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Sample records for absorption spectrophotometry showed

  1. Computer programs for absorption spectrophotometry.

    PubMed

    Jones, R N

    1969-03-01

    Brief descriptions are given of twenty-two modular computer programs for performing the basic numerical computations of absorption spectrophotometry. The programs, written in Fortran IV for card input and output, are available from the National Research Council of Canada. The input and output formats are standardized to permit easy interfacing to yield more complex data processing systems. Though these programs were developed for ir spectrophotometry, they are readily modified for use with digitized visual and uv spectrophotometers. The operations covered include ordinate and abscissal unit and scale interconversions, ordinate addition and subtraction, location of band maxima and minima, smoothing and differentiation, slit function convolution and deconvolution, band profile analysis and asymmetry quantification, Fourier transformation to time correlation curves, multiple overlapping band separation in terms of Cauchy (Lorentz), Gauss, Cauchy-Gauss product, and Cauchy-Gauss sum functions and cell path length determination from fringe spacing analysis.

  2. Maps and tables showing data and analyses of semiquantitative emmission spectrometry and atomic-absorption spectrophotometry of rock samples, Ugashik, Bristol Bay, and part of Karluk quadrangles, Alaska

    USGS Publications Warehouse

    Wilson, F.H.; O'Leary, R. M.

    1986-01-01

    The accompanying maps and tables show analytical data and data analyses from rock samples collected in conjunction with geologic mapping in the Ugashik, Bristol Bay and western Karluck quadrangles from 1979 through 1981. This work was conducted under the auspices of the Alaska Mineral Resource Assessment Program (AMRAP). A total of 337 samples were collected for analysis, primarily in areas of surficial alteration. The sample locations are shown on sheet 1: they are concentrated along the Pacific Ocean side of the area because the Bristol Bay lowlands part of the map is predominantly unconsolidated Quaternary deposits. Sample collection was by the following people, with their respective two letter identifying code shown in parentheses: W.H. Allaway (AY), J.E. Case (CE), D.P. Cox (CX), R.L. Detterman, (DT), T.G. Theodore (MK), F.H. Wilson (WS), and M.E. Yount (YB).

  3. Studies of selected transuranium and lanthanide triiodides under pressure using absorption spectrophotometry

    SciTech Connect

    Haire, R.G.; Young, J.P.; Peterson, J.R.; Benedict, U.

    1986-01-01

    The anhydrous triiodides of plutonium, americium, and curium under pressure have been investigated using absorption spectrophotometry. These initial studies on plutonium and curium triiodides together with the published data for americium triiodide show that the rhombohedral (BiI/sub 3/-type structure) form of these compounds can be converted to the same orthorhombic (PuBr/sub 3/-type structure) form by applying pressure at room temperature. Absorption spectrophotometry can often differentiate between two crystallographic forms of materials and has been used in the present high pressure studies to monitor the effects of pressure on the triiodides. A complication in these studies of the triiodides is a significant shift of their absorption edges from the near uv to the visible spectral region with pressure. With curium triiodide this shift causes interference with the major f-f absorption peaks and precludes identification by absorption spectrophotometry of the high pressure phase of CmI/sub 3/. 21 refs., 2 figs.

  4. Spectrophotometry of six broad absorption line QSOs

    NASA Technical Reports Server (NTRS)

    Junkkarinen, Vesa T.; Burbidge, E. Margaret; Smith, Harding E.

    1987-01-01

    Spectrophotometric observations of six broad absorption-line QSOs (BALQSOs) are presented. The continua and emission lines are compared with those in the spectra of QSOs without BALs. A statistically significant difference is found in the emission-line intensity ratio for (N V 1240-A)/(C IV 1549-A). The median value of (N V)/(C IV) for the BALQSOs is two to three times the median for QSOs without BALs. The absorption features of the BALQSOs are described, and the column densities and limits on the ionization structure of the BAL region are discussed. If the dominant ionization mechanism is photoionization, then it is likely that either the ionizing spectrum is steep or the abundances are considerably different from solar. Collisional ionization may be a significant factor, but it cannot totally dominate the ionization rate.

  5. Analysis of cement by atomic absorption spectrophotometry and volumetric method.

    PubMed

    Choi, K K; Lam, L; Luk, S F

    1994-01-01

    A new method to determine the composition of cement raw mix and cement is devised. The sample was fused with a mixture of sodium carbonate and lithium tetraborate (3:1) at 925 degrees C for 10 min. The fusion cake was dissolved in hydrochloric acid. The concentration of analyte in solution was either determined by atomic absorption spectrophotometry or titrimetry. The proposed method is quick and the analysis for interested oxides (SiO(2), Al(2)O(3), Fe(2)O(3), and CaO) can be completed within 1 hr. The accuracy and precision are comparable to that of X-ray fluorescence spectrometry.

  6. Electrothermal atomic absorption spectrophotometry of nickel in tissue homogenates

    SciTech Connect

    Sunderman, F.W. Jr.; Marzouk, A.; Crisostomo, M.C.; Weatherby, D.R.

    1985-01-01

    A method for analysis of Ni concentrations in tissues is described, which involves (a) tissue dissection with metal-free obsidian knives, (b) tissue homogenization in polyethylene bags by use by a Stomacher blender, (c) oxidative digestion with mixed nitric, sulfuric, and perchloric acids, and (d) quantitation of Ni by electrothermal atomic absorption spectrophotometry with Zeeman background correction. The detection limit for Ni in tissues is 10 ng per g, dry weight; the coefficient of variation ranges from 7 to 15%, depending on the tissue Ni concentration; the recovery of Ni added in concentration of 20 ng per g, dry weight, to kidney homogenates averages 101 +/- 8% (mean +/-SD). In control rats, Ni concentrations are highest in lung (102 +/- 39 ng per g, dry weight) and lowest in spleen (35 +/- 16 ng per g, dry wt.). In descending order of Ni concentrations, the tissues of control rats rank as follows: lung > heart > bone > kidney > brain > testis > fat > liver > spleen. In rats killed 24 h after sc injection of NiCl/sub 2/ (0.125 mmol per kg, body weight) Ni concentrations are highest in kidney (17.7 +/- 2.5 ..mu..g per g, dry weight) and lowest in brain (0.38 +/- 0.14 ..mu..g per g, dry weight). In descending order of Ni concentrations, the tissues of NiCl/sub 2/-treated rats rank as follows: kidney >> lung > spleen > testis > heart > fat > liver > bone > brain. The present method fills the need for an accurate, sensitive, and practical technique to determine tissue Ni concentrations, with stringent precautions to minimize Ni contamination during tissue sampling and processing. 35 references, 5 figures, 1 table.

  7. Teaching Beer's Law and Absorption Spectrophotometry with a Smart Phone: A Substantially Simplified Protocol

    ERIC Educational Resources Information Center

    Kuntzleman, Thomas S.; Jacobson, Erik C.

    2016-01-01

    A very simple protocol for teaching Beer's Law and absorption spectrophotometry using a smart phone is described. Materials commonly found in high school chemistry laboratories or even around the house may be used. Data collection and analysis is quick and easy. Despite the simple nature of the experiment, excellent results can be achieved.

  8. Uranium isotopes quantitatively determined by modified method of atomic absorption spectrophotometry

    NASA Technical Reports Server (NTRS)

    Lee, G. H.

    1967-01-01

    Hollow-cathode discharge tubes determine the quantities of uranium isotopes in a sample by using atomic absorption spectrophotometry. Dissociation of the uranium atoms allows a large number of ground state atoms to be produced, absorbing the incident radiation that is different for the two major isotopes.

  9. Cinchocaine hydrochloride determination by atomic absorption spectrometry and spectrophotometry.

    PubMed

    Abdel-Ghani, Nour T; Youssef, Ahmed F A; Awady, Mohamed A

    2005-05-01

    Two sensitive spectrophotometric and atomic absorption spectrometric procedures have been developed for determination of cinchocaine hydrochloride (Cin.Cl) in pure form and in pharmaceutical formulation. The spectrophotometric method was based on formation of an insoluble colored ion-associate between the cited drug and tetrathiocyanatocobaltate (CoTC) or hexathiocyanatochromate (CrTC) which dissolved and extracted in an organic solvent. The optimal experimental conditions for quantitative extraction such as pH, concentration of the reagents and solvent were studied. Toluene and iso-butyl alcohol proved to be the most suitable solvents for quantitative extraction of Cin-CoTC and Cin-CrTC ion-associates with maximum absorbance at 620 and 555 nm, respectively. The optimum concentration ranges, molar absorptivities, Ringbom ranges and Sandell sensitivities were also evaluated. The atomic absorption spectrometric method is based on measuring of the excess cobalt or chromium in the aqueous solution, after precipitation of the drug, at 240.7 and 357.9 nm, respectively. Linear application ranges, characteristic masses and detection limits were 57.99-361.9, 50.40 and 4.22 microg ml(-1) of Cin.Cl, in case of CoTC, while 37.99-379.9, 18.94 and 0.81 microg ml(-1) in case of CrTC.

  10. Stability of low concentration calibration standards for graphite furnace atomic absorption spectrophotometry

    SciTech Connect

    Bass, D A; TenKate, L B

    1993-11-01

    Graphite furnace atomic absorption spectrophotometry (GFAAS) is used for determination of ultra-trace metals in environmentally important samples. In the generation of GFAAS calibration curves for many environmental applications, low concentration calibration standards must be prepared dally, as required by the Statement of Work (SOW) for the US Environmental Protection Agency (EPA) Contract Laboratory Program (CLP). This results in significant time and work for the analyst and significant cost to the Analytical Chemistry Laboratory (ACL) for chemicals and waste management. While EPA SW 846 is less prescriptive than the CLP SOW, ACL has been following the CLP guidelines because in-house criteria regarding the stability of GFAAS standards have not been established. A study was conducted to determine the stability of GFAAS standards for analytes commonly used in the ACL (single and mixed) as a function of time. Data were collected over nine months. The results show that GFAAS standards for Sb, Pb, Se, Ag, and TI are stable for a longer period of time than currently assumed by the CLP SOW. Reducing the frequency of preparing these standards will increase efficiency, decrease the handling of hazardous the quantity of hazardous waste generated, and decrease the quantity of hazardous substances to be ordered and stocked by the laboratory. These benefits will improve GFAAS analysis quality, reduce costs, enhance safety, and lower environmental concerns.

  11. [Determination of trace elements in new food sources by flame atomic absorption spectrophotometry].

    PubMed

    Liu, Li E; Ding, Li; Qi, Min; Han, Xiu Li; Zhang, Hong-Quan

    2007-07-01

    Samples were digested by HNO3 + HClO4. Flame atomic absorption spectrophotometry (FAAS) was successfully used to determine copper, zinc and iron in new resource food. Under our experimental conditions, the recovery ratio was 94.66%-108.80%; the precision was 0.71%-4.78%. This method of measuring elements is convenient, rapid and accurate. The results showed that there are profitable elements, such as copper, zinc and iron in new resourse food in Henan province. By F test and SNK test, the content sequence of metal elements was found as follows: copper, Chrysanthemum morifolium Ramat = Silkworm pupa > flowers of Pueraria lobata Ohwin = Wheat germ = Codonopsis lanceolata = roots of Pueraria lobata Ohwi > Opuntia dillenii Haw. Zinc, Opuntia dillenii Haw > Silkworm pupa = flowers of Pueraria lobata Ohwi = roots of Pueraria lobata Ohwi = Wheat germ = Codonopsis lanceolata = Chrysanthemum morifolium Ramat. Iron, Silkworm pupa = C hrysanthemum morifolium Ramat = roots of Pueraria lobata Ohwi > flowers of Pueraria lobata Ohwi = Wheat germ = Codonopis lanceolata = Opuntia dillenii Haw.

  12. 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.

  13. Determination of traces of silver in waters by anion exchange and atomic absorption spectrophotometry

    USGS Publications Warehouse

    Chao, T.T.; Fishman, M. J.; Ball, J.W.

    1969-01-01

    A method has been developed for the accurate determination of 0.1-1 ??g of silver per liter of water. The method permits stabilization of silver in water without loss to container walls. Optimum conditions have been established for the complete recovery of silver from water with an anion-exchange column, for quantitative elution of silver from the resin, and for measurement of silver by atomic absorption spectrophotometry after chelation with ammonium pyrrolidine dithiocarbamate and extraction of the chelate with MIBK. Silver in the 1-10 ??g 1 range can be determined by extraction without pre-concentration on an ion-exchange resin. ?? 1969.

  14. [Determination of trace Rh in organic residue by flame atomic absorption spectrophotometry].

    PubMed

    Han, Mei; Cheng, Fang; Gu, Shi-fang; Cui, Li-jun; Xiao, Guang; Xu, Song-yun

    2003-02-01

    The catalytic organic residue contained Rh was digested with HNO3 at 130 degrees C for 12 h. Trace noble metal Rh in catalytic organic residue was determined by flame atomic absorption spectrophotometry. Rh was atomized by air-acetylene flame at lamp Current of 7 mA. The methods of sample pretreatment for Rh in residue were compared in this paper. The recovery rates of this method were 95.3%-105.5% and the relative standard derivation was 0.9%. The method was applied to the analysis of some practical samples and the results obtained were satisfactory.

  15. Determination of beryllium in urine by graphite furnace atomic absorption spectrophotometry

    SciTech Connect

    Thorat, D.D.; Bhat, P.N.; Mahadevan, T.N.

    1995-08-01

    A method for the determination of beryllium in urine samples by Graphite Furnace Atomic Absorption Spectrophotometry (GFAAS) has been developed. The background correction problem due to the sample matrix was overcome by solvent extraction step. Urine samples were digested with a mixture of concentrated nitric and sulphuric acids. Beryllium in solution was complexed with acetylacetone, extracted in chloroform at pH 8.5 and back extracted in 2%(v/v) nitric acid for final analysis by AAS. The range of concentrations of beryllium observed in urine samples covering both occupational and control subject was 0.03 - 0.37 ng Be/ml.

  16. Analysis of lithium in deep basalt groundwaters using graphite furnace atomic absorption spectrophotometry

    SciTech Connect

    Dill, J.A.; Marcy, A.D.

    1986-05-01

    Lithium is under consideration for use as a reactive (sorptive) tracer in experiments designed to provide information regarding natural attenuation processes in a basalt-groundwater environment. In support of these activities, background lithium concentrations in samples obtained from a variety of test horizons have been determined using graphite furnace atomic absorption spectrophotometry. Significant interference was observed in these determinations and was found to be due to the presence of silicate in the samples. It was found that these problems could be circumvented through the use of alkaline silicate or synthetic groundwater matrix modifiers. This matrix effect was examined in some detail. Results obtained using the graphite furnace were compared to results obtained using inductively coupled plasma atomic emission spectroscopy.

  17. Removal of iron interferences by solvent extraction for geochemical analysis by atomic-absorption spectrophotometry

    USGS Publications Warehouse

    Zhou, L.; Chao, T.T.; Sanzolone, R.F.

    1985-01-01

    Iron is a common interferent in the determination of many elements in geochemical samples. Two approaches for its removal have been taken. The first involves removal of iron by extraction with methyl isobutyl ketone (MIBK) from hydrochloric acid medium, leaving the analytes in the aqueous phase. The second consists of reduction of iron(III) to iron(II) by ascorbic acid to minimize its extraction into MIBK, so that the analytes may be isolated by extraction. Elements of interest can then be determined using the aqueous solution or the organic extract, as appropriate. Operating factors such as the concentration of hydrochloric acid, amounts of iron present, number of extractions, the presence or absence of a salting-out agent, and the optimum ratio of ascorbic acid to iron have been determined. These factors have general applications in geochemical analysis by atomic-absorption spectrophotometry. ?? 1985.

  18. Determination of nickel by flame atomic-absorption spectrophotometry after separation by adsorption of its nioxime complex on microcrystalline naphthalene.

    PubMed

    Nagahiro, T; Puri, B K; Katyal, M; Satake, M

    1984-11-01

    A method has been developed for the determination of nickel in alloys by flame atomic-absorption spectrophotometry after formation of a water-insoluble complex, its adsorption on microcrystalline naphthalene, and dissolution of the complex and naphthalene in nitric acid and xylene.

  19. Separation and quantitation of metallothioneins by high-performance liquid chromatography coupled with atomic absorption spectrophotometry

    SciTech Connect

    Lehman, L.D.; Klaassen, C.D.

    1986-03-01

    A rapid, reproducible, and sensitive high-performance liquid chromatography (HPLC) method for the determination of the concentrations of metallothionein-I (MT-I) and metallothionein-II (MT-II) in rat liver has been developed. Metallothioneins (MTs) were separated and quantitated by anion-exchange high-performance liquid chromatography coupled with atomic absorption spectrophotometry (AAS). Purified rat liver MT-I and MT-II, used as standards for developing the method, were easily resolved, eluting at 7.5 and 10.4 min, respectively. To establish standard curves, protein concentrations of solutions of the purified MTs were determined by the Kjeldahl method for the determination of nitrogen, after which the standards were saturated with Cd (final concentration of 50 ppm Cd). Rat liver cytosols obtained from untreated and Cd- or Zn-treated rats were prepared for HPLC-AAS analysis by saturation with Cd (50 ppm Cd) followed by heat denaturation (placing in a boiling water bath for 1 min). Based on the method of standard additions, recovery of MTs exceeded 95% and repeated injection of a sample yielded a coefficient of variance of approximately 2%. A detection limit of 5 ..mu..g MT/g liver was established for the method. Only MT-II was detected in untreated rats, whereas following exposure to Cd or Zn, both forms of MTs were detected. Concentrations of total MTs in liver of untreated and Cd- or Zn-treated rats were also determined by the Cd/hemoglobin radioassay (which fails to distinguish MT-I from MT-II) and indicated that results obtained with the HPLC-AAS method compared favorably to the Cd/hemoglobin radioassay.

  20. Quantification of minerals and trace elements in raw caprine milk using flame atomic absorption spectrophotometry and flame photometry.

    PubMed

    Singh, Mahavir; Yadav, Poonam; Garg, V K; Sharma, Anshu; Singh, Balvinder; Sharma, Himanshu

    2015-08-01

    This study reports minerals and trace elements quantification in raw caprine milk of Beetal breed, reared in Northern India and their feed, fodder & water using flame atomic absorption spectrophotometry and flame photometry. The mineral and trace elements' concentration in the milk was in the order: K > Ca > Na > Fe > Zn > Cu. The results showed that minerals concentration in caprine milk was lesser than reference values. But trace elements concentration (Fe and Zn) was higher than reference values. Multivariate statistical techniques, viz., Pearsons' correlation, Cluster analysis (CA) and Principal component analysis (PCA) were applied to analyze the interdependences within studied variables in caprine milk. Significantly positive correlations were observed between Fe - Zn, Zn - K, Ca - Na and Ca - pH. The results of correlation matrix were further supported by Cluster analysis and Principal component analysis as primary cluster pairs were found for Ca - pH, Ca - Na and Fe - Zn in the raw milk. No correlation was found between mineral & trace elements content of the milk and feed.

  1. Determination of trace chromium in water by graphite furnace atomic absorption spectrophotometry after preconcentration on a soluble membrane filter

    SciTech Connect

    Gao Piying; Feng Ruolan; Zhang Huaizhu; Li Zhiqiang

    1998-04-01

    A new concentration and determination method has been described for the determination of lower than 0.1 {micro}g L{sup {minus}1} levels of chromium (VI) in water, based on the reaction between chromium (VI) and phenylfluorone (PF) to form an anionic chelate and the collection of the ternary ion-associate of the chelate with cetyltrimethylammonium bromide (CTMAB) (a cationic surfactant) on an organic solvent-soluble membrane filter. Determination of the solution obtained after dissolving the membrane and analyte in a suitable solvent is achieved using graphite furnace atomic absorption spectrophotometry. The ternary complex (Cr(VI)-PF-CTMAB = 1:2:2) is collected on a 0.45 {micro}m nitrocellulose filter and the filter and analyte are dissolved in a small volume of 2-methoxyethanol acidified with dilute sulfuric acid. The chromium is determined by graphite furnace atomic absorption spectrophotometry under optimum experimental conditions. A good linear relationship exists in the range 0.05--0.30 {micro}g chromium in 5.0 ml, with satisfactory reproducibility. The detection limit, defined as three times the standard deviation of the blank, is 0.06 {micro}g L{sup {minus}1} with 20 fold preconcentration. The ions normally present in water do not interfere under the experimental conditions used. The proposed method has been applied to the concentration and determination of chromium (VI) in water samples from several sources by means of direct graphic furnace atomic absorption spectrophotometry; the recoveries of chromium (VI) added to the samples are quantitative, and results found are satisfactory.

  2. Determination of silver in soils, sediments, and rocks by organic-chelate extraction and atomic absorption spectrophotometry

    USGS Publications Warehouse

    Chao, T.T.; Ball, J.W.; Nakagawa, H.M.

    1971-01-01

    A useful method for the determination of silver in soil, sediment, and rock samples in geochemical exploration has been developed. The sample is digested with concentrated nitric acid, and the silver extracted with triisooctyl thiophosphate (TOTP) in methyl isobutyl ketone (MIBK) after dilution of the acid digest to approximately 6 M. The extraction of silver into the organic extractant is quantitative and not affected by the nitric acid concentration from 4 M to 8 M, or by different volumes of TOTP-MIBK. The extracted silver is stable and remains in the organic phase up to several days. The silver concentration is determined by atomic absorption spectrophotometry. ?? 1971.

  3. [Study on determination of trace nitrite and reaction mechanism by two-wavelength negative absorption-catalytic spectrophotometry].

    PubMed

    Zi, Yan-qin; Lu, Hao-miao

    2006-01-01

    A new method was proposed for the determination of trace nitrite by two wavelength negative absorption catalytic spectrophotometry based on the catalysis of nitrite on the oxidation fading reaction of acridine orange by potassium bromate in phosphoricacid medium. The additive value of negative absorbances at two wavelengths was linear to the nitrite concentration in the range of 1.0 x 10(-5)-5.0 x 10(-7) mol x L(1). The method has been used to the determination of nitrite in environment water sample with satisfactory

  4. An international evaluation of holmium oxide solution reference materials for wavelength calibration in molecular absorption spectrophotometry.

    PubMed

    Travis, John C; Zwinkels, Joanne C; Mercader, Flora; Ruíz, Arquímedes; Early, Edward A; Smith, Melody V; Noël, Mario; Maley, Marissa; Kramer, Gary W; Eckerle, Kenneth L; Duewer, David L

    2002-07-15

    Commercial spectrophotometers typically use absorption-based wavelength calibration reference materials to provide wavelength accuracy for their applications. Low-mass fractions of holmium oxide (Ho2O3) in dilute acidic aqueous solution and in glass matrixes have been favored for use as wavelength calibration materials on the basis of spectral coverage and absorption band shape. Both aqueous and glass Ho2O3 reference materials are available commercially and through various National Metrology Institutes (NMIs). Three NMIs of the North American Cooperation in Metrology (NORAMET) have evaluated the performance of Ho3-(aq)-based Certified Reference Materials (CRMs) under "routine" operating conditions using commercial instrumentation. The study was not intended to intercompare national wavelength scales but to demonstrate comparability of wavelength measurements among the participants and between two versions of the CRMs. It was also designed to acquire data from a variety of spectrophotometers for use in a NIST study of wavelength assignment algorithms and to provide a basis for a possible reassessment of NIST-certified Ho3+(aq) band locations. The resulting data show a substantial level of agreement among laboratories, instruments, CRM preparations, and peak-location algorithms. At the same time, it is demonstrated that the wavelength comparability of the five participating instruments can actually be improved by calibrating all of the instruments to the consensus Ho3+(aq) band locations. This finding supports the value of absorption-based wavelength standards for calibrating absorption spectrophotometers. Coupled with the demonstrated robustness of the band position values with respect to preparation and measurement conditions, it also supports the concept of extending the present approach to additional NMIs in order to certify properly prepared dilute acidic Ho2O3 solution as an intrinsic wavelength standard.

  5. 25. View down launch tube, showing shock absorption system. Lyon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. View down launch tube, showing shock absorption system. Lyon - Whiteman Air Force Base, Minuteman Missile Launch Facility Trainer T-12, Northeast of Oscar-01 Missile Alert Facility, Knob Noster, Johnson County, MO

  6. Simultaneous Determination of Ofloxacin and Flavoxate Hydrochloride by Absorption Ratio and Second Derivative UV Spectrophotometry

    PubMed Central

    Attimarad, Mahesh

    2010-01-01

    The objective of this study was to develop simple, precise, accurate and sensitive UV spectrophotometric methods for the simultaneous determination of ofloxacin (OFX) and flavoxate HCl (FLX) in pharmaceutical formulations. The first method is based on absorption ratio method, by formation of Q absorbance equation at 289 nm (λmax of OFX) and 322.4 nm (isoabsorptive point). The linearity range was found to be 1 to 30 μg/ml for FLX and OFX. In the method-II second derivative absorption at 311.4 nm for OFX (zero crossing for FLX) and at 246.2 nm for FLX (zero crossing for OFX) was used for the determination of the drugs and the linearity range was found to be 2 to 30 μg/ml for OFX and 2-75 μg /ml for FLX. The accuracy and precision of the methods were determined and validated statistically. Both the methods showed good reproducibility and recovery with % RSD less than 1.5%. Both the methods were found to be rapid, specific, precise and accurate and can be successfully applied for the routine analysis of OFX and FLX in combined dosage form PMID:24826003

  7. Determination of Pb in Biological Samples by Graphite Furnace Atomic Absorption Spectrophotometry: An Exercise in Common Interferences and Fundamental Practices in Trace Element Determination

    ERIC Educational Resources Information Center

    Spudich, Thomas M.; Herrmann, Jennifer K.; Fietkau, Ronald; Edwards, Grant A.

    2004-01-01

    An experiment is conducted to ascertain trace-level Pb in samples of bovine liver or muscle by applying graphite furnace atomic absorption spectrophotometry (GFAAS). The primary objective is to display the effects of physical and spectral intrusions in determining trace elements, and project the usual methods employed to minimize accuracy errors…

  8. [Simultaneous determination of cobalt and nickel in catalyst by microwave digestion-dual wavelength equal absorption spectrophotometry].

    PubMed

    Li, L; Zhang, J; Gao, C

    2001-08-01

    Catalyst samples are digested in a microwave digestion system. The optimum parameters for microwave digestion are selected. Cobalt and nickel in the mixture of Co2+ and Ni2+ with 4-(2-pyridylazo) resorcinol (PAR) can be determined simultaneously by dual-wavelength equal absorption spectrophotometry. By means of the combination of two methods, Co2+ and Ni2+ in catalyst can be determined rapidly, accurately, and contamination problems avoided. The linear ranges are 0-30 micrograms.25 mL-1 for Co2+ and 0-25 micrograms.25 mL-1 for Ni2+. The recoveries of Co2+ and Ni2+ in synthetic samples are between 98.2%-103.6% and between 97.9%-103.7%, respectively. The relative standard deviations of analytical results in catalyst samples are less than 2.2% for Co2+ and less than 1.8% for Ni2+, and relative errors are less than +/- 2.5% for Co2+ and Ni2+.

  9. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of antimony by automated-hydride atomic absorption spectrophotometry

    USGS Publications Warehouse

    Brown, G.E.; McLain, B.J.

    1994-01-01

    The analysis of natural-water samples for antimony by automated-hydride atomic absorption spectrophotometry is described. Samples are prepared for analysis by addition of potassium and hydrochloric acid followed by an autoclave digestion. After the digestion, potassium iodide and sodium borohydride are added automatically. Antimony hydride (stibine) gas is generated, then swept into a heated quartz cell for determination of antimony by atomic absorption spectrophotometry. Precision and accuracy data are presented. Results obtained on standard reference water samples agree with means established by interlaboratory studies. Spike recoveries for actual samples range from 90 to 114 percent. Replicate analyses of water samples of varying matrices give relative standard deviations from 3 to 10 percent.

  10. Development of mixed-waste analysis capability for graphite furnace atomic absorption spectrophotometry

    SciTech Connect

    Bass, D.A.; TenKate, L.B.; Wroblewski, A.

    1995-03-01

    Graphite furnace atomic absorption spectrophotometer (GFAAS) are typically configured with ventilation to capture potentially toxic and corrosive gases emitted from the vaporization of sample aliquots. When radioactive elements are present, additional concerns (such as meeting safety guidelines and ALARA principles) must be addressed. This report describes a modification to a GFAAS that provides additional containment of vaporized sample aliquots. The modification was found to increase containment by a factor of 80, given expected operating conditions. The use of the modification allows more mixed-waste samples to be analyzed, permits higher levels of radioactive samples to be analyzed, or exposes the analyst to less airborne radioactivity. The containment apparatus was attached to a Perkin-Elmer Zeeman 5000 spectrophotometer for analysis of mixed-waste samples; however, it could also be used on other systems and in other applications where greater containment of vaporized material is desired.

  11. Determination of soluble aluminium concentration in alkaline humic water using atomic absorption spectrophotometry.

    PubMed

    Nguyen, K L; Lewis, D M; Jolly, M; Robinson, J

    2004-11-01

    The steps of the standard method to determine soluble aluminium concentration are filtering, followed by acidifying, then analysing with the atomic absorption spectrophotometer (AAS). When applied to alkaline humic water, acidification gives rise to the formation of humic acid as a brown particulate matter. Of the total soluble aluminium in the original water, 49-61% forms complexes with the particulate humic acid upon acidification. Although the AAS is capable of detecting the binding aluminium, the particulate nature of humic acid easily induces inaccurate readings as a result of the non-uniform distribution of the particulate matter. A more precise analysis of soluble aluminium concentration of alkaline humic water is shown to be achievable in basicified solutions instead. Basicified solutions keep humic acid in the soluble form; hence maintain the homogeneity of the sample.

  12. Measurement of aluminum in neuronal tissues using electrothermal atomization atomic absorption spectrophotometry

    SciTech Connect

    Pierson, K.B.; Evenson, M.A.

    1986-07-01

    Studies characterizing aluminum complexes isolated from neuronal tissues require accurate and precise techniques for aluminum measurement. A solution of 0.01 M nitric acid containing 0.2% Triton X-100 was the optimal diluent for aluminum measurement under the experimental conditions used. Three National Bureau of Standards Standard Reference Materials (SRM) were digested, and the aluminum concentration of each was measured with a Perkin-Elmer 503 atomic absorption spectrophotometer equipped with a Perkin-Elmer HGA 2100 controller. The calculated detection limit of aluminum was 120 pg using 15-..mu..L sample injections (8 ..mu..g/L). Aluminum concentrations present in citrus leaves (SRM 1572), pine needles (SRM 1575), and tomato leaves (SRM 1573) were 100 +- 12 (certified value, 92 +- 15), 522 +- 45 (certified value, 454 +- 30), and 1273 +- 112 (provisional value, 1200) ..mu..g/g, respectively. The within- and between-day precision had coefficients of variation for citrus leaves, pine needles, and tomato leaves of 18 and 12%, 6.3 and 8.6%, and 3.7 and 8.7%, respectively. Aluminum absorbance was enhanced at high pH values and by zinc.

  13. Determination of selenium in human spermatozoa and prostasomes using base digestion and electrothermal atomic absorption spectrophotometry.

    PubMed

    Suistomaa, U; Saaranen, M; Vanha-Perttula, T

    1987-10-15

    A method for the determination of selenium in human spermatozoa and prostasomes is described. The samples were digested with 25% (w/v) tetramethylammonium hydroxide (TMAH) in methanol and analyzed by atomic absorption spectrometry with electrothermal atomization and Zeeman background correction (ET-AAS). Nickel was used as a matrix modifier. Calibration was performed using the matrix-based calibration curve. The TMAH-digestion method agreed well with a conventional digestion procedure using concentrated nitric acid. The TMAH-digestion does not require heating or strong acids and it was suitable for small biological samples. The average recovery of added selenium in spermatozoan digests was 95.1 +/- 5.2% (n = 5). The coefficient of variation was 9.1% (n = 21). The accuracy of the method tested with the NBS standard 1577 (bovine liver, certified at 1.1 +/- 0.1 micrograms Se/g) resulted in a value of 0.98 +/- 0.10 micrograms Se/g (n = 16). The method was further tested in an interlaboratory comparison study.

  14. [Microanalysis of serum iron by atomatic absorption spectrophotometry in a graphite oven: improvement and evaluation of this method].

    PubMed

    Favier, A; Maljournal, B; Decoux, G; Ruffieux, D

    1983-01-01

    We describe a method of micro-assay of serum iron by atomic absorption without flame, after deproteinisation of the serum by molar hydrochloric acid. In this way, we can assay the serum iron in 10 microliters of serum by injection of the supernatant into a graphite oven. The results show a good correlation with those obtained by conventional techniques of atomic absorption and colorimetric assays using ferrozine and bathophenanthroline. However, great care must be taken in the cleaning of plastic test tubes.

  15. Sample preparation in determination of lead in garden vegetables by flame atomic absorption spectrophotometry.

    PubMed

    Preer, J R; Stephens, B R; Bland, C W

    1982-07-01

    Dry and wet ashing methods have been used in the analysis of garden vegetables for Pb. The reliability of wet ashing has been verified by the method of standard additions. Comparison of dry and wet ashing showed good agreement for a variety of garden vegetables. Sample size was more strictly limited for the wet-ashed samples, which led to lower sensitivity. Vegetable samples are commonly analyzed for a number of trace elements, which introduces additional constraints on sample preparation, notably because of Cd loss on dry ashing. Pretreatment with HNO3/H2SO4 ash aid eliminated Cd loss. Reliability of dry ashing with pretreatment was shown with NBS SRM Orchard Leaves, Pine Needles, Spinach, and Tomato Leaves. The analysis was insensitive to ashing temperature in the range 480-625 degrees C. A practical detection limit for the method is about 2 ppm Pb, dry weight basis (DWB). Care must be exercised to avoid contamination of the sample with lead at this level by improper handling. Segregation and acid washing of glassware and protection of the sample from contact with any object not demonstrably clean was necessary. No evidence was found of Pb contamination at this level from tap water washing of fresh vegetables, forced-air oven drying, or grinding with mortar and pestle. No special clean room facilities or laboratory air purification measures were used. Sensitivity was increased 3-fold by extraction with dithizone in CHCl3 followed by back-extraction into dilute HCl. Detection limits were not improved, however, because of variation in the extraction results. The instrumental method for assessing effective correction for back-ground absorbance showed adequate compensation, although comparison of direct and extractive determinations showed a small but significant difference between the methods of about 1 ppm Pb (DWB).

  16. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of chromium in water by graphite furnace atomic absorption spectrophotometry

    USGS Publications Warehouse

    McLain, B.J.

    1993-01-01

    Graphite furnace atomic absorption spectrophotometry is a sensitive, precise, and accurate method for the determination of chromium in natural water samples. The detection limit for this analytical method is 0.4 microg/L with a working linear limit of 25.0 microg/L. The precision at the detection limit ranges from 20 to 57 percent relative standard deviation (RSD) with an improvement to 4.6 percent RSD for concentrations more than 3 microg/L. Accuracy of this method was determined for a variety of reference standards that was representative of the analytical range. The results were within the established standard deviations. Samples were spiked with known concentrations of chromium with recoveries ranging from 84 to 122 percent. In addition, a comparison of data between graphite furnace atomic absorption spectrophotometry and direct-current plasma atomic emission spectrometry resulted in suitable agreement between the two methods, with an average deviation of +/- 2.0 microg/L throughout the analytical range.

  17. Temperatures of galactic molecular clouds showing CO self-absorption

    NASA Technical Reports Server (NTRS)

    Phillips, T. G.; Knapp, G. R.; Wannier, P. G.; Huggins, P. J.; Werner, M. W.; Neugebauer, G.; Ennis, D.

    1981-01-01

    The CO J = 2-1 line has been observed and, in most cases, mapped in 10 star-forming molecular clouds (W3, NGC 1333, NGC 2071, Mon R2, CRL 961, Rho Oph, W49N, W51A, DR 21, and Cep A). The CO J = 3-2 line has been observed in W3 and DR 21. The CO lines from all these sources are strongly self-absorbed. By comparing the present results with published CO(1-0) line profiles, it is found that large corrections to the temperatures of the cloud cores, as measured by the CO(1-0) lines, are required. The corrections for self-absorption bring the CO brightness temperatures into closer agreement with the grain temperatures inferred from far-IR photometry.

  18. Optothermistor as a breakthrough in the quantification of lycopene content of thermally processed tomato-based foods: verification versus absorption spectrophotometry and high-performance liquid chromatography.

    PubMed

    Bicanic, Dane; Swarts, Jan; Luterotti, Svjetlana; Helander, Per; Fogliano, Vincenzo; Anese, Monica

    2005-05-04

    This study reports on the first use of the "optothermistor" as a novel, precise, fast, and low-cost detector of lycopene in a wide range of commercially available processed-tomato products. The quantitative performance of the new device was evaluated by comparing data obtained to that acquired by conventional methods, namely, absorption spectrophotometry and high-performance liquid chromatography (HPLC); the linear correlation was high (R = 0.98). The variation of data obtained with the optothermistor in a series of consecutive measurements performed with the same loading of the sample was better than 1%. However, the repeatability (RSD 0.5-9.0%, n = 3-5) achieved with the optothermistor by independent analyses (multiple loading) is comparable to that of HPLC and spectrophotometry. Results of the studies performed on the 19 products derived from tomatoes demonstrated that the optothermistor is suitable for selective, accurate, precise, and simple determination of lycopene (range = 7-75 mg/100 g of product weight) without the need for a sample pretreatment step. The estimated sensitivity of the present optothermistor is 2 mg of lycopene/100 g of product.

  19. Extraction and preconcentration of selenium from aqueous solutions and its determination in water and hair samples by atomic-absorption spectrophotometry.

    PubMed

    Ejaz, M; Qureshi, M A

    1987-03-01

    Several organic solvents, including benzene, xylene, toluene, nitrobenzene, chloroform, carbon tetrachloride, chlorobenzene and high molecular-weight pyridines such as 4-(5-nonyl)pyridine, 2-hexyl-pyridine and benzylpyridine have been investigated as components of systems for the extraction and preconcentration of selenium from nitric acid solutions containing iodide. The results are discussed in terms of choice of reagents and the acid and iodide concentrations, and of several other parameters affecting the extraction. The utility of the method for separation of selenium from aqueous solution has been evaluated. The method has been used for preconcentration of trace levels of selenium from water and hair samples for determination by atomic-absorption spectrophotometry.

  20. Determination of molybdenum in ores, iron and steel by atomic-absorption spectrophotometry after separation by alpha-benzoinoxime extraction or further xanthate extraction.

    PubMed

    Donaldson, E M

    1980-02-01

    A simple and moderately rapid method for determining 0.001% or more of molybdenum in ores, iron and steel is described. After sample decomposition, molybdenum is separated from the matrix elements, except tungsten, by chloroform extraction of its alpha-benzoinoxime complex from a 1.75 M hydrochloric-0.13 M tartaric acid medium. Depending on the amount of tungsten present, molybdenum, if necessary, is back-extracted into concentrated ammonia solution and subsequently separated from coextracted tungsten by chloroform extraction of its xanthate complex from a 1.5M hydrochloric-0.13M tartaric acid medium. It is ultimately determined by atomic-absorption spectrophotometry, at 313.3 nm, in a 15% v/v hydrochloric acid medium containing 1,000 microg/ml of aluminium as the chloride, after evaporation of either extract to dryness with nitric, perchloric and sulphuric acids and dissolution of the salts in dilute ammonia solution.

  1. Ultrasound-assisted pseudodigestion for toxic metals determination in fish muscles followed by electrothermal atomic absorption spectrophotometry: multivariate strategy.

    PubMed

    Arain, Mohammad B; Kazi, Tasneem G; Jamali, Mohammad K; Afridi, Hassan I; Jalbani, Nusrat; Memon, Attique R

    2007-01-01

    A simple and efficient procedure for the determination of arsenic (As), cadmium (Cd), and lead (Pb) in the edible parts of freshwater fish by ultrasonic-assisted acid pseudodigestion (USD) was developed. A Plackett-Burman experimental design was used as a multivariate strategy for the evaluation of the effects of several variables at once. Five variables--sonication time, sample mass of muscle tissue, temperature of the ultrasonic bath, mL of nitric acid, and mL of a mixture of acid and oxidant--were regarded as factors. From these studies, certain variables showed up as significant, and they were optimized by a 23+star central composite design, which involved 16 experiments. Optimum values of the variables were selected for the development of USD to determine the contents of As, Cd, and Pb in fish muscles used as pollution bioindicators from Lake Manchar (Sindh, Pakistan). The determination of the 3 toxic metals under study was performed by electrothermal atomic absorption spectrometry. The accuracy of the optimized procedure was evaluated by analysis of certified reference materials BCR 185R bovine liver and by comparison with conventional wet acid digestion methodology. The result obtained by the optimized method showed good agreement with the certified values and sufficiently high recovery. No significant differences were observed for P = 0.05. Relative standard deviation values (average of 10 separate determinations) were 1.21, 5.52, and 5.32% for As, Cd, and Pb, respectively.

  2. Determination of Copper by Graphite Furnace Atomic Absorption Spectrophotometry: A Student Exercise in Instrumental Methods of Analysis.

    ERIC Educational Resources Information Center

    Williamson, Mark A.

    1989-01-01

    Discusses a student exercise which requires the optimizing of the charring and atomization temperatures by producing a plot of absorbance versus temperature for each temperature parameter. Notes that although the graphite furnace atomic absorption spectroscopy technique has widespread industrial use, there are no published, structured experiments…

  3. Matrix effects on the determination of manganese in geological materials by atomic-absorption spectrophotometry under different flame conditions

    USGS Publications Warehouse

    Sanzolone, R.F.; Chao, T.T.

    1978-01-01

    Suppression caused by five of the seven matrix elements studied (Si, Al, Fe, Ca and Mg) was observed in the atomic-absorption determination of manganese in geological materials, when synthetic solutions and the recommended oxidizing air-acetylene flame were used. The magnitude of the suppression effects depends on (1) the kind and concentration of the interfering elements, (2) the type of acid medium, and (3) the concentration of manganese to be determined. All interferences noted are removed or alleviated by using a reducing nitrous oxide-acetylene flame. The atomic-absorption method using this flame can be applied to the determination of total and extractable manganese in a wide range of geological materials without interferences. Analyses of six U.S. Geological Survey rock standards for manganese gave results in agreement with the reported values. ?? 1978.

  4. Determination of tin in ores, iron, steel and non-ferrous alloys by atomic-absorption spectrophotometry after separation by extraction as the iodide.

    PubMed

    Donaldson, E M

    1980-06-01

    A simple and moderately rapid method for determining 0.001% or more of tin in ores, concentrates and tailings, iron, steel and copper-, zinc-, aluminium-, titanium- and zirconium-base alloys is described. After sample decomposition, tin is separated from the matrix elements, except arsenic, by toluene extraction of its iodide from a 3M sulphuric acid-1.5M potassium iodide medium containing tartaric and ascorbic acids. It is finally back-extracted into a nitric-sulphuric acid solution containing hydrochloric acid to prevent the formation of an insoluble tin-arsenic compound and the resultant solution is evaporated to dryness. Tin is subsequently determined by atomic-absorption spectrophotometry in a nitrous oxide-acetylene flame, at 235.4 nm in a 10% hydrochloric-0.5% tartaric acid medium containing 250 mug of potassium per ml. Co-extracted arsenic does not interfere. Results obtained by this method are compared with those obtained spectrophotometrically with gallein after the separation of tin by iodide extraction.

  5. Does the prior application of the field kit bullet hole testing kit 3 on a suspected bullet hole bias the analysis of atomic absorption spectrophotometry?

    PubMed

    Seltenhammer, Monika H; Fitzl, Christine; Wieser, Ingo; Binder, Reinhard; Paula, Pia; Risser, Daniele U

    2014-09-01

    Forensic ballistics is the study of bullet trajectory and consists of determining gunshot residue (GSR) to identify bullet holes. Among several highly sensitive methods, atomic absorption spectrophotometry (AAS) is employed to analyze GSR in the laboratory. However, it is sometimes necessary to identify bullet holes immediately at a crime scene. The purpose of this examination was to determine whether the use of the field test Bullet Hole Testing Kit 3 (BTK3) on a suspected bullet hole would influence the outcome of AAS-analysis: Three commonly encountered firearms (Glock17, Tokarev, and Colt) were fired at skin, wood, and cloth. AAS-analysis was performed with and without previous BTK3 application. The results clearly indicate that there is no significant interaction on the grounds of BTK3 use (BTK3 vs. no-BTK3 [kit_nokit] [Pb: p = 0.1309; Sb: p = 0.9111], material*kit_nokit [Pb: p = 0.5960; Sb: p = 0.9930], distance*kit_nokit [Pb: p = 0.4014; Sb: p = 0.9184], and firearm type*kit_nokit [Pb: p = 0.9662; Sb: p = 0.9885]); hence, applying this field kit does not falsify later AAS outcomes.

  6. Optimisation of Direct Copper Determination in Human Breast Milk Without Digestion by Zeeman Graphite Furnace Atomic Absorption Spectrophotometry with Two Chemical Modifiers.

    PubMed

    Pineau, Alain; Fauconneau, Bernard; Marrauld, Annie; Lebeau, Alexandra; Hankard, Regis; Guillard, Olivier

    2015-08-01

    Milk is an important food in the human diet, and copper (Cu) in human milk is indispensable to children's normal growth and development. It is consequently important that Cu deficiency, occurring in malnourished women or in malabsorption following bariatric surgery, be prevented. The objective of this work is to provide hospital-based paediatricians with a tool enabling rapid measurement of Cu in human breast milk through a technique that biology laboratories can easily apply. Using electrothermal atomic absorption spectrophotometry with Zeeman correction, we have optimized this method with two chemical modifiers and without digestion for analytical procedure. Detection limits and quantification limits for Cu in human milk were found to be 0.077 and 0.26 μmol/L, respectively. Within-run (n = 30) and between-run (n = 15) variations in a pool of human milk samples were 1.50 and 3.62%, respectively. Average recoveries ranged from 98.67 to 100.61%. The reliability of this method was also confirmed by analysing certified reference material (10%). In breast milk samples collected from 100 lactating mothers, Cu mean (±1 SD) was 7.09 ± 1.60 μmol/L. In conclusion, with minimal preparation and quick determination, the method proposed is suitable for measurement of Cu in human breast milk.

  7. Rapid determination of zinc and iron in foods by flow-injection analysis with flame atomic-absorption spectrophotometry and slurry nebulization.

    PubMed

    de Andrade, J C; Strong, F C; Martin, N J

    1990-07-01

    A rapid method of determining zinc and iron in food by flame atomic-absorption spectrophotometry with slurry nebulization into an air-acetylene flame has been developed. A V-groove, clog-free Babington-type nebulizer, coupled to a single-line flow-injection analysis (FIA) system, was employed to introduce the slurry into the spray chamber. Under the FIA conditions described, an injection frequency of 120/hr is possible, with negligible carry-over and memory effects. The calibration graphs were obtained by using various concentrations (up to 0.1 g/ml) of white bean homogenate as standards, rather than solutions. The method has been applied to various kinds of foods, including grains, vegetables, fruits and sausage. Homogenization of semi-prepared samples to form slurries took only 4 min. Relative deviations between results by the slurry and solution methods for both elements averaged 2-3%. Detection limits by the slurry method were 0.3 mug/ml Zn and 0.6 mug/ml Fe.

  8. Determination of chromium in ores, rocks and related materials, iron, steel and non-ferrous alloys by atomic-absorption spectrophotometry after separation by tribenzylamine-chloroform extraction.

    PubMed

    Donaldson, E M

    1980-10-01

    A method for determining trace and moderate amounts of chromium in ores, concentrates, rocks, soils and clays is described. After fusion of the sample with sodium peroxide, the melt is dissolved in dilute sulphuric acid. The chromium(III) produced by the hydrogen peroxide formed is co-precipitated with hydrous ferric oxide. The precipitate is dissolved in 0.7M sulphuric acid and chromium oxidized to chromium(VI) with ceric ammonium sulphate. The chromium(VI) is extracted as an ion-association complex into chloroform containing tribenzylamine and stripped with ammoniacal hydrogen peroxide. This solution is acidified with perchloric acid and chromium determined by atomic-absorption spectrophotometry in an air-acetylene flame, at 357.9 nm. Barium and strontium do not interfere. The procedure is also applicable to iron and steel, and nickel-copper, aluminium and zirconium alloys. Up to 5 mg of manganese and 10 mg each of molybdenum and vanadium will not interfere. In the absence of vanadium, up to 10 mg of tungsten will not interfere. In the presence of 1 mg of vanadium, up to 1 mg of tungsten will not interfere.

  9. Graphite furnace atomic absorption spectrophotometry--a novel method to quantify blood volume in experimental models of intracerebral hemorrhage.

    PubMed

    Kashefiolasl, Sepide; Foerch, Christian; Pfeilschifter, Waltraud

    2013-02-15

    Intracerebral hemorrhage (ICH) accounts for 10% of all strokes and has a significantly higher mortality than cerebral ischemia. For decades, ICH has been neglected by experimental stroke researchers. Recently, however, clinical trials on acute blood pressure lowering or hyperacute supplementation of coagulation factors in ICH have spurred an interest to also design and improve translational animal models of spontaneous and anticoagulant-associated ICH. Hematoma volume is a substantial outcome parameter of most experimental ICH studies. We present graphite furnace atomic absorption spectrophotometric analysis (AAS) as a suitable method to precisely quantify hematoma volumes in rodent models of ICH.

  10. Comparison of Adsorbed Mercury Screening Method With Cold-Vapor Atomic Absorption Spectrophotometry for Determination of Mercury in Soil

    NASA Technical Reports Server (NTRS)

    Easterling, Donald F.; Hovanitz, Edward S.; Street, Kenneth W.

    2000-01-01

    A field screening method for the determination of elemental mercury in environmental soil samples involves the thermal desorption of the mercury from the sample onto gold and then the thermal desorption from the gold to a gold-film mercury vapor analyzer. This field screening method contains a large number of conditions that could be optimized for the various types of soils encountered. In this study, the conditions were optimized for the determination of mercury in silty clay materials, and the results were comparable to the cold-vapor atomic absorption spectrophotometric method of determination. This paper discusses the benefits and disadvantages of employing the field screening method and provides the sequence of conditions that must be optimized to employ this method of determination on other soil types.

  11. Determination of boron in silicon-doped gallium arsenide by electrothermal atomic absorption spectrometry and ultraviolet-visible spectrophotometry.

    PubMed

    Taddia, Marco; Cerroni, Maria Grazia; Morelli, Elio; Musiani, Andrea

    2002-01-01

    Two methods have been developed for the determination of boron impurities in silicon-doped gallium arsenide (GaAs) for electronics. The first method employs the electrothermal atomic absorption spectrometry (ETAAS), the second, the UV-Vis molecular absorption spectrophotomety. In both cases the GaAs sample is decomposed with aqua regia (1+1). To prevent Ga(III) interference on the ETAAS determination of boron, a double extraction of the chlorogallic acid (HGaCl4) in diethyl ether is performed. To improve the overall ETAAS performance, the graphite tubes were pre-treated with iridium(III) and tungsten(IV). A mixed chemical modifier containing Ni(II), Sr(II) and citric acid was also used. The characteristic mass (m0) is 301 +/- 47 pg and the detection limit (3sB) is 2.4 microg g(-1). The classic UV-Vis spectrophotometric procedure using curcumin was also extended to the determination of boron in GaAs. By masking Ga(III) with EDTA and a preliminary extraction of boron with 2-ethyl-hexane 1,3-diol, performed on a semi-micro scale, a detection limit of 0.6 microg g(-1) was achieved. Both methods were applied to the analysis of two Si-doped GaAs samples which were suspected of being boron-contaminated. Results are compared with those obtained by direct analysis of the decomposed sample solution using the inductively coupled plasma atomic emission spectrometry (ICP-AES).

  12. Determination of total tin in geological materials by electrothermal atomic-absorption spectrophotometry using a tungsten-impregnated graphite furnace

    USGS Publications Warehouse

    Zhou, L.; Chao, T.T.; Meier, A.L.

    1984-01-01

    An electrothermal atomic-absorption spectrophotometric method is described for the determination of total tin in geological materials, with use of a tungsten-impregnated graphite furnace. The sample is decomposed by fusion with lithium metaborate and the melt is dissolved in 10% hydrochloric acid. Tin is then extracted into trioctylphosphine oxide-methyl isobutyl ketone prior to atomization. Impregnation of the furnace with a sodium tungstate solution increases the sensitivity of the determination and improves the precision of the results. The limits of determination are 0.5-20 ppm of tin in the sample. Higher tin values can be determined by dilution of the extract. Replicate analyses of eighteen geological reference samples with diverse matrices gave relative standard deviations ranging from 2.0 to 10.8% with an average of 4.6%. Average tin values for reference samples were in general agreement with, but more precise than, those reported by others. Apparent recoveries of tin added to various samples ranged from 95 to 111% with an average of 102%. ?? 1984.

  13. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of low-level silver by graphite furnace atomic absorption spectrophotometry

    USGS Publications Warehouse

    Damrau, D.L.

    1993-01-01

    Increased awareness of the quality of water in the United States has led to the development of a method for determining low levels (0.2-5.0 microg/L) of silver in water samples. Use of graphite furnace atomic absorption spectrophotometry provides a sensitive, precise, and accurate method for determining low-level silver in samples of low ionic-strength water, precipitation water, and natural water. The minimum detection limit determined for low-level silver is 0.2 microg/L. Precision data were collected on natural-water samples and SRWS (Standard Reference Water Samples). The overall percent relative standard deviation for natural-water samples with silver concentrations more than 0.2 microg/L was less than 40 percent throughout the analytical range. For the SRWS with concentrations more than 0.2 microg/L, the overall percent relative standard deviation was less than 25 percent throughout the analytical range. The accuracy of the results was determined by spiking 6 natural-water samples with different known concentrations of the silver standard. The recoveries ranged from 61 to 119 percent at the 0.5-microg/L spike level. At the 1.25-microg/L spike level, the recoveries ranged from 92 to 106 percent. For the high spike level at 3.0 microg/L, the recoveries ranged from 65 to 113 percent. The measured concentrations of silver obtained from known samples were within the Branch of Quality Assurance accepted limits of 1 1/2 standard deviations on the basis of the SRWS program for Inter-Laboratory studies.

  14. Measuring Cation Transport by Na,K- and H,K-ATPase in Xenopus Oocytes by Atomic Absorption Spectrophotometry: An Alternative to Radioisotope Assays

    PubMed Central

    Dürr, Katharina L.; Tavraz, Neslihan N.; Spiller, Susan; Friedrich, Thomas

    2013-01-01

    Whereas cation transport by the electrogenic membrane transporter Na+,K+-ATPase can be measured by electrophysiology, the electroneutrally operating gastric H+,K+-ATPase is more difficult to investigate. Many transport assays utilize radioisotopes to achieve a sufficient signal-to-noise ratio, however, the necessary security measures impose severe restrictions regarding human exposure or assay design. Furthermore, ion transport across cell membranes is critically influenced by the membrane potential, which is not straightforwardly controlled in cell culture or in proteoliposome preparations. Here, we make use of the outstanding sensitivity of atomic absorption spectrophotometry (AAS) towards trace amounts of chemical elements to measure Rb+ or Li+ transport by Na+,K+- or gastric H+,K+-ATPase in single cells. Using Xenopus oocytes as expression system, we determine the amount of Rb+ (Li+) transported into the cells by measuring samples of single-oocyte homogenates in an AAS device equipped with a transversely heated graphite atomizer (THGA) furnace, which is loaded from an autosampler. Since the background of unspecific Rb+ uptake into control oocytes or during application of ATPase-specific inhibitors is very small, it is possible to implement complex kinetic assay schemes involving a large number of experimental conditions simultaneously, or to compare the transport capacity and kinetics of site-specifically mutated transporters with high precision. Furthermore, since cation uptake is determined on single cells, the flux experiments can be carried out in combination with two-electrode voltage-clamping (TEVC) to achieve accurate control of the membrane potential and current. This allowed e.g. to quantitatively determine the 3Na+/2K+ transport stoichiometry of the Na+,K+-ATPase and enabled for the first time to investigate the voltage dependence of cation transport by the electroneutrally operating gastric H+,K+-ATPase. In principle, the assay is not limited to K

  15. Nile blue shows its true colors in gas-phase absorption and luminescence ion spectroscopy

    NASA Astrophysics Data System (ADS)

    Stockett, M. H.; Houmøller, J.; Brøndsted Nielsen, S.

    2016-09-01

    Nile blue is used extensively in biology as a histological stain and fluorescent probe. Its absorption and emission spectra are strongly solvent dependent, with variations larger than 100 nm. The molecule is charged due to an iminium group, and it is therefore an obvious target for gas-phase ion spectroscopy. Here we report the absorption and emission spectra of the mass-selected bare ions isolated in vacuo, and based on our results we revisit the interpretation of solution-phase spectra. An accelerator mass spectrometer was used for absorption spectroscopy where the absorption is represented by the yield of photofragment ions versus excitation wavelength (action spectroscopy). The luminescence experiments were done with a newly built ion trap setup equipped with an electrospray ion source, and some details on the mass selection technique will be given which have not been described before. In vacuo, the absorption and emission maxima are at 580 ± 10 nm and 628 ± 1 nm. These values are somewhat blue-shifted relative to those obtained in most solvents; however, they are much further to the red than those in some of the most non-polar solvents. Furthermore, the Stokes shift in the gas phase (1300 cm-1) is much smaller than that in these non-polar solvents but similar to that in polar ones. An explanation based on charge localization by solvent dipoles, or by counterions in some non-polar solvents, can fully account for these findings. Hence in the case of ions, it is nontrivial to establish intrinsic electronic transition energies from solvatochromic shifts alone.

  16. Tables showing analyses of semiquantitative spectrometry and atomic-absorption spectrophotometry of rock samples collected in the Ugashik, Bristol Bay, and western part of the Karluk quadrangles, Alaska

    USGS Publications Warehouse

    Wilson, Frederic H.; O'Leary, Richard M.

    1987-01-01

    The accompanying tables list chemical analyses of 337 rock samples that were collected in 1979, 1980, and 1981 in conjunction with geologic mapping in the Ugashik, Bristol Bay, and part of Karluk quadrangles. This work was conducted under the auspices of the Alaska Mineral Resource Assessment Program (AMRAP). This report is to accompany Wilson and O'Leary (1986) which inadvertently is missing most of the data tables listed here. Together the two reports contain the complete data from all samples collected for the Ugashik AMRAP.

  17. Determination of aluminium in iron, steel and ferrous and non-ferrous alloys by atomic-absorption spectrophotometry after a mercury-cathode separation and extraction of the aluminium-acetylacetone complex.

    PubMed

    Donaldson, E M

    1981-07-01

    A method for determining 0.0005% or more of total aluminium in high- and low-alloy steels, iron and ferrovanadium is described. Iron, chromium and other matrix elements are separated from aluminium by electrolysis with a mercury cathode and aluminium is separated from tungsten, titanium, vanadium and phosphate by chloroform extraction of its acetylacetone complex at pH 6.5 from an ammonium acetate-hydrogen peroxide medium. The extract is evaporated to dryness and organic material is destroyed with nitric and perchloric acids. Aluminium is determined by atomic-absorption spectrophotometry in a nitrous oxide-acetylene flame, at 309.3 nm, in a 5% v/v perchloric acid medium containing 1000 mug of sodium per ml. Acid-soluble and acid-insoluble aluminium can also be determined. The method is also applicable to copper- and nickel-base alloys. Results obtained by this method are compared with those obtained spectrophotometrically with Pyrocatechol Violet, after the separations described above followed by the separation of the residual co-extracted iron and copper by a combined ammonium pyrrolidinedithiocarbamate-cupferron-chloroform extraction from 10% v/v hydrochloric acid medium.

  18. Differential determination of arsenic(III) and arsenic(V), and antimony(III) and antimony-(V) by hydride generation-atomic absorption spectrophotometry, and its application to the determination of these species in sea water

    NASA Astrophysics Data System (ADS)

    Yamamoto, Manabu; Urata, Keiji; Murashige, Kiyoto; Yamamoto, Yuroku

    A method is described for the differential determination of As(III) and As(V). and Sb(III) and Sb(V) by hydride generation-atomic absorption spectrophotometry with hydrogen-nitrogen flame using sodium borohydride solution as a reductant. For the determination of As(III) and Sb(III), most of the elements, other than Ag +, Cu 2+, Sn 2+, Se 4+ and Te 4+, do not interfere in an at least 30,000 fold excess with respect to As(III) or Sb(III). This method was applied to the determination of these species in sea water and it was found that a sample size of only 100 ml is enough to determine them with a precision of 1.5-2.5%. Analytical results for surface sea water of Hiroshima Bay were 0.72 μgl -1, 0.27 μgl -1 and 0.22 μgl -1 for As(total), As(III) and Sb(total), respectively, but Sb(III) was not detected in the present sample. The effect of acidification on storage was also examined.

  19. Determination of sub-microgram amounts of selenium in geological materials by atomic-absorption spectrophotometry with electrothermal atomisation after solvent extraction

    USGS Publications Warehouse

    Sanzolone, R.F.; Chao, T.T.

    1981-01-01

    An atomic-absorption spectrophotometric method with electrothermal atomisation has been developed for the determination of selenium in geological materials. The sample is decomposed with a mixture of nitric, perchloric and hydrofluoric acids and heated with hydrochloric acid to reduce selenium to selenium (IV). Selenium is then extracted into toluene from a hydrochloric acid - hydrobromic acid medium containing iron. A few microlitres of the toluene extract are injected into a carbon rod atomiser, using a nickel solution as a matrix modifier. The limits of determination are 0.2-200 p.p.m. of selenium in a geological sample. For concentrations between 0.05 and 0.2 p.p.m., back-extraction of the selenium into dilute hydrochloric acid is employed before atomisation. Selenium values for reference samples obtained by replicate analysis are in general agreement with those reported by other workers, with relative standard deviations ranging from 4.1 to 8.8%. Recoveries of selenium spiked at two levels were 98-108%. Major and trace elements commonly encountered in geological materials do not interfere. Arsenic has a suppressing effect on the selenium signals, but only when its concentration is greater than 1000 p.p.m. Nitric acid interferes seriously with the extraction of selenium and must be removed by evaporation in the sample-digestion step.

  20. Lead-iodide nanowire perovskite with methylviologen showing interfacial charge-transfer absorption: a DFT analysis.

    PubMed

    Fujisawa, Jun-ichi; Giorgi, Giacomo

    2014-09-07

    Methylviologen lead-iodide perovskite (MVPb2I6) is a self-assembled one-dimensional (1-D) material consisting of lead-iodide nanowires and intervening organic electron-accepting molecules, methylviologen (MV(2+)). MVPb2I6 characteristically shows optical interfacial charge-transfer (ICT) transitions from the lead-iodide nanowire to MV(2+) in the visible region and unique ambipolar photoconductivity, in which electrons are transported through the three-dimensional (3-D) organic network and holes along the 1-D lead-iodide nanowire. In this work, we theoretically study the electronic band-structure and photocarrier properties of MVPb2I6 by density functional theory (DFT) calculations. Our results clearly confirm the experimentally reported type-II band alignment, whose valence band mainly consists of 5p (I) orbitals of the lead-iodide nanowires and the conduction band of the lowest unoccupied molecular orbital of MV(2+). The DFT calculation also reveals weak charge-transfer interactions between the lead-iodide nanowires and MV(2+). In addition, the electronic distributions of the valence and conduction bands indicate the 3-D transport of electrons and 1-D transport of holes, supporting the reported experimental result.

  1. Combined spectrophotometry and tensile measurements of human connective tissues: potentials and limitations.

    PubMed

    Ernstberger, Markus; Sichting, Freddy; Baselt, Tobias; Hartmann, Peter; Aust, Gabriela; Hammer, Niels

    2013-06-01

    Strain-dependent transmission data of nine iliotibial tract specimens are determined using a custom-built optical setup with a halogen light source and an industrial norm material testing machine. Polarized light microscopy and hematoxylin-eosin staining indicated that lateral contraction of collagen structures is responsible for total intensity variations during a 20-cycle preconditioning and a 5-cycle tensile test. Tensile force progress is opposite to total transmission progress. Due to dehydration, wavelength-specific radiation intensity shifting is determined during the test, primarily noticeable in a water absorption band between 1400 and 1500 nm. The results show the capability of integrating spectrophotometry technology into biomechanics for determining structural alterations of human collagen due to applied strain. Being more sensitive to drying, spectrophotometry may likely serve as a quality control in stress-strain testing of biological structures.

  2. Transient absorption and photocurrent microscopy show that hot electron supercollisions describe the rate-limiting relaxation step in graphene.

    PubMed

    Graham, Matt W; Shi, Su-Fei; Wang, Zenghui; Ralph, Daniel C; Park, Jiwoong; McEuen, Paul L

    2013-01-01

    Using transient absorption (TA) microscopy as a hot electron thermometer, we show that disorder-assisted acoustic-phonon supercollisions (SCs) best describe the rate-limiting relaxation step in graphene over a wide range of lattice temperatures (Tl = 5-300 K), Fermi energies (E(F) = ± 0.35 eV), and optical probe energies (~0.3-1.1 eV). Comparison with simultaneously collected transient photocurrent, an independent hot electron thermometer, confirms that the rate-limiting optical and electrical response in graphene are best described by the SC-heat dissipation rate model, H = A(T(e)(3) - T(l)(3)). Our data further show that the electron cooling rate in substrate-supported graphene is twice as fast as in suspended graphene sheets, consistent with SC model prediction for disorder.

  3. 4-8 micron spectrophotometry of OH 0739-14

    NASA Technical Reports Server (NTRS)

    Soifer, B. T.; Willner, S. P.; Rudy, R. J.; Capps, R. W.

    1981-01-01

    Spectrophotometry of the dust-embedded late-type star OH 0739-14 shows an absorption feature at 6.0 microns characteristic of H2O ice at temperatures significantly lower than 150 K, confirming the identification of H2O ice in the circumstellar shell in this source. The differences in the infrared spectra of HO 0739-14 and embedded molecular cloud sources are attributed to the different cloud lifetimes and temperature regimes in which the molecules are formed. A lower limit to the mass loss rate of 0.0001 solar mass per year is derived, based on the column density of ice and the size and the expansion velocity of the circumstellar cloud.

  4. High-Sensitivity Spectrophotometry.

    ERIC Educational Resources Information Center

    Harris, T. D.

    1982-01-01

    Selected high-sensitivity spectrophotometric methods are examined, and comparisons are made of their relative strengths and weaknesses and the circumstances for which each can best be applied. Methods include long path cells, noise reduction, laser intracavity absorption, thermocouple calorimetry, photoacoustic methods, and thermo-optical methods.…

  5. Multi-filter spectrophotometry simulations

    NASA Technical Reports Server (NTRS)

    Callaghan, Kim A. S.; Gibson, Brad K.; Hickson, Paul

    1993-01-01

    To complement both the multi-filter observations of quasar environments described in these proceedings, as well as the proposed UBC 2.7 m Liquid Mirror Telescope (LMT) redshift survey, we have initiated a program of simulated multi-filter spectrophotometry. The goal of this work, still very much in progress, is a better quantitative assessment of the multiband technique as a viable mechanism for obtaining useful redshift and morphological class information from large scale multi-filter surveys.

  6. Clinical applications of lightguide diffuse reflectance spectrophotometry in vascular disease

    NASA Astrophysics Data System (ADS)

    Harrison, David K.; Delaney, Colin; Brown, Linda; Newton, David J.; McCollum, Peter T.

    1994-02-01

    There is enormous potential for application of lightguide tissue reflectance spectrophotometry in the diagnosis and treatment of peripheral vascular disease. In the present study, measurements were carried out in 10 such pre-amputation patients to compare the use of micro-lightguide spectrophotometry with the macro-lightguide technique. These preliminary results show excellent agreement between the new, non-invasive micro-lightguide technique and the `gold standard' skin blood flow measurements. This technique could thus provide a more functional, non-invasive assessment of healing potential than skin blood flow measurement.

  7. PRECISION SPECTROPHOTOMETRY AT THE LEVEL OF 0.1%

    SciTech Connect

    Yan Renbin

    2011-11-15

    Accurate relative spectrophotometry is critical for many science applications. Small wavelength-scale residuals in the flux calibration can significantly impact the measurements of weak emission and absorption features in the spectra. Using Sloan Digital Sky Survey data, we demonstrate that the average spectra of carefully selected red-sequence galaxies can be used as a spectroscopic standard to improve the relative spectrophotometry precision to 0.1% on small wavelength scales (from a few to hundreds of Angstroms). We achieve this precision by comparing stacked spectra across tiny redshift intervals. The redshift intervals must be small enough that any systematic stellar population evolution is minimized and is less than the spectrophotometric uncertainty. This purely empirical technique does not require any theoretical knowledge of true galaxy spectra. It can be applied to all large spectroscopic galaxy redshift surveys that sample a large number of galaxies in a uniform population.

  8. Design, synthesis, and properties of phthalocyanine complexes with main-group elements showing main absorption and fluorescence beyond 1000 nm.

    PubMed

    Furuyama, Taniyuki; Satoh, Koh; Kushiya, Tomofumi; Kobayashi, Nagao

    2014-01-15

    We present a comprehensive description of the unique properties of newly developed phthalocyanines (Pcs) containing main-group elements that absorb and emit in the near-IR region. Group 16 (S, Se, and Te) elements and group 15 (P, As, and Sb) elements were used as peripheral and central (core) substituents. With the introduction of group 16 elements into free-base Pc, a red-shift of the Q-band was observed, as a result of the electron-donating ability of group 16 elements particularly at the α positions. An X-ray crystallographic analysis of α-ArS-, ArSe-, and ArTe-linked free-base Pcs was also successfully performed, and the relationship between structure and optical properties was clarified. When a group 15 element ion was introduced into the center of the Pc ring, the resulting Pcs showed a single Q-band peak beyond 1000 nm (up to 1056 nm in CH2Cl2). In particular, [(ArS)8PcP(OMe)2](+) and [(ArS)8PcAs(OMe)2](+) exhibited a distinct fluorescence in the 960-1400 nm region with moderate quantum yields. The atomic radius of the group 15 element is important for determining the Pc structure, so that this can be controlled by the choice of group 15 elements. Electrochemical data revealed, while MO calculations suggested, that the red-shift of the Q-band is attributable to a decrease of the HOMO-LUMO gap due to significant and moderate stabilization of the LUMO and HOMO, respectively. The effect of peripheral substutuents and a central P(V) ion on the Q-band shift was independently predicted by MO calculations, while the magnitude of the total calculated shift was in good agreement with the experimental observations. The combination of spectral, electrochemical, and theoretical considerations revealed that all of the central group 15 elements, peripheral group 16 elements, and their positions are necessary to shift the Q-band beyond 1000 nm, indicating that the substitution effects of group 15 and 16 elements act synergistically. The Pcs having Q-bands beyond 1000 nm

  9. Optical imagery and spectrophotometry of CTB 80

    NASA Technical Reports Server (NTRS)

    Hester, J. Jeff; Kulkarni, Shrinivas R.

    1989-01-01

    Narrow-band imagery and spectrophotometry of the central region of CTB 80 are presented. The images show weak forbidden O III and ubiquitous filamentary forbidden S II and H-alpha emission from the extended radio lobes in which the core is embedded. The data indicate that the extended component is shock heated. Balmer line-dominated emission is observed around the perimeter of the core. Assuming that the volume of the radio shell is similar to the volume of the thermal shell, it is found that a magnetic field of about 600 microG and a cosmic-ray proton-to-electron ratio of about 200 are required to explain the pressure and synchrotron volume emissivity in the radio shell. It is suggested that the optical emission form the core of CTB 80 arises behind shocks which are being driven into a magnetized thermal plasma by the confined relativistic wind from PSR 1951+32.

  10. Absolute spectrophotometry of Neptune - 3390 to 7800 A

    NASA Astrophysics Data System (ADS)

    Bergstralh, J. T.; Neff, J. S.

    1983-07-01

    Absolute spectrophotometry of Neptune from 3390 to 7800 Å, with spectral resolution of 10 Å in the interval 3390 - 6055 and 20 Å in the interval 6055 - 7800 Å, is reported. The results are compared with filter photometry (Appleby, 1973; Wamsteker, 1973; Savage et al., 1980) and with synthetic spectra computed on the basis of a parameterization proposed by Podolak and Danielson (1977) for aerosol scattering and absorption. A CH4/H2 ratio is derived for the convectively mixed part of Neptune's atmosphere, and constrains optical properties of hypothetical aerosol layers.

  11. [Quantitative determination of total flavonoids in sea-buckthorn fruit juice by three wavelength spectrophotometry].

    PubMed

    Hui, Rui-hua; Hou, Dong-yan; Guan, Chong-xin; Liu, Xiao-yuan

    2005-02-01

    Numerous studies dealing with the quantitative determination of total flavonoids in sea-buckthorn fruit juice by spectrophotometry are presented. The flavonoids in sea-buckthorn fruit juice and aluminate produce stable complex whose absorption occurred at longer wavelength. To determine the total flavonoids in sea-buckthorn fruit juice by traditional spectrophotometry method, baseline shift and asymmetric absorption peak occurred on the absorption curve. Quantitative determination of flavonoids in sea-buckthorn fruit juice by three wavelength spectrophotometry method can eliminate the absorbance error caused interfering components in turbid solution and the scattering effect. Background changing with the concentration change and asymmetric absorption peak problems can also be solved. The regression equation of concentration vs deltaA was obtained: deltaA = - 0.00703 + 0.00048c with a relation coefficient gamma = 0.9991. The experimental results demostrate the total flavonoids concentrations in 0-800 microg x mL(-1) with deltaA obeying linear relation when the absorbance was measured at wavelength lambda1 = 495 nm, lambda2 = 415 nm and lambda3 = 368 nm. The recovery is 97.0%-101.0% and the coefficient of variation is 0.058% (n = 9). The method is more advantageous than tranditional spectrophotometry method.

  12. Study of Biological Pigments by Single Specimen Derivative Spectrophotometry

    PubMed Central

    Goldstein, Jack M.

    1970-01-01

    The single specimen derivative (SSD) method provides an absolute absorption spectrum of a substance in the absence of a suitable reference. Both a reference and a measuring monochromatic beam pass through a single sample, and the specimen itself acts as its own reference. The two monochromatic beams maintain a fixed wavelength difference upon scanning, and the difference in absorbance of the two beams is determined. Thus, the resulting spectrum represents the first derivative of the conventional type absorption spectrum. Tissues and cell fractions have been examined at room and liquid N2 temperature and chromophoric molecules such as the mitochondrial cytochromes and blood pigments have been detectable in low concentrations. In the case of isolated cellular components, the observed effects of substrates and inhibitors confirm similar studies by conventional spectrophotometry. The extension of the SSD concept to the microscopic level has permitted the study of the tissue compartmentalization and function of cytochromes and other pigments within layered tissue. PMID:4392452

  13. Spectrophotometry of 237 Stars in 7 Open Clusters

    NASA Astrophysics Data System (ADS)

    Clampitt, Lori; Burstein, David

    1997-08-01

    Spectrophotometry is presented for 237 stars in 7 nearby open clusters: Hyades, Pleiades, Alpha Persei, Praesepe, Coma Berenices, IC 4665, and M39. The observations were taken by Lee McDonald and David Burstein using the Wampler single-channel scanner on the Crossley 0.9m telescope at Lick Observatory from July 1973 through December 1974. Sixteen bandpasses spanning the spectral range 3500 Angstroms to 7780 Angstroms were observed for each star, with bandwidths 32Angstroms, 48 Angstroms or 64 Angstroms. Data are standardized to the Hayes-Latham system to mutual accuracy of 0.016 mag per passband. The accuracy of the spectrophotometry is assessed in three ways on a star-by-star basis. First, comparisons are made with previously published spectrophotometry for 19 stars observed in common. Second, (B-V) colors and uvby colors are compared for 236 stars and 221 stars, respectively. Finally, comparsions are made for 200 main sequence stars to the spectral synthesis models of Kurucz, fixing log g = 4.0 and [Fe/H] = 0.0, and only varying effective temperature. The accuracy of tests using uvby colors and the Kurucz models are shown to track each other closely, yielding an accuracy estimate (1 sigma ) of 0.01 mag for the 13 colors formed from bandpasses longward of the Balmer jump, and 0.02 mag for the 3 colors formed from the three bandpasses below the Balmer jump. In contrast, larger scatter is found relative to the previously published spectrophotometry of Bohm-Vitense & Johnson (16 stars in common) and Gunn & Stryker (3 stars). We also show that the scatter in the fits of the spectrophotometric colors and the uvby filter colors is a reasonable way to identify the observations of which specific stars are accurate to 1 sigma , 2 sigma , .... As such, the residuals from both the filter color fits and the Kurucz model fits are tabulated for each star where it was possible to make a comparison, so users of these data can choose stars according to the accuracy of the data

  14. X-ray Absorption Spectroscopy of Zinc in Airborne Particulate Matter Shows Tire Debris Concentrated in > 0.5 μm Fraction

    NASA Astrophysics Data System (ADS)

    Pingitore, N. E.; Clague, J. W.; Gill, T. E.; Amaya, M. A.; Cahill, T. A.

    2009-12-01

    Using X-ray absorption spectroscopy (XAS), we speciated Zn in size-resolved fractions of particulate matter (PM) from El Paso, Texas. Spectral patterns indicated that Zn in tire debris is the dominant form of Zn in PM coarser than 0.5 μm in aerodynamic diameter. Although concentrated in the > 0.5 μm fraction, a large portion of the tire debris in PM is small enough to penetrate and deposit in the lower respiratory tract. We collected 3 sets of size-resolved samples of airborne particulate matter (PM) over periods of several days to several weeks in November 2008, and April and May 2009. Local PM compositions typically are dominated by anthropogenic input in November and geologic sources in April, and a mixture in May. The collection site is in the urban core of El Paso, TX, contiguous to the University of Texas at El Paso, 0.6 km from Interstate Highway 10, 0.4 km from State Highway 20, and 1 km from Cd. Juarez, Chihuahua, Mexico. The DRUM sampler (Davis Rotating Uniform size-cut Monitor) employs a rotating Lundgren-type impactor, draws 10 l per minute, and deposits PM on plastic strips mounted on rotating drums. The sampler collected and segregated ambient PM into 8 size cuts: 12-5 μm, 5-2.5, 2.5-1.15, 1.15-0.75, 0.75-0.56, 0.56-0.34, 0.34-0.26, and 0.26-0.09. We conducted the X-ray absorption spectroscopy (XAS) experiments at the Stanford Synchrotron Radiation Lightsource on beam line 7-3. Spectra of the 24 samples of PM and numerous model compounds were collected at the Zn K absorption edge in fluorescence mode using a 30-element Ge solid-state detector. The overall spectral patterns from the 3 seasons were similar to one another. But strikingly, each set of 8 XAS spectra displayed an obvious change in the Zn speciation at the 0.56-0.75 μm size cut. We compared the PM spectra to those of our suite of known model compounds and materials. The spectral pattern of the coarser size cuts was quite similar to those of the tires we tested. The Zn in the tires

  15. Mathematical calculations of iron complex stoichiometry by direct UV-Vis spectrophotometry.

    PubMed

    Filipský, Tomáš; Říha, Michal; Hrdina, Radomír; Vávrová, Kateřina; Mladěnka, Přemysl

    2013-08-01

    The effects of iron-chelating agents on miscellaneous pathologies are currently largely tested. Due to various indications, different properties for chelators are required. A stoichiometry of the complex in relation to pH is one of the crucial factors. Moreover, the published data on the stoichiometry, especially concerning flavonoids, are equivocal. In this study, a new complementary approach was employed for the determination of stoichiometry in 10 iron-chelating agents, including clinically used drugs, by UV-Vis spectrophotometry at relevant pH conditions and compared with the standard Job's method. This study showed that the simple approach based on absorbance at the wavelength of complex absorption maximum was sufficient when the difference between absorption maximum of substance and complex was high. However, in majority of substances this difference was much lower (9-73 nm). The novel complementary approach was able to determine the stoichiometry in all tested cases. The major benefit of this method compared to the standard Job's approach seems to be its capability to reveal a reaction stoichiometry in chelators with moderate affinity to iron. In conclusion, using this complementary method may explain several previous contradictory data and lead to a better understanding of the underlying mechanisms of chelator's action.

  16. A Low-Cost Quantitative Absorption Spectrophotometer

    ERIC Educational Resources Information Center

    Albert, Daniel R.; Todt, Michael A.; Davis, H. Floyd

    2012-01-01

    In an effort to make absorption spectrophotometry available to high school chemistry and physics classes, we have designed an inexpensive visible light absorption spectrophotometer. The spectrophotometer was constructed using LEGO blocks, a light emitting diode, optical elements (including a lens), a slide-mounted diffraction grating, and a…

  17. Infrared Spectrophotometry of NEAR Target Asteroids

    NASA Astrophysics Data System (ADS)

    Rivkin, A. S.; Clark, B. E.; Lebofsky, L. A.

    1996-09-01

    Water and the OH radical, both in free and bound forms, have strong absorption features near 3 mu m, observed on many asteroids since the late 1970's (Lebofsky 1978, Feierberg et al. 1985). A knowledge of which asteroids have hydration and where hydrated asteroids are located gives important insights into the conditions prevailing near the beginning of solar system history. We have performed spectrophotometry of the NEAR target asteroids 253 Mathilde and 433 Eros using 5 filters from 1.25--3.35 mu m. Our observations were made at the Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii in December 1995 and May 1996. We find 253 Mathilde to have a spectrum consistent with C-class asteroids in the near-IR, although without the 3-mu m water-of-hydration feature commonly seen on asteroids of this class ( ~ 60% of Cs are hydrated). The upper limit on a feature for Mathilde is 10%. Our JHK colors of 433 Eros are consistent with previous observations (Chapman and Morrison 1976, Icarus 28), and our 3-mu m data indicate no water of hydration, as expected for an S-class asteroid. No variability in colors was seen on these bodies within our uncertainty, although it is worth noting that 433 Eros was close to pole-on when observed, and that our observing run was short compared to the long rotation period (17.4 days) of 253 Mathilde (Mottola et al. 1995, Planet. Space Sci. 43). Binzel et al. (1996) compared 253 Mathilde to plausible meteorite analogs and found the best spectral matches to be unusual thermally metamorphosed carbonaceous chondrites or the shocked ``black'' ordinary chondrites (Hiroi et al. 1993, Science 261, Britt and Pieters 1989, LPSC 20). We too find the black chondrites to be acceptable spectral analogs, as well as samples of Murchison heated by Hiroi et al. (1993). This suggests that the surface of 253 Mathilde may be composed of either thermally metamorphosed carbonaceous chondrite or shock-darkened ordinary chondrite. Combining our data with the data of

  18. Determination of Iron in Milk Powdermicrowave Digestion and Flame Atomicabsorption Spectrophotometry

    NASA Astrophysics Data System (ADS)

    Zhao, Guangyuan; Li, Bo

    To investigate the conditions of microwave digestion for determining Iron in milk powder by flame atomic absorption spectrophotometry(FAAS), the content of iron in milk powder was determined by flame atomic absorption spectrophotometry after the samples were microwavely digested under different conditions. The optimum parameters for microwave digestion were obtained by the orthogonal test at last. The best optimum parameters for microwave digestion was that, the volume of digestion solution was 8mL, the reagent proportion for HNO3 and H2O2 was 4:1, the digestion time was 8min, the digestion pressure was 2.6 Mpa and the digestion power was 1000 W. The content of Iron in assayed milk powder was 0.0560mg/g. Microwave digestion was a time-saving and practical pretreatment of samples.

  19. Spectrophotometry of 2 complete samples of flat radio spectrum quasars

    NASA Technical Reports Server (NTRS)

    Wampler, E. J.; Gaskell, C. M.; Burke, W. L.; Baldwin, J. A.

    1983-01-01

    Spectrophotometry of two complete samples of flat-spectrum radio quasars show that for these objects there is a strong correlation between the equivalent width of the CIV wavelength 1550 emission line and the luminosity of the underlying continuum. Assuming Friedmann cosmologies, the scatter in this correlation is a minimum for q (sub o) is approximately 1. Alternatively, luminosity evolution can be invoked to give compact distributions for q (sub o) is approximately 0 models. A sample of Seyfert galaxies observed with IUE shows that despite some dispersion the average equivalent width of CIV wavelength 1550 in Seyfert galaxies is independent of the underlying continuum luminosity. New redshifts for 4 quasars are given.

  20. Absolute Spectrophotometry of 237 Open Cluster Stars

    NASA Astrophysics Data System (ADS)

    Clampitt, L.; Burstein, D.

    1994-12-01

    We present absolute spectrophotometry of 237 stars in 7 nearby open clusters: Hyades, Pleiades, Alpha Persei, Praesepe, Coma Berenices, IC 4665, and M 39. The observations were taken using the Wampler single-channel scanner (Wampler 1966) on the Crossley 0.9m telescope at Lick Observatory from July 1973 through December 1974. 21 bandpasses spanning the spectral range 3500 Angstroms to 7780 Angstroms were observed for each star, with bandwiths ranging from 32Angstroms to 64 Angstroms. Data are standardized to the Hayes--Latham (1975) system. Our measurements are compared to filter colors on the Johnson BV, Stromgren ubvy, and Geneva U V B_1 B_2 V_1 G systems, as well as to spectrophotometry of a few stars published by Gunn, Stryker & Tinsley and in the Spectrophotometric Standards Catalog (Adelman; as distributed by the NSSDC). Both internal and external comparisons to the filter systems indicate a formal statistical accuracy per bandpass of 0.01 to 0.02 mag, with apparent larger ( ~ 0.03 mag) differences in absolute calibration between this data set and existing spectrophotometry. These data will comprise part of the spectrophotometry that will be used to calibrate the Beijing-Arizona-Taipei-Connecticut Color Survey of the Sky (see separate paper by Burstein et al. at this meeting).

  1. Slow-Reduction Synthesis of a Thiolate-Protected One-Dimensional Gold Cluster Showing an Intense Near-Infrared Absorption.

    PubMed

    Takano, Shinjiro; Yamazoe, Seiji; Koyasu, Kiichirou; Tsukuda, Tatsuya

    2015-06-10

    Slow reduction of Au ions in the presence of 4-(2-mercaptoethyl)benzoic acid (4-MEBA) gave Au76(4-MEBA)44 clusters that exhibited a strong (3 × 10(5) M(-1) cm(-1)) near-infrared absorption band at 1340 nm. Powder X-ray diffraction studies indicated that the Au core has a one-dimensional fcc structure that is elongated along the {100} direction.

  2. Infrared spectrophotometry of OH 231.8 + 4.2 identified with OH 0739-14

    NASA Technical Reports Server (NTRS)

    Gillett, F. C.; Soifer, B. T.

    1976-01-01

    Infrared spectrophotometry from 2.1 to 4.1 microns and from 7.7 to 13.3 microns of the peculiar OH maser source OH 231.8 + 4.2 identified with OH 0739-14 is reported. Deep absorption features are found at 3.1 microns and from 8 to 13 microns, and are identified with absorption by cold ices and silicates in the line of sight to the infrared source. The infrared flux is also found to vary. These infrared observations present new difficulties in understanding the nature of the object. Several possibly useful observations of OH 231.8 + 4.2 are suggested.

  3. Ultraviolet spectrophotometry of three LINERs

    NASA Technical Reports Server (NTRS)

    Goodrich, R. W.; Keel, W. C.

    1986-01-01

    Three galaxies known to be LINERs were observed spectroscopically in the ultraviolet in an attempt to detect the presumed nonthermal continuum source thought to be the source of photoionization in the nuclei. NGC 4501 was found to be too faint for study with the IUE spectrographs, while NGC 5005 had an extended ultraviolet light profile. Comparison with the optical light profile of NGC 5005 indicates that the ultraviolet source is distributed spatially in the same manner as the optical starlight, probably indicating that the ultraviolet excess is due to a component of hot stars in the nucleus. These stars contribute detectable absorption features longward of 2500 A; together with optical data, the IUE spectra suggest a burst of star formation about 1 billion yr ago, with a lower rate continuing to produce a few OB stars. In NGC 4579, a point source contributing most of the ultraviolet excess is found that is much different than the optical light distribution. Furthermore, the ultraviolet to X-ray spectral index in NGC 4579 is 1.4, compatible with the UV to X-ray indices found for samples of Seyfert galaxies. This provides compelling evidence for the detection of the photoionizing continuum in NGC 4579 and draws the research fields of normal galaxies and active galactic nuclei closer together. The emission-line spectrum of NGC 4579 is compared with calculations from a photoionization code, CLOUDY, and several shock models. The photoionization code is found to give superior results, adding to the increasing weight of evidence that the LINER phenomenon is essentially a scaled-down version of the Seyfert phenomenon.

  4. Partitioning of organophosphorus pesticides into phosphatidylcholine small unilamellar vesicles studied by second-derivative spectrophotometry.

    PubMed

    Takegami, Shigehiko; Kitamura, Keisuke; Ohsugi, Mayuko; Ito, Aya; Kitade, Tatsuya

    2015-06-15

    In order to quantitatively examine the lipophilicity of the widely used organophosphorus pesticides (OPs) chlorfenvinphos (CFVP), chlorpyrifos-methyl (CPFM), diazinon (DZN), fenitrothion (FNT), fenthion (FT), isofenphos (IFP), profenofos (PFF) and pyraclofos (PCF), their partition coefficient (Kp) values between phosphatidylcholine (PC) small unilamellar vesicles (SUVs) and water (liposome-water system) were determined by second-derivative spectrophotometry. The second-derivative spectra of these OPs in the presence of PC SUV showed a bathochromic shift according to the increase in PC concentration and distinct derivative isosbestic points, demonstrating the complete elimination of the residual background signal effects that were observed in the absorption spectra. The Kp values were calculated from the second-derivative intensity change induced by addition of PC SUV and obtained with a good precision of R.S.D. below 10%. The Kp values were in the order of CPFM>FT>PFF>PCF>IFP>CFVP>FNT⩾DZN and did not show a linear correlation relationship with the reported partition coefficients obtained using an n-octanol-water system (R(2)=0.530). Also, the results quantitatively clarified the effect of chemical-group substitution in OPs on their lipophilicity. Since the partition coefficient for the liposome-water system is more effective for modeling the quantitative structure-activity relationship than that for the n-octanol-water system, the obtained results are toxicologically important for estimating the accumulation of these OPs in human cell membranes.

  5. Partitioning of organophosphorus pesticides into phosphatidylcholine small unilamellar vesicles studied by second-derivative spectrophotometry

    NASA Astrophysics Data System (ADS)

    Takegami, Shigehiko; Kitamura, Keisuke; Ohsugi, Mayuko; Ito, Aya; Kitade, Tatsuya

    2015-06-01

    In order to quantitatively examine the lipophilicity of the widely used organophosphorus pesticides (OPs) chlorfenvinphos (CFVP), chlorpyrifos-methyl (CPFM), diazinon (DZN), fenitrothion (FNT), fenthion (FT), isofenphos (IFP), profenofos (PFF) and pyraclofos (PCF), their partition coefficient (Kp) values between phosphatidylcholine (PC) small unilamellar vesicles (SUVs) and water (liposome-water system) were determined by second-derivative spectrophotometry. The second-derivative spectra of these OPs in the presence of PC SUV showed a bathochromic shift according to the increase in PC concentration and distinct derivative isosbestic points, demonstrating the complete elimination of the residual background signal effects that were observed in the absorption spectra. The Kp values were calculated from the second-derivative intensity change induced by addition of PC SUV and obtained with a good precision of R.S.D. below 10%. The Kp values were in the order of CPFM > FT > PFF > PCF > IFP > CFVP > FNT ⩾ DZN and did not show a linear correlation relationship with the reported partition coefficients obtained using an n-octanol-water system (R2 = 0.530). Also, the results quantitatively clarified the effect of chemical-group substitution in OPs on their lipophilicity. Since the partition coefficient for the liposome-water system is more effective for modeling the quantitative structure-activity relationship than that for the n-octanol-water system, the obtained results are toxicologically important for estimating the accumulation of these OPs in human cell membranes.

  6. Surface composition of Mercury from reflectance spectrophotometry

    NASA Technical Reports Server (NTRS)

    Vilas, Faith

    1988-01-01

    The controversies surrounding the existing spectra of Mercury are discussed together with the various implications for interpretations of Mercury's surface composition. Special attention is given to the basic procedure used for reducing reflectance spectrophotometry data, the factors that must be accounted for in the reduction of these data, and the methodology for defining the portion of the surface contributing the greatest amount of light to an individual spectrum. The application of these methodologies to Mercury's spectra is presented.

  7. X-ray absorption and resonant inelastic x-ray scattering (RIXS) show the presence of Cr{sup +} at the surface and in the bulk of CrF{sub 2}

    SciTech Connect

    Jiménez-Mier, J.; Olalde-Velasco, P.; Yang, W.-L.; Denlinger, J.

    2015-07-23

    X-Ray absorption and resonant inelastic x-ray scattering (RIXS) spectra of CrF{sub 2} recorded at the chromium L{sub 2,3} are presented. An atomic multiplet crystal field calculation is compared with the experimental data. Experiment and theory are in agreement once the calculation includes three chromium oxidation states, namely Cr{sup +}, Cr{sup 2+}, and Cr{sup 3+}. X-Ray absorption allows a direct determination of the surface oxidation, while the RIXS spectra shows the presence of these three oxidation states in the sample bulk. To give a quantitative interpretation of the RIXS data the effect of the incomming and outgoing photon penetration depth and self-absorption must be considered. For the much simpler case of MnF{sub 2}, with only one metal oxidation state, the measured RIXS spectra relative intensities are found to be proportional to the square of the sample attenuation length.

  8. Rhenium(I) tricarbonyl polypyridine complexes showing strong absorption of visible light and long-lived triplet excited states as a triplet photosensitizer for triplet-triplet annihilation upconversion.

    PubMed

    Yi, Xiuyu; Zhao, Jianzhang; Wu, Wanhua; Huang, Dandan; Ji, Shaomin; Sun, Jifu

    2012-08-07

    The preparation of rhenium(I) tricarbonyl polypyridine complexes that show a strong absorption of visible light and long-lived triplet excited state and the application of these complexes as triplet photosensitizers for triplet-triplet annihilation (TTA) based upconversion are reported. Imidazole-fused phenanthroline was used as the N^N coordination ligand, on which different aryl groups were attached (Phenyl, Re-0; Coumarin, Re-1 and naphthyl, Re-2). Re-1 shows strong absorption of visible light (ε = 60,800 M(-1) cm(-1) at 473 nm). Both Re-1 and Re-2 show long-lived T(1) states (lifetime, τ(T), is up to 86.0 μs and 64.0 μs, respectively). These properties are in contrast to the weak absorption of visible light and short-lived triplet excited states of the normal rhenium(I) tricarbonyl polypyridine complexes, such as Re-0 (ε = 5100 M(-1) cm(-1) at 439 nm, τ(T) = 2.2 μs). The photophysical properties of the complexes were fully studied with steady state and time-resolved absorption and emission spectroscopes, as well as DFT calculations. The intra-ligand triplet excited state is proposed to be responsible for the exceptionally long-lived T(1) states of Re-1 and Re-2. The Re(I) complexes were used as triplet photosensitizers for TTA based upconversion and an upconversion quantum yield up to 17.0% was observed.

  9. Intestinal absorption of berberine and 8-hydroxy dihydroberberine and their effects on sugar absorption in rat small intestine.

    PubMed

    Wei, Shi-chao; Dong, Su; Xu, Li-jun; Zhang, Chen-yu

    2014-04-01

    The intestinal absorption of berberine (Ber) and its structural modified compound 8-hydroxy dihydroberberine (Hdber) was compared, and their effects on the intestinal absorption of sugar by perfusion experiment were investigated in order to reveal the mechanism of low dose and high activity of Hdber in the treatment of hyperglycemia. The absorption of Hdber and Ber in rat small intestine was measured by in situ perfusion. High performance liquid chromatography (HPLC) was used to determine the concentrations of Hdber and Ber. In situ perfusion method was also used to study the effects of Hdber and Ber on sugar intestinal absorption. Glucose oxidase method and UV spectrophotometry were applied to examine the concentrations of glucose and sucrose in the perfusion fluid. The results showed that the absorption rate of Ber in the small intestine was lower than 10%, but that of Hdber was larger than 70%. Both Hdber and Ber inhibited the absorption of glucose and sucrose at the doses of 10 and 20 μg/mL. However, Hdber presented stronger activity than Ber (P<0.01). It is suggested that Hdber is absorbed easily in rat small intestine and that its inhibitory effect on the absorption of sugar is better than Ber.

  10. Tunable Diode Laser Heterodyne Spectrophotometry of Ozone

    NASA Technical Reports Server (NTRS)

    Fogal, P. F.; McElroy, C. T.; Goldman, A.; Murcray, D. G.

    1988-01-01

    Tunable diode laser heterodyne spectrophotometry (TDLHS) has been used to make extremely high resolution (less than 0.0005/ cm) solar spectra in the 9.6 micron ozone band. Observations have shown that a signal-to-noise ratio of 95 : 1 (35% of theoretical) for an integration time of 1/8 second can be achieved at a resolution of 0.0005 wavenumbers. The spectral data have been inverted to yield a total column amount of ozone, in good agreement with that. measured at the nearby National Oceanographic and Atmospheric Administration (NOAA) ozone monitoring facility in Boulder, Colorado.

  11. White LEDs as broad spectrum light sources for spectrophotometry: demonstration in the visible spectrum range in a diode-array spectrophotometric detector.

    PubMed

    Piasecki, Tomasz; Breadmore, Michael C; Macka, Mirek

    2010-11-01

    Although traditional lamps, such as deuterium lamps, are suitable for bench-top instrumentation, their compatibility with the requirements of modern miniaturized instrumentation is limited. This study investigates the option of utilizing solid-state light source technology, namely white LEDs, as a broad band spectrum source for spectrophotometry. Several white light LEDs of both RGB and white phosphorus have been characterized in terms of their emission spectra and energy output and a white phosphorus Luxeon LED was then chosen for demonstration as a light source for visible-spectrum spectrophotometry conducted in CE. The Luxeon LED was fixed onto the base of a dismounted deuterium (D(2) ) lamp so that the light-emitting spot was geometrically positioned exactly where the light-emitting spot of the original D(2) lamp is placed. In this manner, the detector of a commercial CE instrument equipped with a DAD was not modified in any way. As the detector hardware and electronics remained the same, the change of the deuterium lamp for the Luxeon white LED allowed a direct comparison of their performances. Several anionic dyes as model analytes with absorption maxima between 450 and 600 nm were separated by CE in an electrolyte of 0.01 mol/L sodium tetraborate. The absorbance baseline noise as the key parameter was 5 × lower for the white LED lamp, showing clearly superior performance to the deuterium lamp in the available, i.e. visible part of the spectrum.

  12. Determination of astaxanthin in Haematococcus pluvialis by first-order derivative spectrophotometry.

    PubMed

    Liu, Xiao Juan; Juan, Liu Xiao; Wu, Ying Hua; Hua, Wu Ying; Zhao, Li Chao; Chao, Zhao Li; Xiao, Su Yao; Yao, Xiao Su; Zhou, Ai Mei; Mei, Zhou Ai; Liu, Xin; Xin, Liu

    2011-01-01

    A highly selective, convenient, and precise method, first-order derivative spectrophotometry, was applied for the determination of astaxanthin in Haematococcus pluvialis. Ethyl acetate and ethanol (1:1, v/v) were found to be the best extraction solvent tested due to their high efficiency and low toxicity compared with nine other organic solvents. Astaxanthin coexisting with chlorophyll and beta-carotene was analyzed by first-order derivative spectrophotometry in order to optimize the conditions for the determination of astaxanthin. The results show that when detected at 432 nm, the interfering substances could be eliminated. The dynamic linear range was 2.0-8.0 microg/mL, with a correlation coefficient of 0.9916. The detection threshold was 0.41 microg/mL. The RSD for the determination of astaxanthin was in the range of 0.01-0.06%; the results of recovery test were 98.1-108.0%. The statistical analysis between first-order derivative spectrophotometry and HPLC by T-testing did not exceed their critical values, revealing no significant differences between these two methods. It was proved that first-order derivative spectrophotometry is a rapid and convenient method for the determination of astaxanthin in H. pluvialis that can eliminate the negative effect resulting from the coexistence of astaxanthin with chlorophyll and beta-carotene.

  13. Airborne spectrophotometry of Comet Halley from 5 to 9 microns

    NASA Technical Reports Server (NTRS)

    Campins, H.; Bregman, J. D.; Witteborn, F. C.; Wooden, D. H.; Rank, D. M.; Cohen, M.; Allamandola, Louis J.; Tielens, Alexander G. G. M.

    1986-01-01

    Spectrophotometry from 5 to 9 microns (resolution = 0.02) of comet Halley was obtained from the Kuiper Airborne Observatory on 1985 Dec. 12.1 and 1986 April 8.6 and 10.5 UT. Two spectral features are apparent in all the observations, one from 5.24 to 5.6 microns, and the silicate emission feature which has an onset between 7 and 8 microns. There is no evidence for the 7.5 microns feature observed by the Vega 1 spacecraft; the large difference between the areal coverage viewed from the spacecraft and the airplane may explain the discrepancy. Color temperatures significantly higher than a blackbody indicate that small particles are abundant in the coma. Significant spatial and temporal variations in the spectrum show trends similar to those observed from the ground.

  14. CVF spectrophotometry of Pluto - Correlation of composition with albedo. [circularly variable filter

    NASA Technical Reports Server (NTRS)

    Marcialis, Robert L.; Lebofsky, Larry A.

    1991-01-01

    The present time-resolved, 0.96-2.65-micron spectrophotometry for the Pluto-Charon system indicates night-to-night variations in the depths of the methane absorptions such that the bands' equivalent width is near minimum light. The interpretation of these data in terms of a depletion of methane in dark regions of the planet, relative to bright ones, is consistent with the Buie and Fink (1987) observations. The near-IR spectrum of Pluto seems to be dominated by surface frost. It is suggested that the dark equatorial regions of Pluto are redder than those of moderate albedo.

  15. CVF spectrophotometry of Pluto - Correlation of composition with albedo. [Circularly variable filter

    SciTech Connect

    Marcialis, R.L.; Lebofsky, L.A. Arizona Univ., Tucson )

    1991-02-01

    The present time-resolved, 0.96-2.65-micron spectrophotometry for the Pluto-Charon system indicates night-to-night variations in the depths of the methane absorptions such that the bands' equivalent width is near minimum light. The interpretation of these data in terms of a depletion of methane in dark regions of the planet, relative to bright ones, is consistent with the Buie and Fink (1987) observations. The near-IR spectrum of Pluto seems to be dominated by surface frost. It is suggested that the dark equatorial regions of Pluto are redder than those of moderate albedo. 28 refs.

  16. Spectrophotometry of the shell around AG Carinae

    NASA Technical Reports Server (NTRS)

    Mitra, P. Mila; Dufour, Reginald J.

    1990-01-01

    Spatially-resolved long-slit spectrophotometry are presented for two regions of the shell nebula around the P-Cygni variable star AG Carinae. The spectra cover the 3700-6800 A wavelength range. Emission-line diagnostics are used to derive extinction, electron temperatures, and densities for various positions in the nebula. The chemical abundances and ionization structure are calculated and compared with other types of planetary nebulae and shells around other luminous stars. It is found that the N/O and N/S ratios of Ag Car are high compared to solar neighborhood ISM values. The O/H depletion found for the AG Car shell approaches that found in the condensations of the Eta Car system.

  17. APM Z >=4 QSO Survey: Spectra and Intervening Absorption Systems

    NASA Astrophysics Data System (ADS)

    Storrie-Lombardi, L. J.; McMahon, R. G.; Irwin, M. J.; Hazard, C.

    1996-09-01

    The APM multicolor survey for bright z > 4 objects, covering 2500 deg^2^ of sky to m_r_ ~ 19, resulted in the discovery of 31 quasars with z ~> 4. High signal-to-noise optical spectrophotometry at 5 A resolution has been obtained for the 28 quasars easily accessible from the northern hemisphere. These spectra have been surveyed to create new samples of high-redshift Lyman-limit systems, damped Lyα absorbers, and metal absorption systems (e.g., C IV and Mg II). In this paper we present the spectra, together with line lists of the detected absorption systems. The QSOs display a wide variety of emission- and absorption-line characteristics, with five exhibiting broad absorption lines and one with extremely strong emission lines (BR 2248 - 1242). Eleven candidate damped Lyα absorption systems have been identified covering the redshift range 2.8 <= z <= 4.4 (eight with z > 3.5). An analysis of the measured redshifts of the high-ionization emission lines with the low-ionization lines shows them to be blueshifted by 430 +/- 60 km s^-1^. In a previous paper (by Storrie-Lombardi et al.) we discussed the redshift evolution of the Lyman limit systems cataloged here. In subsequent papers we will discuss the properties of the Lyα forest absorbers and the redshift and column density evolution of the damped Lyα absorbers.

  18. Near-infrared spectrophotometry of Titan

    NASA Technical Reports Server (NTRS)

    Trafton, L. M.

    1975-01-01

    Several unusual features in the near-IR spectrum of Titan are examined. Observations during four apparitions establish the reality of the S(1) absorption at 8150.7 A, but the existence of the S(O) absorption at 8272.7 A will require further sightings to become definitively established. These two features are particularly important, as they bear on the abundance of H2 in Titan's atmosphere.

  19. Noninvasive detection of plant nutrient stress using fiber optic spectrophotometry

    NASA Astrophysics Data System (ADS)

    Chen, Jun-Wei; Asundi, Anand K.; Liew, Oi Wah; Boey, William S. L.

    2001-05-01

    In a previous paper, we described the use of fiber optic spectrophotometry as a non-destructive and sensitive method to detect early symptoms of plant nutrient deficiency. We report further developments of our work on Brassica chinensis var parachinensis (Bailey) showing reproducibility of our data collected at a different seasonal period. Plants at the mid-log growth phase were subjected to nutrient stress by transferring them to nitrate- and calcium- deficient nutrient solution in a standing aerated hydroponic system. After tracking changes in leaf reflectance by FOSpectr for nine days, the plants were returned to complete nutrient solution and their recovery was monitored for a further nine days. The responses of nutrient stressed plants were compared with those grown under complete nutrient solution over the 18-day trial period. We also compared the sensitivity of FOSpectr detection against plant growth measurements vis-a-vis average leaf number and leaf width and show that the former method gave an indication of nutrient stress much earlier than the latter. In addition, this work indicated that while normal and nutrient-stressed plants could not be distinguished within the first 7 days by tracking plant growth indicators, stressed plants did show a clear decline in average leaf number and leaf width in later stages of growth even after the plants were returned to complete nutrient solution. The results further reinforce the need for early detection of nutrient stress, as late remedial action could not reverse the loss in plant growth in later stages of plant development.

  20. Use of β-correction spectrophotometry to improve the determination of copper solution with eriochrome black T

    NASA Astrophysics Data System (ADS)

    Gao, Hong-Wen

    1995-07-01

    Copper has been determined by β-correction spectrophotometry with eriochrome black T (EBT). This reaction is selective in the presence of EDTA to mask other metal ions. A non-ionic surfactant, polyethyleneglycol n-octanoic phenylether (emulsifying agent, OP), was found to increase the sensitivity. The β-correction method can completely eliminate the effect of excess EBT in its Cu 11 colored solution to give out the real absorpance of chelate produced. The sensitivity, precision and accuracy are increased. By means of the β-correction principle, the complex ratio of Cu 11 to EBT can be calculated as 1/2. Beer's law is obeyed over the range 0-2.0 mg l -1 copper at 550 nm and the true molar absorptivity of Cu-EBT chelate equals 2.61 × 10 4 l mol -1 cm -1. The detection limit of copper is 0.03 mg l -1 and the results show that the relative standard deviation was less than 4.5% with the recovery between 92.0 and 109%.

  1. Airborne infrared spectrophotometry of Mira variables

    NASA Technical Reports Server (NTRS)

    Strecker, D. W.; Erickson, E. F.; Witteborn, F. C.

    1978-01-01

    Airborne spectrophotometric observations of R Cas near minimum and maximum light, R Leo near minimum, and NML Tau near maximum are reported which were obtained over the wavelength range from 1.2 to 4 microns with 1.5% resolution. The spectral energy distributions of the three stars at the indicated times are presented, and it is shown that the H2O bands at 1.4, 1.9, and 2.7 microns are clearly evident in all the spectra, while the absorption bands of CO at about 1.6 and 2.3 microns are probably present although they are masked by the strong water vapor features. The results indicate that water vapor is the dominant opacity source in the atmospheres of Mira variables, that R Leo and NML Tau may be fitted well over the entire spectrum by respective single temperatures of 2250 and 1800 K, and that R Cas near both minimum and maximum cannot be adequately described by one temperature over the entire wavelength range investigated. The shapes and depths of the absorption bands are determined together with the apparent angular diameter of each star and the equivalent widths of the H2O + CO absorption bands. It is concluded that water vapor absorption is more strongly correlated with color temperature than with spectral type for R Cas and R Leo.

  2. Spectrophotometry of Kuiper Belt Objects and Centaurs

    NASA Astrophysics Data System (ADS)

    Lederer, S. M.; Vilas, F.

    2002-09-01

    We present an ongoing study of Kuiper Belt Objects (KBOs) and Centaurs. We acquired broadband (UBVRI) and medium band photometry with the 4m Mayall telescope at Kitt Peak and the 1.8m Perkins telescope at Lowell Observatory. We present broadband colors of these objects and discuss the results of our search for absorption bands in the visible spectral region. Vilas (Icarus, 111) demonstrated that the existence of the 0.7um absorption feature in asteroids with solar-like colors was strongly correlated with the presence of the 3.0um water of hydration feature. The broad 0.7um absorption band is attributed to a charge-transfer in Fe-bearing hydrated silicates (phyllosilicates), which are a product of aqueous alteration. For aqueous alteration to take place, one must have water ice present in an object, and an energy source to heat the water ice to a liquid water phase. Water ice has already been discovered in some Centaurs (Luu et al. ApJ, 531; Brown AJ, 119), and Durda and Stern (Icarus, 145) estimate that KBOs experience collisional processing regularly throughout their lifetimes. The estimated impact energies are high enough to induce aqueous alteration. We undertook this study to search for evidence of the 0.7um feature in KBOs and Centaurs. We employed medium band Windhorst filters, located at 0.527, 0.666, 0.705, 0.755 and 0.848 um in conjunction with the Mosaic CCD to search for this absorption band, which extends from 0.57-0.83um. Initial analysis suggests that an absorption feature exists near 0.7um in the greyer objects but not the redder objects, following the correlations observed in asteroids. These data are consistent with the absorption band detected near 0.7um by de Bergh et al. (ACM 2002, Berlin) in visible spectra of 2000 EB173 and 2000 GN171. However, further analysis is required to confirm whether the absorption we see is due to phyllosilicates or another source. We will present the results from this analysis. This research was supported through the

  3. [Comparison of two methods for determining G, A, M immunoglobulins (spectrophotometry and radial immunodiffusion)].

    PubMed

    Gamaleia, N B; Mondrus, K A

    1994-01-01

    Blood serum levels of immunoglobulins A, G, and M were measured by two methods, spectrophotometry and radial immunodiffusion. The results were in good correlation, this permitting the authors recommend spectrophotometry as a simpler and more objective method for such measurements.

  4. [Studies on the interaction between RNA with neutral red and determination of RNA by spectrophotometry].

    PubMed

    Si, Wen-Hui

    2007-06-01

    An analytical method for the determination of ribonucleic acid by spectrophotometry was established. At the maximum absorption wavelength for neutral red in B-R buffer solution, and under the best conditions, the decrease in the absorbance was linear with the amount of ribonucleic acid. The linearity range was 0.0-9.0 microg x mL(-1), the detection limit was 0.52 microg x mL(-1), and the correlation coeffient was 0.999 8. This method was simple, rapid, and selective. So its application to the determination of ribonucleic acid was satisfactory. The reaction mechanism was that the electrostatic interaction leads to molecular association of RNA with neutral red, resulting in anti-ion permutation and bonding reaction.

  5. Novel ratio difference at coabsorptive point spectrophotometric method for determination of components with wide variation in their absorptivities.

    PubMed

    Saad, Ahmed S; Abo-Talib, Nisreen F; El-Ghobashy, Mohamed R

    2016-01-05

    Different methods have been introduced to enhance selectivity of UV-spectrophotometry thus enabling accurate determination of co-formulated components, however mixtures whose components exhibit wide variation in absorptivities has been an obstacle against application of UV-spectrophotometry. The developed ratio difference at coabsorptive point method (RDC) represents a simple effective solution for the mentioned problem, where the additive property of light absorbance enabled the consideration of the two components as multiples of the lower absorptivity component at certain wavelength (coabsorptive point), at which their total concentration multiples could be determined, whereas the other component was selectively determined by applying the ratio difference method in a single step. Mixture of perindopril arginine (PA) and amlodipine besylate (AM) figures that problem, where the low absorptivity of PA relative to AM hinders selective spectrophotometric determination of PA. The developed method successfully determined both components in the overlapped region of their spectra with accuracy 99.39±1.60 and 100.51±1.21, for PA and AM, respectively. The method was validated as per the USP guidelines and showed no significant difference upon statistical comparison with reported chromatographic method.

  6. Moderate resolution spectrophotometry of high redshift quasars

    NASA Technical Reports Server (NTRS)

    Schneider, Donald P.; Schmidt, Maarten; Gunn, James E.

    1991-01-01

    A uniform set of photometry and high signal-to-noise moderate resolution spectroscopy of 33 quasars with redshifts larger than 3.1 is presented. The sample consists of 17 newly discovered quasars (two with redshifts in excess of 4.4) and 16 sources drawn from the literature. The objects in this sample have r magnitudes between 17.4 and 21.4; their luminosities range from -28.8 to -24.9. Three of the 33 objects are broad absorption line quasars. A number of possible high redshift damped Ly-alpha systems were found.

  7. "The Show"

    ERIC Educational Resources Information Center

    Gehring, John

    2004-01-01

    For the past 16 years, the blue-collar city of Huntington, West Virginia, has rolled out the red carpet to welcome young wrestlers and their families as old friends. They have come to town chasing the same dream for a spot in what many of them call "The Show". For three days, under the lights of an arena packed with 5,000 fans, the…

  8. Study of the impact of mechanical treatments on wastewater solids by UV spectrophotometry.

    PubMed

    Berho, C; Pouet, M F; Thomas, O

    2003-12-01

    The aim of this paper is, from the perspective of improvement of Total Suspended Solids (TSS) measurement by UV spectrophotometry, to study the influence of two pretreatments on the UV responses of urban wastewater (sonication and mechanical grinding). The study of optical properties evolution the different phenomena involved and show mechanical grinding as a potential pre-treatment is prosed. Mechanical grinding is applied to samples characterised by different TSS concentration and particle size distributions in order to test its feasability. Results show the limit of the pretreatment and the difficulty of exploiting the UV response of urban wastewater for TSS characterization and estimation.

  9. Spatial variability of absorption properties in Lake Balaton, Hungary

    NASA Astrophysics Data System (ADS)

    Riddick, C. A.; Hunter, P. D.; Tyler, A. N.; Vicente, V. M.; Groom, S.; Horváth, H.; Kovacs, A.; Preston, T.; Presing, M.

    2013-12-01

    In order to improve robustness of current remote sensing algorithms for lake monitoring, it is vital to understand the variability of inherent optical properties (IOPs) within a lake. In this study, absorption coefficients were measured in situ at 38 stations in Lake Balaton, Hungary, using a WET Labs AC-S and AC-9 and compared to concurrent absorption measurements by dual beam spectrophotometry in the laboratory. The spatial variability of bulk and chlorophyll-specific absorption coefficients was examined across 5 basins, demonstrating a gradient in total absorption corresponding to the trophic gradient. Our data suggests that sampling conditions had an impact on particulate absorption, affecting the proportion attributed to non-algal particles (aNAP), phytoplankton (aph) or color dissolved organic matter (aCDOM). The specific absorption of phytoplankton (a*ph) spectra showed a distinct peak in the UV portion of the spectra in Basins 3 and 4 (east), which may be due to the presence of phytoplankton photoprotective pigments to compensate for lower CDOM levels in these basins. In contrast to oceans, particulate attenuation (cp) had a weaker relationship to chlorophyll-a (R2=0.15) than to total suspended matter (R2=0.84), particularly the inorganic fraction. Additionally, the relative contribution of particulate scattering (bp) to attenuation was significantly higher in Lake Balaton (up to 85-99%) than that found in previous lacustrine studies. bp also demonstrated a gradient across the lake, where values increased as the water progressed from phytoplankton-dominated to mineral-dominated. These results provide knowledge of the heterogeneity of the IOPs within Lake Balaton, which is to be considered for the future improvement of bio-optical algorithms for constituent retrieval in inland waters.

  10. A Computer-aided Learning Exercise in Spectrophotometry.

    ERIC Educational Resources Information Center

    Pamula, Frederick

    1994-01-01

    Discusses the use of a computer simulation program in teaching the concepts of spectrophotometry. Introduces several parts of the program and program usage. Presents an assessment activity to evaluate students' mastery of material. Concludes with the advantages of this approach to the student and to the assessor. (ASK)

  11. Evolution of Instrumentation for UV-Visible Spectrophotometry. Part I.

    ERIC Educational Resources Information Center

    Altemose, Ines R.

    1986-01-01

    Traces the development of instruments used in spectrophotometry. Discusses how spectrophotometric measurements are made. Describes the color comparator, the filter photometer, and the spectrophotometer. Outlines the evolution of optical systems, including light sources, the monochromator, the photodetector, double-beam optics, and split-beam…

  12. Ion Exchange Chromatography and Spectrophotometry: An Introductory Undergraduate Laboratory Experiment.

    ERIC Educational Resources Information Center

    Foster, N.; And Others

    1985-01-01

    Describes an experiment in which students use ion exchange chromatography to separate a mixture of chloro complexes of transition metal ions and then use spectrophotometry to define qualitatively the efficiency of the ion exchange columns. Background information, materials needed, and procedures used are included. (JN)

  13. Wavelength Anomalies in UV-Vis Spectrophotometry

    NASA Astrophysics Data System (ADS)

    Tellinghuisen, J.

    2012-06-01

    Commercial spectrophotometers are great tools for recording absorption spectra of low-to-moderate resolution and high photometic quality. However, in the case of at least one such instrument, the Shimadzu UV-2101PC (and by assumption, similar Shimadzu models), the wavelength accuracy may not match the photometric accuracy. In fact the wavelength varies with slit width, spectral sampling interval, and even the specified range, with a smoothing algorithm invoked any time the spectrum includes more than 65 sampled wavelengths. This behavior appears not to be documented anywhere, but it has been present for at least 20 years and persists even in the latest software available to run the instrument. The wavelength shifts can be as large as 1 nm, so for applications where wavelength accuracy better than this is important, wavelength calibration must be done with care to ensure that the results are valid for the parameters used to record the target spectra.

  14. Spectrophotometry-based detection of carbapenemase producers among Enterobacteriaceae.

    PubMed

    Bernabeu, Sandrine; Poirel, Laurent; Nordmann, Patrice

    2012-09-01

    Carbapenem-hydrolyzing ß-lactamases are the most powerful ß-lactamases being able to hydrolyse almost all ß-lactams. They are mostly of the KPC, VIM, IMP, NDM, and OXA-48 type. A spectrophotometry technique based on analysis of the imipenem hydrolysis has been developed that differentiated carbapenemase- from noncarbapenemase producers. This inexpensive technique adapted to screening of carbapenemase producers may be implemented in any reference laboratory worldwide.

  15. Speech therapy changes blood circulation and oxygenation in the brain and muscle: a near-infrared spectrophotometry study.

    PubMed

    Wolf, Martin; von Bonin, Dietrich; Wolf, Ursula

    2011-01-01

    Recently it has been shown that artistic speech therapy (AST) has effects on heart rate variability. The aim of this pilot study was to investigate whether AST also affects hemodynamics and tissue oxygenation in the brain and skeletal muscle measured by near infrared spectrophotometry(NIRS). The results show that ATS has effects on important physiological parameters, i.e., it leads to a decrease in cerebral blood flow during recitation and to brain activation thereafter.

  16. Airborne stellar spectrophotometry from 1.2 to 5.5 microns - Absolute calibration and spectra of stars earlier than M3

    NASA Technical Reports Server (NTRS)

    Strecker, D. W.; Erickson, E. F.; Witteborn, F. C.

    1979-01-01

    Airborne infrared spectrophotometry (1.2-5.5 microns, 1.5% resolution) is presented for 13 stars which have been extensively used as infrared calibration objects: alpha Lyr, alpha CMA, alpha UMi, beta Dra, and mu Her; the K giants beta Gem, alpha UMa, alpha Boo, gamma-1 And, and alpha Tau; and the M giants beta And, beta Peg, and alpha Cet. These spectra, obtained using NASA's Kuiper Airborne Observatory and Lear Jet Observatory, are virtually free of the interfering effects of terrestrial absorptions. Absolute calibration of the spectrophotometry was based on the theoretical model of alpha Lyr by Schild, Peterson, and Oke (1971), which fits photometric measurements at shorter wavelengths. The resulting flux densities are compared with previous ground-based photometry.

  17. Detection of silver nanoparticles in seawater at ppb levels using UV-visible spectrophotometry with long path cells.

    PubMed

    Lodeiro, Pablo; Achterberg, Eric P; El-Shahawi, Mohammad S

    2017-03-01

    Silver nanoparticles (AgNPs) are emerging contaminants that are difficult to detect in natural waters. UV-visible spectrophotometry is a simple technique that allows detection of AgNPs through analysis of their characteristic surface plasmon resonance band. The detection limit for nanoparticles using up to 10cm path length cuvettes with UV-visible spectrophotometry is in the 0.1-10ppm range. This detection limit is insufficiently low to observe AgNPs in natural environments. Here we show how the use of capillary cells with an optical path length up to 200cm, forms an excellent technique for rapid detection and quantification of non-aggregated AgNPs at ppb concentrations in complex natural matrices such as seawater.

  18. Comparative study between univariate spectrophotometry and multivariate calibration as analytical tools for quantitation of Benazepril alone and in combination with Amlodipine.

    PubMed

    Farouk, M; Elaziz, Omar Abd; Tawakkol, Shereen M; Hemdan, A; Shehata, Mostafa A

    2014-04-05

    Four simple, accurate, reproducible, and selective methods have been developed and subsequently validated for the determination of Benazepril (BENZ) alone and in combination with Amlodipine (AML) in pharmaceutical dosage form. The first method is pH induced difference spectrophotometry, where BENZ can be measured in presence of AML as it showed maximum absorption at 237nm and 241nm in 0.1N HCl and 0.1N NaOH, respectively, while AML has no wavelength shift in both solvents. The second method is the new Extended Ratio Subtraction Method (EXRSM) coupled to Ratio Subtraction Method (RSM) for determination of both drugs in commercial dosage form. The third and fourth methods are multivariate calibration which include Principal Component Regression (PCR) and Partial Least Squares (PLSs). A detailed validation of the methods was performed following the ICH guidelines and the standard curves were found to be linear in the range of 2-30μg/mL for BENZ in difference and extended ratio subtraction spectrophotometric method, and 5-30 for AML in EXRSM method, with well accepted mean correlation coefficient for each analyte. The intra-day and inter-day precision and accuracy results were well within the acceptable limits.

  19. Technical note: comparing von Luschan skin color tiles and modern spectrophotometry for measuring human skin pigmentation.

    PubMed

    Swiatoniowski, Anna K; Quillen, Ellen E; Shriver, Mark D; Jablonski, Nina G

    2013-06-01

    Prior to the introduction of reflectance spectrophotometry into anthropological field research during the 1950s, human skin color was most commonly classified by visual skin color matching using the von Luschan tiles, a set of 36 standardized, opaque glass tiles arranged in a chromatic scale. Our goal was to establish a conversion formula between the tile-based color matching method and modern reflectance spectrophotometry to make historical and contemporary data comparable. Skin pigmentation measurements were taken on the forehead, inner upper arms, and backs of the hands using both the tiles and a spectrophotometer on 246 participants showing a broad range of skin pigmentation. From these data, a second-order polynomial conversion formula was derived by jackknife analysis to estimate melanin index (M-index) based on tile values. This conversion formula provides a means for comparing modern data to von Luschan tile measurements recorded in historical reports. This is particularly important for populations now extinct, extirpated, or admixed for which tile-based measures of skin pigmentation are the only data available.

  20. Chemometrics-assisted spectrophotometry method for the determination of chemical oxygen demand in pulping effluent.

    PubMed

    Chen, Honglei; Chen, Yuancai; Zhan, Huaiyu; Fu, Shiyu

    2011-04-01

    A new method has been developed for the determination of chemical oxygen demand (COD) in pulping effluent using chemometrics-assisted spectrophotometry. Two calibration models were established by inducing UV-visible spectroscopy (model 1) and derivative spectroscopy (model 2), combined with the chemometrics software Smica-P. Correlation coefficients of the two models are 0.9954 (model 1) and 0.9963 (model 2) when COD of samples is in the range of 0 to 405 mg/L. Sensitivities of the two models are 0.0061 (model 1) and 0.0056 (model 2) and method detection limits are 2.02-2.45 mg/L (model 1) and 2.13-2.51 mg/L (model 2). Validation experiment showed that the average standard deviation of model 2 was 1.11 and that of model 1 was 1.54. Similarly, average relative error of model 2 (4.25%) was lower than model 1 (5.00%), which indicated that the predictability of model 2 was better than that of model 1. Chemometrics-assisted spectrophotometry method did not need chemical reagents and digestion which were required in the conventional methods, and the testing time of the new method was significantly shorter than the conventional ones. The proposed method can be used to measure COD in pulping effluent as an environmentally friendly approach with satisfactory results.

  1. Far ultraviolet spectrophotometry of BD +28 4211

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  2. Far-ultraviolet spectrophotometry of Spica

    NASA Technical Reports Server (NTRS)

    Cook, Timothy A.; Cash, Webster; Snow, Theodore P.

    1989-01-01

    A spectrum of the star Spica (Alpha Virginis) from 960 to 1270 A was recorded by a rocket-borne spectrograph March 13, 1988. The spectrum, which has 3.4 A resolution, shows a much sharper drop-off in intensity near 1050 A than similar measurements made by the Voyager UVS, but is in good agreement with the spectrum obtained by Brune et al. in a 1977 sounding rocket. The disagreement with Voyager is a factor of 1.5 at 1100 A and grows to a factor of 5.7 at 960 A. This implies that the photometric standards between 912 and 1100 A may need some revision, and that the standard photospheric models for hot stars may err significantly near the Lyman limit.

  3. Occultation Spectrophotometry of Extrasolar Planets with SOFIA

    NASA Technical Reports Server (NTRS)

    Angerhausen, Daniel; Huber, Klaus F.; Mandell, Avi M.; McElwain, Michael W.; Czesla, Stefan; Madhusudhan, Nikku

    2012-01-01

    The NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA), a 2.5- meter infrared telescope on board a Boeing 747-SP, will conduct 0.3 - 1,600 micrometer photometric, spectroscopic, and imaging observations from altitudes as high as 45,000 ft., where the average atmospheric transmission is greater than 80 percent. SOFIA's first light cameras and spectrometers, as well as future generations of instruments, will make important contributions to the characterization of the physical properties of exoplanets. Our analysis shows that optical and near-infrared photometric and spectrophotometric follow-up observations during planetary transits and eclipses will be feasible with SOFIA's instrumentation, in particular the HIPOFLITECAM optical/NIR instruments. The airborne-based platform has unique advantages in comparison to ground- and space-based observatories in this field of research which we will outline here. Furthermore we will present two exemplary science cases, that will be conducted in SOFIA's cycle 1.

  4. Occultation Spectrophotometry of Extrasolar Planets with SOFIA

    NASA Astrophysics Data System (ADS)

    Angerhausen, Daniel; Huber, Klaus F.; Mandell, Avi M.; McElwain, Michael W.; Czesla, Stefan; Madhusudhan, Nikku; Morse, Jon A.

    2014-04-01

    The NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA), a 2.5-meter infrared telescope on board a Boeing 747-SP, will conduct 0.3 - 1,600 μm photometric, spectroscopic, and imaging observations from altitudes as high as 45,000 ft., where the average atmospheric transmission is greater than 80 percent. SOFIA's first light cameras and spectrometers, as well as future generations of instruments, will make important contributions to the characterization of the physical properties of exoplanets. Our analysis shows that optical and near-infrared photometric and spectrophotometric follow-up observations during planetary transits and eclipses will be feasible with SOFIA's instrumentation, in particular the HIPO-FLITECAM optical/NIR instruments. The airborne-based platform has unique advantages in comparison to ground- and space-based observatories in this field of research which we will outline here. Furthermore we will present two exemplary science cases, that will be conducted in SOFIA's cycle 1.

  5. Determination of niobium in rocks, ores and alloys by atomic-absorption spectrophotometry.

    PubMed

    Husler, J

    1972-07-01

    Niobium, in concentrations as low as 0.02% Nb(2)O(5), is determined in a variety of materials without separation or enrichment. Chemical and ionization interferences are controlled, and sensitivity is increased, by maintaining the iron, aluminium, hydrofluoric acid and potassium content within certain broad concentration limits. There is close agreement with the results of analyses by emission spectrographic, electron microprobe and X-ray fluorescence methods.

  6. Determination of Trace Elements in Nickel Base Alloys by Atomic Absorption Spectrophotometry.

    DTIC Science & Technology

    elements such as silver (Ag), bismuth (Bi), cadmium (Cd), lead ( Pb ), phosphorus (P), and arsenic (As) in nickel alloys such as Udimet 500 without interference of other constituent elements. (Author)

  7. Determination of Trace Elements in Nickel Base Gas Turbine Parts by Atomic Absorption Spectrophotometry.

    DTIC Science & Technology

    elements such as silver (Ag), bismuth (Bi), cadmium (Cd), and lead (Pb) in nickel base alloys such as IN100, B1900 and 713C , without interference from...the constituent elements. Failed and nonfailed gas turbine parts made of the above alloys were tested to ascertain whether trace amounts of these

  8. Ultraviolet spectrophotometry from Gemini 11 of stars in Orion

    NASA Technical Reports Server (NTRS)

    Morgan, T. H.; Spear, G. G.; Kondo, Y.; Henize, K. G.

    1975-01-01

    Ultraviolet spectrophotometry in the wavelength region 2600-3600 A is reported for the bright early-type stars beta, eta, gamma, delta, iota, epsilon, sigma, zeta, and kappa Ori. The results are in good agreement with other observations, and, with the possible exception of the supergiants, are in good agreement with recent line-blanketed model atmospheres. There is evidence that the supergiants possess a small ultraviolet deficiency shortward of 3000 A relative to main-sequence stars of similar spectral type. The most extreme example of this phenomenon is the star kappa Ori.

  9. The Use of Erythrosin B in Undergraduate Spectrophotometry Experiments

    NASA Astrophysics Data System (ADS)

    Stock, L. James, III

    1995-10-01

    The CMU chemistry department has met regulatory and waste disposal concerns by using a non-toxic food color in a general chemistry experiment. Erythrosin B was found to be a suitable alternative to Sodium Dichromate when teaching solution preparation and the principles of spectrophotometry. Students weigh a small mass of Erythrosin B and prepare several solutions that are measured in a spectrophotometer. From these a Beer's Law plot is constructed. Finally, concentrations of unknown solutions are determined using the spectrophotometer and the Beer's Law plot.

  10. Quantitation of heparosan with heparin lyase III and spectrophotometry.

    PubMed

    Huang, Haichan; Zhao, Yingying; Lv, Shencong; Zhong, Weihong; Zhang, Fuming; Linhardt, Robert J

    2014-02-15

    Heparosan is Escherichia coli K5 capsule polysaccharide, which is the key precursor for preparing bioengineered heparin. A rapid and effective quantitative method for detecting heparosan is important in the large-scale production of heparosan. Heparin lyase III (Hep III) effectively catalyzes the heparosan depolymerization, forming unsaturated disaccharides that are measurable using a spectrophotometer at 232 nm. We report a new method for the quantitative detection of heparosan with heparin lyase III and spectrophotometry that is safer and more specific than the traditional carbazole assay. In an optimized detection system, heparosan at a minimum concentration of 0.60 g/L in fermentation broth can be detected.

  11. A sensitive, spatially uniform photodetector for broadband infrared spectrophotometry

    SciTech Connect

    Iglesias, Enrique J.; Smith, Allan W.; Kaplan, Simon G

    2008-05-01

    We describe the design and performance of a liquid helium-cooled As:Si blocked-impurity-band photodetector system intended for spectrophotometry in the thermal infrared (2 to 30 {mu}m) spectral region. The system has been characterized for spectral sensitivity, noise, thermal stability, and spatial uniformity, and optimized for use with a Fourier-transform infrared spectrophotometer source for absolute goniometric reflectance measurements. Its performance is evaluated and compared to more common detector systems used in this spectral region, including room-temperature pyroelectric and liquid-N2-cooled photoconductive devices.

  12. Method for rapidly determining a pulp kappa number using spectrophotometry

    DOEpatents

    Chai, Xin-Sheng; Zhu, Jun Yong

    2002-01-01

    A system and method for rapidly determining the pulp kappa number through direct measurement of the potassium permanganate concentration in a pulp-permanganate solution using spectrophotometry. Specifically, the present invention uses strong acidification to carry out the pulp-permanganate oxidation reaction in the pulp-permanganate solution to prevent the precipitation of manganese dioxide (MnO.sub.2). Consequently, spectral interference from the precipitated MnO.sub.2 is eliminated and the oxidation reaction becomes dominant. The spectral intensity of the oxidation reaction is then analyzed to determine the pulp kappa number.

  13. Low resolution ultraviolet and optical spectrophotometry of symbiotic stars

    NASA Technical Reports Server (NTRS)

    Slovak, M. H.

    1982-01-01

    Low resolution International Ultraviolet Explorer spectra combined with optical spectrophotometry provide absolute flux distributions for seven symbiotic variables from 1200 to 6450 A. For five stars (EG And, BF Cyg, CI Cyg, AG Peg, and Z And) the data are representative of the quiescent/out-of-eclipse energy distributions; for CH Cyg and AX Per, the observations were obtained following their atest outburst in 1977 and 1978, respectively. The de-reddened distributions reveal a remarkable diversity of both line spectra and continua. While the optical and near infrared regions lambda = 5500 A) are well represented by single component stellar models, multicomponent flux distributions are required to reproduce the ultraviolet continua.

  14. Determination of glucosinolates in 19 Chinese medicinal plants with spectrophotometry and high-pressure liquid chromatography.

    PubMed

    Hu, Ye; Liang, Hao; Yuan, Qipeng; Hong, Yuancheng

    2010-08-01

    Glucosinolates were evaluated in 19 traditional Chinese medicinal plants involved in seven different families: Brassicaceae, Capparaceae, Euphorbiaceae, Phytolaccaceae, Tropaeolaceae, Caricaceae and Rubiaceae. The total glucosinolate contents were determined by spectrophotometry. Results showed that the high contents of total glucosinolates were found in some herbs of Brassicaceae, Capparaceae and Euphorbiaceae families, while low total glucosinolate contents were observed in two Rubiaceae herbs. In addition, eight glucosinolates (glucoraphanin, glucoraphenin, sinalbin, sinigrin, progoitrin, 4-hydroglucobrassicin, glucoiberin and glucoibervirin) in these herbs were measured using HPLC, and the data showed that individual glucosinolates and their contents varied at different degrees among the distinct species. The highest contents of cancer-protective compounds were found in the seeds of Raphanus sativus L. (glucoraphenin), Sinapis alba (sinalbin) and Phyllanthus emblica L. (sinigrin).

  15. Determination of thiamazole in pharmaceutical samples by phosphorus molybdenum blue spectrophotometry.

    PubMed

    Huo, Jing'e; Li, Quanmin

    2012-02-15

    A novel method is established to determine thiamazole by phosphorus molybdenum blue spectrophotometry. The experiment indicates that PO(4)(3-) reacts with Mo(7)O(24)(6-) in 0.30mol/L H(2)SO(4) solution to form a product with phosphorus-molybdenum heteropoly acid ([H(2)PMo(12)O(40)](-)). Then [H(2)PMo(12)O(40)](-) is deoxidized to form phosphorus molybdenum blue (H(3)PO(4)·10MoO(3)·Mo(2)O(5)) by thiamazole. The amount of thiamazole can be determined based on the absorbance of phosphorus molybdenum blue (λ(max)=710nm). A good linear relationship is obtained between the absorbance and the concentration of thiamazole in the range of 0.035-70μg/mL. The equation of the linear regression is A=0.03384+0.00834c (μg/mL), with a linear correlation coefficient of 0.9990. The apparent molar absorption coefficient is 1.0×10(3)L/(molcm). The method has been successfully applied to the determination of thiamazole in pharmaceutical samples with satisfactory results, and recoveries are in the range of 99.6-100.6%.

  16. Optical and infrared spectrophotometry of the symbiotic system V1016 Cygni

    NASA Technical Reports Server (NTRS)

    Rudy, Richard J.; Rossano, George S.; Cohen, Ross D.; Puetter, R. C.

    1990-01-01

    Spectrophotometry from 0.46 to 1.3 micron of the peculiar emission-line object V1016 Cyg is presented. The optical region displays a weak continuum underlying the rich emission-line spectrum detailed in past studies. The infrared spectrum consists of prominent emission lines of H I, He I, He II, forbidden Ni, O I, and forbidden S III overlying a strong stellar continuum. The latter displays bands at 0.94 micron and 1.13 micron characteristic of a late-type, oxygen-rich giant as well as an absorption at 1.05 micron which is due to VO. The presence of these molecular features indicates a spectral class of M6 or later for the cool secondary. The reddening of the secondary does not appear to be much different from that of the emission lines. Among the infrared emission features is the rarely seen permitted transition of neutral oxygen at 1.1287 micron. Its presence at a strength comparable to O I 8446 A, together with the absence of O I 13164 A, confirms the result of Strafella that the strong O I lines arise primarily from fluorescent excitation by Ly-beta.

  17. Determination of boron in uranium aluminum silicon alloy by spectrophotometry and estimation of expanded uncertainty in measurement

    NASA Astrophysics Data System (ADS)

    Ramanjaneyulu, P. S.; Sayi, Y. S.; Ramakumar, K. L.

    2008-08-01

    Quantification of boron in diverse materials of relevance in nuclear technology is essential in view of its high thermal neutron absorption cross section. A simple and sensitive method has been developed for the determination of boron in uranium-aluminum-silicon alloy, based on leaching of boron with 6 M HCl and H 2O 2, its selective separation by solvent extraction with 2-ethyl hexane 1,3-diol and quantification by spectrophotometry using curcumin. The method has been evaluated by standard addition method and validated by inductively coupled plasma-atomic emission spectroscopy. Relative standard deviation and absolute detection limit of the method are 3.0% (at 1 σ level) and 12 ng, respectively. All possible sources of uncertainties in the methodology have been individually assessed, following the International Organization for Standardization guidelines. The combined uncertainty is calculated employing uncertainty propagation formulae. The expanded uncertainty in the measurement at 95% confidence level (coverage factor 2) is 8.840%.

  18. Fiber optic spectrophotometry monitoring of plant nutrient deficiency under hydroponic culture conditions

    NASA Astrophysics Data System (ADS)

    Liew, Oi Wah; Boey, William S. L.; Asundi, Anand K.; Chen, Jun-Wei; He, Duo-Min

    1999-05-01

    In this paper, fiber optic spectrophotometry (FOSpectr) was adapted to provide early detection of plant nutrient deficiency by measuring leaf spectral reflectance variation resulting from nutrient stress. Leaf reflectance data were obtained form a local vegetable crop, Brassica chinensis var parachinensis (Bailey), grown in nitrate-nitrogen (N)- and calcium (Ca)- deficient hydroponics nutrient solution. FOSpectr analysis showed significant differences in leaf reflectance within the first four days after subjecting plants to nutrient-deficient media. Recovery of the nutrient-stressed plants could also be detected after transferring them back to complete nutrient solution. In contrast to FOSpectr, plant response to nitrogen and calcium deficiency in terms of reduced growth and tissue elemental levels was slower and less pronounced. Thus, this study demonstrated the feasibility of using FOSpectr methodology as a non-destructive alternative to augment current methods of plant nutrient analysis.

  19. (21) Lutetia spectrophotometry from Rosetta-OSIRIS images and comparison to ground-based observations

    NASA Astrophysics Data System (ADS)

    Magrin, S.; La Forgia, F.; Pajola, M.; Lazzarin, M.; Massironi, M.; Ferri, F.; da Deppo, V.; Barbieri, C.; Sierks, H.; Osiris Team

    2012-06-01

    Here we present some preliminary results on surface variegation found on (21) Lutetia from ROSETTA-OSIRIS images acquired on 2010-07-10. The spectrophotometry obtained by means of the two cameras NAC and WAC (Narrow and Wide Angle Cameras) is consistent with ground based observations, and does not show surface diversity above the data error bars. The blue and UV images (shortward 500 nm) may, however, indicate a variegation of the optical properties of the asteroid surface on the Baetica region (Sierks et al., 2011). We also speculate on the contribution due to different illumination and to different ground properties (composition or, more probably, grain size diversity). In particular a correlation with geologic units independently defined by Massironi et al. (2012) is evident, suggesting that the variegation of the ground optical properties is likely to be real.

  20. A quantitative and qualitative method to control chemotherapeutic preparations by Fourier transform infrared-ultraviolet spectrophotometry.

    PubMed

    Dziopa, Florian; Galy, Guillaume; Bauler, Stephanie; Vincent, Benoit; Crochon, Sarah; Tall, Mamadou Lamine; Pirot, Fabrice; Pivot, Christine

    2013-06-01

    Chemotherapy products in hospitals include a reconstitution step of manufactured drugs providing an adapted dosage to each patient. The administration of highly iatrogenic drugs raises the question of patients' safety and treatment efficiency. In order to reduce administration errors due to faulty preparations, we introduced a new qualitative and quantitative routine control based on Fourier Transform Infrared (FTIR) and UV-Visible spectrophotometry. This automated method enabled fast and specific control for 14 anticancer drugs. A 1.2 mL sample was used to assay and identify each preparation in less than 90 sec. Over a two-year period, 9370 controlled infusion bags showed a 1.49% nonconformity rate, under 15% tolerance from the theoretical concentration and 96% minimum identification matching factor. This study evaluated the reliability of the control process, as well as its accordance to chemotherapy deliverance requirements. Thus, corrective measures were defined to improve the control process.

  1. Complexation of Lactate with Nd(III) and Eu(III) at Variable Temperatures: Studies by Potentiometry, Microcalorimetry, Optical Absorption and Luminescence Spectroscopy

    SciTech Connect

    Tian, Guoxin; Martin, Leigh R.; Rao, Linfeng

    2010-10-01

    Complexation of neodymium(III) and europium(III) with lactate was studied at variable temperatures by potentiometry, absorption spectrophotometry, luminescence spectroscopy and microcalorimetry. Stability constants of three successive lactate complexes (ML{sup 2+}, ML{sup 2+} and ML{sub 3}(aq), where M stands for Nd and Eu, and L stands for lactate) at 10, 25, 40, 55 and 70 C were determined. The enthalpies of complexation at 25 C were determined by microcalorimetry. Thermodynamic data show that the complexation of trivalent lanthanides (Nd{sup 3+} and Eu{sup 3+}) with lactate is exothermic, and the complexation becomes weaker at higher temperatures. Results from optical absorption and luminescence spectroscopy suggest that the complexes are inner-sphere chelate complexes in which the protonated {alpha}-hydroxyl group of lactate participates in the complexation.

  2. Petawatt laser absorption bounded

    PubMed Central

    Levy, Matthew C.; Wilks, Scott C.; Tabak, Max; Libby, Stephen B.; Baring, Matthew G.

    2014-01-01

    The interaction of petawatt (1015 W) lasers with solid matter forms the basis for advanced scientific applications such as table-top particle accelerators, ultrafast imaging systems and laser fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light f, and even the range of f is unknown. Here using a relativistic Rankine-Hugoniot-like analysis, we show for the first time that f exhibits a theoretical maximum and minimum. These bounds constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials. PMID:24938656

  3. Spectrophotometry of comets Giacobini-Zinner and Halley

    NASA Technical Reports Server (NTRS)

    Tegler, Stephen C.; O'Dell, C. R.

    1987-01-01

    Optical window spectrophotometry was performed on comets Giacobini-Zinner and Halley over the interval 300-1000 nm. Band and band-sequence fluxes were obtained for the brightest features of OH, CN, NH, and C2, special care having been given to determinations of extinction, instrumental sensitivities, and corrections for Fraunhofer lines. C2 Swan band-sequence flux ratios were determined with unprecedented accuracy and compared with the predictions of the detailed equilibrium models of Krishna Swamy et al. (1977, 1979, 1981, and 1987). It is found that these band sequences do not agree with the predictions, which calls into question the assumptions made in deriving the model, namely resonance fluorescence statistical equilibrium. Suggestions are made as to how to resolve this discrepancy.

  4. 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…

  5. The role of the surfaces in the photon absorption in Ge nanoclusters embedded in silica

    NASA Astrophysics Data System (ADS)

    Cosentino, Salvatore; Mirabella, Salvatore; Miritello, Maria; Nicotra, Giuseppe; Lo Savio, Roberto; Simone, Francesca; Spinella, Corrado; Terrasi, Antonio

    2011-12-01

    The usage of semiconductor nanostructures is highly promising for boosting the energy conversion efficiency in photovoltaics technology, but still some of the underlying mechanisms are not well understood at the nanoscale length. Ge quantum dots (QDs) should have a larger absorption and a more efficient quantum confinement effect than Si ones, thus they are good candidate for third-generation solar cells. In this work, Ge QDs embedded in silica matrix have been synthesized through magnetron sputtering deposition and annealing up to 800°C. The thermal evolution of the QD size (2 to 10 nm) has been followed by transmission electron microscopy and X-ray diffraction techniques, evidencing an Ostwald ripening mechanism with a concomitant amorphous-crystalline transition. The optical absorption of Ge nanoclusters has been measured by spectrophotometry analyses, evidencing an optical bandgap of 1.6 eV, unexpectedly independent of the QDs size or of the solid phase (amorphous or crystalline). A simple modeling, based on the Tauc law, shows that the photon absorption has a much larger extent in smaller Ge QDs, being related to the surface extent rather than to the volume. These data are presented and discussed also considering the outcomes for application of Ge nanostructures in photovoltaics. PACS: 81.07.Ta; 78.67.Hc; 68.65.-k

  6. Magnetic resonance cell-tracking studies: spectrophotometry-based method for the quantification of cellular iron content after loading with superparamagnetic iron oxide nanoparticles.

    PubMed

    Böhm, Ingrid

    2011-08-01

    The purpose of this article is to present a user-friendly tool for quantifying the iron content of superparamagnetic labeled cells before cell tracking by magnetic resonance imaging (MRI). Iron quantification was evaluated by using Prussian blue staining and spectrophotometry. White blood cells were labeled with superparamagnetic iron oxide (SPIO) nanoparticles. Labeling was confirmed by light microscopy. Subsequently, the cells were embedded in a phantom and scanned on a 3 T magnetic resonance tomography (MRT) whole-body system. Mean peak wavelengths λ(peak) was determined at A(720 nm) (range 719-722 nm). Linearity was proven for the measuring range 0.5 to 10 μg Fe/mL (r  =  .9958; p  =  2.2 × 10(-12)). The limit of detection was 0.01 μg Fe/mL (0.1785 mM), and the limit of quantification was 0.04 μg Fe/mL (0.714 mM). Accuracy was demonstrated by comparison with atomic absorption spectrometry. Precision and robustness were also proven. On T(2)-weighted images, signal intensity varied according to the iron concentration of SPIO-labeled cells. Absorption spectrophotometry is both a highly sensitive and user-friendly technique that is feasible for quantifying the iron content of magnetically labeled cells. The presented data suggest that spectrophotometry is a promising tool for promoting the implementation of magnetic resonance-based cell tracking in routine clinical applications (from bench to bedside).

  7. Airborne 20-65 micron spectrophotometry of Comet Halley

    NASA Technical Reports Server (NTRS)

    Glaccum, William; Moseley, S. H.; Campins, Humberto C.; Loewenstein, R. F.

    1988-01-01

    Observations of Comet Halley with a grating spectrometer on board the Kuiper Airborne Observatory on four nights in Dec. 1985 to Apr. 1986 are reported. Low resolution 20 to 65 micrometer spectra of the nucleus with a 40 arcsec FWHM beam was obtained on 17 Dec. 1985, and on 15 and 17 Apr. 1986. On 20 Dec. 1985, only a 20 to 35 micrometer spectrum was obtained. Most of the data have been discussed in a paper where the continuum was dealt with. In that paper, models were fit to the continuum that showed that more micron sized particles of grain similar to amorphous carbon were needed to fit the spectrum than were allowed by the Vega SP-2 mass distribution, or that a fraction of the grains had to be made out of a material whose absorption efficiency fell steeper than lambda sup -1 for lambda greater than 20 micrometers. Spectra was also presented taken at several points on the coma on 15 Apr. which showed that the overall shape to the spectrum is the same in the coma. Tabulated values of the data and calibration curves are available. The spectral features are discussed.

  8. View from My Classroom: A Spectrophotometry Unit for Advanced Chemistry Students.

    ERIC Educational Resources Information Center

    Diehl-Jones, Susan M.

    1983-01-01

    Rationale, objectives, and instructional strategies for a directed study course on spectrophotometry are provided. Descriptions of three experiments and four student research projects are also provided. Objectives, laboratory procedures, advantages, and disadvantages for the experiments and projects are included. (JN)

  9. PERITONEAL ABSORPTION

    PubMed Central

    Hahn, P. F.; Miller, L. L.; Robscheit-Robbins, F. S.; Bale, W. F.; Whipple, G. H.

    1944-01-01

    The absorption of red cells from the normal peritoneum of the dog can be demonstrated by means of red cells labeled with radio-iron incorporated in the hemoglobin of these red cells. Absorption in normal dogs runs from 20 to 100 per cent of the amount given within 24 hours. Dogs rendered anemic by bleeding absorb red cells a little less rapidly—ranging from 5 to 80 per cent of the injected red cells. Doubly depleted dogs (anemic and hypoproteinemic) absorb even less in the three experiments recorded. This peritoneal absorption varies widely in different dogs and even in the same dog at different times. We do not know the factors responsible for these variations but there is no question about active peritoneal absorption. The intact red cells pass readily from the peritoneal cavity into lymph spaces in diaphragm and other areas of the peritoneum. The red cells move along the lymphatics and through the lymph glands with little or no phagocytosis and eventually into the large veins through the thoracic ducts. PMID:19871404

  10. Nutrient absorption.

    PubMed

    Rubin, Deborah C

    2004-03-01

    Our understanding of nutrient absorption continues to grow, from the development of unique animal models and from studies in which cutting-edge molecular and cellular biologic approaches have been used to analyze the structure and function of relevant molecules. Studies of the molecular genetics of inherited disorders have also provided many new insights into these processes. A major advance in lipid absorption has been the cloning and characterization of several intestinal acyl CoA:monoacylglycerol acyltransferases; these may provide new targets for antiobesity drug therapy. Studies of intestinal cholesterol absorption and reverse cholesterol transport have encouraged the development of novel potential treatments for hyperlipidemia. Observations in genetically modified mice and in humans with mutations in glucose transporter 2 suggest the importance of a separate microsomal membrane transport pathway for glucose transport. The study of iron metabolism has advanced greatly with the identification of the hemochromatosis gene and the continued examination of the genetic regulation of iron absorptive pathways. Several human thiamine transporters have been identified, and their specific roles in different tissues are being explored.

  11. Spectrophotometry of (32) Pomona, (145) Adeona, (704) Interamnia, (779) Nina, (330825) 2008 XE3, and 2012 QG42 and laboratory study of possible analog samples

    NASA Astrophysics Data System (ADS)

    Busarev, Vladimir V.; Barabanov, Sergey I.; Rusakov, Vyacheslav S.; Puzin, Vasiliy B.; Kravtsov, Valery V.

    2015-12-01

    Six asteroids including two NEAs, one of which is PHA, accessible for observation in September 2012 were investigated using a low-resolution (R ≈ 100) spectrophotometry in the range 0.35-0.90 μm with the aim to study features of their reflectance spectra. A high-altitude position of our Terskol Observatory (3150 m above sea level) favorable for the near-UV and visible-range observations of celestial objects allowed us to probably detect some new spectral features of the asteroids. Two subtle absorption bands centered at 0.53 and 0.74 μm were found in the reflectance spectra of S-type (32) Pomona and interpreted as signs of presence of pyroxenes in the asteroid surface matter and its different oxidation. Very similar absorption bands centered at 0.38, 0.44 and 0.67-0.71 μm have been registered in the reflectance spectra of (145) Adeona, (704) Interamnia, and (779) Nina of primitive types. We performed laboratory investigations of ground samples of known carbonaceous chondrites, Orguel (CI), Mighei (CM2), Murchison (CM2), Boriskino (CM2), and seven samples of low-iron Mg serpentines as possible analogs of the primitive asteroids. In the course of this work, we discovered an intense absorption band (up to ∼25%) centered at 0.44 μm in reflectance spectra of the low-Fe serpentine samples. As it turned out, the equivalent width of the band has a high correlation with content of Fe3+ (octahedral and tetrahedral) in the samples. It may be considered as a confirmation of the previously proposed mechanism of the absorption due to electronic transitions in exchange-coupled pairs (ECP) of Fe3+ neighboring cations. It means that the absorption feature can be used as an indicator of ferric iron in oxidized and hydrated low-Fe compounds on the surface of asteroids and other atmosphereless celestial bodies. Moreover, our measurements showed that the mechanism of light absorption is partially or completely blocked in the case of intermediate to high iron contents. Therefore

  12. Simultaneous determination of titanium and molybdenum in steel samples using derivative spectrophotometry in neutral micellar medium

    NASA Astrophysics Data System (ADS)

    Varghese, Anitha; Khadar, A. M. A.; Kalluraya, Balakrishna

    2006-05-01

    A simple, selective and sensitive spectrophotometric method has been developed for the individual and simultaneous determination of Ti(IV) and Mo(VI) using resacetophenone p-hydroxybenzoylhydrazone (RAPHBH) in presence of Triton X-100, without any prior separation. Beer's law is obeyed between 0.13-1.2 μg mL -1 and 0.18-1.90 μg mL -1 concentration of Ti(IV) and Mo(VI) at 455 nm and 405 nm, respectively. The molar absorptivity and Sandell's sensitivity of the coloured complexes at pH 3.0 are 3.1 × 10 4 L mol -1 cm -1, 4.2 × 10 4 L mol -1 cm -1, and 1.6 ng cm -2, 2.3 ng cm -2 for Ti(IV) and Mo(VI), respectively. The stoichiometry of the complexes were found to be 1:2 and 1:1 (metal:ligand) for Ti(IV) and Mo(VI), respectively. These metal ions interfere with the determination of each other in zero-order spectrophotometry. The first derivative spectra of these complexes permitted a simultaneous determination of Ti(IV) and Mo(VI) at zero crossing wavelengths of 500.0 nm and 455.0 nm, respectively. The effect of foreign ions in the determination of Ti(IV) and Mo(VI) were investigated. The proposed method has been successfully applied for the determination of titanium and molybdenum in standard alloy steel, mineral and soil samples.

  13. Simultaneous determination of titanium and molybdenum in steel samples using derivative spectrophotometry in neutral micellar medium.

    PubMed

    Varghese, Anitha; Khadar, A M A; Kalluraya, Balakrishna

    2006-05-15

    A simple, selective and sensitive spectrophotometric method has been developed for the individual and simultaneous determination of Ti(IV) and Mo(VI) using resacetophenone p-hydroxybenzoylhydrazone (RAPHBH) in presence of Triton X-100, without any prior separation. Beer's law is obeyed between 0.13-1.2 microg mL-1 and 0.18-1.90 microg mL-1 concentration of Ti(IV) and Mo(VI) at 455 nm and 405 nm, respectively. The molar absorptivity and Sandell's sensitivity of the coloured complexes at pH 3.0 are 3.1x10(4) L mol-1 cm-1, 4.2x10(4) L mol-1 cm-1, and 1.6 ng cm-2, 2.3 ng cm-2 for Ti(IV) and Mo(VI), respectively. The stoichiometry of the complexes were found to be 1:2 and 1:1 (metal:ligand) for Ti(IV) and Mo(VI), respectively. These metal ions interfere with the determination of each other in zero-order spectrophotometry. The first derivative spectra of these complexes permitted a simultaneous determination of Ti(IV) and Mo(VI) at zero crossing wavelengths of 500.0 nm and 455.0 nm, respectively. The effect of foreign ions in the determination of Ti(IV) and Mo(VI) were investigated. The proposed method has been successfully applied for the determination of titanium and molybdenum in standard alloy steel, mineral and soil samples.

  14. Direct DOC and nitrate determination in water using dual pathlength and second derivative UV spectrophotometry.

    PubMed

    Causse, Jean; Thomas, Olivier; Jung, Aude-Valérie; Thomas, Marie-Florence

    2017-01-01

    UV spectrophotometry is largely used for water and wastewater quality monitoring. The measurement/estimation of specific and aggregate parameters such as nitrate and dissolved organic carbon (DOC) is possible with UV spectra exploitation, from 2 to multi wavelengths calibration. However, if nitrate determination from UV absorbance is known, major optical interferences linked to the presence of suspended solids, colloids or dissolved organic matter limit the relevance of UV measurement for DOC assessment. A new method based on UV spectrophotometric measurement of raw samples (without filtration) coupling a dual pathlength for spectra acquisition and the second derivative exploitation of the signal is proposed in this work. The determination of nitrate concentration is carried out from the second derivative of the absorbance at 226 nm corresponding at the inflexion point of nitrate signal decrease. A short optical pathlength can be used considering the strong absorption of nitrate ion around 210 nm. For DOC concentration determination the second derivative absorbance at 295 nm is proposed after nitrate correction. Organic matter absorbing slightly in the 270-330 nm window, a long optical pathlength must be selected in order to increase the sensitivity. The method was tested on several hundred of samples from small rivers of two agricultural watersheds located in Brittany, France, taken during dry and wet periods. The comparison between the proposed method and the standardised procedures for nitrate and DOC measurement gave a good adjustment for both parameters for ranges of 2-100 mg/L NO3 and 1-30 mg/L DOC.

  15. Spectrophotometry of Pluto from 3500 to 7350 A

    SciTech Connect

    Barker, E.S.; Cochran, W.D.; Cochran, A.L.

    1980-01-01

    Spectra of Pluto have been obtained on six nights during February 1979 by the use of the Cassegrain Digicon spectrograph on the 2.1-m Struve reflector and the IDS spectrograph on the 2.7-m reflector of McDonald Observatory. These spectra, with nominal resolution of 6-7 A, have been reduced to relative fluxes. Relative albedos were then calculated using the solar irradiances of Arvesen et al. (1969). The spectra taken in the blue show no indication of the upturn in albedo at wavelengths less than 3800 A previously reported by Fix, et al. (1970). The lack of a UV upturn cannot be interpreted in terms of a Rayleigh scattering atmosphere unless the albedo of the underlying surface is known. From the lack of methane absorption at the wavelength of the 6190- or 7270-A methane bands, an upper limit of 1-3 m-am of gaseous CH4 is derived. The albedo curve has a constant slope between 3500 and 7300 A. The only other solar system body which has this feature is an S-type asteroid.

  16. Spectrophotometry of Wolf-Rayet stars. I - Continuum energy distributions

    NASA Technical Reports Server (NTRS)

    Morris, Patrick W.; Brownsberger, Kenneth R.; Conti, Peter S.; Massey, Philip; Vacca, William D.

    1993-01-01

    All available low-resolution IUE spectra are assembled for Galactic, LMC, and SMC W-R stars and are merged with ground-based optical and NIR spectra in order to collate in a systematic fashion the shapes of these energy distributions over the wavelength range 0.1-1 micron. They can be consistently fitted by a power law of the form F(lambda) is approximately equal to lambda exp -alpha over the range 1500-9000 A to derive color excesses E(B-V) and spectral indices by removing the 2175-A interstellar absorption feature. The WN star color excesses derived are found to be in good agreement with those of Schmutz and Vacca (1991) and Koesterke et al. (1991). Significant heterogeneity in spectral index values was generally seen with any given subtype, but the groups consisting of the combined set of Galactic and LMC W-R stars, the separate WN and WC sequences, and the Galactic and LMC W-R stars all showed a striking and consistent Gaussian-like frequency distribution of values.

  17. Measurement of carboxyhaemoglobin by spectrophotometry and gas chromatography.

    PubMed

    Johansson, M B; Wollmer, P

    1989-12-01

    The purpose of this study was to evaluate state-of-the-art spectrophotometry for measurement of carboxyhaemoglobin (COHb). We measured the fractional concentration of COHb in 109 blood samples from patients under investigation of anaemia or with exposure to carbon monoxide (smokers) with the OSM3 Hemoximeter and by gas chromatography. Duplicate measurements were made with both methods in 42 samples. We found only a trivial systematic difference between the two methods. There was, however, a considerable scatter of the measurements, the limits of agreement (95% confidence limits for the difference between the two methods) being -0.98 and 0.86% COHb. The poor agreement between the methods was largely explained by a large random scatter in duplicate spectrophotometric measurements, whereas the method based on gas chromatography was highly reproducible. We conclude that the low accuracy of spectrophotometric measurements of COHb precludes its use for assessment of the endogenous production of CO, but that it may be useful for assessment of exposure to exogenous CO.

  18. Liquid standards utilization for metrological ensuring of spectrophotometry

    NASA Astrophysics Data System (ADS)

    Mogilnaya, L. G.; Sayapin, A. I.; Solov'ev, Victor A.

    1993-12-01

    At the present time the testing of spectrophotometrical measuring means (spectrophotometers) in the ultraviolet and visible spectrum in accordance with the existing USSR verification scheme carried out by means of glass light filters, types KS-100, KS-102 certified with standard instruments. The main shortage of these light filters when using them as the standard measures is the necessity to certify them for transmission coefficient. To solve the problem, it seems reasonable to develop and use the liquid standard samples of optical density (LS) as highly efficient and economical means ensuring the unity of measurements in the spectrophotometry. In this report the possibility of utilization of the set of LS of optical density is considered. The set of LS represents acid and water solutions of organic compounds of five types (LS 04-1, LS 04-2, LS 04-3, LS 04-4, LS 04-5) having two levels of optical density in the wave band of 220 - 720 nm.

  19. HUBBLE SPACE TELESCOPE SPECTROPHOTOMETRY AND MODELS FOR SOLAR ANALOGS

    SciTech Connect

    Bohlin, R. C.

    2010-04-15

    Absolute flux distributions for seven solar analog stars are measured from 0.3 to 2.5 {mu}m by Hubble Space Telescope (HST) spectrophotometry. In order to predict the longer wavelength mid-IR fluxes that are required for James Webb Space Telescope calibration, the HST spectral energy distributions are fit with Castelli and Kurucz model atmospheres; and the results are compared with fits from the MARCS model grid. The rms residuals in 10 broadband bins are all <0.5% for the best fits from both model grids. However, the fits differ systematically: the MARCS fits are 40-100 K hotter in T {sub eff}, 0.25-0.80 higher in log g, 0.01-0.10 higher in log z, and 0.008-0.021 higher in the reddening E(B - V), probably because their specifications include different metal abundances. Despite these differences in the parameters of the fits, the predicted mid-IR fluxes differ by only {approx}1%; and the modeled flux distributions of these G stars have an estimated ensemble accuracy of 2% out to 30 {mu}m.

  20. Automated measurement of urinary creatinine by multichannel kinetic spectrophotometry.

    PubMed

    Ohira, Shin-Ichi; Kirk, Andrea B; Dasgupta, Purnendu K

    2009-01-15

    Urinary creatinine analysis is required for clinical diagnosis, especially for evaluation of renal function. Creatinine adjustment is also widely used to estimate 24-h excretion from spot samples. Few convenient validated approaches are available for in-house creatinine measurement for small- to medium-scale studies. Here we apply the Jáffe reaction to creatinine determination with zone fluidic multichannel kinetic spectrophotometry. Diluted urine sample and reagent, alkaline picric acid, were mixed by a computer-programmed dispenser and rapidly delivered to a four-channel detection cell. The absorbance change was monitored by a flow-through light-emitting diode-photodiode-based detector. Validation results against high-performance liquid chromatography-ultraviolet (HPLC-UV)/mass spectrometry (MS) are presented. Responses for 10-fold diluted samples were linear within clinically relevant ranges (0-250 mg/L after dilution). The system can analyze 70 samples per hour with a limit of detection of 0.76 mg/L. The relative standard deviation was 1.29% at 100 mg/L creatinine (n=225). Correlation with the HPLC (UV quantitation/MS confirmation) system was excellent (linear, r2=0.9906). The developed system allows rapid, simple, cost-effective, and robust creatinine analysis and is suitable for the analysis of large numbers of urine samples.

  1. Infrared spectrophotometry of three Seyfert galaxies and 3C 273

    NASA Technical Reports Server (NTRS)

    Cutri, R. M.; Puetter, R. C.; Rudy, R. J.; Willner, S. P.; Aitken, D. K.; Jones, B.; Merrill, K. M.; Roche, P. F.; Russell, R. W.; Soifer, B. T.

    1981-01-01

    Spectrophotometry in the range 2.1-4.0 microns is presented for the Seyfert galaxies NGC 1068, NGC 4151 and Mrk 231 and the quasar 3C 273, together with broadband and narrowband observations of the Seyfert galaxies in the range 8-13 microns. The spectra of NGC 1068 and NGC 4151 are found to contain a significant component due to starlight, especially at shorter wavelengths. The nonstellar component in NGC 1068 is observed to fall off rapidly at wavelengths shorter than 4 microns, consistent with the interpretation of the excess beyond 5 microns as thermal reradiation by dust. Observations confirm the variability of NGC 4151, and indicate the presence of two components of the flux other than starlight: a nonthermal variable component predominant at shorter wavelengths and a constant, probably thermal component at wavelengths greater than 3 microns. Mrk 231 and 3C 273 exhibit no discernable stellar component and were not observed to vary by more than 10%. Evidence is obtained for a broad minimum in the 8 to 13 micron spectrum of Mrk 231, as well as possible structure between rest wavelengths of 2.8 and 2.9 microns, and the spectrum is not a power law. The spectrum of 3C 273 is consistent with a power law from 1.2 to 10 microns, with small but significant deviations.

  2. Aluminum complexation by catechol as determined by ultraviolet spectrophotometry

    SciTech Connect

    Sikora, F.J.; McBride, M.B.

    1989-03-01

    Methods of ultraviolet (UV) spectrophotometry were used to determine the stoichiometry and association constant for the Al-catechol complex from pH 3.8 to 4.6. Job's method of continuous variation indicated the Al-catechol complex had a 1:1 stoichiometry in the pH range studied. Aluminum titrations of catechol and pH titrations of catechol plus Al resulted in a shift in the UV spectra due to the formation of an Al-catechol complex absorbing UV radiation uniquely different than that of free catechol. General equations were developed for the determination of association constants assuming an organic and Al-organic complex absorb UV radiation. Aluminum titrations with constant catechol concentration yielded a log k/sub 0.1//sup c/ of 16.22 for a 1:1 Al-catechol complex. Calculated absorbance as a function of pH agree dwell with experimental pH titrations of solutions containing catechol plus Al. The fact that Al can be complexed by catechol at low pH indicates the o-hydroxy group provides a potential source for Al complexation in soil and surface waters.

  3. Band gap states in nanocrystalline WO3 thin films studied by soft x-ray spectroscopy and optical spectrophotometry

    NASA Astrophysics Data System (ADS)

    Johansson, M. B.; Kristiansen, P. T.; Duda, L.; Niklasson, G. A.; Österlund, L.

    2016-11-01

    Nanocrystalline tungsten trioxide (WO3) thin films prepared by DC magnetron sputtering have been studied using soft x-ray spectroscopy and optical spectrophotometry. Resonant inelastic x-ray scattering (RIXS) measurements reveal band gap states in sub-stoichiometric γ-WO3-x with x  =  0.001-0.005. The energy positions of these states are in good agreement with recently reported density functional calculations. The results were compared with optical absorption measurements in the near infrared spectral region. An optical absorption peak at 0.74 eV is assigned to intervalence transfer of polarons between W sites. A less prominent peak at energies between 0.96 and 1.16 eV is assigned to electron excitation of oxygen vacancies. The latter results are supported by RIXS measurements, where an energy loss in this energy range was observed, and this suggests that electron transfer processes involving transitions from oxygen vacancy states can be observed in RIXS. Our results have implications for the interpretation of optical properties of WO3, and the optical transitions close to the band gap, which are important in photocatalytic and photoelectrochemical applications.

  4. Calculation of optical band gaps of a-Si:H thin films by ellipsometry and UV-Vis spectrophotometry

    NASA Astrophysics Data System (ADS)

    Qiu, Yijiao; Li, Wei; Wu, Maoyang; Fu, Junwei; Jiang, Yadong

    2010-10-01

    Hydrogenated amorphous silicon (a-Si:H) thin films doped with Phosphorus (P) and Nitrogen (N) were deposited by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD). The optical band gaps of the thin films obtained through either changing the gas pressure (P-doped only) or adulterating nitrogen concentration (with fixed P content) were investigated by means of Ellipsometric and Ultraviolet-Visible (UV-Vis) spectroscopy, respectively. Tauc formula was used in calculating the optical band gaps of the thin films in both methods. The results show that Ellipsometry and UV-Vis spectrophotometry can be applied in the research of the optical properties of a-Si:H thin films experimentally. Both methods reflect the variation law of the optical band gaps caused by CVD process parameters, i.e., the optical band gap of the a-Si:H thin films is increased with the rise of the gas pressure or the nitrogen concentration respectively. The difference in optical band gaps of the doped a-Si:H thin films calculated by Ellipsometry or UV-Vis spectrophotometry are not so great that they both can be used to measure the optical band gaps of the thin films in practical applications.

  5. A simple and cost-effective method, as an appropriate alternative for visible spectrophotometry: development of a dopamine biosensor.

    PubMed

    Abbaspour, Abdolkarim; Khajehzadeh, Abdolreza; Ghaffarinejad, Ali

    2009-08-01

    In this study, a new, simple, fast and inexpensive method as an alternative to visible spectrophotometry is developed. In this method the cells containing the sample solution were scanned with a scanner, then the color of each cell was analyzed with software written in visual basic (VB 6) media to red, green and blue values. The cells were built by creating holes in the Plexiglas sheet. The dimensions of identical cells were examined by Cr (III) solution with known concentrations. The validity of this new method was studied by determination of dopamine (DA) without using any other reagent. The parameters which affect the system were optimized. The comparison between the current and traditional UV-Vis spectrophotometry methods was studied and the results revealed similar trends in both methods. The developed method was successfully applied to the determination of dopamine in serum and urine without using any pretreatment. Finally comparing the results obtained in the developed method showed that microwave irradiation of the solution can decrease the experimental time, increase sensitivity and improve the limit of detection.

  6. The Uranian satellites and Hyperion - New spectrophotometry and compositional implications

    NASA Technical Reports Server (NTRS)

    Brown, R. H.

    1983-01-01

    New reflectance spectra at 3.5 percent resolution have been obtained for Ariel, Titania, Oberon, and Hyperion in the 0.8 to 1.6-micron spectrum region. The new spectra show no absorptions other than the 1.5 micron water-ice feature (within the precision of the data), and demonstrate extension into the 0.8- to 1.6 micron region of the 1.5- to 2.5 micron spectral similarity ofo Ariel to Hyperion (Brown and Cruikshank, 1983). The new data confirm the presence of a dark, spectrally bland component on/in the water-ice surfaces of the Uranian satellites, which, with some reservations, has spectral similarities to the dark substance on the leading side of lapetus and the dark material on/in the surface of Hyperion, as well as other dark, spectrally neutral substances such as charcoal. Attempts were made to match the spectra of Ariel, Titania, and Oberon with additive reflectance mixes (aeral coverage) of fine-grained water frost and various dark components such as charcoal, lampblack, and charcoal-water-ice mixtures. The results were broad limits on the amounts of possible areal coverage of a charcoal-like spectral component on the surfaces of the Uranian satellites, but the data are not of sufficient precision to conclusively determine whether the dominant mode of contaminant dispersal is areal or voluminal. The effect of highly variegated albedos on the diameters derived by Brown, Cruikshank, and Morrison (1982) is found to be small.

  7. Kinetics of pH-dependent interconversion of tryptophanase spectral forms studied by scanning stopped-flow spectrophotometry.

    PubMed

    June, D S; Suelter, C H; Dye, J L

    1981-05-12

    Morino and Snell [Morino, Y., & Snell, E. E. (1967) J. Biol. Chem. 242, 5591-5601] previously showed that the relative amplitudes of the 337- and 420-nm absorption bands of tryptophanase depended on both pH and the nature of a required monovalent cation activator. An investigation of the kinetics of interconversion of the 337- and 420-nm forms following a rapid incremental increase (jump) or decrease (drop) in pH over the range of enzyme stability in 0.2 M KCl at 24 +/- 0.3 degrees C by scanning stopped-flow spectrophotometry showed three distinct time-dependent phases. They were (1) an abrupt phase which is complete in less than 6.5 ms, (2) a fast first-order interconversion of the 420- and 337-nm absorbances, and (3) a slow first-order process involving growth at 355 nm coupled to two decays centered at 325 and 430 nm in the incremental pH jumps and decay at 355 nm with concomitant growth at 430 and 290 nm in the incremental pH-drop experiments. The results of these experiments were analyzed in terms of a scheme involving enzyme forms E alpha, E beta, E beta H+, E gamma, E gamma H+, and E delta. The E alpha form predominates in the absence of activating monovalent cations and absorbs at 420 nm. Those in the beta manifold, E beta and E beta H+, also absorb at 420 nm while those in the gamma manifold, E gamma and E gamma H+, absorb at 337 nm. The form E delta absorbs at 335 nm. E beta H+ and E gamma H+ represent the protonated form of the enzyme in each manifold. Analysis of the abrupt phase showed no significant systematic changes in absorbance above 330 nm for either the pH-jump or pH-drop experiments. The fast second phase involves the first-order interconversion of the beta and gamma manifolds while the slow third phase describes the buildup or decay of the delta manifold. Presumably conformational changes control the rate of these interconversions. The pH dependence of the fast first-order beta to gamma conversion was described and evaluated in terms of five

  8. Limitation of fluorescence spectrophotometry in the measurement of naphthenic acids in oil sands process water.

    PubMed

    Lu, Weibing; Ewanchuk, Andrea; Perez-Estrada, Leonidas; Sego, Dave; Ulrich, Ania

    2013-01-01

    Fluorescence spectrophotometry has been proposed as a quick screening technique for the measurement of naphthenic acids (NAs). To evaluate the feasibility of this application, the fluorescence emission spectra of NAs extracted from three oil sands process water sources were compared with that of commercial NAs. The NAs resulting from the bitumen extraction process cannot be differentiated because of the similarity of the fluorescence spectra. Separation of the fluorescent species in NAs using high performance liquid chromatography with fluorescence detector proved unsuccessful. The acidic fraction of NAs is fluorescent but the basic fraction of NAs is not fluorescent, implying that aromatic acids in NAs give rise to the fluorescent signals. The concentrations of NAs in oil sands process water were measured by Fourier transform infrared spectroscopy (FTIR), fluorescence spectrophotometry and ultra high performance liquid chromatography-time of flight/mass spectrometry (UPLC-TOF/MS). Commercial Merichem and Kodak NAs are the best standards to use when measuring NAs concentration with FTIR and fluorescence spectrophotometry. In addition, the NAs concentrations measured by fluorescence spectrophotometry are about 30 times higher than those measured by FTIR and UPLC-TOF/MS. The findings in this study underscore the limitation of fluorescence spectrophotometry in the measurement of NAs.

  9. Determination of attapulgite and nifuroxazide in pharmaceutical formulations by sequential digital derivative spectrophotometry.

    PubMed

    Toral, M Inés; Paine, Maximiliano; Leyton, Patricio; Richter, Pablo

    2004-01-01

    A new method for the sequential determination of attapulgite and nifuroxazide in pharmaceutical formulations by first- and second-derivative spectrophotometry, respectively, has been developed. In order to obtain the optimal conditions for nifuroxazide stability, studies of solvent, light, and temperature effects were performed. The results show that a previous hydrolysis of 2 h in 1.0 x 10(-1)M NaOH solution is necessary in order to obtain stable compounds for analytical purposes. Subsequently, the first- and second-derivative spectra were evaluated directly in the same samples. The sequential determination of the drugs can be performed using the zero-crossing method; the attapulgite determination was carried out using the first derivative at 278.0 nm and the nifuroxazide determination, using the second derivative at 282.0 nm. The determination ranges were 5.7 x 10(-6)-1.0 x 10(-4) and 3.7 x 10(-8) -1.2 x 10(-4)M for attapulgite and nifuroxazide, respectively. Repeatability (relative standard deviation) values of 1.2 and 3.0% were observed for attapulgite and nifuroxazide, respectively. The ingredients commonly found in commercial pharmaceutical formulations do not interfere. The proposed method was applied to the determination of these drugs in tablets. Further, infrared spectroscopy and cyclic voltammetry studies were carried out in order to obtain knowledge of the decomposition products of nifuroxazide.

  10. Metal powder absorptivity: Modeling and experiment

    DOE PAGES

    Boley, C. D.; Mitchell, S. C.; Rubenchik, A. M.; ...

    2016-08-10

    Here, we present results of numerical modeling and direct calorimetric measurements of the powder absorptivity for a number of metals. The modeling results generally correlate well with experiment. We show that the powder absorptivity is determined, to a great extent, by the absorptivity of a flat surface at normal incidence. Our results allow the prediction of the powder absorptivity from normal flat-surface absorptivity measurements.

  11. Methane absorption variations in the spectrum of Pluto

    SciTech Connect

    Buie, M.W.; Fink, U.

    1987-06-01

    The lightcurve phases of 0.18, 0.35, 0.49, and 0.98 covered by 5600-10,500 A absolute spectrophotometry of Pluto during four nights include minimum (0.98) light and one near-maximum (0.49) light. The spectra are noted to exhibit significant methane band absorption depth variations at 6200, 7200, 7900, 8400, 8600, 8900, and 10,000 A, with the minimum absorption occurring at minimum light and thereby indicating a 30-percent change in the methane column abundance in the course of three days. An attempt is made to model this absorption strength variation with rotational phase terms of an isotropic surface distribution of methane frost and a clear layer of CH4 gas. 34 references.

  12. Transient absorption spectroscopy of laser shocked explosives

    SciTech Connect

    Mcgrane, Shawn D; Dang, Nhan C; Whitley, Von H; Bolome, Cindy A; Moore, D S

    2010-01-01

    Transient absorption spectra from 390-890 nm of laser shocked RDX, PETN, sapphire, and polyvinylnitrate (PVN) at sub-nanosecond time scales are reported. RDX shows a nearly linear increase in absorption with time after shock at {approx}23 GPa. PETN is similar, but with smaller total absorption. A broad visible absorption in sapphire begins nearly immediately upon shock loading but does not build over time. PVN exhibits thin film interference in the absorption spectra along with increased absorption with time. The absorptions in RDX and PETN are suggested to originate in chemical reactions happening on picosecond time scales at these shock stresses, although further diagnostics are required to prove this interpretation.

  13. PHASES: A Project to Perform Absolute Spectrophotometry from Space

    NASA Astrophysics Data System (ADS)

    del Burgo, C.; Vather, D.; Allende Prieto, C.; Murphy, N.

    2013-04-01

    This paper presents the current status of the opto-mechanical design of PHASES (Planet Hunting and AsteroSeismology Explorer Spectrophotometer), which is a project to develop a space-borne telescope to obtain absolute flux calibrated spectra of bright stars. The science payload is intended to be housed in a micro-satellite launched into a low-earth Sun-synchronous orbit with an inclination to the equator of 98.7° and a local time ascending node LTAN of 6:00 AM. PHASES will be able to measure micromagnitude photometric variations due to stellar oscillations/activity and planet/moon transits. It consists of a 20 cm aperture modified Baker telescope feeding two detectors: the tracking detector provides the fine telescope guidance system with a required pointing stability of 0.2″, and the science detector performs spectrophotometry in the wavelength range 370-960 nm with a resolving power between 200 and 900. The spectrograph is designed to provide 1% RMS flux calibrated spectra with signal-to-noise ratios > 100 for stars with V < 10 in short integration times. Our strategy to calibrate the system using A type stars is explained. From comparison with model atmospheres it would be possible to determine the stellar angular diameters with an uncertainty of approximately 0.5%. In the case of a star hosting a transiting planet it would be possible to derive its light curve, and then the planet to stellar radius ratio. Bright stars have high precision Hipparcos parallaxes and the expected level of accuracy for their fluxes will be propagated to the stellar radii, and more significantly to the planetary radii. The scientific drivers for PHASES give rise to some design challenges, which are particularly related to the opto-mechanics for extreme environmental conditions. The optical design has been developed with the primary goal of avoiding stray light reaching the science detector. Three different proposals for the opto-mechanical design are under investigation.

  14. ABSORPTION ANALYZER

    DOEpatents

    Brooksbank, W.A. Jr.; Leddicotte, G.W.; Strain, J.E.; Hendon, H.H. Jr.

    1961-11-14

    A means was developed for continuously computing and indicating the isotopic assay of a process solution and for automatically controlling the process output of isotope separation equipment to provide a continuous output of the desired isotopic ratio. A counter tube is surrounded with a sample to be analyzed so that the tube is exactly in the center of the sample. A source of fast neutrons is provided and is spaced from the sample. The neutrons from the source are thermalized by causing them to pass through a neutron moderator, and the neutrons are allowed to diffuse radially through the sample to actuate the counter. A reference counter in a known sample of pure solvent is also actuated by the thermal neutrons from the neutron source. The number of neutrons which actuate the detectors is a function of a concentration of the elements in solution and their neutron absorption cross sections. The pulses produced by the detectors responsive to each neu tron passing therethrough are amplified and counted. The respective times required to accumulate a selected number of counts are measured by associated timing devices. The concentration of a particular element in solution may be determined by utilizing the following relation: T2/Ti = BCR, where B is a constant proportional to the absorption cross sections, T2 is the time of count collection for the unknown solution, Ti is the time of count collection for the pure solvent, R is the isotopic ratlo, and C is the molar concentration of the element to be determined. Knowing the slope constant B for any element and when the chemical concentration is known, the isotopic concentration may be readily determined, and conversely when the isotopic ratio is known, the chemical concentrations may be determined. (AEC)

  15. C3 and infrared spectrophotometry of Y Canum Venaticorum

    NASA Technical Reports Server (NTRS)

    Goebel, J. H.; Bregman, J. D.; Strecker, D. W.; Witteborn, F. C.; Erickson, E. F.

    1978-01-01

    The 1.2- to 5.6-micron spectrum of the carbon star Y CVn is presented and discussed. The observations were made from the Kuiper Airborne Observatory at an altitude of 12.5 km, thereby avoiding most of the absorption due to terrestrial water vapor. Comparison of Y CVn near 5 microns with laboratory spectra provides possible evidence for the presence of the linear triatomic molecule C3. For the first time in a carbon star the clearly formed band heads of the CN red system between 1.2 and 2.3 microns are observed. Corroborative evidence for the presence of the molecules HCN and C2H2 is presented, and the relative contributions of C3, HCN, and C2H2 to the 3.1-micron absorption band are discussed. Spectra of two other carbon stars, TX Psc and S Cep, are presented for comparison.

  16. 3 micron spectrophotometry of Comet Halley - Evidence for water ice

    NASA Technical Reports Server (NTRS)

    Bregman, Jesse D.; Tielens, A. G. G. M.; Witteborn, Fred C.; Rank, David M.; Wooden, Diane

    1988-01-01

    Structure has been observed in the 3-3.6 micron preperihelion spectrum of Comet Halley consistent with either an absorption band near 3.1 microns or emission near 3.3 microns. The results suggest that a large fraction of the water molecules lost by the comet are initially ejected in the form of small ice particles rather than in the gas phase.

  17. Determination of thallium at ultra-trace levels in water and biological samples using solid phase spectrophotometry.

    PubMed

    Amin, Alaa S; El-Sharjawy, Abdel-Azeem M; Kassem, Mohammed A

    2013-06-01

    A new simple, very sensitive, selective and accurate procedure for the determination of trace amounts of thallium(III) by solid-phase spectrophotometry (SPS) has been developed. The procedure is based on fixation of Tl(III) as quinalizarin ion associate on a styrene-divinylbenzene anion-exchange resin. The absorbance of resin sorbed Tl(III) ion associate is measured directly at 636 and 830 nm. Thallium(I) was determined by difference measurements after oxidation of Tl(I) to Tl(III) with bromine. Calibration is linear over the range 0.5-12.0 μg L(-1) of Tl(III) with relative standard deviation (RSD) of 1.40% (n=10). The detection and quantification limits are 150 and 495 ng L(-1) using 0.6 g of the exchanger. The molar absorptivity and Sandell sensitivity are also calculated and found to be 1.31×10(7) L mol(-1)cm(-1) and 0.00156 ng cm(-2), respectively. The proposed procedure has been successfully applied to determine thallium in water, urine and serum samples.

  18. [Study on the hydrolysis distribution of ferric saline by infrared spectrophotometry and single crystal X-ray diffraction method].

    PubMed

    Zheng, Huai-Li; Xie, Li-Guo; Gao, Chao-Yong; Sun, Xiu-Ping; Yang, You; Tang, Xue

    2009-02-01

    The hydrolytic stability of Fe(a), Fe(b) and Fe(c) in different pH values of poly-ferric-flocculants was studied by using Fe-ferron time by time complexation colorimetry. The research results showed that Fe(b) was unstable, and all Fe(b) was transformed to Fe(c) after 10-15 d placement. The content of Fe(c) tended towards stability after 10-15 d. Also, the content of Fe(a) tended towards stability after 10 d. The single crystal was synthesized by the method of direct crystallization in Fe(III)-SO4(2-) water solution at normal temperature and its structure characteristic was studied by single crystal X ray diffraction method and IR (infrared spectrophotometry). The research results showed that there was no group of Fe-OH-Fe, Fe-OH and binary ferric complexed with two hydroxyl groups in the single crystal synthesized from the ferric aqueous solution in low pH (pH was about 0.5). The form of Fe in single crystal was all Fe(III). The chemical formula of the single crystal was Fe(H2O)6 (SO4)2NH4 x 6H2O when the ammonia water was used as the alkalinizing agent. One reason was that with the evaporation of water, these single crystals were synthesized at pH 0. 5 despite of different initial pH and different initial alkalinizing agents. Another reason was that the hydrolysis distribution of ferric saline was unstable. Therefore, it was not easy to obtain the single crystal of Fe(III)-hydroxy complexes or Fe(III)-polymer at low pH value. The study showed that infrared spectrophotometry and single crystal X ray diffraction method have a good prospect in the research on hydrolysis distribution of flocculants.

  19. Five-Photon Absorption and Selective Enhancement of Multiphoton Absorption Processes

    PubMed Central

    2015-01-01

    We study one-, two-, three-, four-, and five-photon absorption of three centrosymmetric molecules using density functional theory. These calculations are the first ab initio calculations of five-photon absorption. Even- and odd-order absorption processes show different trends in the absorption cross sections. The behavior of all even- and odd-photon absorption properties shows a semiquantitative similarity, which can be explained using few-state models. This analysis shows that odd-photon absorption processes are largely determined by the one-photon absorption strength, whereas all even-photon absorption strengths are largely dominated by the two-photon absorption strength, in both cases modulated by powers of the polarizability of the final excited state. We demonstrate how to selectively enhance a specific multiphoton absorption process. PMID:26120588

  20. Five-Photon Absorption and Selective Enhancement of Multiphoton Absorption Processes.

    PubMed

    Friese, Daniel H; Bast, Radovan; Ruud, Kenneth

    2015-05-20

    We study one-, two-, three-, four-, and five-photon absorption of three centrosymmetric molecules using density functional theory. These calculations are the first ab initio calculations of five-photon absorption. Even- and odd-order absorption processes show different trends in the absorption cross sections. The behavior of all even- and odd-photon absorption properties shows a semiquantitative similarity, which can be explained using few-state models. This analysis shows that odd-photon absorption processes are largely determined by the one-photon absorption strength, whereas all even-photon absorption strengths are largely dominated by the two-photon absorption strength, in both cases modulated by powers of the polarizability of the final excited state. We demonstrate how to selectively enhance a specific multiphoton absorption process.

  1. Evaluation of indomethacin percutaneous absorption from nanostructured lipid carriers (NLC): in vitro and in vivo studies.

    PubMed

    Ricci, Maurizio; Puglia, Carmelo; Bonina, Francesco; Di Giovanni, Caterina; Giovagnoli, Stefano; Rossi, Carlo

    2005-05-01

    The aim of this study was the evaluation, in vitro and in vivo, of indomethacin (IND) release through the skin from nanostructured lipid carriers (NLC). NLC were prepared by ultrasonication, and were characterized in order to determine drug content, and particle size; finally the NLC were processed to hydrogels (A and B). The IND release pattern from NLC hydrogels was evaluated in vitro, to determine its percutaneous absorption through excised human skin (stratum corneum and epidermis, SCE), and in vivo. To evaluate the in vivo IND release, two methods were employed: (1) the IND topical anti-inflammatory activity was determined at different time-points after its cutaneous application; in this case, the UVB-induced erythema on healthy human volunteers, chosen as inflammatory model, was monitored by reflectance visible spectrophotometry; (2) the extent of IND absorption into human skin was performed by the tape-stripping technique. The in vitro percutaneous absorption studies showed lower fluxes of IND through SCE membranes from NLC hydrogels (A and B) in comparison to an aqueous dispersion (C) and a hydro-alcoholic gel (D) both containing free IND. The findings from the former in vivo method showed that the anti-inflammatory effect, following IND topical application, was more prolonged with IND-loaded NLC gel formulation (A) if compared to formulation C and D. The results from tape stripping technique confirmed the trend obtained by the former in vivo method and indicated that IND topical bioavailability in the stratum corneum varied substantially depending upon the formulations (A-D).

  2. Spectrophotometry of peculiar B and A stars. XVIII - The helium rich variable stars HR 1890, Sigma Orionis E, and HD 37776

    NASA Technical Reports Server (NTRS)

    Adelman, S. J.; Pyper, D. M.

    1985-01-01

    Optical region spectrophotometry at 3300-7850 A has been obtained for three helium rich stars, HR 1890, Sigma Ori E, and HD 37776, of the Orion OB1 Association. New uvby-beta photometry of HR 1890 and HD 37776 as well as published data are also used to investigate the variability of these stars. A new period of 1.53862 days was determined for HD 37776. For all three stars H-beta varies in antiphase with strong He I lines. The spectrophotometric bandpass containing the strong He I line at 4471 A varies in phase with the R index of Pedersen and Thomsen (1977). Evidence is found for weak absorption features which appear to be an extension of the 5200 A feature seen in cooler CP stars.

  3. Study of inclusion complex formation between tropaeolin OO and beta-cyclodextrin by spectrophotometry and Infrared spectroscopy.

    PubMed

    Wang, Huai You; Han, Juan; Feng, Xia Guang; Pang, Yan Ling

    2006-09-01

    The mechanism of the inclusion of tropaeolin OO (TPOO) and beta-cyclodextrin (beta-CD) has been studied by spectrophotometry. The inclusion depth of the guest molecule in the host molecule was demonstrated by infrared spectrometry. Effect of the pH, concentrations of beta-CD, solvents and ionic strength on the inclusion of TPOO and beta-CD were examined. The result showed that TPOO reacts with beta-CD to form a 1:1 host-guest complex with an apparent formation constant of 1.50 x 10(3) l mol(-1). The thermodynamic parameters of inclusion reaction, DeltaG degrees , DeltaH degrees and DeltaS degrees were obtained.

  4. Comparison of HPLC, UV spectrophotometry and potentiometric titration methods for the determination of lumefantrine in pharmaceutical products.

    PubMed

    da Costa César, Isabela; Nogueira, Fernando Henrique Andrade; Pianetti, Gérson Antônio

    2008-09-10

    This paper describes the development and evaluation of a HPLC, UV spectrophotometry and potentiometric titration methods to quantify lumefantrine in raw materials and tablets. HPLC analyses were carried out using a Symmetry C(18) column and a mobile phase composed of methanol and 0.05% trifluoroacetic acid (80:20), with a flow rate of 1.0ml/min and UV detection at 335nm. For the spectrophotometric analyses, methanol was used as solvent and the wavelength of 335nm was selected for the detection. Non-aqueous titration of lumefantrine was carried out using perchloric acid as titrant and glacial acetic acid/acetic anhydride as solvent. The end point was potentiometrically determined. The three evaluated methods showed to be adequate to quantify lumefantrine in raw materials, while HPLC and UV methods presented the most reliable results for the analyses of tablets.

  5. Identification of Organic Colorants in Art Objects by Solution Spectrophotometry: Pigments.

    ERIC Educational Resources Information Center

    Billmeyer, Fred W., Jr.; And Others

    1981-01-01

    Describes solution spectrophotometry as a simple, rapid identification technique for organic paint pigments. Reports research which includes analytical schemes for the extraction and separation of organic pigments based on their solubilities, and the preparation of an extensive reference collection of spectral curves allowing their identification.…

  6. Near-Infrared Spectrophotometry of Phobos and Deimos

    NASA Technical Reports Server (NTRS)

    Rivkin, A. S.; Brown, R. H.; Trilling, D. E.; Bell, J. F., III; Plassmann, J. H.

    2002-01-01

    We have observed the leading and trailing hemispheres of Phobos from 1.65 to 3.5 microns and Deimos from 1.65 to 3.12 microns near opposition. We find the trailing hemisphere of Phobos to be brighter than its leading hemisphere by 0.24 +/- 0.06 magnitude at 1.65 microns and brighter than Deimos by 0.98 +/- 0.07 magnitude at 1.65 microns. We see no difference larger than observational uncertainties in spectral slope between the leading and trailing hemispheres when the spectra are normalized to 1.65 microns. We find no 3-micron absorption feature due to hydrated minerals on either hemisphere to a level of approx. 5-10% on Phobos and approx. 20% on Deimos. When the infrared data are joined to visible and near-IR data obtained by previous workers, our data suggest the leading (Stickney-dominated) side of Phobos is best matched by T-class asteroids. The spectral slope of the trailing side of Phobos and leading side of Deimos are bracketed by the D-class asteroids. The best laboratory spectral matches to these parts of Phobos are mature lunar soils and heated carbonaceous chondrites. The lack of 3-micron absorption features on either side of Phobos argues against the presence of a large interior reservoir of water ice according to current models of Phobos' interior.

  7. Near-Infrared Spectrophotometry of Phobos and Deimos

    NASA Technical Reports Server (NTRS)

    Rivkin, A. S.; Brown, R. H.; Trilling, D. E.; Bell, J. F., III; Plassmann, J. H.

    2002-01-01

    We have observed the leading and trailing hemispheres of Phobos from 1.65 to 3.5 micrometers and Deimos from 1.65 to 3.12 micrometers near opposition. We find the trailing hemisphere of Phobos to be brighter than its leading hemisphere by 0.24 plus or minus 0.06 magnitude at 1.65 micrometers and brighter than Deimos by 0.98 plus or minus 0.07 magnitude at 1.65 micrometers. We see no difference larger than observational uncertainties in spectral slope between the leading and trailing hemispheres when the spectra are normalized to 1.65 micrometers. We find no 3-micrometer absorption feature due to hydrated minerals on either hemisphere to a level of approximately 5-10% on Phobos and approximately 20% on Deimos. When the infrared data are joined to visible and nearby data obtained by previous workers, our data suggest the leading (Stickney-dominated) side of Phobos is best matched by T-class asteroids. The spectral slope of the trailing side of Phobos and leading side of Deimos are bracketed by the D-class asteroids. The best laboratory spectral matches to these parts of Phobos are mature lunar soils and heated carbonaceous chondrites. The lack of 3-micrometer absorption features on either side of Phobos argues against the presence of a large interior reservoir of water ice according to current models of Phobos' interior.

  8. Near-Infrared Spectrophotometry of Phobos and Deimos

    NASA Technical Reports Server (NTRS)

    Rivkin, A. S.; Brown, R. H.; Trilling, D. E.; Bell, J. F., III; Plassmann, J. H.

    2002-01-01

    We have observed the leading and trailing hemispheres of Phobos from 1.65 to 3.5 microns and Deimos from 1.65 to 3.12 microns near opposition. We find the trailing hemisphere of Phobos to be brighter than its leading hemisphere by 0.24 +/- 0.06 magnitude at 1.65 microns and brighter than Deimos by 0.98 +/- 0.07 magnitude at 1.65 microns. We see no difference larger than observational uncertainties in spectral slope between the leading and trailing hemispheres when the spectra are normalized to 1.65 microns. We find no 3-microns absorption feature due to hydrated minerals on either hemisphere to a level of approx. 5 - 10% on Phobos and approx. 20% on Deimos. When the infrared data are joined to visible and near-IR data obtained by previous workers, our data suggest the leading (Stickney-dominated) side of Phobos is best matched by T-class asteroids. The spectral slope of the trailing side of Phobos and leading side of Deimos are bracketed by the D-class asteroids. The best laboratory spectral matches to these parts of Phobos are mature lunar soils and heated carbonaceous chondrites. The lack of 3-microns absorption features on either side of Phobos argues against the presence of a large interior reservoir of water ice according to current models of Phobos' interior.

  9. Cracking the perfusion code?: Laser-assisted Indocyanine Green angiography and combined laser Doppler spectrophotometry for intraoperative evaluation of tissue perfusion in autologous breast reconstruction with DIEP or ms-TRAM flaps.

    PubMed

    Ludolph, Ingo; Arkudas, Andreas; Schmitz, Marweh; Boos, Anja M; Taeger, Christian D; Rother, Ulrich; Horch, Raymund E; Beier, Justus P

    2016-10-01

    The aim of this prospective study was to assess the correlation of flap perfusion analysis based on laser-assisted Indocyanine Green (ICG) angiography with combined laser Doppler spectrophotometry in autologous breast reconstruction using free DIEP/ms-TRAM flaps. Between February 2014 and July 2015, 35 free DIEP/ms-TRAM flaps were included in this study. Besides the clinical evaluation of flaps, intraoperative perfusion dynamics were assessed by means of laser-assisted ICG angiography and post-capillary oxygen saturation and relative haemoglobin content (rHb) using combined laser Doppler spectrophotometry. Correlation of the aforementioned parameters was analysed, as well as the impact on flap design and postoperative complications. Flap survival rate was 100%. There were no partial flap losses. In three cases, flap design was based on the angiography, contrary to clinical evaluation and spectrophotometry. The final decision on the inclusion of flap areas was based on the angiographic perfusion pattern. Angiography and spectrophotometry showed a correlation in most of the cases regarding tissue perfusion, post-capillary oxygen saturation and relative haemoglobin content. Laser-assisted ICG angiography is a useful tool for intraoperative evaluation of flap perfusion in autologous breast reconstruction with DIEP/ms-TRAM flaps, especially in decision making in cases where flap perfusion is not clearly assessable by clinical signs and exact determination of well-perfused flap margins is difficult to obtain. It provides an objective real-time analysis of flap perfusion, with high sensitivity for the detection of poorly perfused flap areas. Concerning the topographical mapping of well-perfused flap areas, laser-assisted angiography is superior to combined laser Doppler spectrophotometry.

  10. Selective determination of the holmium in rare earth mixtures by second derivative spectrophotometry with 2-isobutylformyl-1,3-dione-indan and octylphenol poly-(ethyleneglycol)ether

    SciTech Connect

    Wang Naixing; Si Zhikun; Jiang Wei

    1996-09-01

    In this paper the absorption spectra of 4f electron transitions of the system of holmium with 2-isobutylformyl-1,3-dione-indan and TX-100 have been studied by normal and derivative spectrophotometry. The molar absorptivities are 98 (at 450 nm) and 21 (at 460 nm) 1 {center_dot} mol{sup -1} {center_dot} cm{sup -1}, respectively. The use of the second derivative spectra, eliminates the interference by other lanthanides and improves the sensitivity for holmium determination. The derivative molar absorptivity is 558 1 {center_dot} mol{sup -1} {center_dot} cm{sup -1}. The calibration graph was linear up to 25{mu}g/ml of holmium. The relative standard deviation evaluated from ten independent determinations of 8.0 {mu}g/ml holmium is 1.0%. The detection limit, obtained from the sensitivity of the calibration graph and for 3 S{sub b} (S{sub b} = standard deviation of a blank without holmium, n = 11), was found to be 0.31 {mu}g/ml of holmium. The quantification limit, obtained for 10 S{sub b}, was 1.0 {mu}g/ml of holmium. A method has been developed for determining holmium in a mixture of lanthanides by means of the second derivative spectra and the analytical results obtained are satisfactory.

  11. UV spectrophotometry for monitoring the performance of a yeast-based deoxygenation process to treat ships' ballast water.

    PubMed

    Veilleux, Éloïse; de Lafontaine, Yves; Thomas, Olivier

    2016-04-01

    This study assessed the usefulness of UV spectrophotometry for the monitoring of a yeast-based deoxygenation process proposed for ships' ballast water treatment to prevent the transfer of aquatic invasive species. Ten-day laboratory experiments using three treatment concentrations and different water types were conducted and resulted in complete oxygen depletion of treated waters. The treatment performance and quality of treated waters were determined by measuring the UV-visible absorbance spectra of water samples taken over time. Samples were also used for laboratory analysis of water quality properties. The UV absorbance spectra values were strongly correlated (r = 0.96) to yeast cell density in treated waters. The second-order derivative (D (2)) of the spectra varied greatly over time, and the spectrum profiles could be divided into two groups corresponding to the oxygenated and anoxic phases of the treatment. The D (2) value at 215 nm was strongly correlated (r = 0.94) to ammonia levels, which increased over time. The D (2) value at 225 nm was strongly correlated (r > 0.97) to DO concentration. Our results showed that UV spectrophotometry may provide a rapid assessment of the behavior and performance of the yeast bioreactor over time by quantifying (1) the density of yeast cells, (2) the time at which anoxic conditions were reached, and (3) a water quality index of the treated water related to the production of ammonia. We conclude that the rapidity of the technique confers a solid advantage over standard methods used for water quality analysis in laboratory and would permit the direct monitoring of the treatment performance on-board ships.

  12. Spectrophotometry, colors, and photometric properties of the 67P/Churyumov-Gerasimenko nucleus from the OSIRIS instrument onboard the ROSETTA mission

    NASA Astrophysics Data System (ADS)

    Fornasier, Sonia; Hasselmann, Pedro; Feller, Clement; Barucci, Maria Antonietta; Lara, Luisa; Oklay, Nilda; Tubiana, Cecilia; Besse, Sebastien; Scholten, Frank; Sierks, Holger; Leyrat, Cedric; La Forgia, Fiorangela; Lazzarin, Monica; Pajola, Maurizio; Thomas, Nick; Pommerol, Antoine; Massironi, Matteo

    2015-04-01

    Rosetta is the cornerstone mission of the European Space Agency devoted to the study of Solar System minor bodies. Launched on 2 March 2004, Rosetta arrived on August 6, 2014, at the comet 67P/Churyumov-Gerasimenko after 10 years of interplanetary journey. Rosetta is now in the main science escort phase of the comet after the successful delivery of the lander Philae on its surface on November 12, 2014. In this work we present the results on the 67P nucleus physical properties derived from the OSIRIS imaging system observations obtained in July- mid August 2014, during the comet approach phase and the first bound orbits. In this timeframe, OSIRIS has mapped the comet surface with a resolution up to 2 m/px with several filters covering the 250-1000 nm range, and at different phase angles (1.3-54 degrees). The images have been reduced using the OSIRIS standard pipeline, and then transformed into I/F reflectance. A 3D shape model of the nucleus, determined from the images obtained during the mapping phase, has been used to retrieve the illumination and geometric conditions of each image. Color cubes of the surface have been hence produced by stacking registered and photometrically corrected images. Globally, the nucleus has spectrophotometric properties in the NUV-VIS-NIR range similar to those of bare cometary nuclei, of primitive D-type asteroids such us Jupiter Trojans, and of the moderately red Transneptunians and Centaurs. No clear absorption bands have been detected so far at the resolution of the used filters. The global spectral slope, evaluated in the 535-880 nm range, varies between 11 %/(100 nm) at a phase angle of 1.3 degrees and 16 %/(100 nm) at a phase angle of 52 degrees, implying a significant phase reddening. Despite the different types of terrains and morphological features seen on the comet (Thomas et al. 2015), the nucleus shows small color variations, with the notable exception of the Hapi region (Sierks et al., 2015). This region is located

  13. Spectrophotometry of Thin Films of Light-Absorbing Particles.

    PubMed

    Binks, Bernard P; Fletcher, Paul D I; Johnson, Andrew J; Marinopoulos, Ioannis; Crowther, Jonathan M; Thompson, Michael A

    2017-04-06

    Thin films of dispersions of light-absorbing solid particles or emulsions containing a light-absorbing solute all have a nonuniform distribution of light-absorbing species throughout the sample volume. This results in nonuniform light absorption over the illuminated area, which causes the optical absorbance, as measured using a conventional specular UV-vis spectrophotometer, to deviate from the Beer-Lambert relationship. We have developed a theoretical model to account for the absorbance properties of such films, which are shown to depend on the size and volume fraction of the light-absorbing particles plus other sample variables. We have compared model predictions with measured spectra for samples consisting of emulsions containing a dissolved light-absorbing solute. Using no adjustable parameters, the model successfully predicts the behavior of nonuniform, light-absorbing emulsion films with varying values of droplet size, volume fraction, and other parameters.

  14. Spectrophotometry of emission-line stars in the magellanic clouds

    NASA Technical Reports Server (NTRS)

    Bohannan, Bruce

    1990-01-01

    The strong emission lines in the most luminous stars in the Magellanic Clouds indicate that these stars have such strong stellar winds that their photospheres are so masked that optical absorption lines do not provide an accurate measure of photospheric conditions. In the research funded by this grant, temperatures and gravities of emission-line stars both in the Large (LMC) and Small Magellanic Clouds (SMC) have been measured by fitting of continuum ultraviolet-optical fluxes observed with IUE with theoretical model atmospheres. Preliminary results from this work formed a major part of an invited review 'The Distribution of Types of Luminous Blue Variables'. Interpretation of the IUE observations obtained in this grant and archive data were also included in a talk at the First Boulder-Munich Hot Stars Workshop. Final results of these studies are now being completed for publication in refereed journals.

  15. Atomic absorption spectrophotometric method for determination of polydimethylsiloxane residues in pineapple juice: collaborative study.

    PubMed

    Parker, R D

    1990-01-01

    An atomic absorption spectrophotometric method for determination of polydimethylsiloxane (PDMS) residues in pineapple juice was collaboratively studied by 9 laboratories. PDMS residues are extracted from pineapple juice with 4-methyl-2-pentanone and the extracted silicone is measured by atomic absorption spectrophotometry using a nitrous oxide/acetylene flame. Collaborators analyzed 5 samples including 1 blind duplicate. Reproducibility relative standard deviations (RSDR) were 13.1% at 31 ppm, 6.9% at 18 ppm, 14.8% at 7.9 ppm, and 16.1% at 4.9 ppm PDMS. The method has been approved interim official first action by AOAC.

  16. Subgap Absorption in Conjugated Polymers

    DOE R&D Accomplishments Database

    Sinclair, M.; Seager, C. H.; McBranch, D.; Heeger, A. J; Baker, G. L.

    1991-01-01

    Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10{sup {minus}5}, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of transparent'' materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination.

  17. [Study on the effect of extraction behaviour of molybdenum (V) thiocyanate complex in the dimethyl sulfoxide and water system by spectrophotometry].

    PubMed

    Liang, Yu-zhen; Gao, Lian-bin; Qu, Zeng-lu; He, Zhong-lin

    2003-02-01

    In this paper the effect of petroleum sulfoxide-carbon tetrachloride used as extractant on the extraction behaviour of molybdenum (V) thiocyanate complex at different concentration of dimethyl sulfoxide and water system is studied by spectrophotometry. The mixture ratio of extraction is directly calculated using spectrophotometric data. Functional relation of mixture ratio and concentration of thiocyanate in mixed solution is discussed. By increasing the percent of volume of dimethyl sulfoxide in mixed solution, the effects of mixture ratio and percentage of extraction were studied. The experimental results were explained. It shows that the extraction system of MoO (SCN)3 has an application value.

  18. Solubility of Lead Sulfate in Water and in Sodium Sulfate Solutions: An Experiment in Atomic Absorption Spectrophotometry.

    ERIC Educational Resources Information Center

    Lehman, Thomas A.; Everett, Wayne W.

    1982-01-01

    Describes a set of undergraduate laboratory experiments which provide experience in deuteration and derivatization procedures applied to infrared spectroscopy. Basic skills in vacuum-line technique are also taught while measuring infrared spectra of deuterated solid samples and demonstrating the value of derivatization as an aid to interpreting…

  19. Simultaneous spectrophotometric determination of Celecoxib and Diacerein in bulk and capsule by absorption correction method and chemometric methods

    NASA Astrophysics Data System (ADS)

    Patel, N. S.; Nandurbarkar, V. P.; Patel, A. J.; Patel, S. G.

    Two methods, absorption correction and multivariate spectrophotometric methods were developed for simultaneous estimation of Celecoxib (CEL) and Diacerein (DIA) in combined dosage form. Absorption correction method involves direct estimation of DIA at wavelength 341 nm in which CEL has zero absorbance and shows no interference. For estimation of CEL, corrected absorbance was calculated at 253 nm due to the interference of DIA at this wavelength. Linearity was observed in the range of 6-22 μg mL-1 for CEL and 3-11 μg mL-1 for DIA. The method was validated as per ICH guidelines. Chemometric methods including classical least square (CLS), inverse least square (ILS), principal component regression (PCR) and partial least square (PLS) were studied for simultaneous determination of CEL and DIA in capsule using spectrophotometry. A set of 25 standard mixtures containing both drugs were prepared in range of 5-25 μg mL-1 for CEL and 3-15 μg mL-1 for DIA. Analytical figure of merit (FOM), such as sensitivity, selectivity, analytical sensitivity, limit of detection and limit of quantitation were determined for chemometric methods. The proposed methods were applied for determination of two components from combined dosage form.

  20. Simultaneous spectrophotometric determination of celecoxib and diacerein in bulk and capsule by absorption correction method and chemometric methods.

    PubMed

    Patel, N S; Nandurbarkar, V P; Patel, A J; Patel, S G

    2014-05-05

    Two methods, absorption correction and multivariate spectrophotometric methods were developed for simultaneous estimation of Celecoxib (CEL) and Diacerein (DIA) in combined dosage form. Absorption correction method involves direct estimation of DIA at wavelength 341 nm in which CEL has zero absorbance and shows no interference. For estimation of CEL, corrected absorbance was calculated at 253 nm due to the interference of DIA at this wavelength. Linearity was observed in the range of 6-22 μg mL(-1) for CEL and 3-11 μg mL(-1) for DIA. The method was validated as per ICH guidelines. Chemometric methods including classical least square (CLS), inverse least square (ILS), principal component regression (PCR) and partial least square (PLS) were studied for simultaneous determination of CEL and DIA in capsule using spectrophotometry. A set of 25 standard mixtures containing both drugs were prepared in range of 5-25 μg mL(-1) for CEL and 3-15 μg mL(-1) for DIA. Analytical figure of merit (FOM), such as sensitivity, selectivity, analytical sensitivity, limit of detection and limit of quantitation were determined for chemometric methods. The proposed methods were applied for determination of two components from combined dosage form.

  1. Nickel absorption and kinetics in human volunteers

    SciTech Connect

    Sunderman, F.W. Jr.; Hopfer, S.M. ); Sweeney, K.R. ); Marcus, A.H.; Creason, J. ); Most, B.M. )

    1989-05-01

    Mathematical modeling of the kinetics of nickel absorption, distribution, and elimination was performed in healthy human volunteers who ingested NiSO{sub 4} drinking water (Experiment 1) or added to food (Experiment 2). Nickel was analyzed by electrothermal atomic absorption spectrophotometry in serum, urine, and feces collected during 2 days before and 4 days after a specified NiSO{sub 4} dose (12 {mu}g of nickel/kg, n = 4; 18 {mu}g of nickel/kg, n = 4; or 50 {mu}g of nickel/kg, n = 1). Absorbed nickel averaged 27 {plus minus} 17% (mean {plus minus} SD) of the dose ingested in water vs. 0.7 {plus minus} 0.4% of the same dose ingested in food (a 40-fold difference); rate constants for nickel absorption, transfer, and elimination were not significantly influenced by the oral vehicle. The elimination half-time for absorbed nickel averaged 28 {plus minus} 9 hr. Renal clearance of nickel averaged 8.3 {plus minus} 2.0 ml/min/1.73 m{sup 2} in Experiment 1 and 5.8 {plus minus} 4.3 ml/min/1.73 m{sub 2} in Experiment 2. This study confirms that dietary constituents profoundly reduce the bioavailability of Ni{sup 2+} for alimentary absorption; approximately one-quarter of nickel ingested in drinking water after an over-night fast is absorbed from the human intestine and excreted in urine, compared with only 1% of nickel ingested in food. The compartmental model and kinetic parameters provided by this study will reduce the uncertainty of toxicologic risk assessments of human exposures to nickel in drinking water and food.

  2. Delta bilirubin: absorption spectra, molar absorptivity, and reactivity in the diazo reaction.

    PubMed

    Doumas, B T; Wu, T W; Jendrzejczak, B

    1987-06-01

    Delta bilirubin (B delta), isolated from serum, has an absorption maximum near 440 nm and a molar absorptivity of 72,000 L mol-1cm-1 in either Tris HCl (0.1 mol/L, pH 8.5) or phosphate (0.13 mol/L, pH 7.4) buffer. This absorptivity exceeds by approximately 50% and 59%, respectively, that of unconjugated bilirubin in the same buffers. This finding suggests that substantial errors can be incurred in direct spectrophotometry of bilirubins in serum. In the total diazo (TBIL) assay (Clin Chem 1985;31:1779-89), the color yield from B delta increases by 10% as the final diazo concentration is increased from 0.27 to 0.81 mmol/L. In the direct (DBIL) assay, if done in HCl (50 mmol/L), B delta yields approximately 15% more color as the diazo concentration is increased from 0.51 to 1.53 mmol/L, whereas in acetate buffer (0.4 mol/L, pH 4.7) the corresponding color yield is 25% greater. However, the absolute color yield for the reaction in HCl exceeds that in acetate buffer. In both the TBIL and the DBIL assay, B delta reacts slowly, nearly complete reaction requiring 10 min. Thus, B delta may be seriously underestimated in diazo (especially DBIL) methods in which short reaction times (20 s to 1 min) are used.

  3. Television Quiz Show Simulation

    ERIC Educational Resources Information Center

    Hill, Jonnie Lynn

    2007-01-01

    This article explores the simulation of four television quiz shows for students in China studying English as a foreign language (EFL). It discusses the adaptation and implementation of television quiz shows and how the students reacted to them.

  4. [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

  5. Interaction of the carbon monoxide-releasing molecule Ru(CO)3Cl(glycinate) (CORM-3) with Salmonella enterica serovar Typhimurium: in situ measurements of carbon monoxide binding by integrating cavity dual-beam spectrophotometry.

    PubMed

    Rana, Namrata; McLean, Samantha; Mann, Brian E; Poole, Robert K

    2014-12-01

    Carbon monoxide (CO) is a toxic gas that binds to haems, but also plays critical signalling and cytoprotective roles in mammalian systems; despite problems associated with systemic delivery by inhalation of the gas, it may be employed therapeutically. CO delivered to cells and tissues by CO-releasing molecules (CO-RMs) has beneficial and toxic effects not mimicked by CO gas; CO-RMs are also attractive candidates as novel antimicrobial agents. Salmonella enterica serovar Typhimurium is an enteropathogen causing gastroenteritis in humans. Recent studies have implicated haem oxygenase-1 (HO-1), the protein that catalyses the degradation of haem into biliverdin, free iron and CO, in the host immune response to Salmonella infection. In several studies, CO administration via CO-RMs elicited many of the protective roles of HO-1 induction and so we investigated the effects of a well-characterized water-soluble CO-RM, Ru(CO)3Cl(glycinate) (CORM-3), on Salmonella. CORM-3 exhibits toxic effects at concentrations significantly lower than those reported to cause toxicity to RAW 264.7 macrophages. We demonstrated here, through oxyhaemoglobin assays, that CORM-3 did not release CO spontaneously in phosphate buffer, buffered minimal medium or very rich medium. CORM-3 was, however, accumulated to high levels intracellularly (as shown by inductively coupled plasma MS) and released CO inside cells. Using growing Salmonella cultures without prior concentration, we showed for the first time that sensitive dual-beam integrating cavity absorption spectrophotometry can detect directly the CO released from CORM-3 binding in real-time to haems of the bacterial electron transport chain. The toxic effects of CO-RMs suggested potential applications as adjuvants to antibiotics in antimicrobial therapy.

  6. An overview of liquid phase microextraction approaches combined with UV-Vis spectrophotometry.

    PubMed

    Dehghani Mohammad Abadi, Malihe; Ashraf, Narges; Chamsaz, Mahmoud; Shemirani, Farzaneh

    2012-09-15

    Ultraviolet and visible spectrophotometer has become a popular analytical instrument in the modern day laboratories. However, the low concentrations of many analytes in samples make it difficult to directly measure them by UV-Vis spectrophotometry. This overview focuses on the combinations of microvolume UV-Vis spectrophotometry with miniaturized approaches to sample preparation, namely, single drop microextraction (SDME), dispersive liquid-liquid microextraction (DLLME), cold induced aggregation microextraction (CIAME), in situ solvent formation microextraction (ISSFME), ultrasound assisted emulsification microextraction (USAEME), solidified floating organic drop microextraction (SFODME), and hollow fiber based liquid phase microextraction (HF-LPME) to improve both the selectivity and sensitivity. Integration of these techniques provides unique advantages which include availability, simplicity of operation, low cost, speed, precision and accuracy; hence making them a powerful tool in chemical analysis.

  7. Monitoring of monosaccharides, oligosaccharides, ethanol and glycerol during wort fermentation by biosensors, HPLC and spectrophotometry.

    PubMed

    Monošík, Rastislav; Magdolen, Peter; Stredanský, Miroslav; Šturdík, Ernest

    2013-05-01

    The aim of the present study was to analyze sugar levels (namely maltose, maltotriose, glucose and fructose) and alcohols (ethanol and glycerol) during the fermentation process in wort samples by amperometric enzymatic biosensors developed by our research group for industrial application, HPLC and spectrophotometry, and to compare the suitability of the presented methods for determination of individual analytes. We can conclude that for the specific monitoring of maltose or maltotriose only the HPLC method was suitable. On the other hand, biosensors and spectrophotometry reflected a decrease in total sugar concentration better and were able to detect both glucose and fructose in the later stages of fermentation, while HPLC was not. This can be attributed to the low detection limits and good sensitivity of the proposed methods. For the ethanol and glycerol analysis all methods proved to be suitable. However, concerning the cost expenses and time analysis, biosensors represented the best option.

  8. [Noninvasive total hemoglobin monitoring based on multiwave spectrophotometry in obstetrics and gynecology].

    PubMed

    Pyregov, A V; Ovechkin, A Iu; Petrov, S V

    2012-01-01

    Results of prospective randomized comparative research of 2 total hemoglobin estimation methods are presented. There were laboratory tests and continuous noninvasive technique with multiwave spectrophotometry on the Masimo Rainbow SET. Research was carried out in two stages. At the 1st stage (gynecology)--67 patients were included and in second stage (obstetrics)--44 patients during and after Cesarean section. The standard deviation of noninvasive total hemoglobin estimation from absolute values (invasive) was 7.2 and 4.1%, an standard deviation in a sample--5.2 and 2.7 % in gynecologic operations and surgical delivery respectively, that confirms lack of reliable indicators differences. The method of continuous noninvasive total hemoglobin estimation with multiwave spectrophotometry on the Masimo Rainbow SET technology can be recommended for use in obstetrics and gynecology.

  9. A comparison of photon counting and current measuring techniques in spectrophotometry of faint sources.

    PubMed

    Tull, R G

    1968-10-01

    The component of dark noise produced by Cerenkov pulses in photomultipliers due to cosmic ray mu mesons is discussed. It is shown by integration of pulse height spectra that this source of noise can be the limiting factor in de measuring spectrophotometry of faint astronomical sources. Direct current methods of photometry are compared with photon counting, and the advantage of photon counting is demonstrated under various operating conditions.

  10. Determination of acidity constants of acid-base indicators by second-derivative spectrophotometry

    NASA Astrophysics Data System (ADS)

    Kara, Derya; Alkan, Mahir

    2000-12-01

    A method for calculation of acid-base dissociation constants of monoprotic weak organic acids whose acid and base species have overlapping spectra from absorptiometric and pH measurements is described. It has been shown that the second-derivative spectrophotometry can effectively be used for determining the dissociation constants, when dissociation constants obtained for methyl orange and bromothymol blue were compared with the values given in the literature.

  11. A comparison of hair colour measurement by digital image analysis with reflective spectrophotometry.

    PubMed

    Vaughn, Michelle R; van Oorschot, Roland A H; Baindur-Hudson, Swati

    2009-01-10

    While reflective spectrophotometry is an established method for measuring macroscopic hair colour, it can be cumbersome to use on a large number of individuals and not all reflective spectrophotometry instruments are easily portable. This study investigates the use of digital photographs to measure hair colour and compares its use to reflective spectrophotometry. An understanding of the accuracy of colour determination by these methods is of relevance when undertaking specific investigations, such as those on the genetics of hair colour. Measurements of hair colour may also be of assistance in cases where a photograph is the only evidence of hair colour available (e.g. surveillance). Using the CIE L(*)a(*)b(*) colour space, the hair colour of 134 individuals of European ancestry was measured by both reflective spectrophotometry and by digital image analysis (in V++). A moderate correlation was found along all three colour axes, with Pearson correlation coefficients of 0.625, 0.593 and 0.513 for L(*), a(*) and b(*) respectively (p-values=0.000), with means being significantly overestimated by digital image analysis for all three colour components (by an average of 33.42, 3.38 and 8.00 for L(*), a(*) and b(*) respectively). When using digital image data to group individuals into clusters previously determined by reflective spectrophotometric analysis using a discriminant analysis, individuals were classified into the correct clusters 85.8% of the time when there were two clusters. The percentage of cases correctly classified decreases as the number of clusters increases. It is concluded that, although more convenient, hair colour measurement from digital images has limited use in situations requiring accurate and consistent measurements.

  12. Detecting estrogenic activity in water samples withestrogen-sensitive yeast cells using spectrophotometry and fluorescencemicroscopy

    SciTech Connect

    Wozei, E.; Holman, H-Y.N.; Hermanowicz, S.W.; Borglin S.

    2006-03-15

    Environmental estrogens are environmental contaminants that can mimic the biological activities of the female hormone estrogen in the endocrine system, i.e. they act as endocrine disrupters. Several substances are reported to have estrogen-like activity or estrogenic activity. These include steroid hormones, synthetic estrogens (xenoestrogens), environmental pollutants and phytoestrogens (plant estrogens). Using the chromogenic substrate ortho-nitrophenyl-{beta}-D-galactopyranoside (ONPG) we show that an estrogen-sensitive yeast strain RMY/ER-ERE, with human estrogen receptor (hER{alpha}) gene and the lacZ gene which encodes the enzyme {beta}-galactosidase, is able to detect estrogenic activity in water samples over a wide range of spiked concentrations of the hormonal estrogen 17{beta}-estradiol (E2). Ortho-nitrophenol (ONP), the yellow product of this assay can be detected using spectrophotometry but requires cell lysis to release the enzyme and allow product formation. We improved this aspect in a fluorogenic assay by using fluorescein di-{beta}-D-galactopyranoside (FDG) as a substrate. The product was visualized using fluorescence microscopy without the need to kill, fix or lyse the cells. We show that in live yeast cells, the uptake of E2 and the subsequent production of {beta}-galactosidase enzyme occur quite rapidly, with maximum enzyme-catalyzed fluorescent product formation evident after about 30 minutes of exposure to E2. The fluorogenic assay was applied to a selection of estrogenic compounds and the Synchrotron-based Fourier transform infrared (SR-FTIR) spectra of the cells obtained to better understand the yeast whole cell response to the compounds. The fluorogenic assay is most sensitive to E2, but the SR-FTIR spectra suggest that the cells respond to all the estrogenic compounds tested even when no fluorescent response was detected. These findings are promising and may shorten the duration of environmental water screening and monitoring regimes using

  13. Incomplete intestinal absorption of fructose.

    PubMed Central

    Kneepkens, C M; Vonk, R J; Fernandes, J

    1984-01-01

    Intestinal D-fructose absorption in 31 children was investigated using measurements of breath hydrogen. Twenty five children had no abdominal symptoms and six had functional bowel disorders. After ingestion of fructose (2 g/kg bodyweight), 22 children (71%) showed a breath hydrogen increase of more than 10 ppm over basal values, indicating incomplete absorption: the increase averaged 53 ppm, range 12 to 250 ppm. Four of these children experienced abdominal symptoms. Three of the six children with bowel disorders showed incomplete absorption. Seven children were tested again with an equal amount of glucose, and in three of them also of galactose, added to the fructose. The mean maximum breath hydrogen increases were 5 and 10 ppm, respectively, compared with 103 ppm after fructose alone. In one boy several tests were performed with various sugars; fructose was the only sugar incompletely absorbed, and the effect of glucose on fructose absorption was shown to be dependent on the amount added. It is concluded that children have a limited absorptive capacity for fructose. We speculate that the enhancing effect of glucose and galactose on fructose absorption may be due to activation of the fructose carrier. Apple juice in particular contains fructose in excess of glucose and could lead to abdominal symptoms in susceptible children. PMID:6476870

  14. Simultaneous determination of Cu 2+, Zn 2+, Cd 2+, Hg 2+ and Pb 2+ by using second-derivative spectrophotometry method

    NASA Astrophysics Data System (ADS)

    Han, Yanyan; Li, Yan; Si, Wei; Wei, Dong; Yao, Zhenxing; Zheng, Xianpeng; Du, Bin; Wei, Qin

    2011-09-01

    A new method of simultaneous determination of Cu 2+, Zn 2+, Cd 2+, Hg 2+ and Pb 2+ is proposed here by using the second-derivative spectrophotometry method. In pH = 10.35 Borax-NaOH buffer, using meso-tetra (3-methoxyl-4-hydroxylphenyl) porphyrin ([T-(3-MO-4-HP)P]) as chromomeric reagent, micelle solution was formed after Tween-80 surfactant was added into the solution containing Cu 2+, Zn 2+, Cd 2+, Hg 2+ and Pb 2+ ions. The original absorption spectrum of the above complexes was obtained after heating in the boiling water for 25 min. The second-derivative absorption peaks of five metal-porphyrin complexes can be separated from the original absorption spectrum by using chemometric tool. In this way, Cu 2+, Zn 2+, Cd 2+, Hg 2+ and Pb 2+ ions can be determined simultaneously. Under the optimal conditions, the linear ranges of the calibration curve were 0-0.60, 0-0.60, 0-0.40, 0-0.80 and 0-0.48 μg mL -1 for Cu 2+, Zn 2+, Cd 2+, Hg 2+ and Pb 2+, respectively. The molar absorptivity of these color systems were 1.38 × 10 5, 1.01 × 10 5, 3.24 × 10 5, 1.07 × 10 5 and 1.29 × 10 5 L mol -1 cm -1. The method developed in this paper has advantages in selectivity, sensitivity, operation and can effectively resolve spectra overlapping problem. This method has been applied to determine the real samples with satisfactory results.

  15. Tunneling induced absorption with competing Nonlinearities

    PubMed Central

    Peng, Yandong; Yang, Aihong; Xu, Yan; Wang, Peng; Yu, Yang; Guo, Hongju; Ren, Tingqi

    2016-01-01

    We investigate tunneling induced nonlinear absorption phenomena in a coupled quantum-dot system. Resonant tunneling causes constructive interference in the nonlinear absorption that leads to an increase of more than an order of magnitude over the maximum absorption in a coupled quantum dot system without tunneling. Resonant tunneling also leads to a narrowing of the linewidth of the absorption peak to a sublinewidth level. Analytical expressions show that the enhanced nonlinear absorption is largely due to the fifth-order nonlinear term. Competition between third- and fifth-order nonlinearities leads to an anomalous dispersion of the total susceptibility. PMID:27958303

  16. Showing What They Know

    ERIC Educational Resources Information Center

    Cech, Scott J.

    2008-01-01

    Having students show their skills in three dimensions, known as performance-based assessment, dates back at least to Socrates. Individual schools such as Barrington High School--located just outside of Providence--have been requiring students to actively demonstrate their knowledge for years. The Rhode Island's high school graduating class became…

  17. The Ozone Show.

    ERIC Educational Resources Information Center

    Mathieu, Aaron

    2000-01-01

    Uses a talk show activity for a final assessment tool for students to debate about the ozone hole. Students are assessed on five areas: (1) cooperative learning; (2) the written component; (3) content; (4) self-evaluation; and (5) peer evaluation. (SAH)

  18. What Do Maps Show?

    ERIC Educational Resources Information Center

    Geological Survey (Dept. of Interior), Reston, VA.

    This curriculum packet, appropriate for grades 4-8, features a teaching poster which shows different types of maps (different views of Salt Lake City, Utah), as well as three reproducible maps and reproducible activity sheets which complement the maps. The poster provides teacher background, including step-by-step lesson plans for four geography…

  19. Show Me the Way

    ERIC Educational Resources Information Center

    Dicks, Matthew J.

    2005-01-01

    Because today's students have grown up steeped in video games and the Internet, most of them expect feedback, and usually gratification, very soon after they expend effort on a task. Teachers can get quick feedback to students by showing them videotapes of their learning performances. The author, a 3rd grade teacher describes how the seemingly…

  20. Chemistry Game Shows

    NASA Astrophysics Data System (ADS)

    Campbell, Susan; Muzyka, Jennifer

    2002-04-01

    We present a technological improvement to the use of game shows to help students review for tests. Our approach uses HTML files interpreted with a browser on a computer attached to an LCD projector. The HTML files can be easily modified for use of the game in a variety of courses.

  1. Honored Teacher Shows Commitment.

    ERIC Educational Resources Information Center

    Ratte, Kathy

    1987-01-01

    Part of the acceptance speech of the 1985 National Council for the Social Studies Teacher of the Year, this article describes the censorship experience of this honored social studies teacher. The incident involved the showing of a videotape version of the feature film entitled "The Seduction of Joe Tynan." (JDH)

  2. Talk Show Science.

    ERIC Educational Resources Information Center

    Moore, Mitzi Ruth

    1992-01-01

    Proposes having students perform skits in which they play the roles of the science concepts they are trying to understand. Provides the dialog for a skit in which hot and cold gas molecules are interviewed on a talk show to study how these properties affect wind, rain, and other weather phenomena. (MDH)

  3. Stage a Water Show

    ERIC Educational Resources Information Center

    Frasier, Debra

    2008-01-01

    In the author's book titled "The Incredible Water Show," the characters from "Miss Alaineus: A Vocabulary Disaster" used an ocean of information to stage an inventive performance about the water cycle. In this article, the author relates how she turned the story into hands-on science teaching for real-life fifth-grade students. The author also…

  4. Fat-soluble vitamin intestinal absorption: absorption sites in the intestine and interactions for absorption.

    PubMed

    Goncalves, Aurélie; Roi, Stéphanie; Nowicki, Marion; Dhaussy, Amélie; Huertas, Alain; Amiot, Marie-Josèphe; Reboul, Emmanuelle

    2015-04-01

    The interactions occurring at the intestinal level between the fat-soluble vitamins A, D, E and K (FSVs) are poorly documented. We first determined each FSV absorption profile along the duodenal-colonic axis of mouse intestine to clarify their respective absorption sites. We then investigated the interactions between FSVs during their uptake by Caco-2 cells. Our data show that vitamin A was mostly absorbed in the mouse proximal intestine, while vitamin D was absorbed in the median intestine, and vitamin E and K in the distal intestine. Significant competitive interactions for uptake were then elucidated among vitamin D, E and K, supporting the hypothesis of common absorption pathways. Vitamin A also significantly decreased the uptake of the other FSVs but, conversely, its uptake was not impaired by vitamins D and K and even promoted by vitamin E. These results should be taken into account, especially for supplement formulation, to optimise FSV absorption.

  5. Objective evaluation by reflectance spectrophotometry can be of clinical value for the verification of blanching/non blanching erythema in the sacral area.

    PubMed

    Sterner, Eila; Fossum, Bjöörn; Berg, Elisabeth; Lindholm, Christina; Stark, André

    2014-08-01

    Early detection of non blanching erythema (pressure ulcer category I) is necessary to prevent any further skin damage. An objective method to discriminate between blanching/non blanching erythema is presently not available. The purpose of this investigation was to explore if a non invasive objective method could differentiate between blanching/non blanching erythema in the sacral area of patients undergoing hip fracture surgery. Seventy-eight patients were included. The sacral area of all patients was assessed using (i) conventional finger-press test and (ii) digital reading of the erythema index assessed with reflectance spectrophotometry. The patients were examined at admission and during 5 days postsurgery. Reflectance spectrophotometry measurements proved able to discriminate between blanching/non blanching erythema. The reliability, quantified by the intra-class correlation coefficient, was excellent between repeated measurements over the measurement period, varying between 0·82 and 0·96, and a significant change was recorded in the areas from day 1 to day 5 (P < 0·0001). The value from the reference point did not show any significant changes over the same period (P = 0·32). An objective method proven to identify early pressure damage to tissue can be a valuable tool in clinical practice.

  6. Not a "reality" show.

    PubMed

    Wrong, Terence; Baumgart, Erica

    2013-01-01

    The authors of the preceding articles raise legitimate questions about patient and staff rights and the unintended consequences of allowing ABC News to film inside teaching hospitals. We explain why we regard their fears as baseless and not supported by what we heard from individuals portrayed in the filming, our decade-long experience making medical documentaries, and the full un-aired context of the scenes shown in the broadcast. The authors don't and can't know what conversations we had, what documents we reviewed, and what protections we put in place in each televised scene. Finally, we hope to correct several misleading examples cited by the authors as well as their offhand mischaracterization of our program as a "reality" show.

  7. Two-phase ultraviolet spectrophotometry of the pulsating white dwarf ZZ Piscium

    NASA Technical Reports Server (NTRS)

    Bond, H. E.; Kemper, E.; Grauer, A. D.; Holm, A. V.; Panek, R. J.; Schiffer, F. H., III

    1985-01-01

    Spectra of the pulsating white dwarf ZZ Psc (= G29-38) were obtained using the International Ultraviolet Explorer. By using a multiple-exposure technique in conjunction with simultaneous ground-based exposure-metering photometry, it was possible to obtain mean on-pulse and off-pulse spectra in the 1950-1310 A wavelength range. The ratio of the time-averaged on-pulse to off-pulse spectra is best fitted by a temperature variation that is in phase with the optical light variation. This result is consistent with the hypothesis that the observed variation is due to a high-order nonradial pulsation. Conventional ultraviolet spectra of ZZ Psc showed broad absorption features at 1390 and 1600 A. These features are also found in the spectra of the cool DA-type white dwarfs G226-29 and G67-23, and appear to increase in strength with decreasing temperature. A possible explanation for the 1600 A feature is absorption by the satellite band of resonance-broadened hydrogen Ly-alpha. Such absorption would also help explain a discrepancy between the observed pulsation amplitude shortward of 1650 A and the predicted amplitudes based on model atmospheres.

  8. Formaldehyde in Alcoholic Beverages: Large Chemical Survey Using Purpald Screening Followed by Chromotropic Acid Spectrophotometry with Multivariate Curve Resolution

    PubMed Central

    Jendral, Julien A.; Monakhova, Yulia B.; Lachenmeier, Dirk W.

    2011-01-01

    A strategy for analyzing formaldehyde in beer, wine, spirits, and unrecorded alcohol was developed, and 508 samples from worldwide origin were analyzed. In the first step, samples are qualitatively screened using a simple colorimetric test with the purpald reagent, which is extremely sensitive for formaldehyde (detection limit 0.1 mg/L). 210 samples (41%) gave a positive purpald reaction. In the second step, formaldehyde in positive samples is confirmed by quantitative spectrophotometry of the chromotropic acid-formaldehyde derivative combined with Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS). Calculation of UV-VIS and 13C NMR spectra confirmed the monocationic dibenzoxanthylium structure as the product of the reaction and disproved the widely cited para,para-quinoidal structure. Method validation for the spectrophotometric procedure showed a detection limit of 0.09 mg/L and a precision of 4.2–8.2% CV. In total, 132 samples (26%) contained formaldehyde with an average of 0.27 mg/L (range 0–14.4 mg/L). The highest incidence occurred in tequila (83%), Asian spirits (59%), grape marc (54%), and brandy (50%). Our survey showed that only 9 samples (1.8%) had formaldehyde levels above the WHO IPCS tolerable concentration of 2.6 mg/L. PMID:21760790

  9. The H-band emitting region of the luminous blue variable P Cygni: Spectrophotometry and interferometry of the wind

    SciTech Connect

    Richardson, N. D.; Gies, D. R.; Baron, F.; Parks, J. R.; Matson, R. A.; Touhami, Y.; Aldoretta, E. J.; McAlister, H. A.; Schaefer, G. H.; Ten Brummelaar, T. A.; Sturmann, J.; Sturmann, L.; Chesneau, O.; Monnier, J. D.; Che, X.; Clemens, D. P.; Taylor, B.; Morrison, N. D.; Kraus, S.; Ridgway, S. T.; and others

    2013-06-01

    We present the first high angular resolution observations in the near-infrared H band (1.6 μm) of the luminous blue variable star P Cygni. We obtained six-telescope interferometric observations with the CHARA Array and the MIRC beam combiner. These show that the spatial flux distribution is larger than expected for the stellar photosphere. A two-component model for the star (uniform disk) plus a halo (two-dimensional Gaussian) yields an excellent fit of the observations, and we suggest that the halo corresponds to flux emitted from the base of the stellar wind. This wind component contributes about 45% of the H-band flux and has an angular FWHM = 0.96 mas, compared to the predicted stellar diameter of 0.41 mas. We show several images reconstructed from the interferometric visibilities and closure phases, and they indicate a generally spherical geometry for the wind. We also obtained near-infrared spectrophotometry of P Cygni from which we derive the flux excess compared to a purely photospheric spectral energy distribution. The H-band flux excess matches that from the wind flux fraction derived from the two-component fits to the interferometry. We find evidence of significant near-infrared flux variability over the period from 2006 to 2010 that appears similar to the variations in the Hα emission flux from the wind.

  10. Formaldehyde in alcoholic beverages: large chemical survey using purpald screening followed by chromotropic Acid spectrophotometry with multivariate curve resolution.

    PubMed

    Jendral, Julien A; Monakhova, Yulia B; Lachenmeier, Dirk W

    2011-01-01

    A strategy for analyzing formaldehyde in beer, wine, spirits, and unrecorded alcohol was developed, and 508 samples from worldwide origin were analyzed. In the first step, samples are qualitatively screened using a simple colorimetric test with the purpald reagent, which is extremely sensitive for formaldehyde (detection limit 0.1 mg/L). 210 samples (41%) gave a positive purpald reaction. In the second step, formaldehyde in positive samples is confirmed by quantitative spectrophotometry of the chromotropic acid-formaldehyde derivative combined with Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS). Calculation of UV-VIS and (13)C NMR spectra confirmed the monocationic dibenzoxanthylium structure as the product of the reaction and disproved the widely cited para,para-quinoidal structure. Method validation for the spectrophotometric procedure showed a detection limit of 0.09 mg/L and a precision of 4.2-8.2% CV. In total, 132 samples (26%) contained formaldehyde with an average of 0.27 mg/L (range 0-14.4 mg/L). The highest incidence occurred in tequila (83%), Asian spirits (59%), grape marc (54%), and brandy (50%). Our survey showed that only 9 samples (1.8%) had formaldehyde levels above the WHO IPCS tolerable concentration of 2.6 mg/L.

  11. Public medical shows.

    PubMed

    Walusinski, Olivier

    2014-01-01

    In the second half of the 19th century, Jean-Martin Charcot (1825-1893) became famous for the quality of his teaching and his innovative neurological discoveries, bringing many French and foreign students to Paris. A hunger for recognition, together with progressive and anticlerical ideals, led Charcot to invite writers, journalists, and politicians to his lessons, during which he presented the results of his work on hysteria. These events became public performances, for which physicians and patients were transformed into actors. Major newspapers ran accounts of these consultations, more like theatrical shows in some respects. The resultant enthusiasm prompted other physicians in Paris and throughout France to try and imitate them. We will compare the form and substance of Charcot's lessons with those given by Jules-Bernard Luys (1828-1897), Victor Dumontpallier (1826-1899), Ambroise-Auguste Liébault (1823-1904), Hippolyte Bernheim (1840-1919), Joseph Grasset (1849-1918), and Albert Pitres (1848-1928). We will also note their impact on contemporary cinema and theatre.

  12. Optical spectrophotometry of oscillations and flickering in AE Aquarii

    NASA Technical Reports Server (NTRS)

    Welsh, William F.; Horne, Keith; Oke, J. B.

    1993-01-01

    We observed rapid variations in the nova-like cataclysmic variable AE Aquarii for 1.7 hr with 4.3 s time resolution using the 30-channel (3227-10494 A) spectrophotometer on the Hale 5 m telescope. The 16.5 and 33.0 s oscillations show a featureless blue spectrum that can be represented by a blackbody with temperature and area much smaller than the accretion disk. Models consisting of the sum of a K star spectrum and a hydrogen slab in LTE at T = 6000-10,000 K can fit the spectrum of AE Aquarii reasonably well. The spectrum of a flare indicates optically thin gas with T = 8000-12,000 K. The energy released by the flare is large compared to typical stellar flares.

  13. Spectrophotometry of Bowen resonance fluorescence lines in three planetary nebulae

    NASA Technical Reports Server (NTRS)

    O'Dell, C. R.; Miller, Christopher O.

    1992-01-01

    The results are presented of a uniquely complete, carefully reduced set of observations of the O III Bowen fluorescence lines in the planetary nebulae NGC 6210, NGC 7027, and NGC 7662. A detailed comparison with the predictions of radiative excitation verify that some secondary lines are enhanced by selective population by the charge exchange mechanism involving O IV. Charge exchange is most important in NGC 6210, which is of significantly lower ionization than the other nebulae. In addition to the principal Bowen lines arising from Ly-alpha pumping of the O III O1 line, lines arising from pumping of the O3 line are also observed. Comparison of lines produced by O1 and O3 with the theoretical predictions of Neufeld indicate poor agreement; comparison with the theoretical predictions of Harrington show agreement with NGC 7027 and NGC 7662.

  14. The Great Cometary Show

    NASA Astrophysics Data System (ADS)

    2007-01-01

    its high spatial and spectral resolution, it was possible to zoom into the very heart of this very massive star. In this innermost region, the observations are dominated by the extremely dense stellar wind that totally obscures the underlying central star. The AMBER observations show that this dense stellar wind is not spherically symmetric, but exhibits a clearly elongated structure. Overall, the AMBER observations confirm that the extremely high mass loss of Eta Carinae's massive central star is non-spherical and much stronger along the poles than in the equatorial plane. This is in agreement with theoretical models that predict such an enhanced polar mass-loss in the case of rapidly rotating stars. ESO PR Photo 06c/07 ESO PR Photo 06c/07 RS Ophiuchi in Outburst Several papers from this special feature focus on the later stages in a star's life. One looks at the binary system Gamma 2 Velorum, which contains the closest example of a star known as a Wolf-Rayet. A single AMBER observation allowed the astronomers to separate the spectra of the two components, offering new insights in the modeling of Wolf-Rayet stars, but made it also possible to measure the separation between the two stars. This led to a new determination of the distance of the system, showing that previous estimates were incorrect. The observations also revealed information on the region where the winds from the two stars collide. The famous binary system RS Ophiuchi, an example of a recurrent nova, was observed just 5 days after it was discovered to be in outburst on 12 February 2006, an event that has been expected for 21 years. AMBER was able to detect the extension of the expanding nova emission. These observations show a complex geometry and kinematics, far from the simple interpretation of a spherical fireball in extension. AMBER has detected a high velocity jet probably perpendicular to the orbital plane of the binary system, and allowed a precise and careful study of the wind and the shockwave

  15. Stretched View Showing 'Victoria'

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Stretched View Showing 'Victoria'

    This pair of images from the panoramic camera on NASA's Mars Exploration Rover Opportunity served as initial confirmation that the two-year-old rover is within sight of 'Victoria Crater,' which it has been approaching for more than a year. Engineers on the rover team were unsure whether Opportunity would make it as far as Victoria, but scientists hoped for the chance to study such a large crater with their roving geologist. Victoria Crater is 800 meters (nearly half a mile) in diameter, about six times wider than 'Endurance Crater,' where Opportunity spent several months in 2004 examining rock layers affected by ancient water.

    When scientists using orbital data calculated that they should be able to detect Victoria's rim in rover images, they scrutinized frames taken in the direction of the crater by the panoramic camera. To positively characterize the subtle horizon profile of the crater and some of the features leading up to it, researchers created a vertically-stretched image (top) from a mosaic of regular frames from the panoramic camera (bottom), taken on Opportunity's 804th Martian day (April 29, 2006).

    The stretched image makes mild nearby dunes look like more threatening peaks, but that is only a result of the exaggerated vertical dimension. This vertical stretch technique was first applied to Viking Lander 2 panoramas by Philip Stooke, of the University of Western Ontario, Canada, to help locate the lander with respect to orbiter images. Vertically stretching the image allows features to be more readily identified by the Mars Exploration Rover science team.

    The bright white dot near the horizon to the right of center (barely visible without labeling or zoom-in) is thought to be a light-toned outcrop on the far wall of the crater, suggesting that the rover can see over the low rim of Victoria. In figure 1, the northeast and southeast rims are labeled

  16. Atmospheric absorption cell characterization

    NASA Astrophysics Data System (ADS)

    1982-06-01

    The measurement capability of the Avionics Laboratory IR Facility was used to evaluate an absorption cell that will be used to simulate atmospheric absorption over horizontal paths of 1 - 10 km in length. Band models were used to characterize the transmittance of carbon dioxide (CO2), nitrogen (N2), and nitrous oxide (N2O) in the cell. The measured transmittance was compared to the calculated values. Nitrous oxide is important in the 4 - 4.5 micron range in shaping the weak line absorption of carbon dioxide. The absorption cell is adequate for simulating atmospheric absorption over these paths.

  17. Spectrophotometry of Dust in Comet Hale-Bopp

    NASA Technical Reports Server (NTRS)

    Witteborn, Fred C. (Technical Monitor)

    1997-01-01

    Comets, such as Hale-Bopp (C/1995 O1), are frozen reservoirs of primitive solar nebula dust grains and ices. Analysis of the composition of cometary dust grains from infrared spectroscopic techniques permits an estimation of the types of organic and inorganic materials that constituted the early primitive solar nebula. In addition, the cometary bombardment of the Earth (approximately 3.5 Gy ago) supplied the water for the oceans and brought organic materials to Earth which may have been biogenic. Spectroscopic observations of comet Hale-Bopp suggest the possible presence of organic hydrocarbon species, silicate and olivine dust grains, and water ice. Spectroscopy near 3 microns obtained in Nov 1996 r=2.393 AU, delta=3.034 AU) shows a feature which we attribute to PAH emission. The spatial morphology of the 3.28 microns PAH feature is also presented. Optical and infrared spectrophotometric observations of comets convey valuable information about the spatial distribution and properties of dust and gas within the inner coma. In the optical and NIR shortward of 2 microns, the observed light is primarily scattered sunlight from the dust grains. At longer wavelengths, particularly in the 10 gm window, thermal emission from these grains dominates the radiation allowing an accurate estimate of grain sizes and chemical composition. Here we present an initial analysis of spectra taken with the NASA HIFOGS at 7-14 microns as part of a multiwavelength temporal study of the "comet of the century".

  18. Spectrophotometry and organic matter on Iapetus. 1: Composition models

    NASA Technical Reports Server (NTRS)

    Wilson, Peter D.; Sagan, Carl

    1995-01-01

    Iapetus shows a greater hemispheric albedo asymmetry than any other body in the solar system. Hapke scattering theory and optical constants measured in the laboratory are used to identify possible compositions for the dark material on the leading hemisphere of Iapetus. The materials considered are poly-HCN, kerogen, Murchison organic residue, Titan tholin, ice tholin, and water ice. Three-component mixtures of these materials are modeled in intraparticle mixture of 25% poly-HCN, 10% Murchison residue, and 65% water ice is found to best fit the spectrum, albedo, and phase behavior of the dark material. The Murchison residue and/or water ice can be replaced by kerogen and ice tholin, respectively, and still produce very good fits. Areal and particle mixtures of poly-HCN, Titan tholin, and either ice tholin or Murchison residue are also possible models. Poly-HCN is a necessary component in almost all good models. The presence of poly-HCN can be further tested by high-resolution observations near 4.5 micrometers.

  19. The use of spectrophotometry to estimate melanin density in Caucasians.

    PubMed

    Dwyer, T; Muller, H K; Blizzard, L; Ashbolt, R; Phillips, G

    1998-03-01

    The density of cutaneous melanin may be the property of the skin that protects it from damage by solar radiation, but there is not an accepted, noninvasive method of measuring it. To determine whether the density of cutaneous melanin can be estimated from reflectance of visible light by the skin, reflectance of 15-nm wavebands of light by the skin of the inner upper arm of each of 82 volunteers was measured at 20-nm intervals with a Minolta 508 spectrophotometer. A 3-mm skin biopsy was then taken from the same site, and four nonserial sections of it were stained with Masson Fontana for melanin. The melanin content of the basal area was calculated using the NIH Image analysis system. We show that cutaneous melanin in Caucasians can be estimated by the difference between two measurements of reflectance of visible light by the skin: those at wavelengths 400 and 420 nm. This new spectrophotometric measurement was more highly correlated (r = 0.68) with the histological measurements of cutaneous melanin than was skin reflectance of light of wavelength 680 nm (r = 0.33). Reflectances in the range of 650-700 nm have been used previously in skin cancer research. This relatively accurate measurement of melanin is quick and noninvasive and can be readily used in the field. It should provide improved discrimination of individual susceptibility to epidermal tumors in Caucasians and information about melanin's biological role in the causation of skin cancer.

  20. The quantification of spermatozoa by real-time quantitative PCR, spectrophotometry, and spermatophore cap size.

    PubMed

    Doyle, Jacqueline M; McCormick, Cory R; DeWoody, J Andrew

    2011-01-01

    Many animals, such as crustaceans, insects, and salamanders, package their sperm into spermatophores, and the number of spermatozoa contained in a spermatophore is relevant to studies of sexual selection and sperm competition. We used two molecular methods, real-time quantitative polymerase chain reaction (RT-qPCR) and spectrophotometry, to estimate sperm numbers from spermatophores. First, we designed gene-specific primers that produced a single amplicon in four species of ambystomatid salamanders. A standard curve generated from cloned amplicons revealed a strong positive relationship between template DNA quantity and cycle threshold, suggesting that RT-qPCR could be used to quantify sperm in a given sample. We then extracted DNA from multiple Ambystoma maculatum spermatophores, performed RT-qPCR on each sample, and estimated template copy numbers (i.e. sperm number) using the standard curve. Second, we used spectrophotometry to determine the number of sperm per spermatophore by measuring DNA concentration relative to the genome size. We documented a significant positive relationship between the estimates of sperm number based on RT-qPCR and those based on spectrophotometry. When these molecular estimates were compared to spermatophore cap size, which in principle could predict the number of sperm contained in the spermatophore, we also found a significant positive relationship between sperm number and spermatophore cap size. This linear model allows estimates of sperm number strictly from cap size, an approach which could greatly simplify the estimation of sperm number in future studies. These methods may help explain variation in fertilization success where sperm competition is mediated by sperm quantity.

  1. The HI absorption "Zoo"

    NASA Astrophysics Data System (ADS)

    Geréb, K.; Maccagni, F. M.; Morganti, R.; Oosterloo, T. A.

    2015-03-01

    We present an analysis of the H I 21 cm absorption in a sample of 101 flux-selected radio AGN (S1.4 GHz> 50 mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). We detect H I absorption in 32 objects (30% of the sample). In a previous paper, we performed a spectral stacking analysis on the radio sources, while here we characterize the absorption spectra of the individual detections using the recently presented busy function. The H I absorption spectra show a broad variety of widths, shapes, and kinematical properties. The full width half maximum (FWHM) of the busy function fits of the detected H I lines lies in the range 32 km s-1absorption (FW20) lies in the range 63 km s-1 200 km s-1). We study the kinematical and radio source properties of each group, with the goal of identifying different morphological structures of H I. Narrow lines mostly lie at the systemic velocity and are likely produced by regularly rotating H I disks or gas clouds. More H I disks can be present among galaxies with lines of intermediate widths; however, the H I in these sources is more unsettled. We study the asymmetry parameter and blueshift/redshift distribution of the lines as a function of their width. We find a trend for which narrow profiles are also symmetric, while broad lines are the most asymmetric. Among the broadest lines, more lines appear blueshifted than redshifted, similarly to what was found by previous studies. Interestingly, symmetric broad lines are absent from the sample. We argue that if a profile is broad, it is also asymmetric and shifted relative to the systemic velocity because it is tracing unsettled H I gas. In particular, besides three of the broadest (up to FW20 = 825 km s-1

  2. Self-scanned photodiode array - High performance operation in high dispersion astronomical spectrophotometry

    NASA Technical Reports Server (NTRS)

    Vogt, S. S.; Tull, R. G.; Kelton, P.

    1978-01-01

    A multichannel spectrophotometric detector system has been developed using a 1024 element self-scanned silicon photodiode array, which is now in routine operation with the high-dispersion coude spectrograph of the University of Texas McDonald Observatory 2.7-m telescope. Operational considerations in the use of such arrays for high precision and low light level spectrophotometry are discussed. A detailed description of the system is presented. Performance of the detector as measured in the laboratory and on astronomical program objects is described, and it is shown that these arrays are highly effective detectors for high dispersion astronomical spectroscopy.

  3. The spectrophotometry and chemical composition of the oxygen-poor bipolar nebula NGC 6164-5

    NASA Technical Reports Server (NTRS)

    Dufour, Reginald J.; Parker, Robert A. R.; Henize, Karl G.

    1988-01-01

    The paper presents new ground-based and IUE spectrophotometry of several positions in NGC 6164-5 surrounding the Population I Of star HD 148937. Electron temperatures, densities, and abundances are derived for the various positions in the nebula using spectral line information. For all of the regions observed, Ne/H is depleted by an amount comparable to O/H, while S/H and Ar/H have normal values. The results suggest that the nebula consists partly of material ejected from inner shell-burning regions of the Of star. In effect, HD 148937 is older and more advanced than what was previously thought.

  4. A straightforward ninhydrin-based method for collagenase activity and inhibitor screening of collagenase using spectrophotometry.

    PubMed

    Zhang, Yanfang; Fu, Yun; Zhou, Sufeng; Kang, Lixia; Li, Changzheng

    2013-06-01

    Currently protease assay kits, requiring substrate that is either radiolabeled or fluorescence labeled and specialized instruments, are all expensive. A simple, reliable assay of protease activity and its inhibitor screening for general laboratory is rare. Here we demonstrated a straightforward ninhydrin-based method for assay of collagenase activity and its inhibitor screening using spectrophotometry. In the method, without multistep sample treatments and substrate labeling, the hydrolytic products were directly traced by ninhydrin. The method is expected to be suitable for not only the assay of collagenase activity but also the others matrix metalloproteinases activities, and can be used for kinetic study.

  5. Near-infrared and ultraviolet spectrophotometry of the young planetary nebula Hubble 12

    NASA Technical Reports Server (NTRS)

    Rudy, Richard J.; Rossano, George S.; Erwin, Peter; Puetter, R. C.; Feibelman, Walter A.

    1993-01-01

    The young planetary nebula Hubble 12 is observed using near-IR and UV spectrophotometry. The brightness of the O I lines, which is greater than in any other planetary nebula yet measured, indicates that fluorescent excitation by stellar continuum is the principal mechanism generating these lines. Extinction, electron density, and electron temperature are determined using infrared measurements combined with UV data and published optical observations. The range in extinction, density, and temperature implies that, within the ionized region, pockets of emission with distinctly different conditions exist. Logarithmic abundances for helium, oxygen, and sulfur are presented.

  6. 8- to 13-micron spectrophotometry of Comet IRAS-Araki-Alcock

    NASA Technical Reports Server (NTRS)

    Feierberg, M. A.; Witteborn, F. C.; Johnson, J. R.; Campins, H.

    1984-01-01

    Spectrophotometry between 8.0 and 13.0 microns at 2 percent spectral resolution is presented for areas in and near the nuclear condensation of Comet IRAS-Araki-Alcock (1983d) on May 11 and 12, 1983. All the spectra can be fit very well by blackbody curves, and no 10-micron silicate emissions are seen. The temperature structure of the coma suggests the presence of small (radii less than 5 microns) dust particles within 150 km of the nucleus and larger ones further out. The change in the spatial distribution of the infrared flux between the two nights suggests that an outburst may have occurred sometime on May 11.

  7. Documentation for the machine-readable version of the Absolute Calibration of Stellar Spectrophotometry

    NASA Technical Reports Server (NTRS)

    Warren, W. H., Jr.

    1982-01-01

    The machine-readable data file of The Absolute Calibration of Stellar Spectrophotometry as distributed by the Astronomical Data Center is described. The data file contains the absolute fluxes for 16 stars published in Tables 1 and 2 of Johnson (1980). The absolute calibrations were accomplished by combining the 13-color photometry calibrations of Johnson and Mitchell (1975) with spectra obtained with a Michelson spectrophotometer and covering the wavelength range 4000 to 10300 A (Johnson 1977). The agreement between this absolute calibration and another recent one based upon data for a Lyr and 109 Vir by Tug, White and Lockwood (1977) is shown by Johnson (1980) to be quite good.

  8. A comparative study of UV-spectrophotometry and first-order derivative UV-spectrophotometry methods for the estimation of diazepam in presence of Tween-20 and propylene glycol.

    PubMed

    Dastidar, Debabrata Ghosh; Sa, Biswanath

    2009-01-01

    Nonionic surfactants like polysorbates (Tweens) and co-surfactant like propylene glycol are used in pharmaceutical dosage forms, like microemulsion of diazepam. These additives interfere significantly with the estimation of diazepam by UV spectrophotomery method. The aim of this work was to develop a first-order derivative UV-spectrophotometry method that can estimate diazepam in presence of Tween-20 and propylene glycol. The experimental results clearly suggested that, in comparison with the UV-spectrophotometry method, the first-order derivative UV-spectrophotometry is a simple method to estimate diazepam with sufficient accuracy, specificity, and precision even in the presence of 282-times Tween-20 and 2,072-times propylene glycol.

  9. UV-visible scanning spectrophotometry and chemometric analysis as tools for carotenoids analysis in cassava genotypes (Manihot esculenta Crantz).

    PubMed

    Moresco, Rodolfo; Uarrota, Virgílio Gavicho; Pereira, Aline; Tomazzoli, Maíra Maciel; Nunes, Eduardo da C; Peruch, Luiz Augusto Martins; Gazzola, Jussara; Costa, Christopher; Rocha, Miguel; Maraschin, Marcelo

    2015-10-21

    In this study, the metabolomics characterization focusing on the carotenoid composition of ten cassava (Manihot esculenta) genotypes cultivated in southern Brazil by UV-visible scanning spectrophotometry and reverse phase-high performance liquid chromatography was performed. Cassava roots rich in β-carotene are an important staple food for populations with risk of vitamin A deficiency. Cassava genotypes with high pro-vitamin A activity have been identified as a strategy to reduce the prevalence of deficiency of this vitamin. The data set was used for the construction of a descriptive model by chemometric analysis. The genotypes of yellow-fleshed roots were clustered by the higher concentrations of cis-β-carotene and lutein. Inversely, cream-fleshed roots genotypes were grouped precisely due to their lower concentrations of these pigments, as samples rich in lycopene (red-fleshed) differed among the studied genotypes. The analytical approach (UV-Vis, HPLC, and chemometrics) used showed to be efficient for understanding the chemodiversity of cassava genotypes, allowing to classify them according to important features for human health and nutrition.

  10. Comparison of three methods of DNA extraction in endocervical specimens for Chlamydia trachomatis infection by spectrophotometry, agarose gel, and PCR.

    PubMed

    Jenab, Anahita; Roghanian, Rasoul; Golbang, Naser; Golbang, Pouran; Chamani-Tabriz, Leili

    2010-06-01

    Chlamydia trachomatis is the major cause of sexually transmitted disease in the world. The aim of this study was to determine the best method of DNA extraction for detecting C. trachomatis by polymerase chain reaction (PCR) in sexually active women (n = 80) attending Shahid Beheshti Hospital in Isfahan, Iran. Endocervical swabs were collected from 80 women, 22 of whom were asymptomatic and 58 symptomatic. Three different DNA extraction methods were used in this study (phenol-chlorophorm, proteinase K, and boiling). DNA yield was evaluated by spectrophotometry, agarose gel, and PCR. The internal control was assayed by beta-globin primers (PCO4, GH20). The DNA cryptic plasmid was selected as the target for C. trachomatis and samples were examined by PCR using specific KL1 and KL2 primers. It was shown that DNA extraction by boiling was the most sensitive with the highest yield of DNA. Of the 80 samples, 17 (21.25%) showed positivity for C. trachomatis by PCR. The highest rate of C. trachomatis infection was found in the group aged between 35 and 45 years old and those who used withdrawal or an intrauterine device as methods of contraception. It was demonstrated that DNA extraction by boiling was the least expensive and a very rapid method that gave the highest DNA yield. The infection rate in the sexually active women, including symptomatic and asymptomatic, was 21.25%, with a presumably high prevalence compared with other studies done in this field.

  11. Combination of solid phase extraction and dispersive liquid-liquid microextraction for separation/preconcentration of ultra trace amounts of uranium prior to its fiber optic-linear array spectrophotometry determination.

    PubMed

    Dadfarnia, Shayessteh; Shabani, Ali Mohammad Haji; Shakerian, Farid; Shiralian Esfahani, Golnaz

    2013-12-15

    A simple and sensitive method for the separation and preconcentration of the ultra trace amounts of uranium and its determination by spectrophotometry was developed. The method is based on the combination of solid phase extraction and dispersive liquid-liquid microextraction. Thus, by passing the sample through the basic alumina column, the uranyl ion and some cations are separated from the sample matrix. The retained uranyl ion along with the cations are eluted with 5 mL of nitric acid (2 mol L(-1)) and after neutralization of the eluent, the extracted uranyl ion is converted to its anionic benzoate complex and is separated from other cations by extraction of its ion pair with malachite green into small volume of chloroform using dispersive liquid-liquid microextraction. The amount of uranium is then determined by the absorption measurement of the extracted ion pair at 621 nm using flow injection spectrophotometry. Under the optimum conditions, with 500 mL of the sample, a preconcentration factor of 1980, a detection limit of 40 ng L(-1), and a relative standard deviation of 4.1% (n=6) at 400 ng L(-1) were obtained. The method was successfully applied to the determination of uranium in mineral water, river water, well water, spring water and sea water samples.

  12. Spectrophotometry of peculiar B and A stars. XIV - 56 Arietis, 41 Tauri, 25 Sextantis, HD 170973, HD 205087, and HD 215441

    NASA Astrophysics Data System (ADS)

    Adelman, S. J.

    1983-03-01

    Optical region spectrophotometry of six relatively hot Ap stars is presented. Additional scans of 56 Ari extend the results of an earlier paper in this series. The data for 41 Tau, 25 Sex, HD 170973, and HD 215441 are studied as a function of phase. The observations of HD 205087 are inconclusive about its variability although they show spectrophotometrically that it is a definite Ap star. The observations of HD 215441 show a prominent λ5200 broad, continuum feature with an unusual shape. However, when the data are corrected for interstellar reddening, the energy distribution resembles those of other silicon stars. The λ5200 feature is found to be variable in phase with the U-B and B-V colors and with the magnetic field strength. This feature is strongest when the Balmer jump is smallest, the Paschen continuum the bluest according to B-V, and the surface magnetic field strength the largest.

  13. Optical Absorption, Stability and Structure of NpO2+ Complexeswith Dicarboxylic Acids

    SciTech Connect

    Guoxin Tian; Linfeng Rao

    2006-01-04

    Complexation of NpO2+ with oxalic acid (OX),2,2'-oxydiacetic acid (ODA), 2,2'-iminodiacetic acid (IDA) and 2,2'-thiodiacetic acid (TDA), has been studied using spectrophotometry in1 M NaClO4. Both the position and the intensity of the absorption band of NpO2+ at 980 nm are affected by the formation of NpO2+/dicarboxylate complexes, providing useful information on the complexation strength, the coordination mode and the structure of the complexes.

  14. Analysis of frequency dependent pump light absorption

    NASA Astrophysics Data System (ADS)

    Wohlmuth, Matthias; Pflaum, Christoph

    2011-03-01

    Simulations have to accurately model thermal lensing in order to help improving resonator design of diode pumped solid state lasers. To this end, a precise description of the pump light absorption is an important prerequisite. In this paper, we discuss the frequency dependency of the pump light absorption in the laser crystal and its influence on the simulated laser performance. The results show that the pump light absorption has to include the spectral overlap of the emitting pump source and the absorbing laser material. This information can either be used for a fully frequency dependent absorption model or, at least in the shown examples, to compute an effective value for an exponential Beer-Lambert law of absorption. This is particularly significant at pump wavelengths coinciding with a peak of absorption. Consequences for laser stability and performance are analyzed for different pump wavelengths in a Nd:YAG laser.

  15. Use of reflectance spectrophotometry to predict the response of port wine stains to pulsed dye laser.

    PubMed

    Halachmi, Shlomit; Azaria, Ron; Inbar, Roy; Ad-El, Dean; Lapidoth, Moshe

    2014-01-01

    Reflectance spectroscopy can be used to quantitate subtle differences in color. We applied a portable reflectance spectrometer to determine its utility in the evaluation of pulsed dye laser treatment of port wine stains (PWS) and in prediction of clinical outcome, in a prospective study. Forty-eight patients with PWS underwent one to nine pulsed dye laser treatments. Patient age and skin color as well as PWS surface area, anatomic location, and color were recorded. Pretreatment spectrophotometric measurements were performed. The subjective clinical results of treatment and the quantitative spectrophotometry results were evaluated by two independent teams, and the findings were correlated. The impact of the clinical characteristics on the response to treatment was assessed as well. Patients with excellent to good clinical results of laser treatments had pretreatment spectrophotometric measurements which differed by more than 10%, whereas patients with fair to poor results had spectrophotometric measurements with a difference of of less than 10%. The correlation between the spectrophotometric results and the clinical outcome was 73% (p < 0.01). The impact of the other clinical variables on outcome agreed with the findings in the literature. Spectrophotometry has a higher correlation with clinical outcome and a better predictive value than other nonmeasurable, nonquantitative, dependent variables.

  16. Preparation of Ion Exchange Films for Solid-Phase Spectrophotometry and Solid-Phase Fluorometry

    NASA Technical Reports Server (NTRS)

    Hill, Carol M.; Street, Kenneth W.; Tanner, Stephen P.; Philipp, Warren H.

    2000-01-01

    Atomic spectroscopy has dominated the field of trace inorganic analysis because of its high sensitivity and selectivity. The advantages gained by the atomic spectroscopies come with the disadvantage of expensive and often complicated instrumentation. Solid-phase spectroscopy, in which the analyte is preconcentrated on a solid medium followed by conventional spectrophotometry or fluorometry, requires less expensive instrumentation and has considerable sensitivity and selectivity. The sensitivity gains come from preconcentration and the use of chromophore (or fluorophore) developers and the selectivity is achieved by use of ion exchange conditions that favor the analyte in combination with speciative chromophores. Little work has been done to optimize the ion exchange medium (IEM) associated with these techniques. In this report we present a method for making ion exchange polymer films, which considerably simplify the solid-phase spectroscopic techniques. The polymer consists of formaldehyde-crosslinked polyvinyl alcohol with polyacrylic acid entrapped therein. The films are a carboxylate weak cation exchanger in the calcium form. They are mechanically sturdy and optically transparent in the ultraviolet and visible portion of the spectrum, which makes them suitable for spectrophotometry and fluorometry.

  17. High-Absorption-Efficiency Superlattice Solar Cells by Excitons

    NASA Astrophysics Data System (ADS)

    Nishinaga, Jiro; Kawaharazuka, Atsushi; Onomitsu, Koji; Horikoshi, Yoshiji

    2013-11-01

    The effect of excitonic absorption on solar cell efficiency has been investigated using solar cells with AlGaAs/GaAs superlattice structures. Numerical calculations reveal that excitonic absorption considerably enhances the overall absorption of bulk GaAs. Excitonic absorption shows strong and sharp peaks at the absorption edge and in the energy region above the band gap. Absorption enhancement is also achieved in the AlGaAs/GaAs superlattice. The measured quantum efficiency spectra of the superlattice solar cells are quite similar to the calculated absorption spectra considering the excitonic effect. The superlattice solar cells are confirmed to have high absorption coefficient compared with the GaAs and AlGaAs bulk solar cells. These results suggest that the enhanced absorption by excitons can increase the quantum efficiency of solar cells. This effect is more prominent for the solar cells with small absorption layer thicknesses.

  18. Simple spectrophotometry method for the determination of sulfur dioxide in an alcohol-thionyl chloride reaction.

    PubMed

    Zheng, Jinjian; Tan, Feng; Hartman, Robert

    2015-09-03

    Thionyl chloride is often used to convert alcohols into more reactive alkyl chloride, which can be easily converted to many compounds that are not possible from alcohols directly. One important reaction of alkyl chloride is nucleophilic substitution, which is typically conducted under basic conditions. Sulfur dioxide, the by-product from alcohol-thionyl chloride reactions, often reacts with alkyl chloride to form a sulfonyl acid impurity, resulting in yield loss. Therefore, the alkyl chloride is typically isolated to remove the by-products including sulfur dioxide. However, in our laboratory, the alkyl chloride formed from alcohol and thionyl chloride was found to be a potential mutagenic impurity, and isolation of this compound would require extensive safety measures. As a result, a flow-through process was developed, and the sulfur dioxide was purged using a combination of vacuum degassing and nitrogen gas sweeping. An analytical method that can quickly and accurately quantitate residual levels of sulfur dioxide in the reaction mixture is desired for in-process monitoring. We report here a simple ultraviolet (UV) spectrophotometry method for this measurement. This method takes advantage of the dramatic change in the UV absorbance of sulfur dioxide with respect to pH, which allows for accurate quantitation of sulfur dioxide in the presence of the strong UV-absorbing matrix. Each sample solution was prepared using 2 different diluents: 1) 50 mM ammonium acetate in methanol +1% v/v hydrochloric acid, pH 1.3, and 2) 50 mM ammonium acetate in methanol +1% glacial acetic acid, pH 4.0. The buffer solutions were carefully selected so that the UV absorbance of the sample matrix (excluding sulfur dioxide) at 276 nm remains constant. In the pH 1.3 buffer system, sulfur dioxide shows strong UV absorbance at 276 nm. Therefore, the UV absorbance of sample solution is the sum of sulfur dioxide and sample matrix. While in the pH 4.0 buffer system, sulfur dioxide has

  19. [A specific feature of the procedure for determination of optical properties of turbid biological tissues and media in calculation tasks of medical noninvasive spectrophotometry].

    PubMed

    Rogatkin, D A

    2007-01-01

    The goal of this work is to discuss the problems of accuracy and reliability of the procedure for determination of optical per-unit-length properties of light-scattering biological tissues and media in medical noninvasive spectrophotometry. The determination procedure is based on the two-flux Kubelka-Munk approach. A simple one-dimensional model problem is formulated. The accurate solution of this problem is compared to its solution based on the Kubelka-Munk approach in various approximations. It is shown that in the general case of light-scattering and absorbing medium use of two independent transport coefficients (for scattering and absorption processes), as suggested in the conventional Kubelka-Munk approach, leads to errors of direct calculation of properties of backscattered and transmitted radiation in biological tissues. More valid and accurate expressions for transport coefficients can be obtained on the basis of a particular solution of the problem for a surface element of the model medium with known photometrical properties. This method makes it possible to determine accurately the radiation flux at the external boundary of the medium using the Kubelka-Munk approach. It is expected that solution of the inverse problem would make it possible to reconstruct accurately the optical properties of biological tissues from the experimental data.

  20. Simple and fast method for iron determination in white and red wines using dispersive liquid-liquid microextraction and ultraviolet-visible spectrophotometry.

    PubMed

    Maciel, Juliana V; Soares, Bruno M; Mandlate, Jaime S; Picoloto, Rochele S; Bizzi, Cezar A; Flores, Erico M M; Duarte, Fabio A

    2014-08-20

    This work reports the development of a method for Fe extraction in white and red wines using dispersive liquid-liquid microextraction (DLLME) and determination by ultraviolet-visible spectrophotometry. For optimization of the DLLME method, the following parameters were evaluated: type and volume of dispersive (1300 μL of acetonitrile) and extraction (80 μL of C(2)Cl(4)) solvents, pH (3.0), concentration of ammonium pyrrolidinedithiocarbamate (APDC, 500 μL of 1% m/v APDC solution), NaCl concentration (not added), and extraction time. The calibration curve was performed using the analyte addition method, and the limit of detection and relative standard deviation were 0.2 mg L(-1) and below 7%, respectively. The accuracy was evaluated by comparison of results obtained after Fe determination by graphite furnace atomic absorption spectrometry, with agreement ranging from 94 to 105%. The proposed method was applied for Fe determination in white and red wines with concentrations ranging from 1.3 to 4.7 mg L(-1).

  1. Speciation of selenium in environmental samples by solid-phase spectrophotometry using 2,3-dichloro-6-(2,7-dihydroxy-naphthylazo)quinoxaline.

    PubMed

    Amin, Alaa S

    2014-01-01

    Solid-phase spectrophotometry was applied to determination of trace amounts of selenium (Se) in water, soil, plant materials, human hair, and a cosmetic preparation (lipstick). Se(IV) was sorbed in a dextran type lipophilic gel as a complex with 2,3-dichloro-6-(2,7-dihydroxy-naphthylazo)quinoxaline (DCDHNAQ), whereas Se(VI) was determined after boiling in HCI for 10 min to convert Se(VI) to Se(IV). Resin phase absorbances at 588 and 800 nm were measured directly, which allowed the determination of Se in the range of 0.2-3.3 microg/L with an RSD of 1.22%. The influences of analytical parameters including pH of the aqueous solution, amounts of DCDHNAQ, and sample volume were investigated. The molar absorptivities were found to be 1.09 x 10(6), 4.60 x 10(6), and 1.23 x 10(7) L/mol cm for 100, 500, and 1000 mL, respectively. The LOD and LOQ of the 500 mL sample method were 110 and 360 ng/L, respectively, when using 50 mg dextran type lipophilic gel. For a 1000 mL sample, the LOD and LOQ were 60 and 200 ng/L, respectively, using 50 mg of the exchanger. Increasing the sample volume enhanced the sensitivity. No considerable interferences were observed from other investigated anions and cations on the Se determination.

  2. Complex Refractive Index Spectra of CH3NH3PbI3 Perovskite Thin Films Determined by Spectroscopic Ellipsometry and Spectrophotometry.

    PubMed

    Löper, Philipp; Stuckelberger, Michael; Niesen, Bjoern; Werner, Jérémie; Filipič, Miha; Moon, Soo-Jin; Yum, Jun-Ho; Topič, Marko; De Wolf, Stefaan; Ballif, Christophe

    2015-01-02

    The complex refractive index (dielectric function) of planar CH3NH3PbI3 thin films at room temperature is investigated by variable angle spectroscopic ellipsometry and spectrophotometry. Knowledge of the complex refractive index is essential for designing photonic devices based on CH3NH3PbI3 thin films such as solar cells, light-emitting diodes, or lasers. Because the directly measured quantities (reflectance, transmittance, and ellipsometric spectra) are inherently affected by multiple reflections, the complex refractive index has to be determined indirectly by fitting a model dielectric function to the experimental spectra. We model the dielectric function according to the Forouhi-Bloomer formulation with oscillators positioned at 1.597, 2.418, and 3.392 eV and achieve excellent agreement with the experimental spectra. Our results agree well with previously reported data of the absorption coefficient and are consistent with Kramers-Kronig transformations. The real part of the refractive index assumes a value of 2.611 at 633 nm, implying that CH3NH3PbI3-based solar cells are ideally suited for the top cell in monolithic silicon-based tandem solar cells.

  3. UV Spectrophotometry of the Hottest Stars from the Southern HK Survey

    NASA Astrophysics Data System (ADS)

    Drilling, John S.; Beers, Timothy C.

    1995-06-01

    Low-resolution UV spectra have been obtained with the long- and short-wavelength lUE cameras for seven of the hottest stars identified in the ongoing HK objective-prism/interference-filter survey begun by Beers, Preston, & Shectman. These stars are a subset of a sample of some 25,000 stars at high galactic latitude whose objective-prism spectra indicate that they are hotter than the Population II main-sequence turnoff in the magnitude range 11 ≤ B ≤ 15.5. The UV fluxes have been corrected for interstellar reddening using a standard reddening law, and comparison of the integrated fluxes in the two lUE cameras indicates that the effective temperatures of these stars range from 40,000 K to 80,000 K. The UV absorption spectra of six of the seven stars are characterized by a strong He II λ1640 line and 3-n series of He II. Five of these stars show strong C IV λ1550 absorption. The low-resolution UV spectrum of the remaining object is featureless.

  4. Solar absorption surface panel

    DOEpatents

    Santala, Teuvo J.

    1978-01-01

    A composite metal of aluminum and nickel is used to form an economical solar absorption surface for a collector plate wherein an intermetallic compound of the aluminum and nickel provides a surface morphology with high absorptance and relatively low infrared emittance along with good durability.

  5. Rectal absorption of propylthiouracil.

    PubMed

    Bartle, W R; Walker, S E; Silverberg, J D

    1988-06-01

    The rectal absorption of propylthiouracil (PTU) was studied and compared to oral absorption in normal volunteers. Plasma levels of PTU after administration of suppositories of PTU base and PTU diethanolamine were significantly lower compared to the oral route. Elevated plasma reverse T3 levels were demonstrated after each treatment, however, suggesting a desirable therapeutic effect at this dosage level for all preparations.

  6. Determination of losartan potassium, quinapril hydrochloride and hydrochlorothiazide in pharmaceutical preparations using derivative spectrophotometry and chromatographic-densitometric method.

    PubMed

    Stolarczyk, Mariusz; Maślanka, Anna; Apola, Anna; Krzek, Jan

    2013-01-01

    Two methods, spectrophotometric and chromatographic-densitometric ones, were developed for determination of losartan potassium, quinapril hydrochloride and hydrochlorothiazide in pharmaceutical preparations. Spectrophotometric method involved derivative spectrophotometry and zero order spectrophotometry. The measurements were carried out at lambda = 224.0 nm for quinapril, lambda = 261.0 nm for hydrochlorothiazide and lambda = 270.0 nm for losartan when the derivative spectrophotometry was applied and lambda = 317.0 nm when zero order spectrophotometry was applied for the determination of hydrochlorothiazide. In chromatographic-densitometric studies high performance thin layer chromatography (HPTLC) plates were used as stationary phase and a mixture of solvents n-butanol : acetic acid : water (15 : 5 : 1, v/v/v) as mobile phase. Under the established conditions good resolution of examined constituents was obtained. Retardation factor for quinapril hydrochloride was R(f) - 0.70, for losartan potassium R(f) - 0.85 and for hydrochlorothiazide R(f) - 0.78. The developed methods are characterized by high sensitivity and accuracy. For quantitative analysis, densitometric measurements were carried out at lambda = 218.0 nm for quinapril, lambda = 275.0 nm for hydrochlorothiazide and = 232.0 nm for losartan.

  7. Theory of graphene saturable absorption

    NASA Astrophysics Data System (ADS)

    Marini, A.; Cox, J. D.; García de Abajo, F. J.

    2017-03-01

    Saturable absorption is a nonperturbative nonlinear optical phenomenon that plays a pivotal role in the generation of ultrafast light pulses. Here we show that this effect emerges in graphene at unprecedentedly low light intensities, thus opening avenues to new nonlinear physics and applications in optical technology. Specifically, we theoretically investigate saturable absorption in extended graphene by developing a semianalytical nonperturbative single-particle approach, describing electron dynamics in the atomically-thin material using the two-dimensional Dirac equation for massless Dirac fermions, which is recast in the form of generalized Bloch equations. By solving the electron dynamics nonperturbatively, we account for both interband and intraband contributions to the intensity-dependent saturated conductivity and conclude that the former dominates regardless of the intrinsic doping state of the material. We obtain results in qualitative agreement with atomistic quantum-mechanical simulations of graphene nanoribbons including electron-electron interactions, finite-size, and higher-band effects. Remarkably, such effects are found to affect mainly the linear absorption, while the predicted saturation intensities are in good quantitative agreement in the limit of extended graphene. Additionally, we find that the modulation depth of saturable absorption in graphene can be electrically manipulated through an externally applied gate voltage. Our results are relevant for the development of graphene-based optoelectronic devices, as well as for applications in mode-locking and random lasers.

  8. Slow light and saturable absorption

    NASA Astrophysics Data System (ADS)

    Selden, A. C.

    2009-06-01

    Quantitative analysis of slow light experiments utilising coherent population oscillation (CPO) in a range of saturably absorbing media, including ruby and alexandrite, Er3+:Y2SiO5, bacteriorhodopsin, semiconductor quantum devices and erbium-doped optical fibres, shows that the observations may be more simply interpreted as saturable absorption phenomena. A basic two-level model of a saturable absorber displays all the effects normally associated with slow light, namely phase shift and modulation gain of the transmitted signal, hole burning in the modulation frequency spectrum and power broadening of the spectral hole, each arising from the finite response time of the non-linear absorption. Only where hole-burning in the optical spectrum is observed (using independent pump and probe beams), or pulse delays exceeding the limits set by saturable absorption are obtained, can reasonable confidence be placed in the observation of slow light in such experiments. Superluminal (“fast light”) phenomena in media with reverse saturable absorption (RSA) may be similarly explained.

  9. Quasar Absorption Studies

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard (Technical Monitor); Elvis, Martin

    2004-01-01

    The aim of the proposal is to investigate the absorption properties of a sample of inter-mediate redshift quasars. The main goals of the project are: Measure the redshift and the column density of the X-ray absorbers; test the correlation between absorption and redshift suggested by ROSAT and ASCA data; constrain the absorber ionization status and metallicity; constrain the absorber dust content and composition through the comparison between the amount of X-ray absorption and optical dust extinction. Unanticipated low energy cut-offs where discovered in ROSAT spectra of quasars and confirmed by ASCA, BeppoSAX and Chandra. In most cases it was not possible to constrain adequately the redshift of the absorber from the X-ray data alone. Two possibilities remain open: a) absorption at the quasar redshift; and b) intervening absorption. The evidences in favour of intrinsic absorption are all indirect. Sensitive XMM observations can discriminate between these different scenarios. If the absorption is at the quasar redshift we can study whether the quasar environment evolves with the Cosmic time.

  10. Catalog of far-ultraviolet objective-prism spectrophotometry: Skylab experiment S-019, ultraviolet steller astronomy

    NASA Technical Reports Server (NTRS)

    Henize, K. G.; Wray, J. D.; Parsons, S. B.; Benedict, G. F.

    1979-01-01

    Ultraviolet stellar spectra in the wavelength region from 1300 to 5000 A (130 to 500) were photographed during the three manned Skylab missions using a 15 cm aperture objective-prism telescope. The prismatic dispersion varied from 58 A mm/1 at 1400 A to 1600 A mm/1 at 3000 A. Approximately 1000 spectra representing 500 stars were measured and reduced to observed fluxes. About 100 stars show absorption lines of Si IV, C IV, or C II. Numerous line features are also recorded in supergiant stars, shell stars, A and F stars, and Wolf-Rayet stars. Most of the stars in the catalog are of spectral class B, with a number of O and A type stars and a sampling of WC, WN, F and C type stars. Spectrophotometric results are tabulated for these 500 stars.

  11. Spectrophotometry of Wolf-Rayet stars - Intrinsic colors and absolute magnitudes

    NASA Technical Reports Server (NTRS)

    Torres-Dodgen, Ana V.; Massey, Philip

    1988-01-01

    Absolute spectrophotometry of about 10-A resolution in the range 3400-7300 A have been obtained for southern Wolf-Rayet stars, and line-free magnitudes and colors have been constructed. The emission-line contamination in the narrow-band ubvr systems of Westerlund (1966) and Smith (1968) is shown to be small for most WN stars, but to be quite significant for WC stars. It is suggested that the more severe differences in intrinsic color from star to star of the same spectral subtype noted at shorter wavelengths are due to differences in atmospheric extent. True continuum absolute visual magnitudes and intrinsic colors are obtained for the LMC WR stars. The most visually luminous WN6-WN7 stars are found to be located in the core of the 30 Doradus region.

  12. Far-ultraviolet and optical spectrophotometry of X-ray selected Seyfert galaxies

    NASA Technical Reports Server (NTRS)

    Clarke, J. T.; Bowyer, S.; Grewing, M.

    1986-01-01

    Five X-ray selected Seyfert galaxies were examined via near-simultaneous far-ultraviolet and optical spectrophotometry in an effort to test models for excitation of emission lines by X-ray and ultraviolet continuum photoionization. The observed Ly-alpha/H-beta ratio in the present sample averages 22, with an increase found toward the high-velocity wings of the H lines in the spectrum of at least one of the Seyfert I nuclei. It is suggested that Seyfert galaxies with the most high-velocity gas exhibit the highest Ly-alpha/H-beta ratios at all velocities in the line profiles, and that sometimes this ratio may be highest for the highest velocity material in the broad-line clouds. Since broad-lined objects are least affected by Ly-alpha trapping effects, they have Ly-alpha/H-beta ratios much closer to those predicted by early photoionization calculations.

  13. Ultraviolet spectrophotometry of comet Giacobini-Zinner during the ICE encounter. [International Cometary Explorer (ICE)

    NASA Technical Reports Server (NTRS)

    Ahearn, Michael F.; Mcfadden, Lucy A.; Feldman, Paul D.; Boehnhardt, Hermann; Rahe, Juergen; Festou, Michael; Brandt, John C.; Maran, Stephen P.; Niedner, Malcom B.; Smith, Andrew M.

    1986-01-01

    The IUE spectrophotometry of Comet P/Giacobini-Zinner was acquired in support of the International Cometary Explorer (ICE) mission. The abundances (or upper limits) of UV-active species were calculated. During the ICE encounter the H2O production rate was 3 times 10 to the 28th power/sec, + or - 50%, consistent with values derived from the ICE experiments. Comparison of the abundance of CO2(+) ions with the total electron density measured by the plasma electron experiment on ICE indicates a deficiency of ions relative to electrons indicating a population of ions not detected by remote sensing. The absence of detectable Mg(+) rules out this species as a possible ion of M/Q = 24 detected by the Ion Composition Instrument, part of the ICE complement of instruments.

  14. Antioxidant study of quercetin and their metal complex and determination of stability constant by spectrophotometry method.

    PubMed

    Ravichandran, R; Rajendran, M; Devapiriam, D

    2014-03-01

    Quercetin found chelate cadmium ions, scavenge free radicals produced by cadmium. Hence new complex, quercetin with cadmium was synthesised, and the synthesised complex structures were determined by UV-vis spectrophotometry, infrared spectroscopy, thermogravimetry and differential thermal analysis techniques (UV-vis, IR, TGA and DTA). The equilibrium stability constants of quercetin-cadmium complex were determined by Job's method. The determined stability constant value of quercetin-cadminum complex at pH 4.4 is 2.27×10(6) and at pH 7.4 is 7.80×10(6). It was found that the quercetin and cadmium ion form 1:1 complex in both pH 4.4 and pH 7.4. The structure of the compounds was elucidated on the basis of obtained results. Furthermore, the antioxidant activity of the free quercetin and quercetin-cadmium complexes were determined by DPPH and ABTS assays.

  15. Heterodyne spectrophotometry of ozone in the 9.6-micron band using a tunable diode laser

    NASA Technical Reports Server (NTRS)

    Mcelroy, C. T.; Goldman, A.; Fogal, P. F.; Murcray, D. G.

    1990-01-01

    Tunable diode laser heterodyne spectrophotometry (TDLHS) has been used to make extremely high resolution (0.0003/cm) solar spectra in the 9.6-micron ozone band. Observations have shown that a signal-to-noise ratio of 120:1 (about 30 percent of theoretical) for an integration time of 1/8 s can be achieved at a resolution of 0.0013 wave numbers. The spectral data have been inverted to yield a total column amount of ozone, in good agreement with that measured at the nearby NOAA ozone monitoring facility in Boulder, Colorado. Line positions for several ozone lines in the spectral region 996-997/cm are reported. Recent improvements have produced a signal-to-noise ratio of 95:1 (about 40 percent of theoretical) at 0.0003/cm and extended the range of wavelengths which can be observed.

  16. Airborne and groundbased spectrophotometry of comet P/Halley from 5-13 micrometers

    NASA Technical Reports Server (NTRS)

    Bregman, J. D.; Witteborn, F. C.; Allamandola, L. J.; Campins, H.; Wooden, D. H.; Rank, D. M.; Cohen, M.; Tielens, A. G. G. M.

    1987-01-01

    Spectrophotometry of comet Halley from 5-13 microns was obtained from the Kuiper Airborne Observatory and from the Lick Observatory Nickel Telescope, revealing a strong broad emission band at 10 microns and a weak feature at 6.8 microns. The 10-micron band is identified with silicate materials, and the primary component of the silicate emission is suggested to be due to olivine. The 6.8 micron feature may be due either to carbonates or the C-H deformation mode in organic molecules. The data indicate that small particles are abundant in the coma and that the dust contains at least two physically separate components. Significant spatial and temporal variations are also noted in the spectrum.

  17. A high-throughput screening strategy for nitrile-hydrolyzing enzymes based on ferric hydroxamate spectrophotometry.

    PubMed

    He, Yu-Cai; Ma, Cui-Luan; Xu, Jian-He; Zhou, Li

    2011-02-01

    Nitrile-hydrolyzing enzymes (nitrilase or nitrile hydratase/amidase) have been widely used in the pharmaceutical industry for the production of carboxylic acids and their derivatives, and it is important to build a method for screening for nitrile-hydrolyzing enzymes. In this paper, a simple, rapid, and high-throughput screening method based on the ferric hydroxamate spectrophotometry has been proposed. To validate the accuracy of this screening strategy, the nitrilases from Rhodococcus erythropolis CGMCC 1.2362 and Alcaligenes sp. ECU0401 were used for evaluating the method. As a result, the accuracy for assaying aliphatic and aromatic carboxylic acids was as high as the HPLC-based method. Therefore, the method may be potentially used in the selection of microorganisms or engineered proteins with nitrile-hydrolyzing enzymes.

  18. Near-infrared spectrophotometry of the satellites and rings of Uranus

    NASA Astrophysics Data System (ADS)

    Soifer, B. T.; Neugebauer, G.; Matthews, K.

    1981-03-01

    New spectrophotometry from 1.5 to 2.5 microns is reported for the Uranian satellites Titania, Oberon, and Umbriel. A spectrum of the rings of Uranus from 2.0 to 2.4 microns is also reported. No evidence is found for frost covering the surface of the ring material, consistent with the low albedo of the rings previously reported by Nicholson and Jones (1980). The surfaces of the satellites are found to be covered by dirty water frost. Assuming albedos of the frost and gray components covering the Uranian satellites to be the same as the light and dark faces of Iapetus, radii are derived that are roughly twice those inferred from the assumption of a visual albedo of 0.5.

  19. Near-infrared spectrophotometry of the satellites and rings of Uranus

    NASA Technical Reports Server (NTRS)

    Soifer, B. T.; Neugebauer, G.; Matthews, K.

    1981-01-01

    New spectrophotometry from 1.5 to 2.5 microns is reported for the Uranian satellites Titania, Oberon, and Umbriel. A spectrum of the rings of Uranus from 2.0 to 2.4 microns is also reported. No evidence is found for frost covering the surface of the ring material, consistent with the low albedo of the rings previously reported by Nicholson and Jones (1980). The surfaces of the satellites are found to be covered by dirty water frost. Assuming albedos of the frost and gray components covering the Uranian satellites to be the same as the light and dark faces of Iapetus, radii are derived that are roughly twice those inferred from the assumption of a visual albedo of 0.5.

  20. Spectrophotometry of Twenty of the Brightest Stars in the Southern Sky

    NASA Astrophysics Data System (ADS)

    Krisciunas, Kevin; Suntzeff, Nicholas B.; Kelarek, Bethany; Bonar, Kyle; Stenzel, Joshua

    2017-01-01

    We have obtained spectra of 20 bright southern stars (including Sirius, Canopus, Betelgeuse, Rigel, and Procyon) using the CTIO 1.5-m telescope and its grating spectrograph RCSPEC. The brightness of the targets required the use of a 7.5 magnitude neutral density filter. Given a Kurucz model spectrum of Sirius (t = 9850 K, log g = 4.30, [Fe/H] = +0.4) with an appropriate spectral resolution, we can place the spectrophotometry on the system of Sirius, which is much less problematic than basing the ultimate calibration on Vega. The resulting B- and V-band synthetic photometry compares well with that of Cousins, with minimal color terms. Our synthetic R- and I-band photometry indicates non-zero offsets and color-terms with respect to Cousins' data.

  1. Spatially Multiplexed Micro-Spectrophotometry in Bright Field Mode for Thin Film Characterization

    PubMed Central

    Pini, Valerio; Kosaka, Priscila M.; Ruz, Jose J.; Malvar, Oscar; Encinar, Mario; Tamayo, Javier; Calleja, Montserrat

    2016-01-01

    Thickness characterization of thin films is of primary importance in a variety of nanotechnology applications, either in the semiconductor industry, quality control in nanofabrication processes or engineering of nanoelectromechanical systems (NEMS) because small thickness variability can strongly compromise the device performance. Here, we present an alternative optical method in bright field mode called Spatially Multiplexed Micro-Spectrophotometry that allows rapid and non-destructive characterization of thin films over areas of mm2 and with 1 μm of lateral resolution. We demonstrate an accuracy of 0.1% in the thickness characterization through measurements performed on four microcantilevers that expand an area of 1.8 mm2 in one minute of analysis time. The measured thickness variation in the range of few tens of nm translates into a mechanical variability that produces an error of up to 2% in the response of the studied devices when they are used to measure surface stress variations. PMID:27338398

  2. Infrared photometry and spectrophotometry of G75.84+0.4

    NASA Technical Reports Server (NTRS)

    Pipher, J. L.; Soifer, B. T.; Krassner, J.

    1979-01-01

    Photometric mapping of G75.84+0.4 at 12.6 microns is compared with previously published radio maps of the region to deduce the relative dust/gas mass ratio for the dust responsible for the 12.6-micron emission. Spectrophotometry from 2-4 microns and 8-13 microns of the highest-emission-measure region reveals the presence of the fine structure lines of forbidden Ar III at 8.99 microns, forbidden Ne II at 12.78 microns, and forbidden S IV at 10.53 microns. Estimates of the abundance of these ions are made, and the nature of the exciting source is discussed.

  3. Can the Assessment of Spontaneous Oscillations by Near Infrared Spectrophotometry Predict Neurological Outcome of Preterm Infants?

    PubMed

    Stammwitz, André; von Siebenthal, Kurt; Bucher, Hans U; Wolf, Martin

    2016-01-01

    The aim was to assess the correlation between cerebral autoregulation and outcome. Included were 31 preterm infants, gestational age 26 1/7 to 32 2/7 and <24 h life. Coherence between cerebral total haemoglobin (tHb) or oxygenation index (OI) measured by near-infrared spectrophotometry (NIRS) and systemic heart rate (HR) or arterial blood pressure (MAP) was calculated as a measure of autoregulation. In contrast to previous studies, low coherences in the first 24 h were significantly associated with intraventricular haemorrhage, death or abnormal neurodevelopmental outcome at 18 months or later. We suggest that our results can be explained by the concept of a multi-oscillatory-functions-order.

  4. Near-infrared spectrophotometry of four Seyfert 1 galaxies and NGC 1275

    NASA Technical Reports Server (NTRS)

    Rudy, R. J.; Jones, B.; Levan, P. D.; Puetter, R. C.; Smith, H. E.; Willner, S. P.; Tokunaga, A. T.

    1982-01-01

    Low-resolution spectrophotometry from 2 to 4 microns is reported for the four Seyfert 1 galaxies Mrk 335, 3C 120, Mrk 509, NGC 7469, and the peculiar emission-line galaxy NGC 1275. The spectrum of NGC 7469 exhibits a strong 3.3-micron dust feature, indicating a thermal origin for the bulk of its considerable nonstellar infrared emission. NGC 1275 has a large stellar contribution to its infrared flux at wavelengths shortward of 3 microns. The spectrum from 3 to 4 microns fits a power law which fits the 10-micron and 20-micron broad bands, as well. A thermal model which can explain the spectrum of NGC 1275 is discussed. Mrk 335 displays a complex spectrum suggestive of thermal dust emission. 3C 120 and Mrk 509 have nonstellar infrared emission shortward of 2 microns, but the data are ambiguous as to whether this emission is thermal or nonthermal in origin.

  5. Direct determination of total serum cholesterol by use of double-wavelength spectrophotometry.

    PubMed

    Sommers, P B; Jatlow, P I; Seligson, D

    1975-05-01

    We describe a simple, accurate method for direct determination of total cholesterol in serum. Systematic investigation of a previously described modified Liebermann-Burchard reagent has indicated the necessity of accounting for both bilirubin interference and decreased specificity owing to exothermia. Double-wavelength spectrophotometry was used to optically null out bilirubin as an interfering factor, whereas adding serum to the cold reagent increases its specificity for the cholesterol color reaction. Comparison of 106 cholesterol values with those obtained by the procedure of Abell et al. [J. Biol. Chem. 195, 357 (1952)] yielded a correlation coefficient greater than 0.99; our inter-run coefficient of variation of polled laboratory serum was 1.7%.

  6. Do GSM 900MHz signals affect cerebral blood circulation? A near-infrared spectrophotometry study

    NASA Astrophysics Data System (ADS)

    Wolf, Martin; Haensse, Daniel; Morren, Geert; Froehlich, Juerg

    2006-06-01

    Effects of GSM 900MHz signals (EMF) typical for a handheld mobile phone on the cerebral blood circulation were investigated using near-infrared spectrophotometry (NIRS) in a three armed (12W/kg, 1.2W/kg, sham), double blind, randomized crossover trial in 16 healthy volunteers. During exposure we observed borderline significant short term responses of oxyhemoglobin and deoxyhemoglobin concentration, which correspond to a decrease of cerebral blood flow and volume and were smaller than regular physiological changes. Due to the relatively high number of statistical tests, these responses may be spurious and require further studies. There was no detectable dose-response relation or long term response within 20min. The detection limit was a fraction of the regular physiological changes elicited by functional activation. Compared to previous studies using PET, NIRS provides a much higher time resolution, which allowed investigating the short term effects efficiently, noninvasively, without the use of radioactive tracers and with high sensitivity.

  7. Determination of total arsenic content in water by atomic absorption spectroscopy (AAS) using vapour generation assembly (VGA).

    PubMed

    Behari, Jai Raj; Prakash, Rajiv

    2006-03-01

    Analysis of arsenic in water is important in view of contamination of ground water with arsenic in some parts of the world including West Bengal in India and neighboring country Bangladesh. WHO has fixed the threshold for arsenic in drinking water to 10ppb (microg/l) level, hence the methodology for determination of arsenic is required to be sensitive at ppb level. Atomic absorption spectrophotometry with vapour generation assembly (AAS-VGA) is well known technique for the trace analysis of arsenic. However, total arsenic analysis [As(III)+As(V)] is very crucial and it requires reduction of As(V) to As(III) for correct analysis. As(III) is reduced to AsH3 vapours and finally to free As atoms, which are responsible for absorption signal in AAS. To accomplish this the vapour generation assembly attached to AAS has acid channel filled with 10 M HCl and the reduction channel with sodium borohydride. Further sample can be reduced either before aspiration for analysis, using potassium iodide (KI) or the sample can be introduced in the instrument directly and KI can be added in the reduction channel along with the sodium borohydride. The present work shows that samples prepared in 3 M HCl can be reduced with KI for 30 min before introduction in the instrument. Alternatively samples can be prepared in 6 M HCl and directly aspirated in AAS using KI in VGA reduction channel. The latter methodology is more useful when the sample size is large and time cycle is difficult to maintain. It is observed that the acid concentration of the sample in both the situations plays an important role. Further reduction in acid concentration and analysis time is achieved for the arsenic analysis by using modified method. Analysis in both the methods is sensitive at ppb level.

  8. 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).

  9. Comparison of direct (X-ray diffraction and infrared spectrophotometry) and indirect (infrared spectrophotometry) methods for the analysis of alpha-quartz in airborne dusts.

    PubMed

    Kauffer, E; Masson, A; Moulut, J C; Lecaque, T; Protois, J C

    2005-11-01

    In this study, the alpha-quartz contents measured by different analytical techniques (X-ray diffraction, direct method; and infrared spectrophotometry, direct and indirect methods) were compared. The analyses were carried out on filters sampled in an industrial setting by means of a Dorr-Oliver cyclone. To verify the methodology used, filters loaded with pure alpha-quartz were also analysed. By and large, the agreement between the two direct methods was close on average, but on the basis of a comparison of the individual results, considerable differences exist. In absolute value, the mean relative deviation between the two techniques was <25% in only 47.8% of the cases. The results obtained by the indirect method (infrared) were on average 13% lower than the results obtained by the two direct methods with a more important difference (23%) for samples where calcite was identified by X-ray diffraction in comparison with those where it was not (8%). This underestimation, which was not owing to dust losses during preparation, is probably explained by the elimination of organic compounds during dust calcinations or by the transformation of mineral compounds. The indirect method introduces additional sample handling operations with more risk of material loss. When the quantity of calcined material was <0.4 mg, the weighing operations necessary to correct any losses of material resulted in considerable variability. In terms of overall uncertainty, it would be better in this case not to carry out correction and to employ an operating mode favouring the recovery of a maximum of material while accepting a bias of about 5-7%.

  10. Absorption of Solar Radiation by Clouds: Observations Versus Models

    NASA Technical Reports Server (NTRS)

    Cess, R. D.; Zhang, M. H.; Minnis, P.; Corsetti, L.; Dutton, E. G.; Forgan, B. W.; Garber, D. P.; Gates, W. L.; Hack, J. J.; Harrison, E. F.; Jing, X.; Kiehl, J. T.; Long, C. N.; Morcrette, J.-J.; Potter, G. L.; Ramanathan, V.; Subasilar, B.; Whitlock, C. H.; Young, D. F.; Zhou, Y.

    1995-01-01

    There has been a long history of unexplained anomalous absorption of solar radiation by clouds. Collocated satellite and surface measurements of solar radiation at five geographically diverse locations showed significant solar absorption by clouds, resulting in about 25 watts per square meter more global-mean absorption by the cloudy atmosphere than predicted by theoretical models. It has often been suggested that tropospheric aerosols could increase cloud absorption. But these aerosols are temporally and spatially heterogeneous, whereas the observed cloud absorption is remarkably invariant with respect to season and location. Although its physical cause is unknown, enhanced cloud absorption substantially alters our understanding of the atmosphere's energy budget.

  11. Absorption imaging of a single atom

    NASA Astrophysics Data System (ADS)

    Streed, Erik W.; Jechow, Andreas; Norton, Benjamin G.; Kielpinski, David

    2012-07-01

    Absorption imaging has played a key role in the advancement of science from van Leeuwenhoek's discovery of red blood cells to modern observations of dust clouds in stellar nebulas and Bose-Einstein condensates. Here we show the first absorption imaging of a single atom isolated in a vacuum. The optical properties of atoms are thoroughly understood, so a single atom is an ideal system for testing the limits of absorption imaging. A single atomic ion was confined in an RF Paul trap and the absorption imaged at near wavelength resolution with a phase Fresnel lens. The observed image contrast of 3.1 (3)% is the maximum theoretically allowed for the imaging resolution of our set-up. The absorption of photons by single atoms is of immediate interest for quantum information processing. Our results also point out new opportunities in imaging of light-sensitive samples both in the optical and X-ray regimes.

  12. Absorption imaging of a single atom.

    PubMed

    Streed, Erik W; Jechow, Andreas; Norton, Benjamin G; Kielpinski, David

    2012-07-03

    Absorption imaging has played a key role in the advancement of science from van Leeuwenhoek's discovery of red blood cells to modern observations of dust clouds in stellar nebulas and Bose-Einstein condensates. Here we show the first absorption imaging of a single atom isolated in a vacuum. The optical properties of atoms are thoroughly understood, so a single atom is an ideal system for testing the limits of absorption imaging. A single atomic ion was confined in an RF Paul trap and the absorption imaged at near wavelength resolution with a phase Fresnel lens. The observed image contrast of 3.1 (3)% is the maximum theoretically allowed for the imaging resolution of our set-up. The absorption of photons by single atoms is of immediate interest for quantum information processing. Our results also point out new opportunities in imaging of light-sensitive samples both in the optical and X-ray regimes.

  13. Creating semiconductor metafilms with designer absorption spectra

    PubMed Central

    Kim, Soo Jin; Fan, Pengyu; Kang, Ju-Hyung; Brongersma, Mark L.

    2015-01-01

    The optical properties of semiconductors are typically considered intrinsic and fixed. Here we leverage the rapid developments in the field of optical metamaterials to create ultrathin semiconductor metafilms with designer absorption spectra. We show how such metafilms can be constructed by placing one or more types of high-index semiconductor antennas into a dense array with subwavelength spacings. It is argued that the large absorption cross-section of semiconductor antennas and their weak near-field coupling open a unique opportunity to create strongly absorbing metafilms whose spectral absorption properties directly reflect those of the individual antennas. Using experiments and simulations, we demonstrate that near-unity absorption at one or more target wavelengths of interest can be achieved in a sub-50-nm-thick metafilm using judiciously sized and spaced Ge nanobeams. The ability to create semiconductor metafilms with custom absorption spectra opens up new design strategies for planar optoelectronic devices and solar cells. PMID:26184335

  14. Novel absorption detection techniques for capillary electrophoresis

    SciTech Connect

    Xue, Yongjun

    1994-07-27

    Capillary electrophoresis (CE) has emerged as one of the most versatile separation methods. However, efficient separation is not sufficient unless coupled to adequate detection. The narrow inner diameter (I.D.) of the capillary column raises a big challenge to detection methods. For UV-vis absorption detection, the concentration sensitivity is only at the μM level. Most commercial CE instruments are equipped with incoherent UV-vis lamps. Low-brightness, instability and inefficient coupling of the light source with the capillary limit the further improvement of UV-vis absorption detection in CE. The goals of this research have been to show the utility of laser-based absorption detection. The approaches involve: on-column double-beam laser absorption detection and its application to the detection of small ions and proteins, and absorption detection with the bubble-shaped flow cell.

  15. Solid methane on Triton and Pluto - 3- to 4-micron spectrophotometry

    NASA Technical Reports Server (NTRS)

    Spencer, John R.; Buie, Marc W.; Bjoraker, Gordon L.

    1990-01-01

    Methane has been identified in the Pluto/Charon system on the basis of absorption features in the reflectance spectrum at 1.5 and 2.3 microns; attention is presently given to observations of a 3.25 micron-centered deep absorption feature in Triton and Pluto/Charon system reflectance spectra. This absorption may indicate the presence of solid methane, constituting either the dominant surface species or a mixture with a highly transparent substance, such as N2 frost.

  16. Optical absorptions of polyfluorene transistors

    NASA Astrophysics Data System (ADS)

    Deng, Yvonne Y.; Sirringhaus, Henning

    2005-07-01

    Conjugated polymers are a promising class of materials for organic electronics. While the progress in device performance is impressive, the basics of charge transport still pose many open questions. Specifically, conduction at the comparatively rough polymer-polymer interface in an all-polymer field-effect transistor is expected to be different from a sharp interface with an inorganic dielectric, such as silicon dioxide. In this work, charge modulation spectroscopy (CMS) is used to study the optical absorptions in the presence of charges in situ in the transistor structure. This allows direct observation of the charge carriers in the operational device via their spectroscopic signature; the technique is by design very sensitive to the properties of the semiconductor-dielectric interface. The semiconducting copolymer poly( 9,9' -dioctyl-fluorene-co-bithiophene) (F8T2) is incorporated into a top-gate thin-film transistor structure with a polymer dielectric layer deposited by spin coating and inkjet-printed polymer electrodes. A prominent charge-induced absorption at 1.65eV is observed as well as a shoulder at 1.3eV and a tail extending toward the absorption edge. The bias dependence of the CMS signature confirms that intermixing of the polymer layers is minimal, as expected from the excellent transistor characteristics. Polarization-dependent CMS measurements on aligned transistors show that the main feature at 1.65eV is strongly polarized whereas the shoulder is unpolarized. This observation, as well as further experimental evidence, lead to the conclusion that while the main absorption is attributable to the intrinsic, polaronic absorption in F8T2, the shoulder is likely to originate from a defect state.

  17. Absorption heat pump system

    DOEpatents

    Grossman, G.

    1982-06-16

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  18. Compounds affecting cholesterol absorption

    NASA Technical Reports Server (NTRS)

    Hua, Duy H. (Inventor); Koo, Sung I. (Inventor); Noh, Sang K. (Inventor)

    2004-01-01

    A class of novel compounds is described for use in affecting lymphatic absorption of cholesterol. Compounds of particular interest are defined by Formula I: ##STR1## or a pharmaceutically acceptable salt thereof.

  19. 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

  20. Absorption heat pump system

    DOEpatents

    Grossman, Gershon

    1984-01-01

    The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

  1. Optical absorption measurement system

    DOEpatents

    Draggoo, Vaughn G.; Morton, Richard G.; Sawicki, Richard H.; Bissinger, Horst D.

    1989-01-01

    The system of the present invention contemplates a non-intrusive method for measuring the temperature rise of optical elements under high laser power optical loading to determine the absorption coefficient. The method comprises irradiating the optical element with a high average power laser beam, viewing the optical element with an infrared camera to determine the temperature across the optical element and calculating the absorption of the optical element from the temperature.

  2. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R.; Reed, Scott T.; Ashley, Carol S.; Martinez, F. Edward

    2003-10-14

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  3. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R.; Reed, Scott T.; Ashley, Carol S.; Martinez, F. Edward

    2004-08-31

    A new class of solar selective absorption coatings are disclosed. These coatings comprise a structured metallic overlayer such that the overlayer has a sub-micron structure designed to efficiently absorb solar radiation, while retaining low thermal emissivity for infrared thermal radiation. A sol-gel layer protects the structured metallic overlayer from mechanical, thermal, and environmental degradation. Processes for producing such solar selective absorption coatings are also disclosed.

  4. Intranasal absorption of oxymorphone.

    PubMed

    Hussain, M A; Aungst, B J

    1997-08-01

    The nasal bioavailability of oxymorphone HCI was determined. Rats were surgically prepared to isolate the nasal cavity, into which a solution of oxymorphone was administered. A reference group of rats was administered oxymorphone HCl intravenously. Plasma oxymorphone concentrations were determined by HPLC. Nasal absorption was rapid, nasal bioavailability was 43%, and the iv and nasal elimination profiles were similar. Oxymorphone HCI appears to have the solubility, potency, and absorption properties required for efficient nasal delivery, which is an alternative to injections.

  5. Atmospheric Solar Heating in Minor Absorption Bands

    NASA Technical Reports Server (NTRS)

    Chou, Ming-Dah

    1998-01-01

    Solar radiation is the primary source of energy driving atmospheric and oceanic circulations. Concerned with the huge computing time required for computing radiative transfer in weather and climate models, solar heating in minor absorption bands has often been neglected. The individual contributions of these minor bands to the atmospheric heating is small, but collectively they are not negligible. The solar heating in minor bands includes the absorption due to water vapor in the photosynthetically active radiation (PAR) spectral region from 14284/cm to 25000/cm, the ozone absorption and Rayleigh scattering in the near infrared, as well as the O2 and CO2 absorption in a number of weak bands. Detailed high spectral- and angular-resolution calculations show that the total effect of these minor absorption is to enhance the atmospheric solar heating by approximately 10%. Depending upon the strength of the absorption and the overlapping among gaseous absorption, different approaches are applied to parameterize these minor absorption. The parameterizations are accurate and require little extra time for computing radiative fluxes. They have been efficiently implemented in the various atmospheric models at NASA/Goddard Space Flight Center, including cloud ensemble, mesoscale, and climate models.

  6. Seven-effect absorption refrigeration

    DOEpatents

    DeVault, R.C.; Biermann, W.J.

    1989-05-09

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit. 1 fig.

  7. Seven-effect absorption refrigeration

    DOEpatents

    DeVault, Robert C.; Biermann, Wendell J.

    1989-01-01

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit.

  8. Optical absorption in trilayer graphene

    NASA Astrophysics Data System (ADS)

    Li, Xiao; Zhang, Fan; Niu, Qian

    2013-03-01

    We use a low energy effective model to analyze the optical responses of trilayer graphene samples. We first show that optical absorption of the ABA-stacked trilayer has strong dependence on both the Fermi energy and optical frequency, which is in sharp contrast to that of ABC-stacked trilayer graphene. Secondly, we are able to determine the possible existence of trigonal warping effects in the bandstructure of ABC-stacked trilayer graphene by a divergence in the absorption spectra at around 10 meV. In addition, we can partially distinguish the vairious broken symmetry states driven by electron-electron interactions in ABC-stacked trilayer graphene. In particular, the quantum anomalous Hall (QAH) state is sensitive to the polarization of the incident light, giving a way to detect its possible existence.

  9. Absorption-Line Studies of Seyfert Galaxies

    NASA Astrophysics Data System (ADS)

    Shull, J. Michael

    We propose to undertake a "reverberation analysis" of the variable absorption lines ill two Seyfert Galaxies (NGC 4051 and Mrk 279) to help understand the origin of intrinsic absorption lines in AGNs. Stich an analysis is a powerful tool for elucidating the radial distribution of absorbing gas in the broad-line region (BLR) and narrow-line region (NLR). Only two Seyferts have previously been studied with this technique: NGC 4151 (Bromage el al. 1985; Clavel et al. 1987) and NGC 3516 (Voit, Shull, and Begelman 1987). The absorption features have been interpreted as an outflow of ionized clouds from the nuclear region or from an accretion disk affected by UV/X-ray heating. Neither the source of the absorbing gas in these Seyferts nor the "gene" which distingishes them from other Seyferts is known. Until the 1984 onset of absorption in Mrk 279, broad self-absorbed. lines had been observed only in Seyferts of low intrinsic luminosity, such as NGC 4051. Mrk 279 is intrinsically much brighter, and therefore more quasar-like, than the other three absorptionline Seyfert I's in the CfA sample. Thus, it may show how the absorption phenomenon changes at higher luminosity and could bridge the gap between the low luminosity absorption-line Seyferts and the well-studied broad absorption-line (BAL) QSO's. In addition, Mrk 279's significant redshift will allow us to study, for the first time, the Ly-alpha line in an absorption-line Seyfert. With 3 US-1 shifts for each of these two underobserved Seyferts, we can double the number of objects in which absorption-line variability has been studied and investigate why the absorption-line strengths correlate or anti-correlate with the UV continuum.

  10. Selective coherent perfect absorption in metamaterials

    SciTech Connect

    Nie, Guangyu; Shi, Quanchao; Zhu, Zheng; Shi, Jinhui

    2014-11-17

    We show multi-band coherent perfect absorption (CPA) in simple bilayered asymmetrically split ring metamaterials. The selectivity of absorption can be accomplished by separately excited electric and magnetic modes in a standing wave formed by two coherent counterpropagating beams. In particular, each CPA can be completely switched on/off by the phase of a second coherent wave. We propose a practical scheme for realizing multi-band coherent perfect absorption of 100% that is allowed to work from microwave to optical frequency.

  11. Total absorption by degenerate critical coupling

    SciTech Connect

    Piper, Jessica R. Liu, Victor; Fan, Shanhui

    2014-06-23

    We consider a mirror-symmetric resonator with two ports. We show that, when excited from a single port, complete absorption can be achieved through critical coupling to degenerate resonances with opposite symmetry. Moreover, any time two resonances with opposite symmetry are degenerate in frequency and absorption is always significantly enhanced. In contrast, when two resonances with the same symmetry are nearly degenerate, there is no absorption enhancement. We numerically demonstrate these effects using a graphene monolayer on top of a photonic crystal slab, illuminated from a single side in the near-infrared.

  12. Polarization control of intermediate state absorption in resonance-mediated multi-photon absorption process

    NASA Astrophysics Data System (ADS)

    Xu, Shuwu; Huang, Yunxia; Yao, Yunhua; Jia, Tianqing; Ding, Jingxin; Zhang, Shian; Sun, Zhenrong

    2015-07-01

    We theoretically and experimentally demonstrate the control of the intermediate state absorption in an (n + m) resonance-mediated multi-photon absorption process by the polarization-modulated femtosecond laser pulse. An analytical solution of the intermediate state absorption in a resonance-mediated multi-photon absorption process is obtained based on the time-dependent perturbation theory. Our theoretical results show that the control efficiency of the intermediate state absorption by the polarization modulation is independent of the laser intensity when the transition from the intermediate state to the final state is coupled by the single-photon absorption, but will be affected by the laser intensity when this transition is coupled by the non-resonant multi-photon absorption. These theoretical results are experimentally confirmed via a two-photon fluorescence control in (2 + 1) resonance-mediated three-photon absorption of Coumarin 480 dye and a single-photon fluorescence control in (1 + 2) resonance-mediated three-photon absorption of IR 125 dye.

  13. Derivative spectrophotometry in the determination of phenyl-beta-naphthylamine used as an antioxidant in rubber mixtures.

    PubMed

    Moldovan, Z; Alexandrescu, L

    2002-09-01

    A method for the determination of phenyl-beta-naphthylamine (PBN) in ternary mixtures by second-derivative spectrophotometry is described. The procedure works without any separation step of PBN from the other polymer additives. By applying the second-derivative spectrophotometry, Beer's law was valid over the range 0.25-10 micro g mL(-1). The proposed method has been applied to the determination PBN in synthetic ternary mixtures and rubber samples. A comparative study of the results obtained using the second and the third-derivative spectrophotometric methods is presented and evaluated. The derivative spectrophotometric method indicated that the amount of PBN found after extraction from the rubber samples was 0.97+/-0.02 g/100 g of sample.

  14. Absorption heat pump system

    DOEpatents

    Grossman, Gershon; Perez-Blanco, Horacio

    1984-01-01

    An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

  15. Absorption Heat Pump Cycles

    NASA Astrophysics Data System (ADS)

    Kunugi, Yoshifumi; Kashiwagi, Takao

    Various advanced absorption cycles are studied, developed and invented. In this paper, their cycles are classified and arranged using the three categories: effect, stage and loop, then an outline of the cycles are explained on the Duehring diagram. Their cycles include high COP cycles for refrigerations and heat pumps, high temperature lift cycles for heat transformer, absorption-compression hybrid cycles and heat pump transformer cycle. The highest COPi is attained by the seven effect cycle. In addition, the cycles for low temperature are invented and explained. Furthermore the power generation • refrigeration cycles are illustrated.

  16. Lactose enhances mineral absorption in infancy.

    PubMed

    Ziegler, E E; Fomon, S J

    1983-05-01

    To determine if lactose promotes the intestinal absorption of calcium and other minerals by infants, metabolic balance studies were performed with infants fed two formulas nearly identical in composition except for carbohydrate. One contained only lactose and the other contained sucrose and corn starch hydrolysate. Each of six normal infants had two balance studies performed with each formula in alternating sequence. When lactose was the carbohydrate, net absorption and net retention of calcium were significantly greater than when lactose was not present in the formula. Absorptions of magnesium and manganese were also significantly enhanced by lactose. Absorptions of copper and zinc were somewhat greater (not statistically significant) when lactose was present, whereas absorption of iron was not affected. Absorption of phosphorus was not different, but urinary excretion was less when the lactose containing formula was fed and, hence, net retention of phosphorus was significantly enhanced. These results confirm findings from animal studies and previous human studies and show that, in infants, lactose has a significant and sustained promoting effect on absorption of calcium and other minerals.

  17. Solid methane on Triton and Pluto - 3- to 4-micron spectrophotometry

    SciTech Connect

    Spencer, J.R.; Buie, M.W.; Bjoraker, G.L. Space Telescope Science Institute, Baltimore, MD NASA, Goddard Space Flight Center, Greenbelt, MD )

    1990-12-01

    Methane has been identified in the Pluto/Charon system on the basis of absorption features in the reflectance spectrum at 1.5 and 2.3 microns; attention is presently given to observations of a 3.25 micron-centered deep absorption feature in Triton and Pluto/Charon system reflectance spectra. This absorption may indicate the presence of solid methane, constituting either the dominant surface species or a mixture with a highly transparent substance, such as N2 frost. 35 refs.

  18. Spectrophotometry of zonal cloud structure variations on Jupiter, 1988-1993

    NASA Astrophysics Data System (ADS)

    Tejfel, V. G.; Vdovichenko, V. D.; Sinyaeva, N. V.; Mosina, S. A.; Gajsina, W. N.; Kharitonova, G. A.; Aksenov, A. N.

    1994-04-01

    Global changes of zonal cloud structure on Jupiter have been observed and analyzed from data obtained with a 1-m telescope and a low-dispersion spectrograph in the spectral range wavelengths 400-680 nm, and with a 70-cm telescope and planetary three-channel spectrometer in the spectral range wavelengths 320-1100 nm during each Jovian apparition from 1988 to 1992. Variations of the observed meridional intensity profiles and relative spectrophotometric gradients are described as well as the changes of absolute spectral reflectivity of five main belts on Jupiter (North and South Equatorial belts, North and South Tropical zones, and Equatorial region). Some peculiarities in the behavior of spectrophotometric gradients may be interpreted as a result of increased Rayleigh scattering in the gas layer over the deeper effective cloud boundary within main dark belts. The polar limb darkening varies only slightly with wavelength and it may be considered as evidence for dark aerosols in the stratosphere at high latitudes. The intensity of the methane absorption band centered at 8860 A shows an increase from the equator to temperate latitudes throughout the 1988-1992 period, despite the large variations in belt and zone reflectivities observed during this period in the southern hemisphere.

  19. Multimode Surface Functional Group Determination: Combining Steady-State and Time-Resolved Fluorescence with X-ray Photoelectron Spectroscopy and Absorption Measurements for Absolute Quantification.

    PubMed

    Fischer, Tobias; Dietrich, Paul M; Unger, Wolfgang E S; Rurack, Knut

    2016-01-19

    The quantitative determination of surface functional groups is approached in a straightforward laboratory-based method with high reliability. The application of a multimode BODIPY-type fluorescence, photometry, and X-ray photoelectron spectroscopy (XPS) label allows estimation of the labeling ratio, i.e., the ratio of functional groups carrying a label after reaction, from the elemental ratios of nitrogen and fluorine. The amount of label on the surface is quantified with UV/vis spectrophotometry based on the molar absorption coefficient as molecular property. The investigated surfaces with varying density are prepared by codeposition of 3-(aminopropyl)triethoxysilane (APTES) and cyanoethyltriethoxysilane (CETES) from vapor. These surfaces show high functional group densities that result in significant fluorescence quenching of surface-bound labels. Since alternative quantification of the label on the surface is available through XPS and photometry, a novel method to quantitatively account for fluorescence quenching based on fluorescence lifetime (τ) measurements is shown. Due to the complex distribution of τ on high-density surfaces, the stretched exponential (or Kohlrausch) function is required to determine representative mean lifetimes. The approach is extended to a commercial Rhodamine B isothiocyanate (RITC) label, clearly revealing the problems that arise from such charged labels used in conjunction with silane surfaces.

  20. [Determination of trace amounts of aluminum by light-absorption ratio variation combined with continuous flow analysis].

    PubMed

    Wang, Hong-yan; Gao, Hong-wen

    2008-12-01

    In a pH 5.66 acetate-acetic acid medium, the complex reaction of Al(II) with chlorophosphonazo-mS (MSCPA) is very sensitive. In order to react with Al(III) completely, MSCPA must be added excessively enough. Without doubt, the excess MSCPA in the reaction solution affected the measurement of light-absorption of the Al-MSCPA complex. Thus, ordinary spectrophotmetry is unfit for the measurement of such a complex. To eliminate such an interference, both A(537 nm), and A(618 nm) were selected as the work wavelengths and the spectral correction technique was applied to the characterization of the above complex. The result showed that the composition ratio of Al(III) to MSCPA is 1:1. Using the complexation, a new dual-wavelength approach named the light-absorption ratio variation approach (LARVA) was applied to the determination of trace amounts of Al(III), which often increases the sensitivity up to 10 times better than ordinary spectrophotometry. From the LARVA, the less the MSCPA added, the higher the sensitivity obtained. However, a too low amount of MSCPA caused an obvious error in the measurement because of the noise of instrument background. In the present work, 2.80 micromol x L(-1) MSCPA was added into the Al(III) solution. The absorbance ratio difference (deltaAr) of the Al-MSCPA solution is proportional to the Al(III) concentration in the range of 0 and 0.150 mg x mL(-1). The LOD of Al(III) is only 2 mg x L(-1). The result indicated that many kinds of metal ions did not affect the direct determination of Al(III). Besides, the addition of thiourea solution may mask Fe(III) and Cr(III) effectively. The complexation between Al(III) and MSCPA was completed in 2 min, and the color absorption of solution remained almost constant for more than 1 h. Therefore, a set of continuous flow analysis (CFA) device was designed for the online rapid analysis of Al(III) and coupled with LARVA to increase greatly the analytical efficiency. The results showed that the LOD of Al

  1. Two-Phonon Absorption

    ERIC Educational Resources Information Center

    Hamilton, M. W.

    2007-01-01

    A nonlinear aspect of the acousto-optic interaction that is analogous to multi-photon absorption is discussed. An experiment is described in which the second-order acousto-optically scattered intensity is measured and found to scale with the square of the acoustic intensity. This experiment using a commercially available acousto-optic modulator is…

  2. Spectrophotometry of the Deep Impact Ejecta of Comet 9P/Tempel 1

    NASA Astrophysics Data System (ADS)

    Hodapp, K. W.; Aldering, G.; Meech, K. J.; Cochran, A.

    We have obtained optical spectrophotometry of the evolution of comet 9P/Tempel 1 after the impact of the Deep Impact spacecraft [1], using the SNIFS Supernova Integral Field Spectrograph at the UH 2.2 m telescope. From the data-cubes, we extracted both continuum flux distributions as well as emission line fluxes of the violet CN system and of [OI].We found that the continuum brightness of the comet, i.e., scattered sunlight, started rising immediately after the impact, but that the ejecta were slightly bluer in color than the material normally released by the comet.The emission of [OI] at 630 nm, which is a tracer of water, rose similar to the scattered continuum light, but then remained nearly constant for several hours after impact.We found that CN emission at 388 nm centered on the nucleus was delayed compared to the rise of dust-scattered sunlight. This CN emission also expanded faster spatially than the cloud of scattering dust.

  3. Spectrophotometry of the galaxies and nebulosity associated with the quasar III Zw 2

    NASA Technical Reports Server (NTRS)

    Green, R. F.; Williams, T. B.; Morton, D. C.

    1978-01-01

    Results are presented for spectrophotometry of the object III Zw 2, the faint nebulosity to the NW of its nucleus, and two associated galaxies (a normal elliptical and a more luminous late-type spiral). The object III Zw 2 is defined to be a quasar on the basis of its dominant starlike nucleus, redshift, and optical and radio variability. The spectrophotometrically measured redshifts of the two associated galaxies are shown to place III Zw 2 as a member of Zwicky Cluster 0007.7+1056, thus establishing the cosmological origin of the quasar's emission-line redshift of 0.089. It is found that the nebulosity to the NW of the quasar exhibits an emission-line spectrum at the same redshift as the nucleus with an underlying red continuum, that the strength of the forbidden lines relative to the permitted lines is 3 to 4 times greater than in the nucleus, and that the data for the nebulosity are not well fitted by a bremsstrahlung emission spectrum, but are consistent with a spectrum of starlight from an underlying galaxy at the system redshift of 0.089.

  4. Measurement of mucosal capillary hemoglobin oxygen saturation in the colon by reflectance spectrophotometry

    NASA Astrophysics Data System (ADS)

    Friedland, Shai; Benaron, David A.; Parachikov, Ilian H.; Soetikno, Roy

    2003-06-01

    Advances in optical and computer technology have enabled the development of a device that utilizes white-light reflectance spectrophotometry to measure capillary hemoglobin saturation in intestinal mucosa during colonoscopy. Studies were performed using the colon oximeter in anesthetized animals and patients undergoing colonoscopy. Mucosal hemoglobin saturation in the normal colon (mean +/- S.D.) is 72% +/- 3.5%. In an animal model, ischemia via arterial ligation and hypoxemia via hypoxic ventilation each result in a decrease of over 40% in the mucosal saturation. In human patients with colon polyps, ischemia induced by epinephrine injection, stalk ligation using a loop, or clipping of the polyp stalk each result in a decrease of over 40% in the mucosal saturation (p<0.02). In contrast, saline injection does not decrease the mucosal saturation (p=N.S.). A patient who previously underwent partial colectomy with sacrifice of the inferior mesenteric artery had a saturation of 55% in the remaining sigmoid colon, with normal values in the superior mesenteric artery territory (p<0.05). A novel device for measuring capillary hemoglobin saturation in intestinal mucosa during colonoscopy is capable of providing reproducible measurements in normal patients and clearly detects dramatic decreases in saturation with ischemic and hypoxic insults.

  5. Direct UV Spectrophotometry and HPLC Determination of Triton X-100 in Split Virus Influenza Vaccine.

    PubMed

    Pavlović, Bojana; Cvijetić, Nataša; Dragačević, Luka; Ivković, Branka; Vujić, Zorica; Kuntić, Vesna

    2016-01-01

    One of the most commonly used surfactants in the production of split virus influenza vaccine is nonionic surfactant Triton X-100. After splitting of the virus is accomplished, Triton X-100 is removed from the vaccine by subsequent production steps. Because of toxicity of Triton X-100, which remains in the vaccine in residual amounts, a sufficiently sensitive method for its detection and quantification needs to be defined. Two methods for determination of Triton X-100 residuals were developed: the UV-spectrophotometry and HPLC methods. For both methods, preparation of vaccine samples and removal of proteins and virus particles were crucial: samples were treated with methanol (1:1) and then centrifuged at 25 000 × g for 30 min. After such treatment, the majority of vaccine components that interfered in the UV region were removed, and diluted samples could be directly measured. The chromatographic system included C18 column, step methanol gradient, and detection at 225 nm with a single peak of Triton X-100 at 12.6 min. Both methods were validated and gave satisfactory results for accuracy, precision, specificity, linearity, and robustness. LOQ was slightly lower for the HPLC method. Hence, it was shown that both methods are suitable for analysis of residual amounts of Triton X-100, with the advantages of the UV method being its simplicity and availability in most laboratories.

  6. Determination of Oxytetracycline from Salmon Muscle and Skin by Derivative Spectrophotometry.

    PubMed

    Toral, M Inés; Sabay, Tamara; Orellana, Sandra L; Richter, Pablo

    2015-01-01

    A method was developed for the identification and quantification of oxytetracycline residues present in salmon muscle and skin using UV-Vis derivative spectrophotometry. With this method, it was possible to reduce the number of steps in the procedure typically required for instrumental analysis of a sample. The spectral variables, order of the derivative, scale factor, smoothing factor, and analytical wavelength were optimized using standard solutions of oxytetracycline dissolved in 900 mg/L oxalic acid in methanol. The matrix effect was significant; therefore, quantification for oxytetracycline residues was carried out using drug-free salmon muscle and skin samples fortified with oxytetracycline. The LOD and LOQ were found to be 271 and 903 μg/kg, respectively. The precision and accuracy of the method were validated using drug-free salmon muscle and skin tissues fortified at three different concentrations (8, 16, and 32 mg/kg) on 3 different days. The recoveries at all fortified concentrations were between 90 and 105%, and RSDs in all cases were less than 6.5%. This method can be used to screen out compliant samples and thereby reduce the number of suspect positive samples that will require further confirmatory analysis.

  7. Application of response surface methodology for determination of methyl red in water samples by spectrophotometry method.

    PubMed

    Khodadoust, Saeid; Ghaedi, Mehrorang

    2014-12-10

    In this study a rapid and effective method (dispersive liquid-liquid microextraction (DLLME)) was developed for extraction of methyl red (MR) prior to its determination by UV-Vis spectrophotometry. Influence variables on DLLME such as volume of chloroform (as extractant solvent) and methanol (as dispersive solvent), pH and ionic strength and extraction time were investigated. Then significant variables were optimized by using a Box-Behnken design (BBD) and desirability function (DF). The optimized conditions (100μL of chloroform, 1.3mL of ethanol, pH 4 and 4% (w/v) NaCl) resulted in a linear calibration graph in the range of 0.015-10.0mgmL(-1) of MR in initial solution with R(2)=0.995 (n=5). The limits of detection (LOD) and limit of quantification (LOQ) were 0.005 and 0.015mgmL(-1), respectively. Finally, the DLLME method was applied for determination of MR in different water samples with relative standard deviation (RSD) less than 5% (n=5).

  8. Application of response surface methodology for determination of methyl red in water samples by spectrophotometry method

    NASA Astrophysics Data System (ADS)

    Khodadoust, Saeid; Ghaedi, Mehrorang

    2014-12-01

    In this study a rapid and effective method (dispersive liquid-liquid microextraction (DLLME) was developed for extraction of methyl red (MR) prior to its determination by UV-Vis spectrophotometry. Influence variables on DLLME such as volume of chloroform (as extractant solvent) and methanol (as dispersive solvent), pH and ionic strength and extraction time were investigated. Then significant variables were optimized by using a Box-Behnken design (BBD) and desirability function (DF). The optimized conditions (100 μL of chloroform, 1.3 mL of ethanol, pH 4 and 4% (w/v) NaCl) resulted in a linear calibration graph in the range of 0.015-10.0 mg mL-1 of MR in initial solution with R2 = 0.995 (n = 5). The limits of detection (LOD) and limit of quantification (LOQ) were 0.005 and 0.015 mg mL-1, respectively. Finally, the DLLME method was applied for determination of MR in different water samples with relative standard deviation (RSD) less than 5% (n = 5).

  9. Endoscopic reflectance spectrophotometry and visible light spectroscopy in clinical gastrointestinal studies.

    PubMed

    Leung, Felix W

    2008-06-01

    The use of reflectance spectrophotometry (RS) for mucosal hemodynamic measurement relies on the recognition of changes in indexes of mucosal hemoglobin concentration and oxygen saturation. Endoscopic application in clinical studies has confirmed important observations demonstrated in animal experiments. The vasoconstriction induced by propranolol, vasopressin, glypressin, or somatostatin in the portal hypertensive gastric mucosa and the reduction of gastroduodenal mucosal perfusion by nonsteroidal anti-inflammatory drugs (NSAIDs) or smoking, mesenteric venoconstriction associated with systemic hypoxia, and acid-induced duodenal hyperemia are important examples. Prognostic predictions include the development of stress-induced gastric ulcerations in patients with significant reductions in gastric perfusion after thermal or head injury, or the demonstration of delayed gastric or duodenal ulcer healing when the hyperemia at the ulcer margin fails to materialize. In mechanical-ventilator-dependent patients with sepsis, a significantly reduced gastric mucosal RS measurement portends a grave prognosis (mortality >80%). Recent advances in technology resulted in the construction and validation of instruments for visible light spectroscopy. Measurements focused on tissue oxygen saturation demonstrated epinephrine and vessel-ligation-induced vasoconstriction, the absence of ischemia in radiation-induced rectal telangiectasias, and gut ischemia responsive to revascularization treatment. Endoscopic RS and visible light spectroscopy are suitable for assessing the role of blood flow in conditions with a lesser degree of ischemia and for testing the hypothesis that functional dyspepsia and dysmotility syndromes may be due to gut ischemia.

  10. Determination of myoglobin based on its enzymatic activity by stopped-flow spectrophotometry

    NASA Astrophysics Data System (ADS)

    Zheng, Qi; Liu, Zhihong; Cai, Ruxiu

    2005-04-01

    A new method has been developed for the determination of myoglobin (Mb) based on its enzymatic activity for the oxidation of o-phenylenediamine (OPDA) with hydrogen peroxide. Stopped-flow spectrophotometry was used to study the kinetic behavior of the oxidation reaction. The catalytic activity of Mb was compared to other three kinds of catalyst. The time dependent absorbance of the reaction product, 2,3-diamimophenazine (DAPN), at a wavelength of 426 nm was recorded. The initial reaction rate obtained at 40 °C was found to be proportional to the concentration of Mb in the range of 1.0 × 10 -6 to 4.0 × 10 -9 mol L -1. The detection limit of Mb was found to be 9.93 × 10 -10 mol L -1. The relative standard deviations were within 5% for the determination of different concentrations of Mb. Excess of bovine serum albumin (BSA), Ca(II), Mg(II), Cu(II), glucose, caffeine, lactose and uric acid did not interfere.

  11. Fourier transform infrared spectrophotometry for thin film monitors: computer and equipment integration for enhanced capabilities

    NASA Astrophysics Data System (ADS)

    Cox, J. Neal; Sedayao, J.; Shergill, Gurmeet S.; Villasol, R.; Haaland, David M.

    1991-03-01

    Fourier transform infrared spectrophotometry (FTIR) is a valuable technique for monitoring thin films used in semiconductor device manufacture. Determinations of the constituent contents in borophosphosilicate (BPSG) phosphosilicate (PSG) silicon oxynitride (SiON:H and spin-on-glass (SOG) thin films are a few applications. Due to the nature of the technique FTIR instrumentation is one of the most extensively computer-dependent pieces of equipment that is likely to be found in a microelectronics plant. In the role of fab monitor or reactor characterization tool FTIR instruments can rapidly generate large amounts of data. Also the drive for greater accuracy and tighter precision is leading to the development of increasingly sophisticated data processing software that tax the computing abilities of most instrument local data stations. By linking a local FTIR data station to a remote minicomputer its capabilities are greatly improved. We discuss three classes of enhancement. First the FTIR in the fab area communicates and interacts in real time with the minicomputer: transferring data segments to it instructing it to perform sophisticated processing and returning the results to the operator in the fab. Characterizations of PSG thin films by this approach are discussed. Second the spectra of large numbers of samples are processed locally. The large database is then transmitted to the minicomputer for study by statistical/graphics software. Results of CVD-reactor spatial profiling experiments for plasma SiON are presented. Third processing of calibration spectra is performed

  12. Tissue spectrophotometry and thermographic imaging applied to routine clinical prediction of amputation level viability

    NASA Astrophysics Data System (ADS)

    Hanson, Jon M.; Harrison, David K.; Hawthorn, Ian E.

    2002-06-01

    About 5% of British males over 50 years develop peripheral arterial occlusive disease. Of these about 2% ultimately require lower limb amputation. In 1995 we proposed a new technique using lightguide spectrophotometry to measure the oxygen saturation level of haemoglobin (SO2) in the skin as a method for predicting tissue viability. This technique, in combination with thermographic imaging, was compared with skin blood flow measurements using the I125)4- Iodoantipyrine (IAP) clearance technique. The optical techniques gave a sensitivity and selectivity of 1.0 for the prediction of successful outcome of a below knee amputation compared with a specificity of 93% using the traditional IAP technique at a below knee to above knee amputation ratio (BKA:AKA) of 75%. The present study assesses the routine clinical application of these optical techniques. The study is ongoing, but the data to date comprises 22 patients. 4 patients were recommended for above knee amputation (AKA) and 18 patients for below knee amputation on the basis of thermographic and tissue SO2 measurements. All but one of the predicted BKA amputations healed. The study to date produces evidence of 94% healing rate (specificity) for a BKA:AKA ratio of 82%. This compares favorably with the previous figures given above.

  13. [Mutual Effect on Determination of Gibberellins and Glyphosate in Groundwater by Spectrophotometry].

    PubMed

    Zhang, Li; Chen, Liang; Liu, Fei

    2015-04-01

    In the present study, a spectrophotometry method for the simultaneous determination of gibberellins (GA3) and glyphosate in groundwater was established and optimized. In addition, the mutual effect on simultaneous determination of GA3 and glyphosate was studied. Based on the experiment, good linearity (R2 > 0.99) was obtained for GA3 in the range of 0-20 and 0-100 µg and for glyphosate in the range of 0-8 and 5-15 µg. The method's detection limit (MDL) of GA3 and glyphosate was 0.48 and 0.82 µg, respectively; and the recovery rates of 15 to 150 µg GA3 and 3 to 10 µg glyphosate in all samples at a spiked level were 71.3% ± 1.9% and 98.4% ± 8.1%, respectively. No obvious influence of glyphosate (0-100 mg · L(-1)) on the recovery rates of GA3 was observed, but the presence of glyphosate could cause slight determination precision decrease of GA3. Meanwhile, adding 2 mg · L(-1) GA3 can increase the recovery rate of glyphosate.

  14. Blood oxygen saturation determined by transmission spectrophotometry of hemolyzed blood samples

    NASA Technical Reports Server (NTRS)

    Malik, W. M.

    1967-01-01

    Use of the Lambert-Beer Transmission Law determines blood oxygen saturation of hemolyzed blood samples. This simplified method is based on the difference in optical absorption properties of hemoglobin and oxyhemoglobin.

  15. 15. Detail showing lower chord pinconnected to vertical member, showing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. Detail showing lower chord pin-connected to vertical member, showing floor beam riveted to extension of vertical member below pin-connection, and showing brackets supporting cantilevered sidewalk. View to southwest. - Selby Avenue Bridge, Spanning Short Line Railways track at Selby Avenue between Hamline & Snelling Avenues, Saint Paul, Ramsey County, MN

  16. Performance Analysis of Solution Transportation Absorption Chiller

    NASA Astrophysics Data System (ADS)

    Kiani, Behdad; Hamamoto, Yoshinori; Akisawa, Atsushi; Kashiwagi, Takao

    Thermally activated advanced absorption cycles are considered promising candidates to replace CFCs, HCFCs and HFCs for residential and commercial applications. In such absorption systems, it is desirable to utilize the waste heat from industries for heating and cooling applications in commercial and residential sectors. For this purpose, it is necessary to transport energy over some distance because the waste heat source and demand are generally located apart from each other. Transportation of steam, hot water or chilled water requires high construction costs for insulation. There is an efficient method of energy transportation using absorption system called “ Solution Transportation Absorption System (STA)”. The solution is transported at an ambient temperature so that tube-insulations not required. This paper shows the simulation of the abovementioned system and the optimal result, using mathematical optimization. The optimum system with industry‧s waste heat utilization is obtained. At the end, the effect on the pollution emission and energy conservation is obtained.

  17. Theory of absorption-induced transparency

    NASA Astrophysics Data System (ADS)

    Rodrigo, Sergio G.; García-Vidal, F. J.; Martín-Moreno, L.

    2013-10-01

    Recent experiments [Hutchison, O’Carroll, Schwartz, Genet, and Ebbesen, Angew. Chem. Int. Ed.1433-785110.1002/anie.201006019 50, 2085 (2011)] have demonstrated that optical transmission through an array of subwavelength holes in a metal film can be enhanced by the intentional presence of dyes in the system. As the transmission maximum occurs spectrally close to the absorption resonances of the dyes, this phenomenon was christened “absorption induced transparency”. Here, a theoretical study on absorption induced transparency is presented. The results show that the appearance of transmission maxima requires that the absorbent fills the holes and that it occurs also for single holes. Furthermore, it is shown that the transmission process is nonresonant, being composed by a sequential passage of the electromagnetic field through the hole. Finally, the physical origin of the phenomenon is demonstrated to be nonplasmonic, which implies that absorption induced transparency should also occur at the infrared or terahertz frequency regimes.

  18. The origin of the excess transit absorption in the HD 189733 system: planet or star?

    NASA Astrophysics Data System (ADS)

    Barnes, J. R.; Haswell, C. A.; Staab, D.; Anglada-Escudé, G.

    2016-10-01

    We have detected excess absorption in the emission cores of Ca II H&K during transits of HD 189733b for the first time. Using observations of three transits, we investigate the origin of the absorption, which is also seen in Hα and the Na I D lines. Applying differential spectrophotometry methods to the Ca II H and Ca II K lines combined, using respective passband widths of Δλ = 0.4 and 0.6 Å yields excess absorption of td = 0.0074 ± 0.0044 (1.7σ; Transit 1) and 0.0214 ± 0.0022 (9.8σ; Transit 2). Similarly, we detect excess Hα absorption in a passband of width Δλ = 0.7 Å, with td = 0.0084 ± 0.0016 (5.2σ) and 0.0121 ± 0.0012 (9.9σ). For both lines, Transit 2 is thus significantly deeper. Combining all three transits for the Na I D lines yields excess absorption of td = 0.0041 ± 0.0006 (6.5σ). By considering the time series observations of each line, we find that the excess apparent absorption is best recovered in the stellar reference frame. These findings lead us to postulate that the main contribution to the excess transit absorption in the differential light curves arises because the normalizing continuum bands form in the photosphere, whereas the line cores contain a chromospheric component. We cannot rule out that part of the excess absorption signature arises from the planetary atmosphere, but we present evidence which casts doubt on recent claims to have detected wind motions in the planet's atmosphere in these data.

  19. Formaldehyde Absorption toward W51

    SciTech Connect

    Kogut, A.; Smoot, G.F.; Bennett, C.L.; Petuchowski, S.J.

    1988-04-01

    We have measured formaldehyde (H{sub 2}CO) absorption toward the HII region complex W51A (G49.5-0.4) in the 6 cm and 2 cm wavelength rotational transitions with angular resolution of approximately 4 inch. The continuum HII region shows a large, previously undetected shell structure 5.5 pc along the major axis. We observe no H{sub 2}CO emission in regions of low continuum intensity. The absorption, converted to optical depth, shows a higher degree of clumping than previous maps at lower resolution. The good S/N of the maps allows accurate estimation of the complicated line profiles, showing some of the absorbing clouds to be quite patchy. We list the properties of the opacity spectra for a number of positions both in the clumps and in the more diffuse regions of the absorbing clouds, and derive column densities for the 1{sub 11} and 2{sub 12} rotational levels of ortho-formaldehyde.

  20. 69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    69. INTERIOR VIEW OF THE ABSORPTION TOWER BUILDING, ABSORPTION TOWER UNDER CONSTRUCTION. (DATE UNKNOWN). - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

  1. Effect of idler absorption in pulsed optical parametric oscillators.

    PubMed

    Rustad, Gunnar; Arisholm, Gunnar; Farsund, Øystein

    2011-01-31

    Absorption at the idler wavelength in an optical parametric oscillator (OPO) is often considered detrimental. We show through simulations that pulsed OPOs with significant idler absorption can perform better than OPOs with low idler absorption both in terms of conversion efficiency and beam quality. The main reason for this is reduced back conversion. We also show how the beam quality depends on the beam width and pump pulse length, and present scaling relations to use the example simulations for other pulsed nanosecond OPOs.

  2. Quantum absorption refrigerator.

    PubMed

    Levy, Amikam; Kosloff, Ronnie

    2012-02-17

    A quantum absorption refrigerator driven by noise is studied with the purpose of determining the limitations of cooling to absolute zero. The model consists of a working medium coupled simultaneously to hot, cold, and noise baths. Explicit expressions for the cooling power are obtained for Gaussian and Poisson white noise. The quantum model is consistent with the first and second laws of thermodynamics. The third law is quantified; the cooling power J(c) vanishes as J(c) ∝ T(c)(α), when T(c)→0, where α=d+1 for dissipation by emission and absorption of quanta described by a linear coupling to a thermal bosonic field, where d is the dimension of the bath.

  3. Acoustic absorption by sunspots

    NASA Technical Reports Server (NTRS)

    Braun, D. C.; Labonte, B. J.; Duvall, T. L., Jr.

    1987-01-01

    The paper presents the initial results of a series of observations designed to probe the nature of sunspots by detecting their influence on high-degree p-mode oscillations in the surrounding photosphere. The analysis decomposes the observed oscillations into radially propagating waves described by Hankel functions in a cylindrical coordinate system centered on the sunspot. From measurements of the differences in power between waves traveling outward and inward, it is demonstrated that sunspots appear to absorb as much as 50 percent of the incoming acoustic waves. It is found that for all three sunspots observed, the amount of absorption increases linearly with horizontal wavenumber. The effect is present in p-mode oscillations with wavelengths both significantly larger and smaller than the diameter of the sunspot umbrae. Actual absorption of acoustic energy of the magnitude observed may produce measurable decreases in the power and lifetimes of high-degree p-mode oscillations during periods of high solar activity.

  4. 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

    Graphical abstract: Display Omitted Highlights: ► Self-assembled stannous oxide (SnO) 2D nano-square sheets have been synthesized. ► The average size of the nano-square sheets is about 200–400 nm. ► Direct optical band gap of 3.16 eV was acquired by using Davis–Mott model. ► The hydrogen absorption capacity of as-synthesized material was 1.194 wt.% comparatively good. -- Abstract: Stannous oxide is an important functional material which contributes to a wide range of applications in energy storage and optoelectronic devices. In the present study, the single crystalline self-assembled stannous oxide (SnO) 2D nano-square sheets have been synthesized with template-free hydrothermal growth method. The morphology, composition and structure were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) with selected area electron diffraction (SAED), energy dispersive X-ray (EDX), X-ray diffraction (XRD) and Raman spectroscopy, respectively. FESEM results have illustrated that the size of self-assembled 3D hierarchical polygon-shape structure of SnO is in the range of 8–12 μm and the average size of the nano-square sheets is about 100 nm. X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns have revealed that the prepared SnO nano-square sheets exist in single-crystalline nature. Two Raman modes A{sub 1g} = 211 cm{sup −1} and B{sub 1g} = 113 cm{sup −1} were observed by Raman spectroscopy, which is consistent with nano tetragonal phase SnO. Furthermore, the chemical valence of Sn and relative atomic composition of as-prepared SnO have been confirmed by X-ray photoelectron spectroscopy (XPS). Ultraviolet–visible–near infrared spectrophotometry was used to study the transmittance behavior of SnO nano-structures and direct optical band gap of 3.16 eV was acquired by using Davis–Mott model. The first ever study on

  5. Bioacoustic Absorption Spectroscopy

    DTIC Science & Technology

    2016-06-07

    seas in co-operation with fisheries biologists. The first planned experiment will be in the seas off California in co-operation with the Southwest... Fisheries Science Center of NOAA’s National Marine Fisheries Service. These experiments will be designed to investigate the “signatures” of the two major...formulating environmental adaptation strategies for tactical sonars. Fisheries applications: These results suggest that bioacoustic absorptivity can be used to

  6. Vehicular impact absorption system

    NASA Technical Reports Server (NTRS)

    Knoell, A. C.; Wilson, A. H. (Inventor)

    1978-01-01

    An improved vehicular impact absorption system characterized by a plurality of aligned crash cushions of substantially cubic configuration is described. Each consists of a plurality of voided aluminum beverage cans arranged in substantial parallelism within a plurality of superimposed tiers and a covering envelope formed of metal hardware cloth. A plurality of cables is extended through the cushions in substantial parallelism with an axis of alignment for the cushions adapted to be anchored at each of the opposite end thereof.

  7. Hydrogen Absorption by Niobium.

    DTIC Science & Technology

    1982-04-13

    incorporate an independent means for ascertaining surface cleanliness (e.g. AES). The form of the absorption curve in Fig. 7 appears to agree with that...very interesting study and is well within the capabilities of the systen designed, if the surface cleanliness can be assured. Wire specimens have a...assessing surface cleanliness would be an important supporting technique for understanding the results of these measurements. The simple kinetic

  8. Relic Neutrino Absorption Spectroscopy

    SciTech Connect

    Eberle, b

    2004-01-28

    Resonant annihilation of extremely high-energy cosmic neutrinos on big-bang relic anti-neutrinos (and vice versa) into Z-bosons leads to sizable absorption dips in the neutrino flux to be observed at Earth. The high-energy edges of these dips are fixed, via the resonance energies, by the neutrino masses alone. Their depths are determined by the cosmic neutrino background density, by the cosmological parameters determining the expansion rate of the universe, and by the large redshift history of the cosmic neutrino sources. We investigate the possibility of determining the existence of the cosmic neutrino background within the next decade from a measurement of these absorption dips in the neutrino flux. As a by-product, we study the prospects to infer the absolute neutrino mass scale. We find that, with the presently planned neutrino detectors (ANITA, Auger, EUSO, OWL, RICE, and SalSA) operating in the relevant energy regime above 10{sup 21} eV, relic neutrino absorption spectroscopy becomes a realistic possibility. It requires, however, the existence of extremely powerful neutrino sources, which should be opaque to nucleons and high-energy photons to evade present constraints. Furthermore, the neutrino mass spectrum must be quasi-degenerate to optimize the dip, which implies m{sub {nu}} 0.1 eV for the lightest neutrino. With a second generation of neutrino detectors, these demanding requirements can be relaxed considerably.

  9. The usage of activated carbon from teak sawdust (tectona grandis l.f.) and zeolite for the adsorption of Cr(VI) and its analysis using solid-phase spectrophotometry (sps)

    NASA Astrophysics Data System (ADS)

    Saputro, S.; Masykuri, M.; Mahardiani, L.; Mulyani, B.; Qorina, I.; Yoshimura, K.; Takehara, K.; Matsuoka, S.

    2017-02-01

    This study aims to evaluate the usage of teak sawdust and zeolite as an adsorbent of Cr(VI) ion; optimal composition ratio of the composite adsorbent; and the sensitivity of solid-phase spectrophotometry (SPS) as a method to determine the levels of Cr(VI) ion as an adsorption results of adsorbents. The adsorbent used were teak sawdust activated carbon and zeolite as a single and composite adsorbents. The teak sawdust carbonization using muffle furnace and then activated with H3PO4 10% while the zeolite with H2SO4 10%. The contacting process of the adsorbents with Cr(VI) was done by varying the compositions. Analysis of Cr(VI) level was done using SPS method. Characterization of adsorbent before and after being activated is done using a FTIR. The results showed that teak sawdust and zeolite can be used as adsorbents to adsorb Cr(VI) in the simulated liquid waste with the adsorption capacity 1.19 µg/g the optimum composition ratio of teak sawdust activated carbon and zeolite was 75%:25% with the percentage of adsorption was 62.72%. Solid-phase spectrophotometry is a sensitive method to analyze the decreased levels of Cr(VI) as an adsorption results in µg/L level with the limit of detection (LOD) was 0.03 µg/L.

  10. Iodine Absorption Cells Purity Testing

    PubMed Central

    Hrabina, Jan; Zucco, Massimo; Philippe, Charles; Pham, Tuan Minh; Holá, Miroslava; Acef, Ouali; Lazar, Josef; Číp, Ondřej

    2017-01-01

    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). PMID:28067834

  11. Lead Quantification in Urine Samples of Athletes by Coupling DLLME with UV-Vis Spectrophotometry.

    PubMed

    Faraji, Hakim; Helalizadeh, Masoumeh

    2017-04-01

    Urine lead level is one of the most employed measures of lead exposure and risk. The urine samples used in this study were obtained from ten healthy male cyclists. Dispersive liquid-liquid microextraction combined with ultraviolet and visible spectrophotometry was utilized for preconcentration, extraction, and determination of lead in urine samples. Optimization of the independent variables was carried out based on chemometric methods in three steps. According to the screening and optimization study, 133 μL of CCl4 (extracting solvent), 1.34 mL ethanol (dispersing solvent), pH 2.0, 0.00 % of salt, and 0.1 % O,O-diethyl dithiophosphoric (chelating agent) were used as the optimum independent variables for microextraction and determination of lead. Under the optimized conditions, R (2) was 0.9991, and linearity range was 0.01-100 μg L(-1). Precision was evaluated in terms of repeatability and intermediate precision, with relative standard deviations being <9.1 and <15.3 %, respectively. The accuracy was estimated using urine samples of cyclists as real samples and it was confirmed. The relative error of ≤5 % was considered significant in the method specificity study. The lead concentration mean for the cyclists was 3.79 μg L(-1) in urine samples. As a result, the proposed method is a robust technique to quantify lead concentrations higher than 11.6 ng L(-1) in urine samples.

  12. Use of thermal lensing spectrophotometry (TLS) for the study of mononuclear hydrolysis of uranium(IV)

    SciTech Connect

    Grenthe, I.; Bidoglio, G.; Omenetto, N.

    1989-01-11

    The possibility of using thermal lensing spectrophotometry (TLS) for the quantitative determination of chemical equilibria in very dilute (/approx/ 10/sup /minus/5/ M) aqueous solution has been explored. The hyrolysis of uranium(IV) has been used as a test case. TLS turned out to be a convenient, precise, and rapid method to obtain information about the mononuclear hydrolysis, information that is difficult to obtain with more traditional solution chemical methods. The TLS data were obtained at 25/degree/C in the concentration range of 0 /le/ /minus/log (H/sup +/) /le/ 2.8 by using a 3 M (Na,H)ClO/sub 4/ ionic medium. The data were described with the following chemical model: U/sup 4+/ + H/sub 2/O /r equilibrium/ UOH/sup 3+/ + H/sup +/, log */beta//sub 1/ = -1.65 /plus minus/ 0.05; U/sup 4+/ + 2H/sub 2/O /r equilibrium/ U(OH)/sub 2//sup 2+/ + 2H/sup +/, log */beta//sub 2/ < -4.5. Apart from its higher sensitivity, the TLS method has the same characteristics as ordinary spectrophotometric methods. The experimental results of this study and previous literature information were interpreted by using the specific ion interaction theory to give log */beta//degree//sub 1/ = -0.51 /plus minus/ 0.03 (log */beta//degree//sub 1/ is the equilibrium constant at zero ionic strength) and /Delta//epsilon/ is the ion interaction term /Delta//epsilon/ = /epsilon/(UOH/sup 3+/, ClO/sub 4//sup /minus//) + /epsilon/(H/sup +/, ClO/sub 4//sup /minus//) /minus/ /epsilon/(U/sup 4+/, ClO/sub 4//sup /minus//). 16 refs., 5 figs..

  13. Determination of crystal violet in water by direct solid phase spectrophotometry after rotating disk sorptive extraction.

    PubMed

    Manzo, Valentina; Navarro, Orielle; Honda, Luis; Sánchez, Karen; Inés Toral, M; Richter, Pablo

    2013-03-15

    The microextraction of crystal violet (CV) from water samples into polydimethylsiloxane (PDMS) using the rotating disk sorptive extraction (RDSE) technique was performed. The extracting device was a small Teflon disk that had an embedded miniature magnetic stirring bar and a PDMS (560 μL) film attached to one side of the disk using double-sided tape. The extraction involves a preconcentration of CV into the PDMS, where the analyte is then directly quantified using solid phase spectrophotometry at 600 nm. Different chemical and extraction device-related variables were studied to achieve the best sensitivity for the determination. The optimum extraction was performed at pH 14 because under this condition, CV is transformed to the neutral and colorless species carbinol, which can be quantitatively transferred to the PDMS phase. Although the colorless species is the chemical form extracted in the PDMS, an intense violet coloration appeared in the phase because the -OH bond in the carbinol molecule is weakened through the formation of hydrogen bonds with the oxygen atoms of the PDMS, allowing the resonance between the three benzene rings to compensate for the charge deficit on the central carbon atom of the molecule. The accuracy and precision of the method were evaluated in river water samples spiked with 10 and 30 μg L(-1) of CV, yielding a relative standard deviation of 6.2% and 8.4% and a recovery of 98.4% and 99.4%, respectively. The method detection limit was 1.8 μg L(-1) and the limit of quantification was 5.4 μg L(-1), which can be decreased if the sample volume is increased.

  14. FTIR (Fourier Transform Infrared) spectrophotometry for thin film monitors: Computer and equipment integration for enhanced capabilities

    NASA Astrophysics Data System (ADS)

    Cox, J. N.; Sedayao, J.; Shergill, G.; Villasol, R.; Haaland, D. M.

    Fourier transform infrared spectrophotometry (FTIR) is a valuable technique for monitoring thin films used in semiconductor device manufacture. Determinations of the constituent contents in borophosphosilicate (BPSG), phosphosilicate (PSG), silicon oxynitride (SiON:H,OH), and spin-on-glass (SOG) thin films are a few applications. Due to the nature of the technique, FTIR instrumentation is one of the most extensively computer-dependent pieces of equipment that is likely to be found in a microelectronics plant. In the role of fab monitor or reactor characterization tool, FTIR instruments can rapidly generate large amounts of data. By linking a local FTIR data station to a remote minicomputer its capabilities are greatly improved. We discuss three caused of enhancement. First, the FTIR in the fab area communicates and interacts in real time with the minicomputer: transferring data segments to it, instructing it to perform sophisticated processing, and returning the result to the operator in the fab. Characterizations of PSG thin films by this approach are discussed. Second, the spectra of large numbers of samples are processed locally. The large database is then transmitted to the minicomputer for study by statistical/graphics software. Results of CVD-reactor spatial profiling experiments for plasma SiON are presented. Third, processing of calibration spectra is performed on the minicomputer to optimize the accuracy and precision of a Partial Least Squares analysis mode. This model is then transferred to the data station in the fab. The analysis of BPSG thin films is discussed in this regard. The prospects for fully automated at-line monitoring and for real-time, in-situ monitoring will be discussed.

  15. Estimation of nitrite in source-separated nitrified urine with UV spectrophotometry.

    PubMed

    Mašić, Alma; Santos, Ana T L; Etter, Bastian; Udert, Kai M; Villez, Kris

    2015-11-15

    Monitoring of nitrite is essential for an immediate response and prevention of irreversible failure of decentralized biological urine nitrification reactors. Although a few sensors are available for nitrite measurement, none of them are suitable for applications in which both nitrite and nitrate are present in very high concentrations. Such is the case in collected source-separated urine, stabilized by nitrification for long-term storage. Ultraviolet (UV) spectrophotometry in combination with chemometrics is a promising option for monitoring of nitrite. In this study, an immersible in situ UV sensor is investigated for the first time so to establish a relationship between UV absorbance spectra and nitrite concentrations in nitrified urine. The study focuses on the effects of suspended particles and saturation on the absorbance spectra and the chemometric model performance. Detailed analysis indicates that suspended particles in nitrified urine have a negligible effect on nitrite estimation, concluding that sample filtration is not necessary as pretreatment. In contrast, saturation due to very high concentrations affects the model performance severely, suggesting dilution as an essential sample preparation step. However, this can also be mitigated by simple removal of the saturated, lower end of the UV absorbance spectra, and extraction of information from the secondary, weaker nitrite absorbance peak. This approach allows for estimation of nitrite with a simple chemometric model and without sample dilution. These results are promising for a practical application of the UV sensor as an in situ nitrite measurement in a urine nitrification reactor given the exceptional quality of the nitrite estimates in comparison to previous studies.

  16. FTIR (Fourier transform infrared) spectrophotometry for thin film monitors: Computer and equipment integration for enhanced capabilities

    SciTech Connect

    Cox, J.N.; Sedayao, J.; Shergill, G.; Villasol, R. ); Haaland, D.M. )

    1990-01-01

    Fourier transform infrared spectrophotometry (FTIR) is a valuable technique for monitoring thin films used in semiconductor device manufacture. Determinations of the constituent contents in borophosphosilicate (BPSG), phosphosilicate (PSG), silicon oxynitride (SiON:H,OH), and spin-on-glass (SOG) thin films are a few applications. Due to the nature of the technique, FTIR instrumentation is one of the most extensively computer-dependent pieces of equipment that is likely to be found in a microelectronics plant. In the role of fab monitor or reactor characterization tool, FTIR instruments can rapidly generate large amounts of data. By linking a local FTIR data station to a remote minicomputer its capabilities are greatly improved. We discuss three caused of enhancement. First, the FTIR in the fab area communicates and interacts in real time with the minicomputer: transferring data segments to it, instructing it to perform sophisticated processing, and returning the result to the operator in the fab. Characterizations of PSG thin films by this approach are discussed. Second, the spectra of large numbers of samples are processed locally. The large database is then transmitted to the minicomputer for study by statistical/graphics software. Results of CVD-reactor spatial profiling experiments for plasma SiON are presented. Third, processing of calibration spectra is performed on the minicomputer to optimize the accuracy and precision of a Partial Least Squares'' analysis mode. This model is then transferred to the data station in the fab. The analysis of BPSG thin films is discussed in this regard. The prospects for fully automated at-line monitoring and for real-time, in-situ monitoring will be discussed. 10 refs., 4 figs.

  17. Corrosion Problems in Absorption Chillers

    ERIC Educational Resources Information Center

    Stetson, Bruce

    1978-01-01

    Absorption chillers use a lithium bromide solution as the medium of absorption and water as the refrigerant. Discussed are corrosion and related problems, tests and remedies, and cleaning procedures. (Author/MLF)

  18. Hey Teacher, Your Personality's Showing!

    ERIC Educational Resources Information Center

    Paulsen, James R.

    1977-01-01

    A study of 30 fourth, fifth, and sixth grade teachers and 300 of their students showed that a teacher's age, sex, and years of experience did not relate to students' mathematics achievement, but that more effective teachers showed greater "freedom from defensive behavior" than did less effective teachers. (DT)

  19. Planning a Successful Tech Show

    ERIC Educational Resources Information Center

    Nikirk, Martin

    2011-01-01

    Tech shows are a great way to introduce prospective students, parents, and local business and industry to a technology and engineering or career and technical education program. In addition to showcasing instructional programs, a tech show allows students to demonstrate their professionalism and skills, practice public presentations, and interact…

  20. The saturable absorption and reverse saturable absorption properties of Cu doped zinc oxide thin films

    NASA Astrophysics Data System (ADS)

    Yao, Cheng-Bao; Wen, Xin; Li, Qiang-Hua; Yan, Xiao-Yan; Li, Jin; Zhang, Ke-Xin; Sun, Wen-Jun; Bai, Li-Na; Yang, Shou-Bin

    2017-03-01

    We present the structure and nonlinear absorption (NLA) properties of Cu-doped ZnO (CZO) films prepared by magnetron sputtering. The films were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results show that the CZO films can maintain a wurtzite structure. Furthermore, the open-aperture (OA) Z-scan measurements of the film were carried out by nanosecond laser pulse. A transition from saturable absorption (SA) to reverse saturable absorption (RSA) was observed as the excitation intensity increasing. With good excellent nonlinear optical coefficient, the samples were expected to be the potential applications in optical devices.

  1. Determination of copper in tap water using solid-phase spectrophotometry

    NASA Technical Reports Server (NTRS)

    Hill, Carol M.; Street, Kenneth W.; Philipp, Warren H.; Tanner, Stephen P.

    1994-01-01

    A new application of ion exchange films is presented. The films are used in a simple analytical method of directly determining low concentrations of Cu(2+) in aqueous solutions, in particular, drinking water. The basis for this new test method is the color and absorption intensity of the ion when adsorbed onto the film. The film takes on the characteristic color of the adsorbed cation, which is concentrated on the film by many orders of magnitude. The linear relationship between absorbance (corrected for variations in film thickness) and solution concentration makes the determinations possible. These determinations agree well with flame atomic absorption determinations.

  2. Spectrophotometry of Pluto-Charon mutual events - Individual spectra of Pluto and Charon

    NASA Technical Reports Server (NTRS)

    Sawyer, S. R.; Barker, E. S.; Cochran, A. L.; Cochran, W. D.

    1987-01-01

    Time-resolved spectra of the March 3 and April 4, 1987 mutual events of Pluto and Charon, obtained with spectral coverage from 5500 to 10,000 A with 25-A spectral resolution, are discussed. Charon has a featureless reflectance spectrum, with no evidence of methane absorption. Charon's reflectance appears neutral in color and corresponds to a geometric albedo of about 0.37 at 6000 A. The Pluto reflectance spectrum displays methane absorption bands at 7300, 7900, 8400, 8600, and 8900 A and is red in color, with a geometric albedo of about 0.56 at 6000 A.

  3. Satellite Animation Shows California Storms

    NASA Video Gallery

    This animation of visible and infrared imagery from NOAA's GOES-West satellite shows a series of moisture-laden storms affecting California from Jan. 6 through Jan. 9, 2017. TRT: 00:36 Credit: NASA...

  4. Satellite Movie Shows Erika Dissipate

    NASA Video Gallery

    This animation of visible and infrared imagery from NOAA's GOES-West satellite from Aug. 27 to 29 shows Tropical Storm Erika move through the Eastern Caribbean Sea and dissipate near eastern Cuba. ...

  5. Ultraviolet absorption hygrometer

    DOEpatents

    Gersh, Michael E.; Bien, Fritz; Bernstein, Lawrence S.

    1986-01-01

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined.

  6. Ultraviolet absorption hygrometer

    DOEpatents

    Gersh, M.E.; Bien, F.; Bernstein, L.S.

    1986-12-09

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined. 5 figs.

  7. Modular total absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Karny, M.; Rykaczewski, K. P.; Fijałkowska, A.; Rasco, B. C.; Wolińska-Cichocka, M.; Grzywacz, R. K.; Goetz, K. C.; Miller, D.; Zganjar, E. F.

    2016-11-01

    The design and performance of the Modular Total Absorption Spectrometer built and commissioned at the Oak Ridge National Laboratory is presented. The active volume of the detector is approximately one ton of NaI(Tl), which results in very high full γ energy peak efficiency of 71% at 6 MeV and nearly flat efficiency of around 81.5% for low energy γ-rays between 300 keV and 1 MeV. In addition to the high peak efficiency, the modular construction of the detector permits the use of a γ-coincidence technique in data analysis as well as β-delayed neutron observation.

  8. Absorption in Extended Inhomogeneous Clouds

    NASA Technical Reports Server (NTRS)

    Joiner, Joanna; Vasilkov, Alexander; Spurr, Robert; Bhartia, P. K.; Krotkov, Nick

    2008-01-01

    The launch of several different sensors, including CloudSat, into the A-train constellation of satellites allows us for the first time to compute absorption that can occur in realistic vertically inhomogeneous clouds including multiple cloud decks. CloudSat data show that these situations are common. Therefore, understanding vertically inhomogeneous clouds is important from both climate and satellite atmospheric composition remote sensing perspectives. Satellite passive sensors that operate from the near IR to the UV often rely on radiative cloud pressures derived from absorption in oxygen bands (A, B, gamma, or O2-O2 bands) or from rotational-Raman scattering in order to retrieve information about atmospheric trace gases. The radiative cloud pressure is distinct from the physical cloud top derived from thermal infrared measurements. Therefore, the combination of information from different passive sensors yields some information about the cloud vertical profile. When either or both the clouds or atmospheric absorbers (trace gases and aerosols) are vertically inhomogeneous, the use of an effective cloud pressure derived from these approaches may lead to errors. Here, we focus on several scenarios (deep convective clouds and distinct two layer clouds) based on realistic cloud optical depth vertical profiles derived from the CloudSatfMODIS combination. We focus on implications for trace-gas column amount retrievals (specifically ozone and NO2) and derived surface UV irradiance from the Ozone Monitoring Instrument (OMI) on the Atrain Aura platform.

  9. IUE spectrophotometry of the hot helium-rich PG1159 DO degenerates

    NASA Astrophysics Data System (ADS)

    Sion, E. M.; Liebert, J.; Starrfield, S.; Wesemael, F.

    1984-12-01

    The PG1159 degenerates represent the hottest spectroscopic subgroup of DO stars. Their optical spectra are characterized by broad HeII (lambda 4686) absorption and several transitions of CIV, NIII and CIII. High resolution MMT scans reveal central emission reversals. The discovery of complex, non-radial pulsations in four members of the class underscores the need for accurate temperatures, gravities and abundances for these object. Low resolution IUE spectra of four PG1159 stars, PG1151-029, PG1424+535, PG1520+525 were obtained, as well as an additional image of PG1159-035 and an optical ultraviolet spectrum of PG2131+066. IUE (SWP) spectra suggest the presence of numerous metallic absorption features of CIV (lambda 1550), NV (lambda 1240) and a few unidentified features. The metal absorption lines and HEII (lambda 1640) have equivalent widths of a few angstroms. IUE/optical energy distributions are considered. Tentative identifications of CIV absorptions and possibly, weak OVI features in optical ultraviolet reticon spectra suggest a probable link to the subluminous Wolf-Rayet OV5 I planetary nuclei. The PG1159 DO degenerates are the hottest known (Te 100,000K), high gravity (log g 7 ) objects.

  10. Extraction and preconcentration of copper from water, soils, lubricating oils and plant materials and its subsequent determination by atomic-absorption spectrophotometry.

    PubMed

    Ejaz, M; Shamus-Zuha; Dil, W; Akhtar, A; Chaudhri, S A

    1981-07-01

    The extraction and preconcentration of the cupric thiocyanate complex with 4-(5-nonyl)pyridine in benzene is possible from neutral or up to 2M HCl, 0.5M HNO(3) or 0.25M H(2)SO(4) solutions. The method has considerable advantages over previously recommended extraction procedures because of selectivity, completeness of extraction in a single operation, short contact period, minimum amount of complexing agents needed and wide tolerance to various solution parameters. The complex formed from as little as 1 mug of copper can be extracted quantitatively into 1 ml of the organic phase from 500 ml of natural water. An extraction method is described which in combination with AAS can be used to determine copper in water, soils, fresh and used lubricating oils and plant-ash solutions down to the ng/ml or ng/g level.

  11. Simultaneous determination of mercury and organic carbon in sediment and soils using a direct mercury analyzer based on thermal decomposition-atomic absorption spectrophotometry.

    PubMed

    Chen, Jingjing; Chakravarty, Pragya; Davidson, Gregg R; Wren, Daniel G; Locke, Martin A; Zhou, Ying; Brown, Garry; Cizdziel, James V

    2015-04-29

    The purpose of this work was to study the feasibility of using a direct mercury analyzer (DMA) to simultaneously determine mercury (Hg) and organic matter content in sediment and soils. Organic carbon was estimated by re-weighing the sample boats post analysis to obtain loss-on-ignition (LOI) data. The DMA-LOI results were statistically similar (p<0.05) to the conventional muffle furnace approach. A regression equation was developed to convert DMA-LOI data to total organic carbon (TOC), which varied between 0.2% and 13.0%. Thus, mercury analyzers based on combustion can provide accurate estimates of organic carbon content in non-calcareous sediment and soils; however, weight gain from moisture (post-analysis), measurement uncertainty, and sample representativeness should all be taken into account. Sediment cores from seasonal wetland and open water areas from six oxbow lakes in the Mississippi River alluvial flood plain were analyzed. Wetland sediments generally had higher levels of Hg than open water areas owing to a greater fraction of fine particles and higher levels of organic matter. Annual loading of Hg in open water areas was estimated at 4.3, 13.4, 19.2, 20.7, 129, and 135 ng cm(-2) yr(-1) for Beasley, Roundaway, Hampton, Washington, Wolf and Sky Lakes, respectively. Generally, the interval with the highest Hg flux was dated to the 1960s and 1970s.

  12. National Orange Show Photovoltaic Demonstration

    SciTech Connect

    Dan Jimenez Sheri Raborn, CPA; Tom Baker

    2008-03-31

    National Orange Show Photovoltaic Demonstration created a 400KW Photovoltaic self-generation plant at the National Orange Show Events Center (NOS). The NOS owns a 120-acre state fairground where it operates an events center and produces an annual citrus fair known as the Orange Show. The NOS governing board wanted to employ cost-saving programs for annual energy expenses. It is hoped the Photovoltaic program will result in overall savings for the NOS, help reduce the State's energy demands as relating to electrical power consumption, improve quality of life within the affected grid area as well as increase the energy efficiency of buildings at our venue. In addition, the potential to reduce operational expenses would have a tremendous effect on the ability of the NOS to service its community.

  13. Use of reflectance spectrophotometry and colorimetry in a general linear model for the determination of the age of bruises.

    PubMed

    Hughes, Vanessa K; Langlois, Neil E I

    2010-12-01

    Bruises can have medicolegal significance such that the age of a bruise may be an important issue. This study sought to determine if colorimetry or reflectance spectrophotometry could be employed to objectively estimate the age of bruises. Based on a previously described method, reflectance spectrophotometric scans were obtained from bruises using a Cary 100 Bio spectrophotometer fitted with a fibre-optic reflectance probe. Measurements were taken from the bruise and a control area. Software was used to calculate the first derivative at 490 and 480 nm; the proportion of oxygenated hemoglobin was calculated using an isobestic point method and a software application converted the scan data into colorimetry data. In addition, data on factors that might be associated with the determination of the age of a bruise: subject age, subject sex, degree of trauma, bruise size, skin color, body build, and depth of bruise were recorded. From 147 subjects, 233 reflectance spectrophotometry scans were obtained for analysis. The age of the bruises ranged from 0.5 to 231.5 h. A General Linear Model analysis method was used. This revealed that colorimetric measurement of the yellowness of a bruise accounted for 13% of the bruise age. By incorporation of the other recorded data (as above), yellowness could predict up to 32% of the age of a bruise-implying that 68% of the variation was dependent on other factors. However, critical appraisal of the model revealed that the colorimetry method of determining the age of a bruise was affected by skin tone and required a measure of the proportion of oxygenated hemoglobin, which is obtained by spectrophotometric methods. Using spectrophotometry, the first derivative at 490 nm alone accounted for 18% of the bruise age estimate. When additional factors (subject sex, bruise depth and oxygenation of hemoglobin) were included in the General Linear Model this increased to 31%-implying that 69% of the variation was dependent on other factors. This

  14. Determination of vitamin B6 by means of differential spectrophotometry in pharmaceutical preparations in the presence of magnesium compounds.

    PubMed

    Muszalska, Izabela; Puchalska, Marta; Sobczak, Agnieszka

    2011-01-01

    The content of pyridoxine hydrochloride in two-component pharmaceutical preparations containing various magnesium compounds was examined. The UV differentiation spectrophotometry was devised and compared with the reference method of high performance liquid chromatography (HPLC). The analysis of the absorbance spectra (A) and its first (D1) and second (D2) derivatives made it possible to establish the appropriate analytical wavelengths (A: 290 nm; D1: 302 nm; D2: 308 nm). It was proved that spectrum differentiation significantly corrects errors resulting from overlapping background especially when the magnesium hydroaspartate, lactate or magnesium lactogluconate is present together with vitamin B6.

  15. [Quantitative determination of the protein content of milk by ultraviolet spectrophotometry. 3. Determination of proteins in preserved milk samples].

    PubMed

    Reichardt, W; Schüler, E; Sieber, L; Schüler, E

    1987-01-01

    It is reported upon the results of the quantitative estimation of protein content from preserved milk by means of ultraviolet spectrophotometry. In addition to the preservation by boric acid, bronopol, copper sulphate, potassium dichromate and ammonium peroxodisulphate storage at temperatures below 0 degrees C and freeze drying were tested. Besides bronopol and copper sulphate especially physical preservation methods proves fit for the protein estimation by measurements of absorbance at 210 nm, 235 and 280 nm or 210 and 220 nm. It is recommended to use solutions and filters of quartz with evaluated absorbance in daily calibrating of the spectrophotometer.

  16. Phyllodes tumor showing intraductal growth.

    PubMed

    Makidono, Akari; Tsunoda, Hiroko; Mori, Miki; Yagata, Hiroshi; Onoda, Yui; Kikuchi, Mari; Nozaki, Taiki; Saida, Yukihisa; Nakamura, Seigo; Suzuki, Koyu

    2013-07-01

    Phyllodes tumor of the breast is a rare fibroepithelial lesion and particularly uncommon in adolescent girls. It is thought to arise from the periductal rather than intralobular stroma. Usually, it is seen as a well-defined mass. Phyllodes tumor showing intraductal growth is extremely rare. Here we report a girl who has a phyllodes tumor with intraductal growth.

  17. [Alleviated affect of exogenous CaCl2 on the growth, antioxidative enzyme activities and cadmium absorption efficiency of Wedelia trilobata hairy roots under cadmium stress].

    PubMed

    Shi, Heping; Wang, Yunling; Tsang, PoKeung Eric; Chan, LeeWah Andrew

    2012-06-01

    In order to study the physiological mechanism of exogenous calcium on the toxicity of heavy metal cadmium (Cd) to Wedelia trilobata hairy roots, the effects of Cd alone, and in combination with different concentrations of Ca on growth, contents of soluble protein and malondialdehyde (MDA), activities of superoxide dismutase (SOD) and peroxidase (POD), Cd2+ absorption in W. trilobata hairy roots were investigated. Cd concentrations lower than 50 micromol/L enhanced the growth of hairy roots, while concentrations higher than 100 micromol/L inhibited growth, making the branched roots short and small, and also turning the root tips brown, even black. In comparison with the control (0 micromol/L Cd), the soluble protein content in hairy roots was found to increase when cultured with 10-50 micromol/L Cd, and decrease when exposed to a cadmium concentration higher than 100 micromol/L Cd. In addition, the activities of POD and SOD activity and MDA content were significantly higher than the control. Compared to the control (hairy roots cultured without 10-30 mmol/L Ca), 100 micromol/L Cd or 300 micromol/L Cd in combination with 10-30 mmol/L Ca resulted in increased growth, causing the main root and secondary roots thicker and also an increase in soluble protein content. On the contrary, MDA content and POD and SOD activities decreased. Quantitative analysis by Atomic Absorption Spectrophotometry showed that W. trilobata hairy roots can absorb and adsorb heavy metal Cd in the ionic form of Cd2+. The maximum content of Cd2+ absorbed by the hairy roots was obtained with a concentration 100 micromol/L Cd2+ while that of Cd2+ adsorbed by hairy roots was achieved with a concentration of 300 micromol/L Cd2+. The exogenous addition of 10-30 mmol/L Ca2+ was found to reduce the absorption, adsorption of Cd2+ and the toxicity of Cd significantly. This reduction in toxicity was caused by the reduction in the absorption of Cd and decreasing the lipid peroxidation through regulating the

  18. Water-related absorption in fibrous diamonds

    NASA Astrophysics Data System (ADS)

    Zedgenizov, D. A.; Shiryaev, A. A.; Kagi, H.; Navon, O.

    2003-04-01

    Cubic and coated diamonds from several localities (Brasil, Canada, Yakutia) were investigated using spectroscopic techniques. Special emphasis was put on investigation of water-related features of transmission Infra-red and Raman spectra. Presence of molecular water is inferred from broad absorption bands in IR at 3420 and 1640 cm-1. These bands were observed in many of the investigated samples. It is likely that molecular water is present in microinclusions in liquid state, since no clear indications of solid H_2O (ice VI-VII, Kagi et al., 2000) were found. Comparison of absorption by HOH and OH vibrations shows that diamonds can be separated into two principal groups: those containing liquid water (direct proportionality of OH and HOH absorption) and those with stronger absorption by OH group. Fraction of diamonds in every group depends on their provenance. There might be positive correlation between internal pressure in microinclusions (determined using quartz barometer, Navon et al., 1988) and affiliation with diamonds containing liquid water. In many cases absorption by HOH vibration is considerably lower than absorption by hydroxyl (OH) group. This may be explained if OH groups are partially present in mineral and/or melt inclusions. This hypothesis is supported by following fact: in diamonds with strong absorption by silicates and other minerals shape and position of the OH band differs from that in diamonds with low absorption by minerals. Moreover, in Raman spectra of individual inclusions sometimes the broad band at 3100 cm-1 is observed. This band is OH-related. In some samples water distribution is not homogeneous. Central part of the diamond usually contains more water than outer parts, but this is not a general rule for all the samples. Water absorption usually correlated with absorption of other components (carbonates, silicates and others). At that fibrous diamonds with relatively high content of silicates are characterized by molecular water. OH

  19. Low-Absorption Liquid Crystals for Infrared Beam Steering

    DTIC Science & Technology

    2014-10-17

    goals are: ri~0.2 (at-tSilri),*? (at 1 kHz), and absorption coefficient B 5/cm. 15. SUBJECT TERMS Low absorption, MWIR, chlorinated liquid crystals...spectral region of interest by deuteration, fluorination and chlorination ; 2) Employing thin cell gap by choosing a high birefringence liquid crystal...mixture. First, we synthesized several chlorinated terphenyls and made a eutectic mixture showing a low absorption window in the region of 4-5|a.m

  20. Calculation of laser absorption by metal powders in additive manufacturing.

    PubMed

    Boley, C D; Khairallah, S A; Rubenchik, A M

    2015-03-20

    We have calculated the absorption of laser light by a powder of metal spheres, typical of the powder employed in laser powder-bed fusion additive manufacturing. Using ray-trace simulations, we show that the absorption is significantly larger than its value for normal incidence on a flat surface, due to multiple scattering. We investigate the dependence of absorption on powder content (material, size distribution, and geometry) and on beam size.

  1. Determination of lamivudine and stavudine in pharmaceutical preparations using chemometrics-assisted spectrophotometry.

    PubMed

    Mohamed, Abd El-Maaboud I; Mikre, Workalemahu

    2009-10-01

    A simple chemometrics-assisted spectrophotometric method for the simultaneous determination of lamivudine and stavudine in pharmaceutical tablets is described. The UV absorption spectra of the studied drugs, in the range of 200-310 nm, showed a considerable degree of spectral overlapping ([Di ](0.5) = 94.9%). Resolution of the mixture has been accomplished by using classical least-squares regression analysis (CLS) and principle components regression analysis methods (PCR). Beer's law was obeyed for both drugs in the general concentration ranges of 2-12 and 3-15 μg ml(-1) for lamivudine and stavudine, respectively. The proposed methods were successfully applied for the determination of the two drugs in laboratory prepared mixtures. The overall recoveries percent were found 98.58 ± 1.53-101.30 ± 1.35 (CLS) and 98.62 ± 1.65-101.13 ± 1.04 (PCR) for lamivudine and 98.43 ± 1.62-99.42 ± 1.55 (CLS) and 98.23 ± 1.97-101.20 ± 1.79 (PCR) for stavudine, respectively. The commercial tablets percentage content was found 98.10 ± 2.5-102.47 ± 2.94 (CLS) and 99.12 ± 1.71-100.92 ± 1.54 (PCR) for lamivudine and 96.00 ± 2.94-98.17 ± 1.72 (CLS) and 97.40 ± 1.55-97.80 ± 1.92 (PCR) for stavudine, respectively. Good percentage recoveries and proper statistical data obtained with both the laboratory prepared mixtures and the commercial tablets proved the suitability and efficiency of the proposed procedures for routine analysis and quality control purposes with quite satisfactory precision. A comparison of the obtained results from CLS and PCR were also performed with those obtained from reported method. The obtained F- and t-values obtained indicating no significant differences between the results of the proposed and reported methods.

  2. Magic Carpet Shows Its Colors

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The upper left image in this display is from the panoramic camera on the Mars Exploration Rover Spirit, showing the 'Magic Carpet' region near the rover at Gusev Crater, Mars, on Sol 7, the seventh martian day of its journey (Jan. 10, 2004). The lower image, also from the panoramic camera, is a monochrome (single filter) image of a rock in the 'Magic Carpet' area. Note that colored portions of the rock correlate with extracted spectra shown in the plot to the side. Four different types of materials are shown: the rock itself, the soil in front of the rock, some brighter soil on top of the rock, and some dust that has collected in small recesses on the rock face ('spots'). Each color on the spectra matches a line on the graph, showing how the panoramic camera's different colored filters are used to broadly assess the varying mineral compositions of martian rocks and soils.

  3. New methods for determination of cinnarizine in mixture with piracetam by spectrodensitometry, spectrophotometry, and liquid chromatography.

    PubMed

    Metwally, Fadia H; Elzeany, B A; Darwish, H W

    2005-01-01

    Four new methods were developed and validated for the determination of cinnarizine HCl in its binary mixture with piracetam in pure and pharmaceutical preparations. The first one was a densitometric analysis that provides a simple and rapid method for the separation and quantification of cinnarizine HCI. The method depends on the quantitative densitometric evaluation of thin-layer chromatograms of cinnarizine HCI at 252 nm over concentration range of 1-6 microg/spot, with a mean accuracy of 100.05 +/- 0.91%. The second method was determination of the drug using a colorimetric method that utilizes the reaction of 3-methyl-benzothiazolin-2-one in the presence of FeCl3 as an oxidant. The green color of the resulting product was measured at 630 nm over concentration range 10-40 microg/mL, with a mean accuracy of 100.10 +/- 1.13%. The third method was a direct spectrophotometric determination of cinnarizine HCI at 252 nm over the concentration range 7-20 microg/mL, while piracetam was determined by derivative ratio spectrophotometry at 221.6 nm over concentration range 5-30 microg/mL, with a mean accuracy of 100.14 +/- 0.79 and 100.26 +/- 1.24% for cinnarizine HCI and piracetam, respectively. The last method was a liquid chromatography analysis of both cinnarizine HCI and piracetam, depending on quantitative evaluation of chromatograms of cinnarizine HCI and piracetam at 252 and 212 nm, respectively, over the concentration range 10-200 microg/mL for cinnarizine HCI and 20-500 microg/mL for piracetam, with a mean accuracy of 100.03 +/- 0.89 and 100.40 +/- 0.94% for cinnarizine HCI and piracetam, respectively. The proposed procedures were checked using laboratory-prepared mixtures and successfully applied for the analysis of their pharmaceutical preparations. The validity of the proposed procedures was further assessed by applying the standard addition technique. Recoveries were quantitative, and the results obtained agreed with those obtained by other reported methods.

  4. Quantifying the Magnitude of Anomalous Solar Absorption

    SciTech Connect

    Ackerman, Thomas P.; Flynn, Donna M.; Marchand, Roger T.

    2003-05-16

    The data set from ARESE II, sponsored by the Atmospheric Radiation Measurement Program, provides a unique opportunity to understand solar absorption in the atmosphere because of the combination of three sets of broadband solar radiometers mounted on the Twin Otter aircraft and the ground based instruments at the ARM Southern Great Plains facility. In this study, we analyze the measurements taken on two clear sky days and three cloudy days and model the solar radiative transfer in each case with two different models. On the two clear days, the calculated and measured column absorptions agree to better than 10 Wm-2, which is about 10% of the total column absorption. Because both the model fluxes and the individual radiometer measurements are accurate to no better than 10 Wm-2, we conclude that the models and measurements are essentially in agreement. For the three cloudy days, the model calculations agree very well with each other and on two of the three days agree with the measurements to 20 Wm-2 or less out of a total column absorption of more than 200 Wm-2, which is again agreement at better than 10%. On the third day, the model and measurements agree to either 8% or 14% depending on which value of surface albedo is used. Differences exceeding 10% represent a significant absorption difference between model and observations. In addition to the uncertainty in absorption due to surface albedo, we show that including aerosol with an optical depth similar to that found on clear days can reduce the difference between model and measurement by 5% or more. Thus, we conclude that the ARESE II results are incompatible with previous studies reporting extreme anomalous absorption and can be modeled with our current understanding of radiative transfer.

  5. Determination of tributyltin in tissues and sediments by graphite furnace atomic absorption spectrometry

    SciTech Connect

    Stephenson, M.D.; Smith, D.R.

    1988-04-01

    A method for the determination of tributyltin (TBT) in tissue and sediments has been developed for environmental samples. The technique involves extraction with methylene chloride and isolation of TBT from mono- and dibutyltin with a sodium hydroxide wash. The TBT is then back extracted and converted to elemental Sn with nitric acid. Analysis is by Zeeman graphite furnace atomic absorption spectrophotometry. Recoveries of spiked samples were between 99% and 111% for mussel and fish tissues and 72% and 99% for various sediments. The limit of quantification was 0.0025 ..mu..g/g for tissue (on a wet weight basis). This technique was developed in response to their need to process large numbers of environmental samples with a minimum time investment.

  6. An atomic-absorption method for the determination of gold in large samples of geologic materials

    USGS Publications Warehouse

    VanSickle, Gordon H.; Lakin, Hubert William

    1968-01-01

    A laboratory method for the determination of gold in large (100-gram) samples has been developed for use in the study of the gold content of placer deposits and of trace amounts of gold in other geologic materials. In this method the sample is digested with bromine and ethyl ether, the gold is extracted into methyl isobutyl ketone, and the determination is made by atomicabsorption spectrophotometry. The lower limit of detection is 0.005 part per million in the sample. The few data obtained so far by this method agree favorably with those obtained by assay and by other atomic-absorption methods. About 25 determinations can be made per man-day.

  7. Determination of calcium, magnesium and zinc in unused lubricating oils by atomic absorption spectroscopy.

    PubMed

    Udoh, A P

    1995-12-01

    Varying concentrations of lanthanum and strontium were added to solutions of ashed unused lubricating oils for the determination of calcium, magnesium and zinc content using flame atomic absorption spectrophotometry. At least 3000 mug g(-1) of lanthanum or strontium was required to completely overcome the interference of the phosphate ion, PO(3-)(4), and give peak values for calcium. The presence of lanthanum or strontium did not cause an appreciable increase in the amount of magnesium and zinc obtained from the analyses. The method is fast and reproducible, and the coefficients of variation calculated for the elements using one of the samples were 1.6% for calcium, 3.5% for magnesium and 0.2% for zinc. Results obtained by this method were better than those obtained by other methods for the same samples.

  8. Quantum-enhanced absorption refrigerators

    PubMed Central

    Correa, Luis A.; Palao, José P.; Alonso, Daniel; Adesso, Gerardo

    2014-01-01

    Thermodynamics is a branch of science blessed by an unparalleled combination of generality of scope and formal simplicity. Based on few natural assumptions together with the four laws, it sets the boundaries between possible and impossible in macroscopic aggregates of matter. This triggered groundbreaking achievements in physics, chemistry and engineering over the last two centuries. Close analogues of those fundamental laws are now being established at the level of individual quantum systems, thus placing limits on the operation of quantum-mechanical devices. Here we study quantum absorption refrigerators, which are driven by heat rather than external work. We establish thermodynamic performance bounds for these machines and investigate their quantum origin. We also show how those bounds may be pushed beyond what is classically achievable, by suitably tailoring the environmental fluctuations via quantum reservoir engineering techniques. Such superefficient quantum-enhanced cooling realises a promising step towards the technological exploitation of autonomous quantum refrigerators. PMID:24492860

  9. Quantum-enhanced absorption refrigerators

    NASA Astrophysics Data System (ADS)

    Correa, Luis A.; Palao, José P.; Alonso, Daniel; Adesso, Gerardo

    2014-02-01

    Thermodynamics is a branch of science blessed by an unparalleled combination of generality of scope and formal simplicity. Based on few natural assumptions together with the four laws, it sets the boundaries between possible and impossible in macroscopic aggregates of matter. This triggered groundbreaking achievements in physics, chemistry and engineering over the last two centuries. Close analogues of those fundamental laws are now being established at the level of individual quantum systems, thus placing limits on the operation of quantum-mechanical devices. Here we study quantum absorption refrigerators, which are driven by heat rather than external work. We establish thermodynamic performance bounds for these machines and investigate their quantum origin. We also show how those bounds may be pushed beyond what is classically achievable, by suitably tailoring the environmental fluctuations via quantum reservoir engineering techniques. Such superefficient quantum-enhanced cooling realises a promising step towards the technological exploitation of autonomous quantum refrigerators.

  10. Absorption enhancement and total absorption in a graphene-waveguide hybrid structure

    NASA Astrophysics Data System (ADS)

    Guo, Jun; Wu, Leiming; Dai, Xiaoyu; Xiang, Yuanjiang; Fan, Dianyuan

    2017-02-01

    We propose a graphene/planar waveguide hybrid structure, and demonstrate total absorption in the visible wavelength range by means of attenuated total reflectance. The excitation of planar waveguide mode, which has strong near field enhancement and increased light interaction length with graphene, plays a vital role in total absorption. We analyze the origin and physical insight of total absorption theoretically by using an approximated reflectance, and show how to design such hybrid structure numerically. Utilizing the tunability of doped graphene, we discuss the possible application in optical modulators. We also achieve broadband absorption enhancement in near-IR range by cascading multiple graphene-waveguide hybrid structures. We believe our results will be useful not only for potential applications in optical devices, but also for studying other two-dimension materials.

  11. "Medicine show." Alice in Doctorland.

    PubMed

    1987-01-01

    This is an excerpt from the script of a 1939 play provided to the Institute of Social Medicine and Community Health by the Library of Congress Federal Theater Project Collection at George Mason University Library, Fairfax, Virginia, pages 2-1-8 thru 2-1-14. The Federal Theatre Project (FTP) was part of the New Deal program for the arts 1935-1939. Funded by the Works Progress Administration (WPA) its goal was to employ theater professionals from the relief rolls. A number of FTP plays deal with aspects of medicine and public health. Pageants, puppet shows and documentary plays celebrated progress in medical science while examining social controversies in medical services and the public health movement. "Medicine Show" sharply contrasts technological wonders with social backwardness. The play was rehearsed by the FTP but never opened because funding ended. A revised version ran on Broadway in 1940. The preceding comments are adapted from an excellent, well-illustrated review of five of these plays by Barabara Melosh: "The New Deal's Federal Theatre Project," Medical Heritage, Vol. 2, No. 1 (Jan/Feb 1986), pp. 36-47.

  12. OH measurement by laser light absorption

    NASA Technical Reports Server (NTRS)

    Perner, D.

    1986-01-01

    Since the first attempt to measure atmospheric hydroxyl radicals by optical absorption in 1975 (Perner et al., 1976) this method has been continuously developed further and its major obstacles and limitations are known today. The laser beam needs to be expanded in order to reduce the beam divergence. At the same time the energy density of the laser beam which produces OH via ozone photolysis is reduced to such an extent that the self-produced OH concentration ranges well below the atmospheric value. Atmospheric absorptions should be observed over a wide spectral range so that not only the OH radicals are properly identified by several rotational lines but their absorption can be corrected for interfering absorptions from other air constituents as SO2, CH2O, CS2, etc., which can be identified in a wide spectral range with more confidence. Air turbulence demands fast spectral scanning or probing on and off the absorption line. Energy requirements should be kept small in field operations. In the experiment frequency doubled dye laser pulses at 308 nm are produced. The picosecond light pulses are expected to show a smooth profile (light intensity against wavelength) which will be broadened to the required spectral width according to the uncertainty principle. The pump laser will be an optoacoustically modulated Nd:YAG laser.

  13. Nanofibrous membrane-based absorption refrigeration system

    SciTech Connect

    Isfahani, RN; Sampath, K; Moghaddam, S

    2013-12-01

    This paper presents a study on the efficacy of highly porous nanofibrous membranes for application in membrane-based absorbers and desorbers. Permeability studies showed that membranes with a pore size greater than about one micron have a sufficient permeability for application in the absorber heat exchanger. Membranes with smaller pores were found to be adequate for the desorber heat exchanger. The membranes were implemented in experimental membrane-based absorber and desorber modules and successfully tested. Parametric studies were conducted on both absorber and desorber processes. Studies on the absorption process were focused on the effects of water vapor pressure, cooling water temperature, and the solution velocity on the absorption rate. Desorption studies were conducted on the effects of wall temperature, vapor and solution pressures, and the solution velocity on the desorption rate. Significantly higher absorption and desorption rates than in the falling film absorbers and desorbers were achieved. Published by Elsevier Ltd.

  14. Super-Resonant Intracavity Coherent Absorption

    NASA Astrophysics Data System (ADS)

    Malara, P.; Campanella, C. E.; Giorgini, A.; Avino, S.; de Natale, P.; Gagliardi, G.

    2016-07-01

    The capability of optical resonators to extend the effective radiation-matter interaction length originates from a multipass effect, hence is intrinsically limited by the resonator’s quality factor. Here, we show that this constraint can be overcome by combining the concepts of resonant interaction and coherent perfect absorption (CPA). We demonstrate and investigate super-resonant coherent absorption in a coupled Fabry-Perot (FP)/ring cavity structure. At the FP resonant wavelengths, the described phenomenon gives rise to split modes with a nearly-transparent peak and a peak whose transmission is exceptionally sensitive to the intracavity loss. For small losses, the effective interaction pathlength of these modes is proportional respectively to the ratio and the product of the individual finesse coefficients of the two resonators. The results presented extend the conventional definition of resonant absorption and point to a way of circumventing the technological limitations of ultrahigh-quality resonators in spectroscopy and optical sensing schemes.

  15. Analyzing Water's Optical Absorption

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A cooperative agreement between World Precision Instruments (WPI), Inc., and Stennis Space Center has led the UltraPath(TM) device, which provides a more efficient method for analyzing the optical absorption of water samples at sea. UltraPath is a unique, high-performance absorbance spectrophotometer with user-selectable light path lengths. It is an ideal tool for any study requiring precise and highly sensitive spectroscopic determination of analytes, either in the laboratory or the field. As a low-cost, rugged, and portable system capable of high- sensitivity measurements in widely divergent waters, UltraPath will help scientists examine the role that coastal ocean environments play in the global carbon cycle. UltraPath(TM) is a trademark of World Precision Instruments, Inc. LWCC(TM) is a trademark of World Precision Instruments, Inc.

  16. Differential optoacoustic absorption detector

    NASA Technical Reports Server (NTRS)

    Shumate, M. S. (Inventor)

    1978-01-01

    A differential optoacoustic absorption detector employed two tapered cells in tandem or in parallel. When operated in tandem, two mirrors were used at one end remote from the source of the beam of light directed into one cell back through the other, and a lens to focus the light beam into the one cell at a principal focus half way between the reflecting mirror. Each cell was tapered to conform to the shape of the beam so that the volume of one was the same as for the other, and the volume of each received maximum illumination. The axes of the cells were placed as close to each other as possible in order to connect a differential pressure detector to the cells with connecting passages of minimum length. An alternative arrangement employed a beam splitter and two lenses to operate the cells in parallel.

  17. Two absorption furosemide prodrugs.

    PubMed

    Mombrú, A W; Mariezcurrena, R A; Suescun, L; Pardo, H; Manta, E; Prandi, C

    1999-03-15

    The structures of two absorption furosemide prodrugs, hexanoyloxymethyl 4-chloro-N-furfuryl-5-sulfamoyl-anthranilate (C19H23CIN2O7S), (I), and benzoyloxymethyl 4-chloro-N-furfuryl-5-sulfamoylanthranilate (C20H17CIN2O7S), (II), are described in this paper and compared with furosemide and four other prodrugs. The molecular conformations of both compounds are similar to those of the other prodrugs; the packing and the crystal system are the primary differences. Compound (I) crystallizes in the trigonal space group R3 and compound (II) in the monoclinic space group P2(1)/n. The packing of both structures is stabilized by a three-dimensional hydrogen-bond network.

  18. Derivative spectrophotometry for the determination of faropenem in the presence of degradation products: an application for kinetic studies.

    PubMed

    Cielecka-Piontek, Judyta

    2013-07-01

    A simple and selective derivative spectrophotometric method was developed for the quantitative determination of faropenem in pure form and in pharmaceutical dosage. The method is based on the zero-crossing effect of first-derivative spectrophotometry (λ = 324 nm), which eliminates the overlapping effect caused by the excipients present in the pharmaceutical preparation, as well as degradation products, formed during hydrolysis, oxidation, photolysis, and thermolysis. The method was linear in the concentration range 2.5-300 μg/mL (r = 0.9989) at λ = 341 nm; the limits of detection and quantitation were 0.16 and 0.46 μg/mL, respectively. The method had good precision (relative standard deviation from 0.68 to 2.13%). Recovery of faropenem ranged from 97.9 to 101.3%. The first-order rate constants of the degradation of faropenem in pure form and in pharmaceutical dosage were determined by using first-derivative spectrophotometry. A statistical comparison of the validation results and the observed rate constants for faropenem degradation with these obtained with the high-performance liquid chromatography method demonstrated that both were compatible.

  19. "Show me" bioethics and politics.

    PubMed

    Christopher, Myra J

    2007-10-01

    Missouri, the "Show Me State," has become the epicenter of several important national public policy debates, including abortion rights, the right to choose and refuse medical treatment, and, most recently, early stem cell research. In this environment, the Center for Practical Bioethics (formerly, Midwest Bioethics Center) emerged and grew. The Center's role in these "cultural wars" is not to advocate for a particular position but to provide well researched and objective information, perspective, and advocacy for the ethical justification of policy positions; and to serve as a neutral convener and provider of a public forum for discussion. In this article, the Center's work on early stem cell research is a case study through which to argue that not only the Center, but also the field of bioethics has a critical role in the politics of public health policy.

  20. Phoenix Scoop Inverted Showing Rasp

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This image taken by the Surface Stereo Imager on Sol 49, or the 49th Martian day of the mission (July 14, 2008), shows the silver colored rasp protruding from NASA's Phoenix Mars Lander's Robotic Arm scoop. The scoop is inverted and the rasp is pointing up.

    Shown with its forks pointing toward the ground is the thermal and electrical conductivity probe, at the lower right. The Robotic Arm Camera is pointed toward the ground.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is led by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  1. ShowMe3D

    SciTech Connect

    Sinclair, Michael B

    2012-01-05

    ShowMe3D is a data visualization graphical user interface specifically designed for use with hyperspectral image obtained from the Hyperspectral Confocal Microscope. The program allows the user to select and display any single image from a three dimensional hyperspectral image stack. By moving a slider control, the user can easily move between images of the stack. The user can zoom into any region of the image. The user can select any pixel or region from the displayed image and display the fluorescence spectrum associated with that pixel or region. The user can define up to 3 spectral filters to apply to the hyperspectral image and view the image as it would appear from a filter-based confocal microscope. The user can also obtain statistics such as intensity average and variance from selected regions.

  2. Measuring absorption coefficient of scattering liquids using a tube inside an integrating sphere.

    PubMed

    Villanueva, Yolanda; Veenstra, Colin; Steenbergen, Wiendelt

    2016-04-10

    A method for measuring the absorption coefficient μa of absorbing and scattering liquid samples is presented. The sample is injected into a small transparent tube mounted through an integrating sphere. Two models for determining the absorption coefficient using the relative optical output signal are described and validated using aqueous ink absorbers of 0.5 vol.% (0.3  mm-1a<1.55  mm-1) and 1.0 vol.% (1.0  mm-1a<4.0  mm-1) concentrations with 1 vol.% (μs'≈1.4  mm-1) and 10 vol.% (μs'≈14  mm-1) Intralipid dilutions. The low concentrations give μa and μs values, which are comparable with those of biological tissues. One model assumes a uniform light distribution within the sample, which is valid for low absorption. Another model considers light attenuation that obeys Lambert-Beer's law, which may be used for relatively high absorption. Measurements with low and high scattering samples are done for the wavelength range of 400-900 nm. Measured spectra of purely absorbing samples are within 15% agreement with measurements using standard transmission spectrophotometry. For 0.5 vol.% ink absorbers and at wavelengths below 700 nm, measured μa values are higher for samples with low scattering and lower for those with high scattering. At wavelengths above 700 nm, measured μa values do not vary significantly with amount of scattering. For 1.0 vol.% ink absorbers, measured spectra do not change with low scattering. These results indicate that the method can be used for measuring absorption spectra of scattering liquid samples with optical properties similar to biological absorbers, particularly at wavelengths above 700 nm, which is difficult to accomplish with standard transmission spectrophotometry.

  3. Sapphire fiber evanescent wave absorption in turbid media.

    PubMed

    Zhang, Jian; Xiong, Feibing; Djeu, Nicholas

    2009-08-01

    The influence of particulates on sapphire fiber evanescent wave absorption by water has been studied. Suspensions containing micro-sized graphite flakes and glassy carbon powder were used. Conventional free-space transmittance measurements of these samples showed strong absorption and scattering, which severely screened the absorption by water. However, the absorption on the water band determined from the evanescent wave interaction was unaffected by the presence of the graphite flakes. These results indicate that fiber-optic evanescent wave chemical sensors may be suitable for process control applications involving turbid reactor streams.

  4. Casimir experiments showing saturation effects

    SciTech Connect

    Sernelius, Bo E.

    2009-10-15

    We address several different Casimir experiments where theory and experiment disagree. First out is the classical Casimir force measurement between two metal half spaces; here both in the form of the torsion pendulum experiment by Lamoreaux and in the form of the Casimir pressure measurement between a gold sphere and a gold plate as performed by Decca et al.; theory predicts a large negative thermal correction, absent in the high precision experiments. The third experiment is the measurement of the Casimir force between a metal plate and a laser irradiated semiconductor membrane as performed by Chen et al.; the change in force with laser intensity is larger than predicted by theory. The fourth experiment is the measurement of the Casimir force between an atom and a wall in the form of the measurement by Obrecht et al. of the change in oscillation frequency of a {sup 87}Rb Bose-Einstein condensate trapped to a fused silica wall; the change is smaller than predicted by theory. We show that saturation effects can explain the discrepancies between theory and experiment observed in all these cases.

  5. X-ray Absorption Spectroscopy

    SciTech Connect

    Yano, Junko; Yachandra, Vittal K.

    2009-07-09

    This review gives a brief description of the theory and application of X-ray absorption spectroscopy, both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), especially, pertaining to photosynthesis. The advantages and limitations of the methods are discussed. Recent advances in extended EXAFS and polarized EXAFS using oriented membranes and single crystals are explained. Developments in theory in understanding the XANES spectra are described. The application of X-ray absorption spectroscopy to the study of the Mn4Ca cluster in Photosystem II is presented.

  6. BASIC STUDIES IN PERCUTANEOUS ABSORPTION.

    DTIC Science & Technology

    FATTY ACIDS, *SKIN(ANATOMY), ABSORPTION, ALKYL RADICALS, AMIDES, DIFFUSION, ELECTRON MICROSCOPY, HUMIDITY, LABORATORY ANIMALS, LIPIDS, ORGANIC SOLVENTS, PENETRATION, PRIVATION, PROTEINS, RATS, TEMPERATURE, WATER

  7. Mimas Showing False Colors #1

    NASA Technical Reports Server (NTRS)

    2005-01-01

    False color images of Saturn's moon, Mimas, reveal variation in either the composition or texture across its surface.

    During its approach to Mimas on Aug. 2, 2005, the Cassini spacecraft narrow-angle camera obtained multi-spectral views of the moon from a range of 228,000 kilometers (142,500 miles).

    The image at the left is a narrow angle clear-filter image, which was separately processed to enhance the contrast in brightness and sharpness of visible features. The image at the right is a color composite of narrow-angle ultraviolet, green, infrared and clear filter images, which have been specially processed to accentuate subtle changes in the spectral properties of Mimas' surface materials. To create this view, three color images (ultraviolet, green and infrared) were combined into a single black and white picture that isolates and maps regional color differences. This 'color map' was then superimposed over the clear-filter image at the left.

    The combination of color map and brightness image shows how the color differences across the Mimas surface materials are tied to geological features. Shades of blue and violet in the image at the right are used to identify surface materials that are bluer in color and have a weaker infrared brightness than average Mimas materials, which are represented by green.

    Herschel crater, a 140-kilometer-wide (88-mile) impact feature with a prominent central peak, is visible in the upper right of each image. The unusual bluer materials are seen to broadly surround Herschel crater. However, the bluer material is not uniformly distributed in and around the crater. Instead, it appears to be concentrated on the outside of the crater and more to the west than to the north or south. The origin of the color differences is not yet understood. It may represent ejecta material that was excavated from inside Mimas when the Herschel impact occurred. The bluer color of these materials may be caused by subtle differences in

  8. Absorption Capacity of Ammonia into Ionic Liquids for Absorption Refrigeration Applications

    NASA Astrophysics Data System (ADS)

    Ariyadi, H. M.; Coronas, A.

    2016-09-01

    In this paper ionic liquids are proposed as a novel absorbent for absorption refrigeration application with ammonia as refrigerant. The main objective of this work is to develop a measurement setup to study the absorption capacity of the ammonia vapour in ionic liquids in a pool type absorber. This investigation is essential in order to identify the most suitable ionic liquid as an absorbent for ammonia refrigerant. The ionic liquids studied in this work are combinations of two different cations ([EtOHmim]+ and [emim]+) and three different anions ([BF4]-, [NTf2]- and [EtSO4]-). The absorption processes are observed within 20 minutes in each experiment at different temperatures and pressures. The detail of the methodology and experimental setup are explained in this paper and measurement results of absorption capacity of ammonia into ionic liquid are discussed. Among all ionic liquids studied in this paper [EtOHmim]+ based ionic liquids shows higher absorption capacity than [emim]+ based ionic liquids, which means that the OH structure in the cation may improve the absorption capacity of ammonia.

  9. Cloud geometry effects on atmospheric solar absorption

    SciTech Connect

    Fu, Q.; Cribb, M.C.; Barker, H.W.; Krueger, S.K.; Grossman, A.

    2000-04-15

    A 3D broadband solar radiative transfer scheme is formulated by integrating a Monte Carlo photon transport algorithm with the Fu-Liou radiation model. It is applied to fields of tropical mesoscale convective clouds and subtropical marine boundary layer clouds that were generated by a 2D cloud-resolving model. The effects of cloud geometry on the radiative energy budget are examined by comparing the full-resolution Monte Carlo results with those from the independent column approximation (ICA) that applies the plane-parallel radiation model to each column. For the tropical convective cloud system, it is found that cloud geometry effects always enhance atmospheric solar absorption regardless of solar zenith angle. In a large horizontal domain (512 km), differences in domain-averaged atmospheric absorption between the Monte Carlo and the ICA are less than 4 W m{sup {minus}2} in the daytime. However, for a smaller domain (e.g., 75 km) containing a cluster of deep convective towers, domain-averaged absorption can be enhanced by more than 20 W m{sup {minus}2}. For a subtropical marine boundary layer cloud system during the stratus-to-cumulus transition, calculations show that the ICA works very well for domain-averaged fluxes of the stratocumulus cloud fields even for a very small domain (4.8 km). For the trade cumulus cloud field, the effects of cloud sides and horizontal transport of photons become more significant. Calculations have also been made for both cloud systems including black carbon aerosol and a water vapor continuum. It is found that cloud geometry produces no discernible effects on the absorption enhancement due to the black carbon aerosol and water vapor continuum. The current study indicates that the atmospheric absorption enhancement due to cloud-related 3D photon transport is small. This enhancement could not explain the excess absorption suggested by recent studies.

  10. Intestinal Lipid Absorption and Lipoprotein Formation

    PubMed Central

    Hussain, M. Mahmood

    2014-01-01

    Purpose of review The purpose of this review is to summarize evidence for the presence of two pathways of lipid absorption and their regulation. Recent findings Lipid absorption involves hydrolysis of dietary fat in the lumen of the intestine followed by the uptake of hydrolyzed products by enterocytes. Lipids are re-synthesized in the endoplasmic reticulum and are either secreted with chylomicrons and high density lipoproteins or stored as cytoplasmic lipid droplets. Lipids in the droplets are hydrolyzed and are secreted at a later time. Secretion of lipids by the chylomicron and HDL pathways are critically dependent on MTP and ABCA1, respectively, and are regulated independently. Gene ablation studies showed that MTP function and chylomicron assembly is essential for the absorption of triglyceride and retinyl esters. Ablation of MTP abolishes triglyceride absorption and results in massive triglyceride accumulation in enterocytes. Although majority of phospholipid, cholesterol and vitamin E are absorbed through the chylomicron pathway, a significant amount of these lipids are also absorbed via the HDL pathway. Chylomicron assembly and secretion is increased by the enhanced availability of fatty acids, whereas HDL pathway is upregulated by LXR agonists. Intestinal insulin resistance increases chylomicron and might reduce HDL production. Summary Triglycerides are exclusively transported via the chylomicron pathway and this process is critically dependent on MTP. Besides chylomicrons, absorption of phospholipids, free cholesterol, retinol, and vitamin E also involves high density lipoproteins. These two pathways are complementary and are regulated independently. They may be targeted to lower lipid absorption in order to control hyperlipidemia, obesity, metabolic syndrome, steatosis, insulin resistance, atherosclerosis and other disorders. PMID:24751933

  11. Absorption of light dark matter in semiconductors

    NASA Astrophysics Data System (ADS)

    Hochberg, Yonit; Lin, Tongyan; Zurek, Kathryn M.

    2017-01-01

    Semiconductors are by now well-established targets for direct detection of MeV to GeV dark matter via scattering off electrons. We show that semiconductor targets can also detect significantly lighter dark matter via an absorption process. When the dark matter mass is above the band gap of the semiconductor (around an eV), absorption proceeds by excitation of an electron into the conduction band. Below the band gap, multiphonon excitations enable absorption of dark matter in the 0.01 eV to eV mass range. Energetic dark matter particles emitted from the sun can also be probed for masses below an eV. We derive the reach for absorption of a relic kinetically mixed dark photon or pseudoscalar in germanium and silicon, and show that existing direct detection results already probe new parameter space. With only a moderate exposure, low-threshold semiconductor target experiments can exceed current astrophysical and terrestrial constraints on sub-keV bosonic dark matter.

  12. Airborne spectrophotometry of P/Halley from 16 to 30 microns

    NASA Technical Reports Server (NTRS)

    Herter, T.; Gull, G. E.; Campins, H.

    1986-01-01

    Comet Halley was observed in the 16 to 30 micron region using the Cornell University 7-channel spectrometer (resolution = 0.02) on board the Kuiper Airborne Observatory on 1985 Dec. 14.2. A 30-arcsec aperture (FWHM) was used. Measurements centered on the nuclear condensation micron indicate that if present, the 20 micron silicate feature is very weak, and that a relatively narrow strong feature centered at 28.4 microns possibly exists. However, this feature may be an artifact of incomplete correction for telluric water vapor absorption.

  13. 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.

  14. Atmospheric absorption of sound - Update

    NASA Technical Reports Server (NTRS)

    Bass, H. E.; Sutherland, L. C.; Zuckerwar, A. J.

    1990-01-01

    Best current expressions for the vibrational relaxation times of oxygen and nitrogen in the atmosphere are used to compute total absorption. The resulting graphs of total absorption as a function of frequency for different humidities should be used in lieu of the graph published earlier by Evans et al (1972).

  15. CO2 Capture from Flue Gas by Phase Transitional Absorption

    SciTech Connect

    Liang Hu

    2009-06-30

    A novel absorption process called Phase Transitional Absorption was invented. What is the Phase Transitional Absorption? Phase Transitional Absorption is a two or multi phase absorption system, CO{sub 2} rich phase and CO{sub 2} lean phase. During Absorption, CO{sub 2} is accumulated in CO{sub 2} rich phase. After separating the two phases, CO{sub 2} rich phase is forward to regeneration. After regeneration, the regenerated CO{sub 2} rich phase combines CO{sub 2} lean phase to form absorbent again to complete the cycle. The advantage for Phase Transitional Absorption is obvious, significantly saving on regeneration energy. Because CO{sub 2} lean phase was separated before regeneration, only CO{sub 2} rich phase was forward to regeneration. The absorption system we developed has the features of high absorption rate, high loading and working capacity, low corrosion, low regeneration heat, no toxic to environment, etc. The process evaluation shows that our process is able to save 80% energy cost by comparing with MEA process.

  16. Energy Absorption in a Shear-Thickening Fluid

    NASA Astrophysics Data System (ADS)

    Afeshejani, Seyed Hossein Amiri; Sabet, Seyed Ali Reza; Zeynali, Mohammad Ebrahim; Atai, Mohammad

    2014-12-01

    This study investigates energy absorption in a shear-thickening fluid (STF) containing nano-size fumed silica as a suspending material. Fumed silica particles in 20, 30, and 40 wt.% were used in polyethylene glycol and ethylene glycol. Three areas were studied, namely: energy absorption of STF pre-impregnated aramid fabric, neat STF under high-velocity impact, and flexible foam soaked in STF under low-velocity drop weight impact. Results showed moderate energy absorption in STF pre-impregnated aramid fabric compared to dry fabric. High-velocity impact tests also revealed higher fabric weave density, and multi-layered target plays vital role in optimum performance of SFT impregnated targets. High-velocity impact tests on the neat STF showed good energy absorption at velocities near STF critical shear rate. Low-velocity drop weight impact test on flexible foam soaked in STF also indicated significant energy absorption.

  17. Optical absorption of silicon nanowires

    SciTech Connect

    Xu, T.; Lambert, Y.; Krzeminski, C.; Grandidier, B.; Stievenard, D.; Leveque, G.; Akjouj, A.; Pennec, Y.; Djafari-Rouhani, B.

    2012-08-01

    We report on simulations and measurements of the optical absorption of silicon nanowires (NWs) versus their diameter. We first address the simulation of the optical absorption based on two different theoretical methods: the first one, based on the Green function formalism, is useful to calculate the scattering and absorption properties of a single or a finite set of NWs. The second one, based on the finite difference time domain (FDTD) method, is well-adapted to deal with a periodic set of NWs. In both cases, an increase of the onset energy for the absorption is found with increasing diameter. Such effect is experimentally illustrated, when photoconductivity measurements are performed on single tapered Si nanowires connected between a set of several electrodes. An increase of the nanowire diameter reveals a spectral shift of the photocurrent intensity peak towards lower photon energies that allow to tune the absorption onset from the ultraviolet radiations to the visible light spectrum.

  18. Ultraviolet absorption spectrum of HOCl

    NASA Technical Reports Server (NTRS)

    Burkholder, James B.

    1993-01-01

    The room temperature UV absorption spectrum of HOCl was measured over the wavelength range 200 to 380 nm with a diode array spectrometer. The absorption spectrum was identified from UV absorption spectra recorded following UV photolysis of equilibrium mixtures of Cl2O/H2O/HOCl. The HOCl spectrum is continuous with a maximum at 242 nm and a secondary peak at 304 nm. The measured absorption cross section at 242 nm was (2.1 +/- 0.3) x 10 exp -19/sq cm (2 sigma error limits). These results are in excellent agreement with the work of Knauth et al. (1979) but in poor agreement with the more recent measurements of Mishalanie et al. (1986) and Permien et al. (1988). An HOCl nu2 infrared band intensity of 230 +/- 35/sq cm atm was determined based on this UV absorption cross section. The present results are compared with these previous measurements and the discrepancies are discussed.

  19. Assessment of cosmetic ingredients in the in vitro reconstructed human epidermis test method EpiSkin™ using HPLC/UPLC-spectrophotometry in the MTT-reduction assay.

    PubMed

    Alépée, N; Hibatallah, J; Klaric, M; Mewes, K R; Pfannenbecker, U; McNamee, P

    2016-06-01

    Cosmetics Europe recently established HPLC/UPLC-spectrophotometry as a suitable alternative endpoint detection system for measurement of formazan in the MTT-reduction assay of reconstructed human tissue test methods irrespective of the test system involved. This addressed a known limitation for such test methods that use optical density for measurement of formazan and may be incompatible for evaluation of strong MTT reducer and/or coloured chemicals. To build on the original project, Cosmetics Europe has undertaken a second study that focuses on evaluation of chemicals with functionalities relevant to cosmetic products. Such chemicals were primarily identified from the Scientific Committee on Consumer Safety (SCCS) 2010 memorandum (addendum) on the in vitro test EpiSkin™ for skin irritation testing. Fifty test items were evaluated in which both standard photometry and HPLC/UPLC-spectrophotometry were used for endpoint detection. The results obtained in this study: 1) provide further support for Within Laboratory Reproducibility of HPLC-UPLC-spectrophotometry for measurement of formazan; 2) demonstrate, through use a case study with Basazol C Blue pr. 8056, that HPLC/UPLC-spectrophotometry enables determination of an in vitro classification even when this is not possible using standard photometry and 3) addresses the question raised by SCCS in their 2010 memorandum (addendum) to consider an endpoint detection system not involving optical density quantification in in vitro reconstructed human epidermis skin irritation test methods.

  20. Spectrophotometry of pluto-charon mutual events: individual spectra of pluto and charon.

    PubMed

    Sawyer, S R; Barker, E S; Cochran, A L; Cochran, W D

    1987-12-11

    Time-resolved spectra of the 3 March and 4 April 1987 mutual events of Pluto and its satellite Charon were obtained with spectral coverage from 5,500 to 10,000 angstroms with 25 angstrom spectral resolution. Since both events were total occultations of Charon by Pluto, spectra were obtained of the anti-Charon-facing hemisphere of Pluto, with no contribution from Charon during totality. On 4 April, a combined spectrum of Pluto and Charon immediately before first contact was also obtained. The spectrum of the Pluto-facing hemisphere of Charon was extracted by differencing the pre-event and totality spectra. The spectra were reduced to reflectances by ratioing them to spectra of solar analog stars. Charon has a featureless reflectance spectrum, with no evidence of methane absorption. Charon's reflectance appears neutral in color and corresponds to a geometric albedo of approximately 0.37 at 6000 angstroms. The Pluto reflectance spectrum displays methane absorption bands at 7300, 7900, 8400, 8600, and 8900 angstroms and is red in color, with a geometric albedo of approximately 0.56 at 6000 angstroms. The signal-to-noise ratios of the eclipse spectra were not high enough to unambiguously identify the weaker methane band at 6200 angstroms.

  1. Determination of specific activity of iron-55 by spectrophotometry and liquid scintillation counting with bathophenanthroline complex

    SciTech Connect

    Yonezawa, C.; Hoshi, M.; Tachikawa, E.

    1985-12-01

    A method for determining the macroscopic amount of iron and its radioactivity (/sup 55/Fe) in radioactive corrosion products was established with a single chemical procedure. The iron was first extracted into a liquid scintillator (2,5-diphenyloxazole-xylene) as an ion associate of iron bathophenanthroline (BPT) complex and perchlorate at pH 3-8, followed by measurement of its radioactivity by a liquid scintillation counter and its absorbance by a spectrophotometer. The absorption maximum and molar absorptivity (epsilon) of the complex were 535 nm and 22,000, respectively. The system conforms to Beer's law at concentrations of up to 30 ..mu..g of iron in 10 mL of organic phase. The counting efficiency of the extracted /sup 55/Fe was found to be 60%. Although /sup 60/Co is extracted into the PPO-xylene together with /sup 5/)2%Fe, it is separated from /sup 55/Fe by back extraction with 0.005 M ethylenediaminetetraacetic acid (pH 6.0) into the aqueous phase. The effects of other foreign elements and radionuclides were also examined. The proposed method was successfully applied to analysis of radioactive corrosion products. 21 references, 6 figures, 3 tables.

  2. Gas-absorption process

    DOEpatents

    Stephenson, Michael J.; Eby, Robert S.

    1978-01-01

    This invention is an improved gas-absorption process for the recovery of a desired component from a feed-gas mixture containing the same. In the preferred form of the invention, the process operations are conducted in a closed-loop system including a gas-liquid contacting column having upper, intermediate, and lower contacting zones. A liquid absorbent for the desired component is circulated through the loop, being passed downwardly through the column, regenerated, withdrawn from a reboiler, and then recycled to the column. A novel technique is employed to concentrate the desired component in a narrow section of the intermediate zone. This technique comprises maintaining the temperature of the liquid-phase input to the intermediate zone at a sufficiently lower value than that of the gas-phase input to the zone to effect condensation of a major part of the absorbent-vapor upflow to the section. This establishes a steep temperature gradient in the section. The stripping factors below this section are selected to ensure that virtually all of the gases in the downflowing absorbent from the section are desorbed. The stripping factors above the section are selected to ensure re-dissolution of the desired component but not the less-soluble diluent gases. As a result, a peak concentration of the desired component is established in the section, and gas rich in that component can be withdrawn therefrom. The new process provides important advantages. The chief advantage is that the process operations can be conducted in a single column in which the contacting zones operate at essentially the same pressure.

  3. Airborne spectrophotometry of Eta Carinae from 4.5 to 7.5 microns and a model for source morphology

    NASA Technical Reports Server (NTRS)

    Russell, Ray W.; Lynch, David K.; Hackwell, John A.; Rudy, Richard J.; Rossano, George S.; Castelaz, M. W.

    1987-01-01

    Spectrophotometric observations of Eta Car between 4.5 and 7.5 microns show a featureless thermal-like spectrum with no fine-structure lines or broad emission or absorption features. The color temperature of the spectrum is approximately 375 K. High spatial resolution maps at 3.5, 4.8, and 10 microns obtained from the ground are used to discuss the dust distribution and temperature structure, and to present a model for general source morphology. The upper limit to the brightness of the forbidden Ar II fine-structure emission line at 6.98 microns is less than 7 x 10 to the -16th W/sq cm, which still allows for a significant overabundance of argon and is consistent with the evolved nature of the source.

  4. The measurement of meat pigments by fibre-optic reflectance spectrophotometry using the Kubelka-Munk equation.

    PubMed

    Osawa, M

    1995-01-01

    A reflectance spectrophotometry system with an adhesive pad type fibreoptic probe was developed to measure a wide range of absorbance. The performance of the instrument was evaluated by undertaking in vitro measurements of the reflectance spectra of metmyoglobin solution and meat pastes containing known amounts of oxy-, deoxy- and metmyoglobin. The absorbance of metmyoglobin solution in the range of 0-4 mg/dl as successfully distinguised, but at the upper range of 4 mg/ml the reflectance results were not in proportion to the concentration. All absorbances at 525 nm for meat pastes were also not in proportion to the concentration. These non-linearities were considered to be a result of back-scattering. Therefore, the K/S value of the Kubelka-Munk equation was applied in an effort the refine the fibre optic reflectance method. Positive correlations between the myoglobin concentration and the K/S values obtained from spectra of meat pastes were found.

  5. Combination of fluorescence imaging and local spectrophotometry in fluorescence diagnostics of early cancer of larynx and bronchi

    SciTech Connect

    Sokolov, Vladimir V; Filonenko, E V; Telegina, L V; Boulgakova, N N; Smirnov, V V

    2002-11-30

    The results of comparative studies of autofluorescence and 5-ALA-induced fluorescence of protoporphyrin IX, used in the diagnostics of early cancer of larynx and bronchi, are presented. The autofluorescence and 5-ALA-induced fluorescence images of larynx and bronchial tissues are analysed during the endoscopic study. The method of local spectrophotometry is used to verify findings obtained from fluorescence images. It is shown that such a combined approach can be efficiently used to improve the diagnostics of precancer and early cancer, to detect a primary multiple tumours, as well as for the diagnostics of a residual tumour or an early recurrence after the endoscopic, surgery or X-ray treatment. The developed approach allows one to minimise the number of false-positive results and to reduce the number of biopsies, which are commonly used in the white-light bronchoscopy search for occult cancerous loci. (laser biology and medicine)

  6. Simultaneous determination of trace iron and aluminum by catalytic spectrophotometry based on a novel oxidation reaction of xylene cyanol FF.

    PubMed

    Cai, Longfei; Xu, Chunxiu

    2008-06-01

    A new, simple, sensitive and selective method for the simultaneous determination of trace iron and aluminum by catalytic spectrophotometry was presented, based on the catalytic effects of iron and aluminum on the discoloring reaction of xylene cyanol FF proceeded by hydrogen peroxide and potassium periodate in weak nitric acid medium. No catalytic effect was obtained in the presence of hydrogen peroxide or potassium periodate only. With the conditional rate constants determined in reaction systems catalyzed by Al or Fe only, the concentrations of Fe and Al in the samples can be calculated. The method was applied to the simultaneous determination of trace Fe and Al in tap water, lake water, river water and tea leaves without separation and preconcentration.

  7. Laser Absorption by Over-Critical Plasmas

    NASA Astrophysics Data System (ADS)

    May, J.; Tonge, J.; Fiuza, F.; Fonseca, R. A.; Silva, L. O.; Mori, W. B.

    2015-11-01

    Absorption of high intensity laser light by matter has important applications to emerging sciences and technology, such as Fast Ignition ICF and ion acceleration. As such, understanding the underlying mechanisms of this absorption is key to developing these technologies. Critical features which distinguish the interaction of high intensity light - defined here as a laser field having a normalized vector potential greater than unity - are that the reaction of the material to the fields results in sharp high-density interfaces; and that the movement of the electrons is in general relativistic, both in a fluid and a thermal sense. The results of these features are that the absorption mechanisms are qualitatively distinct from those at lower intensities. We will review previous work, by our group and others, on the absorption mechanisms, and highlight current research. We will show that the standing wave structure of the reflected laser light is key to particle dynamics for normally incident lasers. The authors acknowledge the support of the Department of Energy under contract DE-NA 0001833 and the National Science Foundation under contract ACI 1339893.

  8. Benefit of cerebrospinal fluid spectrophotometry in the assessment of CT scan negative suspected subarachnoid haemorrhage: a diagnostic accuracy study.

    PubMed

    Hann, Angus; Chu, Kevin; Greenslade, Jaimi; Williams, Julian; Brown, Anthony

    2015-01-01

    This study aimed to determine if performing cerebrospinal fluid spectrophotometry in addition to visual inspection detects more ruptured cerebral aneurysms than performing cerebrospinal fluid visual inspection alone in patients with a normal head CT scan but suspected of suffering an aneurysmal subarachnoid haemorrhage (SAH). We performed a single-centre retrospective study of patients presenting to the emergency department of a tertiary hospital who underwent both head CT scan and lumbar puncture to exclude SAH. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of an approach utilising both spectrophotometry and visual inspection (combined approach) was compared to visual inspection alone. A total of 409 patients (mean age 37.8 years, 56.2% female) were recruited and six (1.5%) had a cerebral aneurysm on angiography. The sensitivity of visual inspection was 50% (95% confidence interval [CI]: 12.4-82.6%), specificity was 99% (95% CI: 97.5-99.7%), PPV was 42.9% (95% CI: 10.4-81.3%) and NPV was 99.2% (95% CI: 97.8-99.8%). The combined approach had a sensitivity of 100% (95% CI: 54.1-100%), specificity of 79.7% (95% CI: 75.4-83.5%), PPV of 6.8% (95% CI: 2.6-14.3%) and a NPV of 100% (95% CI: 98.8-100%). The sensitivity of the combined approach was not significantly different to that of visual inspection alone (p=0.25). Visual inspection had a significantly higher specificity than the combined approach (p<0.01). The combined approach detected more cases of aneurysmal SAH than visual inspection alone, however the difference in sensitivity was not statistically significant. Visual xanthochromia should prompt angiography because of a superior specificity and PPV. Due to its reduced sensitivity, caution should be applied when using only visual inspection of the supernatant.

  9. Gastrointestinal citrate absorption in nephrolithiasis

    NASA Technical Reports Server (NTRS)

    Fegan, J.; Khan, R.; Poindexter, J.; Pak, C. Y.

    1992-01-01

    Gastrointestinal absorption of citrate was measured in stone patients with idiopathic hypocitraturia to determine if citrate malabsorption could account for low urinary citrate. Citrate absorption was measured directly from recovery of orally administered potassium citrate (40 mEq.) in the intestinal lavage fluid, using an intestinal washout technique. In 7 stone patients citrate absorption, serum citrate levels, peak citrate concentration in serum and area under the curve were not significantly different from those of 7 normal subjects. Citrate absorption was rapid and efficient in both groups, with 96 to 98% absorbed within 3 hours. The absorption of citrate was less efficient from a tablet preparation of potassium citrate than from a liquid preparation, probably due to a delayed release of citrate from wax matrix. However, citrate absorption from solid potassium citrate was still high at 91%, compared to 98% for a liquid preparation. Thus, hypocitraturia is unlikely to be due to an impaired gastrointestinal absorption of citrate in stone patients without overt bowel disease.

  10. Optical Radiation Bioeffects TO9

    DTIC Science & Technology

    2009-02-01

    Absorption coefficient data from a spectrophotometry study. ............................ 23 Figure 15 Combined data from Figures 13 and 14, showing...distribution unlimited Figure 14 Absorption coefficient data from a spectrophotometry study. The results of Figure 13, and the...G. Y. Swanland, R. J. Thomas, and A. T. Tsin, 2006, Optical properties of ocular tissues in the near infrared region, Ophthalmic Technologies XVI

  11. Application of first-derivative UV-spectrophotometry, TLC-densitometry and liquid chromatography for the simultaneous determination of mebeverine hydrochloride and sulpiride.

    PubMed

    El Walily, A F; El Gindy, A; Bedair, M F

    1999-11-01

    Three methods are described for the simultaneous determination of mebeverine hydrochloride (MB) and sulpiride (SU) in combined pharmaceutical tablets. The first method depends on first-derivative ultraviolet spectrophotometry, with zero-crossing measurement method. The first derivative amplitudes at 214.2 and 221.6 nm were selected for the assay of MB and SU, respectively. Calibration graphs follow Beer's law in the range of 10-30 and 2-8 microg/ml(-1), and the linearity was satisfactory (r = 0.9999), for MB and SU, respectively. The second method was based on the application of the thin layer chromatographic separation of both drugs followed by the densitometric measurements of their spot areas. After separation on silica gel GF254 plates, using ethanol: diethyl ether: triethylamine (70:30:1 v/v) as the mobile phase, the chromatographic zones corresponding to the spots of MB and SU were scanned at 262 and 240 nm, respectively. The calibration function was established in the ranges of 4-12 microg for MB and 2-8 microg for SU. The third method was an internal standard procedure based on high performance liquid chromatographic separation of the two drugs on a reversed-phase, Bondapak CN column. The detection was done at 243 nm using buclizine hydrochloride as internal standard. All chromatographic methods showed good linearity, precision and reproducibility. No spectral or chromatographic interference from the tablet excipients were found. The proposed methods were successfully applied to the assay of commercial tablets and content uniformity test. The procedures were rapid, simple and suitable for quality control application.

  12. Ultraviolet spectrophotometry (dual wavelength and chemometric) and high performance liquid chromatography for simultaneous estimation of meropenem and sulbactam sodium in pharmaceutical dosage form.

    PubMed

    Marwada, Kuldip R; Patel, Jigar B; Patel, Nisarg S; Patel, Bhargav D; Borkhatariya, Dharnant V; Patel, Archita J

    2014-04-24

    UV spectrophotometric and high performance liquid chromatography (HPLC) methods were developed for simultaneous determination of meropenem (MERM) and sulbactam sodium (SB) in injection. UV spectrophotometric methods were developed using 0.1N sodium hydroxide as solvent. The Beer's plot for dual wavelength method was linear in the range of 4-24 μg mL(-1) and 2-12 μg mL(-1) for MERM and SB, respectively. The percent recoveries were found to be 98.52±1.23% for MERM and 101.45±1.1% for SB. Chemometrics assisted UV spectrophotometry was performed using Partial Least Square (PLS) analysis model and Principal Component Regression (PCR) analysis model. The % recoveries of the MERM were found to be 100.61±0.06% and 101.31±0.12% using PLS and PCR, respectively. The % recoveries of the SB were found to be 98.29±0.09% and 97.61±0.13% using PLS and PCR, respectively. Chromatography was performed on Hypersil BDS C18 column using methanol:acetonitrile:water (10:20:70 v/v/v) as mobile phase. The retention times of MERM and SB were found to be 2.9 min and 2.25 min, respectively. Developed HPLC method was found to be linear in the range of 50-250 μg mL(-1) and 25-125 μg mL(-1) for MERM and SB, respectively. The % recoveries were found to be 98.85±0.25% and 98.63±0.34% for MERM and SB, respectively. The developed analytical methods did not show any interference of the excipients when applied to pharmaceutical dosage form.

  13. AGN warm absorption with the ATHENA

    NASA Astrophysics Data System (ADS)

    Różańska, Agata; Gronkiewicz, Dominik; Hryniewicz, Krzysztof; Adhikari, Tek Prasad; Rataj, Mirosław; Skup, Konrad

    2016-06-01

    X-ray astronomy requires satellites to make progress in searching the distribution of hot matter in the Universe. Approximately 15 years period of time is needed for full construction of the flight instrument from the mission concept up to the launch. A new generation X-ray telescope ATHENA (the Advanced Telescope for High Energy Astrophysics) was approved by European Space Agency as a large mission with a launch foreseen in 2028. In this paper we show how microcalorimeter on the board of ATHENA will help us to study warm absorption observed in active galactic nuclei (AGN). We show that future observations will allow us to identify hundreds of lines from highly ionized elements and to measure Galactic warm absorption with very high precision.

  14. Seasonal skin colour changes in a sample teenage population measured by reflection spectrophotometry

    NASA Astrophysics Data System (ADS)

    Stringer, M. R.; Cruse-Sawyer, J. E.

    2007-11-01

    As part of a classroom-based research project, reflectance spectra from the skin of a group of teenage school students were recorded over a four-month period, from early spring to mid-summer. The relative changes in skin colour during the course of the study were quantified by integrating over the full wavelength range of the normalized reflectance spectra. Measurements made upon the inner forearm and the back of the hand produce results which indicate a decrease in total reflectance (increase in absorption) corresponding to different levels of tanning for limited and extended exposure to ambient sunlight, respectively. The rate of change of skin colour qualitatively matches that of the solar illuminance.

  15. [Rate of controlled-release urea pervasion through membrane determined by ultraviolet spectrophotometry].

    PubMed

    Zuo, Xiu-jin; Wang, Zhen-xin; Dai, Xiao-min; Zhou, Yi; Ma, Xiao-jun

    2006-06-01

    Application of controlled-release nitrogenous fertilizers can improve the efficiency of fertilizers and reduce the environmental pollution. Controlled-release urea (coated urea) is one of the controlled-release nitrogenous fertilizers developed quickly in the recent years. The rate of controlled-release urea pervasion through membrane is the most important index of the capacity of controlled release. There is a maximum absorption at lambda=426 nm with complex in acidic solution, using p-dimethylaminozenzaldehyde as color reagent, and the absorbance exhibits a linear reponses to the urea concentration over the range of 7.5-210 microg x mL(-1). The method for determining the rate of controlled-release urea pervasion through membrane was realized through determining the content of urea in the liquor, the recovery efficiency of the method is 96.1%-103.9%.

  16. Phononic glass: a robust acoustic-absorption material.

    PubMed

    Jiang, Heng; Wang, Yuren

    2012-08-01

    In order to achieve strong wide band acoustic absorption under high hydrostatic pressure, an interpenetrating network structure is introduced into the locally resonant phononic crystal to fabricate a type of phononic composite material called "phononic glass." Underwater acoustic absorption coefficient measurements show that the material owns high underwater sound absorption coefficients over 0.9 in 12-30 kHz. Moreover, the quasi-static compressive behavior shows that the phononic glass has a compressive strength over 5 MPa which is crucial for underwater applications.

  17. High absorption efficiency of AlGaAs/GaAs superlattice solar cells

    NASA Astrophysics Data System (ADS)

    Nishinaga, Jiro; Kawaharazuka, Atsushi; Horikoshi, Yoshiji

    2015-05-01

    The effects of excitonic absorption on the solar cell efficiency have been investigated in solar cells with AlGaAs/GaAs superlattice absorption layers. Numerical calculations reveal that excitonic absorption considerably enhances the overall absorption coefficient. The excitonic absorption shows strong peaks at the absorption edge and in the energy region above the band gap. Absorption enhancement is also achieved in the AlGaAs/GaAs superlattice. The measured quantum efficiency spectra of superlattice solar cells at room temperature are reasonably well reproduced by simulations taking excitonic effects into account. The superlattice solar cells are confirmed to have a high absorbance and good temperature stability. The theoretical analysis of the experimental results confirms that the enhanced excitonic absorption in the superlattice absorption layers survives even at 100 °C, which is considered as the actual device temperature under realistic device operations.

  18. Impedance Matched Absorptive Thermal Blocking Filters

    NASA Technical Reports Server (NTRS)

    Wollack, E. J.; Chuss, D. T.; Rostem, K.; U-Yen, K.

    2014-01-01

    We have designed, fabricated and characterized absorptive thermal blocking filters for cryogenic microwave applications. The transmission line filter's input characteristic impedance is designed to match 50O and its response has been validated from 0-to-50GHz. The observed return loss in the 0-to-20GHz design band is greater than 20 dB and shows graceful degradation with frequency. Design considerations and equations are provided that enable this approach to be scaled and modified for use in other applications.

  19. Impedance Matched Absorptive Thermal Blocking Filters

    NASA Technical Reports Server (NTRS)

    Wollack, E. J.; Chuss, D. T.; U-Yen, K.; Rostem, K.

    2014-01-01

    We have designed, fabricated and characterized absorptive thermal blocking filters for cryogenic microwave applications. The transmission line filter's input characteristic impedance is designed to match 50 Omega and its response has been validated from 0-to-50GHz. The observed return loss in the 0-to-20GHz design band is greater than 20 dB and shows graceful degradation with frequency. Design considerations and equations are provided that enable this approach to be scaled and modified for use in other applications.

  20. Atmospheric ammonia: absorption by plant leaves.

    PubMed

    Hutchinson, G L; Millington, R J; Peters, D B

    1972-02-18

    By monitoring the disappearance of ammonia from an airstream flowing through a small growth chamber containing a single plant seedling, it was discovered that plant leaves absorb significant quantities of ammonia from the air, even at naturally occurring low atmospheric concentrations. The measured absorption rates of ammonia showed large diurnal fluctuations and varied somewhat among species, but differed little with the nitrogen fertility level of plants within a species.

  1. Hemin (Fe(3+))-- and heme (Fe(2+))--smectite conjugates as a model of hemoprotein based on spectrophotometry.

    PubMed

    Itoh, T; Yamada, T; Kodera, Y; Matsushima, A; Hiroto, M; Sakurai, K; Nishimura, H; Inada, Y

    2001-01-01

    Hemin (Fe(3+)) was adsorbed onto synthetic smectite (clay mineral) in acetone to form a hemin-smectite conjugate. The hemin-smectite conjugate became soluble in water to form a transparent colloidal solution with a dark brown color. Its absorption spectrum in water showed a sharp Soret band at 398 nm with the molar extinction coefficient as epsilon(398nm) = 11.6 x 10(4) M(-1) cm(-1), which is in good agreement with epsilon(398nm) = (12.2 +/- 3) x 10(4) M(-1) cm(-1) of monomeric hematin (1). Hemin (Fe(3+))-smectite conjugate had a peroxidase-like activity in the presence of hydrogen peroxide (a hydrogen acceptor) and guaiacol (a hydrogen donor) in aqueous solution and its activity was higher than that of hematin. Hemin (Fe(3+))-smectite conjugate in water was reduced by adding sodium dithionite to form a heme (Fe(2+))-smectite conjugate which is also a transparent colloidal solution in water. Its absorption spectrum in aqueous solution was surprisingly in close agreement with that of oxyhemoglobin. Its peak positions of alpha, beta, and Soret bands were located in only a 9--3 nm shift to shorter wavelengths in comparison with those of oxyhemoglobin. Therefore, heme (Fe(2+))-smectite conjugate was bound to O(2) to form O(2)-heme (Fe(2+))-smectite conjugate. The addition of carbon monoxide, CO, to O(2)-heme (Fe(2+))-smectite conjugate caused the formation of CO-heme (Fe(2+))-smectite conjugate with a similar absorption spectrum of carboxyhemoglobin (HbCO) accompanied by shifting 8--10 nm to shorter wavelength. Therefore, the transformation of O(2)-heme (Fe(2+))-smectite conjugate to CO-heme (Fe(2+))-smectite conjugate was accompanied by shifting of 7, 4, and 3 nm to shorter wavelengths in the alpha, beta, and Soret bands respectively, which are similar to the spectral change from oxyhemoglobin to carboxyhemoglobin. Also the ratio (1:1.6) of the molar extinction coefficient of Soret band of O(2)-heme (Fe(2+))-smectite conjugate and CO-heme (Fe(2+))-smectite conjugate

  2. Design of plasmonic circular grating with broadband absorption enhancements

    NASA Astrophysics Data System (ADS)

    Chiu, Nan-Fu; Yang, Cheng-Du; Kao, Yi-Lun; Cheng, Chih-Jen

    2015-05-01

    We have investigated the effect of concentric circles geometry on the performance of focusing plasmonic circular grating (PCG)-coupled surface-omnidirectional absorption. We wish to highlight the essential characteristics of plasmonic circular grating nanostructure to assist researchers in developing and advancing suitable organic solar cells (OSC) for unique applications. Exactly how plasmonic enhancement and the absorption characteristics of the organic materials (P3HT:PCBM and PEDOT:PSS) interact with each other is also examined. We present experimental studies of broadband absorption enhancement in PCG structure. We show that the PCG structure can result in broadband absorption enhancement, the overall optical absorption in organic film can be greatly enhanced up to ~111.2 % compared to the planar device without grating.

  3. Excitonic absorption intensity of semiconducting and metallic carbon nanotubes.

    PubMed

    Verdenhalven, Eike; Malić, Ermin

    2013-06-19

    The knowledge of the intrinsic absorption intensity of each carbon nanotube is of crucial importance for the optical assignment of nanotube species and the estimation of their abundance in a sample. Based on a microscopic approach, we calculate excitonic absorption spectra for a variety of semiconducting and metallic nanotubes, revealing a clear diameter, chirality, and family dependence of the absorption intensity. In particular, we also study the appearance of excited excitonic transitions, which are shown to be well pronounced for semiconducting nanotubes, reaching intensities of up to 10% of the main transition. We find that nanotubes with large diameters show the most pronounced absorption intensities, confirming well the experimentally observed trend. Depending on the CNT family and transition, the absorption is enhanced or reduced with the chiral angle. This behavior reflects well the qualitative chirality dependence of the analytically derived optical matrix element.

  4. Quantum Entanglement Molecular Absorption Spectrum Simulator

    NASA Technical Reports Server (NTRS)

    Nguyen, Quang-Viet; Kojima, Jun

    2006-01-01

    Quantum Entanglement Molecular Absorption Spectrum Simulator (QE-MASS) is a computer program for simulating two photon molecular-absorption spectroscopy using quantum-entangled photons. More specifically, QE-MASS simulates the molecular absorption of two quantum-entangled photons generated by the spontaneous parametric down-conversion (SPDC) of a fixed-frequency photon from a laser. The two-photon absorption process is modeled via a combination of rovibrational and electronic single-photon transitions, using a wave-function formalism. A two-photon absorption cross section as a function of the entanglement delay time between the two photons is computed, then subjected to a fast Fourier transform to produce an energy spectrum. The program then detects peaks in the Fourier spectrum and displays the energy levels of very short-lived intermediate quantum states (or virtual states) of the molecule. Such virtual states were only previously accessible using ultra-fast (femtosecond) laser systems. However, with the use of a single-frequency continuous wave laser to produce SPDC photons, and QEMASS program, these short-lived molecular states can now be studied using much simpler laser systems. QE-MASS can also show the dependence of the Fourier spectrum on the tuning range of the entanglement time of any externally introduced optical-path delay time. QE-MASS can be extended to any molecule for which an appropriate spectroscopic database is available. It is a means of performing an a priori parametric analysis of entangled photon spectroscopy for development and implementation of emerging quantum-spectroscopic sensing techniques. QE-MASS is currently implemented using the Mathcad software package.

  5. Microwave radiation absorption: behavioral effects.

    PubMed

    D'Andrea, J A

    1991-07-01

    The literature contains much evidence that absorption of microwave energy will lead to behavioral changes in man and laboratory animals. The changes include simple perturbations or outright stoppage of ongoing behavior. On one extreme, intense microwave absorption can result in seizures followed by death. On the other extreme, man and animals can hear microwave pulses at very low rates of absorption. Under certain conditions of exposure, animals will avoid microwaves, while under other conditions, they will actively work to obtain warmth produced by microwaves. Some research has shown behavioral effects during chronic exposure to low-level microwaves. The specific absorption rates that produce behavioral effects seem to depend on microwave frequency, but controversy exists over thresholds and mechanism of action. In all cases, however, the behavioral disruptions cease when chronic microwave exposure is terminated. Thermal changes in man and animals during microwave exposure appear to account for all reported behavioral effects.

  6. Reflective-tube absorption meter

    NASA Astrophysics Data System (ADS)

    Zaneveld, J. Ronald V.; Bartz, Robert; Kitchen, James C.

    1990-09-01

    The design and calibration of a proposed in situ spectral absorption meter is evaluated using a laboratory prototype. The design includes a silver coated (second-surface) glass tube, a tungsten light source (stabilized by means of optical feedback), a monochromator, and a solid state detector. The device measures the absorption coefficient plus a portion of the volume scattering function. Theoretical analyses and laboratory experiments which explore the magnitude and variation of the errors due to scattering and internal reflections are described. Similar analyses are performed on the Cary 1 18 Spectrophotometer to allow cross calibration. Algorithms to yield the abscrption coefficient and the zenith-sun diffuse attenuation coefficient are presented and evaluated. Simultaneous measurement of the beam attenuation or backscattering coefficient allows use of algoriThms with much narrower error bands. The various methods of obtaining absorption and diffuse attenuation values are compared. Procedures for using reverse osmosis filtration to produce a clean water calibration standard are described. An absorption spectrum for pure water is obtained. Development of the absorption meter is proceeding along two lines: 1) a two-wavelength side-by-side LED is being fabricated to allow an in situ chlorophyll a absorption meter to be constructed, and 2) scientific projects using a shipboard or laboratory flow.-through pumping system are being planned.

  7. Study of the absorption spectra of the 4f electron transitions of the praseodymium complex with ciprofloxacin and its analytical application.

    PubMed

    Wei, J; Naixing, W; Quanjie, M; Zhikun, S; Xiuqin, X; Fuxiang, L

    2001-08-01

    Ciprofloxacin (CPFX) is proposed as a reagent for the derivative spectrophotometric determination of praseodymium in mixed rare earths. The absorption spectra of 4f electron transitions of the praseodymium complex with CPFX was studied by normal and derivative spectrophotometry. The stoichiometry of the praseodymium-CPFX complex was calculated by the molar ratio and continuous variations methods. A ratio of Pr to CPFX of 1:3 was found. The absorption bands of the 4f electron transitions of the complex were enhanced markedly. Using the third derivative spectrum. Beer's law was obeyed up to 35 microg cm(-3) of praseodymium. The relative standard deviation is 0.62% for 14 microg cm(-3) of praseodymium. The detection and quantification limits were 0.17 and 0.56 microg cm(-3) of praseodymium, respectively. A method for the direct determination of praseodymium in mixtures of rare earths with good accuracy and selectivity is described.

  8. Determination of gold, indium, tellurium and thallium in the same sample digest of geological materials by atomic-absorption spectroscopy and two-step solvent extraction

    USGS Publications Warehouse

    Hubert, A.E.; Chao, T.T.

    1985-01-01

    A rock, soil, or stream-sediment sample is decomposed with hydrofluoric acid, aqua regia, and hydrobromic acid-bromine solution. Gold, thallium, indium and tellurium are separated and concentrated from the sample digest by a two-step MIBK extraction at two concentrations of hydrobromic add. Gold and thallium are first extracted from 0.1M hydrobromic acid medium, then indium and tellurium are extracted from 3M hydrobromic acid in the presence of ascorbic acid to eliminate iron interference. The elements are then determined by flame atomic-absorption spectrophotometry. The two-step solvent extraction can also be used in conjunction with electrothermal atomic-absorption methods to lower the detection limits for all four metals in geological materials. ?? 1985.

  9. Quantitation of Pyrantel Pamoate in Pharmaceuticals Using Permanganate by Visible Spectrophotometry

    NASA Astrophysics Data System (ADS)

    Rajendraprasad, N.; Basavaiah, K.

    2014-03-01

    Two simple, accurate and precise spectrophotometric methods are developed and validated for the assay of pyrantel pamoate (PP) in pharmaceuticals. The methods employ the oxidative property of potassium permanganate (KMnO4) in acidic and alkaline conditions. In the first method (method A), PP is converted into its free base, pyrantel (PR), and treated with known excess of KMnO4 in acidic condition followed by the measurement of unreacted KMnO4 at 550 nm. Method B is based on the registration of absorbance of green colored chromogen formed due to the reduction of KMnO4 by PP in alkaline condition. The methods obeyed Beer's law over a range of 1-20 μg/ml in inverse manner, and 0.75-15 μg/ml for method A and method B, respectively, with apparent molar absorptivity values of 1.05ṡ104 and 2.85ṡ104 lṡmol-1ṡcm-1. The optical parameters such as limits of detection (LOD), quantification (LOQ), and the Sandell sensitivity values are also reported. The accuracy and precision of the methods are assessed on intra- and inter-day basis. A recovery study by standard addition procedure is also carried out for further assurance of accuracy. The developed methods are successfully applied to determine PP in tablets. The results are more satisfactory as per current ICH guidelines.

  10. Flow injection spectrophotometry using natural reagent from Morinda citrifolia root for determination of aluminium in tea.

    PubMed

    Tontrong, Sopa; Khonyoung, Supada; Jakmunee, Jaroon

    2012-05-01

    A flow injection (FI) spectrophotometric method with using natural reagent extracted from Morinda citrifolia root has been developed for determination of aluminium. The extract contained anthraquinone compounds which could react with Al(3+) to form reddish complexes which had maximum absorption wavelength at 499.0nm. The extract could be used as a reagent in FI system without further purification to obtain pure compound. A sensitive method for determination of aluminium in concentration range of 0.1-1.0mgL(-1), with detection limit of 0.05mgL(-1) was achieved. Relative standard deviations of 1.2% and 1.7% were obtained for the determination of 0.1 and 0.6mgL(-1) Al(3+) (n=11). Sample throughput of 35h(-1) was achieved with the consumption of 3mL each of carrier and reagent solutions per injection. The developed method was successfully applied to tea samples, validated by the FAAS standard method. The method is simple, fast, economical and could be classified as a greener analytical method.

  11. Imaging Spectrophotometry of the Jet/ISM Interaction in IC5063

    NASA Technical Reports Server (NTRS)

    Cecil, G.; Schuft, B.; Morse, J.; Bland-Hawthorn, J.

    2004-01-01

    IC5063 is a somewhat dusty z=0.0110 S0 galaxy with a Seyfert 2 nucleus. It has a triple radio source that spans 3 arcsec, mostly blueshifted H I absorption that spans 700 km/s, and ionization cones that extend for more than 2 arcmins. We obtained fully sampled [O III]\\lambda5007 grids at 0."9 and 70 km/s FWHM resolution using the Rutgers Fabry-Perot system on the Blanco 4m telescope. Complementary long-slit spectra using the RC spectrograph on the Blanco, and Taurus Tunable Filter spectral images in H\\alpha and [N II]\\lambda6583, were also obtained to assess gaseous ionization conditions. We present the results of our analysis, and correlate spectral structures to those visible in archival WFPC2 images. We find that, in the region near the radio triple, gaseous ionization and line velocity width is tightly correlated, in excellent quantitative agreement with the high-velocity shock regime in the diagnostic emission-line ratio diagrams of Dopita & Sutherland. We separate kinematically gas in normal disk rotation that is illuminated by the AGN in the ionization cones from that agitated mechanically by the jet, and assess the energy input from both processes.

  12. Determination of trace amount of oxalic acid with zirconium(IV)-(DBS-arsenazo) by spectrophotometry

    NASA Astrophysics Data System (ADS)

    Zhai, Qing-Zhou

    2008-11-01

    A novel method is proposed for the determination of trace amount of oxalic acid in the present article. In 1.0 M hydrochloric acid medium, oxalic acid can react with the zirconium(IV) in Zr(IV)-(DBS-arsenazo) complex and replaces the DBS-arsenazo to produce a hyperchromic effect at 520 nm. The hyperchromic degree is proportional to the concentration of the oxalic acid added over a defined range. Based on this property, a new method for the spectrophotometric determination of trace oxalic acid was developed. Beer's law is held over the concentration range of 9.0 × 10 -6 to 5.0 × 10 -4 M for oxalic acid with a correlation coefficient of 0.9995. The apparent molar absorptivity of the method is ɛ520 nm = 1.16 × 10 3 L mol -1 cm -1 and the detection limit for oxalic acid is 0.815 μg/mL. The developed method was directly applied to the determination of oxalic acid in tomato samples with satisfactory results.

  13. The determination of trace lead in drinking water by flow injection spectrophotometry.

    PubMed

    Dai, Shijun; Zhang, Xinshen; Yu, Lingyun; Yang, Yujie

    2010-01-01

    Lead is the non-essential trace element in the human body, and it has been confirmed that drinking water is one of the sources of lead in human body. In the research, based on the sensitive colour reaction of lead with I(-)-EV(+)-PVA, a simple, sensitive, accurate and portable method for the determination of trace lead in drinking waters was proposed. Chemicals and physicals had been optimized in detail. The apparent molar absorption coefficient was up to 7.4x10(5) mol L(-1) cm(-1). The developed method provided a linearity range over 5-80 microg L(-1). The regression deviation was between 0.71% and 2.33%. The 3sigma detection limit was 0.9 microg L(-1). Close to the quantitation limit for the analyte the relative standard deviation was 1.10% (n=10) at 40 microg L(-1). The method developed here for analysis of lead yielded results that were comparable with those of the GFAAS.

  14. Determination of trace amount of oxalic acid with zirconium(IV)-(DBS-arsenazo) by spectrophotometry.

    PubMed

    Zhai, Qing-Zhou

    2008-11-15

    A novel method is proposed for the determination of trace amount of oxalic acid in the present article. In 1.0M hydrochloric acid medium, oxalic acid can react with the zirconium(IV) in Zr(IV)-(DBS-arsenazo) complex and replaces the DBS-arsenazo to produce a hyperchromic effect at 520 nm. The hyperchromic degree is proportional to the concentration of the oxalic acid added over a defined range. Based on this property, a new method for the spectrophotometric determination of trace oxalic acid was developed. Beer's law is held over the concentration range of 9.0 x 10(-6) to 5.0 x 10(-4)M for oxalic acid with a correlation coefficient of 0.9995. The apparent molar absorptivity of the method is epsilon520 nm = 1.16 x 10(3)L mol(-1)cm(-1) and the detection limit for oxalic acid is 0.815 microg/mL. The developed method was directly applied to the determination of oxalic acid in tomato samples with satisfactory results.

  15. Simultaneous determination of hexavalent and total chromium in water and plating baths by spectrophotometry.

    PubMed

    Gao, R M; Zhao, Z Q; Zhou, Q Z; Yuan, D X

    1993-05-01

    A new spectrophotometric determination method of hexavalent chromium in waste water and plating baths is described based on the oxidation of beryllon III by chromium(VI) in 0.02M sulphuric acid medium. The decrease in the absorbance of beryllon III was measured at 482 nm with an apparent molar absorptivity of 5.15 x 10(4)1.mole(-1).cm(-1). Beer's law was obeyed for chromium(VI) over the range 0-25 mug/25 ml. After the oxidation of Cr(III) to Cr(VI) by ammonium persulphate, total chromium can be determined. Therefore, chromium(III) can be calculated by subtracting chromium(VI) from total chromium. The detection limit is 0.015 and 0.020 mug/25 ml for chromium(VI) and total chromium, respectively. A sensitive spectrophotometric method for trace Cr(III) and Cr(VI) in waste water and plating baths was developed with good precision and accuracy. The reaction is also discussed.

  16. Spectrophotometry of the central region of the galaxy Markaryan 298 = IC 1182-4

    NASA Astrophysics Data System (ADS)

    Metik, L. P.; Pronik, I. I.

    1981-10-01

    An analysis of spectra obtained with an approximately 95 A/mm-dispersion spectrograph has yielded new data on the structure of the central region of the Seyfert galaxy Markaryan 298 = IC 1182-4. The central region's gaseous formation has a diameter of 6.5 kpc, an electron density of 0.2-0.5/cu cm, and a mass ratio (M/solar-M) ranging from 0.6 x 10 to the 7th to 7 x 10 to the 8th. The data further suggests that this gas formation is associated with condensations of blue stars, and interacts with both the nucleus and the eastern elongated structure of the galaxy. The nucleus of Markaryan 298 is found to be a type 1 Seyfert which is distorted by dust absorption, with a hydrogen envelope that is opaque in the Balmer lines and inhomogeneous in its physical conditions. Gas condensations in the forbidden line emission region are found to be of the densities 20, 10,000 and 200,000/cu cm

  17. Milli-tesla NMR and spectrophotometry of liquids hyperpolarized by dissolution dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Zhu, Yue; Chen, Chia-Hsiu; Wilson, Zechariah; Savukov, Igor; Hilty, Christian

    2016-09-01

    Hyperpolarization methods offer a unique means of improving low signal strength obtained in low-field NMR. Here, simultaneous measurements of NMR at a field of 0.7 mT and laser optical absorption from samples hyperpolarized by dissolution dynamic nuclear polarization (D-DNP) are reported. The NMR measurement field closely corresponds to a typical field encountered during sample injection in a D-DNP experiment. The optical spectroscopy allows determination of the concentration of the free radical required for DNP. Correlation of radical concentration to NMR measurement of spin polarization and spin-lattice relaxation time allows determination of relaxivity and can be used for optimization of the D-DNP process. Further, the observation of the nuclear Overhauser effect originating from hyperpolarized spins is demonstrated. Signals from 1H and 19F in a mixture of trifluoroethanol and water are detected in a single spectrum, while different atoms of the same type are distinguished by J-coupling patterns. The resulting signal changes of individual peaks are indicative of molecular contact, suggesting a new application area of hyperpolarized low-field NMR for the determination of intermolecular interactions.

  18. Circadian regulators of intestinal lipid absorption

    PubMed Central

    Hussain, M. Mahmood; Pan, Xiaoyue

    2015-01-01

    Among all the metabolites present in the plasma, lipids, mainly triacylglycerol and diacylglycerol, show extensive circadian rhythms. These lipids are transported in the plasma as part of lipoproteins. Lipoproteins are synthesized primarily in the liver and intestine and their production exhibits circadian rhythmicity. Studies have shown that various proteins involved in lipid absorption and lipoprotein biosynthesis show circadian expression. Further, intestinal epithelial cells express circadian clock genes and these genes might control circadian expression of different proteins involved in intestinal lipid absorption. Intestinal circadian clock genes are synchronized by signals emanating from the suprachiasmatic nuclei that constitute a master clock and from signals coming from other environmental factors, such as food availability. Disruptions in central clock, as happens due to disruptions in the sleep/wake cycle, affect intestinal function. Similarly, irregularities in temporal food intake affect intestinal function. These changes predispose individuals to various metabolic disorders, such as metabolic syndrome, obesity, diabetes, and atherosclerosis. Here, we summarize how circadian rhythms regulate microsomal triglyceride transfer protein, apoAIV, and nocturnin to affect diurnal regulation of lipid absorption. PMID:25057097

  19. Dust in MG II Absorption Systems

    NASA Astrophysics Data System (ADS)

    Malhotra, S.

    The dust absorption feature at 2175 AA is detected in a composite spectrum of Mg II absorbers. The composite absorber spectrum is obtained by taking the geometric mean of 92 quasar spectra after aligning them in the rest-frame of 96 absorbers. By aligning the spectra according to absorber redshifts we reinforce the spectral features of the absorbers, and smooth over possible bumps and wiggles in the emission spectra. The width of the observed absorption feature is 200-300 AA (FWHM), or 0.4-0.6 microns^{-1} and the central wavelength is 2240 AA. The Galactic dust feature has a central wavelength of 2176 AA and FWHM = 0.8-1.25 microns^{-1}. Simulations show that this discrepancy between the properties of the 2175 AA feature in Mg II absorbers and Galactic ISM can be mostly explained by the different methods used to measure them (cf. Malhotra 1997).

  20. Exciton absorption in narrow armchair graphene nanoribbons

    NASA Astrophysics Data System (ADS)

    Monozon, B. S.; Schmelcher, P.

    2016-11-01

    We develop an analytical approach to the exciton optical absorption for narrow gap armchair graphene nanoribbons (AGNR). We focus on the regime of dominant size quantization in combination with the attractive electron-hole interaction. An adiabatic separation of slow and fast motions leads via the two-body Dirac equation to the isolated and coupled subband approximations. Discrete and continuous exciton states are in general coupled and form quasi-Rydberg series of purely discrete and resonance type character. The corresponding oscillator strengths and widths are derived. We show that the exciton peaks are blue-shifted, become broader and increase in magnitude upon narrowing the ribbon. At the edge of a subband the singularity related to the 1D density of states is transformed into finite absorption via the presence of the exciton. Our analytical results are in good agreement with those obtained by other methods including numerical approaches. Estimates of the expected experimental values are provided for realistic AGNR.

  1. Graphite filter atomizer in atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Katskov, Dmitri A.

    2007-09-01

    Graphite filter atomizers (GFA) for electrothermal atomic absorption spectrometry (ETAAS) show substantial advantages over commonly employed electrothermal vaporizers and atomizers, tube and platform furnaces, for direct determination of high and medium volatility elements in matrices associated with strong spectral and chemical interferences. Two factors provide lower limits of detection and shorter determination cycles with the GFA: the vaporization area in the GFA is separated from the absorption volume by a porous graphite partition; the sample is distributed over a large surface of a collector in the vaporization area. These factors convert the GFA into an efficient chemical reactor. The research concerning the GFA concept, technique and analytical methodology, carried out mainly in the author's laboratory in Russia and South Africa, is reviewed. Examples of analytical applications of the GFA in AAS for analysis of organic liquids and slurries, bio-samples and food products are given. Future prospects for the GFA are discussed in connection with analyses by fast multi-element AAS.

  2. Iron absorption by small intestine of chickens.

    PubMed

    Sáiz, M P; Martí, M T; Mitjavila, M T; Planas, J

    1993-01-01

    Iron (Fe) absorption by three segments (duodenum, jejunum, and ileum) of the small intestine of chickens was studied by a perfusion technique in vivo in closed circuit using 59Fe Cl3 and was related to the histological characteristics of each segment. The serosal transfers of Fe for the duodenum and jejunum were the same (14%/cm), but significantly different (p < 0.05) from those of the ileum (9%/cm), which may be explained by the morphological and histological properties of the gut of chickens. However, the presence of Fe in blood and in liver was significantly lower after perfusion of the jejunum and ileum than after perfusion of the duodenum. It is concluded that chickens show an early adaptation of small intestine to Fe absorption in response to the considerable loss of Fe suffered during the laying process.

  3. EVIDENCE FOR PHOTOIONIZATION-DRIVEN BROAD ABSORPTION LINE VARIABILITY

    SciTech Connect

    Wang, Tinggui; Yang, Chenwei; Wang, Huiyuan; Ferland, Gary

    2015-12-01

    We present a qualitative analysis of the variability of quasar broad absorption lines using the large multi-epoch spectroscopic data set of the Sloan Digital Sky Survey Data Release 10. We confirm that variations of absorption lines are highly coordinated among different components of the same ion or the same absorption component of different ions for C iv, Si iv, and N v. Furthermore, we show that the equivalent widths (EWs) of the lines decrease or increase statistically when the continuum brightens or dims. This is further supported by the synchronized variations of emission and absorption-line EWs when the well-established intrinsic Baldwin effect for emission lines is taken into account. We find that the emergence of an absorption component is usually accompanied by the dimming of the continuum while the disappearance of an absorption-line component is accompanied by the brightening of the continuum. This suggests that the emergence or disappearance of a C iv absorption component is only the extreme case, when the ionic column density is very sensitive to continuum variations or the continuum variability the amplitude is larger. These results support the idea that absorption-line variability is driven mainly by changes in the gas ionization in response to continuum variations, that the line-absorbing gas is highly ionized, and in some extreme cases, too highly ionized to be detected in UV absorption lines. Due to uncertainties in the spectroscopic flux calibration, we cannot quantify the fraction of quasars with asynchronized continuum and absorption-line variations.

  4. Water vapor absorption of carbon dioxide laser radiation

    NASA Technical Reports Server (NTRS)

    Shumate, M. S.; Menzies, R. T.; Margolis, J. S.; Rosengren, L.-G.

    1976-01-01

    An optoacoustic detector or spectrophone has been used to perform detailed measurements of the absorptivity of mixtures of water vapor in air. A (C-12) (O-16)2 laser was used as the source, and measurements were made at forty-nine different wavelengths from 9.2 to 10.7 microns. The details of the optoacoustic detector and its calibration are presented, along with a discussion of its performance characteristics. The results of the measurements of water vapor absorption show that the continuum absorption in the wavelength range covered is 5-10% lower than previous measurements.

  5. Flameless atomic-absorption determination of gold in geological materials

    USGS Publications Warehouse

    Meier, A.L.

    1980-01-01

    Gold in geologic material is dissolved using a solution of hydrobromic acid and bromine, extracted with methyl isobutyl ketone, and determined using an atomic-absorption spectrophotometer equipped with a graphite furnace atomizer. A comparison of results obtained by this flameless atomic-absorption method on U.S. Geological Survey reference rocks and geochemical samples with reported values and with results obtained by flame atomic-absorption shows that reasonable accuracy is achieved with improved precision. The sensitivity, accuracy, and precision of the method allows acquisition of data on the distribution of gold at or below its crustal abundance. ?? 1980.

  6. Extraordinary absorption of sound in porous lamella-crystals

    PubMed Central

    Christensen, J.; Romero-García, V.; Picó, R.; Cebrecos, A.; de Abajo, F. J. García; Mortensen, N. A.; Willatzen, M.; Sánchez-Morcillo, V. J.

    2014-01-01

    We present the design of a structured material supporting complete absorption of sound with a broadband response and functional for any direction of incident radiation. The structure which is fabricated out of porous lamellas is arranged into a low-density crystal and backed by a reflecting support. Experimental measurements show that strong all-angle sound absorption with almost zero reflectance takes place for a frequency range exceeding two octaves. We demonstrate that lowering the crystal filling fraction increases the wave interaction time and is responsible for the enhancement of intrinsic material dissipation, making the system more absorptive with less material. PMID:24728322

  7. The C2H, C2, and CN electronic absorption bands in the carbon star HD 19557

    NASA Technical Reports Server (NTRS)

    Goebel, J. H.; Bregman, J. D.; Cooper, D. M.; Goorvitch, D.; Langhoff, S. R.; Witteborn, F. C.

    1983-01-01

    Infrared spectrophotometry of the R-type carbon star HD 19557 is presented. Two unusual spectroscopic features are seen: a 3.1 micron band is lacking and a 2.8 micron band is present. Identifications are proposed for three previously unreported stellar absorption bands with electronic sequences of C2, CN, and C2H. The latter is proposed to be responsible for the 2.8 micron feature. The atmospheric structure of the star is studied with synthetic spectra, and an effective temperature between 2600 K and 3000 K is suggested. No SiC emission is seen at 11.3 microns, indicating that grain formation is not a viable process around the star. The lack of dust in R stars may suggest a salient difference between R and N types.

  8. UV-Visible Absorption Spectroscopy Enhanced X-ray Crystallography at Synchrotron and X-ray Free Electron Laser Sources.

    PubMed

    Cohen, Aina E; Doukov, Tzanko; Soltis, Michael S

    2016-01-01

    This review describes the use of single crystal UV-Visible Absorption micro-Spectrophotometry (UV-Vis AS) to enhance the design and execution of X-ray crystallography experiments for structural investigations of reaction intermediates of redox active and photosensitive proteins. Considerations for UV-Vis AS measurements at the synchrotron and associated instrumentation are described. UV-Vis AS is useful to verify the intermediate state of an enzyme and to monitor the progression of reactions within crystals. Radiation induced redox changes within protein crystals may be monitored to devise effective diffraction data collection strategies. An overview of the specific effects of radiation damage on macromolecular crystals is presented along with data collection strategies that minimize these effects by combining data from multiple crystals used at the synchrotron and with the X-ray free electron laser.

  9. Absorption and Metabolism of Xanthophylls

    PubMed Central

    Kotake-Nara, Eiichi; Nagao, Akihiko

    2011-01-01

    Dietary carotenoids, especially xanthophylls, have attracted significant attention because of their characteristic biological activities, including anti-allergic, anti-cancer, and anti-obese actions. Although no less than forty carotenoids are ingested under usual dietary habits, only six carotenoids and their metabolites have been found in human tissues, suggesting selectivity in the intestinal absorption of carotenoids. Recently, facilitated diffusion in addition to simple diffusion has been reported to mediate the intestinal absorption of carotenoids in mammals. The selective absorption of carotenoids may be caused by uptake to the intestinal epithelia by the facilitated diffusion and an unknown excretion to intestinal lumen. It is well known that β-carotene can be metabolized to vitamin A after intestinal absorption of carotenoids, but little is known about the metabolic transformation of non provitamin A xanthophylls. The enzymatic oxidation of the secondary hydroxyl group leading to keto-carotenoids would occur as a common pathway of xanthophyll metabolism in mammals. This paper reviews the absorption and metabolism of xanthophylls by introducing recent advances in this field. PMID:21747746

  10. Determination of tungsten in niobium-tantalum, vanadium and molybdenum bearing geological samples using derivative spectrophotometry and ICP-AES.

    PubMed

    Padmasubashini, V; Ganguly, M K; Satyanarayana, K; Malhotra, R K

    1999-10-01

    Two different procedures, one using derivative spectrophotometry and another using inductively coupled plasma atomic emission spectrometry (ICP-AES) have been developed for the determination of tungsten in niobate-tantalates, tin slag samples, ores, concentrates and vanadium and molybdenum bearing geological materials. In the first method involving derivative spectrophotometry, 0.05-0.5 g of the sample is fused with sodium hydroxide, the tungsten is extracted by leaching the melt with distilled water and estimated as thiocyanate using a second derivative spectrophotometric method in the presence of interferents, i.e. Nb, Mo and V, without separating them. Mixtures of tungsten with V, Nb and Mo are used for standardizing the various parameters like zero-crossing wavelength, wavelength range, etc. Tolerance limits for V, Nb and Mo have also been evaluated. In the second method involving ICP-AES, 0.05-0.5 g of sample is fused with KHSO(4) to a clear melt and dissolved in ammonium oxalate solution. Ammonium hydroxide precipitation is then carried out to separate Nb and Ta as hydroxides and the filtrate is boiled with nitric acid to destroy the oxalates before aspiration into the plasma for measurement of tungsten values by ICP-AES using the 207.911 nm emission line. Both methods have been applied to niobate-tantalate and tin slag samples and the results obtained are reported in this paper. The values obtained by both methods are in good agreement with each other. The proposed methods have also been applied to the determination of tungsten in two Canadian Certified Reference Standards (CT-1 and MP-2) and the values obtained are in good agreement with the certified values and the R.S.D.% in case of the ICP-AES method varied from 1-2% at >1000 mug g(-1) level to 9.4% at the 20 mug g(-1) level whereas the R.S.D.% in case of the derivative method varied from 1 to 7.8%.

  11. Chirality dependence of the absorption cross section of carbon nanotubes.

    PubMed

    Vialla, Fabien; Roquelet, Cyrielle; Langlois, Benjamin; Delport, Géraud; Santos, Silvia Morim; Deleporte, Emmanuelle; Roussignol, Philippe; Delalande, Claude; Voisin, Christophe; Lauret, Jean-Sébastien

    2013-09-27

    The variation of the optical absorption of carbon nanotubes with their geometry has been a long-standing question at the heart of both metrological and applicative issues, in particular because optical spectroscopy is one of the primary tools for the assessment of the chiral species abundance of samples. Here, we tackle the chirality dependence of the optical absorption with an original method involving ultraefficient energy transfer in porphyrin-nanotube compounds that allows uniform photoexcitation of all chiral species. We measure the absolute absorption cross section of a wide range of semiconducting nanotubes at their S22 transition and show that it varies by up to a factor of 2.2 with the chiral angle, with type I nanotubes showing a larger absorption. In contrast, the luminescence quantum yield remains almost constant.

  12. Chirality Dependence of the Absorption Cross Section of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Vialla, Fabien; Roquelet, Cyrielle; Langlois, Benjamin; Delport, Géraud; Santos, Silvia Morim; Deleporte, Emmanuelle; Roussignol, Philippe; Delalande, Claude; Voisin, Christophe; Lauret, Jean-Sébastien

    2013-09-01

    The variation of the optical absorption of carbon nanotubes with their geometry has been a long-standing question at the heart of both metrological and applicative issues, in particular because optical spectroscopy is one of the primary tools for the assessment of the chiral species abundance of samples. Here, we tackle the chirality dependence of the optical absorption with an original method involving ultraefficient energy transfer in porphyrin-nanotube compounds that allows uniform photoexcitation of all chiral species. We measure the absolute absorption cross section of a wide range of semiconducting nanotubes at their S22 transition and show that it varies by up to a factor of 2.2 with the chiral angle, with type I nanotubes showing a larger absorption. In contrast, the luminescence quantum yield remains almost constant.

  13. 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

  14. Absorption and Direct Processes in Chaotic Wave Scattering

    SciTech Connect

    Mendez-Sanchez, R. A.; Baez, G.; Martinez-Mares, M.

    2010-12-21

    Recent results on the scattering of waves by chaotic systems with losses and direct processes are discussed. We start by showing the results without direct processes nor absorption. We then discuss systems with direct processes and lossy systems separately. Finally the discussion of systems with both direct processes and loses is given. We will see how the regimes of strong and weak absorption are modified by the presence of the direct processes.

  15. Enhanced absorption cycle computer model

    NASA Astrophysics Data System (ADS)

    Grossman, G.; Wilk, M.

    1993-09-01

    Absorption heat pumps have received renewed and increasing attention in the past two decades. The rising cost of electricity has made the particular features of this heat-powered cycle attractive for both residential and industrial applications. Solar-powered absorption chillers, gas-fired domestic heat pumps, and waste-heat-powered industrial temperature boosters are a few of the applications recently subjected to intensive research and development. The absorption heat pump research community has begun to search for both advanced cycles in various multistage configurations and new working fluid combinations with potential for enhanced performance and reliability. The development of working absorption systems has created a need for reliable and effective system simulations. A computer code has been developed for simulation of absorption systems at steady state in a flexible and modular form, making it possible to investigate various cycle configurations with different working fluids. The code is based on unit subroutines containing the governing equations for the system's components and property subroutines containing thermodynamic properties of the working fluids. The user conveys to the computer an image of his cycle by specifying the different subunits and their interconnections. Based on this information, the program calculates the temperature, flow rate, concentration, pressure, and vapor fraction at each state point in the system, and the heat duty at each unit, from which the coefficient of performance (COP) may be determined. This report describes the code and its operation, including improvements introduced into the present version. Simulation results are described for LiBr-H2O triple-effect cycles, LiCl-H2O solar-powered open absorption cycles, and NH3-H2O single-effect and generator-absorber heat exchange cycles. An appendix contains the user's manual.

  16. Breaking temporal symmetries for emission and absorption

    PubMed Central

    Hadad, Yakir; Soric, Jason C.; Alu, Andrea

    2016-01-01

    Time-reversal symmetries impose stringent constraints on emission and absorption. Antennas, from radiofrequencies to optics, are bound to transmit and receive signals equally well from the same direction, making a directive antenna prone to receive echoes and reflections. Similarly, in thermodynamics Kirchhoff’s law dictates that the absorptivity and emissivity are bound to be equal in reciprocal systems at equilibrium, e(ω,θ)=a(ω,θ), with important consequences for thermal management and energy applications. This bound requires that a good absorber emits a portion of the absorbed energy back to the source, limiting its overall efficiency. Recent works have shown that weak time modulation or mechanical motion in suitably designed structures may largely break reciprocity and time-reversal symmetry. Here we show theoretically and experimentally that a spatiotemporally modulated device can be designed to have drastically different emission and absorption properties. The proposed concept may provide significant advances for compact and efficient radiofrequency communication systems, as well as for energy harvesting and thermal management when translated to infrared frequencies. PMID:26984502

  17. Terahertz absorption of DNA decamer duplex.

    PubMed

    Li, Xiaowei; Globus, Tatiana; Gelmont, Boris; Salay, Luiz C; Bykhovski, Alexei

    2008-11-27

    This work combines experimental and theoretical approaches to investigate terahertz absorption spectra of the DNA formed by the sequence oligomer 5'-CCGGCGCCGG-3'. The three-dimensional structure of this self-complimentary DNA decamer has been well-studied, permitting us to perform direct identification of the low-frequency phonon modes associated with specific conformation and to conduct comprehensive computer simulations. Two modeling techniques, normal-mode analysis and nanosecond molecular dynamics with explicit solvent molecules, were employed to extract the low-frequency vibrational modes based on which the absorption spectra were calculated. The absorption spectra of the DNA decamer in aqueous solution were measured in the frequency range 10-25 cm(-1) using the terahertz Fourier transform infrared spectroscopy. Multiple well-resolved and reproducible resonance modes were observed. When calculated and experimental spectra were compared, the spectrum based on molecular dynamics simulations showed a better correlation with the experimental spectra than the one based on normal-mode analysis. These results demonstrate that there exist a considerable number of active low-frequency phonon modes in this short DNA duplex.

  18. Breaking temporal symmetries for emission and absorption

    NASA Astrophysics Data System (ADS)

    Hadad, Yakir; Soric, Jason C.; Alu, Andrea

    2016-03-01

    Time-reversal symmetries impose stringent constraints on emission and absorption. Antennas, from radiofrequencies to optics, are bound to transmit and receive signals equally well from the same direction, making a directive antenna prone to receive echoes and reflections. Similarly, in thermodynamics Kirchhoff's law dictates that the absorptivity and emissivity are bound to be equal in reciprocal systems at equilibrium, e(ω,θ)=a(ω,θ), with important consequences for thermal management and energy applications. This bound requires that a good absorber emits a portion of the absorbed energy back to the source, limiting its overall efficiency. Recent works have shown that weak time modulation or mechanical motion in suitably designed structures may largely break reciprocity and time-reversal symmetry. Here we show theoretically and experimentally that a spatiotemporally modulated device can be designed to have drastically different emission and absorption properties. The proposed concept may provide significant advances for compact and efficient radiofrequency communication systems, as well as for energy harvesting and thermal management when translated to infrared frequencies.

  19. Absorption-heat-pump system

    DOEpatents

    Grossman, G.; Perez-Blanco, H.

    1983-06-16

    An improvement in an absorption heat pump cycle is obtained by adding adiabatic absorption and desorption steps to the absorber and desorber of the system. The adiabatic processes make it possible to obtain the highest temperature in the absorber before any heat is removed from it and the lowest temperature in the desorber before heat is added to it, allowing for efficient utilization of the thermodynamic availability of the heat supply stream. The improved system can operate with a larger difference between high and low working fluid concentrations, less circulation losses, and more efficient heat exchange than a conventional system.

  20. Use of HPLC/UPLC-spectrophotometry for detection of formazan in in vitro Reconstructed human Tissue (RhT)-based test methods employing the MTT-reduction assay to expand their applicability to strongly coloured test chemicals.

    PubMed

    Alépée, N; Barroso, J; De Smedt, A; De Wever, B; Hibatallah, J; Klaric, M; Mewes, K R; Millet, M; Pfannenbecker, U; Tailhardat, M; Templier, M; McNamee, P

    2015-06-01

    A number of in vitro test methods using Reconstructed human Tissues (RhT) are regulatory accepted for evaluation of skin corrosion/irritation. In such methods, test chemical corrosion/irritation potential is determined by measuring tissue viability using the photometric MTT-reduction assay. A known limitation of this assay is possible interference of strongly coloured test chemicals with measurement of formazan by absorbance (OD). To address this, Cosmetics Europe evaluated use of HPLC/UPLC-spectrophotometry as an alternative formazan measurement system. Using the approach recommended by the FDA guidance for validation of bio-analytical methods, three independent laboratories established and qualified their HPLC/UPLC-spectrophotometry systems to reproducibly measure formazan from tissue extracts. Up to 26 chemicals were then tested in RhT test systems for eye/skin irritation and skin corrosion. Results support that: (1) HPLC/UPLC-spectrophotometry formazan measurement is highly reproducible; (2) formazan measurement by HPLC/UPLC-spectrophotometry and OD gave almost identical tissue viabilities for test chemicals not exhibiting colour interference nor direct MTT reduction; (3) independent of the test system used, HPLC/UPLC-spectrophotometry can measure formazan for strongly coloured test chemicals when this is not possible by absorbance only. It is therefore recommended that HPLC/UPLC-spectrophotometry to measure formazan be included in the procedures of in vitro RhT-based test methods, irrespective of the test system used and the toxicity endpoint evaluated to extend the applicability of these test methods to strongly coloured chemicals.

  1. Remote laser evaporative molecular absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Hughes, Gary B.; Lubin, Philip; Cohen, Alexander; Madajian, Jonathan; Kulkarni, Neeraj; Zhang, Qicheng; Griswold, Janelle; Brashears, Travis

    2016-09-01

    We describe a novel method for probing bulk molecular and atomic composition of solid targets from a distant vantage. A laser is used to melt and vaporize a spot on the target. With sufficient flux, the spot temperature rises rapidly, and evaporation of surface materials occurs. The melted spot creates a high-temperature blackbody source, and ejected material creates a plume of surface materials in front of the spot. Molecular and atomic absorption occurs as the blackbody radiation passes through the ejected plume. Bulk molecular and atomic composition of the surface material is investigated by using a spectrometer to view the heated spot through the ejected plume. The proposed method is distinct from current stand-off approaches to composition analysis, such as Laser-Induced Breakdown Spectroscopy (LIBS), which atomizes and ionizes target material and observes emission spectra to determine bulk atomic composition. Initial simulations of absorption profiles with laser heating show great promise for Remote Laser-Evaporative Molecular Absorption (R-LEMA) spectroscopy. The method is well-suited for exploration of cold solar system targets—asteroids, comets, planets, moons—such as from a spacecraft orbiting the target. Spatial composition maps could be created by scanning the surface. Applying the beam to a single spot continuously produces a borehole or trench, and shallow subsurface composition profiling is possible. This paper describes system concepts for implementing the proposed method to probe the bulk molecular composition of an asteroid from an orbiting spacecraft, including laser array, photovoltaic power, heating and ablation, plume characteristics, absorption, spectrometry and data management.

  2. Improved 20- to 32-GHz atmospheric absorption model

    NASA Astrophysics Data System (ADS)

    Cruz Pol, Sandra L.; Ruf, Christopher S.; Keihm, Stephen J.

    1998-09-01

    An improved model for the absorption of the atmosphere near the 22-GHz water vapor line is presented. The Van Vleck-Weisskopf line shape is used with a simple parameterized version of the model from Liebe et al. [1993] for the water vapor absorption spectra and a scaling of the model from Rosenkranz [1993] for the 20- to 32-GHz oxygen absorption. Radiometric brightness temperature measurements from two sites of contrasting climatological properties, San Diego, California, and West Palm Beach, Florida, were used as ground truth for comparison with in situ radiosonde-derived brightness temperatures under clear-sky conditions. Estimation of the new model's four parameters, related to water vapor line strength, line width and continuum absorption, and far-wing oxygen absorption, was performed using the Newton-Raphson inversion method. Improvements to the water vapor line strength and line width parameters are found to be statistically significant. The accuracy of the new absorption model is estimated to be 3% between 20 and 24 GHz, degrading to 8% near 32 GHz. In addition, the Hill line shape asymmetry ratio was evaluated in several currently used models to show the agreement of the data with Van Vleck-Weisskopf based models and to rule out water vapor absorption models near 22 GHz given by Waters [1976] and Ulaby et al. [1981], which are based on the Gross line shape.

  3. Absorption of ethanol by steam-exploded corn stalk.

    PubMed

    Fei, Chi; Hongzhang, Chen

    2009-02-01

    The aim of this work is to study the feasibility of using a low-cost biomass absorbent steam-exploded corn stalk (SECS) to absorb ethanol in its production by fermentation. Measurement of many the physical properties of SECS showed its specific surface area was about 214 m(2)/g and it had a good structure for absorption. Some influencing parameters of using SECS to absorb ethanol in water were studied. Second-order and parabolic diffusion equations excellently described the kinetics of absorption for ethanol. Its absorption isotherm was well described by an improved BET equation, indicating that it was a process of polymolecular layer absorption and had phenomena similar to capillary coacervation. Mesh size did not significantly affect absorptivity, but absorbency decreased with temperature. Absorptivity of SECS for ethanol was compared to that of other absorbents: at 30 degrees C and 5% initial ethanol, the absorptivity of SECS for ethanol at 5h was 92 mg/g. When inactivated through use, SECS can continue to be used as an substrate to produce more ethanol, thus avoiding pollution through discarding.

  4. Fibre optic spectrophotometry for the in vitro evaluation of ultraviolet radiation (UVR) spectral transmittance of rabbit corneas.

    PubMed

    Walsh, J E; Bergmanson, J P G; Koehler, L V; Doughty, M J; Fleming, D P; Harmey, J H

    2008-03-01

    A fibre optic spectrophotometer front-end system for measuring corneas to overcome shortcomings associated with existing instruments was tested. The system allowed prompt measurement postmortem, minimizing beam pathlength to reduce the effects of scatter and unwanted refraction and eliminated optical interfaces and cuvette media. Rabbit corneas were excised immediately postmortem and placed on a detecting fibre optic coupled to an Ocean Optics spectrophotometer and illuminated by a deuterium-halogen source. The compact instrument with its small beam size allowed tissue profiling at test points across the corneal surface and efficient interchange for comparison of different tissues. This simplified system operation allowed rapid tissue altering to study induced changes on transmittance. The corneal transmittance data showed a consistent sharp cut-off at 320 nm in the ultraviolet radiation (UVR) spectrum, which decayed rapidly from postmortem swelling. Inter- and intra-corneal consistency was demonstrated by comparing data from different regions of the same cornea and those from opposite eyes. Changes to the spectra, particularly in the UVB below 300 nm, were evident when the corneal epithelium was removed, indicating that this layer is not the only corneal UVR filter. The new system reduced much of the variability associated with previous methods, as it rapidly measured corneal transmittance postmortem. Data are in broad agreement with published transmittance curves. The removal of the corneal epithelium revealed a substantial stromal contribution to the overall corneal UVR absorption, suggesting that corneas with pathologically or iatrogenically thinned stromas are less effective UVR blockers.

  5. On the nature of absorption features toward nearby stars

    NASA Astrophysics Data System (ADS)

    Kohl, S.; Czesla, S.; Schmitt, J. H. M. M.

    2016-06-01

    Context. Diffuse interstellar absorption bands (DIBs) of largely unknown chemical origin are regularly observed primarily in distant early-type stars. More recently, detections in nearby late-type stars have also been claimed. These stars' spectra are dominated by stellar absorption lines. Specifically, strong interstellar atomic and DIB absorption has been reported in τ Boo. Aims: We test these claims by studying the strength of interstellar absorption in high-resolution TIGRE spectra of the nearby stars τ Boo, HD 33608, and α CrB. Methods: We focus our analysis on a strong DIB located at 5780.61 Å and on the absorption of interstellar Na. First, we carry out a differential analysis by comparing the spectra of the highly similar F-stars, τ Boo and HD 33608, whose light, however, samples different lines of sight. To obtain absolute values for the DIB absorption, we compare the observed spectra of τ Boo, HD 33608, and α CrB to PHOENIX models and carry out basic spectral modeling based on Voigt line profiles. Results: The intercomparison between τ Boo and HD 33608 reveals that the difference in the line depth is 6.85 ± 1.48 mÅ at the DIB location which is, however, unlikely to be caused by DIB absorption. The comparison between PHOENIX models and observed spectra yields an upper limit of 34.0 ± 0.3 mÅ for any additional interstellar absorption in τ Boo; similar results are obtained for HD 33608 and α CrB. For all objects we derive unrealistically large values for the radial velocity of any presumed interstellar clouds. In τ Boo we find Na D absorption with an equivalent width of 0.65 ± 0.07 mÅ and 2.3 ± 0.1 mÅ in the D2 and D1 lines. For the other Na, absorption of the same magnitude could only be detected in the D2 line. Our comparisons between model and data show that the interstellar absorption toward τ Boo is not abnormally high. Conclusions: We find no significant DIB absorption in any of our target stars. Any differences between modeled and

  6. 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

  7. Episodes of apnea and bradycardia in the preterm newborn: impact on cerebral oxygenation measured by near-infrared spectrophotometry

    NASA Astrophysics Data System (ADS)

    Van Huffel, Sabine; Craemers, Johan; Lenaerts, Bart; Daniels, Hans; Naulaers, Gunnar; Casaer, Paul

    1998-12-01

    The objective of this study is to evaluate the effect of episodes of apneas and/or mild bradycardia (heart rate decreases of 10 to 20% or more) on cerebral oxyhemoglobin (HbO2) and reduced hemoglobin (Hb) concentration as measured by Near Infrared Spectrophotometry (NIRS). Measurements were carried out on 7 preterm infants who experienced apneic and bradycardiac events. It is shown how to characterize these events using time-frequency analysis. In addition to NIRS (performed with a NIRO-500 from Hamamatsu, Japan), the heart rate, ECG, peripheral arterial oxygen saturation (measured at the foot) and respiration (abdominal and thoracic pressure, and nasal airflow) were continuously recorded. The impact of apneic events and periodic breathing on these measurements reveals the clinical relevance of NIRS. In particular, we investigate whether these changes in heart rate and respiration also influence HbO2 and reduced Hb concentration in neonatal brain. These changes are characterized, as well as their relationships with the other simultaneously recorded signals such as peripheral arterial oxygen saturation.

  8. Molybdenum blue spectrophotometry for trace arsenic in ground water using a soluble membrane filter and calcium carbonate column.

    PubMed

    Okazaki, Takuya; Wang, Wenjing; Kuramitz, Hideki; Hata, Noriko; Taguchi, Shigeru

    2013-01-01

    An improved molybdenum blue spectrophotometry using a soluble membrane filter and CaCO(3)-column was proposed for determining arsenic in drinking water supplied from ground water in the presence of phosphate. A 100 mL sample solution containing 0.5 - 10 μg arsenic was passed through a CaCO(3)-column to remove phosphate, arsenate (As(V)). Arsenite (As(III)) which was not retained on the column was oxidized to As(V). As(V) was converted into a heteropolymolybdenum blue anion. The blue anion was collected on a membrane filter as an ion-associate with n-dodecyltrimethylammonium ion by filtration. The filter was dissolved in 2 mL of 2-methoxyethanol. The absorbance of the solution was measured at 810 nm against a reagent blank. Total inorganic arsenic was determined by reducing As(V) to As(III) before the column treatment. The RSDs for 10 μg L(-1) of As(III) and As(V) were 2.9%. Phosphate 0.2 mg L(-1) (as P) and iron 0.1 mg L(-1) did not interfere with the determination of 10 μg L(-1) arsenic. The proposed method was successfully applied to ground waters.

  9. Inter-laboratory verification of European pharmacopoeia monograph on derivative spectrophotometry method and its application for chitosan hydrochloride.

    PubMed

    Marković, Bojan; Ignjatović, Janko; Vujadinović, Mirjana; Savić, Vedrana; Vladimirov, Sote; Karljiković-Rajić, Katarina

    2015-01-01

    Inter-laboratory verification of European pharmacopoeia (EP) monograph on derivative spectrophotometry (DS) method and its application for chitosan hydrochloride was carried out on two generation of instruments (earlier GBC Cintra 20 and current technology TS Evolution 300). Instruments operate with different versions of Savitzky-Golay algorithm and modes of generating digital derivative spectra. For resolution power parameter, defined as the amplitude ratio A/B in DS method EP monograph, comparable results were obtained only with algorithm's parameters smoothing points (SP) 7 and the 2nd degree polynomial and those provided corresponding data with other two modes on TS Evolution 300 Medium digital indirect and Medium digital direct. Using quoted algorithm's parameters, the differences in percentages between the amplitude ratio A/B averages, were within accepted criteria (±3%) for assay of drug product for method transfer. The deviation of 1.76% for the degree of deacetylation assessment of chitosan hydrochloride, determined on two instruments, (amplitude (1)D202; the 2nd degree polynomial and SP 9 in Savitzky-Golay algorithm), was acceptable, since it was within allowed criteria (±2%) for assay deviation of drug substance, for method transfer in pharmaceutical analyses.

  10. Rapid determination of trace thiabendazole in apple juice utilizing dispersive liquid-liquid microextraction combined with fluorescence spectrophotometry.

    PubMed

    Li, Wei; Wang, Yuning; Huang, Limin; Wu, Ting; Hu, Huilian; Du, Yiping

    2015-09-01

    Food safety has become a large concern and prompts an urgent need for the development of rapid, simple and sensitive analytical methods that can monitor pesticide residues in foods. This study aimed to provide a method for quantitative determination of trace thiabendazole in apple juice. Due to its high sensitivity and selectivity, fluorescence spectrophotometry was utilized as a front end to dispersive liquid-liquid microextraction (DLLME). The experimental parameters that influenced the extraction were systematically investigated. Under optimum conditions, the whole procedure, including DLLME and analysis of one sample, was carried out within 5 min, and linearity was found in the 5-50 µg/L range with a correlation coefficient (r) of 0.9987. The limit of detection value was 2.2 µg/L. Good reproducibility was achieved based with a less than 4.5% relative standard deviation (RSD) for five replicates at different sample concentrations. This method was shown to be suitable for rapid and sensitive quantification of thiabendazole in apple juice.

  11. Study of monoprotic acid-base equilibria in aqueous micellar solutions of nonionic surfactants using spectrophotometry and chemometrics.

    PubMed

    Babamoradi, Hamid; Abdollahi, Hamid

    2015-10-05

    Many studies have shown the distribution of solutes between aqueous phase and micellar pseudo-phase in aqueous micellar solutions. However, spectrophotometric studies of acid-base equilibria in these media do not confirm such distribution because of the collinearity between concentrations of chemical species in the two phases. The collinearity causes the number of detected species to be equal to the number of species in a homogenous solution that automatically misinterpreted as homogeneity of micellar solutions, therefore the collinearity is often neglected. This interpretation is in contradiction to the distribution theory in micellar media that must be avoided. Acid-base equilibrium of an indicator was studied in aqueous micellar solutions of a nonionic surfactant to address the collinearity using UV/Visible spectrophotometry. Simultaneous analysis (matrix augmentation) of the equilibrium and solvation data was applied to eliminate the collinearity from the equilibrium data. A model was then suggested for the equilibrium that was fitted to the augmented data to estimate distribution coefficients of the species between the two phases. Moreover, complete resolution of concentration and spectral profiles of species in each phase was achieved.

  12. Qualitative and quantitative evaluation of chrysotile and crocidolite fibres with infrared spectrophotometry: application to asbestos-cement products.

    PubMed

    Valerio, F; Balducci, D

    1989-01-01

    Infrared (IR) spectrophotometry allows simple and rapid qualitative and quantitative evaluations of different types of asbestos, as well as of other inorganic particles. In particular, chrysotile and crocidolite have characteristic IR spectra, and optical density measurements in the 2710 nm band for chrysotile and the 12820 nm band for crocidolite permit the quantitative evaluation of each fibre either alone or in mixtures. IR spectra also provide information on changes in fibre structure and in chemical composition as the result, for example, of thermal treatment or acid leaching. The analytical method that we have developed can detect amounts as small as 0.1 mg of fibre in a 300-mg disk of potassium bromide using a low-cost IR spectrophotometer. The use of a Fourier transform IR spectrophotometer dramatically improves the sensitivity and selectivity. Computer-assisted analysis of spectra offers the possibility of reducing matrix interference and of comparing different spectra. The application of the IR technique to asbestos-cement products and insulating materials is described.

  13. Measuring Binding Affinity of Protein-Ligand Interaction Using Spectrophotometry: Binding of Neutral Red to Riboflavin-Binding Protein

    ERIC Educational Resources Information Center

    Chenprakhon, Pirom; Sucharitakul, Jeerus; Panijpan, Bhinyo; Chaiyen, Pimchai

    2010-01-01

    The dissociation constant, K[subscript d], of the binding of riboflavin-binding protein (RP) with neutral red (NR) can be determined by titrating RP to a fixed concentration of NR. Upon adding RP to the NR solution, the maximum absorption peak of NR shifts to 545 nm from 450 nm for the free NR. The change of the absorption can be used to determine…

  14. Correlation of solar energetic protons and polar cap absorption

    NASA Astrophysics Data System (ADS)

    Patterson, J. D.; Armstrong, T. P.; Laird, C. M.; Detrick, D. L.; Weatherwax, A. T.

    2001-01-01

    This study shows the results of a model of polar cap absorption events (PCAs) using solar energetic proton flux as an input. The proton data are recorded by the Charged Particle Measurement Experiment (CPME) on board the IMP 8 satellite and are collected by the Applied Physics Laboratory at Johns Hopkins University. The IMP 8 satellite orbits the Earth at distances between 30 and 35 Earth radii, which places it in the solar energetic particle environment throughout most of its orbit. It has been shown in previous studies that these solar energetic particles have direct and immediate access to the polar atmosphere [Reid, 1970]. Our model shows that the majority of the ionization resulting from the influx of solar energetic protons occurs in the altitude range from ~50-90 km. Excess ionization at these altitudes causes enhanced absorption of cosmic HF radio waves. The levels of absorption used for comparison in this study were measured directly by the riometer at South Pole station, Antarctica. The results show a very strong correlation between the incident proton flux and measured path-integrated cosmic HF radio noise absorption for significant events, involving absorptions greater than 1.0 dB. For absorption levels lower than this it is obvious that other phenomena dominate. For HF radio waves the primary contributors to PCA are protons with energies near 20 MeV. This study extends the correlated observations of interplanetary particles and PCA throughout a 9-year period. The close quantitative agreement between the measured and calculated values of absorption supports the validity of the assumptions and suppositions made by this model. The data also suggest a method by which the path-integrated cosmic noise absorption may be used to probe the E and D layers of the ionosphere to determine the effective ion-electron recombination coefficients within these regions.

  15. Migrant labor absorption in Malaysia.

    PubMed

    Nayagam, J

    1992-01-01

    The use of migrant workers to ease labor shortages caused by rapid industrialization in Malaysia during the twentieth century is examined. "This paper will focus on: (1) the extent, composition and distribution of migrant workers; (2) the labor shortage and absorption of migrant workers; and (3) the role of migrant workers in the government's economic restructuring process."

  16. Quasistellar Objects: Intervening Absorption Lines

    NASA Astrophysics Data System (ADS)

    Charlton, J.; Churchill, C.; Murdin, P.

    2000-11-01

    Every parcel of gas along the line of sight to a distant QUASAR will selectively absorb certain wavelengths of continuum light of the quasar due to the presence of the various chemical elements in the gas. Through the analysis of these quasar absorption lines we can study the spatial distributions, motions, chemical enrichment and ionization histories of gaseous structures from REDSHIFT five unti...

  17. Oxygen Absorption in Cooling Flows.

    PubMed

    Buote

    2000-04-01

    The inhomogeneous cooling flow scenario predicts the existence of large quantities of gas in massive elliptical galaxies, groups, and clusters that have cooled and dropped out of the flow. Using spatially resolved, deprojected X-ray spectra from the ROSAT PSPC, we have detected strong absorption over energies approximately 0.4-0.8 keV intrinsic to the central approximately 1&arcmin; of the galaxy NGC 1399, the group NGC 5044, and the cluster A1795. These systems have among the largest nearby cooling flows in their respective classes and low Galactic columns. Since no excess absorption is indicated for energies below approximately 0.4 keV, the most reasonable model for the absorber is warm, collisionally ionized gas with T=105-106 K in which ionized states of oxygen provide most of the absorption. Attributing the absorption only to ionized gas reconciles the large columns of cold H and He inferred from Einstein and ASCA with the lack of such columns inferred from ROSAT and also is consistent with the negligible atomic and molecular H inferred from H i and CO observations of cooling flows. The prediction of warm ionized gas as the product of mass dropout in these and other cooling flows can be verified by Chandra and X-Ray Multimirror Mission.

  18. Neutron Absorption in Geological Material

    NASA Astrophysics Data System (ADS)

    Løvhøiden, G.; Andersen, E.

    1990-01-01

    Thermal neutron absorption cross section of geological samples is determined with the steady state neutron source method. Cross section measurements of North Sea sediments demonstrate that also materials with high contents of clay minerals may be investigated with the steady state method.

  19. Ultraviolet and Light Absorption Spectrometry.

    ERIC Educational Resources Information Center

    Hargis, L. G.; Howell, J. A.

    1984-01-01

    Reviews developments in ultraviolet and light absorption spectrometry from December 1981 through November 1983, focusing on the chemistry involved in developing suitable reagents, absorbing systems, and methods of determination, and on physical aspects of the procedures. Includes lists of spectrophotometric methods for metals, non-metals, and…

  20. Light Absorption By Coated Soot

    NASA Astrophysics Data System (ADS)

    Sedlacek, A. J.; Lee, J.; Onasch, T. B.; Davidovits, P.; Cross, E. S.

    2009-12-01

    The contribution of aerosol absorption on direct radiative forcing is still an active area of research, in part, because aerosol extinction is dominated by light scattering and, in part, because the primary absorbing aerosol of interest, soot, exhibits complex aging behavior that alters its optical properties. The consequences of this can be evidenced by the work of Ramanathan and Carmichael (2008) who suggest that incorporating the atmospheric heating due to brown clouds will increase black carbon (BC) radiative forcing from the IPCC best estimate of 0.34 Wm-2 (±0.25 Wm-2) (IPCC 2007) to 0.9 Wm-2. This noteworthy degree of the uncertainty is due largely to the interdependence of BC optical properties on particle mixing state and aggregate morphology, each of which changes as the particle ages in the atmosphere and becomes encapsulated within a coating of inorganic and/or organic substances. With the advent of techniques that can directly measure aerosol light absorption without influences due to collection substrate or light scattering (e.g., photoacoustic spectroscopy (Arnott et al., 2005; Lack et al., 2006) and photothermal interferometry (Sedlacek and Lee 2007)) the potential exists for quantifying this interdependence. In July 2008, a laboratory-based measurement campaign, led by Boston College and Aerodyne, was initiated to begin addressing this interdependence. To achieve this objective measurements of both the optical and physical properties of flame-generated soot under nascent, coated and denuded conditions were conducted. In this paper, light absorption by dioctyl sebacate (DOS) encapsulated soot and sulfuric acid coated soot using the technique of photothermal interferometry will be presented. In the case of DOS-coated soot, a monotonic increase in light absorption as a function DOS coating thickness to nearly 100% is observed. This observation is consistent with a coating-induced amplification in particle light absorption. (Bond et al. 2006) However