Science.gov

Sample records for absorption spectral characteristics

  1. Absorption spectroscopy setup for determination of whole human blood and blood-derived materials spectral characteristics

    NASA Astrophysics Data System (ADS)

    Wróbel, M. S.; Gnyba, M.; Milewska, D.; Mitura, K.; Karpienko, K.

    2015-09-01

    A dedicated absorption spectroscopy system was set up using tungsten-halogen broadband source, optical fibers, sample holder, and a commercial spectrometer with CCD array. Analysis of noise present in the setup was carried out. Data processing was applied to the absorption spectra to reduce spectral noise, and improve the quality of the spectra and to remove the baseline level. The absorption spectra were measured for whole blood samples, separated components: plasma, saline, washed erythrocytes in saline and human whole blood with biomarkers - biocompatible nanodiamonds (ND). Blood samples had been derived from a number of healthy donors. The results prove a correct setup arrangement, with adequate preprocessing of the data. The results of blood-ND mixtures measurements show no toxic effect on blood cells, which proves the NDs as a potential biocompatible biomarkers.

  2. Test of spectral emission and absorption characteristics of active optical fibers by direct side pumping.

    PubMed

    Zhang, Jianzhong; Luo, Yanhua; Sathi, Zinat M; Azadpeyma, Nilram; Peng, Gang-Ding

    2012-08-27

    Emission and absorption are two main properties of active optical fibers that are important for fiber amplifiers and lasers. We propose a direct side pumping scheme for non-deconstructive evaluation of active optical fibers. This scheme enables a simple in situ test of both emission and absorption characteristics without cutting fiber and produces good accuracy with very low pumping background. A commercial Er-doped fiber and a home-made Bi/Er co-doped optical fiber have been tested to demonstrate that the scheme is a useful alternative technique for characterizing active optical fiber or waveguides.

  3. Molar absorptivity (ε) and spectral characteristics of cyanidin-based anthocyanins from red cabbage.

    PubMed

    Ahmadiani, Neda; Robbins, Rebecca J; Collins, Thomas M; Giusti, M Monica

    2016-04-15

    Red cabbage extract contains mono and di-acylated cyanidin (Cy) anthocyanins and is often used as food colorants. Our objectives were to determine the molar absorptivity (ε) of different red cabbage Cy-derivatives and to evaluate their spectral behaviors in acidified methanol (MeOH) and buffers pH 1-9. Major red cabbage anthocyanins were isolated using a semi-preparatory HPLC, dried and weighed. Pigments were dissolved in MeOH and diluted with either MeOH (0.1% HCl) or buffers to obtain final concentrations between 5×10(-5) and 1×10(-3) mol/L. Spectra were recorded and ε calculated using Lambert-Beer's law. The ε in acidified MeOH and buffer pH 1 ranged between ~16,000-30,000 and ~13,000-26,000 L/mol cm, respectively. Most pigments showed higher ε in pH 8 than pH 2, and lowest ε between pH 4 and 6. There were bathochromic shifts (81-105 nm) from pH 1 to 8 and hypsochromic shifts from pH 8 to 9 (2-19 nm). Anthocyanins molecular structures and the media were important variables which greatly influenced their ε and spectral behaviors.

  4. Absorption spectra and spectral-kinetic characteristics of the fluorescence of Sanguinarine in complexes with polyelectrolytes and DNA

    NASA Astrophysics Data System (ADS)

    Motevich, I. G.; Strekal, N. D.; Nowicky, J. W.; Maskevich, S. A.

    2010-07-01

    The absorption spectra and stationary and time resolved fluorescence spectra of the isoquinoline alkaloid sanguinarine are studied in aqueous media and during interactions with synthetic polyelectrolytes (polystyrene sulfonate and polyallylamine) and a natural polyelectrolyte (DNA).

  5. SPECTRAL RELATIVE ABSORPTION DIFFERENCE METHOD

    SciTech Connect

    Salaymeh, S.

    2010-06-17

    When analyzing field data, the uncertainty in the background continuum emission produces the majority of error in the final gamma-source analysis. The background emission typically dominates an observed spectrum in terms of counts and is highly variable spatially and temporally. The majority of the spectral shape of the background continuum is produced by combinations of cosmic rays, {sup 40}K, {sup 235}U, and {sup 220}Rn, and the continuum is similar in shape to the 15%-20% level for most field observations. However, the goal of spectroscopy analysis is to pick up subtle peaks (<%5) upon this large background. Because the continuum is falling off as energy increases, peak detection algorithms must first define the background surrounding the peak. This definition is difficult when the range of background shapes is considered. The full spectral template matching algorithms are heavily weighted to solving for the background continuum as it produces significant counts over much of the energy range. The most appropriate background mitigation technique is to take a separate background observation without the source of interest. But, it is frequently not possible to record a background observation in the exact location before (or after) a source has been detected. Thus, one uses approximate backgrounds that rely on spatially nearby locations or similar environments. Since the error in many field observations is dominated by the background, a technique that is less sensitive to the background would be quite beneficial. We report the result of an initial investigation into a novel observation scheme for gamma-emission detection in high background environments. Employing low resolution, NaI, detectors, we examine the different between the direct emission and the 'spectral-shadow' that the gamma emission produces when passed through a thin absorber. For this detection scheme to be competitive, it is required to count and analyze individual gamma-events. We describe the

  6. [Spectral calibration of hyperspectral imager based on spectral absorption target].

    PubMed

    Gou, Zhi-Yang; Yan, Lei; Chen, Wei; Zhao, Hong-Ying; Yin, Zhong-Yi; Duan, Yi-Ni

    2013-02-01

    Retrieval of center wavelength and bandwidth is a key step for quantitative analysis of hyperspectral data. The present paper proposes a spectral calibration method of hyperspectral imager, whose spectrum covers visible and near-infrared band, using spectral absorption target. Ground calibration experiment was designed for a hyperspectral imager with a bandwidth of 6 nm. Hyperspectral imager and ASD spectrometer measured the same spectral absorption target synchronously. Reflectance spectrum was derived from the different data set. Center wavelength and bandwidth were retrieved by matching the reflectance data from hyperspectral imager and ASD spectrometer. The experiment result shows that this method can be applied in spectral calibration of hyperspectral imagers to improve the quantitative studies on hyperspectral imagery.

  7. Acoustic Absorption Characteristics of People.

    ERIC Educational Resources Information Center

    Kingsbury, H. F.; Wallace, W. J.

    1968-01-01

    The acoustic absorption characteristics of informally dressed college students in typical classroom seating are shown to differ substantially from data for formally dressed audiences in upholstered seating. Absorption data, expressed as sabins per person or absorption coefficient per square foot, shows that there is considerable variation between…

  8. Molecular absorption in transition region spectral lines

    NASA Astrophysics Data System (ADS)

    Schmit, D. J.; Innes, D.; Ayres, T.; Peter, H.; Curdt, W.; Jaeggli, S.

    2014-09-01

    Aims: We present observations from the Interface Region Imaging Spectrograph (IRIS) of absorption features from a multitude of cool atomic and molecular lines within the profiles of Si IV transition region lines. Many of these spectral lines have not previously been detected in solar spectra. Methods: We examined spectra taken from deep exposures of plage on 12 October 2013. We observed unique absorption spectra over a magnetic element which is bright in transition region line emission and the ultraviolet continuum. We compared the absorption spectra with emission spectra that is likely related to fluorescence. Results: The absorption features require a population of sub-5000 K plasma to exist above the transition region. This peculiar stratification is an extreme deviation from the canonical structure of the chromosphere-corona boundary. The cool material is not associated with a filament or discernible coronal rain. This suggests that molecules may form in the upper solar atmosphere on small spatial scales and introduces a new complexity into our understanding of solar thermal structure. It lends credence to previous numerical studies that found evidence for elevated pockets of cool gas in the chromosphere. Movies associated to Figs. 1 and 2 are available in electronic form at http://www.aanda.org

  9. Spectral absorption coefficients of argon and silicon and spectral reflectivity of aluminum

    NASA Technical Reports Server (NTRS)

    Krascella, N. L.

    1972-01-01

    A theoretical investigation was conducted to estimate the spectral properties of argon as a function of pressure, temperature, and wave number. The spectral characteristics of the argon buffer gas exert a strong influence on radiative energy transfer in the in-reactor test configuration of the nuclear light bulb engine. An existing computer program was modified and used to calculate the spectral absorption coefficients of argon at total pressures of 50, 100, 250, 500, 750 and 1000 atm in the temperature interval between 1000 and 30,000 K. At each pressure and temperature, spectral properties were calculated for forty-seven wave numbers in the interval between 1000 and 1,000,000 cm/1. Estimates of the spectral absorption coefficients of silicon were made as part of an evaluation of silicon vapor as a possible buffer-gas seeding agent for the reference nuclear light bulb engine. Existing cross-section data were used to calculate the spectral characteristics of silicon at twenty-four temperatures in the interval between 2000 and 10,000 K.

  10. Spectrophotometer spectral bandwidth calibration with absorption bands crystal standard.

    PubMed

    Soares, O D; Costa, J L

    1999-04-01

    A procedure for calibration of a spectral bandwidth standard for high-resolution spectrophotometers is described. Symmetrical absorption bands for a crystal standard are adopted. The method relies on spectral band shape fitting followed by a convolution with the slit function of the spectrophotometer. A reference spectrophotometer is used to calibrate the spectral bandwidth standard. Bandwidth calibration curves for a minimum spectral transmission factor relative to the spectral bandwidth of the reference spectrophotometer are derived for the absorption bands at the wavelength of the band absorption maximum. The family of these calibration curves characterizes the spectral bandwidth standard. We calibrate the spectral bandwidth of a spectrophotometer with respect to the reference spectrophotometer by determining the spectral transmission factor minimum at every calibrated absorption band of the bandwidth standard for the nominal instrument values of the spectral bandwidth. With reference to the standard spectral bandwidth calibration curves, the relation of the spectral bandwidth to the reference spectrophotometer is determined. We determine the discrepancy in the spectrophotometers' spectral bandwidths by averaging the spectral bandwidth discrepancies relative to the standard calibrated values found at the absorption bands considered. A weighted average of the uncertainties is taken.

  11. SOUL in mouse eyes is a new hexameric heme-binding protein with characteristic optical absorption, resonance Raman spectral, and heme-binding properties.

    PubMed

    Sato, Emiko; Sagami, Ikuko; Uchida, Takeshi; Sato, Akira; Kitagawa, Teizo; Igarashi, Jotaro; Shimizu, Toru

    2004-11-09

    SOUL is specifically expressed in the retina and pineal gland and displays more than 40% sequence homology with p22HBP, a heme protein ubiquitously expressed in numerous tissues. SOUL was purified as a dimer in the absence of heme from the Escherichia coli expression system but displayed a hexameric structure upon heme binding. Heme-bound SOUL displayed optical absorption and resonance Raman spectra typical of 6-coordinate low-spin heme protein, with one heme per monomeric unit for both the Fe(III) and Fe(II) complexes. Spectral data additionally suggest that one of the axial ligands of the Fe(III) heme complex is His. Mutation of His42 (the only His of SOUL) to Ala resulted in loss of heme binding, confirming that this residue is an axial ligand of SOUL. The K(d) value of heme for SOUL was estimated as 4.8 x 10(-9) M from the association and dissociation rate constants, suggesting high binding affinity. On the other hand, p22HBP was obtained as a monomer containing one heme per subunit, with a K(d) value of 2.1 x 10(-11) M. Spectra of heme-bound p22HBP were different from those of SOUL but similar to those of heme-bound bovine serum albumin in which heme bound to a hydrophobic cavity with no specific axial ligand coordination. Therefore, the heme-binding properties and coordination structure of SOUL are distinct from those of p22HBP, despite high sequence homology. The physiological role of the new heme-binding protein, SOUL, is further discussed in this report.

  12. Spectral Characteristics of Titan's Surface

    NASA Astrophysics Data System (ADS)

    Griffith, Caitlin A.; Turner, Jake D.; Penteado, Paulo; Khamsi, Tymon B.; Soderblom, Jason M.

    2014-11-01

    Cassini/Huygens and ground-based measurements of Titan reveal an eroded surface, with lakes, dunes, and sinuous washes. These features, coupled with measurements of clouds and rain, indicate the transfer of methane between Titan’s surface and atmosphere. The presence of methane-damp lowlands suggests further that the atmospheric methane (which is continually depleted through photolysis) may be supplied by sub-surface reservoirs. The byproducts of methane photolysis condense onto the surface, leaving layers of organic sediments that record Titan’s past atmospheres.Thus knowledge of the source and history of Titan's atmosphere requires measurements of the large scale compositional makeup of Titan's surface, which is shrouded by a thick and hazy atmosphere. Towards this goal, we analyzed roughly 100,000 spectra recorded by Cassini’s Visual and Infrared Mapping Spectrometer (VIMS). Our study is confined to the latitude region (20S—20N) surrounding the landing site of the Huygens probe (at 10S, 192W), which supplied only measurement of the vertical profiles of the methane abundance and haze scattering characteristics. VIMS near-IR spectral images indicate subtle latitudinal and temporal variations in the haze characteristics in the tropics. We constrain these small changes with full radiative transfer analyses of each of the thousands of VIMS spectra, which were recorded of different terrains and at different lighting conditions. The resulting models of Titan’s atmosphere as a function of latitude and year indicate the seasonal migration of Titan’s tropical haze and enable the derivation of Titan’s surface albedo at 8 near-IR wavelength regions where Titan’s atmosphere is transparent enough to allow visibility to the surface. The resultant maps of Titan’s surface indicate a number of terrain types with distinct spectral characteristics that are suggestive of atmospheric and surficial processes, including the deposition of organic material, erosion of

  13. Determination of the in-flight spectral calibration of AVIRIS using atmospheric absorption features

    NASA Astrophysics Data System (ADS)

    Green, Robert O.

    1995-01-01

    Spectral calibration of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) as data are acquired in flight is essential to quantitative analysis of the measured upwelling spectral radiance. In each spectrum measured by AVIRIS in flight, there are numerous atmospheric gas absorption bands that drive this requirement for accurate spectral calibration. If the surface and atmospheric properties are measured independently, these atmospheric absorption bands may be used to deduce the in-flight spectral calibration of an imaging spectrometer. Both the surface and atmospheric characteristics were measured for a calibration target during an in-flight calibration experiment held at Lunar Lake, Nevada on April 5, 1994. This paper uses upwelling spectral radiance predicted for the calibration target with the MODTRAN radiative transfer code to validate the spectral calibration of AVIRIS in flight.

  14. Liquid optical phantoms mimicking spectral characteristics of laboratory mouse biotissues

    NASA Astrophysics Data System (ADS)

    Loginova, D. A.; Sergeeva, E. A.; Krainov, A. D.; Agrba, P. D.; Kirillin, M. Yu

    2016-06-01

    Optical phantoms mimicking optical properties of real biotissues in the visible and IR spectral regions are developed based on measurements of the spectral characteristics of ex vivo samples of laboratory mouse biotissues. The phantoms are composed of aqueous solutions of Lipofundin, Indian ink and red ink with different spectral characteristics. The deviations of the measured absorption and scattering coefficients of phantoms in the wavelength range 480 - 580 nm from the corresponding values for real biotissues do not exceed 25% and 2%, respectively. For phantoms in the wavelength region 580 - 880 nm, the deviations of the absorption coefficient do not exceed 40% and the deviations of the scattering coefficient do not exceed 25%. These values, in general, fall within the range of variations for different individual mice of one strain.

  15. Spectral characteristics of Shuttle glow

    NASA Technical Reports Server (NTRS)

    Viereck, R. A.; Mende, S. B.; Murad, E.; Swenson, G. R.; Pike, C. P.; Culbertson, F. L.; Springer, R. C.

    1992-01-01

    The glowing cloud near the ram surfaces of the Space Shuttle was observed with a hand-held, intensified spectrograph operated by the astronauts from the aft-flight-deck of the Space Shuttle. The spectral measurements were made between 400 and 800 nm with a resolution of 3 nm. Analysis of the spectral response of the instrument and the transmission of the Shuttle window was performed on orbit using earth-airglow OH Meinel bands. This analysis resulted in a correction of the Shuttle glow intensity in the spectral region between 700 and 800 nm. The data presented in this report is in better agreement with laboratory measurements of the NO2 continuum.

  16. Analyte-induced spectral filtering in femtosecond transient absorption spectroscopy

    DOE PAGES

    Abraham, Baxter; Nieto-Pescador, Jesus; Gundlach, Lars

    2017-03-06

    Here, we discuss the influence of spectral filtering by samples in femtosecond transient absorption measurements. Commercial instruments for transient absorption spectroscopy (TA) have become increasingly available to scientists in recent years and TA is becoming an established technique to measure the dynamics of photoexcited systems. Furthermore, we show that absorption of the excitation pulse by the sample can severely alter the spectrum and consequently the temporal pulse shape. This “spectral self-filtering” effect can lead to systematic errors and misinterpretation of data, most notably in concentration dependent measurements. Finally, the combination of narrow absorption peaks in the sample with ultrafast broadbandmore » excitation pulses is especially prone to this effect.« less

  17. Soil classification basing on the spectral characteristics of topsoil samples

    NASA Astrophysics Data System (ADS)

    Liu, Huanjun; Zhang, Xiaokang; Zhang, Xinle

    2016-04-01

    Soil taxonomy plays an important role in soil utility and management, but China has only course soil map created based on 1980s data. New technology, e.g. spectroscopy, could simplify soil classification. The study try to classify soils basing on the spectral characteristics of topsoil samples. 148 topsoil samples of typical soils, including Black soil, Chernozem, Blown soil and Meadow soil, were collected from Songnen plain, Northeast China, and the room spectral reflectance in the visible and near infrared region (400-2500 nm) were processed with weighted moving average, resampling technique, and continuum removal. Spectral indices were extracted from soil spectral characteristics, including the second absorption positions of spectral curve, the first absorption vale's area, and slope of spectral curve at 500-600 nm and 1340-1360 nm. Then K-means clustering and decision tree were used respectively to build soil classification model. The results indicated that 1) the second absorption positions of Black soil and Chernozem were located at 610 nm and 650 nm respectively; 2) the spectral curve of the meadow is similar to its adjacent soil, which could be due to soil erosion; 3) decision tree model showed higher classification accuracy, and accuracy of Black soil, Chernozem, Blown soil and Meadow are 100%, 88%, 97%, 50% respectively, and the accuracy of Blown soil could be increased to 100% by adding one more spectral index (the first two vole's area) to the model, which showed that the model could be used for soil classification and soil map in near future.

  18. O2 on ganymede: Spectral characteristics and plasma formation mechanisms

    USGS Publications Warehouse

    Calvin, W.M.; Johnson, R.E.; Spencer, J.R.

    1996-01-01

    Weak absorption features in the visible reflectance spectrum of Jupiter's satellite Ganymede have been correlated to those observed in the spectrum of molecular oxygen. We examine the spectral characteristics of these absorption features in all phases of O2 and conclude that the molecular oxygen is most likely present at densities similar to the liquid or solid ??-phase. The contribution of O2 to spectral features observed on Ganymede in the near-infrared wavelength region affects the previous estimates of photon pathlength in ice. The concentration of the visible absorption features on the trailing hemisphere of Ganymede suggests an origin due to bombardment by magneto-spheric ions. We derive an approximate O2 formation rate from this mechanism and consider the state of O2 within the surface.

  19. Optical Absorption Characteristics of Aerosols.

    DTIC Science & Technology

    1985-09-11

    properties of the powder as well as the thickness of the layer. For a layer that is thick enough so that no light is transmitted, the Kubelka -- Munk theory...which is a two stream radiative transfer model, relates the reflectance to the ratio of the absorption to the scattering. The Kubelka - Munk theory has...of the aerosol material is known. Under the assumptions of the Kubelka - Munk . theory, the imaginary component of the refractive index is deter- mined

  20. Spectral Classification of Heavily Reddened Stars by CO Absorption Strength

    NASA Astrophysics Data System (ADS)

    Garling, Christopher; Bary, Jeffrey S.; Huard, Tracy L.

    2017-01-01

    The nature of dust grains in dense molecular clouds can be explored by obtaining spectra of giant stars located behind the clouds and examining the wavelength-dependent attentuation of their light. This approach requires the intrinsic spectra of the background stars to be known, which can be achieved by determining their spectral types. In the K-band spectra of cool giant stars, several temperature-sensitive CO absorption bands serve as good spectral type indicators. Taking advantage of the SpeX Infrared Telescope Facility Spectral Library, near-infrared spectra collected with TripleSpec and the 3.5-meter ARC Telescope at Apache Point Observatory, and a previously constructed CO spectral index, we make precise spectral determinations of 20 giant stars located behind two dense cloud cores: CB188 and L429C. With spectral types in hand, we then utilize Markov Chain Monte Carlo techniques to constrain extinctions along these lines of sight. The spectral typing method will be described and assessed as well as its success at finding a couple of incorrectly spectral typed stars in the SpeX Library. Funding for this program was provided by a NSF REU grant to the Keck Northeast Astronomy Consortium and a grant from the NASA Astrophysics Data Analysis Program.

  1. Characterization of Spectral Absorption Properties of Aerosols Using Satellite Observations

    NASA Technical Reports Server (NTRS)

    Torres, O.; Jethva, H.; Bhartia, P. K.; Ahn, C.

    2012-01-01

    The wavelength-dependence of aerosol absorption optical depth (AAOD) is generally represented in terms of the Angstrom Absorption Exponent (AAE), a parameter that describes the dependence of AAOD with wavelength. The AAE parameter is closely related to aerosol composition. Black carbon (BC) containing aerosols yield AAE values near unity whereas Organic carbon (OC) aerosol particles are associated with values larger than 2. Even larger AAE values have been reported for desert dust aerosol particles. Knowledge of spectral AAOD is necessary for the calculation of direct radiative forcing effect of aerosols and for inferring aerosol composition. We have developed a satellitebased method of determining the spectral AAOD of absorbing aerosols. The technique uses high spectral resolution measurements of upwelling radiation from scenes where absorbing aerosols lie above clouds as indicated by the UV Aerosol Index. For those conditions, the satellite measured reflectance (rho lambda) is approximately given by Beer's law rho lambda = rho (sub 0 lambda) e (exp -mtau (sub abs lambda)) where rho(sub 0 lambda) is the cloud reflectance, m is the geometric slant path and tau (sub abs lambda) is the spectral AAOD. The rho (sub 0 lambda) term is determined by means of radiative transfer calculations using as input the cloud optical depth derived as described in Torres et al. [JAS, 2012] that accounts for the effects of aerosol absorption. In the second step, corrections for molecular and aerosol scattering effects are applied to the cloud reflectance term, and the spectral AAOD is then derived by inverting the equation above. The proposed technique will be discussed in detail and application results will be presented. The technique can be easily applied to hyper-spectral satellite measurements that include UV such as OMI, GOME and SCIAMACHY, or to multi-spectral visible measurements by other sensors provided that the aerosol-above-cloud events are easily identified.

  2. Plasma absorption evidence via chirped pulse spectral transmission measurements

    SciTech Connect

    Jedrkiewicz, Ottavia; Minardi, Stefano; Couairon, Arnaud; Jukna, Vytautas; Selva, Marco; Di Trapani, Paolo

    2015-06-08

    This work aims at highlighting the plasma generation dynamics and absorption when a Bessel beam propagates in glass. We developed a simple diagnostics allowing us to retrieve clear indications of the formation of the plasma in the material, thanks to transmission measurements in the angular and wavelength domains. This technique featured by the use of a single chirped pulse having the role of pump and probe simultaneously leads to results showing the plasma nonlinear absorption effect on the trailing part of the pulse, thanks to the spectral-temporal correspondence in the measured signal, which is also confirmed by numerical simulations.

  3. Spectral absorption of visual pigments in stomatopod larval photoreceptors.

    PubMed

    Feller, Kathryn D; Cronin, Thomas W

    2016-03-01

    Larval stomatopod eyes appear to be much simpler versions of adult compound eyes, lacking most of the visual pigment diversity and photoreceptor specializations. Our understanding of the visual pigment diversity of larval stomatopods, however, is based on four species, which severely limits our understanding of stomatopod eye ontogeny. To investigate several poorly understood aspects of stomatopod larval eye function, we tested two hypotheses surrounding the spectral absorption of larval visual pigments. First, we examined a broad range of species to determine if stomatopod larvae generally express a single, spectral class of photoreceptor. Using microspectrophotometry (MSP) on larvae captured in the field, we found data which further support this long-standing hypothesis. MSP was also used to test whether larval species from the same geographical region express visual pigments with similar absorption spectra. Interestingly, despite occupation of the same geographical location, we did not find evidence to support our second hypothesis. Rather, there was significant variation in visual pigment absorption spectra among sympatric species. These data are important to further our understanding of larval photoreceptor spectral diversity, which is beneficial to ongoing investigations into the ontogeny, physiology, and molecular evolution of stomatopod eyes.

  4. [Analysis of typical mangrove spectral reflectance characteristics].

    PubMed

    Yu, Xiang; Zhang, Feng-Shou; Liu, Qing; Li, De-Yi; Zhao, Dong-Zhi

    2013-02-01

    Acquisition of mangrove spectrum properties and detecting the sensitive bands provide technology basis for inverse modeling and estimation by remote sensing for various indexes of mangrove. The typical mangroves of Guangxi Shankou Mangrove Reserve were taken for study objects, the standard spectrum curves of Bruguiera gymnorrhiza (Linn.) Savigny, Rhizophora stylosa, Kandelia candel, Avicennia marina, Aegiceras corniculatum, Spartina anglica and mudflat were gained by denoising analysis of field-measured spectrum curves acquired by ASD FieldSpec 2. Analyzing the spectral characteristics and their differences, the authors found that the spectrum curves for various kinds of mangrove are coincident, the bands that appeared with reflection peaks and reflection valleys are basically identical, the within-class differentiated characteristics are comparatively small, the spectrum characteristics of mangroves are obviously different with Spartina anglica and mudflat. In order to gain the quantitative description for within-class differentiated characteristics of mangrove, space distance method, correlation coefficient method and spectral angle mapping method were used to calculate the within-class differentiated characteristics. The division accuracy of correlation coefficient method is higher than spectral angle mapping method which is higher than space distance method, and the result indicates that the spectrum differences of within-class mangrove and Spartina anglica are relatively small with correlation coefficients more than 0.995, and spectrum curve angle cosine values more than 0.95.

  5. A High Spectral Resolution Lidar Based on Absorption Filter

    NASA Technical Reports Server (NTRS)

    Piironen, Paivi

    1996-01-01

    A High Spectral Resolution Lidar (HSRL) that uses an iodine absorption filter and a tunable, narrow bandwidth Nd:YAG laser is demonstrated. The iodine absorption filter provides better performance than the Fabry-Perot etalon that it replaces. This study presents an instrument design that can be used a the basis for a design of a simple and robust lidar for the measurement of the optical properties of the atmosphere. The HSRL provides calibrated measurements of the optical properties of the atmospheric aerosols. These observations include measurements of aerosol backscatter cross sections, optical depth, backscatter phase function depolarization, and multiple scattering. The errors in the HSRL data are discussed and the effects of different errors on the measured optical parameters are shown.

  6. Spectral broadening of interacting pigments: polarized absorption by photosynthetic proteins.

    PubMed

    Somsen, O J; van Grondelle, R; van Amerongen, H

    1996-10-01

    Excitonic interaction between pigment molecules is largely responsible for the static and dynamic spectroscopic properties of photosynthetic pigment-proteins. This paper provides a new description of its effect on polarized absorption spectroscopy, in particular on circular dichroism (CD). We investigate excitonic spectra of finite width and use "spectral moments" to compare 1) inhomogeneously broadened excitonic spectra, 2) spectra that are (homogeneously broadened by vibrations or electron-phonon interaction, and 3) spectra that are simulated by applying convolution after the interaction has been evaluated. Two cases are distinguished. If the excitonic splitting is smaller than the width of the interacting absorption bands, the broadening of the excitonic spectrum can be approximated by a convolution approach, although a correction is necessary for CD spectra. If the excitonic splitting exceeds the bandwidth, the well-known exchange narrowing occurs. We demonstrate that this is accompanied by redistribution of dipole strength and spectral shifts. The magnitude of a CD spectrum is conveniently expressed by its first spectral moment. As will be shown, this is independent of spectral broadening as well as dispersive shifts induced by pigment-protein interactions. Consequently, it provides a simple tool to relate the experimental CD spectrum of a pigment complex to the excitonic interactions from which it originates. To illustrate the potential of the presented framework, the spectroscopy of the LH2 pigment-protein complex from purple bacteria is analyzed and compared for dimer-like and ring-like structures. Furthermore, it is demonstrated that the variability of the CD of chlorosomes from green bacteria can be explained by small changes in the structure of their cylindrical bacteriochlorophyll c subunits.

  7. Absorption Characteristics of Vertebrate Non-Visual Opsin, Opn3

    PubMed Central

    Sugihara, Tomohiro; Nagata, Takashi; Mason, Benjamin; Koyanagi, Mitsumasa; Terakita, Akihisa

    2016-01-01

    Most animals possess multiple opsins which sense light for visual and non-visual functions. Here, we show spectral characteristics of non-visual opsins, vertebrate Opn3s, which are widely distributed among vertebrates. We successfully expressed zebrafish Opn3 in mammalian cultured cells and measured its absorption spectrum spectroscopically. When incubated with 11-cis retinal, zebrafish Opn3 formed a blue-sensitive photopigment with an absorption maximum around 465 nm. The Opn3 converts to an all-trans retinal-bearing photoproduct with an absorption spectrum similar to the dark state following brief blue-light irradiation. The photoproduct experienced a remarkable blue-shift, with changes in position of the isosbestic point, during further irradiation. We then used a cAMP-dependent luciferase reporter assay to investigate light-dependent cAMP responses in cultured cells expressing zebrafish, pufferfish, anole and chicken Opn3. The wild type opsins did not produce responses, but cells expressing chimera mutants (WT Opn3s in which the third intracellular loops were replaced with the third intracellular loop of a Gs-coupled jellyfish opsin) displayed light-dependent changes in cAMP. The results suggest that Opn3 is capable of activating G protein(s) in a light-dependent manner. Finally, we used this assay to measure the relative wavelength-dependent response of cells expressing Opn3 chimeras to multiple quantally-matched stimuli. The inferred spectral sensitivity curve of zebrafish Opn3 accurately matched the measured absorption spectrum. We were unable to estimate the spectral sensitivity curve of mouse or anole Opn3, but, like zebrafish Opn3, the chicken and pufferfish Opn3-JiL3 chimeras also formed blue-sensitive pigments. These findings suggest that vertebrate Opn3s may form blue-sensitive G protein-coupled pigments. Further, we suggest that the method described here, combining a cAMP-dependent luciferase reporter assay with chimeric opsins possessing the third

  8. Characterization of bottom ice algal and detrital spectral absorption properties in first-year sea ice of an Arctic polynya

    NASA Astrophysics Data System (ADS)

    Mundy, C.; Gosselin, M.; Nozais, C.; Simard, M.

    2009-12-01

    Little information exists on the spectral absorption properties of algal and detrital matter in sea ice. During the International North Water polynya study, we collected a large dataset on ice algal spectral absorption characteristics within the bottom 2 to 4 cm of first-year sea ice from April to June 1998. The data compared surprisingly well with select phytoplankton models, given that the models were extrapolated well beyond their limits to ice algal chlorophyll a (Chl a) concentrations that ranged up to 2000 mg m-3. However, a strong packaging effect was apparent at Chl a concentrations >500 mg m-3, which tended to decrease the Chl a specific algal absorption coefficient relative to model predictions. Diatoms dominated the ice algae community for most of the period and subsequently, controlled absorption characteristics. Although not conclusive, an outlier dominated by nanoflagellates did show an increase in the Chl a specific algal absorption coefficient, demonstrating the decrease in packaging effect associated with the smaller cell size. Seasonal progression in ice algal spectral absorption revealed a change in pigment composition from strong absorption >500 nm, indicative of photosynthetic accessory pigments, to strong absorption between 450 nm to 500 nm, indicative of photoprotective pigments. Furthermore, the ratio of phytoplankton absorption at 490:470 nm regressed significantly with time (positive) and ice thickness (negative) throughout the study period, suggesting a continual photoacclimation of the ice algal community to increasing transmitted irradiance. The results of our study show that measurements of ice algal spectral absorption properties will not only improve their parameterization in sea ice bio-optical models, but can provide information on both taxonomic composition and physiological state.

  9. Study on the Relationship between the Depth of Spectral Absorption and the Content of the Mineral Composition of Biotite.

    PubMed

    Yang, Chang-bao; Zhang, Chen-xi; Liu, Fang; Jiang, Qi-gang

    2015-09-01

    The mineral composition of rock is one of the main factors affecting the spectral reflectance characteristics, and it's an important reason for generating various rock characteristic spectra. This study choose the rock samples provided by Jet Propulsion Laboratory (JPL) (including all kinds of mineral percentage of rocks, and spectral reflectances range from 0.35 to 2.50 μm wavelength measured by ASD spectrometer), and the various types of mineral spectral reflectances contained within the rocks are the essential data. Using the spectral linear mixture model of rocks and their minerals, firstly, a simulation study on the mixture of rock and mineral composition is achieved, the experimental results indicate that rock spectral curves using the model which based on the theory of the linear mixture are able to simulate better and preserve the absorption characteristics of various mineral components well. Then, 8 samples which contain biotite mineral are picked from the rock spectra of igneous, biotite contents and the absorption depth characteristics of spectral reflection at 2.332 μm, furthermore, a variety of linear and nonlinear normal statistical models are used to fit the relationship between the depth of absorption spectra and the content of the mineral composition of biotite, finally, a new simulation model is build up with the Growth and the Exponential curve model, and a statistical response relationship between the spectral absorption depth and the rock mineral contents is simulated by using the new model, the fitting results show that the correlation coefficient reaches 0.9984 and the standard deviation is 0.572, although the standard deviation using Growth and Exponential model is less than the two model combined with the new model fitting the standard deviation, the correlation coefficient of the new model had significantly increased, which suggesting that the, new model fitting effect is closer to the measured values of samples, it proves that the

  10. Guided-wave approaches to spectrally selective energy absorption

    NASA Technical Reports Server (NTRS)

    Stegeman, G. I.; Burke, J. J.

    1987-01-01

    Results of experiments designed to demonstrate spectrally selective absorption in dielectric waveguides on semiconductor substrates are reported. These experiments were conducted with three waveguides formed by sputtering films of PSK2 glass onto silicon-oxide layers grown on silicon substrates. The three waveguide samples were studied at 633 and 532 nm. The samples differed only in the thickness of the silicon-oxide layer, specifically 256 nm, 506 nm, and 740 nm. Agreement between theoretical predictions and measurements of propagation constants (mode angles) of the six or seven modes supported by these samples was excellent. However, the loss measurements were inconclusive because of high scattering losses in the structures fabricated (in excess of 10 dB/cm). Theoretical calculations indicated that the power distribution among all the modes supported by these structures will reach its steady state value after a propagation length of only 1 mm. Accordingly, the measured loss rates were found to be almost independent of which mode was initially excited. The excellent agreement between theory and experiment leads to the conclusion that low loss waveguides confirm the predicted loss rates.

  11. Morphological, structural, and spectral characteristics of amorphous iron sulfates

    NASA Astrophysics Data System (ADS)

    Sklute, E. C.; Jensen, H. B.; Rogers, A. D.; Reeder, R. J.

    2015-04-01

    Current or past brine hydrologic activity on Mars may provide suitable conditions for the formation of amorphous ferric sulfates. Once formed, these phases would likely be stable under current Martian conditions, particularly at low- to mid-latitudes. Therefore, we consider amorphous iron sulfates (AIS) as possible components of Martian surface materials. Laboratory AIS were created through multiple synthesis routes and characterized with total X-ray scattering, thermogravimetric analysis, scanning electron microscopy, visible/near-infrared (VNIR), thermal infrared (TIR), and Mössbauer techniques. We synthesized amorphous ferric sulfates (Fe(III)2(SO4)3 · ~ 6-8H2O) from sulfate-saturated fluids via vacuum dehydration or exposure to low relative humidity (<11%). Amorphous ferrous sulfate (Fe(II)SO4 · ~ 1H2O) was synthesized via vacuum dehydration of melanterite. All AIS lack structural order beyond 11 Å. The short-range (<5 Å) structural characteristics of amorphous ferric sulfates resemble all crystalline reference compounds; structural characteristics for the amorphous ferrous sulfate are similar to but distinct from both rozenite and szomolnokite. VNIR and TIR spectral data for all AIS display broad, muted features consistent with structural disorder and are spectrally distinct from all crystalline sulfates considered for comparison. Mössbauer spectra are also distinct from crystalline phase spectra available for comparison. AIS should be distinguishable from crystalline sulfates based on the position of their Fe-related absorptions in the visible range and their spectral characteristics in the TIR. In the NIR, bands associated with hydration at ~1.4 and 1.9 µm are significantly broadened, which greatly reduces their detectability in soil mixtures. AIS may contribute to the amorphous fraction of soils measured by the Curiosity rover.

  12. Importance of the green color, absorption gradient, and spectral absorption of chloroplasts for the radiative energy balance of leaves.

    PubMed

    Kume, Atsushi

    2017-03-14

    Terrestrial green plants absorb photosynthetically active radiation (PAR; 400-700 nm) but do not absorb photons evenly across the PAR waveband. The spectral absorbance of photosystems and chloroplasts is lowest for green light, which occurs within the highest irradiance waveband of direct solar radiation. We demonstrate a close relationship between this phenomenon and the safe and efficient utilization of direct solar radiation in simple biophysiological models. The effects of spectral absorptance on the photon and irradiance absorption processes are evaluated using the spectra of direct and diffuse solar radiation. The radiation absorption of a leaf arises as a consequence of the absorption of chloroplasts. The photon absorption of chloroplasts is strongly dependent on the distribution of pigment concentrations and their absorbance spectra. While chloroplast movements in response to light are important mechanisms controlling PAR absorption, they are not effective for green light because chloroplasts have the lowest spectral absorptance in the waveband. With the development of palisade tissue, the incident photons per total palisade cell surface area and the absorbed photons per chloroplast decrease. The spectral absorbance of carotenoids is effective in eliminating shortwave PAR (<520 nm), which contains much of the surplus energy that is not used for photosynthesis and is dissipated as heat. The PAR absorptance of a whole leaf shows no substantial difference based on the spectra of direct or diffuse solar radiation. However, most of the near infrared radiation is unabsorbed and heat stress is greatly reduced. The incident solar radiation is too strong to be utilized for photosynthesis under the current CO2 concentration in the terrestrial environment. Therefore, the photon absorption of a whole leaf is efficiently regulated by photosynthetic pigments with low spectral absorptance in the highest irradiance waveband and through a combination of pigment density

  13. Spectral Measurements of Aerosol Absorption from UV to VISIBLE

    NASA Astrophysics Data System (ADS)

    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

  14. Spectral Similarity Assessment Based on a Spectrum Reflectance-Absorption Index and Simplified Curve Patterns for Hyperspectral Remote Sensing.

    PubMed

    Ma, Dan; Liu, Jun; Huang, Junyi; Li, Huali; Liu, Ping; Chen, Huijuan; Qian, Jing

    2016-01-26

    Hyperspectral images possess properties such as rich spectral information, narrow bandwidth, and large numbers of bands. Finding effective methods to retrieve land features from an image by using similarity assessment indices with specific spectral characteristics is an important research question. This paper reports a novel hyperspectral image similarity assessment index based on spectral curve patterns and a reflection-absorption index. First, some spectral reflection-absorption features are extracted to restrict the subsequent curve simplification. Then, the improved Douglas-Peucker algorithm is employed to simplify all spectral curves without setting the thresholds. Finally, the simplified curves with the feature points are matched, and the similarities among the spectral curves are calculated using the matched points. The Airborne Visible Infrared Imaging Spectrometer (AVIRIS) and Reflective Optics System Imaging Spectrometer (ROSIS) hyperspectral image datasets are then selected to test the effect of the proposed index. The practical experiments indicate that the proposed index can achieve higher precision and fewer points than the traditional spectral information divergence and spectral angle match.

  15. Spectral Similarity Assessment Based on a Spectrum Reflectance-Absorption Index and Simplified Curve Patterns for Hyperspectral Remote Sensing

    PubMed Central

    Ma, Dan; Liu, Jun; Huang, Junyi; Li, Huali; Liu, Ping; Chen, Huijuan; Qian, Jing

    2016-01-01

    Hyperspectral images possess properties such as rich spectral information, narrow bandwidth, and large numbers of bands. Finding effective methods to retrieve land features from an image by using similarity assessment indices with specific spectral characteristics is an important research question. This paper reports a novel hyperspectral image similarity assessment index based on spectral curve patterns and a reflection-absorption index. First, some spectral reflection-absorption features are extracted to restrict the subsequent curve simplification. Then, the improved Douglas-Peucker algorithm is employed to simplify all spectral curves without setting the thresholds. Finally, the simplified curves with the feature points are matched, and the similarities among the spectral curves are calculated using the matched points. The Airborne Visible Infrared Imaging Spectrometer (AVIRIS) and Reflective Optics System Imaging Spectrometer (ROSIS) hyperspectral image datasets are then selected to test the effect of the proposed index. The practical experiments indicate that the proposed index can achieve higher precision and fewer points than the traditional spectral information divergence and spectral angle match. PMID:26821030

  16. A new method to retrieve spectral absorption coefficient of highly-scattering and weakly-absorbing materials

    NASA Astrophysics Data System (ADS)

    Dombrovsky, Leonid A.

    2016-03-01

    A significant uncertainty in the absorption coefficient of highly scattering dispersed materials is typical in the spectral ranges of very weak absorption. The traditional way to identify the main absorption and scattering characteristics of semi-transparent materials is based on spectral measurements of normal-hemispherical reflectance and transmittance for the material sample. Unfortunately this way cannot be used in the case of in vivo measurements of optical properties of biological tissues. A method suggested in the present paper is based on thermal response to the periodic radiative heating of the open surface of a semi-transparent material. It is shown that the period of a variation of the surface temperature is sensitive to the value of an average absorption coefficient in the surface layer. As a result, the monochromatic external irradiation combined with the surface temperature measurements can be used to retrieve the spectral values of absorption coefficient. Possible application of this method to porous semi-transparent ceramics is considered. An example problem is also solved to illustrate the applicability of this method to human skin. The approach suggested enables one to estimate an average absorption coefficient of human skin of a patient just before the thermal processing.

  17. Spectral Apparatus with a Cryogenic, High-Throughput, Multipass Gas Cell for Studies of Absorption of Radiation by Gaseous Media

    NASA Astrophysics Data System (ADS)

    Moskalenko, N. I.; Mirumyants, S. O.; Parzhin, S. N.; Dodov, I. R.

    2016-11-01

    Spectral systems with an MKhK-6 cryogenic, high-throughput, multipass gas cell for studying the absorption spectra of gaseous media with high spectral resolution in the 0.1-6 μm range at pressures of 100 to 5·106 Pa and temperatures of 180-300 K are discussed. Their use in measurements of spectral absorption coefficients, temperature dependences of the spectral transmission function, and parameters of spectral absorption lines is examined.

  18. Spectral absorption index in hyperspectral image analysis for predicting moisture contents in pork longissimus dorsi muscles.

    PubMed

    Ma, Ji; Sun, Da-Wen; Pu, Hongbin

    2016-04-15

    Spectral absorption index was proposed to extract the morphological features of the spectral curves in pork meat samples (longissimus dorsi) under the conditions including fresh, frozen-thawed, heated-dehydrated and brined-dehydrated. Savitzky-Golay (SG) smoothing and multiplicative scatter correction (MSC) were used for calibrating both the spectral reflectance and absorbance values. The absorption values were better than the reflectance values and the calibrated spectra by MSC were better than the raw and SG smoothing corrected spectra in building moisture content predictive models. The optimized partial least square regression (PLSR) model attained good results with the MSC calibrated spectral absorption values based on the spectral absorption index features (R(2)P=0.952, RMSEP=1.396) and the optimal wavelengths selected by regression coefficients (R(2)P=0.966, RMSEP=0.855), respectively. The models proved spectral absorption index was promising in spectral analysis to predict moisture content in pork samples using HSI techniques for the first time.

  19. Spectral reflecting characteristics of dinas refractory

    SciTech Connect

    Zapechnikov, V.N.; Pushkin, V.T.; Zen'kovskii, A.G.

    1987-09-01

    This article outlines a nondestructive testing format which uses spectral reflectance to assess the remaining service life, the thermal degradation, and the insulating effectiveness of refractories used as insulating liners in glass melters. Thermal as well as mechanical influences on the reflectance behavior of several refractories are discussed.

  20. Structural and Spectral Characteristics of Amorphous Iron Sulfates

    NASA Astrophysics Data System (ADS)

    Sklute, E.; Jensen, H. B.; Rogers, D.; Reeder, R. J.

    2014-12-01

    Substantial evidence points to the existence of hydrated sulfate phases on the Martian surface1-3. In addition, the discovery of recurring slope lineae could point to an active brine hydrologic cycle on the surface4,5. The rapid dehydration of both hydrated sulfates and sulfate-rich brines can lead to the formation of amorphous sulfates. Evidence suggests that the Rocknest soil target and the Sheepbed mudstone interrogated by the Mars Science Laboratory at Gale crater contain ~30 wt.% XRD amorphous material that is rich in both sulfur and iron6. These factors have led us to consider hydrated amorphous iron sulfates as possible components in Martian surface materials. Amorphous iron sulfates were created through multiple synthesis routes, and then characterized with total x-ray scattering, TGA, SEM, visible/near-infrared (VNIR), thermal infrared (TIR), and Mössbauer techniques. We synthesized amorphous ferric sulfates (Fe(III)2(SO4)3•~5-8H2O) from sulfate-saturated fluids via two pathways: vacuum dehydration and exposure to low relative humidity (<11%) using a LiCl buffer. Amorphous ferrous sulfate (Fe(II)SO4•~1H2O) was synthesized via vacuum dehydration of melanterite (Fe(II) SO4•7H2O). We find that both the ferric and ferrous sulfates synthesized from these methods lack long-range (>10Å) order, and thus are truly amorphous. VNIR and TIR spectral data for the amorphous sulfates display broad, muted features consistent with structural disorder and are spectrally distinct from all crystalline sulfates considered for comparison. Mössbauer spectra are also distinct from all crystalline phase spectra available for comparison. The amorphous sulfates should be distinguishable based on the position of their Fe-related absorptions in the visible range and their spectral characteristics in the TIR. In the NIR, which is the spectral range that has primarily been used to detect sulfates on Mars, the bands associated with hydration at ~1.4 and 1.9 μm are significantly

  1. [Absorption spectra of nucleic acids and related compounds in the spectral region 120--280 nm].

    PubMed

    Kiseleva, M N; Zarochentseva, E P; Dodonova, N Ia

    1975-01-01

    The absorption spectra of thin films of nucleic acids, nucleosides, nucleotides, D-ribose, Na3PO4 in vacuum ultraviolet region are measured. In the spectral region 280--160 nm the absorption spectra consist of the bands of nucleic acid bases. In the range shorter than 160 nm the absorption is determined by phosphate and D-ribose groups. The methods of thin films preparation are discussed.

  2. Spectral dependences of extrinsic optical absorption in sillenite crystals

    SciTech Connect

    Kisteneva, M G; Khudyakova, E S; Shandarov, S M; Akrestina, A S; Dyu, V G; Kargin, Yu F

    2015-07-31

    The influence of laser irradiation at wavelengths of 532 and 655 nm and annealing in air at temperatures from 200 to 370 °C on optical absorption spectra of undoped bismuth silicon oxide and bismuth germanium oxide and aluminium-doped bismuth titanium oxide crystals has been studied experimentally. The experimental data have been interpreted in terms of a model for extrinsic absorption that takes into account not only the contribution of the photoexcitation of electrons from deep donor centres with a normal distribution of their concentration with respect to ionisation energy but also that of intracentre transitions. (laser applications and other topics in quantum electronics)

  3. Spectral properties of molecular iodine in absorption cells filled to specified saturation pressure.

    PubMed

    Hrabina, Jan; Šarbort, Martin; Acef, Ouali; Burck, Frédéric Du; Chiodo, Nicola; Holá, Miroslava; Číp, Ondřej; Lazar, Josef

    2014-11-01

    We present the results of measurement and evaluation of spectral properties of iodine absorption cells filled at certain saturation pressure. A set of cells made of borosilicate glass instead of common fused silica was tested for their spectral properties in greater detail with special care for the long-term development of the absorption media purity. The results were compared with standard fused silica cells and the high quality of iodine was verified. A measurement method based on an approach relying on measurement of linewidth of the hyperfine transitions is proposed as a novel technique for iodine cell absorption media purity evaluation. A potential application in laser metrology of length is also discussed.

  4. Performance Characteristics of Absorption Hybrid Cycle Introduced Compressor

    NASA Astrophysics Data System (ADS)

    Iyoki, Shigeki; Kotani, Yuji; Uemura, Tadashi

    In this paper, four kinds of absorption hybrid cycle which introduced the compressor in the absorption cycle were proposed. As basic cycle of absorption refrigerating machine, the following were chosen: two kinds of single-stage absorption refrigerating machine and two kinds of double effect absorption refrigerating machine. As a working medium-absorbent system, NH3-H2O system, C2H5NH2-H2O system and C2H5NH2-H2O-LiBr system were adopted. Using these three kinds of working medium-absorbent system, the performance characteristics of four kinds of absorption hybrid cycle were simulated. And the performance characteristics of these cycles were compared.

  5. Mixing state and spectral absorption of atmospheric aerosols observed at a marine background site

    NASA Astrophysics Data System (ADS)

    Cayetano, M. G.; Lee, K. Y.; Kim, Y. J.

    2011-12-01

    Mineral dust and sea salt particles are portions of atmospheric aerosols in Korea due to the periodic transport of loess dust particles from Gobi and Taklimakan deserts in west China, as well as the sea salt enrichment of atmospheric particles from the seas surrounding the Korean peninsula [Kim et al., 2009; Sahu et al., 2009]. Carbonaceous particles and secondary inorganic aerosols (sulphates and nitrates) are ubiquitous due to the proliferating biomass burning [Ryu et al., 2004], as well as the increasing use of fossil fuels locally and by regional transport from neighbouring countries. Collectively, when these aerosols are transported, their compositions are further modified due to the aging process, impacting their physico-chemical properties including spectral absorption. In order to investigate the spectral response of the absorption under different ambient aerosol conditions, measurements have been conducted at a marine background site in Korea (Deokjeok Island. 37° 13' 33" N, 126° 8' 51" E) during the spring (13 days) and fall (8 days) seasons of 2009 using an aethalometer (Magee AE31), a nephelometer (Optec NGN2a) and other supporting instruments (PILS-IC, PM2.5 cyclone samplers for off-line OC/EC measurements). It has been found that spring aerosols were dominated by sulphate-rich and carbonaceous-rich fractions (21.4%±8.0% and 28.8%±7.9%, respectively), with an Angström exponent of absorption, αabs = 1.3±0.1 at 370-950 nm. The fall season aerosols were grouped based on their chemical composition as acidic aerosols, dust-enriched, and seasalt-enriched aerosols. Angström exponent of absorption, αabs for acidic aerosols was obtained to be 1.3±0.2 at 370-950 nm. However, dust enriched aerosols showed increased absorption in the short UV-Vis range (370-590 nm), which can be attributed to their mixing with light absorbing aerosols. Different types of aerosols exhibit different spectral absorption characteristics depending on their composition and

  6. [Application in methane extraction of fiber methane monitoring system based on spectral absorption].

    PubMed

    Zhao, Yan-jie; Wang, Chang; Liu, Tong-yu; Wang, Zhe; Wei, Yu-bin; Li, Yan-fang; Shang, Ying; Wang, Qian

    2010-10-01

    An optical fiber distributed multi-point methane real-time monitoring system based on the methane spectral absorption characteristic is researched, and it's application in methane extraction is presented. An 1665 nm distributed feedback (DFB) laser is used as the light source by taking the triangular signal to modulate the light frequency of the DFB laser. Using the combination of single-chip computer C8051F410, A/D transform circuit, communication circuit, display circuit, etc, the concentration of methane can be monitored and displayed on the screen. And the function of sounding the alarm bell and communication are achieved. The laser wavelength shift is carried out with adaptive adjustment by the built-in gas calibration pond so as to realize the locking of a methane absorption line. Several field tests have been founded at home and abroad. The results show that the system has good performance in stability and sensitivity. The distributed multi-point methane concentration monitoring is realized in the range of 0%-100%. A sensitivity of ppm order of magnitude has been achieved. It possesses of wide application in methane extraction.

  7. Molar absorptivity and color characteristics of acylated and non-acylated pelargonidin-based anthocyanins.

    PubMed

    Giusti, M M; Rodríguez-Saona, L E; Wrolstad, R E

    1999-11-01

    The effects of glycosylation and acylation on the spectral characteristics, molar absorptivity, and color attributes of purified acylated and non-acylated pelargonidin derivatives were compared. Pigments were obtained from strawberries, radishes, red-fleshed potatoes, and partially hydrolyzed radish pigments. Individual pigments were isolated by using semipreparative HPLC. Spectral and color (CIELch) attributes of purified pigments were measured. Molar absorptivity ranged from 15 600 to 39 590 for pelargonidin-3-glucoside (pg-3-glu) and pg-3-rutinoside-5-glucoside acylated with p-coumaric acid, respectively. The presence of cinnamic acid acylation had a considerable impact on spectral and color characteristics, causing a bathochromic shift of lambda(max). Sugar substitution also played an important role, with a hypsochromic shift caused by the presence of glycosylation. Pg-3, 5-diglu and pg-3,5-triglu possessed a higher hue angle (>40 degrees ) than the other pg derivatives at pH 1.0, corresponding to the yellow-orange region of the color solid. Acylation with malonic acid did not affect lambda(max) and showed little effect on color characteristics. The solvent system had an effect not only on the molar absorptivity, but also on the visual color characteristic of the pigments.

  8. Theoretical and experimental study of spectral characteristics of the photoacoustic signal from stochastically distributed particles.

    PubMed

    Wang, Shaohua; Tao, Chao; Yang, Yiqun; Wang, Xueding; Liu, Xiaojun

    2015-07-01

    Photoacoustic imaging is an emerging technique which inherits the merits of optical imaging and ultrasonic imaging. However, classical photoacoustic imaging mainly makes use of the time-domain parameters of signals. In contrast to previous studies, we theoretically investigate the spectral characteristics of the photoacoustic signal from stochastic distributed particles. The spectral slope is extracted and used for describing the spectral characteristics of the photoacoustic signal. Both Gaussian and spherical distributions of optical absorption in particles are considered. For both situations, the spectral slope is monotonically decreased with the increase of particle size. In addition, the quantitative relationship between the spectral slope and the imaging system factors, including the laser pulse envelope, directivity of ultrasound transducer, and signal bandwidth, are theoretically analyzed. Finally, an idealized phantom experiment is performed to validate the analyses and examine the instrument independent of the spectral slope. This work provides a theoretical framework and new experimental evidence for spectrum analysis of the photoacoustic signal. This could be helpful for quantitative tissue evaluation and imaging based on the spectral parameters of the photoacoustic signal.

  9. Inferring spectral characteristics of the Hα spectral line observed by the DOT Lyot filter

    NASA Astrophysics Data System (ADS)

    Koza, J.; Rybák, J.; Gömöry, P.; Kučera, A.

    2014-04-01

    A tunable Lyot filter can serve as a spectroscopic device rendering wide-field 2-D pseudospectroscopy of solar structures and follow-up crude reconstruction of a spectral line profile at each pixel within the field of view. We developed a method of inferring of the Doppler shift, the core intensity, the core width, and the core asymmetry of the Hα spectral line observed by the Lyot filter installed on the Dutch Open Telescope (DOT). The spectral characteristics are inferred through the fitting of five intensity samples, separated from each other by 0.35 Å, by a 4th-order polynomial, a Gaussian, and a parabola. We use the atlas Hα profile as a reference in estimating deviations of the derived spectral characteristics. The Gaussian is the most preferable means for measurements of the Doppler shift with deviations smaller than 1 km s-1. When using the 4th-order polynomial, deviations are within the interval ±2.5 km s-1, but it renders comparable deviations of the core intensity and the width as the Gaussian. The deviations are largely insensitive to the shape of the filter transmission, but depend mostly non-linearly on the Doppler shift. Therefore, they do not cancel out if the spectral characteristics are represented by their relative variations. Results can be used as corrections of spectral characteristics extracted from area-averaged Hα profiles acquired by the DOT Lyot filter.

  10. Absorption and fluorescent spectral studies of imidazophenazine derivatives

    NASA Astrophysics Data System (ADS)

    Ryazanova, O. A.; Zozulya, V. N.; Voloshin, I. M.; Karachevtsev, V. A.; Makitruk, V. L.; Stepanian, S. G.

    2004-07-01

    Absorption and fluorescent spectra as well as fluorescence polarization degree of imidazo-[4,5-d]-phenazine (F1) and its two modified derivatives, 2-trifluoridemethylimidazo-[4,5-d]-phenazine (F2) and 1,2,3-triazole-[4,5-d]-phenazine (F3), were investigated in organic solvents of various polarities and hydrogen bonding abilities. Extinction coefficients of F2 and F3 are increased, their fluorescence Stokes shifts are reduced in comparison with those for unmodified imidazophenazine. For F3 a red shift of the longwave absorption band is observed by 15-20 nm. Modifications of imidazophenazine have led to a sufficient increase of fluorescence polarization degrees that enables to use F2 and F3 as promising fluorescent probes with polarization method application. The configuration, atomic charge distribution and dipole moments of the isolated dye molecules in the ground state were calculated by the DFT method. The computation has revealed that ground state dipole moments of F1, F2, and F3 differ slightly and are equal to 3.5, 3.2, and 3.7 D, respectively. The changes in dipole moments upon the optical excitation for all derivatives estimated using Lippert equation were found to be Δ μ=9 D. The energies of the electronic S 1←S 0 transition in solvents of different proton donor abilities were determined, and energetic diagram illustrating the substituent effect was plotted. For nucleoside analogs of these compounds, covalently incorporated into a nucleotide chain, we have considered a possibility to use them as fluorescent reporters of hybridization of antisense oligonucleotides, as well as molecular anchors for its stabilization.

  11. Multi-spectral optical absorption in substrate-free nanowire arrays

    SciTech Connect

    Zhang, Junpeng; Chia, Andrew; Boulanger, Jonathan; LaPierre, Ray; Dhindsa, Navneet; Khodadad, Iman; Saini, Simarjeet

    2014-09-22

    A method is presented of fabricating gallium arsenide (GaAs) nanowire arrays of controlled diameter and period by reactive ion etching of a GaAs substrate containing an indium gallium arsenide (InGaP) etch stop layer, allowing the precise nanowire length to be controlled. The substrate is subsequently removed by selective etching, using the same InGaP etch stop layer, to create a substrate-free GaAs nanowire array. The optical absorptance of the nanowire array was then directly measured without absorption from a substrate. We directly observe absorptance spectra that can be tuned by the nanowire diameter, as explained with rigorous coupled wave analysis. These results illustrate strong optical absorption suitable for nanowire-based solar cells and multi-spectral absorption for wavelength discriminating photodetectors. The solar-weighted absorptance above the bandgap of GaAs was 94% for a nanowire surface coverage of only 15%.

  12. In Situ Measurements of Aerosol Mass Concentration and Spectral Absorption in Xianghe, SE of Beijing, China

    NASA Astrophysics Data System (ADS)

    Chaudhry, Z.; Martins, V.; Li, Z.

    2005-12-01

    China's rapid industrialization over the last few decades has affected air quality in many regions of China, and even the regional climate. As a part of the EAST-AIRE (East Asian Study of Tropospheric Aerosols: an International Regional Experiment) study, Nuclepore filters were collected in two size ranges (PM10 and PM2.5) at 12 hour intervals since January 2005 at Xianghe, about 70 km southeast of Beijing. Each filter was analyzed for mass concentration, aerosol scattering and absorption efficiencies. Mass concentrations during the winter months (January-March) ranged from 9 to 459 μg/m3 in the coarse mode with an average concentration of 122 μg/m3, and from 11 to 203 μg/m3 in the fine mode with an average concentration of 45 μg/m3. While some of the extreme values are likely linked to local emissions, regional air pollution episodes also played important roles. Absorption efficiency measurements at 550 nm show very high values compared to measurements performed in the United States during the CLAMS experiment. The spectral mass absorption efficiency was measured from 350 to 2500 nm and shows large differences between the absorption properties of soil dust, black carbon, and organic aerosols. The strong spectral differences observed can be related to differences in refractive indices from the several collected species and particle size effects. The absorption properties from aerosols measured in China show large absorption efficiencies, compared to aerosols measured in the US, possibly linked to different technology practices used in these countries. For organic plus black carbon aerosols, where the refractive index seems to be relatively constant, the absorption efficiency spectral dependence for fine mode aerosols falls between 1/λ and 1/λ2. The coarse mode absorption shows much less spectral dependence.

  13. Spectral effects on direct-insolation absorptance of five collector coatings

    NASA Technical Reports Server (NTRS)

    Hotchkiss, G. B.; Simon, F. F.; Burmeister, L. C.

    1979-01-01

    Absorptances for direct insolation of black chrome, black nickel, copper oxide, and two black zinc conversion selective coatings were calculated for a number of typical solar spectrums. Measured spectral reflectances were used while the effects of atmospheric ozone density, turbidity, and air mass were incorporated in calculated direct solar spectrums. Absorptance variation for direct insolation was found to be of the order of 1 percent for a typical range of clear-sky atmospheric conditions.

  14. Electrically Tunable Absorption Enhancement with Spectral and Polarization Selectivity through Graphene Plasmonic Light Trapping

    PubMed Central

    Liu, Wenbin; Zhang, Jianfa; Zhu, Zhihong; Yuan, Xiaodong; Qin, Shiqiao

    2016-01-01

    In this paper, anisotropic graphene plasmonic structures are explored for light trapping and absorption enhancement in surrounding media. It is shown that electrically tunable and versatile spectral and polarization selectivity can be realized. Particularly, it is possible to control absorption of the incident light’s polarization component at a specific wavelength by varying the Fermi energy with suitable geometric designs. It may find applications for new types of infrared and THz photodetectors and will promote the research of other novel polarization devices.

  15. [Spectral Characteristic of Dissolved Organic Matter in Xiaohe River, Hebei].

    PubMed

    Yu, Min-da; Zhang, Hui; He, Xiao-song; Tan, Wen-bing; Zhang, Yuan; Ma, Li-na; Xi, Bei-dou; Dang, Qiu-ling; Gao, Ru-tai

    2015-09-01

    The spectral characteristic of dissolved organic matter (DOM) in Xiaohe River, Hebei, was investigated by fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy, and basic chemical water quality indicators. The data was then statistical analyzed using principal component analysis and correlation analysis method. The result based on 3D excitation-emission matrix fluorescence spectroscopy showed that DOM in Xiaohe River contained both protein-like and humus-like components. DOM and N-containing compounds were obviously correlated with COD, especially between NH4+ -N and humic-like component, indicating that COD of water in Xiaohe River can be reduced by removing NH4+ -N and DOM, which could be good indicators for monitoring water quality in the future. The relative content of protein-like component reduces gradually along the downstream, while that of humic-like component showed an increasing trend. DOM in samples S1 and S2 was mainly consisted of humic-like components with larger molecular weight and higher aromaticity, while that in samples S3 and S6 was mainly consisted of protein-like components with smaller molecular weight, lower aromaticity, which are easier to be degraded. Therefore, in order to enhance the remove of refractory humic-like substances, sewage treatment plants of S1 and S2 or improved membrane treatment equipment with better removal effect of macromolecules should be provide. On the other hand, the anaerobic and aerobic biological treatment processes should be optimized in S3 and S6, so as to better remove these degradable protein-like substances.

  16. Spectral response characteristics of photovoltaic materials

    NASA Astrophysics Data System (ADS)

    Hanselman, Daniel L.

    The most efficient solar modules use multiple materials of slightly varying composition and electronic characteristics to convert different bandwidths of the solar spectrum into usable electricity. Cells made in this fashion generally require very expensive, high precision equipment leading to a high cost of the modules. It has been suggested that an optical system be used to disperse the sunlight into its constituent wavelengths (see Conte et. al. (1989)[22]) with different materials strategically placed under the appropriate bandwidth of light to produce higher efficiency, low cost modules. The proper selection and placement of materials requires detailed knowledge of the response of various materials to different wavelengths of light. Solid State Theory calculates this response through complicated mathematical models describing the band structure of the materials and the density of states for charge carriers. The research described herein defines this response through experiment. The experiment designed for this research examines the response of commercially available photovoltaic cells of various materials. Concentrated sunlight is passed through filters with known transmittance to illuminate a photovoltaic cell. The incident irradiance, and thereby the incident power, on the cell is recorded as well as the power output by the cell. These two powers are compared for each filter, and the results are plotted as efficiency vs. wavelength providing an experimental check for theoretical calculations. This experiment can be performed on any photovoltaic material of interest to determine optimal material selection and placement under the dispersed sunlight for a solar module. The combination of the methods developed in this research and the optics described in the paper by Conte et. al. can be used to produce an inexpensive, high efficiency solar module.

  17. Assessing multiple quality attributes of peaches using spectral absorption and scattering properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this research was to measure the spectral absorption and reduced scattering coefficients of peaches, using a hyperspectral imaging-based spatially-resolved method, for maturity/quality assessment. A newly developed optical property measuring instrument was used for acquiring hypersp...

  18. Spectral characteristics analysis of red tide water in mesocosm experiment

    NASA Astrophysics Data System (ADS)

    Cui, Tingwei; Zhang, Jie; Zhang, Hongliang; Ma, Yi; Gao, Xuemin

    2003-05-01

    Mesocosm ecosystem experiment with seawater enclosed of the red tide was carried out from July to September 2001. We got four species of biology whose quantities of bion are dominant in the red tide. During the whole process from the beginning to their dying out for every specie, in situ spectral measurements were carried out. After data processing, characteristic spectra of red tide of different dominant species are got. Via comparison and analysis of characteristics of different spectra, we find that in the band region between 685 and 735 nanometers, spectral characteristics of red tide is apparently different from that of normal water. Compared to spectra of normal water, spectra of red tide have a strong reflectance peak in the above band region. As to spectra of red tide dominated by different species, the situations of reflectance peaks are also different: the second peak of Mesodinium rubrum spectrum lies between 726~732 nm, which is more than 21nm away from the other dominant species spectra"s Leptocylindrus danicus"s second spectral peak covers 686~694nm; that of Skeletonema costatum lies between 691~693 nm. Chattonella marina"s second spectral peak lies about 703~705 nm. Thus we can try to determine whether red tide has occurred according to its spectral data. In order to monitor the event of red tide and identify the dominant species by the application of the technology of hyperspectral remote sensing, acquiring spectral data of different dominant species of red tide as much as possible becomes a basic work to be achieved for spectral matching, information extraction and so on based on hyperspectral data.

  19. Quantifying the effect of finite spectral bandwidth on extinction coefficient of species in laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Singh, Manjeet; Singh, Jaswant; Singh, Baljit; Ghanshyam, C.

    2016-11-01

    The aim of this study is to quantify the finite spectral bandwidth effect on laser absorption spectroscopy for a wide-band laser source. Experimental analysis reveals that the extinction coefficient of an analyte is affected by the bandwidth of the spectral source, which may result in the erroneous conclusions. An approximate mathematical model has been developed for optical intensities having Gaussian line shape, which includes the impact of source's spectral bandwidth in the equation for spectroscopic absorption. This is done by introducing a suitable first order and second order bandwidth approximation in the Beer-Lambert law equation for finite bandwidth case. The derived expressions were validated using spectroscopic analysis with higher SBW on a test sample, Rhodamine B. The concentrations calculated using proposed approximation, were in significant agreement with the true values when compared with those calculated with conventional approach.

  20. Spectral reflectance and radiance characteristics of water pollutants

    NASA Technical Reports Server (NTRS)

    Wezernak, C. T.; Turner, R. E.; Lyzenga, D. R.

    1976-01-01

    Spectral reflectance characteristics of water pollutants and water bodies were compiled using the existing literature. Radiance calculations were performed at satellite altitude for selected illumination angles and atmospheric conditions. The work described in this report was limited to the reflective portion of the spectrum between 0.40 micrometer to 1.0 micrometer.

  1. Confirmation of uncontrolled flow dynamics in clinical simulated multi-infusion setups using absorption spectral photometry

    NASA Astrophysics Data System (ADS)

    Timmerman, Anna M.; Riphagen, Brechtje; Klaessens, John H.; Verdaasdonk, Rudolf M.

    2010-02-01

    Multi-infusion systems are used frequently at intensive care units to administer several liquid therapeutic agents to patients simultaneously. By passively combining the separate infusion lines in one central line, the number of punctures needed to access the patient's body, is reduced. So far, the mutual influence between the different infusion lines is unknown. Although the flow properties of single infusion systems have been investigated extensively, only a few research groups have investigated the flow properties of multi-infusion systems. We showed in a previous study that applying multi-infusion can lead to fluctuations in syringe pump infusions, resulting in uncontrolled and inaccurate drug administration. This study presents a performance analysis of multi-infusion systems as used in the Neonatology Intensive Care Unit. The dynamics between multiple infusion lines in multi-infusion systems were investigated by simulation experiments of clinical conditions. A newly developed real-time spectral-photometric method was used for the quantitative determination of concentration and outflow volume using a deconvolution method of absorption spectra of mixed fluids. The effects for common clinical interventions were studied in detail. Results showed mutual influence between the different infusion lines following these interventions. This mutual influence led to significant volume fluctuations up to 50%. These deviations could result in clinically dangerous situations. A complete analysis of the multiinfusion system characteristics is recommended in further research to estimate both the presence and severity of potential risks in clinical use.

  2. Spectral characteristics of ventricular response to atrial fibrillation.

    PubMed

    Hayano, J; Yamasaki, F; Sakata, S; Okada, A; Mukai, S; Fujinami, T

    1997-12-01

    To investigate the spectral characteristics of the fluctuation in ventricular response during atrial fibrillation (AF), R-R interval time series obtained from ambulatory electrocardiograms were analyzed in 45 patients with chronic AF and in 30 age-matched healthy subjects with normal sinus rhythm (SR). Although the 24-h R-R interval spectrum during SR showed a 1/f noise-like downsloping linear pattern when plotted as log power against log frequency, the spectrum during AF showed an angular shape with a breakpoint at a frequency of 0.005 +/- 0.002 Hz, by which the spectrum was separated into long-term and short-term components with different spectral characteristics. The short-term component showed a white noise-like flat spectrum with a spectral exponent (absolute value of the regression slope) of 0.05 +/- 0.08 and an intercept at 10(-2) Hz of 4.9 +/- 0.3 log(ms2/Hz). The long-term component had a 1/f noise-like spectrum with a spectral exponent of 1.26 +/- 0.40 and an intercept at 10(-4) Hz of 7.0 +/- 0.3 log(ms2/Hz), which did not differ significantly from those for the spectrum during SR in the same frequency range [spectral exponent, 1.36 +/- 0.06; intercept at 10(-4) Hz, 7.1 +/- 0.3 log(ms2/Hz)]. The R-R intervals during AF may be a sequence of uncorrelated values over the short term (within several minutes). Over the longer term, however, the R-R interval fluctuation shows the long-range negative correlation suggestive of underlying regulatory processes, and spectral characteristics indistinguishable from those for SR suggest that the long-term fluctuations during AF and SR may originate from similar dynamics of the cardiovascular regulatory systems.

  3. [Laser induced breakdown spectra of coal sample and self-absorption of the spectral line].

    PubMed

    Zhang, Gui-yin; Ji, Hui; Jin, Yi-dong

    2014-12-01

    The LIBS of one kind of household fuel coal was obtained with the first harmonic output 532 nm of an Nd·YAG laser as radiation source. With the assignment of the spectral lines, it was found that besides the elements C, Si, Mg, Fe, Al, Ca, Ti, Na and K, which are reported to be contained in coal, the presented sample also contains trace elements, such as Cd, Co, Hf, Ir, Li, Mn, Ni, Rb, Sr, V, W, Zn, Zr etc, but the spectral lines corresponding to O and H elements did not appear in the spectra. This is owing to the facts that the transition probability of H and O atoms is small and the energy of the upper level for transition is higher. The results of measurement also show that the intensity of spectral line increases with the laser pulse energy and self-absorption of the spectral lines K766.493 nm and K769.921 nm will appear to some extent. Increasing laser energy further will make self-absorption more obvious. The presence of self-absorption can be attributed to two factors. One is the higher transition rate of K atoms, and the other is that the increase in laser intensity induces the enhancement of the particle number density in the plasma.

  4. Light fluence correction for quantitative determination of tissue absorption coefficient using multi-spectral optoacoustic tomography

    NASA Astrophysics Data System (ADS)

    Brochu, Frederic M.; Joseph, James; Tomaszewski, Michal; Bohndiek, Sarah E.

    2015-07-01

    MultiSpectral Optoacoustic Tomography (MSOT) is a fast developing imaging modality, combining the high resolution and penetration depth of ultrasound with the excellent contrast from optical imaging of tissue. Absorption and scattering of the near infrared excitation light modulates the spectral profile of light as it propagates deep into biological tissue, meaning the images obtained provide only qualitative insight into the distribution of tissue chromophores. The goal of this work is to accurately recover the spectral profile of excitation light by modelling light fluence in the data reconstruction, to enable quantitative imaging. We worked with a commercial small animal MSOT scanner and developed our light fluence correction for its' cylindrical geometry. Optoacoustic image reconstruction pinpoints the sources of acoustic waves detected by the transducers and returns the initial pressure amplitude at these points. This pressure is the product of the dimensionless Grüneisen parameter, the absorption coefficient and the light fluence. Under the condition of constant Grüneisen parameter and well modelled light fluence, there is a linear relationship between the initial pressure amplitude measured in the optoacoustic image and the absorption coefficient. We were able to reproduce this linear relationship in different physical regions of an agarose gel phantom containing targets of known optical absorption coefficient, demonstrating that our light fluence model was working. We also demonstrate promising results of light fluence correction effects on in vivo data.

  5. Using high spectral resolution spectrophotometry to study broad mineral absorption features on Mars

    NASA Technical Reports Server (NTRS)

    Blaney, D. L.; Crisp, D.

    1993-01-01

    Traditionally telescopic measurements of mineralogic absorption features have been made using relatively low to moderate (R=30-300) spectral resolution. Mineralogic absorption features tend to be broad so high resolution spectroscopy (R greater than 10,000) does not provide significant additional compositional information. Low to moderate resolution spectroscopy allows an observer to obtain data over a wide wavelength range (hundreds to thousands of wavenumbers) compared to the several wavenumber intervals that are collected using high resolution spectrometers. However, spectrophotometry at high resolution has major advantages over lower resolution spectroscopy in situations that are applicable to studies of the Martian surface, i.e., at wavelengths where relatively weak surface absorption features and atmospheric gas absorption features both occur.

  6. Spectral control of an alexandrite laser for an airborne water-vapor differential absorption lidar system

    NASA Technical Reports Server (NTRS)

    Ponsardin, Patrick; Grossmann, Benoist E.; Browell, Edward V.

    1994-01-01

    A narrow-linewidth pulsed alexandrite laser has been greatly modified for improved spectral stability in an aircraft environment, and its operation has been evaluated in the laboratory for making water-vapor differential absorption lidar measurements. An alignment technique is described to achieve the optimum free spectral range ratio for the two etalons inserted in the alexandrite laser cavity, and the sensitivity of this ratio is analyzed. This technique drastically decreases the occurrence of mode hopping, which is commonly observed in a tunable, two-intracavity-etalon laser system. High spectral purity (greater than 99.85%) at 730 nm is demonstrated by the use of a water-vapor absorption line as a notch filter. The effective cross sections of 760-nm oxygen and 730-nm water-vapor absorption lines are measured at different pressures by using this laser, which has a finite linewidth of 0.02 cm(exp -1) (FWHM). It is found that for water-vapor absorption linewidths greater than 0.04 cm(exp -1) (HWHM), or for altitudes below 10 km, the laser line can be considered monochromatic because the measured effective absorption cross section is within 1% of the calculated monochromatic cross section. An analysis of the environmental sensitivity of the two intracavity etalons is presented, and a closed-loop computer control for active stabilization of the two intracavity etalons in the alexandrite laser is described. Using a water-vapor absorption line as a wavelength reference, we measure a long-term frequency drift (approximately 1.5 h) of less than 0.7 pm in the laboratory.

  7. [Study on spectral reflectance characteristics of hemp canopies].

    PubMed

    Tian, Yi-Chen; Jia, Kun; Wu, Bing-Fang; Li, Qiang-Zi

    2010-12-01

    Hemp (Cannabis sativa L.) is a special economic crop and widely used in many field. It is significative for the government to master the information about planting acreage and spatial distribution of hemp for hemp industrial policy decision in China. Remote sensing offers a potential way of monitoring large area for the cultivation of hemp. However, very little study on the spectral properties of hemp is available in the scientific literature. In the present study, the spectral reflectance characteristics of hemp canopy were systematically analyzed based on the spectral data acquired with ASD FieldSpec portable spectrometer. The wavebands and its spectral resolution for discriminating hemp from other plants were identified using difference analysis. The major differences in canopy reflectance of hemp and other plants were observed near 530, 552, 734, 992, 1 213, 1 580 and 2 199 nm, and the maximal difference is near 734 nm. The spectral resolution should be 30 nm or less in visible and near infrared regions, and 50 nm or less in middle infrared regions.

  8. Performance Characteristics of Hybrid Cycle Combined Absorption Heat Transformer and Absorption Refrigerating Machine

    NASA Astrophysics Data System (ADS)

    Iyoki, Shigeki; Otsuka, Shin-Ichi; Uemura, Tadashi

    In this paper, four kinds of hybrid cycles which combined the single-stage absorption refrigerating machine and four kinds of absorption heat transformers were proposed. It is possible that each of these hybrid cycles gets high temperature and low temperature from one cycle, simultaneously. As basic cycle of absorption heat transformer, the following were chosen: two kinds of single-stage absorption heat transformer and two kinds of two-stage absorption heat transformer. As a working medium-absorbent system, H2O-LiBr system, H2O-LiBr-LiNO3 system, H2O-LiBr-LiNO3-LiCl system, H2O-LiBr-C2H6O2 system and H2O-LiNO3-LiCl system were adopted. Using these five kinds of working medium-absorbent system, the performance characteristics of four kinds of hybrid cycle were simulated. And the performance characteristics of these cycles were compared.

  9. Spectral Characteristics of the Unitary Critical Almost-Mathieu Operator

    NASA Astrophysics Data System (ADS)

    Fillman, Jake; Ong, Darren C.; Zhang, Zhenghe

    2016-10-01

    We discuss spectral characteristics of a one-dimensional quantum walk whose coins are distributed quasi-periodically. The unitary update rule of this quantum walk shares many spectral characteristics with the critical Almost-Mathieu Operator; however, it possesses a feature not present in the Almost-Mathieu Operator, namely singularity of the associated cocycles (this feature is, however, present in the so-called Extended Harper's Model). We show that this operator has empty absolutely continuous spectrum and that the Lyapunov exponent vanishes on the spectrum; hence, this model exhibits Cantor spectrum of zero Lebesgue measure for all irrational frequencies and arbitrary phase, which in physics is known as Hofstadter's butterfly. In fact, we will show something stronger, namely, that all spectral parameters in the spectrum are of critical type, in the language of Avila's global theory of analytic quasiperiodic cocycles. We further prove that it has empty point spectrum for each irrational frequency and away from a frequency-dependent set of phases having Lebesgue measure zero. The key ingredients in our proofs are an adaptation of Avila's Global Theory to the present setting, self-duality via the Fourier transform, and a Johnson-type theorem for singular dynamically defined CMV matrices which characterizes their spectra as the set of spectral parameters at which the associated cocycles fail to admit a dominated splitting.

  10. Spectral Characteristics of the Unitary Critical Almost-Mathieu Operator

    NASA Astrophysics Data System (ADS)

    Fillman, Jake; Ong, Darren C.; Zhang, Zhenghe

    2017-04-01

    We discuss spectral characteristics of a one-dimensional quantum walk whose coins are distributed quasi-periodically. The unitary update rule of this quantum walk shares many spectral characteristics with the critical Almost-Mathieu Operator; however, it possesses a feature not present in the Almost-Mathieu Operator, namely singularity of the associated cocycles (this feature is, however, present in the so-called Extended Harper's Model). We show that this operator has empty absolutely continuous spectrum and that the Lyapunov exponent vanishes on the spectrum; hence, this model exhibits Cantor spectrum of zero Lebesgue measure for all irrational frequencies and arbitrary phase, which in physics is known as Hofstadter's butterfly. In fact, we will show something stronger, namely, that all spectral parameters in the spectrum are of critical type, in the language of Avila's global theory of analytic quasiperiodic cocycles. We further prove that it has empty point spectrum for each irrational frequency and away from a frequency-dependent set of phases having Lebesgue measure zero. The key ingredients in our proofs are an adaptation of Avila's Global Theory to the present setting, self-duality via the Fourier transform, and a Johnson-type theorem for singular dynamically defined CMV matrices which characterizes their spectra as the set of spectral parameters at which the associated cocycles fail to admit a dominated splitting.

  11. The modification of spectral characteristics of cytostatics by optical beams

    NASA Astrophysics Data System (ADS)

    Pascu, Mihail Lucian; Brezeanu, Mihail; Carstocea, Benone D.; Voicu, Letitia; Gazdaru, Doina M.; Smarandache, Adriana A.

    2004-10-01

    Besides the biochemical action of methotrexate (MTX) and 5-fluorouracil (FU) their effect in destroying cancer tumours could be enhanced by exposure to light at different doses. Absorption, excitation and emission spectra of 10-4M - 10-5M MTX solutions in natural saline and sodium hydroxide at pH = 8.4 were measured, while their exposure to coherent and uncoherent light in the visible and near ultraviolet (UV) spectral ranges was made (Hg lamps and Nitrogen pulsed laser radiation were used). Absorption spectra exhibit spectral bands in the range 200 nm - 450 nm. The 200 - 450 nm excitation spectra were measured with emission centered on 470 nm; MTX fluorescence excitation was measured at 390 nm and the emission was detected between 400 nm and 600 nm showing a maximum at 470 nm. Spectra modifications, nonlinearly depending on exposure time (varying from 1 min to 20 min), evidenced MTX photo-dissociation to the fluorescent compound 2,4 diamino-formylpteridine. In the 5-FU case the absorption spectra exhibit bands between 200 nm and 450 nm. The emission fluorescence spectra were measured between 400 nm and 600 nm, with λex = 350 nm for UV Hg lamp and with λex = 360 nm for laser irradiated samples; at irradiation with N2 laser emitted radiation the excitation spectra were measured in the range of 200 nm - 400 nm, with λem = 440 nm. New vascularity rapid destruction was observed for conjunctive impregnated with 5-FU solution whilst exposed to incoherent UV and visible light.

  12. Relating water absorption features to soil moisture characteristics

    NASA Astrophysics Data System (ADS)

    Tian, Jia; Philpot, William D.

    2015-09-01

    The spectral reflectance of a sample of quartz sand was monitored as the sample progressed from air-dry to fully saturated, and then back to air-dry. Wetting was accomplished by spraying small amounts of water on the surface of the sample, and collecting spectra whenever change occurred. Drying was passive, driven by evaporation from the sand surface, with spectra collected every 5 minutes until the sample was air dry. Water content was determined by monitoring the weight of the sample through both wetting and drying. There was a pronounced difference in the pattern of change in reflectance during wetting and drying, with the differences being apparent both in spectral details (i.e., the depth of absorption bands) and in the magnitude of the reflectance for a particular water content. The differences are attributable to the disposition of water in the sample. During wetting, water initially occurred only on the surface, primarily as water adsorbed onto sand particles. With increased wetting the water infiltrated deeper into the sample, gradually covering all particles and filling the pore spaces. During drying, water and air were distributed throughout the sample for most of the drying period. The differences in water distribution are assumed to be the cause of the differences in reflectance and to the differences in the depths of four strong water absorption bands.

  13. Application of Video Spectral Comparator (absorption spectra) for establishing the chronological order of intersecting printed strokes and writing pen strokes.

    PubMed

    Kaur, Ridamjeet; Saini, Komal; Sood, N C

    2013-06-01

    The sequence of intersecting strokes of laser printers (black, blue, red and green) and typewriter ink (black) with the strokes of gel pen ink, ballpoint pen ink and fountain pen ink (black, blue, red and green) has been determined by studying their absorption spectra. The absorption spectra have been generated for each of the two pure inks (i.e. A and B) and points of their intersections (i.e. A over B and B over A) by using Video Spectral Comparator (VSC-2000-HR). The study was carried out with an assumption that the peak characteristics of spectra from the point of intersection should correspond to the peak characteristics of pure ink which was executed later. It was observed that the absorption spectrum of intersection corresponds with either the laser printer or the typewriter ink stroke, whether these strokes were executed earlier or later than the writing instrument strokes. As the results obtained from the study were negative, the FDEs are advised against the practice of this technique in the examination of the sequence of intersecting strokes for these specified inks.

  14. Water vapor absorption coefficients in the 8-13-micron spectral region - A critical review

    NASA Technical Reports Server (NTRS)

    Grant, William B.

    1990-01-01

    Measurements of water vapor absorption coefficients in the thermal IR atmospheric window (8-13 microns) during the past 20 years obtained by a variety of techniques are reviewed for consistency and compared with computed values based on the AFGL spectral data tapes. The methods of data collection considered were atmospheric long path absorption with a CO2 laser or a broadband source and filters, a White cell and a CO2 laser or a broadband source and a spectrometer, and a spectrophone with a CO2 laser. Advantages and disadvantages of each measurement approach are given as a guide to further research. Continuum absorption has apparently been measured accurately to about the 5-10 percent level in five of the measurements reported.

  15. Dynamic energy absorption characteristics of hollow microlattice structures

    SciTech Connect

    Liu, YL; Schaedler, TA; Chen, X

    2014-10-01

    Hollow microlattice structures are promising candidates for advanced energy absorption and their characteristics under dynamic crushing are explored. The energy absorption can be significantly enhanced by inertial stabilization, shock wave effect and strain rate hardening effect. In this paper we combine theoretical analysis and comprehensive finite element method simulation to decouple the three effects, and then obtain a simple model to predict the overall dynamic effects of hollow microlattice structures. Inertial stabilization originates from the suppression of sudden crushing of the microlattice and its contribution scales with the crushing speed, v. Shock wave effect comes from the discontinuity across the plastic shock wave front during dynamic loading and its contribution scales with e. The strain rate effect increases the effective yield strength upon dynamic deformation and increases the energy absorption density. A mechanism map is established that illustrates the dominance of these three dynamic effects at a range of crushing speeds. Compared with quasi-static loading, the energy absorption capacity a dynamic loading of 250 m/s can be enhanced by an order of magnitude. The study may shed useful insight on designing and optimizing the energy absorption performance of hollow microlattice structures under various dynamic loads. (C) 2014 Elsevier Ltd. All rights reserved.

  16. Synthetic absorption lines for a clumpy medium: a spectral signature for cloud acceleration in AGN?

    NASA Astrophysics Data System (ADS)

    Waters, Tim; Proga, Daniel; Dannen, Randall; Kallman, Timothy R.

    2017-01-01

    There is increasing evidence that the highly ionised multiphase components of AGN disc winds may be due to thermal instability. The ions responsible for forming the observed X-ray absorption lines may only exist in relatively cool clumps that can be identified with the so-called `warm absorbers'. Here we calculate synthetic absorption lines for such warm absorbers from first principles by combining 2D hydrodynamic solutions of a two-phase medium with a dense grid of photoionization models to determine the detailed ionization structure of the gas. Our calculations reveal that cloud disruption, which leads to a highly complicated velocity field (i.e. a clumpy flow), will only mildly affect line shapes and strengths when the warm gas becomes highly mixed but not depleted. Prior to complete disruption, clouds which are optically thin to the driving UV resonance lines will cause absorption at an increasingly blueshifted line of sight velocity as they are accelerated. This behavior will imprint an identifiable signature on the line profile if warm absorbers are enshrouded in an even broader absorption line produced by a high column of intercloud gas. Interestingly, we show that it is possible to develop a spectral diagnostic for cloud acceleration by differencing the absorption components of a doublet line, a result which can be qualitatively understood using a simple partial covering model. Our calculations also permit us to comment on the spectral differences between cloud disruption and ionization changes driven by flux variability. Notably, cloud disruption offers another possibility for explaining absorption line variability.

  17. The NSLS VUV undulator: Spectral characteristics and operating experience

    SciTech Connect

    Johnson, P.D.; Galayda, J.; Hulbert, S.L.; Klaffky, R.W.; Luccio, A.; Vignola, G.; Jacobsen, C.

    1987-01-01

    The design and operating characteristics of the VUV undulator installed on the NSLS VUV ring are presented. Specifically, the spectral output through three circular on-axis pinholes of different diameters has been measured. Near the minimum magnetic gap (40mm), the flux into a 0.25 mrad circular aperture at the peak of the fundamental (h..nu.. = 57 eV) is approx.1 /times/ 10/sup 14/ photonssec0.1A1%BW. We find good agreement in spectral shape between these measured spectra and spectra calculated by integrating the theoretical undulator emission spectrum over the relevant spatial variables and including electron beam emittance. We also show calculated zero-emittance and on-axis flux spectra for comparison. A description is given of the beam line and monochromator currently installed on this undulator for the purpose of performing spin-resolved photoemission.

  18. Effect of solid-phase amorphization on the spectral characteristics of europium-doped gadolinium molybdate

    NASA Astrophysics Data System (ADS)

    Shmurak, S. Z.; Kiselev, A. P.; Kurmasheva, D. M.; Red'Kin, B. S.; Sinitsyn, V. V.

    2010-05-01

    A method is proposed for detecting spectral characteristics of optically inactive molybdates of rare-earth elements by their doping with rare-earth ions whose luminescence lies in the transparency region of all structural modifications of the sample. Gadolinium molybdate is chosen as the object of investigations, while europium ions are used as an optically active and structurally sensitive admixture. It is shown that after the action of a high pressure under which gadolinium molybdate passes to the amorphous state, the spectral characteristics of Gd1.99Eu0.01(MoO4)3 (GMO:Eu) change radically; namely, considerable line broadening is observed in the luminescence spectra and the luminescence excitation spectra, while the long-wave threshold of optical absorption is shifted considerably (by approximately 1.1 eV) towards lower energies. It is found that by changing the structural state of GMO:Eu by solid-state amorphization followed by annealing, the spectral characteristics of the sample can be purposefully changed. This is extremely important for solving the urgent problem of designing high-efficiency light-emitting diodes producing “white” light.

  19. Spectral dependence of absorption sensitivity on concentration of oxygenated hemoglobin: pulse oximetry implications.

    PubMed

    Strojnik, Marija; Paez, Gonzalo

    2013-10-01

    The sensitivity analysis indicates that the effective absorption coefficient is most sensitive to the concentration of oxygenated hemoglobin in spectral bands centered at 700 and 960 nm. We find that the highest temporal modulation due to heart function for a thick sample, like an arm, is at 940 nm, a significant shift from 710 nm measured for a finger. The most favorable spectral region for a thick transmission sample, such as a forearm, is the domain defined by intervals [900  nm ≤ λ₁ ≤ 1000  nm] and [650 nm ≤ λ₂ ≤ 720  nm]. We evaluated five near-infrared light-emitting diodes (LEDs) for their potential applications in oximetry. The LED with peak emission at 930 nm emits well in this spectral region. Here the temporal noise is low, and the effective absorption coefficient is strongly dependent on the concentration of the oxygenated hemoglobin. High-quality saturation results are obtained through the forearm during a short measurement (30 s).

  20. ON NEUTRAL ABSORPTION AND SPECTRAL EVOLUTION IN X-RAY BINARIES

    SciTech Connect

    Miller, J. M.; Cackett, E. M.; Reis, R. C.

    2009-12-10

    Current X-ray observatories make it possible to follow the evolution of transient and variable X-ray binaries across a broad range in luminosity and source behavior. In such studies, it can be unclear whether evolution in the low-energy portion of the spectrum should be attributed to evolution in the source, or instead to evolution in neutral photoelectric absorption. Dispersive spectrometers make it possible to address this problem. We have analyzed a small but diverse set of X-ray binaries observed with the Chandra High Energy Transmission Grating Spectrometer across a range in luminosity and different spectral states. The column density in individual photoelectric absorption edges remains constant with luminosity, both within and across source spectral states. This finding suggests that absorption in the interstellar medium strongly dominates the neutral column density observed in spectra of X-ray binaries. Consequently, evolution in the low-energy spectrum of X-ray binaries should properly be attributed to evolution in the source spectrum. We discuss our results in the context of X-ray binary spectroscopy with current and future X-ray missions.

  1. Mechanical properties and energy absorption characteristics of a polyurethane foam

    SciTech Connect

    Goods, S.H.; Neuschwanger, C.L.; Henderson, C.; Skala, D.M.

    1997-03-01

    Tension, compression and impact properties of a polyurethane encapsulant foam have been measured as a function of foam density. Significant differences in the behavior of the foam were observed depending on the mode of testing. Over the range of densities examined, both the modulus and the elastic collapse stress of the foam exhibited power-law dependencies with respect to density. The power-law relationship for the modulus was the same for both tension and compression testing and is explained in terms of the elastic compliance of the cellular structure of the foam using a simple geometric model. Euler buckling is used to rationalize the density dependence of the collapse stress. Neither tension nor compression testing yielded realistic measurements of energy absorption (toughness). In the former case, the energy absorption characteristics of the foam were severely limited due to the inherent lack of tensile ductility. In the latter case, the absence of a failure mechanism led to arbitrary measures of energy absorption that were not indicative of true material properties. Only impact testing revealed an intrinsic limitation in the toughness characteristics of the material with respect to foam density. The results suggest that dynamic testing should be used when assessing the shock mitigating qualities of a foam.

  2. Collisional Induced Absorption (CIA) bands measured in the IR spectral range .

    NASA Astrophysics Data System (ADS)

    Stefani, S.; Piccioni, G.; Snels, M.; Adriani, A.; Grassi, D.

    In this work we present two experimental setup able to characterize the optical properties of gases, in particular CO_2 and H_2, at typically planetary conditions. The apparatus consists of a Fourier Transform InfraRed (FT-IT) interferometer able to work in a wide spectral range, from 350 to 25000 cm-1 (0.4 to 29 mu m ) with a relatively high spectral resolution, from 10 to 0.07 cm-1. Two dedicated gas cells have been integrated with the FT-IR. The first, called High Pressure High Temperature (HP-HT), can support pressures up to 300 bar, temperatures up to 300oC and is characterized by an optical path of 2 cm. The second one, a Multi Pass (MP) absorption gas cell, is designed to have a variable optical path, from 2.5 to 30 m, can be heated up to 200o and operate at pressures up to 10 bar. In this paper, measurements of Collision-Induced Absorption (CIA) bands in carbon dioxide and hydrogen recorded in the InfraRed spectral range will be presented. In principle, linear symmetric molecules such as CO_2 and H_2 possess no dipole moment, but, even when the pressure is only a few bar, we have observed the Collisional Induced Absorption (CIA) bands. This absorption results from a short-time collisional interaction between molecules. The band integrated intensity shows a quadratic dependence versus density opposed to the absorption by isolated molecules, which follows Beer's law \\citep{Beer's}. This behaviour suggests an absorption by pairs rather than by individual molecules. The bands integrated intensities show a linear dependence vs square density according to \\citep {CIA Shape} and \\citep{CIA posi}. For what concerns the H_2 CIA bands, a preliminary comparison between simulated data obtained with the model described in \\citep{CIA H2}and measured, shows a good agreement. These processes are very relevant in the dense atmospheres of planets, such as those of Venus and Jupiter and also in extrasolar planets. A detailed knowledge of these contributions is very

  3. Spectral characteristics of VUV radiation emitted by a laser plume

    SciTech Connect

    Khater, Mohamed A.

    2013-12-16

    We study some experimental parameters and conditions of laser-generated plasma plumes using time-integrated, spatially resolved emission spectroscopy in the VUV range. The influences of the laser focusing lens type, laser wavelength, as well as laser pulse energy on the emission characteristics of the laser plasmas are investigated. The aim of the work is to improve the detection capability of the laser-induced plasma spectroscopy (LIPS) technique. The results obtained demonstrate a set of optimum conditions for maximum spectral line intensities and signal-to-background ratios of laser-produced plasmas in the VUV regime.

  4. Spectral characteristics of speech with fixed jaw displacements

    NASA Astrophysics Data System (ADS)

    Solomon, Nancy P.; Makashay, Matthew J.; Munson, Benjamin

    2004-05-01

    During speech, movements of the mandible and the tongue are interdependent. For some research purposes, the mandible may be constrained to ensure independent tongue motion. To examine specific spectral characteristics of speech with different jaw positions, ten normal adults produced sentences with multiple instances of /t/, /s/, /squflg/, /i/, /ai/, and /squflgi/. Talkers produced stimuli with the jaw free to vary, and while gently biting on 2- and 5-mm bite blocks unilaterally. Spectral moments of /s/ and /squflg/ frication and /t/ bursts differed such that mean spectral energy decreased, and diffuseness and skewness increased with bite blocks. The specific size of the bite block had minimal effect on these results, which were most consistent for /s/. Formant analysis for the vocoids revealed lower F2 frequency in /i/ and at the end of the transition in /ai/ when bite blocks were used; F2 slope for diphthongs was not sensitive to differences in jaw position. Two potential explanations for these results involve the physical presence of the bite blocks in the lateral oral cavity, and the oromotor system's ability to compensate for fixed jaw displacements. [Work supported by NIDCD R03-DC06096.

  5. Effect of input spectrum on the spectral switch characteristics in a white-light Michelson interferometer.

    PubMed

    Brundavanam, Maruthi M; Viswanathan, Nirmal K; Rao, D Narayana

    2009-12-01

    We report here a detailed experimental study to demonstrate the effect of source spectral characteristics such as spectral bandwidth (Deltalambda), peak wavelength (lambda(0)), and shape of the spectrum on the spectral shifts and spectral switches measured due to temporal correlation in a white-light Michelson interferometer operated in the spectral domain. Behavior of the spectral switch characteristics such as the switch position, switch amplitude, and switch symmetry are discussed in detail as a function of optical path difference between the interfering beams. The experimental results are compared with numerical calculations carried out using interference law in the spectral domain with modified source spectral characteristics. On the basis of our results we feel that our study is of critical importance in the selection of source spectral characteristics to further improve the longitudinal resolution or the measurement sensitivity in spectral-domain optical coherence tomography and microscopy.

  6. Reconfiguration of spectral absorption features using a frequency-chirped laser pulse.

    PubMed

    Tian, Mingzhen; Chang, Tiejun; Merkel, Kristian D; Babbitt, W Randall

    2011-12-20

    A technique is proposed to manipulate atomic population in an inhomogeneously broadened medium, which can set an arbitrary absorption spectrum to a uniform transparency (erasure) or to a nearly complete inversion. These reconfigurations of atomic spectral distribution are achieved through excitation of electronic transitions using a laser pulse with chirped frequency, which precisely affects selected spectral regions while leaving the rest of the spectrum unperturbed. An erasure operation sets the final atomic population inversion to zero and the inversion operation flips the population between the ground and the excited states, regardless of the previously existing population distribution. This technique finds important applications both in optical signal processing, where fast, recursive processing and high dynamic range are desirable and in quantum memory and quantum computing, which both require high efficiency and high fidelity in quantum state preparation of atomic ensembles. Proof-of-concept demonstrations were performed in a rare-earth doped crystal.

  7. Spectral characteristics of chlorites and Mg-serpentines using high- resolution reflectance spectroscopy

    USGS Publications Warehouse

    King, T.V.V.; Clark, R.N.

    1989-01-01

    The present laboratory study using high-resolution reflectance spectroscopy (0.25-2.7 ??m) focuses on two primary phyllosilicate groups, serpentines and chlorites. The results show that it is possible to spectrally distinguish between isochemical end-members of the Mg-rich serpentine group (chrysotile, antigorite, and lizardite) and to recognize spectral variations in chlorites as a function of Fe/Mg ratio (~8-38 wt% Fe). The position and relative strength of the 1.4-??m absorption feature in the trioctahedral chlorites appear to be correlated to the total iron content and/or the Mg/Si ratio and the loss on ignition values of the sample. Spectral differences in the 2.3-??m wavelength region can be attributed to differences in lattice environments and are characteristic for specific trioctahedral chlorites. The 1.4-??m feature in the isochemical Mg-rich serpentines (total iron content ~1.5-7.0 wt%) show marked spectral differences, apparently due to structural differences. -Authors

  8. Analysis Of Spectrally Selective Liquid Absorption Filters For Hybrid Solar Energy Conversion

    NASA Astrophysics Data System (ADS)

    Chendo, M. A. C.; Osborn, D. E.; Swenson, Rick

    1985-12-01

    Various techniques have been proposed to convert solar energy to both electric power and heat in hybrid systems. Many of these approaches are designed to utilize spectral selectivity to improve the overall conversion efficiency. Examples include spectrally selective beamsplitters and arrangements of long-wave or short-wave-pass glass filters that divide the spectrum so that photon energies are roughly matched to the energies corresponding to the solar-cell bandgaps or to efficient photothermal convertors. This paper describes the analysis of liquid optical filters that have high transmittance in the visible spectrum and high absorptance in the infrared. These qualities make it possible to capture that portion of the spectrum useful to a quantum convertor, such as a photovoltaic cell, while channeling the "excess heat" of the photons with energies below the bandgap to a thermal convertor, thereby enhancing the overall conversion efficiency of the system. The preliminary studies show that spectral responses of the tested solutions (salts in water) are primarily influenced by the cation component of the salt solution. By changing the solutions and concentrations, a variety of spectrally selective filters can be tailored to match system requirements.

  9. High Spectral Resolution Lidar Measurements Using an I2 Absorption Filter

    NASA Technical Reports Server (NTRS)

    Eloranta, E. W.; Piironen, P.

    1996-01-01

    The University of Wisconsin high spectral resolution lidar (HSRL) measures optical properties of the atmosphere by separating the Doppler-broadened molecular backscatter return from the unbroadened aerosol return. The HSRL was modified to use an I2 absorption cell The modified HSRL transmitter uses a continuously pumped, Q-switched, injection seeded, frequency doubled Nd:YAG laser operating at a 4 kHz pulse repetition rate. This laser is tunable over a 124 GHz frequency range by temperature tuning the seed laser under computer control.

  10. Spectral Absorption of Solar Radiation by Aerosols during ACE-Asia

    NASA Technical Reports Server (NTRS)

    Bergstrom, R. W.; Pilewskie, P.; Pommier, J.; Rabbette, M.; Russell, P. B.; Schmid, B.; Redermann, J.; Higurashi, A.; Nakajima, T.; Quinn, P. K.

    2004-01-01

    As part of the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia), the upward and downward spectral solar radiant fluxes were measured with the Spectral Solar Flux Radiometer (SSFR), and the aerosol optical depth was measured with the Ames Airborne Tracking Sunphotometer (AATS-14) aboard the Center for INterdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft. IN this paper, we examine the data obtained for two cases: a moderately thick aerosol layer, 12 April, and a relatively thin aerosol case, 16 April 2001. ON both days, the Twin Otter flew vertical profiles in the Korean Strait southeast of Gosan Island. For both days we determine the aerosol spectral absorption of the layer and estimate the spectral aerosol absorption optical depth and single-scattering albedo. The results for 12 April show that the single-scattering albedo increases with wavelength from 0.8 at 400 nm to 0.95 at 900 nm and remains essentially constant from 950 to 1700 nm. On 16 April the amount of aerosol absorption was very low; however, the aerosol single-scattering albedo appears to decrease slightly with wavelength in the visible region. We interpret these results in light of the two absorbing aerosol species observed during the ACE-asia study: mineral dust and black carbon. The results for 12 April are indicative of a mineral dust-black carbon mixture. The 16 April results are possibly caused by black carbon mixed with nonabsorbing pollution aerosols. For the 12 April case we attempt to estimate the relative contributions of the black carbon particles and the mineral dust particles. We compare our results with other estimates of the aerosol properties from a Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) satellite analysis and aerosol measurements made aboard the Twin Otter, aboard the National Oceanic and Atmospheric Administration Ronald H Brown ship, and at ground sites in Gosan and Japan. The results indicate a relatively complicated aerosol

  11. Propagation of ultrashort laser pulses in water: linear absorption and onset of nonlinear spectral transformation.

    PubMed

    Sokolov, Alexei V; Naveira, Lucas M; Poudel, Milan P; Strohaber, James; Trendafilova, Cynthia S; Buck, William C; Wang, Jieyu; Strycker, Benjamin D; Wang, Chao; Schuessler, Hans; Kolomenskii, Alexandre; Kattawar, George W

    2010-01-20

    We study propagation of short laser pulses through water and use a spectral hole filling technique to essentially perform a sensitive balanced comparison of absorption coefficients for pulses of different duration. This study is motivated by an alleged violation of the Bouguer-Lambert-Beer law at low light intensities, where the pulse propagation is expected to be linear, and by a possible observation of femtosecond optical precursors in water. We find that at low intensities, absorption of laser light is determined solely by its spectrum and does not directly depend on the pulse duration, in agreement with our earlier work and in contradiction to some work of others. However, as the laser fluence is increased, interaction of light with water becomes nonlinear, causing energy exchange among the pulse's spectral components and resulting in peak-intensity dependent (and therefore pulse-duration dependent) transmission. For 30 fs pulses at 800 nm center wavelength, we determine the onset of nonlinear propagation effects to occur at a peak value of about 0.12 mJ/cm(2) of input laser energy fluence.

  12. Polarization control efficiency manipulation in resonance-mediated two-photon absorption by femtosecond spectral frequency modulation

    NASA Astrophysics Data System (ADS)

    Yao, Yunhua; Cheng, Wenjing; Zheng, Ye; Xu, Cheng; Liu, Pei; Jia, Tianqing; Qiu, Jianrong; Sun, Zhenrong; Zhang, Shian

    2017-04-01

    The femtosecond laser polarization modulation is considered as a very simple and efficient method to control the multi-photon absorption process. In this work, we theoretically and experimentally show that the polarization control efficiency in the resonance-mediated two-photon absorption can be artificially manipulated by modulating the femtosecond spectral frequency components. We theoretically demonstrate that the on- and near-resonant parts in the resonance-mediated two-photon absorption process depend on the different femtosecond spectral frequency components, and therefore their contributions in the whole excitation process can be controlled by properly designing the femtosecond spectral frequency components. The near-resonant two-photon absorption is correlated with the femtosecond laser polarization while the on-resonant two-photon absorption is independent of it, and thus the polarization control efficiency in the resonance-mediated two-photon absorption can be manipulated by the femtosecond spectral frequency modulation. We experimentally verify these theoretical results by performing the laser polarization control experiment in the Dy3+-doped glass sample under the modulated femtosecond spectral frequency components, and the experimental results show that the polarization control efficiency can be increased when the central spectral frequency components are cut off, while it is decreased when both the low and high spectral frequency components are cut off, which is in good agreement with the theoretical predictions. Our works can provide a feasible pathway to understand and control the resonance-mediated multi-photon absorption process under the femtosecond laser field excitation, and also may open a new opportunity to the related application areas.

  13. An investigation of spectral characteristics of water-glucose solutions

    NASA Astrophysics Data System (ADS)

    Lastovskaia, Elena A.; Gorbunova, Elena V.; Chertov, Aleksandr N.; Korotaev, Valery V.

    2016-04-01

    One of the problems of modern medical device engineering is the development of an instrument for non-invasive monitoring of glucose levels in the blood. The urgency of this task is ensured by the following facts: the increase in the incidence of diabetes, the need for regular monitoring of blood sugar, and pain of modern methods of glycemia measurement. The problem can be solved with the help of a spectrophotometric method. This report is devoted to the investigation of spectral characteristics of glucose solution with various molar concentrations. The authors proposed the methodology of experimental research and data processing algorithm. The results of the experimental studies confirmed potential opportunity of blood sugar control by spectrophotometric method. Further research is expected to continue by the way of complication of the composition of the object from an aqueous solution of glucose to biological object.

  14. SimBAL: A Spectral Synthesis Approach to Analyzing Broad Absorption Line Quasar Spectra

    NASA Astrophysics Data System (ADS)

    Terndrup, Donald M.; Leighly, Karen; Gallagher, Sarah; Richards, Gordon T.

    2017-01-01

    Broad Absorption Line quasars (BALQSOs) show blueshifted absorption lines in their rest-UV spectra, indicating powerful winds emerging from the central engine. These winds are essential part of quasars: they can carry away angular momentum and thus facilitate accretion through a disk, they can distribute chemically-enriched gas through the intergalactic medium, and they may inject kinetic energy to the host galaxy, influencing its evolution. The traditional method of analyzing BALQSO spectra involves measuring myriad absorption lines, computing the inferred ionic column densities in each feature, and comparing with the output of photonionization models. This method is inefficient and does not handle line blending well. We introduce SimBAL, a spectral synthesis fitting method for BALQSOs, which compares synthetic spectra created from photoionization model results with continuum-normalized observed spectra using Bayesian model calibration. We find that we can obtain an excellent fit to the UV to near-IR spectrum of the low-redshift BALQSO SDSS J0850+4451, including lines from diverse ionization states such as PV, CIII*, SIII, Lyalpha, NV, SiIV, CIV, MgII, and HeI*.

  15. Origin of the characteristic X-ray spectral variations of IRAS 13224-3809

    NASA Astrophysics Data System (ADS)

    Yamasaki, Hiroki; Mizumoto, Misaki; Ebisawa, Ken; Sameshima, Hiroaki

    2016-10-01

    The narrow-line Seyfert 1 galaxy (NLS1) IRAS 13224-3809 is known to exhibit significant X-ray spectral variation, a sharp spectral drop at ˜7 keV, strong soft excess emission, and a hint of an iron L-edge feature, which is very similar to the NLS1 1H 0707-495. We have proposed the "Variable Double Partial Covering (VDPC) model" to explain the energy spectra and spectral variability of 1H 0707-495 (Mizumoto et al. 2014, PASJ, 66, 122). In this model, the observed flux/spectral variations below 10 keV within ˜ a day are primarily caused by change of the partial covering fraction of patchy clouds composed by double absorption layers in the line of sight. In this paper, we apply the VDPC model to IRAS 13224-3809. Consequently, we have found that the VDPC model can explain the observed spectral variations of IRAS 13224-3809 in the 0.5-10 keV band. In particular, we can explain the observed root mean square (RMS) spectra (energy dependence of the fractional flux variation) in the entire 0.5-10 keV band. In addition to the well-known significant drop in the iron K-band, we have found intriguing iron L-peaks in the RMS spectra when the iron L-edge is particularly deep. This feature, which is also found in 1H 0707-495, is naturally explained with the VDPC model, such that the RMS variations increase at the energies where optical depths of the partial absorbers are large. The absorbers have a larger optical depth at the iron L-edge than in the adjacent energy bands, and thus a characteristic iron L-peak appears. On the other hand, just below the iron K-edge, the optical depth is the lowest and the RMS spectrum has a broad dip.

  16. DFT analysis and spectral characteristics of Celecoxib a potent COX-2 inhibitor

    NASA Astrophysics Data System (ADS)

    Vijayakumar, B.; Kannappan, V.; Sathyanarayanamoorthi, V.

    2016-10-01

    Extensive quantum mechanical studies are carried out on Celecoxib (CXB), a new generation drug to understand the vibrational and electronic spectral characteristics of the molecule. The vibrational frequencies of CXB are computed by HF and B3LYP methods with 6-311++G (d, p) basis set. The theoretical scaled vibrational frequencies have been assigned and they agreed satisfactorily with experimental FT-IR and Raman frequencies. The theoretical maximum wavelength of absorption of CXB are calculated in water and ethanol by TD-DFT method and these values are compared with experimentally determined λmax values. The spectral and Natural bonds orbital (NBO) analysis in conjunction with spectral data established the presence of intra molecular interactions such as mesomeric, hyperconjugative and steric effects in CXB. The electron density at various positions and reactivity descriptors of CXB indicate that the compound functions as a nucleophile and establish that aromatic ring system present in the molecule is the site of drug action. Electronic distribution and HOMO - LUMO energy values of CXB are discussed in terms of intra-molecular interactions. Computed values of Mulliken charges and thermodynamic properties of CXB are reported.

  17. X-ray Spectral Characteristics of V1432 Aquilae: An Unusual Hot Polar

    NASA Astrophysics Data System (ADS)

    Rana, V. R.; Singh, K. P.; Barrett, P. E.

    2005-08-01

    Results from spectral analysis of X-ray data with the RXTE and XMM-Newton for an asynchronous polar V1432 Aql are presented based on two spectral models -- a multi-temperature plasma model and a photo-ionized plasma model. Using a multi-temperature plasma model, the RXTE PCA data are used to constrain the mass of the white dwarf to be 1.2±0.1 M⊙. A strong soft X-ray excess below 0.8 keV, seen with XMM MOS, is modelled by a black body component having temperature of 80-90 eV. The emission lines seen at 6.7 and 7.0 keV are well fit using the multi-temperature plasma model, however the 6.4 keV line requires an additional Gaussian component. Two absorbers, one that fully covers the source and another that covers ˜ 65% of the source are required. The results from spin phase resolved spectroscopy indicate varying absorption parameters and varying 6.4 keV line flux. X-ray spectral characteristics and their variation with the spin period suggest that V1432 Aql is an unusual hot Polar. The photo-ionized plasma model with a range of column densities for the Fe ions gives a slightly better overall fit and fits all emission line features.

  18. Atmospheric-water absorption features near 2.2 micrometers and their importance in high spectral resolution remote sensing

    NASA Technical Reports Server (NTRS)

    Kruse, F. A.; Clark, R. N.

    1986-01-01

    Selective absorption of electromagnetic radiation by atmospheric gases and water vapor is an accepted fact in terrestrial remote sensing. Until recently, only a general knowledge of atmospheric effects was required for analysis of remote sensing data; however, with the advent of high spectral resolution imaging devices, detailed knowledge of atmospheric absorption bands has become increasingly important for accurate analysis. Detailed study of high spectral resolution aircraft data at the U.S. Geological Survey has disclosed narrow absorption features centered at approximately 2.17 and 2.20 micrometers not caused by surface mineralogy. Published atmospheric transmission spectra and atmospheric spectra derived using the LOWTRAN-5 computer model indicate that these absorption features are probably water vapor. Spectral modeling indicates that the effects of atmospheric absorption in this region are most pronounced in spectrally flat materials with only weak absorption bands. Without correction and detailed knowledge of the atmospheric effects, accurate mapping of surface mineralogy (particularly at low mineral concentrations) is not possible.

  19. Spectral Light Absorption and Scattering by Aerosol Particles in Central Amazonia

    NASA Astrophysics Data System (ADS)

    Artaxo, P.; Holanda, B. A.; Ferreira De Brito, J.; Carbone, S.; Barbosa, H. M.; Rizzo, L. V.; Cirino, G. G.; Andreae, M. O.; Saturno, J.; Pöhlker, C.; Martin, S. T.; Holben, B. N.; Schafer, J.

    2015-12-01

    As part of the GoAmazon2014/5, a detailed characterization of spectral light absorption and light scattering was performed at four research sites located in the central Amazon forest at different distances upwind and downwind of Manaus. The sites ATTO (T0a) and Embrapa (T0e) are located upwind of Manaus where it is possible to observe very pristine atmospheric conditions in wet season. The site Tiwa (T2) is being operated under the direct influence of the Manaus plume at 5 km downwind of Manaus and, finally, the Manacapuru (T3) site is located at about 60 km downwind of Manaus. The spectral dependence of light absorption and light scattering were measured using Aethalometers (7-wavelengths) and Nephelometers (3-wavelengths), respectively. By calculating the Absorption Angstrom Exponent (AAE), it was possible to get information about the source of the aerosol whereas the Scattering Angstrom Exponent (SAE) gives information about its size distribution. Sunphotometers from the AERONET network were set up at T3 and T0e sites to measure column Aerosol Optical Depth (AOD). For all the stations, much higher absorption and scattering coefficients were observed during the dry season in comparison to the wet season, as a result of the larger concentration of BC and OC present in the biomass burning events. Additionally, we also observed Manaus plume pollution that alters the BC signal. There is also an increase of the AAE during the dry season due to the larger amount of aerosols from biomass burning compared with urban pollution. High values of AAE are also observed during the wet season, attributed to the presence of long-range transport of aerosols from Africa. The SAE for all the sites are lower during the wet season, with the dominance of large biological particles, and increases during the dry season as a consequence of fine particles emitted from both biomass and fossil fuel burning. The AOD at T0e and T3 (Jan-Jun/2014) showed very similar values ranging from 0.05 to

  20. Spectral characteristics of high-latitude raw 40 MHz cosmic noise signals

    NASA Astrophysics Data System (ADS)

    Hall, Chris M.

    2016-08-01

    Cosmic noise at 40 MHz is measured at Ny-Ålesund (79° N, 12° E) using a relative ionospheric opacity meter ("riometer"). A riometer is normally used to determine the degree to which cosmic noise is absorbed by the intervening ionosphere, giving an indication of ionisation of the atmosphere at altitudes lower than generally monitored by other instruments. The usual course is to determine a "quiet-day" variation, this representing the galactic noise signal itself in the absence of absorption; the current signal is then subtracted from this to arrive at absorption expressed in decibels (dB). By a variety of means and assumptions, it is thereafter possible to estimate electron density profiles in the very lowest reaches of the ionosphere. Here however, the entire signal, i.e. including the cosmic noise itself, will be examined and spectral characteristics identified. It will be seen that distinct spectral subranges are evident which can, in turn, be identified with non-Gaussian processes characterised by generalised Hurst exponents, α. Considering all periods greater than 1 h, α ≈ 24, an indication of fractional Brownian motion, whereas for periods greater than 1 day α ≈ 0.9 - approximately pink noise and just in the domain of fractional Gaussian noise. The results are compared with other physical processes, suggesting that absorption of cosmic noise is characterised by a generalised Hurst exponent ≈ 1.24 and thus non-persistent fractional Brownian motion, whereas generation of cosmic noise is characterised by a generalised Hurst exponent ≈ 1. The technique unfortunately did not result in clear physical understanding of the ionospheric phenomena, and thus, in this respect, the application was not successful; the analysis could, however, be used as a tool for instrument validation.

  1. Numerical calculations of spectral turnover and synchrotron self-absorption in CSS and GPS radio sources

    NASA Astrophysics Data System (ADS)

    Jeyakumar, S.

    2016-06-01

    The dependence of the turnover frequency on the linear size is presented for a sample of Giga-hertz Peaked Spectrum and Compact Steep Spectrum radio sources derived from complete samples. The dependence of the luminosity of the emission at the peak frequency with the linear size and the peak frequency is also presented for the galaxies in the sample. The luminosity of the smaller sources evolve strongly with the linear size. Optical depth effects have been included to the 3D model for the radio source of Kaiser to study the spectral turnover. Using this model, the observed trend can be explained by synchrotron self-absorption. The observed trend in the peak-frequency-linear-size plane is not affected by the luminosity evolution of the sources.

  2. Spectral fluorescence signature techniques and absorption measurements for continuous monitoring of biofuel-producing microalgae cultures

    NASA Astrophysics Data System (ADS)

    Martín de la Cruz, M. C.; Gonzalez Vilas, L.; Yarovenko, N.; Spyrakos, E.; Torres Palenzuela, J. M.

    2013-08-01

    Biofuel production from microalgae can be both sustainable and economically viable. Particularly in the case of algal growth in wastewater an extra benefit is the removal or biotransformation of pollutants from these types of waters. A continuous monitoring system of the microalgae status and the concentration of different wastewater contaminants could be of great help in the biomass production and the water characterisation. In this study we present a system where spectral fluorescence signature (SFS) techniques are used along with absorption measurements to monitor microalgae cultures in wastewater and other mediums. This system aims to optimise the microalgae production for biofuel applications or other uses and was developed and tested in prototype indoor photo-bioreactors at the University of Vigo. SFS techniques were applied using the fluorescence analyser INSTAND-SCREENER developed by Laser Diagnostic Instruments AS. INSTAND-SCREENER permits wavelength scanning in two modes, one in UV and another in VIS. In parallel, it permits the on-line monitoring and rapid analysis of both water quality and phytoplankton status without prior treatment of the sample. Considering that different contaminants and microalgae features (density, status etc.) have different spectral signatures of fluorescence and absorption properties, it is possible to characterise them developing classification libraries. Several algorithms were used for the classification. The implementation of this system in an outdoor raceway reactor in a Spanish wastewater treatment plant is also discussed. This study was part of the Project EnerBioAlgae (http://www.enerbioalgae.com/), which was funded by the Interreg SUDOE and led by the University of Vigo.

  3. Influence of environmental factors on spectral characteristic of chromophoric dissolved organic matter (CDOM) in Inner Mongolia Plateau, China

    NASA Astrophysics Data System (ADS)

    Wen, Z. D.; Song, K. S.; Zhao, Y.; Du, J.; Ma, J. H.

    2015-06-01

    Spectral characteristics of chromophoric dissolved organic matter (CDOM) were examined in conjunction with environmental factors in the waters of 22 rivers and 26 terminal waters in Hulun Buir plateau, northeast China. Dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorous (TP) were significantly higher in terminal waters than rivers waters (p < 0.01). Principal component analysis (PCA) indicated that non-water light absorption and anthropogenic nutrient disturbances might be the causes of the diversity of water quality parameters in Hulun Buir plateau. CDOM absorption in river waters was significantly lower than terminal waters (p < 0.01). Analysis of ratio of absorption at 250-365 nm (E250 : 365), specific UV absorbance (SUVA254), and spectral slope ratio (Sr) indicated that CDOM in river waters had higher aromaticity, molecular weight, and vascular plant contribution than in terminal waters. Furthermore, results showed that DOC concentration, CDOM light absorption, and the proportion of autochthonous sources of CDOM in plateau waters were all higher than in other freshwater rivers reported in the literature. The strong evapoconcentration, intense ultraviolet irradiance and landscape features of Hulun Buir plateau may be responsible for the above phenomenon. Redundancy analysis (RDA) indicated that the environmental variables TSM, TN, and EC had a strong correlation with light absorption characteristics, followed by TDS and chlorophyll a. In most sampling locations, CDOM was the dominant non-water light-absorbing substance. Light absorption by non-algal particles often exceeded that by phytoplankton in the plateau waters. Study of these optical-physicochemical correlations is helpful in the evaluation of the potential influence of water quality factors on non-water light absorption in cold plateau water environments. And the study on organic carbon in plateau lakes had a vital contribution to global carbon balance estimation.

  4. Influence of environmental factors on spectral characteristics of chromophoric dissolved organic matter (CDOM) in Inner Mongolia Plateau, China

    NASA Astrophysics Data System (ADS)

    Wen, Z. D.; Song, K. S.; Zhao, Y.; Du, J.; Ma, J. H.

    2016-02-01

    Spectral characteristics of chromophoric dissolved organic matter (CDOM) were examined in conjunction with environmental factors in the waters of rivers and terminal lakes within the Hulun Buir plateau, northeast China. Dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorous (TP) were significantly higher in terminal lakes than rivers waters (p < 0.01). Principal component analysis (PCA) indicated that non-water light absorption and anthropogenic nutrient disturbances were the likely causes of the diversity of water quality parameters. CDOM absorption in river waters was significantly lower than terminal lakes. Analysis of the ratio of absorption at 250 to 365 nm (E250 : 365), specific ultraviolet (UV) absorbance (SUVA254), and the spectral slope ratio (Sr) indicated that CDOM in river waters had higher aromaticity, molecular weight, and vascular plant contribution than in terminal lakes. Furthermore, results showed that DOC concentration, CDOM light absorption, and the proportion of autochthonous sources of CDOM in plateau waters were all higher than in other freshwater rivers reported in the literature. The strong evapoconcentration, intense ultraviolet irradiance, and landscape features of the Hulun Buir plateau may be responsible for the above phenomenon. Redundancy analysis (RDA) indicated that the environmental variables total suspended matter (TSM), TN, and electrical conductivity (EC) had a strong correlation with light absorption characteristics, followed by total dissolved solid (TDS) and chlorophyll a. In most sampling locations, CDOM was the dominant non-water light-absorbing substance. Light absorption by non-algal particles often exceeded that by phytoplankton in the plateau waters. Study of these optical-physicochemical correlations is helpful in the evaluation of the potential influence of water quality factors on non-water light absorption in cold plateau water environments. The construction of a correlation between DOC

  5. Experimental investigation of X-ray spectral absorption coefficients in heated Al and Ge on the Iskra-5 laser facility

    SciTech Connect

    Bondarenko, S V; Garanin, Sergey G; Zhidkov, N V; Pinegin, A V; Suslov, N A

    2012-01-31

    We set forth the data of experimental investigation of X-ray spectral absorption coefficients in the 1.1 - 1.6 keV photon energy range for Al and Ge specimens bulk heated by soft X-ray radiation. Two experimental techniques are described: with the use of one facility channel and the heating of specimens by the X-ray radiation from a plane burnthrough target, as well as with the use of four channels and the heating by the radiation from two cylindrical targets with internal input of laser radiation. The X-ray radiation absorption coefficients were studied by way of transmission absorption spectroscopy using backlighting X-ray radiation from a point source. The results of investigation of X-ray spectral absorption coefficients on the 1s - 2p transitions in Al atoms and the 2p - 3d transitions in Ge atoms are presented.

  6. Temperature dependence of aggregated structure of β-carotene by absorption spectral experiment and simulation

    NASA Astrophysics Data System (ADS)

    Lu, Liping; Wu, Jie; Wei, Liangshu; Wu, Fang

    2016-12-01

    β-carotene can self-assemble to form J- or H-type aggregate in hydrophilic environments, which is crucial for the proper functioning of biological system. Although several ways controlling the formation of the two types of aggregate in hydrated ethanol have been investigated in recent years, our study provided another way to control whether J- or H- β-carotene was formed and presented a method to investigate the aggregated structure. For this purpose, the aggregates of β-carotene formed at different temperatures were studied by UV-Vis spectra and a computational method based on Frenkel exciton was applied to simulate the absorption spectra to obtain the aggregated structure of the β-carotene. The analysis showed that β-carotene formed weakly coupled H-aggregate at 15 °C in 1:1 ethanol-water solvent, and with the increase of temperature it tended to form J-type of aggregate. The absorption spectral simulation based on one-dimensional Frenkel exciton model revealed that good fit with the experiment was obtained with distance between neighbor molecules r = 0.82 nm, disorder of the system D = 1500 cm- 1 for H-type and r = 1.04 nm, D = 1800 cm- 1 for J-type.

  7. Spectral Characteristics of a 140-GHz Long-Pulsed Gyrotron

    PubMed Central

    Han, Seong-Tae; Griffin, Robert G.; Hu, Kan-Nian; Joo, Chan-Gyu; Joye, Colin D.; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Torrezan, Antonio C.; Woskov, Paul P.

    2008-01-01

    Gyrotrons operating in the millimeter and submillimeter wavelength ranges are the promising sources for applications that are requiring good spectral characteristics and a wide range of output power. We report the precise measurement results of gyrotron spectra. Experiments were conducted using a 140-GHz long-pulse gyrotron that is developed for the dynamic nuclear polarization/nuclear-magnetic-resonance spectroscopy at the Massachusetts Institute of Technology. Transient downshift of the frequency by 12 MHz with a time constant of 3 s was observed. After reaching equilibrium, the frequency was maintained within 1 ppm for over 20 s. The coefficient of the frequency change with cavity temperature was −2.0 MHz/K, which shows that fine tuning of the gyrotron frequency is plausible by cavity-temperature control. Frequency pulling by the beam current was observed, but it was shown to be masked by the downward shift of the gyrotron frequency with temperature. The linewidth was measured to be much less than 1 MHz at 60 dB relative to the carrier power [in decibels relative to carrier (dBc)] and 4.3 MHz at 75 dBc, which is the largest dynamic range to date for the measurement of gyrotron linewidth to our knowledge. PMID:19081779

  8. Towards photodetection with high efficiency and tunable spectral selectivity: graphene plasmonics for light trapping and absorption engineering

    NASA Astrophysics Data System (ADS)

    Zhang, Jianfa; Zhu, Zhihong; Liu, Wei; Yuan, Xiaodong; Qin, Shiqiao

    2015-08-01

    Plasmonics can be used to improve absorption in optoelectronic devices and has been intensively studied for solar cells and photodetectors. Graphene has recently emerged as a powerful plasmonic material. It shows significantly less loss compared to traditional plasmonic materials such as gold and silver and its plasmons can be tuned by changing the Fermi energy with chemical or electrical doping. Here we propose the use of graphene plasmonics for light trapping in optoelectronic devices and show that the excitation of localized plasmons in doped, nanostructured graphene can enhance optical absorption in its surrounding medium including both bulky and two-dimensional materials by tens of times, which may lead to a new generation of photodetectors with high efficiency and tunable spectral selectivity in the mid-infrared and THz ranges.Plasmonics can be used to improve absorption in optoelectronic devices and has been intensively studied for solar cells and photodetectors. Graphene has recently emerged as a powerful plasmonic material. It shows significantly less loss compared to traditional plasmonic materials such as gold and silver and its plasmons can be tuned by changing the Fermi energy with chemical or electrical doping. Here we propose the use of graphene plasmonics for light trapping in optoelectronic devices and show that the excitation of localized plasmons in doped, nanostructured graphene can enhance optical absorption in its surrounding medium including both bulky and two-dimensional materials by tens of times, which may lead to a new generation of photodetectors with high efficiency and tunable spectral selectivity in the mid-infrared and THz ranges. Electronic supplementary information (ESI) available: Spectral tuning of absorption by changing the diameter of graphene nanodisks. Perfect light absorption in the whole structure and further enhancement of absorption in the underlying absorptive layer with a back mirror. Light trapping and enhancement of

  9. Spectral absorption properties of colored dissolved organic matter (CDOM) and total suspended matter (TSM) of inland waters

    NASA Astrophysics Data System (ADS)

    Song, Kaishan; Liu, Dianwei; Li, Lin; Wang, Zongming; Wang, Yuandong; Jiang, Guangjia

    2010-08-01

    Spectral absorption properties of total suspended matter (TSM) and colored dissolved organic matter (CDOM) are important for the use of the bio-optical model to estimate water quality parameters. This study aims to investigate the variation in the absorption coefficients of TSM and CDOM of inland waters. A total of 92 water samples were collected from Shitoukoumen Reservoir and Songhua Lake in Northeast China, analyzed for TSM and Chl-a, and measured for the absorption coefficient of TSM, CDOM and total pigments using a laboratory spectrophotometer. The absorption coefficient of TSM has been decomposed for phytoplankton and inorganic sediments. The results show that for Shitoukoumen Reservoir, CDOM has strong absorptions with shallow absorption slopes (i.e., the coefficient S in a(λ)=a(λ0)exp[-S(λ- λ0)]) and large absorption at 355 nm; and for Songhua Lake, CDOM follows similar spectral absorption curves but less variation in the S value. The results also show TSM has the average absorption coefficient 5.7 m-1 at 440 nm and 0.93 m-1 at 675 nm, and their concentration is well correlated to TSM with R2 larger than 0.85 at 440 nm over both Songhu Lake and Shitoukoumen Reservoir. In summer, CDOM was mainly terrigenous and had a high proportion of humic acid derived from the decomposition of phytoplankton and there were no obvious difference of S value. The results indicate that inorganic sediments contributed much more absorption than phytoplankton pigments in Shitoukoumen Reservoir than that in Songhua Lake, and there is strong association of TSM concentration to absorption coefficient at 440 nm.

  10. Characteristics of active spectral sensor for plant sensing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant stress has been estimated by spectral signature using both passive and active sensors. As optical sensors measure reflected light from a target, changes in illumination conditions critically affect sensor response. Active spectral sensors minimize the illumination effects by producing their ...

  11. Spectral reflectance characteristics of different snow and snow-covered land surface objects and mixed spectrum fitting

    USGS Publications Warehouse

    Zhang, J.-H.; Zhou, Z.-M.; Wang, P.-J.; Yao, F.-M.; Yang, L.

    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 1030 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 300~1300, 1700~1800 and 2200~2300 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 350~1300 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=0.9509).

  12. [Gastric cancer detection using kubelka-Munk spectral function of DNA and protein absorption bands].

    PubMed

    Li, Lan-quan; Wei, Hua-jiang; Guo, Zhou-yi; Yang, Hong-qin; Xie, Shu-sen; Chen, Xue-mei; Li, Li-bo; He, Bol-hua; Wu, Guo-yong; Lu, Jian-jun

    2009-09-01

    Differential diagnosis for epithelial tissues of normal human gastric, undifferentiation gastric adenocarcinoma, gastric squamous cell carcinomas, and poorly differentiated gastric adenocarcinoma were studied using the Kubelka-Munk spectral function of the DNA and protein absorption bands at 260 and 280 nm in vitro. Diffuse reflectance spectra of tissue were measured using a spectrophotometer with an integrating sphere attachment. The results of measurement showed that for the spectral range from 250 to 650 nm, pathological changes of gastric epithelial tissues induced that there were significant differences in the averaged value of the Kubelka-Munk function f(r infinity) and logarithmic Kubelka-Munk function log[f(r infinity)] of the DNA absorption bands at 260 nm between epithelial tissues of normal human stomach and human undifferentiation gastric cancer, between epithelial tissues of normal human stomach and human gastric squamous cell carcinomas, and between epithelial tissues of normal human stomach and human poorly differentiated cancer. Their differences were 68.5% (p < 0.05), 146.5% (p < 0.05), 282.4% (p < 0.05), 32.4% (p < 0.05), 56.00 (p < 0.05) and 83.0% (p < 0.05) respectively. And pathological changes of gastric epithelial tissues induced that there were significant differences in the averaged value of the Kubelka-Munk function f(r infinity) and logarithmic Kubelka-Munk function log[f(r infinity)] of the protein absorption bands at 280 nm between epithelial tissues of normal human stomach and human undifferentiation gastric cancer, between epithelial tissues of normal human stomach and human gastric squamous cell carcinomas, and between epithelial tissues of normal human stomach and human poorly differentiated cancer. Their differences were 86.8% (p < 0.05), 262.9% (p < 0.05), 660.1% (p < 0.05) and 34% (p < 0.05), 72. 2% (p < 0.05), 113.5% (p < 0.05) respectively. And pathological changes of gastric epithelial tissues induced that there were

  13. A high spectral resolution VLA search for H I absorption towards A496, A1795, and A2584

    NASA Technical Reports Server (NTRS)

    O'Dea, Christopher P.; Gallimore, Jack F.; Baum, Stefi A.

    1995-01-01

    In this paper, we present the results of a Very Large Array (VLA) search for H I absorption with high spectral resolution (1.6 km/s) towards A496, A1795, A2584, and A2597. These observations are well matched to the properties of cold, optically thick H I clouds, where the line width is given by the width of an individual cloud rather than the dispersion in an ensemble of clouds. We do not detect any H I absorption with narrow linewidths in these clusters. Our limits mainly apply to clouds which are larger than a few tenths parsec-i.e., if the clouds are much smaller than the background radio source and have a low covering factor in velocity space, they could still escape detection. The estimated limits on column density (for clouds in this regime of parameter space) are 2-3 orders of magnitude less than the 10(exp 21)/sq cm required to explain the x-ray absorption seen in some cooling flow clusters. The combination of our high spectral resolution H I absorption searches with the existing lower spectral resolution H I absorption searches and the searches for H I emission makes it unlikely that atomic hydrogen is the dominant component of the cold x-ray absorbing gas in the inter-cloud medium (ICM).

  14. Spectral fluorescence and polarization characteristics of Z,Z-bilirubin IXα

    NASA Astrophysics Data System (ADS)

    Plavskii, V. Yu.; Mostovnikov, V. A.; Mostovnikova, G. R.; Tret'yakova, A. I.

    2007-01-01

    We have studied the spectral fluorescence and polarization characteristics of Z,Z-bilirubin IXα, at room temperature in chloroform and in aqueous buffer medium, within an equilibrium complex with human serum albumin (HSA), and also under low temperature conditions (T = -100°C) in isobutyl alcohol. We have observed a bathochromic shift of the fluorescence spectra, which is most pronounced for the bilirubin-albumin complex. The following are considered as possible reasons for the observed dependence of the position of the fluorescence (fluorescence excitation) spectra on the excitation (detection) wavelength: structural and spectral differences between the chromophores making up the bilirubin molecule; conformational heterogeneity of the pigment in solution; a contribution to the fluorescence from molecules which have not completed the vibrational relaxation process; inhomogeneous orientational broadening of the levels; heterogeneity of the microenvironment of the chromophores in the protein matrix. We show that polarized fluorescence of bilirubin occurs at room temperature, due to the anomalously short fluorescence lifetime τ (picosecond or subpicosecond ranges). Despite such a short τ, the absorption and emission polarization spectra suggest the presence of intramolecular nonradiative singlet-singlet energy transfer when bilirubin is excited to high vibrational sublevels of the S1 state (degree of polarization p = 0.11-0.12). When fluorescence is excited on the long-wavelength slope of the absorption band, no transfer occurs: the degree of polarization (p = 0.46-0.47) is close to the limiting value (p = 0.50). We discuss the question of the role played by exciton interactions between chromophores in the bilirubin molecule when it is excited.

  15. Spectrally Consistent Scattering, Absorption, and Polarization Properties of Atmospheric Ice Crystals at Wavelengths from 0.2 to 100 um

    NASA Technical Reports Server (NTRS)

    Yang, Ping; Bi, Lei; Baum, Bryan A.; Liou, Kuo-Nan; Kattawar, George W.; Mishchenko, Michael I.; Cole, Benjamin

    2013-01-01

    A data library is developed containing the scattering, absorption, and polarization properties of ice particles in the spectral range from 0.2 to 100 microns. The properties are computed based on a combination of the Amsterdam discrete dipole approximation (ADDA), the T-matrix method, and the improved geometric optics method (IGOM). The electromagnetic edge effect is incorporated into the extinction and absorption efficiencies computed from the IGOM. A full set of single-scattering properties is provided by considering three-dimensional random orientations for 11 ice crystal habits: droxtals, prolate spheroids, oblate spheroids, solid and hollow columns, compact aggregates composed of eight solid columns, hexagonal plates, small spatial aggregates composed of 5 plates, large spatial aggregates composed of 10 plates, and solid and hollow bullet rosettes. The maximum dimension of each habit ranges from 2 to 10,000 microns in 189 discrete sizes. For each ice crystal habit, three surface roughness conditions (i.e., smooth, moderately roughened, and severely roughened) are considered to account for the surface texture of large particles in the IGOM applicable domain. The data library contains the extinction efficiency, single-scattering albedo, asymmetry parameter, six independent nonzero elements of the phase matrix (P11, P12, P22, P33, P43, and P44), particle projected area, and particle volume to provide the basic single-scattering properties for remote sensing applications and radiative transfer simulations involving ice clouds. Furthermore, a comparison of satellite observations and theoretical simulations for the polarization characteristics of ice clouds demonstrates that ice cloud optical models assuming severely roughened ice crystals significantly outperform their counterparts assuming smooth ice crystals.

  16. Measurement of the Spectral Absorption of Liquid Water in Melting Snow With an Imaging Spectrometer

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Dozier, Jeff

    1995-01-01

    Melting of the snowpack is a critical parameter that drives aspects of the hydrology in regions of the Earth where snow accumulates seasonally. New techniques for measurement of snow melt over regional scales offer the potential to improve monitoring and modeling of snow-driven hydrological processes. In this paper we present the results of measuring the spectral absorption of liquid water in a melting snowpack with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). AVIRIS data were acquired over Mammoth Mountain, in east central California on 21 May 1994 at 18:35 UTC. The air temperature at 2926 m on Mammoth Mountain at site A was measured at 15-minute intervals during the day preceding the AVIRIS data acquisition. At this elevation. the air temperature did not drop below freezing the night of the May 20 and had risen to 6 degrees Celsius by the time of the overflight on May 21. These temperature conditions support the presence of melting snow at the surface as the AVIRIS data were acquired.

  17. Measurement of the spectral absorption of liquid water in melting snow with an imaging spectrometer

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Dozier, Jeff

    1995-01-01

    Melting of the snowpack is a critical parameter that drives aspects of the hydrology in regions of the earth where snow accumulates seasonally. New techniques for measurement of snow melt over regional scales offer the potential to improve monitoring and modeling of snow-driven hydrological processes. We present the results of measuring the spectral absorption of liquid water in a melting snowpack with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). AVIRIS data were acquired over Mammoth Mountain, in east central California on 21 May 1994 at 18:35 UTC. The air temperature at 2926 m on Mammoth Mountain at site A was measured at 15-minute intervals during the day preceding the AVIRIS data acquisition. At this elevation, the air temperature did not drop below freezing the night of May 20 and had risen to 6 degrees Celsius by the time of the overflight on May 21. These temperature conditions support the presence of melting snow at the surface as the AVIRIS data were acquired.

  18. Level-crossing absorption with narrow spectral width in Rb vapor with buffer gas

    SciTech Connect

    Yu, Ye Jin; Lee, Hyun Jun; Bae, In-Ho; Moon, Han Seb; Noh, Heung-Ryoul

    2010-02-15

    We present the transformation in the Hanle configuration of the transmission that results from coherent population trapping (CPT) into the level-crossing absorption (LCA) that results from the single-photon optical pumping in the {sup 87}Rb D{sub 1} line of a Rb vapor cell with a Ne buffer gas when the polarization of the laser field is changed from linear to circular. The LCA spectrum, with a narrow spectral width of 2.4 mG (1.7 kHz), was observed in the F{sub g{yields}}F{sub e{<=}}F{sub g} transition with the circularly polarized laser. This may be because the LCA is both related to the transverse magnetic field and the atom-laser interaction time resulting from diffusive atomic motion in the cell with the buffer gas. The CPT and LCA spectra were calculated numerically using the full density matrix equations for the relevant magnetic sublevels of the hyperfine levels, considering the residual magnetic fields perpendicular to laser propagation and the collision effects resulting from the buffer gas. There was good qualitative agreement between theoretical and experimental results.

  19. Recovery of x-ray absorption spectral profile in etched TiO{sub 2} thin films

    SciTech Connect

    Sano, Keiji; Niibe, Masahito; Kawakami, Retsuo; Nakano, Yoshitaka

    2015-05-15

    Near edge x-ray absorption fine structure (NEXAFS) spectra of plasma-etched TiO{sub 2} thin films were observed using the total fluorescence yield method involving visible emission. The disrupted spectrum recovered its as-grown (nonetched) profile, upon soft x-ray (SX) irradiation. This recovery was investigated by ultraviolet (UV) irradiation, spatial distribution measurements, exposing recovered samples to air, and NEXAFS measurements of ultrafine TiO{sub 2} particles. The spectral profile recovered upon UV irradiation, and at sample positions outside of the SX irradiation site. The recovered spectral profiles were disrupted again, upon exposure to air. Nonetched ultrafine TiO{sub 2} particles also exhibited a disrupted spectral profile, which was recovered upon SX irradiation. The spectral recovery is explained by a model involving electrons trapped in oxygen vacancies generated by etching.

  20. Revealing spectral features in two-photon absorption spectrum of Hoechst 33342: a combined experimental and quantum-chemical study.

    PubMed

    Olesiak-Banska, Joanna; Matczyszyn, Katarzyna; Zaleśny, Robert; Murugan, N Arul; Kongsted, Jacob; Ågren, Hans; Bartkowiak, Wojciech; Samoc, Marek

    2013-10-10

    We present the results of wide spectral range Z-scan measurements of the two-photon absorption (2PA) spectrum of the Hoechst 33342 dye. The strongest 2PA of the dye in aqueous solution is found at 575 nm, and the associated two-photon absorption cross section is 245 GM. A weak but clearly visible 2PA band at ∼850 nm is also observed, a feature that could not be anticipated from the one-photon absorption spectrum. On the basis of the results of hybrid quantum mechanics/molecular mechanics calculations, we put forward a notion that the long-wavelength feature observed in the two-photon absorption spectrum of Hoechst 33342 is due to the formation of dye aggregates.

  1. [Species Determination and Spectral Characteristics of Swelling Clay Minerals in the Pliocene Sandstones in Xinghai, Qinghai].

    PubMed

    Wang, Chao-wen; Chen, Jiang-jun; Fang, Qian; Yin, Ke; Hong, Han-lie

    2015-10-01

    X-ray diffraction (XRD) and Fourier infrared absorption spectroscopy (FTIR) were conducted to deepen our research on specific species and spectral characteristics of swelling clay minerals in the Pliocene sandstones in Xinghai, Qinghai province. XRD results show that swelling clay minerals are dominant clay minerals in the sandstones, which can be up to 97% in percentage. XRD patterns show 060 reflections of the samples occur both remarkably at 1.534 Å and 1.498 Å, indicating the samples contain physical mixtures of trioctahedral and dioctahedral swelling clay minerals, respectively. Further treatment of Li-300 degrees C heat and glycerol saturation shows the swelling clay minerals collapse to 9.3-9.9 Å with a partial expansion to -18 Å. This indicates the swelling clay minerals dominate montmorillonite and contain minor saponite. The montmorillonite shows no swelling after Li-300 degrees C heat and glycerol saturation because of Li+ inserting into the octahedral layers, which balances the layer charge caused by the substitution of Mg to Al. FTIR results show the samples are composed of a kind of phyllosilicate with absorbed and structural water, which is in agreement with the results of XRD. Absorbed peaks at 913, 842, 880 cm(-1), corresponding to OH associated with Al-Al, Al-Mg, and Al-Fe pairs, further indicates the minerals are dominant dioctahedron in structure. Meanwhile, absorbed peaks at 625 and 519 cm(-1), corresponding to coupled Si-O and Al-O-Si deformation, indicates parts of Si is replaced by Al in tetrahedron. The spectral characteristics of the samples are against the presence of beidellite and nontronite based on the results of XRD and FTIR, while demonstrating an,existence of montmorillonite. This study, to distinguish the specific species of swelling clay species in clay minerals, would be of great importance when using clay mineralogy to interpret provenance and climatic information.

  2. Absorption cross-sections of ozone in the ultraviolet and visible spectral regions: Status report 2015

    NASA Astrophysics Data System (ADS)

    Orphal, Johannes; Staehelin, Johannes; Tamminen, Johanna; Braathen, Geir; De Backer, Marie-Renée; Bais, Alkiviadis; Balis, Dimitris; Barbe, Alain; Bhartia, Pawan K.; Birk, Manfred; Burkholder, James B.; Chance, Kelly; von Clarmann, Thomas; Cox, Anthony; Degenstein, Doug; Evans, Robert; Flaud, Jean-Marie; Flittner, David; Godin-Beekmann, Sophie; Gorshelev, Viktor; Gratien, Aline; Hare, Edward; Janssen, Christof; Kyrölä, Erkki; McElroy, Thomas; McPeters, Richard; Pastel, Maud; Petersen, Michael; Petropavlovskikh, Irina; Picquet-Varrault, Benedicte; Pitts, Michael; Labow, Gordon; Rotger-Languereau, Maud; Leblanc, Thierry; Lerot, Christophe; Liu, Xiong; Moussay, Philippe; Redondas, Alberto; Van Roozendael, Michel; Sander, Stanley P.; Schneider, Matthias; Serdyuchenko, Anna; Veefkind, Pepijn; Viallon, Joële; Viatte, Camille; Wagner, Georg; Weber, Mark; Wielgosz, Robert I.; Zehner, Claus

    2016-09-01

    The activity "Absorption Cross-Sections of Ozone" (ACSO) started in 2008 as a joint initiative of the International Ozone Commission (IO3C), the World Meteorological Organization (WMO) and the IGACO ("Integrated Global Atmospheric Chemistry Observations") O3/UV subgroup to study, evaluate, and recommend the most suitable ozone absorption cross-section laboratory data to be used in atmospheric ozone measurements. The evaluation was basically restricted to ozone absorption cross-sections in the UV range with particular focus on the Huggins band. Up until now, the data of Bass and Paur published in 1985 (BP, 1985) are still officially recommended for such measurements. During the last decade it became obvious that BP (1985) cross-section data have deficits for use in advanced space-borne ozone measurements. At the same time, it was recognized that the origin of systematic differences in ground-based measurements of ozone required further investigation, in particular whether the BP (1985) cross-section data might contribute to these differences. In ACSO, different sets of laboratory ozone absorption cross-section data (including their dependence on temperature) of the group of Reims (France) (Brion et al., 1993, 1998, 1992, 1995, abbreviated as BDM, 1995) and those of Serdyuchenko et al. (2014), and Gorshelev et al. (2014), (abbreviated as SER, 2014) were examined for use in atmospheric ozone measurements in the Huggins band. In conclusion, ACSO recommends: The spectroscopic data of BP (1985) should no longer be used for retrieval of atmospheric ozone measurements. For retrieval of ground-based instruments of total ozone and ozone profile measurements by the Umkehr method performed by Brewer and Dobson instruments data of SER (2014) are recommended to be used. When SER (2014) is used, the difference between total ozone measurements of Brewer and Dobson instruments are very small and the difference between Dobson measurements at AD and CD wavelength pairs are diminished

  3. Characteristic of Absorption Heat Transfer using LiBr+LiI Solution

    NASA Astrophysics Data System (ADS)

    Tsujimori, Atsushi; Ozaki, Eiichi; Nakao, Kazushige

    LiBr-H20 absorption chiller is widely used in Japan, and many research have been made for absorption characteristic in terms of enhancing heat transfer. Another study have been performed for widening working range with higher crystallization limits, and it was reported that adding LiI salt to LiBr-H20 working fluid provide about 5 [mass%] higher crystallization limit under the condition of absorption pressure range. It is necessary to reveal absorption heat transfer performance to utilize this working fluid pair for absorption chiller. In this study absorption heat transfer characteristic was investigated for horizontal and vertical tube. As a result, it was found that heat transfer coefficient increased as mass flow rate of solution increased and mass concentration of solution decrease and that these characteristic were almost the same as LiBr solution, though this solution gave slightly less heat transfer coefficient than LiBr solution.

  4. Two cyanobacterial strains can be distinguished from each other and other eukaryotic algae by spectral absorption method.

    PubMed

    Lokuhewage, Asha U M; Fujino, T

    2011-01-01

    Spectral absorption method based on two step linear regression analyses (TSLR) was applied for detection of two strains of cyanobacterium, Microcystis (blue-green algae) from eukaryotic algae. Both blue-green algae, algae and dissolved organic carbon (DOC) were considered from freshwater bodies in Kanto region, Japan. The results show that blue-green species can be detected from other algal species using absorption spectra of water samples. In this study statistical analysis was done by TSLR method, which determined the gradient vectors of single algal species and DOC. We believe that this method might be useful in environmental monitoring of freshwater algae.

  5. The characteristic analysis of spectral image for cabbage leaves damaged by diamondback moth pests

    NASA Astrophysics Data System (ADS)

    Lin, Li-bo; Li, Hong-ning; Cao, Peng-fei; Qin, Feng; Yang, Shu-ming; Feng, Jie

    2015-02-01

    Cabbage growth and health diagnosis are important parts for cabbage fine planting, spectral imaging technology with the advantages of obtaining spectrum and space information of the target at the same time, which has become a research hotspot at home and abroad. The experiment measures the reflection spectrum at different stages using liquid crystal tunable filter (LCTF) and monochromatic CMOS camera composed of spectral imaging system for cabbage leaves damaged by diamondback moth pests, and analyzes its feature bands and the change of spectral parameters. The study shows that the feature bands of cabbage leaves damaged by diamondback moth pests have a tendency to blue light direction, the red edge towards blue shift, and red valley raising in spectral characteristic parameters, which have a good indication in diagnosing the extent of cabbage damaged by pests. Therefore, it has a unique advantage of monitoring the cabbage leaves damaged by diamondback moth pests by combinating feature bands and spectral characteristic parameters in spectral imaging technology.

  6. The continuum spectral characteristics of gamma ray bursts observed by BATSE

    NASA Technical Reports Server (NTRS)

    Pendleton, Geoffrey N.; Paciesas, William S.; Briggs, Michael S.; Mallozzi, Robert S.; Koshut, Tom M.; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.; Harmon, Alan B.; Kouveliotou, Chryssa

    1994-01-01

    Distributions of the continuum spectral characteristics of 260 bursts in the first Burst and Transient Source Experiment (BATSE) catalog are presented. The data are derived from flux ratios calculated from the BATSE Large Area Detector (LAD) four channel discriminator data. The data are converted from counts to photons using a direct spectral inversion technique to remove the effects of atmospheric scattering and the energy dependence of the detector angular response. Although there are intriguing clusterings of bursts in the spectral hardness ratio distributions, no evidence for the presence of distinct burst classes based on spectral hardness ratios alone is found. All subsets of bursts selected for their spectral characteristics in this analysis exhibit spatial distributions consistent with isotropy. The spectral diversity of the burst population appears to be caused largely by the highly variable nature of the burst production mechanisms themselves.

  7. The continuum spectral characteristics of gamma-ray bursts observed by BATSE

    NASA Technical Reports Server (NTRS)

    Pendleton, Geoffrey N.; Paciesas, William S.; Briggs, Michael S.; Mallozzi, Robert S.; Koshut, Tom M.; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.; Harmon, Alan B.; Kouveliotou, Chryssa

    1994-01-01

    Distributions of the continuum spectral characteristics of 260 bursts in the first Burst And Transient Source Experiement (BATSE) catalog are presented. The data are derived from flux calculated from BATSE Large Area Detector (LAD) four-channel discriminator data. The data are converted from counts to protons using a direct spectral inversion technique to remove the effects of atmospheric scattering and the energy dependence of the detector angular response. Although there are intriguing clusters of bursts in the spectral hardness ratio distributions, no evidence for the presence of distinct burst classes based in spectral hardness ratios alone is found. All subsets of bursts selected for their spectral characteristics in this analysis exhibit spatial distributions consistent with isotropy. The spectral diversity of the burst population appears to be caused largely by the highly variable nature of the burst production mechanisms themselves.

  8. CHaracteristics of Two-Stage Absorption Heat Pump Cycler Driven by Waste Heat From Gas Engine

    NASA Astrophysics Data System (ADS)

    Kojima, Hiroshi; Akisawa, Atsushi; Kashiwagi, Takao

    Recently the energy conservation is expected from the global environment protection view point. In this study, a new concept of a compound gas cooling system using treated sewage water combining a gas engine heat pump and an absorption heat pump is proposed. In this system, the absorption heat pump is driven by the waste heat from the gas engine. In this paper, first, the best absorption cycle for this absorption heat pump is selected for the cooling and heating mode. And finally the simulation model of the two-stage absorption heat pumps for heating mode is demonstrated and the static characteristics are clarified.

  9. Absorption spectral change of peripheral-light harvesting complexes 2 induced by magnesium protoporphyrin IX monomethyl ester association

    NASA Astrophysics Data System (ADS)

    Yue, Huiying; Zhao, Chungui; Li, Kai; Yang, Suping

    2015-02-01

    Several spectrally different types of peripheral light harvesting complexes (LH) have been reported in anoxygenic phototrophic bacteria in response to environmental changes. In this study, two spectral forms of LH2 (T-LH2 and U-LH2) were isolated from Rhodobacter azotoformans. The absorption of T-LH2 was extremely similar to the LH2 isolated from Rhodobacter sphaeroides. U-LH2 showed an extra peak at ∼423 nm in the carotenoid region. To explore the spectral origin of this absorption peak, the difference in pigment compositions of two LH2 was analyzed. Spheroidene and bacteriochlorophyll aP were both contained in the two LH2. And magnesium protoporphyrin IX monomethyl ester (MPE) was only contained in U-LH2. It is known that spheroidene and bacteriochlorophyll aP do not produce ∼423 nm absorption peak either in vivo or in vitro. Whether MPE accumulation was mainly responsible for the formation of the ∼423 nm peak? The interactions between MPE and different proteins were further studied. The results showed that the maximum absorption of MPE was red-shifted from ∼415 nm to ∼423 nm when it was mixed with T-LH2 and its apoproteins, nevertheless, the Qy transitions of the bound bacteriochlorophylls in LH2 were almost unaffected, which indicated that the formation of the ∼423 nm peak was related to MPE-LH2 protein interaction. MPE did not bind to sites involved in the spectral tuning of BChls, but the conformation of integral LH2 was affected by MPE association, the alkaline stability of U-LH2 was lower than T-LH2, and the fluorescence intensity at 860 nm was decreased after MPE combination.

  10. Endoplasmic motility spectral characteristics in plasmodium of Physarum polycephalum

    NASA Astrophysics Data System (ADS)

    Avsievich, T. I.; Ghaleb, K. E. S.; Frolov, S. V.; Proskurin, S. G.

    2015-03-01

    Spectral Fourier analysis of experimentally acquired velocity time dependencies, V(t), of shuttle endoplasmic motility in an isolated strand of plasmodium of slime mold Physarum Polycephalum has been realized. V(t) registration was performed in normal conditions and after the treatment by respiration inhibitors, which lead to a complete cessation of endoplasmic motion in the strand. Spectral analysis of the velocity time dependences of the endoplasm allows obtaining two distinct harmonic components in the spectra. Their ratio appeared to be constant in all cases, ν2/ν1=1.97±0.17. After the inhibitors are washed out respiratory system becomes normal, gradually restoring the activity of both harmonic oscillatory sources with time. Simulated velocity time dependences correspond to experimental data with good accuracy.

  11. Dual absorption spectral changes by light-triggered shuttling in bistable [2]rotaxanes with non-destructive readout.

    PubMed

    Zhan, Tian-Guang; Yun, Meng-Yan; Lin, Jia-Le; Yu, Xin-Yao; Zhang, Kang-Da

    2016-12-01

    Light-triggered photoisomerization of the azobenzene (AB) unit in bistable [2]rotaxanes can cause the shuttling of the macrocycle on the dumbbell, resulting in distinctive dual spectral variation characteristics: (1) the spectral change of the photochromic unit and (2) the variation of the charge-transfer band. By employing the CT bond region as an output signal, non-destructive readout of optical information could be achieved.

  12. Spectral characteristics of skin sympathetic nerve activity in heat-stressed humans.

    PubMed

    Cui, Jian; Sathishkumar, Mithra; Wilson, Thad E; Shibasaki, Manabu; Davis, Scott L; Crandall, Craig G

    2006-04-01

    Skin sympathetic nerve activity (SSNA) exhibits low- and high-frequency spectral components in normothermic subjects. However, spectral characteristics of SSNA in heat-stressed subjects are unknown. Because the main components of the integrated SSNA during heat stress (sudomotor/vasodilator activities) are different from those during normothermia and cooling (vasoconstrictor activity), we hypothesize that spectral characteristics of SSNA in heat-stressed subjects will be different from those in subjects subjected to normothermia or cooling. In 17 healthy subjects, SSNA, electrocardiogram, arterial blood pressure (via Finapres), respiratory activity, and skin blood flow were recorded during normothermia and heat stress. In 7 of the 17 subjects, these variables were also recorded during cooling. Spectral characteristics of integrated SSNA, R-R interval, beat-by-beat mean blood pressure, skin blood flow variability, and respiratory excursions were assessed. Heat stress and cooling significantly increased total SSNA. SSNA spectral power in the low-frequency (0.03-0.15 Hz), high-frequency (0.15-0.45 Hz), and very-high-frequency (0.45-2.5 Hz) regions was significantly elevated by heat stress and cooling. Interestingly, heat stress caused a greater relative increase of SSNA spectral power within the 0.45- to 2.5-Hz region than in the other spectral ranges; cooling did not show this effect. Differences in the SSNA spectral distribution between normothermia/cooling and heat stress may reflect different characteristics of central modulation of vasoconstrictor and sudomotor/vasodilator activities.

  13. Observation of the Optical and Spectral Characteristics of Ball Lightning

    NASA Astrophysics Data System (ADS)

    Cen, Jianyong; Yuan, Ping; Xue, Simin

    2014-01-01

    Ball lightning (BL) has been observed with two slitless spectrographs at a distance of 0.9 km. The BL is generated by a cloud-to-ground lightning strike. It moves horizontally during the luminous duration. The evolution of size, color, and light intensity is reported in detail. The spectral analysis indicates that the radiation from soil elements is present for the entire lifetime of the BL.

  14. Predicting leaf traits of herbaceous species from their spectral characteristics

    PubMed Central

    Roelofsen, Hans D; van Bodegom, Peter M; Kooistra, Lammert; Witte, Jan-Philip M

    2014-01-01

    Trait predictions from leaf spectral properties are mainly applied to tree species, while herbaceous systems received little attention in this topic. Whether similar trait–spectrum relations can be derived for herbaceous plants that differ strongly in growing strategy and environmental constraints is therefore unknown. We used partial least squares regression to relate key traits to leaf spectra (reflectance, transmittance, and absorbance) for 35 herbaceous species, sampled from a wide range of environmental conditions. Specific Leaf Area and nutrient-related traits (N and P content) were poorly predicted from any spectrum, although N prediction improved when expressed on a per area basis (mg/m2 leaf surface) instead of mass basis (mg/g dry matter). Leaf dry matter content was moderately to good correlated with spectra. We explain our results by the range of environmental constraints encountered by herbaceous species; both N and P limitations as well as a range of light and water availabilities occurred. This weakened the relation between the measured response traits and the leaf constituents that are truly responsible for leaf spectral behavior. Indeed, N predictions improve considering solely upper or under canopy species. Therefore, trait predictions in herbaceous systems should focus on traits relating to dry matter content and the true, underlying drivers of spectral properties. PMID:24683454

  15. Absorption characteristics of elemental mercury in mercury chloride solutions.

    PubMed

    Ma, Yongpeng; Xu, Haomiao; Qu, Zan; Yan, Naiqiang; Wang, Wenhua

    2014-11-01

    Elemental mercury (Hg(0)) in flue gases can be efficiently captured by mercury chloride (HgCl2) solution. However, the absorption behaviors and the influencing effects are still poorly understood. The mechanism of Hg(0) absorption by HgCl2 and the factors that control the removal were studied in this paper. It was found that when the mole ratio of Cl(-) to HgCl2 is 10:1, the Hg(0) removal efficiency is the highest. Among the main mercury chloride species, HgCl3(-) is the most efficient ion for Hg(0) removal in the HgCl2 absorption system when moderate concentrations of chloride ions exist. The Hg(0) absorption reactions in the aqueous phase were investigated computationally using Moller-Plesset perturbation theory. The calculated Gibbs free energies and energy barriers are in excellent agreement with the results obtained from experiments. In the presence of SO3(2-) and SO2, Hg(2+) reduction occurred and Hg(0) removal efficiency decreased. The reduced Hg(0) removal can be controlled through increased chloride concentration to some degree. Low pH value in HgCl2 solution enhanced the Hg(0) removal efficiency, and the effect was more significant in dilute HgCl2 solutions. The presence of SO4(2-) and NO3(-) did not affect Hg(0) removal by HgCl2.

  16. The Features of the Frequency-Modulation Method When Studying the Shapes of the Spectral Lines of Nonlinear Absorption

    NASA Astrophysics Data System (ADS)

    Golubiatnikov, G. Yu.; Belov, S. P.; Lapinov, A. V.

    2017-01-01

    We briefly consider the method of the frequency (phase) modulation and signal detection at the second harmonic of the modulation frequency for recording and analyzing the spectral-line shapes. The precision sub-Doppler spectrometer in the millimeter- and submillimeter-wave ranges, which operated in the regime of nonlinear saturation of the spectral transitions in a standing wave (the Lamb-dip method), was used during the measurements. The influence of the saturation degree on the value and shape of the recorded frequency-modulated signals in the quadrature channels during the synchronous detection is demonstrated. Variation in the relationships among the signals determined by dispersion and absorption was observed. The necessity of allowance for the influence of the group-velocity dispersion and coherent effects on the shape of the recorded spectral lines is experimentally shown.

  17. Spectral Signature of Column Solar Radiation Absorption During the Atmospheric Radiation Measurement Enhanced Shortwave Experiment (ARESE). Revision

    SciTech Connect

    O'Hirok, William; Gautier, Catherine; Ricchiazzi, Paul

    1999-11-01

    Spectral and broadband shortwave radiative flux data obtained from the Atmospheric Radiation Measurement Enhanced Shortwave Experiment (ARESE) are compared with 3-D radiative transfer computations for the cloud field of October 30, 1995. Because the absorption of broadband solar radiation in the cloudy atmosphere deduced from observations and modeled differ by 135 Wm{sup -2}, we performed a consistency analysis using spectral observations and the model to integrate for wavelengths between the spectral observations. To match spectral measurements, aerosols need a reduction in both single scattering albedo (from 0.938 to 0.82) and asymmetry factor (from 0.67 to 0.61), and cloud droplets require a three-fold increase in co-albedo. Even after modifying the model inputs and microphysics the difference in total broadband absorption is still of the order of 75Wm{sup -2}. Finally, an unexplained absorber centered around 1.06 {micro}m appears in the comparison that is much too large to be explained by dimers.

  18. Cr(CO)6 photochemistry: semi-classical study of UV absorption spectral intensities and dynamics of photodissociation.

    PubMed

    Crespo-Otero, Rachel; Barbatti, Mario

    2011-04-28

    The UV absorption spectrum of Cr(CO)(6) (chromium hexacarbonyl) in gas phase is investigated by theoretical methods with focus on the absorption intensities. It is shown that in spite of good predictions for the excitation energies, the most frequently employed methods for excited-state calculations produce poor predictions for oscillator strengths and absorption cross sections. In particular, time-dependent DFT predicts relative intensities for the two main spectral bands to be up to five times larger than the experimental results depending on the functional. The best results are obtained by a multireference configuration interaction method based on DFT (DFT/MRCI). Spectral shoulders caused by vibronic-coupling absorption are assigned based on symmetry-restricted spectrum simulations. The dynamics of Cr(CO)(6) photodissociation was also considered at TDDFT/B3LYP level. The estimated time constants for the Cr(CO)(6) relaxation and dissociation are in excellent agreement with experimental values. The time constant for internal conversion, however, is longer than the experimentally observed by factor 2, presumably due to an underestimation of the experimental analysis.

  19. Satellite monitoring of different vegetation types by differential optical absorption spectroscopy (DOAS) in the red spectral range

    NASA Astrophysics Data System (ADS)

    Wagner, T.; Beirle, S.; Deutschmann, T.; Grzegorski, M.; Platt, U.

    2007-01-01

    A new method for the satellite remote sensing of different types of vegetation and ocean colour is presented. In contrast to existing algorithms relying on the strong change of the reflectivity in the red and near infrared spectral region, our method analyses weak narrow-band (few nm) reflectance structures (i.e. "fingerprint" structures) of vegetation in the red spectral range. It is based on differential optical absorption spectroscopy (DOAS), which is usually applied for the analysis of atmospheric trace gas absorptions. Since the spectra of atmospheric absorption and vegetation reflectance are simultaneously included in the analysis, the effects of atmospheric absorptions are automatically corrected (in contrast to other algorithms). The inclusion of the vegetation spectra also significantly improves the results of the trace gas retrieval. The global maps of the results illustrate the seasonal cycles of different vegetation types. In addition to the vegetation distribution on land, they also show patterns of biological activity in the oceans. Our results indicate that improved sets of vegetation spectra might lead to more accurate and more specific identification of vegetation type in the future.

  20. Study on three-dimensional fluorescent spectral characteristics of fluoroquinolones in varying media

    NASA Astrophysics Data System (ADS)

    Liu, Zhihong; Huang, Zuyun; Cai, Ruxiu

    2000-08-01

    Behaviors of fluoroquinolones in varying media were observed by employing their intrinsic fluorescence. Spectral characteristics in reversed micelles (Aerosol OT/ n-octane) were compared with those in aqueous solution and micelles (sodium dodecyl sulfonate). Those differences in interactions between fluoroquinolones and the various media were clearly illustrated by three-dimensional fluorescent spectra. The influences of other environmental factors on spectral characteristics (pH, SDS concentration, etc.) were also investigated.

  1. Mapping vegetation types with the multiple spectral feature mapping algorithm in both emission and absorption

    NASA Technical Reports Server (NTRS)

    Clark, Roger N.; Swayze, Gregg A.; Koch, Christopher; Ager, Cathy

    1992-01-01

    Vegetation covers a large portion of the Earth's land surface. Remotely sensing quantitative information from vegetation has proven difficult because in a broad sense, all vegetation is similar from a chemical viewpoint, and most healthy plants are green. Plant species are generally characterized by the leaf and flower or fruit morphology, not by remote sensing spectral signatures. But to the human eye, many plants show varying shades of green, so there is direct evidence for spectral differences between plant types. Quantifying these changes in a predictable manner has not been easy. The Clark spectral features mapping algorithm was applied to mapping spectral features in vegetation species.

  2. Effects of Mg 2+on spectral characteristics and photosynthetic functions of spinach photosystem II

    NASA Astrophysics Data System (ADS)

    Liang, Chen; Xiao, Wu; Hao, Huang; Xiaoqing, Liu; Chao, Liu; Lei, Zheng; Fashui, Hong

    2009-03-01

    In the present paper we report the results obtained with the photosystem II (PSII) isolated from spinach treated by MgCl 2, and studied the effect of Mg 2+ on spectral characteristics and photosynthetic functions of PSII. The results showed that Mg 2+ treatment at a suitable concentration could significantly increase the absorption intensity of PSII and the intensity ratio of Soret band to Q band of chlorophyll-a. The treatment also elevated the excited peak intensity at 230, 278 and 343 nm, and the emitted peak intensity at 304 and 682 nm, and the ratio of F278/ F230, respectively. The results implied that Mg 2+ increased absorbance for visible light, improving energy transfer among amino acids within PSII protein complex and accelerating energy transport from tyrosine residue to chlorophyll-a. The photochemical activity and oxygen evolving rate of PSII were also enhanced by Mg 2+. This is viewed as evidence that Mg 2+ can promote energy transfer and oxygen evolution in PSII of spinach.

  3. Effects of Mg(2+)on spectral characteristics and photosynthetic functions of spinach photosystem II.

    PubMed

    Liang, Chen; Xiao, Wu; Hao, Huang; Xiaoqing, Liu; Chao, Liu; Lei, Zheng; Fashui, Hong

    2009-03-01

    In the present paper we report the results obtained with the photosystem II (PSII) isolated from spinach treated by MgCl(2), and studied the effect of Mg(2+) on spectral characteristics and photosynthetic functions of PSII. The results showed that Mg(2+) treatment at a suitable concentration could significantly increase the absorption intensity of PSII and the intensity ratio of Soret band to Q band of chlorophyll-a. The treatment also elevated the excited peak intensity at 230, 278 and 343 nm, and the emitted peak intensity at 304 and 682 nm, and the ratio of F(278)/F(230), respectively. The results implied that Mg(2+) increased absorbance for visible light, improving energy transfer among amino acids within PSII protein complex and accelerating energy transport from tyrosine residue to chlorophyll-a. The photochemical activity and oxygen evolving rate of PSII were also enhanced by Mg(2+). This is viewed as evidence that Mg(2+) can promote energy transfer and oxygen evolution in PSII of spinach.

  4. Microwave Absorption Characteristics of Conventionally Heated Nonstoichiometric Ferrous Oxide

    NASA Astrophysics Data System (ADS)

    Peng, Zhiwei; Hwang, Jiann-Yang; Mouris, Joe; Hutcheon, Ron; Sun, Xiang

    2011-08-01

    The temperature dependence of the microwave absorption of conventionally heated nonstoichiometric ferrous oxide (Fe0.925O) was characterized via the cavity perturbation technique between 294 K and 1373 K (21 °C and 1100 °C). The complex relative permittivity and permeability of the heated Fe0.925O sample slightly change with temperature from 294 K to 473 K (21 °C to 200 °C). The dramatic variations of permittivity and permeability of the sample from 473 K to 823 K (200 °C to 550 °C) are partially attributed to the formation of magnetite (Fe3O4) and metal iron (Fe) from the thermal decomposition of Fe0.925O, as confirmed by the high-temperature X-ray diffraction (HT-XRD). At higher temperatures up to 1373 K (1100 °C), it is found that Fe0.925O regenerates and remains as a stable phase with high permittivity. Since the permittivity dominates the microwave absorption of Fe0.925O above 823 K (550 °C), resulting in shallow microwave penetration depth (~0.11 and ~0.015 m at 915 and 2450 MHz, respectively), the regenerated nonstoichiometric ferrous oxide exhibits useful microwave absorption capability in the temperature range of 823 K to1373 K (550 °C to 1100 °C).

  5. Characteristics of Single/Double-Effect Combination Absorption Refrigerator

    NASA Astrophysics Data System (ADS)

    Kimijima, Shinji; Waragai, Shisei; Uekusa, Tsuneo; Nakao, Masaki; Kawai, Sunao

    In recent years, co-generation system with fuel cell occupies the attention of the world from a standpoint of the environmental protection and the effective utilization of the energy. Since the waste heat of phosphoric acid fuel cell is recovered in two forms of steam (0.6 [MPa]) and hot water (65∼90 [°C]), this type of absorption refrigerator is driven by two heat sources. In this paper, we inquire the result of the experiment intented for this absorption refrigerator the standard cooling capacity of which is 35[kW]. It is recognized that there is a mutual intervention when the supply condition of steam pressure is changed. Also the effects of hot water temperature, cooling water temperature and chilled water temperature for the performance of this absorption refrigerator is clarified. As a result, the effectiveness of using steam and hot water simultaneously in year-round operation is shown. Furthermore, it is clarified that the utilization of the low boiling temperature medium as the heat transfer medium for air-conditioner is effective.

  6. Temporal and spectral characteristics of terrestrial gamma flashes

    NASA Astrophysics Data System (ADS)

    Nemiroff, Robert J.; Bonnell, Jerry T.; Norris, Jay P.

    1997-05-01

    We have analyzed the Burst and Transient Source Experiment (BATSE) high-resolution timing data for 13 terrestrial gamma flashes (TGFs) to better characterize this newly identified phenomenon, which may be related to atmospheric lightning. We find that the minimum timescale for TGF variability is ~25-250μs, with 50 μs near typical. In general, TGFs are spectrally much harder than cosmic gamma ray bursts (GRBs). We additionally find that as with GRBs, individual pulses within a TGF tend to peak earlier at higher energies. This time-asymmetry rules out models such as sweeping beams. We also find that different pulses can have different spectra, with spectra typically softening as a pulse progresses. Event-averaged spectra for the TGFs were examined and found to be better fit in the 25-500 keV range by a power law than by a blackbody model. However, in general, even a power law is not a perfect fit. We find correlation between minimum TGF timescale and the power law spectral index, with rapidly varying TGFs appearing softer. From empirical comparisons of timescales and structures we speculate that if TGFs are somehow related to known high-atmospheric lightning events, then they are more probably related to red sprites than to blue jets or transionospheric pulse pairs.

  7. Spectral Fingerprinting of Individual Cells Visualized by Cavity-Reflection-Enhanced Light-Absorption Microscopy

    PubMed Central

    Arai, Yoshiyuki; Yamamoto, Takayuki; Minamikawa, Takeo; Takamatsu, Tetsuro; Nagai, Takeharu

    2015-01-01

    The absorption spectrum of light is known to be a “molecular fingerprint” that enables analysis of the molecular type and its amount. It would be useful to measure the absorption spectrum in single cell in order to investigate the cellular status. However, cells are too thin for their absorption spectrum to be measured. In this study, we developed an optical-cavity-enhanced absorption spectroscopic microscopy method for two-dimensional absorption imaging. The light absorption is enhanced by an optical cavity system, which allows the detection of the absorption spectrum with samples having an optical path length as small as 10 μm, at a subcellular spatial resolution. Principal component analysis of various types of cultured mammalian cells indicates absorption-based cellular diversity. Interestingly, this diversity is observed among not only different species but also identical cell types. Furthermore, this microscopy technique allows us to observe frozen sections of tissue samples without any staining and is capable of label-free biopsy. Thus, our microscopy method opens the door for imaging the absorption spectra of biological samples and thereby detecting the individuality of cells. PMID:25950513

  8. Spectral fingerprinting of individual cells visualized by cavity-reflection-enhanced light-absorption microscopy.

    PubMed

    Arai, Yoshiyuki; Yamamoto, Takayuki; Minamikawa, Takeo; Takamatsu, Tetsuro; Nagai, Takeharu

    2015-01-01

    The absorption spectrum of light is known to be a "molecular fingerprint" that enables analysis of the molecular type and its amount. It would be useful to measure the absorption spectrum in single cell in order to investigate the cellular status. However, cells are too thin for their absorption spectrum to be measured. In this study, we developed an optical-cavity-enhanced absorption spectroscopic microscopy method for two-dimensional absorption imaging. The light absorption is enhanced by an optical cavity system, which allows the detection of the absorption spectrum with samples having an optical path length as small as 10 μm, at a subcellular spatial resolution. Principal component analysis of various types of cultured mammalian cells indicates absorption-based cellular diversity. Interestingly, this diversity is observed among not only different species but also identical cell types. Furthermore, this microscopy technique allows us to observe frozen sections of tissue samples without any staining and is capable of label-free biopsy. Thus, our microscopy method opens the door for imaging the absorption spectra of biological samples and thereby detecting the individuality of cells.

  9. [Influence of human body target's spectral characteristics on visual range of low light level image intensifiers].

    PubMed

    Zhang, Jun-Ju; Yang, Wen-Bin; Xu, Hui; Liu, Lei; Tao, Yuan-Yaun

    2013-11-01

    To study the effect of different human target's spectral reflective characteristic on low light level (LLL) image intensifier's distance, based on the spectral characteristics of the night-sky radiation and the spectral reflective coefficients of common clothes, we established a equation of human body target's spectral reflective distribution, and analyzed the spectral reflective characteristics of different human targets wearing the clothes of different color and different material, and from the actual detection equation of LLL image intensifier distance, discussed the detection capability of LLL image intensifier for different human target. The study shows that the effect of different human target's spectral reflective characteristic on LLL image intensifier distance is mainly reflected in the average reflectivity rho(-) and the initial contrast of the target and the background C0. Reflective coefficient and spectral reflection intensity of cotton clothes are higher than polyester clothes, and detection capability of LLL image intensifier is stronger for the human target wearing cotton clothes. Experimental results show that the LLL image intensifiers have longer visual ranges for targets who wear cotton clothes than targets who wear same color but polyester clothes, and have longer visual ranges for targets who wear light-colored clothes than targets who wear dark-colored clothes. And in the full moon illumination conditions, LLL image intensifiers are more sensitive to the clothes' material.

  10. Binding characteristics of salbutamol with DNA by spectral methods.

    PubMed

    Bi, Shuyun; Pang, Bo; Zhao, Tingting; Wang, Tianjiao; Wang, Yu; Yan, Lili

    2013-07-01

    Salbutamol interacting with deoxyribonucleic acid (DNA) was examined by fluorescence, UV absorption, viscosity measurements, and DNA melting techniques. The binding constants and binding sites were obtained at different temperatures by fluorescence quenching. The Stern-Volmer plots showed that the quenching of fluorescence of salbutamol by DNA was a static quenching. To probe the binding mode, various analytical methods were performed and the results were as follows: hyperchromic effect was shown in the absorption spectra of salbutamol upon addition of DNA; there was no appreciable increase in melting temperature of DNA when salbutamol was presented in DNA solution; the fluorescence intensity of salbutamol-DNA decrease with the increasing ionic strength; the relative viscosity of DNA did not change in the presence of salbutamol; the binding constant of salbutamol with double strand DNA (dsDNA) was much higher than that of it with single strand DNA (ssDNA). All these results indicated that the binding mode of salbutamol to DNA should be groove binding. The thermodynamic parameters suggested that hydrogen bond or van der Waals force might play an important role in salbutamol binding to DNA. According to the Förster energy transference theory, the binding distance between the acceptor and donor was 3.70 nm.

  11. Binding characteristics of salbutamol with DNA by spectral methods

    NASA Astrophysics Data System (ADS)

    Bi, Shuyun; Pang, Bo; Zhao, Tingting; Wang, Tianjiao; Wang, Yu; Yan, Lili

    2013-07-01

    Salbutamol interacting with deoxyribonucleic acid (DNA) was examined by fluorescence, UV absorption, viscosity measurements, and DNA melting techniques. The binding constants and binding sites were obtained at different temperatures by fluorescence quenching. The Stern-Volmer plots showed that the quenching of fluorescence of salbutamol by DNA was a static quenching. To probe the binding mode, various analytical methods were performed and the results were as follows: hyperchromic effect was shown in the absorption spectra of salbutamol upon addition of DNA; there was no appreciable increase in melting temperature of DNA when salbutamol was presented in DNA solution; the fluorescence intensity of salbutamol-DNA decrease with the increasing ionic strength; the relative viscosity of DNA did not change in the presence of salbutamol; the binding constant of salbutamol with double strand DNA (dsDNA) was much higher than that of it with single strand DNA (ssDNA). All these results indicated that the binding mode of salbutamol to DNA should be groove binding. The thermodynamic parameters suggested that hydrogen bond or van der Waals force might play an important role in salbutamol binding to DNA. According to the Förster energy transference theory, the binding distance between the acceptor and donor was 3.70 nm.

  12. Temporal and spectral characteristics of terrestrial gamma flashes

    NASA Astrophysics Data System (ADS)

    Nemiroff, R. J.; Bonnell, J. T.; Norris, J. P.

    1996-08-01

    We have analyzed the BATSE high time resolution data for several terrestrial gamma flashes (TGFs) to characterize this newly identified phenomenon, which may be related to atmospheric lightning. The minimum timescale for TGF variability is 40-250 μs. In general, TGFs are spectrally much harder than cosmic gamma-ray bursts (GRBs), but as in GRBs, pulses within a TGF tend to peak earlier at higher energies and can have different spectra. Spectra for several TGFs were examined and found to be better fit in the 25-500 keV range by a power-law than a black body model. From empirical comparisons, we speculate that if TGFs are related to known high-atmospheric lightning events, then they are more probably related to red sprites than to blue jets or trans-ionospheric pulse pairs.

  13. Analysis of the excited-state absorption spectral bandshape of oligofluorenes

    NASA Astrophysics Data System (ADS)

    Hayes, Sophia C.; Silva, Carlos

    2010-06-01

    We present ultrafast transient absorption spectra of two oligofluorene derivatives in dilute solution. These spectra display a photoinduced absorption band with clear vibronic structure, which we analyze rigorously using a time-dependent formalism of absorption to extract the principal excited-state vibrational normal-mode frequencies that couple to the electronic transition, the configurational displacement of the higher-lying excited state, and the reorganization energies. We can model the excited-state absorption spectrum using two totally symmetric vibrational modes with frequencies 450 (dimer) or 400 cm-1 (trimer), and 1666 cm-1. The reorganization energy of the ground-state absorption is rather insensitive to the oligomer length at 230 meV. However, that of the excited-state absorption evolves from 58 to 166 meV between the oligofluorene dimer and trimer. Based on previous theoretical work [A. Shukla et al., Phys. Rev. B 67, 245203 (2003)], we assign the absorption spectra to a transition from the 1Bu excited state to a higher-lying mAg state, and find that the energy of the excited-state transition with respect to the ground-state transition energy is in excellent agreement with the theoretical predictions for both oligomers studied here. These results and analysis permit profound understanding of the nature of excited-state absorption in π-conjugated polymers, which are the subject of general interest as organic semiconductors in the solid state.

  14. Effects of lump characteristics on plutonium self absorption correction methods

    SciTech Connect

    Curtis, D. C.; Wormald, M. R.; Croft, S.

    2007-07-01

    An evaluation study has been undertaken to assess the robustness of several published Pu self-absorption correction methods against variation in size, shape, density etc. for use in the gamma assay of nuclear waste. The correction methods studied are a numerical plutonium self absorption correction (PuSAC) technique, the Fleissner 2-line, Fleissner 3-line and Infinite Energy Extrapolation methods with both linear and polynomial extrapolation to 1/E=0. The performance of these methods has been compared for a limited set of measured encapsulated PuO{sub 2} sources plus a range of modelled unencapsulated Pu lumps. An indication of the magnitude of the uncertainties of the numerical PuSAC method has been determined for cases of blind assays where the Pu material, shape and distribution are unknown with the aim of ultimately applying it to real waste. The importance of the range of Pu lumps used in the baseline modelled dataset has been examined. Data are presented to illustrate how the uncertainties in the method are affected by the shape, composition, density, number and mass distribution of Pu particles in a sample for a given modelled base dataset. (authors)

  15. Energy absorption characteristics of lightweight structural member by stacking conditions

    NASA Astrophysics Data System (ADS)

    Choi, Juho; Yang, Yongjun; Hwang, Woochae; Pyeon, Seokbeom; Min, Hanki; Yeo, Ingoo; Yang, Inyoung

    2012-04-01

    The recent trend in vehicle design is aimed at improving crash safety and environmental-friendliness. To solve these issues, the needs for lighter vehicle to limit exhaust gas and improve fuel economy has been requested for environmental-friendliness. Automobile design should be made for reduced weight once the safety of vehicle is maintained. In this study, composite structural members were manufactured using carbon fiber reinforced plastic (CFRP) which are representative lightweight structural materials. Carbon fiber has been researched as alternative to metals for lightweight vehicle and better fuel economy. CFRP is an anisotropic material which is the most widely adapted lightweight structural member because of their inherent design flexibility and high specific strength and stiffness. Also, variation of CFRP interface number is important to increase the energy absorption capacity. In this study, one type of circular shaped composite tube was used, combined with reinforcing foam. The stacking condition was selected to investigate the effect of the fiber orientation angle and interface number. The crashworthy behavior of circular composite material tubes subjected to static axial compression under same conditions is reported. The axial static collapse tests were carried out for each section member. The collapse modes and the energy absorption capability of the members were analyzed.

  16. Energy absorption characteristics of lightweight structural member by stacking conditions

    NASA Astrophysics Data System (ADS)

    Choi, Juho; Yang, Yongjun; Hwang, Woochae; Pyeon, Seokbeom; Min, Hanki; Yeo, Ingoo; Yang, Inyoung

    2011-11-01

    The recent trend in vehicle design is aimed at improving crash safety and environmental-friendliness. To solve these issues, the needs for lighter vehicle to limit exhaust gas and improve fuel economy has been requested for environmental-friendliness. Automobile design should be made for reduced weight once the safety of vehicle is maintained. In this study, composite structural members were manufactured using carbon fiber reinforced plastic (CFRP) which are representative lightweight structural materials. Carbon fiber has been researched as alternative to metals for lightweight vehicle and better fuel economy. CFRP is an anisotropic material which is the most widely adapted lightweight structural member because of their inherent design flexibility and high specific strength and stiffness. Also, variation of CFRP interface number is important to increase the energy absorption capacity. In this study, one type of circular shaped composite tube was used, combined with reinforcing foam. The stacking condition was selected to investigate the effect of the fiber orientation angle and interface number. The crashworthy behavior of circular composite material tubes subjected to static axial compression under same conditions is reported. The axial static collapse tests were carried out for each section member. The collapse modes and the energy absorption capability of the members were analyzed.

  17. Surfactant-directed synthesis of silver nanorods and characteristic spectral changes occurred by their morphology evolution

    NASA Astrophysics Data System (ADS)

    Zhang, Wen; Hu, Guansong; Zhang, Wanzhong; Qiao, Xueliang; Wu, Kai; Chen, Qingyuan; Cai, Yuchun

    2014-11-01

    Silver nanorods with different polydispersity were synthesized in the cetyltrimethylammonium bromide (CTAB) rod-shaped micelles by inducing the orientation growth of silver seeds and adjusting the volumes of CTAB. The reaction for the formation of silver nanorods had basically finished in 10 min. A suitable volume of CTAB (i.e., 15.0 mL of 0.1 M CTAB) is beneficial to obtain high-quality silver nanorods in the given reaction system. That is, the volume of added CTAB is a key factor to determine the polydispersity of the formed nanorods. The aging time plays a critical role in the morphology evolution of silver nanorods due to the oxidation of silver nanorods with Br-, O2 and the Ostwald ripening of the nanoparticles. As a result, the characteristic spectral changes occurred due to the morphology evolution of silver nanorods. The ablation in the top ends of the longer nanorods is often accompanied by the growth of some shorter nanorods and nanospheres. The size distribution of silver nanorods might be more uniform in the early aging stage. All the nanorods in the colloidal solution should turn into the near-spherical nanoparticles with larger sizes and thus the characteristic absorption should change to single peak centered at about 400 nm. Based on the research results, mathematical models are proposed for explaining the formation and morphology changes of silver nanorods. The morphology evolution of silver nanorods may be important and can be used as a reference for preparing silver nanorods, nanowires and other anisotropic nanomaterials.

  18. Spectral Fingerprinting: The potential of VNIR-SWIR spectral characteristics for tracing sediment sources in a Spanish mesoscale catchment

    NASA Astrophysics Data System (ADS)

    Brosinsky, Arlena; Foerster, Saskia; Segl, Karl; Bronstert, Axel; Kaufmann, Hermann; Lopéz-Tarazón, José-Andrés

    2014-05-01

    Knowledge on the origin of suspended sediment can greatly facilitate erosion prevention and thus sustainable watershed management. One approach providing information on the origin of suspended sediments is the fingerprinting technique. It is based on the assumption that potential sediment sources can be discriminated and that the contribution of these sources to the sediment can be determined on the basis of distinctive characteristics (fingerprints). Recent studies indicate that VNIR-SWIR reflectance characteristics of soil may be a rapid, inexpensive alternative to traditional fingerprinting properties such as e.g. geochemical composition. In this study, we aim at further assessing the potential of this innovative sediment tracing technique, specifically whether (a) potential sediment sources can be reliably identified based on spectral features, (b) field derived source information (more rapid) is sufficient for spectral fingerprinting, (c) spectral fingerprints permit the quantification of source contribution, and (d) to examine changes in the relative contributions from different sources both, between and within individual storm events. Therefore, samples were collected in the Isábena catchment (445 km²) in the central Spanish Pyrenees: 1) soil samples from the main potential source areas and 2) suspended sediment samples during four flood events in autumn 2011 and spring 2012 at the catchment outlet and at several subcatchment outlets. In addition, 3) artificial mixtures of known proportions were produced from soil samples for testing of key assumptions in a controlled environment. Soil samples (1) were spectrally measured in the field using an ASD spectrometer and subsequently all samples (1-3) were dried and spectrally measured in the laboratory using the same equipment. Colour parameters and physically based features with relation to organic carbon, iron oxide and clay content were calculated from field- and laboratory spectra. Principal component

  19. Study of gain and photoresponse characteristics for back-illuminated separate absorption and multiplication GaN avalanche photodiodes

    SciTech Connect

    Wang, Xiaodong; Pan, Ming; Hou, Liwei; Xie, Wei; Hu, Weida Xu, Jintong; Li, Xiangyang; Chen, Xiaoshuang Lu, Wei

    2014-01-07

    The gain and photoresponse characteristics have been numerically studied for back-illuminated separate absorption and multiplication (SAM) GaN avalanche photodiodes (APDs). The parameters of fundamental models are calibrated by simultaneously comparing the simulated dark and light current characteristics with the experimental results. Effects of environmental temperatures and device dimensions on gain characteristics have been investigated, and a method to achieve the optimum thickness of charge layer is obtained. The dependence of gain characteristics and breakdown voltage on the doping concentration of the charge layer is also studied in detail to get the optimal charge layer. The bias-dependent spectral responsivity and quantum efficiency are then presented to study the photoresponse mechanisms inside SAM GaN APDs. It is found the responsivity peak red-shifts at first due to the Franz-Keldysh effect and then blue-shifts due to the reach-through effect of the absorption layer. Finally, a new SAM GaN/AlGaN heterojunction APD structure is proposed for optimizing SAM GaN APDs.

  20. Effect of radiometric errors on accuracy of temperature-profile measurement by spectral scanning using absorption-emission pyrometry

    NASA Technical Reports Server (NTRS)

    Buchele, D. R.

    1972-01-01

    The spectral-scanning method may be used to determine the temperature profile of a jet- or rocket-engine exhaust stream by measurements of gas radiation and transmittance, at two or more wavelengths. A single, fixed line of sight is used, using immobile radiators outside of the gas stream, and there is no interference with the flow. At least two sets of measurements are made, each set consisting of the conventional three radiometric measurements of absorption-emission pyrometry, but each set is taken over a different spectral interval that gives different weight to the radiation from a different portion of the optical path. Thereby, discrimination is obtained with respect to location along the path. A given radiometric error causes an error in computed temperatures. The ratio between temperature error and radiometric error depends on profile shape, path length, temperature level, and strength of line absorption, and the absorption coefficient and its temperature dependency. These influence the choice of wavelengths, for any given gas. Conditions for minimum temperature error are derived. Numerical results are presented for a two-wavelength measurement on a family of profiles that may be expected in a practical case of hydrogen-oxygen combustion. Under favorable conditions, the fractional error in temperature approximates the fractional error in radiant-flux measurement.

  1. Distributed Seismic Moment Fault Model, Spectral Characteristics and Radiation Patterns

    NASA Astrophysics Data System (ADS)

    Shani-Kadmiel, Shahar; Tsesarsky, Michael; Gvirtzman, Zohar

    2014-05-01

    We implement a Distributed Seismic Moment (DSM) fault model, a physics-based representation of an earthquake source based on a skewed-Gaussian slip distribution over an elliptical rupture patch, for the purpose of forward modeling of seismic-wave propagation in 3-D heterogeneous medium. The elliptical rupture patch is described by 13 parameters: location (3), dimensions of the patch (2), patch orientation (1), focal mechanism (3), nucleation point (2), peak slip (1), rupture velocity (1). A node based second order finite difference approach is used to solve the seismic-wave equations in displacement formulation (WPP, Nilsson et al., 2007). Results of our DSM fault model are compared with three commonly used fault models: Point Source Model (PSM), Haskell's fault Model (HM), and HM with Radial (HMR) rupture propagation. Spectral features of the waveforms and radiation patterns from these four models are investigated. The DSM fault model best incorporates the simplicity and symmetry of the PSM with the directivity effects of the HMR while satisfying the physical requirements, i.e., smooth transition from peak slip at the nucleation point to zero at the rupture patch border. The implementation of the DSM in seismic-wave propagation forward models comes at negligible computational cost. Reference: Nilsson, S., Petersson, N. A., Sjogreen, B., and Kreiss, H.-O. (2007). Stable Difference Approximations for the Elastic Wave Equation in Second Order Formulation. SIAM Journal on Numerical Analysis, 45(5), 1902-1936.

  2. Spectral characteristics of normal and nutrient-deficient maize leaves

    NASA Technical Reports Server (NTRS)

    Al-Abbas, A. H.; Barr, R.; Hall, J. D.; Crane, F. L.; Baumgardner, M. F.

    1972-01-01

    Reflectance, transmittance and absorbance spectra of normal and six types of mineral-deficient (N,P,K,S,Mg and Ca) maize (Zea mays L.) leaves were analyzed at 30 selected wavelengths along the electromagnetic spectrum from 500 to 2600 nm. Chlorophyll content and percent leaf moisture were also determined. Leaf thermograms were obtained for normal, N- and S- deficient leaves. The results of the analysis of variance showed significant differences in reflectance, transmittance and absorbance in the visible wavelengths among leaf numbers 3, 4, and 5, among the seven nutrient treatments, and among the interactions of leaves and treatments. In the reflective infrared wavelengths only treatments produced significant differences. The chlorophyll content of leaves was reduced in all deficiencies in comparison to controls. Percent moisture was increased in S-, Mg- and N- deficiencies. Positive correlation (r = 0.707) between moisture content and percent absorption at both 1450 and 1930 nm were obtained. Polynomial regression analysis of leaf thickness and leaf moisture content showed that these two variables were significantly and directly related (r = 0.894).

  3. Iron-absorption band analysis for the discrimination of iron-rich zones. [infrared spectral reflectance of Nevada iron deposits

    NASA Technical Reports Server (NTRS)

    Rowan, L. C. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. Most major rock units and unaltered and altered areas in the study area can be discriminated on the basis of visible and near-infrared spectral reflectivity differences recorded from satellite altitude. These subtle spectral differences are detectable by digital ratioing of the MSS bands and subsequent stretching to increase the contrast to enhance spectral differences. Hydrothermally altered areas appear as anomalous color patches within the volcanic-rock areas. A map has been prepared which can be regarded as an excellent reconnaissance exploration map, for use in targeting areas for more detailed geological, geochemical, and geophysical studies. Mafic and felsic rock types are easily discriminated on the color stretched-ratio composite. The ratioing process minimizes albedo effects, leaving only the recorded characteristic spectral response. The spectra of unaltered rocks appear different from those of altered rocks, which are typically dominated by limonite and clay minerals. It seems clear that differences in spectral shape can provide a basis for discrimination of geologic material, although the relations between visible and near-infrared spectral reflectivity and mineralogical composition are not yet entirely understood.

  4. Absorption and swelling characteristics of silver (I) antimicrobial wound dressings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An important characteristic of moist wound dressings is their ability to swell and absorb exudates from the wound, while maintaining a moist atmosphere at the wound site. At the Southern Regional Research Center (SRRC), we have previously developed antimicrobial silver-sodium-carboxymethylated (CM)-...

  5. Spectral characteristics of earth-space paths at 2 and 30 FHz

    NASA Technical Reports Server (NTRS)

    Baxter, R. A.; Hodge, D. B.

    1978-01-01

    Spectral characteristics of 2 and 30 GHz signals received from the Applications Technology Satellite-6 (ATS-6) are analyzed in detail at elevation angles ranging from 0 deg to 44 deg. The spectra of the received signals are characterized by slopes and break frequencies. Statistics of these parameters are presented as probability density functions. Dependence of the spectral characteristics on elevation angle is investigated. The 2 and 30 GHz spectral shapes are contrasted through the use of scatter diagrams. The results are compared with those predicted from turbulence theory. The average spectral slopes are in close agreement with theory, although the departure from the average value at any given elevation angle is quite large.

  6. Far-infrared permanent and induced dipole absorption of diatomic molecules in rare-gas fluids. I. Spectral theory

    NASA Astrophysics Data System (ADS)

    Roco, J. M. M.; Hernández, A. Calvo; Velasco, S.

    1995-12-01

    We present a spectral theory for the far-infrared absorption spectrum of a very diluted solution of diatomic molecules in a rare-gas fluid, that includes permanent and induced contributions. The absorption coefficient is given as the convolution of a translational spectrum and a rotational spectrum. The former is described in terms of time correlation functions associated to the induced dipole moment. The latter is discussed on the basis of a model consisting of a quantum rigid rotor interacting with a thermal bath, making use of time correlation functions associated to the different anisotropic orders of the solute-solvent intermolecular potential. Non-Markovian and line mixing effects are taken into account. Explicit expressions for the five leading contributions of the induced dipole moment are given.

  7. Towards photodetection with high efficiency and tunable spectral selectivity: graphene plasmonics for light trapping and absorption engineering.

    PubMed

    Zhang, Jianfa; Zhu, Zhihong; Liu, Wei; Yuan, Xiaodong; Qin, Shiqiao

    2015-08-28

    Plasmonics can be used to improve absorption in optoelectronic devices and has been intensively studied for solar cells and photodetectors. Graphene has recently emerged as a powerful plasmonic material. It shows significantly less loss compared to traditional plasmonic materials such as gold and silver and its plasmons can be tuned by changing the Fermi energy with chemical or electrical doping. Here we propose the use of graphene plasmonics for light trapping in optoelectronic devices and show that the excitation of localized plasmons in doped, nanostructured graphene can enhance optical absorption in its surrounding medium including both bulky and two-dimensional materials by tens of times, which may lead to a new generation of photodetectors with high efficiency and tunable spectral selectivity in the mid-infrared and THz ranges.

  8. Broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region for measurements of nitrogen dioxide and formaldehyde

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Attwood, A. R.; Flores, J. M.; Zarzana, K. J.; Rudich, Y.; Brown, S. S.

    2016-01-01

    Formaldehyde (CH2O) is the most abundant aldehyde in the atmosphere, and it strongly affects photochemistry through its photolysis. We describe simultaneous measurements of CH2O and nitrogen dioxide (NO2) using broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region. The light source consists of a continuous-wave diode laser focused into a Xenon bulb to produce a plasma that emits high-intensity, broadband light. The plasma discharge is optically filtered and coupled into a 1 m optical cavity. The reflectivity of the cavity mirrors is 0.99930 ± 0.00003 (1- reflectivity = 700 ppm loss) at 338 nm, as determined from the known Rayleigh scattering of He and zero air. This mirror reflectivity corresponds to an effective path length of 1.43 km within the 1 m cell. We measure the cavity output over the 315-350 nm spectral region using a grating monochromator and charge-coupled device array detector. We use published reference spectra with spectral fitting software to simultaneously retrieve CH2O and NO2 concentrations. Independent measurements of NO2 standard additions by broadband cavity-enhanced absorption spectroscopy and cavity ring-down spectroscopy agree within 2 % (slope for linear fit = 1.02 ± 0.03 with r2 = 0.998). Standard additions of CH2O measured by broadband cavity-enhanced absorption spectroscopy and calculated based on flow dilution are also well correlated, with r2 = 0.9998. During constant mixed additions of NO2 and CH2O, the 30 s measurement precisions (1σ) of the current configuration were 140 and 210 pptv, respectively. The current 1 min detection limit for extinction measurements at 315-350 nm provides sufficient sensitivity for measurement of trace gases in laboratory experiments and ground-based field experiments. Additionally, the instrument provides highly accurate, spectroscopically based trace gas detection that may complement higher precision techniques based on non

  9. Gravity-induced absorption changes in Phycomyces blakesleeanus during parabolic flights: first spectral approach in the visible.

    PubMed

    Schmidt, Werner

    2006-12-01

    Gravity-induced absorption changes as experienced during a series of parabolas on the Airbus 300 Zero-G have been measured previously pointwise on the basis of dual-wavelength spectroscopy. Only the two wavelengths of 460 and 665 nm as generated by light-emitting diodes have been utilised during our first two parabolic-flight campaigns. In order to gain complete spectral information throughout the wavelength range from 400 to 900 nm, a miniaturized rapid scan spectrophotometer was designed. The difference of spectra taken at 0 g and 1.8 g presents the first gravity-induced absorption change spectrum measured on wild-type Phycomyces blakesleeanus sporangiophores, exhibiting a broad positive hump in the visible range and negative values in the near infrared with an isosbestic point near 735 nm. The control experiment performed with the stiff mutant A909 of Phycomyces blakesleeanus does not show this structure. These results are in agreement with those obtained with an array spectrophotometer. In analogy to the more thoroughly understood so-called light-induced absorption changes, we assume that gravity-induced absorption changes reflect redox changes of electron transport components such as flavins and cytochromes localised within the plasma membrane.

  10. Precise methane absorption measurements in the 1.64 μm spectral region for the MERLIN mission.

    PubMed

    Delahaye, T; Maxwell, S E; Reed, Z D; Lin, H; Hodges, J T; Sung, K; Devi, V M; Warneke, T; Spietz, P; Tran, H

    2016-06-27

    In this article we describe a high-precision laboratory measurement targeting the R(6) manifold of the 2ν3 band of (12)CH4. Accurate physical models of this absorption spectrum will be required by the Franco-German, Methane Remote Sensing LIDAR (MERLIN) space mission for retrievals of atmospheric methane. The analysis uses the Hartmann-Tran profile for modeling line shape and also includes line-mixing effects. To this end, six high-resolution and high signal-to-noise absorption spectra of air-broadened methane were recorded using a frequency-stabilized cavity ring-down spectroscopy apparatus. Sample conditions corresponded to room temperature and spanned total sample pressures of 40 hPa - 1013 hPa with methane molar fractions between 1 μmol mol(-1) and 12 μmol mol(-1). All spectroscopic model parameters were simultaneously adjusted in a multispectrum nonlinear least-squares fit to the six measured spectra. Comparison of the fitted model to the measured spectra reveals the ability to calculate the room-temperature, methane absorption coefficient to better than 0.1% at the on-line position of the MERLIN mission. This is the first time that such fidelity has been reached in modeling methane absorption in the investigated spectral region, fulfilling the accuracy requirements of the MERLIN mission. We also found excellent agreement when comparing the present results with measurements obtained over different pressure conditions and using other laboratory techniques. Finally, we also evaluated the impact of these new spectral parameters on atmospheric transmissions spectra calculations.

  11. Precise methane absorption measurements in the 1.64 μm spectral region for the MERLIN mission

    NASA Astrophysics Data System (ADS)

    Delahaye, T.; Maxwell, S. E.; Reed, Z. D.; Lin, H.; Hodges, J. T.; Sung, K.; Devi, V. M.; Warneke, T.; Spietz, P.; Tran, H.

    2016-06-01

    In this article we describe a high-precision laboratory measurement targeting the R(6) manifold of the 2ν3 band of 12CH4. High-fidelity modeling of this absorption spectrum for atmospheric temperature and pressure conditions will be required by the Franco-German, Methane Remote Sensing LIDAR (MERLIN) space mission for retrievals of atmospheric methane. The analysis uses the Hartmann-Tran profile for modeling line shape and also includes line-mixing effects. To this end, six high-resolution and high signal-to-noise ratio absorption spectra of air-broadened methane were recorded using a frequency-stabilized cavity ring-down spectroscopy apparatus. Sample conditions corresponded to room temperature and spanned total sample pressures of 40 hPa-1013 hPa with methane molar fractions between 1 µmol mol-1 and 12 µmol mol-1. All spectroscopic model parameters were simultaneously adjusted in a multispectrum nonlinear least squares fit to the six measured spectra. Comparison of the fitted model to the measured spectra reveals the ability to calculate the room temperature, methane absorption coefficient to better than 0.1% at the online position of the MERLIN mission. This is the first time that such fidelity has been reached in modeling methane absorption in the investigated spectral region, fulfilling the accuracy requirements of the MERLIN mission. We also found excellent agreement when comparing the present results with measurements obtained over different pressure conditions and using other laboratory techniques. Finally, we also evaluated the impact of these new spectral parameters on atmospheric transmissions spectra calculations.

  12. Characteristic Simulation of the Waste-Heat Utilization Absorption Cycles

    NASA Astrophysics Data System (ADS)

    Yoon, Jung-In; Oh, Hoo-Kyu; Kashiwagi, Takao

    In the recent years double effect cycles have gathered a lot of attention because of their good efficiency particularly fitting with preoccupation of energy saving and with recent environmental problems. Simulation studies on double effect absorption cycles for refrigeration purposes have been performed for H2O/LiBr fair. The purpose of this study is the objective for evaluating the possibilities of effectively utilizing waste-heat as a secondary heat source for the low temperature generator. The efficiency of the different cycles have been studied and the simulation results show that higher coefficient of performance could be obtained for standard parallel cycle (TYPE PA). The optimum designs and operating conditions were determined based on the operating conditions and the coefficient of performance. The effectiveness of introducing a waste-heat source of about the same temperature level as the low temperature generator is demonstrated. If the cycles are assisted by fuel cell waste-heat, the input of waste-heat to low temperature generation parallel cycle (TYPE PB) yields highest COP.

  13. Infrared absorption and emission characteristics of interstellar PAHs

    NASA Technical Reports Server (NTRS)

    Barker, J. R.; Allamandola, Louis J.; Tielens, Alexander G. G. M.; Barker, J. R.; Barker, J. R.

    1986-01-01

    The mid-infrared interstellar emission spectrum with features at 3.28, 6.2, 7.7, 8.7 and 11.3 microns is discussed in terms of the Polycyclic Aromatic Hydrocarbon (PAH) hypothesis, which is based on the suggestive, but inconclusive comparison between the interstellar emission spectrum with the infrared absorption and Raman spectra of a few PAHs. The fundamental vibrations of PAHs and PAH-like species which determine the IR and Raman properties are discussed. Interstellar IR band emission is due to relaxation from highly vibrationally excited PAHs excited by ultraviolet photons. The excitation/emission process is described and the IR fluorescence from one PAH, chrysene, is traced. Generally, there is sufficient energy to populate several vibrational levels in each mode. Molecular vibrational potentials are anharmonic and emission from these higher levels will fall at lower frequencies and produce weak features to the red of the stronger fundamentals. This process is also described and can account for some spectroscopic details of the interstellar emission spectra previously unexplained. Analysis of the interstellar spectrum shows that PAHs contain between 20 and 30 carbon atoms are responsible for the emission.

  14. Light absorption efficiencies of photosynthetic pigments: the dependence on spectral types of central stars

    NASA Astrophysics Data System (ADS)

    Komatsu, Yu; Umemura, Masayuki; Shoji, Mitsuo; Kayanuma, Megumi; Yabana, Kazuhiro; Shiraishi, Kenji

    2015-07-01

    For detecting life from reflection spectra on extrasolar planets, trace of photosynthesis is one of the indicators. However, it is not yet clear what kind of radiation environments is acceptable for photosynthesis. Light absorption in photosystems on the Earth occurs using limited photosynthetic pigments such as chlorophylls (Chls) and bacteriochlorophylls (BChls). Efficiencies of light absorption for the pigments were evaluated by calculating the specific molecular absorption spectra at the high accuracy-quantum mechanical level. We used realistic stellar radiation spectra such as F, G, K and M-type stars to investigate the efficiencies. We found that the efficiencies are increased with the temperature of stars, from M to F star. Photosynthetic pigments have two types of absorption bands, the Q y and Soret. In higher temperature stars like F star, contributions from the Soret region of the pigments are dominant for the efficiency. On the other hand, in lower temperature stars like M stars, the Q y band is crucial. Therefore, differences on the absorption intensity and the wavelength between the Q y and Soret band are the most important to characterize the photosynthetic pigments. Among photosynthetic pigments, Chls tend to be efficient in higher temperature stars, while BChls are efficient for M stars. Blueward of the 4000 Å break, the efficiencies of BChls are smaller than Chls in the higher temperature stars.

  15. [Absorption Characteristics and Simulation of LLM-105 in the Terahertz Range].

    PubMed

    Meng, Zeng-rui; Shang, Li-ping; Du, Yu; Deng, Hu

    2015-07-01

    2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105), a novel explosive with high energy and low sensibility. In order to study the molecular structure characteristics of the explosive, the absorption spectra of LLM-105 in the frequency range of 0.2-2.4 THz were detected by terahertz time-domain spectroscopy (THz-TDS). The results showed that a number of characteristic absorption peaks with different intensity located at 1.27, 1.59, 2.00, 2.08, 2.20, 2.29 THz. The article also simulated the absorption spectra of LLM-105 molecular crystal within 0.2-2.5 THz region by using Materials Studio 6.0 software based on density functional theory (DFT), and the simulated results agreed well with the experimental data except for the peak at 2.29 THz, which verified theoretically the accuracy of the experimental data. In addition, the vibrational modes of the characteristic peaks in the experimental absorption spectra were analyzed and identified, the results showed that the forming of the characteristic absorption peaks and the molecular vibration were closely related, which further provided important laboratory and technology support for the study of the transformation of molecule structure of LLM-105. There was no simulated frequency agreed with the experimental absorption peak at 2.29 THz, which may be caused by the vibration of the crystal lattice or other reasons.

  16. Spectral characteristics of vertical ground motion in the Northridge and other earthquakes

    SciTech Connect

    Bozorgnia, Y.; Niazi, M.; Campbell, K.W.

    1995-12-31

    Spectral characteristics of vertical ground motion recorded during the Northridge earthquake are evaluated and compared to those of other earthquakes. Relationship between vertical and horizontal spectra is examined through development of attenuation of vertical and horizontal response spectra. Vertical-to-horizontal response spectral relationship is then compared to that of 1989 Loma Prieta earthquake, and several other earthquakes recorded over SMART-1 array in Taiwan. This preliminary analysis shows that the main characteristics of vertical-to-horizontal spectral ratio are similar to those of other earthquakes. One main characteristic is that in the near-field region and in short period range, the ratio is much higher than commonly assumed ratio of 2/3.

  17. Investigation of Tree Spectral Reflectance Characteristics Using a Mobile Terrestrial Line Spectrometer and Laser Scanner

    PubMed Central

    Lin, Yi; Puttonen, Eetu; Hyyppä, Juha

    2013-01-01

    In mobile terrestrial hyperspectral imaging, individual trees often present large variations in spectral reflectance that may impact the relevant applications, but the related studies have been seldom reported. To fill this gap, this study was dedicated to investigating the spectral reflectance characteristics of individual trees with a Sensei mobile mapping system, which comprises a Specim line spectrometer and an Ibeo Lux laser scanner. The addition of the latter unit facilitates recording the structural characteristics of the target trees synchronously, and this is beneficial for revealing the characteristics of the spatial distributions of tree spectral reflectance with variations at different levels. Then, the parts of trees with relatively low-level variations can be extracted. At the same time, since it is difficult to manipulate the whole spectrum, the traditional concept of vegetation indices (VI) based on some particular spectral bands was taken into account here. Whether the assumed VIs capable of behaving consistently for the whole crown of each tree was also checked. The specific analyses were deployed based on four deciduous tree species and six kinds of VIs. The test showed that with the help of the laser scanner data, the parts of individual trees with relatively low-level variations can be located. Based on these parts, the relatively stable spectral reflectance characteristics for different tree species can be learnt. PMID:23877127

  18. Stable nocturnal spectral characteristics over a vineyard (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Prueger, John H.; Alfieri, joesph G.; Hipps, Lawrence E.; Kustas, William P.; Neale, Christopher M.

    2016-10-01

    Vineyards are agricultural surfaces that present a unique structural perturbation to the mean wind flow. As part of the Grape Remote Sensing Atmospheric Profiling and Evapotranspiration Experiment (GRAPEX) a 10-m profile tower of three sonic anemometers at 2, 3.75 and 8 m above ground level in in a mature vineyard having was deployed to measure high frequency diurnal variations of 3-dimensional velocity components (u, v, w) and temperature (T) throughout the growing season. Previous work has been published involving eddy covariance measurements in vineyards but these mostly represented convective daytime unstable conditions. Significantly less has been published about turbulence in vineyards during stable nocturnal periods. Hence, in this study we focused on the nocturnal stable periods under clear skies and relatively light winds typical of the northern portion of California's Central Valley. Our objective was to characterize and evaluate turbulent exchange processes in the layer near the top of a vine canopy during nocturnal periods which are often characterized by weak and intermittent turbulence. Spectra, cospectra and coherence plots were evaluated for nocturnal periods. The spectra suggest there are periods of intermittent turbulence with features indicative of local and regional scale processes. Additionally the impact of the vine structure and spacing on slow meandering flows enhance the decomposition of organized turbulent eddies resulting in intricate mechanical turbulence generated by intermittent eddies that are rapidly decomposed as eddies interact with the vine structure and spacing. Preliminary results will be discussed that provide insight into turbulence characteristics at several heights above a canopy vineyard as affected by vine structure and spacing, wind speed, direction and stable conditions.

  19. Experimental and Ab Initio Studies of the HDO Absorption Spectrum in the 13165-13500 1/cm Spectral Region

    NASA Technical Reports Server (NTRS)

    Schwenke, David; Naumenko, Olga; Bertseva, Elena; Campargue, Alain; Arnold, James O. (Technical Monitor)

    2000-01-01

    The HDO absorption spectrum has been recorded in the 13165 - 13500 cm(exp-1) spectral region by Intracavity Laser Absorption Spectroscopy. The spectrum (615 lines), dominated by the 2n2 + 3n3 and n1+3n3 bands was assigned and modeled leading to the derivation of 196 accurate energy levels of the (103) and (023) vibrational states. Finally, 150 of these levels have been reproduced by an effective Hamiltonian involving two vibrational dark states interacting with the (023) and ( 103) bright states. The rms deviation achieved by variation of 28 parameters is 0.05-1 cm, compared to an averaged experimental uncertainty of 0.007-1 cm, indicating the limit of validity of the effective Hamiltonian approach for HDO at high vibrational excitation. The predictions of previous ab initio calculations of the HDO spectrum were extensively used in the assignment process. The particular spectral region under consideration has been used to test and discuss the improvements of new ab initio calculations recently performed on the basis of the same potential energy surface but with an improved dipole moment surface. The improvements concern both the energy levels and the line intensities. In particular, the strong hybrid character of the n1+3n3 band is very well accounted for by the the new ab initio calculations.

  20. X-ray absorption spectral studies of copper (II) mixed ligand complexes

    NASA Astrophysics Data System (ADS)

    Soni, B.; Dar, Davood Ah; Shrivastava, B. D.; Prasad, J.; Srivastava, K.

    2014-09-01

    X-ray absorption spectra at the K-edge of copper have been studied in two copper mixed ligand complexes, one having tetramethyethylenediamine (tmen) and the other having tetraethyethylenediamine (teen) as one of the ligands. The spectra have been recorded at BL-8 dispersive extended X-ray absorption fine structure (EXAFS) beamline at the 2.5 GeV INDUS- 2 synchrotron, RRCAT, Indore, India. The data obtained has been processed using the data analysis program Athena. The energy of the K-absorption edge, chemical shift, edge-width and shift of the principal absorption maximum in the complexes have been determined and discussed. The values of these parameters have been found to be approximately the same in both the complexes indicating that the two complexes possess similar chemical environment around the copper metal atom. The chemical shift has been utilized to estimate effective nuclear charge on the absorbing atom. The normalized EXAFS spectra have been Fourier transformed. The position of the first peak in the Fourier transform gives the value of first shell bond length, which is shorter than the actual bond length because of energy dependence of the phase factors in the sine function of the EXAFS equation. This distance is thus the phase- uncorrected bond length. Bond length has also been determined by Levy's, Lytle's and Lytle, Sayers and Stern's (LSS) methods. The results obtained from LSS and the Fourier transformation methods are comparable with each other, since both are phase uncorrected bond lengths.

  1. Water absorption characteristics and structural properties of rice for sake brewing.

    PubMed

    Mizuma, Tomochika; Kiyokawa, Yoshifumi; Wakai, Yoshinori

    2008-09-01

    This study investigated the water absorption curve characteristics and structural properties of rice used for sake brewing. The parameter values in the water absorption rate equation were calculated using experimental data. Differences between sample parameters for rice used for sake brewing and typical rice were confirmed. The water absorption curve for rice suitable for sake brewing showed a quantitatively sharper turn in the S-shaped water absorption curve than that of typical rice. Structural characteristics, including specific volume, grain density, and powdered density of polished rice, were measured by a liquid substitution method using a Gay-Lussac pycnometer. In addition, we calculated internal porosity from whole grain and powdered grain densities. These results showed that a decrease in internal porosity resulted from invasion of water into the rice grain, and that a decrease in the grain density affected expansion during the water absorption process. A characteristic S-shape water absorption curve for rice suitable for sake brewing was related to the existence of an invisible Shinpaku-like structure.

  2. Absorption characteristics of lithium bromide (LiBr) solution constrained by superhydrophobic nanofibrous structures

    SciTech Connect

    Isfahani, RN; Moghaddam, S

    2013-08-01

    An experimental study on absorption characteristics of water vapor into a thin lithium bromide (LiBr) solution flow is presented. The LiBr solution flow is constrained between a superhydrophobic vapor permeable wall and a solid surface that removes the heat of absorption. As opposed to conventional falling film absorbers, in this configuration, the solution film thickness and velocity can be controlled independently to enhance the absorption rate. The effects of water vapor pressure, cooling surface temperature, solution film thickness, and solution flow velocity on the absorption rate are studied. An absorption rate of approximately 0.006 kg/m(2) s was measured at a LiBr solution channel thickness and flow velocity of 100 mu m and 5 mm/s, respectively. The absorption rate increased linearly with the water vapor driving potential at the test conditions of this study. It was demonstrated that decreasing the solution film thickness and increasing the solution velocity enhance the absorption rate. The high absorption rate and the inherently compact form of the proposed,absorber facilitate development of compact small-scale waste heat or solar-thermal driven cooling systems. Published by Elsevier Ltd.

  3. Evidence for cyclotron absorption from spectral features in gamma-ray bursts seen with Ginga

    NASA Technical Reports Server (NTRS)

    Murakami, T.; Fujii, M.; Hayashida, K.; Itoh, M.; Nishimura, J.

    1988-01-01

    New observations by the gamma-ray burst detector on board the Ginga satellite, which has two well-calibrated detectors covering a wide energy range of 1.5 to 375 keV, are reported. The spectral features obtained are consistent with first and second cyclotron harmonics. This finding is taken as strong evidence for the magnetized neutron star model of gamma-ray bursts.

  4. Development of a Cone Penetrometer for Measuring Spectral Characteristics of Soils in Situ

    NASA Technical Reports Server (NTRS)

    Lee, Landris T., Jr.; Malone, Philip G.

    1993-01-01

    A patent was recently granted to the U.S. Army for an adaptation of a soil cone penetrometer that can be used to measure the spectral characteristics (fluorescence or reflectance) of soils adjacent to the penetrometer rod. The system can use a variety of light sources and spectral analytical equipment. A laser induced fluorescence measuring system has proven to be of immediate use in mapping the distribution of oil contaminated soil at waste disposal and oil storage areas. The fiber optic adaptation coupled with a cone penetrometer permits optical characteristics of the in-situ soil to be measured rapidly, safely, and inexpensively. The fiber optic cone penetrometer can be used to gather spectral data to a depth of approximately 25 to 30 m even in dense sands or stiff clays and can investigate 300 m of soil per day. Typical detection limits for oil contamination in sand is on the order of several hundred parts per million.

  5. Beam profile and spectral characteristic of THz wave in free space

    NASA Astrophysics Data System (ADS)

    Zhao, Guozhong; Yang, Kun; Wu, Meng; Wu, Lizhong

    2008-12-01

    Beam profile and spectral characteristic of terahertz (THz) wave in free space are presented in this paper. The beam width of THz wave at the focus point of parabolic mirror is obtained by means of the narrow-slit measurement. By the spectroscopic imaging, we present the transverse mode distribution of THz beam on the cross-section of focus point. Our experimental results show that the centre wavelength of THz spectra has a distinguished red-shift when it is far away the centre of THz focus point. The spectral range of THz wave far from the focus point is less than that of the centre. This kind of spectral characteristic of THz wave is closely related to the diffraction effect of electromagnetic wave.

  6. Spectral Characteristics of Speech at the Ear: Implications for Amplification in Children.

    ERIC Educational Resources Information Center

    Pittman, Andrea L.; Stelmachowicz, Patricia G.; Lewis, Dawna E.; Hoover, Brenda M.

    2003-01-01

    A study examined the long- and short-term spectral characteristics of speech simultaneously recorded at the ear and at a reference microphone position. Twenty adults and 26 children (ages 2-4) produced 9 short sentences. Children's vocal levels were low in amplitude at both the ear and at the microphone position. (Contains references.) (CR)

  7. Applying and comparing two chemometric methods in absorption spectral analysis of photopigments from Arctic microalgae.

    PubMed

    Zhang, Fang; He, Jianfeng; Xia, Lihua; Cai, Minghong; Lin, Ling; Guang, Yingzhi

    2010-11-01

    Pigment absorption property of two arctic microalgae species (Skeletonema marinoi and Chlorella sp.) cultured at three temperatures (0, 4 and 8°C) was analyzed. Carotenoids and chlorophyll (Chl) c were positive factors to the high cell activities and primary productivities of S. marinoi at 4°C and 0°C, respectively; whereas Chl a had a positive effect on Chlorella sp. at all three temperatures, and carotenoids had a relatively high effect at 0°C. The absorption locations of photopigments were analyzed in detail using both fourth derivative and Symlet-6 wavelet analysis. Both methods precisely detected pigments with a relative large content; the fourth derivative analysis specifically detected the existence of a Chl a peak at about 410 nm and showed better differentiation of diatoxanthin, whereas the wavelet analysis distinctively indicated the existence of chlorophyllide a, β-carotene, and Chl c. The separation limit to pigment peaks of the fourth derivative spectra (4 nm) was 1 nm higher than that of the wavelet high-frequency spectra (3 nm). The wavelet high-frequency spectra were more stable in detecting pigment locations and were more effective in discriminating microalgae. Small algebraic difference of 10(-16) between the reconstructed absorption spectra obtained by the inverse wavelet transform and their corresponding original spectra also showed the validity of Symlet-6 wavelet in the detection of pigments. Another specific discovery of this research is the existence of a Chl a allomer in Chlorella sp., which was detected by both methods.

  8. Fitting peculiar spectral profiles in He I 10830Å absorption features

    NASA Astrophysics Data System (ADS)

    González Manrique, S. J.; Kuckein, C.; Pastor Yabar, A.; Collados, M.; Denker, C.; Fischer, C. E.; Gömöry, P.; Diercke, A.; Bello González, N.; Schlichenmaier, R.; Balthasar, H.; Berkefeld, T.; Feller, A.; Hoch, S.; Hofmann, A.; Kneer, F.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Verma, M.; Volkmer, R.; von der Lühe, O.; Waldmann, T.

    2016-11-01

    The new generation of solar instruments provides better spectral, spatial, and temporal resolution for a better understanding of the physical processes that take place on the Sun. Multiple-component profiles are more commonly observed with these instruments. Particularly, the He I 10830 Å triplet presents such peculiar spectral profiles, which give information on the velocity and magnetic fine structure of the upper chromosphere. The purpose of this investigation is to describe a technique to efficiently fit the two blended components of the He I 10830 Å triplet, which are commonly observed when two atmospheric components are located within the same resolution element. The observations used in this study were taken on 2015 April 17 with the very fast spectroscopic mode of the GREGOR Infrared Spectrograph (GRIS) attached to the 1.5-m GREGOR solar telescope, located at the Observatorio del Teide, Tenerife, Spain. We apply a double-Lorentzian fitting technique using Levenberg-Marquardt least-squares minimization. This technique is very simple and much faster than inversion codes. Line-of-sight Doppler velocities can be inferred for a whole map of pixels within just a few minutes. Our results show sub- and supersonic downflow velocities of up to 32 km s-1 for the fast component in the vicinity of footpoints of filamentary structures. The slow component presents velocities close to rest.

  9. Integral light-scattering and absorption characteristics of large, nonspherical particles

    NASA Astrophysics Data System (ADS)

    Kokhanovsky, Alexander A.; Macke, Andreas

    1997-11-01

    We obtain and analyze simple analytical formulas for asymmetry parameters and absorption cross sections of large, nonspherical particles. The formulas are based on the asymptotic properties of these characteristics at strong and weak absorption of radiation inside particles. The absorption cross section depends on parameter , which determines the value of the light-absorption cross section for weakly absorbing particles. It is larger for nonspherical scatterers. The asymmetry parameter depends on two parameters. The first is the asymmetry parameter g0 of a nonspherical, transparent particle with the same shape as an absorbing one. The second parameter, , determines the strength of the influence of light absorption on the value of the asymmetry parameter. Parameter is larger for nonspherical particles. One can find these three parameters ( , g0 , and ) using a ray-tracing code (RTC) for nonabsorbing and weakly absorbing particles. The RTC can then be used to check the accuracy of the equations at any absorption for hexagonal cylinders and spheroids. It is found that the error of computing the absorption cross section and 1 -g (g is the asymmetry parameter) is less than 20% at the refractive index of particles n = 1.333. Values for asymmetry parameters of large, nonabsorbing, spheroidal particles with different aspect ratios are tabulated for the first time to our knowledge. They do not depend on the size of particles and can serve as an independent check of the accuracy of T-matrix codes for large parameters.

  10. Effect of the additional anode layers on the absorption enhancement characteristic of plasmonic organic solar cells

    NASA Astrophysics Data System (ADS)

    Yoo, Sanghyuk; Kim, Jungho

    2014-12-01

    We numerically investigate the effect of additional anode layers on the absorption enhancement characteristic of pyramidal-grating plasmonic organic solar cells (OSCs) using the finite element method. The behaviors of the plasmonic absorption enhancement are compared between a “simple” structure consisting of only the active and metal cathode layers and a “practical” structure with the additional anode layers. The plasmonic absorption enhancement is identified by comparing the polarization-dependent absorbance spectra between the planar and plasmonic OSCs. When the active-layer thickness is small, the plasmonic resonance condition changes owing to the addition of the anode layers. When the active-layer thickness is large, the plasmonic resonance condition and corresponding absorption behavior show a slight difference irrespective of the inclusion of the additional anode layers. Therefore, the additional anode layers should be included in the optical analysis and design of plasmonic OSCs when the active-layer thickness is small.

  11. Improvement of Electromagnetic Wave Absorption Ability by Reducing Impedance Oscillation Characteristics

    NASA Astrophysics Data System (ADS)

    Itoh, Masahiro; Terada, Masao; Sasada, Masaaki; Machida, Ken-ichi

    2012-01-01

    Improvement of the electromagnetic wave absorption ability was examined from the electromagnetic point of view. The oscillation behavior in relation to incident impedance derived from a hyperbolic tangent function can be reduced by increasing the imaginary part, i.e., loss value, of permeability and/or permittivity owing to its mathematical characteristics. It was demonstrated that the electromagnetic wave absorption ability was obviously enhanced by inserting the lossy magnetic layer between the electromagnetic wave absorber and a reflector. The absorption ability was improved further by pilling the polyurethane foam plate having lower permittivity to provide -9.6 dB (ca. 89% absorption) for the frequency range above 0.75 GHz with a total absorber thickness of 15.15 mm.

  12. [Progress in spectral characteristics of biological soil crust of arid or semiarid region].

    PubMed

    Fang, Shi-bo; Liu, Hua-jie; Zhang, Xin-shi; Dong, Ming; Liu, Jian-dong

    2008-08-01

    The Biological Soil Crusts (BSC) (also known as organic or microphytic crust) can be formed by different combinations of microphytic communities including mosses, lichens, liverworts, algae, fungi, cyanobacteria (= blue-green algae or Cyanophyta), as well as bacteria. Large areas of sand fields in arid and semi-arid regions are covered by BSC. Remote sensing distinction should be made between physical and biogenical crust formations. It was reviewed the advances of domestic and overseas studies of BSC spectral characteristics, as well as spectral reflectance measurement in situ of our workgruop. When the BSC is wet, it turns green, a notable change in the reflectance curve occurs. The wet BSC's spectral reflectance curve is similar to those of the higher plants and therefore may lead to misinterpretation of the vegetation dynamics and to overestimation of ecosystem productivity. This spectral feature produces a much higher NDVI value for the wet moss BSC than for the dry moss BSC (0.65 vs. 0.30 units, respectively), a higher NDVI value for the wet algae BSC than for the dry algae BSC (0.30 vs. 0.15 units, respectively). The "maximum value composite" (MVC) technique is used to eliminate the effect of clouds and haze from vegetation maps. Misinterpretation of the vegetation dynamics could be more severe due to the MVC technique used to compose the global vegetation maps in the study of vegetation dynamics. But relatively limited research has been conducted to investigate the spectral characteristics of BSC change with different moisture conditions and under different seasons. More research works could be considered in spectral characteristics of BSC. The researches would be useful for detecing and mapping BSC, from remote sensing imagery. It also is to the advantage to employ Vegetation Index wisely.

  13. Leaf Optical Properties in Higher Plants: Linking Spectral Characteristics to Stress and Chlorophyll Concentration

    NASA Technical Reports Server (NTRS)

    Carter, Gregory A.; Knapp, Alan K.

    2000-01-01

    A number of studies have linked responses in leaf spectral reflectance, transmittance or absorptance to physiological stress. A variety of stressors including dehydration, flooding,freezing, ozone, herbicides, competition, disease, insects and deficiencies in ectomycorrhizal development and N fertilization have been imposed on species ranging from grasses to conifers and deciduous trees. In this cases, the maximum difference in reflectance within the 400 - 850 nm wavelength range between control and stressed states occurred as a reflectance increase at wavelength near 700 nm. In studies that included transmittance and absorptance as well as reflectance, maximum differences occurred as increases and decreases, respectively, near 700 nm. This common optical response to stress could be simulated closely by varying the chlorophyll concentrations in senescent leaves of five species. The optical response to stress near 700 nm, as well as corresponding changes in reflectance that occur in the green-yellow spectrum, can be explained by the general tendency of stress to reduce leaf chlorophyll concentration.

  14. Difference Verification of Cheek Subcutaneous Fat Thickness of Male and Female Using Near Infrared Ray Spectral Characteristic Simulation of Cheek

    NASA Astrophysics Data System (ADS)

    Nishino, Satoshi; Yasuda, Shun

    The near infrared ray spectral characteristic of a person’s cheeks was simulated in this paper, and it was confirmed that the spectral characteristic of the cheeks part by the near infrared rays was detected at the subcutaneous fat under 2mm of the skin. Therefore, subcutaneous fat has a great influence at the near infrared ray spectral characteristic. Concretely, when subcutaneous fat thickness is thick, the absorbance falls down, and the spectral characteristic around 1200nm is the same for an acute angle, and becomes the spectral characteristic of the female. On the other hand, increasing the water content to simulate the increase in the thickness of the subcutaneous fat, the light absorbance rises, and the acute angle of the spectral characteristic around 1200nm disappears. The 1200nm characteristic becomes that of the male’s spectral characteristic which shows a rounded form. From the discussion above, it could be verified that a difference in the subcutaneous fat thickness is the factor of the difference in the near infrared ray spectral characteristics between that of a male and female cheek.

  15. Leaf Optical Properties in Higher Plants: Linking Spectral Characteristics with Plant Stress

    NASA Technical Reports Server (NTRS)

    Carter, Gregory A.; Knapp, Alan K.

    1999-01-01

    A number of studies have addressed responses of leaf spectral reflectance, transmittance, or absorptance to physiological stress. Stressors included dehydration, ozone, herbicides, disease, insufficient mycorrhizae and N fertilization, flooding and insects. Species included conifers, grasses, and broadleaved trees. Increased reflectance with maximum responses near 700 nm wavelength occurred in all cases. Varying the chlorophyll content in leaves or pigment extracts can simulate this effect. Thus, common optical responses to stress result from decreases in leaf chlorophyll contents or the capacity of chloroplasts to absorb light. Leaf optic can be quite sensitive to any stressor that alters soil-plant-atmosphere processes.

  16. Spectral characteristics of two-photon autofluorescence and second harmonic generation from human skin in vivo

    NASA Astrophysics Data System (ADS)

    Breunig, Hans G.; König, Karsten

    2011-03-01

    We performed multiphoton imaging of human skin and recorded in combination the complete spectral content of the signals in vivo. The spectra represent the integration of multiphoton signals over the investigated regions of the epidermis and dermis. They are used to study depth-resolved in vivo emission characteristics of main endogenous skin fluorophores like keratin, NAD(P)H, collagen and elastin. The identification of the specific fluorophores is supported by analysis of additional in vivo fluorescence lifetime imaging. Furthermore, as a potential application of spectrally selective imaging the possibility to investigate the penetration of nanoparticles from sunscreen lotion into skin in vivo is discussed.

  17. A critical review of measurements of water vapor absorption in the 840 to 1100 cm(-1) spectral region

    NASA Technical Reports Server (NTRS)

    Grant, William B.

    1987-01-01

    A set of eleven measurements of the water vapor continuum absorption in the 840 to 1100 sq cm spectral region is reviewed and compared with spectral models maintained by the Air Force Geophysics Laboratory. The measurements were made in four different ways: spectrometer with a White cell, CO2 laser with a White cell, CO2 laser with a spectrophone, and broadband radiation source over a long atmospheric path. Where possible, the data were selected at a water vapor partial pressure of ten torr buffered to 760 torr with N2 or synthetic air and a temperature of between 296 and 300 K. The intercomparison of the data leads to several observations and conclusions. First, there are four sets of laboratory data taken with nitrogen as the buffer gas which generally agree well mutually and with AFGL's HITRAN code. Second, there is one set of laboratory data that shows that using air as the buffer gas gives a few percent decrease in the water vapor continuum compared with using nitrogen as the buffer gas. Third, the atmospheric long-path measurements for water vapor partial pressure below about 12 torr are roughly grouped within 20 percent of the HITRAN values. Fourth, there are three sets of spectrophone data for water vapor in synthetic air which are significantly higher than any of the other measurements. This discrepancy is attributed to the effects of impurity gases in the cell.

  18. Spectral Moments of Collision-Induced Absorption of CO2 Pairs: The Role of the Intermolecular Potential

    NASA Technical Reports Server (NTRS)

    Gruszka, Marcin; Borysow, Aleksandra

    1994-01-01

    In this paper we examine the role of the anisotropy of the intermolecular potential in the rototranslational collision-induced absorption of the CO2 pairs. Using newly developed formulas that include the effects of anisotropy of the potential to all orders, we calculate the two lowest spectral moments gamma(prime), and alpha(prime), for four different classes of C02 pair potentials and compare the results with the experimental values. We assumed only multipolar induction in the process of forming the induced dipole, with the second-order contributions included. Using a site-site LJ and a site-site semi-ab initio intermolecular potentials we were able to reproduce the experimental values of gamma(prime), and alpha(prime) moments over entire temperature range from 230 to 330 K. Also, the role of an electrostatic interaction between two C02 molecules and its impact on the spectral moments is thoroughly investigated. An isotropic core with a point quadrupole centered at each molecule is shown to be an inadequate representation of the C02-CO2 potential. Additionally, we show the results obtained with the first- and second-order perturbation theory to be more than twice too small.

  19. Diversity in the Visible-NIR Absorption Band Characteristics of Lunar and Asteroidal Plagioclase

    NASA Technical Reports Server (NTRS)

    Hiroi, T.; Kaiden, H.; Misawa, K.; Kojima, H.; Uemoto, K.; Ohtake, M.; Arai, T.; Sasaki, S.; Takeda, H.; Nyquist, L. E.; Shih, C.-Y.

    2012-01-01

    Studying the visible and near-infrared (VNIR) spectral properties of plagioclase has been challenging because of the difficulty in obtaining good plagioclase separates from pristine planetary materials such as meteorites and returned lunar samples. After an early study indicated that the 1.25 m band position of plagioclase spectrum might be correlated with the molar percentage of anorthite (An#) [1], there have been few studies which dealt with the band center behavior. In this study, the VNIR absorption band parameters of plagioclase samples have been derived using the modified Gaussian model (MGM) [2] following a pioneering study by [3].

  20. Spectral anomalies of the light-induced drift effect caused by the velocity dependence of the collision broadening and shift of the absorption line

    NASA Astrophysics Data System (ADS)

    Parkhomenko, A. I.; Shalagin, Anatolii M.

    2013-02-01

    We have theoretically investigated the spectral features of the light-induced drift (LID) effect, arising due to the dependence of the collision broadening γ and shift Δ of the absorption line on the velocity of resonance particles, ν. It is shown that under certain conditions, account of this dependence can radically change the spectral shape of the LID signal, up to the appearance of additional zeros in the dependence of the drift velocity on the radiation frequency.

  1. Spectral anomalies of the light-induced drift effect caused by the velocity dependence of the collision broadening and shift of the absorption line

    SciTech Connect

    Parkhomenko, A I; Shalagin, Anatolii M

    2013-02-28

    We have theoretically investigated the spectral features of the light-induced drift (LID) effect, arising due to the dependence of the collision broadening {gamma} and shift {Delta} of the absorption line on the velocity of resonance particles, {nu}. It is shown that under certain conditions, account of this dependence can radically change the spectral shape of the LID signal, up to the appearance of additional zeros in the dependence of the drift velocity on the radiation frequency. (nonlinear optical phenomena)

  2. [The canopy and leaf spectral characteristics and nutrition diagnosis of tomato in greenhouse].

    PubMed

    Zhao, Rui-jiao; Li, Min-zan; Yang, Ce; Yang, Wei; Sun, Hong

    2010-11-01

    A green house experiment was conducted to research the characteristics of tomato canopy spectral reflectance and leaf spectral reflectance under different nutrition treatments, and the relationships between spectral reflectance and the water content, chlorophyll content, as well as nitrogen content were analyzed. Substrate cultivation method was used to grow the plants. The substrate was made from a mixture of peat and vermiculite. Test area was prepared for four levels of nutrition to form nutritional stress. There were 12 seedlings under each nutritional condition and a total of 48 seedlings were planted for the experiment. The canopy reflectance and leaf reflectance were measured by an ASD handheld spectroradiometer and a FT-NIR spectrometer respectively. It was observed that the trend of tomato canopy reflectance was similar to each others. There was a reflection peak at about 550 nm, and the reflectance in the visible light region was lower than that in near-infrared region. The results of analysis also indicated that under different nutrient conditions, canopy spectral reflectance characteristics of tomato took on disciplinary change. At near-infrared bands, the reflectance gradually increased with adding nutrition, while reduced at visible light bands. The leaf spectral reflectance characteristics at near-infrared bands had the similar change with the canopy reflectance. There were four sensitive wavelengths of water at near-infrared bands: about 980, 1450, 1 930, and 2 210 nm, and the results of single linear regression (SLR) and multi-linear regression (MLR) indicated that the reflectance at these sensitive wavelengths could be used to estimate the water content in tomato leaves. R2 were 0.5903 and 0.7437 respectively. NDCI as one of the most important spectral parameter was calculated by the spectral reflectance of 530 and 760 nm, and the result indicated that there existed a good correlation between NDCI and the nitrogen content, with R2 = 0

  3. Presence of terrestrial atmospheric gas absorption bands in standard extraterrestrial solar irradiance curves in the near-infrared spectral region.

    PubMed

    Gao, B C; Green, R O

    1995-09-20

    The solar irradiance curves compiled by Wehrli [Physikalisch-Meteorologisches Observatorium Publ. 615 (World Radiation Center, Davosdorf, Switzerland, 1985)] and by Neckel and Labs [Sol. Phys. 90, 205 (1984)] are widely used. These curves were obtained based on measurements of solar radiation from the ground and from aircraft platforms. Contaminations in these curves by atmospheric gaseous absorptions were inevitable. A technique for deriving the transmittance spectrum of the Sun's atmosphere from high-resolution (0.01 cm(-1)) solar occultation spectra measured above the Earth's atmosphere by the use of atmospheric trace molecule spectroscopy (ATMOS) aboard the space shuttle is described. The comparisons of the derived ATMOS solar transmittance spectrum with the two solar irradiance curves show that he curve derived by Wehrli contains many absorption features in the 2.0-2.5-µm region that are not of solar origin, whereas the curve obtained by Neckel and Labs is completely devoid of weak solar absorption features that should be there. An Earth atmospheric oxygen band at 1.268 µm and a water-vapor band near 0.94 µm are likely present in the curve obtained by Wehrli. It is shown that the solar irradiance measurement errors in some narrow spectral intervals can be as large as 20%. An improved solar irradiance spectrum is formed by the incorporation of the solar transmittance spectrum derived from the ATMOS data into the solar irradiance spectrum from Neckel and Labs. The availability of a new solar spectrum from 50 to 50 000 cm(-1) from the U.S. Air Force Phillips Laboratory is also discussed.

  4. In Situ Measurements of Aerosol Mass Concentration and Spectral Absorption at Three Location in and Around Mexico City

    NASA Astrophysics Data System (ADS)

    Chaudhry, Z.; Martins, V.; Li, Z.

    2006-12-01

    As a result of population growth and increasing industrialization, air pollution in heavily populated urban areas is one of the central environmental problems of the century. As a part of the MILAGRO (Megacity Initiative: Local and Global Research Observations) study, Nuclepore filters were collected in two size ranges (PM10 and PM2.5) at 12 hour intervals at three location in Mexico during March, 2006. Sampling stations were located at the Instituto Mexicano del Petroleo (T0), at the Rancho La Bisnago in the State of Hidalgo (T2) and along the Gulf Coast in Tampico (Tam). Each filter was analyzed for mass concentration, aerosol scattering and absorption efficiencies. Mass concentrations at T0 ranged from 47 to 179 μg/m3 for PM10 with an average concentration of 96 μg/m3, and from 20 to 93 μg/m3 for PM2.5 with an average concentration of 41 μg/m3. Mass concentrations at T2 ranged from 12 to 154 μg/m3 for PM10 with an average concentration of 51 μg/m3, and from 7 to 50 μg/m3 for PM2.5 with an average concentration of 25 μg/m3. Mass concentrations at Tam ranged from 34 to 80 μg/m3 for PM10 with an average concentration of 52 μg/m3, and from 8 to 23 μg/m3 for PM2.5 with an average concentration of 13 μg/m3. While some of the extreme values are likely linked to local emissions, regional air pollution episodes also played important roles. Each of the sampling stations experienced a unique atmospheric condition. The site at T0 was influenced by urban air pollution and dust storms, the site at T2 was significantly less affected by air pollution but more affected by regional dust storms and local dust devils while Tam was influenced by air pollution, dust storms and the natural marine environment. The spectral mass absorption efficiency was measured from 350 to 2500 nm and shows large differences between the absorption properties of soil dust, black carbon, and organic aerosols. The strong spectral differences observed can be related to differences in

  5. High-accuracy measurement of low-water-content in liquid using NIR spectral absorption method

    NASA Astrophysics Data System (ADS)

    Peng, Bao-Jin; Wan, Xu; Jin, Hong-Zhen; Zhao, Yong; Mao, He-Fa

    2005-01-01

    Water content measurement technologies are very important for quality inspection of food, medicine products, chemical products and many other industry fields. In recent years, requests for accurate low-water-content measurement in liquid are more and more exigent, and great interests have been shown from the research and experimental work. With the development and advancement of modern production and control technologies, more accurate water content technology is needed. In this paper, a novel experimental setup based on near-infrared (NIR) spectral technology and fiber-optic sensor (OFS) is presented. It has a good measurement accuracy about -/+ 0.01%, which is better, to our knowledge, than most other methods published until now. It has a high measurement resolution of 0.001% in the measurement range from zero to 0.05% for water-in-alcohol measurement, and the water-in-oil measurement is carried out as well. In addition, the advantages of this method also include pollution-free to the measured liquid, fast measurement and so on.

  6. Improved absorption and in vivo kinetic characteristics of nanoemulsions containing evodiamine–phospholipid nanocomplex

    PubMed Central

    Hu, Jiangbo; Chen, Dilong; Jiang, Rong; Tan, Qunyou; Zhu, Biyue; Zhang, Jingqing

    2014-01-01

    Purpose The purpose of this study was to assess the improved absorption and in vivo kinetic characteristics of a novel water-in-oil nanoemulsion containing evodiamine–phospholipid nanocomplex (NEEPN) when administered orally. Methods NEEPN was fabricated by loading an evodiamine–phospholipid nanocomplex into a water-in-oil nanoemulsive system. The gastrointestinal absorption of NEEPN was investigated using an in situ perfusion method. The modified in vivo kinetic characteristics of evodiamine (EDA) in NEEPN were also evaluated. Results Compared with EDA or conventional nanoemulsions containing EDA instead of evodiamine–phospholipid complex, NEEPN with its favorable in vivo kinetic characteristics clearly enhanced the gastrointestinal absorption and oral bioavailability of EDA; for example, the relative bioavailability of NEEPN to free EDA was calculated to be 630.35%, and the effective permeability of NEEPN in the colon was 8.64-fold that of EDA. Conclusion NEEPN markedly improved the oral bioavailability of EDA, which was probably due to its increased gastrointestinal absorption. NEEPN also increased efficacy and reduced adverse effects for oral delivery of EDA. Such finding demonstrates great clinical significance as an ideal drug delivery system demands high efficacy and no adverse effects. PMID:25258531

  7. Creating a Stellar Thermometer Using the Spectral Characteristics of M Giants in Andromeda

    NASA Astrophysics Data System (ADS)

    Krause, Teresa; Guhathakurta, P.; Hamren, K.; Toloba, E.; Dorman, C.; Woloshyn, L.; PHAT Collaboration

    2013-01-01

    M giant stars are the most common type of luminous evolved star and dominate the light emitted by large galaxies such as our own. These stars have much lower temperatures than the Sun, and therefore have molecular absorption bands in their spectra that makes them hard to model. The temperature of an M giant star can be estimated from photometric measurements of its color, but this method is somewhat inexact as other factors such as dust can change the color. In this project we developed another method of thermometry by examining the molecular absorption in the spectra of M giant stars. Measuring these features provides a reliable thermometer. The available data provided a large number of samples, though each contained significant noise. In order to resolve this low quality, we combined the spectra of many stars with similar temperatures into 37 template spectra. By comparing the spectral features of the original stars with those of the templates, we found a method of determining temperature based off the spectral features of M giant stars. Finding the effective surface temperature may allow us to separate the effects of dust from the other physical properties of red giant stars.

  8. Absorption characteristics of glass fiber materials at normal and oblique incidence. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Wyerman, B. R.

    1974-01-01

    The absorption characteristics of several fibrous materials of the Owens Corning 700 Fiberglas Series were measured to determine the variation in impedance as a function of incident angle of the sound wave. The results, indicate that the fibrous absorbents behave as extended reacting materials. The poor agreement between measurement and theory for sound absorption based on the parameters of flow resistance and porosity indicates that this theory does not adequately predict the acoustic behavior of fibrous materials. A much better agreement with measured results is obtained for values calculated from the bulk acoustic parameters of the material.

  9. The Effect of Heat on Structural Characteristics and Water Absorption Behavior of Agave Fibers

    NASA Astrophysics Data System (ADS)

    Saikia, Dip

    2008-04-01

    The structural characteristics and water absorptions behavior agave fibers were investigated over a range of temperature by using XRD, IR, TG and gravimetric methods. Three distinct thermal processes were observed during heating the fiber in the temperature range 310-760 K in air, oxygen and nitrogen invariably. The cellulose structures of the fibers were unaffected on heating up to 450 K. The samples showed thermal decomposition processes beyond 500 K. Fibers displayed a two-stage diffusion behavior. The structural parameters and kinetic of water absorption of the fibers at specific temperatures were analyzed.

  10. Temporal and spatial variation of canopy spectral characteristics in apple orchard

    NASA Astrophysics Data System (ADS)

    Deng, Xiaolei; Li, Minzan; Zheng, Lihua; Zhang, Yao; An, Xiaofei

    2012-11-01

    Plant nutritional status can be evaluated with remote sensing. In order to detect the temporal and spatial variation of spectral characteristics in apple orchard, the experiments were carried out. Firstly the flower/ leaf samples from 15 year-on trees and 5 year-off t rees were collected. The real time reflectance spectra of flowers/leaves from three parts (base, middle, top) of each main branch were measured by using the ASD spectrometer. And then the temporal and spatial variations of spectral characteristics were analyzed. The results showed that leaves from the top of the branch had higher reflectance than the other parts of the branch at the same time. The reflectance spectra of apple trees changed significantly at different stages. Furthermore, the reflectance spectra varied in different parts of the apple trees as well as in different trees. Accordingly the temporal curve and spatial figure were obtained and the growing informat ion can be analyzed from them.

  11. Spectral and temperature characteristics of light transmission in solutions of chemical indicators

    NASA Astrophysics Data System (ADS)

    Gavrichev, V. D.; Dmitriev, A. L.; Karacharov, G.; Nagibin, Yu. T.

    2015-12-01

    Spectral and temperature characteristics of light transmission in water solutions of chemical indicators— bromophenol blue, bromothymol blue, and cresol red—were measured in the wavelength range of 500-750 nm and the temperature range from 20 to 90°C. It was demonstrated that these solutions can be applied in optical fiber thermometers with continuous reading which are not affected by strong external electromagnetic fields.

  12. Investigation of absorption and scattering characteristics of kiwifruit tissue using a single integrating sphere system*

    PubMed Central

    Fang, Zhen-huan; Fu, Xia-ping; He, Xue-ming

    2016-01-01

    For a quantitative understanding of light interaction with fruit tissue, it is critical to obtain two fundamental parameters: the absorption coefficient and the scattering coefficient of the tissue. This study was to investigate the optical properties of kiwifruit tissue at the wavelength of 632.8 nm. The total reflectance and total transmittance of kiwifruit tissue from three parts (including the flesh part, the seed part, and the seed-base part) were measured using a single integrating sphere system. Based on the measured spectral signals, the absorption coefficient μ a and the reduced scattering coefficient μ s' of kiwifruit tissue were calculated using the inverse adding-doubling (IAD) method. Phantoms made from Intralipid 20% and India ink as well as a Biomimic solid phantom were used for system validation. The mean values of μ a and μ s' of different parts of the kiwifruit were 0.031–0.308 mm−1 and 0.120–0.946 mm−1, respectively. The results showed significant differences among the μ a and μ s' of the three parts of the kiwifruit. The results of this study confirmed the importance of studying the optical properties for a quantitative understanding of light interaction with fruit tissue. Further investigation of fruit optical properties will be extended to a broader spectral region and different kinds of fruits. PMID:27256682

  13. Static Characteristics of Absorption Chiller-Heater Supplying Cold and Hot Water Simultaneously

    NASA Astrophysics Data System (ADS)

    Inoue, Naoyuki; Irie, Tomoyoshi

    Absorption chiller-heaters which can supply both chilled water and hot water at the same time, are used for cooling and heating air conditioning systems. In this paper, we classified absorption cold and hot water generating cycles and control methods, studied these absorption cycles by cycle simulation. In economizer cycle, condensed refrigerant which heats hot water is transported to cooling cycle and used effectively for cooling chilled water, Concerning with transported condensed refrigerant, there are two methods, all condensed refrigerant or required refrigerant for cooling are transported to cooling cycle, and required refrigerant method is better for energy saving. Adding improvement of solution control to this economizer cycle, simultaneous cold and hot water supplying chiller-heaters have good characteristics of energy saving in the all region.

  14. Time-varying spectral characteristics of ENSO over the Last Millennium

    NASA Astrophysics Data System (ADS)

    Hope, Pandora; Henley, Benjamin J.; Gergis, Joelle; Brown, Josephine; Ye, Hua

    2016-10-01

    The characteristics of El Nino-Southern Oscillation (ENSO) spectra over the Last Millennium are examined to characterise variability over past centuries. Seven published palaeo-ENSO reconstructions and Nino3.4 from six Coupled Model Intercomparison Project-Phase 5 and Paleoclimate Modelling Intercomparison Project-Phase 3 (CMIP5-PMIP3) Last Millennium simulations were analysed. The corresponding Historical and pre-industrial Control CMIP5-PMIP3 simulations were also considered. The post-1850 spectrum of each modelled or reconstructed ENSO series captures aspects of the observed spectrum to varying degrees. We note that no single model or ENSO reconstruction completely reproduces the instrumental spectral characteristics. The spectral power across the 2-3 years (near biennial), 3-8 years (classical ENSO) and 8-25 years (decadal) periodicity bands was calculated in a sliding 50 year window, revealing temporal variability in the spectra. There was strong temporal variability in the spectral power of each periodicity band in observed Nino3.4 and SOI and for all reconstructions and simulations of ENSO. Significant peaks in spectral power such as observed in recent decades also occur in some of the reconstructed palaeo-ENSO (around 1600, the early 1700s and 1900) and modelled series (around the major volcanic eruptions of 1258 and 1452). While the recent increase in spectral power might be in response to enhanced greenhouse gas levels, the increase lies within the range of variability across the suite of ENSO reconstructions and simulations examined here. This study demonstrates that the analysis of a suite of ENSO reconstructions and model simulations can build a broader understanding of the time-varying nature of ENSO spectra, and how the nature of the past spectra of ENSO is to some extent dependant on the climate model or palaeo-ENSO reconstruction chosen.

  15. Local structure and optical absorption characteristic investigation on Fe doped TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhao, Tian-Xing; Feng, Ya-Juan; Huang, Jun-Heng; He, Jin-Fu; Liu, Qing-Hua; Pan, Zhi-Yun; Wu, Zi-Yu

    2015-02-01

    The local structures and optical absorption characteristics of Fe doped TiO2 nanoparticles synthesized by the sol-gel method were characterized by X-ray diffraction (XRD), X-ray absorption fine structure spectroscopy (XAFS) and ultraviolet-visible absorption spectroscopy (UV-Vis). XRD patterns show that all Fe-doped TiO2 samples have the characteristic anatase structure. Accurate Fe and Ti K-edge EXAFS analysis further reveal that all Fe atoms replace Ti atoms in the anatase lattice. The analysis of UV-Vis data shows a red shift to the visible range. According to the above results, we claim that substitutional Fe atoms lead to the formation of structural defects and new intermediate energy levels appear, narrowing the band gap and extending the optical absorption edge towards the visible region. Supported by National Basic Research Program of China (2012CB825801), Science Fund for Creative Research Groups of NSFC (11321503), National Natural Science Foundation of China (11321503, 11179004) and Guangdong Natural Science Foundation (S2011040003985)

  16. Absolute bioavailability and absorption characteristics of divalproex sodium extended-release tablets in healthy volunteers.

    PubMed

    Dutta, Sandeep; Reed, Ronald C; Cavanaugh, John H

    2004-07-01

    Conventional delayed-release, enteric-coated divalproex sodium tablet has an absolute bioavailability of approximately 100%. Divalproex sodium extended-release (ER) tablet is a novel formulation of valproic acid (VPA) designed to release the drug slowly at a constant zero-order rate. The purpose of this study was to evaluate the absolute bioavailability and absorption characteristics of divalproex ER. Healthy adult volunteers (n = 16) received divalproex ER and intravenous VPA in crossover fashion. Absolute bioavailability was calculated as the divalproex ER/intravenous VPA ratio of area under the curve extrapolated to infinity. The duration and rate of absorption of VPA from divalproex ER tablets were determined by deconvolution analysis. The geometric mean absolute bioavailability of divalproex ER was 0.896. The mean (coefficient of variation) duration of drug absorption from divalproex ER was 21.8 (17%) hours, and the zero-order absorption rate was 21.6 (24%) mg/h for a 500-mg tablet. Divalproex ER has a lower absolute bioavailability than conventional divalproex tablets but exhibits good extended-release characteristics without any dose dumping.

  17. The spectral variability of the GHZ-Peaked spectrum radio source PKS 1718-649 and a comparison of absorption models

    SciTech Connect

    Tingay, S. J.; Macquart, J.-P.; Wayth, R. B.; Trott, C. M.; Emrich, D.; Collier, J. D.; Wong, G. F.; Rees, G.; Stevens, J.; Carretti, E.; Callingham, J. R.; Gaensler, B. M.; McKinley, B.; Briggs, F.; Bernardi, G.; Bowman, J. D.; Cappallo, R. J.; Corey, B. E.; Deshpande, A. A.; Goeke, R.; and others

    2015-02-01

    Using the new wideband capabilities of the ATCA, we obtain spectra for PKS 1718-649, a well-known gigahertz-peaked spectrum radio source. The observations, between approximately 1 and 10 GHz over 3 epochs spanning approximately 21 months, reveal variability both above the spectral peak at ∼3 GHz and below the peak. The combination of the low- and high-frequency variability cannot be easily explained using a single absorption mechanism, such as free–free absorption or synchrotron self-absorption. We find that the PKS 1718-649 spectrum and its variability are best explained by variations in the free–free optical depth on our line of sight to the radio source at low frequencies (below the spectral peak) and the adiabatic expansion of the radio source itself at high frequencies (above the spectral peak). The optical depth variations are found to be plausible when X-ray continuum absorption variability seen in samples of active galactic nuclei is considered. We find that the cause of the peaked spectrum in PKS 1718-649 is most likely due to free–free absorption. In agreement with previous studies, we find that the spectrum at each epoch of observation is best fit by a free–free absorption model characterized by a power-law distribution of free–free absorbing clouds. This agreement is extended to frequencies below the 1 GHz lower limit of the ATCA by considering new observations with Parkes at 725 MHz and 199 MHz observations with the newly operational Murchison Widefield Array. These lower frequency observations argue against families of absorption models (both free–free and synchrotron self-absorption) that are based on simple homogenous structures.

  18. Characteristic features of optical absorption for Gd2O3 and NiO nanoparticles

    NASA Astrophysics Data System (ADS)

    Zatsepin, A. F.; Kuznetsova, Yu. A.; Rychkov, V. N.; Sokolov, V. I.

    2017-03-01

    The technical approach to determination of the structural and optical parameters of oxides with reduced dimensionality based on optical absorption measurements is described by example of gadolinium and nickel oxides. It was established that the temperature behavior of fundamental absorption edge for oxide nanoparticles is similar with the bulk materials with crystal structure. At the same time, the energy characteristics (band gap and effective phonon energies) for low-dimensional oxides are found to be significantly different from their bulk counterparts. The presented methodological method to obtain of qualitative and quantitative correlations of structural and optical characteristics provides novel reliable knowledge of nanoscaled 3d and 4f-metal oxide materials that is useful for development of their practical applications.

  19. Relationship between anaerobic digestion of biodegradable solid waste and spectral characteristics of the derived liquid digestate.

    PubMed

    Zheng, Wei; Lü, Fan; Phoungthong, Khamphe; He, Pinjing

    2014-06-01

    The evolution of spectral properties during anaerobic digestion (AD) of 29 types of biodegradable solid waste was investigated to determine if spectral characteristics could be used for assessment of biological stabilization during AD. Biochemical methane potential tests were conducted and spectral indicators (including the ratio of ultraviolet-visible absorbance at 254nm to dissolved organic carbon concentration (SUVA254), the ratio of ultraviolet-visible absorbance measured at 465nm and 665nm (E4/E6), and the abundance of fluorescence peaks) were measured at different AD phases. Inter-relationship between organic degradation and spectral indicators were analyzed by principle component analysis. The results shows that from methane production phase to the end of methane production phase, SUVA254 increased by 0.16-10.93 times, the abundance of fulvic acid-like compounds fluorescence peak increased by 0.01-0.54 times, the abundance of tyrosine fluorescence peak decreased by 0.03-0.64 times. Therefore, these indicators were useful to judge the course of mixed waste digestion.

  20. The spectral and image characteristics of vegetation in the presence of heavy metals in southern China

    NASA Astrophysics Data System (ADS)

    Yang, Fengjie; Li, Na; Zhou, Guangzhu; Song, Cuiyu; Li, Qingting

    2008-10-01

    The principle and methodology to monitor the heavy metal pollution using hyperspectral remote sensing are put forward based on the study areas, copper mine in De-Xing and tin ore in GeJiu, and selected plants, China Sumac, Sweet Wormwood Herb, and Nephrolepis Cordifolia. In the areas defined by former information, vegetation samples and corresponding spectral data are gathered. The samples are then analyzed in chemical lab, telling us to what extent the vegetation is polluted by heavy metal. The spectral curves are also processed, and some spectral parameters are extracted, such as reflectance, blue-shift extent, position of red-edge, vegetation index, band-depth. Then the regression model from spectral characteristic parameters to heavy metal content can be built. At last, the conclusion can be attained. In copper mine area, the vegetation is polluted by seven kinds of heavy metals. As far as China Sumac, the reflectance of red band correlates the Pb content well. The reflectance of all study plants at 1240nm and 725/675(nm) correlates heavy metal content well. The reflectance of 450nm, 550nm, 670nm, 760nm, and 1240nm can be liner combined as a parameter to monitor heavy metal pollution. Besides, some band-depth can also be combined as parameters using "Enter". In a word, as an advanced technique to monitor environmental pollution, hyperspectral remote sensing has wild perspective.

  1. Spectral characteristics of Rossby waves in the Northwestern Pacific based on satellite altimetry

    NASA Astrophysics Data System (ADS)

    Belonenko, T. V.; Kubrjakov, A. A.; Stanichny, S. V.

    2016-12-01

    Using satellite altimetry measurement data for 1993-2013, we study the spectral characteristics of Rossby waves in the Northwestern Pacific (25°-50° N, 140°-180° E). For each latitude degree, we draw integral plots of spectral power density calculated with a two-dimensional Fourier transform (2D-FFT). We compare the dispersion equations of Rossby waves calculated from the WKB-approximation and an approximation of a two-layer ocean model with the empirical velocities determined by the slope of isopleths by the Radon method; also, we compare the dispersion equations with the spectral distributions of level variations. It is shown that the main energy of Rossby waves in the Northwestern Pacific corresponds to the first baroclinic mode. At almost all latitudes, there is good agreement between the empirical phase velocities calculated by isopleths by the Radon method and the theoretical values; also, the spectral peaks correspond to graphs of the dispersion equations for the first baroclinic mode Rossby waves, except for the Kuroshio region, where some peaks correspond to the second mode.

  2. Experimental recovery of intrinsic fluorescence and fluorophore concentration in the presence of hemoglobin: spectral effect of scattering and absorption on fluorescence

    NASA Astrophysics Data System (ADS)

    Du Le, Vinh Nguyen; Patterson, Michael S.; Farrell, Thomas J.; Hayward, Joseph E.; Fang, Qiyin

    2015-12-01

    The ability to recover the intrinsic fluorescence of biological fluorophores is crucial to accurately identify the fluorophores and quantify their concentrations in the media. Although some studies have successfully retrieved the fluorescence spectral shape of known fluorophores, the techniques usually came with heavy computation costs and did not apply for strongly absorptive media, and the intrinsic fluorescence intensity and fluorophore concentration were not recovered. In this communication, an experimental approach was presented to recover intrinsic fluorescence and concentration of fluorescein in the presence of hemoglobin (Hb). The results indicated that the method was efficient in recovering the intrinsic fluorescence peak and fluorophore concentration with an error of 3% and 10%, respectively. The results also suggested that chromophores with irregular absorption spectra (e.g., Hb) have more profound effects on fluorescence spectral shape than chromophores with monotonic absorption and scattering spectra (e.g., black India ink and polystyrene microspheres).

  3. Experimental recovery of intrinsic fluorescence and fluorophore concentration in the presence of hemoglobin: spectral effect of scattering and absorption on fluorescence.

    PubMed

    Du Le, Vinh Nguyen; Patterson, Michael S; Farrell, Thomas J; Hayward, Joseph E; Fang, Qiyin

    2015-01-01

    The ability to recover the intrinsic fluorescence of biological fluorophores is crucial to accurately identify the fluorophores and quantify their concentrations in the media. Although some studies have successfully retrieved the fluorescence spectral shape of known fluorophores, the techniques usually came with heavy computation costs and did not apply for strongly absorptive media, and the intrinsic fluorescence intensity and fluorophore concentration were not recovered. In this communication, an experimental approach was presented to recover intrinsic fluorescence and concentration of fluorescein in the presence of hemoglobin (Hb). The results indicated that the method was efficient in recovering the intrinsic fluorescence peak and fluorophore concentration with an error of 3% and 10%, respectively. The results also suggested that chromophores with irregular absorption spectra (e.g., Hb) have more profound effects on fluorescence spectral shape than chromophores with monotonic absorption and scattering spectra (e.g., black India ink and polystyrene microspheres).

  4. Absorption fever characteristics due to percutaneous renal biopsy-related hematoma.

    PubMed

    Hu, Tingyang; Liu, Qingquan; Xu, Qin; Liu, Hui; Feng, Yan; Qiu, Wenhui; Huang, Fei; Lv, Yongman

    2016-09-01

    This study aims to describe the unique characteristics of absorption fever in patients with a hematoma after percutaneous renal biopsy (PRB) and distinguish it from secondary infection of hematoma.We retrospectively studied 2639 percutaneous renal biopsies of native kidneys. We compared the clinical characteristics between 2 groups: complication group (gross hematuria and/or perirenal hematoma) and no complication group. The axillary temperature of patients with a hematoma who presented with fever was measured at 06:00, 10:00, 14:00, and 18:00. The onset and duration of fever and the highest body temperature were recorded. Thereafter, we described the time distribution of absorption fever and obtained the curve of fever pattern.Of 2639 patients, PRB complications were observed in 154 (5.8%) patients. Perirenal hematoma was the most common complication, which occurred in 118 (4.5%) of biopsies, including 74 small hematoma cases (thickness ≤3 cm) and 44 large hematoma cases (thickness >3 cm). Major complications were observed in only 6 (0.2%) cases resulting from a large hematoma. Of 118 patients with a perirenal hematoma, absorption fever was observed in 48 cases. Furthermore, large hematomas had a 5.23-fold higher risk for absorption fever than the small ones.Blood pressure, renal insufficiency, and prothrombin time could be risk factors for complications. Fever is common in patients with hematoma because of renal biopsy and is usually noninfectious. Evaluation of patients with post-biopsy fever is necessary to identify any obvious infection sources. If no focus is identified, empiric antibiotic therapy should not be initiated nor should prophylactic antibiotics be extended for prolonged durations. Absorption fevers will resolve in time without specific therapeutic interventions.

  5. Variation of Spectral Characteristics of Coelenteramide-Containing Fluorescent Protein from Obelia Longissima Exposed to Dimethyl Sulfoxide

    NASA Astrophysics Data System (ADS)

    Petrova, A. S.; Alieva, R. R.; Belogurova, N. V.; Tirranen, L. S.; Kudryasheva, N. S.

    2016-08-01

    Effect of dimethyl sulfoxide (DMSO), a widespread biomedical agent, on spectral-luminescent characteristics of coelenteramide-containing fluorescent protein - discharged obelin - is investigated. Contributions of violet and blue-green spectral components to fluorescence of discharged obelin are elucidated and characterized at different photoexcitation energies. Dependences of these contributions on the DMSO concentration are presented. Spectral changes are related to the destructive effect of DMSO on fluorescent protein and decreasing efficiency of proton transfer to electronically excited states of fluorophore.

  6. Spectral Absorption of Solar Radiation in Cloudy Atmospheres: A 20 cm1 Model.

    NASA Astrophysics Data System (ADS)

    Davies, Roger; Ridgway, William L.; Kim, Kyung-Eak

    1984-07-01

    The spectral of solar radiation in typical water clouds is determined using a radiative transfer model based on LOWTRAN transmission functions at a 20 cm1 resolution and Monte Carlo simulations of photon pathlength distributions. Relative absorption by the vapor and droplets within each cloud is obtained, and both plane-parallel and horizontally finite clouds are considered.Results indicate slightly lower absorption than found previously, with boundary layer clouds typically absorbing 9% of the extraterrestrial insolation for overhead sun. Cloud absorption depends strongly on the presence of water vapor above the cloud top and solar zenith angle, moderately on cloud aspect ratio, and (provided the cloud is neither tenuous nor broken) weakly on cloud type and thickness. The droplets, not the vapor, are shown to be the dominant absorbers within the cloud, except in the absence of water vapor above the cloud top, in which case the vapor and droplets make similar contributions to the low cloud absorption. For many of the cases modeled, the sum of the cloud and atmospheric absorption remained invariant, allowing the net solar radiation budget at the surface to be deduced from broadband satellite measurements of albedo. An explanation for this behavior is found in the analysis of the spectral absorption by the different components.

  7. Spectral characteristics of tramadol in different solvents and β-cyclodextrin

    NASA Astrophysics Data System (ADS)

    Anton Smith, A.; Manavalan, R.; Kannan, K.; Rajendiran, N.

    2009-10-01

    Effect of solvents and β-cyclodextrin on the absorption and fluorescence spectra of tramadol drug has been investigated and compared with anisole. The solid inclusion complex of tramadol with β-CD is investigated by FT-IR, 1H NMR, scanning electron microscope (SEM), DSC and semiempirical methods. The thermodynamic parameter (Δ G) of inclusion process is determined. A solvent study shows (i) the spectral behaviour of both tramadol and anisole molecules is similar to each other and (ii) the cyclohexanol group in tramadol is not effectively conjugated with anisole group. However, in β-CD, due to space restriction of the CD cavity, a weak interaction is present between the above groups in tramadol. β-Cyclodextrin studies show that tramadol forms 1:2 inclusion complex with β-CD. A mechanism is proposed for the inclusion process.

  8. STATISTICAL STUDY of HARD X-RAY SPECTRAL CHARACTERISTICS OF SOLAR FLARES

    NASA Astrophysics Data System (ADS)

    Alaoui, M.; Krucker, S.; Saint-Hilaire, P.; Lin, R. P.

    2009-12-01

    We investigate the spectral characteristics of 75 solar flares at the hard X-ray peak time observed by RHESSI (Ramaty High Energy Solar Spectroscopic Imager) in the energy range 12-150keV. At energies above 40keV, the Hard X-ray emission is mostly produced by bremsstrahlung of suprathermal electrons as they interact with the ambient plasma in the chromosphere. The observed photon spectra therefore provide diagnostics of electron acceleration processes in Solar flares. We will present statistical results of spectral fitting using two models: a broken power law plus a thermal component which is a direct fit of the photon spectrum and a thick target model plus a thermal component which is a fit of the photon spectra with assumptions on the electrons emitting bremsstrahlung in the thick target approximation.

  9. [Spectral characteristics of decomposition of incorporated straw in compound polluted arid loess].

    PubMed

    Fan, Chun-Hui; Zhang, Ying-Chao; Xu, Ji-Ting; Wang, Jia-Hong

    2014-04-01

    The original loess from western China was used as soil sample, the spectral methods of scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), elemental analysis, Fourier transform infrared spectroscopy (FT-IR) and 13C nuclear magnetic resonance (13C NMR) were used to investigate the characteristics of decomposed straw and formed humic acids in compound polluted arid loess. The SEM micrographs show the variation from dense to decomposed surface, and finally to damaged structure, and the EDS data reveal the phenomenon of element transfer. The newly-formed humic acids are of low aromaticity, helpful for increasing the activity of organic matters in loess. The FTIR spectra in the whole process are similar, indicating the complexity of transformation dynamics of humic acids. The molecular structure of humic acids becomes simpler, shown from 13C NMR spectra. The spectral methods are useful for humic acids identification in loess region in straw incorporation process.

  10. Spectral and lasing characteristics of 1% Ho:YAG ceramics under intracavity pumping

    SciTech Connect

    Bagayev, S N; Vatnik, S M; Vedin, I A; Kurbatov, P F; Osipov, V V; Shitov, V A; Maksimov, R N; Luk'yashin, K E; Pavlyuk, A A

    2015-01-31

    High-transparency 1% Ho:YAG ceramics with the transmission coefficient of 82% in the IR range at the sample thickness of 1 mm are synthesised from a mixture of the Ho:Y{sub 2}O{sub 3} and Al{sub 2}O{sub 3} nanopowders obtained by the laser method. Results of investigations of spectral and lasing characteristics of 1 % Ho:YAG ceramics under intracavity pumping by radiation of a 5% Tm:KLuW disk element are presented. Based on spectral intensity analysis of generation in the 1.8 – 2.1 mm range and on cavity parameters, the estimated lasing slope efficiency for 1% Ho:YAG ceramics is about 40%. (lasers)

  11. Spectral and Temporal Characteristics of LS PEG and TW PIC Using XMM-NEWTON Data

    NASA Astrophysics Data System (ADS)

    Talebpour Sheshvan, Nasrin; Balman, Solen

    2016-07-01

    We report the analysis of archival XMM-Newton X-ray observations of LS Peg and TW Pic. These are Cataclysmic Variables (CVs) suggested as Intermediate Polars (IPs), but unconfirmed in the X-rays. Identification of several periodic oscillations in the optical band hint them as IPs. Unlike the previous spectral analysis on the EPIC-MOS data by fitting a hot optically thin plasma emission model with a single temperature for LS Peg, we simultaneously fitted all EPIC spectrum (pn+MOS) using a composite model of absorption for interstellar medium (tbabs) with two different partial covering absorbers (pcfabs) including a multitemperature plasma emission component (cevmkl) and a Gaussian emission line at 6.4 keV. TW Pic is best modeled in a similar manner with only one partial covering absorber and an extra Gaussian emission line at 6.7 keV. LS Peg has a maximum plasma temperature of ˜14.8 keV with an X-ray luminosity of ˜5×10^{32}ergs ^{-1} translating to an accretion rate of ˜1.27×10^{-10}M _{⊙}yr ^{-1}. TW Pic shows kT _{max} ˜38.7 keV with an X-ray luminosity around 1.6×10^{33}ergs ^{-1} at an accretion rate of ˜4×10^{-10}M _{⊙}yr ^{-1}. In addition, we discuss orbital modulations in the X-rays and power spectral analysis, and derive the EPIC pn spectra for orbital minimum and orbital maximum phases for both sources. We elaborate on the geometry of accretion and absorption in the X-ray emitting regions of both sources with articulation on the magnetic nature.

  12. Maxillary Arch Dimensions and Spectral Characteristics of Children with Cleft Lip and Palate Who Produce Middorsum Palatal Stops

    ERIC Educational Resources Information Center

    Zajac, David J.; Cevidanes, Lucia; Shah, Sonam; Haley, Katarina L.

    2012-01-01

    Purpose: The purpose of this study was twofold: (a) to determine maxillary arch dimensions of children with repaired cleft lip and palate (CLP) who produced middorsum palatal stops and (b) to describe some spectral characteristics of middorsum palatal stops. Method: Maxillary arch width, length, and height dimensions and first spectral moments of…

  13. Use of spectral characteristics of DSLR cameras with Bayer filter sensors

    NASA Astrophysics Data System (ADS)

    Cheremkhin, P. A.; Lesnichii, V. V.; Petrov, N. V.

    2014-09-01

    The expensive photosensors of scientific cameras are commonly used in the wide variety of research fields. However, photosensors that are implemented in DSLR cameras are seen to be an appropriate substitution in order to decrease price/quality ratio or even receive additional features. In this article different scientific applications of DSLR cameras' photosensors with Bayer filter as well as calibration methods of its spectral characteristics are discussed. The approach, based on determination of latter and usage of its features, is shown to increase SNR of the color reconstructed images in digital holography.

  14. Discharge characteristics of dielectric materials examined in mono-, dual-, and spectral energy electron charging environments

    NASA Technical Reports Server (NTRS)

    Coakley, P.; Treadway, M.; Wild, N.; Kitterer, B.

    1985-01-01

    The effects of midenergy electrons on the charge and discharge characteristics of spacecraft dielectric materials and the data base from which basic discharge models can be formulated is expanded. Thin dielectric materials were exposed to low, mid combined low and mid, and spectral energy electron environments. Three important results are presented: (1) it determined electron environments that lead to dielectric discharges at potentials less negative than -5 kV; (2) two types of discharges were identified that dominate the kinds of discharges seen; and (3) it is shown that, for the thin dielectric materials tested, the worst-case discharges observed in the various environments are similar.

  15. Spectral characteristics of the microfiber MZ interferometer with a knot resonator

    NASA Astrophysics Data System (ADS)

    Liao, Yipeng; Wang, Jing; Wang, Shanshan; Yang, Hongjuan; Wang, Xin

    2017-04-01

    This paper investigates the transmission spectral characteristics of microfiber MZ interferometer with a knot resonator (MZIKR). The MZIKR exhibits a combined effect of resonance and interference in its transmission spectra. By adjusting the coupling coefficients to convert the relative strength of resonance and interference, the transmission spectra show various shapes, mainly reflected in the direction of fringes. The obtained upward fringe exhibits an extinction ratio of 17 dB and a FWHM of 0.3 nm. The tunable transmission spectrum demonstrated here may have great potential for narrow-band filtering, and the coexisting resonance and interference effect also allows the MZIKR to perform dual-parameters sensing.

  16. Spectral and spatial characteristics of third-harmonic generation in conical light beams

    SciTech Connect

    Peet, V.E.; Shchemeljov, S.V.

    2003-01-01

    Generation of resonance-enhanced third harmonic in Bessel and other conical beams is analyzed from a simple picture, where the fundamental light field is decomposed into elementary configurations of crossed plain-wave sub-beams. We show that the overall harmonic output can be derived as a superposition of all partial harmonic components driven by elementary configurations of the fundamental field. Good agreement with experimental observations has been obtained in simulation of spectral and spatial characteristics of the generated third harmonic. Some peculiarities of harmonic generation in conical light fields are discussed.

  17. Spectral characteristics of steady-state Lévy flights in confinement potential profiles

    NASA Astrophysics Data System (ADS)

    Kharcheva, A. A.; Dubkov, A. A.; Dybiec, B.; Spagnolo, B.; Valenti, D.

    2016-05-01

    The steady-state correlation characteristics of superdiffusion in the form of Lévy flights in one-dimensional confinement potential profiles are investigated both theoretically and numerically. Specifically, for Cauchy stable noise we calculate the steady-state probability density function for an infinitely deep rectangular potential well and for a symmetric steep potential well of the type U(x)\\propto {{x}2m} . For these potential profiles and arbitrary Lévy index α, we obtain the asymptotic expression of the spectral power density.

  18. CONTROL OF LASER RADIATION PARAMETERS: New method to control the shape of spectral characteristics of Bragg gratings in electrooptical materials

    NASA Astrophysics Data System (ADS)

    Shamrai, A. V.; Kozlov, A. S.; Il'ichev, I. V.; Petrov, Mikhail P.

    2005-08-01

    A new method is proposed to control the shape of spectral characteristics of Bragg gratings, which is based on the introduction of electrically controlled shifts of the average refractive index. The shape of the spectral characteristics of Bragg gratings with a complex step structure of the spatial distribution of the average refractive index is calculated. The operative electric control of their shape in a channel optical LiNbO3 crystal waveguide is experimentally demonstrated.

  19. Spectral characteristics of a laser emitter designed for pumping and detecting a reference quantum transition of a caesium frequency standard

    SciTech Connect

    Ivanov, A V; Kurnosov, V D; Kurnosov, K V; Romantsevich, V I; Chernov, Roman V; Marmalyuk, Aleksandr A; Volkov, N A; Zholnerov, V S

    2011-08-31

    Experimental and calculated spectral characteristics of a diode laser with a Bragg grating soldered on a thermoelectric cooler are presented. A model of the laser is developed, which takes into account the pressure arising after soldering the Bragg grating on the thermoelectric cooler, as well as temperature and dispersion. Theoretical and experimental spectral characteristics of the laser are compared and their satisfactory agreement is shown. (control of radiation parameters)

  20. Spectral aspects of the determination of Si in organic and aqueous solutions using high-resolution continuum source or line source flame atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Kowalewska, Zofia; Pilarczyk, Janusz; Gościniak, Łukasz

    2016-06-01

    High-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS) was applied to reveal and investigate spectral interference in the determination of Si. An intensive structured background was observed in the analysis of both aqueous and xylene solutions containing S compounds. This background was attributed to absorption by the CS molecule formed in the N2O-C2H2 flame. The lines of the CS spectrum at least partially overlap all five of the most sensitive Si lines investigated. The 251.611 nm Si line was demonstrated to be the most advantageous. The intensity of the structured background caused by the CS molecule significantly depends on the chemical form of S in the solution and is the highest for the most-volatile CS2. The presence of O atoms in an initial S molecule can diminish the formation of CS. To overcome this S effect, various modes of baseline fitting and background correction were evaluated, including iterative background correction (IBC) and utilization of correction pixels (WRC). These modes were used either independently or in conjunction with least squares background correction (LSBC). The IBC + LSBC mode can correct the extremely strong interference caused by CS2 at an S concentration of 5% w:w in the investigated solution. However, the efficiency of this mode depends on the similarity of the processed spectra and the correction spectra in terms of intensity and in additional effects, such as a sloping baseline. In the vicinity of the Si line, three lines of V were recorded. These lines are well-separated in the HR-CS FAAS spectrum, but they could be a potential source of overcorrection when using line source flame atomic absorption spectrometry (LS FAAS). The expected signal for the 251.625 nm Fe line was not registered at 200 mg L- 1 Fe concentration in the solution, probably due to the diminished population of Fe atoms in the high-temperature flame used. The observations made using HR-CS FAAS helped to establish a "safe" level

  1. Influence of drug physicochemical characteristics on in vitro transdermal absorption of hydrophobic drug nanosuspensions.

    PubMed

    Shen, Cheng-Ying; Li, Rui-Sheng; Shen, Bao-de; Shen, Gang; Wang, Li-Qiang; Zheng, Juan; Li, Xiao-Rong; Min, Hong-Yan; Han, Jin; Yuan, Hai-Long

    2015-01-01

    The purpose of this paper was to study the influence of drug physicochemical characteristics on in vitro transdermal absorption of hydrophobic drug nanosuspensions. Four drug nanosuspensions were produced by high-pressure homogenization technique, which were the same in stabilizer and similar in particle size. Differential scanning calorimetry and powder X-ray diffraction analysis showed that the crystalline state of the nanocrystals did not change. In vitro permeation study demonstrated that the drug nanosuspensions have a higher rate of permeation that ranged from 1.69- to 3.74-fold compared to drug microsuspensions. Correlation analysis between drug physicochemical properties and Jss revealed that log P and pKa were factors that influenced the in vitro transdermal absorption of hydrophobic drug nanosuspensions, and drugs with a log P value around 3 and a higher pKa value (when pKa < pH+2) would gain higher Jss in this paper.

  2. Study on the Partial Load Characteristics of Double-Effect Absorption Systems

    NASA Astrophysics Data System (ADS)

    Kawakami, Ryuichiro; Fukuchi, Toru; Kaita, Yoshio

    Simulation analysis was carried out to study the partial load characteristics of three different types of double-effect LiBr-water absorption cycle, namely series flow, parallel flow and reverse flow. A computer program was developed for this study to simulate the behavior of the absorption cycles equipped with flow rate control of absorbent, cooling water and chilling water on partial load. The effects of the flow rate control on the coefficient of performance (COP), the maximum temperature and maximum pressure were studied. The results show that not only flow rate control of absorbent is essential for high COP on the partial load, but also flow rate control of cooling water and chilling water is recommendable to save the power of pumping.

  3. Synthesis of Nanocrystalline SnO2 Microspheres and Their Hydrogen Absorption Characteristics.

    PubMed

    Wang, Zhiyuan; Wang, Fengping; Li, Mingyan; Iqbal, M Zubair; Javed, Qurat-Ul-Ain; Lu, Yanzhen; Xu, Mei; Li, Quanshui

    2015-02-01

    SnO2 solid microspheres and multilayered nanocrystalline SnO2 hollow microspheres (MHS-SnO2) have been successfully synthesized in the solvothermal environment by using different solvents. The morphology, structure and composition of the as-prepared products are characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) with selected area electron diffraction (SAED) and X-ray diffraction (XRD). The growth mechanism of SnO2 solid microspheres and MHS-SnO2 are proposed and attributed to the viscosity of solvent. The studies on hydrogen absorption characteristics of SnO2 solid structure and MHS-SnO2 show an absorption capability of 0.50 wt.% and 0.92 wt.%, respectively.

  4. Moisture absorption and bakeout characteristics of rigid-flexible multilayer printed wiring boards

    SciTech Connect

    Lula, J.W.

    1991-01-01

    Moisture absorption and bakeout characteristics of Allied-Signal Inc., Kansas City Division (KCD) rigid-flexible printed wiring boards were determined. It was found that test specimens had absorbed 0.95 weight percent moisture when equilibrated to a 50 percent RH, 25{degree}C environment. Heating those equilibrated specimens in a 120{degree}C static air oven removed 92 percent of this absorbed moisture in 24 h. Heating the samples in a 80{degree}C static air oven removed only 64 percent of the absorbed moisture at the end of 24 h. A 120{degree}C vacuum bake removed moisture at essentially the same rate with parylene slowed the absorption rate by approximately 50 percent but did not appreciably affect the equilibrium moisture content or the drying rate.

  5. Waveform spectral analysis to determining the CTBTO's seismic stations noise characteristics in Indonesia

    NASA Astrophysics Data System (ADS)

    Wibowo, B. A.; Heryandoko, N.; Rohadi, S.

    2016-05-01

    All we analysed recording waveform of six seismograph stations which is part of CTBTO's seismic network in Indonesia. The analysis using the spectral analysis method conducted to determine the characteristics response of each seismographic station. We analysed background noise level of sites using Power Spectral Density (PSD) and Probability of Density Function (PDF). The result of spectral analysis indicates that PSI station (Parapat, Sumatera) has the lowest background noise level, so it has highest Signal to Noise Ratio (SNR). This station has best recording of nuclear explosion and earthquake event compare to recording of other station. This good quality of recording signal because the seismometer located on the representative bedrock and the site good protected from the ambient or environmental noise. Otherwise, LEM station (Lembang, Bandung) has the highest background noise level and has lowest SNR. LEM station located near the Tangkuban Perahu Mountain that one of active volcano in Bandung. Activity of the volcano may create disturbance noise to the recording signal in Lembang station (LEM). The significance noise also may because of human activity around this site.

  6. Spectral characteristics of geomagnetic field variations at low and equatorial latitudes

    USGS Publications Warehouse

    Campbell, W.H.

    1977-01-01

    Geomagnetic field spectra from eight standard observations at geomagnetic latitudes below 30?? were studied to determine the field characteristics unique to the equatorial region. Emphasis was placed upon those variations having periods between 5 min and 4 hr for a selection of magnetically quiet, average, and active days in 1965. The power spectral density at the equator was about ten times that the near 30?? latitude. The initial manifestation of the equatorial electrojet as evidenced by the east-west alignment of the horizontal field or the change in vertical amplitudes occurred below about 20?? latitude. Induced current effects upon the vertical component from which the Earth conductivity might be inferred could best be obtained at times and latitudes unaffected by the electrojet current. Values of about 1.6 ?? 103 mhos/m for an effective skin depth of 500-600 km were determined. The spectral amplitudes increased linearly with geomagnetic activity index, Ap. The spectral slope had a similar behavior at all latitudes. The slope changed systematically with Ap-index and showed a diurnal variation, centered on local noon, that changed form with geomagnetic activity.

  7. Spectral reflectance characteristics of soils in northeastern Brazil as influenced by salinity levels.

    PubMed

    Pessoa, Luiz Guilherme Medeiros; Freire, Maria Betânia Galvão Dos Santos; Wilcox, Bradford Paul; Green, Colleen Heather Machado; De Araújo, Rômulo José Tolêdo; De Araújo Filho, José Coelho

    2016-11-01

    In northeastern Brazil, large swaths of once-productive soils have been severely degraded by soil salinization, but the true extent of the damage has not been assessed. Emerging remote sensing technology based on hyperspectral analysis offers one possibility for large-scale assessment, but it has been unclear to what extent the spectral properties of soils are related to salinity characteristics. The purpose of this study was to characterize the spectral properties of degraded (saline) and non-degraded agricultural soils in northeastern Brazil and determine the extent to which these properties correspond to soil salinity. We took soil samples from 78 locations within a 45,000-km(2) site in Pernambuco State. We used cluster analysis to group the soil samples on the basis of similarities in salinity and sodicity levels, and then obtained spectral data for each group. The physical properties analysis indicated a predominance of the coarse sand fraction in almost all the soil groups, and total porosity was similar for all the groups. The chemical analysis revealed different levels of degradation among the groups, ranging from non-degraded to strongly degraded conditions, as defined by the degree of salinity and sodicity. The soil properties showing the highest correlation with spectral reflectance were the exchangeable sodium percentage followed by fine sand. Differences in the reflectance curves for the various soil groups were relatively small and were not significant. These results suggest that, where soil crusts are not present, significant challenges remain for using hyperspectral remote sensing to assess soil salinity in northeastern Brazil.

  8. Spectral and angular characteristics of dielectric resonator metasurface at optical frequencies

    SciTech Connect

    Zou, Longfang; López-García, Martin; Oulton, Ruth; Klemm, Maciej; Withayachumnankul, Withawat; Fumeaux, Christophe; Shah, Charan M.; Mitchell, Arnan; Bhaskaran, Madhu; Sriram, Sharath

    2014-11-10

    The capability of manipulating light at subwavelength scale has fostered the applications of flat metasurfaces in various fields. Compared to metallic structure, metasurfaces made of high permittivity low-loss dielectric resonators hold the promise of high efficiency by avoiding high conductive losses of metals at optical frequencies. This letter investigates the spectral and angular characteristics of a dielectric resonator metasurface composed of periodic sub-arrays of resonators with a linearly varying phase response. The far-field response of the metasurface can be decomposed into the response of a single grating element (sub-array) and the grating arrangement response. The analysis also reveals that coupling between resonators has a non-negligible impact on the angular response. Over a wide wavelength range, the simulated and measured angular characteristics of the metasurface provide a definite illustration of how different grating diffraction orders can be selectively suppressed or enhanced through antenna sub-array design.

  9. EMG spectral characteristics of masticatory muscles and upper trapezius during maximum voluntary teeth clenching.

    PubMed

    Lodetti, Gianluigi; Mapelli, Andrea; Musto, Federica; Rosati, Riccardo; Sforza, Chiarella

    2012-02-01

    To assess the surface electromyographic spectral characteristics of masticatory and neck muscles during the performance of maximum voluntary clench (MVC) tasks, 29 healthy young adults (15 men, 14 women, mean age 22years) were examined. Electromyography of masseter, temporalis and upper trapezius muscles was performed during 5-s MVCs either on cotton rolls or in intercuspal position. Using a fast Fourier transform, the median power frequency (MPF) was obtained for the first and last seconds of clench, and compared between sexes, muscles, sides, tests and time intervals using ANOVAs. On average, the MPFs did not differ between sexes or sides (p>0.05), but significant effects of muscle (MPF temporalis larger than masseter, larger than trapezius muscles), test (larger MPFs when clenching in intercuspal position than when clenching on cotton rolls) and time (larger MPFs in the first than in the fifth second of clench) were found. In conclusion, a set of data to characterize the sEMG spectral characteristics of jaw and neck muscles in young adult subjects performing MVC tasks currently in use within the dental field was obtained. Reference values may assist in the assessment of patients with alterations in the cranio-cervical-mandibular system.

  10. The spectral characteristics of rotor blade-vortex interaction noise - Experimental and mathematical results

    NASA Technical Reports Server (NTRS)

    Martin, Ruth M.; Hardin, Jay C.

    1987-01-01

    The BVI impulsive content of a rotor acoustic signal is shown to appear in the mid-frequency range of the power spectrum, between the fifth and thirtieth harmonics of the blade passage frequency, concentrated at the harmonics of the blade passage frequency. These harmonics exhibit a humped or scalloped shape in this mid-frequency spectral region. Increased energy at the harmonics of the shaft frequency appears when the BVI impulsive content demonstrates unsteadiness and blade-to-blade differences in the time domain. A mathematical model of a generalized BVI acoustic signal and its power spectrum shows that the power spectrum is scalloped and filtered by a comb function. The spectrum amplitude is defined by the impulse amplitude and emission time. The scalloping of the spectrum is related to the emission time of the impulse itself, and the spacing of the comb function is related to the repetition time (period) of the impulse. The decay rate of the spectral humps is governed by the inverse of frequency squared. The mathematical model validates the characteristics observed in the data and verify that these characteristics are due to blade-vortex interaction activity.

  11. A method for monitoring the variability in nuclear absorption characteristics of aviation fuels

    NASA Technical Reports Server (NTRS)

    Sprinkle, Danny R.; Shen, Chih-Ping

    1988-01-01

    A technique for monitoring variability in the nuclear absorption characteristics of aviation fuels has been developed. It is based on a highly collimated low energy gamma radiation source and a sodium iodide counter. The source and the counter assembly are separated by a geometrically well-defined test fuel cell. A computer program for determining the mass attenuation coefficient of the test fuel sample, based on the data acquired for a preset counting period, has been developed and tested on several types of aviation fuel.

  12. Preparation and Absorption Spectral Property of a Multifunctional Water-Soluble Azo Compound with D-π-A Structure, 4-(4- Hydroxy-1-Naphthylazo)Benzoic Acid

    NASA Astrophysics Data System (ADS)

    Hu, L.; Lv, H.; Xie, C. G.; Chang, W. G.; Yan, Z. Q.

    2015-07-01

    A multifunctional water-soluble azo dye with the D-π-A conjugated structure, 4-(4-hydroxy-1-naphthylazo) benzoic acid ( HNBA), was designed and synthesized using 1-naphanol as the electron donator, benzoic acid as the electron acceptor, and -N=N- as the bridging group. After its structure was characterized by FTIR, 1H NMR, and element analysis, the UV-Vis absorption spectral performance of the target dye was studied in detail. The results showed that the dye, combining hydroxyl group, azo group, and carboxyl group, possessed excellent absorption spectral properties (ɛ = 1.2·104 l·mol-1·cm-1) changing with pH and solvents. In particular, in polar and protonic water, it had excellent optical response to some metal ions, i.e., Fe3+ and Pb2+, which might make it a latent colorimetric sensor for detecting heavy metal ions.

  13. [Spectral characteristics of dissolved organic matter released during the metabolic process of small medusa].

    PubMed

    Guo, Dong-Hui; Yi, Yue-Yuan; Zhao, Lei; Guo, Wei-Dong

    2012-06-01

    The metabolic processes of jellyfish can produce dissolved organic matter (DOM) which will influence the functioning of the aquatic ecosystems, yet the optical properties of DOM released by jellyfish are unknown. Here we report the absorption and fluorescence properties of DOM released by a medusa species Black fordia virginica during a 24 h incubation experiment. Compared with the control group, an obvious increase in the concentrations of dissolved organic carbon (DOC), absorption coefficient (a280) and total dissolved nitrogen (TDN) was observed in incubation group. This clearly demonstrated the release of DOM, chromophoric DOM (CDOM) and dissolved nutrients by B. virginica which feed on enough of Artemia sp. before the experiment. The increase in spectral slope ratio (SR) and decrease in humification index (HIX) indicated that the released DOM was less-humified and had relatively lower molecular weight. Parallel factor analysis (PARAFAC) decomposed the fluorescence matrices of DOM into three humic-like components (C1-C3) and one protein-like component (C4). The Fmax of two components (C2: < 250, 295/386 nm; C4: 275/334 nm) with the emission wavelength < 400 nm increased significantly during the metabolic process of B. virginica. However, the Fmax of the other two components with the emission wavelength > 400 nm showed little changes. Thus, we suggested a zooplankton index (ZIX) to trace and characterize the DOM excreted by metabolic activity of zooplankton, which is calculated as the ratio of the sum of Fmax of all fluorescence components with the emission wavelength < 400 nm to the sum of Fmax of the other components with the emission wavelength > 400 nm.

  14. Performance characteristics of single effect lithium bromide/ water absorption chiller for small data centers

    NASA Astrophysics Data System (ADS)

    Mysore, Abhishek Arun Babu

    A medium data center consists of servers performing operations such as file sharing, collaboration and email. There are a large number of small and medium data centers across the world which consume more energy and are less efficient when compared to large data center facilities of companies such as GOOGLE, APPLE and FACEBOOK. Such companies are making their data center facilities more environmental friendly by employing renewable energy solutions such as wind and solar to power the data center or in data center cooling. This not only reduces the carbon footprint significantly but also decreases the costs incurred over a period of time. Cooling of data center play a vital role in proper functioning of the servers. It is found that cooling consumes about 50% of the total power consumed by the data center. Traditional method of cooling includes the use of mechanical compression chillers which consume lot of power and is not desirable. In order to eliminate the use of mechanical compressor chillers renewable energy resources such as solar and wind should be employed. One such technology is solar thermal cooling by means of absorption chiller which is powered by solar energy. The absorption chiller unit can be coupled with either flat plate or evacuated tube collectors in order to achieve the required inlet temperature for the generator of the absorption chiller unit. In this study a modular data center is considered having a cooling load requirement of 23kw. The performance characteristics of a single stage Lithium Bromide/ water refrigeration is presented in this study considering the cooling load of 23kw. Performance characteristics of each of the 4 heat exchangers within the unit is discussed which helps in customizing the unit according to the users' specific needs. This analysis helps in studying the importance of different properties such as the effect of inlet temperatures of hot water for generator, inlet temperatures of cooling water for absorber and

  15. Spectral response of the intrinsic region of a GaAs-InAs quantum dot solar cell considering the absorption spectra of ideal cubic dots

    NASA Astrophysics Data System (ADS)

    Biswas, Sayantan; Chatterjee, Avigyan; Biswas, Ashim Kumar; Sinha, Amitabha

    2016-10-01

    Recently, attempts have been made by some researchers to improve the efficiency of quantum dot solar cells by incorporating different types of quantum dots. In this paper, the photocurrent density has been obtained considering the absorption spectra of ideal cubic dots. The effects of quantum dot size dispersion on the spectral response of the intrinsic region of a GaAs-InAs quantum dot solar cell have been studied. The dependence of the spectral response of this region on the size of quantum dots of such solar cell has also been investigated. The investigation shows that for smaller quantum dot size dispersion, the spectral response of the intrinsic region of the cell increases significantly. It is further observed that by enlarging the quantum dot size it is possible to enhance the spectral response of such solar cells as it causes better match between absorption spectra of the quantum dots and the solar spectrum. These facts indicate the significant role of quantum dot size and size dispersion on the performance of such devices. Also, the power conversion efficiency of such solar cell has been studied under 1 sun, AM 1.5 condition.

  16. [Study on Spectral Characteristics of Two Kinds of Home-Made Novel Yb-Doped Fluoride Laser Crystals].

    PubMed

    Xu, Wen-bin; Chai, Lu; Shi, Jun-kai; Song, You-jian; Hu, Ming-lie; Wang, Qing-yue; Su, Liang-bi; Jiang, Da-peng; Xu, Jun

    2015-09-01

    Yb-doped fluoride crystals are of important another Yb-doped laser materials besides Yb-doped oxide, which are becoming one of interests for developing tunable lasers and ultrafast lasers. In this paper, the systematic and contrastive experiments of the optical spectral characteristics are presented for two types of home-made novel Yb-doped fluoride laser crystals, namely, Yb-doped CaF2-SrF2 mixed crystal and co-doped Yb, Y:CaF2 single crystal. The fluorescent features of Yb-doped CaF2-SrF2 mixed crystal and co-doped Yb, Y:CaF2 single crystal are apparently different by the fluorescence experiment. The physical mechanism of these fluorescence spectra were analyzed and proposed. The influence of doping concentrations of active Yb(3+) ions or co-doping Y ions on the absorption of Yb-doped CaF2-SrF2 mixed crystal and co-doped Yb, Y:CaF2 single crystal was experimentally investigated, and the optimal values of doping concentrations of active Yb(3+) ions or co-doping Y ions in the two types of fluoride laser crystals were obtained. Continuous-wave laser operation for the two novel fluoride laser crystals has been achieved in three-mirror-folded resonator using a laser diode as the pump source. Therein, the laser operation for the co-doped Yb, Y:CaF2 crystal is demonstrated for the first time. For the two types of fluoride laser crystals (four samples), the input-output power relational curves, the optical slope efficiencies and the laser spectra were demonstrated by the laser experiments. By comparisons between the two types of fluoride laser crystals in the absorbability, fluorescence and laser spectra, laser threshold and slope efficiency of the continuous-wave laser operation, the results show that the best one of the four samples in spectral and laser characteristics is co-doped 3at%Yb, 6at% Y:CaF2 single crystal, which has an expected potential in the application. The research results provide available references for improving further laser performance of Yb

  17. [Study on the characteristic UV absorption parameters of dissolved organic matter extracted from chicken manure during composting].

    PubMed

    Li, Ming-xiao; He, Xiao-song; Liu, Jun; Xi, Bei-dou; Zhao, Yue; Wei, Zi-min; Jiang, Yong-hai; Su, Jing; Hu, Chun-ming

    2010-11-01

    The characteristic parameters obtained from UV-Visible spectra of dissolved organic matter (DOM) during composting were studied in the present paper. The results showed that, during composting progress, the non-humic substances were translated into humus substances, and the aromatization, humification degree and molecular weight of the humus substances increased, while the fatty chains linked with the benzene ring structure were cleavaged into carbonyl, carboxyl and other functional groups. The correlation analysis showed that, when DOM concentration (DOC) from all samples was the same, the specific ultraviolet absorbance values at 254 and 280 nm (SUVA254 and SUVA280, respectively), and the area of a spectrum obtained from 226 to 400 nm (A(226-400)) showed significant positive correlation, furthermore, they were all significantly negatively correlated with the concentration of DOM (DOC), but the correlation between A(226-400) and DOC was the best; The ratio between the absorbance value at 253 nm and that at 203 nm (E253/E203) was significantly correlative with SUVA254, SUVA280 and A 226-400, though the correlation between E253/E203 and DOC was not as good as the other three characteristic parameters; The ratio between the absorbance value at 250 nm and that at 365 nm (E250/E365) and the ratio between the absorbance value at 465 nm and that at 665 nm(E250/E365) were not correlated with the other parameters. The results showed that, the stability of DOM extracted from chicken manure increased during composting, and the complex ability between DOM and heavy metals enhanced as well; A(226-400) reflects the changes of compost maturity best in all UV-Visible spectral absorption parameters studied in this paper.

  18. Comparative study on three highly sensitive absorption measurement techniques characterizing lithium niobate over its entire transparent spectral range.

    PubMed

    Leidinger, M; Fieberg, S; Waasem, N; Kühnemann, F; Buse, K; Breunig, I

    2015-08-24

    We employ three highly sensitive spectrometers: a photoacoustic spectrometer, a photothermal common-path interferometer and a whispering-gallery-resonator-based absorption spectrometer, for a comparative study of measuring the absorption coefficient of nominally transparent undoped, congruently grown lithium niobate for ordinarily and extraordinarily polarized light in the wavelength range from 390 to 3800 nm. The absorption coefficient ranges from below 10(-4) cm(-1) up to 2 cm(-1). Furthermore, we measure the absorption at the Urbach tail as well as the multiphonon edge of the material by a standard grating spectrometer and a Fourier-transform infrared spectrometer, providing for the first time an absorption spectrum of the whole transparency window of lithium niobate. The absorption coefficients obtained by the three highly sensitive and independent methods show good agreement.

  19. [Spectral characteristics and implication of granite from pozaiying molybdenite deposits in west of Guangdong].

    PubMed

    An, Yan-Fei; Zhong, Li-li; Zhou, Yang-Zhang; Chen, Qing; Li, Xing-yuan

    2014-06-01

    Some granite samples from Pozaiying molybdenite deposits in the west of Guangdong were retrieved to characterize the spectral signature of XRD, FT-NIR and Raman. The results show that compared to the Porphyry granite and granite in the far zone, the signal of XRD and Raman of granite in near zone is weaker while the signal of FT-NIR is stronger. The authors' analyses indicate that the FWHM of quartz (101) peak in XRD, Sericite peak (4 529 cm(-1)) in FT-NIR and quartz peak in Raman shift from the latter are higher than those of former two. Those spectral characteristics indicate that compared with other samples, the content of petrogenetic mineral in samples from near zone is lower while the content of alteration mineral is higher, and its crystallinity and crystallization temperatures are both lower. The authors' studies suggest that there may be an alteration zone, embracing the granite-porphyry, which comprised low temperature mineral, and the quartz-porphyry which related to molybdenite mineralization belongs to the zone near Guanshanzhang mass.

  20. Raman spectral characteristics of magmatic-contact metamorphic coals from Huainan Coalfield, China.

    PubMed

    Chen, Shancheng; Wu, Dun; Liu, Guijian; Sun, Ruoyu

    2017-01-15

    Normal burial metamorphism of coal superimposed by magmatic-contact metamorphism makes the characteristics of the Raman spectrum of coal changed. Nine coal samples were chosen at a coal transect perpendicular to the intrusive dike, at the No. 3 coal seam, Zhuji Coal Mine, Huainan Coalfield, China, with different distances from dike-coal boundary (DCB). Geochemical (proximate and ultimate) analysis and mean random vitrinite reflectance (R0, %) indicate that there is a significant relationship between the values of volatile matter and R0 in metamorphosed coals. Raman spectra show that the graphite band (G band) becomes the major band but the disordered band (D band) disappears progressively, with the increase of metamorphic temperature in coals, showing that the structural organization in high-rank contact-metamorphosed coals is close to that of well-crystallized graphite. Evident relationships are observed between the calculated Raman spectral parameters and the peak metamorphic temperature, suggesting some spectral parameters have the potentials to be used as geothermometers for contact-metamorphic coals.

  1. Spectral-luminescence characteristics of lead sulfide molecular clusters and quantum dots in fluorophosphate glasses

    NASA Astrophysics Data System (ADS)

    Lipatova, Zh. O.; Kolobkova, E. V.; Nikonorov, N. V.

    2015-12-01

    PbS molecular clusters and quantum dots (QDs) have been formed by heat treatment in fluorophosphate glasses of the Na2O3-P2O5-Ga2O3-ALF3-ZnO(S)-PbF2 system, and their spectral-luminescence characteristics have been investigated. It is experimentally shown that the transition from molecular clusters to QDs is accompanied by a stepwise change in the spectrum and luminescence quantum yield. Molecular PbS clusters luminesce in the visible spectral range (1.5-3.5 eV) and QDs luminesce in the IR region (0.6-1.4 eV). The luminescence of molecular PbS clusters is characterized by low quantum yield, which decreases from 10 to 1% with an increase in excitation energy. An increase in nanoparticle size leads to a decrease in the Stokes shift from 80 to 50 meV. The QD luminescence spectrum contains two bands, which are due to transitions from two lower excited states.

  2. Raman spectral characteristics of magmatic-contact metamorphic coals from Huainan Coalfield, China

    NASA Astrophysics Data System (ADS)

    Chen, Shancheng; Wu, Dun; Liu, Guijian; Sun, Ruoyu

    2017-01-01

    Normal burial metamorphism of coal superimposed by magmatic-contact metamorphism makes the characteristics of the Raman spectrum of coal changed. Nine coal samples were chosen at a coal transect perpendicular to the intrusive dike, at the No. 3 coal seam, Zhuji Coal Mine, Huainan Coalfield, China, with different distances from dike-coal boundary (DCB). Geochemical (proximate and ultimate) analysis and mean random vitrinite reflectance (R0, %) indicate that there is a significant relationship between the values of volatile matter and R0 in metamorphosed coals. Raman spectra show that the graphite band (G band) becomes the major band but the disordered band (D band) disappears progressively, with the increase of metamorphic temperature in coals, showing that the structural organization in high-rank contact-metamorphosed coals is close to that of well-crystallized graphite. Evident relationships are observed between the calculated Raman spectral parameters and the peak metamorphic temperature, suggesting some spectral parameters have the potentials to be used as geothermometers for contact-metamorphic coals.

  3. [Study on expert system of infrared spectral characteristic of combustible smoke agent].

    PubMed

    Song, Dong-ming; Guan, Hua; Hou, Wei; Pan, Gong-pei

    2009-05-01

    The present paper studied the application of expert system in prediction of infrared spectral characteristic of combustible anti-infrared smoke agent. The construction of the expert system was founded, based on the theory of minimum free energy and infrared spectral addition. After the direction of smoke agent was input, the expert system could figure out the final combustion products. Then infrared spectrogram of smoke could also be simulated by adding the spectra of all of the combustion products. Meanwhile, the screening index of smoke was provided in the wave bands of 3-5 im and 8-14 microm. FTIR spectroscope was used to investigate the performance of one kind of HC smoke. The combustion products calculated by the expert system were coincident with the actual data, and the simulant infrared spectrum was also similar to the real one of the smoke. The screening index given by the system was consistent with the known facts. It was showed that a new approach was offered for the fast discrimination of varieties of directions of smoke agent.

  4. Environment effect on spectral and charge distribution characteristics of some drugs of folate derivatives

    NASA Astrophysics Data System (ADS)

    Khadem Sadigh, M.; Zakerhamidi, M. S.; Seyed Ahmadian, S. M.; Johari-Ahar, M.; Zare Haghighi, L.

    2017-01-01

    Molecular surrounding media as an important factor can effect on the operation of wide variety of drugs. For more study in this paper, spectral properties of Methotrexate and Folinic acid have been studied in various solvents. Our results show that the photo-physical of solute molecules depend strongly on solute-solvent interactions and active groups in their chemical structures. In order to investigate the contribution of specific and nonspecific interactions on the various properties of drug molecules, the linear solvation energy relationships concept is used. Moreover, charge distribution characteristics of used samples with various resonance structures in solvent environments were calculated by means of solvatochromic method. The high value of dipole moments in excited state show that local intramolecular charge transfer can occur by excitation. These results about molecular interactions can be extended to biological systems and can indicate completely the behaviors of Methotrexate and Folinic acid in polar solvents such as water in body system.

  5. Spectral Characteristics of Laser-Induced Graphite Plasma in Ambient Air

    NASA Astrophysics Data System (ADS)

    Wang, Jinmei; Zheng, Peichao; Liu, Hongdi; Fang, Liang

    2016-11-01

    An experimental setup of laser-induced graphite plasma was built and the spectral characteristics and properties of graphite plasma were studied. From the temporal behavior of graphite plasma, the duration of CN partials (B2 Σ+ → X2 Σ+) emission was two times longer than that of atomic carbon, and all intensities reached the maximum during the early stage from 0.2 μs to 0.8 μs. The electron temperature decreased from 11807 K to 8755 K, the vibration temperature decreased from 8973 K to 6472 K, and the rotational temperature decreased from 7288 K to 4491 K with the delay time, respectively. The effect of the laser energy was also studied, and it was found that the thresholds and spectral characteristics of CN molecular and C atomic spectroscopy presented great differences. At lower laser energies, the electron excited temperature, the electron density, the vibrational temperature and rotational temperature of CN partials increased rapidly. At higher laser energies, the increasing of electron excited temperature and electron density slow down, and the vibrational temperature and rotational temperature even trend to saturation due to plasma shielding and dissociation of CN molecules. The relationship among the three kinds of temperatures was Telec>Tvib>Trot at the same time. The electron density of the graphite plasma was in the order of 1017 cm-3 and 1018 cm-3. supported by National Natural Science Foundation of China (No. 61205149), Scientific Research Foundation for the Returned Overseas Chinese Scholars of State Education Ministry, Science Research Funds of Chongqing Municipal Education Commission (KJ1500436), Scientific and Technological Talents Training Project of Chongqing (CSTC2013kjrc-qnrc40002), Key Project of Foundation and Advanced Technology Research Project of Chongqing (CSTC2015jcyjB0358), Visiting Scholarship of State Key Laboratory of Power Transmission Equipment & System Security and New Technology (2007DA10512714409)

  6. Deuterium absorption and material phase characteristics of SAES St 198 Zr-Fe Alloy. Revision 1

    SciTech Connect

    Nobile, A.; Mosley, W.C.; Holder, J.S.; Brooks, K.N.

    1994-01-01

    This document reports deuterium absorption and material phase characteristics of SAES St 198 Zr-Fe Alloy (76.5% Zr). Scanning electron microscope images of polished surfaces, electron probe microanalysis, and x-ray powder diffractometry indicated the presence of a primary Zr{sub 2}Fe phase with secondary phases of ZrFe{sub 2}, Zr{sub 5}FeSn, {alpha}-Zr, and Zr{sub 6}Fe{sub 3}O. A statistically designed experiment to determine the effects of temperature, time, and vacuum quality on activation of St 198 revealed that, when activated at low temperature (350C), deuterium absorption rate was slower when the vacuum quality was poor (2.5 Pa vs. 3 {times} 10{sup {minus}4} Pa). However, at higher activation temperature (500C), deuterium absorption rate was fast and was independent of vacuum quality. Deuterium pressure-composition-temperature (P-C-T) data are reported for St 198 in the temperature range 200 to 500C. The P-C-T data over the full range of deuterium loading and at temperatures of 350C and below is described an expression. At higher temperatures, one or more secondary reactions in the solid phase occur that slowly consume D{sub 2} from the gas phase. X-ray diffraction and other data suggest these reactions to be: 2 Zr{sub 2}FeD{sub x} {yields} xZrD{sub 2} + x/3 ZrFe{sub 2} + (2 {minus} 2/3x) Zr{sub 2}Fe and Zr{sub 2}FeD{sub x} + (2 {minus} 1/2x) D{sub 2} {yields} 2 ZrD{sub 2} + Fe, where 0 < x < 3. Reaction between gas-phase deuterium and Zr{sub 2}Fe formed in the first reaction accounts for the observed consumption of deuterium from the gas phase by this reaction.

  7. Estimating organic micro-pollutant removal potential of activated carbons using UV absorption and carbon characteristics.

    PubMed

    Zietzschmann, Frederik; Altmann, Johannes; Ruhl, Aki Sebastian; Dünnbier, Uwe; Dommisch, Ingvild; Sperlich, Alexander; Meinel, Felix; Jekel, Martin

    2014-06-01

    Eight commercially available powdered activated carbons (PAC) were examined regarding organic micro-pollutant (OMP) removal efficiencies in wastewater treatment plant (WWTP) effluent. PAC characteristic numbers such as B.E.T. surface, iodine number and nitrobenzene number were checked for their potential to predict the OMP removal of the PAC products. Furthermore, the PAC-induced removal of UV254 nm absorption (UVA254) in WWTP effluent was determined and also correlated with OMP removal. None of the PAC characteristic numbers can satisfactorily describe OMP removal and accordingly, these characteristics have little informative value on the reduction of OMP concentrations in WWTP effluent. In contrast, UVA254 removal and OMP removal correlate well for carbamazepine, diclofenac, and several iodinated x-ray contrast media. Also, UVA254 removal can roughly describe the average OMP removal of all measured OMP, and can accordingly predict PAC performance in OMP removal. We therefore suggest UVA254 as a handy indicator for the approximation of OMP removal in practical applications where direct OMP concentration quantification is not always available. In continuous operation of large-scale plants, this approach allows for the efficient adjustment of PAC dosing to UVA254, in order to ensure reliable OMP removal whilst minimizing PAC consumption.

  8. A simple fiber optic humidity sensor based on water-absorption characteristic of CAB

    NASA Astrophysics Data System (ADS)

    Li, Guang; Xu, Wei; Huang, Xuguang

    2015-02-01

    A simple fiber-optic relative humidity sensor based on cellulose acetate butyrate (CAB) and Fresnel reflection is proposed and investigated theoretically and experimentally. The sensing system is only composed of one light source, three optical couplers, two photo-detectors and two fiber sensing ends. The operation principle is based on relative Fresnel reflection and water-absorption characteristic of the CAB which simultaneously contains hydrophilic and hydrophobic groups. The water absorption process will lead to variation of the CAB's refractive index or permittivity. It has to be noted that the double-channel system can effectively eliminate the intensity fluctuation of the light source and the influence of the environment. In this paper, the relative humidity environments approximately ranging from 10 % to 100% are generated and measured both in the humidification and dehumidification processes, which shows a good repeatability and reveals a very good fitting feature with a high value of R2 above 0.99. It is of reflection type and can be simply extend to be a multi-point-monitoring system. The sensing system is of cost- effective, simple operation and high precision.

  9. Visible spectral dependence of the scattering and absorption coefficients of pigmented coatings from inversion of diffuse reflectance spectra.

    PubMed

    Curiel, Fernando; Vargas, William E; Barrera, Rubén G

    2002-10-01

    A spectral-projected gradient method and an extension of the Kubelka-Munk theory are applied to obtain the relevant parameters of the theory from measured diffuse reflectance spectra of pigmented samples illuminated with visible diffuse radiation. The initial estimate of the spectral dependence of the parameters, required by a recursive spectral-projected gradient method, was obtained by use of direct measurements and up-to-date theoretical estimates. We then tested the consistency of the Kubelka-Munk theory by repeating the procedure with samples of different thicknesses.

  10. Spectral Cauchy characteristic extraction of strain, news and gravitational radiation flux

    NASA Astrophysics Data System (ADS)

    Handmer, Casey J.; Szilágyi, Béla; Winicour, Jeffrey

    2016-11-01

    We present a new approach for the Cauchy-characteristic extraction (CCE) of gravitational radiation strain, news function, and the flux of the energy-momentum, supermomentum and angular momentum associated with the Bondi-Metzner-Sachs asymptotic symmetries. In CCE, a characteristic evolution code takes numerical data on an inner worldtube supplied by a Cauchy evolution code, and propagates it outwards to obtain the space-time metric in a neighborhood of null infinity. The metric is first determined in a scrambled form in terms of coordinates determined by the Cauchy formalism. In prior treatments, the waveform is first extracted from this metric and then transformed into an asymptotic inertial coordinate system. This procedure provides the physically proper description of the waveform and the radiated energy but it does not generalize to determine the flux of angular momentum or supermomentum. Here we formulate and implement a new approach which transforms the full metric into an asymptotic inertial frame and provides a uniform treatment of all the radiation fluxes associated with the asymptotic symmetries. Computations are performed and calibrated using the spectral Einstein code.

  11. Broadband absorption and reduced scattering spectra of in-vivo skin can be noninvasively determined using δ-P1 approximation based spectral analysis

    PubMed Central

    Hung, Cheng-Hung; Chou, Ting-Chun; Hsu, Chao-Kai; Tseng, Sheng-Hao

    2015-01-01

    Previously, we revealed that a linear gradient line source illumination (LGLSI) geometry could work with advanced diffusion models to recover the sample optical properties at wavelengths where sample absorption and reduced scattering were comparable. In this study, we employed the LGLSI geometry with a broadband light source and utilized the spectral analysis to determine the broadband absorption and scattering spectra of turbid samples in the wavelength range from 650 to 1350 nm. The performance of the LGLSI δ-P1 diffusion model based spectral analysis was evaluated using liquid phantoms, and it was found that the sample optical properties could be properly recovered even at wavelengths above 1000 nm where μs' to μa ratios were in the range between 1 to 20. Finally, we will demonstrate the use of our system for recovering the 650 to 1350 nm absorption and scattering spectra of in-vivo human skin. We expect this system can be applied to study deep vessel dilation induced hemoglobin concentration variation and determine the water and lipid concentrations of in-vivo skin in clinical settings in the future. PMID:25780735

  12. Relationship between Spectral Characteristics of Spontaneous Postural Sway and Motion Sickness Susceptibility

    PubMed Central

    Laboissière, Rafael; Letievant, Jean-Charles; Ionescu, Eugen; Barraud, Pierre-Alain; Mazzuca, Michel; Cian, Corinne

    2015-01-01

    Motion sickness (MS) usually occurs for a narrow band of frequencies of the imposed oscillation. It happens that this frequency band is close to that which are spontaneously produced by postural sway during natural stance. This study examined the relationship between reported susceptibility to motion sickness and postural control. The hypothesis is that the level of MS can be inferred from the shape of the Power Spectral Density (PSD) profile of spontaneous sway, as measured by the displacement of the center of mass during stationary, upright stance. In Experiment 1, postural fluctuations while standing quietly were related to MS history for inertial motion. In Experiment 2, postural stability measures registered before the onset of a visual roll movement were related to MS symptoms following the visual stimulation. Study of spectral characteristics in postural control showed differences in the distribution of energy along the power spectrum of the antero-posterior sway signal. Participants with MS history provoked by exposure to inertial motion showed a stronger contribution of the high frequency components of the sway signal. When MS was visually triggered, sick participants showed more postural sway in the low frequency range. The results suggest that subject-specific PSD details may be a predictor of the MS level. Furthermore, the analysis of the sway frequency spectrum provided insight into the intersubject differences in the use of postural control subsystems. The relationship observed between MS susceptibility and spontaneous posture is discussed in terms of postural sensory weighting and in relation to the nature of the provocative stimulus. PMID:26657203

  13. Spectral and Temporal Characteristics of X-Ray-Bright Stars in the Pleiades

    NASA Technical Reports Server (NTRS)

    Gagne, Marc; Caillault, Jean-Pierre; Stauffer, John R.

    1995-01-01

    We follow up our deep ROSAT imaging survey of the Pleiades (Stauffer et al. 1994) with an analysis of the spectral and temporal characteristics of the X-ray-bright stars in the Pleiades. Raymond & Smith (1977) one and two-temperature models have been used to fit the position-sensitive proportional counter (PSPC) pulse-height spectra of the dozen or so brightest sources associated with late-type Pleiades members. The best-fit temperatures suggest hot coronal temperatures for K, M, and rapidly rotating G stars, and cooler temperatures for F and slowly rotating G stars. In order to probe the many less X-ray-luminous stars, we have generated composite spectra by combining net counts from all Pleiades members according to spectral type and rotational velocity. Model fits to the composite spectra confirm the trend seen in the individual spectral fits. Particularly interesting is the apparent dependence of coronal temperature on L(sub x)/L(sub bol). A hardness-ratio analysis also confirms some of these trends. The PSPC data have also revealed a dozen or so strong X-ray flares with peak X-ray luminosities in excess of approx. 10(exp 30) ergs/sec. We have modeled the brightest of these flares with a simple quasi-static cooling loop model. The peak temperature and emission measure and the inferred electron density and plasma volume suggest a very large scale flaring event. The PSPC data were collected over a period of approx. 18 months, allowing us to search for source variability on timescales ranging from less than a day (in the case of flares) to more than a year between individual exposures. On approximately year-long timescales, roughly 25% of the late-type stars are variable. Since the Pleiades was also intensively monitored by the imaging instruments on the Einstein Observatory, we have examined X-ray luminosity variations on the 10 yr timescale between Einstein and ROSAT and find that up to 40% of the late-type stars are X-ray variable. Since there is only marginal

  14. Combining the absorptive and radiative loss in metasurfaces for multi-spectral shaping of the electromagnetic scattering

    PubMed Central

    Pan, Wenbo; Huang, Cheng; Pu, Mingbo; Ma, Xiaoliang; Cui, Jianhua; Zhao, Bo; Luo, Xiangang

    2016-01-01

    The absorptive and radiative losses are two fundamental aspects of the electromagnetic responses, which are widely occurring in many different systems such as waveguides, solar cells, and antennas. Here we proposed a metasurface to realize the control of the absorptive and radiative loss and to reduce the radar cross section (RCS) in multi-frequency bands. The anti-phase gradient and absorptive metasurfaces were designed that consists of metallic square patch and square loop structure inserted with resistors, acting as an phase gradient material in the X and Ku band, while behaving as an absorber in the S band. The simulation and experiment results verified the double-band, wideband and polarization-independent RCS reduction by the absorptive and anti-phase gradient metasurfaces. PMID:26891773

  15. Combining the absorptive and radiative loss in metasurfaces for multi-spectral shaping of the electromagnetic scattering

    NASA Astrophysics Data System (ADS)

    Pan, Wenbo; Huang, Cheng; Pu, Mingbo; Ma, Xiaoliang; Cui, Jianhua; Zhao, Bo; Luo, Xiangang

    2016-02-01

    The absorptive and radiative losses are two fundamental aspects of the electromagnetic responses, which are widely occurring in many different systems such as waveguides, solar cells, and antennas. Here we proposed a metasurface to realize the control of the absorptive and radiative loss and to reduce the radar cross section (RCS) in multi-frequency bands. The anti-phase gradient and absorptive metasurfaces were designed that consists of metallic square patch and square loop structure inserted with resistors, acting as an phase gradient material in the X and Ku band, while behaving as an absorber in the S band. The simulation and experiment results verified the double-band, wideband and polarization-independent RCS reduction by the absorptive and anti-phase gradient metasurfaces.

  16. Frequency-domain method for measuring spectral properties in multiple-scattering media: methemoglobin absorption spectrum in a tissuelike phantom

    NASA Astrophysics Data System (ADS)

    Fishkin, Joshua B.; So, Peter T. C.; Cerussi, Albert E.; Gratton, Enrico; Fantini, Sergio; Franceschini, Maria Angela

    1995-03-01

    We have measured the optical absorption and scattering coefficient spectra of a multiple-scattering medium (i.e., a biological tissue-simulating phantom comprising a lipid colloid) containing methemoglobin by using frequency-domain techniques. The methemoglobin absorption spectrum determined in the multiple-scattering medium is in excellent agreement with a corrected methemoglobin absorption spectrum obtained from a steady-state spectrophotometer measurement of the optical density of a minimally scattering medium. The determination of the corrected methemoglobin absorption spectrum takes into account the scattering from impurities in the methemoglobin solution containing no lipid colloid. Frequency-domain techniques allow for the separation of the absorbing from the scattering properties of multiple-scattering media, and these techniques thus provide an absolute

  17. Collisional Induced Absorption (CIA) bands of CO2 and H2 measured in the IR spectral range

    NASA Astrophysics Data System (ADS)

    Stefani, S.; Piccioni, G.; Snels, M.; Adriani, A.; Grassi, D.

    2015-10-01

    In this paper we present the results on the Collisional Induced Absorption (CIA) bands of CO2 and H2 measured employing two different experimental setup. Each of them allows us to reproduce typical planetary conditions, at a pressure and temperature from 1 up to 50 bar and from 298 up to 500 K respectively. A detailed study on the temperature dependence of the CO2 CIA absorption bands will be presented.

  18. [Synthesis and spectral characteristics of novel di-schiff base derivatives incorporting oxadiazole ring].

    PubMed

    Chen, Tong-bin; Zhang, Xiong-lu; Fan, Xiao-lin; Li, Xun

    2008-12-01

    4-nitrobenzoic acid and hydraxine sulfate were cyclized with H3PO4/P2O5 to afford 2,5-bis(4-nitrophenyl)-1, 3,4-oxadiazole(1), then(1)was reduced to 2,5-bis(4-aminophenyl)-1,3,4-oxadiazole using Zn/CaCl2 as reduction reagent, and at last, a series of novel di-schiff base derivatives containing oxadiazole ring were obtained by the reaction of 2,5-bis(4-aminophenyl)-1, 3,4-oxadiazole with aromatic aldehydes (yield: 65%-81%). The structures of these compounds were confirmed by 1H NMR, FTIR and MS. Their UV-Vis spectra as well as fluorescence spectra were studied and the electrochemical properties were tested with cyclic voltammetry. The UV-Vis spectroscopy results show that the characteristic absorption peaks of 1, 3, 4-oxadiazole unit and di-schiff base unit disappeared. The maximum absorption wavelength was detected at 345-357 nm because conjugation effect made the two energy bands partially hybrid and form a new energy band structure. Fluorescence spectroscopy results show that they emit strong blue and purple fluorescence, and the emission maximum wavelengths of di-schiff base are from 390 to 407 nm. Electrochemical properties results show that they have higher affinity energy (2.36-3.04 eV) and ionic potential (5.35-6.06 eV), which indicated that they have better electron-transporting properties than PBD except 3 a and 3 h. The results give a reference to further application to organic electroluminescent devices of the target compound.

  19. Determination of the Characteristics of Ground-Based IR Spectral Instrumentation for Environmental Monitoring of the Atmosphere

    NASA Astrophysics Data System (ADS)

    Makarova, M. V.; Poberovskii, A. V.; Hase, F.; Timofeyev, Yu. M.; Imhasin, Kh. Kh.

    2016-07-01

    This is a study of the spectral characteristics of a ground-based spectral system consisting of an original system for tracking the sun developed at St. Petersburg State University and a Bruker IFS125HR Fourier spectrometer. The importance of accounting for the actual instrument function of the spectral system during processing of ground-based IR spectra of direct solar radiation is illustrated by the example of determining the overall abundance of methane in the atmosphere. Spectral intervals are proposed for taking spectra of direct solar radiation with an HBr cell, which yield information on the parameters of the ground-based system, while simultaneously checking the alignment of the system for each spectrum of the atmosphere.

  20. Intersubband absorption of cubic GaN/Al(Ga)N quantum wells in the near-infrared to terahertz spectral range

    NASA Astrophysics Data System (ADS)

    Machhadani, H.; Tchernycheva, M.; Sakr, S.; Rigutti, L.; Colombelli, R.; Warde, E.; Mietze, C.; As, D. J.; Julien, F. H.

    2011-02-01

    The intersubband absorption of cubic GaN/Al(Ga)N quantum wells is studied experimentally and theoretically over a wide spectral range. By changing the quantum well thickness it is possible to tune the intersubband absorption peak wavelength from 1.4 μm (214 THz) to 63 μm (4.76 THz). Comparing the experimental results with simulations based on the effective-mass model we demonstrate that the GaN/AlN conduction-band offset is higher than 1.2 eV. The best fit with the experimental data is achieved for a conduction-band offset of 1.4 eV and for a GaN effective mass of 0.11m0.

  1. Heat and mass transfer characteristics of absorption of R134a into DMAC in a horizontal tube absorber

    NASA Astrophysics Data System (ADS)

    Harikrishnan, L.; Maiya, M. P.; Tiwari, S.; Wohlfeil, A.; Ziegler, F.

    2009-10-01

    In this paper the heat and mass transfer characteristics of a horizontal tube absorber for the mixture R134a/DMAC in terms of experimentally gained heat and mass transfer coefficients are presented. The heat transfer coefficient is mainly dependent on the solution’s mass flow rate. The mass transfer coefficient is strongly related to the subcooling of the solution. The data are compared to experimental absorption characteristics of water into aqueous lithium bromide in an absorption chiller. The mass transfer coefficients are of similar size whereas the heat transfer coefficients are about one order of magnitude smaller for R134a-DMAC.

  2. Effect of the temperature of synthesis on the spectral and dimensional characteristics of selenium-chymotrypsin nanocomplexes

    NASA Astrophysics Data System (ADS)

    Borovikova, L. N.; Titova, A. V.; Kipper, A. I.; Pisarev, O. A.

    2015-03-01

    The effect temperature has on the spectral and dimensional characteristics of nanocomplexes formed in aqueous chymotrypsin solutions as a result of ionic selenium reduction in a redox selenite-ascorbate system is investigated by means of spectrophotometry and dynamic light scattering.

  3. Spectral and amplitude-time characteristics of radiation of plasma of a repetitively pulsed discharge initiated by runaway electrons

    NASA Astrophysics Data System (ADS)

    Lomaev, M. I.; Beloplotov, D. V.; Sorokin, D. A.; Tarasenko, V. F.

    2016-02-01

    Spectral and amplitude-time characteristics of radiation of plasma of a repetitively pulsed discharge initiated by runaway electrons were studied experimentally in nitrogen. Intense emission lines of copper atoms, nitrogen atoms, and ions, as well as the first and the second positive systems of nitrogen, NO, and CN, were observed in the regime of repetitively pulsed excitation.

  4. Polarization and spectral characteristics of the two-photon luminescence from colloidal gold nanoparticles excited by tunable laser radiation

    SciTech Connect

    Yashunin, D. A. Korytin, A. I.; Stepanov, A. N.

    2015-12-15

    We have experimentally studied two-photon luminescence from a colloidal solution of spherical gold nanoparticles by tuning the wavelength of the exciting radiation. The measured polarization and spectral characteristics of the two-photon luminescence signal show that the observed nonlinear optical response is determined by the dimers present in the solution with a concentration of a few percent of total nanoparticle number.

  5. Temporal and spectral characteristics of seismicity observed at Popocatepetl volcano, central Mexico

    USGS Publications Warehouse

    Arciniega-Ceballos, A.; Valdes-Gonzalez, C.; Dawson, P.

    2000-01-01

    Popocatepetl volcano entered an eruptive phase from December 21, 1994 to March 30, 1995, which was characterized by ash and fumarolic emissions. During this eruptive episode, the observed seismicity consisted of volcano-tectonic (VT) events, long-period (LP) events and sustained tremor. Before the initial eruption on December 21, VT seismicity exhibited no increase in number until a swarm of VT earthquakes was observed at 01:31 hours local time. Visual observations of the eruption occurred at dawn the next morning. LP activity increased from an average of 7 events a day in October 1994 to 22 events per day in December 1994. At the onset of the eruption, LP activity peaked at 49 events per day. LP activity declined until mid-January 1995 when no events were observed. Tremor was first observed about one day after the initial eruption and averaged 10 h per episode. By late February 1995, tremor episodes became more intermittent, lasting less than 5 min, and the number of LP events returned to pre-eruption levels (7 events per day). Using a spectral ratio technique, low-frequency oceanic microseismic noise with a predominant peak around 7 s was removed from the broadband seismic signal of tremor and LP events. Stacks of corrected tremor episodes and LP events show that both tremor and LP events contain similar frequency features with major peaks around 1.4 Hz. Frequency analyses of LP events and tremor suggest a shallow extended source with similar radiation pattern characteristics. The distribution of VT events (between 2.5 and 10 km) also points to a shallow source of the tremor and LP events located in the first 2500 m beneath the crater. Under the assumption that the frequency characteristics of the signals are representative of an oscillator we used a fluid-filled-crack model to infer the length of the resonator.

  6. Comparisons of spectral characteristics of wind noise between omnidirectional and directional microphones.

    PubMed

    Chung, King

    2012-06-01

    Wind noise reduction is a topic of ongoing research and development for hearing aids and cochlear implants. The purposes of this study were to examine spectral characteristics of wind noise generated by directional (DIR) and omnidirectional (OMNI) microphones on different styles of hearing aids and to derive wind noise reduction strategies. Three digital hearing aids (BTE, ITE, and ITC) were fitted to Knowles Electronic Manikin for Acoustic Research. They were programmed to have linear amplification and matching frequency responses between the DIR and OMNI modes. Flow noise recordings were made from 0° to 360° azimuths at flow velocities of 4.5, 9.0, and 13.5 m/s in a quiet wind tunnel. Noise levels were analyzed in one-third octave bands from 100 to 8000 Hz. Comparison of wind noise revealed that DIR generally produced higher noise levels than OMNI for all hearing aids, but it could result in lower levels than OMNI at some frequencies and head angles. Wind noise reduction algorithms can be designed to detect noise levels of DIR and OMNI outputs in each frequency channel, remove the constraint to switch to OMNI in low-frequency channel(s) only, and adopt the microphone mode with lower noise levels to take advantage of the microphone differences.

  7. Composition and spectral characteristics of ambient aerosol at Mauna Loa Observatory

    SciTech Connect

    Johnson, S.A.; Kumar, R. )

    1991-03-20

    Ambient aerosol particles were sampled continuously with a time resolution of {approximately}4 hours for a period of 8 days at the Mauna Loa Observatory, Hawaii, in August 1986. The samples were analyzed on-site for their chemical composition by attenuated total internal reflection infrared spectroscopy. The infrared absorption spectra of the samples also provided data on aerosol light absorbance characteristics at 9.1 and 10.6 {mu}m - wavelengths of interest in determining aerosol backscatter coefficients for CO{sub 2} lidars. The chemical species in the ambient aerosol varied considerably during this 8-day period. The aerosol was acidic ((NH{sub 4}){sub 3}H(SO{sub 4}){sub 2},NH{sub 4}HSO{sub 4}, or H{sub 2}SO{sub 4}) rather than neutral ((NH{sub 4}){sub 2}SO{sub 4}) for a major fraction of the sampling time. The samples generally showed much higher absorbance at 9.1 {mu}m than at 10.6 {mu}m. Changes in the chemical composition between (NH{sub 4}){sub 2}SO{sub 4} and the more acidic forms were accompanied by substantial changes in the sample's absorbance at 9.1 {mu}m but lesser changes in the absorbance at 10.6 {mu}m. These variations could have a profound effect on backscatter coefficients of atmospheric aerosol particles at CO{sub 2} wavelengths.

  8. Spectral characteristic investigation on complex of Ni (II) with captopril and its analytical application.

    PubMed

    Wei, Xiaoling; Du, Liangwei; Li, Dongmei; Gong, Qi; Wang, Lisheng; Lin, Yu

    2012-08-01

    In this paper, Ni (II) reacting with captopril (CPT) can form complex in alkaline solution and the formed complex has a characteristic absorption peak at 340nm. The absorbance of the Ni-CPT complex increases linearly with the increased concentration of captopril. The study also shows that ammonia has an obvious sensitizing effect on the absorbance. Based on the study, a new method for the determination of captopril is established. Experimental results show that the linear range of this method under optimum condition is 1.0-60mg/L with correlation coefficient, detection limit and precision of 0.9999, 0.31mg/L and 0.87%, respectively. The method used to determine captopril in commercial captopril tablets has a satisfactory result with the recoveries in the range of 99.0-103.6% and the relative standard deviation (RSD) in the range of 0.8-3.7%. We preliminarily study the reaction mechanism and demonstrate that the complex ratio of Ni (II) with captopril is 1:2 and the formation constant is 6.3×10(9).

  9. Spectral characteristic investigation on complex of Ni (II) with captopril and its analytical application

    NASA Astrophysics Data System (ADS)

    Wei, Xiaoling; Du, Liangwei; Li, Dongmei; Gong, Qi; Wang, Lisheng; Lin, Yu

    In this paper, Ni (II) reacting with captopril (CPT) can form complex in alkaline solution and the formed complex has a characteristic absorption peak at 340 nm. The absorbance of the Ni-CPT complex increases linearly with the increased concentration of captopril. The study also shows that ammonia has an obvious sensitizing effect on the absorbance. Based on the study, a new method for the determination of captopril is established. Experimental results show that the linear range of this method under optimum condition is 1.0-60 mg/L with correlation coefficient, detection limit and precision of 0.9999, 0.31 mg/L and 0.87%, respectively. The method used to determine captopril in commercial captopril tablets has a satisfactory result with the recoveries in the range of 99.0-103.6% and the relative standard deviation (RSD) in the range of 0.8-3.7%. We preliminarily study the reaction mechanism and demonstrate that the complex ratio of Ni (II) with captopril is 1:2 and the formation constant is 6.3 × 109.

  10. Development of Spectral and Atomic Models for Diagnosing Energetic Particle Characteristics in Fast Ignition Experiments

    SciTech Connect

    MacFarlane, Joseph J

    2009-08-07

    This Final Report summarizes work performed under DOE STTR Phase II Grant No. DE-FG02-05ER86258 during the project period from August 2006 to August 2009. The project, “Development of Spectral and Atomic Models for Diagnosing Energetic Particle Characteristics in Fast Ignition Experiments,” was led by Prism Computational Sciences (Madison, WI), and involved collaboration with subcontractors University of Nevada-Reno and Voss Scientific (Albuquerque, NM). In this project, we have: Developed and implemented a multi-dimensional, multi-frequency radiation transport model in the LSP hybrid fluid-PIC (particle-in-cell) code [1,2]. Updated the LSP code to support the use of accurate equation-of-state (EOS) tables generated by Prism’s PROPACEOS [3] code to compute more accurate temperatures in high energy density physics (HEDP) plasmas. Updated LSP to support the use of Prism’s multi-frequency opacity tables. Generated equation of state and opacity data for LSP simulations for several materials being used in plasma jet experimental studies. Developed and implemented parallel processing techniques for the radiation physics algorithms in LSP. Benchmarked the new radiation transport and radiation physics algorithms in LSP and compared simulation results with analytic solutions and results from numerical radiation-hydrodynamics calculations. Performed simulations using Prism radiation physics codes to address issues related to radiative cooling and ionization dynamics in plasma jet experiments. Performed simulations to study the effects of radiation transport and radiation losses due to electrode contaminants in plasma jet experiments. Updated the LSP code to generate output using NetCDF to provide a better, more flexible interface to SPECT3D [4] in order to post-process LSP output. Updated the SPECT3D code to better support the post-processing of large-scale 2-D and 3-D datasets generated by simulation codes such as LSP. Updated atomic physics modeling to provide for

  11. The Effects of High Frequency ULF Wave Activity on the Spectral Characteristics of Coherent HF Radar Returns

    NASA Astrophysics Data System (ADS)

    Wright, D. M.; Yeoman, T. K.; Woodfield, E. E.

    2003-12-01

    It is now a common practice to employ ground-based radars in order to distinguish between those regions of the Earth's upper atmosphere which are magnetically conjugate to open and closed field lines. Radar returns from ionospheric irregularities inside the polar cap and cusp regions generally exhibit large spectral widths in contrast to those which exist on closed field lines at lower latitudes. It has been suggested that the so-called Spectral Width Boundary (SWB) might act as a proxy for the open-closed field line boundary (OCFLB), which would then be an invaluable tool for investigating reconnection rates in the magnetosphere. The exact cause of the increased spectral widths observed at very high latitudes is still subject to considerable debate. Several mechanisms have been proposed. This paper compares a dusk-sector interval of coherent HF radar data with measurements made by an induction coil magnetometer located at Tromso, Norway (66° N geomagnetic). On this occasion, a series of transient regions of radar backscatter exhibiting large spectral widths are accompanied by increases in spectral power of ULF waves in the Pc1-2 frequency band. These observations would then, seem to support the possibility that high frequency magnetospheric wave activity at least contribute to the observed spectral characteristics and that such wave activity might play a significant role in the cusp and polar cap ionospheres.

  12. Stabilization and spectral characterization of an alexandrite laser for water vapor lidar measurements

    NASA Technical Reports Server (NTRS)

    Ponsardin, Patrick; Higdon, Noah S.; Grossman, Benoist E.; Browell, Edward V.

    1991-01-01

    A description of an optical system used to lock the alexandrite laser frequency on a water vapor absorption line is presented. The laser spectral characteristics, which include the spectral purity, the effect of the laser linewidth on the absorption, and the laser wavelength stability, are evaluated.

  13. Spectral-induced polarization characteristics of rocks from Shinyemi deposit in Northeastern South Korea

    NASA Astrophysics Data System (ADS)

    Park, Samgyu; Shin, Seung Wook; Son, Jeong-Sul; Kim, Changryol

    2016-04-01

    Contact metasomatism between carbonate and igneous rocks leads to the formation of skarn deposits, and ore minerals are abundant. Geophysical methods that visualize the distributions of physical properties have been utilized to determine lithological boundaries in ore deposits. In particular, spectral-induced polarization (SIP) is the most effective of those methods for mineral exploration because it can obtain not only the boundaries but also the abundance and grain size of ore minerals. It is crucial to characterize the SIP responses of in situ rocks for a more realistic interpretation. Thus, typical rocks composed of igneous rock, skarn rock, skarn ore, and carbonate rock were sampled from drilling cores in the Shinyemi deposit, which is one of the well-known skarn deposits in Northeastern South Korea. The purpose of this study was to characterize the SIP responses of rocks by laboratory measurements. The characterization was performed by evaluating spectra and IP parameters. The IP properties were acquired from equivalent circuit analysis using a circuit model based on the electrochemical theory, and the analysis results of this circuit model were relatively well fit compared with those of the traditional Dias and Cole-Cole models. The frequency responses below 100 Hz in the spectra and the chargeability values of the skarn rocks and ores containing magnetite were relatively strong and high, respectively, compared with those of non-mineralized igneous and carbonate rocks. Therefore, it is considered that these characteristics are dependent on the abundance of magnetite. In case of the skarn ores with high magnetite content, the resistivity values were significantly low and the relaxation time values were influenced by the grain size of magnetite. On the other hand, it is considered that the DC resistivity and the relaxation time values of the igneous and carbonate rocks are slightly related to the porosity and the grade of hydrothermal alteration, respectively.

  14. Spectral Analysis and Metastable Absorption Measurements of High Pressure Capacitively and Inductively Coupled Radio-Frequency Argon-Helium Discharges

    DTIC Science & Technology

    2013-06-01

    University published a paper that showed that the excited states of the noble gases can be used to form an analogous laser system to the DPAL. Dr...Another method for studying the population of a certain excited state is Tunable Diode Laser Absorption Spectroscopy (TDLAS). This method uses a laser ...four level lasers in a myriad of different transitions. The drawback is in the complicated kinetics of the excited states in the discharge and the

  15. Interaction of Angeli's salt with cytochrome P450 1A2 distal mutants: an optical absorption spectral study.

    PubMed

    Shibata, Y; Sato, H; Sagami, I; Shimizu, T

    1997-11-14

    Angeli's salt, Na2N2O3 or O-N=N+-(OH)(O-) in aqueous solution, is known to release NO- or NO., which relaxes vascular tissue and lowers blood pressure. In the liver, the most abundant heme enzyme is cytochrome P450. In the present study, we studied the effect of rat liver cytochrome P450 1A2 (P450 1A2) in regard to its catalysis of the N=N bond scission of Angeli's salt with optical absorption spectra. Also, we examined the contribution of putative distal amino acids of P450 1A2 to the reaction with the salt. We found that wild-type Fe3+ P450 1A2 markedly enhances the N=N scission of the salt up to 100 fold in terms of absorption spectroscopy. A Fe3+ P450 1A2-NO complex with an absorption peak at 435 nm was formed when the salt was added and the complex was then changed to a 6-coordinated Fe2+-NO complex having a 440-nm peak. Glu318Asp, Glu318Ala and Thr319Ala mutants at the putative distal site of P450 1A2 formed a 5-coordinated Fe2+-NO complex having a 400-nm absorption, that was not formed with the wild type. The Glu318Ala mutant, in particular, did not form the Fe3+-NO complex with the addition of Angeli's salt. The presence of L-Cys, reduced glutathione, catalase or superoxide dismutase markedly stabilized the Fe3+ wild type-NO complex. Thus, our data suggests that the N=N bond of Angeli's salt is cleaved with the P450 1A2 active site and NO- or NO. is released. We discuss mechanisms of redox and ligand changes of the P450 heme.

  16. Effect of a progressive sound wave on the profiles of spectral lines. 2: Asymmetry of faint Fraunhofer lines. [absorption spectra

    NASA Technical Reports Server (NTRS)

    Kostyk, R. I.

    1974-01-01

    The absorption coefficient profile was calculated for lines of different chemical elements in a medium with progressive sound waves. Calculations show that (1) the degree and direction of asymmetry depend on the atomic ionization potential and the potential of lower level excitation of the individual line; (2) the degree of asymmetry of a line decreases from the center toward the limb of the solar disc; and (3) turbulent motions 'suppress' the asymmetry.

  17. Age-Related Changes to Spectral Voice Characteristics Affect Judgments of Prosodic, Segmental, and Talker Attributes for Child and Adult Speech

    ERIC Educational Resources Information Center

    Dilley, Laura C.; Wieland, Elizabeth A.; Gamache, Jessica L.; McAuley, J. Devin; Redford, Melissa A.

    2013-01-01

    Purpose: As children mature, changes in voice spectral characteristics co-vary with changes in speech, language, and behavior. In this study, spectral characteristics were manipulated to alter the perceived ages of talkers' voices while leaving critical acoustic-prosodic correlates intact, to determine whether perceived age differences were…

  18. Ultraviolet Broad Absorption Features and the Spectral Energy Distribution of the QSO PG 1351+641. 2.5

    NASA Technical Reports Server (NTRS)

    Zheng, W.; Kriss, G. A.; Wang, J. X.; Brotherton, M.; Oegerle, W. R.; Blair, W. P.; Davidsen, A. F.; Green, R. F.; Hutchings, J. B.; Kaiser, M. E.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We present a moderate-resolution (approximately 20 km/s) spectrum of the broad-absorption line QSO PG 1351+64 between 915-1180 angstroms, obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). Additional low-resolution spectra at longer wavelengths were also obtained with the Hubble Space Telescope (HST) and ground-based telescopes. Broad absorption is present on the blue wings of C III lambda977, Ly-beta, O VI lambda-lambda-1032,1038, Ly-alpha, N V lambda-lambda-1238,1242, Si IV lambda-lambda-1393,1402, and C IV lambda-lambda-1548,1450. The absorption profile can be fitted with five components at velocities of approximately -780, -1049, -1629, -1833, and -3054 km/s with respect to the emission-line redshift of z = 0.088. All the absorption components cover a large fraction of the continuum source as well as the broad-line region. The O VI emission feature is very weak, and the O VI/Ly-alpha flux ratio is 0.08, one of the lowest among low-redshift active galaxies and QSOs. The ultraviolet continuum shows a significant change in slope near 1050 angstroms in the restframe. The steeper continuum shortward of the Lyman limit extrapolates well to the observed weak X-ray flux level. The absorbers' properties are similar to those of high-redshift broad absorption-line QSOs. The derived total column density of the UV absorbers is on the order of 10(exp 21)/s, unlikely to produce significant opacity above 1 keV in the X-ray. Unless there is a separate, high-ionization X-ray absorber, the QSO's weak X-ray flux may be intrinsic. The ionization level of the absorbing components is comparable to that anticipated in the broad-line region, therefore the absorbers may be related to broad-line clouds along the line of sight.

  19. Ultraviolet Broad Absorption Features and the Spectral Energy Distribution of the QSO PG 1351+64. 3.1

    NASA Technical Reports Server (NTRS)

    Zheng, W.; Kriss, G. A.; Wang, J. X.; Brotherton, M.; Oegerle, W. R.; Blair, W. P.; Davidsen, A. F.; Green, R. F.; Hutchings, J. B.; Kaiser, M. E.; Fisher, R. (Technical Monitor)

    2001-01-01

    We present a moderate-resolution (approximately 20 km s(exp -1) spectrum of the mini broad absorption line QSO PG 1351+64 between 915-1180 A, obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). Additional low-resolution spectra at longer wavelengths were also obtained with the Hubble Space Telescope (HST) and ground-based telescopes. Broad absorption is present on the blue wings of C III (lambda)977, Ly(beta), O VI (lambda)(lambda)1032,1038, Ly(alpha), N V (lambda)(lambda)1238,1242, Si IV (lambda)(lambda)1393,1402, and C IV (lambda)(lambda)1548,1450. The absorption profile can be fitted with five components at velocities of approximately -780, -1049, -1629, -1833, and -3054 km s(exp -1) with respect to the emission-line redshift of z = 0.088. All the absorption components cover a large fraction of the continuum source as well as the broad-line region. The O VI emission feature is very weak, and the O VI/Ly(alpha) flux ratio is 0.08, one of the lowest among low-redshift active galaxies and QSOs. The UV (ultraviolet) continuum shows a significant change in slope near 1050 A in the restframe. The steeper continuum shortward of the Lyman limit extrapolates well to the observed weak X-ray flux level. The absorbers' properties are similar to those of high-redshift broad absorption-line QSOs. The derived total column density of the UV absorbers is on the order of 10(exp 21) cm(exp -2), unlikely to produce significant opacity above 1 keV in the X-ray. Unless there is a separate, high-ionization X-ray absorber, the QSO's weak X-ray flux may be intrinsic. The ionization level of the absorbing components is comparable to that anticipated in the broad-line region, therefore the absorbers may be related to broad-line clouds along the line of sight.

  20. An experimental study of the electronic absorption and fluorescence spectral properties of new p-substituted-N-phenylpyrroles and their electrosynthesized polymers.

    PubMed

    Diaw, A K D; Gningue-Sall, D; Yassar, A; Brochon, J-C; Henry, E; Aaron, J-J

    2015-01-25

    Electronic absorption and fluorescence spectral properties of new p-substituted-N-phenylpyrroles (N-PhPys), including HOPhPy, MeOPhPy, ThPhPy, PhDPy, DPhDPy, PyPhThThPhPy, and their available, electrosynthesized polymers were investigated. Electronic absorption spectra, fluorescence excitation and emission spectra, fluorescence quantum yields (ΦF) and lifetimes (τF), and other photophysical parameters of these N-PhPy derivatives and their polymers were measured in DMF, DMSO diluted solutions and/or solid state at room temperature. The electronic absorption spectra of N-PhPy derivatives and their polymers included one to several bands, located in the 270-395 nm region, according to the p-phenyl substituent electron-donating effect and conjugated heteroaromatic system length. The fluorescence excitation spectra were characterized by one broad main peak, with, in most cases, one (or more) poorly resolved shoulder (s), appearing in the 270-405 nm region, and their emission spectra were generally constituted of several bands located in the 330-480 nm region. No significant shift of the absorption, fluorescence excitation and emission spectra wavelengths was found upon going from the monomers to the corresponding polymers. ΦF values were high, varying between 0.11 and 0.63, according to the nature of substituents(s) and to the conjugated system extension. Fluorescence decays were mono-exponential for the monomers and poly-exponential for PyPhThThPhPy and for polymers. τF values were relatively short (0.35-5.17 ns), and markedly decreased with the electron-donor character of the phenyl group p-substituent and the conjugated system extension.

  1. [Characteristics of urea 15N absorption, allocation, and utilization by sweet-cherry (Prunus avium L.)].

    PubMed

    Zhao, Feng-Xia; Jiang, Yuan-Mao; Peng, Fu-Tian; Gao, Xiang-Bin; Liu, Bing-Hua; Wang, Hai-Yun; Zhao, Lin

    2008-03-01

    With five-year old 'Zaodaguo' sweet-cherry (Prunus avium L.) as test material, this paper studied the characteristics of its urea 15N absorption, allocation, and utilization when applied before bud-break. The results showed that the Ndff of different organs increased gradually with time, and was higher in fine roots and storage organs at full-blooming stage. At fruit core-hardening stage, the Ndff of long shoots and leaves increased quickly, reaching to 0.72% and 0.59% , respectively. From fruit core-hardening to harvesting stage, the Ndff of fruit had a rapid increase, with the peak (1.78%) at harvesting stage. After harvest, the Ndff of neonatal organs increased slowly while that of storage organs increased quickly. At full-blooming stage, the absorbed 15N in roots was firstly allocated to storage organs, with the highest allocation rate (54.91%) in large roots. At fruit core-hardening stage, the allocation rate in fine roots and storage organs decreased from 85.43% to 55.11%, while that in neonatal branches and leaves increased to 44.89%. At harvesting stage, the allocation rate in different organs had no significant change, but after harvest, the absorbed 15N had a rapid translocation to storage organs, and the allocation rate in fine roots and storage organs reached the highest (72.26%) at flower bud differentiation stage. The 15N allocation rate in neonatal branches and leaves at flower bud differentiation stage was decreased by 19.31%, compared with that at harvesting stage. From full-blooming to flower bud differentiation stage, the utilization rate of urea 15N was increasing, and reached the peak (16.86%) at flower bud differentiation stage.

  2. Acoustic and spectral characteristics of young children's fricative productions: A developmental perspective

    NASA Astrophysics Data System (ADS)

    Nissen, Shawn L.; Fox, Robert Allen

    2005-10-01

    Scientists have made great strides toward understanding the mechanisms of speech production and perception. However, the complex relationships between the acoustic structures of speech and the resulting psychological percepts have yet to be fully and adequately explained, especially in speech produced by younger children. Thus, this study examined the acoustic structure of voiceless fricatives (/f, θ, s, /sh/) produced by adults and typically developing children from 3 to 6 years of age in terms of multiple acoustic parameters (durations, normalized amplitude, spectral slope, and spectral moments). It was found that the acoustic parameters of spectral slope and variance (commonly excluded from previous studies of child speech) were important acoustic parameters in the differentiation and classification of the voiceless fricatives, with spectral variance being the only measure to separate all four places of articulation. It was further shown that the sibilant contrast between /s/ and /sh/ was less distinguished in children than adults, characterized by a dramatic change in several spectral parameters at approximately five years of age. Discriminant analysis revealed evidence that classification models based on adult data were sensitive to these spectral differences in the five-year-old age group.

  3. Pressure influence on the structural characteristics of modified absorptive glass mat separators: A standard contact porosimetry study

    NASA Astrophysics Data System (ADS)

    Burashnikova, M. M.; Khramkova, T. S.; Kazarinov, I. A.; Shmakov, S. L.

    2015-09-01

    The article presents a comparative analysis of the structural characteristics of absorptive glass mats manufactured by "Hollingsworth & Vose" (a 2.8 mm thickness) and "Bernard Dumas" (a 3.0 mm thickness) modified by impregnation with polymeric emulsions based on polyvinylidene fluoride, a polyvinylpyrrolidone styrene copolymer, and polytetrafluoroethylene, by means of standard contact porosimetry. The key study is influence of features of the porous structure on the compression properties, the rate of wicking, and the oxygen cycle efficiency in lead-acid battery mock-ups under several plate-group compression pressures. It is found that the treatment of the absorptive glass mat separators with polymeric emulsions leads to redistribution of their pores by size. An increased pressure in the electrode unit insignificantly changes the pore structure of the modified absorptive glass mat separators, and the oxygen cycle efficiency rises in comparison with unmodified separators.

  4. [Study on spectral characteristics of third-order harmonic emission of plasma channels in atmosphere].

    PubMed

    Li, Hai-ning; Zhang, Li-ping; Wu, Hong; Li, Xian; Ding, Liang-en

    2008-06-01

    . Studies on spectral characteristics of the third-order harmonic emission in plasma channels at atmosphere are very useful to developing the technology of tuning the radiation in generation of ultraviolet or even soft X-ray domain.

  5. Spectral characteristics of mid-latitude continental convection from a global variable-resolution Voronoi-mesh atmospheric model

    NASA Astrophysics Data System (ADS)

    Wong, M.; Skamarock, W. C.

    2015-12-01

    Global numerical weather forecast tests were performed using the global nonhydrostatic atmospheric model, Model for Prediction Across Scales (MPAS), for the NOAA Storm Prediction Center 2015 Spring Forecast Experiment (May 2015) and the Plains Elevated Convection at Night (PECAN) field campaign (June to mid-July 2015). These two sets of forecasts were performed on 50-to-3 km and 15-to-3 km smoothly-varying horizontal meshes, respectively. Both variable-resolution meshes have nominal convection-permitting 3-km grid spacing over the entire continental US. Here we evaluate the limited-area (vs. global) spectra from these NWP simulations. We will show the simulated spectral characteristics of total kinetic energy, vertical velocity variance, and precipitation during these spring and summer periods when diurnal continental convection is most active over central US. Spectral characteristics of a high-resolution global 3-km simulation (essentially no nesting) from the 20 May 2013 Moore, OK tornado case are also shown. These characteristics include spectral scaling, shape, and anisotropy, as well as the effective resolution of continental convection representation in MPAS.

  6. Spectral and Lensing Characteristics of Gel-Derived Strontium Tartrate Single Crystals Using Dual-Beam Thermal Lens Technique.

    PubMed

    Rejeena, I; Thomas, V; Mathew, S; Lillibai, B; Nampoori, V P N; Radhakrishnan, P

    2016-09-01

    The Dual Beam mode-matched thermal lens spectrometry is a sensible technique for direct measurements of the thermal properties of tartrate crystalline materials. Here we report the measurement of thermal diffusivity of Strontium Tartrate single crystals incorporated with Rhodamine 6G using the thermal lens experiment. The respective crystals were prepared by solution-gel method at room temperature. The absorption characteristics of three different Strontium Tartrate crystals viz. pure, electric field applied and magnetic field applied were also carried out.

  7. Characteristics of anomalous skin effect and evolution of power absorption regions in a cylindrical radio frequency inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Ding, Z. F.; Sun, B.; Huo, W. G.

    2015-06-01

    In a low-pressure radio-frequency (13.56 MHz), inductively coupled argon plasma generated by a normal cylindrical rf coil, electric field, current density, and absorbed power density is calculated from magnetic field measured with a phase-resolved magnetic probe. The anomalous skin effect (ASE) for the cylindrical rf coil is compared to those previously reported for the planar and re-entrant cylindrical rf coils. Physical reasons for our observed characteristics of ASE are presented. With the increasing discharge power, the size and the number of negative and positive power absorption regions evolve into several distinct patterns. For the low discharge power (at 156.9 W), there is one area of positive and one area of negative power absorption in the radial direction. For the medium discharge power (279 W-683.5 W), there are two areas of negative and two areas of positive power absorption. For the even higher discharge power (above 803.5 W), the number of areas is the same as that of the medium discharge power, but the size of the inner positive and negative power absorption areas is approximately doubled and halved, respectively, while the outer positive and negative power absorption areas slightly shrinks. The evolution of positive and negative power absorption regions is explained as a result of electron thermal diffusion and the energy conversion between rf current and electric field. The spatial decays of electric field and current density are also elucidated by linking them with the positive and negative power absorption pattern.

  8. Characteristics of anomalous skin effect and evolution of power absorption regions in a cylindrical radio frequency inductively coupled plasma

    SciTech Connect

    Ding, Z. F.; Sun, B.; Huo, W. G.

    2015-06-15

    In a low-pressure radio-frequency (13.56 MHz), inductively coupled argon plasma generated by a normal cylindrical rf coil, electric field, current density, and absorbed power density is calculated from magnetic field measured with a phase-resolved magnetic probe. The anomalous skin effect (ASE) for the cylindrical rf coil is compared to those previously reported for the planar and re-entrant cylindrical rf coils. Physical reasons for our observed characteristics of ASE are presented. With the increasing discharge power, the size and the number of negative and positive power absorption regions evolve into several distinct patterns. For the low discharge power (at 156.9 W), there is one area of positive and one area of negative power absorption in the radial direction. For the medium discharge power (279 W–683.5 W), there are two areas of negative and two areas of positive power absorption. For the even higher discharge power (above 803.5 W), the number of areas is the same as that of the medium discharge power, but the size of the inner positive and negative power absorption areas is approximately doubled and halved, respectively, while the outer positive and negative power absorption areas slightly shrinks. The evolution of positive and negative power absorption regions is explained as a result of electron thermal diffusion and the energy conversion between rf current and electric field. The spatial decays of electric field and current density are also elucidated by linking them with the positive and negative power absorption pattern.

  9. Investigation of the mica x-ray absorption near-edge structure spectral features at the Al K-edge

    NASA Astrophysics Data System (ADS)

    Wu, Ziyu; Marcelli, A.; Cibin, G.; Mottana, A.; Della Ventura, G.

    2003-10-01

    Near-edge features of Al x-ray absorption near-edge structure (XANES) spectra in aluminosilicate compounds with mixed coordination number are usually assigned to a fourfold coordinated site contribution followed by a sixfold coordinated site contribution that is displaced towards higher energy because of the increasing ligand nucleus potentials, neglecting possible contributions due to bond distance variations and local geometrical distortion. Here we present and discuss the Al K-edge XANES spectra of synthetic micas with either fourfold coordinated Al (phlogopite), or with sixfold coordinated Al (polylithionite), as well as with mixed coordination (preiswerkite). Multiple scattering simulations of XANES spectra demonstrate that octahedral contributions may overlap the tetrahedral ones so that the lower energy structures in mixed coordination compounds may be associated with the octahedral sites. This unexpected behaviour can be described as due to the effect of a significant reduction of the ligand field strength (i.e. large local distortion and Al-O bond distances).

  10. AVIRIS data characteristics and their effects on spectral discrimination of rocks exposed in the Drum Mountains, Utah: Results of a preliminary study

    NASA Technical Reports Server (NTRS)

    Bailey, G. B.; Dwyer, J. L.; Meyer, D. J.

    1988-01-01

    Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) data collected over a geologically diverse field site and over a nearby calibration site were analyzed and interpreted in efforts to document radiometric and geometric characteristics of AVIRIS, quantify and correct for detrimental sensor phenomena, and evaluate the utility of AVIRIS data for discriminating rock types and identifying their constituent mineralogy. AVIRIS data acquired for these studies exhibit a variety of detrimental artifacts and have lower signal-to-noise ratios than expected in the longer wavelength bands. Artifacts are both inherent in the image data and introduced during ground processing, but most may be corrected by appropriate processing techniques. Poor signal-to-noise characteristics of this AVIRIS data set limited the usefulness of the data for lithologic discrimination and mineral identification. Various data calibration techniques, based on field-acquired spectral measurements, were applied to the AVIRIS data. Major absorption features of hydroxyl-bearing minerals were resolved in the spectra of the calibrated AVIRIS data, and the presence of hydroxyl-bearing minerals at the corresponding ground locations was confirmed by field data.

  11. Spectral characteristics of high-power 1. 5. mu. m broad-band superluminescent fiber sources

    SciTech Connect

    Wysocki, P.F.; Digonnet, M.J.F.; Kim, B.Y. . Edward L. Ginzton Lab.)

    1990-03-01

    The authors study the spectral variation of spontaneous emission from erbium-doped single-mode fibers with the aim of producing high-power (more than 5 mW), broad-band (in excess of 10 nm) amplified spontaneous emission sources for fiber gyroscope applications. In particular, they demonstrate the evolution of spectral shape and center wavelength with fiber length and output power in the previously unstudied high-power regime where saturation effects dominate. Also presented is a visibility curve for a potential twin-peaked nonresonant erbium-doped fiber gyroscope source with a short (210 {mu}m) coherence length.

  12. Effect of a pulsed power supply on the spectral and electrical characteristics of HID lamps

    NASA Astrophysics Data System (ADS)

    Chammam, Abdeljelil; Elloumi, Hatem; Mrabet, Brahim; Charrada, Kamel; Stambouli, Mongi; Damelincourt, Jean Jacques

    2005-04-01

    Results of spectral and photometric measurements are presented for pulsed power operated high intensity discharges (HIDs). This investigation is related to the application of a pulsed power supply for pile driving of HID lamps. Specifically, we are interested in controlling the spectral response radiation of visible and ultraviolet (UV) lines for tertiary treatment of water using UV radiation. Simulations based on a physical model of the lamps were conducted. These results relate to the radial temperature, line intensity and electrical properties (voltage, power and conductivity). Good agreement has been found between the results of the simulations and the experimental findings.

  13. Analysis of the Spectral Characteristics of Pure Moxa Stick Burning by Hyperspectral Imaging and Fourier Transform Infrared Spectroscopy

    PubMed Central

    Li, Yin-long

    2016-01-01

    The objective of this study was to investigate the spectra characteristics (SC) at wavelengths of 400~1000 nm and 2.5~15.5 μm of pure moxa stick (MS) during its 25-minute burning process using new spectral imaging techniques. Spectral images were collected for the burning pure MS at 5, 10, 15, 20, and 25 min using hyperspectral imaging (HSI) and Fourier transform infrared spectroscopy (FTIR) for the first time. The results showed that, at wavelengths of 400~1000 nm, the spectral range of the cross section of MS burning was 750~980 nm; the peak position was 860 nm. At wavelengths of 2.5~15.5 μm, the spectral range of the cross section of MS burning was 3.0~4.0 μm; the peak position was approximately 3.5 μm. The radiation spectra of MS burning include litter red and amount of infrared (but mainly near infrared) wavelengths. The temperature, blood perfusion, and oxygen saturation increase of Shenshu (BL23) after moxibustion radiation were observed too. According to mechanism of photobiological effects and moxibustion biological effects, it was inferred that moxibustion effects should be linked with moxibustion SC. This study provided new data and means for physical properties of moxibustion research. PMID:27721889

  14. Environmental Processes and Spectral Reflectance Characteristics Associated with Soil Erosion in Desert Fringe Regions

    NASA Technical Reports Server (NTRS)

    Jacobberger, P. A.

    1987-01-01

    Results of analysis of spectral variation of sand dunes in El Ghorabi, Bahariya, Egypt; Tombouctou/Azaouad, Mali; and Tsodilo Hills, western Botswana are presented. Seasonal variations in dune extent and location of dune crests and their relationship to such factors as wind and weather variations are emphasized.

  15. Absorption and emission spectral shapes of a prototype dye in water by combining classical/dynamical and quantum/static approaches.

    PubMed

    Petrone, Alessio; Cerezo, Javier; Ferrer, Francisco J Avila; Donati, Greta; Improta, Roberto; Rega, Nadia; Santoro, Fabrizio

    2015-05-28

    We study the absorption and emission electronic spectra in an aqueous solution of N-methyl-6-oxyquinolinium betaine (MQ), an interesting dye characterized by a large change of polarity and H-bond ability between the ground (S0) and the excited (S1) states. To that end we compare alternative approaches based either on explicit solvent models and density functional theory (DFT)/molecular-mechanics (MM) calculations or on DFT calculations on clusters models embedded in a polarizable continuum (PCM). In the first approach (ClMD), the spectrum is computed according to the classical Franck-Condon principle, from the dispersion of the time-dependent (TD)-DFT vertical transitions at selected snapshots of molecular dynamics (MD) on the initial state. In the cluster model (Qst) the spectrum is simulated by computing the quantum vibronic structure, estimating the inhomogeneous broadening from state-specific TD-DFT/PCM solvent reorganization energies. While both approaches provide absorption and emission spectral shapes in nice agreement with experiment, the Stokes shift is perfectly reproduced by Qst calculations if S0 and S1 clusters are selected on the grounds of the MD trajectory. Furthermore, Qst spectra better fit the experimental line shape, mostly in absorption. Comparison of the predictions of the two approaches is very instructive: the positions of Qst and ClMD spectra are shifted due to the different solvent models and the ClMD spectra are narrower than the Qst ones, because MD underestimates the width of the vibrational density of states of the high-frequency modes coupled to the electronic transition. On the other hand, both Qst and ClMD approaches highlight that the solvent has multiple and potentially opposite effects on the spectral width, so that the broadening due to solute-solvent vibrations and electrostatic interaction with bulk solvent is (partially) counterbalanced by a narrowing of the contribution due to the solute vibrational modes. Qst analysis

  16. Microwave absorption characteristics of the clouds of Venus from Mariner 10 radio occultation

    NASA Technical Reports Server (NTRS)

    Kliore, A. J.; Elachi, C.; Patel, I. R.; Way, J. B.

    1977-01-01

    Measurements of received signal strength at S-band (13 cm) and X-band (4.8 cm) wavelengths during the radio occultation of Mariner 10 by Venus on February 5, 1974, are examined in order to study the structure and composition of the absorbing medium. The frequency excursions of the signals are determined and used to obtain the structure of the refractive index in the lower atmosphere. Profiles of excess signal attenuation due to atmospheric scattering and absorption are presented which indicate that the X-band signal experienced much more absorption and was extinguished at about 50 km, while the S-band signal penetrated to about 42 km. The optical-depth data are inverted by means of a discrete inversion method to obtain the absorption coefficient for each band as a function of height, and the resulting absorption-coefficient profiles are compared with the attenuation at vertical incidence modeled from planetary radar and passive microwave observations of Venus. The absorption coefficients at the two wavelengths are employed to estimate the liquid content and composition of the microwave-absorbing cloud particles.

  17. Absorption characteristics of aerosols over the northwestern region of India: Distinct seasonal signatures of biomass burning aerosols and mineral dust

    NASA Astrophysics Data System (ADS)

    Gogoi, Mukunda M.; Suresh Babu, S.; Krishna Moorthy, K.; Manoj, M. R.; Chaubey, Jai Prakash

    2013-07-01

    Continuous measurements of aerosol black carbon (BC) mass concentrations made over a period of 3 years from a semi-arid, near-coastal, remote and sparsely inhabited location along with satellite-based data of aerosol absorption index, optical depth and extinction profiles in western India are used to characterize the distinct nature of aerosols near the surface and in the free troposphere and their seasonality. Despite being far remote and sparsely inhabited, significant levels of BC are observed in the ambient during winter (1.45 ± 0.71 μg m-3) attributed to biomass burning aerosols, advected to the site from the north and west; while during summer the concentrations are far reduced (0.23 ± 0.11 μg m-3) and represent the apparent background concentrations. The spectral absorption coefficients suggest the BC during summer be mostly of fossil fuel combustions. The strong convective boundary layer dynamics produces significant diurnal variation during winter and modulates to a lesser extent the seasonal variation. Examination of aerosol (absorption) index from OMI data for the study period showed a seasonal pattern that is almost opposite to that seen at the surface; with high aerosol index in summer, showing a significant difference between the surface and columnar aerosol types in summer. MISR and MODIS-derived columnar AOD follow the OMI pattern. Analysis of the vertical profiles of aerosol extinction and volume depolarization ratio (VDR), derived from CALIPSO data indicates the presence of strong dust layers with VDR ˜ 0.3 in the altitude region 4-6 km, contributing to the high aerosol index in the OMI data, while the surface measurements show absorptive properties representing fossil fuel BC aerosols.

  18. Optical nonlinear absorption characteristics of Sb{sub 2}Se{sub 3} nanoparticles

    SciTech Connect

    Muralikrishna, Molli Kiran, Aditha Sai Ravikanth, B. Sowmendran, P. Muthukumar, V. Sai Venkataramaniah, Kamisetti

    2014-04-24

    In this work, we report for the first time, the nonlinear optical absorption properties of antimony selenide (Sb{sub 2}Se{sub 3}) nanoparticles synthesized through solvothermal route. X-ray diffraction results revealed the crystalline nature of the nanoparticles. Electron microscopy studies revealed that the nanoparticles are in the range of 10 - 40 nm. Elemental analysis was performed using EDAX. By employing open aperture z-scan technique, we have evaluated the effective two-photon absorption coefficient of Sb{sub 2}Se{sub 3} nanoparticles to be 5e-10 m/W at 532 nm. These nanoparticles exhibit strong intensity dependent nonlinear optical absorption and hence could be considered to have optical power limiting applications in the visible range.

  19. Atmospheric solar absorption measurements in the 9-11 micron region using a diode laser heterodyne spectrometer

    NASA Technical Reports Server (NTRS)

    Harward, C. N.; Hoell, J. M., Jr.

    1980-01-01

    A tunable diode laser heterodyne radiometer was developed for ground based measurements of atmospheric solar absorption spectra in the 9 to 12 micron spectral range. The performance and operating characteristics of this tunable infrared heterodyne radiometer (TIHR) is discussed along with recently measured heterodyne solar absorption spectra in the 10 to 11 micron spectral region.

  20. Spectral linewidth and resonant frequency characteristics of InGaAsP/InP multiquantum well lasers

    SciTech Connect

    Sasai, Y.; Ohya, J.; Ogura, M.

    1989-04-01

    The spectral linewidth and resonant frequency characteristics of 1.3 ..mu..m InGaAsP/InP multiquantum well (MQW) lasers grown by liquid phase epitaxy (LPE) were investigated, compared to those of the conventional double heterostructure (DH) lasers. The result showed a decrease in spectral linewidth and an increase in resonant frequency f/sub r/ with decreasing well thickness. Moreover, it was recognized that the linewidth enhancement factor became smaller in well thicknesses of less than -- 200 A, namely, the factor ..cap alpha.. reduced to -- 2, while that of the DH laser was -- 6. The f/sub r/ of 9 GHz, which is about twice as large as that of conventional DH lasers, was achieved at an optical power of 5.3 mW/facet.

  1. Spectral characteristics and meridional variations of energy transformations during the first and second special observation periods of FGGE

    NASA Technical Reports Server (NTRS)

    Kung, E. C.; Tanaka, H.

    1984-01-01

    The global features and meridional spectral energy transformation variations of the first and second special observation periods of the First Global GARP Experiment (FGGE) are investigated, together with the latitudinal distribution of the kinetic energy balance. Specific seasonal characteristics are shown by the spectral distributions of the global transformations between (1) zonal mean and eddy components of the available potential energy, (2) the zonal mean and eddy components of the kinetic energy, and (3) the available potential energy and the kinetic energy. Maximum kinetic energy production is found to occur at subtropical latitudes, with a secondary maximum at higher middle latitudes. Between these two regions, there is another region characterized by the adiabatic destruction of kinetic energy above the lower troposphere.

  2. Spectral characteristics of scintillations producing ionospheric irregularities in the Indian region

    NASA Astrophysics Data System (ADS)

    Banola, S.; Pathan, B. M.; Rao, D. R. K.; Chandra, H.

    2005-01-01

    VHF amplitude scintillations were recorded at Tirunelveli (8.7°N, 77.7°E; 0.6°N dip Latitude), Pondicherry (12°N, 79.1°E; 4.4°N dip Latitude) and Mumbai, (19°N, 73°E; 13.5°N dip Latitude) for the years 1992-1996 using the 250 MHz radio beacon from the geostationary satellite FLEETSAT (7°E). The recorded digital scintillation data for few nights are analyzed to estimate scintillation index (S4), fade rates, auto-correlation functions and power spectral densities for every 2.5 minute sample during the period of the scintillation activity. The power spectral slopes are shallower for the scintillation at the generation phase and steeper towards the decay phase, which indicates the erosion of smaller scale sizes towards the decay phase.

  3. Study of Spectral/Radiometric Characteristics of the Thematic Mapper for Land Use Applications

    NASA Technical Reports Server (NTRS)

    Malila, W. A. (Principal Investigator); Metzler, M. D. (Principal Investigator)

    1985-01-01

    An investigation conducted in support of the LANDSAT 4/5 Image Data Quality Analysis (LIDQA) Program is discussed. Results of engineering analyses of radiometric, spatial, spectral, and geometric properties of the Thematic Mapper systems are summarized; major emphasis is placed on the radiometric analysis. Details of the analyses are presented in appendices, which contain three of the eight technical papers produced during this investigation; these three, together, describe the major activities and results of the investigation.

  4. Spectral characteristics of draw-tower step-chirped fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Idrisov, Ravil F.; Varzhel, Sergey V.; Kulikov, Andrey V.; Meshkovskiy, Igor K.; Rothhardt, Manfred; Becker, Martin; Schuster, Kay; Bartelt, Hartmut

    2016-06-01

    This paper presents research results on the spectral properties of step-chirped fiber Bragg grating arrays written during the fiber drawing process into a birefringent optical fiber with an elliptical stress cladding. The dependences of resonance shift of the step-chirped fiber Bragg grating on bending, on applied tensile stress and on temperature have been investigated. A usage of such step-chirped fiber Bragg gratings in fiber-optic sensing elements creation has been considered.

  5. Defect assisted saturable absorption characteristics in Al and Li doped ZnO thin films

    NASA Astrophysics Data System (ADS)

    K. M., Sandeep; Bhat, Shreesha; S. M., Dharmaprakash; P. S., Patil; Byrappa, K.

    2016-09-01

    The influence of different doping ratios of Al and Li on the nonlinear optical properties, namely, a two-photon absorption and a nonlinear refraction using single beam Z-scan technique, of nano-crystalline ZnO thin films has been investigated in the present study. A sol-gel spin-coated pure ZnO, Al-doped ZnO (AZO), and Li-doped ZnO (LZO) thin films have been prepared. The stoichiometric deviations induced by the occupancy of Al3+ and Li+ ions at the interstitial sites injects the compressive stress in the AZO and LZO thin films, respectively, while the extended defect states below the conduction band leads to a redshift of energy band gap in the corresponding films as compared to pure ZnO thin film. Switching from an induced absorption in ZnO and 1 at. wt. % doped AZO and LZO films to a saturable absorption (SA) in 2 at. wt. % doped AZO and LZO films has been observed, and it is attributed to the saturation of a linear absorption of the defect states. The closed aperture Z-scan technique revealed the self-focusing (a positive nonlinear refractive index) in all the films, which emerge out of the thermo-optical effects due to the continuous illumination of laser pulses. A higher third-order nonlinear optical susceptibility χ(3) of the order 10-3 esu has been observed in all the films.

  6. Multidimensional scaling of synthetic musical timbre: perception of spectral and temporal characteristics.

    PubMed

    Samson, S; Zatorre, R J; Ramsay, J O

    1997-12-01

    The perceptual correlates of acoustic parameters involved in musical timbre were investigated by examining judgements of timbre dissimilarity. Nine synthetic sounds were created, derived from crossing three levels of spectral and temporal parameters (number of harmonics and rise time, respectively). Two separate conditions were tested, one using single tones, the other using short melodies. Fifteen musically untrained subjects were presented with pairs of stimuli and asked to judge dissimilarity on an 8-point scale. The spatial configuration resulting from multidimensional analysis of the data was best fit by a three-dimensional model, with the first two dimensions accounting for most of the variance. The perceptual space derived from the analysis indicates that these two orthogonal dimensions corresponded closely to the spectral and temporal differences inherent to the stimuli. Similar results were obtained with both melodies and single tones. A second experiment replicated the findings despite the introduction of random loudness variation, indicating that timbre judgements can be made independently of loudness. We conclude that even musically unselected subjects are sensitive to spectral and temporal information in musical tones, and are able to use them independently in making perceptual judgements of musical timbre.

  7. Time- and spectrally resolved characteristics of flavin fluorescence in U87MG cancer cells in culture

    NASA Astrophysics Data System (ADS)

    Horilova, Julia; Cunderlikova, Beata; Marcek Chorvatova, Alzbeta

    2015-05-01

    Early detection of cancer is crucial for the successful diagnostics of its presence and its subsequent treatment. To improve cancer detection, we tested the progressive multimodal optical imaging of U87MG cells in culture. A combination of steady-state spectroscopic methods with the time-resolved approach provides a new insight into the native metabolism when focused on endogenous tissue fluorescence. In this contribution, we evaluated the metabolic state of living U87MG cancer cells in culture by means of endogenous flavin fluorescence. Confocal microscopy and time-resolved fluorescence imaging were employed to gather spectrally and time-resolved images of the flavin fluorescence. We observed that flavin fluorescence in U87MG cells was predominantly localized outside the cell nucleus in mitochondria, while exhibiting a spectral maximum under 500 nm and fluorescence lifetimes under 1.4 ns, suggesting the presence of bound flavins. In some cells, flavin fluorescence was also detected inside the cell nuclei in the nucleoli, exhibiting longer fluorescence lifetimes and a red-shifted spectral maximum, pointing to the presence of free flavin. Extra-nuclear flavin fluorescence was diminished by 2-deoxyglucose, but failed to increase with 2,4-dinitrophenol, the uncoupler of oxidative phosphorylation, indicating that the cells use glycolysis, rather than oxidative phosphorylation for functioning. These gathered data are the first step toward monitoring the metabolic state of U87MG cancer cells.

  8. Comparison of DTR spectral-angular characteristics of divergent beam of relativistic electrons in scattering geometry of Laue and Bragg

    NASA Astrophysics Data System (ADS)

    Blazhevich, S. V.; Koskova, T. V.; Ligidov, A. Z.; Noskov, A. V.

    2016-07-01

    Diffracted transition radiation (DTR) generated by a divergent beam of relativistic electrons crossing a single-crystal plate in different (Laue, Bragg) scattering geometry has been considered for the general case of asymmetric reflection of the electron coulomb field relative to the entrance target surface. The expressions for spectral-angular density of DTR and parametric X-ray Radiation (PXR) has been derived. Then DTR and PXR has been considered in case of a thin target, when multiple scattering of electron is negligibly small, which is important for divergence measurement in real time regime. Numerical calculation of spectral-angular density of DTR by a beam of relativistic electrons has been made using averaging over the bivariate Gauss distribution as angular distribution of relativistic electrons in the beam. It has been shown that in Bragg scattering geometry the angular density of DTR is bigger, than in Laue geometry, which can be explained by the existence of the frequency range, in which the incident wave propagation vector takes complex value even under absence of absorption. In this range, all of photons are reflected in Bragg direction. It means that the range of total reflection defines the width of DTR spectrum.

  9. Spectral-luminescent and photochemical characteristics of homodimers of the styrylcyanine dye Sbt in solutions.

    PubMed

    Kurtaliev, Eldar N

    2011-10-15

    The influence of concentration, solvent nature on the intermolecular interaction and its spectroscopic manifestations in solutions of styrylcyanine dye Sbt ((E)-2-(4-(dimethylamino)styryl)-3-methylbenzo[d]thiazol-3-ium iodide) and its homodimers, i.e. dyes with two interconnected chromophores, was studied. It was found out that, depending on the concentration, the structure of dye molecules, the nature of the solvent various forms of associated molecules are forms; each of these forms is manifested in the spectra of absorption and fluorescence in its own way. It is shown that the intensity of the main absorption band of the studied dyes in aqueous solutions and in a mixture of water+ethanol decreases in the process of light irradiation and a new band is observed in the region of shorter wavelengths; the intensity of the new band increases with increase of radiation exposure of solutions.

  10. Using Finite Element and Eigenmode Expansion Methods to Investigate the Periodic and Spectral Characteristic of Superstructure Fiber Bragg Gratings

    PubMed Central

    He, Yue-Jing; Hung, Wei-Chih; Lai, Zhe-Ping

    2016-01-01

    In this study, a numerical simulation method was employed to investigate and analyze superstructure fiber Bragg gratings (SFBGs) with five duty cycles (50%, 33.33%, 14.28%, 12.5%, and 10%). This study focuses on demonstrating the relevance between design period and spectral characteristics of SFBGs (in the form of graphics) for SFBGs of all duty cycles. Compared with complicated and hard-to-learn conventional coupled-mode theory, the result of the present study may assist beginner and expert designers in understanding the basic application aspects, optical characteristics, and design techniques of SFBGs, thereby indirectly lowering the physical concepts and mathematical skills required for entering the design field. To effectively improve the accuracy of overall computational performance and numerical calculations and to shorten the gap between simulation results and actual production, this study integrated a perfectly matched layer (PML), perfectly reflecting boundary (PRB), object meshing method (OMM), and boundary meshing method (BMM) into the finite element method (FEM) and eigenmode expansion method (EEM). The integrated method enables designers to easily and flexibly design optical fiber communication systems that conform to the specific spectral characteristic by using the simulation data in this paper, which includes bandwidth, number of channels, and band gap size. PMID:26861322

  11. Spectral characteristics of the iron oxides with application to the Martian bright region mineralogy

    NASA Technical Reports Server (NTRS)

    Sherman, D. M.; Burns, R. G.; Mee Burns, V.

    1982-01-01

    Reflectance spectra of eight polymorphs of FeOOH and Fe2O3 are determined in order to clarify the nature and significance of the iron oxide mineralogy on Mars. The effect of other components that might interfere with iron oxide absorption features is qualitatively constrained through the use of the Kebulka-Munk theory. It is found that the effect of temperature complicates the identification of a given Fe(3+) phase based on the position of the 6A1-4T1 absorption feature. While the Fe(3+) crystal field transitions are spin forbidden, most of the iron oxide polymorphs exhibit anomalously intense crystal field absorption features due to magnetic coupling between adjacent FeO6 octahedra. It is suggested that the resulting deviations from observed remotely sensed reflectance spectra of Mars may provide a basis for the exclusion of many iron oxide phases as significant components of the Martian Fe(3+) mineralogy. A comparison of these results with the visible region spectra of Martian bright regions indicates that the predominant Fe(3+)-bearing phase may be a magnetically disordered material, such as amorphous gels, some ferric sulphates, and other minerals in which Fe(3+) ions in the crystal structure are not magnetically coupled.

  12. Spectral characteristics of a broadband exciplex spontaneous emission source upon mixtures of the cadmium dibromide vapor with gases

    NASA Astrophysics Data System (ADS)

    Guivan, M. M.; Malinin, A. N.

    2007-03-01

    The spectral characteristics of radiation from atmospheric-pressure gas-discharge plasma in mixtures of cadmium dibromide vapor with gases (Ne, Ar, Kr, Xe, and N2), as well as the temporal characteristics of the voltage and current, have been investigated. A barrier discharge at the repetition frequency of sine voltage pulses up to 140 kHz has been used to create the gas-discharge plasma and excite the components of the working mixture. The discharge radiation has been analyzed in the spectral range 200-900 nm with a high resolution (0.05 nm). In the spectra, we have revealed radiation from exciplex molecules CdBr( B → X) and CdBr( C → X), atomic lines of cadmium and inert gases, and, in mixtures with xenon, radiation of exciplex molecules XeBr( B → X, B → A). The XeBr( B → X) radiation prevailed in the spectra at mixture temperatures up to 200°C. The further increase of the temperature resulted in the prevalence of the CdBr( B → X) radiation. The most intense CdBr( B → X) radiation was observed in mixtures of CdBr2/Xe. When the temperature of the mixture was higher than 250°C, the discharge radiation had a silvery-white color. Regularities in the spectral characteristics of the radiation from the gas-discharge plasma are discussed. The high-frequency atmospheric-pressure barrier discharge in mixtures of cadmium dibromide with gases, excited by sine voltage pulses, can be used in multiwave and broadband excilamps, operating in the UV and visible regions.

  13. Removal characteristics of CO2 using aqueous MEA/AMP solutions in the absorption and regeneration process.

    PubMed

    Choi, Won-Joon; Seo, Jong-Beom; Jang, Sang-Yong; Jung, Jong-Hyeon; Oh, Kwang-Joong

    2009-01-01

    The carbon dioxide (CO2) removal efficiency, reaction rate, and CO2 loading into aqueous blended monoethanolamine (MEA) + 2-amino-2-methyl-1-propanol (AMP) solutions to enhance absorption characteristics of MEA and AMP were carried out by the absorption/regeneration process. As a result, compared to aqueous MEA and AMP solutions, aqueous blended MEA + AMP solutions have a higher CO2 loading than MEA and a higher reaction rate than AMP. The CO2 loading of rich amine of aqueous 18 wt.% MEA + 12 wt.% AMP solution was 0.62 mol CO2/mol amine, which is 51.2% more than 30 wt.% MEA (0.41 mol CO2/mol amine). Consequently, blending MEA and AMP could be an effective way to design considering economical efficiency and used to operate absorber for a long time.

  14. Analysis of dispersion and absorption characteristics of shear waves in sinusoidally corrugated elastic medium with void pores

    PubMed Central

    Kundu, Santimoy; Gupta, Shishir

    2017-01-01

    This theoretical work reports the dispersion and absorption characteristics of horizontally polarized shear wave (SH-wave) in a corrugated medium with void pores sandwiched between two dissimilar half-spaces. The dispersion and absorption equations have been derived in a closed form using the method of separation of variables. It has been established that there are two different kinds of wavefronts propagating in the proposed media. One of the wavefronts depends on the modulus of rigidity of elastic matrix of the medium and satisfies the dispersion equation of SH-waves. The second wavefront depends on the changes in volume fraction of the pores. Numerical computation of the obtained relations has been performed and the results are depicted graphically. The influence of corrugation, sandiness on the phase velocity and the damped velocity of SH-wave has been studied extensively. PMID:28386416

  15. Analysis of dispersion and absorption characteristics of shear waves in sinusoidally corrugated elastic medium with void pores

    NASA Astrophysics Data System (ADS)

    Pandit, Deepak Kr.; Kundu, Santimoy; Gupta, Shishir

    2017-02-01

    This theoretical work reports the dispersion and absorption characteristics of horizontally polarized shear wave (SH-wave) in a corrugated medium with void pores sandwiched between two dissimilar half-spaces. The dispersion and absorption equations have been derived in a closed form using the method of separation of variables. It has been established that there are two different kinds of wavefronts propagating in the proposed media. One of the wavefronts depends on the modulus of rigidity of elastic matrix of the medium and satisfies the dispersion equation of SH-waves. The second wavefront depends on the changes in volume fraction of the pores. Numerical computation of the obtained relations has been performed and the results are depicted graphically. The influence of corrugation, sandiness on the phase velocity and the damped velocity of SH-wave has been studied extensively.

  16. Mg II Absorption Characteristics of a Volume-Limited Sample of Galaxies at z ~ 0.1

    NASA Astrophysics Data System (ADS)

    Barton, Elizabeth J.; Cooke, Jeff

    2009-12-01

    We present an initial survey of Mg II absorption characteristics in the halos of a carefully constructed, volume-limited subsample of galaxies embedded in the spectroscopic part of the Sloan Digital Sky Survey (SDSS). We observed quasars near sightlines to 20 low-redshift (z ~ 0.1), luminous (M r + 5log h <=-20.5) galaxies in SDSS DR4 and DR6 with the LRIS-B spectrograph on the Keck I telescope. The primary systematic criteria for the targeted galaxies are a redshift z gsim 0.1 and the presence of an appropriate bright background quasar within a projected 75 h -1 kpc of its center, although we preferentially sample galaxies with lower impact parameters and slightly more star formation within this range. Of the observed systems, six exhibit strong (W eq(2796) >= 0.3 Å) Mg II absorption at the galaxy's redshift, six systems have upper limits which preclude strong Mg II absorption, while the remaining observations rule out very strong (W eq(2796) >= 1-2 Å) absorption. The absorbers fall at higher impact parameters than many non-absorber sightlines, indicating a covering fraction fc lsim 0.4 for >=0.3 Å absorbers at z ~ 0.1, even at impact parameters <=35 h -1 kpc (f c ~ 0.25). The data are consistent with a possible dependence of covering fraction and/or absorption halo size on the environment or star-forming properties of the central galaxy. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  17. Mg II ABSORPTION CHARACTERISTICS OF A VOLUME-LIMITED SAMPLE OF GALAXIES AT z {approx} 0.1

    SciTech Connect

    Barton, Elizabeth J.; Cooke, Jeff E-mail: cooke@uci.edu

    2009-12-15

    We present an initial survey of Mg II absorption characteristics in the halos of a carefully constructed, volume-limited subsample of galaxies embedded in the spectroscopic part of the Sloan Digital Sky Survey (SDSS). We observed quasars near sightlines to 20 low-redshift (z {approx} 0.1), luminous (M {sub r} + 5log h {<=}-20.5) galaxies in SDSS DR4 and DR6 with the LRIS-B spectrograph on the Keck I telescope. The primary systematic criteria for the targeted galaxies are a redshift z {approx}> 0.1 and the presence of an appropriate bright background quasar within a projected 75 h {sup -1} kpc of its center, although we preferentially sample galaxies with lower impact parameters and slightly more star formation within this range. Of the observed systems, six exhibit strong (W {sub eq}(2796) {>=} 0.3 A) Mg II absorption at the galaxy's redshift, six systems have upper limits which preclude strong Mg II absorption, while the remaining observations rule out very strong (W {sub eq}(2796) {>=} 1-2 A) absorption. The absorbers fall at higher impact parameters than many non-absorber sightlines, indicating a covering fraction f{sub c} {approx}< 0.4 for {>=}0.3 A absorbers at z {approx} 0.1, even at impact parameters {<=}35 h {sup -1} kpc (f {sub c} {approx} 0.25). The data are consistent with a possible dependence of covering fraction and/or absorption halo size on the environment or star-forming properties of the central galaxy.

  18. Gamma-ray Spectral Characteristics of Thermal and Non-thermal Emission from Three Black Holes

    NASA Technical Reports Server (NTRS)

    Ling, James C.; Wheaton, William A.

    2004-01-01

    Cygnus X-1 and the gamma-ray transients GROJ0422+32 and GROJ1719-24 displayed similar spectral properties when they underwent transitions between the high and low gamma-ray (30 keV to few MeV) intensity states. When these sources were in the high (gamma)-ray intensity state ((gamma)2, for Cygnus X-l), their spectra featured two components: a Comptonized shape below 200-300 keV with a soft power-law tail (photon index >= 3) that extended to 1 MeV or beyond. When the sources were in the low-intensity state ((gamma)0, for Cygnus X-l), the Comptonized spectral shape below 200 keV typically vanished and the entire spectrum from 30 keV to 1 MeV can be characterized by a single power law with a relatively harder photon index 2-2.7. Consequently the high- and low-intensity gamma-ray spectra intersect, generally in the 400 KeV - 1 MeV range, in contrast to the spectral pivoting seen previously at lower (10 keV) energies. The presence of the power-law component in both the high- and low-intensity gammaray spectra strongly suggests that the non-thermal process is likely to be at work in both the high and the low-intensity situations. We have suggested a possible scenario (Ling & Wheaton, 2003), by combining the ADAF model of Esin et al. (1998) with a separate jet region that produces the non-thermal gamma-ray emission, and which explains the state transitions. Such a scenario will be discussed in the context of the observational evidence, summarized above, from the database produced by EBOP, JPL's BATSE earth occultation analysis system.

  19. Spectral characteristics of mesoscale variability of the bottom currents in the Ocean

    NASA Astrophysics Data System (ADS)

    Morozov, E. G.; Neiman, V. G.

    2016-11-01

    We performed spectral analysis of variations in the bottom currents on the basis of direct measurements in a number of regions of the entire Atlantic Ocean. We compared the spectra of the atmospheric pressure fluctuations at sea level and fluctuations of current velocities in the bottom layer. A significant energy of current fluctuations near the bottom with a synoptic period in the range 10-15 days that exceeds similar energies in the other regions of the ocean was found in the region of the Newfoundland energetically active zone, where increased cyclonic activity in the atmosphere is observed.

  20. Spectral characteristics of distributed feedback semiconductor laser and their improvements by corrugation-pitch-modulated structure

    NASA Astrophysics Data System (ADS)

    Okai, Makoto

    1994-01-01

    This paper presents a review of a theoretical analysis problems that occur with single-mode lasers, and a novel laser structure for superstable single-mode operation. Also presented is a new grating-fabrication technique termed photo-mask self-interference, to fabricate corrugation-pitch-modulated (CPM) structures, for enhancing the stability of the longitudinal single-mode operation in distributed feedback lasers (DFB). It is seen that the CPM-DFB laser developed for coherent transmission systems displays the narrowest spectral linewidth (56 kHz) reported so far for a semiconductor.

  1. Absorption and emission characteristics of Er3+ ions in alkali chloroborophosphate glasses.

    PubMed

    Moorthy, L R; Rao, T S; Janardhnam, K; Radhapathy, A

    2000-08-01

    Alkali chloroborophosphate glasses containing 1 mol% of Er3+ ions were studied experimentally using the absorption and emission spectroscopy. The energy level scheme for the 4f11 (Er3+) electronic configuration was deduced from the observed band energies of the absorption spectra in terms of a parametrized Hamiltonian using the various free-ion spectroscopic parameters. Oscillator strengths (f) measured from the absorption spectra have been analyzed using the Judd-Ofelt theory to evaluate the three intensity parameters omegalambda (lambda = 2, 4 and 6). Reasonable agreement between the measured and calculated f values has been found. Electric and magnetic dipole transition probabilities, fluorescence branching ratios, integrated emission cross sections and radiative lifetimes were calculated for all the excited states of Er3+ ions. The non-radiative (WNR) relaxation rates from the excited levels to the next lower levels have been calculated and the relationship between the energy gap and non-radiative relaxation rate has been established. These results were used to predict the possible potential laser transitions in Er-doped alkali chloroborophosphate glasses.

  2. [Synthesis and luminescent spectral characteristics of porphyrin complexes with platinum group metals].

    PubMed

    Rumiantseva, V D; Ivanovskaia, N P; Konovalenko, L I; Tsukanov, S V; Mironov, A F; Osin, N S

    2008-01-01

    The synthesis of natural and synthetic porphyrin complexes with Pt, Pd, Rh, and Ru is reported. Their electronic absorption spectra, phosphorescence spectra, and lifetimes at room temperature both in the presence and in the absence of oxygen were studied. It has been shown that the variation of the nature of the central metal atom and of the substituents in pyrrole and phenyl rings allows the obtaining of metalloporphyrins with various phosphorescence excitation and phosphorescing emission spectra at room temperature. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2008, vol. 34, no. 2; see also http://www.maik.ru.

  3. Identification and characterization of Salmonella serotypes using DNA spectral characteristics by fourier transform infrared

    NASA Astrophysics Data System (ADS)

    Sundaram, Jaya; Park, Bosoon; Hinton, Arthur; Yoon, Seung Chul; Lawrence, Kurt C.

    2012-05-01

    Analysis of DNA samples of Salmonella serotypes were performed using FT-IR spectrometer by placing directly in contact with a diamond attenuated total reflection (ATR) crystal. Spectra were recorded from 4000 cm-1 to 525 cm-1 wavenumber with the resolution of 4 cm-1 and data spacing of 1.928 cm-1. Collected spectra were subtracted from the background spectra of empty diamond crystal surface. Principal Component Analysis (PCA) was conducted at four different spectral regions to differentiate the different serotypes of Salmonella on the basis of difference in their spectral features of DNA structure macromolecules. PCA was used to show the natural clusters in the data set and to describe the difference between the sample clusters. At the region 1800 - 1200 cm-1, PC1 distinguished 93 % and PC2 distinguished 7 % of the serotypes. Therefore, maximum classification of 100 % in total was obtained at this region. For all the Salmonella serotypes, the frequency between 1000-1150 cm-1 and 1170 -1280 cm-1 had higher loading values which showed their significant contribution in the serotype classification.

  4. [Absorption Characteristics of Particulates and CDOM in Waters of Chagan Lake and Xinlicheng Reservoir in Autumn].

    PubMed

    Li, Si-jia; Song, Kai-shan; Zhao, Ying; Mu, Guang-yi; Shao, Tian-tian; Ma, Jian-hang

    2016-01-15

    Field surveys and laboratory analysis were carried out in Chagan Lake and Xinlicheng Reservoir under different salinity conditions in September 2012. In the laboratory, the absorption coefficients of particulates and chromophoric dissolved organic matter (CDOM) were measured, aiming to compare the absorption features, source of optical active substances and relative contribution of optical active constituents over the range of PAR (400-700 nm) in Chagan Lake and Xinlicheng Reservoir. The results showed that the Chagan Lake and Xinlicheng Reservoir were water bodies with medium eutrophication in autumn by TAL nutrient index and the absorption spectra of particulates matters were similar to those of phytoplankton. For the Chagan Lake with high salinity( EC = 988. 87 micro S x cm(-1)), the total particulate absorption was dominated by the nonalgal particles, and the contribution rate was in the order of nonalgal particles > phytoplankton > CDOM. For the Xinlicheng Reservoir with low salinity (EC = 311.67 microS x -cm(-1)), the total particulate absorption was dominated by the phytoplankton, and the contribution rate was ranked as phytoplankton > nonalgal particles > CDOM. Positive correlation was observed between a(p) (440), a(p) (675), a(d) (440) and total suspended matter (TSM), inorganic suspended matter (ISM), organic suspended matter (OSM) and Chl-a respectively in Chagan Lake, with correlation coefficients all above 0.55. Positive correlation was observed between a(p)(440), a(p) (675) and Chl-a (0.77 and 0.85, P < 0.05) , so did a(d) (440) and ISM (0.74, P < 0.01), while negative correlation was observed between a(p) (440) and OSM in the Xinlicheng Reservoir. In terms of Chagan Lake, negative correlation was merely observed between a(g) (440) and OSM (-0.54, P < 0.05) , but not in the Xinlicheng Reservoir. Both Sg, which was calculated by the fitting absorption curve from 250 to 400 nm, and relative molecular weight M showed that Sg[ (0.021 +/- 0.001) m(-1)] in

  5. Informatic analysis for hidden pulse attack exploiting spectral characteristics of optics in plug-and-play quantum key distribution system

    NASA Astrophysics Data System (ADS)

    Ko, Heasin; Lim, Kyongchun; Oh, Junsang; Rhee, June-Koo Kevin

    2016-10-01

    Quantum channel loopholes due to imperfect implementations of practical devices expose quantum key distribution (QKD) systems to potential eavesdropping attacks. Even though QKD systems are implemented with optical devices that are highly selective on spectral characteristics, information theory-based analysis about a pertinent attack strategy built with a reasonable framework exploiting it has never been clarified. This paper proposes a new type of trojan horse attack called hidden pulse attack that can be applied in a plug-and-play QKD system, using general and optimal attack strategies that can extract quantum information from phase-disturbed quantum states of eavesdropper's hidden pulses. It exploits spectral characteristics of a photodiode used in a plug-and-play QKD system in order to probe modulation states of photon qubits. We analyze the security performance of the decoy-state BB84 QKD system under the optimal hidden pulse attack model that shows enormous performance degradation in terms of both secret key rate and transmission distance.

  6. A study on transmission characteristics and specific absorption rate using impedance-matched electrodes for various human body communication.

    PubMed

    Machida, Yuta; Yamamoto, Takahiko; Koshiji, Kohji

    2013-01-01

    Human body communication (HBC) is a new communication technology that has presented potential applications in health care and elderly support systems in recent years. In this study, which is focused on a wearable transmitter and receiver for HBC in a body area network (BAN), we performed electromagnetic field analysis and simulation using the finite difference time domain (FDTD) method with various models of the human body. Further we redesigned a number of impedance-matched electrodes to allow transmission without stubs or transformers. The specific absorption rate (SAR) and transmission characteristics S21 of these electrode structures were compared for several models.

  7. Spectral characteristics of airway opening and chest wall tidal flows in spontaneously breathing preterm infants.

    PubMed

    Habib, Robert H; Pyon, Kee H; Courtney, Sherry E; Aghai, Zubair H

    2003-05-01

    We compared the harmonic content of tidal flows measured simultaneously at the mouth and chest wall in spontaneously breathing very low birth weight infants (n = 16, 1,114 +/- 230 g, gestation age: 28 +/- 2 wk). Airway opening flows were measured via face mask-pneumotachograph (P-tach), whereas chest wall flows were derived from respiratory inductance plethysmography (RIP) excursions. Next, for each, we computed two spectral shape indexes: 1) harmonic distortion (k(d); k(d,P-tach) and k(d,RIP), respectively) defines the extent to which flows deviated from a single sine wave, and 2) the exponent of the power law (s; s(P-tach) and s(RIP), respectively), describing the spectral energy vs. frequency. P-tach and RIP flow spectra exhibited similar power law functional forms consistently in all infants. Also, mouth [s(P-tach) = 3.73 +/- 0.23% (95% confidence interval), k(d,P-tach) = 38.8 +/- 4.6%] and chest wall (s(RIP) = 3.51 +/- 0.30%, k(d,RIP) = 42.8 +/- 4.8%) indexes were similar and highly correlated (s(RIP) = 1.17 x s(P-tach) + 0.85; r(2) = 0.81; k(d,RIP) = 0.90 x k(d,P-tach) + 8.0; r(2) = 0.76). The corresponding time to peak tidal expiratory flow-to-expiratory time ratio (0.62 +/- 0.08) was higher than reported in older infants. The obtained s and k(d) values are similar to those reported in older and/or larger chronic lung disease infants, yet appreciably lower than for 1-mo-old healthy infants of closer age and/or size; this indicated increased complexity of tidal flows in very low birth weight babies. Importantly, we found equivalent flow spectral data from mouth and chest wall tidal flows. The latter are desirable because they avoid face mask artificial effects, including leaks around it, they do not interfere with ventilatory support delivery, and they may facilitate longer measurements that are useful in control of breathing assessment.

  8. Spectrally resolved intraband transitions on two-step photon absorption in InGaAs/GaAs quantum dot solar cell

    SciTech Connect

    Tamaki, Ryo Shoji, Yasushi; Okada, Yoshitaka; Miyano, Kenjiro

    2014-08-18

    Two-step photon absorption processes in a self-organized In{sub 0.4}Ga{sub 0.6}As/GaAs quantum dot (QD) solar cell have been investigated by monitoring the mid-infrared (IR) photoinduced modulation of the external quantum efficiency (ΔEQE) at low temperature. The first step interband and the second step intraband transitions were both spectrally resolved by scanning photon energies of visible to near-IR CW light and mid-IR pulse lasers, respectively. A peak centered at 0.20 eV corresponding to the transition to virtual bound states and a band above 0.42 eV probably due to photoexcitation to GaAs continuum states were observed in ΔEQE spectra, when the interband transition was above 1.4 eV, directly exciting wetting layers or GaAs spacer layers. On the other hand, resonant excitation of the ground state of QDs at 1.35 eV resulted in a reduction of EQE. The sign of ΔEQE below 1.40 eV changed from negative to positive by increasing the excitation intensity of the interband transition. We ascribe this to the filling of higher energy trap states.

  9. Spectrally resolved intraband transitions on two-step photon absorption in InGaAs/GaAs quantum dot solar cell

    NASA Astrophysics Data System (ADS)

    Tamaki, Ryo; Shoji, Yasushi; Okada, Yoshitaka; Miyano, Kenjiro

    2014-08-01

    Two-step photon absorption processes in a self-organized In0.4Ga0.6As/GaAs quantum dot (QD) solar cell have been investigated by monitoring the mid-infrared (IR) photoinduced modulation of the external quantum efficiency (ΔEQE) at low temperature. The first step interband and the second step intraband transitions were both spectrally resolved by scanning photon energies of visible to near-IR CW light and mid-IR pulse lasers, respectively. A peak centered at 0.20 eV corresponding to the transition to virtual bound states and a band above 0.42 eV probably due to photoexcitation to GaAs continuum states were observed in ΔEQE spectra, when the interband transition was above 1.4 eV, directly exciting wetting layers or GaAs spacer layers. On the other hand, resonant excitation of the ground state of QDs at 1.35 eV resulted in a reduction of EQE. The sign of ΔEQE below 1.40 eV changed from negative to positive by increasing the excitation intensity of the interband transition. We ascribe this to the filling of higher energy trap states.

  10. Moisture absorption characteristics of the Orbiter thermal protection system and methods used to prevent water ingestion

    NASA Technical Reports Server (NTRS)

    Schomburg, C.; Dotts, R. L.; Tillian, D. J.

    1983-01-01

    The Space Shuttle Orbiter's silica tile Thermal Protection System (TPS) is beset by the moisture absorption problems inherently associated with low density, highly porous insulation systems. Attention is presently given to the comparative success of methods for the minimization and/or prevention of water ingestion by the TPS tiles, covering the development of water-repellent agents and their tile application techniques, flight test program results, and materials improvements. The use of external films for rewaterproofing of the TPS tiles after each mission have demonstrated marginal to unacceptable performance. By contrast, a tile interior waterproofing agent has shown promise.

  11. Plant Resources, (13)C-NMR Spectral Characteristic and Pharmacological Activities of Dammarane-Type Triterpenoids.

    PubMed

    Ruan, Jingya; Zheng, Chang; Qu, Lu; Liu, Yanxia; Han, Lifeng; Yu, Haiyang; Zhang, Yi; Wang, Tao

    2016-08-12

    Dammarane-type triterpenoids (DTT) widely distribute in various medicinal plants. They have generated a great amount of interest in the field of new drug research and development. Generally, DTT are the main bioactive ingredients abundant in Araliaceae plants, such as Panax ginseng, P. japonicas, P. notoginseng, and P. quinquefolium. Aside from Araliaceae, DTT also distribute in other families, including Betulaceae, Cucurbitaceae, Meliaceae, Rhamnaceae, and Scrophulariaceae. Until now, about 136 species belonging to 46 families have been reported to contain DTT. In this article, the genus classifications of plant sources of the botanicals that contain DTT are reviewed, with particular focus on the NMR spectral features and pharmacological activities based on literature reports, which may be benefit for the development of new drugs or food additives.

  12. Continuum spectral characteristics of bursts measured with BATSE large area detectors

    NASA Technical Reports Server (NTRS)

    Pendleton, Geoffrey N.; Paciesas, William S.; Briggs, Michael S.; Mallozzi, Robert S.; Koshut, Tom M.; Fishman, Gerald J.; Wilson, Robert B.; Meegan, Charles A.; Kouveliotou, Chryssa

    1994-01-01

    The continuum spectra of bursts are studied with particular emphasis placed on the search for spectral subcomponents. The spectra observed in individual bursts show significant evolution throughout their durations. The degree to which hard and soft spectra are combined in bursts and the effect this has on the complexity of the observed spectra are addressed. In particular the presence of broad cusps in spectra in the 50-100 keV range are studied to determine both the degree to which these features are present in the LAD data and whether superposition of hard and soft spectra simultaneously can account for them. Also the time histories of the power output (ergs/sec) from bursts are studied to investigate the dynamic coupling between hard and soft spectra in bursts as a probe of the autonomy of the hard and soft emission mechanisms.

  13. Attractors and Spectral Characteristics of Neural Structures Based on the Model of the Quantum Harmonic Oscillator

    SciTech Connect

    Rigatos, Gerasimos G.

    2007-09-06

    Neural computation based on principles of quantum mechanics can provide improved models of memory processes and brain functioning and is of importance for the realization of quantum computing machines. To this end, this paper studies neural structures with weights that follow the model of the quantum harmonic oscillator. These weights correspond to diffusing particles, which interact to each other as the theory of Brownian motion predicts. The learning of the stochastic weights (convergence of the diffusing particles to an equilibrium) is analyzed. In the case of associative memories the proposed neural model results in an exponential increase of the number of attractors. Spectral analysis shows that the stochastic weights satisfy an equation which is analogous to the principle of uncertainty.

  14. Study on spectral/radiometric characteristics of the Thematic Mapper for land use applications

    NASA Technical Reports Server (NTRS)

    Malila, W. A.; Metzler, M. D. (Principal Investigator); Crist, E. P.

    1983-01-01

    Previous characterization of scan-related low-frequency noise was extended and refined through detailed analysis of shutter calibration data on CCT-ADDS tapes and reflective-band data from nighttime acquisitions. A recommended correction procedure was identified that uses calibration shutter data both as a diagnostic and to obtain correction values. Through comparison of coincident TM and MSS data, illustrations of the added information content of TM data for agricultural applications were developed. The capability of improved spatial resolution to better define boundaries and to resolve spatial details is shown. Spectral analysis of tasseled-cap transformations of TM and MSS data shows high correlation between greenness features, greater signal range for TM, and indications that a subset of TM bands could accurately simulate MSS data, if required.

  15. Spectral characteristics of steady quiet-time EMIC waves observed at geosynchronous orbit

    NASA Astrophysics Data System (ADS)

    Kim, Khan-Hyuk; Park, Jong-Sun; Omura, Yoshiharu; Shiokawa, Kazuo; Lee, Dong-Hun; Kim, Gi-Jeong; Jin, Ho; Lee, Ensang; Kwon, Hyuck-Jin

    2016-09-01

    We have studied the spectral properties of quiet-time electromagnetic ion cyclotron (EMIC) waves following a steady quiet condition, which is defined with Kp values ≤1 during 12 h, using GOES 10, 11, and 12 magnetometer data for solar minimum years 2007-2008. We identified 6584 steady quiet-time EMIC wave samples using a semiautomated procedure. Approximately 82% of the samples were observed in the morning-to-early afternoon sector (0700-1500 magnetic local time) with a maximum occurrence near noon, and their peak frequencies were mostly in the He band. We found that the occurrence rate of steady quiet-time EMIC waves is higher than that of EMIC waves for all or quiet geomagnetic conditions (Dst > 0 nT or AE < 100 nT) reported in previous studies by a factor of 2 or more. The frequency ratio fpeak (sample's peak frequency)/fH+ (the local proton gyrofrequency) of the He-band waves (˜0.11-0.16) under steady quiet conditions is lower than that (˜0.14-0.24) in previous studies. These results may be due to the fact that the plasmasphere expanded more frequently to the geosynchronous region under extremely quiet geomagnetic conditions in 2007-2008 than the periods selected in previous studies. The amplitude and frequency of He-band EMIC waves for nonlinear wave growth are examined as changing cold plasma density at geosynchronous orbit. We confirm that the spectral properties of observed EMIC waves are in good agreement with the nonlinear theory.

  16. Mean spectral characteristics of acoustic gravity waves in the thermosphere-ionosphere determined from Dynasonde data

    NASA Astrophysics Data System (ADS)

    Negrea, Cǎtǎlin; Zabotin, Nikolay A.

    2016-03-01

    Wave-like disturbances have been observed in the ionospheric plasma for several decades using a wide range of remote sensing techniques. In this paper, the use of Dynasonde-derived ionospheric "tilt" measurements is demonstrated to determine the dominant features of the underlying acoustic gravity wave spectrum and its height variation. The diurnal ionospheric variability introduces data gaps of varying length and distribution at any constant height level. This excludes the use of conventional fast Fourier transform techniques for spectral calculations. To obtain a complete and accurate image of the height variability of the wave activity in the thermosphere-ionosphere, a method is required that would provide physically comparable results at all altitudes, regardless of the variations in sampling. In addition, the true geophysical variability should be distinguished from overlapping noise. The proposed solution is a combination of the well-known Lomb-Scargle and Welch methods, with the dataset of interest being divided into several overlapping subintervals and the mean spectrum calculated using results for those subintervals for which the power spectral density integral equals the time domain variance within a preset tolerance. The choice of the tolerance value is justified by means of numerical simulations using synthetic data similar to the tilt measurements. The proposed method is verified using a 10 day long dataset obtained with the Wallops Island Dynasonde. Results obtained with this method are compared in this paper with those obtained with a basic implementation and with a filtering method based on the amount of available data. A considerable reduction in the number of artifacts is observed with the use of this innovative approach, allowing reliable conclusions to be derived regarding the acoustic gravity wave spectrum and its height variability.

  17. [Spectral-kinetic characteristics of the cation-radical of pheophytin a].

    PubMed

    Evstigneev, V B

    1977-01-01

    The photochemical generation of pheophytin a cation-radical in acidulated ethanol and aceto nitril has been studied by the method of flash-photolysis. The bands with maxima at 450, 580 and 800 nm correspond to pheophytin a cation-radical in the differential absorption spectra. The efficient rate constants of pheophytin a triplet state desactivation in ethanol, acetonitril, aceton have the following values: 1.5.10(4), 9.10(3), 8.7.10(3) sec(-1) correspondingly. The rate constant of electron transfer from pheophytin a to p-benzoqui-none in ethanol solutions is 7.8.10(9) l/m.sec. The recombination constants of pheophytin a cation-radical with Q-in acetonitril, and with quinone neutral (QH) in acidulated ethanol have the following values: 5.10(9) and 2.10(9) l/m.sec correspondingly.

  18. Gender Recognition Method Using Near Infrared Ray Spectral Characteristics of Narrow Band

    NASA Astrophysics Data System (ADS)

    Nishino, Satoshi

    Male and female recognition is necessary to make security stronger and when various statistics on the visitor are taken in commercial facilities and so on. The conventional method of male and female recognition is currently determined by using the person's dress and in such cases, the way of walking, the foot pressure, the hair type. But, these characteristics can be intentionally changed by human intervention or design. The proposed method obtains a difference in the male's and female's characteristics by taking absorbance characteristics of the fat distribution of the person's cheek by near infrared ray scanning spectrophotometer. This is a male and female recognition based on the new concept idea which this is used for. Consequently, this can be used to recognize a male from a female even if a male turns himself into the female intentionally (and vice versa), because this method involves biometrics authentication. Therefore, the proposed method will be applied to the security system.

  19. Deuterium absorption and material phase characteristics of Zr[sub 2]Fe

    SciTech Connect

    Nobile, A.; Mosley, W.C.; Holder, J.S.; Brooks, K.N.

    1992-12-30

    Scanning electron microscope (SEM) images of polished surfaces, electron probe microanalysis, and X-ray powder diffractometry indicated the presence of a continuous Zr[sub 2]Fe phase with secondary phases of ZrFe[sub 2], Zr[sub 5]FeSn, [alpha]-Zr, and Zr[sub 6]Fe[sub 3]O. A statistically-designed experiment to determine the effects of temperature, time, and vacuum quality On activation of St 198 revealed that when activated at low temperature (350[degrees]C) deuterium absorption rate was slower when the vacuum quality was pwr (2.5 Pa vs. 3[times]10[sup [minus]4] Pa). However, at higher activation temperature (500[degrees]C), deuterium absorption rate was fast and was independent of vacuum quality. Deuterium pressure-composition-temperature (P-C-T) data are reported for St 198 in the temperature range 200--500[degrees]C. The P-C-T data over the full range of deuterium loading and at temperatures of 350[degrees]C and below is described by: K[sub 0e]-([Delta]H[sub [alpha

  20. [Influence of the Composition of the Initial Mixtures on the Physicochemical and Biological Properties and Spectral Characteristics of Composts].

    PubMed

    Song, Cai-hong; Li, Ming-xiao; Wei, Zi-min; Xi, Bei-dou; Zhao, Yue; Jia, Xuan; Liu, Ya-ru; Liu, Dong-ming

    2015-08-01

    In this work, biogas residues, the remnant of the anaerobic digestion, was used for composting with livestock manure as the co-substrate. It is important for improving the soil quality in China, because the negative influence of biogas residues being utilized directly as organic fertilizer (a mainstream way of disposing biogas residues in China) on the soil could be eliminated or mitigated via composting. The composition of composting substrate has a great influence on the composting process. To explore the influence of the composition of the initial mixtures on the physicochemical properties and spectroscopic characteristics of composts, fifteen co-composting of biogas residue, pig manure and chicken manure, with different material ratios, were carried out. Physicochemical and biological indicators were determined. Meanwhile, spectroscopic methods, such as UV-Vis, synchronous fluorescence and 3D-EEM spectra were used for identifying characteristic spectral parameters companied with FRI and PARAFAC. Therefore, spectroscopic characteristics of composts were characterized. The relationship between physicochemical properties of composts and the composition of the initial mixtures was established using CCA. Similarly, that between spectroscopic characteristics of composts and the composition of the initial mixtures was also established. The results showed that: physicochemical properties of composts exhibits a significant correlation with the composition of the initial mixtures. A significant correlation between spectroscopic characteristics of composts and the composition of the initial mixtures was also observed. In the two CCA, the former four axes account for 83.9% and 97.5% of the total sample variation. The influence of enviro nmental factors on physicochemical properties of composts was in the order of pig manure amount>chicken manure amount>biogas residue amount and that on spectroscopic characteristics of composts was in the order of biogas residue amount

  1. Hydrogenation and dehydrogenation of interstellar PAHs: Spectral characteristics and H2 formation

    NASA Astrophysics Data System (ADS)

    Andrews, H.; Candian, A.; Tielens, A. G. G. M.

    2016-10-01

    Context. We have modelled the abundance distribution and IR emission of the first 3 members of the coronene family in the north-west photodissociation region of the well-studied reflection nebulae NGC 7023. Aims: Our aim was 3-fold: i) analyze the distribution of abundances; (ii) examine the spectral footprints from the hydrogenation state of polycyclic aromatic hydrocarbons (PAHs); and (iii) assess the role of PAHs in the formation of H2 in photodissociation regions. Methods: To model the physical conditions inside the cloud, we used the Meudon PDR Code, and we gave this as input to our kinetic model. We used specific molecular properties for each PAH, based on the latest data available at the present time. We considered the loss of an H atom or an H2 molecule as multiphoton processes, and we worked under the premise that PAHs with extra H atoms can form H2 through an Eley-Rideal abstraction mechanism. Results: In terms of abundances, we can distinguish clear differences with PAH size. The smallest PAH, coronene (C24H12), is found to be easily destroyed down to the complete loss of all of its H atoms. The largest species circumcircumcoronene (C96H24), is found in its normal hydrogenated state. The intermediate size molecule, circumcoronene (C54H18), shows an intermediate behaviour with respect to the other two, where partial dehydrogenation is observed inside the cloud. Regarding spectral variations, we find that the emission spectra in NGC 7023 are dominated by the variation in the ionization of the dominant hydrogenation state of each species at each point inside the cloud. It is difficult to "catch" the effect of dehydrogenation in the emitted PAH spectra since, for any conditions, only PAHs within a narrow size range will be susceptible to dehydrogenation, being quickly stripped off of all H atoms (and may isomerize to cages or fullerenes). The 3 μm region is the most sensitive one towards the hydrogenation level of PAHs. Conclusions: Based on our results, we

  2. Characteristics of Wood Sawdust and Chips as Energy Absorption Filling Mediums

    NASA Astrophysics Data System (ADS)

    Singace, Abduljalil Abdulla

    Wood sawdust and chips, as carpentry processes remains, are introduced as alternatives for filling mediums in energy mitigation systems. The natural, economical and environment friendly material, wood, is modeled and its interaction with the collapse of tubes, typical energy absorption elements, has been considered. Compression tests on wood sawdust were used to extract its mechanical properties and the results of which have been used in the validation of the analytical models. The collapse of PVC tubes, filled with wood sawdust of different grades and densifications, has been analyzed considering multi-lobe mode, concertina mode and mixed mode. In these models, the interaction of wood sawdust filler on the final mode of collapse of PVC tubes has been incorporated and the final values of the mean crushing load show favourable results.

  3. [Study on the preparation and spectral characteristics of Bi2S3 nanoribbons].

    PubMed

    Lu, Juan; Han, Qiao-Feng; Yang, Xu-Jie; Lu, Lu-De; Wang, Xin

    2009-01-01

    In the present study, bismuth sulfide (Bi2S3) nanoribbons were prepared by the hydrothermal method using bismuth nitrate (Bi(NO3)3 x 5H2O), thioacetamide (C2H5NS) and nitrilotriacetic acid (C6H9NO6) as raw materials at 180 degrees C for 12 h. The reaction time was largely reduced and the route has been unreported. The constituent, structure and morphology of the products were characterized by XRD, XPS and TEM, respectively. The powder X-ray diffraction (XRD) pattern shows that the Bi2S3 crystals belong to the orthorhombic phase (JCPDS:17-320) with calculated lattice constants a = 1.1106 nm, b = 1.0993 nm and c = 0.3892 nm, which are consistent with the reported values (a = 1.1149 nm, b = 1.1304 nm and c = 0.3981 nm). Transmission electron microscopic (TEM) studies reveal that the appearance of as-prepared Bi2S3 is nanoribbon-like with the typical width of about 100 nm; and the high-resolution transmission electron microscope (HRTEM) image shows that the crystal grows along the y axis. The quantification of X-ray photoelectron spectra (XPS) analysis peaks gives an atomic ratio of 2 : 3 for Bi : S, which is consistent with the given formula of Bi2S3. Furthermore, the Raman and UV-Vis spectra of the product were also studied. Compared with bulk Bi2S3 (236 cm(-1)), the Raman absorption band of the Bi2S3 nanoribbons (195 cm(-1)) red-shifts 41 cm(-1), which is because of the surface effect of nanomaterials. Furthermore, the product has absorption at the wavelength of about 450 nm in the UV-Vis region. The direct bang gap energy (Eg) was estimated to be about 1.58 eV(Eg of the bulk Bi2S3 is 1.3 eV), which indicates that the product has potential application in the optical and electrical areas.

  4. Spectral characteristics and the extent of paleosols of the Palouse formation

    NASA Technical Reports Server (NTRS)

    Frazier, B. E.; Busacca, A.; Cheng, Y.; Wherry, D.; Hart, J.; Gill, S.

    1986-01-01

    Spectral relationships were investigated for several bare soil fields which were in summer fallow rotation on the date of the imagery. Printouts of each band were examined and compared to aerial photography. Bands with dissimilar reflectance patterns for known areas were then combined using ratio techniques which were proven useful in other studies (Williams, 1983). Selected ratios were Thematic Mapper (TM) 1/TM4, TM3/TM4, and TM5/TM4. Cluster analyses and Baysian and Fastclass classifier images were produced using the three ratio images. Plots of cluster analysis outputs revealed distinct groupings of reflectance data representing green crops, ripened crops, soil and green plants, and bare soil. Bare soil was represented by a line of clusters on plots of the ratios TM5/TM4 and TM3/TM4. The soil line was investigated further to determine factors involved in the distributin of clusters alone the line. The clusters representing the bare soil line were also studied by plotting the Tm5/TM4, TM1/TM4 dimension. A total of 76 soil samples were gathered and analyzed for organic carbon.

  5. Environmental processes and spectral reflectance characteristics associated with soil erosion in desert fringe regions

    NASA Technical Reports Server (NTRS)

    Jacobberger, P. A.

    1986-01-01

    Two Thematic Mapper (TM) scenes were acquired. A scene was acquired for the Bahariya, Egypt field area, and one was acquired covering the Okavango Delta site. Investigations at the northwest Botswana study sites have concentrated upon a system of large linear (alab) dunes possessing an average wavelength of 2 kilometers and an east-west orientation. These dunes exist to the north and west of the Okavango Swamp, the pseudodeltaic end-sink of the internal Okavango-Cubango-Cuito drainage network. One archival scene and two TM acquisitions are on order, but at present no TM data were acquired for the Tombouctou/Azaouad Dunes, Mali. The three areas taken together comprise an environmental series ranging from hyperarid to semi-arid, with desertization processes operational or incipient in each. The long range goal is to predict normal seasonal variations, so that aperiodic spectral changes resulting from soil erosion, vegetation damage, and associated surface processes would be distinguishable as departures from the norm.

  6. Spectral characteristics of the bentonite loaded with benzyldimethyloctadecylammonium chloride, hexadecyltrimethylammonium bromide and dimethyldioctadecylammonium bromide

    NASA Astrophysics Data System (ADS)

    Majdan, Marek; Maryuk, Oksana; Gładysz-Płaska, Agnieszka; Pikus, Stanisław; Kwiatkowski, Ryszard

    2008-02-01

    The spectral characterization, including the FTIR, DRIFT (diffusive reflectance), SWAXS (small and wide angle X-ray scattering) spectra comparison of the sodium bentonite modified by BDMODA-Cl (benzyldimethyloctadecylammonium chloride), HDTMA-Br (hexadecyltrimethylammonium bromide), DDA-Br (dimethyldioctadecylammonium bromide) is presented in the paper. The FTIR spectra show the shift of C-H stretching vibrations: νsym(CH2), νasym(CH2) of surfactants methylene chains toward lower frequencies (from 2855 to 2851 cm -1 for νsym(CH2) and from 2927 to 2918 cm -1 for νansym(CH2) with the surfactant concentration in bentonite phase. The bending vibrations δH-O-H in water molecules change their positions in the direction of higher frequencies (from 1634 to 1647 cm -1) with the surfactant concentration for bentonite-BDMODA and bentonite-DDA contrary to bentonite-HDTMA, where the constant position δH-O-H is explained as the consequence of the lower concentration of the hydrogen bonded water in bentonite-HDTMA phase when compared with the remaining forms of bentonite. The DRIFT spectra reveal dramatic shift of the νSi-O stretching vibration toward higher frequencies upon intercalation of the sodium bentonite with the surfactant cations. The SWAXS spectra and SEM images of the bentonite are the evidence of somewhat different sorption mechanism of DDA-Br when compared with the BDMODA-Cl and HDTMA-Br, including remarkable external surface sorption contribution in the overall sorption.

  7. Spectral and photocatalytic characteristics of TiO2 CVD films on quartz.

    PubMed

    Mills, Andrew; Lee, Soo-Keun; Lepre, Anne; Parkin, Ivan P; O'Neill, Shane A

    2002-11-01

    A series of novel CVD films of titanium(IV) oxide of different thicknesses, spanning the range 10-91 nm, are prepared on quartz, via the reaction of titanium(IV) chloride and ethyl acetate, using a CVD technique. The films are clear, mechanically robust and comprise thin layer of nanocrystalline anatase titania of different thicknesses that absorb UV light. The UV-Visible spectral profiles of all the CVD TiO2 films of different thickness are the same and obey Lambert's law (absorbance is porportional to film thickness). A plot of the reciprocal length for the TiO2 coating versus wavelength is reported. The photocatalytic activity of each film to mediate the destruction of a thin layer of stearic acid is investigated. The rate depends directly upon the fraction of light absorbed and the apparent quantum yield for the overall process is 0.00035, which appears low compared with that for sol-gel TiO2 films.

  8. Characteristics of surface cyclone forecasts in the Aviation Run of the Global Spectral Model

    SciTech Connect

    Grumm, R.H. )

    1993-03-01

    Results are presented of an evaluation of the performance of the Aviation Run (AVN) of the NMC Global Spectral Model (GSM) in predicting surface cyclones, which was conducted during the autumn of 1990 through the winter of 1992. The results indicated that the finer-resolution T126 GSM produces stronger and deeper cyclones than the old T80 GSM. The errors in AVN position forecasts of surface cyclones were smaller than those found in the NMC Nested Grid Model (NGM). The geographical distribution of the pressure errors were similar to those found in the NGM over eastern North America and the adjacent western Atlantic Ocean. The AVN tended to underpredict the 1000-500-mb thickness over surface cyclones, especially during the first 36 h of the forecast cycle. The T126 AVN forecasts are accurate enough to provide guidance for basic weather forecasts to three days, as has been done for the two-day forecasts for the past 25-30 yr. 19 refs.

  9. [Spectral characteristics of the bioelectrical activity of the cerebral cortex upon electric stimulation of subcortical structures].

    PubMed

    Ianson, Z A; Markin, V P

    1976-01-01

    A spectral-correlation analysis of electrical activity of the rabbit cerebral cortex was made with the use of Dnieper computer, after electrical stimulation (100-250 c/s) of the midbrain reticular formation, the thalamic nonspecific formations (midline nuclei) and different nuclei of the posterior part of the hypothalamic area (ventromedial and posterior hypothalamic nuclei and the lateral field). The background spectrograms were characterized by a high variability; their frequencies ranged from 0,5 to 12 c/s. Under the influence of the electrical stimulation of the indicated formations, a well-pronounced, dominating peak appeared in the spectrograms of the cortical EEG, in the band from 4 to 7 c/s, and the similarity of biopotentials in this rhythm increased. The experimental data show that enhancement of spatial synchronization of the cortical biopotentials under conditions of electrical stimulation of the indicated subcortical formations is based on increased rhythmic oscillations within the theta-band and on a greater coherence in this range.

  10. Effect of crosstalk on combined beam characteristics in spectral beam combining systems

    NASA Astrophysics Data System (ADS)

    Yang, Lei; Wu, Zhen; Zhong, Zheqiang; Zhang, Bin

    2017-02-01

    In a spectral beam combining (SBC) system, crosstalk always happens because stray lights are inevitable due to fabrication errors of optical components and 'smile' effect of laser arrays. Two kinds of crosstalk, including the crosstalk generated between two adjacent emitters of the laser array (ad-crosstalk) and that generated between two non-adjacent emitters (non-ad-crosstalk), have been analyzed. The equivalent light of the crosstalk model has been proposed, and the propagation model of the SBC system with the crosstalk has been built up. On this basis, influences of above two kinds of the crosstalk on the combined beam have been numerically simulated and discussed in detail. The results show that the wavelength composition of the combined beam varies evidently owing to the existence of the crosstalk. With the increasing of the crosstalk intensity, the beam quality of the combined beam degrades, and the side lobes of intensity distribution of the combined beam become more and more obvious. Furthermore, the influence of the non-ad-crosstalk on the beam quality is more serious than that of the ad-crosstalk.

  11. Spectral characteristics and the extent of paleosols of the Palouse formation

    NASA Technical Reports Server (NTRS)

    Frazier, B. E.; Busacca, Alan; Cheng, Yaan; Wherry, David; Hart, Judy; Gill, Steve

    1988-01-01

    The objective of this study is to test the hypothesis that TM data is adequate in band selection and width and in spatial resolution to distinguish soil organic matter, iron oxide, and lime-silica contents to map several severity classes of erosion in soils of the Palouse region. The methodology used is as follows: (1) To develop spectral relationships from TM data that define the spatial distribution of soil areas by levels of (1) organic matter in the surface soil, (2) iron oxide and clay in exposed paleosol B horizons, and (3) lime-silica accumulations in exposed paleosol B horizons; (2) To compare areas determined by the method outlined in 1 to patterns interpreted from color aerial photos, and to ground observations on bare-soil fields; and (3) To define, on the basis of results of 1 and 2 to the extent possible, where exposed paleosols exist within fields that are not bare, but have a crop cover, and the distribution of desirable and undesirable soil properties in each field.

  12. The Spectral Emission Characteristics of Laser Induced Plasma on Tea Samples

    NASA Astrophysics Data System (ADS)

    Zheng, Peichao; Shi, Minjie; Wang, Jinmei; Liu, Hongdi

    2015-08-01

    Laser induced breakdown spectroscopy (LIBS) provides a useful technique for food security as well as determining nutrition contents. In this paper, optical emission studies of laser induced plasma on commercial tea samples were carried out. The spectral intensities of Mg, Mn, Ca, Al, C and CN vibration bands varying with laser energy and the detection delay time of an intensified charge coupled device were studied. In addition, the relative concentrations of six microelements, i.e., Mg, Mn, Ca, Al, Na and K, were analyzed semi-quantitatively as well as H, for four kinds of tea samples. Moreover, the plasma parameters were explored, including electron temperature and electron number density. The electron temperature and electron number density were around 11000 K and 1017 cm-3, respectively. The results show that it is reasonable to consider the LIBS technique as a new method for analyzing the compositions of tea leaf samples. supported by National Natural Science Foundation of China (No. 61205149), the Scientific and Technological Talents Training Project of Chongqing, China (No. CSTC2013kjrc-qnrc40002), the Scientific and Technological Project of Nan'an District (2011) and the Visiting Scholarship of State Key Laboratory of Power Transmission Equipment & System Security and New Technology at Chongqing University, China (No. 2007DA10512714409)

  13. Spectral characteristics of caries-related autofluorescence spectra and their use for diagnosis of caries stage

    NASA Astrophysics Data System (ADS)

    Son, Sung-Ae; Jung, Kyeong-Hoon; Ko, Ching-Chang; Kwon, Yong Hoon

    2016-01-01

    The purpose of the present study was to identify factors useful for diagnosis of the caries stage from laser-induced autofluorescence (AF) spectra. Affected teeth were accurately staged and allocated to four groups: sound, stage II, stage III, or stage IV. A 405-nm laser was used to produce AF spectra. The spectrum factors analyzed were spectrum slope at 550 to 600 nm, spectral area from 500 and 590 nm, and intensity ratio of peaks 625 and 667 nm (625/667 nm). DIAGNOdent was used as control measurement. AF spectra of sound teeth had a peak near 500 nm followed by a smooth decline to 800 nm. As caries progressed, some specimens in stages II to IV showed one or two peak(s) near 625 and 667 nm. Slopes at 550 to 600 nm and areas under the curve at 500 to 590 nm were significantly different (p<0.001) for each stage. Two-peak ratios were also significantly different (p<0.001) except for stage III and stage IV. DIAGNOdent readings for sound and stage II and stage III and IV were not significantly different. Among the studied factors, the spectrum slope at 550 to 600 nm and area under curve at 500 to 590 nm could be useful treatment decision-making tools for carious lesions.

  14. Spectral characteristics of heterocyclic compounds with a chain structure, cooled in an ultrasonic jet

    NASA Astrophysics Data System (ADS)

    Povedailo, V. A.; Yakovlev, D. L.

    2006-11-01

    We have recorded the fluorescence excitation spectra of three heterocyclic compounds with a chain structure [BPO (2-phenyl-5-(4-diphenylyl)oxazole), POPOP (1,4-di[2-(5-phenyloxazolyl)]benzene, and TOPOT (1,4-di[2-(5-n-tolyloxazolyl)]benzene] and the fluorescence spectra of POPOP, under conditions where the molecules were cooled in an ultrasonic helium jet. A line structure is observed in the spectra of POPOP and TOPOT; for the BPO molecules, whose configuration changes considerably during electronic excitation, vibrational structure is apparent only in the low-frequency region of the excitation spectrum, and a diffuse spectrum is recorded starting from ν 0 0 + 200 cm-1. For all the compounds, in the spectra we recorded vibrations with frequencies up to 100 cm-1, arising due to the flexibility of the molecular structure. The rotational contours of the lines for the electronic and vibronic transitions of the POPOP molecules (Trot = 10.5 K) and TOPOT molecules (Trot = 15 K) are structureless and bell-shaped. The degree of polarization of the fluorescence Pfl for the jet-cooled POPOP molecules for excitation of vibrations along the absorption band up to 2000 cm-1 above ν 0 0 is practically constant (˜8.4%) and matches Pfl for high-temperature vapors.

  15. Assessment of spectral characteristics of rodents in conditions of effect of heavy metals

    NASA Astrophysics Data System (ADS)

    Timchenko, Elena V.; Timchenko, Pavel E.; Simak, Sergey V.; Selezneva, Ekaterina A.; Kadayb, Asel D.; Kornilin, Dmitriy V.

    2016-09-01

    The results of studies of effect of heavy metals (HM) on small mammals' bone tissue using Raman spectroscopy method are presented. The characteristics of Raman spectra of small mammals' bone tissue, living in conditions of content HM gradient, were obtained. The main changes were detected at 960 cm-1 and 1247 cm-1 wavenumbers, corresponding to phosphate and amide III. Optical criteria determining the impact of HM on bone tissue were introduced.

  16. Spectral characteristics and synchrony in primary auditory-nerve fibers in response to pure-tone acoustic stimuli

    NASA Astrophysics Data System (ADS)

    Teich, Malvin C.; Khanna, Shyam M.; Guiney, Patrick C.

    1993-01-01

    Under pure-tone stimulation, the spectrum of the period histogram recorded from primary auditory-nerve fibers at low and medium frequencies contains components at DC, at the applied tone frequency (the fundamental), and at a small number of harmonics of the tone frequency. The magnitudes and phases of these spectral components are examined. The spectral magnitudes of the fundamental and various harmonic components generally bear a fixed proportionality to each other over a broad range of signal conditions and nerve-fiber characteristics. This implies that the shape of the underlying rectified wave remains essentially unchanged over a broad range of stimulus intensities. For high-frequency stimuli, the fundamental and harmonic components are substantially attenuated. We provide a theoretical basis for the decrease of the spectralcomponent magnitudes with increasing harmonic number. For low-frequency pure-tone signals, the decrease is caused principally by the uncertainty in the position of neural-event occurrences within the half-wave-rectified period histogram. The lower the stimulus frequency, the greater this time uncertainty and therefore the lower the frequency at which the spectral components begin to diminish. For high-frequency pure-tone signals, on the other hand, the decrease is caused principally by the frequency rolloff associated with nervespike time jitter (it is then called loss of phase locking or loss of synchrony). Since some of this jitter arises from noise in the auditory nerve, it can be minimized by using peak detection rather than level detection. Using a specially designed microcomputer that measures the times at which the peaks of the action potentials occur, we have demonstrated the presence of phase locking to tone frequencies as high as 18 kHz. The traditional view that phase locking is always lost above 6 kHz is clearly not valid. This indicates that the placeversus-periodicity dichotomy in auditory theory requires reexaraination.

  17. Doppler Velocity Estimation Based on Spectral Characteristics of M-Sequence-Modulated Signals in Ultrasonic Measurement for Moving Objects

    NASA Astrophysics Data System (ADS)

    Hirata, Shinnosuke; Hachiya, Hiroyuki

    2013-07-01

    Pulse compression using maximum-length sequence (M-sequence) can improve the signal-to-noise ratio (SNR) of the reflected echo and distance resolution in the pulse-echo method. In the case of a moving object, however, the echo is modulated due to the Doppler effect. The Doppler-shifted M-sequence-modulated signal cannot be correlated with the reference signal, which corresponds to the transmitted M-sequence-modulated signal. Therefore, Doppler velocity estimation before the correlation and cross correlation of the received signal with Doppler-shifted reference signals has been proposed. In this paper, the proposed Doppler velocity estimation based on spectral characteristics of cyclic M-sequence-modulated signals is described. Then, the Doppler velocity estimation is evaluated based on computer simulations. The Doppler velocity can be estimated from the Fourier-transformed spectral density of cycles of the M-sequence-modulated signal with high resolution even in noisy environments. According to the evaluation, furthermore, the cycle number and the number of carrier waves in 1 digit of the M-sequence-modulated signal should be decreased to improve the resolution and accuracy when the length of the transmitted signal is determined.

  18. Caller sex and orientation influence spectral characteristics of "two-voice" stereotyped calls produced by free-ranging killer whales.

    PubMed

    Miller, Patrick J O; Samarra, Filipa I P; Perthuison, Aurélie D

    2007-06-01

    This study investigates how particular received spectral characteristics of stereotyped calls of sexually dimorphic adult killer whales may be influenced by caller sex, orientation, and range. Calls were ascribed to individuals during natural behavior using a towed beamforming array. The fundamental frequency of both high-frequency and low-frequency components did not differ consistently by sex. The ratio of peak energy within the fundamental of the high-frequency component relative to summed peak energy in the first two low-frequency component harmonics, and the number of modulation bands off the high-frequency component, were significantly greater when whales were oriented towards the array, while range and adult sex had little effect. In contrast, the ratio of peak energy in the first versus second harmonics of the low-frequency component was greater in calls produced by adult females than adult males, while orientation and range had little effect. The dispersion of energy across harmonics has been shown to relate to body size or sex in terrestrial species, but pressure effects during diving are thought to make such a signal unreliable in diving animals. The observed spectral differences by signaler sex and orientation suggest that these types of information may be transmitted acoustically by freely diving killer whales.

  19. [Research on chemical oxygen demand optical detection method based on the combination of multi-source spectral characteristics].

    PubMed

    Wu, Guo-Qing; Bi, Wei-Hong

    2014-11-01

    A novel method based on multi-source spectral characteristics of the combination is proposed for chemical oxygen demand detection. First, the ultraviolet and near infrared spectrum of the actual water samples are collected respectively. After pretreatment of the spectrum data, the features of the spectrum are extracted by the nonnegative matrix factorization algorithm for training after normalization. Particle swarm and least squares support vector machines algorithm are applied to predicting chemical oxygen demand of the validation set of water samples. The effect of spectrum's base number on the predicted results is discussed. The experimental results show that the best base number of the ultraviolet spectrum is 5, the best base number of the near infrared spectrum is 2; The validation set correlation coefficient of the prediction model is 0.999 8, and the root mean square error of prediction is 3.26 mg x L(-1). Experimental results demonstrate that the nonnegative matrix factorization algorithm is more suitable for feature extraction of spectral data, and the least squares support vector machines algorithm as a quantitative model correction method of the actual water samples can get good prediction accuracy with different feature extraction methods (principal component analysis, independent component analysis), spectroscopic methods (ultraviolet spectrum method, near infrared spectrum method) and different combination pattern (data direct combination, combining data first, then feature extraction) respectively.

  20. Study of spectral characteristics of radiation from a thermal wake of a pulsating optical discharge in a supersonic air flow

    SciTech Connect

    Malov, A N; Orishich, A M; Terent'eva, Ya S

    2015-10-31

    The spectral characteristics of the thermal wake of a pulsating optical discharge (POD) in a supersonic air flow are studied. The POD is stimulated by radiation of a mechanically Q-switched, repetitively pulsed CO{sub 2} laser with a pulse repetition rate of 7 – 150 kHz and a power up to 4.5 kW. The flow is produced by means of the supersonic aerodynamic MAU-M setup having a conic nozzle with a critical cross-section size of 50 mm, the Mach number being 1.3 – 1.6. We describe in detail the system of optical diagnostics that allows the detection of the spectrum of the weak thermal wake glow against the background of high-power POD radiation. The glow of the thermal wake is due to the emission of light by atoms and ions of nitrogen and oxygen, carried by the flow in the form of hot low-density gas clouds (caverns). The wavelengths of the thermal wake emission and the data on the transitions, corresponding to the spectral lines are presented. (laser applications and other topics in quantum electronics)

  1. [EEG spectral characteristics at different stages of the unconscious visual set in two motivation conditions].

    PubMed

    Kurova, N S; Cheremushkin, E A; Ashkinazi, M L

    2002-01-01

    Multichannel EEG were recorded in young healthy subjects in two series of experiments during formation, actualization, and extinction of the visual unconscious set to the perception of unequal circles under conditions of increased motivation of subjects to the result of their performance. In the first series of experiments, subjects were promised to be rewarded (a small money price) for each correct response (the "general" rise of motivation). In the second series, subjects were promised to be rewarded for correct responses only in cases when one of the circles was larger than the other one (the "directed" rise of motivation). The dynamics of the EEG spectral power derived under these two conditions was compared with similar indices obtained earlier during formation of the same set without any special motivation of subjects (control). In all experimental conditions, before the presentation of the stimuli the EEG power in the alpha range was higher in subjects with the stable set. The dynamics of changes in the alpha power at set stages was principally similar in all conditions. In all the experimental conditions, in subjects with unstable set the EEG power in the delta range was highest at the stage of set actualization. The most pronounced generalized changes in the EEG power in the theta-range during the "general" rise of motivation in subjects with stable and unstable forms of set and greater variability of the reaction time to the probe stimulus suggest that the task performance under these conditions required greater tension than under conditions of the "directed" rise of motivation.

  2. High-Energy Spectral and Temporal Characteristics of GRO J1008-57

    NASA Astrophysics Data System (ADS)

    Shrader, C. R.; Sutaria, F. K.; Singh, K. P.; Macomb, D. J.

    1999-02-01

    A transient X-ray source, GRO J1008-57, was discovered by the Burst and Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory (CGRO) in 1993 July. It reached a maximum intensity of about 1.4 times that of the Crab, in the 20-60 keV energy band. Pulsations in the X-ray intensity were detected at a period of 93.5 s. It has subsequently been determined to be a member of the Be star subclass of X-ray transients. In addition to BATSE, GRO J1008-57 was observed during its outburst by several pointed high-energy experiments: ROSAT, ASCA, and CGRO/OSSE. These nonsimultaneous but contemporaneous observations took place near and shortly after the peak of the outburst light curve. We report for the first time on a combined analysis of the CGRO and ASCA data sets. We have attempted to model the broadband high-energy continuum distribution and phase-resolved spectra. The broadband, phase-averaged continuum is well approximated by a power law with an exponential cutoff. Evidence for 6.4 keV line emission due to Fe is presented based on our spectral analysis. The energy dependence of the pulse profiles is examined in order to determine the energy at which the low-energy double-peaked profile detected by ASCA evolves into single-peaked pulse profile detected by BATSE. We discuss the implications of this pulse profile for the magnetic field and beam distribution for GRO J1008-57. Analysis of the BATSE and Rossi X-Ray Timing Explorer/ASM flux histories suggests that Porbital~135 days. We further suggest that a transient disk is likely to form during episodes of outbursts.

  3. Temporal and spatial temperature distributions in transversely heated graphite tube atomizers and their analytical characteristics for atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Sperling, Michael; Welz, Bernard; Hertzberg, Joachim; Rieck, Christof; Marowsky, Gerd

    1996-07-01

    The important role which temperature plays in atomic absorption spectrometry (AAS) for the formation and detection of atoms in the absorption volume is discussed and the literature is reviewed. Non-homogeneous temperature distribution in the absorption volume is in contradiction to one of the prerequisites for the application of Beer's law used in AAS to convert absorbance into analyte concentration or mass, and is particularly troublesome for an "absolute analysis" envisaged for electrothermal atomic absorption spectrometry (ETAAS). Coherent anti-Stokes Raman scattering (CARS) is used to study the gas-phase temperature distribution in a state-of-the-art transversely heated graphite tube atomizer (THGA). The effect of the internal gas flow on the size of the heated atmosphere is studied by steady-state temperature measurements. Temporally and spatially resolved measurements make it possible to study the temperature field within the atomizer volume in all three dimensions during the rapid heating of the furnace to final temperatures in the range 2173-2673 K. The role of the integrated platform of the THGA on the temperature field is investigated by temperature measurements of the gas phase in the presence and absence of the platform. The platform is identified as the major source of temperature gradients inside the tube volume, which may be as high as 1000 K in the radial direction during rapid heating. These gradients are most pronounced for heating cycles starting at room temperature and gradually decrease with increasing starting temperature. Shortly after the tube wall reaches its final temperature, the gas-phase temperature equilibrates and approaches the wall temperature. Because of the unavoidable contact with the cold environment at the open ends of the tube, minor temperature gradients are observed in the gas phase also in longitudinal direction, which can be further reduced by restricting the openings with end caps. The results obtained for the THGA are

  4. Deuterium absorption and material phase characteristics of Zr{sub 2}Fe

    SciTech Connect

    Nobile, A.; Mosley, W.C.; Holder, J.S.; Brooks, K.N.

    1992-12-30

    Scanning electron microscope (SEM) images of polished surfaces, electron probe microanalysis, and X-ray powder diffractometry indicated the presence of a continuous Zr{sub 2}Fe phase with secondary phases of ZrFe{sub 2}, Zr{sub 5}FeSn, {alpha}-Zr, and Zr{sub 6}Fe{sub 3}O. A statistically-designed experiment to determine the effects of temperature, time, and vacuum quality On activation of St 198 revealed that when activated at low temperature (350{degrees}C) deuterium absorption rate was slower when the vacuum quality was pwr (2.5 Pa vs. 3{times}10{sup {minus}4} Pa). However, at higher activation temperature (500{degrees}C), deuterium absorption rate was fast and was independent of vacuum quality. Deuterium pressure-composition-temperature (P-C-T) data are reported for St 198 in the temperature range 200--500{degrees}C. The P-C-T data over the full range of deuterium loading and at temperatures of 350{degrees}C and below is described by: K{sub 0e}-({Delta}H{sub {alpha}}/RT)=PD{sub 2}q{sup 2}/(q*{minus}q){sup 2} where {Delta}H{alpha} and K{sub 0} have values of 101.8 kJ{center_dot}mole{sup {minus}1} and 3.24{times}10{sup {minus}8}Pa{sup {minus}1}, and q* is 15.998 kPa{center_dot}L{sup {minus}1}{center_dot}g{sup {minus}1}. At higher temperatures, one or more secondary reactions in the solid phase occur that slowly consume D{sub 2} from the gas phase. XRD suggests these reactions to be: 2 Zr{sub 2}FeD{sub x} {yields} x ZrD{sub 2} + x/3 ZrFe{sub 2} + (2 {minus} 2/3x) Zr{sub 2}Fe and Zr{sub 2}FeD{sub x} + (2 {minus}1/2x) D{sub 2} {yields} ZrD{sub 2} + Fe, where 0 < x < 3. Reaction between gas phase deuterium and Zr2FC formed in the first reaction accounts for the observed consumption of deuterium from the gas phase by this reaction.

  5. Characteristics of Organobentonite and Study of Iodide Adsorption on Organobentonite using X-ray Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Yoon, J.; Ha, J.; Hwang, B.; Hwang, J.; Brown, G. E.

    2008-12-01

    The adsorption of iodide on untreated bentonite and bentonites modified with organic cation (i.e., hexadecylpyridinium chloride monohydrate (HDP+)) was investigated, and the organobentonites were characterized using uptake measurements, micro X-ray diffraction (micro-XRD), and electrophoretic mobility measurements prior to reaction with KI solutions. Uptake measurements indicate that bentonite has a high affinity for HDP+. Increasing [HDP+](aq) results in an increase in HDP+ uptake on bentonite by up to 280% of the CEC equivalents of bentonite, and causes a concomitant increase in Na released as a result of the replacement of exchangeable inorganic cations in bentonite interlayers. Based micro-XRD, the d001 spacing of untreated bentonite was 1.22 nm whereas organobentonites modified with HDP+ at different equivalent amounts, corresponding to 100%, 200%, and 400% of the cation exchange capacity (CEC) of bentonite, showed d001 spacings of 1.96 nm, 3.77 nm, and 3.77 nm, respectively. Our micro-XRD study indicates that organobentonites significantly expanded in basal spacing and organic cations were substantially intercalated into the interlayer spaces of montmorillonite. The electrophoretic mobility indicates that the untreated bentonite had a negative surface charge over the entire pH range examined (pH 2-12) whereas the organobentonite at an equivalent amount corresponding to 200% of the CEC had a positive surface charge over this pH range. We found significant differences in adsorption capacities of iodide depending on the bentonite properties as follows: iodide adsorption capacities were 439 mmol/kg for the bentonite modified with HDP+ at an equivalent amount corresponding to 200% of the CEC of bentonite whereas no adsorption of iodide was observed for the untreated bentonite. The molecular environments of iodine adsorbed on organobentonites were further studied using I K-edge and LIII-edge x-ray absorption spectroscopy (XAS). The X-ray absorption near

  6. Quantum spectral rototranslational collision-induced absorption (CIA) in CO2 and CO2-Rg pairs (Rg = He, Ar and Xe): An insightful analysis based on new empirical multi-property isotropic intermolecular potentials

    NASA Astrophysics Data System (ADS)

    El-Kader, M. S. A.; Maroulis, G.

    2017-02-01

    The rototranslational collision-induced absorption (CIA) of carbon dioxide CO2 and of carbon dioxide with inert gas mixtures CO2-He, CO2-Ar and CO2-Xe at different temperature are analyzed in terms of new isotropic intermolecular potentials and multipole-induced dipole function models, using quantum spectral lineshape computations. The irreducible spherical form for the induced operator of light absorption mechanisms was determined. The quality of the present potentials have been checked by comparing between calculated and experimental thermo-physical and transport properties over a wide temperature range. Quite a good agreement is observed for all carbon dioxide noble gas mixtures.

  7. Using naive Bayes classifier for classification of convective rainfall intensities based on spectral characteristics retrieved from SEVIRI

    NASA Astrophysics Data System (ADS)

    Hameg, Slimane; Lazri, Mourad; Ameur, Soltane

    2016-07-01

    This paper presents a new algorithm to classify convective clouds and determine their intensity, based on cloud physical properties retrieved from the Spinning Enhanced Visible and Infrared Imager (SEVIRI). The convective rainfall events at 15 min, 4 × 5 km spatial resolution from 2006 to 2012 are analysed over northern Algeria. The convective rain classification methodology makes use of the relationship between cloud spectral characteristics and cloud physical properties such as cloud water path (CWP), cloud phase (CP) and cloud top height (CTH). For this classification, a statistical method based on `naive Bayes classifier' is applied. This is a simple probabilistic classifier based on applying `Bayes' theorem with strong (naive) independent assumptions. For a 9-month period, the ability of SEVIRI to classify the rainfall intensity in the convective clouds is evaluated using weather radar over the northern Algeria. The results indicate an encouraging performance of the new algorithm for intensity differentiation of convective clouds using SEVIRI data.

  8. The effect of codopants on spectral-kinetic characteristics of luminescence of scintillation glasses doped with terbium ions

    NASA Astrophysics Data System (ADS)

    Valiev, D. T.; Polisadova, E. F.

    2016-10-01

    The effect of Ce3+ and Pr3+ ions on spectral-kinetic characteristics of luminescence of lithium-phosphate-borate glasses is studied. It is shown that terbium ion luminescence caused by transitions from 5 D 3 and 5 D 4 multiplets to the ground 7FJ term is detected in samples containing Tb3+/Ce3+ and Tb3+/Pr3+. It has been found that an increase in the concentration of cerium ions from 0.2 to 1 wt % leads to an increase in the intensity of main luminescence bands of terbium ions. In Tb3+/Pr3+ glasses, a decrease in the relative light yield is observed with an increase in the concentration of Pr3+ ions. Processes of energy transfer between Tb3+/Ce3+ and Tb3+/Pr3+ ions are discussed.

  9. Spectral Characteristics of CN Radical (B → X) and Its Application in Determination of Rotational and Vibrational Temperatures of Plasma

    NASA Astrophysics Data System (ADS)

    Peng, Zhi-Min; Ding, Yan-Jun; Zhai, Xiao-Dong; Yang, Qian-Suo; Jiang, Zong-Lin

    2011-04-01

    The aim is to resolve the difficulties of measurement of temperature at several thousands of Celsius degrees for some unstable non-equilibrium gas flows. Based on the molecular spectroscopy theory and inherent molecular structure characteristics of the CN radical, the dependence of the spectral profile on the rotational temperature (RT), vibrational temperature (VT) and optical apparatus function are numerically explored within some certain ranges. Meanwhile, by comparing the numerically calculated spectra with the experimental spectra of the CN radical, the corresponding RT and VT of the plasma induced by the interaction of the laser pulse from an oscillated Nd:YAG laser with the coal target are determined, respectively. In addition, a short discussion on the thermodynamic state and the energy transfer process of the CN radical is also given.

  10. Influence of the spectral distribution of light on the characteristics of photovoltaic panel. Comparison between simulation and experimental

    NASA Astrophysics Data System (ADS)

    Chadel, Meriem; Bouzaki, Mohammed Moustafa; Chadel, Asma; Petit, Pierre; Sawicki, Jean-Paul; Aillerie, Michel; Benyoucef, Boumediene

    2017-02-01

    We present and analyze experimental results obtained with a laboratory setup based on a hardware and smart instrumentation for the complete study of performance of PV panels using for illumination an artificial radiation source (Halogen lamps). Associated to an accurate analysis, this global experimental procedure allows the determination of effective performance under standard conditions thanks to a simulation process originally developed under Matlab software environment. The uniformity of the irradiated surface was checked by simulation of the light field. We studied the response of standard commercial photovoltaic panels under enlightenment measured by a spectrometer with different spectra for two sources, halogen lamps and sunlight. Then, we bring a special attention to the influence of the spectral distribution of light on the characteristics of photovoltaic panel, that we have performed as a function of temperature and for different illuminations with dedicated measurements and studies of the open circuit voltage and short-circuit current.

  11. Study of spectral/radiometric characteristics of the Thematic Mapper for land use applications

    NASA Technical Reports Server (NTRS)

    Malila, W. A. (Principal Investigator); Metzler, M. D.

    1984-01-01

    Progress during the Environmental Research Institute of Michigan-ERIM's and 5 image data quality assessment program for the thematic mapper is described. Analyses of LANDSAT 5 TM radiometric characteristics were performed. Effects which had earlier been found in LANDSAT 4 TM data were found to be present in LANDSAT 5 data as well, including: (1) scan direction related signal droop; (2) scan correlated level shifts; and (3) low frequency coherent noise. Coincident LANDSAT 4 and 5 raw TM data were analyzed, and band by band relationships between the two sensors were derived. Earlier efforts which developed an information theoretic measure of multispectral information content were continued, comparing TM and MSS information content.

  12. Vegetation species composition and canopy architecture information expressed in leaf water absorption measured in the 1000 nm and 2200 spectral region by an imaging spectrometer

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Roberts, Dar A.

    1995-01-01

    Plant species composition and plant architectural attributes are critical parameters required for the measuring, monitoring, and modeling of terrestrial ecosystems. Remote sensing is commonly cited as an important tool for deriving vegetation properties at an appropriate scale for ecosystem studies, ranging from local to regional and even synoptic scales. Classical approaches rely on vegetation indices such as the normalized difference vegetation index (NDVI) to estimate biophysical parameters such as leaf area index or intercepted photosynthetically active radiation (IPAR). Another approach is to apply a variety of classification schemes to map vegetation and thus extrapolate fine-scale information about specific sites to larger areas of similar composition. Imaging spectrometry provides additional information that is not obtainable through broad-band sensors and that may provide improved inputs both to direct biophysical estimates as well as classification schemes. Some of this capability has been demonstrated through improved discrimination of vegetation, estimates of canopy biochemistry, and liquid water estimates from vegetation. We investigate further the potential of leaf water absorption estimated from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data as a means for discriminating vegetation types and deriving canopy architectural information. We expand our analysis to incorporate liquid water estimates from two spectral regions, the 1000-nm region and the 2200-nm region. The study was conducted in the vicinity of Jasper Ridge, California, which is located on the San Francisco peninsula to the west of the Stanford University campus. AVIRIS data were acquired over Jasper Ridge, CA, on June 2, 1992, at 19:31 UTC. Spectra from three sites in this image were analyzed. These data are from an area of healthy grass, oak woodland, and redwood forest, respectively. For these analyses, the AVIRIS-measured upwelling radiance spectra for the entire Jasper

  13. Infrared absorption and emission characteristics of interstellar PAHs (Polycyclic Aromatic Hydrocarbon)

    SciTech Connect

    Allamandola, L.J.; Tielens, A.G.G.M.; Barker, J.R.

    1986-01-01

    The mid-infrared interstellar emission spectrum with features at 3050, 1610, 1300, 1150, and 885 cm/sup -1/ (3.28, 6.2, 7.7, 8.7 and 11.3 microns) is discussed in terms of the Polycyclic Aromatic Hydrocarbon (PAH) hypothesis. This hypothesis is based on the suggestive, but inconclusive comparison between the interstellar emission spectrum with the infrared absorption and Raman spectra of a few PAHs. The fundamental vibrations of PAHs and PAH-like species which determine the ir and Raman properties are discussed. Interstellar ir band emission is due to relaxation from highly vibrationally excited PAHs which have been excited by ultraviolet photons. The excitation/emission process is described in general and the ir fluorescence from one PAH, chrysene, is traced in detail. Generally, there is sufficient energy to populate several vibrational levels in each mode. Molecular vibrational potentials are anharmonic and emission from these higher levels will fall at lower frequencies and produce weak features to the red of the stronger fundamentals. This process is also described and can account for some spectroscopic details of the interstellar emission spectra previously unexplained. Analysis of the interstellar spectrum shows that PAHs containing between 20 and 30 carbon atoms are responsible for the emission. 43 refs., 11 figs.

  14. Infrared absorption and emission characteristics of interstellar PAHs. [Polycyclic Aromatic Hydrocarbon

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.; Tielens, A. G. G. M.; Barker, J. R.

    1987-01-01

    The mid-infrared interstellar emission spectrum with features at 3.28, 6.2, 7.7, 8.7 and 11.3 microns is discussed in terms of the Polycyclic Aromatic Hydrocarbon (PAH) hypothesis, which is based on the suggestive, but inconclusive comparison between the interstellar emission spectrum with the infrared absorption and Raman spectra of a few PAHs. The fundamental vibrations of PAHs and PAH-like species which determine the IR and Raman properties are discussed. Interstellar IR band emission is due to relaxation from highly vibrationally excited PAHs excited by ultraviolet photons. The excitation/emission process is described and the IR fluorescence from one PAH, chrysene, is traced. Generally, there is sufficient energy to populate several vibrational levels in each mode. Molecular vibrational potentials are anharmonic and emission from these higher levels will fall at lower frequencies and produce weak features to the red of the stronger fundamentals. This process is also described and can account for some spectroscopic details of the interstellar emission spectra previously unexplained. Analysis of the interstellar spectrum shows that PAHs contain between 20 and 30 carbon atoms and are responsible for the emission.

  15. Study on spectral/radiometric characteristics of the thematic mapper for land use applications

    NASA Technical Reports Server (NTRS)

    Malila, W. A. (Principal Investigator); Metzler, M. D.

    1983-01-01

    The change in mean signal level as a function of scan angle and scan direction was studied. The overall scan angle effect corresponded to that expected based on atmospheric modeling and scene characteristics. An initial, empirical correction model employing exponential decay was developed for reflective bands. Band 6 has a significant scan direction effect which is markedly different from that found in the reflective bands. A low frequency noise was discovered which was most pronounced in Band 1, detectors 4, 12, 10, and 8, having amplitudes of approximately 2.0, 1.5, 1.0, and 0.75 quantizing levels, respectively. This low frequency variation in mean signal amplitude was highly correlated among these four Band 1 detectors. Low frequency noise was also observed in Band 7, detector 7; band 2, detector 1; Band 3, detectors 1 and 16; and Band 5, detector 10.

  16. [Analysis of XRD spectral characteristics of soil clay mineral in two typical cultivated soils].

    PubMed

    Zhang, Zhi-Dan; Luo, Xiang-Li; Jiang, Hai-Chao; Li, Qiao; Shen, Cong-Ying; Liu, Hang; Zhou, Ya-Juan; Zhao, Lan-Po; Wang, Ji-Hong

    2014-07-01

    The present paper took black soil and chernozem, the typical cultivated soil in major grain producing area of Northeast, as the study object, and determinated the soil particle composition characteristics of two cultivated soils under the same climate and location. Then XRD was used to study the composition and difference of clay mineral in two kinds of soil and the evolutionary mechanism was explored. The results showed that the two kinds of soil particles were composed mainly of the sand, followed by clay and silt. When the particle accumulation rate reached 50%, the central particle size was in the 15-130 microm interval. Except for black soil profile of Shengli Xiang, the content of clay showed converse sequence to the central particle in two soils. Clay accumulated under upper layer (18.82%) in black soil profile while under caliche layer (17.41%) in chernozem profile. Clay content was the least in parent material horizon except in black profile of Quanyanling. Analysis of clay XRD atlas showed that the difference lied in not only the strength of diffraction peak, but also in the mineral composition. The main contents of black soil and chernozem were both 2 : 1 clay, the composition of black soil was smectite/illite mixed layer-illite-vermiculite and that of chernozem was S/I mixture-illite-montmorillonite, and both of them contained little kaolinite, chlorite, quartz and other primary mineral. This paper used XRD to determine the characteristics of clay minerals comprehensively, and analyzed two kinds of typical cultivated soil comparatively, and it was a new perspective of soil minerals study.

  17. Modeling the effects of wind tunnel wall absorption on the acoustic radiation characteristics of propellers

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.; Eversman, W.

    1986-01-01

    Finite element theory is used to calculate the acoustic field of a propeller in a soft walled circular wind tunnel and to compare the radiation patterns to the same propeller in free space. Parametric solutions are present for a 'Gutin' propeller for a variety of flow Mach numbers, admittance values at the wall, microphone position locations, and propeller to duct radius ratios. Wind tunnel boundary layer is not included in this analysis. For wall admittance nearly equal to the characteristic value of free space, the free field and ducted propeller models agree in pressure level and directionality. In addition, the need for experimentally mapping the acoustic field is discussed.

  18. Modeling the effects of wind tunnel wall absorption on the acoustic radiation characteristics of propellers

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.; Eversman, W.

    1986-01-01

    Finite element theory is used to calculate the acoustic field of a propeller in a soft walled circular wind tunnel and to compare the radiation patterns to the same propeller in free space. Parametric solutions are present for a "Gutin" propeller for a variety of flow Mach numbers, admittance values at the wall, microphone position locations, and propeller to duct radius ratios. Wind tunnel boundary layer is not included in this analysis. For wall admittance nearly equal to the characteristic value of free space, the free field and ducted propeller models agree in pressure level and directionality. In addition, the need for experimentally mapping the acoustic field is discussed.

  19. Aerosol characteristics in north-east India using ARFINET spectral optical depth measurements

    NASA Astrophysics Data System (ADS)

    Pathak, B.; Subba, T.; Dahutia, P.; Bhuyan, P. K.; Moorthy, K. Krishna; Gogoi, M. M.; Babu, S. Suresh; Chutia, L.; Ajay, P.; Biswas, J.; Bharali, C.; Borgohain, A.; Dhar, P.; Guha, A.; De, B. K.; Banik, T.; Chakraborty, M.; Kundu, S. S.; Sudhakar, S.; Singh, S. B.

    2016-01-01

    Four years (2010-2014) of spectral aerosol optical depth (AOD) data from 4 Indian Space Research Organisation's ARFINET (Aerosol Radiative Forcing over India) stations (Shillong, Agartala, Imphal and Dibrugarh) in the North-Eastern Region (NER) of India (lying between 22-30°N and 89-98°E) are synthesized to evolve a regional aerosol representation, for the first time. Results show that the columnar AOD (an indicator of the column abundance of aerosols) is highest at Agartala (0.80 ± 0.24) in the west and lowest at Imphal (0.59 ± 0.23) in the east in the pre-monsoon season due to intense anthropogenic bio-mass burning in this region aided by long-range transport from the high aerosol laden regions of the Indo-Gangetic Plains (IGP), polluted Bangladesh and Bay of Bengal. In addition to local biogenic aerosols and pollutants emitted from brick kilns, oil/gas fields, household bio-fuel/fossil-fuel, vehicles, industries. Aerosol distribution and climatic impacts show a west to east gradient within the NER. For example, the climatological mean AODs are 0.67 ± 0.26, 0.52 ± 0.14, 0.40 ± 0.17 and 0.41 ± 0.23 respectively in Agartala, Shillong, Imphal and Dibrugarh which are geographically located from west to east within the NER. The average aerosol burden in NER ranks second highest with climatological mean AOD 0.49 ± 0.2 next to the Indo-Gangetic Plains where the climatological mean AOD is 0.64 ± 0.2 followed by the South and South-East Asia region. Elevated aerosol layers are observed over the eastern most stations Dibrugarh and Imphal, while at the western stations the concentrations are high near the surface. The climate implications of aerosols are evaluated in terms of aerosol radiative forcing (ARF) and consequent heating of the atmosphere in the region which follows AOD and exhibit high values in pre-monsoon season at all the locations except in Agartala. The highest ARF in the atmosphere occurs in the pre-monsoon season ranging from 48.6 Wm-2 in Agartala

  20. An organic dye-polymer (phenol red-poly (vinyl alcohol)) composite architecture towards tunable -optical and -saturable absorption characteristics

    NASA Astrophysics Data System (ADS)

    Sreedhar, Sreeja; Illyaskutty, Navas; Sreedhanya, S.; Philip, Reji; Muneera, C. I.

    2016-05-01

    Herein, we demonstrate that blending an organic dye (guest/filler), with a vinyl polymer (host template), is an inexpensive and simple approach for the fabrication of multifunctional photonic materials which could display an enhancement in the desirable properties of the constituent materials and, at the same time provide novel synergistic properties for the guest-host system. A new guest-host nanocomposite system comprising Phenol Red dye and poly (vinyl alcohol) as guest and host template, respectively, which exhibits tunable optical characteristics and saturable absorption behavior, is introduced. The dependence of local electronic environment provided by the polymer template and the interactions of the polymer molecules with the encapsulated guest molecules on the observed optical/nonlinear absorption behavior is discussed. An understanding of the tunability of the optical/ photophysical processes, with respect to the filler content, as discussed herein could help in the design of improved optical materials for several photonic device applications like organic light emitting diodes and saturable absorbers.

  1. Ultrasonic absorption characteristics of porous carbon-carbon ceramics with random microstructure for passive hypersonic boundary layer transition control

    NASA Astrophysics Data System (ADS)

    Wagner, Alexander; Hannemann, Klaus; Kuhn, Markus

    2014-06-01

    Preceding studies in the high enthalpy shock tunnel Göttingen of the German Aerospace Center (DLR) revealed that carbon fibre reinforced carbon ceramic (C/C) surfaces can be utilized to damp hypersonic boundary layer instabilities leading to a delay of boundary layer transition onset. To assess the ultrasonic absorption properties of the material, a test rig was set up to measure the reflection coefficient at ambient pressures ranging from 0.1 × 105 to 1 × 105 Pa. For the first time, broadband ultrasonic sound transducers with resonance frequencies of up to 370 kHz were applied to directly cover the frequency range of interest with respect to the second-mode instabilities observed in previous experiments. The reflection of ultrasonic waves from three flat plate test samples with a porous layer thickness between 5 and 30 mm was investigated and compared to an ideally reflecting surface. C/C was found to absorb up to 19 % of the acoustic power transmitted towards the material. The absorption characteristics were investigated theoretically by means of the quasi-homogeneous absorber theory. The experimental results were found to be in good agreement with the theory.

  2. [Analysis of cloud spectral structure characteristics based on cloud profile radar data].

    PubMed

    Han, Yong; Lü, Da-Ren

    2013-04-01

    Cloud plays a very important role in the earth-atmosphere system. However, the current climate models are still lacking data about internal fine structure of cloud. And when the traditional passive satellite radiometer is used for remote sense, a plentiful information of the vertical distribution of cloud layer will be lost. For these reasons, NASA proposed the launch project of CloudSat, Whose purpose is to provide the necessary observation, and then allow us to understand better the internal structure of the cloud. CloudSat was successfully launched on April 28, 2006. It carried the first cloud profile radar (CPR) with W band (94 GHz), which can provide continuous and global time sequence vertical structure and characteristics of cloud. In the present paper, using CloudSat satellite data, we analyzed the 8th "Morakot" and 15th " Koppu" typhoon cloud systems. According to the "typhoon" cloud detection results, the radar reflectivity, cloud types and optical thickness successive variation of cloud layer were gotten, which will provide a reference for studying optical properties of typhoon cloud system.

  3. Spectral reflectance characteristics and automated data reduction techniques which identify wetland and water quality conditions in the Chesapeake Bay

    NASA Technical Reports Server (NTRS)

    Anderson, R. R.

    1970-01-01

    Progress on research designed to test the usability of multispectral, high altitude, remotely sensed data to analyze ecological and hydrological conditions in estuarine environments is presented. Emphasis was placed on data acquired by NASA aircraft over the Patuxent River Chesapeake Bay Test Site, No. 168. Missions were conducted over the Chesapeake Bay at a high altitude flight of 18,460 m and a low altitude flight of 3070. The principle objectives of the missions were: (1) to determine feasibility of identifying source and extent of water pollution problems in Baltimore Harbor, Chesapeake Bay and major tributaries utilizing high altitude, ERTS analogous remote sensing data; (2) to determine the feasibility of mapping species composition and general ecological condition of Chesapeake Bay wetlands, utilizing high altitude, ERTS analogous data; (3) to correlate ground spectral reflectance characteristics of wetland plant species with tonal characteristics on multispectral photography; (4) to determine usefulness of high altitude thermal imagery in delinating isotherms and current patterns in the Chesapeake Bay; and (5) to investigate automated data interpretive techniques which may be usable on high altitude, ERTS analogous data.

  4. Statistical and Spectral Analysis of Wind Characteristics Relevant to Wind Energy Assessment Using Tower Measurements in Complex Terrain

    DOE PAGES

    Belu, Radian; Koracin, Darko

    2013-01-01

    The main objective of the study was to investigate spatial and temporal characteristics of the wind speed and direction in complex terrain that are relevant to wind energy assessment and development, as well as to wind energy system operation, management, and grid integration. Wind data from five tall meteorological towers located in Western Nevada, USA, operated from August 2003 to March 2008, used in the analysis. The multiannual average wind speeds did not show significant increased trend with increasing elevation, while the turbulence intensity slowly decreased with an increase were the average wind speed. The wind speed and direction weremore » modeled using the Weibull and the von Mises distribution functions. The correlations show a strong coherence between the wind speed and direction with slowly decreasing amplitude of the multiday periodicity with increasing lag periods. The spectral analysis shows significant annual periodicity with similar characteristics at all locations. The relatively high correlations between the towers and small range of the computed turbulence intensity indicate that wind variability is dominated by the regional synoptic processes. Knowledge and information about daily, seasonal, and annual wind periodicities are very important for wind energy resource assessment, wind power plant operation, management, and grid integration.« less

  5. Evaluation of the two-photon absorption characteristics of GaSb/GaAs quantum rings

    SciTech Connect

    Wagener, M. C.; Botha, J. R.; Carrington, P. J.; Krier, A.

    2014-07-28

    The optical parameters describing the sub-bandgap response of GaSb/GaAs quantum rings solar cells have been obtained from photocurrent measurements using a modulated pseudo-monochromatic light source in combination with a second, continuous photo-filling source. By controlling the charge state of the quantum rings, the photoemission cross-sections describing the two-photon sub-bandgap transitions could be determined independently. Temperature dependent photo-response measurements also revealed that the barrier for thermal hole emission from the quantum rings is significantly below the quantum ring localisation energy. The temperature dependence of the sub-bandgap photo-response of the solar cell is also described in terms of the photo- and thermal-emission characteristics of the quantum rings.

  6. [Study on spectral characteristic of dissolved organic matter fractions extracted from municipal solid waste landfill leachate].

    PubMed

    Zhang, Jun-Zheng; Yang, Qian; Xi, Bei-Dou; Wei, Zi-Min; He, Xiao-Song; Li, Ming-Xiao; Yang, Tian-Xue

    2008-11-01

    In the present study, the samples of landfill leachate of 0, 5, 10-year-old were respectively taken from landfill plant. Based on a modified Leenheer fractionation scheme, dissolved organic matter (DOM) extracted from landfill leachate of three different ages was fractioned according to their polarities and charge characteristics by using XAD-8 resin, and the fractions of hydrophobic acid (HOA), neutral (HON) and hydrophilic matter (HIM) were obtained, Then the fluorescence and UV spectra of DOM fractions were determined. The fluorescence synchronous scan spectra of DOM fractions exhibited a primary peak at 280 nm for 0-year-old, while the primary peak exhibited at 340nm for 5 and 10 year-old, suggesting that DOM fractions contained mainly protein-like matter at initial stage of landfill, and with the increase in landfill ages, aromatic structures of DOM fractions in leachate were enriched. Among the DOM fractions of HOA, HON and HIM at different ages of landfill leachate, the fluorescence and UV spectra all indicated that the molecular weight, content of aromatic compounds and degree of condensation were all in the order of HOA>HON>HIM. The ratio of UV absorbance at 253 nm to that at 203 nm (A253/A203) showed, that the substituent on the aromatic ring of HOA and HON fractions consisted mainly of carbonyl, carboxyl and hydroxyl; while that of HIM consisted of aliphatic chains, and the content of aromatic compounds was lower than that of HOA and HON; which implied that the HIM displayed a lower molecular weight and simpler structure compared to HOA and HON. Altogether, the results obtained from fluorescence and UV spectra indicate that the degree of aromatization increased in DOM fractions of leachate with the landfill ages, in the following order: HOA > HON > HIM.

  7. The energy and spectral characteristics of a room-temperature pulsed laser on a ZnS:Fe2+ polycrystal

    NASA Astrophysics Data System (ADS)

    Firsov, K. N.; Gavrishchuk, E. M.; Ikonnikov, V. B.; Kazantsev, S. Yu; Kononov, I. G.; Kotereva, T. V.; Savin, D. V.; Timofeeva, N. A.

    2016-04-01

    The energy and spectral characteristics of a laser on a ZnS:Fe2+ polycrystal operating at room temperature have been studied. The laser was pumped by a non-chain electro-discharge HF laser with a full-width at half-maximum pulse duration of ~140 ns. The diameter of the pumping radiation spot on the crystal surface was 3.8& mm. The two-sided diffuse doping of a polycrystalline CVD-ZnS sample with the surfaces preliminarily coated by high-purity iron films was performed in the process of hot isostatic pressing (HIP) in an argon atmosphere at a pressure of 100 MPa and temperature of 1290 °C. Increasing the duration of the HIP treatment from 54 h to 72 h made it possible to obtain twice the doping depth, and correspondingly, twice the length of active medium. As a result, the slope laser efficiency with respect to the absorbed energy was raised by a factor of 1.75 as compared to the value obtained in our earlier work with a polycrystalline sample. The generation energy was 25 mJ at a slope efficiency of ηslope = 35%. It was established that the generation spectra of the laser with a non-selective resonator have a linear structure with intervals between the neighboring lines of δλ 6 ÷ 8 nm, which is spurious for solid-state lasers. The spectral structure observed is not related to the elements inside the resonator, which might form Fabry-Perot interferometers.

  8. Kinetic equations for a density matrix describing nonlinear effects in spectral line wings

    SciTech Connect

    Parkhomenko, A. I. Shalagin, A. M.

    2011-11-15

    Kinetic quantum equations are derived for a density matrix with collision integrals describing nonlinear effects in spectra line wings. These equations take into account the earlier established inequality of the spectral densities of Einstein coefficients for absorption and stimulated radiation emission by a two-level quantum system in the far wing of a spectral line in the case of frequent collisions. The relationship of the absorption and stimulated emission probabilities with the characteristics of radiation and an elementary scattering event is found.

  9. Characteristic performance evaluation of a photon counting Si strip detector for low dose spectral breast CT imaging

    SciTech Connect

    Cho, Hyo-Min; Ding, Huanjun; Molloi, Sabee; Barber, William C.; Iwanczyk, Jan S.

    2014-09-15

    Purpose: The possible clinical applications which can be performed using a newly developed detector depend on the detector's characteristic performance in a number of metrics including the dynamic range, resolution, uniformity, and stability. The authors have evaluated a prototype energy resolved fast photon counting x-ray detector based on a silicon (Si) strip sensor used in an edge-on geometry with an application specific integrated circuit to record the number of x-rays and their energies at high flux and fast frame rates. The investigated detector was integrated with a dedicated breast spectral computed tomography (CT) system to make use of the detector's high spatial and energy resolution and low noise performance under conditions suitable for clinical breast imaging. The aim of this article is to investigate the intrinsic characteristics of the detector, in terms of maximum output count rate, spatial and energy resolution, and noise performance of the imaging system. Methods: The maximum output count rate was obtained with a 50 W x-ray tube with a maximum continuous output of 50 kVp at 1.0 mA. A{sup 109}Cd source, with a characteristic x-ray peak at 22 keV from Ag, was used to measure the energy resolution of the detector. The axial plane modulation transfer function (MTF) was measured using a 67 μm diameter tungsten wire. The two-dimensional (2D) noise power spectrum (NPS) was measured using flat field images and noise equivalent quanta (NEQ) were calculated using the MTF and NPS results. The image quality parameters were studied as a function of various radiation doses and reconstruction filters. The one-dimensional (1D) NPS was used to investigate the effect of electronic noise elimination by varying the minimum energy threshold. Results: A maximum output count rate of 100 million counts per second per square millimeter (cps/mm{sup 2}) has been obtained (1 million cps per 100 × 100 μm pixel). The electrical noise floor was less than 4 keV. The energy

  10. Characteristic performance evaluation of a photon counting Si strip detector for low dose spectral breast CT imaging

    PubMed Central

    Cho, Hyo-Min; Barber, William C.; Ding, Huanjun; Iwanczyk, Jan S.; Molloi, Sabee

    2014-01-01

    Purpose: The possible clinical applications which can be performed using a newly developed detector depend on the detector's characteristic performance in a number of metrics including the dynamic range, resolution, uniformity, and stability. The authors have evaluated a prototype energy resolved fast photon counting x-ray detector based on a silicon (Si) strip sensor used in an edge-on geometry with an application specific integrated circuit to record the number of x-rays and their energies at high flux and fast frame rates. The investigated detector was integrated with a dedicated breast spectral computed tomography (CT) system to make use of the detector's high spatial and energy resolution and low noise performance under conditions suitable for clinical breast imaging. The aim of this article is to investigate the intrinsic characteristics of the detector, in terms of maximum output count rate, spatial and energy resolution, and noise performance of the imaging system. Methods: The maximum output count rate was obtained with a 50 W x-ray tube with a maximum continuous output of 50 kVp at 1.0 mA. A109Cd source, with a characteristic x-ray peak at 22 keV from Ag, was used to measure the energy resolution of the detector. The axial plane modulation transfer function (MTF) was measured using a 67 μm diameter tungsten wire. The two-dimensional (2D) noise power spectrum (NPS) was measured using flat field images and noise equivalent quanta (NEQ) were calculated using the MTF and NPS results. The image quality parameters were studied as a function of various radiation doses and reconstruction filters. The one-dimensional (1D) NPS was used to investigate the effect of electronic noise elimination by varying the minimum energy threshold. Results: A maximum output count rate of 100 million counts per second per square millimeter (cps/mm2) has been obtained (1 million cps per 100 × 100 μm pixel). The electrical noise floor was less than 4 keV. The energy resolution

  11. The Zugspitze radiative closure experiment for quantifying water vapor absorption over the terrestrial and solar infrared - Part 2: Accurate calibration of high spectral-resolution infrared measurements of surface solar radiation

    NASA Astrophysics Data System (ADS)

    Reichert, Andreas; Rettinger, Markus; Sussmann, Ralf

    2016-09-01

    Quantitative knowledge of water vapor absorption is crucial for accurate climate simulations. An open science question in this context concerns the strength of the water vapor continuum in the near infrared (NIR) at atmospheric temperatures, which is still to be quantified by measurements. This issue can be addressed with radiative closure experiments using solar absorption spectra. However, the spectra used for water vapor continuum quantification have to be radiometrically calibrated. We present for the first time a method that yields sufficient calibration accuracy for NIR water vapor continuum quantification in an atmospheric closure experiment. Our method combines the Langley method with spectral radiance measurements of a high-temperature blackbody calibration source (< 2000 K). The calibration scheme is demonstrated in the spectral range 2500 to 7800 cm-1, but minor modifications to the method enable calibration also throughout the remainder of the NIR spectral range. The resulting uncertainty (2σ) excluding the contribution due to inaccuracies in the extra-atmospheric solar spectrum (ESS) is below 1 % in window regions and up to 1.7 % within absorption bands. The overall radiometric accuracy of the calibration depends on the ESS uncertainty, on which at present no firm consensus has been reached in the NIR. However, as is shown in the companion publication Reichert and Sussmann (2016), ESS uncertainty is only of minor importance for the specific aim of this study, i.e., the quantification of the water vapor continuum in a closure experiment. The calibration uncertainty estimate is substantiated by the investigation of calibration self-consistency, which yields compatible results within the estimated errors for 91.1 % of the 2500 to 7800 cm-1 range. Additionally, a comparison of a set of calibrated spectra to radiative transfer model calculations yields consistent results within the estimated errors for 97.7 % of the spectral range.

  12. Facile synthesis of self-assembled SnO nano-square sheets and hydrogen absorption characteristics

    SciTech Connect

    Iqbal, M. Zubair; Wang, Fengping; Feng, Ting; Zhao, Hailei; Rafique, M. Yasir; Rafi ud Din; Farooq, M. Hassan; Javed, Qurat ul ain; Khan, Dil Faraz

    2012-11-15

    hydrogen absorption characteristics of SnO nano-square sheets performed at 373 K shows good absorption capacity of 1.194 wt.%.

  13. Experimental studies on output, spatial, and spectral characteristics of a microdroplet dye laser containing intralipid as a highly scattering medium

    SciTech Connect

    Taniguchi, Hiroshi; Tanosaki, Shinji; Tsujita, Kazuhiro; Inaba, Humio

    1996-11-01

    Lasing characteristics of Rhodamine 6G dye-doped microdroplets containing highly scattering fat emulsion Intralipid-10% are studied experimentally. Noteworthy findings are that well-defined lasing threshold can be observed and one order or more magnitude enhancement of emission intensity with suitable (optimum) conditions of the Intralipid mixing ratio, in comparison with original neat-dye lasing microdroplets. The authors present and discuss the measured results of input-output intensities for different dye concentrations and dye-Intralipid mixing ratios in this high-gain laser dye-soft scatterer system and microscope images of spatial distribution of light emission from both the microdroplets containing neat-dye and dye-Intralipid mixture. It was found that almost no-lasing neat-dye microdroplets, which have either much higher or much lower dye concentration, can achieve lasing by substituting suitably certain amounts of the Intralipid, causing multiple light scattering. Spectral measurements of lasing outputs from the Rhodamine 6G dye-Intralipid microdroplets show the tendency of the disappearance of the well-known mode structures, owing to the morphology-dependent resonances of this microspherical cavity inherent to the neat-dye microdroplets. It is their belief that the present results make this novel method of dye-Intralipid microsystem very attractive for a variety of future applications, including diagnostic tools for highly sensitive detection and identification of small quantity objects and species embedded or hidden in highly scattering media.

  14. [Characteristic wavelengths selection of soluble solids content of pear based on NIR spectral and LS-SVM].

    PubMed

    Fan, Shu-xiang; Huang, Wen-qian; Li, Jiang-bo; Zhao, Chun-jiang; Zhang, Bao-hua

    2014-08-01

    To improve the precision and robustness of the NIR model of the soluble solid content (SSC) on pear. The total number of 160 pears was for the calibration (n=120) and prediction (n=40). Different spectral pretreatment methods, including standard normal variate (SNV) and multiplicative scatter correction (MSC) were used before further analysis. A combination of genetic algorithm (GA) and successive projections algorithm (SPA) was proposed to select most effective wavelengths after uninformative variable elimination (UVE) from original spectra, SNV pretreated spectra and MSC pretreated spectra respectively. The selected variables were used as the inputs of least squares-support vector machine (LS-SVM) model to build models for de- termining the SSC of pear. The results indicated that LS-SVM model built using SNVE-UVE-GA-SPA on 30 characteristic wavelengths selected from full-spectrum which had 3112 wavelengths achieved the optimal performance. The correlation coefficient (Rp) and root mean square error of prediction (RMSEP) for prediction sets were 0.956, 0.271 for SSC. The model is reliable and the predicted result is effective. The method can meet the requirement of quick measuring SSC of pear and might be important for the development of portable instruments and online monitoring.

  15. Growth, spectral, linear and nonlinear optical characteristics of an efficient semiorganic acentric crystal: L-valinium L-valine chloride

    NASA Astrophysics Data System (ADS)

    Nageshwari, M.; Jayaprakash, P.; Kumari, C. Rathika Thaya; Vinitha, G.; Caroline, M. Lydia

    2017-04-01

    An efficient nonlinear optical semiorganic material L-valinium L-valine chloride (LVVCl) was synthesized and grown-up by means of slow evaporation process. Single crystal XRD evince that LVVCl corresponds to monoclinic system having acentric space group P21. The diverse functional groups existing in LVVCl were discovered with FTIR spectral investigation. The UV-Visible and photoluminescence spectrum discloses the optical and electronic properties respectively for the grown crystal. Several optical properties specifically extinction coefficient, reflectance, linear refractive index, electrical and optical conductivity were also determined. The SEM analysis was also carried out and it portrayed the surface morphology of LVVCl. The calculated value of laser damage threshold was 2.59 GW/cm2. The mechanical and dielectric property of LVVCl was investigated employing microhardness and dielectric studies. The second and third order nonlinear optical characteristics of LVVCl was characterized utilizing Kurtz Perry and Z scan technique respectively clearly suggest its suitability in the domain of optics and photonics.

  16. Program in C for studying characteristic properties of two-body interactions in the framework of spectral distribution theory

    NASA Astrophysics Data System (ADS)

    Launey, K. D.; Sarbadhicary, S.; Dytrych, T.; Draayer, J. P.

    2014-01-01

    We present a program in C that employs spectral distribution theory for studies of characteristic properties of a many-particle quantum-mechanical system and the underlying few-body interaction. In particular, the program focuses on two-body nuclear interactions given in a JT-coupled harmonic oscillator basis and calculates correlation coefficients, a measure of similarity of any two interactions, as well as Hilbert-Schmidt norms specifying interaction strengths. An important feature of the program is its ability to identify the monopole part (centroid) of a 2-body interaction, as well as its 'density-dependent' one-body and two-body part, thereby providing key information on the evolution of shell gaps and binding energies for larger nuclear systems. As additional features, we provide statistical measures for 'density-dependent' interactions, as well as a mechanism to express an interaction in terms of two other interactions. This, in turn, allows one to identify, e.g., established features of the nuclear interaction (such as pairing correlations) within a general Hamiltonian. The program handles the radial degeneracy for 'density-dependent' one-body interactions and together with an efficient linked list data structure, facilitates studies of nuclear interactions in large model spaces that go beyond valence-shell applications.

  17. Spectral-Luminescent, Photochemical, and Lasing Characteristics of Boron Dipyrromethene Difluoro (III) Derivatives in Liquid and Solid-State Media

    NASA Astrophysics Data System (ADS)

    Kuznetsova, R. T.; Aksenova, Yu. V.; Prokopenko, A. A.; Bashkirtsev, D. E.; Tel'minov, E. N.; Arabei, S. M.; Pavich, T. A.; Solovyov, K. N.; Antina, E. V.

    2016-08-01

    Optical properties of some boron dipyrromethene difluoro (III) (BF2-dipyrromethene) derivatives are studied depending on the ligand structure, the medium in which they are incorporated, irradiation time, and radiation wavelength. Prospects for application of the prepared solid-state media painted by the examined compounds in various optical devices used in modern technologies are demonstrated. These are active laser media in the range 550-565 nm based on three-component silicate matrices with high laser damage threshold and sensor media based on boron difluoride complexes of halogen-substituted dipyrromethenes incorporated into an organic polymer for the determination of oxygen concentration in a gas mixture. Spectral, energy, and resource characteristics of lasing of solid-state elements are presented. The effect of reversible dye photounpainting in three-component silicate matrices with subsequent restoration in the darkness is discovered. Possible reasons for this effect are discussed with allowance for which laser media with increased photostability can be prepared. A high sensitivity of the sensor medium based on diiodinated complex of BF2-dipyrromethene incorporated into polyvinyl butyral is obtained. Reasons for the increase in the response time to the change of the gas mixture when going over to neutral argon and possibilities of its elimination are discussed.

  18. Cirrus cloud optical and microphysical property retrievals from eMAS during SEAC4RS using bi-spectral reflectance measurements within the 1.88 µm water vapor absorption band

    NASA Astrophysics Data System (ADS)

    Meyer, Kerry; Platnick, Steven; Arnold, G. Thomas; Holz, Robert E.; Veglio, Paolo; Yorks, John; Wang, Chenxi

    2016-04-01

    Previous bi-spectral imager retrievals of cloud optical thickness (COT) and effective particle radius (CER) based on the Nakajima and King (1990) approach, such as those of the operational MODIS cloud optical property retrieval product (MOD06), have typically paired a non-absorbing visible or near-infrared wavelength, sensitive to COT, with an absorbing shortwave or mid-wave infrared wavelength sensitive to CER. However, in practice it is only necessary to select two spectral channels that exhibit a strong contrast in cloud particle absorption. Here it is shown, using eMAS observations obtained during NASA's SEAC4RS field campaign, that selecting two absorbing wavelength channels within the broader 1.88 µm water vapor absorption band, namely the 1.83 and 1.93 µm channels that have sufficient differences in ice crystal single scattering albedo, can yield COT and CER retrievals for thin to moderately thick single-layer cirrus that are reasonably consistent with other solar and IR imager-based and lidar-based retrievals. A distinct advantage of this channel selection for cirrus cloud retrievals is that the below-cloud water vapor absorption minimizes the surface contribution to measured cloudy top-of-atmosphere reflectance, in particular compared to the solar window channels used in heritage retrievals such as MOD06. This reduces retrieval uncertainty resulting from errors in the surface reflectance assumption and reduces the frequency of retrieval failures for thin cirrus clouds.

  19. Spectral and photoelectric characteristics of the gamma irradiated intrinsic oxide-InSe heterostructures obtained under different conditions

    NASA Astrophysics Data System (ADS)

    Sydor, O. M.

    2016-09-01

    The investigations of photoelectric characteristics and photoresponce spectral dependences were carried out for intrinsic oxide-InSe heterostructures (HSs) and their changes induced by bremsstrahlung γ-quanta with an energy of 1-34 MeV at fluences of 1012-1015 cm-2. The thermal oxidation of the p-InSe:Cd substrates was carried out at a temperature of 420 °C. For three selected groups of samples the duration of the process was 15 min, 60 min, and 96 h. At a short-term oxidation (15 and 60 min) a layer of In2O3 appears. The only difference between the samples of these two groups is a higher photosensitivity in the range of energy 1.25-2.8 eV of the HSs obtained after the 60 min oxidation. At the long-term oxidation the photoresponce spectra η(hν) of the obtained HSs are characterized with a sharp short-wavelength decrease at hν≅2.0 eV. It is established that the intrinsic oxide films act as transparent barrier electrodes in the corresponding HSs and are low-sensitive to γ-irradiation in the all range of fluences. The shape of the photoresponce spectra for all the gamma irradiated HSs remains practically the same. However, it was found: (i) some decrease of photosensitivity at the long-wavelength edge, (ii) decreasing the width of η(hν) at half-height, (iii) the appearance of the exciton peak, (iv) the improvement of a slope of the low-energy edge of the photoresponce spectra with increasing irradiation dose whereas at the maximum fluence this parameter decreases, and (v) the slight extension of the spectral sensitivity to the short-wavelength range for the structures obtained after oxidation for 96 h. The photoelectric parameters of the intrinsic oxide-p-InSe HSs, open circuit voltage Voc, short-circuit current Jsc, current SIλmax and voltage SVλmax sensitivities become only improved after irradiation with the fluences 1012-1013 cm-2. At the maximum fluence a small decreasing of the values of Voc and Jsc was detected except for the structures obtained

  20. Dynamic mechanical analysis and high strain-rate energy absorption characteristics of vertically aligned carbon nanotube reinforced woven fiber-glass composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The dynamic mechanical behavior and energy absorption characteristics of nano-enhanced functionally graded composites, consisting of 3 layers of vertically aligned carbon nanotube (VACNT) forests grown on woven fiber-glass (FG) layer and embedded within 10 layers of woven FG, with polyester (PE) and...

  1. Evaluation of metal ion absorptive characteristics of three types of plastic sample bags used for pecipitation sampling

    USGS Publications Warehouse

    Good, A.B.; Schroder, L.J.

    1984-01-01

    Simulated precipitation samples containing 16 metal ions were prepared at 4 pH values. Absorptive characteristics of polypropylene, polyethylene, and polyester/polyolefin sacks were evaluated at pH 3.5, 4.0, 4.5, and 5.0. Simulated precipitation was in contact with the sacks for 17 days, and subsamples were removed for chemical analysis at 3, 7, 10, 14, and 17 days after initial contact. All three types of plastic sacks absorbed Fe throughout the entire pH range. Polypropylene and polyethylene absorbed Pb throughout the entire pH range; polyester/polyolefin sacks absorbed Pb at pH 4.0 or greater. All plastic sacks also absorbed Cu, Mo, and V at pH 4.5 and 5.0. Leaching the plastic sacks with 0.7 percent HNO3 did not result in 100 percent of Cu, Fe, Pb, and V. These sacks would be suitable collection vessels for Ba, Be, Ca, Cd, Co, Li, Mg, Mn, Na Sr and Zn in precipitation through the pH range of 3.5 to 5.0.

  2. Titan's Aerosol and Stratospheric Ice Opacities Between 18 and 500 Micrometers: Vertical and Spectral Characteristics from Cassini CIRS

    NASA Technical Reports Server (NTRS)

    Anderson, Carrie M.; Samuelson, Robert E.

    2011-01-01

    Vertical distributions and spectral characteristics of Titan's photochemical aerosol and stratospheric ices are determined between 20 and 560 per centimeter (500-18 micrometers) from the Cassini Composite Infrared Spectrometer (CIRS). Results are obtained for latitudes of 15 N, 15 S, and 58 S, where accurate temperature profiles can be independently determined. In addition, estimates of aerosol and ice abundances at 62 N relative to those at 15 S are derived. Aerosol abundances are comparable at the two latitudes, but stratospheric ices are approximately 3 times more abundant at 62 N than at 15 S. Generally, nitrile ice clouds (probably HCN and HC3N), as inferred from a composite emission feature at approximately 160 per centimeter, appear to be located over a narrow altitude range in the stratosphere centered at approximately 90 km. Although most abundant at high northern latitudes, these nitrile ice clouds extend down through low latitudes and into mid southern latitudes, at least as far as 58 S. There is some evidence of a second ice cloud layer at approximately 60 km altitude at 58 S associated with an emission feature at approximately 80 per centimeter. We speculate that the identify of this cloud may be due to C2H6 ice, which in the vapor phase is the most abundant hydrocarbon (next to CH4) in the stratosphere of Titan. Unlike the highly restricted range of altitudes (50-100 km) associated with organic condensate clouds, Titan's photochemical aerosol appears to be well-mixed from the surface to the top of the stratosphere near an altitude of 300 km, and the spectral shape does not appear to change between 15 N and 58 S latitude. The ratio of aerosol-to-gas scale heights range from 1.3-2.4 at about 160 km to 1.1-1.4 at 300 km, although there is considerable variability with latitude, The aerosol exhibits a very broad emission feature peaking at approximately 140 per centimeter. Due to its extreme breadth and low wavenumber, we speculate that this feature may

  3. BRIEF COMMUNICATIONS: Influence of the profile of the spectral line of vibrations of a medium on the time characteristics of stimulated scattering

    NASA Astrophysics Data System (ADS)

    Bel'dyugin, Igor'M.; Zolotarev, M. V.; Sviridov, K. A.

    1985-01-01

    A theoretical analysis is made of the problem of the time taken to establish steady-state lasing as a result of various types of stimulated scattering (Raman, Brillouin, and excited by heat evolution in a medium) and of the law governing amplification of Stokes waves after times much shorter than the relaxation time of vibrations of the medium for an arbitrary spectral line profile. It is shown that the characteristic times for the establishment of steady-state lasing in the case of stimulated scattering near the maximum of the gain profile are of the same type for different spectral lines profiles and have similar values.

  4. [Plant Spectral Discrimination Based on Phenological Features].

    PubMed

    Zhang, Lei; Zhao, Jian-long; Jia, Kun; Li, Xiao-song

    2015-10-01

    Spectral analysis plays a significant role onplant characteristic identification and mechanism recognition, there were many papers published on the aspects of absorption features in the spectra of chlorophyll and moisture, spectral analysis onvegetation red edge effect, spectra profile feature extraction, spectra profile conversion, vegetation leaf structure and chemical composition impacts on the spectra in past years. However, fewer researches issued on spectral changes caused by plant seasonal changes of life form, chlorophyll, leaf area index. This paper studied on spectral observation of 11 plants of various life form, plant leaf structure and its size, phenological characteristics, they include deciduous forest with broad vertical leaf, needle leaf evergreen forest, needle leaf deciduous forest, deciduous forest with broadflat leaf, high shrub with big leaf, high shrub with little leaf, deciduous forest with broad little leaf, short shrub, meadow, steppe and grass. Field spectral data were observed with SVC-HR768 (Spectra Vista company, USA), the band width covers 350-2 500 nm, spectral resolution reaches 1-4 nm. The features of NDVI, spectral maximum absorption depth in green band, and spectral maximum absorption depth in red band were measured after continuum removal processing, the mean, amplitude and gradient of these features on seasonal change profile were analyzed, meanwhile, separability research on plant spectral feature of growth period and maturation period were compared. The paper presents a calculation method of separability of vegetation spectra which consider feature spatial distances. This index is carried on analysis of the vegetation discrimination. The results show that: the spectral features during plant growth period are easier to distinguish than them during maturation period. With the same features comparison, plant separability of growth period is 3 points higher than it during maturation period. The overall separabilityof vegetation

  5. Analysis of excitation mechanisms of Ho3+ upconversion luminescence in Ho3+:LiYbF4 (0.2 at %) crystal via photographs of its longitudinal cross sections and via spectral and kinetic characteristics

    NASA Astrophysics Data System (ADS)

    Kazakov, B. N.; Mikheev, A. V.; Goriev, O. G.; Korableva, S. L.; Semashko, V. V.

    2016-10-01

    The results of a complex analysis of the excitation mechanisms of the up conversion luminescence of Ho3+:LiYbF4 (0.2 at %) crystal are presented. The spatial distribution of the upconversion luminescence intensity is studied by the photographs of longitudinal cross sections at different positions of the laser beam waist with respect to the sample. The surface power density of the pump laser diode radiation (0.755 W, λ = 933 nm) was changed by focusing the beam (similar to Z-scanning). The dependences of the longitudinal luminescence cross sections, as well as of the spectral and kinetic characteristics of Ho3+ and Yb3+ luminescence, on the position of the laser beam waist are determined. It is found that there exist two different mechanisms of the population of the energy levels of Ho3+ ions from which green and red luminescence occur, namely, cooperative sensitization of luminescence and absorption of induced photon groups (JETP Letters, 102 (5), 279 (2015)). It is shown that the contributions of these mechanisms vary both in time and over the crystal volume. All the observed spatial, spectral, and temporal specific features of the upconversion luminescence of Ho3+:LiYbF4 (0.2 at %) crystal are qualitatively explained.

  6. Spectral Characteristics of Landslide Induced Seismicity: Experimental Validation Based on the Use of an Up-Scaled Sheer Box

    NASA Astrophysics Data System (ADS)

    Yfantis, G.; Carvajal, H. E. M.; Pytharouli, S.; Lunn, R. J.

    2014-12-01

    Microseismic monitoring has been used for the last 20 years as a tool to understand the landslide mechanisms and to help develop a methodology able to provide real time information regarding landslide behavior. These studies involve deployment of seismic sensors at active slopes, with data usually analyzed and interpreted along with data obtained using other monitoring methods, e.g. geodetic/geotechnical monitoring. The interpretation of the records is based on a number of assumptions regarding the nature of the recorded signals resulting in big uncertainties. In order to overcome this problem, we use an up-scaled sheer box to reproduce seismic signals as those emitted by the movement of a landslide. The experimental set up consists of a 65cm diameter and 50cm high concrete cylinder filled with unsaturated soil. The cylinder is pulled along a surficial corridor with the same type of soil under varying vertical loading conditions and the friction at the interface between the soil in cylinder and soil on corridor emits seismic signals. The signals are recorded by a network of 7 short period 3D seismic sensors at distances ranging from 4 to 15m from the cylinder. We analyse the recorded signals in the frequency and time-frequency domain. The obtained significant frequencies range up to 120Hz. Their amplitude changes depending on the source-to-sensor distance (attenuation effect) and the applied vertical load (simulating different depths of the failure plane). The spectral characteristics of the emitted signals when compared to those of signals emitted from a vertical face failure in very similar geological and loading conditions at a nearby site are consistent. Therefore, this experimental set-up is a good analogue for the study of landslide induced seismicity. The suggested methodology can be a powerful tool in studying the effects of the type of soil, the loading conditions on the failure plane, the degree of saturation and compaction of the soil on signals recorded

  7. Spectral zone selection methodology for pebble bed reactors

    SciTech Connect

    Ramatsemela Mphahlele; Abderrafi M. Ougouag; Kostadin N. Ivanov; Hans D. Gougar

    2011-01-01

    A methodology is developed for determining boundaries of spectral zones for pebble bed reactors. A spectral zone is defined as a region made up of a number of nodes whose characteristics are collectively similar and that are assigned the same few-group diffusion constants. The spectral zones are selected in such a manner that the difference (error) between the reference transport solution and the diffusion code solution takes a minimum value. This is achieved by choosing spectral zones through optimally minimizing this error. The objective function for the optimization algorithm is the total reaction rate error, which is defined as the sum of the leakage, absorption and fission reaction rates errors in each zone. The selection of these spectral zones is such that the core calculation results based on diffusion theory are within an acceptable tolerance as compared to a proper transport reference solution. Through this work, a consistent approach for identifying spectral zones that yield more accurate diffusion results is introduced.

  8. VIIRS S-NPP Nighttime DNB Spectral Response Function (SRF): The At-launch Characteristics and How the SRF Changes with Time Due to Tungsten Oxides Chromaticity

    NASA Astrophysics Data System (ADS)

    Guenther, B.; Lei, N.; Moeller, C.

    2015-12-01

    The VIIRS Day-Night Band (DNB) is designed with 3 gain stages: Low (LGS), Mid (MGS) and High (HGS) to span bright daytime to moonlit night earth scene signal levels. The published at-launch DNB relative spectral response (RSR) is based upon the LGS spectral measurements, since it was well measured in the pre-launch test program and the LGS can be calibrated by the on-board solar diffuser (MGS and HGS saturate on the SD). The LGS RSR however does not fully represent the spectral characteristics of nighttime DNB data from the MGS and HGS. Nighttime data users who apply the detailed DNB spectral characteristics in their analyses should use modulated RSR appropriate to the MGS and HGS observations. The RSR modulation is due to spectral darkening of the 4 mirrors of the S-NPP VIIRS telescope, which were contaminated with tungsten oxides in fabrication. These tungsten oxides are 'in family' with transition lenses on eyeglasses that darken when exposed to sunlight but do not recover when VIIRS goes into darkness because VIIRS in space is in a vacuum (transition lenses require atmospheric oxygen to recover). The on-going mirror darkening has caused a time-dependent shift in DNB RSR towards blue wavelengths. This presentation will provide access to the correct RSR to use for S-NPP DNB nighttime data over the mission time on-orbit. The changes in characteristics will be described in engineering terms to facilitate clear user understanding of how to handle RSR for nighttime observations over the mission lifetime.

  9. Concentration, sources and light absorption characteristics of dissolved organic carbon on a medium-sized valley glacier, northern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Yan, Fangping; Kang, Shichang; Li, Chaoliu; Zhang, Yulan; Qin, Xiang; Li, Yang; Zhang, Xiaopeng; Hu, Zhaofu; Chen, Pengfei; Li, Xiaofei; Qu, Bin; Sillanpää, Mika

    2016-11-01

    Light-absorbing dissolved organic carbon (DOC) constitutes a major part of the organic carbon in glacierized regions, and has important influences on the carbon cycle and radiative forcing of glaciers. However, few DOC data are currently available from the glacierized regions of the Tibetan Plateau (TP). In this study, DOC characteristics of a medium-sized valley glacier (Laohugou Glacier No. 12, LHG) on the northern TP were investigated. Generally, DOC concentrations on LHG were comparable to those in other regions around the world. DOC concentrations in snow pits, surface snow and surface ice (superimposed ice) were 332 ± 132, 229 ± 104 and 426 ± 270 µg L-1, respectively. The average discharge-weighted DOC of proglacial stream water was 238 ± 96 µg L-1, and the annual DOC flux released from this glacier was estimated to be 6949 kg C yr-1, of which 46.2 % of DOC was bioavailable and could be decomposed into CO2 within 1 month of its release. The mass absorption cross section (MAC) of DOC at 365 nm was 1.4 ± 0.4 m2 g-1 in snow and 1.3 ± 0.7 m2 g-1 in ice, similar to the values for dust transported from adjacent deserts. Moreover, there was a significant relationship between DOC and Ca2+; therefore, mineral dust transported from adjacent arid regions likely made important contributions to DOC of the glacierized regions, although contributions from autochthonous carbon and autochthonous/heterotrophic microbial activity cannot be ruled out. The radiative forcing of snow pit DOC was calculated to be 0.43 W m-2, demonstrating that DOC in snow needs to be taken into consideration in accelerating melt of glaciers on the TP.

  10. Calculation of near-edge x-ray-absorption fine structure at finite temperatures: spectral signatures of hydrogen bond breaking in liquid water.

    PubMed

    Hetényi, Balázs; De Angelis, Filippo; Giannozzi, Paolo; Car, Roberto

    2004-05-08

    We calculate the near-edge x-ray-absorption fine structure of H(2)O in the gas, hexagonal ice, and liquid phases using heuristic density-functional based methods. We present a detailed comparison of our results with experiment. The differences between the ice and water spectra can be rationalized in terms of the breaking of hydrogen bonds around the absorbing molecule. In particular the increase in the pre-edge absorption feature from ice to water is shown to be due to the breaking of a donor hydrogen bond. We also find that in water approximately 19% of hydrogen bonds are broken.

  11. Detailed Spectral Analysis of the 260 ks XMM-Newton Data of 1E 1207.4-5209 and Significance of a 2.1 keV Absorption Feature

    NASA Astrophysics Data System (ADS)

    Mori, Kaya; Chonko, James C.; Hailey, Charles J.

    2005-10-01

    We have reanalyzed the 260 ks XMM-Newton observation of 1E 1207.4-5209. There are several significant improvements over previous work. First, a much broader range of physically plausible spectral models was used. Second, we have used a more rigorous statistical analysis. The standard F-distribution was not employed, but rather the exact finite statistics F-distribution was determined by Monte Carlo simulations. This approach was motivated by the recent work of Protassov and coworkers and Freeman and coworkers. They demonstrated that the standard F-distribution is not even asymptotically correct when applied to assess the significance of additional absorption features in a spectrum. With our improved analysis we do not find a third and fourth spectral feature in 1E 1207.4-5209 but only the two broad absorption features previously reported. Two additional statistical tests, one line model dependent and the other line model independent, confirmed our modified F-test analysis. For all physically plausible continuum models in which the weak residuals are strong enough to fit, the residuals occur at the instrument Au M edge. As a sanity check we confirmed that the residuals are consistent in strength and position with the instrument Au M residuals observed in 3C 273.

  12. The absorption spectrum of monodeuterated methane /CH3D/ in the 6000-12000 A spectral region. [in atmospheres of outer planets

    NASA Technical Reports Server (NTRS)

    Danehy, R. G.; Lutz, B. L.; Owen, T.; Scattergood, T. W.; Goetz, W.

    1977-01-01

    Preliminary results of a laboratory study of the absorption spectrum of CH3D are presented. Three new parallel-type bands are reported at 8379 A, 9613 A, and 1.065 microns. The application of this work to the search for CH3D in the atmospheres of the outer planets is discussed.

  13. Resonant optical characteristics of an ultracold laser plasma

    SciTech Connect

    Kosarev, N I; Shaparev, N Ya

    2009-12-31

    We report a computer simulation study of light absorption, scattering and emission at 397 nm in an ultracold calcium ion plasma under resonant excitation. The results point to spectral asymmetry of light scattering, nonlinear absorption, and emission in the plasma. An approach is proposed for ultracold plasma diagnostics using resonant optical characteristics. (laser plasma)

  14. Iodine Absorption Cells Purity Testing.

    PubMed

    Hrabina, Jan; Zucco, Massimo; Philippe, Charles; Pham, Tuan Minh; Holá, Miroslava; Acef, Ouali; Lazar, Josef; Číp, Ondřej

    2017-01-06

    This article deals with the evaluation of the chemical purity of iodine-filled absorption cells and the optical frequency references used for the frequency locking of laser standards. We summarize the recent trends and progress in absorption cell technology and we focus on methods for iodine cell purity testing. We compare two independent experimental systems based on the laser-induced fluorescence method, showing an improvement of measurement uncertainty by introducing a compensation system reducing unwanted influences. We show the advantages of this technique, which is relatively simple and does not require extensive hardware equipment. As an alternative to the traditionally used methods we propose an approach of hyperfine transitions' spectral linewidth measurement. The key characteristic of this method is demonstrated on a set of testing iodine cells. The relationship between laser-induced fluorescence and transition linewidth methods will be presented as well as a summary of the advantages and disadvantages of the proposed technique (in comparison with traditional measurement approaches).

  15. Spectral characteristics of total ozone and temperature vertical distribution over the Issyk Kul lake (Northern Tien Shan)

    NASA Astrophysics Data System (ADS)

    Aref'ev, Vladimir N.; Visheratin, Konstantin N.; Kashin, Felix V.; Kamenogradsky, Nikita Y.; Semyonov, Vladimir K.; Sinyakov, Valeriy P.

    2003-04-01

    The results of long-term measurements of total ozone (TO) obtained during 1979-2001 over Tien Shand at the Issyk Kul (IK) station have been analyzed by the Fourier transform and the wavelet method. The results of the spectral analysis for TO were compared with similar results for the ground surface temperatures. It has been found that the variability of the surface temperature behavior correlates with the TO variations. To study the temperature spectral harmonics variations with altitude the NCER/NCAR data on temperature vertical distributions were used. It was found that within the range of 850-10 mb the temperature spectra behaved differently mainly at the heights less than those of the surrounding mountains, below the polar tropopause and between the polar and tropical topopauses. The peculiarities of TO harmonics for the periods from 15 to 45 months are in higher correlation with the temperature spectral harmonics up to levels of 100-50 mbar.

  16. Spectral characteristics of iron-bearing phyllosilicates: Comparison to Orgueil (CI1), Murchison and Murray (CM2)

    USGS Publications Warehouse

    Calvin, W.M.; King, T.V.V.

    1997-01-01

    Phyllosilicate alteration minerals are commonly found in low petrologic types of carbonaceous chondrites. Previous spectral studies have examined Mg-bearing phyllosilicates with limited success in matching the spectral properties of CM and CI chondrites. Transmission electron microscope and other analytical techniques suggest that Fe-bearing clays are more abundant in CI and CM chondrites than magnesian varieties. Here, we present the results of an examination of the reflectance spectra of Fe-phyllosilicates, including serpentines and berthierines, of which the latter were formerly known as septechlorites. We have measured the diffuse reflectance spectra of powdered samples from 0.3 to 25 ??m. We find that these minerals provide a better spectral match to many of the features seen in CI and CM chondrites, and simple linear combinations of the spectra of both Fe- and Mg-phyllosilicates closely approximate the spectra of CM and CI chondrites.

  17. HITRAN/HITEMP Spectral Databases and Uncertainty Propagation by Means of Monte Carlo Simulation with Application to Tunable Diode Laser Absorption Diagnostics

    DTIC Science & Technology

    2011-02-01

    on the commercial market. These lasers are now routinely used for many gas diagnostics measurements. The availability of low light loss fiber ...this case the laser scan rate has to be much less than the chop rate, which is typically limited to approximately 20 kHz or lower. This requires the...multiple spectral lines, elevated temperatures, and low pressures. Here the target specie is carbon monoxide in the mid-infrared region. This type

  18. Polarization and field dependent two-photon absorption in GaAs/AlGaAs multiquantum well waveguides in the half-band gap spectral region

    NASA Astrophysics Data System (ADS)

    Tsang, H. K.; Penty, R. V.; White, I. H.; Grant, R. S.; Sibbett, W.; Soole, J. B. D.; LeBlanc, H. P.; Andreadakis, N. C.; Colas, E.; Kim, M. S.

    1991-12-01

    We report the observation of two photon absorption which is strongly dependent on the applied electric field and the optical polarization. At 1.55 μm wavelength, the two-photon absorption coefficient of the GaAs/AlGaAs multiquantum well (MQW) waveguides for transverse-magnetic light is about seven times lower than for transverse-electric polarized light and changes by a factor of approximately 4 for a change in applied direct-current electric field of ˜140 kV/cm. Ultrafast nonlinear refraction causing phase changes of over π radians without appreciable excess loss is observed. These measurements demonstrate that GaAs/AlGaAs MQW waveguides could be successfully used for subpicosecond all-optical switching near half-band gap, at wavelengths corresponding to the 1.55 μm optical communications band.

  19. [Characteristics of the absorption spectra of the mixtures of C42(Al), C32 (Si) and so on].

    PubMed

    Chen, W

    1998-12-01

    The mixtures containing C42 (A1), C32 (Si), C30 (Ca) and C28 (Fe) are produced by means of arc discharge and He gas convection. The spectra are measured and compared with the absorption spectra of all carbon molecules. The result shows that after imbeded in all carbon molecules, the Al, Si, Ca and Fe atoms do not change the positions of the absorption peak of original molecules, but only change the probability of pi --> pi* transition and n --> pi* transition of these molecules.

  20. The Zugspitze radiative closure experiment for quantifying water vapor absorption over the terrestrial and solar infrared - Part 3: Quantification of the mid- and near-infrared water vapor continuum in the 2500 to 7800 cm-1 spectral range under atmospheric conditions

    NASA Astrophysics Data System (ADS)

    Reichert, Andreas; Sussmann, Ralf

    2016-09-01

    We present a first quantification of the near-infrared (NIR) water vapor continuum absorption from an atmospheric radiative closure experiment carried out at the Zugspitze (47.42° N, 10.98° E; 2964 m a.s.l.). Continuum quantification is achieved via radiative closure using radiometrically calibrated solar Fourier transform infrared (FTIR) absorption spectra covering the 2500 to 7800 cm-1 spectral range. The dry atmospheric conditions at the Zugspitze site (IWV 1.4 to 3.3 mm) enable continuum quantification even within water vapor absorption bands, while upper limits for continuum absorption can be provided in the centers of window regions. Throughout 75 % of the 2500 to 7800 cm-1 spectral range, the Zugspitze results agree within our estimated uncertainty with the widely used MT_CKD 2.5.2 model (Mlawer et al., 2012). In the wings of water vapor absorption bands, our measurements indicate about 2-5 times stronger continuum absorption than MT_CKD, namely in the 2800 to 3000 cm-1 and 4100 to 4200 cm-1 spectral ranges. The measurements are consistent with the laboratory measurements of Mondelain et al. (2015), which rely on cavity ring-down spectroscopy (CDRS), and the calorimetric-interferometric measurements of Bicknell et al. (2006). Compared to the recent FTIR laboratory studies of Ptashnik et al. (2012, 2013), our measurements are consistent within the estimated errors throughout most of the spectral range. However, in the wings of water vapor absorption bands our measurements indicate typically 2-3 times weaker continuum absorption under atmospheric conditions, namely in the 3200 to 3400, 4050 to 4200, and 6950 to 7050 cm-1 spectral regions.

  1. Effects of interdigitated platinum finger geometry on spectral response characteristics of germanium metal-semiconductor-metal photodetectors.

    PubMed

    Yang, Hyun-Duk; Janardhanam, V; Shim, Kyu-Hwan; Choi, Chel-Jong

    2014-10-01

    We fabricated interdigitated germanium (Ge) metal-semiconductor-metal photodetectors (MSM PDs) with interdigitated platinum (Pt) finger electrodes and investigated the effects of Pt finger width and spacing on their spectral response. An increase in the incident optical power enhances the creation of electron-hole pairs, resulting in a significant increase in photo current. Lowering of the Schottky barrier could be a main cause of the increase in both photo and dark current with increasing applied bias. The manufactured Ge MSM PDs exhibited a considerable spectral response for wavelengths in the range of 1.53-1.56 μm, corresponding to the entire C-band spectrum range. A reduction in the area fraction of the Pt finger electrode in the active region by decreasing and increasing finger width and spacing, respectively, led to an increase in illuminated active area and suppression of dark current, which was responsible for the improvement in responsivity and quantum efficiency of Ge MSM PDs.

  2. [Monitoring spatio-temporal spectral characteristics of leaves of karst plant during dehydration using a field imaging spectrometer system].

    PubMed

    Liu, Bo; Tong, Qing-Xi; Zhang, Li-Fu; Zhang, Xia; Yue, Yue-Min; Zhang, Bing

    2012-06-01

    As the supplement of spaceborne and airborne imaging spectrometer system, field Imaging spectrometer system spans a very broad range of applications. Imaging spectrometer system of this new kind could provide vital information especially for which spaceborne or airborne remote sensing could not be competent, such as proximal detection of plant population, individual plant or plant organs for site-specific management in precision agriculture. A new self-developed imaging spectrometer system was utilized to monitor spatio-temporal dynamics of spectral changes of plant leaves in response to dehydration. lThe phenomenon of blue shift of red edge of plant leaves was successfully detected and visualized in the form of image series. The patterns of photochemical reflectance index (PRI) of leaves during dehydration were compared and confirmed by fluorescence parameter quantum yield. Our results show that FISS has good spectral and radiometric properties and could be used in quantitative researches and precise information mapping.

  3. Change Analysis of the Spectral Characteristics of Rubber Trees at Canopy and Leaf Scales during the Brazilian Autumn

    NASA Astrophysics Data System (ADS)

    Amaral, C. H.; Almeida, T. I. R.; Quitério, G. C. M.; Alves, M. N.; Souza Filho, C. R.

    2012-07-01

    The objective of this work is to investigate the hyperspectral remote sensing potential to detect spectral changes undergone by clones of two rubber trees within Brazilian Autumn, with decrease of rain, temperature and photoperiod between May and June. Indirectly, we also analyze the ability of the data to help discriminating the clones at two dates in autumn. The average canopy spectra of the stands were obtained with two overpasses of the ProSpecTIR-VS airborne hyperspectral sensor (357 bands between 400-2,500 nm; spatial resolution of 1m) by 14th May and 17th June, in 2010 year. Additionally measurements of leaf spectra were taken in the same dates, but in the 2011 year. Considering the analysis of the spectra measured from the three stands, this indicates that spectral differences in the VIS (400-700 nm) region are of genetic origin and occur regardless of environmental conditions and period of data collection. In the NIR (700-1,300 nm) range, the environmental factors predominate in the two periods of data collection. The SWIR (1,300-2,500 nm) displayed the largest differences between the months of data collection. In May, the relationship between stands indicated the prevalence of environmental aspects. However, in June, the stands and clones spectral behaviour indicates that as the temperature, the rainfall and the photoperiod are lower closer to winter, the SWIR can be effectively used to discriminate and map these clones separately.

  4. Temporal measurement and analysis of high-resolution spectral signatures of plants and relationships to biophysical characteristics

    NASA Astrophysics Data System (ADS)

    Bostater, Charles R., Jr.; Rebbman, Jan; Hall, Carlton; Provancha, Mark; Vieglais, David

    1995-11-01

    Measurements of temporal reflectance signatures as a function of growing season for sand live oak (Quercus geminata), myrtle oak (Q. myrtifolia, and saw palmetto (Serenoa repens) were collected during a two year study period. Canopy level spectral reflectance signatures, as a function of 252 channels between 368 and 1115 nm, were collected using near nadir viewing geometry and a consistent sun illumination angle. Leaf level reflectance measurements were made in the laboratory using a halogen light source and an environmental optics chamber with a barium sulfate reflectance coating. Spectral measurements were related to several biophysical measurements utilizing optimal passive ambient correlation spectroscopy (OPACS) technique. Biophysical parameters included percent moisture, water potential (MPa), total chlorophyll, and total Kjeldahl nitrogen. Quantitative data processing techniques were used to determine optimal bands based on the utilization of a second order derivative or inflection estimator. An optical cleanup procedure was then employed that computes the double inflection ratio (DIR) spectra for all possible three band combinations normalized to the previously computed optimal bands. These results demonstrate a unique approach to the analysis of high spectral resolution reflectance signatures for estimation of several biophysical measures of plants at the leaf and canopy level from optimally selected bands or bandwidths.

  5. Spectral representation: a core aspect of modelling the response characteristics of time-domain EMI mine detectors

    NASA Astrophysics Data System (ADS)

    West, G. F.; Bailey, R. C.

    2006-05-01

    Most modern EMI mine detectors can detect the very small conductive and/or ferromagnetic parts of typical mines with relative ease. However, they also respond significantly to certain soils that contain lossy ferromagnetic minerals. In some special environments such as ocean beaches, conductivity of the host soil may also cause a response. Characterizing and modelling both the various target response mechanisms and the EMI detectors quantitatively would be relatively straightforward if it were not for the fact that most modern EMI detectors operate in time domain and use different current waveforms and time gates to observe response. Furthermore, much of the information about targets and interferences and even instrumental spectral limitations is observational rather than analytical data. In this paper, we put forward a spectral representation method that can be incorporated into both EMI data gathering and instrument modelling and which facilitates efficient quantitative simulation of arbitrary time- domain detection systems. The methodology and examples of its use are presented. Pure induction response from the ground is modelled with a sum-over-N-elements transfer function in which the kernel elements are single pole, pure damping responses which are log-spaced over the spectral range of interest. Instrument transfer functions can be described with a standard sparse pole and zero representation (located anywhere in the damped frequency half plane), if required. Model fitting techniques employing generalized inversion controls are used to go back and forth between frequency and time domain and the set of model parameters.

  6. Spectral and luminescent characteristics of trivalent lanthanide ions in a POCl3-SnCl4 inorganic solvent

    NASA Astrophysics Data System (ADS)

    Seregina, E. A.; Seregin, A. A.; Tikhonov, G. V.

    2014-03-01

    We have measured the absorption and luminescence spectra of trivalent lanthanide ions (Pr3+, Sm3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, and Yb3+) in the visible and near-IR wavelength ranges in a POCl3-SnCl4 inorganic solvent. In terms of the Judd-Ofelt model, the oscillator strengths of absorption bands, the probabilities of radiative transitions, the luminescence branching coefficients, the lifetimes of excited states, and the luminescence quantum yields have been calculated. Possibilities of creating new laser media have been evaluated. A conclusion is drawn regarding the symmetry of the environment of trivalent lanthanide ions in the POCl3-SnCl4 solvent.

  7. Diagnostics of Carbon Nanotube Formation in a Laser Produced Plume: Spectroscopic in situ nanotube detection using spectral absorption and surface temperature measurements by black body emission

    NASA Technical Reports Server (NTRS)

    DeBoer, Gary D.

    2005-01-01

    Carbon nanotubes hold great promise for material advancements in the areas of composites and electronics. The advancement of research in these areas is dependent upon the availability of carbon nanotubes to a broad spectrum of academic and industrial researchers. Although there has been much progress made in reducing the costs of carbon nanotubes and increasing the quality and purity of the products, an increase in demand for still less expensive and specific nanotubes types has also grown. This summer's work has involved two experiments that have been designed to further the understanding of the dynamics and chemical mechanisms of carbon nanotube formation. It is expected that a better understanding of the process of formation of nanotubes will aid current production designs and stimulate ideas for future production designs increasing the quantity, quality, and production control of carbon nanotubes. The first experiment involved the measurement of surface temperature of the target as a function of time with respect to the ablation lasers. A peak surface temperature of 5000 K was determined from spectral analysis of black body emission from the target surface. The surface temperature as a function of various changes in operating parameters was also obtained. This data is expected to aid the modeling of ablation and plume dynamics. The second experiment involved a time and spatial measurement of the spectrally resolved absorbance of the laser produced plume. This experiment explored the possibility of developing absorbance and fluorescence to detect carbon nanotubes during production. To attain control over the production of nanotubes with specific properties and reduce costs, a real time in situ diagnostics method would be very beneficial. Results from this summer's work indicate that detection of nanotubes during production may possibly be used for production feed back control.

  8. Multi-decade Measurements of the Long-Term Trends of Atmospheric Species by High-Spectral-Resolution Infrared Solar Absorption Spectroscopy

    NASA Technical Reports Server (NTRS)

    Rinsland, Curtis P.; Chiou, Linda; Goldman, Aaron; Hannigan, James W.

    2010-01-01

    Solar absorption spectra were recorded for the first time in 5 years with the McMath Fourier transform spectrometer at the US National solar Observatory on Kitt Peak in southern Arizona, USA (31.91 N latitude, 111.61 W longitude, 2.09 km altitude). The solar absorption spectra cover 750-1300 and 1850-5000 cm(sup -1) and were recorded on 20 days during March-June 2009. The measurements mark the continuation of a long-term record of atmospheric chemical composition measurements that have been used to quantify seasonal cycles and long-term trends of both tropospheric and stratospheric species from observations that began i 1977. Fits to the measured spectra have been performed, and they indicate the spectra obtained since return to operational status are nearly free of channeling and the instrument line shape function is well reproduced taking into account the measurement parameters. We report updated time series measurements of total columns for six atmospheric species and their analysis for seasonal cycles and long-term trends. An sn example, the time series fit shows a decrease in the annual increase rate i Montreal-Protocol-regulated chlorofluorocarbon CCL2F2 from 1.51 plus or minus 0.38% yr(sup -1) at the beginning of the time span to -1.54 plus or minus 1.28 yr(sup -1) at the end of the time span, 1 sigma, and hence provides evidence for the impact of those regulations on the trend.

  9. Resolving the Large Scale Spectral Variability of the Luminous Seyfert 1 Galaxy 1H 0419-577: Evidence for a New Emission Component and Absorption by Cold Dense Matter

    NASA Technical Reports Server (NTRS)

    Pounds, K. A.; Reeves, J. N.; Page, K. L.; OBrien, P. T.

    2004-01-01

    An XMM-Newton observation of the luminous Seyfert 1 galaxy 1H 0419-577 in September 2002, when the source was in an extreme low-flux state, found a very hard X-ray spectrum at 1-10 keV with a strong soft excess below -1 keV. Comparison with an earlier XMM-Newton observation when 1H 0419-577 was X-ray bright indicated the dominant spectral variability was due to a steep power law or cool Comptonised thermal emission. Four further XMM-Newton observations, with 1H 0419-577 in intermediate flux states, now support that conclusion, while we also find the variable emission component in intermediate state difference spectra to be strongly modified by absorption in low ionisation matter. The variable soft excess then appears to be an artefact of absorption of the underlying continuum while the core soft emission can be attributed to re- combination in an extended region of more highly ionised gas. We note the wider implications of finding substantial cold dense matter overlying (or embedded in) the X-ray continuum source in a luminous Seyfert 1 galaxy.

  10. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Spectral characteristics of fragmentation of kidney stones by microsecond laser radiation

    NASA Astrophysics Data System (ADS)

    Batishche, S. A.; Tarkovsky, V. V.

    1995-07-01

    A study of the action of single microsecond laser pulses on kidney stones revealed a strong spectral dependence of the efficiency K of mass removal. This should be taken into account in the development of apparatus for laser lithotripsy. An increase in the energy of the laser pulses acting on a stone resulted in saturation of K when a certain energy, specific to each wavelength, was exceeded. The radiation energy should be less than the saturation threshold in order to reduce the effects on the surrounding tissues.

  11. Soliton absorption spectroscopy

    PubMed Central

    Kalashnikov, V. L.; Sorokin, E.

    2010-01-01

    We analyze optical soliton propagation in the presence of weak absorption lines with much narrower linewidths as compared to the soliton spectrum width using the novel perturbation analysis technique based on an integral representation in the spectral domain. The stable soliton acquires spectral modulation that follows the associated index of refraction of the absorber. The model can be applied to ordinary soliton propagation and to an absorber inside a passively modelocked laser. In the latter case, a comparison with water vapor absorption in a femtosecond Cr:ZnSe laser yields a very good agreement with experiment. Compared to the conventional absorption measurement in a cell of the same length, the signal is increased by an order of magnitude. The obtained analytical expressions allow further improving of the sensitivity and spectroscopic accuracy making the soliton absorption spectroscopy a promising novel measurement technique. PMID:21151755

  12. Spectral characteristics of the Hellenic vertical network - Validation over Central and Northern Greece using GOCE/GRACE global geopotential models

    NASA Astrophysics Data System (ADS)

    Andritsanos, Vassilios D.; Vergos, George S.; Grigoriadis, Vassilios N.; Pagounis, Vassilios; Tziavos, Ilias N.

    2014-05-01

    The Elevation project, funded by the action "Archimedes III - Funding of research groups in T.E.I.", co-financed by the E.U. (European Social Fund) and national funds under the Operational Program "Education and Lifelong Learning 2007-2013" aims mainly to the validation of the Hellenic vertical datum. This validation is carried out over two areas under study, one in Central and another in Northern Greece. During the first stage of the validation process, satellite-only as well as combined satellite-terrestrial models of the Earth's geopotential are used. GOCE and GRACE satellite information is compared against recently measured GPS/Levelling observations at specific benchmarks of the vertical network in Attiki (Central Greece) and Thessaloniki (Northern Greece). A spectral enhancement approach is followed where, given the GOCE/GRACE GGM truncation degree, EGM2008 is used to fill-in the medium and high-frequency content along with RTM effects for the high and ultra high part. The second stage is based on the localization of possible blunders of the vertical network using the spectral information derived previously. The undoubted accuracy of the contemporary global models at the low frequency band leads to some initial conclusions about the consistency of the Hellenic vertical datum.

  13. RIS4E at Kilauea's December 1974 Flow: Chemical, mineralogical and spectral characteristics of Hawaiian basaltic alteration products measured with portable instruments

    NASA Astrophysics Data System (ADS)

    Young, K. E.; Rogers, D.; Dyar, M. D.; Ito, G.; Yant, M.; McAdam, A.; Bleacher, J. E.; Glotch, T. D.

    2015-12-01

    A major objective of the SSERVI RIS4E (Remote, In-situ, and Synchrotron Studies for Science and Exploration) investigation is to evaluate the performance of portable chemical and mineralogical instruments in a variety of planetary volcanic analog settings. To that end, we used a suite of true/proxy portable instruments (XRF, LIBS, XRD, near-IR and mid-IR spectrometers), to measure the chemical and spectral characteristics of young basaltic flows (erupted December 1974, or D1974) within the southwest rift zone of Kilauea, Hawaii. The D1974 lavas exhibit multiple flow morphologies and textures, and have undergone alteration by a variety of processes, including acid weathering, oxidation and devitrification. The mineralogy, chemistry and infrared spectral properties of select samples from these altered surfaces have been well characterized by previous groups using high resolution (e.g. SEM, TEM) and/or laboratory measurements (XRD, Mossbauer, infrared). Typical alteration products include coatings of Fe-Ti-oxide +/- an overlying silica-rich coating. Coatings are commonly discontinuous and vary in color. Oxidation fronts are also present, most visible as reddish brown discoloration along the edges of broken and uplifted flow crusts. The previous detailed characterizations provide the basis for evaluating instrument performance and also allow us to assess areas where portable instruments can contribute new information to current understanding. These areas include characterizing the spatial variability in alteration chemistry/mineralogy, relating chemical/mineralogical properties to texture and context, and comparing chemical/mineralogical variations with infrared spectral properties. Because infrared spectra are commonly used to assess compositional variations of a site remotely, either from the ground or from orbit, relating changes in chemistry and mineralogy to spectral variations is particularly important. Last, the D1974 site provides an excellent location to test

  14. Object-Based Land Use Classification of Agricultural Land by Coupling Multi-Temporal Spectral Characteristics and Phenological Events in Germany

    NASA Astrophysics Data System (ADS)

    Knoefel, Patrick; Loew, Fabian; Conrad, Christopher

    2015-04-01

    Crop maps based on classification of remotely sensed data are of increased attendance in agricultural management. This induces a more detailed knowledge about the reliability of such spatial information. However, classification of agricultural land use is often limited by high spectral similarities of the studied crop types. More, spatially and temporally varying agro-ecological conditions can introduce confusion in crop mapping. Classification errors in crop maps in turn may have influence on model outputs, like agricultural production monitoring. One major goal of the PhenoS project ("Phenological structuring to determine optimal acquisition dates for Sentinel-2 data for field crop classification"), is the detection of optimal phenological time windows for land cover classification purposes. Since many crop species are spectrally highly similar, accurate classification requires the right selection of satellite images for a certain classification task. In the course of one growing season, phenological phases exist where crops are separable with higher accuracies. For this purpose, coupling of multi-temporal spectral characteristics and phenological events is promising. The focus of this study is set on the separation of spectrally similar cereal crops like winter wheat, barley, and rye of two test sites in Germany called "Harz/Central German Lowland" and "Demmin". However, this study uses object based random forest (RF) classification to investigate the impact of image acquisition frequency and timing on crop classification uncertainty by permuting all possible combinations of available RapidEye time series recorded on the test sites between 2010 and 2014. The permutations were applied to different segmentation parameters. Then, classification uncertainty was assessed and analysed, based on the probabilistic soft-output from the RF algorithm at the per-field basis. From this soft output, entropy was calculated as a spatial measure of classification uncertainty

  15. Determination of Kamlet-Taft solvent parameters pi* of high pressure and supercritical water by the UV-Vis absorption spectral shift of 4-nitroanisole.

    PubMed

    Minami, Kimitaka; Mizuta, Masamichi; Suzuki, Muneyuki; Aizawa, Takafumi; Arai, Kunio

    2006-05-21

    Kamlet-Taft solvent parameters, pi*, of high pressure and supercritical water were determined from 16-420 degrees C based on solvatochromic measurements of 4-nitroanisole. For the measurements, an optical cell that could be used at high temperatures and pressures was developed with the specification of minimal dead space. The low dead space cell allowed us to measure the absorption spectra of 4-nitroanisole at high temperature conditions before appreciable decomposition occurred. The behavior of pi* in terms of water density (pi* = 1.77rho- 0.71) was found to be linear, except in the near critical region, in which deviations were observed that could be attributed to local density augmentation. Excess density, which was defined as the difference between local density and bulk density, showed a maximum near the critical density of water. The frequencies of UV-Vis spectra of 4-(dimethylamino)benzonitrile and N,N-dimethyl-4-nitroaniline were correlated with pi* based on a linear solvation energy relationship (LSER) theory. Local density augmentation around 4-nitroanisole and that around 4-(dimethylamino)benzonitrile were similar but the augmentation observed around N,N-dimethyl-4-nitroaniline was larger.

  16. Development of a serum-free human cornea construct for in vitro drug absorption studies: the influence of varying cultivation parameters on barrier characteristics.

    PubMed

    Hahne, Matthias; Reichl, Stephan

    2011-09-15

    The increased use of ophthalmic products in recent years has led to an increased demand for in vitro and in vivo transcorneal drug absorption studies. Cell-culture models of the human cornea can avoid several of the disadvantages of widely used animal experimental models, including ethical concerns and poor standardisation. This study describes the development of a serum-free cultivated, three-dimensional human cornea model (Hemicornea, HC) for drug absorption experiments. The impact of varying cultivation conditions on the corneal barrier function was analysed and compared with excised rabbit and porcine corneas. The HC was cultivated on permeable polycarbonate filters using immortalised human keratocytes and a corneal epithelial cell line. The equivalence to native tissue was investigated through absorption studies using model substances with a wide range of molecular characteristics, including hydrophilic sodium fluorescein, lipophilic rhodamine B and fluorescein isothiocyanate (FITC)-labelled macromolecule dextran. To study the intra-laboratory repeatability and construct cultivation, the permeation studies were performed independently by different researchers. The HC exhibited a permeation barrier in the same range as excised animal corneas, high reproducibility and a lower standard deviation. Therefore, the HC could be a promising in vitro alternative to ex vivo corneal tissues in preclinical permeation studies.

  17. Internal Characteristics of Phobos and Deimos from Spectral Properties and Density: Relationship to Landforms and Comparison with Asteroids

    NASA Technical Reports Server (NTRS)

    Murchie, S. L.; Fraeman, A. A.; Arvidson, R. E.; Rivkin, A. S.; Morris, R. V.

    2013-01-01

    Compositional interpretations of new spectral measurements of Phobos and Deimos from Mars Express/OMEGA and MRO/CRISM and density measurements from encounters by multiple spacecraft support refined estimates of the moons' porosity and internal structure. Phobos' estimated macroporosity of 12-20% is consistent with a fractured but coherent interior; Deimos' estimated macroporosity of 23-44% is more consistent with a loosely consolidated interior. These internal differences are reflected in differences in surface morphology: Phobos exhibits a globally coherent pattern of grooves, whereas Deimos has a surface dominated instead by fragmental debris. Comparison with other asteroids .110 km in diameter shows that this correspondence between landforms and inferred internal structure is part of a pervasive pattern: asteroids interpreted to have coherent interiors exhibit pervasive, organized ridge or groove systems, whereas loosely consolidated asteroids have landforms dominated by fragmental debris and/or retain craters >1.3 body radii in diameter suggesting a porous, compressible interior.

  18. Coexistence of 1-dimensional and 3-dimensional spectral characteristics in TaTe4 and NbTe4

    NASA Astrophysics Data System (ADS)

    Zwick, F.; Berger, H.; Forro, L.; Margaritondo, G.; Grioni, M.; Laveigne, J.; Tanner, D.; Onellion, M.

    2000-03-01

    We have measured TaTe4 and NbTe4 using resistivity, optical conductivity, and angle-resolved photoemission.[1,2] Consistent with earlier reports, the resistivity and optical conductivity in different directions in the crystal exhibit a small ( ~ 10%) anisotropy. The optical conductivity exhibits a Drude peak and conductivity that scales as (1/w)2 for low photon energies (hw), again consistent with earlier results and as expected for a three-dimensional metal. The residual resistivity is below 5 mW-cm, indicating that disorder does not play a major role in these samples. However, the angle-resolved photoemission data indicate a coexistence of three-dimensional and one-dimensional properties. The three-dimensional properties include (a) quasiparticle states in all major symmetry directions of the Brillouin zone, both parallel to and perpendicular to the Ta (Nb) chains, and (b) an energy resolution-limited Fermi-Dirac cutoff of the spectral function. The quasi-one-dimensional properties include (a) dispersing coherent states only for wavevectors along the cation chains, and (b) no coherent state dispersing through or within 0.2 eV of the chemical potential. Further, we measure the resolution-limited Fermi-Dirac cutoff of the spectral function at every point of the Brillouin zone for which we took data, including all three high symmetry directions. (*) Present address: ABB Corp., Zürich, Switzerland 1. F. Zwick et.al., Phys. Rev. B 59 , 7762 (1999). 2. F. Zwick, Ph.D. thesis, EPFL, September, 1998.

  19. Remote Sensing of Aerosol and Non-Aerosol Absorption

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Dubovik, O.; Holben, B. N.; Remer, L. A.; Tanre, D.; Lau, William K. M. (Technical Monitor)

    2001-01-01

    Remote sensing of aerosol from the new satellite instruments (e.g. MODIS from Terra) and ground based radiometers (e.g. the AERONET) provides the opportunity to measure the absorption characteristics of the ambient undisturbed aerosol in the entire atmospheric column. For example Landsat and AERONET data are used to measure spectral absorption of sunlight by dust from West Africa. Both Application of the Landsat and AERONET data demonstrate that Saharan dust absorption of solar radiation is several times smaller than the current international standards. This is due to difficulties of measuring dust absorption in situ, and due to the often contamination of dust properties by the presence of air pollution or smoke. We use the remotely sensed aerosol absorption properties described by the spectral sin le scattering albedo, together with statistics of the monthly optical thickness for the fine and coarse aerosol derived from the MODIS data. The result is an estimate of the flux of solar radiation absorbed by the aerosol layer in different regions around the globe where aerosol is prevalent. If this aerosol forcing through absorption is not included in global circulation models, it may be interpreted as anomalous absorption in these regions. In a preliminary exercise we also use the absorption measurements by AERONET, to derive the non-aerosol absorption of the atmosphere in cloud free conditions. The results are obtained for the atmospheric windows: 0.44 microns, 0.66 microns, 0.86 microns and 1.05 microns. In all the locations over the land and ocean that were tested no anomalous absorption in these wavelengths, was found within absorption optical thickness of +/- 0.005.

  20. Characteristics of surface sound pressure and absorption of a finite impedance strip for a grazing incident plane wave.

    PubMed

    Sum, K S; Pan, J

    2007-07-01

    Distributions of sound pressure and intensity on the surface of a flat impedance strip flush-mounted on a rigid baffle are studied for a grazing incident plane wave. The distributions are obtained by superimposing the unperturbed wave (the specularly reflected wave as if the strip is rigid plus the incident wave) with the radiated wave from the surface vibration of the strip excited by the unperturbed pressure. The radiated pressure interferes with the unperturbed pressure and distorts the propagating plane wave. When the plane wave propagates in the baffle-strip-baffle direction, it encounters discontinuities in acoustical impedance at the baffle-strip and strip-baffle interfaces. The radiated pressure is highest around the baffle-strip interface, but decreases toward the strip-baffle interface where the plane wave distortion reduces accordingly. As the unperturbed and radiated waves have different magnitudes and superimpose out of phase, the surface pressure and intensity increase across the strip in the plane wave propagation direction. Therefore, the surface absorption of the strip is nonzero and nonuniform. This paper provides an understanding of the surface pressure and intensity behaviors of a finite impedance strip for a grazing incident plane wave, and of how the distributed intensity determines the sound absorption coefficient of the strip.

  1. An ATR-FTIR Study on the Effect of Molecular Structural Variations on the CO2 Absorption Characteristics of Heterocyclic Amines, Part II

    PubMed Central

    Robinson, Kelly; McCluskey, Adam; Attalla, Moetaz I

    2012-01-01

    This paper reports on an ATR-FTIR spectroscopic investigation of the CO2 absorption characteristics of a series of heterocyclic diamines: hexahydropyrimidine (HHPY), 2-methyl and 2,2-dimethylhexahydropyrimidine (MHHPY and DMHHPY), hexahydropyridazine (HHPZ), piperazine (PZ) and 2,5- and 2,6-dimethylpiperazine (2,6-DMPZ and 2,5-DMPZ). By using in situ ATR-FTIR the structure–activity relationship of the reaction between heterocyclic diamines and CO2 is probed. PZ forms a hydrolysis-resistant carbamate derivative, while HHPY forms a more labile carbamate species with increased susceptibility to hydrolysis, particularly at higher CO2 loadings (>0.5 mol CO2/mol amine). HHPY exhibits similar reactivity toward CO2 to PZ, but with improved aqueous solubility. The α-methyl-substituted MHHPY favours HCO3− formation, but MHHPY exhibits comparable CO2 absorption capacity to conventional amines MEA and DEA. MHHPY show improved reactivity compared to the conventional α-methyl- substituted primary amine 2-amino-2-methyl-1-propanol. DMHHPY is representative of blended amine systems, and its reactivity highlights the advantages of such systems. HHPZ is relatively unreactive towards CO2. The CO2 absorption capacity CA (mol CO2/mol amine) and initial rates of absorption RIA (mol CO2/mol amine min−1) for each reactive diamine are determined: PZ: CA=0.92, RIA=0.045; 2,6-DMPZ: CA=0.86, RIA=0.025; 2,5-DMPZ: CA=0.88, RIA=0.018; HHPY: CA=0.85, RIA=0.032; MHHPY: CA=0.86, RIA=0.018; DMHHPY: CA=1.1, RIA=0.032; and HHPZ: no reaction. Calculations at the B3LYP/6-31+G** and MP2/6-31+G** calculations show that the substitution patterns of the heterocyclic diamines affect carbamate stability, which influences hydrolysis rates. PMID:22517608

  2. Temporal and spectral characteristics of aerosol optical depths in a semi-arid region of southern India.

    PubMed

    Kumar, K Raghavendra; Narasimhulu, K; Reddy, R R; Gopal, K Rama; Reddy, L Siva Sankara; Balakrishnaiah, G; Moorthy, K Krishna; Babu, S Suresh

    2009-04-01

    The spectral and temporal variations of aerosol optical depths (AOD) observed over Anantapur (a semi-arid region) located in the Southern part of India are investigated by analyzing the data obtained from a Multiwavelength Solar Radiometer (MWR) during January 2005-December 2006 (a total of 404 clear-sky observations) using the Langley technique. In this paper, we highlighted the studies on monthly, seasonal and spectral variations of aerosol optical depth and their implications. The results showed seasonal variation with higher values during pre-monsoon (March-May) and lower in the monsoon (June-November) season at all wavelengths. The pre-monsoon increase is found to be due to the high wind speed producing larger amounts of wind-driven dust particles. The post-monsoon (December-February) AOD values decrease more at higher wavelengths, indicating a general reduction in the number of bigger particles. Also during the post-monsoon, direction of winds in association with high or low pressure weather systems and the air brings more aerosol content to the region which is surrounded by a number of cement plants, lime kilns, slab polishing and brick making units. The quantity of AOD values in pre-monsoon is higher (low during post-monsoon) for wavelength, such as shortwave infrared (SWIR) or near infrared (NIR), which shows that coarse particles contribute more compare with the sub-micron particles. The composite aerosols near the surface follow suit with the share of the accumulation mode to the total mass concentration decreasing from approximately 70% to 30% from post-monsoon to pre-monsoon. Coarse mode particle loading observed to be high during pre-monsoon and accumulation mode particles observed to be high during post-monsoon. The backward trajectories at three representative altitudes with source point at the observing site indicate a possible transport from the outflow regions into Bay of Bengal, southern peninsular India and Arabian Sea. The temporal variations

  3. Evolution of macromolecular dust: Far-ultraviolet spectral dust extinction and gas absorption of stellar light as measured with the Hopkins Ultraviolet Telescope

    NASA Technical Reports Server (NTRS)

    Buss, Richard H., Jr.; Allen, Marsha; Mccandliss, Stephan; Kruk, Jeffrey; Liu, Ji-Cheng; Brown, Tom

    1994-01-01

    From far-ultraviolet (FUV) spectra of B stars taken with the Hopkins Ultraviolet Telescope (HUT) and Voyager space observations, we determine the far-ultraviolet extinction by Galactic dust and hydrogen absorption in the local spiral-arm clouds towards HD 25443 (B0.5 III), HD 37903 (B1.5 V), and HD 200775 (B3 Ve). We find that the (n (H)) = 1.3 cu cm and number fraction (f = 0.31) of H atoms in molecular hydrogen relative to the total hydrogen indicates a mostly diffuse medium toward HD 25443. We also determine f = 0.56 for the gas in the photodissociation region (PDR) in front of HD 37903 and f approximately equals 0.36 for the HD 200775 PDR. The inferred ratios of N(H2)/I(CO) = 2.4 to 2.8 x 10(exp 20)/K(km/s)/sq cm for cool gas in dark clouds agree with previous canonical estimates of N(H2)/I(CO) = 2 to 3 x 10(exp 20)/K(km/s)/sq cm and support the use of the ratio for determining masses of molecular clouds. We find that the shape and strength of the HD 25443 FUV extinction is the same as a diffuse-medium mean extinction (R(sub nu) = 2.95) extrapolated from mid-UV wavelengths (normal). The HD 37903 FUV extinction through a bright H2 photodissociation region is higher than a mean FUV extinction(R(sub nu) = 4.11), as is the HD 200775 extinction. Another star from the literature rho Oph, probes the dense medium and exhibits an FUV extinction of normal mean strength (R(sub nu) = 4.55) but steeper shape. The normal FUV -extinction of HD 25443 implies that the small FUV-extinction dust in the diffuse medium forms in p art from larger grains as the grains shatter under shocks. The normal strength of the rho Oph FUV-extinction indicates that the minute dust condenses onto or coagulates into larger grains in the dense medium. The high extinction deviation of the HD 37903 PDR (and HD 200775 PDR) shows that FUV radiation from hot stars with T(sub eff) approximately equals 20,000 to 23,000 K in PDRs can evaporate some of the FUV-extinction dust from grain surfaces. In

  4. HTR2 Receptors in a Songbird Premotor Cortical-Like Area Modulate Spectral Characteristics of Zebra Finch Song

    PubMed Central

    Wood, William E.; Roseberry, Thomas K.; Perkel, David J.

    2013-01-01

    Serotonin [5-hydroxytryptamine (5-HT)] is involved in modulating an array of complex behaviors including learning, depression, and circadian rhythms. Additionally, HTR2 receptors on layer V pyramidal neurons are thought to mediate the actions of psychedelic drugs; the native function of these receptors at this site, however, remains unknown. Previously, we found that activation of HTR2 receptors in the zebra finch forebrain song premotor structure the robust nucleus of the arcopallium (RA) led to increased excitation, and that endogenous 5-HT could roughly double spontaneous firing rate. Here, using in vivo single-unit recordings, we found that direct application of 5-HT to these same RA projection neurons, which are analogous to layer V cortical pyramidal neurons, caused a significant increase in the number of action potentials per song-related burst, and a dramatic decrease in signal-to-noise ratio. Injection of the serotonergic neurotoxin 5,7-dihydroxytryptamine into the third ventricle greatly reduced telencephalic 5-HT and resulted in decreased fundamental frequency of harmonic syllables as well as increased goodness of pitch. Both of these results can be explained by the observed actions of 5-HT on RA projection neurons, and both effects recovered to baseline within 2 weeks following the toxin injection. These results show that 5-HT is involved in modulating spectral properties of song, likely via effects on RA projection neurons, but that adult zebra finches can partially compensate for this deficit within 7 d. PMID:23407949

  5. Temporal and Spectral Characteristics of Short Busts from the Soft Gamma Repeaters 1806-20 And 1900+14

    NASA Technical Reports Server (NTRS)

    Goegues, Ersin; Kouveliotou, Chryssa; Woods, Peter M.; Thompson, Christopher; Duncan, Robert C.; Briggs, Michael S.

    2001-01-01

    We study the temporal and coarse spectral properties of 268 bursts from SGR 1806-20 and 679 bursts from SGR 1900+14, all observed with the Rossi X-Ray Timing Explorer/Proportional Counter Array. Hardness ratios and temporal parameters, such as T(sub 90) durations and tau(sub 90) emission times are determined for these bursts. We find a lognormal distribution of burst durations, ranging over more than two orders of magnitude: T(sub 90) equals approximately 10(exp -2) to > 1 s, with a peak at approximately 0.1 s. The burst light curves tend to be asymmetrical, with more than half of all events showing rise times t(sub r) < 0.3 T(sub 90). We find that there exists a correlation between the duration and fluence of bursts from both sources. We also find a significant anticorrelation between hardness ratio and fluence for SGR 1806-20 bursts and a marginal anticorrelation for SGR 1900+14 events. Finally, we discuss possible physical implications of these results within the framework of the magnetar model.

  6. Investigating the spectral characteristic and humification degree of dissolved organic matter in saline-alkali soil using spectroscopic techniques

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Guo, Xujing; Chen, Lu; Li, Yunzhen; Yuan, Donghai; Dai, Benlin; Wang, Sisi

    2017-03-01

    Soil samples were collected from the areas surrounding Wuliangsuhai Lake in China. Dissolved organic matter (DOM) was extracted from the samples and characterized by fluorescence and UV-Vis spectra. Spectral properties and humification degree of DOM were studied. The results indicated that both humic- and protein-like fluorophores were present in the DOM spectra, and the former was the dominant component. The analysis of humification (HIX) and r (A, C) indices revealed that the maximum humification degree in three agricultural soils (AAF, ASC, and ASW) was presented in the second soil layer (20‒40 cm). However, the humification degree of the two Halophytes soils (SSE and GKF) decreased with increasing depth. One index, I344/270, showed that humification degree increased gradually with an increasing proportion of humic-like acid. There was a significant positive correlation between humification degree (HIX) and aromaticity (SUVA254), indicating that a higher aromaticity corresponded to a higher humification degree. Land use was an important factor responsible for the major difference of cation exchange capacity (CEC) in different soils, which led to a higher CEC value in the second soil layer for the three agricultural soils. CEC values and humification degree had the same trend for all five soils. The correlation analysis showed that there was a significant positive correlation between HIX and CEC, and a negative correlation between the r (A, C) index and CEC, indicating that humification degree increases gradually with increasing CEC values.

  7. Spectral properties of different phase composition TiO2

    NASA Astrophysics Data System (ADS)

    Shymanovska, Valentyna V.; Bezrodna, Tamara V.; Melnyk, Vladimir I.; Manzhara, Viktor S.; Khalyavka, Tatjana A.; Viktorova, Tatjana I.; Baran, Jan

    2004-07-01

    Characteristic scattering band in the spectral region of 280-380 rim with the maximum of 300-3 10 nm is observed in the spectra of diffuse scattering for rutile, contrary to anatase sample. Spectral parameters of this band depend on the treatment temperature. Doping of Ti02 samples with Cu, Fe, Co, Cr atoms does not affect the spectral position of the band wing in their diffuse scattering. Luminescence spectra of rutile have only short-wavelength components. Anatase has both fluorescence and phosphorescence at T=4.2 K. At room temperature there is no luminescence detected. Cation-doped anatase does not luminescence at all studied temperatures. Their absorption spectra have a new band in the region of 325-405 nm, which spectral parameters depend on the type ofdoping cation.

  8. Model studies of spectral and photophysical characteristics of a series of donor acceptor polyenes of different length

    NASA Astrophysics Data System (ADS)

    El-Gezawy, Hani; Rettig, Wolfgang

    2006-09-01

    The photophysical behaviour of a series of donor-acceptor-polyenes of different length: 4-dimethylamino-4'-cyanostilbene (DCS), 4-dimethylamino-4'-cyano-1,4-diphenylbutadiene (DCB) and 4-dimethylamino-4'-cyano-1,4-diphenylhexatriene (DCH) has been studied by means of steady state and time resolved fluorescence and low temperature measurements. Quantum chemical calculations were performed for comparison. For all three dyes, the fluorescence quantum yields show a maximum in the most polar solvents. A pronounced solvatochromic behaviour is only observed for the emission spectra whereas the absorption spectra remain nearly unaffected. The nonradiative decay decreases in the order DCS > DCB > DCH. Similarly, the radiative rate constant decreases in this order, contrary to the usual behaviour for a lengthening of the π-system. The chain-length dependence of the dipole moments of the relaxed excited state μe is better described by the Onsager radius derived from molecular length rather than from the density approach. Both calculations and experiments support the conclusion that the emissive state is not a TICT state.

  9. Spectral Characteristic of Tholin Produced from Possible Early Earth Atmospheres and its Role in Antigreenhouse Effect on Early Earth

    NASA Technical Reports Server (NTRS)

    Khare, B. N.; Imanaka, H.; Wilhite, P.; McKay, C.; Bakes, E.; Cruikshank, D. P.; Arakawa, E. T.

    2003-01-01

    We have produced organic material simulating a methane photochemical haze in a CO2- rich atmosphere of the early Earth by irradiating gas mixtures in an inductively coupled cold plasma chamber with pressure approx. 0.25 mbar at 100 W total power. The flow rate was 24 cm3 min. We added progressively higher levels of CH, by combining gas mixtures of N2/CH4 (9/1) and N2/CO2 (9/1) to change the ratio of CH4/CO2. Tholin was accumulated for 5 hours in each experiment; the onset of tholin formation is in the range CH4/CO2 = 0.5 to 1. As the mixing ratio of CH, is increased, the production rate of the brownish tholin film increases. IR spectra showed the C-H and N-H bands similar to that of Titan tholin and closely resemble Titan tholin made at 0.13 mbar pressure. A decrease in the CH bonds on decreasing CH4/CO2 is noted. Ether bands (-(2-O-C) were tentatively detected, but no detectable carbonyl (C=O) band was found. The absorption in the UV region for the early Earth tholin is found to be substantially greater than the Titan tholin. Quantitative values of the optical constants of early Earth tholin are currently being measured.

  10. Full Spectral Resolution Data Generation from the Cross-track Infrared Sounder on S-NPP at NOAA and its Use to Investigate Uncertainty in Methane Absorption Band Near 7.66 µm

    NASA Astrophysics Data System (ADS)

    Xiong, X.; Peischl, J.; Ryerson, T. B.; Sasakawa, M.; Han, Y.; Chen, Y.; Wang, L.; Tremblay, D.; Jin, X.; Zhou, L.; Liu, Q.; Weng, F.; Machida, T.

    2015-12-01

    The Cross-track Infrared Sounder (CrIS) on Suomi National Polar-orbiting Partnership Satellite (S-NPP) is a Fourier transform spectrometer for atmospheric sounding. CrIS on S-NPP started to provide measurements in 1305 channels in its normal mode since its launch on November 2011 to December 4, 2014, and after that it was switched to the full spectral resolution (FSR) mode, in which the spectral resolutions are 0.625 cm-1 in all the MWIR (1210-1750 cm-1), SWIR (2155-2550 cm-1) and the LWIR bands (650-1095 cm-1) with a total of 2211 channels. While the NOAA operational Sensor Data Record (SDR) processing (IDPS) continues to produce the normal resolution SDRs by truncating full spectrum RDR data, NOAA STAR started to process the FSR SDRs data since December 4, 2014 to present, and the data is being delivered through NOAA STAR website (ftp://ftp2.star.nesdis.noaa.gov/smcd/xxiong/). The current FSR processing algorithm was developed on basis of the CrIS Algorithm Development Library (ADL), and is the baseline of J-1 CrIS SDR algorithm. One major benefit to use the FSR data is to improve the retrieval of atmospheric trace gases, such as CH4, CO and CO2 . From our previous studies to retrieve CH4 using Atmospheric Infrared Sounder (AIRS) and Infrared Atmospheric Sounding Interferometer (IASI), it was found the uncertainty in the CH4 absorption band is up to 1-2%. So, in this study we computed the radiance using the community radiative transfer model (CRTM) and line-by-line model, with the inputs of "truth" of atmospheric temperature and moisture profiles from ECMWF model (and/or RAOB sounding) and CH4 profiles from in-situ aircraft measurements, then convoluted with the response function of CrIS. The difference between the simultaed radiance and the collocated CrIS FSR data is used to exam the uncertainty in these strong absorption channels.Through the improved fitting to the transmittance in these channels, it is expected to improve the retrieval of CH4 using CrIS on S

  11. Aerosol Absorption Measurements in MILAGRO.

    NASA Astrophysics Data System (ADS)

    Gaffney, J. S.; Marley, N. A.; Arnott, W. P.; Paredes-Miranda, L.; Barnard, J. C.

    2007-12-01

    During the month of March 2006, a number of instruments were used to determine the absorption characteristics of aerosols found in the Mexico City Megacity and nearby Valley of Mexico. These measurements were taken as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City (MAX-Mex) that was carried out in collaboration with the Megacity Interactions: Local and Global Research Observations (MILAGRO) campaign. MILAGRO was a joint effort between the DOE, NSF, NASA, and Mexican agencies aimed at understanding the impacts of a megacity on the urban and regional scale. A super-site was operated at the Instituto Mexicano de Petroleo in Mexico City (designated T-0) and at the Universidad Technologica de Tecamac (designated T-1) that was located about 35 km to the north east of the T-0 site in the State of Mexico. A third site was located at a private rancho in the State of Hidalgo approximately another 35 km to the northeast (designated T-2). Aerosol absorption measurements were taken in real time using a number of instruments at the T-0 and T-1 sites. These included a seven wavelength aethalometer, a multi-angle absorption photometer (MAAP), and a photo-acoustic spectrometer. Aerosol absorption was also derived from spectral radiometers including a multi-filter rotating band spectral radiometer (MFRSR). The results clearly indicate that there is significant aerosol absorption by the aerosols in the Mexico City megacity region. The absorption can lead to single scattering albedo reduction leading to values below 0.5 under some circumstances. The absorption is also found to deviate from that expected for a "well-behaved" soot anticipated from diesel engine emissions, i.e. from a simple 1/lambda wavelength dependence for absorption. Indeed, enhanced absorption is seen in the region of 300-450 nm in many cases, particularly in the afternoon periods indicating that secondary organic aerosols are contributing to the aerosol absorption. This is likely due

  12. Use of the characteristic Raman lines of toluene (C7 H8) as a precise frequency reference on the spectral analysis of gasoline-ethanol blends

    NASA Astrophysics Data System (ADS)

    Ortega Clavero, Valentin; Javahiraly, Nicolas; Weber, Andreas; Schröder, Werner; Curticapean, Dan; Meyrueis, Patrick P.

    2014-09-01

    In order to reduce some of the toxic emissions produced by internal combustion engines, the fossil-based fuels have been combined with less harmful materials in recent years. However, the fuels used in the automotive industry generally contain different additives, such as toluene, as anti-shock agents and as octane number enhancers. These materials can cause certain negative impact, besides the high volatility implied, on public health or environment due to its chemical composition. Toluene, among several other chemical compounds, is an additive widely used in the commercially-available gasoline-ethanol blends. Despite the negative aspects in terms of toxicity that this material might have, the Raman spectral information of toluene can be used to achieve certain level of frequency calibration without using any additional chemical marker in the sample or any other external device. Moreover, the characteristic and well-defined Raman line of this chemical compound at 1003 cm-1 (even at low v/v content) can be used to quantitatively determine certain aspects of the gasoline-ethanol blend under observation. By using an own-designed Fourier-Transform Raman spectrometer (FT-Raman), we have collected and analyzed different commercially-available and laboratory-prepared gasoline-ethanol blends. By carefully observing the main Raman peaks of toluene in these fuel blends, we have determined the frequency accuracy of the Raman spectra obtained. The spectral information has been obtained in the range of 0 cm-1 to 3500 cm-1 with a spectral resolution of 1.66 cm-1. The Raman spectra obtained presented only reduced frequency deviations in comparison to the standard Raman spectrum of toluene provided by the American Society for Testing and Materials (ASTM).

  13. Characteristic tandem mass spectral features under various collision chemistries for site-specific identification of protein S-glutathionylation.

    PubMed

    Chou, Chi-Chi; Chiang, Bing-Yu; Lin, Jason Ching-Yao; Pan, Kuan-Ting; Lin, Chun-Hung; Khoo, Kay-Hooi

    2015-01-01

    Protein S-glutathionylation is a reversible post-translational modification widely implicated in redox regulated biological functions. Conventional biochemical methods, however, often do not allow such a mixed disulfide modification to be reliably identified on specific cysteine residues or be distinguished from other related oxidized forms. To develop more efficient mass spectrometry (MS)-based analytical strategies for this purpose, we first investigated the MS/MS fragmentation pattern of S-glutathionylated peptides under various dissociation modes, including collision-induced dissociation (CID), higher-energy C-trap dissociation (HCD), and electron transfer dissociation (ETD), using synthetic peptides derived from protein tyrosine phosphatase as models. Our results indicate that a MALDI-based high energy CID MS/MS on a TOF/TOF affords the most distinctive spectral features that would facilitate rapid and unambiguous identification of site-specific S-glutathionylation. For more complex proteomic samples best tackled by LC-MS/MS approach, we demonstrate that HCD performed on an LTQ-Orbitrap hybrid instrument fairs better than trap-based CID and ETD in allowing more protein site-specific S-glutathionylation to be confidently identified by direct database searching of the generated MS/MS dataset using Mascot. Overall, HCD afforded more peptide sequence-informative fragment ions retaining the glutathionyl modification with less neutral losses of side chains to compromise scoring. In conjunction with our recently developed chemo-enzymatic tagging strategy, our nanoLC-HCD-MS/MS approach is sufficiently sensitive to identify endogenous S-glutathionylated peptides prepared from non-stressed cells. It is anticipated that future applications to global scale analysis of protein S-glutathionylation will benefit further from current advances in both speed and mass accuracy afforded by HCD MS/MS mode on the Orbitrap series.

  14. Characteristic Tandem Mass Spectral Features Under Various Collision Chemistries for Site-Specific Identification of Protein S-Glutathionylation

    NASA Astrophysics Data System (ADS)

    Chou, Chi-Chi; Chiang, Bing-Yu; Lin, Jason Ching-Yao; Pan, Kuan-Ting; Lin, Chun-Hung; Khoo, Kay-Hooi

    2015-01-01

    Protein S-glutathionylation is a reversible post-translational modification widely implicated in redox regulated biological functions. Conventional biochemical methods, however, often do not allow such a mixed disulfide modification to be reliably identified on specific cysteine residues or be distinguished from other related oxidized forms. To develop more efficient mass spectrometry (MS)-based analytical strategies for this purpose, we first investigated the MS/MS fragmentation pattern of S-glutathionylated peptides under various dissociation modes, including collision-induced dissociation (CID), higher-energy C-trap dissociation (HCD), and electron transfer dissociation (ETD), using synthetic peptides derived from protein tyrosine phosphatase as models. Our results indicate that a MALDI-based high energy CID MS/MS on a TOF/TOF affords the most distinctive spectral features that would facilitate rapid and unambiguous identification of site-specific S-glutathionylation. For more complex proteomic samples best tackled by LC-MS/MS approach, we demonstrate that HCD performed on an LTQ-Orbitrap hybrid instrument fairs better than trap-based CID and ETD in allowing more protein site-specific S-glutathionylation to be confidently identified by direct database searching of the generated MS/MS dataset using Mascot. Overall, HCD afforded more peptide sequence-informative fragment ions retaining the glutathionyl modification with less neutral losses of side chains to compromise scoring. In conjunction with our recently developed chemo-enzymatic tagging strategy, our nanoLC-HCD-MS/MS approach is sufficiently sensitive to identify endogenous S-glutathionylated peptides prepared from non-stressed cells. It is anticipated that future applications to global scale analysis of protein S-glutathionylation will benefit further from current advances in both speed and mass accuracy afforded by HCD MS/MS mode on the Orbitrap series.

  15. The color of mass culture: spectral characteristics of a shallow water column through shade-limited algal growth dynamics(1).

    PubMed

    Hewes, Christopher D

    2016-04-01

    It is envisioned that mass algal cultivation for commercial biofuels production will entail the use of large raceway pond systems, which typically have shade-limited photosynthetic growth within depths of 20-30 cm. The attenuation of light and spectral qualities of red, green, and blue wavelengths in a 20-cm water column as a function of Chl-a concentration during exponential and linear phases of growth dynamics for the marine diatom Thalassiosira pseudonana was examined under laboratory conditions. While photosynthetically available radiation (PAR) was in excess throughout the water column during the phase of exponential growth, PAR became rate limiting differently for red, green, and blue wavelengths during the phase of linear growth. The transition from exponential to linear growth occurred at 1-2 mg Chl-a · L-1, whereby a scalar ~5 μmol photons · m-2 · s-1 at 20-cm depth was found to occur as would be anticipated having the compensation point for where rates of photosynthesis and respiration are equal. During the phase of linear growth, red wavelengths became increasingly dominant at depth as Chl-a concentrations increased, being contrary to the optical conditions for those natural bodies of water that forced the evolution of phytoplankton photosynthesis. It is hypothesized this dramatic difference in water column optics between natural and synthetic environments could influence a variety of biological reactions, importantly non-photochemical quenching capacities, which could negatively impact crop yield.

  16. Optical absorption characteristics in the assessment of powder phosphor-based x-ray detectors: from nano- to micro-scale

    NASA Astrophysics Data System (ADS)

    Liaparinos, P. F.

    2015-11-01

    X-ray phosphor-based detectors have enormously improved the quality of medical imaging examinations through the optimization of optical diffusion. In recent years, with the development of science and technology in the field of materials, improved powder phosphors require structural and optical properties that contribute to better optical signal propagation. The purpose of this paper was to provide a quantitative and qualitative understanding of the optical absorption characteristics in the assessment of powder phosphor-based detectors (from nano- scale up to micro-scale). Variations on the optical absorption parameters (i.e. the light extinction coefficient {{m}\\text{ext}} and the percentage probability of light absorption p%) were evaluated based on Mie calculations examining a wide range of light wavelengths, particle refractive indices and sizes. To model and assess the effects of the aforementioned parameters on optical diffusion, Monte Carlo simulation techniques were employed considering: (i) phosphors of different layer thickness, 100 μm (thin layer) and 300 μm (thick layer), respectively, (ii) light extinction coefficient values, 1, 3 and 6 μm-1, and (iii) percentage probability of light absorption p% in the range 10-4-10-2. Results showed that the {{m}\\text{ext}} coefficient is high for phosphor grains in the submicron scale and for low light wavelengths. At higher wavelengths (above 650 nm), optical quanta follow approximately similar depths until interaction for grain diameter 500 nm and 1 μm. Regarding the variability of the refractive index, high variations of the {{m}\\text{ext}} coefficient occurred above 1.6. Furthermore, results derived from Monte Carlo modeling showed that high spatial resolution phosphors can be accomplished by increasing the {{m}\\text{ext}} parameter. More specifically, the FWHM was found to decrease (i.e. higher resolution): (i) 4.8% at 100 μm and (ii) 9.5%, at 300 μm layer thickness. This study attempted to

  17. Exploiting Electrocorticographic Spectral Characteristics for Optimized Signal Chain Design: A 1.08 Analog Front End With Reduced ADC Resolution Requirements.

    PubMed

    Smith, William A; Mogen, Brian J; Fetz, Eberhard E; Sathe, Visvesh S; Otis, Brian P

    2016-12-01

    Electrocorticography (ECoG) is an important area of research for Brain-Computer Interface (BCI) development. ECoG, along with some other biopotentials, has spectral characteristics that can be exploited for more optimal front-end performance than is achievable with conventional techniques. This paper optimizes noise performance of such a system and discusses an equalization technique that reduces the analog-to-digital converter (ADC) dynamic range requirements and eliminates the need for a variable gain amplifier (VGA). We demonstrate a fabricated prototype in 1p9m 65 nm CMOS that takes advantage of the presented findings to achieve high-fidelity, full-spectrum ECoG recording. It requires 1.08 μW over a 150 Hz bandwidth for the entire analog front end and only 7 bits of ADC resolution.

  18. Two-photon absorption by a quantum dot pair

    NASA Astrophysics Data System (ADS)

    Scheibner, Michael; Economou, Sophia E.; Ponomarev, Ilya V.; Jennings, Cameron; Bracker, Allan S.; Gammon, Daniel

    2015-08-01

    The biexciton absorption spectrum of a pair of InAs/GaAs quantum dots is being studied by photoluminescence excitation spectroscopy. An absorption resonance with the characteristics of an instantaneous two-photon process reveals a coherent interdot two-photon transition. Pauli-selective tunneling is being used to demonstrate the transduction of the two-photon coherence into a nonlocal spin singlet state. The two-photon transition can be tuned spectrally by electric field, enabling amplification of its transition strength.

  19. Solar Absorption in Cloudy Atmospheres

    NASA Technical Reports Server (NTRS)

    Harshvardhan; Ridgway, William; Ramaswamy, V.; Freidenreich, S. M.; Batey, Michael

    1996-01-01

    The theoretical computations used to compute spectral absorption of solar radiation are discussed. Radiative properties relevant to the cloud absorption problem are presented and placed in the context of radiative forcing. Implications for future measuring programs and the effect of horizontal inhomogeneities are discussed.

  20. Evaluation of in vitro release rate and in vivo absorption characteristics of four metoprolol tartrate immediate-release tablet formulations.

    PubMed

    Rekhi, G S; Eddington, N D; Fossler, M J; Schwartz, P; Lesko, L J; Augsburger, L L

    1997-02-01

    The purpose of this investigation was to examine the impact of formulation and process changes on dissolution and bioavailability/bioequivalency of metoprolol tartrate tablets manufactured using a high-shear granulation process. A half-factorial (2(4-1), Res IV) design was undertaken to study the selected formulation and processing variables during scale-up. Levels and ranges for excipients and processing changes studied represented level 2 or greater changes as indicated by the SUPAC-IR Guidance. Blend and tableting properties were evaluated. Changes in sodium starch glycolate and magnesium stearate levels, and the order of addition microcrystalline cellulose (intra- vs. extragranular) were significant only in affecting percent drug released (Q) in 5, 10, and 15 min. Statistical analysis of data showed no significant curvature. No interaction effects were found to be statistically significant. To examine the impact of formulation and processing variables on in vivo absorption, three batches were selected for a bioavailability study based on their dissolution profiles. Subjects received four metoprolol treatments (Lopressor, slow-, medium-, and fast-dissolving formulations) separated by 1 week according to a randomized crossover design. After an overnight fast, subjects were administered one tablet (100 mg), blood samples were collected over 24 hr and plasma samples were analyzed. The formulations were found to be bioequivalent with respect to the log Cmax and log AUC0-infinity. The results of this study suggest that: (i) bioavailability/bioequivalency studies may not be necessary for metoprolol tartrate and perhaps other class 1 drugs after level 2 type changes and (ii) in vitro dissolution tests may be used to show bioequivalence of metoprolol formulations with processing or formulation changes within the specified level 2 ranges for the equipment examined.

  1. Research of spectral characteristics of ubiquinone solution and explore of the solvent effect on the experimental results

    NASA Astrophysics Data System (ADS)

    Timofeeva, Elvira O.; Gorbunova, Elena V.; Korotaev, Valery V.

    2016-04-01

    This work is dedicated to the research of the clinical diagnosis method of determining the antioxidant status of the human body. The existing methods for determining the level of antioxidants in connection with biological functions of the human antioxidant system were studied. Antioxidants in the human body, in the form of solutions were chosen as a research objects. The technique of experimental studies of ubiquinone solutions in oil and alcohol by spectroscopic method was offered. The experimental results connected with the optical density and color characteristics confirm the possibility of applying the clinical diagnosis method of estimation antioxidant balance. Also, it was found that this method can be applicable to the quality control of medicines for treating diseases provoked by oxidative stress, which means that this method may be developed not only for using in the clinic.

  2. Hydrogen absorption and desorption kinetics in fullerite C60 single crystals. Low-temperature micromechanical and structural characteristics of the interstitial solid solution C60(H2)x

    NASA Astrophysics Data System (ADS)

    Fomenko, L. S.; Lubenets, S. V.; Natsik, V. D.; Stetsenko, Yu. E.; Yagotintsev, K. A.; Strzhemechny, M. A.; Prokhvatilov, A. I.; Osipyan, Yu. A.; Izotov, A. N.; Sidorov, N. S.

    2008-01-01

    The microhardness HV and lattice parameter a of C60 single crystals are measured at room temperature as functions of the hydrogen saturation time t for several values of the saturation temperature (250, 300, and 350°C) at a fixed hydrogen pressure p =30atm. According to the measurements of HV and a, the kinetics of hydrogen absorption is described by a simple exponential law with a single, temperature-dependent characteristic time. In highly saturated samples the microhardness is 4 times greater than for the initial C60 crystal, while the lattice parameter is 0.2% larger. The temperature dependence of the microhardness HV and lattice parameter a of C60(H2)x crystals is investigated in the temperature interval 77-300K. The introduction of hydrogen lowers the temperature of the fcc-sc phase transition, and the transition becomes strongly broadened in temperature. The dependence of the microhardness of the saturated sample on the hold time in air at room temperature is described by the sum of two exponentials with different characteristic times. Kinetics of this kind is presumably due to two processes: desorption of hydrogen from the sample, which causes a decrease of the microhardness, and a simultaneous penetration of gaseous impurities into the sample from the surrounding air, which is accompanied by hardening. The influence of the H2 molecules on the characteristic of the intermolecular interaction in fullerite C60 is discussed and the intercalation-induced processes of dislocation slip and microfracture.

  3. Absorption and fluorescence characteristics of photo-activated adenylate cyclase nano-clusters from the amoeboflagellate Naegleria gruberi NEG-M strain

    NASA Astrophysics Data System (ADS)

    Penzkofer, A.; Stierl, M.; Hegemann, P.; Kateriya, S.

    2012-01-01

    The spectroscopic characteristics of BLUF (BLUF = sensor of blue light using flavin) domain containing soluble adenylate cyclase (nPAC = Naegleria photo-activated cyclase) samples from the amoeboflagellate Naegleria gruberi NEG-M strain is studied at room temperature. The absorption and fluorescence spectroscopic development in the dark was investigated over two weeks. Attenuation coefficient spectra, fluorescence quantum distributions, fluorescence quantum yields, and fluorescence excitation distributions were measured. Thawing of frozen nPAC samples gave solutions with varying protein nano-cluster size and varying flavin, tyrosine, tryptophan, and protein color-center emission. Protein color-center emission was observed in the wavelength range of 360-900 nm with narrow emission bands of small Stokes shift and broad emission bands of large Stokes shift. The emission spectra evolved in time with protein nano-cluster aging.

  4. Project STOP (Spectral Thermal Optimization Program)

    NASA Technical Reports Server (NTRS)

    Goldhammer, L. J.; Opjorden, R. W.; Goodelle, G. S.; Powe, J. S.

    1977-01-01

    The spectral thermal optimization of solar cell configurations for various solar panel applications is considered. The method of optimization depends upon varying the solar cell configuration's optical characteristics to minimize panel temperatures, maximize power output and decrease the power delta from beginning of life to end of life. Four areas of primary investigation are: (1) testing and evaluation of ultraviolet resistant coverslide adhesives, primarily FEP as an adhesive; (2) examination of solar cell absolute spectral response and corresponding cell manufacturing processes that affect it; (3) experimental work with solar cell manufacturing processes that vary cell reflectance (solar absorptance); and (4) experimental and theoretical studies with various coverslide filter designs, mainly a red rejection filter. The Hughes' solar array prediction program has been modified to aid in evaluating the effect of each of the above four areas on the output of a solar panel in orbit.

  5. [Analysis of Component Spectral Characteristics of PM10-Bound PAHs and the Influence of Weather Conditions During Spring in Xiamen].

    PubMed

    Zhang, Jian; Fan, Shu-xian; Sun, Yu; Zhang, Yue; Wei, Jin-cheng

    2015-04-01

    In order to study pollution status and distribution characteristics of PAHs in PM10 during the spring in city and suburban Xiamen. A total of 18 PAHs were analyzed in the aerosol samples collected in daytime and nighttime during 11th to 21st of April, 2013 in city and suburban Xiamen. Results showed diurnal variation of Σ PAHs in suburban was weaker than that in city. In the city, the concentration of PAHs during daytimes was higher than that during nighttimes, close to 1.83 times, and it is still under the national environmental standards. In different times and space scales, PAHs were a bimodal distribution, the components of PAHs gave the priority to low and middle rings in urban and suburban during daytimes and nighttimes. PAHs with high molecular weight decreased gradually by the increase of particle size, and the proportion of low molecular weight PAHs increased gradually in the meantime. In the city, the change of size distribution among 2-4 rings PAHs in PM10 during days and nights was bigger than these among 5-7 rings. The main sources of PAHs were estimated by DR, the main contributions included gasoline and diesel combustion, the smelting furnace exhaust emissions. During sampling periods, the relationship between the concentration of PAHs, temperature and WD is negative, PAHs had a positive correlation with the visibility and WS in suburban. And in urban, the relationship with temperature during the day was negative, and with an opposite correlation between other meteorological elements.

  6. Depth profiles of spectral and hydrological characteristics of water and their relation to abundances of green sulfur bacteria in the stratified lakes of the White Sea

    NASA Astrophysics Data System (ADS)

    Kharcheva, Anastasia V.; Krasnova, Elena D.; Gorlenko, Vladimir M.; Lunina, Olga N.; Savvichev, Alexander S.; Voronov, Dmitry A.; Zhiltsova, Anna A.; Patsaeva, Svetlana V.

    2016-04-01

    We analyze the results received from two expeditions performed in August-September 2013, August-September 2014 and February 2015 in the Kandalaksha Bay of the White Sea. Depth profiles of hydrological characteristics and optical properties of water were recorded for five marine lakes being on different stages of isolation from the White Sea. Those relic lakes demonstrate a tendency to meromixis and are characterized by apparent stratification of the water bodies from the brackish top layer to the bottom salt water. Maximal concentrations of anoxygenic phototrophs (green sulfur bacteria) were found at depths close to the redox interface in all the studied lakes. To discriminate differently pigmented groups of microorganisms the fluorescence emission spectra of bacteriochlorophylls from the living cells were used. We puzzle out the data on light spectrum propagation through the water body in each lake using optical properties of water (attenuation spectra) in the UV, visible and NIR ranges, as well as direct measurements of the total irradiances at various depths. The changes in optical characteristics of water in the stratified reservoirs due to cromophoric dissolved organic matter (CDOM) and microbial pigments affect the light intensity and its spectral distribution at each water layer thus influencing the living conditions for differently pigmented phototrophic microorganisms and determining the composition of microbial community.

  7. Analysis of the spectral response of Tamarix spp vegetation to the soil salinity based on ground spectral measurements

    NASA Astrophysics Data System (ADS)

    Jiapaer, Guli; Chen, Xi; Bao, Anming

    2010-10-01

    In this paper, the field-derived hyperspecral reflectance of the Tamarix spp vegetation and background soil parameters (soluble salt content and eight base ions) of associated saline soil at the lower reaches of the Tarim River were measured and studied. The spectral responses of the Tamarix spp canopy with different level saline soil, and the relationship between soil salt variables and vegetation spectral indices were analyzed in order to understand the sensitive bands and the appropriate vegetation spectral indices. The results revealed that:(1) the spectra at band ranges 600-750nm,1350-1550nm change regularly with the increasing salt content of the background soil. (2) The removal continuum reflectance shows that the three absorb troughs with band ranges 460-560nm, 560-760nm,1050-1300nm, 1300-1700nm, can play an important role in indicating increasing changes of soil salt. Theses sensitive bands just reflect the characteristics of the chlorophyll content, moisture content of the vegetation. It presents a negative correction between the absorption valley changing trend and the salt content in the background soil. When the soil salinity content is higher, the corresponding absorption valley value that reflects vegetation growth condition characteristic is not more obvious. (3) Further analysis are conducted on the absorption width at the band range 1300-1700nm, the absorption width at the band range 560-760nm, λred, absorption depth at the band range 1050-1300nm, R1450, MSAVI, trough area of the band range 560-760nm, λred and the absorption depth at the band range 560-760nm, these nine indices can be used to predict salt values of saline soil and evaluate the degree of soil salinity.

  8. [Study on Spectral Characteristics of Micro Plasma Channels of Different Gas-Gap in Dielectric Barrier Discharge].

    PubMed

    Gao, Ye-nan; Dong, Li-fang; Liu, Ying

    2015-10-01

    By optical emission spectrum, we report on the first investigation on the plasma parameters of micro plasma channels which are generated in two gas-gaps with different thickness in a triple-layer dielectric barrier discharge system. Different from the micro plasma channels formed in traditional two-layer dielectric barrier discharge, micro plasma channels formed in the triple-layer dielectric barrier discharge system reflect a unique discharge characteristic. From the pattern images taken by an ordinary camera, it shows that micro plasma channels generated in two discharge gas-gaps discharge with different sizes and light intensities. The micro plasma channels in wide gas-gap are much bigger than those in narrow gas-gap, and their light intensities are obvious stronger. By collecting the emission spectra of N2 second positive band (C3∏u --> B3∏g ) and calculating the relative intensity ratio method of N2 molecular ion line at 391.4 and the N2 molecular line at 394.1, the molecular vibration temperature and the average electron energy of micro plasma channels in two gas-gaps as functions of Argon concentration and applied voltage are investigated, respectively. It is found that the molecular vibration temperature and the average electron energy of micro plasma channels in wide gas-gap are lower than those in narrow gas-gap, and they both decrease with the increasing of the Argon concentration. As the applied voltage increases, micro plasma channels in wide gas-gap vary in a small range on the above two plasma investigations, while those in narrow gas-gap vary obviously. It indicates that micro plasma channels in narrow gas-gap are more sensitive to the applied voltage and they have a wider variation range of electric field than those in wide gas-gap.

  9. Spectral characteristics of fluorescence and circular dichroism of aflatoxin B1 reaction with its anti-idiotypic antibody

    NASA Astrophysics Data System (ADS)

    Liu, Aiping; Yang, Hongxiu; Wang, Xiaohong; Chen, Fusheng

    2012-11-01

    Aflatoxin B1 (AFB1) is a toxic secondary metabolite and sensitive methods for its analysis have been developed. In our lab, a number of works have been carried out, including exploitation of detection methods and production of anti-idiotypic antibody (Ab2) against Fab fragment of anti-AFB1 antibody (Ab1). In this paper, Ab2 was generated upon the immunization of mice with F(ab')2 fragment, which was specific to AFB1 and obtained by pepsin digestion of Ab1. The characteristics of Ab2 was primarily investigated by indirect competitive enzyme-linked immunosorbent assay (icELISA), which indicated that Ab2, might bear an internal image of antigen AFB1 and was able to combine to F(ab')2 in competition with AFB1, and the concentration of Ab2 to cause 50% inhibition of binding (IC50) was 131.8 μg/mL. In addition, fluorescence and circular dichroism studies were designed to explore the mutual relationship among AFB1, F(ab')2 and Ab2. The fluorescence spectroscopy implied that both AFB1 and Ab2 act as a quencher upon F(ab')2, and the Ab2 could compete with AFB1 when both of Ab2 and AFB1 reacted with F(ab')2. The circular dichroism (CD) spectrum suggested that both the binding of Ab2 and AFB1 on F(ab')2 brought secondary conformation change of F(ab')2, especially in the changes of α helix and β sheet. The research performed would provide unique insight into the comprehension of interaction among AFB1, F(ab')2 and Ab2 as well as offer structural information for substitution researches of toxic antigen like AFB1.

  10. [Light absorption by suspended particulate matter in Chagan Lake, Jilin].

    PubMed

    Wang, Yuan-Dong; Liu, Dian-Wei; Song, Kai-Shan; Zhang, Bai; Wang, Zong-Ming; Jiang, Guang-Ji; Tang, Xu-Guang; Lei, Xiao-Chun; Wu, Yan-Qing

    2011-01-01

    Spectral characteristics and the magnitudes of light absorption by suspended particulate matter were determined by spectrophotometry in this optically complex Lake Chagan waters for the purpose of surveying the natural variability of the absorption coefficients to parameterize the bio-optical models for converting satellite or in-situ water reflectance signatures into water quality information. Experiments were carried out on seasonal frozen Lake Chagan, one representative inland case-2 water body in Northeast of China. Particulate absorption properties analyzed using the field data on July 15th and October 12th 2009 were measured using the quantitative filter technique to produce absorption spectra containing several fractions that could be attributed to two main optical active constituents (OACs) phytoplankton pigments and non-algal particulates (mineral sediments, and organic detritus). Results suggested that the suspended particulate matter (SPM) concentration was higher while phytoplankton biomass (chlorophyll-a concentration) was lower in July and that in October. The spectral shape of total suspended particulate matter resembled that of non-algal particulates which contributed greater than phytoplankton in total particulate absorption during both periods. An obvious absorption peak occurring at around 440 nm exhibited an increase in phytoplankton contribution in October. Non-algal particulate absorption at 440 nm (a(NAP) (440)) had better correlation with total suspended particulate matter concentration than that with chlorophyll-a over the two periods. Light absorption by phytoplankton pigments in the Chagan lake region was generally lower than that of non-algal components. Chl. a dominating phytoplankton pigment composition functioned exponentially with its absorption coefficients at 440 and 675 nm specifically, the average values of which in July were 0.146 8 m2 x mg(-1) and 0.050 3 respectively while in October they were 0.153 3 and 0.013 2 m2 x mg(-1

  11. Features of the spectral dependences of transmittance of organic semiconductors based on tert-butyl substituted lutetium phthalocyanine molecules

    SciTech Connect

    Belogorokhov, I. A.; Tikhonov, E. V.; Dronov, M. A.; Belogorokhova, L. I.; Ryabchikov, Yu. V.; Tomilova, L. G.; Khokhlov, D. R.

    2011-11-15

    Vibronic properties of organic semiconductors based on tert-butyl substituted phthalocyanine lutetium diphthalocyanine molecules are studied by IR and Raman spectroscopy. It is shown that substitution of several carbon atoms in initial phthalocyanine (Pc) ligands with {sup 13}C isotope atoms causes a spectral shift in the main absorption lines attributed to benzene, isoindol, and peripheral C-H groups. A comparison of spectral characteristics showed that the shift can vary from 3 to 1 cm{sup -1}.

  12. [Characteristics of absorption and fluorescence spectra of dissolved organic matter from confluence of rivers: case study of Qujiang River-Jialing River and Fujiang River-Jialing River].

    PubMed

    Yan, Jin-Long; Jiang, Tao; Gao, Jie; Wei, Shi-Qiang; Lu, Song; Liu, Jiang

    2015-03-01

    Three-dimensional fluorescence spectroscopy combined with ultraviolet-visible (UV-Vis) absorption spectra was used to investigate the change characteristics of dissolved organic matter (DOM) in confluences water of Qujiang River-Jialing River and Fujiang River-Jialing River, respectively. The results suggested that DOM showed a significant terrestrial input signal in all the sampling sites, FI < 1.4, HIX > 0.8, possibly representing remarkable signals of humus resulted from humic-like component. Moreover, the mixing zone of this study showed a non-conservative mixed behavior, which had a limited contribution, and was not the dominant factor to interpret the change characteristics of DOM in confluences zones. Different land-use types along all the rivers had an obvious impact on DOM inputs. Results of cluster analysis showed that a higher degree of aromaticity and humification components was observed as the predominant contributor to DOM when the land-use type was forest and farmland ecosystem, for example the confluences of Qujiang River-Jialing River. On the other hand, high concentrations of DOM with relative simple structures were found in the water when the urban land-use type was predominant, for example the confluences of Fujiang River-Jialing River. Meanwhile, a new fluorescent signal of protein-like components (peak T) appeared, which manifested a significant effect on the water quality resulted from anthropogenic activities.

  13. Absorption of solar radiation in broken clouds

    SciTech Connect

    Zuev, V.E.; Titov, G.A.; Zhuravleva, T.B.

    1996-04-01

    It is recognized now that the plane-parallel model unsatisfactorily describes the transfer of radiation through broken clouds and that, consequently, the radiation codes of general circulation models (GCMs) must be refined. However, before any refinement in a GCM code is made, it is necessary to investigate the dependence of radiative characteristics on the effects caused by the random geometry of cloud fields. Such studies for mean fluxes of downwelling and upwelling solar radiation in the visible and near-infrared (IR) spectral range were performed by Zuev et al. In this work, we investigate the mean spectral and integrated absorption of solar radiation by broken clouds (in what follows, the term {open_quotes}mean{close_quotes} will be implied but not used, for convenience). To evaluate the potential effect of stochastic geometry, we will compare the absorption by cumulus (0.5 {le} {gamma} {le} 2) to that by equivalent stratus ({gamma} <<1) clouds; here {gamma} = H/D, H is the cloud layer thickness and D the characteristic horizontal cloud size. The equivalent stratus clouds differ from cumulus only in the aspect ratio {gamma}, all the other parameters coinciding.

  14. Spectral and Spread Spectral Teleportation

    SciTe