information, a second method has also been used, based on the correlation between wavelengths. A correlation has been established between the experimental aerosol optical depth values at 350 nm and 500 nm wavelengths. Although the type of aerosol seems to be the key factor that determines the quality of these estimations, the evaluation of the associated error is necessary to know the behaviour of these estimations in each area of study.

    Key words. Atmospheric composition and structure (aerosols and particles; transmission and scattering of radiation; troposphere – composition and chemistry

  19. Measurements and estimation of the columnar optical depth of tropospheric aerosols in the UV spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Cachorro, V.E.; Vergaz, R.; Martin, M.J.; Frutos, A.M. de [Grupo de Optica Atmosferica, Univ. de Valladolid (GOA-UVA), Valladolid (Spain); Vilaplana, J.M.; Morena, B. de la [Estacion de Sondeos Atmosfericos ESAT ' ' El Arenosillo' ' , INTA, Huelva (Spain)

    2002-04-01

    We report values of the columnar tropospheric aerosol optical depth at UV wavelengths based on experimental measurements of the direct spectral irradiances carried out by a commercial spectroradiometer (Li1800 of Licor company) covering the range from 300-1100 nm at two stations with different climate characteristics in Spain. The first station is located in a rural site in north central Spain with continental climate. The data extend from March to the end of October of 1995. The other station is a coastal site in the Gulf of Cadiz (southwest Spain) of maritime climate type. This study is mainly focused on the capability of estimating aerosol optical depth values in the UV region based on the extracted information in the visible and near infrared ranges. A first method has been used based on the Aangstroem turbidity parameters. However, since this method requires detailed spectral information, a second method has also been used, based on the correlation between wavelengths. A correlation has been established between the experimental aerosol optical depth values at 350 nm and 500 nm wavelengths. Although the type of aerosol seems to be the key factor that determines the quality of these estimations, the evaluation of the associated error is necessary to know the behavior of these estimations in each area of study. (orig.)

  20. Photochemical surface modification of PET by excimer UV lamp irradiation

    Science.gov (United States)

    Gao, S. L.; Häßler, R.; Mäder, E.; Bahners, T.; Opwis, K.; Schollmeyer, E.

    2005-09-01

    UV irradiation has interesting potential for the photochemical modification of polymers. In order to study cross-linking effects and/or thin-layer deposition following a treatment in the presence of bi-functional media or in inert atmosphere, irradiation of PET in various atmospheres was performed using a KrCl excimer lamp. Surface properties were investigated by atomic force microscopy, nanoindentation, micro-thermal analysis, and X-ray photo-electron spectroscopy. The studies reveal that surface chemical composition, morphology, adhesion, thermomechanics, and stiffness/modulus are strongly affected by UV irradiation in the presence of bi-functional media. Films treated in octadiene and argon show an increase of surface modulus, much less expansion, and lower soft/melt temperatures, which is an indication of the surface cross-linking effect and a decrease of crystallinity within the near-surface layer. In the case of a diallylphthalate-treated film, depending on the local structure, either a strong decrease of melting temperature or no melting point is found, which is attributed to the irregular cross linking and thickness of the modified layer associated with a decrease of surface modulus. A significant increase of the alkali resistance is found after irradiation, as a result of both wetting and cross-linking effects on the polymer surface.

  1. AGN spectral states from simultaneous UV and X-ray observations by XMM-Newton

    Science.gov (United States)

    Svoboda, Jiri; Guainazzi, Matteo; Merloni, Andrea

    2017-08-01

    It is generally believed that the supermassive black holes in active galactic nuclei (AGN) and stellar-mass black holes in X-ray binaries (XRB) work in a similar way. Koerding et al. (2006) suggested that different types of AGN correspond to different spectral states of XRB. In our recent work, we extended their analysis by using data of higher quality - we used the whole XMM-Newton archive to extract a sample of about 1500 sources with high-quality simultaneous UV and X-ray measurements of AGN. The thermal disc component is estimated from the UV flux while the non-thermal flux is constrained from the measured 2-10 keV X-ray luminosity. Our results indicate that sources with the higher fraction of the X-ray flux tend to be radio-loud, have flatter X-ray spectra and UV spectrum inconsistent with the thermal accretion disc emission, as expected from the XRB hard state analogy, and vice versa for the soft states. Our study, therefore, provides an observational support to the hypothesis that accretion onto super-massive black hole work in a similar way as for the stellar-mass black holes in X-ray binaries, and that XRB and AGN follow similar evolutionary paths. This suggests that the AGN radio dichotomy of radio-loud and radio-quiet sources can be explained by the evolution of the accretion states.

  2. A portable UV-fluorescence multispectral imaging system for the analysis of painted surfaces.

    Science.gov (United States)

    Comelli, Daniela; Valentini, Gianluca; Nevin, Austin; Farina, Andrea; Toniolo, Lucia; Cubeddu, Rinaldo

    2008-08-01

    A portable fluorescence multispectral imaging system was developed and has been used for the analysis of artistic surfaces. The imaging apparatus exploits two UV lamps for fluorescence excitation and a liquid crystal tunable filter coupled to a low-noise charge coupled device as the image detector. The main features of the system are critically presented, outlining the assets, drawbacks, and practical considerations of portability. A multivariate statistical treatment of spectral data is further considered. Finally, the in situ analysis with the new apparatus of recently restored Renaissance wall paintings is presented.

  3. Galaxy Modelling; 1, Spectral Energy Distributions from Far-UV to Sub-mm Wavelengths

    CERN Document Server

    Devriendt, J E G; Sadat, R

    1999-01-01

    (abridged) We present STARDUST, a new self-consistent modelling of the spectral energy distributions (SEDs) of galaxies from far-UV to radio wavelengths. In order to derive the SEDs in this broad spectral range, we first couple spectrophotometric and (closed-box) chemical evolutions to account for metallicity effects on the spectra of synthetic stellar populations. We then use a phenomenological fit for the metal-dependent extinction curve and a simple geometric distribution of the dust to compute the optical depth of galaxies and the corresponding obscuration curve. This enables us to calculate the fraction of stellar light reprocessed in the infrared range. In a final step, we define a dust model with various components and we fix the weights of these components in order to reproduce the IRAS correlation of IR colours with total IR luminosities. This allows us to compute far-IR SEDs that phenomenologically mimic observed trends. We are able to predict the spectral evolution of galaxies in a broad wavelength...

  4. Spectral behavior of AM Her and QQ Vul in high and intermediate states in the UV

    Science.gov (United States)

    Sanad, M. R.

    2010-12-01

    We present low resolution UV spectra of two polar systems, AM Her and QQ Vul from the observations taken by the IUE (International Ultraviolet Explorer) of the period between 1978-1996 and 1983-1996 for both systems respectively, to accomplish a large scale study of what happens to the ultraviolet flux of C IV 1550 Å spectral line during different orbital phases. Two spectra for both systems showing the variations in line fluxes and line widths at different orbital phases in high and intermediate states are presented. We concentrated on calculating the line fluxes and line widths of C IV 1550 Å emission line originating in the accretion stream. Our results show that there is spectral variability for the aformentioned physical parameters at different times, similar to that known for the light curve (Heise and Verbunt, Astron. Astrophys. 189:112, 1988; Gansicke et al., Astron. Astrophys. 303:127, 1995; Kafka and Honeycutt, Astron. J. 125:2188K, 2003). We attribute it to the variations of both density and temperature as a result of changing the mass transfer rate (Hutchings et al., Astron. J. 123:2841H, 2002; King and Lasota, Astron. Astrophys. 140L:16K, 1984) which is responsible for this spectral variability. Also we found that the line fluxes of AM Her are greater than the line fluxes of QQ Vul, while the line widths of both systems are approximately the same.

  5. Spectral Signatures of Surface Materials in Pig Buildings

    DEFF Research Database (Denmark)

    Zhang, GuoQiang; Strøm, Jan; Blanke, Mogens

    2006-01-01

    and after high-pressure water cleaning. The spectral signatures of the surface materials and dirt attached to the surfaces showed that it is possible to make discrimination and hence to classify areas that are visually clean. When spectral bands 450, 600, 700 and 800 nm are chosen, there are at least two...... the cleaning process and to minimise the amount of water and electricity consumed. This research is aimed at utilising a spectral imaging method for cleanliness detection. Consequently, information on the reflectance of building materials and contamination in different spectral ranges is important...... in the investigation. Reflectance data were sampled under controlled lighting conditions using a spectrometer communicating with a portable computer. The measurements were performed in a laboratory with materials used in a pig house for 4-5 weeks. The spectral data were collected for the surfaces before, during...

  6. Solar Irradiance from 165 to 400 nm in 2008 and UV Variations in Three Spectral Bands During Solar Cycle 24

    Science.gov (United States)

    Meftah, M.; Bolsée, D.; Damé, L.; Hauchecorne, A.; Pereira, N.; Irbah, A.; Bekki, S.; Cessateur, G.; Foujols, T.; Thiéblemont, R.

    2016-12-01

    Accurate measurements of the solar spectral irradiance (SSI) and its temporal variations are of primary interest to better understand solar mechanisms, and the links between solar variability and Earth's atmosphere and climate. The SOLar SPECtrum (SOLSPEC) instrument of the Solar Monitoring Observatory (SOLAR) payload onboard the International Space Station (ISS) has been built to carry out SSI measurements from 165 to 3088 nm. We focus here on the ultraviolet (UV) part of the measured solar spectrum (wavelengths less than 400 nm) because the UV part is potentially important for understanding the solar forcing of Earth's atmosphere and climate. We present here SOLAR/SOLSPEC UV data obtained since 2008, and their variations in three spectral bands during Solar Cycle 24. They are compared with previously reported UV measurements and model reconstructions, and differences are discussed.

  7. Surface Albedo and Spectral Variability of Ceres

    CERN Document Server

    Li, Jian-Yang; Nathues, Andreas; Corre, Lucille Le; Izawa, Matthew R M; Clouts, Edward A; Sykes, Mark V; Carsenty, Uri; Castillo-Rogez, Julie C; Hoffmann, Martin; Jaumann, Ralf; Krohn, Katrin; Mottola, Stefano; Prettyman, Thomas H; Schaefer, Michael; Schenk, Paul; Schröder, Stefan E; Williams, David A; Smith, David E; Zuber, Maria T; Konopliv, Alexander S; Park, Ryan S; Raymond, Carol A; Russell, Christopher T

    2016-01-01

    Previous observations suggested that Ceres has active but possibly sporadic water outgassing, and possibly varying spectral characteristics in a time scale of months. We used all available data of Ceres collected in the past three decades from the ground and the Hubble Space Telescope, and the newly acquired images by Dawn Framing Camera to search for spectral and albedo variability on Ceres, in both a global scale and local regions, particularly the bright spots inside Occator crater, over time scales of a few months to decades. Our analysis has placed an upper limit on the possible temporal albedo variation on Ceres. Sporadic water vapor venting, or any possibly ongoing activity on Ceres, is not significant enough to change the albedo or the area of the bright features in Occator crater by >15%, or the global albedo by >3% over various time scales that we searched. Recently reported spectral slope variations can be explained by changing Sun-Ceres-Earth geometry. The active area on Ceres is less than 1 km$^2...

  8. [Study of the Detecting System of CH4 and SO2 Based on Spectral Absorption Method and UV Fluorescence Method].

    Science.gov (United States)

    Wang, Shu-tao; Wang, Zhi-fang; Liu, Ming-hua; Wei, Meng; Chen, Dong-ying; Wang, Xing-long

    2016-01-01

    According to the spectral absorption characteristics of polluting gases and fluorescence characteristics, a time-division multiplexing detection system is designed. Through this system we can detect Methane (CH4) and sulfur dioxide (SO2) by using spectral absorption method and the SO2 can be detected by using UV fluorescence method. The system consists of four parts: a combination of a light source which could be switched, the common optical path, the air chamber and the signal processing section. The spectral absorption characteristics and fluorescence characteristics are measured first. Then the experiment of detecting CH4 and SO2 through spectral absorption method and the experiment of detecting SO2 through UV fluorescence method are conducted, respectively. Through measuring characteristics of spectral absorption and fluorescence, we get excitation wavelengths of SO2 and CH4 measured by spectral absorption method at the absorption peak are 280 nm and 1.64 μm, respectively, and the optimal excitation wavelength of SO2 measured by UV fluorescence method is 220 nm. we acquire the linear relation between the concentration of CH4 and relative intensity and the linear relation between the concentration of SO2 and output voltage after conducting the experiment of spectral absorption method, and the linearity are 98.7%, 99.2% respectively. Through the experiment of UV fluorescence method we acquire that the relation between the concentration of SO2 and the voltage is linear, and the linearity is 99.5%. Research shows that the system is able to be applied to detect the polluted gas by absorption spectrum method and UV fluorescence method. Combing these two measurement methods decreases the costing and the volume, and this system can also be used to measure the other gases. Such system has a certain value of application.

  9. Spectrally selective UV bactericidal effect for curative treatment of post-surgical intra-abdominal abscesses and other infections

    Science.gov (United States)

    Dudelzak, Alexander E.; Miller, Mark A.; Babichenko, Sergey M.

    2004-07-01

    Results of in-vitro studies of bactericidal effects of ultraviolet (UV) irradiation on strains causing drug-resistant endo-cavital infections (Enterococcus, Staphylococcus aureus, Pseudomonas aeruginosa, and others) are presented. An original technique to measure effects of UV-irradiation on bacterial growth at different wavelengths has been developed. Spectral dependences of the bactericidal effect have been observed, and spectral maxima of bactericidal efficiency have been found. Applications to curative treatments of wounds, post-surgical intra-abdominal abscesses and other diseases are discussed.

  10. A CORRELATION BETWEEN Lyα SPECTRAL LINE PROFILE AND REST-FRAME UV MORPHOLOGY

    Energy Technology Data Exchange (ETDEWEB)

    Vivian U; Hemmati, Shoubaneh; Darvish, Behnam; Mobasher, Bahram; Nayyeri, Hooshang; Mallery, Ryan [Department of Physics and Astronomy, University of California, Riverside, 900 University Avenue, Riverside, CA 92521 (United States); Dickinson, Mark [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Mail Stop 169-221, Pasadena, CA 91109 (United States); Spinrad, Hyron, E-mail: vivianu@ucr.edu [Department of Astronomy, University of California, Berkeley, CA 94720 (United States)

    2015-12-10

    We explore the relationship between the spectral shape of the Lyα emission and the UV morphology of the host galaxy using a sample of 304 Lyα-emitting BVi-dropouts at 3 < z < 7 in the Great Observatories Origins Deep Survey and Cosmic Evolution Survey fields. Using our extensive reservoir of high-quality Keck DEIMOS spectra combined with Hubble Space Telescope WFC3 data, we measure the Lyα line asymmetries for individual galaxies and compare them to axial ratios measured from observed J- and H-band (restframe UV) images. We find that the Lyα skewness exhibits a large scatter at small elongation (a/b < 2), and this scatter decreases as the axial ratio increases. Comparison of this trend to radiative transfer models and various results from the literature suggests that these high-redshift Lyα emitters are not likely to be intrinsically round and symmetric disks, but they probably host galactic outflows traced by Lyα emitting clouds. The ionizing sources are centrally located, and the optical depth is a good indicator of the absorption and scattering events on the escape path of Lyα photons from the source. Our results find no evidence of evolution in Lyα asymmetry or axial ratio with look-back time.

  11. A Correlation Between Ly{\\alpha} Spectral Line Profile and Rest-Frame UV Morphology

    CERN Document Server

    U, Vivian; Darvish, Behnam; Mobasher, Bahram; Nayyeri, Hooshang; Dickinson, Mark; Stern, Daniel; Spinrad, Hyron; Mallery, Ryan

    2015-01-01

    We explore the relationship between the spectral shape of the Ly{\\alpha} emission and the UV morphology of the host galaxy using a sample of 304 Ly{\\alpha}-emitting BV i-dropouts at 3 < z < 7 in the GOODS and COSMOS fields. Using our extensive reservoir of high-quality Keck DEIMOS spectra combined with HST WFC3 data, we measure the Ly{\\alpha} line asymmetries for individual galaxies and compare them to axial ratios measured from observed J- and H-band (restframe UV) images. We find that the Ly{\\alpha} skewness exhibits a large scatter at small elongation (a/b < 2), and this scatter decreases as axial ratio increases. Comparison of this trend to radiative transfer models and various results from literature suggests that these high-redshift Ly{\\alpha} emitters are not likely to be intrinsically round and symmetric disks, but they probably host galactic outflows traced by Ly{\\alpha} emitting clouds. The ionizing sources are centrally located, with the optical depth a good indicator of the absorption and...

  12. Effect of UV Radiation on the Spectral Fingerprints of Earth-like Planets Orbiting M dwarfs

    CERN Document Server

    Rugheimer, S; Segura, A; Linsky, J; Mohanty, S

    2015-01-01

    We model the atmospheres and spectra of Earth-like planets orbiting the entire grid of M dwarfs for active and inactive stellar models with $T_{eff}$ = 2300K to $T_{eff}$ = 3800K and for six observed MUSCLES M dwarfs with UV radiation data. We set the Earth-like planets at the 1AU equivalent distance and show spectra from the VIS to IR (0.4$\\mu$m - 20$\\mu$m) to compare detectability of features in different wavelength ranges with JWST and other future ground- and spaced-based missions to characterize exo-Earths. We focus on the effect of UV activity levels on detectable atmospheric features that indicate habitability on Earth, namely: H$_2$O, O$_3$, CH$_4$, N$_2$O and CH$_3$Cl. To observe signatures of life - O$_2$/O$_3$ in combination with reducing species like CH$_4$, we find that early and active M dwarfs are the best targets of the M star grid for future telescopes. The O$_2$ spectral feature at 0.76$\\mu$m is increasingly difficult to detect in reflected light of later M dwarfs due to low stellar flux in ...

  13. Impacts of brown carbon from biomass burning on surface UV and ozone photochemistry in the Amazon Basin

    KAUST Repository

    Mok, Jungbin

    2016-11-11

    The spectral dependence of light absorption by atmospheric particulate matter has major implications for air quality and climate forcing, but remains uncertain especially in tropical areas with extensive biomass burning. In the September-October 2007 biomass-burning season in Santa Cruz, Bolivia, we studied light absorbing (chromophoric) organic or “brown” carbon (BrC) with surface and space-based remote sensing. We found that BrC has negligible absorption at visible wavelengths, but significant absorption and strong spectral dependence at UV wavelengths. Using the ground-based inversion of column effective imaginary refractive index in the range 305–368 nm, we quantified a strong spectral dependence of absorption by BrC in the UV and diminished ultraviolet B (UV-B) radiation reaching the surface. Reduced UV-B means less erythema, plant damage, and slower photolysis rates. We use a photochemical box model to show that relative to black carbon (BC) alone, the combined optical properties of BrC and BC slow the net rate of production of ozone by up to 18% and lead to reduced concentrations of radicals OH, HO2, and RO2 by up to 17%, 15%, and 14%, respectively. The optical properties of BrC aerosol change in subtle ways the generally adverse effects of smoke from biomass burning.

  14. Impacts of brown carbon from biomass burning on surface UV and ozone photochemistry in the Amazon Basin

    Science.gov (United States)

    Mok, Jungbin; Krotkov, Nickolay A.; Arola, Antti; Torres, Omar; Jethva, Hiren; Andrade, Marcos; Labow, Gordon; Eck, Thomas F.; Li, Zhanqing; Dickerson, Russell R.; Stenchikov, Georgiy L.; Osipov, Sergey; Ren, Xinrong

    2016-11-01

    The spectral dependence of light absorption by atmospheric particulate matter has major implications for air quality and climate forcing, but remains uncertain especially in tropical areas with extensive biomass burning. In the September-October 2007 biomass-burning season in Santa Cruz, Bolivia, we studied light absorbing (chromophoric) organic or “brown” carbon (BrC) with surface and space-based remote sensing. We found that BrC has negligible absorption at visible wavelengths, but significant absorption and strong spectral dependence at UV wavelengths. Using the ground-based inversion of column effective imaginary refractive index in the range 305–368 nm, we quantified a strong spectral dependence of absorption by BrC in the UV and diminished ultraviolet B (UV-B) radiation reaching the surface. Reduced UV-B means less erythema, plant damage, and slower photolysis rates. We use a photochemical box model to show that relative to black carbon (BC) alone, the combined optical properties of BrC and BC slow the net rate of production of ozone by up to 18% and lead to reduced concentrations of radicals OH, HO2, and RO2 by up to 17%, 15%, and 14%, respectively. The optical properties of BrC aerosol change in subtle ways the generally adverse effects of smoke from biomass burning.

  15. Assessment of interplay between UV wavelengths, material surfaces and food residues in open surface hygiene validation

    DEFF Research Database (Denmark)

    Abban, Stephen; Jakobsen, Mogens; Jespersen, Lene

    2014-01-01

    The use of UV-visible radiation for detecting invisible residue on different surfaces as a means of validating cleanliness was investigated. Wavelengths at 365, 395, 435, 445, 470 and 490 nm from a monochromator were used to detect residues of beef, chicken, apple, mango and skim milk. These were......-time hygiene validation of surfaces....

  16. Effective UV surface albedo of seasonally snow-covered lands

    Science.gov (United States)

    Tanskanen, A.; Manninen, T.

    2007-05-01

    At ultraviolet wavelengths the albedo of most natural surfaces is small with the striking exception of snow and ice. Therefore, snow cover is a major challenge for various applications based on radiative transfer modelling. The aim of this work was to determine the characteristic effective UV range surface albedo of various land cover types when covered by snow. First we selected 1 by 1 degree sample regions that met three criteria: the sample region contained dominantly subpixels of only one land cover type according to the 8 km global land cover classification product from the University of Maryland; the average slope of the sample region was less than 2 degrees according to the USGS's HYDRO1K slope data; the sample region had snow cover in March according to the NSIDC Northern Hemisphere weekly snow cover data. Next we generated 1 by 1 degree gridded 360 nm surface albedo data from the Nimbus-7 TOMS Lambertian equivalent reflectivity data, and used them to construct characteristic effective surface albedo distributions for each land cover type. The resulting distributions showed that each land cover type experiences a characteristic range of surface albedo values when covered by snow. The result is explained by the vegetation that extends upward beyond the snow cover and masks the bright snow covered surface.

  17. Assessment of UV biological spectral weighting functions for phenolic metabolites and growth responses in silver birch seedlings.

    Science.gov (United States)

    Kotilainen, Titta; Venäläinen, Tuulia; Tegelberg, Riitta; Lindfors, Anders; Julkunen-Tiitto, Riitta; Sutinen, Sirkka; O'Hara, Robert B; Aphalo, Pedro J

    2009-01-01

    In research concerning stratospheric ozone depletion, action spectra are used as biological spectral weighting functions (BSWFs) for describing the effects of UV radiation on plant responses. Our aim was to evaluate the appropriateness of six frequently used BSWFs that differ in effectiveness with increasing wavelength. The evaluation of action spectra was based on calculating the effective UV radiation doses according to 1-2) two formulations of the generalized plant action spectrum, 3) a spectrum for ultraviolet induced erythema in human skin, 4) a spectrum for the accumulation of a flavonol in Mesembryanthemum crystallinum, 5) a spectrum for DNA damage in alfalfa seedlings and 6) the plant growth action spectrum. We monitored effects of UV radiation on the concentration of individual UV absorbing metabolites and chlorophyll concentrations in leaves and growth responses of silver birch (Betula pendula) seedlings. Experiments were conducted outdoors using plastic films attenuating different parts of the UV spectrum. Chlorophyll concentrations and growth were not affected by the UV treatments. The response to UV radiation varied between and within groups of phenolics. In general, the observed responses of phenolic groups and individual flavonoids were best predicted by action spectra extending into the UV-A region with moderate effectiveness.

  18. Separation Surfaces in the Spectral TV Domain for Texture Decomposition

    Science.gov (United States)

    Horesh, Dikla; Gilboa, Guy

    2016-09-01

    In this paper we introduce a novel notion of separation surfaces for image decomposition. A surface is embedded in the spectral total-variation (TV) three dimensional domain and encodes a spatially-varying separation scale. The method allows good separation of textures with gradually varying pattern-size, pattern-contrast or illumination. The recently proposed total variation spectral framework is used to decompose the image into a continuum of textural scales. A desired texture, within a scale range, is found by fitting a surface to the local maximal responses in the spectral domain. A band above and below the surface, referred to as the \\textit{Texture Stratum}, defines for each pixel the adaptive scale-range of the texture. Based on the decomposition an application is proposed which can attenuate or enhance textures in the image in a very natural and visually convincing manner.

  19. Spectral Signatures of Surface Materials in Pig Buildings

    DEFF Research Database (Denmark)

    Zhang, GuoQiang; Strøm, Jan; Blanke, Mogens

    2006-01-01

    Manual cleaning of pig production buildings based on high-pressure water cleaners is unappealing to workers, because it is tedious and health threatening. To replace manual cleaning, a few cleaning robots have been commercialised. With no cleanliness sensor available, the operation of these robots...... spectral bands for each type of the materials, in which the spectral signals can be used for discrimination of dirty and clean condition of the surfaces. (c) 2006 IAgrE. All rights reserved Published by Elsevier Ltd...

  20. European UV DataBase (EUVDB) as a repository and quality analyser for solar spectral UV irradiance monitored in Sodankylä

    Science.gov (United States)

    Heikkilä, Anu; Kaurola, Jussi; Lakkala, Kaisa; Matti Karhu, Juha; Kyrö, Esko; Koskela, Tapani; Engelsen, Ola; Slaper, Harry; Seckmeyer, Gunther

    2016-08-01

    Databases gathering atmospheric data have great potential not only as data storages but also in serving as platforms for coherent quality assurance (QA). We report on the flagging system and QA tools designed for and implemented in the European UV DataBase (EUVDB; http://uv.fmi.fi/uvdb/) for measured data on solar spectral UV irradiance. We confine the study on the data measured by Brewer #037 MkII spectroradiometer in Sodankylä (67.37° N, 26.63° E) in 1990-2014. The quality indicators associated with the UV irradiance spectra uploaded into the database are retrieved from the database and subjected to a statistical analysis. The study demonstrates the performance of the QA tools of the EUVDB. In addition, it yields an overall view of the availability and quality of the solar UV spectra recorded in Sodankylä over a quarter of a century. Over 90 % of the four main quality indicators are flagged as GREEN, indicating the highest achievable quality. For the BLACK flags, denoting data not meeting the pre-defined requirements, the percentages for all the indicators remain below 0.12 %.

  1. Surface area and conductivity of polyaniline synthesized under UV irradiation

    Science.gov (United States)

    Budi, S.; Fitri, E.; Paristiowati, M.; Cahyana, U.; Pusparini, E.; Nasbey, H.; Imaddudin, A.

    2017-02-01

    This paper reports our study on the synthesis of high electrical conductivity and surface area polyaniline using oxidative polymerization under UV light irradiation. The formation of emeraldine structures of polyaniline was revealed by major absorption bands of FTIR (Fourier transform infrared spectroscopy) spectra attributed to C-N stretching, C=C stretching in the benzenoid ring, C=C stretching in the quinoid ring and QNH+B stretching. XRD (X-ray diffractometer) measurements confirmed typical diffraction patterns with a crystallinity of 13% and 16% for polyaniline prepared under non-stirred and stirred reaction, respectively. SEM (Scanning electron microscope) studies showed more uniform morphology of polyaniline was obtained with stirring reaction process compare to those prepared without stirring. Surface analysis using SAA (surface area analyzer) showed that pure polyaniline with the relatively high surface area of ca.28 m2/g was successfully prepared in this work. Based on four point probe measurement, the prepared polyaniline possesses high conductivity which is important in electrode application.

  2. Spectral theory of infinite-area hyperbolic surfaces

    CERN Document Server

    Borthwick, David

    2016-01-01

    This text introduces geometric spectral theory in the context of infinite-area Riemann surfaces, providing a comprehensive account of the most recent developments in the field. For the second edition the context has been extended to general surfaces with hyperbolic ends, which provides a natural setting for development of the spectral theory while still keeping technical difficulties to a minimum. All of the material from the first edition is included and updated, and new sections have been added. Topics covered include an introduction to the geometry of hyperbolic surfaces, analysis of the resolvent of the Laplacian, scattering theory, resonances and scattering poles, the Selberg zeta function, the Poisson formula, distribution of resonances, the inverse scattering problem, Patterson-Sullivan theory, and the dynamical approach to the zeta function. The new sections cover the latest developments in the field, including the spectral gap, resonance asymptotics near the critical line, and sharp geometric constan...

  3. Estimating cloud optical thickness and associated surface UV irradiance from SEVIRI by implementing a semi-analytical cloud retrieval algorithm

    Directory of Open Access Journals (Sweden)

    P. Pandey

    2012-01-01

    Full Text Available In this paper, we describe the implementation of the Semi-Analytical Cloud Retrieval Algorithm (SACURA, to obtain scaled cloud optical thickness (SCOT from satellite imagery acquired with the SEVIRI instrument and surface UV irradiance levels. In estimation of SCOT particular care is given to the proper specification of the background (i.e., cloud-free spectral albedo and the retrieval of the cloud water phase from reflectance ratios in SEVIRI's 0.6 μm and 1.6 μm spectral bands. The SACURA scheme is then applied to daytime SEVIRI imagery over Europe, for the month of June 2006, at 15-min time increments. The resulting SCOT fields are compared with values obtained by the CloudSat experimental satellite mission, yielding a negligible bias, correlation coefficients ranging from 0.51 to 0.78, and a root mean square difference of 1 to 2 SCOT increments. These findings compare favourably to results from similar intercomparison exercises reported in the literature. Based on the retrieved SCOT from SEVIRI and radiative transfer modelling approach, simple parameterisations are proposed to estimate the surface UV-A and UV-B irradiance. The validation of the modelled UV-A and UV-B irradiance against the measurements over two Belgian stations, Redu and Ostend, indicate good agreement with the high correlation, index of agreement and low bias. The SCOT fields estimated by implementing SACURA on imagery from geostationary satellite are reliable and its impact on surface UV irradiance levels is well produced.

  4. Spectral purity enhancement for the EUV lithography systems by suppressing UV reflection from multilayers

    Science.gov (United States)

    Huang, Qiushi; de Boer, Meint; Barreux, Jonathan; Paardekooper, Daniel M.; van den Boogaard, Toine; van de Kruijs, Robbert; Zoethout, Erwin; Louis, Eric; Bijkerk, Fred

    2014-04-01

    Plasma based radiation sources optimized to emit 13.5 nm Extreme UV radiation also produce a significant amount of light at longer wavelengths. This so called out-of-band (OoB) radiation is detrimental for the imaging capabilities of an EUV lithographic imaging system, particularly the ultraviolet (UV) parts of the light (λ=100-400 nm). To suppress these wavelengths while maintaining the high efficiency of the mirror for EUV light, several methods have been developed, including phase-shift gratings (PsG) and anti-reflection layers (SPE layer). Both methods have achieved a suppression factor of 10 - 30 around the target wavelength. To achieve a full band suppression effect with a minimum loss of EUV light, a new scheme based on surface pyramid structures was developed. An average suppression of more than 10 times was achieved with a relative EUV efficiency of 82.2% by using the Si pyramids structure (compared to a flat multilayer (ML)). Recently, we have successfully produced a pyramid structure consisting of multilayers which greatly improves the relative EUV efficiency to 94.2%.

  5. A New Algorithm for the Satellite-Based Retrieval of Solar Surface Irradiance in Spectral Bands

    Directory of Open Access Journals (Sweden)

    Annette Hammer

    2012-03-01

    Full Text Available Accurate solar surface irradiance data is a prerequisite for an efficient planning and operation of solar energy systems. Further, it is essential for climate monitoring and analysis. Recently, the demand on information about spectrally resolved solar surface irradiance has grown. As surface measurements are rare, satellite derived information with high accuracy might fill this gap. This paper describes a new approach for the retrieval of spectrally resolved solar surface irradiance from satellite data. The method combines a eigenvector-hybrid look-up table approach for the clear sky case with satellite derived cloud transmission (Heliosat method. The eigenvector LUT approach is already used to retrieve the broadband solar surface irradiance of data sets provided by the Climate Monitoring Satellite Application Facility (CM-SAF. This paper describes the extension of this approach to wavelength bands and the combination with spectrally resolved cloud transmission values derived with radiative transfer corrections of the broadband cloud transmission. Thus, the new approach is based on radiative transfer modeling and enables the use of extended information about the atmospheric state, among others, to resolve the effect of water vapor and ozone absorption bands. The method is validated with spectrally resolved measurements from two sites in Europe and by comparison with radiative transfer calculations. The validation results demonstrate the ability of the method to retrieve accurate spectrally resolved irradiance from satellites. The accuracy is in the range of the uncertainty of surface measurements, with exception of the UV and NIR ( ≥ 1200 nm part of the spectrum, where higher deviations occur.

  6. Surface Emissivity Effects on Thermodynamic Retrieval of IR Spectral Radiance

    Science.gov (United States)

    Zhou, Daniel K.; Larar, Allen M.; Smith, William L.; Liu, Xu

    2006-01-01

    The surface emissivity effect on the thermodynamic parameters (e.g., the surface skin temperature, atmospheric temperature, and moisture) retrieved from satellite infrared (IR) spectral radiance is studied. Simulation analysis demonstrates that surface emissivity plays an important role in retrieval of surface skin temperature and terrestrial boundary layer (TBL) moisture. NAST-I ultraspectral data collected during the CLAMS field campaign are used to retrieve thermodynamic properties of the atmosphere and surface. The retrievals are then validated by coincident in-situ measurements, such as sea surface temperature, radiosonde temperature and moisture profiles. Retrieved surface emissivity is also validated by that computed from the observed radiance and calculated emissions based on the retrievals of surface temperature and atmospheric profiles. In addition, retrieved surface skin temperature and emissivity are validated together by radiance comparison between the observation and retrieval-based calculation in the window region where atmospheric contribution is minimized. Both simulation and validation results have lead to the conclusion that variable surface emissivity in the inversion process is needed to obtain accurate retrievals from satellite IR spectral radiance measurements. Retrieval examples are presented to reveal that surface emissivity plays a significant role in retrieving accurate surface skin temperature and TBL thermodynamic parameters.

  7. Beneficial and Detrimental Effects of UV on Aquatic Organisms: Implications of Spectral Variation

    NARCIS (Netherlands)

    Williamson, C.E.; Neale, P.J.; Grad, G.; Lange, de H.J.; Hargreaves, B.R.

    2001-01-01

    Solar ultraviolet radiation (UVR) may have beneficial as well as detrimental effects on living systems. For example, UV-B radiation (280¿320 nm) is generally damaging, while UV-A radiation (320¿400 nm) may cause damage or stimulate beneficial photorepair of UV-B damage. The nature of both direct and

  8. Spectral reflectance properties of minerals exposed to simulated Mars surface conditions

    Science.gov (United States)

    Cloutis, E. A.; Craig, M. A.; Kruzelecky, R. V.; Jamroz, W. R.; Scott, A.; Hawthorne, F. C.; Mertzman, S. A.

    2008-05-01

    A number of mineral species were exposed to martian surface conditions of atmospheric pressure and composition, temperature, and UV light regime, and their evolution was monitored using reflectance spectroscopy. The stabilities for different groups varied widely. Phyllosilicate spectra all showed measurable losses of interlayer H 2O, with some structural groups showing more rapid H 2O loss than others. Loss of OH from the phyllosilicates is not always accompanied by a change in metal-OH overtone absorption bands. OH-bearing sulfates, such as jarosite and alunite, show no measurable change in spectral properties, suggesting that they should be spectrally detectable on Mars on the basis of diagnostic absorption bands in the 0.4-2.5 μm region. Fe 3+- and H 2O-bearing sulfates all showed changes in the appearance and/or reduction in depths of hydroxo-bridged Fe 3+ absorption bands, particularly at 0.43 μm. The spectral changes were often accompanied by visible color changes, suggesting that subsurface sulfates exposed to the martian surface environment may undergo measurable changes in reflectance spectra and color over short periods of time (days to weeks). Organic-bearing geological materials showed no measurable change in C sbnd H related absorption bands, while carbonates and hydroxides also showed no systematic changes in spectral properties. The addition of ultraviolet irradiation did not seem to affect mineral stability or rate of spectral change, with one exception (hexahydrite). In some cases, spectral changes could be related to the formation of specific new phases. The data also suggest that hydrated minerals detected on Mars to date retain their diagnostic spectral properties that allow their unique identification.

  9. High Gas Surface Densities yet Low UV Attenuation in z $\\sim$ 1 Disc Galaxies

    CERN Document Server

    Nordon, Raanan

    2016-01-01

    The gas in galaxies is both the fuel for star formation and a medium that attenuates the light of the young stars. We study the relations between UV attenuation, spectral slope, star formation rates, and molecular gas surface densities in a sample of 28 z$\\sim$1 and a reference sample of 32 z$\\sim$0 galaxies that are detected in CO, far-infrared, and rest frame UV. The samples are dominated by disc-like galaxies close to the main SFR--mass relation. We find that the location of the z$\\sim$1 galaxies on the IRX-$\\beta$ plane is correlated with their gas-depletion time-scale $\\tau_{dep}$ and can predict $\\tau_{dep}$ with a standard deviation of 0.16 dex. We use IRX-$\\beta$ to estimate the mean total gas column densities at the locations of star formation in the galaxies, and compare them to the mean molecular gas surface densities as measured from CO. We confirm previous results regarding high $N_H/A_V$ in z$\\sim$1 galaxies. We estimate an increase in the gas filling factor by a factor of 4--6 from z$\\sim$0 to ...

  10. 纳米银的合成及其UV-Vis光谱特性%Synthesis and UV-Vis Spectral Properties of Silver Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    张万忠; 乔学亮; 陈建国

    2007-01-01

    作为贵金属纳米材料,纳米银在许多领域的广泛应用而成为当今纳米科学最感兴趣的研究对象.简单介绍了纳米银的合成方法如光化学法、超声辅助还原法、电化学还原法、模板法、辐射还原法和生物化学法,主要讨论了化学还原法和微乳液法以及纳米银合成研究的一些进展.光谱吸收是纳米银的重要性质,UV-Vis特征光谱是研究纳米银的形成和纳米晶生长的重要手段,因此详细评述了纳米银的光谱特性,最后,对它们的研究发展趋势进行了展望.%Silver nanoparticles, as noble metallic nanomaterials, are of particular interest today because of their applications in many areas. Besides a brief introduction on the synthetic methods of silver nanoparticles, such as chemical reduction,photochemical method, ultrasonic-assisted reduction, electro-chemical method, template, irradiating reduction and biochemical method, the mini-review mainly discuss chemical reduction and microemulsion method as well as some research advances of the methods for preparation of silver nanoparticles. The characteristic absorption spectra are the important properties of silver nanoparticles, and the UV-Vis spectral researches are good for characterization of the formation and growth of silver nanocrystals. Thus, the UV-Vis spectral properties of silver nanoparticles are reviewed. The possible developing trends of the study on the synthetic methods and spectral properties of silver nanoparticles are also prospected.

  11. Evolution of the complex refractive index in the UV spectral region in ageing secondary organic aerosol

    Science.gov (United States)

    Flores, J. M.; Zhao, D. F.; Segev, L.; Schlag, P.; Kiendler-Scharr, A.; Fuchs, H.; Watne, Å. K.; Bluvshtein, N.; Mentel, Th. F.; Hallquist, M.; Rudich, Y.

    2014-06-01

    The chemical and physical properties of secondary organic aerosol (SOA) formed by the photochemical degradation of biogenic and anthropogenic volatile organic compounds (VOC) are as yet still poorly constrained. The evolution of the complex refractive index (RI) of SOA, formed from purely biogenic VOC and mixtures of biogenic and anthropogenic VOC, was studied over a diurnal cycle in the SAPHIR photochemical outdoor chamber in Jülich, Germany. The correlation of RI with SOA chemical and physical properties such as oxidation level and volatility was examined. The RI was retrieved by a newly developed broadband cavity-enhanced spectrometer for aerosol optical extinction measurements in the UV spectral region (360 to 420 nm). Chemical composition and volatility of the particles were monitored by a high-resolution time-of-flight aerosol mass spectrometer, and a volatility tandem differential mobility analyzer. SOA was formed by ozonolysis of either (i) a mixture of biogenic VOC (α-pinene and limonene), (ii) biogenic VOC mixture with subsequent addition of an anthropogenic VOC (p-xylene-d10), or (iii) a mixture of biogenic and anthropogenic VOC. The SOA aged by ozone/OH reactions up to 29.5 h was found to be non-absorbing in all cases. The SOA with p-xylene-d10 showed an increase of the scattering component of the RI correlated with an increase of the O / C ratio and with an increase in the SOA density. There was a greater increase in the scattering component of the RI when the SOA was produced from the mixture of biogenic VOCs and anthropogenic VOC than from the sequential addition of the VOCs after approximately the same ageing time. The increase of the scattering component was inversely correlated with the SOA volatility. Two RI retrievals determined for the pure biogenic SOA showed a constant RI for up to 5 h of ageing. Mass spectral characterization shows the three types of the SOA formed in this study have a significant amount of semivolatile components. The

  12. UV spectral variability in the Herbig Ae star HR 5999. 11: The accretion interpretation

    Science.gov (United States)

    Perez, M. R.; Grady, C. A.; The, P. S.

    1993-01-01

    We report recent IUE high- and low-dispersion observations with the IUE long wavelength camera (LWP) and short wavelength camera (SWP) of the Herbig Ae star HR 5999. We have found a dramatic change in the structure of the Mg II h and k lines (2795.5, 2802.7 A) along with some continuum flux excesses especially at the short end of the SWP camera. LWP high dispersion observations of HR 5999 obtained between 1979 and 1990, at times of comparatively low UV continuum fluxes, exhibit P Cygni type m profiles in the Mg II resonance doublet. In contrast, observations made from September 1990 through March 16-18, 1992, with high W continuum fluxes, present Mg II lines with reverse P Cygni profiles indicative of some active episodic accretion. Accreting gas can also be detected in the additional red wings of the various Fe II and Mn II absorption lines, with velocities up to +300-350 km/s (September 1990). By September 10, 1992 the Mg II profile had returned to the type III P Cygni profile similar to those from earlier spectra. The correlation between the presence of large column densities of accreting gas and the continuum light variations supports suggestions by several authors that HR 5999 is surrounded by an optically thick, viscously heated accretion disk. Detection of accreting gas in the line of sight to HR 5999 permits us to place constraints on our viewing geometry for this system. A discussion is included comparing the spectral and physical similarities between HR 5999 and the more evolved proto-planetary candidate system, beta Pictoris.

  13. Search for olivine spectral signatures on the surface of Vesta

    Science.gov (United States)

    Palomba, E.; De Sanctis, M. C.; Ammannito, E.; Capaccioni, F.; Capria, M. T.; Farina, M.; Frigeri, A.; Longobardo, A.; Tosi, F.; Zambon, F.; McSween, H. Y.; Mittlefehldt, D. W.; Russell, C. T.; Raymond, C. A.; Sunshine, J.; McCord, T. B.

    2012-04-01

    The occurrence of olivines on Vesta were first postulated from traditional petrogenetic models which suggest the formation of olivine as lower crustal cumulates. An indirect confirmation is given by their presence as a minor component in some samples of diogenite meteorites, the harzburgitic diogenites and the dunitic diogenites, and as olivine mineral clasts in howardites. Another indication for this mineral was given by interpretations of ground-based and Hubble Space Telescope observations that suggested the presence of local olivine-bearing units on the surface of Vesta. The VIR instrument onboard the DAWN mission has been mapping Vesta since July 2011. VIR acquired hyperspectral images of Vesta's surface in the wavelength range from 0.25 to 5.1 µm during Approach, Survey and High Altitude Mapping (HAMO) orbits that allowed a 2/3 of the entire asteroid surface to be mapped. The VIR operative spectral interval, resolution and coverage is suitable for the detection and mapping of any olivine rich regions that may occur on the Vesta surface. The abundance of olivine in diogenites is typically lower than 10% but some samples richer in olivine are known. However, we do not expect to have extensive exposures of olivine-rich material on Vesta. Moreover, the partial overlap of olivine and pyroxene spectral signatures will make olivine difficult to detect. Different spectral parameters have been used to map olivine on extraterrestrial bodies, and here we discuss the different approaches used, and develop new ones specifically for Vesta. Our new methods are based on combinations of the spectral parameters relative to the 1 and 2 micron bands (the most prominent spectral features of Vesta surface in the visible and the infrared), such as band center locations, band depths, band areas, band area ratios. Before the direct application to the VIR data, the efficiency of each approach is evaluated by means of analysis of laboratory spectra of HED meteorites, pyroxenes

  14. Search for Olivine Spectral Signatures on the Surface of Vesta

    Science.gov (United States)

    Palomba, E.; De Sanctis, M. C.; Ammannito, E.; Capaccioni, F.; Capria, M. T.; Farina, M.; Frigeri, A.; Longobardo, A.; Tosi, F.; Zambon, F.; McSween, H. Y.; Mittlefehldt, D. W.; Russell, C. T.; Raymond, C. A.; Sunshine, J.; McCord, T. B.

    2012-01-01

    The occurrence of olivines on Vesta were first postulated from traditional petrogenetic models which suggest the formation of olivine as lower crustal cumulates. An indirect confirmation is given by their presence as a minor component in some samples of diogenite meteorites, the harzburgitic diogenites and the dunitic diogenites, and as olivine mineral clasts in howardites. Another indication for this mineral was given by interpretations of groundbased and Hubble Space Telescope observations that suggested the presence of local olivine-bearing units on the surface of Vesta. The VIR instrument onboard the DAWN mission has been mapping Vesta since July 2011. VIR acquired hyperspectral images of Vesta s surface in the wavelength range from 0.25 to 5.1 m during Approach, Survey and High Altitude Mapping (HAMO) orbits that allowed a 2/3 of the entire asteroid surface to be mapped. The VIR operative spectral interval, resolution and coverage is suitable for the detection and mapping of any olivine rich regions that may occur on the Vesta surface. The abundance of olivine in diogenites is typically lower than 10% but some samples richer in olivine are known. However, we do not expect to have extensive exposures of olivine-rich material on Vesta. Moreover, the partial overlap of olivine and pyroxene spectral signatures will make olivine difficult to detect. Different spectral parameters have been used to map olivine on extraterrestrial bodies, and here we discuss the different approaches used, and develop new ones specifically for Vesta. Our new methods are based on combinations of the spectral parameters relative to the 1 and 2 micron bands (the most prominent spectral features of Vesta surface in the visible and the infrared), such as band center locations, band depths, band areas, band area ratios. Before the direct application to the VIR data, the efficiency of each approach is evaluated by means of analysis of laboratory spectra of HED meteorites, pyroxenes, olivines

  15. Enveloping Spectral Surfaces: Covariate Dependent Spectral Analysis of Categorical Time Series.

    Science.gov (United States)

    Krafty, Robert T; Xiong, Shuangyan; Stoffer, David S; Buysse, Daniel J; Hall, Martica

    2012-09-01

    Motivated by problems in Sleep Medicine and Circadian Biology, we present a method for the analysis of cross-sectional categorical time series collected from multiple subjects where the effect of static continuous-valued covariates is of interest. Toward this goal, we extend the spectral envelope methodology for the frequency domain analysis of a single categorical process to cross-sectional categorical processes that are possibly covariate dependent. The analysis introduces an enveloping spectral surface for describing the association between the frequency domain properties of qualitative time series and covariates. The resulting surface offers an intuitively interpretable measure of association between covariates and a qualitative time series by finding the maximum possible conditional power at a given frequency from scalings of the qualitative time series conditional on the covariates. The optimal scalings that maximize the power provide scientific insight by identifying the aspects of the qualitative series which have the most pronounced periodic features at a given frequency conditional on the value of the covariates. To facilitate the assessment of the dependence of the enveloping spectral surface on the covariates, we include a theory for analyzing the partial derivatives of the surface. Our approach is entirely nonparametric, and we present estimation and asymptotics in the setting of local polynomial smoothing.

  16. Effect of spectral range in surface inactivation of Listeria innocua using broad-spectrum pulsed light.

    Science.gov (United States)

    Woodling, Sarah E; Moraru, Carmen I

    2007-04-01

    Pulsed light (PL) treatment is an alternative to traditional thermal treatment that has the potential to achieve several log-cycle reductions in the concentration of microorganisms. One issue that is still debated is related to what specifically causes cell death after PL treatments. The main objective of this work was to elucidate which portions of the PL range are responsible for bacterial inactivation. Stainless steel coupons with controlled surface properties were inoculated with a known concentration of Listeria innocua in the stationary growth phase and treated with 1 to 12 pulses of light at a pulse rate of 3 pulses per s and a pulse width of 360 micros. The effects of the full spectrum (lambda = 180 to 1,100 nm) were compared with the effects obtained when only certain regions of UV, visible, and near-infrared light were used. The effectiveness of the treatments was determined in parallel by the standard plate count and most-probable-number techniques. At a fluence of about 6 J/cm(2), the full-spectrum PL treatment resulted in a 4.08-log reduction of L. innocua on a Mill finish surface, the removal of lambda light resulted in no lethal effects on L. innocua. Overwhelmingly, the portions of the PL spectrum responsible for bacterial death are the UV-B and UV-C spectral ranges (X light (lambda > 400 nm). This work provides additional supporting evidence that cell death in PL treatment is due to exposure to UV light. Additionally, it was shown that even a minor modification of the light path or the UV light spectrum in PL treatments can have a significant negative impact on the treatment intensity and effectiveness.

  17. Effect of surface plasmon resonance on the photocatalytic activity of Au/TiO2 under UV/visible illumination.

    Science.gov (United States)

    Tseng, Yao-Hsuan; Chang, I-Guo; Tai, Yian; Wu, Kung-Wei

    2012-01-01

    In this study, gold-loaded titanium dioxide was prepared by an impregnation method to investigate the effect of surface plasmon resonance (SPR) on photoactivity. The deposited gold nanoparticles (NPs) absorb visible light because of SPR. The effects of both the gold content and the TiO2 size of Au/TiO2 on SPR and the photocatalytic efficiency were investigated. The morphology, crystal structure, light absorption, emission from the recombination of a photoexcited electron and hole, and the degree of aggregation were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-visible-diffuse reflectance spectra (UV-VIS-DRS), photoluminescence (PL) spectroscopy, and turbidimetry, respectively. Photocatalytic activity was evaluated by the decolorization of methyl orange solution over modified titania under UV and UV/GLED (green light emitting diode) illumination. Au/TiO2 NPs exhibited an absorption peak (530-570 nm) because of SPR. The results of our photocatalytic experiments indicated that the UV-inducedly photocatalytic reaction rate was improved by simultaneously using UV and green light illumination; this corresponds to the adsorption region of SPR. Au/TiO2 could use the enhanced electric field amplitude on the surface of the Au particle in the spectral vicinity of its plasmon resonance and thus improve the photoactivity. Experimental results show that the synergistic effect between UV and green light for the improvement of photoactivity increases with increasing the SPR absorption, which in turn is affected by the Au content and TiO2 size.

  18. Spectral reflectance of SNC meteorites: Relationships to Martian surface composition

    Science.gov (United States)

    Mcfadden, L. A.

    1987-01-01

    The spectral signatures of each of the Shergottite-Nakhlite-Chassignite (SNC) meteorite types measured to date are unique among extraterrestrial materials. Reflectance spectra of dark regions of Mars show evidence of basaltic composition. Analytic analysis of absorption band positions and widths in reflectance spectra of SNC meteorites will permit comparisons with spectra from approximately 600 km sized regions for which high-quality, near-IR spectra are available. Multi-spectral mapping data from orbital spacecraft is expected to provide the necessary spectra to determine basaltic compositions of smaller regions on Mars provided fresh, unaltered basalts can be observed or the effects of Martian weathering can be understood and removed from the spectra. With modeling of spectral weathering and mixing of SNC meteoritic assemblages it should be possible with the Mars Observer data to test for the presence of SNC analogs on the Martian surface. Before the relationship between the basaltic composition of units on Mars and the SNC meteorites can be addressed, it is necessary to analyze the absorption band parameters of the SNC reflectance spectra and to acquire high resolution spectral data on smaller regions of the Martian surface.

  19. Spectral variations of UV-A and PAR solar radiation in estuarine waters of Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Talaulikar, M.; Suresh, T.; Silveira, N.; Desa, E.; Matondkar, S.G.P.; Lotlikar, A.

    by Particulate organic carbon (POC). Both UV-B and UV-A have important effects on bacterial activities, phytoplankton photosynthesis, photo-degradation of chromophoric dissolved organic matter (CDOM) [1], and photoproduction of DNA damages in bacterio... for plankton communities”. Limnol. Oceanogr., 41, pp. 1024–1034. 1996. [7] Cullen, J. J., and P. J. Neale, “Ultraviolet radiation, ozone depletion, and marine photosynthesis”, Photosynth. Res., 39, pp. 303–320, 1994. [8] Jeffrey, W. H., R. J. Pledger, P...

  20. Space weathering of asteroidal surfaces. Influence on the UV-Vis spectra

    Science.gov (United States)

    Kaňuchová, Z.; Baratta, G. A.; Garozzo, M.; Strazzulla, G.

    2010-07-01

    Context. The surfaces of airless bodies in the Solar System are continuously altered by the bombardment of micrometeoroids and irradiation by solar wind, flares, and cosmic particles. Major effects of this process - space weathering - are darkening and “reddening” of the spectra of surface materials, as well as a “degrading” of absorption features. Aims: We studied the changes induced by energetic ion irradiation in the ultraviolet-visual-near-infrared (UV-Vis-NIR) (0.2-0.98 μm) reflectance spectra of targets selected to mimic the surfaces of airless bodies in the inner Solar System. Our chosen targets are olivine pellets, pure or covered by an organic polymer (polystyrene), which is transparent before irradiation. Polystyrene is used as a template for organic matter of low volatility that can be present on asteroidal surfaces. Moreover we measured the changes induced by ion irradiation in the absorption coefficient of the polymer. The purpose was to have a tool to better compare laboratory with observed spectra and distinguish between planetary objects with pure silicate surfaces and those whose surface is covered by organic matter exposed to cosmic ion bombardment. Methods: The samples were irradiated in vacuum, at room temperature, with 200 keV protons or 200-400 keV argon ions. Before, during, and after irradiation diffuse reflectance spectra were acquired. Polystyrene films were also deposited on quartz substrates and irradiated while transmittance spectra were recorded. Results: We measured the variations of the absorption coefficient of polystyrene as a function of ion fluence. We showed that after ion irradiation the diffuse reflectance spectra of the samples covered by organics exhibit a much more significant variation than those of pure silicates. The spectra of targets made of olivine plus polystyrene can be fitted by using the measured absorption coefficient of polystyrene. Conclusions: The results obtained for pure olivine extend to the UV the

  1. Spectral response of solvent-cast polyvinyl chloride (PVC) thin film used as a long-term UV dosimeter.

    Science.gov (United States)

    Amar, Abdurazaq; Parisi, Alfio V

    2013-08-01

    The spectral response of solvent-cast polyvinyl chloride (PVC) thin film suitable for use as a long-term UV dosimeter has been determined by measuring the UV induced change in the 1064 cm(-1) peak intensity of the PVC's infrared (IR) spectra as a function of the wavelength of the incident radiation. Measurements using cut-off filters, narrow band-pass filters and monochromatic radiation showed that the 16 μm PVC film responds mainly to the UVB band. The maximum response was at 290 nm and decreasing exponentially with wavelength up to about 340 nm independent of temperature and exposure dose. The most suitable concentration (W/V%) of PVC/Tetrahydrofuran solution was found to be 10% and the best thickness for the dosimeter was determined as 16 μm.

  2. UV-curable low surface energy fluorinated polycarbonate-based polyurethane dispersion.

    Science.gov (United States)

    Hwang, Hyeon-Deuk; Kim, Hyun-Joong

    2011-10-15

    UV-curable low surface energy fluorinated polycarbonate-based polyurethane dispersions were synthesized by incorporating a hydroxy-terminated perfluoropolyether (PFPE) into the soft segment of polyurethane. The effects of the PFPE content on the UV-curing behavior, physical, surface, thermal properties and refractive index were investigated. The UV-curing behavior was analyzed by photo-differential scanning calorimetry. The surface free energy of the UV-cured film, which is related to the water or oil repellency, was calculated from contact angle measurements using the Lewis acid-base three liquids method. The surface free energy decreased significantly with increasing fluorine concentration because PFPE in the soft segment was tailored to the surface and produced a UV-cured film with a hydrophobic fluorine enriched surface, as confirmed by X-ray photoelectron spectroscopy. With increasing the fluorine content, the refractive indices of UV-cured films decreased. However, the UV-curing rate and final conversion was decreased with increasing contents of PFPE, which resulted in the decrease of the glass transition temperature (T(g)), crosslink density, tensile strength and surface hardness.

  3. Gas-phase absorption cross sections of 24 monocyclic aromatic hydrocarbons in the UV and IR spectral ranges

    Science.gov (United States)

    Etzkorn, Thomas; Klotz, Björn; Sørensen, Søren; Patroescu, Iulia V.; Barnes, Ian; Becker, Karl H.; Platt, Ulrich

    Absorption cross sections of 24 volatile and non-volatile derivatives of benzene in the ultraviolet (UV) and the infrared (IR) regions of the electromagnetic spectrum have been determined using a 1080 l quartz cell. For the UV a 0.5 m Czerny-Turner spectrometer coupled with a photodiode array detector (spectral resolution 0.15 nm) was used. IR spectra were recorded with an FT-IR spectrometer (Bruker IFS-88, spectral resolution 1 cm -1). Absolute absorption cross sections and the instrument function are given for the UV, while for the IR, absorption cross sections and integrated band intensities are reported. The study focused primarily on the atmospherically relevant methylated benzenes (benzene, toluene, o-xylene, m-xylene, p-xylene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, ethylbenzene, styrene) and their ring retaining oxidation products (benzaldehyde, o-tolualdehyde, m-tolualdehyde, p-tolualdehyde, phenol, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,4-dimethylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,4,6-trimethylphenol and ( E,Z)- and ( E,E)-2,4-hexadienedial). The UV absorption cross sections reported here can be used for the evaluation of DOAS spectra (Differential Optical Absorption Spectroscopy) for measurements of the above compounds in the atmosphere and in reaction chambers, while the IR absorption cross sections will primarily be useful in laboratory studies on atmospheric chemistry, where FT-IR spectrometry is an important tool.

  4. Estimation of surface UV levels based on Meteor-3/TOMS ozone data

    Energy Technology Data Exchange (ETDEWEB)

    Borisov, Y.A. [Central Aerological Observatory, Moscow (Russian Federation); Geogdzhaev, I.V. [Moscow Inst. of Physics and Technology, Moscow (Russian Federation); Khattatov, V.U. [Central Aerological Observatory, Moscow (Russian Federation)

    1995-12-31

    The major consequence of ozone layer depletion for the environment is an increase of harmful ultraviolet (UV) radiation on the Earth surface and in the upper ocean. This implies the importance of environmental UV monitoring. Since the direct global monitoring is not currently possible, indirect estimations of surface UV levels may be used based on satellite ozone data (Madronich, S. 1992). Total Ozone Mapping Spectrometer (TOMS) on board the METEOR-3 satellite provided regular set of data for such estimates. During the time of its operation (August, 1991 - December, 1994) the instrument registered several ozone hole events over Antarctica, when ozone levels dropped by as much as 60 % from their unperturbed values. Probably even more alarming ozone depletions were observed over highly populated regions of middle latitudes of northern hemisphere. Radiative transfer modeling was used to convert METEOR-3/TOMS daily ozone values into regional and global maps of biologically active UV. Calculations demonstrate the effect on surface UV levels produced by ozone hole over Antarctica and ozone depletions over the territory of Russia (March, 1994). UV contour lines deviate from the normal appearance which is determined by growing southward solar elevation. UV contour lines are almost perpendicular to the ozone ones in the ozone depletions areas. The 30 % ozone depletion, over Siberia caused more than 30 % increase in noontime erythemal UV levels, which is equivalent to 10-15 degrees southward latitude displacement. Higher UV radiation increases were found in ozone hole over South America (October 1992) equivalent to about 20 degrees southward displacement

  5. ADE Spectral Networks and Decoupling Limits of Surface Defects

    CERN Document Server

    Longhi, Pietro

    2016-01-01

    We study vacua and BPS spectra of canonical surface defects of class $\\mathcal{S}$ theories in different decoupling limits using ADE spectral networks. In some regions of the IR moduli spaces of these 2d-4d systems, the mixing between 2d and 4d BPS states is suppressed, and the spectrum of 2d-4d BPS states becomes that of a 2d $\\mathcal{N}=(2,2)$ theory. For some decoupling limits, we identify the 2d theories describing the surface defects with nonlinear sigma models and coset models that have been previously studied. We also study certain cases where the decoupling limit of a surface defect exhibits a set of vacua and a BPS spectrum that appear to be entirely new. A detailed analysis of these spectra and their wall-crossing behavior is performed.

  6. ADE spectral networks and decoupling limits of surface defects

    Science.gov (United States)

    Longhi, Pietro; Park, Chan Y.

    2017-02-01

    We study vacua and BPS spectra of canonical surface defects of class S theories in different decoupling limits using ADE spectral networks. In some regions of the IR moduli spaces of these 2d-4d systems, the mixing between 2d and 4d BPS states is suppressed, and the spectrum of 2d-4d BPS states becomes that of a 2d N = (2, 2) theory. For some decoupling limits, we identify the 2d theories describing the surface defects with nonlinear sigma models and coset models that have been previously studied. We also study certain cases where the decoupling limit of a surface defect exhibits a set of vacua and a BPS spectrum that appear to be entirely new. A detailed analysis of these spectra and their wall-crossing behavior is performed.

  7. UV Spectral Analysis of the Chemical Modification and Photolysis of Acetylacetone Modified Alumina Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    Chengbin JING; Xiujian ZHAO; Haizheng TAO; Xina WANG; Aiyun LIU

    2004-01-01

    Acetylacetone was firstly introduced into the aqueous media with the presence of aluminum sec-butoxide and peptizator. It was confirmed that the UV (ultraviolet) absorption band of acetylacetone underwent 14 nm of red-shift due to the formation of the six-membered ring of the complex between alumina and acetylacetone in the aqueous solution. It was also found that the chemical modification can be dissociated by the UV irradiation with a wavelength shorter than 286 nm as a result of the excitation of π-π* transition in the complex.

  8. Spectral and surface investigations of Ca{sub 2}V{sub 2}O{sub 7}:Eu{sup 3+} nanophosphors prepared by citrate-gel combustion method: a potential red-emitting phosphor for near-UV light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vinay [Shri Mata Vaishno Devi University, School of Physics, Katra, J and K (India); University of the Free State, Department of Physics, P.O. Box 339, Bloemfontein (South Africa); Bedyal, A.K.; Sharma, J. [Shri Mata Vaishno Devi University, School of Physics, Katra, J and K (India); Kumar, V.; Ntwaeaborwa, O.M.; Swart, H.C. [University of the Free State, Department of Physics, P.O. Box 339, Bloemfontein (South Africa)

    2014-09-15

    In the present work, red-emitting Ca{sub 2}V{sub 2}O{sub 7}:xEu{sup 3+} (x = 0.5-6.0 mol%) nanophosphors, in the form of powders, were synthesized by the citrate-gel combustion method using metal nitrates as precursors and citric acid as fuel. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy, photoluminescence (PL) and cathodoluminescence (CL) spectroscopy were used to study the structure, morphology and spectral properties of the samples. The chemical compositions and electronic states of the powders were analyzed with X-ray photoelectron spectroscopy. The average crystallite sizes estimated using the XRD data were found to be in the range of 30-45 nm, and were cross verified by TEM. The lattice parameters determined by the POWD program were approximated as a = 7.242 Aa, b = 6.674 Aa, c = 6.932 Aa and V = 291.24 Aa{sup 3}, respectively. Under UV (395 nm) (PL) and electron (CL) excitation, the nanophosphors show characteristic emission from the Eu{sup 3+} ion ({sup 5}D{sub 0} → {sup 7}F{sub j}, j = 1-5) with the main peaks at 612 and 616 nm. The maximum emission intensity was recorded from the sample with an Eu{sup 3+} concentration of 4 mol% and a critical energy distance of 19.084 Aa between the donor and the acceptor. Above this concentration, there was a reduction in the intensity due to dipole-dipole induced concentration quenching effects. The potential applications of this phosphor as a high color-purity phosphor in light-emitting diodes are evaluated. (orig.)

  9. Spectral UV measurements in Austria from 1994 to 2006: investigations of short- and long-term changes

    Directory of Open Access Journals (Sweden)

    S. Simic

    2008-12-01

    Full Text Available The influence of variability of atmospheric parameters on short- and long-term changes of spectral UV irradiance measured at the Sonnblick observatory (47.03° N, 12.57° E, 3106 m during the period from 1994 to 2006 is studied. Measurements were performed with the Brewer #093 single-monochromator spectrophotometer and with a Bentham DM 150 spectroradiometer (double-monochromator.

    The influence of ozone, albedo, snowline and clouds on UV variability is evaluated for each parameter separately using 10-year climatology. It is found that the effect of total ozone on short-term variability of UV irradiance at 305 nm can be more than 200% and on average more than 50%. Clouds can cause variability of 150% or more and on average 35%. Variability caused by albedo reaches a maximum of 32% in April (6% on average. In summer and autumn, total ozone and clouds strongly influence the variability of UV radiation, whereas in winter and spring ozone has the more pronounced effect. A decrease in snowline height from 3000 m to 800 m a.s.l. enhances the UV irradiance by a factor of 1.24 for clear sky conditions and by a factor of 1.7 for 8/8 cloud cover.

    Long-term trends are investigated for the time period from 1994 to 2006 based on clear-sky measurements, using the non-parametric Mann-Kendall trend test. Significant downward trends (99% confidence level are found for solar zenith angle 55° at wavelengths from 305 nm to 324 nm and erythemally weighted irradiance according to CIE, which are caused by an increase in sunshine duration during periods of high total column ozone. Significant trends (90% confidence level were also found for other combinations of wavelength and SZA.

  10. Spectral purity enhancement for the EUV Lithography Systems by suppressing UV reflection from multilayers

    NARCIS (Netherlands)

    Huang, Qiushi; de Boer, Meint J.; Barreaux, J.L.P.; Paardekooper, D.M.; van den Boogaard, Toine; van de Kruijs, Robbert Wilhelmus Elisabeth; Zoethout, E.; Louis, Eric; Bijkerk, Frederik; Wood, O.R.; Panning, E.M.

    2014-01-01

    Plasma based radiation sources optimized to emit 13.5 nm Extreme UV radiation also produce a significant amount of light at longer wavelengths. This so called out-of-band (OoB) radiation is detrimental for the imaging capabilities of an EUV lithographic imaging system, particularly the ultraviolet

  11. Constraints on the Early Terrestrial Surface UV Environment Relevant to Prebiotic Chemistry

    CERN Document Server

    Ranjan, Sukrit

    2016-01-01

    The UV environment is a key boundary condition for the origin of life. However, considerable uncertainty exists as to planetary conditions and hence surface UV at abiogenesis. Here, we present two-stream multi-layer clear-sky calculations of the UV surface radiance on Earth at 3.9 Ga to constrain the UV surface fluence as a function of albedo, solar zenith angle (SZA), and atmospheric composition. Variation in albedo and latitude (through SZA) can affect maximum photoreaction rates by a factor of >10.4; for the same atmosphere, photoreactions can proceed an order of magnitude faster at the equator of a snowball Earth than at the poles of a warmer world. Surface conditions are important considerations when computing prebiotic UV fluences. For climatically reasonable levels of CO2, fluence shortward of 189 nm is screened out, meaning that prebiotic chemistry is robustly shielded from variations in UV fluence due to solar flares or variability. Strong shielding from CO2 also means that the UV surface fluence is ...

  12. Quantitative characterization of surface topography using spectral analysis

    Science.gov (United States)

    Jacobs, Tevis D. B.; Junge, Till; Pastewka, Lars

    2017-03-01

    Roughness determines many functional properties of surfaces, such as adhesion, friction, and (thermal and electrical) contact conductance. Recent analytical models and simulations enable quantitative prediction of these properties from knowledge of the power spectral density (PSD) of the surface topography. The utility of the PSD is that it contains statistical information that is unbiased by the particular scan size and pixel resolution chosen by the researcher. In this article, we first review the mathematical definition of the PSD, including the one- and two-dimensional cases, and common variations of each. We then discuss strategies for reconstructing an accurate PSD of a surface using topography measurements at different size scales. Finally, we discuss detecting and mitigating artifacts at the smallest scales, and computing upper/lower bounds on functional properties obtained from models. We accompany our discussion with virtual measurements on computer-generated surfaces. This discussion summarizes how to analyze topography measurements to reconstruct a reliable PSD. Analytical models demonstrate the potential for tuning functional properties by rationally tailoring surface topography—however, this potential can only be achieved through the accurate, quantitative reconstruction of the PSDs of real-world surfaces.

  13. Multispectral UV imaging for surface analysis of MUPS tablets with special focus on the pellet distribution

    DEFF Research Database (Denmark)

    Novikova, Anna; Carstensen, Jens Michael; Rades, Thomas

    2016-01-01

    In the present study the applicability of multispectral UV imaging in combination with multivariate image analysis for surface evaluation of MUPS tablets was investigated with respect to the differentiation of the API pellets from the excipients matrix, estimation of the drug content as well as p...... image analysis is a promising approach for the automatic quality control of MUPS tablets during the manufacturing process.......In the present study the applicability of multispectral UV imaging in combination with multivariate image analysis for surface evaluation of MUPS tablets was investigated with respect to the differentiation of the API pellets from the excipients matrix, estimation of the drug content as well...... on the tablet surface allowed an estimation of the true drug content in the respective MUPS tablet. In addition, the pellet distribution in the MUPS formulations could be estimated by UV image analysis of the tablet surface. In conclusion, this study revealed that UV imaging in combination with multivariate...

  14. Depolarization effect in rare-earth doped Y{sub 2}O{sub 3} films in blue and UV spectral range

    Energy Technology Data Exchange (ETDEWEB)

    Gasimov, Naghi; Mammadov, Eldar; Babayev, Sardar; Mamedova, Irada; Mamedov, Nazim [Department of Ellipsometry, Institute of Physics, Azerbaijan National Academy of Sciences, H. Javid ave. 33, Baku-1143 (Azerbaijan); Joudrier, Anne L.; Andriamiadamanana, Christian; Naghavi, Negar; Guillemoles, Jean F. [Institute for Research and Development of Photovoltaic Energy, 6 Quai Watier, 78401 Chatou, Paris (France)

    2015-06-15

    The 200 to 300 nm thick, Er and Er,Yb doped Y{sub 2}O{sub 3} films deposited onto silicon substrate by spin coating have been studied by spectroscopic ellipsometry over the 192-1680 nm spectral range at room temperature. All samples have been found to be strongly depolarizing in the blue and UV part of the spectrum. Complimentary examination of the sample surfaces, using confocal photoluminescence microscopy has disclosed the non-uniform distribution of the rare-earth dopants. The depolarization effects have then been modeled and found to be best reproduced by taking the thickness non-uniformity as the main source of depolarization. The optical constants of the studied films have been determined after four-step modeling with sequential decrease of the mean square error. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Spatial resolution in thin film deposition on silicon surfaces by combining silylation and UV/ozonolysis

    Science.gov (United States)

    Guo, Lei; Zaera, Francisco

    2014-12-01

    A simple procedure has been developed for the processing of silicon wafers in order to facilitate the spatially resolved growth of thin solid films on their surfaces. Specifically, a combination of silylation and UV/ozonolysis was tested as a way to control the concentration of the surface hydroxo groups required for subsequent atomic layer deposition (ALD) of metals or oxides. Water contact angle measurements were used to evaluate the hydrophilicity/hydrophobicity of the surface, a proxy for OH surface coverage, and to optimize the UV/ozonolysis treatment. Silylation with hexamethyldisilazane, trichloro(octadecyl)silane, or trimethylchlorosilane was found to be an efficient way to block the hydroxo sites and to passivate the underlying surface, and UV/O3 treatments were shown to effectively remove the silylation layer and to regain the surface reactivity. Both O3 and 185 nm UV radiation were determined necessary for the removal of the silylation layer, and additional 254 nm radiation was found to enhance the process. Attenuated total reflection-infrared absorption spectroscopy was employed to assess the success of the silylation and UV/O3 removal steps, and atomic force microscopy data provided evidence for the retention of the original smoothness of the surface. Selective growth of HfO2 films via TDMAHf + H2O ALD was seen only on the UV/O3 treated surfaces; total inhibition of the deposition was observed on the untreated silylated surfaces (as determined by x-ray photoelectron spectroscopy and ellipsometry). Residual film growth was still detected on the latter if the ALD was carried out at high temperatures (250 °C), because the silylation layer deteriorates under such harsh conditions and forms surface defects that act as nucleation sites for the growth of oxide grains (as identified by electron microscopy and scanning electron microscopy). We believe that the silylation-UV/O3 procedure advanced here could be easily implemented for the patterning of surfaces

  16. Spectral, structural, optical and dielectrical studies of UV irradiated Rose Bengal thin films prepared by spin coating technique

    Energy Technology Data Exchange (ETDEWEB)

    Zeyada, H.M., E-mail: hzeyada@gmail.com [Department of Physics, Faculty of Science at New Damietta, University of Damietta, 34517 (Egypt); Youssif, M.I.; El-Ghamaz, N.A. [Department of Physics, Faculty of Science at New Damietta, University of Damietta, 34517 (Egypt); Aboderbala, M.E.O. [Department of Physics, Faculty of Science at New Damietta, University of Damietta, 34517 (Egypt); Department of Physics, Faculty of Science, AlJabl Al Gharbi University (Libya)

    2017-02-01

    Optical properties of pristine and UV irradiated Rose Bengal (RB) films have been investigated using transmittance and reflectance methods. The refractive index(n) and extinction coefficient (k) have been calculated from the absolute values of transmission and reflection spectrum. Single oscillator parameters and Drude model of free carrier absorption have been applied for analysis of the refractive index dispersion. Within the frame work of the band-to-band electron transitions theory; the fundamental absorption edge data were analyzed. Our results suggest that thickness of RB films has no effect on the absorption or the refractive indices in the investigated thicknesses range and within the experimental error. Structural transformation of films from amorphous to polycrystalline has been observed upon UV irradiation. Accordingly, the decreases of all of the absorption coefficient, the energy gap and the refractive index of RB films have been detected. Furthermore, the dependence of the optical functions on UV exposure times has been discussed based on the spectral distribution of the dielectric constant.

  17. Spectral, structural, optical and dielectrical studies of UV irradiated Rose Bengal thin films prepared by spin coating technique

    Science.gov (United States)

    Zeyada, H. M.; Youssif, M. I.; El-Ghamaz, N. A.; Aboderbala, M. E. O.

    2017-02-01

    Optical properties of pristine and UV irradiated Rose Bengal (RB) films have been investigated using transmittance and reflectance methods. The refractive index(n) and extinction coefficient (k) have been calculated from the absolute values of transmission and reflection spectrum. Single oscillator parameters and Drude model of free carrier absorption have been applied for analysis of the refractive index dispersion. Within the frame work of the band-to-band electron transitions theory; the fundamental absorption edge data were analyzed. Our results suggest that thickness of RB films has no effect on the absorption or the refractive indices in the investigated thicknesses range and within the experimental error. Structural transformation of films from amorphous to polycrystalline has been observed upon UV irradiation. Accordingly, the decreases of all of the absorption coefficient, the energy gap and the refractive index of RB films have been detected. Furthermore, the dependence of the optical functions on UV exposure times has been discussed based on the spectral distribution of the dielectric constant.

  18. Constraints on the Early Terrestrial Surface UV Environment Relevant to Prebiotic Chemistry

    Science.gov (United States)

    Ranjan, Sukrit; Sasselov, Dimitar D.

    2017-03-01

    The UV environment is a key boundary condition to abiogenesis. However, considerable uncertainty exists as to planetary conditions and hence surface UV at abiogenesis. Here, we present two-stream multilayer clear-sky calculations of the UV surface radiance on Earth at 3.9 Ga to constrain the UV surface fluence as a function of albedo, solar zenith angle (SZA), and atmospheric composition. Variation in albedo and latitude (through SZA) can affect maximum photoreaction rates by a factor of >10.4; for the same atmosphere, photoreactions can proceed an order of magnitude faster at the equator of a snowball Earth than at the poles of a warmer world. Hence, surface conditions are important considerations when computing prebiotic UV fluences. For climatically reasonable levels of CO2, fluence shortward of 189 nm is screened out, meaning that prebiotic chemistry is robustly shielded from variations in UV fluence due to solar flares or variability. Strong shielding from CO2 also means that the UV surface fluence is insensitive to plausible levels of CH4, O2, and O3. At scattering wavelengths, UV fluence drops off comparatively slowly with increasing CO2 levels. However, if SO2 and/or H2S can build up to the ≥1-100 ppm level as hypothesized by some workers, then they can dramatically suppress surface fluence and hence prebiotic photoprocesses. H2O is a robust UV shield for λ atmospheric gases, fluence ≲198 nm is only available for cold, dry atmospheres, meaning sources with emission ≲198 (e.g., ArF excimer lasers) can only be used in simulations of cold environments with low abundance of volcanogenic gases. On the other hand, fluence at 254 nm is unshielded by H2O and is available across a broad range of NCO2, meaning that mercury lamps are suitable for initial studies regardless of the uncertainty in primordial H2O and CO2 levels.

  19. UV and x-ray spectral lines of FeXXIII ion for plasma diagnostics

    CERN Document Server

    Murakami, I; Murakami, Izumi; Kato, Takako

    1996-01-01

    We have calculated X-ray and UV spectra of Be-like Fe (FeXXIII) ion in collisional-radiative model including all fine-structure transitions among the 2s^2, 2s2p, 2p^2, 2snl, and 2pnl levels where n=3 and 4, adopting data for the collision strengths by Zhang & Sampson (1992) and by Sampson, Goett, & Clark (1984). Some line intensity ratios can be used for the temperature diagnostics. We show 5 ratios in UV region and 9 ratios in X-ray region as a function of electron temperature and density at 0.3keV < T_e < 10keV and n_e = 1 - 10^{25} cm^{-3}. The effect of cascade in these line ratios and in the level population densities are discussed.

  20. LADEE UVS (UltraViolet Visible Spectrometer) and the Search for Lunar Exospheric Dust: A Detailed Spectral Analysis

    Science.gov (United States)

    Wooden, Diane H.; Cook, Amanda; Colaprete, Anthony; Shirley, Mark; Vargo, Kara; Elphic, Richard C.; Hermalyn, Brendan; Stubbs, Timothy John; Glenar, David A.

    2014-01-01

    The Lunar Atmosphere and Dust Environment Explorer (LADEE) executed science observations in lunar orbit spanning 2013-Oct-16- 2014-04-18 UT. LADEE's Ultraviolet/Visible Spectrometer (UVS) studies the composition and temporal variations of the tenuous lunar exosphere and dust environment, utilizing two sets of optics: a limb-viewing telescope, and a solar-viewer. The limb-viewing telescope observes illuminated dust and emitting gas species while the Sun is just behind the lunar limb. The solar viewer, with its diffuser, allows UVS to also stare directly at the solar disk as it approaches the limb, sampling progressively lower exosphere altitudes. Solar viewer "Occultation" activities occur at the lunar sunrise limb, as the LADEE spacecraft passes into the lunar night side, facing the Sun (the spacecraft orbit is near-equatorial retrograde). A loss of transmission of sunlight occurs by the occultation of dust grains along the line-of-sight. So-called "Inertial Limb" activities have the limb-viewing telescope pointed at the lit exosphere just after the Sun has set. Inertial Limb activities follow a similar progression of diminishing sampling altitudes but hold the solar elongation angle constant so the zodiacal light contribution remains constant while seeking to observe the weak lunar horizon glow. On the dark side of the moon, "Sodium Tail" activities pointed the limb-viewing telescope in the direction of the Moon's sodium tail (similar to anti-sunward), during different lunar phases. Of the UVS data sets, these show the largest excess of scattered blue light, indicative of the presence of small (approximately 100 nm) dust grains in the tail. Correlations are sought between dust in the sodium tail and meteor streams and magnetotail crossings to investigate impact- versus electrostatic-lofting. Once lofted, nanoparticles can become charged and picked up by the solar wind. The LADEE UVS Occultation, Inertial Limb, and Sodium Tail spectral datasets provide evidence of

  1. UV-B辐射胁迫下杨梅幼苗的高光谱响应%High-spectral responses of Myrica rubra seedlings to UV-B radiation stress

    Institute of Scientific and Technical Information of China (English)

    金鑫杰; 江洪; 陈健; 时启龙; 张倩倩

    2012-01-01

    A simulated field experiment with three treatments, i. e. , ambient light ( control) , reduced UV-B radiation, and enhanced UV-B radiation, was conducted to evaluate the effects of solar ultraviolet ( UV-B) radiation on the seedlings of Myrica rubra, a typical woody species in subtropical region. The leaf chlorophyll content, spectral reflectance and spectral characteristic parameters were measured and analyzed. As compared with the control, enhanced UV-B radiation decreased the seedling chlorophyll content while reduced UV-B radiation significantly increased the chlorophyll content, and these effects reflected in the spectral reflectance. Under the effects of the three gradients of UV-B radiation, the differences in the reflectance at visible region mainly occurred around the green peak and red edge on the reflectance curve, and the peak wavelength of the red edge shifted to longer wavelength. Enhanced UV-B radiation had an accumulated temporal effect on M. rubra. The inverted-Gaussian model parameters R0, λ0, λp, Rs, and 6 were the useful guides to reveal the spectral responses of M. rubra seedlings under UV-B radiation stress, among which, R8 performed the best. The differences in the spectral reflectance under different UV-B radiation levels could be effectively distinguished with the vegetation indices composed of the spectral reflectance of narrow wave bands or the reflectance at specific wavelengths.%设置UV-B滤光减弱、UV-B辐射增强和自然光(对照)3组模拟大田试验,比较了不同UV-B辐射处理下,亚热带典型木本植物杨梅幼苗的叶绿素含量、光谱反射率及光谱特征参数,研究UV-B辐射变化对亚热带森林树种的影响.结果表明:增强UV-B辐射可降低杨梅幼苗的叶绿素含量,而降低辐射则会显著促进叶绿素的增加,并且这种胁迫反应于光谱反射率中.3种不同梯度UV-B辐射作用下,可见光部分光谱反射率间的差异主要集中在绿光反射峰及红边附近,

  2. Interaction of UV-Laser Radiation with Molecular Surface Films.

    Science.gov (United States)

    2014-09-26

    physics of organometallics on surfaces and in the gas phase, and the first observation of surface enhanced chemistry . DI ~(B ~ _ __ _ __ _ ___E_ _ 20...reverse if nee~tary an~d Identify by biock number) FIEL GROP SU GR- Laser, Microelectronics, Surface Chemistry 19 ABSTRACT i CoiEIDue on reverset of...eke chmry and iden NlY by bloch numberg -he surface chemistry of Laser Photodeposition has been explored. The findings include the photodissociation

  3. Extensive reduction of surface UV radiation since 1750 in world's populated regions

    Directory of Open Access Journals (Sweden)

    M. M. Kvalevåg

    2009-10-01

    Full Text Available Human activity influences a wide range of components that affect the surface UV radiation levels, among them ozone at high latitudes. We calculate the effect of human-induced changes in the surface erythemally weighted ultra-violet radiation (UV-E since 1750. We compare results from a radiative transfer model to surface UV-E radiation for year 2000 derived by satellite observations (from Total Ozone Mapping Spectroradiometer and to ground based measurements at 14 sites. The model correlates well with the observations; the correlation coefficients are 0.97 and 0.98 for satellite and ground based measurements, respectively. In addition to the effect of changes in ozone, we also investigate the effect of changes in SO2, NO2, the direct and indirect effects of aerosols, albedo changes and aviation-induced contrails and cirrus. The results show an increase of surface UV-E in polar regions, most strongly in the Southern Hemisphere. Furthermore, our study also shows an extensive surface UV-E reduction over most land areas; a reduction up to 20% since 1750 is found in some industrialized regions. This reduction in UV-E over the industrial period is particularly large in highly populated regions.

  4. Impact of UV/ozone surface treatment on AlGaN/GaN HEMTs

    Institute of Scientific and Technical Information of China (English)

    Yuan Tingting; Liu Xinyu; Zheng Yingkui; Li Chengzhan; Wei Ke; Liu Guoguo

    2009-01-01

    Surface treatment plays an important role in the process of making high performance AIGaN/GaN HEMTs. A clean surface is critical for enhancing device performance and long-term reliability. By experiment-ing with different surface treatment methods, we find that using UV/ozone treatment significantly influences the electrical properties of Ohmic contacts and Schottky contacts. According to these experimental phenomena and X-ray photoelectron spectroscopy surface analysis results, the effect of the UV/ozone treatment and the reason that it influences the Ohmic/Schottky contact characteristics of A1GaN/GaN HEMTs is investigated.

  5. Similarities and Differences in Spectral Behavior Between W Ser and UX Mon in the UV

    Science.gov (United States)

    Bobrowsky, Matthew; Sanad, M. R.

    2012-01-01

    We present ultraviolet spectra of two eclipsing interacting binary systems, W Ser and UX Mon. The data contain good coverage over the 14.16-day and 5.9-day orbital periods, respectively, using observations taken by the International Ultraviolet Explorer (IUE) during periods between 1978 - 1993 and 1981 - 1991 for the two systems respectively. Two profiles of both W Ser and UX Mon showing variations of line fluxes at two orbital phases are presented. We investigated the N V emission line at 1240 Å, C II emission line at 1336 Å, C IV emission line at 1550 Å, O III emission line at 1666 Å, and Si III emission line at 1892 Å (which are produced in an extended gaseous envelope around the mass-gaining component), by calculating the line fluxes of these spectral lines. Our results show that there are spectral variations of line fluxes at different orbital phases, correlated with the light curves found for both W Ser and UX Mon. We attribute these spectral variations to effects from the eclipse and to variations in the mass transfer rate. M.B. acknowledges support from NASA, through grant number HST-AR-10304.04-A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  6. Europa: Characterization and interpretation of global spectral surface units

    Science.gov (United States)

    Nelson, M.L.; McCord, T.B.; Clark, R.N.; Johnson, T.V.; Matson, D.L.; Mosher, J.A.; Soderblom, L.A.

    1986-01-01

    The Voyager global multispectral mosaic of the Galilean satellite Europa (T. V. Johnson, L. A. Soderblom, J. A. Mosher, G. E. Danielson, A. F. Cook, and P. Kupferman, 1983, J. Geophys. Res. 88, 5789-5805) was analyzed to map surface units with similar optical properties (T. B. McCord, M. L. Nelson, R. N. Clark, A. Meloy, W. Harrison, T. V. Johnson, D. L. Matson, J. A. Mosher, and L. Soderblom, 1982, Bull Amer. Astron. Soc. 14, 737). Color assignments in the unit map are indicative of the spectral nature of the unit. The unit maps make it possible to infer extensions of the geologic units mapped by B. K. Lucchitta and L. A. Soderblom (1982, in Satellites of Jupiter, pp. 521-555, Univ. of Arizona Press, Tucson) beyond the region covered in the high-resolution imagery. The most striking feature in the unit maps is a strong hemispheric asymmetry. It is seen most clearly in the ultraviolet/violet albedo ratio image, because the asymmetry becomes more intense as the wavelength decreases. It appears as if the surface has been darkened, most intensely in the center of the trailing hemisphere and decreasing gradually, essentially as the cosine of the angle from the antapex of motion, to a minimum in the center of the leading hemisphere. The cosine pattern suggests that the darkening is exogenic in origin and is interpreted as evidence of alteration of the surface by ion bombardment from the Jovian magnetosphere. ?? 1986.

  7. Polarized spectral combs probe optical fiber surface plasmons.

    Science.gov (United States)

    Caucheteur, Christophe; Voisin, Valérie; Albert, Jacques

    2013-02-11

    The high-order cladding modes of conventional single mode fiber come in semi-degenerate pairs corresponding to mostly radially or mostly azimuthally polarized light. Using tilted fiber Bragg gratings to excite these mode families separately, we show how plasmonic coupling to a thin gold coating on the surface of the fiber modifies the effective indices of the modes differently according to polarization and to mode order. In particular, we show the existence of a single "apolarized" grating resonance, with equal effective index for all input polarization states. This special resonance provides direct evidence of the excitation of a surface plasmon on the metal surface but also an absolute wavelength reference that allows for the precise localization of the most sensitive resonances in refractometric and biochemical sensing applications. Two plasmon interrogation methods are proposed, based on wavelength and amplitude measurements. Finally, we use a biotin-streptavidin biomolecular recognition experiment to demonstrate that differential spectral transmission measurements of a fine comb of cladding mode resonances in the vicinity of the apolarized resonance provide the most accurate method to extract information from plasmon-assisted Tilted fiber Bragg gratings, down to pM concentrations and at least 10(-5) refractive index changes.

  8. Mechanistic study for immobilization of cysteine-labeled oligopeptides on UV-activated surfaces.

    Science.gov (United States)

    Ong, Lian Hao; Ding, Xiaokang; Yang, Kun-Lin

    2014-10-01

    In this study, we report immobilization of cysteine-labeled oligopeptides on UV activated surfaces decorated with N,N-dimethyl-n-octadecyl-3-aminopropyltrimethoxysilyl chloride (DMOAP). Our result shows that cysteine group, regardless of its position in the oligopeptide, is essential for successful immobilization of oligopeptide on the UV-activated surface. A possible reaction mechanism is nucleophilic addition of thiolates to surface aldehyde groups generated during UV activation. By using this technique, we are able to incorporate anchoring points into oligopeptides through cysteine residues. Furthermore, immobilized oligopeptides on the UV-activated surface is very stable even under harsh washing conditions. Finally, we show that an HPQ-containing oligopeptide can be immobilized on the UV-activated surface, but the final surface density and its ability to bind streptavidin are affected by the position of cysteine and HPQ. An oligopeptide with a cysteine at the N-terminus and a HPQ motif at the C-terminus gives the highest binding signal in the streptavidin-binding assay. This result is potentially useful for the development of functional oligopeptide microarrays for detecting target protein molecules.

  9. Directional uv photoemission from (100) and (110) molybdenum surfaces

    DEFF Research Database (Denmark)

    Cinti, R. C.; Khoury, E. Al; Chakraverty, B. K.;

    1976-01-01

    A study of the (100) and (110) molybdenum surfaces by directional photoemission spectroscopy is presented. Energy distribution spectra formed by photoelectrons emitted normal to the surfaces have been measured for photon energies between 10.2 and 21.2 eV. The results are discussed in terms of cal...

  10. Wettability modification of human tooth surface by water and UV and electron-beam radiation

    Energy Technology Data Exchange (ETDEWEB)

    Tiznado-Orozco, Gaby E., E-mail: gab0409@gmail.com [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Unidad Académica de Odontología, Universidad Autónoma de Nayarit, Edificio E7, Ciudad de la Cultura “Amado Nervo”, C.P. 63190 Tepic, Nayarit (Mexico); Reyes-Gasga, José, E-mail: jreyes@fisica.unam.mx [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Instituto de Física, UNAM, Circuito de la Investigación s/n, Ciudad Universitaria, 04510 Coyoacan, México, D.F. (Mexico); Elefterie, Florina, E-mail: elefterie_florina@yahoo.com [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Beyens, Christophe, E-mail: christophe.beyens@ed.univ-lille1.fr [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Maschke, Ulrich, E-mail: Ulrich.Maschke@univ-lille1.fr [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Brès, Etienne F., E-mail: etienne.bres@univ-lille1.fr [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France)

    2015-12-01

    The wettability of the human tooth enamel and dentin was analyzed by measuring the contact angles of a drop of distilled water deposited on the surface. The samples were cut along the transverse and longitudinal directions, and their surfaces were subjected to metallographic mirror-finish polishing. Some samples were also acid etched until their microstructure became exposed. Wettability measurements of the samples were done in dry and wet conditions and after ultraviolet (UV) and electron beam (EB) irradiations. The results indicate that water by itself was able to increase the hydrophobicity of these materials. The UV irradiation momentarily reduced the contact angle values, but they recovered after a short time. EB irradiation raised the contact angle and maintained it for a long time. Both enamel and dentin surfaces showed a wide range of contact angles, from approximately 10° (hydrophilic) to 90° (hydrophobic), although the contact angle showed more variability on enamel than on dentin surfaces. Whether the sample's surface had been polished or etched did not influence the contact angle value in wet conditions. - Highlights: • Human tooth surface wettability changes in dry/wet and UV/EB radiation conditions. • More variability in contact angle is observed on enamel than on dentin surfaces. • Water by itself increases the hydrophobicity of the human tooth surface. • UV irradiation reduces momentarily the human tooth surface hydrophobicity. • EB irradiation increases and maintains the hydrophobicity for a long time.

  11. Optical injection and spectral filtering of high-power UV laser diodes

    CERN Document Server

    Schäfer, V M; Tock, C J; Lucas, D M

    2015-01-01

    We demonstrate injection-locking of 120mW laser diodes operating at 397nm. We achieve stable operation with injection powers of ~100uW and a slave laser output power of up to 110mW. We investigate the spectral purity of the slave laser light via photon scattering experiments on a single trapped Ca40 ion. We show that it is possible to achieve a scattering rate indistinguishable from that of monochromatic light by filtering the laser light with a diffraction grating to remove amplified spontaneous emission.

  12. Choice of Eye-Safe Radiation Wavelength in UV and Near IR Spectral Bands for Remote Sensing

    Directory of Open Access Journals (Sweden)

    M. L. Belov

    2016-01-01

    Full Text Available The introduction of laser remote sensing systems carries a particular risk to the human’s sense of vision. A structure of the eye, and especially the retina, is the main critical organ as related to the laser radiation.The work uses the optical models of the atmosphere, correctly working in both the UV and the near-IR band, to select the eye-safe radiation wavelengths in the UV (0.355 m and near-IR (~ 1.54 and ~ 2 m spectral bands from the point of view of recorded lidar signal value to fulfill the tasks of laser sensing the natural formations and laser aerosol sensing in the atmosphere.It is shown that the remote sensing lasers with appropriate characteristics can be selected both in the UV band (at a wavelength of 0.355 μm and in the near-IR band (at wavelengths of 1.54 ~ or ~ 2 μm.Molecular scattering has its maximum (for the selected wavelength at a wavelength of 0.355 μm in the UV band, and the minimum at the wavelengths of 1.54 and 2.09 μm in the near -IR band. The main contribution to the molecular absorption at a wavelength of 0.355 μm is made by ozone. In the near-IR spectral band the radiation is absorbed due to water vapor and carbon dioxide.Calculations show that the total effect of the molecular absorption and scattering has no influence on radiation transmission for both the wavelength of 0.355 μm in the UV band, and the wavelengths of 1.54 and 2.09 μm in the near-IR band for sensing trails ~ 1 km.One of the main factors of laser radiation attenuation in the Earth's atmosphere is radiation scattering by aerosol particles.The results of calculations at wavelengths of 0.355 μm, 1.54 μm and 2.09 μm for the several models of the atmosphere show that a choice of the most effective (in terms of the recorded signal of lidar and eye-safe radiation wavelength depends strongly on the task of sensing.To fulfill the task of laser sensing the natural formations, among the eye-safe wavelengths there is one significantly advantageous

  13. Optical properties in the UV and visible spectral region of organic acids relevant to tropospheric aerosols

    Directory of Open Access Journals (Sweden)

    C. E. Lund Myhre

    2004-06-01

    Full Text Available Refractive and absorption indices in the UV and visible region of selected aqueous organic acids relevant to tropospheric aerosols are reported. The acids investigated are the aliphatic dicarboxylic acids oxalic, malonic, tartronic, succinic and glutaric acid. In addition we report data for pyruvic, pinonic, benzoic and phthalic acid. To cover a wide range of conditions we have investigated the aqueous organic acids at different concentrations spanning from highly diluted samples to concentrations close to saturation. The density of the investigated samples is reported and a parameterisation of the absorption and refractive index that allows the calculation of the optical constants of mixed aqueous organic acids at different concentrations is presented. The single scattering albedo is calculated for two size distributions using measured and a synthetic set of optical constants. The results show that tropospheric aerosols consisting of only these organic acids and water have a pure scattering effect.

  14. Optical properties in the UV and visible spectral region of organic acids relevant to tropospheric aerosols

    Directory of Open Access Journals (Sweden)

    C. E. Lund Myhre

    2004-01-01

    Full Text Available Refractive and absorption indices in the UV and visible region of selected aqueous organic acids relevant to tropospheric aerosols are reported. The acids investigated are the aliphatic dicarboxylic acids oxalic, malonic, tartronic, succinic and glutaric acid. In addition we report data for pyruvic, pinonic, benzoic and phthalic acid. To cover a wide range of conditions we have investigated the aqueous organic acids at different concentrations spanning from highly diluted samples to concentrations close to saturation. The density of the investigated samples is reported and a parameterisation of the absorption and refractive index that allows the calculation of the optical constants of mixed aqueous organic acids at different concentrations is presented. The single scattering albedo is calculated for two size distributions using measured and a synthetic set of optical constants. The results show that tropospheric aerosols consisting of only these organic acids and water have a pure scattering effect.

  15. A sensitive spectral survey of interstellar features in the near-UV [3050-3700{\\AA}

    CERN Document Server

    Bhatt, Neil Hemant

    2014-01-01

    We present a comprehensive and sensitive unbiased survey of interstellar features in the near-UV range (3050-3700 {\\AA}). We combined a large number of VLT/UVES archival observations of a sample of highly reddened early type stars -- typical diffuse interstellar band (DIB) targets -- and unreddened standards. We stacked the individual observations to obtain a reddened "superspectrum" in the interstellar rest frame with a signal-to-noise (S/N) ratio exceeding 1500. We compared this to the analogous geocentric and stellar rest frame superspectra as well as to an unreddened superspectrum to find interstellar absorption features. We find 30 known features (11 atomic and 19 molecular) and tentatively detect up to 7 new interstellar absorption lines of unknown origin. Our survey is sensitive to narrow and weak features; telluric residuals preclude us from detecting broader features. For each sightline, we measured fundamental parameters (radial velocities, line widths, and equivalent widths) of the detected interst...

  16. Influence of the surface structure on the filtration performance of UV-modified PES membranes

    DEFF Research Database (Denmark)

    Kæselev, Bozena Alicja; Kingshott, P.; Jonsson, Gunnar Eigil

    2002-01-01

    Poly (ether sulfone) (PES) 50 kDa membranes were surface modified by irradiation with UV light (254 nm) in the presence of N-vinyl-2-pyrrolidine (NVP), 2-acrylamidoglycolic acid monohydrate (AAG) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AAP). The surfaces of the modified membranes were c...

  17. UV SURFACE ENVIRONMENT OF EARTH-LIKE PLANETS ORBITING FGKM STARS THROUGH GEOLOGICAL EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Rugheimer, S.; Sasselov, D. [Harvard Smithsonian Center for Astrophysics, 60 Garden st., 02138 MA Cambridge (United States); Segura, A. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México (Mexico); Kaltenegger, L., E-mail: srugheimer@cfa.harvard.edu [Carl Sagan Institute, Cornell University, Ithaca, NY 14853 (United States)

    2015-06-10

    The UV environment of a host star affects the photochemistry in the atmosphere, and ultimately the surface UV environment for terrestrial planets and therefore the conditions for the origin and evolution of life. We model the surface UV radiation environment for Earth-sized planets orbiting FGKM stars in the circumstellar Habitable Zone for Earth through its geological evolution. We explore four different types of atmospheres corresponding to an early-Earth atmosphere at 3.9 Gyr ago and three atmospheres covering the rise of oxygen to present-day levels at 2.0 Gyr ago, 0.8 Gyr ago, and modern Earth. In addition to calculating the UV flux on the surface of the planet, we model the biologically effective irradiance, using DNA damage as a proxy for biological damage. We find that a pre-biotic Earth (3.9 Gyr ago) orbiting an F0V star receives 6 times the biologically effective radiation as around the early Sun and 3520 times the modern Earth–Sun levels. A pre-biotic Earth orbiting GJ 581 (M3.5 V) receives 300 times less biologically effective radiation, about 2 times modern Earth–Sun levels. The UV fluxes calculated here provide a grid of model UV environments during the evolution of an Earth-like planet orbiting a range of stars. These models can be used as inputs into photo-biological experiments and for pre-biotic chemistry and early life evolution experiments.

  18. UV light induced surface modification of HDPE films with bioactive compounds

    Energy Technology Data Exchange (ETDEWEB)

    Daniloska, Vesna; Blazevska-Gilev, Jadranka; Dimova, Vesna [Faculty of Technology and Metallurgy, University St. Cyril and Methodius, Ruger Boskovic 16, 1000 Skopje (Macedonia, The Former Yugoslav Republic of); Fajgar, Radek [Institute of Chemical Process Fundamentals, ASCR, Rozvojova 135, Prague 6-Suchdol (Czech Republic); Tomovska, Radmila, E-mail: radmila_tomovska@ehu.es [Institute for Polymer Materials, POLYMAT, Centro Joxe Mari Korta, University of the Basque Country, P.O. Box 1072, 20080 Donostia-San Sebastian (Spain); IKERBASQUE, Basque Foundation for Science, 48011 Bilbao (Spain)

    2010-01-15

    The development of different techniques for surface modification of polymers becomes popular in a last decade. These techniques preserve useful bulk polymer properties unchanged, while the activation of the polymer surface offers more possibilities for polymer applications. In this work, a new, one-step method for bio-activation of HDPE (high density polyethylene) surface by UV irradiation is presented. HDPE films coupled with selected active compound and a photoinitiator was treated by UV lamp, emitting light at 254 nm. For surface functionalization of HDPE films, the following compounds were employed: 2-aminopyridine (AP), N{sup 1}-(2-pyridylaminomethyl)-1,2,4-triazole (TA) and benzocaine (BC). The influence of irradiation time on the extent of surface changes was investigated. The modified polymer surfaces were investigated by Fourier transformed infrared (FTIR) and Raman spectroscopy, scanning electron microscopy (SEM) and contact angle measurements, demonstrating successful functionalization of HDPE surface.

  19. EFFECT OF UV LASER ON SPECTRAL PROPERTIES OF BORATE GLASSES DOPED WITH COPPER CHLORIDE NANOCRYSTALS

    Directory of Open Access Journals (Sweden)

    A. N. Babkina

    2017-01-01

    Full Text Available We present the results of the pulsed ultraviolet laser effect on the spectral properties of the potassium-aluminium-borate glasses doped with the copper chloride nanocrystals with the average size of 3.1-6.3 nm. We have studied the changes of the exciton absorption spectra of the CuCl nanocrystals induced by different duration of the laser exposure. The results show the possibility of the laser-induced crystallization and growth of the nanocrystals. For the first time the effect of the irreversible photochromism has been obtained in the potassium-aluminium-borate glasses doped with the copper chloride nanocrystals. The effect is associated with the formation of the temperature stable Cu0n colloidal color centers.

  20. UV-Induced Adenine Radicals Induced in DNA A-Tracts: Spectral and Dynamical Characterization.

    Science.gov (United States)

    Banyasz, Akos; Ketola, Tiia-Maaria; Muñoz-Losa, Aurora; Rishi, Sunny; Adhikary, Amitava; Sevilla, Michael D; Martinez-Fernandez, Lara; Improta, Roberto; Markovitsi, Dimitra

    2016-10-06

    Adenyl radicals generated in DNA single and double strands, (dA)20 and (dA)20·(dT)20, by one- and two-photon ionization by 266 nm laser pulses decay at 600 nm with half-times of 1.0 ± 0.1 and 4 ± 1 ms, respectively. Though ionization initially forms the cation radical, the radicals detected for (dA)20 are quantitatively identified as N6-deprotonated adenyl radicals by their absorption spectrum, which is computed quantum mechanically employing TD-DFT. Theoretical calculations show that deprotonation of the cation radical induces only weak spectral changes, in line with the spectra of the adenyl radical cation and the deprotonated radical trapped in low temperature glasses.

  1. Aluminum-induced changes in properties and fouling propensity of DOM solutions revealed by UV-vis absorbance spectral parameters.

    Science.gov (United States)

    Zhou, Minghao; Meng, Fangang

    2016-04-15

    The integration of pre-coagulation with ultrafiltration (UF) is expected to not only reduce membrane fouling but also improve natural organic matter (NOM) removal. However, it is difficult to determine the proper coagulant dosage for different water qualities. The objective of this study was to probe the potential of UV-vis spectroscopic analysis to reveal the coagulant-induced changes in the fouling potentials of dissolved organic matter (DOM) and to determine the optimal coagulant dosage. The Zeta potentials (ZPs) and average particle size of the four DOM solutions (Aldrich humic acid (AHA), AHA-sodium alginate (SA), AHA-bovine serum albumin (BSA) and AHA-dextran (DEX)) coagulated with aluminum chloride (AlCl3) were measured. Results showed that increasing the aluminum coagulant dosage induced the aggregation of DOM. Meanwhile, the addition of aluminum coagulant resulted in an increase in DSlope(325-375) (the slope of the log-transformed absorbance spectra from 325 to 375 nm) and a decrease in S(275-295) (the slope of the log-transformed absorption coefficient from 275 to 295 nm) and SR (the ratio of Slope(275-295) and Slope(350-400)). The variations of these spectral parameters (i.e., DSlope(325-375), S(275-295) and SR) correlated well with the aluminum-caused changes in ZPs and average particle size. This implies that spectral parameters have the potential to indicate DOM aggregation. In addition, good correlations of spectral parameters and membrane fouling behaviors (i.e., unified membrane fouling index (UMFI)) suggest that the changes in DSlope(325-375), S(275-295) and SR were indicative of the aluminum-caused alterations of fouling potentials of all DOM solutions. Interestingly, the optimal dosage of aluminum (40 μM for AHA, AHA-BSA, and AHA-DEX) was obtained based on the relation between spectral parameters and fouling behaviors. Overall, the spectroscopic analysis, particularly for the utilization of spectral parameters, provided a convenient approach

  2. Electrochemical analysis of the UV treated bactericidal Ti6Al4V surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pacha-Olivenza, Miguel A. [Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) (Spain); Department of Applied Physics, Faculty of Science, University of Extremadura, Av. Elvas s/n, 06071 Badajoz (Spain); Gallardo-Moreno, Amparo M., E-mail: amparogm@unex.es [Department of Applied Physics, Faculty of Science, University of Extremadura, Av. Elvas s/n, 06071 Badajoz (Spain); Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) (Spain); Vadillo-Rodríguez, Virginia; González-Martín, M. Luisa [Department of Applied Physics, Faculty of Science, University of Extremadura, Av. Elvas s/n, 06071 Badajoz (Spain); Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) (Spain); Pérez-Giraldo, Ciro [Department of Microbiology, Faculty of Medicine, University of Extremadura, Av. Elvas s/n, 06071 Badajoz (Spain); Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) (Spain); Galván, Juan C. [National Centre for Metallurgical Research (CENIM-CSIC), Av. Gregorio del Amo 8, 28040-Madrid (Spain)

    2013-04-01

    This research investigates in detail the bactericidal effect exhibited by the surface of the biomaterial Ti6Al4V after being subjected to UV-C light. It has been recently hypothesized that small surface currents, occurring as a consequence of the electron–hole pair recombination taking place after the excitation process, are behind the bactericidal properties displayed by this UV-treated material. To corroborate this hypothesis we have used different electrochemical techniques, such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization plots and Mott–Schottky plots. EIS and Mott–Schottky plots have shown that UV-C treatment causes an initial increase on the surface electrical conduction of this material. In addition, EIS and polarization plots demonstrated that higher corrosion currents occur at the UV treated than at the non-irradiated samples. Despite this increase in the corrosion currents, EIS has also shown that such currents are not likely to affect the good stability of this material oxide film since the irradiated samples completely recovered the control values after being stored in dark conditions for a period not longer than 24 h. These results agree with the already-published in vitro transitory behavior of the bactericidal effect, which was shown to be present at initial times after the biomaterial implantation, a crucial moment to avoid a large number of biomaterial associated infections. Highlights: ► Bactericidal response of UV-treated Ti6Al4V is explained through electrochemistry. ► There is an increase in the superficial electrical conduction after UV-treatment. ► Higher corrosion currents for UV-treated against non-UV-treated samples are shown. ► EIS shows the recuperation on irradiated samples in agreement with microbial tests.

  3. Modelling UV irradiances on arbitrarily oriented surfaces: effects of sky obstructions

    Directory of Open Access Journals (Sweden)

    M. Hess

    2008-02-01

    Full Text Available A method is presented to calculate UV irradiances on inclined surfaces that additionally takes into account the influence of sky obstructions caused by obstacles such as mountains, houses, trees, or umbrellas. Thus the method allows calculating the impact of UV radiation on biological systems, such as for instance the human skin or eye, in any natural or artificial environment. The method, a combination of radiation models, is explained and the correctness of its results is demonstrated. The effect of a natural skyline is shown for an Alpine ski area, where the UV irradiance even on a horizontal surface may increase due to reflection at snow by more than 10%. In contrast in a street canyon the irradiance on a horizontal surface is reduced down to 30% in shadow and to about 75% for a position in the sun.

  4. Modelling UV irradiances on arbitrarily oriented surfaces: effects of sky obstructions

    Science.gov (United States)

    Hess, M.; Koepke, P.

    2008-07-01

    A method is presented to calculate UV irradiances on inclined surfaces that additionally takes into account the influence of sky obstructions caused by obstacles such as mountains, houses, trees, or umbrellas. With this method it is thus possible to calculate the impact of UV radiation on biological systems, such as, for instance, the human skin or eye, in any natural or artificial environment. The method, which consists of a combination of radiation models, is explained here and the accuracy of its results is demonstrated. The effect of a natural skyline is shown for an Alpine ski area, where the UV irradiance even on a horizontal surface may increase due to reflection from snow by more than 10 percent. In contrast, in a street canyon the irradiance on a horizontal surface is reduced to 30% in shadow and to about 75% for a position in the sun.

  5. UV-Surface Treatment of Fungal Resistant Polyether Polyurethane Film-Induced Growth of Entomopathogenic Fungi

    Directory of Open Access Journals (Sweden)

    Gabriela Albara Lando

    2017-07-01

    Full Text Available Synthetic polymers are the cause of some major environmental impacts due to their low degradation rates. Polyurethanes (PU are widely used synthetic polymers, and their growing use in industry has produced an increase in plastic waste. A commercial polyether-based thermoplastic PU with hydrolytic stability and fungus resistance was only attacked by an entomopathogenic fungus, Metarhiziumanisopliae, when the films were pre-treated with Ultraviolet (UV irradiation in the presence of reactive atmospheres. Water contact angle, Fourier transform infrared spectroscopy in attenuated total reflection mode (FTIR-ATR, scanning electron microscopy (SEM, and profilometer measurements were mainly used for analysis. Permanent hydrophilic PU films were produced by the UV-assisted treatments. Pristine polyether PU films incubated for 10, 30, and 60 days did not show any indication of fungal growth. On the contrary, when using oxygen in the UV pre-treatment a layer of fungi spores covered the sample, indicating a great adherence of the microorganisms to the polymer. However, if acrylic acid vapors were used during the UV pre-treatment, a visible attack by the entomopathogenic fungi was observed. SEM and FTIR-ATR data showed clear evidence of fungal development: growth and ramifications of hyphae on the polymer surface with the increase in UV pre-treatment time and fungus incubation time. The results indicated that the simple UV surface activation process has proven to be a promising alternative for polyether PU waste management.

  6. Preparation and UV-light Absorption Property of Oleic Acid Surface Modified ZnO Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    KANG Jong-hun; GUO Yu-peng; CHEN Yue; WANG Zi-chen

    2011-01-01

    Syntheses of zince oxide(ZnO) nanoparticles by direct precipitation and surface modification with oleic acid were reported. ZnO nanoparticles were characterized via X-ray diffractometry(XRD), transmission electron microscopy(TEM), infrared spectroscopy(IR) and UV-Vis spectroscopy. The prepared ZnO nanoparticles were nearly spherical and highly crystalline with an average size of 29 nm. In addition, high UV-light absorption properties of oleic acid surface modified ZnO nanoparticles were successfully obtained for a dispersion of ZnO nanoparticles in ethanol.

  7. The influence of surface topography of UV coated and printed cardboard on the print gloss

    Directory of Open Access Journals (Sweden)

    Igor Karlović

    2010-09-01

    Full Text Available The incident light on the printed surface undergoes through several processes of scattering, absorbtion and reflectiondepending on the surface topography and structure of the material. The specular part of the surface reflection is commonlyattributed as the geometric component of the reflection, and when measured is associated with specular gloss.The diffuse part of the surface reflection contains the chromatic part of the reflection and is commonly calculatedthrough colorimetric values. Using UV coatings as surface enhacement materials which affect the optical propertiesof coated surfaces and final appearance of the printed product forms new surface topography over the existingone. We have investigated the influence of three different amounts of UV glossy and matte oveprint coating on themeasured specular gloss of printed cardboard samples. The different amount of coatings on the printed samples wereachived using three different screen stencils of 180 threads/cm, 150 threads/cm and 120 threads/cm thread count.The cardboard samples were analysed with AFM and SEM microscopes to obtain surface topography and roughnessvalues which were evaluated with the measured geometric values speficied as instrumental gloss. The surfaceswith a specific amount of UV coatings showed a new formed topography which influences the reflection of light.The changes in topography were evaluated through surface roughness parameters which showed a decline of surfaceroughness with tht additional ammount of glossy and matte coatings. The obtained and calculated correlations showthere is a high correlation between coating ammount and surface roughness change and gloss for the glossy UVcoating. The results for the matte UV coatings showed lower correlation for the gloss and surface roughness.

  8. One-step surface selective modification of UV-curable hard coatings with photochemical metal organics

    Science.gov (United States)

    Lee, Yoon Kwang; Park, Chang-Sun; Park, Hyung-Ho

    2016-12-01

    An organic-inorganic hybrid bi-layer film with a selective distribution of inorganic components was synthesized from a one-pot process of UV irradiation. A photochemical metal oxide precursor (Sr 2-ethylhexanoate) varying from 0 to 4 wt% was dispersed in UV-curable coating materials. Under UV exposure, the bi-layer started reacting simultaneously but at different rates due to differences in the two UV-condensable components' reactivity. The effects of the dispersed inorganic component on the surface morphology and mechanical properties were investigated by atomic force microscopy and nanoindentation, respectively. The reaction process and rates were studied from linkage change using Fourier transform infrared spectroscopy at various UV exposure times (0-30 min). The elemental distribution and the interface on the coating layer were characterized by X-ray photoelectron spectroscopy from Ar etching, revealing continuous and gradual composition changes in depth. The results showed that a flattened and surface-selectively hardened SrO containing the coating film could be obtained by this simple process. Consequently, a small ratio of photochemical metal oxide reinforced the organic hard coating film's mechanical properties through the formation of an effective SrO top layer.

  9. The physical properties of Spitzer/IRS galaxies derived from their UV to 22 μm spectral energy distribution

    Science.gov (United States)

    Vika, Marina; Ciesla, Laure; Charmandaris, Vassilis; Xilouris, Emmanuel M.; Lebouteiller, Vianney

    2017-01-01

    We provide the basic integrated physical properties of all the galaxies contained in the full Cornell Atlas of Spitzer/IRS Sources (CASSIS) with available broad-band photometry from UV to 22 μm. We have collected broad-band photometric measurements in 14 wavelengths from available public surveys in order to study the spectral energy distribution (SED) of each galaxy in CASSIS, thus constructing a final sample of 1146 galaxies in the redshift range 0 code which relies on the energy balance between the absorbed stellar and the dust emission while taking into account the possible contribution due to the presence of an active galactic nucleus (AGN). We split the galaxies in three groups, a low-redshift (z r colour, Sérsic indices, optical [OIII] and [NII] emission lines we explore the nature of these galaxies by investigating further their structure as well as their star-formation and AGN activity. Using a colour magnitude diagram we confirm that 97% of the galaxies with redshift smaller than 0.5 have experienced a recent star-formation episode. For a sub-sample of galaxies with available structural information and redshift smaller than 0.3 we find that early-type galaxies are placed below the main sequence, while late-type galaxies are found on the main-sequence as expected. Finally, for all the galaxies with redshift smaller than 0.5 and available optical spectral line measurements we compare the ability of CIGALE to detect the presence of an AGN in contrast to the optical spectra classification. We find that galaxies with high AGN luminosity, as calculated by CIGALE, are most likely to be classified as composite or AGNs by optical spectral lines. The full Table A.1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/597/A51

  10. Ultra-Sensitive Instrumentation in the UV-Vis-NIR Spectral Region with Applications on Overtone Spectroscopy

    Science.gov (United States)

    Camejo, David

    Fourier transform infrared spectroscopy (FT-IR) is a technique widely used in molecular spectroscopy. Technology advancements are such that FT-IR spectrometers can measure vibrational transitions occurring well within the visible (Vis) region of the electromagnetic spectrum. High overtone transitions of C-H, N-H, and O-H can be measured in the near-infrared (NIR) and the Vis regions using long path cells. Despite the large sensitivity of the FT-IR spectrometers and the use of long path cells, the absorption intensities of these transitions are so low that commercial FT-IR spectrometers would not register the absorption bands. Phase shift cavity ring down (PS-CRD) and thermal lens spectroscopy (TLS) are ultra-sensitive instrumental absorption techniques very commonly used in our laboratory. These are very powerful techniques for the detection of weak absorptions in the NIR-Vis region. In the case of high overtone spectra, CRD is ideal for gas samples whereas TLS is great for liquid samples. In our laboratory we use FT-IR and UV-Vis spectrometers as complementary techniques to CRDS and TLS. In order to simulate conditions in the atmospheres of other planets, we couple our instruments to a low temperature cryostat. In this way, these ultra-sensitive techniques can be applied to the study of gases in the atmosphere and liquid cryo-solutions to simulate the lakes of Saturn's largest moon, Titan. This work shows the use of signal-to-noise ratios to determine the spectral quality of spectra obtained with the PS-CRD technique, particularly in situations where human eye cannot perceive the small differences. We evaluate the impact of some instrumental parameters involved in data acquisition process of the PS-CRD technique, as well as evaluate the spectral quality as a function of the On-Axis/Off-Axis position of the incoming beam. This work also introduces the use of a second pumping laser for the analysis of multi-component samples in thermal lens. The design facilitates

  11. Leaf surface wax is a source of plant methane formation under UV radiation and in the presence of oxygen

    DEFF Research Database (Denmark)

    Bruhn, Dan; Mikkelsen, Teis Nørgaard; Rolsted, M. M. M.

    2014-01-01

    The terrestrial vegetation is a source of UV radiation-induced aerobic methane (CH4) release to the atmosphere. Hitherto pectin, a plant structural component, has been considered as the most likely precursor for this CH4 release. However, most of the leaf pectin is situated below the surface wax...... layer, and UV transmittance of the cuticle differs among plant species. In some species, the cuticle effectively absorbs and/or reflects UV radiation. Thus, pectin may not necessarily contribute substantially to the UV radiation-induced CH4 emission measured at surface level in all species. Here, we...... investigated the potential of the leaf surface wax itself as a source of UV radiationinduced leaf aerobic CH4 formation. Isolated leaf surface wax emitted CH4 at substantial rates in response to UV radiation. This discovery has implications for how the phenomenon should be scaled to global levels. In relation...

  12. Plasmonic resonances in hybrid systems of aluminum nanostructured arrays and few layer graphene within the UV-IR spectral range.

    Science.gov (United States)

    González-Campuzano, Ricardo; Saniger, J M; Mendoza, Doroteo

    2017-09-15

    The size-controllable and ordered Al nanocavities and nanodomes arrays were synthesized by electrochemical anodization of aluminum using phosphoric acid, citric acid and mixture both acids. Few layer graphene (FLG) was transferred directly on top of Al nanostructures and their morphology were evaluated by Scanning Electron Microscopy. The interaction between FLG and the plasmonic properties of Al nanostructures arrays were investigated based on specular reflectivity in the UV-Vis-IR range and Raman Spectroscopy. We found that their optical reflectivity was dramatically reduced as compared with unstructured Al. At the same time pronounced reflectivity dips were detectable in the 200 nm-896 nm wavelength range, which were ascribed to plasmonic resonances. The plasmonic properties of these nanostructures do not exhibit evident changes by the presence of FLG in the UV-Vis range of the electromagnetic spectrum. By contrast, the Surface-Enhanced Raman Spectroscopy (SERS) of FLG was observed in nanocavities and nanodomes structures that result in an intensity increase of the characteristic G and 2D bands of FLG induced by the plasmonic properties of Al nanostructures. © 2017 IOP Publishing Ltd.

  13. ARM Climate Research Facility Spectral Surface Albedo Value-Added Product (VAP) Report

    Energy Technology Data Exchange (ETDEWEB)

    McFarlane, S; Gaustad, K; Long, C; Mlawer, E

    2011-07-15

    This document describes the input requirements, output data products, and methodology for the Spectral Surface Albedo (SURFSPECALB) value-added product (VAP). The SURFSPECALB VAP produces a best-estimate near-continuous high spectral resolution albedo data product using measurements from multifilter radiometers (MFRs). The VAP first identifies best estimates for the MFR downwelling and upwelling shortwave irradiance values, and then calculates narrowband spectral albedo from these best-estimate irradiance values. The methodology for finding the best-estimate values is based on a simple process of screening suspect data and backfilling screened and missing data with estimated values when possible. The resulting best-estimate MFR narrowband spectral albedos are used to determine a daily surface type (snow, 100% vegetation, partial vegetation, or 0% vegetation). For non-snow surfaces, a piecewise continuous function is used to estimate a high spectral resolution albedo at 1 min temporal and 10 cm-1 spectral resolution.

  14. ARM Climate Research Facility Spectral Surface Albedo Value-Added Product (VAP) Report

    Energy Technology Data Exchange (ETDEWEB)

    McFarlane, S; Gaustad, K; Long, C; Mlawer, E

    2011-07-15

    This document describes the input requirements, output data products, and methodology for the Spectral Surface Albedo (SURFSPECALB) value-added product (VAP). The SURFSPECALB VAP produces a best-estimate near-continuous high spectral resolution albedo data product using measurements from multifilter radiometers (MFRs). The VAP first identifies best estimates for the MFR downwelling and upwelling shortwave irradiance values, and then calculates narrowband spectral albedo from these best-estimate irradiance values. The methodology for finding the best-estimate values is based on a simple process of screening suspect data and backfilling screened and missing data with estimated values when possible. The resulting best-estimate MFR narrowband spectral albedos are used to determine a daily surface type (snow, 100% vegetation, partial vegetation, or 0% vegetation). For non-snow surfaces, a piecewise continuous function is used to estimate a high spectral resolution albedo at 1 min temporal and 10 cm-1 spectral resolution.

  15. Chemical imaging and solid state analysis at compact surfaces using UV imaging

    DEFF Research Database (Denmark)

    Wu, Jian X.; Rehder, Sönke; van den Berg, Frans

    2014-01-01

    Fast non-destructive multi-wavelength UV imaging together with multivariate image analysis was utilized to visualize distribution of chemical components and their solid state form at compact surfaces. Amorphous and crystalline solid forms of the antidiabetic compound glibenclamide...... and excipients in a non-invasive way, as well as mapping the glibenclamide solid state form. An exploratory data analysis supported the critical evaluation of the mapping results and the selection of model parameters for the chemical mapping. The present study demonstrated that the multi-wavelength UV imaging...

  16. UV Surface Environment of Earth-like Planets Orbiting FGKM Stars Through Geological Evolution

    CERN Document Server

    Rugheimer, S; Kaltenegger, L; Sasselov, D

    2015-01-01

    The UV environment of a host star affects the photochemistry in the atmosphere, and ultimately the surface UV environment for terrestrial planets and therefore the conditions for the origin and evolution of life. We model the surface UV radiation environment for Earth-sized planets orbiting FGKM stars at the 1AU equivalent distance for Earth through its geological evolution. We explore four different types of atmospheres corresponding to an early Earth atmosphere at 3.9 Gyr ago and three atmospheres covering the rise of oxygen to present day levels at 2.0 Gyr ago, 0.8 Gyr ago and modern Earth (Following Kaltenegger et al. 2007). In addition to calculating the UV flux on the surface of the planet, we model the biologically effective irradiance, using DNA damage as a proxy for biological damage. We find that a pre-biotic Earth (3.9 Gyr ago) orbiting an F0V star receives 6 times the biologically effective radiation as around the early Sun and 3520 times the modern Earth-Sun levels. A pre-biotic Earth orbiting GJ...

  17. Interaction and UV-Stability of Various Organic Capping Agents on the Surface of Anatase Nanoparticles

    Directory of Open Access Journals (Sweden)

    Mohsin Raza

    2014-04-01

    Full Text Available Anatase nanoparticles synthesized by the sol-gel method were surface-functionalized with long alkyl chain coupling agents as compatibilizers for a nonpolar environment, containing different anchor groups for surface interaction namely phosphonate (dodecyl phosphonate, carboxylate (dodecanoic acid, sulfate (sodium dodecyl sulphate, and amine (dodecyl amine. It was shown that the surface of the nanoparticles can be functionalized with the various surface groups applying similar reaction conditions. The kind of surface interaction was analyzed applying FTIR spectroscopy. The phosphonate and the carboxylate groups interact with the surface via quite strong covalent or coordinative interactions, respectively. The sulfate and amine based coupling agents on the other hand exhibit electrostatic interactions. UV stability studies of the surface bound groups revealed different degradation mechanisms for the various functionalities and moreover showed that phosphonates are the most stable among the investigated surface capping groups.

  18. Remote sensing for oil products on water surface via fluorescence induced by UV filaments

    Science.gov (United States)

    Sunchugasheva, E. S.; Ionin, A. A.; Mokrousova, D. V.; Seleznev, L. V.; Sinitsyn, D. V.; Geints, Yu. E.; Zemlyanov, A. A.

    2016-10-01

    Remote monitoring of water pollution, namely thin films of oil or oil products on water surface, can be carried out by laser fluorimetry. The pollutants fluorescence during its interaction with ultrashort UV laser pulses was experimentally studied in this paper. The laser pulses power was considered in a wide range of values including the filamentation regime. We compared fluorescence stimulated by femtosecond UV laser pulses with two central wavelengths (248 and 372 nm) for detection of crude oil and the following oil products: oil VM-5, oil 5W-40 and solvent WhiteSpirit. It was shown that shorter UV wavelengths are more suitable for fluorescence excitation. The spatial resolution of the fluorescence localization was no worse than 30 cm. We discuss techniques of high intensity emission delivery to the remote target as post-filamentation channels and multifilamentation beam propagation regime as well experimentally and numerically.

  19. Spectral phase transfer from near IR to deep UV by broadband phase-matched four-wave mixing in an argon-filled hollow core waveguide

    Science.gov (United States)

    Siqueira, J. P.; Mendonça, C. R.; Zilio, S. C.; Misoguti, L.

    2016-10-01

    We report on the implementation of a spectral phase transfer scheme from near IR to deep UV, in which the frequency conversion step is based on the broadband phase-matched four-wave mixing in a gas-filled hollow core waveguide. Micro joule level femtosecond pulses at 260 nm were generated by nonlinear mixing of a Ti:sapphire laser and its second-harmonic. The transfer of a π-step phase in a controllable manner was proposed and confirmed by a modulation observed in the generated deep UV femtosecond pulse spectrum due to an interference process. Numerical simulations confirmed our results.

  20. IR and UV laser-induced morphological changes in silicon surface under oxygen atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez-Jarquin, J.; Fernandez-Guasti, M.; Haro-Poniatowski, E.; Hernandez-Pozos, J.L. [Laboratorio de Optica Cuantica, Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco No. 186, Col. Vicentina, C.P. 09340, Mexico D.F. (Mexico)

    2005-08-01

    We irradiated silicon (100) wafers with IR (1064 nm) and UV (355 nm) nanosecond laser pulses with energy densities within the ablation regime and used scanning electron microscopy to analyze the morphological changes induced on the Si surface. The changes in the wafer morphology depend both on the incident radiation wavelength and the environmental atmosphere. We have patterned Si surfaces with a single focused laser spot and, in doing the experiments with IR or UV this reveals significant differences in the initial surface cracking and pattern formation, however if the experiment is carried out in O{sub 2} the final result is an array of microcones. We also employed a random scanning technique to irradiate the silicon wafer over large areas, in this case the microstructure patterns consist of a ''semi-ordered'' array of micron-sized cones. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Vibrational spectral investigation, NBO, first hyperpolarizability and UV-Vis spectral analysis of 3,5-dichlorobenzonitrile and m-bromobenzonitrile by ab initio and density functional theory methods.

    Science.gov (United States)

    Senthil kumar, J; Jeyavijayan, S; Arivazhagan, M

    2015-02-05

    The FT-IR and FT-Raman spectra of 3,5-dichlorobenzonitrile and m-bromobenzonitrile have been recorded in the region 4000-400 cm(-1) and 3500-50 cm(-1), respectively. The optimized geometry, wave numbers and intensity of vibrational bonds of title molecules are obtained by ab initio and DFT level of theory with complete relaxation in the potential energy surface using 6-311++G(d, p) basis set. A complete vibrational assignments aided by the theoretical harmonic frequency, analysis have been proposed. The harmonic vibrational frequencies calculated have been compared with experimental FT-IR and FT-Raman spectra. The observed and calculated frequencies are found to be in good agreement. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The UV-Vis spectral analysis of the molecules has also been done which confirms the charge transfer of the molecules. Furthermore, the first hyperpolarizability and total dipole moment of the molecules have been calculated.

  2. Evolution of the complex refractive index in the near UV spectral region in ageing secondary organic aerosol

    Directory of Open Access Journals (Sweden)

    J. M. Flores

    2014-02-01

    Full Text Available The chemical and physical properties of secondary organic aerosol (SOA formed by the photochemical degradation of biogenic and anthropogenic volatile organic compounds (VOC are yet poorly constrained. The evolution of the complex refractive index (RI of SOA, formed from purely biogenic VOC and mixtures of biogenic and anthropogenic VOC was studied over a diurnal cycle in the SAPHIR photochemical outdoor chamber in Jülich, Germany. The correlation of RI with SOA chemical and physical properties such as oxidation level and volatility was examined. The RI was retrieved by a newly developed broadband cavity enhanced spectrometer for aerosol optical extinction measurements in the near UV spectral region (360 to 420 nm. Chemical composition and volatility of the particles were monitored by a high resolution time of flight aerosol mass spectrometer, and a volatility tandem differential mobility analyzer. SOA was formed by ozonolysis of either (i a mixture of biogenic VOC (α-pinene and limonene, (ii biogenic VOC mixture with subsequent addition of an anthropogenic VOC (p-xylene-d10, or (iii a mixture of biogenic and anthropogenic VOC. The SOA aged by ozone / OH reactions up to 29.5 h was found to be non-absorbing in all cases. The SOA with p-xylene-d10 showed an increase of the scattering component of the RI correlated with an increase of the O / C ratio and with an increase in the SOA density. There was a greater increase in the scattering component of the RI when the SOA was produced from the mixture of biogenic VOCs and anthropogenic VOC than from the sequential addition of the VOCs after the approximate same ageing time. The increase of the scattering component was inversely correlated with the SOA volatility. Two RI retrievals determined for the pure biogenic SOA showed a constant RI for up to 5 h of ageing. Mass spectral characterization shows the three types of the SOA formed in this study have significant amount of semivolatile components. The

  3. Evolution of the complex refractive index in the near UV spectral region in ageing secondary organic aerosol

    Science.gov (United States)

    Flores, J. M.; Zhao, D. F.; Segev, L.; Schlag, P.; Kiendler-Scharr, A.; Fuchs, H.; Watne, Å. K.; Bluvshtein, N.; Mentel, Th. F.; Hallquist, M.; Rudich, Y.

    2014-02-01

    The chemical and physical properties of secondary organic aerosol (SOA) formed by the photochemical degradation of biogenic and anthropogenic volatile organic compounds (VOC) are yet poorly constrained. The evolution of the complex refractive index (RI) of SOA, formed from purely biogenic VOC and mixtures of biogenic and anthropogenic VOC was studied over a diurnal cycle in the SAPHIR photochemical outdoor chamber in Jülich, Germany. The correlation of RI with SOA chemical and physical properties such as oxidation level and volatility was examined. The RI was retrieved by a newly developed broadband cavity enhanced spectrometer for aerosol optical extinction measurements in the near UV spectral region (360 to 420 nm). Chemical composition and volatility of the particles were monitored by a high resolution time of flight aerosol mass spectrometer, and a volatility tandem differential mobility analyzer. SOA was formed by ozonolysis of either (i) a mixture of biogenic VOC (α-pinene and limonene), (ii) biogenic VOC mixture with subsequent addition of an anthropogenic VOC (p-xylene-d10), or (iii) a mixture of biogenic and anthropogenic VOC. The SOA aged by ozone / OH reactions up to 29.5 h was found to be non-absorbing in all cases. The SOA with p-xylene-d10 showed an increase of the scattering component of the RI correlated with an increase of the O / C ratio and with an increase in the SOA density. There was a greater increase in the scattering component of the RI when the SOA was produced from the mixture of biogenic VOCs and anthropogenic VOC than from the sequential addition of the VOCs after the approximate same ageing time. The increase of the scattering component was inversely correlated with the SOA volatility. Two RI retrievals determined for the pure biogenic SOA showed a constant RI for up to 5 h of ageing. Mass spectral characterization shows the three types of the SOA formed in this study have significant amount of semivolatile components. The influence

  4. UV irradiation induced switching of surface charge polarity on pyrene modified Si nanowires

    Science.gov (United States)

    Zhao, Wen-Chao; Wang, Hui; Ou, Xue-Mei; Lee, Chun-Sing; Zhang, Xiao-Hong

    2011-06-01

    It has been widely recognized that surface charge in nanomaterials can significantly affect their electrical properties. In this letter, we demonstrate that polarity of surface charge on pyrene modified silicon nanowires (SiNWs) can be switched by illumination of UV light. Unlike the reported conversion method via changing the surrounding pH value, switching process reported here takes place in real-time and does not require introduction of any other chemical species. Mechanisms of the surface charge polarity switching and potential applications of such systems were discussed.

  5. Poly(ethylene terephthalate) surface modification by deep UV (172 nm) irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhengmao Zhua; Michael J. Kelley

    2004-09-01

    The prospects of obtaining desired surface-mediated characteristics while retaining bulk-mediated physical properties and avoiding potential environmental issues with wet chemical technology lends considerable appeal to photochemical approaches. We investigated the response of poly(ethylene terephthalate) to 172 nm UV from a xenon excimer lamp in the absence of oxygen, using XPS, ToF/SIMS, and AFM. The main effects are increasing loss of a C=O moiety and carboxylic acid production without effect on topography up to a total fluence of 16 J/cm2. Above this level no further change in surface chemistry was evident, but surfaces became rougher, suggesting the onset of etching.

  6. UV Light Inactivation of Human and Plant Pathogens in Unfiltered Surface Irrigation Water

    Science.gov (United States)

    Jones, Lisa A.; Worobo, Randy W.

    2014-01-01

    Fruit and vegetable growers continually battle plant diseases and food safety concerns. Surface water is commonly used in the production of fruits and vegetables and can harbor both human- and plant-pathogenic microorganisms that can contaminate crops when used for irrigation or other agricultural purposes. Treatment methods for surface water are currently limited, and there is a need for suitable treatment options. A liquid-processing unit that uses UV light for the decontamination of turbid juices was analyzed for its efficacy in the treatment of surface waters contaminated with bacterial or oomycete pathogens, i.e., Escherichia coli, Salmonella enterica, Listeria monocytogenes, Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. tomato, and Phytophthora capsici. Five-strain cocktails of each pathogen, containing approximately 108 or 109 CFU/liter for bacteria or 104 or 105 zoospores/liter for Ph. capsici, were inoculated into aliquots of two turbid surface water irrigation sources and processed with the UV unit. Pathogens were enumerated before and after treatment. In general, as the turbidity of the water source increased, the effectiveness of the UV treatment decreased, but in all cases, 99.9% or higher inactivation was achieved. Log reductions ranged from 10.0 to 6.1 and from 5.0 to 4.2 for bacterial pathogens and Ph. capsici, respectively. PMID:24242253

  7. UV light inactivation of human and plant pathogens in unfiltered surface irrigation water.

    Science.gov (United States)

    Jones, Lisa A; Worobo, Randy W; Smart, Christine D

    2014-02-01

    Fruit and vegetable growers continually battle plant diseases and food safety concerns. Surface water is commonly used in the production of fruits and vegetables and can harbor both human- and plant-pathogenic microorganisms that can contaminate crops when used for irrigation or other agricultural purposes. Treatment methods for surface water are currently limited, and there is a need for suitable treatment options. A liquid-processing unit that uses UV light for the decontamination of turbid juices was analyzed for its efficacy in the treatment of surface waters contaminated with bacterial or oomycete pathogens, i.e., Escherichia coli, Salmonella enterica, Listeria monocytogenes, Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. tomato, and Phytophthora capsici. Five-strain cocktails of each pathogen, containing approximately 10(8) or 10(9) CFU/liter for bacteria or 10(4) or 10(5) zoospores/liter for Ph. capsici, were inoculated into aliquots of two turbid surface water irrigation sources and processed with the UV unit. Pathogens were enumerated before and after treatment. In general, as the turbidity of the water source increased, the effectiveness of the UV treatment decreased, but in all cases, 99.9% or higher inactivation was achieved. Log reductions ranged from 10.0 to 6.1 and from 5.0 to 4.2 for bacterial pathogens and Ph. capsici, respectively.

  8. Surface Degradation and Nanoparticle Release of a Commercial Nanosilica/Polyurethane Coating Under UV Exposure.

    Science.gov (United States)

    Jacobs, Deborah S; Huang, Sin-Ru; Cheng, Yu-Lun; Rabb, Savelas A; Gorham, Justin M; Krommenhoek, Peter J; Yu, Lee L; Nguyen, Tinh; Sung, Lipiin

    2016-09-01

    Many coatings properties such as mechanical, electrical, and ultra violet (UV) resistance are greatly enhanced by the addition of nanoparticles, which can potentially increase the use of nanocoatings for many outdoor applications. However, because polymers used in all coatings are susceptible to degradation by weathering, nanoparticles in a coating may be brought to the surface and released into the environment during the life cycle of a nanocoating. Therefore, the goal of this study is to investigate the process and mechanism of surface degradation and potential particle release from a commercial nanosilica/polyurethane coating under accelerated UV exposure. Recent research at the National Institute of Standards and Technology (NIST) has shown that the matrix in an epoxy nanocomposite undergoes photodegradation during exposure to UV radiation, resulting in surface accumulation of nanoparticles and subsequent release from the composite. In this study, specimens of a commercial polyurethane (PU) coating, to which a 5 mass % surface treated silica nanoparticles solution was added, were exposed to well-controlled, accelerated UV environments. The nanocoating surface morphological changes and surface accumulation of nanoparticles as a function of UV exposure were measured, along with chemical change and mass loss using a variety of techniques. Particles from the surface of the coating were collected using a simulated rain process developed at NIST, and the collected runoff specimens were measured using inductively coupled plasma-optical emission spectroscopy (ICP-OES) to determine the amount of silicon released from the nanocoatings. The results demonstrated that the added silica nanoparticle solution decreased the photodegradation rate (i.e., stabilization) of the commercial PU nanocoating. Although the degradation was slower than the previous nanosilica epoxy model system, the degradation of the PU matrix resulted in accumulation of silica nanoparticles on the

  9. Influence of base impurity distribution on the photoelectric properties of surface-barrier UV photodetectors

    Directory of Open Access Journals (Sweden)

    Bobrenko Yu. N.

    2012-10-01

    Full Text Available The article presents the study on spectral, capacitance-voltage and current-voltage characteristics of surface-barrier structures based on A2B6 composition with different carrier concentration profiles in space-charge region sensitive to ultraviolet range and perspective for ultraviolet sensor application.

  10. Spectral emissivity measurements of land-surface materials and related radiative transfer simulations

    Science.gov (United States)

    Wan, Z.; Ng, D.; Dozier, J.

    1994-01-01

    Spectral radiance measurements have been made in the laboratory and in the field for deriving spectral emissivities of some land cover samples with a spectroradiometer and an auxiliary radiation source in the wavelength range 2.5-14.5 micrometers. A easy and quick four-step method (four steps to measure the sample and a diffuse reflecting plate surface under sunshine and shadowing conditions, respectively) has been used for simultaneous determination of surface temperature and emissivity. We emphasized in-situ measurements in combination with radiative transfer simulations, and an error analysis for basic assumptions in deriving spectral emissivity of land-surface samples from thermal infrared measurements.

  11. DFT calculations and experimental FT-IR, FT-Raman, NMR, UV-Vis spectral studies of 3-fluorophenylboronic acid.

    Science.gov (United States)

    Karabacak, M; Kose, E; Sas, E B; Kurt, M; Asiri, A M; Atac, A

    2015-02-05

    The spectroscopic (FT-IR, FT-Raman, (1)H and (13)C NMR, UV-Vis), structural, electronic and thermodynamical properties of 3-fluorophenylboronic acid (C6H4FB(OH)2), 3FPBA) were submitted by using both experimental techniques and theoretical methods (quantum chemical calculations) in this work. The experimental infrared and Raman spectra were obtained in the region 4000-400 cm(-1) and 3500-10 cm(-1), respectively. The equilibrium geometry and vibrational spectra were calculated by using DFT (B3LYP) with 6-311++G(d,p) basis set. The vibrational wavenumbers were also corrected with scale factor to take better results for the calculated data. The total energy distributions (TED) of the vibrational modes were performed for the assignments of the title molecule by using scaled quantum mechanics (SQM) method. The NMR chemical shifts ((1)H and (13)C) were recorded in DMSO solution. The (1)H and (13)C NMR spectra were computed by using the gauge-invariant atomic orbital (GIAO) method, showing a good agreement with the experimental ones. The last one UV-Vis absorption spectra were analyzed in two solvents (ethanol and water), saved in the range of 200-400 nm. In addition these, HOMO and LUMO energies, the excitation energies, density of states (DOS) diagrams, thermodynamical properties and molecular electrostatic potential surface (MEPs) were presented. Nonlinear optical (NLO) properties and thermodynamic features were performed. The experimental results are combined with the theoretical calculations using DFT calculations to fortification of the paper. At the end of this work, the results were proved our paper had been indispensable for the literature backing.

  12. Enhanced optical transmission through a star-shaped bull's eye at dual resonant-bands in UV and the visible spectral range.

    Science.gov (United States)

    Nazari, Tavakol; Khazaeinezhad, Reza; Jung, Woohyun; Joo, Boram; Kong, Byung-Joo; Oh, Kyunghwan

    2015-07-13

    Dual resonant bands in UV and the visible range were simultaneously observed in the enhanced optical transmission (EOT) through star-shaped plasmonic structures. EOTs through four types of polygonal bull's eyes with a star aperture surrounded by the concentric star grooves were analyzed and compared for 3, 4, 5, and 6 corners, using finite difference time domain (FDTD) method. In contrast to plasmonic resonances in the visible range, the UV-band resonance intensity was found to scale with the number of corners, which is related with higher order multipole interactions. Spectral positions and relative intensities of the dual resonances were analyzed parametrically to find optimal conditions to maximize EOT in UV-visible dual bands.

  13. Spectral Studies of UV and Solar Photocatalytic Degradation of AZO Dye and Textile Dye Effluents Using Green Synthesized Silver Nanoparticles.

    Science.gov (United States)

    Mariselvam, R; Ranjitsingh, A J A; Mosae Selvakumar, P; Alarfaj, Abdullah A; Munusamy, Murugan A

    2016-01-01

    The photocatalytic degradation of the chemical dye AZO and dye effluents in different time duration has been investigated using biologically synthesized silver nanoparticles. Dye industry effluents and AZO dye undergo degradation to form harmless intermediate and colourless products following irradiation by UV and solar light in the presence of green synthesized silver nanoparticles. The degree of degradation was tested under the experimental conditions such as P(H), temperature, and absorbance of the dye in UV and solar light was measured. The degradation was higher in the UV light source than in the solar light source. Green synthesized silver nanoparticles in the UV light source were found to expedite the dye degradation process.

  14. A novel method to prepare superhydrophobic, UV resistance and anti-corrosion steel surface

    KAUST Repository

    Isimjan, Tayirjan T.

    2012-11-01

    Both TiO 2 and SiO 2 coated steel surfaces containing micro- and nanoscale binary structures with different surface roughness were successfully fabricated by means of a facile layer by layer deposition process followed by heat treatment. The resulting surfaces were modified by the low free energy chemical PTES (1H,1H,2H,2H-Perfluorodecyltriethoxysilane). The experimental results of wettability exhibit that such modified surfaces have a strong repulsive force to water droplets, their static contact angles exceed 165°, receding angle>160°, advanced angles>170° and slide angle<1°. The resulting surfaces not only exhibit superhydrophobic properties but also show strong UV resistance (after coating SiO 2 on top of TiO 2) and strong stability to various solvents including 0.01% HCl solution. © 2012 Elsevier B.V.

  15. Photolysis of polycyclic aromatic hydrocarbons on soil surfaces under UV irradiation

    Institute of Scientific and Technical Information of China (English)

    Chengbin Xu; Dianbo Dong; Xuelian Meng; Xin Su; Xu Zheng; Yaoyao Li

    2013-01-01

    Photolysis of some polycyclic aromatic hydrocarbons (PAHs) on soil surfaces may play an important role in the fate of PAHs in the environment.Photolysis of PAHs on soil surfaces under UV irradiation was investigated.The effects of oxygen,irradiation intensity and soil moisture on the degradation of the three PAHs were observed.The results showed that oxygen,soil moisture and irradiation intensity enhanced the photolysis of the three PAHs on soil surfaces.The degradation of the three PAHs on soil surfaces is related to their absorption spectra and the oxidation-half-wave potential.The photolysis of PAHs on soil surfaces in the presence of oxygen followed pseudo first-order kinetics.The photolysis half-lives ranged from 37.87 days for benzo[a]pyrene to 58.73 days for phenanthrene.The results indicate that photolysis is a successful way to remediate PAHs-contaminated soils.

  16. A Facile in Situ and UV Printing Process for Bioinspired Self-Cleaning Surfaces

    Directory of Open Access Journals (Sweden)

    Marina A. González Lazo

    2016-08-01

    Full Text Available A facile in situ and UV printing process was demonstrated to create self-cleaning synthetic replica of natural petals and leaves. The process relied on the spontaneous migration of a fluorinated acrylate surfactant (PFUA within a low-shrinkage acrylated hyperbranched polymer (HBP and its chemical immobilization at the polymer-air interface. Dilute concentrations of 1 wt. % PFUA saturated the polymer-air interface within 30 min, leading to a ten-fold increase of fluorine concentration at the surface compared with the initial bulk concentration and a water contact angle (WCA of 108°. A 200 ms flash of UV light was used to chemically crosslink the PFUA at the HBP surface prior to UV printing with a polydimethylsiloxane (PDMS negative template of red and yellow rose petals and lotus leaves. This flash immobilization hindered the reverse migration of PFUA within the bulk HBP upon contacting the PDMS template, and enabled to produce texturized surfaces with WCA well above 108°. The synthetic red rose petal was hydrophobic (WCA of 125° and exhibited the adhesive petal effect. It was not superhydrophobic due to insufficient concentration of fluorine at its surface, a result of the very large increase of the surface of the printed texture. The synthetic yellow rose petal was quasi-superhydrophobic (WCA of 143°, roll-off angle of 10° and its self-cleaning ability was not good also due to lack of fluorine. The synthetic lotus leaf did not accurately replicate the intricate nanotubular crystal structures of the plant. In spite of this, the fluorine concentration at the surface was high enough and the leaf was superhydrophobic (WCA of 151°, roll-off angle below 5° and also featured self-cleaning properties.

  17. UV-Vis and Surface Photovoltage Spectra of Fe2O3/Polystyrene Composite Microspheres

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Fe2O3 sol with the particle diameter of 3-5 nm was flocculated by the addition of SDS, and the flocculate formed was redispersed by the further addition of that surfactant. Thus the surfactant bilayer was formed on the surface of Fe2O3. The emulsion polymerization of styrene(St) adsolubilized on the surfactant adsorbed bilayer was carried out by initiator potassium persulfate(KPS). The UV-Vis and surface photovoltage spectra(SPS) indicate that the Fe2O3 particles were encapsulated in polystyrene(PSt) successfully.

  18. Constructing robust and functional micropatterns on polystyrene surfaces by using deep UV irradiation.

    Science.gov (United States)

    Palacios, Marta; García, Olga; Rodríguez-Hernández, Juan

    2013-02-26

    We report the preparation of different surface patterns based on the photo-cross-linking/degradation kinetics of polystyrene (PS) by using UV light. Upon exposure to UV light, PS can be initially cross-linked, whereas an excess of the exposure time or intensity provokes the degradation of the material. Typically photolithography employs either positive or negative photoresist layers that upon removal of either the exposed or the nonexposed areas transfer the pattern of the mask. Herein, we present a system that can be both negative and positive depending on several aspects, including the irradiation time, intensity, or presence of absorbing active species (photoinitiators) using a general setup. As a result of the optimization of the time of exposure and the use of an appropriate cover or the incorporation of an appropriate amount of photoinitiator (in this particular case IRG 651), different tailor-made surface patterns can be obtained. Moreover, changes of the chemical composition of the polystyrene using, for instance, block copolymers can lead to surface patterns with variable functional groups. In this study we describe the formation of surface patterns using polystyrene-block-poly(2,3,4,5,6-pentafluorostyrene) block copolymers. The introduction of fluorinated moieties clearly modifies the wettability of the films when compared with that of the same structures obtained with PS. As a consequence we present herein a patterning methodology that can simultaneously vary not only the morphology but also the surface chemical composition.

  19. A comparative study of the bactericidal activity and daily disinfection housekeeping surfaces by a new portable pulsed UV radiation device.

    Science.gov (United States)

    Umezawa, Kazuo; Asai, Satomi; Inokuchi, Sadaki; Miyachi, Hayato

    2012-06-01

    Daily cleaning and disinfecting of non-critical surfaces in the patient-care areas are known to reduce the occurrence of health care-associated infections. However, the conventional means for decontamination of housekeeping surfaces of sites of frequent hand contact such as manual disinfection using ethanol wipes are laborious and time-consuming in daily practice. This study evaluated a newly developed portable pulsed ultraviolet (UV) radiation device for its bactericidal activity in comparison with continuous UV-C, and investigated its effect on the labor burden when implemented in a hospital ward. Pseudomonas aeruginosa, Multidrug-resistant P. aeruginosa, Escherichia coli, Acinetobacter baumannii, Amikacin and Ciprofloxacin-resistant A. baumannii, Staphylococcus aureus, Methicillin-resistant S. aureus and Bacillus cereus were irradiated with pulsed UV or continuous UV-C. Pulsed UV and continuous UV-C required 5 and 30 s of irradiation, respectively, to attain bactericidal activity with more than 2Log growth inhibition of all the species. The use of pulsed UV in daily disinfection of housekeeping surfaces reduced the working hours by half in comparison to manual disinfection using ethanol wipes. The new portable pulsed UV radiation device was proven to have a bactericidal activity against critical nosocomial bacteria, including antimicrobial-resistant bacteria after short irradiation, and was thus found to be practical as a method for disinfecting housekeeping surfaces and decreasing the labor burden.

  20. Controlling adverse and beneficial effects of solar UV radiation by wearing suitable clothes - spectral transmission of different kinds of fabrics.

    Science.gov (United States)

    Sobolewski, Piotr S; Krzyścin, Janusz W; Jarosławski, Janusz; Wink, Jakub; Lesiak, Aleksandra; Narbutt, Joanna

    2014-11-01

    Humans should avoid prolonged exposure to the Sun during the warm subperiod of the year with naturally high solar UV level. One of the known recommendations to avoid excessive UV radiation is wearing clothes with UV protection additives. However there is an important question: how do we get an adequate solar UV radiation, which maintains a healthy status of vitamin D, without facing overexposure risks? It is found that some kind of 100% cotton knitted fabric, used in the production of normal daily clothing, has ∼15% transmittance of solar UV. Model studies show that a garment made of this fabric allows larger synthesis of vitamin D3 in human body without the erythema risks (skin redness). Thus the adequate level of vitamin D could be attained safely by a person exposing only small part of the body (face, palms) during the period (May-August) of the year.

  1. Inference of Surface Chemical and Physical Properties Using Mid-Infrared (MIR) Spectral Observations

    Science.gov (United States)

    Roush, Ted L.

    2016-01-01

    Reflected or emitted energy from solid surfaces in the solar system can provide insight into thermo-physical and chemical properties of the surface materials. Measurements have been obtained from instruments located on Earth-based telescopes and carried on several space missions. The characteristic spectral features commonly observed in Mid-Infrared (MIR) spectra of minerals will be reviewed, along with methods used for compositional interpretations of MIR emission spectra. The influence of surface grain size, and space weathering processes on MIR emissivity spectra will also be discussed. Methods used for estimating surface temperature, emissivity, and thermal inertias from MIR spectral observations will be reviewed.

  2. Technical report. Video imaging of ethidium bromide-stained DNA gels with surface UV illumination.

    Science.gov (United States)

    Solioz, M

    1994-06-01

    We describe here the use of surface UV illumination to record ethidium bromide-stained DNA gels with a video camera. This mode of illumination allows the use of a standard video camera equipped with a red filter and results in a high signal strength. The assembly of a low-cost video system on this basis is described. It uses the public domain software called Image on a Macintosh computer and PostScript laser printer or a thermal printer to generate hard copies. The setup is sensitive enough to detect 500 pg of DNA on an ethidium bromide-stained DNA gel. The UV illumination method described here can also greatly improve the sensitivity of existing video recording equipment.

  3. Prevention of Ultraviolet (UV)-Induced Surface Damage and Cytotoxicity of Polyethersulfone Using Atomic Layer Deposition (ALD) Titanium Dioxide

    Science.gov (United States)

    Petrochenko, Peter E.; Scarel, Giovanna; Hyde, G. Kevin; Parsons, Gregory N.; Skoog, Shelby A.; Zhang, Qin; Goering, Peter L.; Narayan, Roger J.

    2013-04-01

    Nanostructured surfaces are finding use in several medical applications, including tissue scaffolds and wound dressings. These surfaces are frequently manufactured from biocompatible polymers that are susceptible to ultraviolet (UV) damage. Polyethersulfone (PES) is a biocompatible polymer that undergoes oxidation and degradation when exposed to ultraviolet (UV) light. A uniform TiO2 coating can protect PES during exposure to UV sources (e.g., germicidal lamps and sunlight). The goal of this study was to determine whether atomic layer deposition (ALD) can successfully be used to grow TiO2 onto PES, protect it from UV irradiation, and reduce macrophage in vitro cytotoxicity. TiO2 was ALD-coated onto PES at 21 nm thickness. Uncoated PES exposed to UV for 30 min visibly changed color, whereas TiO2-coated PES showed no color change, indicating limited degradation. Macrophages exposed to UV-treated PES for 48 h showed reduced cell viability (via MTT assay) to 18% of control. In contrast, the cell viability for UV-treated TiO2-coated PES was 90% of control. Non-UV treated PES showed no decrease in cell viability. The results indicate that ALD of TiO2 thin films is a useful technique to protect polymers from UV damage and to retain low cytotoxicity to macrophages and other types of cells that are involved in wound healing. TiO2- coated PES membranes also have potential use in direct methanol fuel cells and in wastewater treatment membranes.

  4. Efficiency of the UV/H2O2 process for the disinfection of humic surface waters.

    Science.gov (United States)

    Alkan, Ufuk; Teksoy, Arzu; Atesli, Ahu; Baskaya, Huseyin S

    2007-03-01

    The efficiency of the UV/H2O2 process for the disinfection of total coliforms and the prevention of bacterial regrowth in humic surface waters were investigated. Inactivation of total coliforms was determined in water samples containing various concentrations ranging from 0-10 mg/L dissolved organic carbon (DOC) of fulvic acid, which were exposed to various doses (68-681 mWs/cm2) of UV radiation in the presence of 0.125 mg/L and 3.000 mg/L of hydrogen peroxide. Disinfection efficiencies of the UV radiation and the UV/H2O2 processes were compared. The results of bacterial inactivation experiments showed that the performances of the UV and the UV/H2O2 (0.125) were comparable whereas the UV/H2O2 (3.000) process showed significant improvement in performance, especially, in highly humic waters. Inactivation coefficient appeared to be almost doubled by the addition of 3.000 mg/L hydrogen peroxide during the treatment of highly humic waters. In contradiction to significant regrowth which occurred in the single UV radiation treatment, residual bacteria following the UV/H2O2 (0.125) and the UV/H2O2 (3.000) treatments were completely inactivated during dark incubation indicating the elimination of possible bacterial regrowth.

  5. Photoluminescence of hexagonal boron nitride: effect of surface oxidation under UV-laser irradiation

    CERN Document Server

    Museur, Luc; Petitet, Jean-Pierre; Michel, Jean Pierre; Kanaev, Andrei V

    2008-01-01

    We report on the UV laser induced fluorescence of hexagonal boron nitride (h-BN) following nanosecond laser irradiation of the surface under vacuum and in different environments of nitrogen gas and ambient air. The observed fluorescence bands are tentatively ascribed to impurity and mono (VN), or multiple (m-VN with m = 2 or 3) nitrogen vacancies. A structured fluorescence band between 300 nm and 350 nm is assigned to impurity-band transition and its complex lineshape is attributed to phonon replicas. An additional band at 340 nm, assigned to VN vacancies on surface, is observed under vacuum and quenched by adsorbed molecular oxygen. UV-irradiation of h-BN under vacuum results in a broad asymmetric fluorescence at ~400 nm assigned to m-VN vacancies; further irradiation breaks more B-N bonds enriching the surface with elemental boron. However, no boron deposit appears under irradiation of samples in ambient atmosphere. This effect is explained by oxygen healing of radiation-induced surface defects. Formation o...

  6. Spectral reflectance of surface soils - A statistical analysis

    Science.gov (United States)

    Crouse, K. R.; Henninger, D. L.; Thompson, D. R.

    1983-01-01

    The relationship of the physical and chemical properties of soils to their spectral reflectance as measured at six wavebands of Thematic Mapper (TM) aboard NASA's Landsat-4 satellite was examined. The results of performing regressions of over 20 soil properties on the six TM bands indicated that organic matter, water, clay, cation exchange capacity, and calcium were the properties most readily predicted from TM data. The middle infrared bands, bands 5 and 7, were the best bands for predicting soil properties, and the near infrared band, band 4, was nearly as good. Clustering 234 soil samples on the TM bands and characterizing the clusters on the basis of soil properties revealed several clear relationships between properties and reflectance. Discriminant analysis found organic matter, fine sand, base saturation, sand, extractable acidity, and water to be significant in discriminating among clusters.

  7. "UV-olution, a photochemistry experiment in Low Earth Orbit": investigation of the photostability of carboxylic acids exposed to Mars surface UV radiation conditions

    Science.gov (United States)

    Stalport, Fabien; Guan, Yuan Yong; Noblet, Audrey; Coll, Patrice; Szopa, Cyril; Macari, Frederique; Raulin, Francois; Chaput, Didier; Cottin, Hervé

    The detection and identification of organics at Mars are necessary to establish the existence of a possible ancient prebiotic chemistry or even a biological activity. Excepted methane, no organic matter was detected. The harsh environmental conditions on the surface could explain this non detection but only rare studies tested this hypothesis. To investigate the nature, abundance, and stability of organics that could survive under such conditions, we exposed in low Earth orbit organic molecules with martian astrobiological relevance to solar UV radiation ¿ 200 nm during 12 days, during the UVolution experiment, onboard the BIOPAN ESA module which was set outside a Russian Foton capsule. We also studied the photostability of these molecules in laboratory. Indeed we developed a laboratory experiment, MOMIE (Martian Organic Material Irradiation and Evolution) in order to investigate the behaviour of material related to Mars under UV radiation. The targeted molecules (AIB, mellitic, phthalic and trimesic acids) have been exposed with and without an analogous martian soil. Here, we present results with regard to the impact of solar UV radiation on the targeted molecules. Our results show that no sample seems to resist to UVs if directly exposed to them. Moreover, the presence of a mineral matrix seems to increases the photodestruction rate. These molecules should then not be considered as primary targets for in situ molecular analyses during future surface missions if samples are only collected at the top of the surface.

  8. Spectral Dependent Degradation of the Solar Diffuser on Suomi-NPP VIIRS Due to Surface Roughness-Induced Rayleigh Scattering

    Directory of Open Access Journals (Sweden)

    Xi Shao

    2016-03-01

    Full Text Available The Visible Infrared Imaging Radiometer Suite (VIIRS onboard Suomi National Polar Orbiting Partnership (SNPP uses a solar diffuser (SD as its radiometric calibrator for the reflective solar band calibration. The SD is made of Spectralon™ (one type of fluoropolymer and was chosen because of its controlled reflectance in the Visible/Near-Infrared/Shortwave-Infrared region and its near-Lambertian reflectance property. On-orbit changes in VIIRS SD reflectance as monitored by the Solar Diffuser Stability Monitor showed faster degradation of SD reflectance for 0.4 to 0.6 µm channels than the longer wavelength channels. Analysis of VIIRS SD reflectance data show that the spectral dependent degradation of SD reflectance in short wavelength can be explained with a SD Surface Roughness (length scale << wavelength based Rayleigh Scattering (SRRS model due to exposure to solar UV radiation and energetic particles. The characteristic length parameter of the SD surface roughness is derived from the long term reflectance data of the VIIRS SD and it changes at approximately the tens of nanometers level over the operational period of VIIRS. This estimated roughness length scale is consistent with the experimental result from radiation exposure of a fluoropolymer sample and validates the applicability of the Rayleigh scattering-based model. The model is also applicable to explaining the spectral dependent degradation of the SDs on other satellites. This novel approach allows us to better understand the physical processes of the SD degradation, and is complementary to previous mathematics based models.

  9. Application of UV-LED surface light source in PCB solder mask exposure%UV-LED面光源在PCB阻焊曝光中的应用

    Institute of Scientific and Technical Information of China (English)

    闵秀红

    2013-01-01

    In recent years, the development of the UV-LED, bring revolutionary changes in the field of PCB exposure. It is energy efficient and has constant light intensity, good temperature control, and almost zero maintenance cost. It promotes UV-LED surface light source replacing the traditional exposure lamp and becomes a trend.In accordance with the characteristics of the ultraviolet light source for PCB solder mask exposure process, this paper discusses not only the related technologies to overcome the difficulties in the promotion and application, but also provided solutions through experimental data, analysis of the factors of impact on the uniformity, the time and the resolution of UV-LED surface light source exposure. Using scanning mixed-wavelength UV-LED surface light source exposure mode, the practice shows that it is energy efficient, and the light intensity distribution is uniform and stable, is able to fully meet the requirements of the indicators of the anti-welds exposure process, and the maneuverability is strong, and it will play a catalytic role in the PCB exposure process for quality improvement and energy conservation.%  近年来随着UV-LED的问世,为印制电路板曝光领域带来革命性的变化。其高效节能、恒定的光照强度、优秀的温度控制、几乎为零的维护成本。促使UV-LED面光源替代传统曝光灯成为发展趋势。文章针对印制电路板阻焊曝光工艺紫外光源的特点,论述了推广应用中需要克服的相关技术及解决方法;并通过实验数据,分析出影响UV-LED面光源曝光均匀性、时间、解析度的因素。实践表明,采用扫描式、混合波长的UV-LED面光源曝光方式,高效节能、光强分布均匀稳定、能够完全满足阻焊曝光过程对光源的指标要求,可操作性强,对印制电路板曝光工艺的品质提升与节能降耗将起到推动作用。

  10. Phonon spectral densities of Cu surfaces: Application to Cu(211)

    Science.gov (United States)

    Mărinică, M.-C.; Raşeev, G.; Smirnov, K. S.

    2001-05-01

    Power phonon spectra of vicinal stepped surfaces of Cu(211) have been calculated using a molecular dynamics method combined with a semiempirical potential. The potential is based on an analytic form of inverse powers proposed by Finnis and Sinclair with the parametrization of Sutton and Chen. One of the four independent parameters of the potential was rescaled to reproduce the bulk phonon spectrum of Cu while retaining other properties of the bulk Cu close to the experimental values. Using this potential, we calculated the power surface phonon spectra, projection of the spectra at the high-symmetry points of surface Brillouin zone (SBZ), and the mean square displacements (MSD's) of atoms of the Cu(211) surface. The calculated projected phonon spectra at Γ¯ and at two new SBZ points (at X¯ and Y¯) compare favorably with experiment and theory when available. The MSD of the Cu(211) surface is also well reproduced and its temperature dependence shows that anharmonicity of the atomic motion becomes important above 200 K.

  11. Stratified spectral mixture analysis of medium resolution imagery for impervious surface mapping

    Science.gov (United States)

    Sun, Genyun; Chen, Xiaolin; Ren, Jinchang; Zhang, Aizhu; Jia, Xiuping

    2017-08-01

    Linear spectral mixture analysis (LSMA) is widely employed in impervious surface estimation, especially for estimating impervious surface abundance in medium spatial resolution images. However, it suffers from a difficulty in endmember selection due to within-class spectral variability and the variation in the number and the type of endmember classes contained from pixel to pixel, which may lead to over or under estimation of impervious surface. Stratification is considered as a promising process to address the problem. This paper presents a stratified spectral mixture analysis in spectral domain (Sp_SSMA) for impervious surface mapping. It categorizes the entire data into three groups based on the Combinational Build-up Index (CBI), the intensity component in the color space and the Normalized Difference Vegetation Index (NDVI) values. A suitable endmember model is developed for each group to accommodate the spectral variation from group to group. The unmixing into the associated subset (or full set) of endmembers in each group can make the unmixing adaptive to the types of endmember classes that each pixel actually contains. Results indicate that the Sp_SSMA method achieves a better performance than full-set-endmember SMA and prior-knowledge-based spectral mixture analysis (PKSMA) in terms of R, RMSE and SE.

  12. First Derivative UV Spectra of Surface Water as a Monitor of Chlorination in Drinking Water Treatment

    Directory of Open Access Journals (Sweden)

    V. Zitko

    2001-01-01

    Full Text Available Many countries require the presence of free chlorine at about 0.1 mg/l in their drinking water supplies. For various reasons, such as cast-iron pipes or long residence times in the distribution system, free chlorine may decrease below detection limits. In such cases it is important to know whether or not the water was chlorinated or if nonchlorinated water entered the system by accident. Changes in UV spectra of natural organic matter in lakewater were used to assess qualitatively the degree of chlorination in the treatment to produce drinking water. The changes were more obvious in the first derivative spectra. In lakewater, the derivative spectra have a maximum at about 280 nm. This maximum shifts to longer wavelengths by up to 10 nm, decreases, and eventually disappears with an increasing dose of chlorine. The water treatment system was monitored by this technique for over 1 year and changes in the UV spectra of water samples were compared with experimental samples treated with known amounts of chlorine. The changes of the UV spectra with the concentration of added chlorine are presented. On several occasions, water, which received very little or no chlorination, may have entered the drinking water system. The results show that first derivative spectra are potentially a tool to determine, in the absence of residual chlorine, whether or not surface water was chlorinated during the treatment to produce potable water.

  13. Photochemical behavior of benzo[a]pyrene on soil surfaces under UV light irradiation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li-hong; LI Pei-jun; GONG Zong-qiang; Oni Adeola A.

    2006-01-01

    The rates of photodegradation and photocatalysis of benzo [a]pyrene (BaP) on soil surfaces under UV light have been studied. Different parameters such as temperature, soil particle sizes, and soil depth responsible for photodegradation, catalyst loads and wavelength of UV irradiation blamed for photocatalysis have been monitored. The results obtained indicated that BaP photodegradation follows pseudo-first-order kinetics. BaP photodegradation was the fastest at 30℃. The rates of BaP photodegradation at different soil particle size followed the order: less than 1 mm>less than 0.45 mm>less than 0.25 mm. When the soil depth increased from 1 mm to 4 mm, the half-life increased from 13.23 d to 17.73 d. The additions of TiO2 or Fe2O3 accelerated the photodegradation of BaP, and the photocatalysis of BaP follows pseudo-first-order kinetics. Changes in catalyst loads of TiO2 (0.5%,1%, 2%, and 3% (wt)) or Fe2O3 (2%, 5%, 7%, and 10% (wt)) did not significantly affect the degradation rates. Both BaP photocatalysis in the presence of TiO2 and Fe2O3 were the fastest at 254 nm UV irradiation.

  14. Highly stable hydrophilic surfaces of PDMS thin layer obtained by UV radiation and oxygen plasma treatments

    Energy Technology Data Exchange (ETDEWEB)

    Menezes Atayde, Cleuson de; Doi, Ioshiaki [Center for Semiconductor Components, University of Campinas - UNICAMP, Campinas, SP (Brazil); School of Electrical and Computer Engineering, University of Campinas - UNICAMP, Campinas, SP (Brazil)

    2010-02-15

    Surface modification of polydimethylsiloxane (PDMS, Sylgard 184) was carried out by O{sub 2} plasma and UV in broadband mode/O{sub 2} plasma treatments with different exposure times, and studied in terms of hydrophilic stability. Water contact angle measurements, Fourier Transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) were used for the analysis of the modified surface and hydrophilic stability of the PDMS films. The results show reasonably good hydrophilic stability in the range of a week with a contact angle of around 70 for O{sub 2} plasma treated samples, whereas a more high hydrophilic stability, with a low contact angle of 65 up to 15 days, was observed for UV/O{sub 2} plasma treated PDMS. FTIR analysis of the samples reveals significant oxidation noted by large presence of Si-O-Si, and Si-OH bonds on the PDMS surface, which improves the affinity with water molecules and increases the hydrophilicy. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Surface coverage enhancement of a mixed halide perovskite film by using an UV-ozone treatment

    Science.gov (United States)

    Lee, Hyunho; Rhee, Seunghyun; Kim, Jaeyoul; Lee, Changhee; Kim, Hyeok

    2016-08-01

    Recently, a significant breakthrough in emerging photovoltaics occurred. Now, perovskite solar cells, hybrid types of organic and inorganic solar cells, are considered as reliable next-generation solar cells due to their outstanding photovoltaic performance. Records of the National Renewable Energy Laboratory (NREL) on cell efficiency research indicates a prominent growth in the power conversion efficiency (PCE) of a perovskite solar cells which is now approaching 20.1%. Perovskite solar cells are, in general, classified into three types based on their structures; the mesoporous type with TiO2 nanoparticles, the meso-superstructure type with Al2O3 and the planar hetero-junction type. Among them, planar-structured perovskite solar cells have strong advantages due to their easy processibility and flexibility. We can replace the materials in the electron transport layer (ETL) and the hole transport layer (HTL) with common materials that are available in organic solar cells. However, a great challenge is to fabricate a high-quality perovskite film because the perovskite morphology is highly sensitive to its fabrication conditions. For control of the film's morphology, some experiments, such as changing the annealing temperature or time and adding some additives, have been done to increase the surface coverage of perovskite films. In this work, we introduce normal, planar, perovskite solar cells with a hetero-junction structure based on compact TiO2 and a mixed halide perovskite (CH3NH3PbI3- x Cl x ). To enlarge the surface coverage of perovskite film, we used an UV-ozone treatment on top of the compact TiO2, which made the surface of TiO2 hydrophilic. Because a perovskite precursor is hydrophilic, an UV-ozone treatment is expected to improve the wettability between the compact TiO2 and the perovskite film. Here, we present the photovoltaic performance, along with the surface coverage difference, for various UV-ozone treatment time. In addition, the effect of the UV

  16. Shuttling of the autoantigen La between nucleus and cell surface after uv irradiation of human keratinocytes

    Energy Technology Data Exchange (ETDEWEB)

    Bachmann, M.; Chang, S.; Slor, H.; Kukulies, J.; Mueller, W.E. (Universitaet, Mainz (Germany, F.R.))

    1990-12-01

    During the past years we have established that the nuclear autoantigen La shuttles between the nucleus and the cytoplasm in tumor cells after inhibition of transcription or virus infection. We reinvestigated this shuttling using primary human keratinocytes from both healthy donors and patients with xeroderma pigmentosum. Ultraviolet irradiation resulted in both an inhibition of transcription and a translocation of La protein from the nucleus to the cytoplasm. After a prolonged inhibition of transcription La protein relocated into the nucleus and assembled with nuclear storage regions. The uv-induced shuttling included a translocation to the cell surface, where La protein colocalized with epidermal growth factor receptors.

  17. Spectral features in isolated neutron stars induced by inhomogeneous surface temperatures

    CERN Document Server

    Viganò, Daniele; Rea, Nanda; Pons, José A

    2014-01-01

    The thermal X-ray spectra of several isolated neutron stars display deviations from a pure blackbody. The accurate physical interpretation of these spectral features bears profound implications for our understanding of the atmospheric composition, magnetic field strength and topology, and equation of state of dense matter. With specific details varying from source to source, common explanations for the features have ranged from atomic transitions in the magnetized atmospheres or condensed surface, to cyclotron lines generated in a hot ionized layer near the surface. Here we quantitatively evaluate the X-ray spectral distortions induced by inhomogeneous temperature distributions of the neutron star surface. To this aim, we explore several surface temperature distributions, we simulate their corresponding general relativistic X-ray spectra (assuming an isotropic, blackbody emission), and fit the latter with a single blackbody model. We find that, in some cases, the presence of a spurious 'spectral line' is requ...

  18. The combined action of UV irradiation and chemical treatment on the titanium surface of dental implants

    Energy Technology Data Exchange (ETDEWEB)

    Spriano, Silvia [Politecnico di Torino, Department of Applied Science and Technology, Corso Duca degli Abruzzi, 24-10129 Torino (Italy); Ferraris, Sara, E-mail: sara.ferraris@polito.it [Politecnico di Torino, Department of Applied Science and Technology, Corso Duca degli Abruzzi, 24-10129 Torino (Italy); Bollati, Daniele; Morra, Marco; Cassinelli, Clara [Nobil Bio Ricerche, Portacomaro (Italy); Lorenzon, Giorgio [Centro Chirurgico, Via Mallonetto, 47, 10032, Brandizzo Torino (Italy)

    2015-09-15

    Highlights: • A combined UV irradiation and H{sub 2}O{sub 2} treatment was applied to titanium surfaces. • A thin, homogeneous, not porous, crack-free and bioactive oxide layer was obtained. • The process significantly improves the biological response of titanium surfaces. • A clinical case demonstrates the effectiveness of the proposed treatment. - Abstract: The purpose of this paper is to describe an innovative treatment for titanium dental implants, aimed at faster and more effective osteointegration. The treatment has been performed with the use of hydrogen peroxide, whose action was enhanced by concomitant exposure to a source of ultraviolet light. The developed surface oxide layer was characterized from the physical and chemical points of view. Moreover osteoblast-like SaOS2 cells were cultured on treated and control titanium surfaces and cell behavior investigated by scanning electron microscope observation and gene expression measurements. The described process produces, in only 6 min, a thin, homogeneous, not porous, free of cracks and bioactive (in vitro apatite precipitation) oxide layer. High cell density, peculiar morphology and overexpression of several genes involved with osteogenesis have been observed on modified surfaces. The proposed process significantly improves the biological response of titanium surfaces, and is an interesting solution for the improvement of bone integration of dental implants. A clinical application of the described surfaces, with a 5 years follow-up, is reported in the paper, as an example of the effectiveness of the proposed treatment.

  19. Variation of surface water spectral response as a function of in situ sampling technique

    Science.gov (United States)

    Davis, Bruce A.; Hodgson, Michael E.

    1988-01-01

    Tests were carried out to determine the spectral variation contributed by a particular sampling technique. A portable radiometer was used to measure the surface water spectral response. Variation due to the reflectance of objects near the radiometer (i.e., the boat side) during data acquisition was studied. Consideration was also given to the variation due to the temporal nature of the phenomena (i.e., wave activity).

  20. Formation of quasi-periodic nano- and microstructures on silicon surface under IR and UV femtosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Ionin, Andrei A; Golosov, E V; Kolobov, Yu R; Kudryashov, Sergei I; Ligachev, A E; Makarov, Sergei V; Novoselov, Yurii N; Seleznev, L V; Sinitsyn, D V

    2011-09-30

    Quasi-periodic nano- and microstructures have been formed on silicon surface using IR ( {lambda} Almost-Equal-To 744 nm) and UV ( {lambda} Almost-Equal-To 248 nm) femtosecond laser pulses. The influence of the incident energy density and the number of pulses on the structured surface topology has been investigated. The silicon nanostructurisation thresholds have been determined for the above-mentioned wavelengths. Modulation of the surface relief at the doubled spatial frequency is revealed and explained qualitatively. The periods of the nanostructures formed on the silicon surface under IR and UV femtosecond laser pulses are comparatively analysed and discussed.

  1. Theoretical and Experimental Study of Spectral Selectivity Surface for Both Solar Heating and Radiative Cooling

    Directory of Open Access Journals (Sweden)

    Mingke Hu

    2015-01-01

    Full Text Available A spectral selectivity surface for both solar heating and radiative cooling was proposed. It has a high spectral absorptivity (emissivity in the solar radiation band and atmospheric window band (i.e., 0.2~3 μm and 8~13 μm, as well as a low absorptivity (emissivity in other bands aside from the solar radiation and atmospheric window wavelengths (i.e., 3~8 μm or above 13 μm. A type of composite surface sample was trial-manufactured combining titanium-based solar selective absorbing coating with polyethylene terephthalate (TPET. Sample tests showed that the TPET composite surface has clear spectral selectivity in the spectra of solar heating and radiation cooling wavelengths. The equilibrium temperatures of the TPET surface under different sky conditions or different inclination angles of surface were tested at both day and night. Numerical analysis and comparisons among the TPET composite surface and three other typical surfaces were also performed. These comparisons indicated that the TPET composite surface had a relative heat efficiency of 76.8% of that of the conventional solar heating surface and a relative temperature difference of 75.0% of that of the conventional radiative cooling surface, with little difference in cooling power.

  2. MMA/DVB emulsion surface graft polymerization initiated by UV light.

    Science.gov (United States)

    Wang, Yongxin; Yang, Wantai

    2004-07-20

    Methyl methacrylate/1,2-divinylbenzene (MMA/DVB) in an opaque emulsion were successfully grafted onto the surface of polymeric substrate under the irradiation of UV light with benzophenone (BP) as a photoinitiator that was previously coated on the substrate surface. Monomer conversion, grafting efficiency, and grafting yields were determined by the gravimetric method. ATR-IR, AFM, and TEM were used to characterize the surface composition, to observe the topography of the grafted substrates, and to view inter-film colloid particles formed by cross-linking. The results reveal that, with the opaque MMA/DVB emulsion system and CPP film as substrate, the monomer conversion is in the range of 15-55%, the grafting efficiency is about 80%, the grafting yield reaches 5%, and the thickness of the graft layer can be controlled in the range 0.09-1.5 microm. Images of AFM show that the graft layer is piled up by nanoparticles (about 30-50 nm in diameter), which are linked together and tied to the substrate surface with covalent bonds. A possible model of surface graft polymerization including surface initiating, nucleation, and shish kebab growing is put forward to interpreting the above results.

  3. Surface modification induced by UV nanosecond Nd:YVO4 laser structuring on biometals

    Science.gov (United States)

    Fiorucci, M. Paula; López, Ana J.; Ramil, Alberto

    2014-08-01

    Laser surface texturing is a promising tool for improving metallic biomaterials performance in dental and orthopedic bone-replacing applications. Laser ablation modifies the topography of bulk material and might alter surface properties that govern the interactions with the surrounding tissue. This paper presents a preliminary evaluation of surface modifications in two biometals, stainless steel 316L and titanium alloy Ti6Al4V by UV nanosecond Nd:YVO4. Scanning electron microscopy of the surface textured by parallel micro-grooves reveals a thin layer of remelted material along the grooves topography. Furthermore, X-ray diffraction allowed us to appreciate a grain refinement of original crystal structure and consequently induced residual strain. Changes in the surface chemistry were determined by means of X-ray photoelectron spectroscopy; in this sense, generalized surface oxidation was observed and characterization of the oxides and other compounds such hydroxyl groups was reported. In case of titanium alloy, oxide layer mainly composed by TiO2 which is a highly biocompatible compound was identified. Furthermore, laser treatment produces an increase in oxide thickness that could improve the corrosion behavior of the metal. Otherwise, laser treatment led to the formation of secondary phases which might be detrimental to physical and biocompatibility properties of the material.

  4. Modified surface morphology in surface ablation of cobalt-cemented tungsten carbide with pulsed UV laser radiation

    Science.gov (United States)

    Li, Tiejun; Lou, Qihong; Dong, Jingxing; Wei, Yunrong; Liu, Jingru

    2001-03-01

    Surface ablation of cobalt-cemented tungsten carbide hardmetal has been carried out in this work using a 308 nm, 20 ns XeCl excimer laser. The influence of ablation rate, surface roughness, surface micromorphology as well as surface phase structure on laser conditions including laser irradiance and pulse number have been investigated. The experimental results showed that the ablation rate and surface roughness were controlled by varying the number of pulses and laser irradiance. The microstructure and crystalline structure of irradiated surface layer varied greatly with different laser conditions. After 300 shots of laser irradiation at irradiance of 125 MW/cm 2, the surface micromorphology characterizing a uniform framework pattern of "hill-valleys". With the increment of laser shots at laser irradiance of 125 MW/cm 2, the microstructure of cemented tungsten carbide transformed from original polygon grains with the size of 3 μm to interlaced large and long grains after 300 shots of laser irradiation, and finally to gross grains with the size of 10 μm with clear grain boundaries after 700 shots. The crystalline structure of irradiated area has partly transformed from original WC to β-WC 1- x, then to α-W 2C and CW 3, and finally to W crystal. At proper laser irradiance and pulse number, cobalt binder has been selectively removed from the surface layer of hardmetal. It has been demonstrated that surface ablation with pulsed UV laser should be a feasible way to selectively remove cobalt binder from surface layer of cemented tungsten carbide hardmetal.

  5. The UV-A and visible solar irradiance spectrum: inter-comparison of absolutely calibrated, spectrally medium resolution solar irradiance spectra from balloon- and satellite-borne measurements

    Directory of Open Access Journals (Sweden)

    W. Gurlit

    2005-01-01

    Full Text Available Within the framework of the ENVISAT/-SCIAMACHY satellite validation, solar irradiance spectra are absolutely measured at moderate resolution in the UV/visible spectral range (in the UV from 316.7-418 nm and the visible from 400-652 nm at a full width half maximum resolution of 0.55 nm and 1.48 nm, respectively from aboard the azimuth-controlled LPMA/DOAS balloon gondola at around 32 km balloon float altitude. After accounting for the atmospheric extinction due to Rayleigh scattering and gaseous absorption (O3 and NO2, the measured solar spectra are compared with previous observations. Our solar irradiance spectrum perfectly agrees within +0.03% with the re-calibrated Kurucz et al. (1984 solar spectrum (Fontenla et al., 1999, called MODTRAN 3.7 in the visible spectral range (415-650 nm, but it is +2.1% larger in the (370-415 nm wavelength interval, and -4% smaller in the UV-A spectral range (316.7-370 nm, when the Kurucz spectrum is convolved to the spectral resolution of our instrument. Similar comparisons of the SOLSPEC (Thuillier et al., 1997, 1998a, b and SORCE/SIM (Harder et al., 2000 solar spectra with MODTRAN 3.7 confirms our findings with the values being -0.5%, +2%, and -1.4% for SOLSPEC -0.33%, -0.47%, and -6.2% for SORCE/SIM, respectively. Comparison of the SCIAMACHY solar spectrum from channels 1 to 4 (- re-calibrated by the University of Bremen - with MODTRAN 3.7 indicates an agreement within -0.4% in the visible spectral range (415-585 nm, -1.6% within the 370-415 nm, and -5.7% within 325-370 nm wavelength interval, in agreement with the results of the other sensors. In agreement with findings of Skupin et al. (2002 our study emphasizes that the present ESA SCIAMACHY level 1 calibration is systematically +15% larger in the considered wavelength intervals when compared to all available other solar irradiance measurements.

  6. Surface modification of polycarbonate and polyethylene naphtalate foils by UV-ozone treatment and μPlasma printing

    Science.gov (United States)

    Verkuijlen, R. O. F.; van Dongen, M. H. A.; Stevens, A. A. E.; van Geldrop, J.; Bernards, J. P. C.

    2014-01-01

    In this study, we investigated the effect of UV-ozone and μPlasma printing on surface modification of polycarbonate (PC) and polyethylene naphthalate (PEN). The effects on the wetting behaviour was studied, in terms of surface energy and chemical modification of the treated substrate, by analysis of attenuated total reflectance-Fourier transform infrared spectrometry (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). Both UV-ozone and μPlasma printing are effective ways to modify the wettability of both polymer substrates, substantially increasing the wetting envelope after a short treatment period. This increase is primarily due to an increase of the polar part of the surface energy. This is confirmed by ATR-FTIR and XPS, which show the formation of oxygen containing groups as well as a decrease in the aromatic Csbnd C bonds on the surface of the substrate due to the treatment. For both types of surface treatment, prolonged exposure showed no further increase in wettability, although continuous change in chemical composition of the surface was measured. This effect is more evident for UV-ozone treatment, as a larger increase in O/C ratio of the surface was measured as compared to μPlasma printing. It can be concluded that μPlasma printing results in a more chemically selective modification as compared to UV-ozone. In the case that chemical selectivity and treatment time are considered important, μPlasma printing is favourable over UV-ozone.

  7. Surface modification of polycarbonate and polyethylene naphtalate foils by UV-ozone treatment and μPlasma printing

    Energy Technology Data Exchange (ETDEWEB)

    Verkuijlen, R.O.F. [Expertise Centre Thin Films and Functional Materials, Fontys University of Applied Sciences, 5600 AH Eindhoven (Netherlands); Dongen, M.H.A. van, E-mail: mha.vandongen@fontys.nl [Expertise Centre Thin Films and Functional Materials, Fontys University of Applied Sciences, 5600 AH Eindhoven (Netherlands); Stevens, A.A.E. [InnoPhysicsB.V., 5627 JM Eindhoven (Netherlands); Geldrop, J. van; Bernards, J.P.C. [Expertise Centre Thin Films and Functional Materials, Fontys University of Applied Sciences, 5600 AH Eindhoven (Netherlands)

    2014-01-30

    In this study, we investigated the effect of UV-ozone and μPlasma printing on surface modification of polycarbonate (PC) and polyethylene naphthalate (PEN). The effects on the wetting behaviour was studied, in terms of surface energy and chemical modification of the treated substrate, by analysis of attenuated total reflectance-Fourier transform infrared spectrometry (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). Both UV-ozone and μPlasma printing are effective ways to modify the wettability of both polymer substrates, substantially increasing the wetting envelope after a short treatment period. This increase is primarily due to an increase of the polar part of the surface energy. This is confirmed by ATR-FTIR and XPS, which show the formation of oxygen containing groups as well as a decrease in the aromatic C-C bonds on the surface of the substrate due to the treatment. For both types of surface treatment, prolonged exposure showed no further increase in wettability, although continuous change in chemical composition of the surface was measured. This effect is more evident for UV-ozone treatment, as a larger increase in O/C ratio of the surface was measured as compared to μPlasma printing. It can be concluded that μPlasma printing results in a more chemically selective modification as compared to UV-ozone. In the case that chemical selectivity and treatment time are considered important, μPlasma printing is favourable over UV-ozone.

  8. Mapping the low surface brightness Universe in the UV band with Lya emission from IGM filaments

    CERN Document Server

    Silva, Marta B; Zaroubi, Saleem

    2016-01-01

    A large fraction of the baryonic matter in the Universe is located in filaments in the intergalactic medium. However, the low surface brightness of these filaments has not yet allowed their direct detection except in very special regions in the circum-galactic medium (CGM). Here we simulate the intensity and spatial fluctuations in Lyman Alpha ${\\rm (Ly\\alpha)}$ emission from filaments in the intergalactic medium (IGM) and discuss the prospects for the next generation of space based instruments to detect the low surface brightness universe at UV wavelengths. Starting with a high resolution N-body simulation we obtain the dark matter density fluctuations and associate baryons with the dark matter particles assuming that they follow the same spatial distribution. The IGM thermal and ionization state is set by a model of the UV background and by the relevant cooling processes for a hydrogen and helium gas. The ${\\rm Ly\\alpha}$ emissivity is then estimated, taking into account recombination and collisional excita...

  9. Study of micro and nano surface structures from UV irradiated urethane/urea elastomers.

    Science.gov (United States)

    Godinho, M H; Trindade, A C; Figueirinhas, J L; Melo, L V; Brogueira, P

    2007-02-01

    In this work we address new results obtained with a thin free standing flexible film (approximately 120 microm) of a urethane/urea copolymer related to the formation of micro and nano size structures [M.H. Godinho, A.C. Trindade, J.L. Figueirinhas, L.V. Melo, P. Brogueira, Synthetic Metals, 147(1-3), 209 (2004); M.H. Godinho, A.C. Trindade, J.L. Figueirinhas, L.V. Melo, P. Brogueira, Molecular Crystals and Liquid Crystals (2005)]. The copolymer was synthesized from a polypropylene oxide-based prepolymer with three isocyanate terminal groups (PU) and polybutadienediol (PBDO) with PBDO content of 40% wt. After casting and curing the film was cut into different samples and each exposed to UV radiation for different periods of time; 23, 25, 26, 31 and 49 h (lambda=254 nm) and later extracted with toluene and dried. The dried films were then studied by polarising optical microscopy (POM), small angle light scattering (SALS) and the surfaces exposed to UV radiation analyzed by means of atomic force microscopy (AFM). Before extraction with toluene a nanometer-flat surface, characterized by a mean roughness value Ra=0.59 nm, was obtained. Depending on exposure time to UV radiation and after extraction with toluene a corrugated surface, with features mum-sized in all axes, resulting in an increase of the overall mean roughness value to Ra=50.7 nm, starts to develop after 25 h of exposure time. This work gives evidence of the non-monotonous time behavior of the wrinkled surface growth that develops under the action of ultraviolet radiation. As the exposure time increases the free-standing films directly exposed surfaces show a decreasing density of the structures observed and an increasing characteristic peak-to-valley height. The peak-to-valley height measured for samples exposed for 23, 25, 26, 31 and 49 h, respectively 193, 383, 381, 1550 and 2039 nm and the corresponding mean roughness values are Ra=50.7 nm, 105.4, 116.8, 438.3 and 515.4 nm, respectively. Between 26 and

  10. Sensitivity of Biosignatures on Earth-like Planets orbiting in the Habitable Zone of Cool M-Dwarf Stars to varying Stellar UV Radiation and Surface Biomass Emissions

    CERN Document Server

    Grenfell, John Lee; von Paris, Philip; Godolt, Mareike; Rauer, Heike

    2015-01-01

    We find that variations in the UV emissions of cool M-dwarf stars have a potentially large impact upon atmospheric biosignatures in simulations of Earth-like exoplanets i.e. planets with Earths development, and biomass and a molecular nitrogen-oxygen dominated atmosphere. Starting with an assumed black-body stellar emission for an M7 class dwarf star, the stellar UV irradiation was increased stepwise and the resulting climate-photochemical response of the planetary atmosphere was calculated. Results suggest a Goldilocks effect with respect to the spectral detection of ozone. At weak UV levels, the ozone column was weak (due to weaker production from the Chapman mechanism) hence its spectral detection was challenging. At strong UV levels, ozone formation is stronger but its associated stratospheric heating leads to a weakening in temperature gradients between the stratosphere and troposphere, which results in weakened spectral bands. Also, increased UV levels can lead to enhanced abundances of hydrogen oxides ...

  11. Structural origin of surface transformations in arsenic sulfide thin films upon UV-irradiation

    Science.gov (United States)

    Kovalskiy, Andriy; Vlcek, Miroslav; Palka, Karel; Buzek, Jan; York-Winegar, James; Oelgoetz, Justin; Golovchak, Roman; Shpotyuk, Oleh; Jain, Himanshu

    2017-02-01

    Photostructural transformations within AsxS100-x (x = 30, 33, 35, 40) thin films upon exposure to LED light of different wavelengths, in both air and argon environments have been studied by high resolution XPS, Raman spectroscopy and LEIS methods. These complementary results show that light of energies close to the band gap does not modify chemical composition of the surface, but induces simple photopolymerization reactions. Superbandgap UV light, however, significantly increases S/As ratio on the surface due to formation of S-rich layer under both environmental conditions. It is proposed that photovaporization of both oxide and non-oxide cage-like molecules is responsible for the observed effect.

  12. Determination of the Wenzel roughness parameter by the Power Spectral Density of functional Alumina surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jardim, P.L.G., E-mail: pedro.lovato@ufrgs.br [Programa de Pós-Graduação em Microeletrônica, Instituto de Física da Universidade Federal do Rio Grande do Sul, CEP. 91501-970 Porto Alegre (Brazil); Horowitz, F. [Programa de Pós-Graduação em Microeletrônica, Instituto de Física da Universidade Federal do Rio Grande do Sul, CEP. 91501-970 Porto Alegre (Brazil); Felde, N.; Schröder, S.; Coriand, L.; Duparré, A. [Fraunhofer Institute for Applied Optics and Precision Engineering, D 07745 Jena (Germany)

    2016-05-01

    The Wenzel roughness parameter of isotropic Gaussian surfaces is analytically described in terms of the Power Spectral Density function without the smooth surface approximation. This Wenzel roughness parameter — Power Spectral Density link was examined for distinct roughnesses of Aluminum-oxide thin films. The Power Spectral Density functions of the surfaces were determined in a wide spatial frequency range by combining different scan areas of Atomic Force Microscopy measurements. The calculated results presented a good agreement with the Wenzel roughness parameter values obtained directly from the topography measured by Atomic Force Microscopy. Finally, wetting behavior was ascertained through determination of water contact angles, including superhydrophobic behavior. This approach, together with an empirical procedure based on a structural parameter, can predict the wetting properties of a surface by taking all its relevant roughness components into account. - Highlights: • Wenzel roughness parameter and Power Spectral Density are theoretically linked. • The formula is tested for Alumina surfaces with distinct roughnesses. • The formula agrees with the experimental data from Atomic Force Microscopy. • The proper contribution of topography in surface wetting can be ascertained.

  13. Spectral (FT-IR, FT-Raman, UV, and fluorescence), DFT, and solid state interaction analyses of (E)-4-(3,4-dimethoxybenzylideneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one

    Science.gov (United States)

    Alam, Mohammad Sayed; Lee, Dong-Ung

    2017-01-01

    Here, the authors report a combined experimental and theoretical study on the molecular structure and vibrational spectral analyses of (E)-4-(3,4-dimethoxybenzylideneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (DMBADPP), a pyrazolone-based bioactive molecule. Density functional theory (DFT) calculations were carried out to obtain the ground state optimized geometry of the molecule using the B3LYP method and the 6-311G(d,p) basis set. Calculated results agreed well with X-ray data. The vibrational spectra of DMBADPP were calculated at the same level of theory and theoretical scaled vibrational frequencies and assignments were found to agree well with experimental FT-IR and FT-Raman values. Partial atomic charge and molecular electrostatic potential (MEP) surface map analyses were performed to study reactive sites. Calculated frontier molecular orbitals (FMOs) energies and chemical reactivity parameters indicated that the DMBADPP exhibits high polarizability and low kinetic susceptibility. Excitation energy, wavelength, and oscillator strength were calculated using the Time Dependant-DFT/B3LYP/6-311G(d,p) method and compared with experimental UV-Vis spectra obtained in ethanol. However, UV-Vis and fluorescence spectroscopic experiments showed that DMBADPP has good absorption and fluorescent properties and a large Stokes shift. In addition, the solid state behaviors of molecules in crystals were analyzed quantitatively and qualitatively using 3D Hirshfeld surface analysis and associated 2D fingerprint plots.

  14. Analysis of galaxy spectral energy distributions from far-UV to far-IR with CIGALE: studying a SINGS test sample

    Science.gov (United States)

    Noll, S.; Burgarella, D.; Giovannoli, E.; Buat, V.; Marcillac, D.; Muñoz-Mateos, J. C.

    2009-12-01

    Aims: Photometric data of galaxies covering the rest-frame wavelength range from far-UV to far-IR make it possible to derive galaxy properties with a high reliability by fitting the attenuated stellar emission and the related dust emission at the same time. Methods: For this purpose we wrote the code CIGALE (Code Investigating GALaxy Emission) that uses model spectra composed of the Maraston (or PEGASE) stellar population models, synthetic attenuation functions based on a modified Calzetti law, spectral line templates, the Dale & Helou dust emission models, and optional spectral templates of obscured AGN. Depending on the input redshifts, filter fluxes were computed for the model set and compared to the galaxy photometry by carrying out a Bayesian-like analysis. CIGALE was tested by analysing 39 nearby galaxies selected from SINGS. The reliability of the different model parameters was evaluated by studying the resulting expectation values and their standard deviations in relation to the input model grid. Moreover, the influence of the filter set and the quality of photometric data on the code results was estimated. Results: For up to 17 filters with effective wavelengths between 0.15 and 160 μm, we find robust results for the mass, star formation rate, effective age of the stellar population at 4000 Å, bolometric luminosity, luminosity absorbed by dust, and attenuation in the far-UV. Details of the star formation history (excepting the burst fraction) and the shape of the attenuation curve are difficult to investigate with the available broad-band UV and optical photometric data. A study of the mutual relations between the reliable properties confirms the dependence of star formation activity on morphology in the local Universe and indicates a significant drop in this activity at about 1011 M⊙ towards higher total stellar masses. The dustiest galaxies in the SINGS sample are present in the same mass range. On the other hand, the far-UV attenuation of our sample

  15. Hydrophobic recovery of UV/ozone treated poly(dimethylsiloxane): adhesion studies by contact mechanics and mechanism of surface modification

    NARCIS (Netherlands)

    Oláh, Attila; Hillborg, Henrik; Vancso, G. Julius

    2005-01-01

    Silicone elastomers (Sylgard 184 and 170), based on poly(dimethylsiloxane) (PDMS), were surface treated by a combined exposure to UV and ozone. The effects of the treatments were analyzed as a function of time elapsed after stopping the treatments using different standard surface characterization te

  16. Slide-free histology via MUSE: UV surface excitation microscopy for imaging unsectioned tissue (Conference Presentation)

    Science.gov (United States)

    Levenson, Richard M.; Harmany, Zachary; Demos, Stavros G.; Fereidouni, Farzad

    2016-03-01

    Widely used methods for preparing and viewing tissue specimens at microscopic resolution have not changed for over a century. They provide high-quality images but can involve time-frames of hours or even weeks, depending on logistics. There is increasing interest in slide-free methods for rapid tissue analysis that can both decrease turn-around times and reduce costs. One new approach is MUSE (microscopy with UV surface excitation), which exploits the shallow penetration of UV light to excite fluorescent signals from only the most superficial tissue elements. The method is non-destructive, and eliminates requirement for conventional histology processing, formalin fixation, paraffin embedding, or thin sectioning. It requires no lasers, confocal, multiphoton or optical coherence tomography optics. MUSE generates diagnostic-quality histological images that can be rendered to resemble conventional hematoxylin- and eosin-stained samples, with enhanced topographical information, from fresh or fixed, but unsectioned tissue, rapidly, with high resolution, simply and inexpensively. We anticipate that there could be widespread adoption in research facilities, hospital-based and stand-alone clinical settings, in local or regional pathology labs, as well as in low-resource environments.

  17. Diverse policy implications for future ozone and surface UV in a changing climate

    Science.gov (United States)

    Butler, A. H.; Daniel, J. S.; Portmann, R. W.; Ravishankara, A. R.; Young, P. J.; Fahey, D. W.; Rosenlof, K. H.

    2016-06-01

    Due to the success of the Montreal Protocol in limiting emissions of ozone-depleting substances, concentrations of atmospheric carbon dioxide, nitrous oxide, and methane will control the evolution of total column and stratospheric ozone by the latter half of the 21st century. As the world proceeds down the path of reducing climate forcing set forth by the 2015 Conference of the Parties to the United Nations Framework Convention on Climate Change (COP 21), a broad range of ozone changes are possible depending on future policies enacted. While decreases in tropical stratospheric ozone will likely persist regardless of the future emissions scenario, extratropical ozone could either remain weakly depleted or even increase well above historical levels, with diverse implication for ultraviolet (UV) radiation. The ozone layer’s dependence on future emissions of these gases creates a complex policy decision space for protecting humans and ecosystems, which includes unexpected options such as accepting nitrous oxide emissions in order to maintain historical column ozone and surface UV levels.

  18. UV surface modification of a new nanocomposite polymer to improve cytocompatibility.

    Science.gov (United States)

    Olbrich, Michael; Punshon, Geoffrey; Frischauf, Irene; Salacinski, Henryk J; Rebollar, Esther; Romanin, Christoph; Seifalian, Alexander M; Heitz, Johannes

    2007-01-01

    A novel modified nanocomposite was studied for the adhesion and proliferation of the human umbilical vein endothelial cell (HUVEC) line EA.hy926. The nanocomposite under investigation was poly(carbonate-urea)urethane with silsesquioxane nano-cages, here in the form of a mixture of two polyhedral oligomeric silsesquioxanes. The nanocomposite surfaces were exposed to ultraviolet (UV) light of a Xe(*)(2)-excimer lamp at a wavelength of 172 nm in an ammonia atmosphere. The effects of the irradiation were characterized by atomic force and scanning electron microscopy (AFM, SEM), X-ray photo-electron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR) using an attenuated total reflection (ATR) device and measurements of advancing water contact angle (CA). The irradiation resulted in the introduction of new hydrophilic N- and O-containing groups into the surface, which was initially amphiphilic, while surface morphology remained mainly unchanged. Slight chemical changes were also observed for the silsesquioxane nano-cages at the surface. Onto the untreated and irradiated samples HUVECs were seeded and grown for various durations in culture. Standard tissue-culture polystyrene (PS) was employed as a positive control to check the efficiency of the cell-culture methods. Viability and proliferation of the cells were then assessed using a non-radioactive assay. Compared to the untreated nanocomposite polymer, irradiation times of at least 5 min resulted in a significantly increased cell proliferation between 3 and 8 days after seeding with the HUVEC line EA.hy926.

  19. UV surface brightness of galaxies from the local Universe to z ~ 5

    CERN Document Server

    Lerner, Eric J; Scarpa, Riccardo

    2014-01-01

    The Tolman test for surface brightness dimming was originally proposed as a test for the expansion of the Universe. The test, which is independent of the details of the assumed cosmology,is based on comparisons of the surface brightness (SB) of identical objects at different cosmological distances. Claims have been made that the Tolman test provides compelling evidence against a static model for the Universe. In this paper we reconsider this subject by adopting a static Euclidean Universe with a linear Hubble relation at all z (which is not the standard Einstein- de Sitter model),resulting in a relation between flux and luminosity that is virtually indistinguishable from the one used for LCDM models. Based on the analysis of the UV surface brightness of luminous disk galaxies from HUDF and GALEX datasets, reaching from the local Universe to z ~ 5 we show that the surface brightness remains constant as expected in a SEU. A re-analysis of previously-published data used for the Tolman test at lower redshift, whe...

  20. Development of a low-cost, 11 µm spectral domain optical coherence tomography surface profilometry prototype

    Science.gov (United States)

    Suliali, Nyasha J.; Baricholo, Peter; Neethling, Pieter H.; Rohwer, Erich G.

    2017-06-01

    A spectral-domain Optical Coherence Tomography (OCT) surface profilometry prototype has been developed for the purpose of surface metrology of optical elements. The prototype consists of a light source, spectral interferometer, sample fixture and software currently running on Microsoft® Windows platforms. In this system, a broadband light emitting diode beam is focused into a Michelson interferometer with a plane mirror as its sample fixture. At the interferometer output, spectral interferograms of broadband sources were measured using a Czerny-Turner mount monochromator with a 2048-element complementary metal oxide semiconductor linear array as the detector. The software performs importation and interpolation of interferometer spectra to pre-condition the data for image computation. One dimensional axial OCT images were computed by Fourier transformation of the measured spectra. A first reflection surface profilometry (FRSP) algorithm was then formulated to perform imaging of step-function-surfaced samples. The algorithm re-constructs two dimensional colour-scaled slice images by concatenation of 21 and 13 axial scans to form a 10 mm and 3.0 mm slice respectively. Measured spectral interferograms, computed interference fringe signals and depth reflectivity profiles were comparable to simulations and correlated to displacements of a single reflector linearly translated about the arm null-mismatch point. Surface profile images of a double-step-function-surfaced sample, embedded with inclination and crack detail were plotted with an axial resolution of 11 μm. The surface shape, defects and misalignment relative to the incident beam were detected to the order of a micron, confirming high resolution of the developed system as compared to electro-mechanical surface profilometry techniques.

  1. UV/PAR radiations and DOM properties in surface coastal waters of the Canadian shelf of the Beaufort Sea during summer 2009

    Directory of Open Access Journals (Sweden)

    J. Para

    2012-11-01

    Full Text Available Water masses from the Beaufort Sea in the Arctic Ocean were evaluated for dissolved organic carbon (DOC, and optical characteristics including UV and PAR diffuse attenuation (Kd, and chromophoric and fluorescent dissolved organic matter (CDOM and FDOM as part of the MALINA field campaign (30 July to 27 August. Even with relatively low mean daily solar radiation incident on the sea surface (0.12 ± 0.03, 8.46 ± 1.64 and 18.09 ± 4.20 kJ m−2 for UV-B (305 nm, UV-A (380 nm and PAR, respectively, we report significant light penetration with 10% irradiance depths (Z10% (λ reaching 9.5 m for 340 nm (UV-A radiation in the Eastern sector and 4.5 m in the Mackenzie River influenced area (Western sector. Spectral absorption coefficients (aCDOM (350 nm (m−1 were significantly correlated to both diffuse attenuation coefficients (Kd in the UV-A and UV-B and to DOC concentrations. This indicates CDOM as the dominant attenuator of UV solar radiation and suggests its use as an optical proxy for DOC concentrations in this region. Extrapolating CDOM to DOC relationships, we estimate that ~ 16% of the DOC in the Mackenzie River does not absorb radiation at 350 nm. DOC and CDOM discharges by the Mackenzie River during the MALINA Cruise are estimated as ~ 0.22 TgC and 0.18 TgC, respectively. Three dissolved fluorescent components (C1–C3 were identified by fluorescence Excitation/Emission Matrix Spectroscopy (EEMS and PARAFAC analysis. Our results showed an in-situ biological component (C1 that co-dominated with a terrestrial humic-like component (C2 in the Mackenzie Delta sector, whereas the protein-like (C3 component dominated in the saltiest waters of the North East sector.

  2. Estimating and Mapping Urban Impervious Surfaces: Reflection on Spectral, Spatial, and Temporal Resolutions

    Science.gov (United States)

    Weng, Q.

    2007-12-01

    Impervious surface is a key indicator of urban environmental quality and urbanization degree. Therefore, estimation and mapping of impervious surfaces in urban areas has attracted more and more attention recently by using remote sensing digital images. In this paper, satellite images with various spectral, spatial, and temporal resolutions are employed to examine the effects of these remote sensing data characteristics on mapping accuracy of urban impervious surfaces. The study area was the city proper of Indianapolis (Marion County), Indiana, United States. Linear spectral mixture analysis was applied to generate high albedo, low albedo, vegetation, and soil fraction images (endmembers) from the satellite images, and impervious surfaces were then estimated by adding high albedo and low albedo fraction images. A comparison of EO-1 ALI (multispectral) and Hyperion (hyperspectral) images indicates that the Hyperion image was more effective in discerning low albedo surface materials, especially the spectral bands in the mid-infrared region. Linear spectral mixing modeling was found more useful for medium spatial resolution images, such as Landsat TM/ETM+ and ASTER images, due to the existence of a large amount of mixed pixels in the urban areas. The model, however, may not be suitable for high spatial resolution images, such as IKONOS images, because of less influence from the mixing pixel. The shadow problem in the high spatial resolution images, caused by tall buildings and large tree crowns, is a challenge in impervious surface extraction. Alternative image processing algorithms such as decision tree classifier may be more appropriate to achieve high mapping accuracy. For mid-latitude cities, seasonal vegetation phenology has a significant effect on the spectral response of terrestrial features, and therefore, image analysis must take into account of this environmental characteristic. Three ASTER images, acquired on April 5, 2004, June 16, 2001, and October 3, 2000

  3. Capturing latent fingerprints from metallic painted surfaces using UV-VIS spectroscope

    Science.gov (United States)

    Makrushin, Andrey; Scheidat, Tobias; Vielhauer, Claus

    2015-03-01

    In digital crime scene forensics, contactless non-destructive detection and acquisition of latent fingerprints by means of optical devices such as a high-resolution digital camera, confocal microscope, or chromatic white-light sensor is the initial step prior to destructive chemical development. The applicability of an optical sensor to digitalize latent fingerprints primarily depends on reflection properties of a substrate. Metallic painted surfaces, for instance, pose a problem for conventional sensors which make use of visible light. Since metallic paint is a semi-transparent layer on top of the surface, visible light penetrates it and is reflected off of the metallic flakes randomly disposed in the paint. Fingerprint residues do not impede light beams making ridges invisible. Latent fingerprints can be revealed, however, using ultraviolet light which does not penetrate the paint. We apply a UV-VIS spectroscope that is capable of capturing images within the range from 163 to 844 nm using 2048 discrete levels. We empirically show that latent fingerprints left behind on metallic painted surfaces become clearly visible within the range from 205 to 385 nm. Our proposed streakiness score feature determining the proportion of a ridge-valley pattern in an image is applied for automatic assessment of a fingerprint's visibility and distinguishing between fingerprint and empty regions. The experiments are carried out with 100 fingerprint and 100 non-fingerprint samples.

  4. A spectral formalism for computing three-dimensional deformations due to surface loads. 1: Theory

    Science.gov (United States)

    Mitrovica, J. X.; Davis, J. L.; Shapiro, I. I.

    1994-01-01

    We outline a complete spectral formalism for computing high spatial resolution three-dimensional deformations arising from the surface mass loading of a spherically symmetric planet. The main advantages of the formalism are that all surface mass loads are always described using a consistent mathematical representation and that calculations of deformation fields for various spatial resolutions can be performed by simpley altering the spherical harmonic degree truncation level of the procedure. The latter may be important when incorporating improved observational constraints on a particular surface mass load, when considering potential errors in the computed field associated with mass loading having a spatial scale unresolved by the observational constraints, or when treating a number of global surface mass loads constrained with different spatial resolutions. The advantages do not extend to traditional 'Green's function' approaches which involve surface element discretizations of the global mass loads. Another advantage of the spectral formalism, over the Green's function approach, is that a posteriori analyses of the computed deformation fields are easily performed. In developing the spectral formalism, we consider specific cases where the Earth's mantle is assumed to respond as an elastic, slightly anelastic, or linear viscoelastic medium. In the case of an elastic or slightly anelastic mantle rheology the spectral response equations incorporate frequency dependent Love numbers. The formalism can therefore be used, for example, to compute the potentially resonant deformational response associated with the free core nutation and Chandler wobble eigenfunctions. For completeness, the spectral response equations include both body forces, as arise from the gravitational attraction of the Sun and the Moon, and surface mass loads. In either case, and for both elastic and anelastic mantle rheologies, we outline a pseudo-spectral technique for computing the ocean

  5. Effect of Vacuum on the Occurrence of UV-Induced Surface Photoluminescence, Transmission Loss, and Catastrophic Surface Damage

    Energy Technology Data Exchange (ETDEWEB)

    Burnham, A K; Runkel, M; Demos, S G; Kozlowski, M R; Wegner, P J

    2000-07-20

    Vacuum degrades the transmittance and catastrophic damage performance of fused-silica surfaces, both bare and silica-sol anti-reflective coated. These effects may be important in certain space application of photonics devices. When exposed to hundreds of 355-rim, 10-ns laser pulses with fluences in the 2-15 J/cm{sup 2} range, transmittance loss is due to both increased reflectance and absorption at the surface. Spectroscopic measurements show that the absorbed light induces broadband fluorescence from the visible to infrared and that the peak photoluminescence wavelength depends cumulative fluence. The effect appears to be consistent with the formation of surface SiO{sub x} (x<2) with progressively lower x as cumulative fluence increases. Conversely, low fluence CW UV irradiation of fluorescent sites in air reduces the fluorescence signal, which suggests a photochemical oxidation reaction back to Si0{sub 2}. The occurrence of catastrophic damage (craters that grow on each subsequent pulse) also increases in a vacuum relative to air for both coated and uncoated samples. In both cases, the 50% damage probability for 100 one-mm sites decreases from about 45 to 35 J/cm{sup 2} for superpolished fused silica at pressures in the 10{sup -6} Torr range. The damage probability distribution in 10 Torr of air is close to that at one atmosphere of air. The damage morphology of the crater formed in vacuum differs substantially from that in air and has a more melted appearance and does not show cracking and flaking. These differences are possibly due to more coupling of the plasma shock wave into the surface with air present but slower heat dissipation in a vacuum. While it is attractive to propose that formation of sub-stoichiometric silica on the surface in a vacuum environment enhances the probability of catastrophic damage, initial experiments have not yet been able to establish a mechanistic link between the two phenomena.

  6. Spectral Approximation of an Oldroyd Liquid Draining down a Porous Vertical Surface

    Directory of Open Access Journals (Sweden)

    F. Talay Akyildiz

    2011-01-01

    Full Text Available Consideration is given to the free drainage of an Oldroyd four-constant liquid from a vertical porous surface. The governing systems of quasilinear partial differential equations are solved by the Fourier-Galerkin spectral method. It is shown that Fourier-Galerkin approximations are convergent with spectral accuracy. An efficient and accurate algorithm based on the Fourier-Galerkin approximations for the governing system of quasilinear partial differential equations is developed and implemented. Numerical results indicating the high accuracy and effectiveness of this algorithm are presented. The effect of the material parameters, elasticity, and porous medium constant on the centerline velocity and drainage rate is discussed.

  7. Spectrally selective surfaces for ground and space-based instrumentation: support for a resource base

    Science.gov (United States)

    McCall, Susan H.; Sinclair, R. Lawrence; Pompea, Stephen M.; Breault, Robert P.

    1993-11-01

    The performance of space telescopes, space instruments, and space radiator systems depends critically upon the selection of appropriate spectrally selective surfaces. Many space programs have suffered severe performance limitations, schedule setbacks, and spent hundreds of thousands of dollars in damage control because of a lack of readily-accessible, accurate data on the properties of spectrally selective surfaces, particularly black surfaces. A Canadian effort is underway to develop a resource base (database and support service) to help alleviate this problem. The assistance of the community is required to make the resource base comprehensive and useful to the end users. The paper aims to describe the objectives of this project. In addition, a request for information and support is made for various aspects of the project. The resource base will be useful for both ground and space-based instrumentation.

  8. The spectral characteristics of Gd sub 2 SiO sub 5 :Eu sup 3 sup + in VUV-UV range

    CERN Document Server

    Chen Yong; Wei Ya Guang; Tao Ye

    2002-01-01

    Synchrotron radiation source was used to investigated the spectral characteristics of Gd sub 2 SiO sub 5 :Eu sup 3 sup + in VUV-UV range. The various energy transfers at room temperature and 10 K, including from host or Gd sup 3 sup + ions to Eu sup 3 sup + ions and transfer between Eu sup 3 sup + ions at two different lattice sites, were discussed. In addition the emission spectra under 186 nm and 276 nm excitation were compared from the view of quantum cutting. The results indicate that Gd sub 2 SiO sub 5 :Eu sup 3 sup + is a kind of material with potential high efficiency quantum cutting

  9. UV light impact on ellagitannins and wood surface colour of European oak ( Quercus petraea and Quercus robur)

    Science.gov (United States)

    Zahri, S.; Belloncle, C.; Charrier, F.; Pardon, P.; Quideau, S.; Charrier, B.

    2007-03-01

    Two European oak species ( Q. petraea and Q. robur) have a high content of phenols which may participate in the alteration of colour upon UV irradiation. To study the photodegradation process of oak surfaces, the two oak species extractives, vescalagin, castalagin, ellagic acid and gallic acid were analysed quantitatively by HPLC before and after UV irradiation. Irradiation time was altered between 3, 24, 72, 96, 120, 144, 192 and 216 h. In parallel, any colour changes of Oak wood surface was followed after 120 h of UV-irradiation by measuring CIELAB parameters (DL*, Da*, Db* and DE*). We observed that 60% of total phenol content of extractives decreased after the maximal exposure time. Our findings also showed that castalagin and gallic acid were destroyed after 216 h and vescalagin and ellagic acid after 72 h. This study proves the photosenibility of oakwood extractives which, supplementary to lignin degradation, would strongly result in the discolouration of oak heartwood.

  10. Reconstruction of the solar spectral UV irradiance for nowcasting of the middle atmosphere state on the basis of LYRA measurements

    Directory of Open Access Journals (Sweden)

    T. Egorova

    2008-02-01

    Full Text Available The LYRA instrument onboard ESA PROBA2 satellite will provide 6-hourly solar irradiance at the Lyman-alpha (121.6 nm and the Herzberg continuum (~200–220 nm wavelength range. Because the nowcasting of the neutral and ionic state of the middle atmosphere requires the solar irradiance for the wide spectral area (120–680 nm we have developed the statistical tool for the reconstruction of the full spectrum from the LYRA measurements. The accuracy of the reconstructed irradiance has been evaluated with 1-D transient radiative-convective model with neutral and ion chemistry using the daily solar spectral irradiance measured with SUSIM and SOLSTICE instruments onboard UARS satellite. We compared the results of transient 1-yr long model simulations for 2000 driven by the observed and reconstructed solar irradiance and showed that the reconstruction of the full spectrum using linear regression equation based on the solar irradiance in two LYRA channels can be successfully used for nowcasting of the middle atmosphere. We have also defined some conditions when the proposed approach does not provide reasonable accuracy.

  11. Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains Central Facility

    Energy Technology Data Exchange (ETDEWEB)

    McFarlane, Sally A.; Gaustad, Krista L.; Mlawer, Eli J.; Long, Charles N.; Delamere, Jennifer

    2011-09-01

    We present a method for identifying dominant surface type and estimating high spectral resolution surface albedo at the Atmospheric Radiation Measurement (ARM) facility at the Southern Great Plains (SGP) site in Oklahoma for use in radiative transfer calculations. Given a set of 6-channel narrowband visible and near-infrared irradiance measurements from upward and downward looking multi-filter radiometers (MFRs), four different surface types (snow-covered, green vegetation, partial vegetation, non-vegetated) can be identified. A normalized difference vegetation index (NDVI) is used to distinguish between vegetated and non-vegetated surfaces, and a scaled NDVI index is used to estimate the percentage of green vegetation in partially vegetated surfaces. Based on libraries of spectral albedo measurements, a piecewise continuous function is developed to estimate the high spectral resolution surface albedo for each surface type given the MFR albedo values as input. For partially vegetated surfaces, the albedo is estimated as a linear combination of the green vegetation and non-vegetated surface albedo values. The estimated albedo values are evaluated through comparison to high spectral resolution albedo measurements taken during several Intensive Observational Periods (IOPs) and through comparison of the integrated spectral albedo values to observed broadband albedo measurements. The estimated spectral albedo values agree well with observations for the visible wavelengths constrained by the MFR measurements, but have larger biases and variability at longer wavelengths. Additional MFR channels at 1100 nm and/or 1600 nm would help constrain the high resolution spectral albedo in the near infrared region.

  12. Numerical study of the effects of surface roughness on water disinfection UV reactor.

    Science.gov (United States)

    Sultan, Tipu; Ahmad, Sarfraz; Cho, Jinsoo

    2016-04-01

    UV reactors are an emerging choice as a big barrier against the pathogens present in drinking water. However, the precise role of reactor's wall roughness for cross flow ultraviolet (CF-UV) and axial flow ultraviolet (AF-UV) water disinfection reactors are unknown. In this paper, the influences of reactor's wall roughness were investigated with a view to identify their role on the performance factors namely dose distribution and reduction equivalent dose (RED). Herein, the relative effects of reactor's wall roughness on the performance of CF-UV and AF-UV reactors were also highlighted. This numerical study is a first step towards the comprehensive analysis of the effects of reactor's wall roughness for UV reactor. A numerical analysis was performed using ANSYS Fluent 15 academic version. The reactor's wall roughness has a significant effect on the RED. We found that the increase in RED is Reynolds number dependent (at lower value of turbulent Reynolds number the effects are remarkable). The effects of reactor's roughness were more pronounced for AF-UV reactor. The simulation results suggest that the study of reactor's wall roughness provides valuable insight to fully understand the effects of reactor's wall roughness and its impact on the flow behavior and other features of CF-UV and AF-UV water disinfection reactors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Comparison of UV-RSS spectral measurements and TUV model runs for clear skies for the May 2003 ARM aerosol intensive observation period

    Directory of Open Access Journals (Sweden)

    J. J. Michalsky

    2007-11-01

    Full Text Available The first successful deployment of the fully-operational ultraviolet rotating shadow-band spectroradiometer occurred during the May 2003 U.S. Department of Energy's Atmospheric Radiation Measurement program's Aerosol Intensive Observation Period. The aerosol properties in the visible range were characterized using redundant measurements with several instruments to determine the column aerosol optical depth, the single scattering albedo, and the asymmetry parameter needed as input for radiative transfer calculations of the downwelling direct normal and diffuse horizontal solar irradiance in clear-sky conditions. The Tropospheric Ultraviolet and Visible (TUV radiative transfer model developed by Madronich and his colleagues at the U.S. National Center for Atmospheric Research was used for the calculations of the spectral irradiance between 300–360 nm. Since there are few ultraviolet measurements of aerosol properties, most of the input aerosol data for the radiative transfer model are based on the assumption that UV input parameters can be extrapolated from the visible portion of the spectrum. Disagreements between available extraterrestrial spectra, which are discussed briefly, suggested that instead of comparing irradiances that measured and modeled spectral transmittances between 300–360 nm should be compared for the seven cases studied. These cases included low to moderate aerosol loads and low to high solar-zenith angles. A procedure for retrieving single scattering albedo in the ultraviolet based on the comparisons of direct and diffuse transmittance is outlined.

  14. Vibrational spectra, UV-vis spectral analysis and HOMO-LUMO studies of 2,4-dichloro-5-nitropyrimidine and 4-methyl-2-(methylthio)pyrimidine.

    Science.gov (United States)

    Arivazhagan, M; Anitha Rexalin, D

    2013-04-15

    The FT-IR and FT-Raman vibrational spectra of 2,4-dichloro-5-nitropyrimidine (DCNP) and 4-methyl-2-(methylthio)pyrimidine (MTP) have been recorded in the range 4000-400 and 3600-50 cm(-1), respectively. A detailed vibrational spectral analysis has been carried out and assignments of the observed fundamental bands have been proposed on the basis of peak positions and relative intensities. The optimized molecular geometry and vibrational frequencies in the ground state are calculated using density functional B3LYP method with 6-31+G(d,p) and 6-311++G(d,p) basis set combinations. With the help of specific scaling procedures, the observed vibrational wavenumbers in FT-IR and FT-Raman spectra are analyzed and assigned to different normal modes of the molecules. The predicted first hyperpolarizability reveals that the molecules are an attractive object for future studies of non-linear optical properties. And also HOMO-LUMO energy gap explains the eventual charge transfer interaction taking place within the molecules. UV-vis spectral analysis of the title compounds has been researched by theoretical calculations. The frontier orbital energies, absorption wavelengths (λ), oscillator strengths (f) and excitation energies (E) studied using TD-DFT (B3LYP) with 6-311++G(d,p) basis set are calculated in this work.

  15. Spatially Complete Global Spectral Surface Albedos: Value-Added Datasets Derived from Terra MODIS Land Products

    Science.gov (United States)

    Moody, Eric G.; King, Michael D.; Platnick, Steven; Schaaf, Crystal B.; Gao, Feng

    2004-01-01

    Land surface albedo is an important parameter in describing the radiative properties of the earth s surface as it represents the amount of incoming solar radiation that is reflected from the surface. The amount and type of vegetation of the surface dramatically alters the amount of radiation that is reflected; for example, croplands that contain leafy vegetation will reflect radiation very differently than blacktop associated with urban areas. In addition, since vegetation goes through a growth, or phenological, cycle, the amount of radiation that is reflected changes over the course of a year. As a result, albedo is both temporally and spatially dependant upon global location as there is a distribution of vegetated surface types and growing conditions. Land surface albedo is critical for a wide variety of earth system research projects including but not restricted to remote sensing of atmospheric aerosol and cloud properties from space, ground-based analysis of aerosol optical properties from surface-based sun/sky radiometers, biophysically-based land surface modeling of the exchange of energy, water, momentum, and carbon for various land use categories, and surface energy balance studies. These projects require proper representation of the surface albedo s spatial, spectral, and temporal variations, however, these representations are often lacking in datasets prior to the latest generation of land surface albedo products.

  16. On-line surface inspection using cylindrical lens-based spectral domain low-coherence interferometry.

    Science.gov (United States)

    Tang, Dawei; Gao, Feng; Jiang, X

    2014-08-20

    We present a spectral domain low-coherence interferometry (SD-LCI) method that is effective for applications in on-line surface inspection because it can obtain a surface profile in a single shot. It has an advantage over existing spectral interferometry techniques by using cylindrical lenses as the objective lenses in a Michelson interferometric configuration to enable the measurement of long profiles. Combined with a modern high-speed CCD camera, general-purpose graphics processing unit, and multicore processors computing technology, fast measurement can be achieved. By translating the tested sample during the measurement procedure, real-time surface inspection was implemented, which is proved by the large-scale 3D surface measurement in this paper. ZEMAX software is used to simulate the SD-LCI system and analyze the alignment errors. Two step height surfaces were measured, and the captured interferograms were analyzed using a fast Fourier transform algorithm. Both 2D profile results and 3D surface maps closely align with the calibrated specifications given by the manufacturer.

  17. A simple UV-ozone surface treatment to enhance photocatalytic performance of TiO 2 loaded polymer nanofiber membranes

    KAUST Repository

    Dilpazir, S.

    2016-01-29

    Homogeneously dispersed titanium dioxide loaded polyacrylonitrile nanofiber membranes with increased active mass loading, Ti3+ surface defects and hydrophilicity were fabricated by combining electrospinning and UV-ozone surface treatment. The photocatalytic activity improved by a factor of ∼2 and the kinetics of photodegradation switched from pseudo-first order to pseudo-second order with increasing TiO2 content with a maximum rate constant of 20.7 h-1. © The Royal Society of Chemistry 2016.

  18. Study of cloud enhanced surface UV radiation at the atmospheric observatory of Southern Patagonia, Río Gallegos, Argentina

    Science.gov (United States)

    Wolfram, Elian A.; Salvador, Jacobo; Orte, Facundo; Bulnes, Daniela; D'Elia, Raul; Antón, Manuel; Alados-Arboledas, Lucas; Quel, Eduardo

    2013-05-01

    Ozone and ultraviolet (UV) radiation are two important issues in the study of Earth's atmosphere. The anthropogenic perturbation of the ozone layer has induced change in the amount of UV radiation that reaches the Earth's surface, mainly through the Antarctic ozone hole. Also clouds have been identified as the main modulator of UV amount over short time scales. While clouds can decrease direct radiation, they can produce an increase in the diffuse component, and as a consequence the surface UV radiation may be higher than during an equivalent clear sky scenario. In particular this situation can be important when a low ozone column and partially cloud coverered skies occur simultaneously. These situations happen frequently in southern Patagonia, where the CEILAP Lidar Division has established the Atmospheric Observatory of Southern Patagonia, an atmospheric remote sensing site near the city of Río Gallegos (51°55'S, 69°14'W). In this paper, the impact of clouds on UV radiation is investigated by the use of ground based measurements from the passive remote sensing instruments operating at this site, mainly broad and moderate narrow band filter radiometers. Cloud modification factors (CMF, ratio between the measured UV radiation in a cloudy sky and the simulated radiation under cloud-free conditions) are evaluated for the study site. CMFs higher than 1 are found during spring and summer time, when lower total ozone columns, higher solar elevations and high cloud cover occur simultaneously, producing extreme erythemal irradiance at the ground surface. Enhancements as high as 25% were registered. The maximum duration of the enhancement was around 30 minutes. This produces dangerous sunbathing conditions for the Río Gallegos citizen.

  19. Average surface albedo measurements in the UV, IR, and TSR on the Holy Mosque and places in Makkah, Saudi Arabia

    Science.gov (United States)

    Seroji, Abdulaziz R.

    2005-08-01

    Average albedo values were measured at three broad wavebands; UV region (295 - 385 nm), Total Solar Radiation, TSR, (305 - 2800 nm), and IR region (3500 - 50000 nm), over different surfaces in the Holy Mosque and Places in Makkah (21°.25 N, 39°.49 E). The Eppley Laboratory Radiometers of TUVR and PIR were used for UV and IR measurements respectively, while Kipp & Zonen Pyranometer of CM3 was adopted for the TSR observations. Measurements were performed during two different periods (summer 28/7-10/8/2004 at Holy Mosque and winter 18-30/1/2005 at Holy Places). Summer measurements showed that the average surface albedos of the Holy Mosque white marbles were 0.45, 0.70 and 1.14 at UV, TSR and IR regions respectively. These values have decreased to 0.12 and 0.18 at UV and TSR regions respectively over the Holy Mosque brown marbles. However, the average albedo value has increased to 1.38 at IR region due to the large Longwave radiation emission from the brown marble surfaces. The albedo values of the Holy Mosque red carpets were determined. The average albedo values were also measured over the Holy Places surfaces (18 m) of pilgrimage, (Muna and Arafat sites) during winter 2005. The observed average surface albedo values over Arafat selected area were 0.00, 0.22 and 1.18 at UV, TSR and IR regions respectively. The average albedo values over Muna selected area and Muna tents were also presented. The effect of clouds and solar zenith angle (SZA) on the measured albedo were investigated in this study.

  20. Spectral analysis of quasi-stationary sea surface topography from GRACE mission

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zizhan; LU Yang

    2005-01-01

    During the last two decades satellite altimetry has offered an abundance of measurements of the sea surface resulting in the improvement of global mean sea surface height (MSSH) and marine geoid determination. On the other hand, with the launching of new generation gravity satellites, some high accuracy long-wavelength gravity models are available. These breakthroughs give us a great opportunity for new estimation of quasi-stationary sea surface topography (QSST). In this paper, the new gravity model GGM01C derived from GRACE mission is briefly presented, and a new global high precision and high-resolution QSST is determined based on the GGM01C model and the global MSSH. The spectral features of the QSST estimated by GGM01C and EGM96 gravity model to degree/order 200 are discussed by spectral analysis. As a result, the QSST is mainly composed of long waves, medium waves partially and short waves scarcely, its power spectral structures are different between the zonal direction and the meridional direction, there are great differences between the two models, which maybe explain why the ocean currents derived from the two gravity models by Tapley show different patterns.

  1. The physical properties of Spitzer/IRS galaxies derived from their UV to 22 $\\mu$m spectral energy distribution

    CERN Document Server

    Vika, Marina; Charmandaris, Vassilis; Xilouris, Emmanuel M; Lebouteiller, Vianney

    2016-01-01

    We provide the basic integrated physical properties of all the galaxies contained in the full CASSIS with available broad-band photometry from UV to 22 $\\mu$m. We have collected photometric measurements in 14 wavelengths from available public surveys in order to study the SED of each galaxy in CASSIS, thus constructing a final sample of 1,146 galaxies in the redshift range 0

  2. Spectral and Spatial UV Sky Radiance Measurements at a Seaside Resort Under Clear Sky and Slightly Overcast Conditions.

    Science.gov (United States)

    Sandmann, Henner; Stick, Carsten

    2014-01-01

    Spatial measurements of the diffusely scattered sky radiance at a seaside resort under clear sky and slightly overcast conditions have been used to calculate the sky radiance distribution across the upper hemisphere. The measurements were done in the summer season when solar UV radiation is highest. The selected wavelengths were 307, 350 and 550 nm representing the UVB, UVA and VIS band. Absolute values of radiance differ considerably between the wavelengths. Normalizing the measured values by use of direct solar radiance made the spatial distributions of unequal sky radiance comparable. The results convey a spatial impression of the different distributions of the radiance at the three wavelengths. Relative scattered radiance intensity is one order of magnitude greater in UVB than in VIS, whereas in UVA lies roughly in between. Under slightly overcast conditions scattered radiance is increased at all three wavelengths by about one order of magnitude. These measurements taken at the seaside underline the importance of diffuse scattered radiance. The effect of shading parts of the sky can be estimated from the distribution of sky radiance. This knowledge might be useful for sun seekers and in the treatment of people staying at the seaside for therapeutic purposes.

  3. Ornaments in radiation treatment of cultural heritage: Color and UV-vis spectral changes in irradiated nacres

    Science.gov (United States)

    Marušić, Katarina; Pucić, Irina; Desnica, Vladan

    2016-07-01

    Cultural heritage objects that are radiation treated in order to stop their biodegradation often contain ornamenting materials that cannot be removed. Radiation may produce unwanted changes to such materials. Nacre is a common ornamenting material so this is an attempt to assess the impact of gamma-radiation on its optical properties. Two types of nacre (yellow and white) were obtained from a museum and subjected to different absorbed doses of Co-60 gamma irradiation under the same conditions. The radiation induced changes of nacres color were investigated with fiber optic reflectance spectroscopy (FORS). Colorimetry in CIE Lab space revealed that in both nacres the lightness shifted to darker grey hues at high doses while the color component's (red, green, yellow and blue) behavior depended on the nacre type. Observable changes occurred at doses much above the dose range needed for radiation treatment of cultural heritage objects that are often ornamented with nacre. In UV-vis reflectance spectra of samples irradiated to high doses carbonate radical anion absorption appeared.

  4. Solvent, anion, and structural effects on the redox potentials and UV-visible spectral properties of mononuclear manganese corroles.

    Science.gov (United States)

    Shen, Jing; El Ojaimi, Maya; Chkounda, Mohammed; Gros, Claude P; Barbe, Jean-Michel; Shao, Jianguo; Guilard, Roger; Kadish, Karl M

    2008-09-01

    A series of manganese(III) corroles were investigated as to their electrochemistry and spectroelectrochemistry in nonaqueous solvents. Up to three oxidations and one reduction were obtained for each complex depending on the solvents. The main compound discussed in this paper is the meso-substituted manganese corrole, (Mes 2PhCor)Mn, and the main points are how changes in axially coordinated anion and solvent will affect the redox potentials and UV-vis spectra of each electrogenerated species in oxidation states of Mn(III), Mn(IV), or Mn(II). The anions OAc (-), Cl (-), CN (-), and SCN (-) were found to form five-coordinate complexes with the neutral Mn(III) corrole while two OH (-) or F (-) anions were shown to bind axially in a stepwise addition to give the five- and six-coordinate complexes in nonaqueous media. In each case, complexation with one or two anionic axial ligands led to an easier oxidation and a harder reduction as compared to the uncomplexed four-coordinate species.

  5. Spectral analysis, vibrational assignments, NBO analysis, NMR, UV-Vis, hyperpolarizability analysis of 2-aminofluorene by density functional theory.

    Science.gov (United States)

    Jone Pradeepa, S; Sundaraganesan, N

    2014-05-05

    In this present investigation, the collective experimental and theoretical study on molecular structure, vibrational analysis and NBO analysis has been reported for 2-aminofluorene. FT-IR spectrum was recorded in the range 4000-400 cm(-1). FT-Raman spectrum was recorded in the range 4000-50 cm(-1). The molecular geometry, vibrational spectra, and natural bond orbital analysis (NBO) were calculated for 2-aminofluorene using Density Functional Theory (DFT) based on B3LYP/6-31G(d,p) model chemistry. (13)C and (1)H NMR chemical shifts of 2-aminofluorene were calculated using GIAO method. The computed vibrational and NMR spectra were compared with the experimental results. The total energy distribution (TED) was derived to deepen the understanding of different modes of vibrations contributed by respective wavenumber. The experimental UV-Vis spectra was recorded in the region of 400-200 nm and correlated with simulated spectra by suitably solvated B3LYP/6-31G(d,p) model. The HOMO-LUMO energies were measured with time dependent DFT approach. The nonlinearity of the title compound was confirmed by hyperpolarizabilty examination. Using theoretical calculation Molecular Electrostatic Potential (MEP) was investigated.

  6. Effect of spectrally varying albedo of vegetation surfaces on shortwave radiation fluxes and direct aerosol forcing

    Directory of Open Access Journals (Sweden)

    L. Zhu

    2012-06-01

    Full Text Available This study develops an algorithm for the representation of large spectral variations of albedo over vegetation surfaces based on Moderate Resolution Imaging Spectrometer (MODIS observations at 7 discrete channels centered at 0.47, 0.55, 0.67, 0.86, 1.24, 1.63, and 2.11 μm. The MODIS 7-channel observations miss several major features of vegetation albedo including the vegetation red edge near 0.7 μm and vegetation absorption features at 1.48 and 1.92 μm. We characterize these features by investigating aerosol forcing in different spectral ranges. We show that the correction at 0.7 μm is the most sensitive and important due to the presence of the red edge and strong solar radiation; the other two corrections are less sensitive due to the weaker solar radiation and strong atmospheric water absorption. Four traditional approaches for estimating the reflectance spectrum and the MODIS enhanced vegetation albedo (MEVA are tested against various vegetation types: dry grass, green grass, conifer, and deciduous from the John Hopkins University (JHU spectral library; aspens from the US Geological Survey (USGS digital spectral library; and Amazon vegetation types. Compared to traditional approaches, MEVA improves the accuracy of the outgoing flux at the top of the atmosphere by over 60 W m−2 and aerosol forcing by over 10 W m−2. Specifically, for Amazon vegetation types, MEVA can improve the accuracy of daily averaged aerosol forcing at equator at equinox by 3.7 W m−2 (about 70% of the aerosol forcing calculated with high spectral resolution surface reflectance. These improvements indicate that MEVA can contribute to vegetation covered regional climate studies, and help to improve understanding of climate processes and climate change.

  7. Effect of UV-ozone treatment on poly(dimethylsiloxane) membranes: surface characterization and gas separation performance.

    Science.gov (United States)

    Fu, Ywu-Jang; Qui, Hsuan-zhi; Liao, Kuo-Sung; Lue, Shingjiang Jessie; Hu, Chien-Chieh; Lee, Kueir-Rarn; Lai, Juin-Yih

    2010-03-16

    A thin SiO(x) selective surface layer was formed on a series of cross-linked poly(dimethylsiloxane) (PDMS) membranes by exposure to ultraviolet light at room temperature in the presence of ozone. The conversion of the cross-linked polysiloxane to SiO(x) was monitored by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray (EDX) microanalysis, contact angle analysis, and atomic force microscopy (AFM). The conversion of the cross-linked polysiloxane to SiO(x) increased with UV-ozone exposure time and cross-linking agent content, and the surface possesses highest conversion. The formation of a SiO(x) layer increased surface roughness, but it decreased water contact angle. Gas permeation measurements on the UV-ozone exposure PDMS membranes documented interesting gas separation properties: the O(2) permeability of the cross-linked PDMS membrane before UV-ozone exposure was 777 barrer, and the O(2)/N(2) selectivity was 1.9; after UV-ozone exposure, the permeability decreased to 127 barrer while the selectivity increased to 5.4. The free volume depth profile of the SiO(x) layer was investigated by novel slow positron beam. The results show that free volume size increased with the depth, yet the degree of siloxane conversion to SiO(x) does not affect the amount of free volume.

  8. Mars surface weathering products and spectral analogs: Palagonites and synthetic iron minerals

    Science.gov (United States)

    Golden, D. C.; Ming, D. W.; Morris, R. V.; Lauer, H. V., Jr.

    1992-01-01

    There are several hypotheses regarding the formation of Martian surface fines. These surface fines are thought to be products of weathering processes occurring on Mars. Four major weathering environments of igneous rocks on Mars have been proposed; (1) impact induced hydrothermal alterations; (2) subpermafrost igneous intrusion; (3) solid-gas surface reactions; and (4) subaerial igneous intrusion over permafrost. Although one or more of these processes may be important on the Martian surface, one factor in common for all these processes is the reaction of solid or molten basalt with water (solid, liquid, or gas). These proposed processes, with the exception of solid-gas surface reactions, are transient processes. The most likely product of transient hydrothermal processes are layer silicates, zeolites, hydrous iron oxides and palagonites. The long-term instability of hydrous clay minerals under present Martian conditions has been predicted; however, the persistence of such minerals due to slow kinetics of dehydration, or entrapment in permafrost, where the activity of water is high, can not be excluded. Anhydrous oxides of iron (e.g., hematite and maghemite) are thought to be stable under present Martian surface conditions. Oxidative weathering of sulfide minerals associated with Martian basalts has been proposed. Weathering of sulfide minerals leads to a potentially acidic permafrost and the formation of Fe(3) oxides and sulfates. Weathering of basalts under acidic conditions may lead to the formation of kaolinite through metastable halloysite and metahalloysite. Kaolinite, if present, is thought to be a thermodynamically stable phase at the Martian surface. Fine materials on Mars are important in that they influence the surface spectral properties; these fines are globally distributed on Mars by the dust storms and this fraction will have the highest surface area which should act as a sink for most of the absorbed volatiles near the surface of Mars. Therefore

  9. Two-photon absorption, nonlinear optical and UV-vis spectral properties of 2-furanylmethyleneaminoantipyrine, benzylideneaminoantipyrine and cinnamilideneaminoantipyrine

    Energy Technology Data Exchange (ETDEWEB)

    Sun Yuxi, E-mail: yuxisun@163.com [Key Laboratory for Soft Chemistry and Functional Materials of Education Ministry, Nanjing University of Science and Technology, Nanjing 210094 (China) and Key Laboratory of Life-Organic Analysis, School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, Shandong 273165 (China); Hao Qingli; Tang Weihua; Wang Yufeng [Key Laboratory for Soft Chemistry and Functional Materials of Education Ministry, Nanjing University of Science and Technology, Nanjing 210094 (China); Yang Xujie, E-mail: yangx@mail.njust.edu.cn [Key Laboratory for Soft Chemistry and Functional Materials of Education Ministry, Nanjing University of Science and Technology, Nanjing 210094 (China); Lu Lude; Wang Xin [Key Laboratory for Soft Chemistry and Functional Materials of Education Ministry, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2011-09-15

    Highlights: {yields} Three imine-bridged aromatic antipyrine derivatives as photo-responsive materials. {yields} The compounds exhibit two-photon absorption and first-hyperpolarization properties {yields} The compounds have long-range electron transfer characteristics. - Abstract: Organic compounds as functional materials have attracted much keen interest in the past three decades owing to their potential applications in science and technology. Currently, great efforts have been made in looking for suitable photo-responsive materials among the multifarious organic compounds. Herein we reported the photophysical properties of 2-furanylmethylene-aminoantipyrine (FMAAP), benzylideneaminoantipyrine (BIAAP) and cinnamilideneamino-antipyrine (CIAAP) studied by a combined experimental and theoretical investigation. Two-photon absorption measurements give the cross-section values of 1.350 x 10{sup -50} cm{sup 4} s/photon for FMAAP, 1.046 x 10{sup -50} cm{sup 4} s/photon for BIAAP and 2.047 x 10{sup -50} cm{sup 4} s/photon for CIAAP. The calculated first-hyperpolarization values are of 2.303 x 10{sup -30}, 1.257 x 10{sup -29}, 2.889 x 10{sup -29} cm{sup 5}/esu for FMAAP, BIAAP and CIAAP, respectively. UV-vis spectroscopy technique further reveals that the studied compounds display long-range electron transfer characteristics by absorbing light of specific wavelengths of 294.5 nm for FMAAP, 293.2 nm for BIAAP and 303.1 nm for CIAAP. All the results indicate that the studied compounds are promising candidates of functionally photo-responsive materials.

  10. TiO2 micro-nano-hybrid surface to alleviate biological aging of UV-photofunctionalized titanium

    Directory of Open Access Journals (Sweden)

    Iwasa F

    2011-06-01

    Full Text Available Fuminori Iwasa1, Naoki Tsukimura1, Yoshihiko Sugita1, Rajita Kodali Kanuru1, Katsutoshi Kubo1, Hafiz Hasnain1, Wael Att1,2, Takahiro Ogawa11Laboratory of Bone and Implant Sciences (LBIS, The Weintraub Center for Reconstructive Biotechnology, Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry, UCLA School of Dentistry, Los Angeles, CA, USA; 2Department of Prosthodontics, Dental School, Albert-Ludwigs University, Freiburg, GermanyAbstract: Bioactivity and osteoconductivity of titanium degrade over time after surface processing. This time-dependent degradation is substantial and defined as the biological aging of titanium. UV treatment has shown to reactivate the aged surfaces, a process known as photofunctionalization. This study determined whether there is a difference in the behavior of biological aging for titanium with micro-nano-hybrid topography and titanium with microtopography alone, following functionalization. Titanium disks were acid etched to create micropits on the surface. Micro-nano-hybrid surfaces were created by depositioning 300-nm diameter TiO2 nodules onto the micropits using a previously established self-assembly protocol. These disks were stored for 8 weeks in the dark to allow sufficient aging, then treated with UV light for 48 hours. Rat bone marrow–derived osteoblasts were cultured on fresh disks (immediately after UV treatment, 3-day-old disks (disks stored for 3 days after UV treatment, and 7-day-old disks. The rates of cell attachment, spread, proliferation, and levels of alkaline phosphatase activity, and calcium deposition were reduced by 30%–50% on micropit surfaces, depending on the age of the titanium. In contrast, 7-day-old hybrid surfaces maintained equivalent levels of bioactivity compared with the fresh surfaces. Both micropit and micro-nano-hybrid surfaces were superhydrophilic immediately after UV treatment. However, after 7 days, the micro-nano-hybrid surfaces became hydrorepellent

  11. Potential of Ozone Formation by the Smog Mechanism to shield the surface of the Early Earth from UV radiation?

    CERN Document Server

    Grenfell, J L; Patzer, B; Titz, R; Rauer, H; Grenfell, John Lee; Stracke, Barbara; Patzer, Beate; Titz, Ruth; Rauer, Heike

    2006-01-01

    We propose that the photochemical smog mechanism produced substantial ozone (O3) in the troposphere during the Proterozoic, which contributed to ultraviolet (UV) radiation shielding hence favoured the establishment of life. The smog mechanism is well-established and is associated with pollution hazes which sometimes cover modern cities. The mechanism proceeds via the oxidation of volatile organic compounds (VOCs) such as methane (CH4) in the presence of UV radiation and nitrogen oxides (NOx). It would have been particularly favoured during the Proterozoic given the high levels of CH4 (up to 1000 ppm) recently suggested. Proterozoic UV levels on the surface of the Earth were generally higher compared with today, which would also have favoured the mechanism. On the other hand, Proterozoic O2 required in the final step of the smog mechanism to form O3 was less abundant compared with present times. Further, results are sensitive to Proterozoic NOx concentrations, which are challenging to predict, since they depen...

  12. A Web-Interface for Data Interoperability: the Spectral Library of Mt Etna Volcanic Surfaces

    Science.gov (United States)

    Colini, L.; Doumaz, F.; Spinetti, C.; Mazzarini, F.; Favalli, M.; Isola, I.; Buongiorno, M. F.; Ananasso, C.

    2014-12-01

    In the frame of the future Italian Space Agency (ASI) Space Mission PRISMA (Precursore IperSpettrale della Missione Applicativa), the Istituto Nazionale di Geofisica e Vulcanologia (INGV) coordinates the scientific project ASI-AGI (Analisi Sistemi Iperspettrali per le Applicazioni Geofisiche Integrate) aimed to study the hyperspectral volcanic applications and to identify and characterize a vicarious validation and calibration site for hyperspectral space missions. PRISMA is an Earth observation system with innovative electro-optical instrumentation which combines an hyperspectral sensor with a panchromatic medium-resolution camera. These instruments offer the scientific community and users many applications in the field of environmental monitoring, risk management, crop classification, pollution control, and Security. In this context Mt. Etna (Italy) has been choose as main site for testing the sensor capability to assess volcanic risk. The volcanic calibration and validation activities comprise the managing of a large amount of in situ hyperspectral data collected during the last 10 years. The usability and interoperability of these datasets represents a task of ASI-AGI project. For this purpose a database has been created to collect all the spectral signatures of the measured volcanic surfaces. This process has begun with the creation of the metadata structure compliant with those belonging to some standard spectral libraries such as USGS ones. Each spectral signature is described in a table containing ancillary data such as the location map of where it was collected, description of the target selected, etc. The relational database structure has been developed WOVOdat compliant. Specific tables have been formatted for each type of measurements, instruments and targets in order to query the database through a user-friendly web-interface. The interface has an upload area to populate the database and a visualization tool that allows downloading the ASCII spectral

  13. Spectral simulation of thermocapillary convection with a deformable free surface using boundary-fitted coordinates

    Science.gov (United States)

    Ahmed, Ikramuddin

    A Chebyshev-spectral collocation scheme has been developed to simulate thermocapillary convection processes in a differentially heated cavity with and without buoyancy effects. The time-dependent Navier- Stokes equations in primitive variables were solved with a semi-implicit scheme using the influence matrix technique. The deformable free surface was incorporated by means of a boundary-fitted coordinate (BFC) system. The BFC grid was generated by solving a system of elliptic equations. An iterative scheme based on finite difference methods was found to be sufficient for calculating a smooth distribution of grid-points for relatively low degrees of deformation of the free surface. The metrics of transformation, however, were calculated spectrally in order to achieve a high order of accuracy in the a posteriori mapping of the physical grid to the computational grid. The overall scheme was found to be efficient, economical, and capable of resolving the complex hydrodynamic and thermal structures in thermocapillarity driven flows with deformable free surfaces. The scheme was also modified to study problems with very high Marangoni numbers and non-deformable free surfaces, and later extended to three dimensions with periodic boundary conditions in order to explore the transitions to fully three dimensional phenomena that are anticipated in industrially relevant flow configurations.

  14. Spectral properties of Titan's impact craters imply chemical weathering of its surface

    Science.gov (United States)

    Barnes, J. W.; Sotin, C.; MacKenzie, S.; Soderblom, J. M.; Le Mouélic, S.; Kirk, R. L.; Stiles, B. W.; Malaska, M. J.; Le Gall, A.; Brown, R. H.; Baines, K. H.; Buratti, B.; Clark, R. N.; Nicholson, P. D.

    2015-01-01

    Abstract We examined the spectral properties of a selection of Titan's impact craters that represent a range of degradation states. The most degraded craters have rims and ejecta blankets with spectral characteristics that suggest that they are more enriched in water ice than the rims and ejecta blankets of the freshest craters on Titan. The progression is consistent with the chemical weathering of Titan's surface. We propose an evolutionary sequence such that Titan's craters expose an intimate mixture of water ice and organic materials, and chemical weathering by methane rainfall removes the soluble organic materials, leaving the insoluble organics and water ice behind. These observations support the idea that fluvial processes are active in Titan's equatorial regions. PMID:27656006

  15. Spectral Properties of ENVISAT ASAR and QuikSCAT Surface Winds in the North Sea

    DEFF Research Database (Denmark)

    Karagali, Ioanna; Larsén, Xiaoli Guo; Badger, Merete

    2013-01-01

    Spectra derived from ENVISAT Advanced Synthetic Aperture Radar (ASAR) and QuikSCAT near-surface ocean winds are investigated over the North Sea. The two sensors offer a wide range of spatial resolutions, from 600 m to 25 km, with different spatial coverage over the area of interest. This provides...... a unique opportunity to study the impact of the spatial resolution on the spectral properties of the wind over a wide range of length scales. Initially, a sub-domain in the North Sea is chosen, due to the overlap of 87 wind scenes from both sensors. The impact of the spatial resolution is manifested...... or lower. The lower power levels of coarser resolution wind products, particularly when comparing QuikSCAT to ENVISAT ASAR, strongly suggest that the effective resolution of the wind products should be high enough to resolve the spectral properties. Spectra computed from 87 wind maps are consistent...

  16. Group interpretation of the spectral parameter. The case of isothermic surfaces

    Science.gov (United States)

    Cieśliński, Jan L.; Kobus, Artur

    2017-03-01

    It is well known that in some cases the spectral parameter has a group interpretation. We discuss in detail the case of Gauss-Codazzi equations for isothermic surfaces immersed in E3. The algebra of Lie point symmetries is 4-dimensional and all these symmetries are also symmetries of the Gauss-Weingarten equations (which can be considered as so(3) -valued non-parametric linear problem). In order to obtain a non-removable spectral parameter one has to consider so(4 , 1) -valued linear problem which has a 3-dimensional algebra of Lie point symmetries. The missing symmetry introduces a non-removable parameter. In the second part of the paper we extend these results on the case of isothermic immersions in arbitrary multidimensional Euclidean spaces. In order to simplify calculations the problem was formulated in terms of a Clifford algebra.

  17. The optimal UV exposure time for vitamin D3 synthesis and erythema estimated by UV observations in Korea

    Science.gov (United States)

    Lee, Y. G.; Koo, J. H.

    2016-12-01

    Solar UV radiation in a wavelength range between 280 to 400 nm has both positive and negative influences on human body. Surface UV radiation is the main natural source of vitamin D, providing the promotion of bone and musculoskeletal health and reducing the risk of a number of cancers and other medical conditions. However, overexposure to surface UV radiation is significantly related with the majority of skin cancer, in addition other negative health effects such as sunburn, skin aging, and some forms of eye cataracts. Therefore, it is important to estimate the optimal UV exposure time, representing a balance between reducing negative health effects and maximizing sufficient vitamin D production. Previous studies calculated erythemal UV and vitamin-D UV from the measured and modelled spectral irradiances, respectively, by weighting CIE Erythema and Vitamin D3 generation functions (Kazantzidis et al., 2009; Fioletov et al., 2010). In particular, McKenzie et al. (2009) suggested the algorithm to estimate vitamin-D production UV from erythemal UV (or UV index) and determined the optimum conditions of UV exposure based on skin type Ⅱ according to the Fitzpatrick (1988). Recently, there are various demands for risks and benefits of surface UV radiation on public health over Korea, thus it is necessary to estimate optimal UV exposure time suitable to skin type of East Asians. This study examined the relationship between erythemally weighted UV (UVEry) and vitamin D weighted UV (UVVitD) from spectral UV measurements during 2006-2010. The temporal variations of the ratio (UVVitD/UVEry) were also analyzed and the ratio as a function of UV index was applied to the broadband UV measured by UV-Biometer at 6 sites in Korea Thus, the optimal UV exposure time for vitamin D3 synthesis and erythema was estimated for diurnal, seasonal, and annual scales over Korea. In summer with high surface UV radiation, short exposure time leaded to sufficient vitamin D and erythema and vice

  18. Dispersion and surface functionalization of oxide nanoparticles for transparent photocatalytic and UV-protecting coatings and sunscreens

    Directory of Open Access Journals (Sweden)

    Bertrand Faure, German Salazar-Alvarez, Anwar Ahniyaz, Irune Villaluenga, Gemma Berriozabal, Yolanda R De Miguel and Lennart Bergström

    2013-01-01

    Full Text Available This review describes recent efforts on the synthesis, dispersion and surface functionalization of the three dominating oxide nanoparticles used for photocatalytic, UV-blocking and sunscreen applications: titania, zinc oxide, and ceria. The gas phase and liquid phase synthesis is described briefly and examples are given of how weakly aggregated photocatalytic or UV-absorbing oxide nanoparticles with different composition, morphology and size can be generated. The principles of deagglomeration are reviewed and the specific challenges for nanoparticles highlighted. The stabilization of oxide nanoparticles in both aqueous and non-aqueous media requires a good understanding of the magnitude of the interparticle forces and the surface chemistry of the materials. Quantitative estimates of the Hamaker constants in various media and measurements of the isoelectric points for the different oxide nanoparticles are presented together with an overview of different additives used to prepare stable dispersions. The structural and chemical requirements and the various routes to produce transparent photocatalytic and nanoparticle-based UV-protecting coatings, and UV-blocking sunscreens are described and discussed.

  19. Survival of Staphylococcus aureus exposed to UV radiation on the surface of ceramic tiles coated with TiO2.

    Science.gov (United States)

    Szczawiński, J; Tomaszewski, H; Jackowska-Tracz, A; Szczawińska, M E

    2011-01-01

    The aim of this study was to determine and compare the antimicrobial activity of UV radiation of wavelength 253.7 nm (used in typical germicidal lamps) against Staphylococcus aureus on the surfaces of conventionally produced white ceramic wall tiles (matt and shiny) and the same tiles coated with TiO2 using three different methods: RF diode sputtering, atmospheric pressure chemical vapour deposition (APCVD) and spray pyrolysis deposition (SPD). Results clearly indicate that the bactericidal action of UV radiation is much stronger on the surfaces of tiles coated with TiO2 than on the tiles uncovered. The strongest bactericidal effect of UV radiation was found for film prepared by APCVD. Results of experiments for shiny and matt tiles did not differ statistically. The use of ceramic wall tiles coated with TiO2 films in hospitals, veterinary clinics, laboratories, food processing plants and other places where UV radiation is applied for disinfection should greatly improve the efficiency of this treatment.

  20. Hydrophobic recovery of UV/ozone treated poly(dimethylsiloxane): adhesion studies by contact mechanics and mechanism of surface modification

    Science.gov (United States)

    Oláh, Attila; Hillborg, Henrik; Vancso, G. Julius

    2005-01-01

    Silicone elastomers (Sylgard 184 and 170), based on poly(dimethylsiloxane) (PDMS), were surface treated by a combined exposure to UV and ozone. The effects of the treatments were analyzed as a function of time elapsed after stopping the treatments using different standard surface characterization techniques, such as water contact angle measurements, XPS and atomic force microscopy (AFM). However, the primary focus of this study was to apply the Johnson-Kendall-Roberts (JKR) contact mechanics approach to investigate PDMS samples prior to and following UV/ozone surface treatment. A gradual formation of a hydrophilic, silica-like surface layer with increasing modulus was observed with increasing UV/ozone exposure. A subsequent hydrophobic recovery after UV/ozone exposure was observed, as indicated by increasing contact angles. This supports the hypothesis that the hydrophobic recovery is mainly caused by the gradual coverage of a permanent silica-like structure with free siloxanes and/or reorientation of polar groups. PDMS containing a homogenously dispersed filler (Sylgard 184), exhibited a decreasing surface roughness (by AFM) when the oxidized surface region "collapsed" into a smooth SiO x layer (final surface roughness Sylgard 170), exhibited an increasing surface roughness with treatment dose, which was attributed to the "collapse" of the oxidized surface region thus exposing the contours of the underlying filler aggregates (final surface roughness ˜140 nm). A dedicated device was designed and built to study the contact mechanics behavior of PDMS prior to, and following surface treatment. The value of the combined elastic modulus obtained for PDMS lens and semi-infinite flat surface system showed an increase in full agreement with the formation of a silica-like layer exhibiting a high elastic modulus (compared with untreated PDMS). The work of adhesion observed in JKR experiments exhibited an increasing trend as a function of treatment done in agreement with

  1. Effect of emissivity uncertainty on surface temperature retrieval over urban areas: Investigations based on spectral libraries

    Science.gov (United States)

    Chen, Feng; Yang, Song; Su, Z.; Wang, Kai

    2016-04-01

    Land surface emissivity (LSE) is a prerequisite for retrieving land surface temperature (LST) through single channel methods. According to error model, a 0.01 (1%) uncertainty of LSE may result in a 0.5 K error in LST under a moderate condition, while an obvious error (approximately 1 K) is possible under a warmer and less humid situation. Significant emissivity variations are presented among the anthropogenic materials in three spectral libraries, which raise a critical question that whether urban LSE can be estimated accurately to meet the needs for LST retrieval. Methods widely used for urban LSE estimation are investigated, including the classification-based method, the spectral-index based method, and the linear spectral mixture model (LSMM). Results indicate that the classification-based method may not be effectively applicable for urban LSE estimation, due mainly to the insignificant relation between the short-wave multispectral reflectance and the long-wave thermal emissivity shown by the spectra. Compared with the classification-based method, the LSMM shows relatively more accurate predictions, whereas, the performance of the LSMM largely depends on the determination of endmembers. Obvious uncertainties in LSE estimation likely appear if endmembers are determined improperly. Increasing the spectra for endmembers is a practical and beneficial means for LSMM when there is not a priori knowledge, which emphasizes the necessity of building a comprehensive spectral library of urban materials. Furthermore, the LST retrieval from a single channel of Landsat 8 is more challenging as compared with the retrieval from the channels of its predecessors-Landsat 4/5/7.

  2. The PROCESS experiment: amino and carboxylic acids under Mars-like surface UV radiation conditions in low-earth orbit.

    Science.gov (United States)

    Noblet, Audrey; Stalport, Fabien; Guan, Yuan Yong; Poch, Olivier; Coll, Patrice; Szopa, Cyril; Cloix, Mégane; Macari, Frédérique; Raulin, Francois; Chaput, Didier; Cottin, Hervé

    2012-05-01

    The search for organic molecules at the surface of Mars is a top priority of the next Mars exploration space missions: Mars Science Laboratory (NASA) and ExoMars (ESA). The detection of organic matter could provide information about the presence of a prebiotic chemistry or even biological activity on this planet. Therefore, a key step in interpretation of future data collected by these missions is to understand the preservation of organic matter in the martian environment. Several laboratory experiments have been devoted to quantifying and qualifying the evolution of organic molecules under simulated environmental conditions of Mars. However, these laboratory simulations are limited, and one major constraint is the reproduction of the UV spectrum that reaches the surface of Mars. As part of the PROCESS experiment of the European EXPOSE-E mission on board the International Space Station, a study was performed on the photodegradation of organics under filtered extraterrestrial solar electromagnetic radiation that mimics Mars-like surface UV radiation conditions. Glycine, serine, phthalic acid, phthalic acid in the presence of a mineral phase, and mellitic acid were exposed to these conditions for 1.5 years, and their evolution was determined by Fourier transform infrared spectroscopy after their retrieval. The results were compared with data from laboratory experiments. A 1.5-year exposure to Mars-like surface UV radiation conditions in space resulted in complete degradation of the organic compounds. Half-lives between 50 and 150 h for martian surface conditions were calculated from both laboratory and low-Earth orbit experiments. The results highlight that none of those organics are stable under low-Earth orbit solar UV radiation conditions.

  3. Direct spectral analysis of tea samples using 266 nm UV pulsed laser-induced breakdown spectroscopy and cross validation of LIBS results with ICP-MS.

    Science.gov (United States)

    Gondal, M A; Habibullah, Y B; Baig, Umair; Oloore, L E

    2016-05-15

    Tea is one of the most common and popular beverages spanning vast array of cultures all over the world. The main nutritional benefits of drinking tea are its anti-oxidant properties, presumed protection against certain cancers, inhibition of inflammation and possible protective effects against diabetes. Laser induced breakdown spectrometer (LIBS) was assembled as a powerful tool for qualitative and quantitative analysis of various brands of tea samples using 266 nm pulsed UV laser. LIBS spectra for six brands of tea samples in the wavelength range of 200-900 nm was recorded and all elements present in our tea samples were identified. The major toxic elements detected in several brands of tea samples were bromine, chromium and minerals like iron, calcium, potassium and silicon. The spectral assignment was conducted prior to the determination of concentration of each element. For quantitative analysis, calibration curves were drawn for each element using standard samples prepared in known concentration in the tea matrix. The plasma parameters (electron temperature and electron density) were also determined prior to the tea samples spectroscopic analysis. The concentration of iron, chromium, potassium, bromine, copper, silicon and calcium detected in all tea samples was between 378-656, 96-124, 1421-6785, 99-1476, 17-36, 2-11 and 92-130 mg L(-1) respectively. The limits of detection estimated for Fe, Cr, K, Br, Cu, Si, Ca in tea samples were 22, 12, 14, 11, 6, 1 and 12 mg L(-1) respectively. To further confirm the accuracy of our LIBS results, we determined the concentration of each element present in tea samples by using standard analytical technique like ICP-MS. The concentrations detected with our LIBS system are in excellent agreement with ICP-MS results. The system assembled for spectral analysis in this work could be highly applicable for testing the quality and purity of food and also pharmaceuticals products. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Comparison of UV-RSS spectral measurements and TUV model runs for clear skies for the May 2003 ARM aerosol intensive observation period

    Directory of Open Access Journals (Sweden)

    P. W. Kiedron

    2008-03-01

    Full Text Available The first successful deployment of the fully-operational ultraviolet rotating shadow-band spectroradiometer occurred during the May 2003 US Department of Energy's Atmospheric Radiation Measurement program's Aerosol Intensive Observation Period. The aerosol properties in the visible range were characterized using redundant measurements with several instruments to determine the column aerosol optical depth, the single scattering albedo, and the asymmetry parameter needed as input for radiative transfer calculations of the downwelling direct normal and diffuse horizontal solar irradiance in clear-sky conditions. The Tropospheric Ultraviolet and Visible (TUV radiative transfer model developed by Madronich and his colleagues at the US National Center for Atmospheric Research was used for the calculations of the spectral irradiance between 300–360 nm. Since there are few ultraviolet measurements of aerosol properties, most of the input aerosol data for the radiative transfer model are based on the assumption that UV input parameters can be extrapolated from the visible portion of the spectrum. Disagreements among available extraterrestrial spectra, which are discussed briefly, suggested that instead of comparing irradiances, measured and modeled spectral transmittances between 300–360 nm should be compared for the seven cases studied. Transmittance was calculated by taking the ratios of the measured irradiances to the Langley-derived, top-of-the-atmosphere irradiances. The cases studied included low to moderate aerosol loads and low to high solar-zenith angles. A procedure for retrieving single scattering albedo in the ultraviolet based on the comparisons of direct and diffuse transmittance is outlined.

  5. Surface Compositional Units on Mercury from Spectral Reflectance at Ultraviolet to Near-infrared Wavelengths

    Science.gov (United States)

    Izenberg, N. R.; Holsclaw, G. M.; Domingue, D. L.; McClintock, W. E.; Klima, R. L.; Blewett, D. T.; Helbert, J.; Head, J. W.; Sprague, A. L.; Vilas, F.; Solomon, S. C.

    2012-12-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has been acquiring reflectance spectra of Mercury's surface for over 16 months. The Visible and Infrared Spectrograph (VIRS) component of MASCS has accumulated a global data set of more than 2 million spectra over the wavelength range 300-1450 nm. We have derived a set of VIRS spectral units (VSUs) from the following spectral parameters: visible brightness (R575: reflectance at 575 nm); visible/near-infrared reflectance ratio (VISr: reflectance at 415 nm to that at 750 nm); and ultraviolet reflectance ratio (UVr: reflectance at 310 nm to that at 390 nm). Five broad, slightly overlapping VSUs may be distinguished from these parameters. "Average VSU" areas have spectral parameters close to mean global values. "Dark blue VSU" areas have spectra with low R575 and high UVr. "Red VSU" areas have spectra with low UVr and higher VISr and R575 than average. "Intermediate VSU" areas have spectra with higher VISr than VSU red, generally higher R575, and a wide range of UVr. "Bright VSU" areas have high R575 and VISr and intermediate UVr. Several units defined by morphological or multispectral criteria correspond to specific VSUs, including low-reflectance material (dark blue VSU), pyroclastic deposits (red VSU), and hollows (intermediate VSU), but these VSUs generally include other types of areas as well. VSU definitions are complementary to those obtained by unsupervised clustering analysis. The global distribution of VIRS spectral units provides new information on Mercury's geological evolution. Much of Mercury's northern volcanic plains show spectral properties ranging from those of average VSU to those of red VSU, as does a large region in the southern hemisphere centered near 50°S, 245°E. Dark blue VSU material is widely distributed, with concentrations south of the northern plains, around the Rembrandt and

  6. Thermal, spectral, and surface properties of LED light-polymerized bulk fill resin composites.

    Science.gov (United States)

    Pişkin, Mehmet Burçin; Atalı, Pınar Yılmaz; Figen, Aysel Kantürk

    2015-02-01

    The aim of this study was to evaluate the thermal, spectral, and surface properties of four different bulk fill materials – SureFil SDR (SDR, Dentsplay DETREY), QuixFil (QF, Dentsplay DETREY), X-tra base (XB, Voco) X-tra fil (XF, Voco) – polymerized by light-emitting diode (LED). Resin matrix, filler type, size and amount, and photoinitiator types influence the degree of conversion. LED-cured bulk fill composites achieved sufficient polymerization. Scanning electron microscope (SEM) analysis revealed different patterns of surface roughness, depending on the composite material. Bulk fill materials showed surface characteristics similar to those of nanohybrid composites. Based on the thermal analysis results, glass transition (T(g)) and initial degradation (T(i)) temperatures changed depending on the bulk fill resin composites.

  7. Utilization of the UV laser with picosecond pulses for the formation of surface microstructures on elastomeric plastics

    Science.gov (United States)

    Antoszewski, B.; Tofil, S.; Scendo, M.; Tarelnik, W.

    2017-08-01

    Elastomeric plastics belong to a wide range of polymeric materials with special properties. They are used as construction material for seals and other components in many branches of industry and, in particular, in the biomedical industry, mechatronics, electronics and chemical equipment. The micromachining of surfaces of these materials can be used to build micro-flow, insulating, dispensing systems and chemical and biological reactors. The paper presents results of research on the effects of micro-machining of selected elastomeric plastics using a UV laser emitting picosecond pulses. The authors see the prospective application of the developed technology in the sealing technique in particular to shaping the sealing pieces co-operating with the surface of the element. The result of the study is meant to show parameters of the UV laser’s performance when producing typical components such as grooves, recesses for optimum ablation in terms of quality and productivity.

  8. Synthesis, spectral (FT-IR, UV-visible, NMR) features, biological activity prediction and theoretical studies of 4-Amino-3-(4-hydroxybenzyl)-1H-1,2,4-triazole-5(4H)-thione and its tautomer

    Science.gov (United States)

    Srivastava, Ambrish Kumar; Kumar, Abhishek; Misra, Neeraj; Manjula, P. S.; Sarojini, B. K.; Narayana, B.

    2016-03-01

    Triazole compounds constitute an important class of organic chemistry due to their various biological and corrosion inhibition activities. The synthesis scheme of a new triazole compound namely, 4-Amino-3-(4-hydroxybenzyl)-1H-1,2,4-triazole-5(4H)-thione (4AHT) has been theoretically analyzed. Our density functional theory (DFT) based calculations show that the synthesis of 4AHT is energetically feasible at the room temperature as the reaction is exothermic, spontaneous as well as favored in forward direction. The calculated bond-lengths are found to be in good agreement with corresponding crystallographic values. We have considered two possible tautomers of 4AHT viz. thione and thiol forms. The FT-IR (KBr disc), UV-visible (ethanol) and 1H-NMR (DMSO) spectra of 4AHT have been recorded. The vibrational modes have been assigned on the basis of their potential energy distributions and scaled wavenumbers agree well with the FT-IR wavenumbers. Time dependent DFT calculations are performed to analyze the electronic transitions for various excited states which reproduce the experimental peak observed in UV-visible spectrum. Using gauge independent atomic orbital method 1H-NMR chemical shifts have been calculated and correlated with the experimental chemical shifts with the linear correlation coefficient of 0.9453. Our spectral analyses reveal the dominance of thione over thiol form of 4AHT. The chemical reactivity of 4AHT has been discussed by molecular electrostatic potential surface as well as various electronic parameters. The biological activities of 4AHT have also been explored theoretically and it has been found that the title molecule can act as a potential inhibitor of cyclin-dependent kinase 5 enzyme. These findings may guide the synthesis and design of new triazole compounds with interesting biological activity.

  9. Non-UV based germicidal activity of metal-doped TiO2 coating on solid surfaces

    Institute of Scientific and Technical Information of China (English)

    LIU Li-fen; John Barford; YEUNG King Lun; SI Grace

    2007-01-01

    A stain-based screening method was developed to screen different catalyst coatings for their germicidal activity. A Baclight dead/live bacteria viability kit (invitrogen, molecular probes) was used for staining the cell. The screening was carried out following a standard procedure. This included loading cell suspension to solid surface and maintaining contact for 30 min, then staining with a mixture containing dyes. The stained cells were observed using an epifluorescent microscope and photographed using a CCD camera under UV. Metal-doped TiO2 coatings on Al plates were prepared and tested for non-UV germicidal activity without using UV. It was tested using model microorganisms such as Bakers Yeast (Saccharomyces cerevisiae), Bacillus subtilis, Pseudomonas putida, and Escherichia coli. On the basis of the germicidal activity of catalyst and the degree of damage caused to the cells, the stained cells may appear green (viable), green with red or yellow nuclei and yellow (compromised) or red (nonviable). According to their stained color, cells were counted to calculate the percentage of dead, live, and compromised cells. Compromised cells are cells that grow very slowly after reculturing indicating a degree of reversible cell damage. Screening the germicidal activity using this staining method is accurate and efficient, and requires less time than the culture-based method. A modification to the procedure for measuring germicidal activity of rough surfaces or fibrous coatings was developed. Both TiO2 and metal-doped TiO2 (Ag, Pt, Au, Cu) possess non-UV based germicidal activity. The germicidal activity of TiO2 was found to be related with its wetting property and can be improved by UV irradiation before testing. It is not greatly affected by contact time, indicating a fast acting germicidal activity.

  10. Classification of Clean and Dirty Pighouse Surfaces Based on Spectral Reflectance

    DEFF Research Database (Denmark)

    Blanke, Mogens; Braithwaite, Ian David; Zhang, Guo-Qiang

    2004-01-01

    Current pig house cleaning procedures are hazardous to the health of farm workers, and yet necessary if the spread of disease between batches of animals is to be satisfactorily controlled. Autonomous cleaning using robot technology offers salient benefits. This report addresses the feasibility...... of designing a vision based system to locate dirty areas and subsequently direct a cleaning robot to remove dirt. Novel results include the characterisation of the spectral reflectance of real surfaces and dirt in a pig house and the design of illumination to obtain discrimination of clean from dirty areas...

  11. Nonlocal Symmetries, Spectral Parameter and Minimal Surfaces in AdS/CFT

    CERN Document Server

    Klose, Thomas; Münkler, Hagen

    2016-01-01

    We give a general account of nonlocal symmetries in symmetric space models and their relation to the AdS/CFT correspondence. In particular, we study a master symmetry which generates the spectral parameter and acts as a level-raising operator on the classical Yangian generators. The master symmetry extends to an infinite tower of symmetries with nonlocal Casimir elements as associated conserved charges. We discuss the algebraic properties of these symmetries and establish their role in explaining the recently observed one-parameter deformation of holographic Wilson loops. Finally, we provide a numerical framework, in which discretized minimal surfaces and their master symmetry deformation can be calculated.

  12. Potentiometric and UV Spectral Studies of Binary and Ternary Complexes of Some Metal Ions with N-Acetylcysteine and Amino Acids

    Directory of Open Access Journals (Sweden)

    Shaesta Quyoom

    2009-01-01

    Full Text Available The formation constants of the binary 1:1 and 1:2 complexes of Cu(II, Zn(II, Cd(II, Hg(II, and Pb(II with N-acetylcysteine (NAC and 1:1:1 ternary complexes of the said metal ions with NAC as a primary ligand and some biologically important amino acids as secondary ligands have been determined potentiometrically in aqueous medium. Acid dissociation constants of the ligands used and the formation constants of the binary and the ternary complexes were determined at 25 °C and in ionic strength I=0.1 mol dm-3 (KNO3.The formation constants of the 1:1 complexes were found to be higher than 1:2 complexes and the metal ions follow the order Hg(II >Cu(II >Cd(II >Zn(II. In addition UV-spectral studies of the NAC-Metal (II complexes have also been conducted at appropriate pH values to give further information about the structural nature of NAC- Metal (II complexes in aqueous medium.

  13. Surface-enhanced Raman Spectral Measurements of 5-Fluorouracil in Saliva

    Directory of Open Access Journals (Sweden)

    John Murren

    2008-10-01

    Full Text Available The ability of surface-enhanced Raman spectroscopy (SERS to measure 5-fluorouracil (5-FU in saliva is presented. The approach is based on the capacity of Raman spectroscopy to provide a unique spectral signature for virtually every chemical, and the ability of SERS to provide μg/mL sensitivity. A simple sampling method, that employed 1-mm glass capillaries filled with silver-doped sol-gels, was developed to isolate 5-FU from potential interfering chemical components of saliva and simultaneously provide SERSactivity. The method involved treating a 1 mL saliva sample with 1 mL of acetic acid, drawing 10 μL of sample into a SERS-active capillary by syringe, and then measuring the SER spectrum. Quality SER spectra were obtained for samples containing as little as 2 μg of 5-FU in 1 mL saliva. The entire process, the acid pretreatment, extraction and spectral measurement, took less than 5 minutes. The SERS of 5-fluorouridine and 5-fluoro-2’-deoxyuridine, two major metabolites of 5-FU, were also measured and shown to have unique spectral peaks. These measurements suggest that disposable SERS-active capillaries could be used to measure 5-FU and metabolite concentrations in chemotherapy patient saliva, thereby providing metabolic data that would allow regulating dosage. Tentative vibrational mode assignments for 5-FU and its metabolites are also given.

  14. Enhancement of photoelectrochemical and photocathodic protection properties of TiO2 nanotube arrays by simple surface UV treatment

    Science.gov (United States)

    Zhang, Tingting; Liu, Yupeng; Liang, Jun; Wang, Daoai

    2017-02-01

    A simple and efficient surface treatment method toward practical applications to enhance photo response of TiO2 nanotube arrays (NTs) photoelectrode was reported. TiO2 NTs were prepared by two-step electrochemical anodization methods, following by surface ultra violet light (UV) illumination treatment, which can produce amounts of hydroxyl groups on the surface of TiO2 NTs photoelectrode. The photoelectrochemical measurements demonstrate that the photocurrent density of the UV treated TiO2 NTs photoelectrode enhances by 50% than that of the pristine TiO2 NTs photoelectrode. More interestingly, the decayed photocurrent density of TiO2 NTs can recover the high value by illumination treatment again after using/storing for several days. Additionally, open circuit potential, tafel curves and electrochemical impedance spectroscopy measurements exhibit that the UV illumination treatment for TiO2 NTs photoelectrode is an easy and effective strategy to protect 304 stainless steel from corrosion by photogenerated cathode protection.

  15. Asteroid surface archaeology: Identification of eroded impact structures by spectral properties on (4) Vesta

    Science.gov (United States)

    Hoffmann, M.; Nathues, A.; Schäfer, M.; Schmedemann, N.; Vincent, J.; Russell, C.

    2014-07-01

    Introduction: Vesta's surface material is characterized as a deep regolith [1,2], mobilized by countless impacts. The almost catastrophic impact near Vesta's south pole, which has created the Rheasilvia basin, and the partly overlapping older impact of similar size, Veneneia, have not only reshaped the areas of their interior (roughly 50 % of the Vesta surface), but also emplaced each time a huge ejecta blanket of similar size, thus covering the whole remaining surface. In this context, pristine and even younger morphologic features have been erased. However, the spectral signatures of the early differentiation and alteration products by impacts have partially remained in situ. While near the north pole several large old eroded impact features are visible, the equatorial zone close to the basin rims seems to be void of those. Since it is unlikely, that this zone has been entirely avoided by large projectiles, in this area the results of such impacts may have left morphologically not detectable remnants: Individual distribution of particle sizes and altered photometric properties, excavated layers, shock metamorphism, melt generation inside particles and on macroscopic scales, and emplacement of exogenous projectile material. An analysis by color ratio images and spatial profiles of diagnostic spectral parameters reveals such features. Results: Based on local spectroscopic evidence we have detected eroded impact features of three categories: 1) Small craters with diameters of a few kilometers, 2) Large craters or, if even larger, incipient impact basins, 3) Sub-global ejecta blankets. The eastern part of Feralia Planitia, diameter 140 km, has little evidence of a round outline in the shape model, but it features spectral gradients towards its center. A feature of similar size, centered north of Lucaria Tholus becomes only visible by a similar spectra gradient and a circular outline in specific spectral ratio mosaics. These features seem to be related to the

  16. Characterizing Earthflow Surface Morphology With Statistical and Spectral Analyses of Airborne Laser Altimetry

    Science.gov (United States)

    McKean, J.; Roering, J.

    High-resolution laser altimetry can depict the topography of large landslides with un- precedented accuracy and allow better management of the hazards posed by such slides. The surface of most landslides is rougher, on a local scale of a few meters, than adjacent unfailed slopes. This characteristic can be exploited to automatically detect and map landslides in landscapes represented by high resolution DTMs. We have used laser altimetry measurements of local topographic roughness to identify and map the perimeter and internal features of a large earthflow in the South Island, New Zealand. Surface roughness was first quantified by statistically characterizing the local variabil- ity of ground surface orientations using both circular and spherical statistics. These measures included the circular resultant, standard deviation and dispersion, and the three-dimensional spherical resultant and ratios of the normalized eigenvalues of the direction cosines. The circular measures evaluate the amount of change in topographic aspect from pixel-to-pixel in the gridded data matrix. The spherical statistics assess both the aspect and steepness of each pixel. The standard deviation of the third di- rection cosine was also used alone to define the variability in just the steepness of each pixel. All of the statistical measures detect and clearly map the earthflow. Cir- cular statistics also emphasize small folds transverse to the movement in the most active zone of the slide. The spherical measures are more sensitive to the larger scale roughness in a portion of the slide that includes large intact limestone blocks. Power spectra of surface roughness were also calculated from two-dimensional Fourier transformations in local test areas. A small earthflow had a broad spectral peak at wavelengths between 10 and 30 meters. Shallower soil failures and surface erosion produced surfaces with a very sharp spectral peak at 12 meters wavelength. Unfailed slopes had an order of magnitude

  17. Applying Spectral Unmixing to Determine Surface Water Parameters in a Mining Environment

    Directory of Open Access Journals (Sweden)

    Veronika Kopačková

    2014-11-01

    Full Text Available Compared to natural waters, mine waters represent an extreme water type that is frequently heavily polluted. Although they have been traditionally monitored by in situ measurements of point samples taken at regular intervals, the emergence of a new generation of multispectral and hyperspectral (HS sensors means that image spectroscopy has the potential to become a modern method for monitoring polluted surface waters. This paper describes an approach employing linear Spectral Unmixing (LSU for analysis of hyperspectral image data to map the relative abundances of mine water components (dissolved Fe—Fediss, dissolved organic carbon—DOC, undissolved particles. The ground truth data (8 monitored ponds were used to validate the results of spectral mapping. The same approach applied to HS data was tested using the image data resampled to WorldView2 (WV2 spectral resolution. A key aspect of the image data processing was to define the proper pure image end members for the fundamental water types. The highest correlations detected between the studied water parameters and the fractional images using the HyMap and the resampled WV2 data, respectively, were: dissolved Fe (R2 = 0.74 and R2vw2 = 0.6, undissolved particles (R2 = 0.57 and R2vw2 = 0.49 and DOC (R2 = 0.42 and R2vw2 < 0.40. These fractional images were further classified to create semi-quantitative maps. In conclusion, the classification still benefited from the higher spectral resolution of the HyMap data; however the WV2 reflectance data can be suitable for mapping specific inherent optical properties (SIOPs, which significantly differ from one another from an optical point of view (e.g., mineral suspension, dissolved Fe and phytoplankton, but it seems difficult to differentiate among diverse suspension particles, especially when the waters have more complex properties (e.g., mineral particles, DOC together with tripton or other particles, etc..

  18. Solar UV Irradiation-Induced Production of Greenhouse Gases from Plant Surfaces: From Leaf to Earth

    DEFF Research Database (Denmark)

    Mikkelsen, Teis Nørgaard; Bruhn, Dan; Ambus, Per

    2016-01-01

    During the past few decades it has been documented that the ultra-violet (UV) component of natural sunlight alone or in combination with visible light can instantaneously stimulate aerobic plant production of a range of important trace gases: CH4, CO2, CO, short-chain hydrocarbons/ non...... for CH4 production, but underlying mechanisms are not fully known. For other gases such generating processes have not been established yet and mechanisms remain hypothetical. Field measurements of UV-induced emissions of the gases under natural light conditions are scarce. Therefore, realistic upscaling...... to the ecosystem level is uncertain for all gases. Nevertheless, based on empirical response curves, we propose the first global upscaling of UV-induced N2O and CO to illustrate emission ranges from a global perspective and as a contribution to an ongoing quantification process. When scaled to the global level...

  19. A method of laser micro-polishing for metallic surface using UV nano-second pulse and CW lasers

    CERN Document Server

    Jang, Pong-Ryol; Ji, Kum-Hyok; Kim, Nam-Chol

    2014-01-01

    During laser micro-polishing, the constant control of laser energy density is a key technology to improve the surface roughness. In this paper, a method which controls the energy density of UV(ultraviolet) pulse laser in real time with the control of CW(continuous wave) laser spot size in laser micro-polishing for metallic surface was presented. The experimental and analytical considerations of several influence factors such as laser spot size, fusion zone and focal offset were investigated. In addition, using a laser micro-polishing system manufactured with this method, the laser micro-polishing experiments on the two different surface shapes of stainless steel 316L were conducted. For the inclined or curved surface, the surface roughness improvements of up to 56.4% and 57.3% were respectively obtained, and the analysis of the results were discussed.

  20. Investigation of γ-(2,3-Epoxypropoxypropyltrimethoxy Silane Surface Modified Layered Double Hydroxides Improving UV Ageing Resistance of Asphalt

    Directory of Open Access Journals (Sweden)

    Canlin Zhang

    2017-01-01

    Full Text Available γ-(2,3-Epoxypropoxypropyltrimethoxy silane surface modified layered double hydroxides (KH560-LDHs were prepared and used to improve the ultraviolet ageing resistance of asphalt. The results of X-ray photoelectron spectrometry (XPS indicated that KH560 has been successfully grafted onto the surface of LDHs. The agglomeration of LDHs particles notably reduced after KH560 surface modification according to scanning electron microscopy (SEM, which implied that the KH560 surface modification was helpful to promote the dispersibility of LDHs in asphalt. Then, the influence of KH560-LDHs and LDHs on the physical and rheological properties of asphalt before and after UV ageing was thoroughly investigated. The storage stability test showed that the difference in softening point (ΔS of LDHs modified asphalt decreased from 0.6 °C to 0.2 °C at an LDHs content of 1% after KH560 surface modification, and the tendency became more pronounced with the increase of LDH content, indicating that KH560 surface modification could improve the stability of LDHs in asphalt. After UV ageing, the viscous modulus (G’’ of asphalt significantly reduced, and correspondingly, the elastic modulus (G’ and rutting factor (G*/sin δ rapidly increased. Moreover, the asphaltene increased and the amount of “bee-like” structures of the asphalt decreased. Compared with LDHs, KH560-LDHs obviously restrained performance deterioration of the asphalt, and helped to relieve the variation of the chemical compositions and morphology of asphalt, which suggested that the improvement of KH560-LDHs on UV ageing resistance of asphalt was superior to LDHs.

  1. Impact of soil moisture and winter wheat height from the Loess Plateau in Northwest China on surface spectral albedo

    Science.gov (United States)

    Li, Zhenchao; Yang, Jiaxi; Gao, Xiaoqing; Zheng, Zhiyuan; Yu, Ye; Hou, Xuhong; Wei, Zhigang

    2016-12-01

    The understanding of surface spectral radiation and reflected radiation characteristics of different surfaces in different climate zones aids in the interpretation of regional surface energy transfers and the development of land surface models. This study analysed surface spectral radiation variations and corresponding surface albedo characteristics at different wavelengths as well as the relationship between 5-cm soil moisture and surface albedo on typical sunny days during the winter wheat growth period. The analysis was conducted using observational Loess Plateau winter wheat data from 2015. The results show that the ratio of atmospheric downward radiation to global radiation on typical sunny days is highest for near-infrared wavelengths, followed by visible wavelengths and ultraviolet wavelengths, with values of 57.3, 38.7 and 4.0%, respectively. The ratio of reflected spectral radiation to global radiation varies based on land surface type. The visible radiation reflected by vegetated surfaces is far less than that reflected by bare ground, with surface albedos of 0.045 and 0.27, respectively. Thus, vegetated surfaces absorb more visible radiation than bare ground. The atmospheric downward spectral radiation to global radiation diurnal variation ratios vary for near-infrared wavelengths versus visible and ultraviolet wavelengths on typical sunny days. The near-infrared wavelengths ratio is higher in the morning and evening and lower at noon. The visible and ultraviolet wavelengths ratios are lower in the morning and evening and higher at noon. Visible and ultraviolet wavelength surface albedo is affected by 5-cm soil moisture, demonstrating a significant negative correlation. Excluding near-infrared wavelengths, correlations between surface albedo and 5-cm soil moisture pass the 99% confidence test at each wavelength. The correlation with 5-cm soil moisture is more significant at shorter wavelengths. However, this study obtained surface spectral radiation

  2. Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains central facility

    Directory of Open Access Journals (Sweden)

    J. Delamere

    2011-09-01

    Full Text Available We present a method for identifying dominant surface type and estimating high spectral resolution surface albedo at the Atmospheric Radiation Measurement (ARM facility at the Southern Great Plains (SGP site in Oklahoma for use in radiative transfer calculations. Given a set of 6-channel narrowband visible and near-infrared irradiance measurements from upward and downward looking multi-filter radiometers (MFRs, four different surface types (snow-covered, green vegetation, partial vegetation, non-vegetated can be identified. A normalized difference vegetation index (NDVI is used to distinguish between vegetated and non-vegetated surfaces, and a scaled NDVI index is used to estimate the percentage of green vegetation in partially vegetated surfaces. Based on libraries of spectral albedo measurements, a piecewise continuous function is developed to estimate the high spectral resolution surface albedo for each surface type given the MFR albedo values as input. For partially vegetated surfaces, the albedo is estimated as a linear combination of the green vegetation and non-vegetated surface albedo values. The estimated albedo values are evaluated through comparison to high spectral resolution albedo measurements taken during several Intensive Observational Periods (IOPs and through comparison of the integrated spectral albedo values to observed broadband albedo measurements. The estimated spectral albedo values agree well with observations for the visible wavelengths constrained by the MFR measurements, but have larger biases and variability at longer wavelengths. Additional MFR channels at 1100 nm and/or 1600 nm would help constrain the high resolution spectral albedo in the near infrared region.

  3. Spectral locking in an extended area two-dimensional coherent grating surface emitting laser array

    Energy Technology Data Exchange (ETDEWEB)

    DeFreez, R.K.; Ximen, H.; Bossert, D.J.; Hunt, J.M.; Wilson, G.A.; Elliott, R.A.; Orloff, J. (Dept. of Applied Physics and Electrical Engineering, Oregon Graduate Center, Beaverton, OR (US)); Evans, G.A.; Carlson, N.W.; Lurie, M. (David Sarnoff Research Center, Princeton, NJ (US))

    1990-01-01

    The spectral properties of a monolithic pair of two-dimensional coherent grating surface emitting laser arrays optically coupled by means of total-internal-reflection (TIR) corner turning mirrors have been studied. Each of the pair consists of six groups of ten laterally {ital Y}-coupled, index-guided ridge lasers interspersed with second-order DBR grating sections in the longitudinal direction to provide feedback and surface emitting output coupling. The turning mirrors were formed by focused-ion-beam micromachining channels in the wafer angled at 45{degrees} to the laser waveguide. Locking of the emission spectra of the pair of GSE arrays and shifting of the spectrum of one of the pair by varying the drive current to one gain section in the other is demonstrated.

  4. Probing DNA-Protein Interactions on Surfaces Using Spectral Self-interference Fluorescence Microscopy

    Science.gov (United States)

    Dogan, Mehmet; Droge, Peter; Swan, Anna K.; Unlu, Selim; Goldberg, Bennett B.

    2007-03-01

    We are probing the interactions between double-stranded DNA and integration host factor (IHF) proteins [1] on surfaces using Spectral Self-interference Fluorescence Microscopy (SSFM) [2].The probing technique utilizes the spectral fringes produced by interference of direct and reflected emission from fluorescent molecules. The modified spectrum provides a unique signature of the axial position of the fluorophores. Using the SSFM technique, we probe the average location of the fluorescent markers attached to the DNA molecules to study the conformational changes in double-stranded DNA tethered to SiO2 surfaces. In the presence of IHF, a DNA bending protein, we observe reduction in the vertical position of fluorescent molecules suggesting the formation of IHF-DNA complex and IHF-induced DNA bending. We also discuss the results with different IHF strains and different binding conditions. [1] Q. Bao et. al., Gene, Vol.343 pp.99-106 (2004) [2] L.A. Moiseev et. al., Journal of Applied Physics, Vol.96, pp. 5311-5315 (2004)

  5. Detection of organic residues on food processing equipment surfaces by spectral imaging method

    Science.gov (United States)

    Qin, Jianwei; Jun, Won; Kim, Moon S.; Chao, Kaunglin

    2010-04-01

    Organic residues on equipment surfaces in poultry processing plants can generate cross contamination and increase the risk of unsafe food for consumers. This research was aimed to investigate the potential of LED-induced fluorescence imaging technique for rapid inspection of organic residues on poultry processing equipment surfaces. High-power blue LEDs with a spectral output at 410 nm were used as the excitation source for a line-scanning hyperspectral imaging system. Common chicken residue samples including fat, blood, and feces from ceca, colon, duodenum, and small intestine were prepared on stainless steel sheets. Fluorescence emission images were acquired from 120 samples (20 for each type of residue) in the wavelength range of 500-700 nm. LED-induced fluorescence characteristics of the tested samples were determined. PCA (principal component analysis) was performed to analyze fluorescence spectral data. Two SIMCA (soft independent modeling of class analogy) models were developed to differentiate organic residues and stainless steel samples. Classification accuracies using 2-class ('stainless steel' and 'organic residue') and 4-class ('stainless steel', 'fat', 'blood', and 'feces') SIMCA models were 100% and 97.5%, respectively. An optimal single-band and a band-pair that are promising for rapid residue detection were identified by correlation analysis. The single-band approach using the selected wavelength of 666 nm could generate false negative errors for chicken blood inspection. Two-band ratio images using 503 and 666 nm (F503/F666) have great potential for detecting various chicken residues on stainless steel surfaces. This wavelength pair can be adopted for developing a LED-based hand-held fluorescence imaging device for inspecting poultry processing equipment surfaces.

  6. Biodegradation improvement of poly(3-hydroxy-butyrate) films by entomopathogenic fungi and UV-assisted surface functionalization.

    Science.gov (United States)

    Kessler, Felipe; Marconatto, Leticia; Rodrigues, Roberta da Silva Bussamara; Lando, Gabriela Albara; Schrank, Augusto; Vainstein, Marilene Henning; Weibel, Daniel Eduardo

    2014-01-05

    Ultraviolet (UV)-assisted surface modification in the presence of oxygen was used as initial step to achieve controlled degradation of poly(3-hydroxy-butyrate), PHB, films by entomopathogenic fungi. Treated surfaces were investigated by surface analysis techniques (water contact angle, Fourier Transformed Infrared Spectroscopy in Attenuated Total Reflectance mode, X-ray Photoelectron Spectroscopy, Near-edge X-ray Absorption Fine Structure, Gel Permeation Chromatography, Optical Microscopy, Scanning Electron Microscopy, and weight loss). After the UV-assisted treatments, new carbonyl groups in new chemical environments were detected by XPS and NEXAFS spectroscopy. The oxidizing atmosphere did not allow the formation of CC bonds, indicating that Norrish Type II mechanism is suppressed during or by the treatments. The higher hydrophilicity and concentration of oxygenated functional groups at the surface of the treated films possibly improved the biodegradation of the films. It was observed a clear increase in the growth of this fungus when oxygenated groups were grafted on the polymers surfaces. This simple methodology can be used to improve and control the degradation rate of PHB films in applications that require a controllable degradation rate.

  7. Measuring and modeling the effect of surface moisture on the spectral reflectance of coastal beach sand.

    Science.gov (United States)

    Nolet, Corjan; Poortinga, Ate; Roosjen, Peter; Bartholomeus, Harm; Ruessink, Gerben

    2014-01-01

    Surface moisture is an important supply limiting factor for aeolian sand transport, which is the primary driver of coastal dune development. As such, it is critical to account for the control of surface moisture on available sand for dune building. Optical remote sensing has the potential to measure surface moisture at a high spatio-temporal resolution. It is based on the principle that wet sand appears darker than dry sand: it is less reflective. The goals of this study are (1) to measure and model reflectance under controlled laboratory conditions as function of wavelength (λ) and surface moisture (θ) over the optical domain of 350-2500 nm, and (2) to explore the implications of our laboratory findings for accurately mapping the distribution of surface moisture under natural conditions. A laboratory spectroscopy experiment was conducted to measure spectral reflectance (1 nm interval) under different surface moisture conditions using beach sand. A non-linear increase of reflectance upon drying was observed over the full range of wavelengths. Two models were developed and tested. The first model is grounded in optics and describes the proportional contribution of scattering and absorption of light by pore water in an unsaturated sand matrix. The second model is grounded in soil physics and links the hydraulic behaviour of pore water in an unsaturated sand matrix to its optical properties. The optical model performed well for volumetric moisture content θ 0.97), but underestimated reflectance for θ between 24-30% (R2 > 0.92), most notable around the 1940 nm water absorption peak. The soil-physical model performed very well (R2 > 0.99) but is limited to 4% > θ < 24%. Results from a field experiment show that a short-wave infrared terrestrial laser scanner (λ = 1550 nm) can accurately relate surface moisture to reflectance (standard error 2.6%), demonstrating its potential to derive spatially extensive surface moisture maps of a natural coastal beach.

  8. Measuring and modeling the effect of surface moisture on the spectral reflectance of coastal beach sand.

    Directory of Open Access Journals (Sweden)

    Corjan Nolet

    Full Text Available Surface moisture is an important supply limiting factor for aeolian sand transport, which is the primary driver of coastal dune development. As such, it is critical to account for the control of surface moisture on available sand for dune building. Optical remote sensing has the potential to measure surface moisture at a high spatio-temporal resolution. It is based on the principle that wet sand appears darker than dry sand: it is less reflective. The goals of this study are (1 to measure and model reflectance under controlled laboratory conditions as function of wavelength (λ and surface moisture (θ over the optical domain of 350-2500 nm, and (2 to explore the implications of our laboratory findings for accurately mapping the distribution of surface moisture under natural conditions. A laboratory spectroscopy experiment was conducted to measure spectral reflectance (1 nm interval under different surface moisture conditions using beach sand. A non-linear increase of reflectance upon drying was observed over the full range of wavelengths. Two models were developed and tested. The first model is grounded in optics and describes the proportional contribution of scattering and absorption of light by pore water in an unsaturated sand matrix. The second model is grounded in soil physics and links the hydraulic behaviour of pore water in an unsaturated sand matrix to its optical properties. The optical model performed well for volumetric moisture content θ 0.97, but underestimated reflectance for θ between 24-30% (R2 > 0.92, most notable around the 1940 nm water absorption peak. The soil-physical model performed very well (R2 > 0.99 but is limited to 4% > θ < 24%. Results from a field experiment show that a short-wave infrared terrestrial laser scanner (λ = 1550 nm can accurately relate surface moisture to reflectance (standard error 2.6%, demonstrating its potential to derive spatially extensive surface moisture maps of a natural coastal beach.

  9. Validation of an HPLC–UV method for the determination of digoxin residues on the surface of manufacturing equipment

    Directory of Open Access Journals (Sweden)

    ZORAN B. TODOROVIĆ

    2009-09-01

    Full Text Available In the pharmaceutical industry, an important step consists in the removal of possible drug residues from the involved equipments and areas. The cleaning procedures must be validated and methods to determine trace amounts of drugs have, therefore, to be considered with special attention. An HPLC–UV method for the determination of digoxin residues on stainless steel surfaces was developed and validated in order to control a cleaning procedure. Cotton swabs, moistened with methanol were used to remove any residues of drugs from stainless steel surfaces, and give recoveries of 85.9, 85.2 and 78.7 % for three concentration levels. The precision of the results, reported as the relative standard deviation (RSD, were below 6.3 %. The method was validated over a concentration range of 0.05–12.5 µg mL-1. Low quantities of drug residues were determined by HPLC–UV using a Symmetry C18 column (150´4.6 mm, 5 µm at 20 °C with an acetonitrile–water (28:72, v/v mobile phase at a flow rate of 1.1 mL min-1, an injection volume of 100 µL and were detected at 220 nm. A simple, selective and sensitive HPLC–UV assay for the determination of digoxin residues on stainless steel was developed, validated and applied.

  10. Anthropogenic changes in the surface all-sky UV-B radiation through 1850–2005 simulated by an Earth system model

    Directory of Open Access Journals (Sweden)

    S. Watanabe

    2012-06-01

    Full Text Available The historical anthropogenic change in the surface all-sky UV-B (solar ultraviolet: 280–315 nm radiation through 1850–2005 is evaluated using an Earth system model. Responses of UV-B dose to anthropogenic changes in ozone and aerosols are separately evaluated using a series of historical simulations including/excluding these changes. Increases in these air pollutants cause reductions in UV-B transmittance, which occur gradually/rapidly before/after 1950 in and downwind of industrial and deforestation regions. Furthermore, changes in ozone transport in the lower stratosphere, which is induced by increasing greenhouse gas concentrations, increase ozone concentration in the extratropical upper troposphere and lower stratosphere. These transient changes work to decrease the amount of UV-B reaching the Earth's surface, counteracting the well-known effect increasing UV-B due to stratospheric ozone depletion, which developed rapidly after ca. 1980. As a consequence, the surface UV-B radiation change between 1850 and 2000 is negative in the tropics and NH extratropics and positive in the SH extratropics. Comparing the contributions of ozone and aerosol changes to the UV-B change, the transient change in ozone absorption of UV-B mainly determines the total change in the surface UV-B radiation at most locations. On the other hand, the aerosol direct and indirect effects on UV-B play an equally important role to that of ozone in the NH mid-latitudes and tropics. A typical example is East Asia (25° N–60° N and 120° E–150° E, where the effect of aerosols (ca. 70% dominates the total UV-B change.

  11. Anthropogenic changes in the surface all-sky UV-B radiation through 1850–2005 simulated by an Earth system model

    Directory of Open Access Journals (Sweden)

    T. Yokohata

    2012-02-01

    Full Text Available The historical anthropogenic change in the surface all-sky UV-B (solar ultraviolet: 280–315 nm radiation through 1850–2005 is evaluated using an Earth system model. Responses of UV-B dose to anthropogenic changes in ozone and aerosols are separately evaluated using a series of historical simulations including/excluding these changes. Increases in these air pollutants cause reductions in UV-B transmittance, which occur gradually/rapidly before/after 1950 in and downwind of industrial and deforestation regions. Furthermore, changes in ozone transport in the lower stratosphere, which is induced by increasing greenhouse gas concentrations, increase ozone concentration in the extratropical upper troposphere and lower stratosphere. These transient changes work to decrease the amount of UV-B reaching the Earth's surface, counteracting the well-known effect increasing UV-B due to stratospheric ozone depletion, which developed rapidly after ca. 1980. As a consequence, the surface all-sky UV-B radiation change between 1850 and 2000 is negative in the tropics and NH extratropics and positive in the SH extratropics. Comparing the contributions of ozone and aerosol changes to the UV-B change, the transient change in ozone absorption of UV-B mainly determines the total change in the surface all-sky UV-B radiation at most locations. On the other hand, the aerosol direct and indirect effects on UV-B play an equally important role to that of ozone in the NH mid-latitudes and tropics. A typical example is East Asia (25° N–60° N and 120° E–150° E, where the effect of aerosols (ca. 70% dominates the total UV-B change.

  12. GALEX observations of the UV surface brightness and color profiles of the Local Group elliptical galaxy M32 (NGC221)

    CERN Document Server

    De Paz, A G; Sohn, Y J; Lee, Y W; Seibert, M; Rich, R M; Bianchi, L; Barlow, T A; Byun, Y I; Donas, J; Forster, K; Friedman, P G; Heckman, T M; Jelinsky, P N; Malina, R F; Martin, D C; Milliard, B; Morrissey, P F; Neff, S G; Schiminovich, D; Siegmund, O H W; Small, T; Szalay, A S; Welsh, B Y; Wyder, T K

    2004-01-01

    M32, the compact elliptical-galaxy companion to the Andromeda spiral galaxy has been imaged by the Galaxy Evolution Explorer (GALEX) in two ultraviolet bands, centered at ~1500 (FUV) and 2300 Angstroms (NUV). The imaging data have been carefully decomposed so as to properly account for the complicated background contamination from the disk of M31. We have derived the surface brightness and color profiles finding a slightly positive color gradient of Delta(FUV-B)/Delta log(r)=+0.15+/-0.03 within one effective radius. Earlier data from the Ultraviolet Imaging Telescope suggested that M32 had an extremely large (negative) FUV-optical color gradient (Delta(FUV-B)/Delta log(r)<-2), inverted with respect to the majority of gradients seen in giant elliptical galaxies. Our new results show that, despite of its very low UV-upturn, M32 has similar UV properties to those observed in luminous elliptical galaxies.

  13. Mapping the low-surface brightness Universe in the UV band with Lyα emission from IGM filaments

    Science.gov (United States)

    Silva, Marta B.; Kooistra, Robin; Zaroubi, Saleem

    2016-10-01

    A large fraction of the baryonic matter in the Universe is located in filaments in the intergalactic medium (IGM). However, the low surface brightness of these filaments has not yet allowed their direct detection except in very special regions in the circum-galactic medium. Here we simulate the intensity and spatial fluctuations in Lyman alpha (Lyα) emission from filaments in the IGM and discuss the prospects for the next generation of space-based instruments to detect the low-surface brightness Universe at ultraviolet (UV) wavelengths. Starting with a high-resolution N-body simulation, we obtain the dark matter density fluctuations and associate baryons with the dark matter particles assuming that they follow the same spatial distribution. The IGM thermal and ionization state is set by a model of the UV background and by the relevant cooling processes for a hydrogen and helium gas. The Lyα emissivity is then estimated, taking into account recombination and collisional excitation processes. We find that the detection of these filaments through their Lyα emission is well in the reach of the next generation of UV space-based instruments and so it should be achieved in the next decade. The density field is populated with halos and galaxies and their Lyα emission is estimated. Galaxies are treated as foregrounds and so we discuss methods to reduce their contamination from observational maps. Finally, we estimate the UV continuum background as a function of the redshift of the Lyα emission line and discuss how this continuum can affect observations.

  14. Significant Enhancement of the Adhesion between Metal Films and Polymer Substrates by UV-Ozone Surface Modification in Nanoscale.

    Science.gov (United States)

    Liu, Junshan; He, Licheng; Wang, Liang; Man, Yuncheng; Huang, Luyi; Xu, Zheng; Ge, Dan; Li, Jingmin; Liu, Chong; Wang, Liding

    2016-11-09

    Polymer metallization is extensively used in a variety of micro- and nanosystem technologies. However, the deposited metal film exhibits poor adhesion to polymer substrates, which may cause difficulties in many applications. In this work, ultraviolet (UV)-ozone surface modification is for the first time put forward to enhance the adhesion between metal films and polymer substrates. The adhesion of sputtered Cu films on UV-ozone modified poly(methyl methacrylate) (PMMA) substrates is enhanced by a factor of 6, and that of Au films is improved by a factor of 10. Moreover, metal films on the modified PMMA substrates can withstand a long-time liquid immersion. To understand the mechanism for the adhesion enhancement, the surface modification is studied with contact angle measurements, attenuated total reflection Fourier-transform infrared spectrometry (ATR-FTIR) and atomic force microscopy (AFM). Detailed characterization results indicate that the significant adhesion enhancement is attributed to the increases of both the surface wettability by generating some polar functional groups and the roughness of the surface in nanoscale. To demonstrate this novel polymer metallization method, a 6-in. PMMA chip with arrays of three-electrode electrochemical microsensors is designed and fabricated, and the microsensor exhibits excellent reproducibility, uniformity, and long-term stability.

  15. Air plasma or UV-irradiation applied to surface modification of pectin/poly(vinyl alcohol) blends

    Science.gov (United States)

    Kowalonek, Jolanta; Kaczmarek, Halina; Dąbrowska, Aldona

    2010-10-01

    Poly(vinyl alcohol), pectin and their blends with different components ratio were exposed to low-temperature air plasma or high energy UV-irradiation ( λ = 254 nm) for the purpose of surface modification. The physico-chemical changes in surface properties have been studied by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and contact angle measurements. Surface free energy of polymeric films, its polar and dispersive components have been calculated by Owens-Wendt method. Moreover, the work of adhesion was estimated and the recovery of hydrophobic properties of modified films after storage have been also studied. The few seconds air-plasma treatment caused more effective surface modification than 5-6 h UV-irradiation. The observed changes were partially reversible, contrary to these caused by photo-modification. It was found that pectin/PVA (50:50) blend was characterised by larger susceptibility to plasma modification compared to pure pectin and pure PVA, whereas the photosensitivity to radiation of 254 nm wavelength was the lowest for this specimen in comparison to other studied samples.

  16. Spectral calibration for deriving surface mineralogy of Asteroid (25143) Itokawa from Hayabusa Near-Infrared Spectrometer (NIRS) Data

    CERN Document Server

    Bhatt, Megha; Corre, Lucille Le; Sanchez, Juan A; Dunn, Tasha; Izawa, Matthew R M; Li, Jian-Yang; Becker, Kris J; Weller, Lynn

    2015-01-01

    We present spectral calibration equations for determining mafic silicate composition of near-Earth asteroid (25143) Itokawa from visible/near-infrared spectra measured using the Near Infrared Spectrometer (NIRS), on board the Japanese Hayabusa spacecraft. Itokawa was the target of the Hayabusa sample return mission and has a surface composition similar to LL-type ordinary chondrites. Existing laboratory spectral calibrations use a spectral wavelength range that is wider (0.75-2.5 microns) than that of the NIRS instrument (0.85-2.1 microns) making them unfit for interpreting the Hayabusa spectral data currently archived in the Planetary Data System. We used laboratory measured near-infrared reflectance spectra of ordinary (H, L and LL) chondrites from the study of Dunn et al. (2010), which we resampled to the NIRS wavelength range. Using spectral parameters extracted from these resampled spectra we established a relationship between band parameters and their mafic silicate composition (olivine and low-Ca pyrox...

  17. Spectral Analysis of Surface Features of Subaquaeous Pyroclastic Flow Deposits Around Santorini Volcano, Greece

    Science.gov (United States)

    Croff, K. L.; Sigurdsson, H.; Carey, S.; Alexandri, M.; Sakellariou, D.; Nomikou, P.

    2006-12-01

    Multibeam bathymetry mapping and seismic airgun surveys of the submarine region around the Santorini volcanic field in the Hellenic Arc (Greece) have revealed regions of terraced or step-like topography. These features may be related to the transport and deposition of submarine pyroclastic flows from the last major eruption of this volcano (~3600yrs. B.P.). The uppermost sediment sequence identified in seismic records has an average thickness of approximately 29 meters and may represent the pyroclastic flow deposits from this eruption. These terraced or step-like features are mainly located in areas that are approximately five kilometers offshore and at depths in the range of 200 to 800 meters. The seafloor in these areas has slope ratios on the order of 1:20. Profiles of the seafloor topography were sampled from seismic profiles that radiate from the Sanotrini caldera in five regions of interest. Spectral analysis of seafloor topography has been carried out to determine spectral characteristics of these features, including power spectrum, periodicity and amplitude of the waveforms, variance, and roughness of topography. The results are compared to surface features of the subaqueous pyroclastic deposits from the 1883 explosive eruption of Krakatau (Indonesia) and other areas with similar environments, to determine the parameters that are characteristic of this new feature of submarine volcaniclastic deposits.

  18. The impact of grid and spectral nudging on the variance of the near-surface wind speed

    DEFF Research Database (Denmark)

    Vincent, Claire Louise; Hahmann, Andrea N.

    2015-01-01

    variance in the Weather Research and Forecasting model is analyzed. Simulations are run on nested domains with horizontal grid spacing 15 and 5 km over the Baltic Sea region. For the 15 km domain, 36-hr simulations initialized each day are compared with 11-day simulations with either grid or spectral......Grid and spectral nudging are effective ways of preventing drift from large scale weather patterns in regional climate models. However, the effect of nudging on the wind-speed variance is unclear. In this study, the impact of grid and spectral nudging on near-surface and upper boundary layer wind...

  19. Spectral Analysis of Surface Wave for Empirical Elastic Design of Anchored Foundations

    Directory of Open Access Journals (Sweden)

    S. E. Chen

    2012-01-01

    Full Text Available Helical anchors are vital support components for power transmission lines. Failure of a single anchor can lead to the loss of an entire transmission line structure which results in the loss of power for downstream community. Despite being important, it is not practical to use conventional borehole method of subsurface exploration, which is labor intensive and costly, for estimating soil properties and anchor holding capacity. This paper describes the use of an empirical and elasticity-based design technique coupled with the spectral analysis of surface wave (SASW technique to provide subsurface information for anchor foundation designs. Based on small-strain wave propagation, SASW determines shear wave velocity profile which is then correlated to anchor holding capacity. A pilot project involving over 400 anchor installations has been performed and demonstrated that such technique is reliable and can be implemented into transmission line structure designs.

  20. Spatial Downscaling Research of Satellite Land Surface Temperature Based on Spectral Normalization Index

    Directory of Open Access Journals (Sweden)

    LI Xiaojun

    2017-03-01

    Full Text Available Aiming at the problem that the spatial and temporal resolution of land surface temperature (LST have the contradiction with each other, a new downscaling model was put forward, based on the TsHARP(an algorithm for sharpening thermal imagery downscaling method, this research makes improvements by selecting the better correlation of spectral index(normalized difference vegetation index, NDVI; normalized difference build-up index, NDBI; modified normalized difference water index, MNDWI; enhanced bare soil index, EBSI with LST, i.e., replaces the original NDVI with new spectral index according to the different surface land-cover types, to assess the accuracy of each downscaling method based on qualitative and quantitative analysis with synchronous Landsat 8 TIRS LST data. The results show that both models could effectively enhance the spatial resolution while simultaneously preserving the characteristics and spatial distribution of the original 1 km MODIS LST image, and also eliminate the “mosaic” effect in the original 1 km image, both models were proved to be effective and applicable in our study area; global scale analysis shows that the new model (RMSE:1.635℃ is better than the TsHARP method (RMSE:2.736℃ in terms of the spatial variability and accuracy of the results; the different land-cover types of downscaling statistical analysis shows that the TsHARP method has poor downscaling results in the low vegetation coverage area, especially for the bare land and building-up area(|MBE|>3℃, the new model has obvious advantages in the description of the low vegetation coverage area. Seasonal analysis shows that the downscaling results of two models in summer and autumn are superior to those in spring and winter, the new model downscaling results are better than the TsHARP method in the four seasons, in which the spring and winter downscaling improvement is better than summer and autumn.

  1. Synthesis of Perfluorinated Oxetane and Surface Properties of Its Cationic UV Cured Coating as a Reactive Additive

    Institute of Scientific and Technical Information of China (English)

    ZHAN Fu; ZHANG Yong; SHI Wen-fang

    2012-01-01

    Perfluorinated oxetane(F-OXE) was synthesized via the ring-opening reaction of epoxy-functionalized oxetane with 2-(perfluorooctyl)ethanol under base-catalysis,and characterized by FTIR and 1H NMR spectroscopy.The synthesized F-OXE was mixed with a commercial cationic UV curable resin,UVR6110,as a reactive additive at different mass fractions,and UV-irradiation cured in the presence of triphenylsulphonium hexafluoroantimonate as a cationic photoinitiator.The surface property study of cured films indicated that both hydrophobicity and oleophobicity were effectively enhanced by the addition of a small amount of F-OXE.The contact angles of water and 1-bromonaphthalene on the surface of the cured film with 1.0%(mass fraction) F-OXE loading increased from 72° to 106° and from 0° to 76°,respectively,compared with those on the surface of the film without F-OXE addition.The surface tension of UVR6110-F-OXE cured film decreased greatly from 55.6 mN/m of referenced film to 22.9 mN/m.The results from X-ray photoelectron spectroscopy analysis confirm the migration and aggregation effect of perfluoroalkyl group to the surface of cured film.For 1%(mass fraction) addition of F-OXE,the relative content of fluorine greatly increased from 0.70%(mass fraction) in the interior of the cured film to 36.73°%(mass fraction) at the surface of the cured film,whereas those of carbon and oxygen decreased from 73.29% to 40.96% and from 26.00% to22.30%,respectively.

  2. Electrospun TiO₂ nanofelt surface-decorated with Ag nanoparticles as sensitive and UV-cleanable substrate for surface enhanced Raman scattering.

    Science.gov (United States)

    Zhao, Yong; Sun, Lei; Xi, Min; Feng, Quan; Jiang, Chaoyang; Fong, Hao

    2014-04-23

    In this study, the free-standing electrospun nanofibrous mat (i.e., nanofelt) consisting of anatase-phase TiO2 nanofibers with diameters of ∼200 nm was prepared, and the nanofelt was subsequently surface-decorated with Ag nanoparticles via an electroless plating method. The sensitivity toward surface enhanced Raman scattering (SERS) and UV-cleanable property of electrospun TiO2/Ag nanofelt were then investigated. In the SERS tests, the target analyte (i.e., 4-mercaptobenzoic acid, Rhodamine 6G, and 4-aminothiophenol) was first adsorbed onto the TiO2/Ag nanofelt as the probe analyte; this was followed by the measurements of Raman intensity and SERS maps. Thereafter, the nanofelt adsorbed with target analyte was cleaned and regenerated/recovered upon UV irradiation in O2-saturated water, and the removal of target analyte was attributed to photodegradation property of anatase-phase TiO2. This study suggested that the electrospun TiO2/Ag nanofelt would be promising as SERS-active substrate with UV-cleanable property for cost-effective and reproducible SERS applications.

  3. Surface Plasmon-Assisted Excitation of Atomic Visible Light Spectral Lines in the Impact of Highly Charged Ions 126Xeq+ on Solid Surfaces

    Institute of Scientific and Technical Information of China (English)

    张小安; 赵永涛; 李福利; 杨治虎; 肖国青; 詹文龙

    2003-01-01

    We measured the visible light spectral lines of sputtering atoms from solid surfaces of Al, Ti, Ni, Ta and Au which are impacted by 150keV126Xeq+ (6≤q≤30). It is found that intensities of the light spectral lines are greatly and suddenly enhanced when the charge state of the ion is raised up to a critical value. If assuming that potential energy released from the incidention due to capturing one electron is enough to excite a surface plasmon, we can estimate the critical charge states and obtain the results very well consistent with the measurements for the above-mentioned target materials. This means that a surface plasmon induced by one electron capture can enhance the excitation of atomic visible light spectral lines in the impact of a highly charged ion on a solid surface.

  4. Ecological responses to UV radiation: interactions between the biological effects of UV on plants and on associated organisms.

    Science.gov (United States)

    Paul, Nigel D; Moore, Jason P; McPherson, Martin; Lambourne, Cathryn; Croft, Patricia; Heaton, Joanna C; Wargent, Jason J

    2012-08-01

    Solar ultraviolet (UV)-B radiation (280-315 nm) has a wide range of effects on terrestrial ecosystems, yet our understanding of how UV-B influences the complex interactions of plants with pest, pathogen and related microorganisms remains limited. Here, we report the results of a series of experiments in Lactuca sativa which aimed to characterize not only key plant responses to UV radiation in a field environment but also consequential effects for plant interactions with a sap-feeding insect, two model plant pathogens and phylloplane microorganism populations. Three spectrally modifying filters with contrasting UV transmissions were used to filter ambient sunlight, and when compared with our UV-inclusive filter, L. sativa plants grown in a zero UV-B environment showed significantly increased shoot fresh weight, reduced foliar pigment concentrations and suppressed population growth of green peach aphid (Myzus persicae). Plants grown under a filter which allowed partial transmission of UV-A radiation and negligible UV-B transmission showed increased density of leaf surface phylloplane microbes compared with the UV-inclusive treatment. Effects of UV treatment on the severity of two plant pathogens, Bremia lactucae and Botrytis cinerea, were complex as both the UV-inclusive and zero UV-B filters reduced the severity of pathogen persistence. These results are discussed with reference to known spectral responses of plants, insects and microorganisms, and contrasted with established fundamental responses of plants and other organisms to solar UV radiation, with particular emphasis on the need for future integration between different experimental approaches when investigating the effects of solar UV radiation.

  5. Superhydrophilic surface modification of fabric via coating with nano-TiO{sub 2} by UV and alkaline treatment

    Energy Technology Data Exchange (ETDEWEB)

    Li, Mingyu [College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Deng, Tingting [College of Textile and Garment, Southwest University, Chongqing 400715 (China); Liu, Shuxian [College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Zhang, Fengxiu, E-mail: zhangfx656472@sina.com.cn [College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Zhang, Guangxian, E-mail: zgx656472@sina.com.cn [College of Textile and Garment, Southwest University, Chongqing 400715 (China)

    2014-04-01

    Graphical abstract: - Highlights: • We reported a rapid, environmentally friendly, and highly efficient method for PET fabric surface modification. • The modified PET fabric became superhydrophilic and the water contact angles were decreased to 0° via coating with nano-TiO{sub 2} by UV and alkaline treatment. • The excellent mechanical and physical properties of modified PET fabric were retained. - Abstract: Increasing the hydrophilicity of poly(ethylene terephthalate) (PET) fabric has been an ongoing research goal. In this study, a rapid, environmentally friendly, and highly efficient method for modifying the surface of PET fabric is presented. In a solution of 30 g/L nano-TiO{sub 2}, 50 g/L H{sub 2}O{sub 2}, and 30 g/L NaOH, PET fabric was modified to become superhydrophilic by ultraviolet (UV) irradiation (1000 W) for only 30–40 min. The water contact angle of the modified PET fabric was decreased to 0°, and the water absorption rate of the modified PET fabric was increased from 85% to 104%. The capillary rise height increased from 0.2 cm to 6.2 cm, and the spraying rating decreased from 4 to 1. The crease recovery angles of modified PET fabrics were reduced by only 1.2–8.8%. The mechanical and physical properties of the modified PET fabric remained good. Compared to the surface of unmodified PET fabric, scanning electron microscopy showed that the surface of the modified PET fiber was rough and covered by a layer of other materials. Fourier transform infrared spectroscopy showed the materials on the surface of modified PET fibers likely included -COOH and -OH groups. X-ray diffraction demonstrated the formation of crystalline material. Finally, differential scanning calorimetry thermograms showed that the modification process slightly improved the thermostability of PET fibers.

  6. Individual IOL Surface Topography Analysis by the WaveMaster Reflex UV

    Directory of Open Access Journals (Sweden)

    Marc Kannengießer

    2013-01-01

    Full Text Available Purpose. In order to establish inspection routines for individual intraocular lenses (IOLs, their surfaces have to be measured separately. Currently available measurement devices lack this functionality. The purpose of this study is to evaluate a new topography measurement device based on wavefront analysis for measuring individual regular and freeform IOL surfaces, the “WaveMaster Reflex UV” (Trioptics, Wedel, Germany. Methods. Measurements were performed on IOLs with increasingly complex surface geometries: spherical surfaces, surfaces modelled by higher-order Zernike terms, and freeform surfaces from biometrical patient data. Two independent parameters were measured: the sample’s radius of curvature (ROC and its residual (difference of sample topography and its best-fit sphere. We used a quantitative analysis method by calculating the residuals’ root-mean-square (RMS and peak-to-Valley (P2V values. Results. The sample’s best-fit ROC differences increased with the sample’s complexity. The sample’s differences of RMS values were 80 nm for spherical surfaces, 97 nm for higher-order samples, and 21 nm for freeform surfaces. Graphical representations of both measurement and design topographies were recorded and compared. Conclusion. The measurements of spherical surfaces expectedly resulted in better values than those of freeform surfaces. Overall, the wavefront analysing method proves to be an effective method for evaluating individual IOL surfaces.

  7. The molecular basis for UV vision in birds: spectral characteristics, cDNA sequence and retinal localization of the UV-sensitive visual pigment of the budgerigar (Melopsittacus undulatus)

    National Research Council Canada - National Science Library

    Wilkie, S E; Vissers, P M; Das, D; Degrip, W J; Bowmaker, J K; Hunt, D M

    1998-01-01

    .... The existence of a fourth pigment (UV) is the major difference between the trichromacy of humans and the tetrachromacy of such birds, and recent studies have shown that it may play a determining role in such diverse aspects of behaviour...

  8. Impacts of coal dust from an active mine on the spectral reflectance of Arctic surface snow in Svalbard, Norway

    Science.gov (United States)

    Khan, Alia L.; Dierssen, Heidi; Schwarz, Joshua P.; Schmitt, Carl; Chlus, Adam; Hermanson, Mark; Painter, Thomas H.; McKnight, Diane M.

    2017-02-01

    Light-absorbing particles (LAPs) in snow such as dust and black carbon influence the radiative forcing at the Earth's surface, which has major implications for global climate models. LAPs also significantly influence the melting of glaciers, sea ice, and seasonal snow. Here we present an in situ study of surface snow near an active coal mine in the Norwegian Arctic. We couple measurements of spectral hemispherical directional reflectance factor (HDRF) with measurements of LAPs characterized in two ways, as refractory black carbon using a Single Particle Soot Photometer and the total light absorption of LAPs measured with the Light Absorption Heating Method. The Snow Ice and Aerosol Radiation model was constrained by LAP measurements. Results were compared to observed spectral albedo measurements. Modeled and observed albedos were similar at the cleaner and more remote sites. However, the modeled spectral albedos do not fully account for the low spectral albedo measured next to the mine. LAP measurements also showed a large variation in particle sizes (tenths to tens of microns) related to transport distance of the particles from the mine. Here we find that LAPs from coal dust reduce the spectral HDRF by up to 84% next to the mine and 55% 0.5 km downwind of the mine. The coupling of extreme LAP observations (1 ng g-1 to 4863 ng g-1) with HDRF measurements from 350 to 2500 nm has facilitated the development of spectral band pairs, which could be used in the future to remotely assess LAPs in Arctic snow.

  9. Comparisons Between Model Predictions and Spectral Measurements of Charged and Neutral Particles on the Martian Surface

    Science.gov (United States)

    Kim, Myung-Hee Y.; Cucinotta, Francis A.; Zeitlin, Cary; Hassler, Donald M.; Ehresmann, Bent; Rafkin, Scot C. R.; Wimmer-Schweingruber, Robert F.; Boettcher, Stephan; Boehm, Eckart; Guo, Jingnan; hide

    2014-01-01

    Detailed measurements of the energetic particle radiation environment on the surface of Mars have been made by the Radiation Assessment Detector (RAD) on the Curiosity rover since August 2012. RAD is a particle detector that measures the energy spectrum of charged particles (10 to approx. 200 MeV/u) and high energy neutrons (approx 8 to 200 MeV). The data obtained on the surface of Mars for 300 sols are compared to the simulation results using the Badhwar-O'Neill galactic cosmic ray (GCR) environment model and the high-charge and energy transport (HZETRN) code. For the nuclear interactions of primary GCR through Mars atmosphere and Curiosity rover, the quantum multiple scattering theory of nuclear fragmentation (QMSFRG) is used. For describing the daily column depth of atmosphere, daily atmospheric pressure measurements at Gale Crater by the MSL Rover Environmental Monitoring Station (REMS) are implemented into transport calculations. Particle flux at RAD after traversing varying depths of atmosphere depends on the slant angles, and the model accounts for shielding of the RAD "E" dosimetry detector by the rest of the instrument. Detailed comparisons between model predictions and spectral data of various particle types provide the validation of radiation transport models, and suggest that future radiation environments on Mars can be predicted accurately. These contributions lend support to the understanding of radiation health risks to astronauts for the planning of various mission scenarios

  10. The molecular basis for UV vision in birds: spectral characteristics, cDNA sequence and retinal localization of the UV-sensitive visual pigment of the budgerigar (Melopsittacus undulatus).

    Science.gov (United States)

    Wilkie, S E; Vissers, P M; Das, D; Degrip, W J; Bowmaker, J K; Hunt, D M

    1998-02-15

    Microspectrophotometric (msp) studies have shown that the colour-vision system of many bird species is based on four pigments with absorption peaks in the red, green, blue and UV regions of the spectrum. The existence of a fourth pigment (UV) is the major difference between the trichromacy of humans and the tetrachromacy of such birds, and recent studies have shown that it may play a determining role in such diverse aspects of behaviour as mate selection and detection of food. Avian visual pigments are composed of an opsin protein covalently bound via a Schiff-base linkage to the chromophore 11-cis-retinal. Here we report the cDNA sequence of a UV opsin isolated from an avian species, Melopsittacus undulatus (budgerigar or small parakeet). This sequence has been expressed using the recombinant baculovirus system; the pigment generated from the expressed protein on addition of 11-cis-retinal yielded an absorption spectrum typical of a UV photopigment, with lambdamax 365+/-3 nm. This is the first UV opsin from an avian species to be sequenced and expressed in a heterologous system. In situ hybridization of this sequence to budgerigar retinas selectively labelled a sub-set of UV cones, representing approx. 9% of the total cone population, that are distributed in a semi-regular pattern across the entire retina.

  11. Spectral data of specular reflectance, narrow-angle transmittance and angle-resolved surface scattering of materials for solar concentrators.

    Science.gov (United States)

    Good, Philipp; Cooper, Thomas; Querci, Marco; Wiik, Nicolay; Ambrosetti, Gianluca; Steinfeld, Aldo

    2016-03-01

    The spectral specular reflectance of conventional and novel reflective materials for solar concentrators is measured with an acceptance angle of 17.5 mrad over the wavelength range 300-2500 nm at incidence angles 15-60° using a spectroscopic goniometry system. The same experimental setup is used to determine the spectral narrow-angle transmittance of semi-transparent materials for solar collector covers at incidence angles 0-60°. In addition, the angle-resolved surface scattering of reflective materials is recorded by an area-scan CCD detector over the spectral range 350-1050 nm. A comprehensive summary, discussion, and interpretation of the results are included in the associated research article "Spectral reflectance, transmittance, and angular scattering of materials for solar concentrators" in Solar Energy Materials and Solar Cells.

  12. Spectral data of specular reflectance, narrow-angle transmittance and angle-resolved surface scattering of materials for solar concentrators

    Directory of Open Access Journals (Sweden)

    Philipp Good

    2016-03-01

    Full Text Available The spectral specular reflectance of conventional and novel reflective materials for solar concentrators is measured with an acceptance angle of 17.5 mrad over the wavelength range 300−2500 nm at incidence angles 15–60° using a spectroscopic goniometry system. The same experimental setup is used to determine the spectral narrow-angle transmittance of semi-transparent materials for solar collector covers at incidence angles 0–60°. In addition, the angle-resolved surface scattering of reflective materials is recorded by an area-scan CCD detector over the spectral range 350–1050 nm. A comprehensive summary, discussion, and interpretation of the results are included in the associated research article “Spectral reflectance, transmittance, and angular scattering of materials for solar concentrators” in Solar Energy Materials and Solar Cells.

  13. Laguerre-Gauss beam generation in IR and UV by subwavelength surface-relief gratings

    DEFF Research Database (Denmark)

    Vertchenko, Larissa; Shkondin, Evgeniy; Malureanu, Radu

    2017-01-01

    layerdepositions and dry etch techniques. We exploit the phenomenon of formbirefringence to give rise to the spin-to-orbital angular momentum conversion.We demonstrate that these plates can generate beams with high quality for theUV and IR range, allowing them to interact with high power laser sources orinside......The angular momentum of light can be described by the states of spin angularmomentum, associated with polarization, and orbital angular momentum, relatedto the helical structure of the wave front. Laguerre-Gaussian beams carryorbital angular momentum and their generation can be done by using...... an opticaldevice known as q-plate. However, due to the usage of liquid crystals, thesecomponents may be restricted to operate in specific wavelengths and low powersources. Here we present the fabrication and characterization of q-plates madewithout liquid crystals, using processes of e-beam lithography, atomic...

  14. Laguerre-Gauss beam generation in IR and UV by subwavelength surface-relief gratings

    CERN Document Server

    Vertchenko, Larissa; Malureanu, Radu; Monken, Carlos H

    2016-01-01

    The angular momentum of light can be described by the states of spin angular momentum, associated with polarization, and orbital angular momentum, related to the helical structure of the wave front. Laguerre-Gaussian beams carry orbital angular momentum and their generation can be done by using an optical device known as q-plate. However, due to the usage of liquid crystals, these components may be restricted to operate in specific wavelengths and low power sources. Here we present the fabrication and characterization of q-plates made without liquid crystals, using processes of e-beam lithography, atomic layer depositions and dry etch techniques. We exploit the phenomenon of form birefringence to give rise to the spin-to-orbital angular momentum conversion. We demonstrate that these plates can generate beams with high quality for the UV and IR range, allowing them to interact with high power laser sources or inside laser cavities.

  15. Multi-Spectral Satellite Imagery and Land Surface Modeling Supporting Dust Detection and Forecasting

    Science.gov (United States)

    Molthan, A.; Case, J.; Zavodsky, B.; Naeger, A. R.; LaFontaine, F.; Smith, M. R.

    2014-12-01

    Current and future multi-spectral satellite sensors provide numerous means and methods for identifying hazards associated with polluting aerosols and dust. For over a decade, the NASA Short-term Prediction Research and Transition (SPoRT) Center at Marshall Space Flight Center in Huntsville has focused on developing new applications from near real-time data sources in support of the operational weather forecasting community. The SPoRT Center achieves these goals by matching appropriate analysis tools, modeling outputs, and other products to forecast challenges, along with appropriate training and end-user feedback to ensure a successful transition. As a spinoff of these capabilities, the SPoRT Center has recently focused on developing collaborations to address challenges with the public health community, specifically focused on the identification of hazards associated with dust and pollution aerosols. Using multispectral satellite data from the SEVIRI instrument on the Meteosat series, the SPoRT team has leveraged EUMETSAT techniques for identifying dust through false color (RGB) composites, which have been used by the National Hurricane Center and other meteorological centers to identify, monitor, and predict the movement of dust aloft. Similar products have also been developed from the MODIS and VIIRS instruments onboard the Terra and Aqua, and Suomi-NPP satellites, respectively, and transitioned for operational forecasting use by offices within NOAA's National Weather Service. In addition, the SPoRT Center incorporates satellite-derived vegetation information and land surface modeling to create high-resolution analyses of soil moisture and other land surface conditions relevant to the lofting of wind-blown dust and identification of other, possible public-health vectors. Examples of land surface modeling and relevant predictions are shown in the context of operational decision making by forecast centers with potential future applications to public health arenas.

  16. Laser- and UV-assisted modification of polystyrene surfaces for control of protein adsorption and cell adhesion

    Science.gov (United States)

    Pfleging, Wilhelm; Torge, Maika; Bruns, Michael; Trouillet, Vanessa; Welle, Alexander; Wilson, Sandra

    2009-03-01

    An appropriate choice of laser and process parameters enables new approaches for the fabrication of polymeric lab-on-chip devices with integrated functionalities. We will present our current research results in laser-assisted modification of polystyrene (PS) with respect to the fabrication of polymer devices for cell culture applications. For this purpose laser micro-patterning of PS and subsequent surface functionalization was investigated as function of laser and process parameters. A high power ArF-excimer laser radiation source with a pulse length of 19 ns as well as a high repetition ArF-excimer laser source with a pulse length of 5 ns were used in order to study the influence of laser pulse length on laser-induced surface oxidation. The change in surface chemistry was characterized by X-ray photoelectron spectroscopy and contact angle measurements. The difference between laser-assisted modification versus UV-lamp assisted modification was investigated. A photolytic activation of specific areas of the polymer surface and subsequent oxidization in oxygen or ambient air leads to a chemically modified polymer surface bearing carboxylic acid groups well-suited for controlled competitive protein adsorption or protein immobilization. Finally, distinct areas for cell growth and adhesion are obtained.

  17. Model to explain the effects of halide ions on the increase in surface enhanced Raman spectral intensity over time

    Science.gov (United States)

    Cole, Michael A.

    Understanding the mechanisms responsible for the large increase in spectral intensity when molecules are adsorbed to nanoparticle surfaces such as occurs during surface enhanced Raman (SER) spectroscopy will allow scientists to probe ever smaller scales, even allowing single molecule detection. One particular scenario that increased the SER scattering efficiency was the addition of halide ions to Rhodamine 6G (R6G)-ethanol solution. This thesis presents a theoretical model explaining the effects of halide ions on the SER spectral intensity of the Rhodamine 6G (R6G) molecule when co-adsorbed to a silver nanoparticle surface. Glaspell et al. 2005, found a linear correlation between the increase in spectral intensities of selected vibrational normal modes of R6G over time and the polarizabilities of co-adsorbed halide ions. When the R6G molecule co-adsorbs to the silver nanoparticle surface with the halide ions, the molecule is exposed to three external electric fields that add vectorially, creating a total external electric field. Modelling the fields from the halide ions and the silver nanoparticles as electric dipole fields introduces the polarizability of the halide ion linearly into the Raman spectral intensity equation. This model also shows that there is a necessary interaction between the halide ions and the silver nanoparticle surface in order to see the effects as described by Glaspell et al. Furthermore, we will present experimental results that show that there is a necessary interaction between the halide ions and the nanoparticle surface. Without this interaction there was no increase in the SER spectral intensity of R6G or pyridine molecules in solution with the halide ions but without the silver nanoparticles.

  18. Microscopie interférentielle X-UV : un outil pour l'étude des endommagements des surfaces optiques

    Science.gov (United States)

    Jamelot, G.; Ros, D.; Cassou, K.; Kazamias, S.; Klisnick, A.; Kozlová, M.; Mocek, T.; Homer, P.; Polan, J.; Stupka, M.

    2006-12-01

    Nous présentons des résultats récents concernant des premières investigations de microscopie interférentielle par laser X-UV d'endommagement optique. Le laser X-UV utilisé est un laser collisionnel en régime quasi-stationnaire émettant à 21.2 nm, développé au Prague Asterix Laser System (PALS, Prague, République Tchèque). Des échantillons de silice fondue de haute qualité, avec ou sans rayure, étaient irradiées en face avant par un laser bleu, correspondant au 3selectfontfontsize{7{9}{textrm{ème}}} harmonique du laser à iode du PALS (1.315 μ m), servant également à réaliser le laser X-UV à 21.2 nm. Celui-ci était utilisé, 5 ns après l'irradiation pour réaliser une imagerie microscopique et interférentielle de la face arrière de l'échantillon. Les résultats font apparaître des déformations locales transitoires. Des premières analyses mettent en évidence une probable variation de la rugosité de la surface. Cette démonstration expérimentale encourageante ouvre la voie à de futures investigations, notamment sur notre prochaine installation laser : LASERIX.

  19. Polymer surface modification using UV treatment for attachment of natamycin and the potential applications for conventional food cling wrap (LDPE)

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Joongmin, E-mail: shinj@uwstout.edu [Engineering and Technology, University of Wisconsin-Stout, Menomonie, WI, 54751 (United States); Liu, Xiaojing [Mechanical and Electronic Engineering, Wuhan University of Technology, Wuhan (China); Chikthimmah, Naveen [Food Science and Technology, University of Wisconsin-Stout, Menomonie, WI, 54751 (United States); Lee, Youn Suk [Department of Packaging, Yonsei University, Gangwon 220-710 (Korea, Republic of)

    2016-11-15

    Highlights: • The study suggests an optimized method for UV-induced antimicrobial agents grafting on LDPE. • The study evaluated the effective of various solvents for acrylic acid and natamycin grafting on LDPE. • The study investigated chemical and mechanical property changes by various times of UV light treatments. • Natamycin grafted film demonstrated antifungal function against mold and yeast. - Abstract: The purpose of this study was to develop an active non-migratory antifungal Low Density Polyethylene (LDPE) polymer for use in food packaged applications. The functional acrylic acid monomer was grafted on the LDPE film surface by photo-initiated graft polymerization using Ultra Violet light irradiation (from 0 to 5 min). Natamycin, an antifungal agent, was applied to the treated film to bind with the pendent functional groups and were evaluated its performance against mold and yeast. The grafted amounts were determined by gravimetric measurement and dye absorbance. Attenuated Total Reflectance/Fourier Transfer Infrared Spectroscopy, scanning electron microscopy, mechanical strength test was used to characterize film properties. The antifungal efficacy of the film was evaluated with Saccharomyces cerevisiae and Penicillium chrysogenum on growth media and fresh cut cantaloupe. The amounts of the grafted group were increased with the longer ultraviolet exposure time. The amount of the grafted natamycin on the treated film was up to 49.87 μg/cm{sup 2}, and the film inhibited mycelium formation of P. chrysogenum spores by over 60%. Due to the thickness of the film (less than 12.25 μm), long time UV exposure decrease the film’s mechanical strength. The application of such non-migratory active packaging film represents a promising approach to maintaining food quality with reduced additive.

  20. Integrating seasonal optical and thermal infrared spectra to characterize urban impervious surfaces with extreme spectral complexity: a Shanghai case study

    Science.gov (United States)

    Wang, Wei; Yao, Xinfeng; Ji, Minhe

    2016-01-01

    Despite recent rapid advancement in remote sensing technology, accurate mapping of the urban landscape in China still faces a great challenge due to unusually high spectral complexity in many big cities. Much of this complication comes from severe spectral confusion of impervious surfaces with polluted water bodies and bright bare soils. This paper proposes a two-step land cover decomposition method, which combines optical and thermal spectra from different seasons to cope with the issue of urban spectral complexity. First, a linear spectral mixture analysis was employed to generate fraction images for three preliminary endmembers (high albedo, low albedo, and vegetation). Seasonal change analysis on land surface temperature induced from thermal infrared spectra and coarse component fractions obtained from the first step was then used to reduce the confusion between impervious surfaces and nonimpervious materials. This method was tested with two-date Landsat multispectral data in Shanghai, one of China's megacities. The results showed that the method was capable of consistently estimating impervious surfaces in highly complex urban environments with an accuracy of R2 greater than 0.70 and both root mean square error and mean average error less than 0.20 for all test sites. This strategy seemed very promising for landscape mapping of complex urban areas.

  1. Covalently attached organic monolayers on SiC and SixN4 surfaces: Formation using UV light at room temperature

    NARCIS (Netherlands)

    Rosso, M.; Giesbers, M.; Arafat, A.; Schroën, C.G.P.H.; Zuilhof, H.

    2009-01-01

    We describe the formation of alkyl monolayers on silicon carbide (SiC) and silicon-rich silicon nitride (SixN4) surfaces, using UV irradiation in the presence of alkenes. Both the surface preparation and the monolayer attachment were carried out under ambient conditions. The stable coatings obtained

  2. UV Direct Laser Interference Patterning of polyurethane substrates as tool for tuning its surface wettability

    Energy Technology Data Exchange (ETDEWEB)

    Estevam-Alves, Regina [Instituto de Física de São Carlos, Universidade de São Paulo, 13560-970 São Carlos (Brazil); Günther, Denise; Dani, Sophie; Eckhardt, Sebastian; Roch, Teja [Fraunhofer Institute for Material and Beam Technology IWS, Winterbergstr. 28, Dresden 01277 (Germany); Chair for Large Area Laser Based Surface Micro/Nano-Structuring, Institute for Manufacturing Technology, Technische Universität Dresden, George-Bähr-Str. 3c, 01069 Dresden (Germany); Mendonca, Cleber R., E-mail: crmendon@ifsc.usp.br [Instituto de Física de São Carlos, Universidade de São Paulo, 13560-970 São Carlos (Brazil); Cestari, Ismar N. [Heart Institute (InCOr), University of São Paulo Medical School, São Paulo 05403-000 (Brazil); Lasagni, Andrés F., E-mail: andres_fabian.lasagni@tu-dresden.de [Fraunhofer Institute for Material and Beam Technology IWS, Winterbergstr. 28, Dresden 01277 (Germany); Chair for Large Area Laser Based Surface Micro/Nano-Structuring, Institute for Manufacturing Technology, Technische Universität Dresden, George-Bähr-Str. 3c, 01069 Dresden (Germany)

    2016-06-30

    Highlights: • First reported experiments on Direct Laser Interference Patterning of polyurethane. • First reported sub-micrometer structures (feature size ∼250 nm) fabricated in polyurethane materials using laser processing technologies. • Anisotropic wetting behavior of structured surfaces and possibility to tune the contact angle as function of surface structure parameters. - Abstract: Direct Laser Interference Patterning (DLIP) is a versatile tool for the fabrication of micro and sub-micropatterns on different materials. In this work, DLIP was used to produce periodic surface structures on polyurethane (PU) substrates with spatial periods ranging from 0.5 to 5.0 μm. The influence of the laser energy density on the quality and topographical characteristics of the produced micropatterns was investigated. To characterize the surface topography of the produced structures, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Confocal Microscopy (CFM) were utilized. It was found that high quality and defect free periodic line-like patterns with spatial periods down to 500 nm could be fabricated, with structure depths between 0.88 up to 1.25 μm for spatial periods larger than 2.0 μm and up to 270 nm for spatial periods between 500 nm and 1.0 μm. Measurements of the contact angle of water on the treated surface allowed to identify an anisotropic wetting behavior depending mainly on the spatial period and filling factor of the structured surfaces.

  3. Compositional and surface characterization of HULIS by UV-Vis, FTIR, NMR and XPS: Wintertime study in Northern India

    Science.gov (United States)

    Kumar, Varun; Goel, Anubha; Rajput, Prashant

    2017-09-01

    This study (first attempt) characterizes HULIS (Humic Like Substances) in wintertime aerosols (n = 12 during day and nighttime each) from Indo-Gangetic Plain (IGP, at Kanpur) by using various state-of-the art techniques such as UV-VIS, FTIR, 1H NMR and XPS. Based on UV-Vis analysis the absorption coefficient at 365 nm (babs-365) of HULIS was found to average at 13.6 and 28.8 Mm-1 during day and nighttime, respectively. Relatively high babs-365 of HULIS during the nighttime is attributed to influence of fog-processing. However, the power fit of UV-Vis spectrum provided near similar AAE (absorption Angstrom exponent) value of HULIS centering at 4.9 ± 1.4 and 5.1 ± 1.3 during daytime and nighttime, respectively. FTIR spectra and its double derivative revealed the presence of various functional groups viz. alcohols, ketones aldehydes, carboxylic acids as well as unsaturated and saturated carbon bonds. 1H NMR spectroscopy was applied to quantify relative percentage of various types of hydrogen atoms contained in HULIS, whereas XPS technique provided information on surface composition and oxidation states of various elements present. A significantly high abundance of H‒C‒O group has been observed in HULIS (based on 1H NMR); 41.4± 2.7% and 30.9± 2.4% in day and nighttime, respectively. However, aromatic protons (Ar-H) were higher in nighttime samples (19.3± 1.8%) as compared to that in daytime samples (7.5 ± 1.9). XPS studies revealed presence of various species on the surface of HULIS samples. Carbon existed in 7 different chemical states while total nitrogen and sulfur exhibited 3 and 2 different oxidation states (respectively) on the surface of HULIS. This study reports structural information and absorption properties of HULIS which has implications to their role as cloud condensation nuclei and atmospheric direct radiative forcing.

  4. Improved adhesion of diamond coating on cobalt-cemented tungsten carbide hardmetal by using pulsed-UV-laser substrate surface pretreatment

    Science.gov (United States)

    Tiejun, Li; Qihong, Lou; Jingxing, Dong; Yunrong, Wei; Jun, Zhou; Jingru, Liu; Zhiming, Zhang; Fanghong, Sun

    2002-06-01

    Pulsed-UV-laser surface ablation has been applied in substrate pretreatment in order to obtain good adhesion of diamond coating grown on cobalt-cemented tungsten carbide hardmetal. The dependence of diamond coating's adhesion on different shots of pulsed-UV-laser substrate pretreatment has been studied experimentally. The results were compared with diamond coating deposited by using traditional acid-etching substrate pretreatment. It was shown that adhesion of diamond coating grown on tungsten carbide hardmetal has been greatly improved by using pulsed-UV-laser substrate pretreatment. The corresponding laser pretreatment condition for the optimal adhesion of diamond coatings was finally obtained. It has been demonstrated that pulsed-UV-laser substrate pretreatment should be a feasible and effective method for improving adhesion of diamond coating on cobalt-cemented tungsten carbide hardmetal. It is the characteristic surface morphology produced by pulsed-UV-laser surface ablation that subsequently results in this improved adhesion of diamond coating grown on tungsten carbide hardmetal. The number of laser shots being used in substrate pretreatment has a great influence to the adhesion of diamond coating deposited on tungsten carbide hardmetal. One should always apply proper number of laser shots in pulsed-UV-laser substrate pretreatment when seeking for the optimal adhesion of diamond coating on tungsten carbide hardmetal. In this work, the corresponding number of laser shots for the optimal adhesion of diamond coating has found to be 300 laser shots.

  5. Gas-phase Reactive Oxygen and Nitrogen Species in Air Surface Dielectric Barrier Discharges by FTIR and UV spectroscopy

    Science.gov (United States)

    Chang, Hung-Wen; Sakiyama, Yukinori; Hsu, Cheng-Che; Graves, David B.

    2012-10-01

    Atmospheric pressure plasmas are considered promising for biomedical treatment purpose due to the production of reactive oxygen species and reactive nitrogen species during the discharge. In this study, a surface micro-discharge system which operates at 10 kHz, 0.01 -- 1 W/cm^2 in ambient air is used. FTIR and UV-absorbance are used to investigate the time-average gas phase composition and time-resolved ozone concentration, respectively. The results showed that the gas composition is greatly influenced by the power consumption in plasmas. At 0.3 W/cm^2, the gas phase is dominant by NOx species and nearly no ozone is observed while at 0.05 W/cm^2 the amount of NOx is less and the ozone is dominant. Also, time-resolved ozone measurement by means of UV (254 nm) absorbance shows that ozone concentration reaches higher than 1000 ppm in the first tens of seconds and quenched within 1 minutes at high power condition. However, at low power condition no obvious quench of ozone is observed and the ozone concentration attains a steady state in response to the equilibrium of ozone generation and diffusion loss

  6. One-Pot UV-Triggered o-Nitrobenzyl Dopamine Polymerization and Coating for Surface Antibacterial Application.

    Science.gov (United States)

    Shi, Liya; Santhanakrishnan, Sridhar; Cheah, Yong Shung; Li, Min; Chai, Christina Li Lin; Neoh, Koon Gee

    2016-12-07

    Dopamine (DA) protected by an o-nitrobenzyl functionality on its phenolic group was synthesized as a photolabile catecholamine derivative. This compound, o-nitrobenzyl dopamine (NBDA), was more stable than DA in basic solution at pH 8.5 and will not self-polymerize when protected from light. UV irradiation of a methanolic solution of NBDA at 365 nm for 40 min induced ca. 85% deprotection. Taking advantage of the stability of NBDA, a one-pot spray coating technique for modifying surfaces with polydopamine (PDA) was developed. Using ethylene glycol with Tris buffer (pH 8.5) as the solvent for this technique, stainless steel substrates can be coated with a robust PDA layer. Silver was deposited on the PDA-coated surface after treatment with silver nitrate solution, and >80% of the deposited silver remained on the surface after 1 week immersion in water. The NBDA-Ag surface was highly effective in inhibiting Staphylococcus aureus (S. aureus) biofilm formation.

  7. Herschel / HIFI spectral line survey of the Orion Bar - Temperature and density differentiation near the PDR surface

    CERN Document Server

    Nagy, Z; Ossenkopf-Okada, V; van der Tak, F F S; Bergin, E A; Gerin, M; Joblin, C; Roellig, M; Simon, R; Stutzki, J

    2016-01-01

    Photon Dominated Regions (PDRs) are interfaces between the mainly ionized and mainly molecular material around young massive stars. Analysis of the physical and chemical structure of such regions traces the impact of far-ultraviolet radiation of young massive stars on their environment. We present results on the physical and chemical structure of the prototypical high UV-illumination edge-on Orion Bar PDR from an unbiased spectral line survey with a wide spectral coverage. A spectral scan from 480-1250 GHz and 1410-1910 GHz at 1.1 MHz resolution was obtained by the HIFI instrument onboard the Herschel Space Observatory. For molecules with multiple transitions we used rotational diagrams to obtain excitation temperatures and column densities. For species with a single detected transition we used an optically thin LTE approximation. In case of species with available collisional rates, we also performed a non-LTE analysis to obtain kinetic temperatures, H2 volume densities, and column densities. About 120 lines ...

  8. Exposure machine lfy eye type UV-LED surface light source of collimated light system%复眼式UV-LED面光源的曝光机平行光系统

    Institute of Scientific and Technical Information of China (English)

    闵秀红

    2014-01-01

    印制电路板生产设备紫外线曝光机的光源系统,其能耗大、使用维护成本高、含汞等缺陷,在倡导节能环保的当今,业界一直致力于改进。UV-LED面光源作为新一代绿色环保紫外线光源,为印制电路板曝光领域带来革命性的变化。文章通过分析传统平行光紫外曝光机光学系统特点,设计了一种平行光紫外线曝光机适用的UV-LED面光源系统,UV-LED灯珠光功率利用率大幅提高,光照均匀性优良,并且不改变曝光机结构的情况下,可直接安装使用。实验表明,采用了复眼式阵列光学透镜结构设计的UV-LED面光源系统,完全可替代传统平行光紫外曝光机光源。%The light source system of ultraviolet exposure machine which is the PCB production equipment, has high energy consumption, high using and maintenance costs, mercury and other defects. To promote energy-saving environmental protection industry today, the industry has been working to improve. UV-LED surface light source as a new generation of green ultraviolet light source, brings the revolutionary change for the PCB exposure ifeld. In this paper, through the analysis of features of the traditional collimated light ultraviolet exposure machine, it designed a kind of UV-LED surface light source system for the collimated light ultraviolet exposure machine, a substantial increase in UV-LED light pearl power efifciency, illumination uniformity is good, and does not change the exposure machine structure, can be directly installed. Experiments show that, the UV-LED surface light source system using the optical lens structure of lfy's eye array can completely replace the traditional collimated l light ultraviolet exposure machine light source.

  9. UV and IR laser radiation's interaction with metal film and teflon surfaces

    Science.gov (United States)

    Fedenev, A. V.; Alekseev, S. B.; Goncharenko, I. M.; Koval', N. N.; Lipatov, E. I.; Orlovskii, V. M.; Shulepov, M. A.; Tarasenko, V. F.

    2003-04-01

    The interaction of Xe ([lambda] [similar] 1.73 [mu]m) and XeCl (0.308 [mu]m) laser radiation with surfaces of metal and TiN-ceramic coatings on glass and steel substrates has been studied. Correlation between parameters of surface erosion versus laser-specific energy was investigated. Monitoring of laser-induced erosion on smooth polished surfaces was performed using optical microscopy. The correlation has been revealed between characteristic zones of thin coatings damaged by irradiation and energy distribution over the laser beam cross section allowing evaluation of defects and adhesion of coatings. The interaction of pulsed periodical CO2 ([lambda] [similar] 10.6 [mu]m), and Xe ([lambda] [similar] 1.73 [mu]m) laser radiation with surfaces of teflon (polytetrafluoroethylene—PTFE) has been studied. Monitoring of erosion track on surfaces was performed through optical microscopy. It has been shown that at pulsed periodical CO2-radiation interaction with teflon the sputtering of polymer with formation of submicron-size particles occurs. Dependencies of particle sizes, form, and sputtering velocity on laser pulse duration and target temperature have been obtained.

  10. SO2 frost - UV-visible reflectivity and Io surface coverage

    Science.gov (United States)

    Nash, D. B.; Fanale, F. P.; Nelson, R. M.

    1980-01-01

    The reflectance spectrum in the range 0.24-0.85 microns of SO2 frost is measured in light of the discovery of SO2 gas in the atmosphere of Io and the possible discovery of the frost on its surface. Frost deposits up to 1.5 mm thick were grown in vacuum at 130 K and bi-directional reflectance spectra were obtained. Typical SO2 frost is found to exhibit very low reflectivity (2-5%) at 0.30 microns, rising steeply at 0.32 microns to attain a maximum reflectivity (75-80%) at 4.0 microns and uniformly high reflectivity throughout the visible and near infrared. Comparison with the full disk spectrum of Io reveals that no more than 20% of the surface can be covered with optically thick SO2 frost. Combinations of surface materials including SO2 frost which can produce the observed spectrum are indicated.

  11. SO2 frost - UV-visible reflectivity and Io surface coverage

    Science.gov (United States)

    Nash, D. B.; Fanale, F. P.; Nelson, R. M.

    1980-01-01

    The reflectance spectrum in the range 0.24-0.85 microns of SO2 frost is measured in light of the discovery of SO2 gas in the atmosphere of Io and the possible discovery of the frost on its surface. Frost deposits up to 1.5 mm thick were grown in vacuum at 130 K and bi-directional reflectance spectra were obtained. Typical SO2 frost is found to exhibit very low reflectivity (2-5%) at 0.30 microns, rising steeply at 0.32 microns to attain a maximum reflectivity (75-80%) at 4.0 microns and uniformly high reflectivity throughout the visible and near infrared. Comparison with the full disk spectrum of Io reveals that no more than 20% of the surface can be covered with optically thick SO2 frost. Combinations of surface materials including SO2 frost which can produce the observed spectrum are indicated.

  12. Escape of carbon element in surface ablation of cobalt cemented tungsten carbide with pulsed UV laser

    Science.gov (United States)

    Li, Tiejun; Lou, Qihong; Dong, Jingxing; Wei, Yunrong; Liu, Jingru

    2001-03-01

    Surface ablation of cobalt cemented tungsten carbide hardmetal has been carried out in this work using a 308 nm, 30 ns XeCl excimer laser. The surface phase transformation on different pulse number of laser shots has been investigated by means of XRD and microphotography as well as AES at laser fluence of 2.5 J/cm 2. The experimental results showed that the phase structure of irradiated area has partly transformed from original WC to β-WC 1- x, then to α-W 2C and CW 3, and finally to W crystal. It is suggested that the formation of non-stoichiometric tungsten carbide should result from the escaping of carbon element due to accumulated heating of surface by pulsed laser irradiation.

  13. Study of land surface temperature and spectral emissivity using multi-sensor satellite data

    Indian Academy of Sciences (India)

    P K Srivastava; T J Majumdar; Amit K Bhattacharya

    2010-02-01

    In this study, an attempt has been made to estimate land surface temperatures (LST) and spectral emissivities over a hard rock terrain using multi-sensor satellite data. The study area, of about 6000 km2, is a part of Singhbhum–Orissa craton situated in the eastern part of India. TIR data from ASTER, MODIS and Landsat ETM+ have been used in the present study. Telatemp Model AG-42D Portable Infrared Thermometer was used for ground measurements to validate the results derived from satellite (MODIS/ASTER) data. LSTs derived using Landsat ETM+ data of two different dates have been compared with the satellite data (ASTER and MODIS) of those two dates. Various techniques, viz., temperature and emissivity separation (TES) algorithm, gray body adjustment approach in TES algorithm, Split-Window algorithms and Single Channel algorithm along with NDVI based emissivity approach have been used. LSTs derived from bands 31 and 32 of MODIS data using Split-Window algorithms with higher viewing angle (50°) (LST1 and LST2) are found to have closer agreement with ground temperature measurements (ground LST) over waterbody, Dalma forest and Simlipal forest, than that derived from ASTER data (TES with AST 13). However, over agriculture land, there is some uncertainty and difference between the measured and the estimated LSTs for both validation dates for all the derived LSTs. LST obtained using Single Channel algorithm with NDVI based emissivity method in channel 13 of ASTER data has yielded closer agreement with ground measurements recorded over vegetation and mixed lands of low spectral contrast. LST results obtained with TIR band 6 of Landsat ETM+ using Single Channel algorithm show close agreement over Dalma forest, Simlipal forest and waterbody with LSTs obtained using MODIS and ASTER data for a different date. Comparison of LSTs shows good agreement with ground measurements in thermally homogeneous area. However, results in agriculture area with less homogeneity show

  14. Non-inferiority of pulsed xenon UV light versus bleach for reducing environmental Clostridium difficile contamination on high-touch surfaces in Clostridium difficile infection isolation rooms.

    Science.gov (United States)

    Ghantoji, Shashank S; Stibich, Mark; Stachowiak, Julie; Cantu, Sherry; Adachi, Javier A; Raad, Issam I; Chemaly, Roy F

    2015-02-01

    The standard for Clostridium difficile surface decontamination is bleach solution at a concentration of 10 % of sodium hypochlorite. Pulsed xenon UV light (PX-UV) is a means of quickly producing germicidal UV that has been shown to be effective in reducing environmental contamination by C. difficile spores. The purpose of this study was to investigate whether PX-UV was equivalent to bleach for decontamination of surfaces in C. difficile infection isolation rooms. High-touch surfaces in rooms previously occupied by C. difficile infected patients were sampled after discharge but before and after cleaning using either bleach or non-bleach cleaning followed by 15 min of PX-UV treatment. A total of 298 samples were collected by using a moistened wipe specifically designed for the removal of spores. Prior to disinfection, the mean contamination level was 2.39 c.f.u. for bleach rooms and 22.97 for UV rooms. After disinfection, the mean level of contamination for bleach was 0.71 c.f.u. (P = 0.1380), and 1.19 c.f.u. (P = 0.0017) for PX-UV disinfected rooms. The difference in final contamination levels between the two cleaning protocols was not significantly different (P = 0.9838). PX-UV disinfection appears to be at least equivalent to bleach in the ability to decrease environmental contamination with C. difficile spores. Larger studies are needed to validate this conclusion. © 2015 The Authors.

  15. Solar UV Irradiation-Induced Production of Greenhouse Gases from Plant Surfaces: From Leaf to Earth

    DEFF Research Database (Denmark)

    Mikkelsen, Teis Nørgaard; Bruhn, Dan; Ambus, Per

    2016-01-01

    -methane volatile organic compounds (NMVOC), NOx and N2O. This gas production, near or at the plant surface, is a new discovery and is normally not included in emission budgets (e.g. by the Intergovernmental Panel on Climate Change, IPCC) due to a lack of information with respect to validation and upscaling. For CH...

  16. Phase transformation during surface ablation of cobalt-cemented tungsten carbide with pulsed UV laser

    Energy Technology Data Exchange (ETDEWEB)

    Li, T. [Academia Sinica, Shanghai, SH (China). Shanghai Inst. of Optics and Fine Mechanics; Northwest Institute of Nuclear Technology, Xi' an (China); Lou, Q.; Dong, J.; Wei, Y. [Academia Sinica, Shanghai, SH (China). Shanghai Inst. of Optics and Fine Mechanics; Liu, J. [Northwest Institute of Nuclear Technology, Xi' an (China)

    2001-09-01

    Surface ablation of cobalt-cemented tungsten carbide hard metal has been carried out in this work using a 308 nm, 20 ns XeCl excimer laser. Surface microphotography and XRD, as well as an electron probe have been used to investigate the transformation of phase and microstructure as a function of the pulse-number of laser shots at a laser fluence of 2.5 J/cm{sup 2}. The experimental results show that the microstructure of cemented tungsten carbide is transformed from the original polygonal grains of size 3 {mu}m to interlaced large, long grains with an increase in the number of laser shots up to 300, and finally to gross grains of size 10 {mu}m with clear grain boundaries after 700 shots of laser irradiation. The crystalline structure of the irradiated area is partly transformed from the original WC to {beta}WC{sub 1-x}, then to {alpha}W{sub 2}C and CW{sub 3}, and finally to W crystal. It is suggested that the undulating 'hill-valley' morphology may be the result of selective removal of cobalt binder from the surface layer of the hard metal. The formation of non-stoichiometric tungsten carbide may result from the escape of elemental carbon due to accumulated heating of the surface by pulsed laser irradiation. (orig.)

  17. Phase transformation during surface ablation of cobalt-cemented tungsten carbide with pulsed UV laser

    Science.gov (United States)

    Li, T.; Lou, Q.; Dong, J.; Wei, Y.; Liu, J.

    Surface ablation of cobalt-cemented tungsten carbide hard metal has been carried out in this work using a 308 nm, 20 ns XeCl excimer laser. Surface microphotography and XRD, as well as an electron probe have been used to investigate the transformation of phase and microstructure as a function of the pulse-number of laser shots at a laser fluence of 2.5 J/cm2. The experimental results show that the microstructure of cemented tungsten carbide is transformed from the original polygonal grains of size 3 μm to interlaced large, long grains with an increase in the number of laser shots up to 300, and finally to gross grains of size 10 μm with clear grain boundaries after 700 shots of laser irradiation. The crystalline structure of the irradiated area is partly transformed from the original WC to βWC1-x, then to αW2C and CW3, and finally to W crystal. It is suggested that the undulating `hill-valley' morphology may be the result of selective removal of cobalt binder from the surface layer of the hard metal. The formation of non-stoichiometric tungsten carbide may result from the escape of elemental carbon due to accumulated heating of the surface by pulsed laser irradiation.

  18. Direct measurement of colloidal interactions between polyaniline surfaces in a uv-curable coating formulation

    DEFF Research Database (Denmark)

    Jafarzadeh, Shadi; Claesson, Per M.; Pan, Jinshan

    2014-01-01

    The interactions between polyaniline particles and polyaniline surfaces in polyester acrylate resin mixed with 1,6-hexanediol diacrylate monomer have been investigated using contact angle measurements and the atomic force microscopy colloidal probe technique. Polyaniline with different characteri......The interactions between polyaniline particles and polyaniline surfaces in polyester acrylate resin mixed with 1,6-hexanediol diacrylate monomer have been investigated using contact angle measurements and the atomic force microscopy colloidal probe technique. Polyaniline with different...... characteristics (hydrophilic and hydrophobic) were synthesized directly on spherical polystyrene particles of 10 μm in diameter. Surface forces were measured between core/shell structured polystyrene/polyaniline particles (and a pure polystyrene particle as reference) mounted on an atomic force microscope...... cantilever and a pressed pellet of either hydrophilic or hydrophobic polyaniline powders, in resins of various polymer:monomer ratios. A short-range purely repulsive interaction was observed between hydrophilic polyaniline (doped with phosphoric acid) surfaces in polyester acrylate resin. In contrast...

  19. High solar cycle spectral variations inconsistent with stratospheric ozone observations

    CERN Document Server

    Ball, W T; Rozanov, E V; Kuchar, A; Sukhodolov, T; Tummon, F; Shapiro, A V; Schmutz, W

    2016-01-01

    Some of the natural variability in climate is understood to come from changes in the Sun. A key route whereby the Sun may influence surface climate is initiated in the tropical stratosphere by the absorption of solar ultraviolet (UV) radiation by ozone, leading to a modification of the temperature and wind structures and consequently to the surface through changes in wave propagation and circulation. While changes in total, spectrally-integrated, solar irradiance lead to small variations in global mean surface temperature, the `top-down' UV effect preferentially influences on regional scales at mid-to-high latitudes with, in particular, a solar signal noted in the North Atlantic Oscillation (NAO). The amplitude of the UV variability is fundamental in determining the magnitude of the climate response but understanding of the UV variations has been challenged recently by measurements from the SOlar Radiation and Climate Experiment (SORCE) satellite, which show UV solar cycle changes up to 10 times larger than p...

  20. BSA adsorption onto nanospheres: Influence of surface curvature as probed by electrophoretic light scattering and UV/vis spectroscopy

    Science.gov (United States)

    Sánchez-Pérez, Julio A.; Gallardo-Moreno, Amparo M.; González-Martín, M. Luisa; Vadillo-Rodríguez, Virginia

    2015-10-01

    The influence of surface curvature on the adsorption of bovine serum albumin (BSA) was evaluated through the combination of two fairly simple techniques: electrophoretic light scattering and UV/vis spectroscopy. Measurements were carried out for a range of protein concentrations (0-320 μg/ml) at pH 3.5, 4.5 and 7 using hydrophobic polystyrene nanospheres of 38.8, 82 and 220 nm in diameter. The results obtained demonstrate that the charge of the BSA molecules in solution dictates the pH-dependent behavior of the protein-coated nanospheres, indicating in all cases a significant adsorption of BSA molecules. At a fixed pH, however, it is the zeta potential that characterizes the uncoated nanospheres normalized by their surface area that primarily controls protein adsorption. In particular, it is found that the rate at which BSA interact with the different nanospheres increases as their negative zeta potential per unit area (or diameter) increases (decreases) regardless of the pH. Moreover, provided that adsorption occurs away from the isoelectric point of the protein, highly curved surfaces are found to stabilize the native-like conformation of BSA upon adsorption by likely reducing lateral interactions between adsorbed molecules.

  1. Areal-Averaged Spectral Surface Albedo in an Atlantic Coastal Area: Estimation from Ground-Based Transmission

    Directory of Open Access Journals (Sweden)

    Evgueni Kassianov

    2017-07-01

    Full Text Available Tower-based data combined with high-resolution satellite products have been used to produce surface albedo at various spatial scales over land. Because tower-based albedo data are available at only a few sites, surface albedos using these combined data are spatially limited. Moreover, tower-based albedo data are not representative of highly heterogeneous regions. To produce areal-averaged and spectrally-resolved surface albedo for regions with various degrees of surface heterogeneity, we have developed a transmission-based retrieval and demonstrated its feasibility for relatively homogeneous land surfaces. Here, we demonstrate its feasibility for a highly heterogeneous coastal region. We use the atmospheric transmission measured during a 19-month period (June 2009–December 2010 by a ground-based Multi-Filter Rotating Shadowband Radiometer (MFRSR at five wavelengths (0.415, 0.5, 0.615, 0.673 and 0.87 µm at the Department of Energy’s Atmospheric Radiation Measurement (ARM Mobile Facility (AMF site located on Graciosa Island. We compare the MFRSR-retrieved areal-averaged surface albedo with albedo derived from Moderate Resolution Imaging Spectroradiometer (MODIS observations, and also a composite-based albedo. We demonstrate that these three methods produce similar spectral signatures of surface albedo; however, the MFRSR-retrieved albedo, is higher on average (≤0.04 than the MODIS-based areal-averaged surface albedo and the largest difference occurs in winter.

  2. The Hubble Wide Field Camera 3 Test of Surfaces in the Outer Solar System: Spectral Variation on Kuiper Belt Objects

    CERN Document Server

    Fraser, Wesley C; Glass, Florian

    2015-01-01

    Here we present additional photometry of targets observed as part of the Hubble Wide Field Camera 3 Test of Surfaces in the Outer Solar System. 12 targets were re-observed with the Wide Field Camera 3 in optical and NIR wavebands designed to compliment those used during the first visit. Additionally, all observations originally presented by Fraser and Brown (2012) were reanalyzed through the same updated photometry pipeline. A reanalysis of the optical and NIR colour distribution reveals a bifurcated optical colour distribution and only two identifiable spectral classes, each of which occupies a broad range of colours and have correlated optical and NIR colours, in agreement with our previous findings. We report the detection of significant spectral variations on 5 targets which cannot be attributed to photometry errors, cosmic rays, point spread function or sensitivity variations, or other image artifacts capable of explaining the magnitude of the variation. The spectrally variable objects are found to have ...

  3. Laser cleaning of the metallic thin films from silicon wafer surface with UV laser radiation

    Science.gov (United States)

    Apostol, Ileana; Apostol, Dan; Victor, Damian; Timcu, Adrian; Iordache, Iuliana; Castex, Marie-Claude C.; Galli, Roberta; Ulieru, Dumitru G.

    2004-10-01

    The interest to use laser surface processing in microtechnology as a friendly method from the technologic and environmental point of view lead our studies about laser radiation interaction with photo-resist and metallic thin films. In this view we have tried in our experiments to process metallic thin films deposited on silicon substrate by using laser radiation. To obtain a good quality of the metallic thin film removal from the silicon surface a careful selection of the incident laser intensity, number of pulses and irradiation geometry is needed. The threshold value for the laser cleaning intensity depends on the number of incident laser pulses. A careful experimental estimation of the cleaning conditions from the point of view of incident laser energy, fluence, intensity and irradiation geometry was realized for aluminum, copper, and chromium thin films.

  4. NANOSCALE STRUCTURES GENERATION WITHIN THE SURFACE LAYER OF METALS WITH SHORT UV LASER PULSES

    Directory of Open Access Journals (Sweden)

    Dmitry S. Ivanov

    2017-01-01

    Full Text Available We have completed modeling of a laser pulse influence on a gold target. We have applied a hybrid atomistic-continuum model to analyze the physical mechanisms responsible for the process of nanostructuring. The model combines the advantages of Molecular Dynamics and Two Temperature Model. We have carried out a direct comparison of the modeling results and experimental data on nano-modification due to a single ps laser pulse at the energy densities significantly exceeding the melting threshold. The experimental data is obtained due to a laser pulse irradiation at the wavelength of 248 nm and duration of 1.6 ps. The mask projection (diffraction grating creates the sinusoidal intensity distribution on a gold surface with periods of 270 nm, 350 nm, and 500 nm. The experimental data and modeling results have demonstrated a good match subject to complex interrelations between a fast material response to the laser excitation, generation of crystal defects, phase transitions and hydrodynamic motion of matter under condition of strong laser-induced non-equilibrium. The performed work confirms the proposed approach as a powerful tool for revealing the physical mechanisms underlying the process of nanostructuring of metal surfaces. Detailed understanding of the dynamics of these processes gives the possibility for designing the topology of functional surfaces on nano- and micro-scales.

  5. Comparative tensile strength study of the adhesion improvement of PTFE by UV photon assisted surface processing

    Science.gov (United States)

    Hopp, B.; Geretovszky, Zs.; Bertóti, I.; Boyd, I. W.

    2002-01-01

    Poly(tetrafluoroethylene) (PTFE) is notable for its non-adhesive and non-reactive properties. A number of technologies can potentially benefit from the application of PTFE, but these characteristics restrict the ability to structuring its surface. In this paper, we present results on two ultraviolet photon assisted treatments of PTFE. The originally poor adhesion was significantly improved by both 172 nm excimer lamp and 193 nm excimer laser assisted surface treatments. While Xe2∗ lamp irradiation, applied in a modest vacuum environment, was sufficient by itself to improve adhesion, the ArF laser process was only effective when the irradiated interface was in contact with 1,2-diaminoethane photoreagent. It was found that the tensile strength of an epoxy resin glued interface created on treated surfaces depended strongly on the applied number of laser pulses and lamp irradiation time. Laser treatment caused fast tensile strength increase during the first 50-500 pulses, while after this it saturates slowly at about 5.5 MPa in the 500-2500 pulse domain. The excimer lamp irradiation resulted in a maximum tensile strength of approximately 10 MPa after 2 min irradiation time which reduced to about 65% of the peak value at longer times.

  6. Effect of altitude on solar UVR and spectral and spatial variations of UV irradiances measured inWagrain, Austria in winter

    DEFF Research Database (Denmark)

    Baczynska, Katarzyna A; Pearson, Andy J; O'Hagan, John B;

    2013-01-01

    Ultraviolet radiation spectral irradiance was measured at different altitudes on horizontal and tilted planes in different azimuth directions on cloudless days in Austria, in March 2010, within the Impact of Climatic and Environmental factors on Personal Ultraviolet Radiation Exposure project...

  7. Fabrication of a SU-8-based polymer-enclosed channel with a penetrating UV/ozone-modified interior surface for electrokinetic separation of proteins

    Science.gov (United States)

    Chang, Chia-Jung; Yang, Chung-Shi; Lan, Li-Hua; Wang, Pen-Cheng; Tseng, Fan-Gang

    2010-11-01

    This paper introduces electrokinetic separation inside fully cross-linked epoxy-based polymer channels that were batch modified on the inner surfaces using a penetrating UV/ozone treatment from the outside. The treatment can employ either a 254 nm UV source in an ozone-rich environment or a stand-alone 172 nm UV source to directly generate C=O hydrophilic functional groups on the embedded polymer channel wall surfaces. Short-wavelength UV radiation was employed to break polymer surface bonds inside the channel. Ozone generated directly from air or supplied externally oxidized the reaction site on the activated polymer surface to generate the desired functional groups. An epoxy-based photoresist compound, SU-8 (MicroChem, MA), which is widely used in microfluidic systems, was employed to demonstrate the surface modification. Fourier transform infrared spectroscopy (FTIR) and high resolution x-ray photoelectron spectroscopy (HRXPS) were employed to characterize the functional groups that formed after the UV/ozone surface modification and to confirm the formation of O-H functional groups from the phenol group covalently bonded to the SU-8 surface, attributed mostly to the surface hydrophilicity modification. Water contact angles on the modified surface ranged from 72° to 12° depending on the processing time, UV power and ozone concentration. These angles were retained for at least 4 weeks after the process. Finally, the inner wall surfaces of the SU-8-enclosed channels were successfully modified using this technology, and rapid water transportation and EOF pumping were visualized inside the channel after surface modification. Successful electrokinetic separation of 10 mM BSA and 10 mM anti-rabbit IgG labeled with FITC inside the channel was also carried out. The polymer channel revealed a surface charge density of 75% of the zeta potential on a microslide glass surface, indicating the potential for molecule separation using polymer channels instead of glass channels

  8. Luminescence properties of IR-emitting bismuth centres in SiO{sub 2}-based glasses in the UV to near-IR spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Firstova, E G; Vel' miskin, V V; Firstov, S V; Dianov, E M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Bufetov, I A [Moscow Institute of Physics and Technology (State University), Dolgoprudnyi, Moscow Region (Russian Federation); Khopin, V F; Gur' yanov, A N [G.G.Devyatykh Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation); Bufetova, G A [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Nishchev, K N [N.P. Ogarev Mordovia State University, Physics and Chemistry Institute, Saransk (Russian Federation)

    2015-01-31

    We have studied UV excitation spectra of IR luminescence in bismuth-doped glasses of various compositions and obtained energy level diagrams of IR-emitting bismuth-related active centres (BACs) associated with silicon and germanium atoms up to ∼5.2 eV over the ground level. A possible energy level diagram of the BACs in phosphosilicate glass has been proposed. The UV excitation peaks for the IR luminescence of the BACs in the glasses have been shown to considerably overlap with absorption bands of the Bi{sup 3+} ion, suggesting that Bi{sup 3+} may participate in BAC formation. (optical fibres)

  9. Luminescence properties of IR-emitting bismuth centres in SiO2-based glasses in the UV to near-IR spectral region

    Science.gov (United States)

    Firstova, E. G.; Bufetov, I. A.; Khopin, V. F.; Vel'miskin, V. V.; Firstov, S. V.; Bufetova, G. A.; Nishchev, K. N.; Gur'yanov, A. N.; Dianov, E. M.

    2015-01-01

    We have studied UV excitation spectra of IR luminescence in bismuth-doped glasses of various compositions and obtained energy level diagrams of IR-emitting bismuth-related active centres (BACs) associated with silicon and germanium atoms up to ~5.2 eV over the ground level. A possible energy level diagram of the BACs in phosphosilicate glass has been proposed. The UV excitation peaks for the IR luminescence of the BACs in the glasses have been shown to considerably overlap with absorption bands of the Bi3+ ion, suggesting that Bi3+ may participate in BAC formation.

  10. Spectral Reflectance Characteristics of Different Snow and Snow-Covered Land Surface Objects and Mixed Spectrum Fitting

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jia-hua; ZHOU Zheng-ming; WANG Pei-juan; YAO Feng-mei; Liming Yang

    2011-01-01

    The field spectroradiometer was used to measure spectra of different snow and snow-covered land surface objects in Beijing area.The result showed that for a pure snow spectrum,the snow reflectance peaks appeared from visible to 800 nm band locations; there was an obvious absorption valley of snow spectrum near 1 030 nm wavelength.Compared with fresh snow,the reflection peaks of the old snow and melting snow showed different degrees of decline in the ranges of 300~1 300,1 700~1 800 and 2 200~2 300 nm,the lowest was from the compacted snow and frozen ice.For the vegetation and snow mixed spectral characteristics,it was indicated that the spectral reflectance increased for the snow-covered land types (including pine leaf with snow and pine leaf on snow background),due to the influence of snow background in the range of 350~1 300 nm.However,the spectrum reflectance of mixed pixel remained a vegetation spectral characteristic.In the end,based on the spectrum analysis of snow,vegetation,and mixed snow/vegetation pixels,the mixed spectral fitting equations were established,and the results showed that there was good correlation between spectral curves by simulation fitting and observed ones (correlation coefficient R2 =0.950 9).

  11. Spectral reflectance characteristics of different snow and snow-covered land surface objects and mixed spectrum fitting.

    Science.gov (United States)

    Zhang, Jia-Hua; Zhou, Zheng-Ming; Wang, Pei-Juan; Yao, Feng-Mei; Liming, Yang

    2011-09-01

    The field spectroradiometer was used to measure spectra of different snow and snow-covered land surface objects in Beijing area. The result showed that for a pure snow spectrum, the snow reflectance peaks appeared from visible to 800 nm band locations; there was an obvious absorption valley of snow spectrum near 1 030 nm wavelength. Compared with fresh snow, the reflection peaks of the old snow and melting snow showed different degrees of decline in the ranges of 300-1 300, 1 700-1 800 and 2 200-2 300 nm, the lowest was from the compacted snow and frozen ice. For the vegetation and snow mixed spectral characteristics, it was indicated that the spectral reflectance increased for the snow-covered land types (including pine leaf with snow and pine leaf on snow background), due to the influence of snow background in the range of 350-1 300 nm. However, the spectrum reflectance of mixed pixel remained a vegetation spectral characteristic. In the end, based on the spectrum analysis of snow, vegetation, and mixed snow/vegetation pixels, the mixed spectral fitting equations were established, and the results showed that there was good correlation between spectral curves by simulation fitting and observed ones (correlation coefficient R2 = 0.950 9).

  12. Areal-averaged and Spectrally-resolved Surface Albedo from Ground-based Transmission Data Alone: Toward an Operational Retrieval

    Energy Technology Data Exchange (ETDEWEB)

    Kassianov, Evgueni I.; Barnard, James C.; Flynn, Connor J.; Riihimaki, Laura D.; Michalsky, Joseph; Hodges, G. B.

    2014-08-22

    We present here a simple retrieval of the areal-averaged and spectrally resolved surface albedo using only ground-based measurements of atmospheric transmission under fully overcast conditions. Our retrieval is based on a one-line equation and widely accepted assumptions regarding the weak spectral dependence of cloud optical properties in the visible and near-infrared spectral range. The feasibility of our approach for the routine determinations of albedo is demonstrated for different landscapes with various degrees of heterogeneity using three sets of measurements:(1) spectrally resolved atmospheric transmission from Multi-Filter Rotating Shadowband Radiometer (MFRSR) at wavelength 415, 500, 615, 673, and 870 nm, (2) tower-based measurements of local surface albedo at the same wavelengths, and (3) areal-averaged surface albedo at four wavelengths (470, 560, 670 and 860 nm) from collocated and coincident Moderate Resolution Imaging Spectroradiometer (MODIS) observations. These integrated datasets cover both long (2008-2013) and short (April-May, 2010) periods at the ARM Southern Great Plains (SGP) site and the NOAA Table Mountain site, respectively. The calculated root mean square error (RMSE), which is defined here as the root mean squared difference between the MODIS-derived surface albedo and the retrieved area-averaged albedo, is quite small (RMSE≤0.01) and comparable with that obtained previously by other investigators for the shortwave broadband albedo. Good agreement between the tower-based daily averages of surface albedo for the completely overcast and non-overcast conditions is also demonstrated. This agreement suggests that our retrieval originally developed for the overcast conditions likely will work for non-overcast conditions as well.

  13. UV and gamma irradiation effects on surface properties of polyurethane derivative from castor oil

    Energy Technology Data Exchange (ETDEWEB)

    Azevedo, Elaine C.; Nascimento, Eduardo M., E-mail: helunica@yahoo.com.br [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Chierice, Gilberto O.; Claro Neto, Salvador [Universidade de Sao Paulo (IQSC/USP), Sao Carlos, SP (Brazil). Instituto de Quimica; Lepienski, Carlos M. [Universidade Federal do Parana (UFPR), Curitiba (Brazil)

    2013-07-01

    Gamma and ultraviolet radiation effects on hardness, elastic modulus and viscoelastic properties of polyurethane derived from castor oil (PU) were investigated by nanoindentation tests. Modifications on surface morphology, induce by radiation, were observed by atomic force microscopy. The polyurethane derivative from castor oil shows good resistance to gamma radiation, with only small changes in hardness, elastic modulus, viscoelastic properties and contact angle. The hardness of PY increases at the near surface region due to UVA radiation and decreases after UVC radiation. The contact angle for water drop decreases after UVC radiation, by not after gamma radiation, despite a significant increase in roughness. Such results are attributed to different responses from polyurethane to radiation energy. Increase in hardness due to UVA is attributed to a higher crosslinking at shallow depths, while a decrease in mechanical properties may be attributed to chain scission. These results are consistent with the modifications on viscoelastic properties. Shore D hardness did not show the same trend as observed by nanoindentation results. Hardness, viscoelastic properties and contact angle of castor oil polyurethane are more severely influenced by UVC radiation, while gamma radiation does not have a significant effect. (author)

  14. UV and gamma irradiation effects on surface properties of polyurethane derivate from castor oil

    Directory of Open Access Journals (Sweden)

    Elaine C. Azevedo

    2013-01-01

    Full Text Available Gamma and ultraviolet radiation effects on hardness, elastic modulus and viscoelastic properties of polyurethane derived from castor oil (PU were investigated by nanoindentation tests. Modifications on surface morphology, induced by radiation, were observed by atomic force microscopy. The polyurethane derivate from castor oil shows good resistance to gamma radiation, with only small changes in hardness, elastic modulus, viscoelastic properties and contact angle. The hardness of PU increases at the near surface region due to UVA radiation and decreases after UVC radiation. The contact angle for water drop decreases after UVC radiation, but not after gamma radiation, despite a significant increase in roughness. Such results are attributed to different responses from polyurethane to radiation energy. Increase in hardness due to UVA is attributed to a higher crosslinking at shallow depths, while a decrease in mechanical properties may be attributed to chain scission. These results are consistent with the modifications on viscoelastic properties. Shore D hardness did not show the same trend as observed by nanoindentation results. Hardness, viscoelastic properties and contact angle of castor oil polyurethane are more severely influenced by UVC radiation, while gamma radiation does not have a significant effect.

  15. Effect of UV/ozone irradiation on the surface properties of electrospun webs and films prepared from polydimethylsiloxane-urea copolymers

    Science.gov (United States)

    Yilgor, Emel; Kaymakci, Orkun; Isik, Mehmet; Bilgin, Sevilay; Yilgor, Iskender

    2012-03-01

    Highly hydrophobic surfaces of silicone-urea copolymers were transformed into hydrophilic ones upon UV/ozone treatment. The extent of surface modification was strongly dependent on the sample preparation method and the exposure time. The physical and chemical changes at the copolymer surfaces were analyzed by spectroscopic (XPS, ATR-FTIR), microscopic (SEM) techniques and static water contact angle measurements. ATR-FTIR spectra clearly showed the dramatic change in the strongly hydrogen bonded urea hard segments and the degradation of dimethylsiloxane units in silicone-urea copolymers. XPS results revealed the formation of SiOx on the surface, which gradually increased with exposure time. After 3 h of UV/ozone exposure, Si(2p) binding energy shifted from 101.9 to 102.85 eV, which is a clear indication of an increase in the oxidation state of silicon. The deterioration of microroughness of the electrospun webs upon UV/ozone exposure, which was revealed by SEM, resulted in a dramatic decrease in the static water contact angle values from 129 to 62°. These results clearly show that UV/ozone process is a very simple and facile method to transform hydrophobic silicone-urea copolymer surfaces into fairly hydrophilic ones.

  16. Effect of UV/ozone irradiation on the surface properties of electrospun webs and films prepared from polydimethylsiloxane-urea copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Yilgor, Emel; Kaymakci, Orkun; Isik, Mehmet; Bilgin, Sevilay [Surface Science and Technology Center (KUYTAM), Chemistry Department, Koc University, Istanbul 34450 (Turkey); Yilgor, Iskender, E-mail: iyilgor@ku.edu.tr [Surface Science and Technology Center (KUYTAM), Chemistry Department, Koc University, Istanbul 34450 (Turkey)

    2012-03-01

    Highly hydrophobic surfaces of silicone-urea copolymers were transformed into hydrophilic ones upon UV/ozone treatment. The extent of surface modification was strongly dependent on the sample preparation method and the exposure time. The physical and chemical changes at the copolymer surfaces were analyzed by spectroscopic (XPS, ATR-FTIR), microscopic (SEM) techniques and static water contact angle measurements. ATR-FTIR spectra clearly showed the dramatic change in the strongly hydrogen bonded urea hard segments and the degradation of dimethylsiloxane units in silicone-urea copolymers. XPS results revealed the formation of SiO{sub x} on the surface, which gradually increased with exposure time. After 3 h of UV/ozone exposure, Si(2p) binding energy shifted from 101.9 to 102.85 eV, which is a clear indication of an increase in the oxidation state of silicon. The deterioration of microroughness of the electrospun webs upon UV/ozone exposure, which was revealed by SEM, resulted in a dramatic decrease in the static water contact angle values from 129 to 62 Degree-Sign . These results clearly show that UV/ozone process is a very simple and facile method to transform hydrophobic silicone-urea copolymer surfaces into fairly hydrophilic ones.

  17. Power spectral analysis of surface electromyography (EMG) at matched contraction levels of the first dorsal interosseous muscle in stroke survivors.

    Science.gov (United States)

    Li, Xiaoyan; Shin, Henry; Zhou, Ping; Niu, Xun; Liu, Jie; Rymer, William Zev

    2014-05-01

    The objective of this study was to help assess complex neural and muscular changes induced by stroke using power spectral analysis of surface electromyogram (EMG) signals. Fourteen stroke subjects participated in the study. They were instructed to perform isometric voluntary contractions by abducting the index finger. Surface EMG signals were collected from the paretic and contralateral first dorsal interosseous (FDI) muscles with forces ranging from 30% to 70% maximum voluntary contraction (MVC) of the paretic muscle. Power spectral analysis was performed to characterize features of the surface EMG in paretic and contralateral muscles at matched forces. A Linear Mixed Model was applied to identify the spectral changes in the hemiparetic muscle and to examine the relation between spectral parameters and contraction levels. Regression analysis was performed to examine the correlations between spectral characteristics and clinical features. Differences in power spectrum distribution patterns were observed in paretic muscles when compared with their contralateral pairs. Nine subjects showed increased mean power frequency (MPF) in the contralateral side (>15 Hz). No evident spectrum difference was observed in 3 subjects. Only 2 subjects had higher MPF in the paretic muscle than the contralateral muscle. Pooling all subjects' data, there was a significant reduction of MPF in the paretic muscle compared with the contralateral muscle (paretic: 168.7 ± 7.6 Hz, contralateral: 186.1 ± 8.7 Hz, mean ± standard error, F=36.56, ppower spectrum did not confirm a significant correlation between the MPF and contraction force in either hand (F=0.7, p>0.5). There was no correlation between spectrum difference and Fugl-Meyer or Chedoke scores, or ratio of paretic and contralateral MVC (p>0.2). There appears to be complex muscular and neural processes at work post stroke that may impact the surface EMG power spectrum. The majority of the tested stroke subjects had lower MPF in the

  18. Influence of slight microstructural gradients on the surface properties of Ti6Al4V irradiated by UV

    Energy Technology Data Exchange (ETDEWEB)

    Gallardo-Moreno, A.M. [Department of Applied Physics, University of Extremadura, Av. Elvas s/n, 06071-Badajoz (Spain) and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Badajoz (Spain); Multigner, M. [National Centre for Metallurgical Research (CENIM-CSIC), Av. Gregorio del Amo 8, 28040-Madrid (Spain); Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid (Spain); Pacha-Olivenza, M.A. [Department of Applied Physics, University of Extremadura, Av. Elvas s/n, 06071-Badajoz (Spain) and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Badajoz (Spain); Lieblich, M.; Jimenez, J.A. [National Centre for Metallurgical Research (CENIM-CSIC), Av. Gregorio del Amo 8, 28040-Madrid (Spain); Gonzalez-Carrasco, J.L. [National Centre for Metallurgical Research (CENIM-CSIC), Av. Gregorio del Amo 8, 28040-Madrid (Spain); Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid (Spain); Gonzalez-Martin, M.L., E-mail: mlglez@unex.es [Department of Applied Physics, University of Extremadura, Av. Elvas s/n, 06071-Badajoz (Spain) and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Badajoz (Spain)

    2009-08-30

    Ti6Al4V alloy is one of the most widely used materials for biomedical implants. Among its properties, it is remarkable the photoactivity displayed by its passive layer, which is mainly composed by titanium dioxide. However, variations in the processing conditions may yield to differences in the microstructure which can be reflected on the surface properties of the machined product. From contact angle measurements taken on different zones of samples removed from a commercial bar of Ti6Al4V, it has been shown that the modifications of the surface Gibbs energy suffered by the alloy under UV irradiation have a radial dependence. This behaviour is related to slight microstructural changes of the alloy, particularly with an increase in the volume fraction of the {beta}-phase when moving to the interior of the sample, which alters the composition and/or microstructure of the passive layer along its radius. This study shows that gradients in the microstructure and physical properties are sample size dependent and are likely related to thermal gradients during processing.

  19. Optimization of photocatalytic degradation of palm oil mill effluent in UV/ZnO system based on response surface methodology.

    Science.gov (United States)

    Ng, Kim Hoong; Cheng, Yoke Wang; Khan, Maksudur R; Cheng, Chin Kui

    2016-12-15

    This paper reports on the optimization of palm oil mill effluent (POME) degradation in a UV-activated-ZnO system based on central composite design (CCD) in response surface methodology (RSM). Three potential factors, viz. O2 flowrate (A), ZnO loading (B) and initial concentration of POME (C) were evaluated for the significance analysis using a 2(3) full factorial design before the optimization process. It is found that all the three main factors were significant, with contributions of 58.27% (A), 15.96% (B) and 13.85% (C), respectively, to the POME degradation. In addition, the interactions between the factors AB, AC and BC also have contributed 4.02%, 3.12% and 1.01% to the POME degradation. Subsequently, all the three factors were subjected to statistical central composite design (CCD) analysis. Quadratic models were developed and rigorously checked. A 3D-response surface was subsequently generated. Two successive validation experiments were carried out and the degradation achieved were 55.25 and 55.33%, contrasted with 52.45% for predicted degradation value.

  20. Pseudomonas aeruginosa biofilm formation and UV/irradiation exposure change surface and chemical structures of Pre-Production Resin Pellets

    Science.gov (United States)

    Stam, C. N.; Neal, A.; Park, S.; Mielke, R.; Tsapin, A. I.; Bhartia, R.; Salas, E.; Hug, W.; Behar, A. E.; Nadeau, J. L.

    2011-12-01

    Microbial interactions with synthetic polymers in open ocean is poorly understood. Plastics are a major and persistent contaminant of ocean waters. Many of these plastics are contaminated with toxic and synthetic chemicals that persist in the environment with minimal degradation. The purpose of this study is to look at the effects that microbial biofilm communities have on both surface and chemical structures of pre-production resin pellets (PRPs). Pseudomonas aeruignosa was grown with PRPs under multiple growth and nutrient conditions. These conditions were combined with varying lengths of UV exposures common to ocean environments. Material degradation of the PRPs and the changing surface and chemical structures of these synthetic polymers was evaluated using a combination of Fourier transform infrared spectroscopy, environmental scanning electron microscopy, scanning transmission electron microscopy, X-ray microtomography, and ArcGIS mapping. This study correlates with previous studies conducted on environmental PRP's , collected on the 2009 Project Kaisei expedition in the Subtropical Convergence Zone of the North Pacific Gyre. Further studies are needed to develop a full understanding of degradation rates of synthetic polymers in oceanic environments.

  1. Automated mapping of impervious surfaces in urban and suburban areas: Linear spectral unmixing of high spatial resolution imagery

    Science.gov (United States)

    Yang, Jian; He, Yuhong

    2017-02-01

    Quantifying impervious surfaces in urban and suburban areas is a key step toward a sustainable urban planning and management strategy. With the availability of fine-scale remote sensing imagery, automated mapping of impervious surfaces has attracted growing attention. However, the vast majority of existing studies have selected pixel-based and object-based methods for impervious surface mapping, with few adopting sub-pixel analysis of high spatial resolution imagery. This research makes use of a vegetation-bright impervious-dark impervious linear spectral mixture model to characterize urban and suburban surface components. A WorldView-3 image acquired on May 9th, 2015 is analyzed for its potential in automated unmixing of meaningful surface materials for two urban subsets and one suburban subset in Toronto, ON, Canada. Given the wide distribution of shadows in urban areas, the linear spectral unmixing is implemented in non-shadowed and shadowed areas separately for the two urban subsets. The results indicate that the accuracy of impervious surface mapping in suburban areas reaches up to 86.99%, much higher than the accuracies in urban areas (80.03% and 79.67%). Despite its merits in mapping accuracy and automation, the application of our proposed vegetation-bright impervious-dark impervious model to map impervious surfaces is limited due to the absence of soil component. To further extend the operational transferability of our proposed method, especially for the areas where plenty of bare soils exist during urbanization or reclamation, it is still of great necessity to mask out bare soils by automated classification prior to the implementation of linear spectral unmixing.

  2. Adaption of the MODIS aerosol retrieval algorithm by airborne spectral surface reflectance measurements over urban areas: a case study

    Directory of Open Access Journals (Sweden)

    E. Jäkel

    2015-07-01

    Full Text Available MODIS retrievals of the aerosol optical depth (AOD are biased over urban areas, where surface reflectance is not well characterized. Since the operational MODIS aerosol retrieval for dark targets assumes fixed spectral slopes to calculate the surface reflectance at 0.47 μm, the algorithm may fail in urban areas with different spectral characteristics of the surface reflectance. To investigate this bias we have implemented variable spectral slopes into the operational MODIS aerosol algorithms of Collection 5 (C5 and C6. The variation of slopes is based on airborne measurements of surface reflectances over the city of Zhongshan, China. AOD retrieval results of the operational and the modified algorithms were compared for a MODIS measurement over Zhongshan. For this case slightly lower AOD values were derived using the modified algorithm. The retrieval methods were additionally applied to MODIS data of the Beijing area for a period between 2010–2014 when also AERONET data were available. A reduction of the differences between the AOD retrieved using the modified C5 algorithm and AERONET was found, whereby the mean difference from 0.31 ± 0.11 for the operational C5 and 0.18 ± 0.12 for the operational C6 where reduced to a mean difference of 0.09 ± 0.18 by using the modified C5 retrieval. Furthermore, the sensitivity of the MODIS AOD retrieval for several surface types was investigated. Radiative transfer simulations were performed to model reflectances at top of atmosphere for predefined aerosol properties. The reflectances were used as input for the retrieval methods. It is shown that the operational MODIS AOD retrieval over land reproduces the AOD reference input of 0.85 for dark surface types [retrieved AOD = 0.87 (C5]. An overestimation of AOD = 0.99 is found for urban surfaces, whereby the modified C5 algorithm shows a good performance with a retrieved value of AOD = 0.86.

  3. Effect of nontronite smectite clay on the chemical evolution of several organic molecules under simulated Mars surface UV radiation conditions

    Science.gov (United States)

    Poch, Olivier; Dequaire, Tristan; Stalport, Fabien; Jaber, Maguy; Lambert, Jean-François; Szopa, Cyril; Coll, Patrice

    2015-04-01

    The search for organic carbon-containing molecules at the surface of Mars, as clues of past habitability or remnants of life, is a major scientific goal for Mars exploration. Several lines of evidence, including the detection of phyllosilicates, suggest that early Mars offered favorable conditions for long-term sustaining of water. As a consequence, we can assume that in those days, endogenous chemical processes, or even primitive life, may have produced organic matter on Mars. Moreover, exogenous delivery from small bodies or dust particles is likely to have brought fresh organic molecules to the surface of Mars up today. Organic matter is therefore expected to be present at the surface/subsurface of the planet. But the current environmental conditions at the surface - UV radiation, oxidants and energetic particles - generate physico-chemical processes that may affect organic molecules. On the other hand, on Earth, phyllosilicates are known to accumulate and preserve organic matter. But are phyllosilicates efficient at preserving organic molecules under the current environmental conditions at the surface of Mars? We have monitored the qualitative and quantitative evolutions of glycine, urea and adenine interacting with the Fe3+-smectite clay nontronite, one of the most abundant phyllosilicates present at the surface of Mars, under simulated Martian surface ultraviolet light (190-400 nm), mean temperature (218 ± 2 K) and pressure (6 ± 1 mbar) in a laboratory simulation setup. We have tested organic-rich samples which may be representative of the evaporation of a warm little pond of liquid water having concentrated organics on Mars. For each molecule, we have observed how the nontronite influences the quantum efficiency of its photodecomposition and the nature of its solid evolution products. The results reveal a pronounced photoprotective effect of nontronite on the evolution of glycine and adenine: their efficiencies of photodecomposition are reduced by a factor

  4. Climatology of Ultra Violet(UV) Irradiance at the Surface of the Earth as Measured by the Belgian UV Radiation Monitoring Network

    Science.gov (United States)

    Pandey, Praveen; Gillotay, Didier; Depiesse, Cedric

    2016-08-01

    In this paper we describe the network of ground-based ultraviolet (UV) radiation monitoring stations in Belgium. The evolution of the entire network, together with the details of measuring instruments is given. The observed cumulative irradiations -UVB, UVA and total solar irradiation (TSI)- over the course of measurement for three stations -a northern (Ostende), central (Uccle) and a southern (Redu)- are shown. The longest series of measurement shown in this study is at Uccle, Brussels, from 1995 till 2014. Thus, the variation of the UV index, together with the variation of irradiations during summer and winter months at Uccle are shown as a part of this climatological study. The trend of UVB irradiance over the above mentioned three stations is shown. This UVB trend is studied in conjunction with the long-term satellite-based total column ozone value over Belgium, which shows two distinct trends marked by a change point. The total column ozone trend following the change point is positive. It is also seen that the UVB trend is positive for the urban/sub-urban sites: Uccle and Redu. Whereas the UVB trend at Ostende, which is a coastal site, is not positive. A possible explanation of this relation between total column ozone and UVB trend could be associated with aerosols, which is shown in this paper by means of a radiative transfer model based study -as a part of a preliminary investigation. It is seen that the UVI is influenced by the type of aerosols.

  5. Research and Measurement of Metal Cathode Vacuum UV Detector' s Spectral Response%金属阴极真空型紫外探测器光谱响应测试研究

    Institute of Scientific and Technical Information of China (English)

    赵文锦; 杨杰; 丁继华

    2013-01-01

    One key superiority of ultraviolet detection comparing with infrared detection is clear background and high SNR (signal noise ratio).But it depends strictly on the solar blind characteristic.By spectroradiometric measurement system,the spectral response curve of metal cathode vacuum UV detector is measured.The measurement result is compared with the one of traditional Rb2Te cathode UV detector especially for their solar blind characteristic.Finally,the potential application of metal cathode vacuum UV detector is demonstrated because of its extraordinary superiority of solar blind characteristic.%紫外探测相比红外探测的一个重要优势是背景干净,信噪比高.这一优势充分体现的前提是其日盲特性.本文利用光谱测试系统对制作的金属阴极真空紫外探测器的光谱响应进行测试,并将测试结果与传统的碲铷阴极紫外探测器的光谱响应曲线进行对比,比较了这两类器件的紫外日盲特性,发现金属阴极在日盲特性方面有一定的优势,最终指出该类型器件在某些特殊场合的潜在应用.

  6. Modification of amorphous poly(ethylene terephthalate) surface by UV light and plasma for fabrication of an electrophoresis chip with an integrated gold microelectrode.

    Science.gov (United States)

    Hao, Zhenxia; Chen, Hengwu; Zhu, Xiaoying; Li, Jingmin; Liu, Chong

    2008-10-31

    Amorphous poly(ethylene terephthalate) (PET), which possess a low softening temperature (T(s)=75 degrees C), was exploited to fabricate the electrophoresis chip with an integrated gold electrode for amperometric detection, with emphases being focused on the PET surface modification via UV light and air plasma. Both UV irradiation and plasma treatment were found to be able to improve the surface wettability, enhance the supported electroosmotic flow (EOF), and increase thermal bonding strength of PET sheets, with the latter being more efficient and less time-consuming than the former in the surface modification. Upon treated with plasma for 2 min, the PET sheets could be thermally bonded at 65 degrees C. T-peer test showed that the bonding strength increased from 10 g/cm for native PET sheets to 1250 g/cm for the plasma treated sheets when chips were bonded at the softening point, Attenuated-total-internal-reflection spectrum showed that, after being exposed to the UV light, carboxylic groups site-selectively formed in the UV-exposed region on PET surface. These UV-induced carboxylic groups were further utilized as the scaffold for preparation of micro-gold electrode via electroless gold plating. By using this established UV-directed electroless plating and the plasma-assisted thermal bonding techniques, the full PET electrophoresis chip with an integrated micro-gold electrode could be fabricated in common chemistry laboratory without the need of clean rooms. The fabricated PET chips were demonstrated for separation and detection of model analytes of dopamine (DA) and catechol (CA). Satisfactory resolution of the two analytes was achieved within 40s, and detection limits of 0.87 microM and 1.28 microM for DA and CA were obtained, respectively.

  7. Investigations on the effect of high surface albedo on erythemally effective UV irradiance: results of a campaign at the Salar de Uyuni, Bolivia.

    Science.gov (United States)

    Reuder, Joachim; Ghezzi, Flavio; Palenque, Eduardo; Torrez, Rene; Andrade, Marco; Zaratti, Francesco

    2007-04-02

    Measurements and model calculations have been performed to study the effect of high surface albedo on erythemally effective UV irradiance. A central part of the investigation has been a one week measurement campaign at Salar de Uyuni in the Southern part of the Bolivian Altiplano. The Salar de Uyuni, the largest salt lake of the world, is characterized by largely homogeneous surface conditions during most of the year. Albedo measurements performed by an UV radiometer result in a reflectivity for erythemally effective radiation of 0.69+/-0.02. The measurements show hardly any dependency on solar elevation, indicating the homogeneity of the surface and nearly isotropic reflection properties of the Salar. The effects of the high albedo surface on the erythemally effective irradiance, i.e. the UV index (UVI), has been experimentally determined by simultaneous measurements of several UV radiometers located at different sites around and on the Salar. In this context a method for the minimization of systematic deviations between the individual detectors used for the investigation is presented. It ensures the intercomparability of the performed UV measurements within +/-2% which is a distinct improvement compared to the typical absolute accuracy of UV irradiance measurements in the order of +/-5%. For solar elevations around 50 degrees the UVI measured close to the center of the Salar is typically enhanced by 20% compared to the values determined outside. Towards lower solar elevations this increase becomes slightly weaker. The measurements agree well with both, own corresponding 1D and previously published 3D radiative transfer calculations from literature.

  8. Local Environment and Interactions of Liquid and Solid Interfaces Revealed by Spectral Line Shape of Surface Selective Nonlinear Vibrational Probe

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shun-Li; Fu, Li; Chase, Zizwe A.; Gan, Wei; Wang, Hong-Fei

    2016-11-10

    Vibrational spectral lineshape contains important detailed information of molecular vibration and reports its specific interactions and couplings to its local environment. In this work, recently developed sub-1 cm-1 high-resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS) was used to measure the -C≡N stretch vibration in the 4-n-octyl-4’-cyanobiphenyl (8CB) Langmuir or Langmuir-Blodgett (LB) monolayer as a unique vibrational probe, and the spectral lineshape analysis revealed the local environment and interactions at the air/water, air/glass, air/calcium fluoride and air/-quartz interfaces for the first time. The 8CB Langmuir or LB film is uniform and the vibrational spectral lineshape of its -C≡N group has been well characterized, making it a good choice as the surface vibrational probe. Lineshape analysis of the 8CB -C≡N stretch SFG vibrational spectra suggests the coherent vibrational dynamics and the structural and dynamic inhomogeneity of the -C≡N group at each interface are uniquely different. In addition, it is also found that there are significantly different roles for water molecules in the LB films on different substrate surfaces. These results demonstrated the novel capabilities of the surface nonlinear spectroscopy in characterization and in understanding the specific structures and chemical interactions at the liquid and solid interfaces in general.

  9. Polyhedral oligomeric silsesquioxane trisilanols as pigment surface modifiers for fluoropolymer based thickness sensitive spectrally selective (TSSS) paint coatings

    Energy Technology Data Exchange (ETDEWEB)

    Jerman, I.; Mihelcic, M.; Orel, B. [National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); Verhovsek, D. [Cinkarna - METALURSKO KEMICNA INDUSTRIJA CELJE, d.d. Kidriceva 26, 3001 Celje (Slovenia); Kovac, J. [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia)

    2011-02-15

    Thickness insensitive spectrally selective (TISS) paint coatings based on black pigment (PK 3060, Ferro Company) dispersed in a fluoropolymeric resin binder (Lumiflon, Asahi Company, Japan) have recently been made without added aluminium flakes and their properties have been reported for the first time. In this study we investigated in more detail the effect of trisilanol isobutyl (IB{sub 7} T{sub 7}(OH){sub 3}) polyhedral oligomeric silsesquioxane (trisilanol POSS) on the surface modification of PK 3060 pigment. Infrared spectral analysis of the surface modified pigment particles provided firm evidence for the formation of a POSS layer on the surface of the pigment particles, substantiated by the corresponding TEM and Energy Dispersive X-ray Spectroscopy (EDXS) measurements of functionalized and as-received pigments. SEM micrographs of the diluted dispersions in fluoropolymeric resin binder revealed uniform distribution of pigment particles with an average size of {proportional_to}300 nm and the beneficial effect of the pigment functionalization was assessed from the measured spectral selectivity of coatings of various thicknesses. (author)

  10. Adhesion of nitrile rubber to UV-assisted surface chemical modified PET fabric, part II: Interfacial characterization of MDI grafted PET

    Energy Technology Data Exchange (ETDEWEB)

    Razavizadeh, Mahmoud; Jamshidi, Masoud, E-mail: mjamshidi@iust.ac.ir

    2016-08-30

    Highlights: • In this research UV-irradiated PET fabric was chemically modified. • The fabric at first carboxylated under UV irradiation using glutaric anhydride, then it was grafted using isocyanate (i.e. MDI). • The surface of the fabric was characterized before and after each treating satge. • The composite samples were prepared and tested for T-Peel test. The surfaces of the fabrics were surface characterized to understand. - Abstract: Fiber to rubber adhesion is an important subject in rubber industry. It is well known that surface treatment (i.e. physical, mechanical and chemical) is an effective method to improve interfacial bonding of fibers and/or fabrics to rubbers. UV irradiation is an effective method which has been used to increase fabric-rubber interfacial interactions. In this research UV assisted chemical modification of PET fabrics was used to increase PET to nitrile rubber (NBR) adhesion. Nitrile rubber is a perfect selection as fuel and oil resistant rubber. However it has weak bonding to PET fabric. For this purpose PET fabric was carboxylated under UV irradiation and then methylenediphenyl diisocyanate (MDI) was grafted on carboxylated PET. The chemical composition of the fabric before and after surface treatment was investigated by X-ray photoelectron spectroscopy (XPS). The sectional morphology of the experimental PET fibers and the interface between rubber compound and PET fabric was studied using scanning electron microscope (SEM). The morphology and structure of the product were analyzed by an energy dispersive X-ray spectrometer (EDX). FTIR-ATR and H NMR analysis were used to assess surface modifications on the PET irradiated fabrics.

  11. Interaction of NO2 with TiO2 surface under UV irradiation: measurements of the uptake coefficient

    Directory of Open Access Journals (Sweden)

    Y. Bedjanian

    2012-01-01

    Full Text Available The interaction of NO2 with TiO2 solid films was studied under UV irradiation using a low pressure flow reactor (1–10 Torr combined with a modulated molecular beam mass spectrometer for monitoring of the gaseous species involved. The NO2 to TiO2 reactive uptake coefficient was measured from the kinetics of NO2 loss on TiO2 coated Pyrex rods as a function of NO2 concentration, irradiance intensity (JNO2 = 0.002–0.012 s−1, relative humidity (RH = 0.06–69 %, temperature (T = 275–320 K and partial pressure of oxygen (0.001–3 Torr. TiO2 surface deactivation upon exposure to NO2 was observed. The initial uptake coefficient of NO2 on illuminated TiO2 surface (with 90 ppb of NO2 and JNO2≅0.006 s−1 was found to be γ0 = (1.2±0.4 ×10−4 (calculated using BET surface area under dry conditions at T = 300 K. The steady state uptake, γ, was several tens of times lower than the initial one, independent of relative humidity, and was found to decrease in the presence of molecular oxygen. In addition, it was shown that γ is not linearly dependent on the photon flux and seems to level off under atmospheric conditions. Finally, the following expression for γ was derived, γ = 2.3×10−3 exp(−1910/T/(1 + P0.36 (where P is O2 pressure in Torr, and recommended for atmospheric applications (for any RH, near 90 ppb of NO2 and JNO2 = 0.006 s−1.

  12. Surface Ionization State and Nanoscale Chemical Composition of UV-Irradiated Poly(dimethylsiloxane) Probed by Chemical Force Microscopy, Force Titration, and Electrokinetic Measurements

    NARCIS (Netherlands)

    Song, Jing; Duval, Jerome F.L.; Cohen Stuart, Martien A.; Hillborg, Henrik; Gunst, Ullrich; Arlinghaus, Heinrich F.; Vancso, G. Julius

    2007-01-01

    The surface chemistry and ionization state of cross-linked poly(dimethylsiloxane) (PDMS) exposed to UV/ozone were studied as a function of treatment time. Various complementary and independent experimental techniques were utilized, which yielded information on the macroscopic as well as the nanometr

  13. Surface ionization state and nanoscale chemical composition of UV-irradiated poly(dimethylsiloxane) probed by chemical force microscopy, force titration, and electrokinetic measurements

    NARCIS (Netherlands)

    Song, J.; Duval, J.F.L.; Cohen Stuart, M.A.; Hillborg, H.; Gunst, U.; Arlinghaus, H.F.; Vancso, G.J.

    2007-01-01

    The surface chemistry and ionization state of cross-linked poly(dimethylsiloxane) (PDMS) exposed to UV/ozone were studied as a function of treatment time. Various complementary and independent experimental techniques were utilized, which yielded information on the macroscopic as well as the nanometr

  14. Chemistry of NOx on TiO2 Surfaces Studied by Ambient Pressure XPS: Products, Effect of UV Irradiation, Water, and Coadsorbed K(.).

    Science.gov (United States)

    Rosseler, Olivier; Sleiman, Mohamad; Montesinos, V Nahuel; Shavorskiy, Andrey; Keller, Valerie; Keller, Nicolas; Litter, Marta I; Bluhm, Hendrik; Salmeron, Miquel; Destaillats, Hugo

    2013-02-07

    Self-cleaning surfaces containing TiO2 nanoparticles have been postulated to efficiently remove NOx from the atmosphere. However, UV irradiation of NOx adsorbed on TiO2 also was shown to form harmful gas-phase byproducts such as HONO and N2O that may limit their depolluting potential. Ambient pressure XPS was used to study surface and gas-phase species formed during adsorption of NO2 on TiO2 and subsequent UV irradiation at λ = 365 nm. It is shown here that NO3(-), adsorbed on TiO2 as a byproduct of NO2 disproportionation, was quantitatively converted to surface NO2 and other reduced nitrogenated species under UV irradiation in the absence of moisture. When water vapor was present, a faster NO3(-) conversion occurred, leading to a net loss of surface-bound nitrogenated species. Strongly adsorbed NO3(-) in the vicinity of coadsorbed K(+) cations was stable under UV light, leading to an efficient capture of nitrogenated compounds.

  15. A development and biological safety evaluation of novel PVC medical devices with surface structures modified by UV irradiation to suppress plasticizer migration.

    Science.gov (United States)

    Haishima, Yuji; Isama, Kazuo; Hasegawa, Chie; Yuba, Toshiyasu; Matsuoka, Atsuko

    2013-09-01

    This study examines the chemical, physicochemical, and biological properties of PVC sheets treated with UV irradiation on their surfaces to suppress the elution of a plasticizer, di-(2-ethylhexyl) phthalate (DEHP), for developing novel polyvinyl chloride (PVC) medical devices. The PVC sheets irradiated under conditions 1 (52.5 μW/cm(2), 136 J/cm(2)) and 2 (0.45 mW/cm(2), 972 J/cm(2)) exhibited considerable toxicity in cytotoxicity tests and chromosome aberration tests due to the generation of DEHP oxidants, but no toxicity was detected in the PVC sheet irradiated under condition 3 (8.3 mW/cm(2), 134 J/cm(2)). The release of DEHP from the surface irradiated under condition 3 was significantly suppressed, and mono-(2-ethylhexyl) phthalate (MEHP) converted from a portion of DEHP could be easily removed from the surface by washing with methanol. The physicochemical properties of the surface regarding the suppression of DEHP elution remained stable through all sterilizations tested, but MEHP elution was partially recrudesced by the sterilizations except for gamma irradiation. These results indicated that UV irradiation using a strong UV-source over a short time (condition 3) followed by methanol washing and gamma sterilization may be useful for preparing novel PVC products that did not elute plasticizers and do not exhibit toxicity originating from UV irradiation.

  16. Characterization of the Active Surface Species Responsible for UV-Induced Desorption of O2 from the Rutile TiO2(110) Surface

    Energy Technology Data Exchange (ETDEWEB)

    Henderson, Michael A.; Shen, Mingmin; Wang, Zhitao; Lyubinetsky, Igor

    2013-03-21

    We have examined the chemical and photochemical properties of molecular oxygen on the (110) surface of rutile TiO2 at 100 K using electron energy loss spectroscopy (EELS), photon stimulated desorption (PSD) and scanning tunneling microscopy (STM). Oxygen chemisorbs on the TiO2(110) surface at 100 K through charge transfer from surface Ti3+ sites. The charge transfer process is evident in EELS by a decrease in the intensity of the Ti3+ d-to-d transition in EELS at ~0.9 eV and formation of a new loss ~2.8 eV. Based on comparisons with the available homogeneous and heterogeneous literature for complexed/adsorbed O2, the species responsible for the 2.8 eV peak can be assigned to a surface peroxo (O2 2-) state of O2. This species was identified as the active form of adsorbed O2 on TiO2(110) for PSD. The adsorption site of this peroxo species was assigned to that of a regular five-cooridinated Ti4+ (Ti5c) site based on comparisons between the UV exposure dependent behavior of O2 in STM, PSD and EELS data. Assignment of the active form of adsorbed O2 to a peroxo species at normal Ti5c sites necessitates reevaluation of the simple mechanism in which a single valence band hole neutralizes a singly charged O2 species (superoxo or O2-) leading to desorption of O2 from a physisorbed potential energy surface. This work was supported by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences, and the Chemical Imaging Initiative at Pacific Northwest National Laboratory (PNNL), and was performed in the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE's Office of Biological and Environmental Research and located at PNNL.

  17. Insight to UV-induced formation of laser damage on LiB(3)O(5) optical surfaces during long-term sum-frequency generation.

    Science.gov (United States)

    Möller, S; Andresen, A; Merschjann, C; Zimmermann, B; Prinz, M; Imlau, M

    2007-06-11

    Microscopic investigations of UV-induced formation of laser damage on LiB(3)O(5) optical surfaces during long-term sum-frequency generation (SFG) uncovers a significant growth of a SiO(2)-amorphous layer spatially limited to the illuminated area. The layer gives rise to a catastrophic break-down of the LiB(3)O(5)-output surface upon long-term laser operation even at intensities far below the laser-induced damage threshold. The interaction of UV laser light, LiB(3)O(5) surface and foreign atoms in the ambient atmosphere is discussed in the frame of a two-step process for surface-damage formation.

  18. Laser-induced breakdown spectroscopy for on-line control of selective removal of cobalt binder from tungsten carbide hardmetal by pulsed UV laser surface ablation

    Science.gov (United States)

    Li, Tiejun; Lou, Qihong; Wei, Yunrong; Huang, Feng; Dong, Jingxing; Liu, Jingru

    2001-09-01

    Laser-induced breakdown spectroscopy (LIBS) was successfully used in on-line control of selective removal of cobalt from tungsten carbide hardmetal by pulsed UV laser surface ablation. The dependence of LIBS on number of laser shots was investigated at different laser fluences. The optimal laser fluence of 2.5 J/cm 2 suited for selective removal of cobalt from surface layer of hardmetal was confirmed. The result sample was also subject to different post-examinations to evaluate the feasibility of the application of LIBS in this laser ablation process. It was demonstrated that, monitoring of the emission intensity of cobalt lines could be used as a control parameter for selective removal of cobalt from surface layer of hardmetal by pulsed UV laser. The on-line implementation of the spectroscopic technique LIBS to the surface-ablation process provided important information about the optimal-ablation parameters.

  19. Impact of environmental factors on the spectral characteristics of lava surfaces:field spectrometry of basaltic lava flows on Tenerife, Canary Islands, Spain

    OpenAIRE

    Long Li; Carmen Solana; Frank Canters; Jonathan C.-W. Chan; Matthieu Kervyn

    2015-01-01

    We report on spectral reflectance measurements of basaltic lava flows on Tenerife Island, Spain. Lava flow surfaces of different ages, surface roughness and elevations were systematically measured using a field spectroradiometer operating in the range of 350–2500 nm. Surface roughness, oxidation and lichen coverage were documented at each measured site. Spectral properties vary with age and morphology of lava. Pre-historical lavas with no biological coverage show a prominent increase in spect...

  20. Areal-Averaged Spectral Surface Albedo from Ground-Based Transmission Data Alone: Toward an Operational Retrieval

    Directory of Open Access Journals (Sweden)

    Evgueni Kassianov

    2014-08-01

    Full Text Available We present here a simple retrieval of the areal-averaged spectral surface albedo using only ground-based measurements of atmospheric transmission under fully overcast conditions. Our retrieval is based on a one-line equation. The feasibility of our retrieval for routine determinations of albedo is demonstrated for different landscapes with various degrees of heterogeneity using three sets of measurements: (1 spectral atmospheric transmission from the Multi-Filter Rotating Shadowband Radiometer (MFRSR at five wavelengths (415, 500, 615, 673, and 870 nm; (2 tower-based measurements of local surface albedo at the same wavelengths; and (3 areal-averaged surface albedo at four wavelengths (470, 560, 670 and 860 nm from collocated and coincident Moderate Resolution Imaging Spectroradiometer (MODIS observations. These integrated datasets cover both temporally long (2008–2013 and short (April–May 2010 periods at the Atmospheric Radiation Measurement (ARM Southern Great Plains site and the National Oceanic and Atmospheric Administration (NOAA Table Mountain site, respectively. The calculated root mean square error (RMSE, defined here as the root mean squared difference between the MODIS-derived surface albedo and the retrieved areal-averaged albedo, is quite small (RMSE ≤ 0.015 and comparable with that obtained previously by other investigators for the shortwave broadband albedo. Good agreement between tower-based measurements of daily-averaged surface albedo for completely overcast and non-overcast conditions is also demonstrated.

  1. Characteristics of UV-MicroO3 Reactor and Its Application to Microcystins Degradation during Surface Water Treatment

    Directory of Open Access Journals (Sweden)

    Guangcan Zhu

    2015-01-01

    Full Text Available The UV-ozone (UV-O3 process is not widely applied in wastewater and potable water treatment partly for the relatively high cost since complicated UV radiation and ozone generating systems are utilized. The UV-microozone (UV-microO3, a new advanced process that can solve the abovementioned problems, was introduced in this study. The effects of air flux, air pressure, and air humidity on generation and concentration of O3 in UV-microO3 reactor were investigated. The utilization of this UV-microO3 reactor in microcystins (MCs degradation was also carried out. Experimental results indicated that the optimum air flux in the reactor equipped with 37 mm diameter quartz tube was determined to be 18∼25 L/h for efficient O3 generation. The air pressure and humidity in UV-microO3 reactor should be low enough in order to get optimum O3 output. Moreover, microcystin-RR, YR, and LR (MC-RR, MC-YR, and MC-LR could be degraded effectively by UV-microO3 process. The degradation of different MCs was characterized by first-order reaction kinetics. The pseudofirst-order kinetic constants for MC-RR, MC-YR, and MC-LR degradation were 0.0093, 0.0215, and 0.0286 min−1, respectively. Glucose had no influence on MC degradation through UV-microO3. The UV-microO3 process is hence recommended as a suitable advanced treatment method for dissolved MCs degradation.

  2. Optimization of spectral sensitivities of mosaic five-band camera for estimating chromophore densities from skin images including shading and surface reflections

    Science.gov (United States)

    Hirose, Misa; Akaho, Rina; Maita, Chikashi; Sugawara, Mai; Tsumura, Norimichi

    2016-06-01

    In this paper, the spectral sensitivities of a mosaic five-band camera were optimized using a numerical skin phantom to perform the separation of chromophore densities, shading and surface reflection. To simulate the numerical skin phantom, the spectral reflectance of skin was first calculated by Monte Carlo simulation of photon migration for different concentrations of melanin, blood and oxygen saturation levels. The melanin and hemoglobin concentration distributions used in the numerical skin phantom were obtained from actual skin images by independent component analysis. The calculated components were assigned as concentration distributions. The spectral sensitivities of the camera were then optimized using a nonlinear technique to estimate the spectral reflectance for skin separation. In this optimization, the spectral sensitivities were assumed to be normally distributed, and the sensor arrangement was identical to that of a conventional mosaic five-band camera. Our findings demonstrated that spectral estimation could be significantly improved by optimizing the spectral sensitivities.

  3. An evaluation of ultraviolet light (UV254) as a means to inactivate porcine reproductive and respiratory syndrome virus on common farm surfaces and materials.

    Science.gov (United States)

    Dee, Scott; Otake, Satoshi; Deen, John

    2011-05-12

    A study was conducted to assess the effect of UV(254) on the concentration and viability of PRRSV on surfaces and materials commonly encountered on swine farms. A standard quantity (5 × 10(6)TCID(50), total dose) of a PRRSV modified live vaccine virus was inoculated onto 2 matched sets of surfaces/materials including wood, plastic, latex, rubber, styrofoam, metal, leather, cloth, concrete, cardboard, glass and paper. One set was exposed to UV(254) radiation (treatments) and the other to incandescent light (controls) for a 24h period. During this time, treatments and controls were swabbed at 10 min intervals from 0 to 60 min post-inoculation (PI) and again at 24h PI. The quantity of PRRSV RNA on each item at each sampling time was calculated by RT-PCR and the presence of viable PRRSV in each sample was determined by swine bioassay. A significant reduction (p<0.0001) in the quantity of PRRSV RNA was demonstrated at 24h PI independent of treatment. In addition, a significant reduction (p=0.012) in the number of UV(254)-treated surfaces which harbored viable virus was observed at 60 min (0/12 positive) when compared to control surfaces (5/12 positive). In addition, all UV(254) treated samples collected between 10 and 50 min PI were bioassay negative. These results suggest that UV(254) is an effective means to inactivate PRRSV on commonly encountered farm surfaces and materials and inactivation can be accomplished following 10 min of exposure. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Spectroscopic follow-up of UV-excess objects selected from the UVEX survey

    CERN Document Server

    Verbeek, Kars; Scaringi, Simone; Napiwotzki, Ralf; Spikings, Ben; Østensen, Roy H; Drew, Janet; Steeghs, Danny; Casares, Jorge; Corral-Santana, Jesus M; Corradi, Romano; Deacon, Niall; Drake, Jeremy; Gansicke, Boris T; González-Solares, Eduardo; Greimel, Robert; Heber, Ulrich; Irwin, Mike; Knigge, Christian; Nelemans, Gijs

    2012-01-01

    We present the results of the first spectroscopic follow-up of 132 optically blue UV-excess sources selected from the UV-excess survey of the Northern Galactic Plane (UVEX). The UV-excess spectra are classified into different populations and grids of model spectra are fit to determine spectral types, temperatures, surface gravities and reddening. From this initial spectroscopic follow-up 95% of the UV-excess candidates turn out to be genuine UV-excess sources such as white dwarfs, white dwarf binaries, subdwarfs type O and B, emission line stars and QSOs. The remaining sources are classified as slightly reddened main-sequence stars with spectral types later than A0V. The fraction of DA white dwarfs is 47% with reddening smaller than E(B-V)17 and Galactic latitude smaller than |b|<4 compared to main-sequence stars, blue horizontal branch stars and subdwarfs.

  5. Initial analyses of surface spectral radiance between observations and Line-By-Line calculations

    Energy Technology Data Exchange (ETDEWEB)

    Brown, P.D.; Clough, S.A. [Atmospheric and Environmental Research, Inc., Cambridge, MA (United States); Miller, N.E.; Shippert, T.R.; Turner, D.D. [Pacific Northwest Lab., Richland, WA (United States)] [and others

    1996-04-01

    The evaluation an improvement of radiative transfer calculations are essential to attain improved performance of general circulation models (GCMs) for climate change applications. A Quality Measurement Experiment (QME) is being conducted to analyze the spectral residuals between the downwelling longwave radiance measured by the University of Wisconsin Atmospheric Emitted Radiance Interferometer (AERI) and spectral radiance calculated by the Line-By-Line Radiative Transfer Model (LBLRTM). The three critical components of this study are (1) the assessment of the quality of the high resolution AERI measurements, (2) the assessment of the ability to define the atmospheric state in the radiating column, and (3) the evaluation of the capability of LBLRTM. Validations have been performed on spectral radiance data, obtained from April 1994 through July 1994, through the analysis of the spectral interval and physical process. The results are archived as a function of time, enabling the retrieval of specific data and facilitating investigations and diurnal effects, seasonal effects, and longer-term trends. While the initial focus is restricted to clear-sky analyses, efforts are under way to include the effects of clouds and aerosols. Plans are well formulated for the extension of the current approach to the shortwave. An overview of the concept of the QME is described by Miller et al. (1994), and a detailed description of this study is provided by Clough et al. (1994).

  6. Maternal inhalation of surface-coated nanosized titanium dioxide (UV-Titan) in C57BL/6 mice

    DEFF Research Database (Denmark)

    Jackson, Petra; Halappanavar, Sabina; Hougaard, Karin Sorig

    2013-01-01

    We investigated effects of maternal pulmonary exposure to titanium dioxide (UV-Titan) on prenatally exposed offspring. Time-mated mice (C57BL/6BomTac) were inhalation exposed (1 h/day to 42 mg UV-Titan/m(3) aerosolised powder or filtered air) during gestation days (GDs) 8-18. We evaluated DNA str...

  7. UV-C light inactivation kinetics of Penicillium expansum on pear surfaces: Influence on physicochemical and sensory quality during storage

    Science.gov (United States)

    Postharvest quality and storage life of fresh pear are often limited by fungal growth caused by Penicillium expansum. Ultraviolet-C light (UV-C 254 nm) is a promising alternative disinfestation method to reduce fruit spoilage by fungi. In this study, UV-C inactivation kinetic data of Penicillium exp...

  8. Polymer surface modification using UV treatment for attachment of natamycin and the potential applications for conventional food cling wrap (LDPE)

    Science.gov (United States)

    Shin, Joongmin; Liu, Xiaojing; Chikthimmah, Naveen; Lee, Youn Suk

    2016-11-01

    The purpose of this study was to develop an active non-migratory antifungal Low Density Polyethylene (LDPE) polymer for use in food packaged applications. The functional acrylic acid monomer was grafted on the LDPE film surface by photo-initiated graft polymerization using Ultra Violet light irradiation (from 0 to 5 min). Natamycin, an antifungal agent, was applied to the treated film to bind with the pendent functional groups and were evaluated its performance against mold and yeast. The grafted amounts were determined by gravimetric measurement and dye absorbance. Attenuated Total Reflectance/Fourier Transfer Infrared Spectroscopy, scanning electron microscopy, mechanical strength test was used to characterize film properties. The antifungal efficacy of the film was evaluated with Saccharomyces cerevisiae and Penicillium chrysogenum on growth media and fresh cut cantaloupe. The amounts of the grafted group were increased with the longer ultraviolet exposure time. The amount of the grafted natamycin on the treated film was up to 49.87 μg/cm2, and the film inhibited mycelium formation of P. chrysogenum spores by over 60%. Due to the thickness of the film (less than 12.25 μm), long time UV exposure decrease the film's mechanical strength. The application of such non-migratory active packaging film represents a promising approach to maintaining food quality with reduced additive.

  9. Red-Shift Effects in Surface Enhanced Raman Spectroscopy: Spectral or Intensity Dependence of the Near-Field?

    KAUST Repository

    Colas, Florent

    2016-06-06

    Optimum amplification in Surface Enhanced Raman Scattering (SERS) from individual nanoantennas is expected when the excitation is slightly blue-shifted with respect to the Localized Surface Plasmon Resonance (LSPR), so that the LSPR peak falls in the middle between the laser and the Stokes Raman emission. Recent experiments have shown when moving the excitation from the visible to the near-infrared that this rule of thumb is no more valid. The excitation has to be red-shifted with respect to the LSPR peak, up to 80nm, to obtain highest SERS. Such discrepancy is usually attributed to a Near-Field (NF) to Far-Field (FF) spectral shift. Here we critically discuss this hypothesis for the case of gold nanocylinders. By combining multi-wavelength excitation SERS experiments with numerical calculations, we show that the red-shift of the excitation energy does not originate from a spectral shift between the extinction (FF) and the near-field distribution (NF), which is found to be not larger than 10nm. Rather, it can be accounted for by looking at the peculiar spectral dependence of the near-field intensity on the cylinders diameter, characterized by an initial increase, up to 180nm diameter, followed by a decrease and a pronounced skewness.

  10. An Impurity Emission Survey in the near UV and Visible Spectral Ranges of Electron Cyclotron Heated (ECH) Plasma in the TJ-II Stellarator

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, K. J.; Zurro, B.; Baciero, A.

    2001-07-01

    We report on a near-ultraviolet and visible spectroscopic survey (220-600 nm) of electron cyclotron resonance (ECR) heated plasmas created in the TJ-II stellarator, with central electron temperatures up to 2 keV and central electron densities up to 1.7 x 10 ''19 m''-3. Approximately 1200 lines from thirteen elements have been identified. The purpose of the work is to identify the principal impurities and spectral lines present in TJ-II plasmas, as well as their possible origin to search for transitions from highly ionised ions. This work will act as a base for identifying suitable transitions for following the evolution of impurities under different operating regimens and multiplet systems for line polarisation studies. It is intended to use the database creates as a spectral line reference for comparing spectra under different operating and plasma heating regimes. (Author)

  11. Spectral re-distribution and surface loss effects in Swift XRT (XMM-Newton EPIC) MOS CCDs

    CERN Document Server

    Short, A D; Turner, M J L

    2002-01-01

    In the course of testing and selecting the EPIC MOS CCDs for the XMM-Newton observatory, the developed a Monte-Carlo model of the CCD response. Among other things, this model was used to investigate surface loss effects evident at low energies. By fitting laboratory data, these losses were characterised as a simple function of X-ray interaction depth and this result enabled the spectral re-distribution itself to be modelled as a simple analytical function. Subsequently, this analytical function has been used to generate the response matrix for the EPIC MOS instruments and will now be employed to model the spectral re-distribution for the Swift XRT CCD.

  12. Observation of UV-induced Auger features in catechol adsorbed on anatase TiO{sub 2} (101) single crystal surface

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Andrew G. [School of Physics and Astronomy and Photon Science Institute, University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Syres, Karen L. [School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)

    2012-04-23

    We have investigated the electronic structure of catechol adsorbed on the anatase TiO{sub 2} (101) surface under illumination with ultraviolet (UV) light (4.75 eV) using resonant photoemission spectroscopy. UV illumination results in the appearance of a strong Ti MVV (M refers to photoionization of 3p level and VV the Auger decay process via the valence levels) feature at a kinetic energy of 26.2 eV. This is attributed to the creation of localised states following catechol to Ti-3d excitation by the UV source. A sharp resonance attributed to excitation from Ti 3p states into these localised states is observed in constant final state spectra.

  13. Fusion of spectral and shape features for identification of urban surface cover types using reflective and thermal hyperspectral data

    Science.gov (United States)

    Segl, K.; Roessner, S.; Heiden, U.; Kaufmann, H.

    The urban environment is characterized by an intense multifunctional use of available spaces, where the preservation of open green spaces is of special importance. For this purpose, area-wide urban biotope mapping based on CIR aerial photographs has been carried out for the large cities in Germany during the last 10 years. Because of dynamic urban development and high mapping costs, the municipal authorities are interested in effective methods for mapping urban surface cover types, which can be used for evaluation of ecological conditions in urban structures and supporting updates of biotope maps. Against this background, airborne hyperspectral remote sensing data of the DAIS 7915 instrument have been analyzed for a test site in the city of Dresden (Germany) with regard to their potential for automated material-oriented identification of urban surface cover types. Previous investigations have shown that the high spectral and spatial variabilities of these data require the development of special methods, which are capable of dealing with the resulting mixed-pixel problem in its specific characteristics in urban areas. Earlier, methodological developments led to an approach based on a combination of spectral classification and pixel-oriented unmixing techniques to facilitate sensible endmember selection based on the reflective bands of the DAIS instrument. This approach is now extended by a shape-based classification technique including the thermal bands of the DAIS instrument to improve the detection of buildings during the process of identifying seedling pixels, which represent the starting points for linear spectral unmixing. This new approach increases the reliability of differentiation between buildings and open spaces, leading to more accurate results for the spatial distribution of surface cover types. Thus, the new approach significantly enhances the exploitation of the information potential of the hyperspectral DAIS 7915 data for an area-wide identification

  14. Surface modification of poly(styrene-b-(ethylene-co-butylene)-b-styrene) elastomer via UV-induced graft polymerization of N-vinyl pyrrolidone.

    Science.gov (United States)

    Luan, Shifang; Zhao, Jie; Yang, Huawei; Shi, Hengchong; Jin, Jing; Li, Xiaomeng; Liu, Jingchuan; Wang, Jianwei; Yin, Jinghua; Stagnaro, Paola

    2012-05-01

    Poly(N-vinyl pyrrolidone) (PNVP) was covalently grafted onto the surface of biomedical poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) elastomer via a technique of UV-induced graft polymerization combined with plasma pre-treatment. The surface graft polymerization of N-vinyl pyrrolidone (NVP) was confirmed by ATR-FTIR and XPS. Effect of the parameters of graft polymerization, i.e., the initiator concentration, the UV irradiation time and the monomer concentration on the grafting density was investigated. The morphology and the wettability of the PNVP-modified surfaces were characterized by AFM and DSA, respectively. Protein adsorption and platelet adhesion were obviously suppressed after PNVP was grafted onto the SEBS substrates.

  15. Synthesis of trimethoprim metal complexes: Spectral, electrochemical, thermal, DNA-binding and surface morphology studies.

    Science.gov (United States)

    Demirezen, Nihat; Tarınç, Derya; Polat, Duygu; Ceşme, Mustafa; Gölcü, Ayşegül; Tümer, Mehmet

    2012-08-01

    Complexes of trimethoprim (TMP), with Cu(II), Zn(II), Pt(II), Ru(III) and Fe(III) have been synthesized. Then, these complexes have been characterized by spectroscopic techniques involving UV-vis, IR, mass and (1)H NMR. CHN elemental analysis, electrochemical and thermal behavior of complexes have also been investigated. The electrochemical properties of all complexes have been investigated by cyclic voltammetry (CV) using glassy carbon electrode. The biological activity of the complexes has been evaluated by examining their ability to bind to calf-thymus DNA (CT DNA) with UV spectroscopy and cyclic voltammetry. UV studies of the interaction of the complexes with DNA have shown that these compounds can bind to CT DNA. The binding constants of the complexes with CT DNA have also been calculated. The cyclic voltammograms of the complexes in the presence of CT DNA have shown that the complexes can bind to CT DNA by both the intercalative and the electrostatic binding mode. The antimicrobial activity of these complexes has been evaluated against three Gram-positive and four Gram-negative bacteria. Antifungal activity against two different fungi has been evaluated and compared with the reference drug TMP. Almost all types of complexes show excellent activity against all type of bacteria and fungi. The morphology of the CT DNA, TMP, metal ions and metal complexes has been investigated by scanning electron microscopy (SEM). To get the SEM images, the interaction of compounds with CT DNA has been studied by means of differential pulse voltammetry (DPV) at CT DNA modified pencil graphite electrode (PGE). The decrease in intensity of the guanine oxidation signals has been used as an indicator for the interaction mechanism.

  16. The Variability of Solar Spectral Irradiance and Solar Surface Indices Through the Solar Activity Cycles 21-23

    Science.gov (United States)

    Deniz Goker, Umit

    2016-07-01

    A study of variations of solar spectral irradiance (SSI) in the wavelength ranges 121.5 nm-300.5 nm for the period 1981-2009 is presented. We used various data for ultraviolet (UV) spectral lines and international sunspot number (ISSN) from interactive data centers as SME (NSSDC), UARS (GDAAC), SORCE (LISIRD) and SIDC, respectively. We developed a special software for extracting the data and reduced this data by using the MATLAB. In this respect, we revealed negative correlations of intensities of UV (289.5 nm-300.5 nm) emission lines originating in the solar chromosphere with the ISSN index during the unusually prolonged minimum between the solar cycles (SCs) 23 and 24. We also compared our results with the ground-based telescopes as Solar Irradiance Platform, Stanford Data (SFO), Kodaikanal Data (KKL) and NGDC Homepage (Rome and Learmonth Solar Observatories). We studied the variations of total solar irradiance (TSI), magnetic field, sunspots/sunspot groups, Ca II K-flux, faculae and plage areas data with these ground-based telescopes, respectively. We reduced the selected data using the Phyton programming language and plot with the IDL programme. Therefore, we found that there was a decrease in the area of bright faculae and chromospheric plages while the percentage of dark faculae and plage decrease, as well. However, these decreases mainly occurred in small sunspots, contrary to this, these terms in large sunspot groups were comparable to previous SCs or even larger. Nevertheless, negative correlations between ISSN and SSI data indicate that these emissions are in close connection with the classes of sunspots/sunspot groups and "PLAGE" regions. Finally, we applied the time series of the chemical elements correspond to the wavelengths 121.5 nm-300.5 nm and compared with the ISSN data. We found an unexpected increasing in the 298.5 nm for the Fe II element. The variability of Fe II (298.5 nm) is in close connection with the plage regions and the sizes of the

  17. [The design and implementation of the web typical surface object spectral information system in arid areas based on .NET and SuperMap].

    Science.gov (United States)

    Xia, Jun; Tashpolat, Tiyip; Zhang, Fei; Ji, Hong-jiang

    2011-07-01

    The characteristic of object spectrum is not only the base of the quantification analysis of remote sensing, but also the main content of the basic research of remote sensing. The typical surface object spectral database in arid areas oasis is of great significance for applied research on remote sensing in soil salinization. In the present paper, the authors took the Ugan-Kuqa River Delta Oasis as an example, unified .NET and the SuperMap platform with SQL Server database stored data, used the B/S pattern and the C# language to design and develop the typical surface object spectral information system, and established the typical surface object spectral database according to the characteristics of arid areas oasis. The system implemented the classified storage and the management of typical surface object spectral information and the related attribute data of the study areas; this system also implemented visualized two-way query between the maps and attribute data, the drawings of the surface object spectral response curves and the processing of the derivative spectral data and its drawings. In addition, the system initially possessed a simple spectral data mining and analysis capabilities, and this advantage provided an efficient, reliable and convenient data management and application platform for the Ugan-Kuqa River Delta Oasis's follow-up study in soil salinization. Finally, It's easy to maintain, convinient for secondary development and practically operating in good condition.

  18. New metal based drugs: Spectral, electrochemical, DNA-binding, surface morphology and anticancer activity properties

    Science.gov (United States)

    Çeşme, Mustafa; Gölcü, Aysegul; Demirtaş, Ibrahim

    2015-01-01

    The NSAID piroxicam (PRX) drug was used for complex formation reactions with Cu(II), Zn(II) and Pt(II) metal salts have been synthesized. Then, these complexes have been characterized by spectroscopic and analytical techniques. Thermal behavior of the complexes were also investigated. The electrochemical properties of all complexes have been investigated by cyclic voltammetry (CV) using glassy carbon electrode. The biological activity of the complexes has been evaluated by examining their ability to bind to fish sperm double strand DNA (FSFSdsDNA) with UV spectroscopy. UV studies of the interaction of the PRX and its complexes with FSdsDNA have shown that these compounds can bind to FSdsDNA. The binding constants of the compounds with FSdsDNA have also been calculated. The morphology of the FSdsDNA, PRX, metal ions and metal complexes has been investigated by scanning electron microscopy (SEM). To get the SEM images, the interaction of compounds with FSdsDNA has been studied by means of differential pulse voltammetry (DPV) at FSdsDNA modified pencil graphite electrode (PGE). The decrease in intensity of the guanine oxidation signals has been used as an indicator for the interaction mechanism. The effect of proliferation PRX and complexes were examined on the HeLA and C6 cells using real-time cell analyzer with four different concentrations.

  19. Effects of urban agglomeration on surface-UV doses: a comparison of Brewer measurements in Warsaw and Belsk, Poland, for the period 2013-2015

    Science.gov (United States)

    Czerwińska, Agnieszka E.; Krzyścin, Janusz W.; Jarosławski, Janusz; Posyniak, Michał

    2016-11-01

    Specific aerosols and cloud properties over large urban regions seem to generate an island, similar to the well-known urban heat island, leading to lower ultraviolet (UV) radiation intensity compared to the surrounding less polluted areas, thus creating a shield against excessive human exposure to UV radiation. The present study focuses on differences between erythemal and UVA (324 nm) doses measured by the Brewer spectrophotometers in Warsaw (52.3° N, 21.0° E) and Belsk (51.8° N, 20.8° E). The latter is a rural region located about 60 km south-west of the city. Ratios between erythemal and UVA partly daily doses, obtained during all-sky and cloudless-sky conditions for the period May 2013-December 2015, were analysed to infer a specific cloud and aerosol forcing on the surface UV doses over Warsaw. Radiative model simulations were carried out to find sources of the observed differences between the sites. It was found that Warsaw urban agglomeration induced 8 and 6 % attenuation of the erythemal and UVA doses respectively. This is mostly due to the lower sun elevation in Warsaw during the near-noon measurements and the larger optical depth of the city aerosols and increased cloudiness. It could be hypothesised that the expected stronger absorption of the solar UV radiation by urban aerosols is compensated for here by a higher surface reflectivity over the city.

  20. On the role of localized surface plasmon resonance in UV-Vis light irradiated Au/TiO₂ photocatalysis systems: pros and cons.

    Science.gov (United States)

    Lin, Zhongjin; Wang, Xiaohong; Liu, Jun; Tian, Zunyi; Dai, Loucheng; He, Beibei; Han, Chao; Wu, Yigui; Zeng, Zhigang; Hu, Zhiyu

    2015-03-07

    The role of localized surface plasmon resonance (LSPR) in UV-Vis light irradiated Au/TiO2 photocatalysis systems has been investigated, and it is demonstrated experimentally for the first time that both pros and cons of LSPR exist simultaneously for this photocatalytic reaction. We have proved that when operating under mixed UV and green light irradiation, the LSPR injected hot electrons (from the Au nanoparticles to TiO2 under green light irradiation) may surmount the Schottky barrier (SB) formed between the Au nanoparticles and TiO2, and flow back into the TiO2. As a result, these electrons may compensate for and even surpass those transferred from TiO2 to the Au nanoparticles, thus accelerating the recombination of UV excited electron-hole pairs in TiO2. This is the negative effect of LSPR. On the other hand, more hot electrons existing on the surface of the Au nanoparticles due to LSPR would favor the photocatalytic reaction, which accompanied by the negative effect dominates the overall photocatalytic performance. The presented results reveal the multi-faceted essence of LSPR in Au/TiO2 structures, and is instructive for the application of metal-semiconductor composites in photocatalysis. Moreover, it is confirmed that the extent to which the above pros and cons of LSPR dominate the overall photocatalytic reaction depends on the intensity ratio of visible to UV light.

  1. Simultaneous physical retrieval of surface emissivity spectrum and atmospheric parameters from infrared atmospheric sounder interferometer spectral radiances.

    Science.gov (United States)

    Masiello, Guido; Serio, Carmine

    2013-04-10

    The problem of simultaneous physical retrieval of surface emissivity, skin temperature, and temperature, water-vapor, and ozone atmospheric profiles from high-spectral-resolution observations in the infrared is formulated according to an inverse problem with multiple regularization parameters. A methodology has been set up, which seeks an effective solution to the inverse problem in a generalized L-curve criterion framework. The a priori information for the surface emissivity is obtained on the basis of laboratory data alone, and that for the atmospheric parameters by climatology or weather forecasts. To ensure that we deal with a problem of fewer unknowns than observations, the dimensionality of the emissivity is reduced through expansion in Fourier series. The main objective of this study is to demonstrate the simultaneous retrieval of emissivity, skin temperature, and atmospheric parameters with a two-dimensional L-curve criterion. The procedure has been demonstrated with spectra observed from the infrared atmospheric sounder interferometer, flying onboard the European Meteorological Operational satellite. To check the quality and reliability of the methodology, we have used spectra recorded over regions characterized by known or stable emissivity. These include sea surface, for which effective emissivity models are known, and arid lands (Sahara and Namib Deserts) that are known to exhibit the characteristic spectral signature of quartz-rich sand.

  2. UV-curable nanocomposite based on methacrylic-siloxane resin and surface-modified TiO2 nanocrystals.

    Science.gov (United States)

    Ingrosso, Chiara; Esposito Corcione, Carola; Striani, Raffaella; Comparelli, Roberto; Striccoli, Marinella; Agostiano, Angela; Curri, M Lucia; Frigione, Mariaenrica

    2015-07-22

    A novel UV-light-curable nanocomposite material formed of a methacrylic-siloxane resin loaded with 1 wt % oleic acid and 3-(trimethoxysilyl)propyl methacrylate silane (OLEA/MEMO)-coated TiO2 nanorods (NRs) has been manufactured as a potential self-curing structural coating material for protection of monuments and artworks, optical elements, and dental components. OLEA-coated TiO2 NRs, presynthesized by a colloidal chemistry route, have been surface-modified by a treatment with the methacrylic-based silane coupling agent MEMO. The resulting OLEA/MEMO-capped TiO2 NRs have been dispersed in MEMO; that is a monomer precursor of the organic formulation, used as a "common solvent" for transferring the NRs in prepolymer components of the formulation. Differential scanning calorimetry and Fourier transform infrared spectroscopy have allowed investigation of the effects of the incorporation of the OLEA/MEMO-capped TiO2 NRs on reactivity and photopolymerization kinetics of the nanocomposite, demonstrating that the embedded NRs significantly increase curing reactivity of the neat organic formulation both in air and inert atmosphere. Such a result has been explained on the basis of the photoactivity of the nanocrystalline TiO2 which behaves as a free-radical donor photocatalyst in the curing reaction, finally turning out more effective than the commonly used commercial photoinitiator. Namely, the NRs have been found to accelerate the cure rate and increase cross-linking density, promoting multiple covalent bonds between the resin prepolymers and the NR ligand molecules, and, moreover, they limit inhibition effect of oxygen on photopolymerization. The NRs distribute uniformly in the photocurable matrix, as assessed by transmission electron microscopy analysis, and increase glass transition temperature and water contact angle of the nanocomposite with respect to the neat resin.

  3. In situ deposition of graphene nanosheets on wood surface by one-pot hydrothermal method for enhanced UV-resistant ability

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Caichao, E-mail: wancaichaojy@163.com; Jiao, Yue, E-mail: yjiao123@126.com; Li, Jian, E-mail: lijiangroup@tom.com

    2015-08-30

    Graphical abstract: - Highlights: • The graphene/wood nanocomposites were fabricated via a mild fast one-pot hydrothermal method. • Graphene nanosheets were in situ deposited on the surface of the wood matrix. • The incorporation of graphene nanosheets results in the improvement in the thermal stability of the graphene/wood. • The graphene/wood exhibits superior UV resistance performance. - Abstract: Graphene nanosheets were successfully in situ deposited on the surface of the wood matrix via a mild fast one-pot hydrothermal method, and the resulting hybrid graphene/wood (GW) were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Raman spectroscopy, and thermogravimetric analysis (TGA). According to the results, the wood matrix was evenly coated by dense uninterrupted multilayer graphene membrane structure, which was formed by layer-by-layer self-assembly of graphene nanosheets. Meanwhile, the graphene coating also induced significant improvement in the thermal stability of GW in comparison with that of the original wood (OW). Accelerated weathering tests were employed to measure and determine the UV-resistant ability of OW and GW. After about six hundred hours of experiments, the surface color change of GW was much less than that of OW; besides, the Fourier transform infrared spectroscopy (FTIR) analysis also proved the less significant changes in surface chemical compositions of GW. The results both indicated that the graphene coating effectively protected wood surface from UV damage. Therefore, this class of GW composite might be expected to be served as high-performance wooden building material for outdoor or some particular harsh environments like strong UV radiation regions use.

  4. TL and OSL dose response and stability properties of various commercially glass samples obtained from Turkey for dosimetric purposes in the UV emission spectral region.

    Science.gov (United States)

    Şahiner, Eren

    2017-10-01

    This paper reports Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) dose response characteristics of ten different commercial glass samples collected from Turkey. Nowadays, glass samples are widely used mostly in objects of everyday life. The study focuses to both TL and OSL dose responses, through a dose region within 1 and 512Gy. Lowest detectable dose limit (LDDL) as well as the respective linearity features of the corresponding dose response curves were studied for both TL and OSL. Moreover, signal reproducibility and fading behaviors have also been studied in detail. For specific samples, the lowest detectable dose was yielded at 2Gy, making thus these samples appropriate for retrospective dosimetry applications. Nevertheless, based on the features reported in the present study, the majority of the samples could be possibly used effectively for dosimetric applications of higher doses in the UV region emission. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Spectral analysis of atmospheric composition: application to surface ozone model-measurement comparisons

    Science.gov (United States)

    Bowdalo, Dene R.; Evans, Mathew J.; Sofen, Eric D.

    2016-07-01

    Models of atmospheric composition play an essential role in our scientific understanding of atmospheric processes and in providing policy strategies to deal with societally relevant problems such as climate change, air quality, and ecosystem degradation. The fidelity of these models needs to be assessed against observations to ensure that errors in model formulations are found and that model limitations are understood. A range of approaches are necessary for these comparisons. Here, we apply a spectral analysis methodology for this comparison. We use the Lomb-Scargle periodogram, a method similar to a Fourier transform, but better suited to deal with the gapped data sets typical of observational data. We apply this methodology to long-term hourly ozone observations and the equivalent model (GEOS-Chem) output. We show that the spectrally transformed observational data show a distinct power spectrum with regimes indicative of meteorological processes (weather, macroweather) and specific peaks observed at the daily and annual timescales together with corresponding harmonic peaks at one-half, one-third, etc., of these frequencies. Model output shows corresponding features. A comparison between the amplitude and phase of these peaks introduces a new comparison methodology between model and measurements. We focus on the amplitude and phase of diurnal and seasonal cycles and present observational/model comparisons and discuss model performance. We find large biases notably for the seasonal cycle in the mid-latitude Northern Hemisphere where the amplitudes are generally overestimated by up to 16 ppbv, and phases are too late on the order of 1-5 months. This spectral methodology can be applied to a range of model-measurement applications and is highly suitable for Multimodel Intercomparison Projects (MIPs).

  6. Herschel/HIFI spectral line survey of the Orion Bar. Temperature and density differentiation near the PDR surface

    Science.gov (United States)

    Nagy, Z.; Choi, Y.; Ossenkopf-Okada, V.; van der Tak, F. F. S.; Bergin, E. A.; Gerin, M.; Joblin, C.; Röllig, M.; Simon, R.; Stutzki, J.

    2017-02-01

    Context. Photon dominated regions (PDRs) are interfaces between the mainly ionized and mainly molecular material around young massive stars. Analysis of the physical and chemical structure of such regions traces the impact of far-ultraviolet radiation of young massive stars on their environment. Aims: We present results on the physical and chemical structure of the prototypical high UV-illumination edge-on Orion Bar PDR from an unbiased spectral line survey with a wide spectral coverage which includes lines of many important gas coolants such as [Cii], [Ci], and CO and other key molecules such as H2CO, H2O, HCN, HCO+, and SO. Methods: A spectral scan from 480-1250 GHz and 1410-1910 GHz at 1.1 MHz resolution was obtained by the HIFI instrument on board the Herschel Space Observatory. We obtained physical parameters for the observed molecules. For molecules with multiple transitions we used rotational diagrams to obtain excitation temperatures and column densities. For species with a single detected transition we used an optically thin LTE approximation. In the case of species with available collisional rates, we also performed a non-LTE analysis to obtain kinetic temperatures, H2 volume densities, and column densities. Results: About 120 lines corresponding to 29 molecules (including isotopologues) have been detected in the Herschel/HIFI line survey, including 11 transitions of CO, 7 transitions of 13CO, 6 transitions of C18O, 10 transitions of H2CO, and 6 transitions of H2O. The rotational temperatures are in the range between 22 and 146 K and the column densities are in the range between 1.8 × 1012 cm-2 and 4.5 × 1017 cm-2. For species with at least three detected transitions and available collisional excitation rates we derived a best fit kinetic temperature and H2 volume density. Most species trace kinetic temperatures in the range between 100 and 150 K and H2 volume densities in the range between 105 and 106 cm-3. The species with temperatures and

  7. Adaption of the MODIS aerosol retrieval algorithm using airborne spectral surface reflectance measurements over urban areas: a case study

    Science.gov (United States)

    Jäkel, E.; Mey, B.; Levy, R.; Gu, X.; Yu, T.; Li, Z.; Althausen, D.; Heese, B.; Wendisch, M.

    2015-12-01

    MODIS (MOderate-resolution Imaging Spectroradiometer) retrievals of aerosol optical depth (AOD) are biased over urban areas, primarily because the reflectance characteristics of urban surfaces are different than that assumed by the retrieval algorithm. Specifically, the operational "dark-target" retrieval is tuned towards vegetated (dark) surfaces and assumes a spectral relationship to estimate the surface reflectance in blue and red wavelengths. From airborne measurements of surface reflectance over the city of Zhongshan, China, were collected that could replace the assumptions within the MODIS retrieval algorithm. The subsequent impact was tested upon two versions of the operational algorithm, Collections 5 and 6 (C5 and C6). AOD retrieval results of the operational and modified algorithms were compared for a specific case study over Zhongshan to show minor differences between them all. However, the Zhongshan-based spectral surface relationship was applied to a much larger urban sample, specifically to the MODIS data taken over Beijing between 2010 and 2014. These results were compared directly to ground-based AERONET (AErosol RObotic NETwork) measurements of AOD. A significant reduction of the differences between the AOD retrieved by the modified algorithms and AERONET was found, whereby the mean difference decreased from 0.27±0.14 for the operational C5 and 0.19±0.12 for the operational C6 to 0.10±0.15 and -0.02±0.17 by using the modified C5 and C6 retrievals. Since the modified algorithms assume a higher contribution by the surface to the total measured reflectance from MODIS, consequently the overestimation of AOD by the operational methods is reduced. Furthermore, the sensitivity of the MODIS AOD retrieval with respect to different surface types was investigated. Radiative transfer simulations were performed to model reflectances at top of atmosphere for predefined aerosol properties. The reflectance data were used as input for the retrieval methods. It

  8. Estimation of spectral solar radiation based on global insolation and characteristics of spectral solar radiation on a tilt surface; Zenten nissharyo ni motozuku zenten nissha supekutoru no suitei to keishamen bunko tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Baba, H.; Kanayama, K.; Endo, N.; Koromohara, K.; Takayama, H. [Kitami Institute of Technology, Hokkaido (Japan)

    1996-10-27

    Use of global insolation for estimating the corresponding spectral distribution is proposed. Measurements of global insolation spectrum throughout a year were compiled for clear days and cloudy days, ranked by 100W/m{sup 2}, for the clarification of spectral distribution. Global insolation quantity for a clear day was subject mainly to sun elevation. The global insolation spectral distribution with the sun elevation not lower than 15{degree} was similar to Bird`s model. Under the cloudy sky, energy density was lower in the region of wavelengths longer than the peak wavelength of 0.46{mu}m, and the distribution curve was sharper than that under the clear sky. Values given by Bird`s model were larger than measured values in the wavelength range of 0.6-1.8{mu}m, which was attributed to absorption by vapor. From the standard spectral distribution charts for the clear sky and cloudy sky, and from the dimensionless spectral distributions obtained by dividing them by the peak values, spectral distributions could be estimated of insolation quantities for the clear sky, cloudy sky, etc. As for the characteristics of spectral solar radiation on a tilt surface obtained from Bird`s model, they agreed with actually measured values at an angle of inclination of 60{degree} or smaller. 6 refs., 10 figs., 1 tab.

  9. Effect of emissivity uncertainty on surface temperature retrieval over urban areas: Investigations based on spectral libraries

    NARCIS (Netherlands)

    Chen, F.; Yang, S.; Su, Zhongbo; Wang, K.

    2016-01-01

    Land surface emissivity (LSE) is a prerequisite for retrieving land surface temperature (LST) through single channel methods. According to error model, a 0.01 (1%) uncertainty of LSE may result in a 0.5 K error in LST under a moderate condition, while an obvious error (approximately 1 K) is possible

  10. Measuring and modeling the effect of surface moisture on the spectral reflectance of coastal beach sand

    NARCIS (Netherlands)

    Nolet, Corjan; Poortinga, Ate; Roosjen, Peter; Bartholomeus, Harm; Ruessink, Gerben

    2014-01-01

    Surface moisture is an important supply limiting factor for aeolian sand transport, which is the primary driver of coastal dune development. As such, it is critical to account for the control of surface moisture on available sand for dune building. Optical remote sensing has the potential to measure

  11. Retrieval of Areal-averaged Spectral Surface Albedo from Transmission Data Alone: Computationally Simple and Fast Approach

    Energy Technology Data Exchange (ETDEWEB)

    Kassianov, Evgueni I.; Barnard, James C.; Flynn, Connor J.; Riihimaki, Laura D.; Michalsky, Joseph; Hodges, G. B.

    2014-10-25

    We introduce and evaluate a simple retrieval of areal-averaged surface albedo using ground-based measurements of atmospheric transmission alone at five wavelengths (415, 500, 615, 673 and 870nm), under fully overcast conditions. Our retrieval is based on a one-line semi-analytical equation and widely accepted assumptions regarding the weak spectral dependence of cloud optical properties, such as cloud optical depth and asymmetry parameter, in the visible and near-infrared spectral range. To illustrate the performance of our retrieval, we use as input measurements of spectral atmospheric transmission from Multi-Filter Rotating Shadowband Radiometer (MFRSR). These MFRSR data are collected at two well-established continental sites in the United States supported by the U.S. Department of Energy’s (DOE’s) Atmospheric Radiation Measurement (ARM) Program and National Oceanic and Atmospheric Administration (NOAA). The areal-averaged albedos obtained from the MFRSR are compared with collocated and coincident Moderate Resolution Imaging Spectroradiometer (MODIS) white-sky albedo. In particular, these comparisons are made at four MFRSR wavelengths (500, 615, 673 and 870nm) and for four seasons (winter, spring, summer and fall) at the ARM site using multi-year (2008-2013) MFRSR and MODIS data. Good agreement, on average, for these wavelengths results in small values (≤0.01) of the corresponding root mean square errors (RMSEs) for these two sites. The obtained RMSEs are comparable with those obtained previously for the shortwave albedos (MODIS-derived versus tower-measured) for these sites during growing seasons. We also demonstrate good agreement between tower-based daily-averaged surface albedos measured for “nearby” overcast and non-overcast days. Thus, our retrieval originally developed for overcast conditions likely can be extended for non-overcast days by interpolating between overcast retrievals.

  12. Mapping Chemical and Structural Composition of Pharmaceutical and Biological Samples by Raman, Surface-Enhanced Raman and Fluorescence Spectral Imaging

    Science.gov (United States)

    Chourpa, Igor; Cohen-Jonathan, Simone; Dubois, Pierre

    Raman spectroscopy is an analytical technique recognised for its structural and conformational specificity. The efficient discrimination of molecular species by Raman is particularly potent for multidimensional microscopic imaging of complex biological environment, as demonstrated in the present book. The commonly admitted problem of Raman, low sensitivity, can often be circumvented due to high output instruments and via approaches like RRS (resonance Raman scattering), SERS (surface-enhanced Raman scattering), TERS (tip-enhanced Raman scattering) or CARS (coherent anti-Stokes Raman scattering). In contrast to the latter, RRS and SERS are realizable with less sophisticated set-up based on common Raman systems. Although more invasive than RRS, SERS provides better sensitivity and quenching of fluorescence. SERRS (surface-enhanced resonance Raman scattering) spectroscopy can be used in coupling with fluorescence and competes in selectivity and sensitivity with spectrofluorimetry. In the chapter below, we use recent applications made in our group to illustrate the use of Raman and SERRS spectral imaging for characterization of biological samples (animal subcutaneous tissue, human cancer cells) and pharmaceutical samples (microparticles for drug delivery, fibres for wound dressing). After a brief description of experimental details on spectral imaging, the chapter will focus on results concerning (i) biocompatible pharmaceutical materials made of alginates and (ii) anticancer drugs in pharmaceutical forms and in biological systems.

  13. Gel Based Sunscreen Containing Surface Modified TiO2 Obtained by Sol-Gel Process: Proposal for a Transparent UV Inorganic Filter

    Directory of Open Access Journals (Sweden)

    Marina Paiva Abuçafy

    2016-01-01

    Full Text Available Inorganic UV filters, as titanium dioxide (TiO2, have become attractive because of their role in protecting the skin against the damage caused by the continuous exposure to the sun. However, their high refractive index, responsible for a white residue when applied on the skin, has led to the development of alternative inorganic materials, such as TiO2 nanoparticles. Thus, the aim of this study was the development of transparent and stable gel formulations containing surface modified TiO2 nanoparticles for application in sunscreens. Also, the physical and chemical properties of formulations containing TiO2 nanoparticles were evaluated. The UV absorption spectroscopy analyses indicated that the formulations containing TiO2 nanoparticles had a broad protection spectrum. The diffuse reflectance spectroscopy revealed that the use of PTSH surface modified TiO2 nanoparticles improved the transparency of the sunscreen formulations compared to that containing commercial ones. The rheology analyses showed that the amount of nanoparticles incorporated in the formulations influences the gel-like or liquid-like behavior. The results showed that the surface modified TiO2 nanoparticles are a promising innovative UV filter and the formulations containing these nanoparticles are interesting candidates for being used as sunscreen.

  14. UVolution, a Photochemistry Experiment in Low Earth Orbit: Investigation of the Photostability of Carboxylic Acids Exposed to Mars Surface UV Radiation Conditions

    Science.gov (United States)

    Stalport, Fabien; Guan, Yuan Yong; Coll, Patrice; Szopa, Cyril; Macari, Frédérique; Raulin, François; Chaput, Didier; Cottin, Hervé

    2010-05-01

    The detection and identification of organic molecules on Mars are of prime importance to establish the existence of a possible ancient prebiotic chemistry or even a biological activity. To date, however, no complex organic compounds have been detected on Mars. The harsh environmental conditions at the surface of Mars are commonly advocated to explain this nondetection, but few studies have been implemented to test this hypothesis. To investigate the nature, abundance, and stability of organic molecules that could survive under such environmental conditions, we exposed, in low Earth orbit, organic molecules of martian astrobiological relevance to solar UV radiation (>200 nm). The experiment, called UVolution, was flown on board the Biopan ESA module, which was situated outside a Russian Foton automated capsule and exposed to space conditions for 12 days in September 2007. The targeted organic molecules [α-aminoisobutyric acid (AIB), mellitic acid, phthalic acid, and trimesic acid] were exposed with, and without, an analogous martian soil. Here, we present experimental results of the impact of solar UV radiation on the targeted molecules. Our results show that none of the organic molecules studied seemed to be radiotolerant to the solar UV radiation when directly exposed to it. Moreover, the presence of a mineral matrix seemed to increase the photodestruction rate. AIB, mellitic acid, phthalic acid, and trimesic acid should not be considered as primary targets for in situ molecular analyses during future surface missions if samples are only collected from the first centimeters of the top surface layer.

  15. Adhesion of nitrile rubber to UV-assisted surface chemical modified PET fabric, part II: Interfacial characterization of MDI grafted PET

    Science.gov (United States)

    Razavizadeh, Mahmoud; Jamshidi, Masoud

    2016-08-01

    Fiber to rubber adhesion is an important subject in rubber industry. It is well known that surface treatment (i.e. physical, mechanical and chemical) is an effective method to improve interfacial bonding of fibers and/or fabrics to rubbers. UV irradiation is an effective method which has been used to increase fabric-rubber interfacial interactions. In this research UV assisted chemical modification of PET fabrics was used to increase PET to nitrile rubber (NBR) adhesion. Nitrile rubber is a perfect selection as fuel and oil resistant rubber. However it has weak bonding to PET fabric. For this purpose PET fabric was carboxylated under UV irradiation and then methylenediphenyl diisocyanate (MDI) was grafted on carboxylated PET. The chemical composition of the fabric before and after surface treatment was investigated by X-ray photoelectron spectroscopy (XPS). The sectional morphology of the experimental PET fibers and the interface between rubber compound and PET fabric was studied using scanning electron microscope (SEM). The morphology and structure of the product were analyzed by an energy dispersive X-ray spectrometer (EDX). FTIR-ATR and H NMR analysis were used to assess surface modifications on the PET irradiated fabrics.

  16. Inactivation of hepatitis A virus and norovirus surrogate in suspension and on food-contact surfaces using pulsed UV light (pulsed light inactivation of food-borne viruses).

    Science.gov (United States)

    Jean, Julie; Morales-Rayas, Rocío; Anoman, Marie-Natacha; Lamhoujeb, Safaa

    2011-05-01

    This study was conducted to evaluate the inactivation of murine norovirus (MNV-1) and hepatitis A virus (HAV) by pulsed ultraviolet (UV) light. MNV-1 was used as a model for human norovirus. Viral suspensions of about 10(6) PFU/ml were exposed to pulses of UV light for different times and at different distances in a Xenon Steripulse device (model RS-3000C). Inactivation studies were also carried out on 1-cm(2) stainless steel and polyvinyl chloride disks with 10(5) PFU/ml. Inactivation of MNV-1 and HAV at 10.5 cm from the UV source was greater on inert surfaces than in suspension. The presence of organic matter (fetal bovine serum) reduced the effectiveness of pulsed light both in suspension and on surfaces. However, 2-s treatment in the absence of FBS completely inactivated (5 log reduction) the viral load at different distances tested, whether in suspension (MNV-1) or on disks (MNV-1 and HAV). The same treatment in the presence of fetal bovine serum (5%) allowed a reduction of about 3 log. This study showed that short duration pulses represent an excellent alternative for inactivation of food-borne viruses. This technology could be used to inactivate viruses in drinking water or on food-handling surfaces. Copyright © 2010 Elsevier Ltd. All rights reserved.

  17. UVolution, a photochemistry experiment in low earth orbit: investigation of the photostability of carboxylic acids exposed to mars surface UV radiation conditions.

    Science.gov (United States)

    Stalport, Fabien; Guan, Yuan Yong; Coll, Patrice; Szopa, Cyril; Macari, Frédérique; Raulin, François; Chaput, Didier; Cottin, Hervé

    2010-05-01

    The detection and identification of organic molecules on Mars are of prime importance to establish the existence of a possible ancient prebiotic chemistry or even a biological activity. To date, however, no complex organic compounds have been detected on Mars. The harsh environmental conditions at the surface of Mars are commonly advocated to explain this nondetection, but few studies have been implemented to test this hypothesis. To investigate the nature, abundance, and stability of organic molecules that could survive under such environmental conditions, we exposed, in low Earth orbit, organic molecules of martian astrobiological relevance to solar UV radiation (>200 nm). The experiment, called UVolution, was flown on board the Biopan ESA module, which was situated outside a Russian Foton automated capsule and exposed to space conditions for 12 days in September 2007. The targeted organic molecules [alpha-aminoisobutyric acid (AIB), mellitic acid, phthalic acid, and trimesic acid] were exposed with, and without, an analogous martian soil. Here, we present experimental results of the impact of solar UV radiation on the targeted molecules. Our results show that none of the organic molecules studied seemed to be radiotolerant to the solar UV radiation when directly exposed to it. Moreover, the presence of a mineral matrix seemed to increase the photodestruction rate. AIB, mellitic acid, phthalic acid, and trimesic acid should not be considered as primary targets for in situ molecular analyses during future surface missions if samples are only collected from the first centimeters of the top surface layer.

  18. Modeling and Predicting the Effect of Surface Oxidation on the Normal Spectral Emissivity of Aluminum 5052 at 800 K to 910 K

    Science.gov (United States)

    Shi, Deheng; Zou, Fenghui; Zhu, Zunlue; Sun, Jinfeng

    2016-01-01

    In this study, we tried to develop a model to predict the effect of surface oxidization on the normal spectral emissivity of aluminum 5052 at a temperature range of 800 to 910 K and wavelength of 1.5 \\upmu m. In experiments, specimens were heated in air for 6 h at certain temperatures. Two platinum-rhodium thermocouples were symmetrically welded onto the front surface of the specimens near the measuring area for accurate monitoring of the temperature at the specimen surface. The temperatures measured by the two thermocouples had an uncertainty of 1 K. The normal spectral emissivity values were measured over the 6-h heating period at temperatures from 800 K to 910 K in increments of 10 K. Strong oscillations in the normal spectral emissivity were observed at each temperature. These oscillations were determined to form by the interference between the radiation stemming from the oxide layer and radiation from the substrate. The present measurements were compared with previous experimental results, and the variation in the normal spectral emissivity at given temperatures was evaluated. The uncertainty of the normal spectral emissivity caused only by the surface oxidization was found to be approximately 12.1 % to 21.8 %, and the corresponding uncertainty in the temperature caused only by the surface oxidization was approximately 9.1 K to 15.2 K. The model can reproduce the normal spectral emissivity well, including the strong oscillations that occur during the initial heating period.

  19. Assessment of Surface Soil Moisture Using High-Resolution Multi-Spectral Imagery and Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Leila Hassan-Esfahani

    2015-03-01

    Full Text Available Many crop production management decisions can be informed using data from high-resolution aerial images that provide information about crop health as influenced by soil fertility and moisture. Surface soil moisture is a key component of soil water balance, which addresses water and energy exchanges at the surface/atmosphere interface; however, high-resolution remotely sensed data is rarely used to acquire soil moisture values. In this study, an artificial neural network (ANN model was developed to quantify the effectiveness of using spectral images to estimate surface soil moisture. The model produces acceptable estimations of surface soil moisture (root mean square error (RMSE = 2.0, mean absolute error (MAE = 1.8, coefficient of correlation (r = 0.88, coefficient of performance (e = 0.75 and coefficient of determination (R2 = 0.77 by combining field measurements with inexpensive and readily available remotely sensed inputs. The spatial data (visual spectrum, near infrared, infrared/thermal are produced by the AggieAir™ platform, which includes an unmanned aerial vehicle (UAV that enables users to gather aerial imagery at a low price and high spatial and temporal resolutions. This study reports the development of an ANN model that translates AggieAir™ imagery into estimates of surface soil moisture for a large field irrigated by a center pivot sprinkler system.

  20. FT-Raman, FT-IR and UV-visible spectral investigations and ab initio computations of anti-epileptic drug: vigabatrin.

    Science.gov (United States)

    Edwin, Bismi; Joe, I Hubert

    2013-10-01

    Vibrational analysis of anti-epileptic drug vigabatrin, a structural GABA analog was carried out using NIR FT-Raman and FTIR spectroscopic techniques. The equilibrium geometry, various bonding features and harmonic vibrational wavenumbers were studied using density functional theory method. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA.4 program. Vibrational spectra, natural bond orbital analysis and optimized molecular structure show clear evidence for the effect of electron charge transfer on the activity of the molecule. Predicted electronic absorption spectrum from TD-DFT calculation has been compared with the UV-vis spectrum. The Mulliken population analysis on atomic charges and the HOMO-LUMO energy were also calculated. Good consistency is found between the calculated results and experimental data for the electronic absorption as well as IR and Raman spectra. The blue-shifting of the C-C stretching wavenumber reveals that the vinyl group is actively involved in the conjugation path. The NBO analysis confirms the occurrence of intramolecular hyperconjugative interactions resulting in ICT causing stabilization of the system. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. UV spectral analysis of very hot H-deficient [WCE]-type central stars of planetary nebulae: NGC 2867, NGC 5189, NGC 6905, Pb 6, and Sand 3

    CERN Document Server

    Keller, Graziela R; Maciel, Walter J

    2014-01-01

    We analysed UV FUSE, IUE, and HST/STIS spectra of five of the hottest [WCE]-type central stars of planetary nebulae: NGC 2867, NGC 5189, NGC 6905, Pb 6, and Sand 3. The analysis leveraged on our grid of CMFGEN synthetic spectra, which covers the parameter regime of hydrogen deficient central stars of planetary nebulae and allows a uniform and systematic study of the stellar spectra. The stellar atmosphere models calculated by us include many elements and ionic species neglected in previous analyses, which allowed us to improve the fits to the observed spectra considerably and provided an additional diagnostic line: the Ne VII $\\lambda$ 973 $\\mathrm{\\AA}$, which had not been modelled in [WCE] spectra and which presents, in these stars, a strong P-Cygni profile. We report newly derived photospheric and wind parameters and elemental abundances. The central stars of NGC 2867, NGC 5189, and Pb 6 had their temperatures revised upward in comparison with previous investigations and we found the carbon to helium mass ...

  2. Spectral luminescent properties of bacteriochlorin and aluminum phthalocyanine nanoparticles as hydroxyapatite implant surface coating

    Directory of Open Access Journals (Sweden)

    Yu. S. Maklygina

    2016-01-01

    Full Text Available The development and the spectral research of unique coating as crystalline nanoparticles of IR photosensitizers were performed for the creation of hydroxyapatite implants with photobactericidal properties. It has been proved that by the interaction of nanoparticles covering implant with the polar solvent, which simulates the interaction of the implant with the biocomponents in vivo (fast proliferating and with immunocompetent cells, photosensitizers nanoparticles change the spectroscopic properties, becoming fluorescent and phototoxic. Thus, the developed coating based on crystalline photosensitizer nanoparticles with studied specific properties should have antibacterial, anti-inflammatory effect by the photodynamic treatment in the near implant area. This research opens the prospect of the local prevention of inflammatory and autoimmune reactions in the area of implantation. The results of the study suggest a promising this technology in order to create implants with photobactericidal properties.

  3. 高光谱分辨率紫外平场光谱仪的研制%Development of a High Spectral Resolution UV Flat-Field Spectrograph

    Institute of Scientific and Technical Information of China (English)

    杜亮亮; 杜学维; 李朝阳; 安宁; 王秋平

    2015-01-01

    光栅作为一重要的分光元件,广泛应用于各类光谱仪,其中球面变线距平场光栅以其独特的平场特性使其容易与阵列探测器结合使用,一次实现宽光谱范围的记录。商业球面平场光栅一般只会提供光栅的公称线密度以及相应的安装参数,而不会提供光栅具体的变线距参数,并且提供的安装参数是针对整个使用波段优化的结果。使用者往往只需要其中的一部分波段。针对这种情况,根据球面平场光栅聚焦、分光原理,利用生产厂家提供的光学元件安装参数给出了推导球面变线距光栅变线距参数的方法。并给出了利用这些参数,根据光谱仪的实际工作波段确定最佳的CCD安装位置的方法。根据推导的光栅变线距参数可以对光学系统进行光学追迹已验证光学系统的性能。研制了一台高分辨率紫外平场光谱仪,覆盖光谱范围230~280 nm。采用的球面变线距光栅公称线密度为1200 lines・mm -1,使用波段为170~500 nm。推导了该光栅的变线距参数,并针对230~280 nm波段对CCD的安装位置进行了优化。同时利用不同元素的标准光源空心阴极灯对光谱仪进行了波长标定和光谱分辨率测试。波长标定采用参数拟合法,整个波段范围内的标定精度优于0.01 nm。光谱分辨率测试的结果表明光谱仪的光谱分辨率达到0.08 nm@280.20 nm。%As an important optical splitting element ,grating is used in many different spectrometers and spectrographs .Spheri‐cal varied‐line‐spacing grating (SVLSG) is easily combined with array detectors to get a wide wavelength range of spectrums in one time ,because it can focus the spectrums in approximately a plane .Therefore ,it’s widely used in many spectral instru‐ments .We usually only know the central groove density of a commercial grating and its mounting parameters ,while its line spacing parameters are unknown

  4. Impact of Environmental Factors on the Spectral Characteristics of Lava Surfaces: Field Spectrometry of Basaltic Lava Flows on Tenerife, Canary Islands, Spain

    Directory of Open Access Journals (Sweden)

    Long Li

    2015-12-01

    Full Text Available We report on spectral reflectance measurements of basaltic lava flows on Tenerife Island, Spain. Lava flow surfaces of different ages, surface roughness and elevations were systematically measured using a field spectroradiometer operating in the range of 350–2500 nm. Surface roughness, oxidation and lichen coverage were documented at each measured site. Spectral properties vary with age and morphology of lava. Pre-historical lavas with no biological coverage show a prominent increase in spectral reflectance in the 400–760 nm range and a decrease in the 2140–2210 nm range. Pāhoehoe surfaces have higher reflectance values than ʻaʻā ones and attain a maximum reflectance at wavelengths < 760 nm. Lichen-covered lavas are characterized by multiple lichen-related absorption and reflection features. We demonstrate that oxidation and lichen growth are two major factors controlling spectra of Tenerife lava surfaces and, therefore, propose an oxidation index and a lichen index to quantify surface alterations of lava flows: (1 the oxidation index is based on the increase of the slope of the spectral profile from blue to red as the field-observed oxidation level strengthens; and (2 the lichen index is based on the spectral reflectance in the 1660–1725 nm range, which proves to be highly correlated with lichen coverage documented in the field. The two spectral indices are applied to Landsat ETM+ and Hyperion imagery of the study area for mapping oxidation and lichen coverage on lava surfaces, respectively. Hyperion is shown to be capable of discriminating different volcanic surfaces, i.e., tephra vs. lava and oxidized lava vs. lichen-covered lava. Our study highlights the value of field spectroscopic measurements to aid interpretation of lava flow characterization using satellite images and of the effects of environmental factors on lava surface evolution over time, and, therefore, has the potential to contribute to the mapping as well as dating

  5. Surface temperature measurement of the plasma facing components with the multi-spectral infrared thermography diagnostics in tokamaks

    Science.gov (United States)

    Zhang, C.; Gauthier, E.; Pocheau, C.; Balorin, C.; Pascal, J. Y.; Jouve, M.; Aumeunier, M. H.; Courtois, X.; Loarer, Th.; Houry, M.

    2017-03-01

    For the long-pulse high-confinement discharges in tokamaks, the equilibrium of plasma requires a contact with the first wall materials. The heat flux resulting from this interaction is of the order of 10 MW/m2 for steady state conditions and up to 20 MW/m2 for transient phases. The monitoring on surface temperatures of the plasma facing components (PFCs) is a major concern to ensure safe operation and to optimize performances of experimental operations on large fusion facilities. Furthermore, this measurement is also required to study the physics associated to the plasma material interactions and the heat flux deposition process. In tokamaks, infrared (IR) thermography systems are routinely used to monitor the surface temperature of the PFCs. This measurement requires an accurate knowledge of the surface emissivity. However, and particularly for metallic materials such as tungsten, this emissivity value can vary over a wide range with both the surface condition and the temperature itself, which makes instantaneous measurement challenging. In this context, the multi-spectral infrared method appears as a very promising alternative solution. Indeed, the system has the advantage to carry out a non-intrusive measurement on thermal radiation while evaluating surface temperature without requiring a mandatory surface emissivity measurement. In this paper, a conceptual design for the multi-spectral infrared thermography is proposed. The numerical study of the multi-channel system based on the Levenberg-Marquardt (LM) nonlinear curve fitting is applied. The numerical results presented in this paper demonstrate the design allows for measurements over a large temperature range with a relative error of less than 10%. Furthermore, laboratory experiments have been performed from 200 °C to 740 °C to confirm the feasibility for temperature measurements on stainless steel and tungsten. In these experiments, the unfolding results from the multi-channel detection provide good

  6. Combined retrieval of Arctic liquid water cloud and surface snow properties using airborne spectral solar remote sensing

    Science.gov (United States)

    Ehrlich, André; Bierwirth, Eike; Istomina, Larysa; Wendisch, Manfred

    2017-09-01

    The passive solar remote sensing of cloud properties over highly reflecting ground is challenging, mostly due to the low contrast between the cloud reflectivity and that of the underlying surfaces (sea ice and snow). Uncertainties in the retrieved cloud optical thickness τ and cloud droplet effective radius reff, C may arise from uncertainties in the assumed spectral surface albedo, which is mainly determined by the generally unknown effective snow grain size reff, S. Therefore, in a first step the effects of the assumed snow grain size are systematically quantified for the conventional bispectral retrieval technique of τ and reff, C for liquid water clouds. In general, the impact of uncertainties of reff, S is largest for small snow grain sizes. While the uncertainties of retrieved τ are independent of the cloud optical thickness and solar zenith angle, the bias of retrieved reff, C increases for optically thin clouds and high Sun. The largest deviations between the retrieved and true original values are found with 83 % for τ and 62 % for reff, C. In the second part of the paper a retrieval method is presented that simultaneously derives all three parameters (τ, reff, C, reff, S) and therefore accounts for changes in the snow grain size. Ratios of spectral cloud reflectivity measurements at the three wavelengths λ1 = 1040 nm (sensitive to reff, S), λ2 = 1650 nm (sensitive to τ), and λ3 = 2100 nm (sensitive to reff, C) are combined in a trispectral retrieval algorithm. In a feasibility study, spectral cloud reflectivity measurements collected by the Spectral Modular Airborne Radiation measurement sysTem (SMART) during the research campaign Vertical Distribution of Ice in Arctic Mixed-Phase Clouds (VERDI, April/May 2012) were used to test the retrieval procedure. Two cases of observations above the Canadian Beaufort Sea, one with dense snow-covered sea ice and another with a distinct snow-covered sea ice edge are analysed. The retrieved values of τ, reff

  7. Combined retrieval of Arctic liquid water cloud and surface snow properties using airborne spectral solar remote sensing

    Directory of Open Access Journals (Sweden)

    A. Ehrlich

    2017-09-01

    Full Text Available The passive solar remote sensing of cloud properties over highly reflecting ground is challenging, mostly due to the low contrast between the cloud reflectivity and that of the underlying surfaces (sea ice and snow. Uncertainties in the retrieved cloud optical thickness τ and cloud droplet effective radius reff, C may arise from uncertainties in the assumed spectral surface albedo, which is mainly determined by the generally unknown effective snow grain size reff, S. Therefore, in a first step the effects of the assumed snow grain size are systematically quantified for the conventional bispectral retrieval technique of τ and reff, C for liquid water clouds. In general, the impact of uncertainties of reff, S is largest for small snow grain sizes. While the uncertainties of retrieved τ are independent of the cloud optical thickness and solar zenith angle, the bias of retrieved reff, C increases for optically thin clouds and high Sun. The largest deviations between the retrieved and true original values are found with 83 % for τ and 62 % for reff, C.In the second part of the paper a retrieval method is presented that simultaneously derives all three parameters (τ, reff, C, reff, S and therefore accounts for changes in the snow grain size. Ratios of spectral cloud reflectivity measurements at the three wavelengths λ1 = 1040 nm (sensitive to reff, S, λ2 = 1650 nm (sensitive to τ, and λ3 = 2100 nm (sensitive to reff, C are combined in a trispectral retrieval algorithm. In a feasibility study, spectral cloud reflectivity measurements collected by the Spectral Modular Airborne Radiation measurement sysTem (SMART during the research campaign Vertical Distribution of Ice in Arctic Mixed-Phase Clouds (VERDI, April/May 2012 were used to test the retrieval procedure. Two cases of observations above the Canadian Beaufort Sea, one with dense snow-covered sea ice and another with a distinct snow-covered sea ice

  8. Electronic structure investigations of 4-aminophthal hydrazide by UV-visible, NMR spectral studies and HOMO-LUMO analysis by ab initio and DFT calculations.

    Science.gov (United States)

    Sambathkumar, K; Jeyavijayan, S; Arivazhagan, M

    2015-08-05

    Combined experimental and theoretical studies were conducted on the molecular structure and vibrational spectra of 4-AminoPhthalhydrazide (APH). The FT-IR and FT-Raman spectra of APH were recorded in the solid phase. The molecular geometry and vibrational frequencies of APH in the ground state have been calculated by using the ab initio HF (Hartree-Fock) and density functional methods (B3LYP) invoking 6-311+G(d,p) basis set. The optimized geometric bond lengths and bond angles obtained by HF and B3LYP method show best agreement with the experimental values. Comparison of the observed fundamental vibrational frequencies of APH with calculated results by HF and density functional methods indicates that B3LYP is superior to the scaled Hartree-Fock approach for molecular vibrational problems. The difference between the observed and scaled wave number values of most of the fundamentals is very small. A detailed interpretation of the NMR spectra of APH was also reported. The theoretical spectrograms for infrared and Raman spectra of the title molecule have been constructed. UV-vis spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies, were performed by time dependent density functional theory (TD-DFT) approach. Finally the calculations results were applied to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra. And the temperature dependence of the thermodynamic properties of constant pressure (Cp), entropy (S) and enthalpy change (ΔH0→T) for APH were also determined. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Spectral Aerosol Extinction (SpEx): A New Instrument for In situ Ambient Aerosol Extinction Measurements Across the UV/Visible Wavelength Range

    Science.gov (United States)

    Jordan, C. E.; Anderson, B. E.; Beyersdorf, A. J.; Corr, C. A.; Dibb, J. E.; Greenslade, M. E.; Martin, R. F.; Moore, R. H.; Scheuer, E.; Shook, M. A.; hide

    2015-01-01

    We introduce a new instrument for the measurement of in situ ambient aerosol extinction over the 300-700 nm wavelength range, the Spectral Aerosol Extinction (SpEx) instrument. This measurement capability is envisioned to complement existing in situ instrumentation, allowing for simultaneous measurement of the evolution of aerosol optical, chemical, and physical characteristics in the ambient environment. In this work, a detailed description of the instrument is provided along with characterization tests performed in the laboratory. Measured spectra of NO2 and polystyrene latex spheres agreed well with theoretical calculations. Good agreement was also found with simultaneous aerosol extinction measurements at 450, 530, and 630 nm using CAPS PMex instruments in a series of 22 tests including non-absorbing compounds, dusts, soot, and black and brown carbon analogs. SpEx can more accurately distinguish the presence of brown carbon from other absorbing aerosol due to its 300 nm lower wavelength limit compared to measurements limited to visible wavelengths. In addition, the spectra obtained by SpEx carry more information than can be conveyed by a simple power law fit that is typically defined by the use of Angstrom Exponents. Future improvements aim at lowering detection limits and ruggedizing the instrument for mobile operation.

  10. Spectral Aerosol Extinction (SpEx): A New Instrument for In situ Ambient Aerosol Extinction Measurements Across the UV/Visible Wavelength Range

    Science.gov (United States)

    Jordan, C. E.; Anderson, B. E.; Beyersdorf, A. J.; Corr, C. A.; Dibb, J. E.; Greenslade, M. E.; Martin, R. F.; Moore, R. H.; Scheuer, E.; Shook, M. A.; Thornhill, K. L.; Troop, D.; Winstead, Edward L.; Ziemba, L. D.

    2015-01-01

    We introduce a new instrument for the measurement of in situ ambient aerosol extinction over the 300-700 nm wavelength range, the Spectral Aerosol Extinction (SpEx) instrument. This measurement capability is envisioned to complement existing in situ instrumentation, allowing for simultaneous measurement of the evolution of aerosol optical, chemical, and physical characteristics in the ambient environment. In this work, a detailed description of the instrument is provided along with characterization tests performed in the laboratory. Measured spectra of NO2 and polystyrene latex spheres agreed well with theoretical calculations. Good agreement was also found with simultaneous aerosol extinction measurements at 450, 530, and 630 nm using CAPS PMex instruments in a series of 22 tests including non-absorbing compounds, dusts, soot, and black and brown carbon analogs. SpEx can more accurately distinguish the presence of brown carbon from other absorbing aerosol due to its 300 nm lower wavelength limit compared to measurements limited to visible wavelengths. In addition, the spectra obtained by SpEx carry more information than can be conveyed by a simple power law fit that is typically defined by the use of Angstrom Exponents. Future improvements aim at lowering detection limits and ruggedizing the instrument for mobile operation.

  11. Spectral Aerosol Extinction (SpEx: a new instrument for in situ ambient aerosol extinction measurements across the UV/visible wavelength range

    Directory of Open Access Journals (Sweden)

    C. E. Jordan

    2015-06-01

    Full Text Available We introduce a new instrument for the measurement of in situ ambient aerosol extinction over the 300–700 nm wavelength range, the Spectral Aerosol Extinction (SpEx instrument. This measurement capability is envisioned to complement existing in situ instrumentation, allowing for simultaneous measurement of the evolution of aerosol optical, chemical, and physical characteristics in the ambient environment. In this work, a detailed description of the instrument is provided along with characterization tests performed in the laboratory. Measured spectra of NO2 and polystyrene latex spheres (PSLs agreed well with theoretical calculations. Good agreement was also found with simultaneous aerosol extinction measurements at 450, 530, and 630 nm using CAPS PMex instruments in a series of 22 tests including non-absorbing compounds, dusts, soot, and black and brown carbon analogs. SpEx can more accurately distinguish the presence of brown carbon from other absorbing aerosol due to its 300 nm lower wavelength limit compared to measurements limited to visible wavelengths. Extinction spectra obtained with SpEx contain more information than can be conveyed by a simple power law fit (typically represented by Ångström Exponents. Planned future improvements aim to lower detection limits and ruggedize the instrument for mobile operation.

  12. X-ray flares on the UV Ceti-type star CC Eridani: a "peculiar" time-evolution of spectral parameters

    CERN Document Server

    Crespo-Chacón, I; Reale, F; Caramazza, M; López-Santiago, J; Pillitteri, I

    2007-01-01

    Context: Weak flares are supposed to be an important heating agent of the outer layers of stellar atmospheres. However, due to instrumental limitations, only large X-ray flares have been studied in detail until now. Aims: We used an XMM-Newton observation of the very active BY-Dra type binary star CC Eri in order to investigate the properties of two flares that are weaker than those typically studied in the literature. Methods: We performed time-resolved spectroscopy of the data taken with the EPIC-PN CCD camera. A multi-temperature model was used to fit the spectra. We inferred the size of the flaring loops using the density-temperature diagram. The loop scaling laws were applied for deriving physical parameters of the flaring plasma. We also estimated the number of loops involved in the observed flares. Results: A large X-ray variability was found. Spectral analysis showed that all the regions in the light curve, including the flare segments, are well-described by a 3-T model with variable emission measures...

  13. Red-Edge Spectral Reflectance as an Indicator of Surface Moisture Content in an Alaskan Peatland Ecosystem

    Science.gov (United States)

    McPartland, M.; Kane, E. S.; Turetsky, M. R.; Douglass, T.; Falkowski, M. J.; Montgomery, R.; Edwards, J.

    2015-12-01

    Arctic and boreal peatlands serve as major reservoirs of terrestrial organic carbon (C) because Net Primary Productivity (NPP) outstrips C loss from decomposition over long periods of time. Peatland productivity varies as a function of water table position and surface moisture content, making C storage in these systems particularly vulnerable to the climate warming and drying predicted for high latitudes. Detailed spatial knowledge of how aboveground vegetation communities respond to changes in hydrology would allow for ecosystem response to environmental change to be measured at the landscape scale. This study leverages remotely sensed data along with field measurements taken at the Alaska Peatland Experiment (APEX) at the Bonanza Creek Long Term Ecological Research site to examine relationships between plant solar reflectance and surface moisture. APEX is a decade-long experiment investigating the effects of hydrologic change on peatland ecosystems using water table manipulation treatments (raised, lowered, and control). Water table levels were manipulated throughout the 2015 growing season, resulting in a maximum separation of 35 cm between raised and lowered treatment plots. Water table position, soil moisture content, depth to seasonal ice, soil temperature, photosynthetically active radiation (PAR), CO2 and CH4 fluxes were measured as predictors of C loss through decomposition and NPP. Vegetation was surveyed for percent cover of plant functional types. Remote sensing data was collected during peak growing season, when the separation between treatment plots was at maximum difference. Imagery was acquired via a SenseFly eBee airborne platform equipped with a Canon S110 red-edge camera capable of detecting spectral reflectance from plant tissue at 715 nm band center to within centimeters of spatial resolution. Here, we investigate empirical relationships between spectral reflectance, water table position, and surface moisture in relation to peat carbon balance.

  14. Real-time surface tracking system using common-path spectral domain optical coherence tomography

    Science.gov (United States)

    Kim, Keo-Sik; Park, Hyoung-Jun; Kang, Hyun Seo; Kang, Jin U.; Song, Chul-Gyu

    2012-11-01

    An enhanced surface tracking system based on optical coherence tomography (OCT) modality has been developed and tested for use in a surgical guidance system. A surface detection algorithm based on a Savitzky-Golay filter of A-scan data and thresholding was applied to real-time depth tracking. The algorithm output controlled a motorized stage to adjust the probe position according to the sample's topological variance in real-time. As a result, the root mean square error (RMSE: 4.2 μm) of our algorithm was relatively lower than the conventional method (RMSE: 16.6 μm). Also, OCT images obtained using the algorithm showed a significantly extended imaging range and active surface tracking in real time. Consequently, the devised method demonstrated potential for use in systems for guiding surgical robots and endoscopic OCT.

  15. Genotoxicity testing of samples generated during UV/H2O2 treatment of surface water for the production of drinking water using the Ames test in vitro and the Comet assay and the SCE test in vivo

    NARCIS (Netherlands)

    Penders, E.J.M.; Martijn, A.J.; Spenkelink, A.; Alink, G.M.; Rietjens, I.; Hoogenboezem, W.

    2012-01-01

    UV/H2O2 treatment can be part of the process converting surface water to drinking water, but would pose a potential problem when resulting in genotoxicity. This study investigates the genotoxicity of samples collected from the water treatment plant Andijk, applying UV/H2O2 treatment with an electric

  16. "PROCESS and UVolution: photochemistry experiments in Low Earth Orbit": investigation of the photostability of organic and mineral material exposed to Mars surface UV radiation conditions

    Science.gov (United States)

    Stalport, Fabien; Guan, Yuan Yong; Noblet, Audrey; Coll, Patrice; Szopa, Cyril; Macari, Frederique; Person, Alain; Chaput, Didier; Raulin, Francois; Cottin, Hervé

    The harsh martian environment could explain the lack of organics and minerals such as car-bonates by destroying them: i) no organic molecule has been found at the two different landing sites of the Viking landers within the detection limits of the instruments onboard, ii) to date, no large deposits of carbonates have been detected and their detection is specific of local ar-eas and in very low amounts. In this context several experimental and numerical modelling studies were led to evaluate the possibility for the destruction or evolution of the organics and carbonates under the martian surface environmental conditions. The presence of UV radiation has been proposed to explain the photodecomposition of such material. This is the reason why, to investigate the nature, abundance, and stability of organic and mineral material that could survive under such environmental conditions, we exposed in low Earth orbit organic molecules and carbonates (also biominerals) with martian relevance to solar UV radiation ¿ 200 nm, in the frame of the experiment UVolution, onboard the BIOPAN ESA module which was set outside a Russian Foton automated capsule and exposed to space condition during 12 days in September 2007, and the experiment PROCESS (hervé peux tu rajouter quelques infos sur le temps exact d'exposition stp) which was set outside the International Space Station (ISS). Here, we present results with regard to the impact of solar UV radiation on the targeted molecules. Preliminary results indicate that that no organic sample seems to resist to the solar UV radiation if directly exposed to it. Conversely our results show that the exposed carbonates seem to be stable to the solar UV radiation if directly exposed to it. Moreover, the stability of the biominerals strengthens the interest to explore deeper their potential as life records at Mars. Hence they should be considered as primary targets for in situ analyses during future missions.

  17. Detection of small surface vessels in near, medium, and far infrared spectral bands

    Science.gov (United States)

    Dulski, R.; Milewski, S.; Kastek, M.; Trzaskawka, P.; Szustakowski, M.; Ciurapinski, W.; Zyczkowski, M.

    2011-11-01

    Protection of naval bases and harbors requires close co-operation between security and access control systems covering land areas and those monitoring sea approach routes. The typical location of naval bases and harbors - usually next to a large city - makes it difficult to detect and identify a threat in the dense regular traffic of various sea vessels (i.e. merchant ships, fishing boats, tourist ships). Due to the properties of vessel control systems, such as AIS (Automatic Identification System), and the effectiveness of radar and optoelectronic systems against different targets it seems that fast motor boats called RIB (Rigid Inflatable Boat) could be the most serious threat to ships and harbor infrastructure. In the paper the process and conditions for the detection and identification of high-speed boats in the areas of ports and naval bases in the near, medium and far infrared is presented. Based on the results of measurements and recorded thermal images the actual temperature contrast delta T (RIB / sea) will be determined, which will further allow to specify the theoretical ranges of detection and identification of the RIB-type targets for an operating security system. The data will also help to determine the possible advantages of image fusion where the component images are taken in different spectral ranges. This will increase the probability of identifying the object by the multi-sensor security system equipped additionally with the appropriate algorithms for detecting, tracking and performing the fusion of images from the visible and infrared cameras.

  18. Presence of UV filters in surface water and the effects of phenylbenzimidazole sulfonic acid on rainbow trout (Oncorhynchus mykiss) following a chronic toxicity test.

    Science.gov (United States)

    Grabicova, Katerina; Fedorova, Ganna; Burkina, Viktoriia; Steinbach, Christoph; Schmidt-Posthaus, Heike; Zlabek, Vladimir; Kocour Kroupova, Hana; Grabic, Roman; Randak, Tomas

    2013-10-01

    UV filters belong to a group of compounds that are used by humans and are present in municipal waste-waters, effluents from sewage treatment plants and surface waters. Current information regarding UV filters and their effects on fish is limited. In this study, the occurrence of three commonly used UV filters - 2-phenylbenzimidazole-5-sulfonic acid (PBSA), 2-hydroxy-4-methoxybenzophenone (benzophenone-3, BP-3) and 5-benzoyl-4-hydroxy-2-methoxy-benzenesulfonic acid (benzophenone-4, BP-4) - in South Bohemia (Czech Republic) surface waters is presented. PBSA concentrations (up to 13μgL(-1)) were significantly greater than BP-3 or BP-4 concentrations (up to 620 and 390ngL(-1), respectively). On the basis of these results, PBSA was selected for use in a toxicity test utilizing the common model organism rainbow trout (Oncorhynchus mykiss). Fish were exposed to three concentrations of PBSA (1, 10 and 1000µgL(-1)) for 21 and 42 days. The PBSA concentrations in the fish plasma, liver and kidneys were elevated after 21 and 42 days of exposure. PBSA increased activity of certain P450 cytochromes. Exposure to PBSA also changed various biochemical parameters and enzyme activities in the fish plasma. However, no pathological changes were obvious in the liver or gonads.

  19. Synthesis, spectral (IR, UV-Vis and variable temperature NMR) characterization and crystal structure of (N-benzyl-N-furfuryldithicarbamato-S,S')(thiocyanato-N)(triphenylphosphine)nickel(II).

    Science.gov (United States)

    Valarmathi, P; Thirumaran, S; Sarmal, Lovely; Kant, Rajni

    2014-08-14

    Planar (N-benzyl-N-furfuryldithiocarbamato-S,S')(thiocyanato-N)(triphenylphospine)nickel(II), [Ni(bfdtc)(NCS)(PPh3)], (1) was prepared from bis(N-benzyl-N-furfuryldithiocarbamato-S,S')nickel(II), [Ni(bfdtc)2], (2) and characterized by elemental analysis, cyclic voltammetry, electronic, IR and variable temperature (1)H and (13)C NMR spectra. For complex 1, the thioureide vCN value is shifted to higher wavenumber compared to 2 and N(13)CS2 carbon signal observed for 1 is additionally shielded compared to the parent complex 2, suggesting increased strength of the thioureide bond due to the presence of the π-accepting phosphine. In the room temperature (13)C NMR spectrum of 1, two pseudo doublets are observed in the aliphatic region. Variable temperature (13)C NMR spectral studies suggest that the fast thiocyanate exchange appears to be responsible for the appearance of pseudo doublets. Single crystal X-ray structural analysis of 1 and 2 confirm the presence of four coordinated nickel in a distorted square planar arrangement with the NiS2PN and NiS4 chromophores, respectively. The NiS bonds are symmetric in 2 (2.1914(14) and 2.2073(13)Å). But significant asymmetry in NiS bond distances was observed in 1 (2.2202(8)Å and 2.1841Å). This observation clearly supports the less effective trans effect of SCN(-) over PPh3. Cyclic voltammetric studies revealed easier reduction of nickel(II) to nickel(I) in complex 1 compared to 2.

  20. Free-surface Multiples and full-waveform inversion spectral resolution

    NARCIS (Netherlands)

    Kazei, V.V.; Kashtan, B.M.; Troyan, V.N.; Mulder, W.A.

    2015-01-01

    Low frequencies play a crucial role in the convergence of full-waveform inversion to the correct model in most of its current implementations. However, the lower the frequencies, the bigger are the amplitudes of the surface waves, causing the inversion to be driven by the latter. If they are not bla

  1. High-conductivity silicon based spectrally selective plasmonic surfaces for sensing in the infrared region

    Science.gov (United States)

    Gorgulu, K.; Gok, A.; Yilmaz, M.; Topalli, K.; Okyay, A. K.

    2017-02-01

    Plasmonic perfect absorbers have found a wide range of applications in imaging, sensing, and light harvesting and emitting devices. Traditionally, metals are used to implement plasmonic structures. For sensing applications, it is desirable to integrate nanophotonic active surfaces with biasing and amplification circuitry to achieve monolithic low cost solutions. Commonly used plasmonic metals such as Au and Ag are not compatible with standard silicon complementary metal-oxide-semiconductor (CMOS) technology. Here we demonstrate plasmonic perfect absorbers based on high conductivity silicon. Standard optical lithography and reactive ion etching techniques were used for the patterning of the samples. We present computational and experimental results of surface plasmon resonances excited on a silicon surface at normal and oblique incidences. We experimentally demonstrate our absorbers as ultra-low cost, CMOS-compatible and efficient refractive index sensing surfaces. The experimental results reveal that the structure exhibits a sensitivity of around 11 000 nm/RIU and a figure of merit of up to 2.5. We also show that the sensing performance of the structure can be improved by increasing doping density.

  2. Physical characterization, spectral response and remotely sensed mapping of Mediterranean soil surface crusts

    NARCIS (Netherlands)

    Jong, S.M. de; Addink, E.A.; Duijsing, D.; Beek, L.P.H. van

    2011-01-01

    Soil surface crusting and sealing are frequent but unfavorable processes in Mediterranean areas. Soil crust and seals form on bare soil subject to high-intensity rainfall, resulting in a hard, impenetrable layer that impedes infiltration and hampers the germination and establishment of plants. The a

  3. Formation of environmentally persistent free radicals as the mechanism for reduced catechol degradation on hematite-silica surface under UV irradiation.

    Science.gov (United States)

    Li, Hao; Pan, Bo; Liao, Shaohua; Zhang, Di; Xing, Baoshan

    2014-05-01

    Iron is rich in soils, and is recently reported to form stable complexes with organic free radicals, generating environmentally persistent free radicals (EPFRs). The observation may challenge the common viewpoint that iron is an effective catalyst to facilitate the degradation of various organic chemicals. But no study was specifically designed to investigate the possible inhibited degradation of organic chemicals because of the formation of EPFRs in dry environment. We observed that catechol degradation under UV irradiation was decreased over 20% in silica particles coated with 1% hematite in comparison to uncoated silica particles. Stabilized semiquinone or quinine and phenol radicals were involved in HMT-silica system. EPFR formation was thus the reason for the reduced catechol degradation on HMT-silica surface under UV irradiation at ambient temperature. EPFRs should be incorporated in the studies of organic contaminants geochemical behavior, and will be a new input in their environmental fate modeling.

  4. Comparison of the surface ion density of silica gel evaluated via spectral induced polarization versus acid-base titration

    Science.gov (United States)

    Hao, Na; Moysey, Stephen M. J.; Powell, Brian A.; Ntarlagiannis, Dimitrios

    2016-12-01

    Surface complexation models are widely used with batch adsorption experiments to characterize and predict surface geochemical processes in porous media. In contrast, the spectral induced polarization (SIP) method has recently been used to non-invasively monitor in situ subsurface chemical reactions in porous media, such as ion adsorption processes on mineral surfaces. Here we compare these tools for investigating surface site density changes during pH-dependent sodium adsorption on a silica gel. Continuous SIP measurements were conducted using a lab scale column packed with silica gel. A constant inflow of 0.05 M NaCl solution was introduced to the column while the influent pH was changed from 7.0 to 10.0 over the course of the experiment. The SIP measurements indicate that the pH change caused a 38.49 ± 0.30 μS cm- 1 increase in the imaginary conductivity of the silica gel. This increase is thought to result from deprotonation of silanol groups on the silica gel surface caused by the rise in pH, followed by sorption of Na+ cations. Fitting the SIP data using the mechanistic model of Leroy et al. (Leroyet al., 2008), which is based on the triple layer model of a mineral surface, we estimated an increase in the silica gel surface site density of 26.9 × 1016 sites m- 2. We independently used a potentiometric acid-base titration data for the silica gel to calibrate the triple layer model using the software FITEQL and observed a total increase in the surface site density for sodium sorption of 11.2 × 1016 sites m- 2, which is approximately 2.4 times smaller than the value estimated using the SIP model. By simulating the SIP response based on the calibrated surface complexation model, we found a moderate association between the measured and estimated imaginary conductivity (R2 = 0.65). These results suggest that the surface complexation model used here does not capture all mechanisms contributing to polarization of the silica gel captured by the SIP data.

  5. Martian Surface Temperature and Spectral Response from the MSL REMS Ground Temperature Sensor

    Science.gov (United States)

    Martin-Torres, Javier; Martínez-Frías, Jesús; Zorzano, María-Paz; Serrano, María; Mendaza, Teresa; Hamilton, Vicky; Sebastián, Eduardo; Armiens, Carlos; Gómez-Elvira, Javier; REMS Team

    2013-04-01

    The Rover Environmental Monitoring Station (REMS) on the Mars Science Laboratory (MSL) offers the opportunity to explore the near surface atmospheric conditions and, in particular will shed new light into the heat budget of the Martian surface. This is important for studies of the atmospheric boundary layer (ABL), as the ground and air temperatures measured directly by REMS control the coupling of the atmosphere with the surface [Zurek et al., 1992]. This coupling is driven by solar insolation. The ABL plays an important role in the general circulation and the local atmospheric dynamics of Mars. One of the REMS sensors, the ground temperature sensor (GTS), provides the data needed to study the thermal inertia properties of the regolith and rocks beneath the MSL rover. The GTS includes thermopile detectors, with infrared bands of 8-14 µm and 16-20 µm [Gómez-Elvira et al., 2012]. These sensors are clustered in a single location on the MSL mast and the 8-14 µm thermopile sounds the surface temperature. The infrared radiation reaching the thermopile is proportional to the emissivity of the surface minerals across these thermal wavelengths. We have developed a radiative transfer retrieval method for the REMS GTS using a database of thermal infrared laboratory spectra of analogue minerals and their mixtures. [Martín Redondo et al. 2009, Martínez-Frías et al. 2012 - FRISER-IRMIX database]. This method will be used to assess the perfomance of the REMS GTS as well as determine, through the error analysis, the surface temperature and emissivity values where MSL is operating. Comparisons with orbiter data will be performed. References Gómez-Elvira et al. [2012], REMS: The Environmental Sensor Suite for the Mars Science Laboratory Rover, Space Science Reviews, Volume 170, Issue 1-4, pp. 583-640. Martín-Redondo et al. [2009] Journal of Environmental Monitoring 11:, pp. 1428-1432. Martínez-Frías et al. [2012] FRISER-IRMIX database http

  6. Improvement in the UV resistance of baculoviruses by displaying nano-zinc oxide-binding peptides on the surfaces of their occlusion bodies.

    Science.gov (United States)

    Li, Jin; Zhou, Yin; Lei, Chengfeng; Fang, Wei; Sun, Xiulian

    2015-08-01

    The sensitivity of baculoviruses to UV radiation severely limits their large-scale application as biological insecticides. The polyhedron envelope of a baculovirus, which is composed of carbohydrate and polyhedron envelope protein (PEP), is a significant structure for the stability and persistence of occlusion bodies (OBs) under environmental conditions. The results of this study revealed that the rough pitted surface phenotype of a pep-null Autographa californica multiple nucleopolyhedrovirus (AcMNPV) could not be rescued by any of its homologues, such as Helicoverpa armigera nucleopolyhedrovirus pep or Cydia pomonella granulovirus putative peps. In contrast, the N-terminal and middle flexible region (NM region, 1-167 aa) of AcMNPV PEP were able to form an intact OB envelope. Furthermore, this region was capable of carrying eGFP to the surfaces of the OBs. To improve the UV resistance of AcMNPV OBs, two peptides capable of specifically binding to nano-ZnO were separately fused to the NM region of PEP. Under laboratory conditions, infectivity of the recombinant viruses binding to nano-ZnO particles was about ninefold higher than that without the nano-ZnO particles after UV-B irradiation. Pot experiments revealed that the half-life of the recombinant baculovirus binding nano-ZnO particles was 3.3 ± 0.15 days, which was significantly longer than that of the control virus (0.49 ± 0.06 days). These results therefore represent a new approach for the protection the baculoviral insecticides against UV irradiation in the field.

  7. The spectral emittance and stability of coatings and textured surfaces for thermophotovoltaic (TPV) radiator applications

    Energy Technology Data Exchange (ETDEWEB)

    Cockeram, B.V.; Hollenbeck, J.L.

    2000-11-01

    Coatings or surface modifications are needed to improve the surface emissivity of materials under consideration for TPV radiator applications to a value of 0.8 or higher. Vacuum plasma spray coatings (ZrO{sub 2} + 18% TiO{sub 2} + 10% Y{sub 2}O{sub 3}, ZrC, Fe{sub 2}TiO{sub 5}, ZrTiO{sub 4}, ZrO{sub 2} + 8% Y{sub 2}O{sub 3} + 2% HfO{sub 2}, and Al{sub 2}O{sub 3} + TiO{sub 2}) and a chemical vapor deposited coating of rhenium whiskers were used to increase the surface emissivity of refractory metal and nickel-base materials. Emittance measurements following 4000 hours of vacuum annealing at 1100 C show that only the ZrO{sub 2} + 18% TiO{sub 2} + 10% Y{sub 2}O{sub 3}, ZrC, and Al{sub 2}O{sub 3} + TiO{sub 2} coatings have the desired thermal stability, and maintain emissivity values higher than 0.8. These coatings are graybody emitters, and provide a high emissivity value in the wavelength range that is relevant to the TPV cells. The highest emissivity values were observed for the Al{sub 2}O{sub 3} + TiO{sub 2} coatings, with post-anneal values higher than graphite.

  8. UV-vis spectral analysis of lawsone in henna powder%紫外可见光谱分析海娜粉中的指甲花醌

    Institute of Scientific and Technical Information of China (English)

    乔仙蓉

    2016-01-01

    通过分析海娜粉浸提液和不同pH介质中指甲花醌溶液的紫外可见光谱,研究了分光光度法定量测定海娜粉中指甲花醌含量的检测波长和参比溶液。选择453 nm作为检测波长,以pH=2盐酸介质中的海娜粉浸提液作为参比,测定pH=12的氢氧化钠介质中试液的吸光度值,根据标准曲线法定量分析海娜粉中的指甲花醌。结果表明,指甲花醌质量浓度在10~140 mg/L内符合朗伯比尔定律,线性相关系数r=0.99995,精密度RSD不高于0.47%。样品溶液吸光度值在14 h内无明显变化,指甲花醌加标回收率为99.0%~100.0%。本实验方法操作简便,结果可靠,可作为海娜粉中指甲花醌含量检测的依据。%UV - vis spectra of henna aqueous extract and lawsone solution of different pH mediums were analyzed to select the detection wavelength and the reference solution for determining lawsone content in henna powder by spectrophotometer. Selecting 453 nm as the detection wavelength,with henna powder extract in hydrochloric acid of pH value 2 as the reference solution,the absorbance value of the testing solution samples in NaOH solution of pH =12 as the working medium,the lawsone mass concentration in the henna powder sample was quantified based upon comparison with the standard calibration curve. The results showed that within the lawsone mass concentration range of 10~140 mg/L,the absorbance follows Lambert-Beer's law;the linear correlation coefficient is r=0. 999 95 and the precision RSD is less than 0. 47%. The absorbancevalue of the sample solution can keep stable within 14 h,while the lawsone spiked recoveries achieves 99. 0% ~100. 0%. The method is simple,reliable,and can be used to detect the lawsone content in henna powder.

  9. Design concepts of monolithic metamorphic vertical-cavity surface-emitting lasers for the 1300–1550 nm spectral range

    Energy Technology Data Exchange (ETDEWEB)

    Egorov, A. Yu., E-mail: anton@beam.ioffe.ru; Karachinsky, L. Ya.; Novikov, I. I.; Babichev, A. V.; Nevedomskiy, V. N. [Russian Academy of Sciences, Ioffe Institute (Russian Federation); Bugrov, V. E. [ITMO University (Russian Federation)

    2015-11-15

    Possible design concepts for long-wavelength vertical-cavity surface-emitting lasers for the 1300–1550 nm spectral range on GaAs substrates are suggested. It is shown that a metamorphic GaAs–InGaAs heterostructure with a thin buffer layer providing rapid transition from the lattice constant of GaAs to that of In{sub x}Ga{sub 1–x}As with an indium fraction of x < 0.3 can be formed by molecular-beam epitaxy. Analysis by transmission electron microscopy demonstrated the effective localization of mismatch dislocations in the thin buffer layer and full suppression of their penetration into the overlying InGaAs metamorphic layer.

  10. Topographic power spectral density study of the effect of surface treatment processes on niobium for superconducting radio frequency accelerator cavities

    Energy Technology Data Exchange (ETDEWEB)

    Charles Reece, Hui Tian, Michael Kelley, Chen Xu

    2012-04-01

    Microroughness is viewed as a critical issue for attaining optimum performance of superconducting radio frequency accelerator cavities. The principal surface smoothing methods are buffered chemical polish (BCP) and electropolish (EP). The resulting topography is characterized by atomic force microscopy (AFM). The power spectral density (PSD) of AFM data provides a more thorough description of the topography than a single-value roughness measurement. In this work, one dimensional average PSD functions derived from topography of BCP and EP with different controlled starting conditions and durations have been fitted with a combination of power law, K correlation, and shifted Gaussian models to extract characteristic parameters at different spatial harmonic scales. While the simplest characterizations of these data are not new, the systematic tracking of scale-specific roughness as a function of processing is new and offers feedback for tighter process prescriptions more knowledgably targeted at beneficial niobium topography for superconducting radio frequency applications.

  11. Influence of fiber surface-treatment on interfacial property of poly(L-lactic acid)/ramie fabric biocomposites under UV-irradiation hydrothermal aging

    Energy Technology Data Exchange (ETDEWEB)

    Chen Dakai; Li Jing [Institute of Nano- and Bio-polymeric Materials, School of Material Science and Engineering, Tongji University, Shanghai 200092 (China); Ren Jie, E-mail: renjie6598@163.com [Institute of Nano- and Bio-polymeric Materials, School of Material Science and Engineering, Tongji University, Shanghai 200092 (China) and Key Laboratory of Advanced Civil Engineering Materials, Ministry of Education, Tongji University, Shanghai 200092 (China)

    2011-04-15

    Research highlights: {yields} Ramie fiber is used as reinforced material because it's lowest water absorption among sisal, jute, kenaf and ramie fiber. {yields} Fiber surface-treatment can cause an accelerated decline in mechanical properties of PLLA biocomposites after UV-irradiation hydrothermal aging. {yields} The swelling of ramie fibers reduce the interfacial adhesive strength in critical area of PLLA matrix-ramie fabric interface. - Abstract: The present study is devoted to the effect of fiber surface-treatment on the interfacial property of biocomposites based on poly(L-lactic acid) (PLLA) and ramie fabric. Ramie fiber is used as reinforced material because it's lowest water absorption among sisal, jute, kenaf and ramie fiber. Fiber surface-treatment can increase the water absorption of natural fibers. SEM images show that PLLA biocomposites with treated ramie fabric exhibit better interfacial adhesion character. DMA results show that the storage modulus of PLLA biocomposites with treated ramie increase compared to neat PLLA and PLLA biocomposites with untreated ramie. Unexpectedly, fiber surface-treatment can cause an accelerated decline in mechanical properties of PLLA biocomposites after UV-irradiation hydrothermal aging. Finally, GPC results show that there is no obvious decline in the molecular weight of PLLA. The main reason for this decline is the interfacial destructive effect induced by the water absorption of ramie fiber.

  12. Estimate of Small Stiffness and Damping Ratio in Residual Soil Using Spectral Analysis of Surface Wave Method

    Directory of Open Access Journals (Sweden)

    Bawadi Nor Faizah

    2016-01-01

    Full Text Available Research in the important parameters for modeling the dynamic behavior of soils has led to rapid development of the small strain stiffness and damping ratio for use in the seismic method. It is because, the experimental determination of the damping ratio is problematic, especially for hard soils sample. Many researchers have proved that the surface wave method is a reliable tool to determine shear wave velocity and damping ratio profiles at a site with very small strains level. Surface wave methods based on Rayleigh waves propagation and the resulting attenuation curve can become erroneous when higher modes contribute to the soil’s response. In this study, two approaches has been used to determine the shear strain amplitude and damping ratio of residual soils at small strain level using Spectral Analysis of Surface Wave (SASW method. One is to derive shear strain amplitude from the frequency-response curve and the other is to derive damping ratio from travel-time data. Then, the results are compared to the conventional method.

  13. Fast Inversion of Air-Coupled Spectral Analysis of Surface Wave (SASW Using in situ Particle Displacement

    Directory of Open Access Journals (Sweden)

    Yifeng Lu

    2015-11-01

    Full Text Available Spectral Analysis of Surface Wave (SASW is widely used in nondestructive subsurface profiling for geological sites. The air-coupled SASW is an extension from conventional SASW methods by replacing ground-mounted accelerometers with non-contact microphones, which acquire a leaky surface wave instead of ground vibration. The air-coupled SASW is a good candidate for fast inspection in shallow geological studies. Especially for pavement maintenance, minimum traffic interference might be induced. One issue that restrains SASW from fast inspection is the traditional slow inversion which relies on guess-and-check iteration techniques including a forward analysis. In this article, a fast inversion analysis algorithm is proposed to estimate the shear velocity profile without performing conventional forward simulation. By investigating the attenuation of particle displacement along penetrating depths, a weighted combination relationship is derived to connect the dispersion curve with the shear velocity profile directly. Using this relationship, the shear velocity profile could be estimated from a given/measured dispersion curve. The proposed procedure allows the surface wave-based method to be fully automatic and even operated in real-time for geological site and pavement assessment. The method is verified by the forward analysis with stiffness matrix method. It is also proved by comparing with other published results using various inversion methods.

  14. Integration of Field and Laboratory Spectral Data with Multi-Resolution Remote Sensed Imagery for Asphalt Surface Differentiation

    Directory of Open Access Journals (Sweden)

    Alessandro Mei

    2014-03-01

    Full Text Available The ability to classify asphalt surfaces is an important goal for the selection of suitable non-variant targets as pseudo-invariant targets during the calibration/validation of remotely-sensed images. In addition, the possibility to recognize different types of asphalt surfaces on the images can help optimize road network management. This paper presents a multi-resolution study to improve asphalt surface differentiation using field spectroradiometric data, laboratory analysis and remote sensing imagery. Multispectral Infrared and Visible Imaging Spectrometer (MIVIS airborne data and multispectral images, such as Quickbird and Ikonos, were used. From scatter plots obtained by field data using λ = 460 and 740 nm, referring to MIVIS Bands 2 and 16 and Quickbird and Ikonos Bands 1 and 4, pixels corresponding to asphalt covering were identified, and the slope of their interpolation lines, assumed as asphalt lines, was calculated. These slopes, used as threshold values in the Spectral Angle Mapper (SAM classifier, obtained an overall accuracy of 95% for Ikonos, 98% for Quickbird and 93% for MIVIS. Laboratory investigations confirm the existence of the asphalt line also for new asphalts, too.

  15. Title: Near-UV behaviour of observed TNO reflectance spectra

    Science.gov (United States)

    Seccull, Tom; Fraser, Wesley Cristopher; Izawa, Matthew; Brown, Michael E.

    2016-10-01

    Observed spectra provide the best diagnostics of the surface compositions of Trans-Neptunian Objects (TNOs). We have observed the spectra of 7 TNOs, from across almost the full range of dynamical classes, using the VLT's X-Shooter spectrograph. Compared to the 5 targets in our sample which exhibit linear spectra in the UV-optical range, two of of our targets show highly unusual spectral behaviour, whereby their reflectance decreases sharply at wavelengths below ~440nm. Those same objects exhibit typically unremarkable spectra in the optical and near-IR spectral regions. In these regions where available, our observed spectra of the targets are in agreement with spectra or photometry available in the literature. Using a different solar analogue to produce our reflectance spectra does not remove the UV decrease exhibited by the two targets. Further, it appears that neither reducing the spectra with different pipelines, nor using drastically different parameters in those pipelines changes this general behaviour. Based on laboratory spectra of complex hydrocarbons it is plausible that the near-UV behaviour is the result of a surface coating of organic substances on the TNOs which exhibit it. The spectra of organics are also consistent in having a general red slope similar to that observed in the spectra of many TNOs. While laboratory spectra of some silicate substances also show a decrease in reflectance in the near-UV spectral region that is in principle consistent with our observations, those silicates do not exhibit a red slope consistent with our optical spectra. Hence, the hypothesis that silicates are present seems less likely than the hypothesis that this UV decrease is due to the presence of organics on the surfaces of these objects.

  16. High-Resolution Mapping of Urban Surface Water Using ZY-3 Multi-Spectral Imagery

    Directory of Open Access Journals (Sweden)

    Fangfang Yao

    2015-09-01

    Full Text Available Accurate information of urban surface water is important for assessing the role it plays in urban ecosystem services under the content of urbanization and climate change. However, high-resolution monitoring of urban water bodies using remote sensing remains a challenge because of the limitation of previous water indices and the dark building shadow effect. To address this problem, we proposed an automated urban water extraction method (UWEM which combines a new water index, together with a building shadow detection method. Firstly, we trained the parameters of UWEM using ZY-3 imagery of Qingdao, China. Then we verified the algorithm using five other sub-scenes (Aksu, Fuzhou, Hanyang, Huangpo and Huainan ZY-3 imagery. The performance was compared with that of the Normalized Difference Water Index (NDWI. Results indicated that UWEM performed significantly better at the sub-scenes with kappa coefficients improved by 7.87%, 32.35%, 12.64%, 29.72%, 14.29%, respectively, and total omission and commission error reduced by 61.53%, 65.74%, 83.51%, 82.44%, and 74.40%, respectively. Furthermore, UWEM has more stable performances than NDWI’s in a range of thresholds near zero. It reduces the over- and under-estimation issues which often accompany previous water indices when mapping urban surface water under complex environmental conditions.

  17. Non-inferiority of pulsed xenon UV light versus bleach for reducing environmental Clostridium difficile contamination on high-touch surfaces in Clostridium difficile infection isolation rooms

    National Research Council Canada - National Science Library

    Ghantoji, Shashank S; Stibich, Mark; Stachowiak, Julie; Cantu, Sherry; Adachi, Javier A; Raad, Issam I; Chemaly, Roy F

    2015-01-01

    ... % of sodium hypochlorite. Pulsed xenon UV light (PX-UV) is a means of quickly producing germicidal UV that has been shown to be effective in reducing environmental contamination by C. difficile spores...

  18. A spectral invariant representation of spectral reflectance

    Science.gov (United States)

    Ibrahim, Abdelhameed; Tominaga, Shoji; Horiuchi, Takahiko

    2011-03-01

    Spectral image acquisition as well as color image is affected by several illumination factors such as shading, gloss, and specular highlight. Spectral invariant representations for these factors were proposed for the standard dichromatic reflection model of inhomogeneous dielectric materials. However, these representations are inadequate for other characteristic materials like metal. This paper proposes a more general spectral invariant representation for obtaining reliable spectral reflectance images. Our invariant representation is derived from the standard dichromatic reflection model for dielectric materials and the extended dichromatic reflection model for metals. We proof that the invariant formulas for spectral images of natural objects preserve spectral information and are invariant to highlights, shading, surface geometry, and illumination intensity. It is proved that the conventional spectral invariant technique can be applied to metals in addition to dielectric objects. Experimental results show that the proposed spectral invariant representation is effective for image segmentation.

  19. Avoided Crossing Patterns and Spectral Gaps of Surface Plasmon Modes in Gold Nano-Structures

    CERN Document Server

    Kolomenskii, Alexandre; Hembd, Jeshurun; Kolomenski, Andrei; Noel, John; Teizer, Winfried; Schuessler, Hans

    2010-01-01

    The transmission of ultrashort (7 fs) broadband laser pulses through periodic gold nano-structures is studied. The distribution of the transmitted light intensity over wavelength and angle shows an efficient coupling of the incident p-polarized light to two counter-propagating surface plasmon (SP) modes. As a result of the mode interaction, the avoided crossing patterns exhibit energy and momentum gaps, which depend on the configuration of the nano-structure and the wavelength. Variations of the widths of the SP resonances and an abrupt change of the mode interaction in the vicinity of the avoided crossing region are observed. These features are explained by the model of two coupled modes and a coupling change due to switching from the high frequency dark mode to the low frequency bright mode for increasing wavelength of the excitation light. PACS numbers: 73.20.Mf, 42.70.Qs, 42.25.-p,

  20. Spectral analysis of the low energy Auger emission from a (0 0 0 1) ruthenium surface

    Energy Technology Data Exchange (ETDEWEB)

    Czyzewski, Jerzy J.; Krajniak, Janusz

    2003-04-30

    The low energy Auger emission from a Ru(0 0 0 1) surface have been analysed by means of a cylindrical mirror analyser (CMA) within the range of the electron energy (E) from 27 to 37 eV as a function of the primary electron energy (E{sub p}), which was set from 170 to 450 eV in 20 eV steps. Three Auger transitions at following energies: 31.7, 33.8 and 36.4 eV, have been found due to application of the backscattering generation factor idea. Obtained results for the Auger transitions were verified by means of XPS results published by Fuggle et al. [Surf. Sci. 52 (1975) 521].

  1. Significant improvement of near-UV electroluminescence from ZnO quantum dot LEDs via coupling with carbon nanodot surface plasmons.

    Science.gov (United States)

    Zhang, Cen; Zhu, Feifei; Xu, Haiyang; Liu, Weizhen; Yang, Liu; Wang, Zhongqiang; Ma, Jiangang; Kang, Zhenhui; Liu, Yichun

    2017-10-05

    Short-wavelength LEDs, a hot research topic in modern optoelectronics, have attracted tremendous attention in recent years because of their great application potential in both civil and military domains. Compared to conventional metallic surface-plasmons (SPs), carbon nanodot (CD) SPs with less optical loss and low cost, broader SP resonant frequency and good biocompatibility are expected to provide more prominent luminescence enhancement for light emitters. Herein, SP-enhanced near-UV emission quantum dot LEDs (Q-LED) were fabricated via introducing CDs into p-GaN/Al2O3/ZnO Q-LEDs by optimizing the molar ratio of ZnO quantum dots to CDs and a significant enhancement (∼20-fold) of the near-UV electroluminescence (EL) intensity from the ZnO-based Q-LEDs was achieved. Time-resolved spectroscopy studies reveal that the observed luminescence enhancement arises due to the resonant coupling between ZnO excitons and CD SPs. The current study not only demonstrates a feasible way to acquire near-UV emission from all-inorganic Q-LEDs, but also provides an effective strategy to enhance the EL intensity of these QD light emitters, which can further be extended to other types of light-emitting devices to improve EL efficiency.

  2. Effects of VUV/UV radiation and oxygen radicals on low-temperature sterilization in surface-wave excited O{sub 2} plasma

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Ying; Singh, Mrityunjai K.; Ogino, Akihisa [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8561 (Japan); Nagatsu, Masaaki, E-mail: tmnagat@ipc.shizuoka.ac.j [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8561 (Japan)

    2010-04-30

    Effects of VUV/UV radiation and oxygen radicals on low-temperature sterilization in surface-wave excited O{sub 2} plasma were studied. To examine the effect of VUV/UV radiation on the inactivation of microorganisms, a small metal chamber covered with an optical filter at the top to block the radicals and allow the VUV/UV radiation was placed inside the plasma chamber. With a LiF and a glass filter, two different emission spectra above 120 nm (LiF filter) and above 300 nm (glass filter) were examined. The spores of Geobacillus stearothermophilus with a population of 2.5 x 10{sup 6} were put below the optical filter in the small chamber, which was filled with the oxygen gas at appropriate pressure or pumped down to 10{sup -3} Pa. The survival curve showed that the vacuum condition inside a small chamber with a LiF filter was more efficient than the same O{sub 2} gas pressure as that outside plasma chamber. From the SEM analysis of the spores, there was no obvious change in shape after plasma treatment with filter at vacuum condition. According to the present results, it is concluded that the etching effect by the oxygen radical is more efficient in inactivation process than the sterilizing effect by the VUV emission in the oxygen plasma.

  3. Synthesis, structural, spectral (FT-IR, FT-Ra, and UV-Vis), thermal, and density functional studies on p-methylaniline complexes of Mn(II), Co(II), and Ni(II) bromides

    Science.gov (United States)

    Bardakçı, Tayyibe; Altun, Ahmet; Golcuk, Kurtulus; Kumru, Mustafa

    2015-11-01

    Transition metal complexes of the form MBr2L2, where M = Mn(II), Co(II) and Ni(II); L = p-methylaniline, were prepared and characterized by elemental and thermogravimetric analyses, magnetic moment measurements, and UV-vis, FT-IR and FT-Raman spectral studies. Geometries, spin-state energetics, and vibrational spectra of the complexes were obtained at the B3LYP/def2-TZVP level. The present experimental and theoretical data suggest 5-coordinate polymeric bromide bridged structure for the Mn complex, distorted tetrahedral structure for the Co complex, and distorted octahedral coordination site for the Ni complex. The experimental FT-IR and FT-Raman bands of the complexes were assigned based on the computational results expressed in terms of internal coordinates with percent potential energy distributions. The vibrational spectra suggest that the coordination occurs via nitrogen atom of p-methylaniline. The thermal characteristics of the complexes indicate that their decompositions start through p-methylaniline.

  4. Surface spectral function of momentum-dependent pairing potentials in a topological insulator: application to CuxBi2Se3.

    Science.gov (United States)

    Chen, Liang; Wan, Shaolong

    2013-05-29

    We propose three possible momentum-dependent pairing potentials as candidates for topological superconductors (for example CuxBi2Se3), and calculate the surface spectral function and surface density of states with these pairing potentials. We find that the first two can give the same spectral functions as the fully gapped and node-contacted pairing potentials given by Fu and Berg (2010 Phys. Rev. Lett. 105 097001), and that the third one can obtain a topological non-trivial case in which there exists a flat Andreev bound state and which preserves the threefold rotation symmetry. We hope our proposals and results will be assessed by future experiment.

  5. Urban Surface Temperature Time Series Estimation at the Local Scale by Spatial-Spectral Unmixing of Satellite Observations

    Directory of Open Access Journals (Sweden)

    Zina Mitraka

    2015-04-01

    Full Text Available The study of urban climate requires frequent and accurate monitoring of land surface temperature (LST, at the local scale. Since currently, no space-borne sensor provides frequent thermal infrared imagery at high spatial resolution, the scientific community has focused on synergistic methods for retrieving LST that can be suitable for urban studies. Synergistic methods that combine the spatial structure of visible and near-infrared observations with the more frequent, but low-resolution surface temperature patterns derived by thermal infrared imagery provide excellent means for obtaining frequent LST estimates at the local scale in cities. In this study, a new approach based on spatial-spectral unmixing techniques was developed for improving the spatial resolution of thermal infrared observations and the subsequent LST estimation. The method was applied to an urban area in Crete, Greece, for the time period of one year. The results were evaluated against independent high-resolution LST datasets and found to be very promising, with RMSE less than 2 K in all cases. The developed approach has therefore a high potential to be operationally used in the near future, exploiting the Copernicus Sentinel (2 and 3 observations, to provide high spatio-temporal resolution LST estimates in cities.

  6. Electron dynamics in the normal state of cuprates: Spectral function, Fermi surface and ARPES data

    Science.gov (United States)

    Zubov, E. E.

    2016-11-01

    An influence of the electron-phonon interaction on excitation spectrum and damping in a narrow band electron subsystem of cuprates has been investigated. Within the framework of the t-J model an approach to solving a problem of account of both strong electron correlations and local electron-phonon binding with characteristic Einstein mode ω0 in the normal state has been presented. In approximation Hubbard-I it was found an exact solution for the polaron bands. We established that in the low-dimensional system with a pure kinematic part of Hamiltonian a complicated excitation spectrum is realized. It is determined mainly by peculiarities of the lattice Green's function. In the definite area of the electron concentration and hopping integrals a correlation gap may be possible on the Fermi level. Also, in specific cases it is observed a doping evolution of the Fermi surface. We found that the strong electron-phonon binding enforces a degree of coherence of electron-polaron excitations near the Fermi level and spectrum along the nodal direction depends on wave vector module weakly. It corresponds to ARPES data. A possible origin of the experimentally observed kink in the nodal direction of cuprates is explained by fine structure of the polaron band to be formed near the mode -ω0.

  7. Effects of prenatal exposure to surface-coated nanosized titanium dioxide (UV-Titan. A study in mice

    Directory of Open Access Journals (Sweden)

    Vibenholt Anni

    2010-06-01

    Full Text Available Abstract Background Engineered nanoparticles are smaller than 100 nm and designed to improve or achieve new physico-chemical properties. Consequently, also toxicological properties may change compared to the parent compound. We examined developmental and neurobehavioral effects following maternal exposure to a nanoparticulate UV-filter (UV-titan L181. Methods Time-mated mice (C57BL/6BomTac were exposed by inhalation 1h/day to 42 mg/m3 aerosolized powder (1.7·106 n/cm3; peak-size: 97 nm on gestation days 8-18. Endpoints included: maternal lung inflammation; gestational and litter parameters; offspring neurofunction and fertility. Physicochemical particle properties were determined to provide information on specific exposure and deposition. Results Particles consisted of mainly elongated rutile titanium dioxide (TiO2 with an average crystallite size of 21 nm, modified with Al, Si and Zr, and coated with polyalcohols. In exposed adult mice, 38 mg Ti/kg was detected in the lungs on day 5 and differential cell counts of bronchoalveolar lavage fluid revealed lung inflammation 5 and 26-27 days following exposure termination, relative to control mice. As young adults, prenatally exposed offspring tended to avoid the central zone of the open field and exposed female offspring displayed enhanced prepulse inhibition. Cognitive function was unaffected (Morris water maze test. Conclusion Inhalation exposure to nano-sized UV Titan dusts induced long term lung inflammation in time-mated adult female mice. Gestationally exposed offspring displayed moderate neurobehavioral alterations. The results are discussed in the light of the observed particle size distribution in the exposure atmosphere and the potential pathways by which nanoparticles may impart changes in fetal development.

  8. Doping effect of L-cystine on structural, UV-visible, SHG efficiency, third order nonlinear optical, laser damage threshold and surface properties of cadmium thiourea acetate single crystal

    Science.gov (United States)

    Azhar, S. M.; Anis, Mohd; Hussaini, S. S.; Kalainathan, S.; Shirsat, M. D.; Rabbani, G.

    2017-01-01

    The present article is focused to investigate the influence of L-cystine (LC) on linear-non-linear optical and laser damage threshold of cadmium thiourea acetate (CTA) crystal. The structural parameters of pure and LC doped CTA crystals have been determined using the single crystal X-ray diffraction technique. The functional groups of grown crystals have been identified by means of fourier transform infrared (FT-IR) analysis. The UV-visible spectral analysis has been done in the range of 200-900 nm to ascertain the uplifting influence of LC on optical properties of CTA crystal. The second harmonic generation (SHG) efficiency of LC doped CTA crystal is found to be higher than CTA and KDP crystal. The Z-scan technique has been employed to determine the third order nonlinear optical (TONLO) nature of LC doped CTA crystal at 632.8 nm. The self focusing tendency confirmed the strong kerr lensing ability of LC doped CTA crystal. The TONLO susceptibility (χ3), refraction (n2) and absorption coefficient (β) has been calculated using the Z-scan data. The laser damage threshold of pure and LC doped CTA crystals has been measured using the Q-switched Nd:YAG laser and its is found to be in range of GW/cm2. The surface analysis has been done by means of etching studies.

  9. Muscle fatigue in women with primary biliary cirrhosis: Spectral analysis of surface electromyography

    Institute of Scientific and Technical Information of China (English)

    Maria Rosa Biagini; Alessandro Tozzi; Antonello Grippo; Andrea Galli; Stefano Milani; Aldo Amantini

    2006-01-01

    AIM: To evaluate the myoelectric manifestations of peripheral fatigability in patients with primary biliary cirrhosis in comparison to healthy subjects. METHODS: Sixteen women with primary biliary cirrhosis without comorbidity and 13 healthy women matched for age and body mass index (BMI) completed the self reported questionnaire fatigue impact scale. All subjects underwent surface electromyography assessment of peripheral fatigability. Anterior tibial muscle isometric voluntary contraction was executed for 20 s at 80% of maximal voluntary isometric contraction. During the exercise electromyographic signal series were recorded and root mean square (expression of central drive) as well as mean and median of electromyographic signal frequency spectrum (estimates of muscle fatigability) were computed. Each subject executed the trial two times. EMG parameters were normalized, then linear regression was applied and slopes were calculated. RESULTS: Seven patients were fatigued (median fatigue impact scale score: 38, range: 26-66) and 9 were not fatigued (median fatigue impact scale score: 7, range: 0-17). The maximal voluntary isometric contraction was similar in patients (82, 54-115 N) and controls (87,74-101 N), and in patients with high (81, 54-115 N) and low fatigue impact scale scores (86, 65-106 N). Root mean square as well as mean and median of frequency spectrum slopes were compared with the Mann-Whitney U test, and no significant difference was found between fatigued and non-fatigued patients and controls. CONCLUSION: No instrumental evidence of peripheral fatigability can be found in women with primary biliary cirrhosis but no comorbidity, suggesting that fatigue in such patients may be of central origin.

  10. Using Coupled Nonnegative Matrix Factorization (cnmf) Un-Mixing for High Spectral and Spatial Resolution Data Fusion to Estimate Urban Impervious Surface and Urban Ecological Environment

    Science.gov (United States)

    Wang, T.; Zhang, H.; Lin, H.

    2017-09-01

    surfaces has increasingly roused widely interests of researchers in monitoring urban development and determining the overall environmental health of a watershed. However, studies on the impervious surface using multi-spectral imageries is insufficient and inaccurate due to the complexity of urban infrastructures base on the need to further recognize these impervious surface materials in a finer scale. Hyperspectral imageries have been proved to be sensitive to subtle spectral differences thus capable to exquisitely discriminate these similar materials while limited to the low spatial resolution. Coupled nonnegative matrix factorization (CNMF) unmixing method is one of the most physically straightforward and easily complemented hyperspectral pan-sharpening methods that could produce fused data with both high spectral and spatial resolution. This paper aimed to exploit the latent capacity and tentative validation of CNMF on the killer application of mapping urban impervious surfaces in complexed metropolitan environments like Hong Kong. Experiments showed that the fusion of high spectral and spatial resolution image could provide more accurate and comprehensive information on urban impervious surface estimation.

  11. Laser irradiation induced spectral evolution of the Laser irradiation induced spectral evolution of the surface-enhanced Raman scattering(SERS)of 4-tert-butylbenzylmercaptan on gold nanoparticles assembly

    Institute of Scientific and Technical Information of China (English)

    TONG LianMing; ZHU Tao; LIU ZhongFan

    2007-01-01

    The spectral evolution of the surface-enhanced Raman scattering (SERS) of 4-tert-butylbenzylmer-captan(4-tBBM)on gold nanopanlcles assembly under laser irradiation is reported.The reIative intensities of typical peaks in the spectrum of 4-tBBM gradually change with irradiation time.Comparison of the rate of spectral changes under several experimental conditions indicates that the surface plasmon resonance(SPR)induced heat in the gold nanoparticles assembly is the origin of the spectraI evolution.During the process of self-assembly,4-tBBM molecules do not form a compact ordered monolayer because of the spatial hindrance of the 4-tert-butyl end group.The heat induced by laser irradiation drives the 4-tBBM molecules to rearrange to a more stable orientation.

  12. A Feasibility Study for Measuring Accurate Chest Compression Depth and Rate on Soft Surfaces Using Two Accelerometers and Spectral Analysis

    Directory of Open Access Journals (Sweden)

    Sofía Ruiz de Gauna

    2016-01-01

    Full Text Available Background. Cardiopulmonary resuscitation (CPR feedback devices are being increasingly used. However, current accelerometer-based devices overestimate chest displacement when CPR is performed on soft surfaces, which may lead to insufficient compression depth. Aim. To assess the performance of a new algorithm for measuring compression depth and rate based on two accelerometers in a simulated resuscitation scenario. Materials and Methods. Compressions were provided to a manikin on two mattresses, foam and sprung, with and without a backboard. One accelerometer was placed on the chest and the second at the manikin’s back. Chest displacement and mattress displacement were calculated from the spectral analysis of the corresponding acceleration every 2 seconds and subtracted to compute the actual sternal-spinal displacement. Compression rate was obtained from the chest acceleration. Results. Median unsigned error in depth was 2.1 mm (4.4%. Error was 2.4 mm in the foam and 1.7 mm in the sprung mattress (p<0.001. Error was 3.1/2.0 mm and 1.8/1.6 mm with/without backboard for foam and sprung, respectively (p<0.001. Median error in rate was 0.9 cpm (1.0%, with no significant differences between test conditions. Conclusion. The system provided accurate feedback on chest compression depth and rate on soft surfaces. Our solution compensated mattress displacement, avoiding overestimation of compression depth when CPR is performed on soft surfaces.

  13. Laser irradiation induced spectral evolution of the surface-enhanced Raman scattering(SERS) of 4-tert-butylbenzylmercaptan on gold nanoparticles assembly

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The spectral evolution of the surface-enhanced Raman scattering (SERS) of 4-tert-butylbenzylmer-captan (4-tBBM) on gold nanoparticles assembly under laser irradiation is reported. The relative intensities of typical peaks in the spectrum of 4-tBBM gradually change with irradiation time. Comparison of the rate of spectral changes under several experimental conditions indicates that the surface plasmon resonance (SPR) induced heat in the gold nanoparticles assembly is the origin of the spectral evolution. During the process of self-assembly, 4-tBBM molecules do not form a compact ordered monolayer because of the spatial hindrance of the 4-tert-butyl end group. The heat induced by laser irradiation drives the 4-tBBM molecules to rearrange to a more stable orientation.

  14. Alterations in Spectral Attributes of Surface Electromyograms after Utilization of a Foot Drop Stimulator during Post-Stroke Gait

    Directory of Open Access Journals (Sweden)

    Rakesh Pilkar

    2017-08-01

    Full Text Available BackgroundA foot drop stimulator (FDS is a rehabilitation intervention that stimulates the common peroneal nerve to facilitate ankle dorsiflexion at the appropriate time during post-stroke hemiplegic gait. Time–frequency analysis (TFA of non-stationary surface electromyograms (EMG and spectral variables such as instantaneous mean frequency (IMNF can provide valuable information on the long-term effects of FDS intervention in terms of changes in the motor unit (MU recruitment during gait, secondary to improved dorsiflexion.ObjectiveThe aim of this study was to apply a wavelet-based TFA approach to assess the changes in neuromuscular activation of the tibialis anterior (TA, soleus (SOL, and gastrocnemius (GA muscles after utilization of an FDS during gait post-stroke.MethodsSurface EMG were collected bilaterally from the TA, SOL, and GA muscles from six participants (142.9 ± 103.3 months post-stroke while walking without the FDS at baseline and 6 months post-FDS utilization. Continuous wavelet transform was performed to get the averaged time–frequency distribution of band pass filtered (20–300 Hz EMGs during multiple walking trials. IMNFs were computed during normalized gait and were averaged during the stance and swing phases. Percent changes in the energies associated with each frequency band of 25 Hz between 25 and 300 Hz were computed and compared between visits.ResultsAveraged time–frequency representations of the affected TA, SOL, and GA EMG show altered spectral attributes post-FDS utilization during normalized gait. The mean IMNF values for the affected TA were significantly lower than the unaffected TA at baseline (p = 0.026 and follow-up (p = 0.038 during normalized stance. The mean IMNF values significantly increased (p = 0.017 for the affected GA at follow-up during normalized swing. The frequency band of 250–275 Hz significantly increased in the energies post-FDS utilization for all muscles

  15. Synthesis, spectral and surface investigation of NaSrBO{sub 3}: Sm{sup 3+} phosphor for full color down conversion in LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vinay, E-mail: vinaykdhiman@yahoo.com [School of Physics, Shri Mata Vaishno Devi University, Katra 182320 (J and K) (India); Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300 (South Africa); Bedyal, A.K. [School of Physics, Shri Mata Vaishno Devi University, Katra 182320 (J and K) (India); Pitale, Shreyas S.; Ntwaeaborwa, O.M.; Swart, H.C. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300 (South Africa)

    2013-03-25

    Highlights: ► Suitability of present phosphors as a down conversion phosphor to fill the “yellow gap” has been explored. ► Special attention was given to check its utility to fill the 590–600 nm region (amber range). ► X-ray photoelectron spectroscopy was used to study the surface properties. ► A special analytical technique TOF-SIMS was used for studying the doping distribution. ► The images suggested a uniform distribution of the Sm{sup 3+} ions in the NaSrBO{sub 3}. -- Abstract: Orange–red emitting NaSrBO{sub 3}: Sm{sup 3+} phosphors were prepared by the combustion method using metal nitrates as precursors and urea as fuel. The particle sizes were in the range of 38–43 nm. The monoclinic structure that is in good agreement with the standard NaSrBO{sub 3} was confirmed by X-ray diffraction. Scanning electron microscopy (SEM) indicated that an agglomerated peanut like morphology was obtained. UV–VIS spectrocsopy, photoluminescence (PL) and cathodoluminescence (CL) spectroscopy were utilized to investigate the spectral properties of the phosphor. The chemical states and the distribution of the dopants in the host were analysed with X-ray photoelectron spectroscopy (XPS) and time of flight-secondary ion mass spectroscopy (TOF-SIMS), respectively. Under the excitation of near UV light, NaSrBO{sub 3}: Sm{sup 3+} exhibits the characteristic emissions resulting for the {sup 4}G{sub 5/2} → {sup 6}H{sub x/2} (x = 5, 7 and 9) transitions of Sm{sup 3+}, with a maximum intensity at 599 nm. In addition, the concentration of Sm{sup 3+} was varied in order to determine the optimum PL emission intensity. A maximum intensity was obtained from the sample with 2.0 mol% of Sm{sup 3+}. The potential applications of this phosphor, as a down conversion phosphor with an excitation wavelength of 395 nm and good CL intensity, are evaluated for the possible use as a high-color-purity phosphor in light emitting diodes (LEDs) that can fill the 590–600 nm gap and it

  16. TEMIS UV product validation using NILU-UV ground-based measurements in Thessaloniki, Greece

    Science.gov (United States)

    Zempila, Melina-Maria; van Geffen, Jos H. G. M.; Taylor, Michael; Fountoulakis, Ilias; Koukouli, Maria-Elissavet; van Weele, Michiel; van der A, Ronald J.; Bais, Alkiviadis; Meleti, Charikleia; Balis, Dimitrios

    2017-06-01

    This study aims to cross-validate ground-based and satellite-based models of three photobiological UV effective dose products: the Commission Internationale de l'Éclairage (CIE) erythemal UV, the production of vitamin D in the skin, and DNA damage, using high-temporal-resolution surface-based measurements of solar UV spectral irradiances from a synergy of instruments and models. The satellite-based Tropospheric Emission Monitoring Internet Service (TEMIS; version 1.4) UV daily dose data products were evaluated over the period 2009 to 2014 with ground-based data from a Norsk Institutt for Luftforskning (NILU)-UV multifilter radiometer located at the northern midlatitude super-site of the Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki (LAP/AUTh), in Greece. For the NILU-UV effective dose rates retrieval algorithm, a neural network (NN) was trained to learn the nonlinear functional relation between NILU-UV irradiances and collocated Brewer-based photobiological effective dose products. Then the algorithm was subjected to sensitivity analysis and validation. The correlation of the NN estimates with target outputs was high (r = 0. 988 to 0.990) and with a very low bias (0.000 to 0.011 in absolute units) proving the robustness of the NN algorithm. For further evaluation of the NILU NN-derived products, retrievals of the vitamin D and DNA-damage effective doses from a collocated Yankee Environmental Systems (YES) UVB-1 pyranometer were used. For cloud-free days, differences in the derived UV doses are better than 2 % for all UV dose products, revealing the reference quality of the ground-based UV doses at Thessaloniki from the NILU-UV NN retrievals. The TEMIS UV doses used in this study are derived from ozone measurements by the SCIAMACHY/Envisat and GOME2/MetOp-A satellite instruments, over the European domain in combination with SEVIRI/Meteosat-based diurnal cycle of the cloud cover fraction per 0. 5° × 0. 5° (lat × long) grid cells. TEMIS

  17. The research of air pollution based on spectral features in leaf surface of Ficus microcarpa in Guangzhou, China.

    Science.gov (United States)

    Wang, Jie; Xu, Ruisong; Ma, Yueliang; Miao, Li; Cai, Rui; Chen, Yu

    2008-07-01

    Nowadays development of industry and traffic are the main contributor to city air pollution in the city of GuangZhou, China. Conventional methods for investigating atmosphere potentially harmful element pollution based on sampling and chemical analysis are time and labor consuming and relatively expensive. Reflectance spectroscopy within the visible-near-infrared region of vegetation in city has been widely used to predict atmosphere constituents due to its rapidity, convenience and accuracy. The objective of this study was to examine the possibility of using leaves reflectance spectra of vegetation as a rapid method to simultaneously assess pollutant (S, Cd, Cu, Hg, Pb, XCl, XF) in the atmosphere of the Guangzhou area. This article has studied the spectral features of polluted leaf surface of Ficus microcarpa in 1985 and 1998. According to the analysis, comprehensive assessment for the change of atmospheric condition and degrees of pollution were given. This conclusion was confirmed by the monitored data got from chemical analysis. Future study with real remote sensing data and field measurements were strongly recommended.

  18. High performance spectral-phase surface plasmon resonance biosensors based on single- and double-layer schemes

    Science.gov (United States)

    Wang, Cheng; Ho, Ho-Pui; Shum, Ping

    2013-03-01

    We have investigated the surface plasmon resonance (SPR) phase change across a range of excitation wavelengths (i.e. spectral-phase) using the Fresnel's equations and Transfer Matrix technique with emphasis on optimizing refractive index sensing performance. Having evaluated the phase change characteristics upon varying different sets of parameters, our results indicate the possibility of achieving extremely high resolution within a wide range of sample refractive index (1.3330-1.3505) at a fixed angle of incidence. We also demonstrate that the double-layer (silver/gold or copper/gold) configuration holds very promising characteristics for SPR sensing, and it is possible to achieve a detection limit of 7.9×10-9 RIU (refractive index unit) if one uses a phase measurement resolution of 2×10-4 rad. Among all the factors, material of the metal film and its thickness are found to affect performance most. This work provides a comprehensive analysis of the interplay between various system parameters.