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Sample records for absorption spectrophotometry technique

  1. Determination of Lead in Blood by Atomic Absorption Spectrophotometry1

    PubMed Central

    Selander, Stig; Cramér, Kim

    1968-01-01

    Lead in blood was determined by atomic absorption spectrophotometry, using a wet ashing procedure and a procedure in which the proteins were precipitated with trichloroacetic acid. In both methods the lead was extracted into isobutylmethylketone before measurement, using ammonium pyrrolidine dithiocarbamate as chelator. The simpler precipitation procedure was shown to give results identical with those obtained with the ashing technique. In addition, blood specimens were examined by the precipitation method and by spectral analysis, which method includes wet ashing of the samples, with good agreement. All analyses were done on blood samples from `normal' persons or from lead-exposed workers, and no additions of inorganic lead were made. The relatively simple protein precipitation technique gave accurate results and is suitable for the large-scale control of lead-exposed workers. PMID:5663425

  2. Determination of Lead in Urine by Atomic Absorption Spectrophotometry1

    PubMed Central

    Selander, Stig; Cramé, Kim

    1968-01-01

    A method for the determination of lead in urine by means of atomic absorption spectrophotometry (AAS) is described. A combination of wet ashing and extraction with ammonium pyrrolidine dithiocarbamate into isobutylmethylketone was used. The sensitivity was about 0·02 μg./ml. for 1% absorption, and the detection limit was about 0·02 μg./ml. with an instrumental setting convenient for routine analyses of urines. Using the scale expansion technique, the detection limit was below 0·01 μg./ml., but it was found easier to determine urinary lead concentrations below 0·05 μg./ml. by concentrating the lead in the organic solvent by increasing the volume of urine or decreasing that of the solvent. The method was applied to fresh urines, stored urines, and to urines, obtained during treatment with chelating agents, of patients with lead poisoning. Urines with added inorganic lead were not used. The results agreed well with those obtained with a colorimetric dithizone extraction method (r = 0·989). The AAS method is somewhat more simple and allows the determination of smaller lead concentrations. PMID:5647975

  3. [Study on lead absorption in pumpkin by atomic absorption spectrophotometry].

    PubMed

    Li, Zhen-Xia; Sun, Yong-Dong; Chen, Bi-Hua; Li, Xin-Zheng

    2008-07-01

    A study was carried out on the characteristic of lead absorption in pumpkin via atomic absorption spectrophotometer. The results showed that lead absorption amount in pumpkin increased with time, but the absorption rate decreased with time; And the lead absorption amount reached the peak in pH 7. Lead and cadmium have similar characteristic of absorption in pumpkin.

  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. Estimation of calcium and magnesium in serum and urine by atomic absorption spectrophotometry

    PubMed Central

    Thin, Christian G.; Thomson, Patricia A.

    1967-01-01

    A method has been described for the estimation of calcium and magnesium in serum and urine using atomic absorption spectrophotometry. The precision and accuracy of the techniques have been determined and were found to be acceptable. The range of values for calcium and magnesium in the sera of normal adults was found to be: serum calcium (corrected to a specific gravity of 1·026) 8·38-10·08 mg. per 100 ml.; serum magnesium 1·83-2·43 mg. per 100 ml. PMID:5602562

  6. Determination of urinary manganese by the direct chelation-extraction method and flameless atomic absorption spectrophotometry.

    PubMed Central

    Watanabe, T; Tokunaga, R; Iwahana, T; Tati, M; Ikeda, M

    1978-01-01

    The direct chelation-extraction method, originally developed by Hessel (1968) for blood lead analysis, has been successfully applied to urinalysis for manganese. The analyses of 35 urine samples containing up to 100 microgram/1 of manganese from manganese-exposed workers showed that the data obtained by this method agree well with those by wet digestion-flame atomic absorption spectrophotometry and also by flameless atomic absorption spectrophotometry. PMID:629893

  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. 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.

  10. Determination of aluminum in biological fluids by furnace atomic absorption spectrophotometry.

    PubMed

    Johnson, K E; Treble, R G

    1992-01-01

    Detailed procedures were developed for the furnace atomic absorption spectrophotometry (FAAS) determination of aluminum (Al) in serum, urine, cerebrospinal fluid (CSF), and proportionated dialysate. Of particular note were the use of Mg (NO3)2.6H2O as a matrix modifier and the employment of the standard additions routine in analysis. The accuracy of the method(s) used is supported by work with assayed controls and by recovery studies. The use of a "clean room" was shown to be unnecessary. Normal serum, urine, and CSF Al ranges observed were 4.8-8.9, 5.1-9.1, and 1.0-5.8 micrograms L-1 respectively.

  11. 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.

  12. Micro determination of plasma and erythrocyte copper by atomic absorption spectrophotometry

    PubMed Central

    Blomfield, Jeanette; Macmahon, R. A.

    1969-01-01

    The free and total plasma copper and total erythrocyte copper levels have been determined by simple, yet sensitive and highly specific methods, using atomic absorption spectrophotometry. For total copper determination, the copper was split from its protein combination in plasma or red cells by the action of hydrochloric acid at room temperature. The liberated copper was chelated by ammonium pyrrolidine dithiocarbamate and extracted into n-butyl acetate by shaking and the organic extract was aspirated into the atomic absorption spectrophotometer flame. The entire procedure was carried out in polypropylene centrifuge tubes, capped during shaking. For the free plasma copper measurement the hydrochloric acid step was omitted. Removal of the plasma or erythrocyte proteins was found to be unnecessary, and, in addition, the presence of trichloracetic acid caused an appreciable lowering of absorption. Using a double-beam atomic absorption spectrophotometer and scale expansion × 10, micro methods have been derived for determining the total copper of plasma or erythrocytes with 0·1 ml of sample, and the free copper of plasma with 0·5 ml. The macro plasma copper method requires 2 ml of plasma and is suitable for use with single-beam atomic absorption spectrophotometers. With blood from 50 blood donors, normal ranges of plasma and erythrocyte copper have been determined. PMID:5776543

  13. 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.

  14. 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.

  15. Determination of cadmium in urine by extraction and flameless atomic-absorption spectrophotometry Comparison of urine from smokers and non-smokers of different sex and age.

    PubMed

    Jawaid, M; Lind, B; Elinder, C G

    1983-07-01

    A method is presented for determining cadmium in urine by nameless atomic-absorption spectrophotometry after extraction. The sample is dried, ashed in the presence of nitric acid, and then the residue is dissolved in hydrochloric acid. Cadmium is extracted as its tetrahexylammonium iodide complex into methyl isobutyl ketone. The organic phase is analysed for cadmium by atomic-absorption spectrophotometry with electrothermal atomization. The median urinary excretion of cadmium for smokers aged 50-64 has been found to be 0.7 and 0.75 mug l . for males and females respectively, the values for non-smokers being 0.25 and 0.4mug l .

  16. 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…

  17. 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

  18. Determination of the absorption coefficient of chromophoric dissolved organic matter from underway spectrophotometry.

    PubMed

    Dall'Olmo, Giorgio; Brewin, Robert J W; Nencioli, Francesco; Organelli, Emanuele; Lefering, Ina; McKee, David; Röttgers, Rüdiger; Mitchell, Catherine; Boss, Emmanuel; Bricaud, Annick; Tilstone, Gavin

    2017-11-27

    Measurements of the absorption coefficient of chromophoric dissolved organic matter (ay) are needed to validate existing ocean-color algorithms. In the surface open ocean, these measurements are challenging because of low ay values. Yet, existing global datasets demonstrate that ay could contribute between 30% to 50% of the total absorption budget in the 400-450 nm spectral range, thus making accurate measurement of ay essential to constrain these uncertainties. In this study, we present a simple way of determining ay using a commercially-available in-situ spectrophotometer operated in underway mode. The obtained ay values were validated using independent collocated measurements. The method is simple to implement, can provide measurements with very high spatio-temporal resolution, and has an accuracy of about 0.0004 m -1 and a precision of about 0.0025 m -1 when compared to independent data (at 440 nm). The only limitation for using this method at sea is that it relies on the availability of relatively large volumes of ultrapure water. Despite this limitation, the method can deliver the ay data needed for validating and assessing uncertainties in ocean-colour algorithms.

  19. 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.

  20. On-line preconcentration and speciation of arsenic by flow injection hydride generation atomic absorption spectrophotometry.

    PubMed

    Narcise, Cristine Ingrid S; Coo, Lilibeth Dlc; Del Mundo, Florian R

    2005-12-15

    A flow injection-column preconcentration-hydride generation atomic absorption spectrophotometric (FI-column-HGAAS) method was developed for determining mug/l levels of As(III) and As(V) in water samples, with simultaneous preconcentration and speciation. The speciation scheme involved determining As(V) at neutral pH and As(III+V) at pH 12, with As(III) obtained by difference. The enrichment factor (EF) increased with increase in sample loading volume from 2.5 to 10ml, and for preconcentration using the chloride-form anion exchange column, EFs ranged from 5 to 48 for As(V) and 4 to 24 for As(III+V), with corresponding detection limits of 0.03-0.3 and 0.07-0.3mug/l. Linear concentration range (LCR) also varied with sample loading volume, and for a 5-ml sample was 0.3-5 and 0.2-8mug/l for As(V) and As(III+V), respectively. Sample throughput, which decreased with increase in sample volume, was 8-17 samples/h. For the hydroxide-form column, the EFS for 2.5-10ml samples were 3-23 for As(V) and 2-15 for As(III+V), with corresponding detection limits of 0.07-0.4 and 0.1-0.5mug/l. The LCR for a 5-ml sample was 0.3-10mug/l for As(V) and 0.2-20mug/l for As(III+V). Sample throughput was 10-20 samples/h. The developed method has been effectively applied to tap water and mineral water samples, with recoveries ranging from 90 to 102% for 5-ml samples passed through the two columns.

  1. 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…

  2. 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.

  3. Determination of Tetracycline in Pharmaceutical Preparation by Molecular and Atomic Absorption Spectrophotometry and High Performance Liquid Chromatography via Complex Formation with Au(III) and Hg(II) Ions in Solutions

    PubMed Central

    Abdulghani, Ahlam Jameel; Jasim, Hadi Hassan; Hassan, Abbas Shebeeb

    2013-01-01

    UV-visible and atomic spectrophotometry and HPLC techniques were applied for the determination of tetracycline (TC) in pharmaceutical preparations via complexation of the drug with Au(III) and Hg(II) ions in solutions. The mole ratio of TC to metal ions was 1 : 1. Maximum peak absorption at λ 425 and 320 nm for the two ions, respectively, was optimized at heating temperature 75°C for 15 minutes at pH = 4 followed by the extraction with ethyl acetate. The percentage of extraction and stability constants for the two complexes was 95.247, 95.335% and 2.518 × 104, 1.162 × 105 M−1, respectively. HPLC method was applied without extraction process. The analytical data obtained from direct calibration curves of UV-visible absorption, FAAS, and HPLC for Au(III) complexes were recovery (100.78, 104.85, and 101.777%, resp.); detection limits (0.7403, 0.0997, and 2.647 μg/ml, resp.); linearity (5–70, 5–30, and 10–150 μg/ml, resp.), and correlation coefficient (0.9991, 0.9967, and 0.9986, resp.). The analytical data obtained from direct calibration curves for Hg(II) complexes by UV-visible spectrophotometry and HPLC were recovery (100.95 and 102.000%, resp.); detection limits (0.5867 and 2.532 μg/ml, resp.); linearity (5–70 and 10–150 μg/ml, resp.); and correlation coefficients (0.9989 and 0.9997, resp.). PMID:23853607

  4. 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.

  5. Estimation of perimortal percent carboxy-heme in nonstandard postmortem specimens using analysis of carbon monoxide by GC/MS and iron by flame atomic absorption spectrophotometry.

    PubMed

    Middleberg, R A; Easterling, D E; Zelonis, S F; Rieders, F; Rieders, M F

    1993-01-01

    In decomposed, formalin-fixed, embalmed, exhumed, and some fire-dried cases in which normal blood is unavailable, the usual methods for determination of carboxyhemoglobin saturation frequently fail. To address these specimens, a method utilizing both gas chromatography/mass spectrometric (GC/MS) determination of carbon monoxide (CO) and flame atomic absorption spectrophotometry (FAAS) determination of iron (Fe), in the same specimen, was developed. The method is reported here, along with its application to seven pertinent forsensic death investigations. The CO analytical methodology involves acid liberation of the gas from the specimen aliquot in a headspace vial. After heating and equilibrating, a sample of the headspace vapor is injected into the GC/MS system with a gastight syringe. Quantitation is achieved by standard addition comparison utilizing the ideal gas law equation. Iron is quantified by FAAS analysis of the same aliquot used for the CO determination, following nitric acid digestion. The concentration is determined by comparison to a standard curve. A formula for determining the minimum percent carboxy-heme saturation was derived by using the ratio of the amount of CO to the amount of Fe in the aliquot analyzed. Tissue types analyzed include spleen, liver, muscle, dried blood, and unspecified decomposed tissue.

  6. 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.

  7. 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.

  8. 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…

  9. Differential absorption radar techniques: water vapor retrievals

    NASA Astrophysics Data System (ADS)

    Millán, Luis; Lebsock, Matthew; Livesey, Nathaniel; Tanelli, Simone

    2016-06-01

    Two radar pulses sent at different frequencies near the 183 GHz water vapor line can be used to determine total column water vapor and water vapor profiles (within clouds or precipitation) exploiting the differential absorption on and off the line. We assess these water vapor measurements by applying a radar instrument simulator to CloudSat pixels and then running end-to-end retrieval simulations. These end-to-end retrievals enable us to fully characterize not only the expected precision but also their potential biases, allowing us to select radar tones that maximize the water vapor signal minimizing potential errors due to spectral variations in the target extinction properties. A hypothetical CloudSat-like instrument with 500 m by ˜ 1 km vertical and horizontal resolution and a minimum detectable signal and radar precision of -30 and 0.16 dBZ, respectively, can estimate total column water vapor with an expected precision of around 0.03 cm, with potential biases smaller than 0.26 cm most of the time, even under rainy conditions. The expected precision for water vapor profiles was found to be around 89 % on average, with potential biases smaller than 77 % most of the time when the profile is being retrieved close to surface but smaller than 38 % above 3 km. By using either horizontal or vertical averaging, the precision will improve vastly, with the measurements still retaining a considerably high vertical and/or horizontal resolution.

  10. Determination of silver, antimony, bismuth, copper, cadmium and indium in ores, concentrates and related materials by atomic-absorption spectrophotometry after methyl isobutyl ketone extraction as iodides.

    PubMed

    Donaldson, E M; Wang, M

    1986-03-01

    Methods for determining ~ 0.2 mug g or more of silver and cadmium, ~ 0.5 mug g or more of copper and ~ 5 mug g or more of antimony, bismuth and indium in ores, concentrates and related materials are described. After sample decomposition and recovery of antimony and bismuth retained by lead and calcium sulphates, by co-precipitation with hydrous ferric oxide at pH 6.20 +/- 0.05, iron(III) is reduced to iron(II) with ascorbic acid, and antimony, bismuth, copper, cadmium and indium are separated from the remaining matrix elements by a single methyl isobutyl ketone extraction of their iodides from ~2M sulphuric acid-0.1M potassium iodide. The extract is washed with a sulphuric acid-potassium iodide solution of the same composition to remove residual iron and co-extracted zinc, and the extracted elements are stripped from the extract with 20% v v nitric acid-20% v v hydrogen peroxide. Alternatively, after the removal of lead sulphate by filtration, silver, copper, cadmium and indium can be extracted under the same conditions and stripped with 40% v v nitric acid-25% v v hydrochloric acid. The strip solutions are treated with sulphuric and perchloric acids and ultimately evaporated to dry ness. The individual elements are determined in a 24% v v hydrochloric acid medium containing 1000 mug of potassium per ml by atomic-absorption spectrophotometry with an air-acetylene flame. Tin, arsenic and molybdenum are not co-extracted under the conditions above. Results obtained for silver, antimony, bismuth and indium in some Canadian certified reference materials by these methods are compared with those obtained earlier by previously published methods.

  11. 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.

  12. Atmospheric Precorrected Differential Absorption technique to retrieve columnar water vapor

    SciTech Connect

    Schlaepfer, D.; Itten, K.I.; Borel, C.C.

    1998-09-01

    Differential absorption techniques are suitable to retrieve the total column water vapor contents from imaging spectroscopy data. A technique called Atmospheric Precorrected Differential Absorption (APDA) is derived directly from simplified radiative transfer equations. It combines a partial atmospheric correction with a differential absorption technique. The atmospheric path radiance term is iteratively corrected during the retrieval of water vapor. This improves the results especially over low background albedos. The error of the method for various ground reflectance spectra is below 7% for most of the spectra. The channel combinations for two test cases are then defined, using a quantitative procedure, whichmore » is based on MODTRAN simulations and the image itself. An error analysis indicates that the influence of aerosols and channel calibration is minimal. The APDA technique is then applied to two AVIRIS images acquired in 1991 and 1995. The accuracy of the measured water vapor columns is within a range of {+-}5% compared to ground truth radiosonde data.« less

  13. Techniques For Measuring Absorption Coefficients In Crystalline Materials

    NASA Astrophysics Data System (ADS)

    Klein, Philipp H.

    1981-10-01

    Absorption coefficients smaller than 0.001 cm-1 can, with more or less difficulty, be measured by several techniques. With diligence, all methods can be refined to permit measurement of absorption coefficients as small as 0.00001 cm-1. Spectral data are most readily obtained by transmission (spectrophotometric) methods, using multiple internal reflection to increase effective sample length. Emissivity measurements, requiring extreme care in the elimination of detector noise and stray light, nevertheless afford the most accessible spectral data in the 0.0001 to 0.00001 cm-1 range. Single-wavelength informa-tion is most readily obtained with modifications of laser calorimetry. Thermo-couple detection of energy absorbed from a laser beam is convenient, but involves dc amplification techniques and is susceptible to stray-light problems. Photoacoustic detection, using ac methods, tends to diminish errors of these types, but at some expense in experimental complexity. Laser calorimetry has been used for measurements of absorption coefficients as small as 0.000003 cm-1. Both transmission and calorimetric data, taken as functions of intensity, have been used for measurement of nonlinear absorption coefficients.

  14. Selective determination of arsenic(III) and arsenic(V) with ammonium pyrrolidinedithiocarbamate, sodium diethyldithiocarbamate and dithizone by means of flameless atomic-absorption spectrophotometry with a carbon-tube atomizer.

    PubMed

    Kamada, T

    The extraction behaviour of arsenic(III) and arsenic(V) with ammonium pyrrolidinedithiocarbamate, sodium diethyldithiocarbamate and dithizone in organic solvents has been investigated by means of nameless atomic-absorption spectrophotometry with a carbon-tube atomizer. The selective extraction of arsenic(III) and differential determination of arsenic(III) and arsenic(V) have been developed. With ammonium pyrrolidinedithiocarbamate and methyl isobutyl ketone or nitrobenzene, when the aqueous phase/solvent volume ratio is 5 and the injection volume in the carbon tube is 20 mul, the sensitivities for 1% absorption are 0.4 and 0.5 part per milliard of arsenic, respectively. The relative standard deviations are ca. 3%. Interference by many metal ions can be prevented by masking with EDTA. The proposed methods are applied satisfactorily for determination of As(III) and As(V) in various types of water.

  15. Oxygen detection using the laser diode absorption technique

    NASA Technical Reports Server (NTRS)

    Disimile, P. J.; Fox, C. W.

    1991-01-01

    Accurate measurement of the concentration and flow rate of gaseous oxygen is becoming of greater importance. The detection technique presented is based on the principal of light absorption by the Oxygen A-Band. Oxygen molecules have characteristics which attenuate radiation in the 759-770 nm wavelength range. With an ability to measure changes in the relative light transmission to less than 0.01 percent, a sensitive optical gas detection system was configured. This system is smaller in size and light in weight, has low energy requirements and has a rapid response time. In this research program, the application of temperature tuning laser diodes and their ability to be wavelength shifted to a selected absorption spectral peak has allowed concentrations as low as 1300 ppm to be detected.

  16. New analytical technique for carbon dioxide absorption solvents

    SciTech Connect

    Pouryousefi, F.; Idem, R.O.

    2008-02-15

    The densities and refractive indices of two binary systems (water + MEA and water + MDEA) and three ternary systems (water + MEA + CO{sub 2}, water + MDEA + CO{sub 2}, and water + MEA + MDEA) used for carbon dioxide (CO{sub 2}) capture were measured over the range of compositions of the aqueous alkanolamine(s) used for CO{sub 2} absorption at temperatures from 295 to 338 K. Experimental densities were modeled empirically, while the experimental refractive indices were modeled using well-established models from the known values of their pure-component densities and refractive indices. The density and Gladstone-Dale refractive indexmore » models were then used to obtain the compositions of unknown samples of the binary and ternary systems by simultaneous solution of the density and refractive index equations. The results from this technique have been compared with HPLC (high-performance liquid chromatography) results, while a third independent technique (acid-base titration) was used to verify the results. The results show that the systems' compositions obtained from the simple and easy-to-use refractive index/density technique were very comparable to the expensive and laborious HPLC/titration techniques, suggesting that the refractive index/density technique can be used to replace existing methods for analysis of fresh or nondegraded, CO{sub 2}-loaded, single and mixed alkanolamine solutions.« less

  17. Comparison of two novel in-syringe dispersive liquid-liquid microextraction techniques for the determination of iodide in water samples using spectrophotometry.

    PubMed

    Kaykhaii, Massoud; Sargazi, Mona

    2014-01-01

    Two new, rapid methodologies have been developed and applied successfully for the determination of trace levels of iodide in real water samples. Both techniques are based on a combination of in-syringe dispersive liquid-liquid microextraction (IS-DLLME) and micro-volume UV-Vis spectrophotometry. In the first technique, iodide is oxidized with nitrous acid to the colorless anion of ICl2(-) at high concentration of hydrochloric acid. Rhodamine B is added and by means of one step IS-DLLME, the ion-pair formed was extracted into toluene and measured spectrophotometrically. Acetone is used as dispersive solvent. The second method is based on the IS-DLLME microextraction of iodide as iodide/1, 10-phenanthroline-iron((II)) chelate cation ion-pair (colored) into nitrobenzene. Methanol was selected as dispersive solvent. Optimal conditions for iodide extraction were determined for both approaches. Methods are compared in terms of analytical parameters such as precision, accuracy, speed and limit of detection. Both methods were successfully applied to determining iodide in tap and river water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. 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.

  19. [Determination of total mercury in water samples, sediments and solids in suspension in aquatic systems by cold-vapor atomic absorption spectrophotometry].

    PubMed

    Vieira, J L; Passarelli, M M

    1996-06-01

    The use of metallic mercury in the extraction and concentration of gold causes the discarding of tons of this metal in the environment, leading to a considerable increase in the natural levels of the same and the contamination of the surrounding areas. Thus it is extremely important to monitor the presence of this metal in various sectors of the environment with a view aiming to preventing human exposure to excessive concentrations which can result in serious episodes of mercury poisoning. It is also important to estimate the possibility of river sediments becoming potential sources of contamination of human beings. The determination of total mercury was undertaken by using cold vapor atomic absorption spectrometry. River waters, as well as sediments and suspended solids were used as samples for the standardization of the analytical procedure. Later on, this method was tested on samples originating in gold mining areas for the purpose of assessing its validity.

  20. Thiomersal photo-degradation with visible light mediated by graphene quantum dots: Indirect quantification using optical multipath mercury cold-vapor absorption spectrophotometry

    NASA Astrophysics Data System (ADS)

    Miranda-Andrades, Jarol R.; Khan, Sarzamin; Toloza, Carlos A. T.; Romani, Eric C.; Freire Júnior, Fernando L.; Aucelio, Ricardo Q.

    2017-12-01

    Thiomersal is employed as preservative in vaccines, cosmetic and pharmaceutical products due to its capacity to inhibit bacterial growth. Thiomersal contains 49.55% of mercury in its composition and its highly toxic ethylmercury degradation product has been linked to neurological disorders. The photo-degradation of thiomersal has been achieved by visible light using graphene quantum dots as catalysts. The generated mercury cold vapor (using adjusted experimental conditions) was detected by multipath atomic absorption spectrometry allowing the quantification of thiomersal at values as low as 20 ng L- 1 even in complex samples as aqueous effluents of pharmaceutical industry and urine. A kinetic study (pseudo-first order with k = 0.11 min- 1) and insights on the photo-degradation process are presented.

  1. 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.

  2. Measurement of the absorption coefficient using the sound-intensity technique

    NASA Technical Reports Server (NTRS)

    Atwal, M.; Bernhard, R.

    1984-01-01

    The possibility of using the sound intensity technique to measure the absorption coefficient of a material is investigated. This technique measures the absorption coefficient by measuring the intensity incident on the sample and the net intensity reflected by the sample. Results obtained by this technique are compared with the standard techniques of measuring the change in the reverberation time and the standing wave ratio in a tube, thereby, calculating the random incident and the normal incident adsorption coefficient.

  3. Measurement of water absorption capacity in wheat flour by a headspace gas chromatographic technique.

    PubMed

    Xie, Wei-Qi; Yu, Kong-Xian; Gong, Yi-Xian

    2018-04-17

    The purpose of this work is to introduce a new method for quantitatively analyzing water absorption capacity in wheat flour by a headspace gas chromatographic technique. This headspace gas chromatographic technique was based on measuring the water vapor released from a series of wheat flour samples with different contents of water addition. According to the different trends between the vapor and wheat flour phase before and after the water absorption capacity in wheat flour, a turning point (corresponding to water absorption capacity in wheat flour) can be obtained by fitting the data of the water gas chromatography peak area from different wheat flour samples. The data showed that the phase equilibrium in the vial can be achieved in 25 min at desired temperature (35°C). The relative standard deviation of the reaction headspace gas chromatographic technique in water absorption capacity determination was within 3.48%, the relative differences has been determined by comparing the water absorption capacity obtained from this new analytical technique with the data from the reference technique (i.e., the filtration method), which are less than 8.92%. The new headspace gas chromatographic method is automated, accurate and be a reliable tool for quantifying water absorption capacity in wheat flour in both laboratory research and mill applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Sound absorption by suspensions of nonspherical particles: Measurements compared with predictions using various particle sizing techniques

    NASA Astrophysics Data System (ADS)

    Richards, Simon D.; Leighton, Timothy G.; Brown, Niven R.

    2003-10-01

    Knowledge of the particle size distribution is required in order to predict ultrasonic absorption in polydisperse particulate suspensions. This paper shows that the method used to measure the particle size distribution can lead to important differences in the predicted absorption. A reverberation technique developed for measuring ultrasonic absorption by suspended particles is used to measure the absorption in suspensions of nonspherical particles. Two types of particulates are studied: (i) kaolin (china clay) particles which are platelike in form; and (ii) calcium carbonate particles which are more granular. Results are compared to theoretical predictions of visco-inertial absorption by suspensions of spherical particles. The particle size distributions, which are required for these predictions, are measured by laser diffraction, gravitational sedimentation and centrifugal sedimentation, all of which assume spherical particles. For a given sample, each sizing technique yields a different size distribution, leading to differences in the predicted absorption. The particle size distributions obtained by gravitational and centrifugal sedimentation are reinterpreted to yield a representative size distribution of oblate spheroids, and predictions for absorption by these spheroids are compared with the measurements. Good agreement between theory and measurement for the flat kaolin particles is obtained, demonstrating that these particles can be adequately represented by oblate spheroids.

  5. The way to universal and correct medical presentation of diagnostic informations for complex spectrophotometry noninvasive medical diagnostic systems

    NASA Astrophysics Data System (ADS)

    Rogatkin, Dmitrii A.; Tchernyi, Vladimir V.

    2003-07-01

    The optical noninvasive diagnostic systems are now widely applied and investigated in different areas of medicine. One of the such techniques is the noninvasive spectrophotometry, the complex diagnostic technique consisting on elastic scattering spectroscopy, absorption spectroscopy, fluorescent diagnostics, photoplethismography, etc. Today a lot of real optical diagnostic systems indicate the technical parameters and physical data only as a result of the diagnostic procedure. But, it is clear that for the medical staff the more convenient medical information is needed. This presentation lights the general way for development a diagnostic system"s software, which can produce the full processing of the diagnostic data from a physical to a medical level. It is shown, that this process is a multilevel (3-level) procedure and the main diagnostic result for noninvasive spectrophotometry methods, the biochemical and morphological composition of the tested tissues, arises in it on a second level of calculations.

  6. Spectrophotometry of Symbiotic Stars

    NASA Astrophysics Data System (ADS)

    Boyd, David

    2017-06-01

    Symbiotic stars are fascinating objects - complex binary systems comprising a cool red giant star and a small hot object, often a white dwarf, both embedded in a nebula formed by a wind from the giant star. UV radiation from the hot star ionises the nebula producing a range of emission lines. These objects have composite spectra with contributions from both stars plus the nebula and these spectra can change on many timescales. Being moderately bright, they lend themselves well to amateur spectroscopy. This paper describes the symbiotic star phenomenon, shows how spectrophotometry can be used to extract astrophysically useful information about the nature of these systems, and gives results for three symbiotic stars based on the author's observations.

  7. Spectrophotometry: Past and Present

    NASA Astrophysics Data System (ADS)

    Adelman, Saul J.

    2009-01-01

    I describe the rise of optical region spectrophotometry in the 1960's and 1970's when it achieved a status as a major tool in stellar research through its decline and near demise at present. With absolutely calibrated fluxes and Balmer profiles usually of H-gamma, astronomers used model atmospheres predictions to find both the effective temperatures and surface gravities of many stars. Spectrophotometry as I knew it was photometrically calibrated low dispersion spectroscopy with a typical resolution of order 25 A. A typical data set consists of 10 to 15 values covering most of the optical spectral region. The strengths and shortcomings of the rotating grating scanners are discussed. The accomplishments achieved using spectrophotometric data, which were obtained with instruments using photomultipliers, are reviewed. Extensions to other spectral regions are noted and attempts to use observations from space to calibrate the optical region will be discussed. There are two steps to fully calibrate flux data. The first requires the calibration of the fluxes of one or more standard stars against sources calibrated absolutely in a laboratory. The use of Vega as the primary standard has been both a blessing as it is so bright and a curse especially as modeling it correctly requires treating it as a fast rotating star seen nearly pole-on. At best its calibration has errors of about 1%. The other step is to apply extinction corrections for the Earth's atmosphere and then calibrate the fluxes using the fluxes of standard stars. Now the ASTRA Spectrophotometer promises a revitalization of the use and availability of optical flux data. Its design specifications included solutions to the problems of past optical spectrophotometric instruments.

  8. Study of nonlinear absorption properties of reduced graphene oxide by Z-scan technique

    NASA Astrophysics Data System (ADS)

    Sreeja, V. G.; Vinitha, G.; Reshmi, R.; Anila, E. I.; Jayaraj, M. K.

    2017-05-01

    Graphene has generated enormous research interest during the last decade due to its significant unique properties and wide applications in the field of optoelectronics and photonics. This research studied the structural and nonlinear absorption properties of reduced graphene oxide (rGO) synthesized by Modified Hummer's method. Structural and physiochemical properties of the rGO were explored with the help of Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy (Raman). Nonlinear absorption property in rGO, was investigated by open aperture Z-scan technique by using a continuous wave (CW) laser. The Z-scan results demonstrate saturable absorption property of rGO with a nonlinear absorption coefficient, β, of -2.62 × 10-4 cm/W, making it suitable for applications in Q switching, generation of ultra-fast high energy pulses in laser cavity and mode lockers.

  9. Characterization of laser damage performance of fused silica using photothermal absorption technique

    NASA Astrophysics Data System (ADS)

    Wan, Wen; Shi, Feng; Dai, Yifan; Peng, Xiaoqiang

    2017-06-01

    The subsurface damage and metal impurities have been the main laser damage precursors of fused silica while subjected to high power laser irradiation. Light field enhancement and thermal absorption were used to explain the appearance of damage pits while the laser energy is far smaller than the energy that can reach the intrinsic threshold of fused silica. For fused silica optics manufactured by magnetorheological finishing or advanced mitigation process, no scratch-related damage site occurs can be found on the surface. In this work, we implemented a photothermal absorption technique based on thermal lens method to characterize the subsurface defects of fused silica optics. The pump beam is CW 532 nm wavelength laser. The probe beam is a He-Ne laser. They are collinear and focused through the same objective. When pump beam pass through the sample, optical absorption induces the local temperature rise. The lowest absorptance that we can detect is about the order of magnitude of 0.01 ppm. When pump beam pass through the sample, optical absorption induces the local temperature rise. The photothermal absorption value of fused silica samples range from 0.5 to 10 ppm. The damage densities of the samples were plotted. The damage threshold of samples at 8J/cm2 were gived to show laser damage performance of fused silica.The results show that there is a strong correlation between the thermal absorption and laser damage density. The photothermal absorption technique can be used to predict and evaluate the laser damage performance of fused silica optics.

  10. Microwave resonance lamp absorption technique for measuring temperature and OH number density in combustion environments

    NASA Technical Reports Server (NTRS)

    Lempert, Walter R.

    1988-01-01

    A simple technique for simultaneous determination of temperature and OH number density is described, along with characteristic results obtained from measurements using a premixed, hydrogen air flat flame burner. The instrumentation is based upon absorption of resonant radiation from a flowing microwave discharge lamp, and is rugged, relatively inexpensive, and very simple to operate.

  11. Study of Photosensitive Dry Films Absorption for Printed Circuit Boards by Photoacoustic Technique

    NASA Astrophysics Data System (ADS)

    Hernández, R.; Zaragoza, J. A. Barrientos; Jiménez-Pérez, J. L.; Orea, A. Cruz; Correa-Pacheco, Z. N.

    2017-08-01

    In this work, the study of photosensitive dry-type films by photoacoustic technique is proposed. The dry film photoresist is resistant to chemical etching for printed circuit boards such as ferric chloride, sodium persulfate or ammonium, hydrochloric acid. It is capable of faithfully reproducing circuit pattern exposed to ultraviolet light (UV) through a negative. Once recorded, the uncured portion is removed with alkaline solution. It is possible to obtain good results in surface mount circuits with tracks of 5 mm. Furthermore, the solid resin films are formed by three layers, two protective layers and a UV-sensitive optical absorption layer in the range of 325 nm to 405 nm. By means of optical absorption of UV-visible rays emitted by a low-power Xe lamp, the films transform this energy into thermal waves generated by the absorption of optical radiation and subsequently no-radiative de-excitation occurs. The photoacoustic spectroscopy is a useful technique to measure the transmittance and absorption directly. In this study, the optical absorption spectra of the three layers of photosensitive dry-type films were obtained as a function of the wavelength, in order to have a knowledge of the absorber layer and the protective layers. These analyses will give us the physical properties of the photosensitive film, which are very important in curing the dry film for applications in printed circuit boards.

  12. Recent Developments in the Speciation and Determination of Mercury Using Various Analytical Techniques

    PubMed Central

    Suvarapu, Lakshmi Narayana; Baek, Sung-Ok

    2015-01-01

    This paper reviews the speciation and determination of mercury by various analytical techniques such as atomic absorption spectrometry, voltammetry, inductively coupled plasma techniques, spectrophotometry, spectrofluorometry, high performance liquid chromatography, and gas chromatography. Approximately 126 research papers on the speciation and determination of mercury by various analytical techniques published in international journals since 2013 are reviewed. PMID:26236539

  13. A new technique to assess dermal absorption of volatile chemicals in vitro by thermal gravimetric analysis.

    PubMed

    Rauma, Matias; Isaksson, Tina S; Johanson, Gunnar

    2006-10-01

    Potential health hazards of dermal exposure, variability in reported dermal absorption rates and potential losses from the skin by evaporation indicate a need for a simple, inexpensive and standardized procedure to measure dermal absorption and desorption of chemical substances. The aim of this study was to explore the possibility to measure dermal absorption and desorption of volatile chemicals using a new gravimetric technique, namely thermal gravimetric analysis (TGA), and trypsinated stratum corneum from pig. Changes in skin weight were readily detected before, during and after exposure to vapours of water, 2-propanol, methanol and toluene. The shape and height of the weight curves differed between the four chemicals, reflecting differences in diffusivity and partial pressure and skin:air partitioning, respectively. As the skin weight is highly sensitive to the partial pressure of volatile chemicals, including water, this technique requires carefully controlled conditions with respect to air flow, temperature, chemical vapour generation and humidity. This new technique may help in the assessment of dermal uptake of volatile chemicals. Only a small piece of skin is needed and skin integrity is not necessary, facilitating the use of human samples. The high resolution weight-time curves obtained may also help to elucidate the characteristics of absorption, desorption and diffusion of chemicals in skin.

  14. 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.…

  15. Coal thickness gauge using RRAS techniques, part 1. [radiofrequency resonance absorption

    NASA Technical Reports Server (NTRS)

    Rollwitz, W. L.; King, J. D.

    1978-01-01

    A noncontacting sensor having a measurement range of 0 to 6 in or more, and with an accuracy of 0.5 in or better is needed to control the machinery used in modern coal mining so that the thickness of the coal layer remaining over the rock is maintained within selected bounds. The feasibility of using the radiofrequency resonance absorption (RRAS) techniques of electron magnetic resonance (EMR) and nuclear magnetic resonance (NMR) as the basis of a coal thickness gauge is discussed. The EMR technique was found, by analysis and experiments, to be well suited for this application.

  16. Weak absorptions in high density planetary atmospheres measured by the cavity ring down technique.

    NASA Astrophysics Data System (ADS)

    Snels, M.; Stefani, S.; Piccioni, G.

    2014-04-01

    High density planetary atmospheres are characterized by a high opacity due to the strong absorbers. Howevere usually several transparency windows exist which allow to study the lower part of the atmosphere as well as the surface emission. The weak absorptions occurring in these transparency windows are mostly due to trace species and to continuum absorption of the major absorber(s). A good example is the atmosphere of Venus, where carbondioxide causes a high opacity throughout most of the infrared wavelengths, but also has some transparency spectral windows in the near infrared, allowing the study of low lying clouds , trace species such as water vapor and in some cases the surface emission. The cavity ring down (CRD) technique has shown to be a good tool for studying weak absorptions. Here we present a CRD apparatus which can be operated at high pressures (up to 40 bar) with a sensitivity which allows to measure attenuations up to 2x10-8 cm-1. This instrument has been used to measure the carbon dioxide absorption at pressures up to 40 bar and has been also used to measure attenuation due to Rayleigh scattering at 1.18 μm.

  17. In vivo measurement of human skin absorption of topically applied substances by a photoacoustic technique.

    PubMed

    Gutiérrez-Juárez, G; Vargas-Luna, M; Córdova, T; Varela, J B; Bernal-Alvarado, J J; Sosa, M

    2002-08-01

    A photoacoustic technique is used for studying topically applied substance absorption in human skin. The proposed method utilizes a double-chamber PA cell. The absorption determination was obtained through the measurement of the thermal effusivity of the binary system substance-skin. The theoretical model assumes that the effective thermal effusivity of the binary system corresponds to that of a two-phase system. Experimental applications of the method employed different substances of topical application in different parts of the body of a volunteer. The method is demonstrated to be an easily used non-invasive technique for dermatology research. The relative concentrations as a function of time of substances such as ketoconazol and sunscreen were determined by fitting a sigmoidal function to the data, while an exponential function corresponds to the best fit for the set of data for nitrofurazona, vaseline and vaporub. The time constants associated with the rates of absorption, were found to vary in the range between 10 and 58 min, depending on the substance and the part of the body.

  18. Method and apparatus for measuring butterfat and protein content using microwave absorption techniques

    DOEpatents

    Fryer, Michael O.; Hills, Andrea J.; Morrison, John L.

    2000-01-01

    A self calibrating method and apparatus for measuring butterfat and protein content based on measuring the microwave absorption of a sample of milk at several microwave frequencies. A microwave energy source injects microwave energy into the resonant cavity for absorption and reflection by the sample undergoing evaluation. A sample tube is centrally located in the resonant cavity passing therethrough and exposing the sample to the microwave energy. A portion of the energy is absorbed by the sample while another portion of the microwave energy is reflected back to an evaluation device such as a network analyzer. The frequency at which the reflected radiation is at a minimum within the cavity is combined with the scatter coefficient S.sub.11 as well as a phase change to calculate the butterfat content in the sample. The protein located within the sample may also be calculated in a likewise manner using the frequency, S.sub.11 and phase variables. A differential technique using a second resonant cavity containing a reference standard as a sample will normalize the measurements from the unknown sample and thus be self-calibrating. A shuttered mechanism will switch the microwave excitation between the unknown and the reference cavities. An integrated apparatus for measuring the butterfat content in milk using microwave absorption techniques is also presented.

  19. Measurements of K shell absorption jump factors and jump ratios using EDXRF technique

    NASA Astrophysics Data System (ADS)

    Kacal, Mustafa Recep; Han, İbrahim; Akman, Ferdi

    2015-04-01

    In the present work, the K-shell absorption jump factors and jump ratios for 30 elements between Ti ( Z = 22) and Er ( Z = 68) were measured by energy dispersive X-ray fluorescence (EDXRF) technique. The jump factors and jump ratios for these elements were determined by measuring the K shell fluorescence parameters such as the Kα X-ray production cross-sections, K shell fluorescence yields, Kβ-to- Kα X-rays intensity ratios, total atomic absorption cross sections and mass attenuation coefficients. The measurements were performed using an Am-241 radioactive point source and a Si (Li) detector in direct excitation and transmission experimental geometry. The results for jump factors and jump ratios were compared with theoretically calculated and the ones available in the literature.

  20. Application of the laser induced deflection (LID) technique for low absorption measurements in bulk materials and coatings

    NASA Astrophysics Data System (ADS)

    Triebel, W.; Mühlig, C.; Kufert, S.

    2005-10-01

    Precise absorption measurements of bulk materials and coatings upon pulsed ArF laser irradiation are presented using a compact experimental setup based on the laser induced deflection technique (LID). For absorption measurements of bulk materials the influence of pure bulk and pure surface absorption on the temperature and refractive index profile and thus for the probe beam deflection is analyzed in detail. The separation of bulk and surface absorption via the commonly used variation of the sample thickness is carried out for fused silica and calcium fluoride. The experimental results show that for the given surface polishing quality the bulk absorption coefficient of fused silica can be obtained by investigating only one sample. To avoid the drawback of different bulk and surface properties amongst a thickness series, we propose a strategy based on the LID technique to generally obtain surface and bulk absorption separately by investigating only one sample. Apart from measuring bulk absorption coefficients the LID technique is applied to determine the absorption of highly reflecting (HR) coatings on CaF2 substrates. Beside the measuring strategy the experimental results of a AlF3/LaF3 based HR coating are presented. In order to investigate a larger variety of coatings, including high transmitting coatings, a general measuring strategy based on the LID technique is proposed.

  1. Intestinal absorption of dideoxynucleosides: characterization using a multiloop in situ technique.

    PubMed

    Mirchandani, H L; Chien, Y W

    1995-01-01

    The intestinal absorption of dideoxynucleosides was studied in rabbits, using a closed-loop mesenteric-sampling in situ technique developed in this laboratory, and the kinetic profiles were characterized. Each of the dideoxynucleosides exhibited different dependence on the intestinal regions studied: 3'-azido-2',3'-dideoxythymidine was best absorbed from the ileum, while 2',3'-dideoxyinosine and 2',3'-dideoxycytidine were preferentially absorbed from the jejunum. The results were validated by the mass-balance approach; the percent of drug retained in the intestinal lumen and that degraded at the intestinal pH, by colonic flora, in the intestinal tissue, and in plasma were assessed.

  2. Invited Review Article: Imaging techniques for harmonic and multiphoton absorption fluorescence microscopy

    PubMed Central

    Carriles, Ramón; Schafer, Dawn N.; Sheetz, Kraig E.; Field, Jeffrey J.; Cisek, Richard; Barzda, Virginijus; Sylvester, Anne W.; Squier, Jeffrey A.

    2009-01-01

    We review the current state of multiphoton microscopy. In particular, the requirements and limitations associated with high-speed multiphoton imaging are considered. A description of the different scanning technologies such as line scan, multifoci approaches, multidepth microscopy, and novel detection techniques is given. The main nonlinear optical contrast mechanisms employed in microscopy are reviewed, namely, multiphoton excitation fluorescence, second harmonic generation, and third harmonic generation. Techniques for optimizing these nonlinear mechanisms through a careful measurement of the spatial and temporal characteristics of the focal volume are discussed, and a brief summary of photobleaching effects is provided. Finally, we consider three new applications of multiphoton microscopy: nonlinear imaging in microfluidics as applied to chemical analysis and the use of two-photon absorption and self-phase modulation as contrast mechanisms applied to imaging problems in the medical sciences. PMID:19725639

  3. The Assessment of Liver Reserve Function by Spectrophotometry based on Determination of Phenacetin and Paracetamol.

    PubMed

    Ren, Rui; Ma, Yongmei; Ma, Wanshan; Lu, Sumei

    2015-01-01

    To establish a technical system for assessing liver reserve function based on spectrophotometry by detection of phenacetin and paracetamol in blood samples. Taking detected contents of phenacetin and paracetamol by high performance liquid chromatography (HPLC) as standard, which was proved to be able to detect drug concentrations with high resolution and accuracy, we established a technical system based on the spectrophotometric technique to assay phenacetin and paracetamol, including the color system, the maximum absorption wavelength, the influence factors of color system, and the optimal conditions for hydrolysis. Then we verified our established system compared with that under HPLC by recovery test. This study established a technical system to detect phenacetin and paracetamol in blood samples using spectrophotometry. Mainly, 3 mol/L hydrochloric acid (HCl) was added to samples for hydrolysis for 30 minutes, then, adding 0.02% 1,2-naphthoquinone-4-sulfonate (NQS), 1% cetyltrimethyl ammonium bromide (CTA) and 2% sodium hydroxide (or 3% sodium carbonate) (ratio of 1:6:1:2 or 3), and the absorbance was measured at 500 nm and 570 nm to calculate their concentrations. Using an established spectrophotometric system to detect phenacetin and paracetamol in blood samples could assess liver reserve function, which was proved comparable with HPLC in resolution and repeatability.

  4. Remote sensing of atmospheric NO2 by employing the continuous-wave differential absorption lidar technique.

    PubMed

    Mei, Liang; Guan, Peng; Kong, Zheng

    2017-10-02

    Differential absorption lidar (DIAL) technique employed for remote sensing has been so far based on the sophisticated narrow-band pulsed laser sources, which require intensive maintenance during operation. In this work, a continuous-wave (CW) NO 2 DIAL system based on the Scheimpflug principle has been developed by employing a compact high-power CW multimode 450 nm laser diode as the light source. Laser emissions at the on-line and off-line wavelengths of the NO 2 absorption spectrum are implemented by tuning the injection current of the laser diode. Lidar signals are detected by a 45° tilted area CCD image sensor satisfying the Scheimpflug principle. Range-resolved NO 2 concentrations on a near-horizontal path are obtained by the NO 2 DIAL system in the range of 0.3-3 km and show good agreement with those measured by a conventional air pollution monitoring station. A detection sensitivity of ± 0.9 ppbv at 95% confidence level in the region of 0.3-1 km is achieved with 15-minute averaging and 700 m range resolution during hours of darkness, which allows accurate concentration measurement of ambient NO 2 . The low-cost and robust DIAL system demonstrated in this work opens up many possibilities for field NO 2 remote sensing applications.

  5. Improvement of the tetrachloromercurate absorption technique for measuring low atmospheric SO2 mixing ratios

    NASA Astrophysics Data System (ADS)

    Jaeschke, W.; Beltz, N.; Haunold, W.; Krischke, U.

    1997-07-01

    During the Gas-Phase Sulfur Intercomparison Experiment (GASIE) in 1994 an analytical system for measuring sulfur dioxide mixing ratios at low parts per trillion (pptv) levels was employed. It is based on the absorption of SO2 on a tetrachloromercurate(II)-impregnated filter. The subsequent analysis uses a chemiluminescence reaction by treating the resulting disulfitomercurate(II) complex with an acidic cerium sulfate solution. An improved sampling device has been introduced that increases the maximum sampling volume from 200 L to 500 L. It is also possible to determine the blank value accurately for each sample. The absorption efficiency of the sampling system is 98.7±6.4% at a nominal flow rate of 10 L/min. The calculated (3σ) detection limit is 3±1 pptv SO2. The sample solution is stable for up to 30 days, which allows the samples to be safely stored or shipped before analysis. This permits the use of a sensitive, compact, and reliable sampling system in the field with subsequent analysis under optimal conditions in the laboratory. A continuous flow chemiluminescence (CFCL) analyzer for on-line measurements is also presented. The system is based on the same chemical principles as the described filter technique.

  6. Understanding refraction contrast using a comparison of absorption and refraction computed tomographic techniques

    NASA Astrophysics Data System (ADS)

    Wiebe, S.; Rhoades, G.; Wei, Z.; Rosenberg, A.; Belev, G.; Chapman, D.

    2013-05-01

    Refraction x-ray contrast is an imaging modality used primarily in a research setting at synchrotron facilities, which have a biomedical imaging research program. The most common method for exploiting refraction contrast is by using a technique called Diffraction Enhanced Imaging (DEI). The DEI apparatus allows the detection of refraction between two materials and produces a unique ''edge enhanced'' contrast appearance, very different from the traditional absorption x-ray imaging used in clinical radiology. In this paper we aim to explain the features of x-ray refraction contrast as a typical clinical radiologist would understand. Then a discussion regarding what needs to be considered in the interpretation of the refraction image takes place. Finally we present a discussion about the limitations of planar refraction imaging and the potential of DEI Computed Tomography. This is an original work that has not been submitted to any other source for publication. The authors have no commercial interests or conflicts of interest to disclose.

  7. NONLINEAR-APPROXIMATION TECHNIQUE FOR DETERMINING VERTICAL OZONE-CONCENTRATION PROFILES WITH A DIFFERENTIAL-ABSORPTION LIDAR

    EPA Science Inventory

    A new technique is presented for the retrieval of ozone concentration profiles from backscattered signals obtained by a multi-wavelength differential-absorption lidar (DIAL). The technique makes it possible to reduce erroneous local fluctuations induced in the ozone-concentration...

  8. 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. Copyright © 2012 Elsevier Inc. All rights reserved.

  9. Application of several physical techniques in the total analysis of a canine urinary calculus.

    PubMed

    Rodgers, A L; Mezzabotta, M; Mulder, K J; Nassimbeni, L R

    1981-06-01

    A single calculus from the bladder of a Beagle bitch has been analyzed by a multiple technique approach employing x-ray diffraction, infrared spectroscopy, scanning electron microscopy, x-ray fluorescence spectrometry, atomic absorption spectrophotometry and density gradient fractionation. The qualitative and quantitative data obtained showed excellent agreement, lending confidence to such an approach for the evaluation and understanding of stone disease.

  10. Experimental technique for simultaneous measurement of absorption-, emission cross-sections, and background loss coefficient in doped optical fibers

    NASA Astrophysics Data System (ADS)

    Karimi, M.; Seraji, F. E.

    2010-01-01

    We report a new simple technique for the simultaneous measurements of absorption-, emission cross-sections, background loss coefficient, and dopant density of doped optical fibers with low dopant concentration. Using our proposed technique, the experimental characterization of a sample Ge-Er-doped optical fiber is presented, and the results are analyzed and compared with other reports. This technique is suitable for production line of doped optical fibers.

  11. Quantitative filter technique measurements of spectral light absorption by aquatic particles using a portable integrating cavity absorption meter (QFT-ICAM).

    PubMed

    Röttgers, Rüdiger; Doxaran, David; Dupouy, Cecile

    2016-01-25

    The accurate determination of light absorption coefficients of particles in water, especially in very oligotrophic oceanic areas, is still a challenging task. Concentrating aquatic particles on a glass fiber filter and using the Quantitative Filter Technique (QFT) is a common practice. Its routine application is limited by the necessary use of high performance spectrophotometers, distinct problems induced by the strong scattering of the filters and artifacts induced by freezing and storing samples. Measurements of the sample inside a large integrating sphere reduce scattering effects and direct field measurements avoid artifacts due to sample preservation. A small, portable, Integrating Cavity Absorption Meter setup (QFT-ICAM) is presented, that allows rapid measurements of a sample filter. The measurement technique takes into account artifacts due to chlorophyll-a fluorescence. The QFT-ICAM is shown to be highly comparable to similar measurements in laboratory spectrophotometers, in terms of accuracy, precision, and path length amplification effects. No spectral artifacts were observed when compared to measurement of samples in suspension, whereas freezing and storing of sample filters induced small losses of water-soluble pigments (probably phycoerythrins). Remaining problems in determining the particulate absorption coefficient with the QFT-ICAM are strong sample-to-sample variations of the path length amplification, as well as fluorescence by pigments that is emitted in a different spectral region than that of chlorophyll-a.

  12. ABO blood grouping from hard and soft tissues of teeth by modified absorption-elution technique.

    PubMed

    Ramnarayan, Bk; Manjunath, M; Joshi, Anagha Ananth

    2013-01-01

    Teeth have always been known as stable tissue that can be preserved both physically and chemically for long periods of time. Blood group substances have been known to be present in both the hard and soft tissues of the teeth. This study aimed at detection of ABO blood group substances from soft and hard tissues of teeth and also to evaluate the reliability of teeth stored for a relatively long period as a source of blood group substances by absorption-elution technique with some modifications. Blood group obtained from the teeth was compared with those obtained from the blood sample. Pulp showed a very large correlation in both fresh and long-standing teeth though it decreased slightly in the latter. Hard tissue showed a large correlation in both the groups indicating that hard tissue is quite reliable to detect blood group and that there is no much difference in the reliability in both the groups. However, combining pulp and hard tissue, correlation is moderate. Correlation of blood grouping with the age, sex, and jaw distribution was carried out. Blood group identification from hard and soft tissues of teeth aids in the identification of an individual.

  13. Spectrophotometry of Symbiotic Stars (Abstract)

    NASA Astrophysics Data System (ADS)

    Boyd, D.

    2017-12-01

    (Abstract only) Symbiotic stars are fascinating objects - complex binary systems comprising a cool red giant star and a small hot object, often a white dwarf, both embedded in a nebula formed by a wind from the giant star. UV radiation from the hot star ionizes the nebula, producing a range of emission lines. These objects have composite spectra with contributions from both stars plus the nebula and these spectra can change on many timescales. Being moderately bright, they lend themselves well to amateur spectroscopy. This paper describes the symbiotic star phenomenon, shows how spectrophotometry can be used to extract astrophysically useful information about the nature of these systems, and gives results for three symbiotic stars based on the author's observations.

  14. Spectrophotometry (by Barbara Sawrey and Gabriele Wienhausen)

    NASA Astrophysics Data System (ADS)

    Pringle, David L.

    1998-08-01

    Science Media: San Diego, 1997. 1-10 copies, 99 each; 11-20 copies, 69 each; 21+ copies, $49 each. (Note: CD operates with both Mac and PC.) Spectrophotometry is an interactive CD-ROM which introduces the basics of UV-visible spectrophotometry with some mention of infrared and other forms of spectrophotometry. A Macintosh System 7.5 or higher, CPU 68040 or Power PC processor, 6 megabytes of free RAM, 2.6 megabytes of free disk space, and 4X CD-ROM or faster are required.

  15. Prediction of Human Intestinal Absorption of Compounds Using Artificial Intelligence Techniques.

    PubMed

    Kumar, Rajnish; Sharma, Anju; Siddiqui, Mohammed Haris; Tiwari, Rajesh Kumar

    2017-01-01

    Information about Pharmacokinetics of compounds is an essential component of drug design and development. Modeling the pharmacokinetic properties require identification of the factors effecting absorption, distribution, metabolism and excretion of compounds. There have been continuous attempts in the prediction of intestinal absorption of compounds using various Artificial intelligence methods in the effort to reduce the attrition rate of drug candidates entering to preclinical and clinical trials. Currently, there are large numbers of individual predictive models available for absorption using machine learning approaches. Six Artificial intelligence methods namely, Support vector machine, k- nearest neighbor, Probabilistic neural network, Artificial neural network, Partial least square and Linear discriminant analysis were used for prediction of absorption of compounds. Prediction accuracy of Support vector machine, k- nearest neighbor, Probabilistic neural network, Artificial neural network, Partial least square and Linear discriminant analysis for prediction of intestinal absorption of compounds was found to be 91.54%, 88.33%, 84.30%, 86.51%, 79.07% and 80.08% respectively. Comparative analysis of all the six prediction models suggested that Support vector machine with Radial basis function based kernel is comparatively better for binary classification of compounds using human intestinal absorption and may be useful at preliminary stages of drug design and development. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  16. 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

  17. Combined acquisition technique (CAT) for neuroimaging of multiple sclerosis at low specific absorption rates (SAR).

    PubMed

    Biller, Armin; Choli, Morwan; Blaimer, Martin; Breuer, Felix A; Jakob, Peter M; Bartsch, Andreas J

    2014-01-01

    To compare a novel combined acquisition technique (CAT) of turbo-spin-echo (TSE) and echo-planar-imaging (EPI) with conventional TSE. CAT reduces the electromagnetic energy load transmitted for spin excitation. This radiofrequency (RF) burden is limited by the specific absorption rate (SAR) for patient safety. SAR limits restrict high-field MRI applications, in particular. The study was approved by the local Medical Ethics Committee. Written informed consent was obtained from all participants. T2- and PD-weighted brain images of n = 40 Multiple Sclerosis (MS) patients were acquired by CAT and TSE at 3 Tesla. Lesions were recorded by two blinded, board-certificated neuroradiologists. Diagnostic equivalence of CAT and TSE to detect MS lesions was evaluated along with their SAR, sound pressure level (SPL) and sensations of acoustic noise, heating, vibration and peripheral nerve stimulation. Every MS lesion revealed on TSE was detected by CAT according to both raters (Cohen's kappa of within-rater/across-CAT/TSE lesion detection κCAT = 1.00, at an inter-rater lesion detection agreement of κLES = 0.82). CAT reduced the SAR burden significantly compared to TSE (p<0.001). Mean SAR differences between TSE and CAT were 29.0 (± 5.7) % for the T2-contrast and 32.7 (± 21.9) % for the PD-contrast (expressed as percentages of the effective SAR limit of 3.2 W/kg for head examinations). Average SPL of CAT was no louder than during TSE. Sensations of CAT- vs. TSE-induced heating, noise and scanning vibrations did not differ. T2-/PD-CAT is diagnostically equivalent to TSE for MS lesion detection yet substantially reduces the RF exposure. Such SAR reduction facilitates high-field MRI applications at 3 Tesla or above and corresponding protocol standardizations but CAT can also be used to scan faster, at higher resolution or with more slices. According to our data, CAT is no more uncomfortable than TSE scanning.

  18. Combined Acquisition Technique (CAT) for Neuroimaging of Multiple Sclerosis at Low Specific Absorption Rates (SAR)

    PubMed Central

    Biller, Armin; Choli, Morwan; Blaimer, Martin; Breuer, Felix A.; Jakob, Peter M.; Bartsch, Andreas J.

    2014-01-01

    Purpose To compare a novel combined acquisition technique (CAT) of turbo-spin-echo (TSE) and echo-planar-imaging (EPI) with conventional TSE. CAT reduces the electromagnetic energy load transmitted for spin excitation. This radiofrequency (RF) burden is limited by the specific absorption rate (SAR) for patient safety. SAR limits restrict high-field MRI applications, in particular. Material and Methods The study was approved by the local Medical Ethics Committee. Written informed consent was obtained from all participants. T2- and PD-weighted brain images of n = 40 Multiple Sclerosis (MS) patients were acquired by CAT and TSE at 3 Tesla. Lesions were recorded by two blinded, board-certificated neuroradiologists. Diagnostic equivalence of CAT and TSE to detect MS lesions was evaluated along with their SAR, sound pressure level (SPL) and sensations of acoustic noise, heating, vibration and peripheral nerve stimulation. Results Every MS lesion revealed on TSE was detected by CAT according to both raters (Cohen’s kappa of within-rater/across-CAT/TSE lesion detection κCAT = 1.00, at an inter-rater lesion detection agreement of κLES = 0.82). CAT reduced the SAR burden significantly compared to TSE (p<0.001). Mean SAR differences between TSE and CAT were 29.0 (±5.7) % for the T2-contrast and 32.7 (±21.9) % for the PD-contrast (expressed as percentages of the effective SAR limit of 3.2 W/kg for head examinations). Average SPL of CAT was no louder than during TSE. Sensations of CAT- vs. TSE-induced heating, noise and scanning vibrations did not differ. Conclusion T2−/PD-CAT is diagnostically equivalent to TSE for MS lesion detection yet substantially reduces the RF exposure. Such SAR reduction facilitates high-field MRI applications at 3 Tesla or above and corresponding protocol standardizations but CAT can also be used to scan faster, at higher resolution or with more slices. According to our data, CAT is no more uncomfortable than TSE scanning. PMID

  19. Zinc Absorption from Representative Diet in a Chinese Elderly Population Using Stable Isotope Technique.

    PubMed

    Li, Ya Jie; Li, Min; Liu, Xiao Bing; Ren, Tong Xiang; Li, Wei Dong; Yang, Chun; Wu, Meng; Yang, Lin Li; Ma, Yu Xia; Wang, Jun; Piao, Jian Hua; Yang, Li Chen; Yang, Xiao Guang

    2017-06-01

    To determine the dietary zinc absorption in a Chinese elderly population and provide the basic data for the setting of zinc (Zn) recommended nutrient intakes (RNI) for Chinese elderly people. A total of 24 elderly people were recruited for this study and were administered oral doses of 3 mg 67Zn and 1.2 mg dysprosium on the fourth day. The primary macronutrients, energy, and phytic acid in the representative diet were examined based on the Chinese National Standard Methods. Fecal samples were collected during the experimental period and analyzed for zinc content, 67Zn isotope ratio, and dysprosium content. The mean (± SD) zinc intake from the representative Chinese diet was 10.6 ± 1.5 mg/d. The phytic acid-to-zinc molar ratio in the diet was 6.4. The absorption rate of 67Zn was 27.9% ± 9.2%. The RNI of zinc, which were calculated by the absorption rate in elderly men and women, were 10.4 and 9.2 mg/d, respectively. This study got the dietary Zn absorption in a Chinese elderly population. We found that Zn absorption was higher in elderly men than in elderly women. The current RNI in elderly female is lower than our finding, which indicates that more attention is needed regarding elderly females' zinc status and health. Copyright © 2017 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

  20. Serum paraquat concentration detected by spectrophotometry in patients with paraquat poisoning

    PubMed Central

    Li, Chang-bin; Li, Xin-hua; Wang, Zhen; Jiang, Cheng-hua; Peng, Ai

    2011-01-01

    BACKGROUND: Paraquat (PQ) is a world-wide used herbicide and also a type of common poison for suicide and accidental poisoning. Numerous studies have proved that the concentration of serum PQ plays an important role in prognosis. Spectrophotometry, including common spectrophotometry and second-derivative spectrophotometry, is commonly used for PQ detection in primary hospitals. So far, lack of systematic research on the reliability of the method and the correlation between clinical features of patients with PQ poisoning and the test results has restricted the clinical use of spectrophotometry. This study aimed to evaluate the reliability and value of spectrophotometry in detecting the concentration of serum PQ. METHODS: The wavelengths for detecting the concentration of serum PQ by common and second-derivative spectrophotometry were determined. Second-derivative spectrophotometry was applied to detect the concentration of serum PQ. The linear range and precision for detection of PQ concentration by this method were confirmed. The concentration of serum PQ shown by second-derivative spectrophotometry and HPLC were compared in 8 patients with PQ poisoning. Altogether 21 patients with acute poisoning 4 hours after PQ ingestion treated in the period of October 2008 to September 2010 were retrospectively reviewed. The patients were divided into higher and lower than 1.8 μg/mL groups based on their concentrations of serum PQ measured by second-derivative spectrophotometry on admission. The severity of clinical manifestations between the two groups were analyzed with Student's t test or Fisher's exact test. RESULTS: The absorption peak of 257 nm could not be found when common spectrophotometry was used to detect the PQ concentration in serum. The calibration curve in the 0.4–8.0 μg/mL range for PQ concentration shown by second-derivative spectrophotometry obeyed Beer's law with r=0.996. The average recovery rates of PQ were within a range of 95.0% to 99.5%, relative

  1. Predicting both passive intestinal absorption and the dissociation constant toward albumin using the PAMPA technique.

    PubMed

    Bujard, Alban; Sol, Marine; Carrupt, Pierre-Alain; Martel, Sophie

    2014-10-15

    The parallel artificial membrane permeability assay (PAMPA) is a high-throughput screening (HTS) method that is widely used to predict in vivo passive permeability through biological barriers, such as the skin, the blood brain barrier (BBB) and the gastrointestinal tract (GIT). The PAMPA technique has also been used to predict the dissociation constant (Kd) between a compound and human serum albumin (HSA) while disregarding passive permeability. Furthermore, the assay is based on the use of two separate 5-point kinetic experiments, which increases the analysis time. In the present study, we adapted the hexadecane membrane (HDM)-PAMPA assay to both predict passive gastrointestinal absorption via the permeability coefficient logPe value and determine the Kd. Two assays were performed: one in the presence and one in the absence of HSA in the acceptor compartment. In the absence of HSA, logPe values were determined after a 4-h incubation time, as originally described, but the dimethylsulfoxide (DMSO) percentage and pH were altered to be compatible with the protein. In parallel, a second PAMPA assay was performed in the presence of HSA during a 16-h incubation period. By adding HSA, a variation in the amount of compound crossing the membrane was observed compared to the permeability measured in the absence of HSA. The concentration of compound reaching the acceptor compartment in each case was used to determine both parameters (logPe and logKd) using numerical simulations, which highlighted the originality of this method because these calculations required only two endpoint measurements instead of a complete kinetic study. It should be noted that the amount of compound that reaches the acceptor compartment in the presence of HSA is modulated by complex dissociation in the receptor compartment. Only compounds that are moderately bound to albumin (-3

  2. Optical Region Spectrophotometry: Past and Present

    NASA Astrophysics Data System (ADS)

    Adelman, Saul J.

    In the 1960s and 1970s optical region spectrophotometry achieved the status of a major tool in stellar research. New instrumentation, rotating grating scanners using photomultiplier tubes as detectors, and improved absolute calibrations of Vega made this possible. After this period the use of this technique declined to its near demise at present. The use of Vega as the primary standard has been both a blessing as it is so bright and a curse especially as modeling it correctly requires treating it as a fast rotating star seen nearly pole-on. It may be better to use several stars to define any future absolute calibration. With absolutely calibrated fluxes and Balmer profiles, often Hγ, investigators used the predictions of model atmospheres to find both the effective temperatures and the surface gravities of stars. The fluxes were photometrically calibrated low dispersion spectra with a typical resolution of order 25 Å. A typical data set consisted of 10-15 values covering most of the optical spectral region. At present two instrumental projects ACCESS and the ASTRA Spectrophotometer promise, respectively, a new substantially improved absolute calibration of the optical fluxes of several targets and the availability of a considerable amount of well-calibrated optical flux data for use in studies concerned with stellar properties. They jointly promise to revive optical region spectrophotometric studies.

  3. Absorption kinetics of vitamin E nanoemulsion and green tea microstructures by intestinal in situ single perfusion technique in rats.

    PubMed

    Saratale, Rijuta Ganesh; Lee, Hee-Seok; Koo, Yong Eui; Saratale, Ganesh Dattatraya; Kim, Young Jun; Imm, Jee Young; Park, Yooheon

    2018-04-01

    The absorption kinetics of food ingredients such as nanoemulsified vitamin E and green tea microstructures were evaluated by the intestinal in situ single perfusion technique. Absorption rate, sub-acute oral toxicity and organ morphology in a rat model were examined. The intestinal in situ single perfusion technique and HPLC analysis were applied to investigate the absorption rate of selected materials by examining time-dependent changes in the serum levels of catechin and dl-α-tocopherol. The acute toxicity test and histopathological evaluation were applied to analyze the safety of microsized green tea and nanosized vitamin E in a rat model. Total serum dl-α-tocopherol levels significantly increased with nanosized vitamin E administration (P<0.05). Rats treated to nanosized vitamin E until 90min after administration showed significantly increased absorption rate of serum dl-α-tocopherol levels at each time point (10min interval) (P<0.001). Rats administered 2000mg/kg of nanosized vitamin E and microsized green tea did not show signs of acute toxicity or death after 14days of observation. In addition, macroscopic analysis showed that there were no changes in representative organ sections of rats following the oral administration of food-related nanoscale materials. We successfully demonstrated that using nanosized vitamin E increased absorption rate to a greater extent than normal food-related material, and these results occurs via safety analyses on food-related nanoscale materials for human consumption. These results could be useful for the design and development of novel nanoemulsified vitamin E and microsized green tea formulations that can overcome the problem of their bioavailability and improve their efficacy while still maintaining their essential therapeutic efficacies. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Evaluation of fluid absorption during holmium laser enucleation of prostate by breath ethanol technique.

    PubMed

    Shah, Hemendra N; Kausik, Vikram; Hegde, Sunil; Shah, Jignesh N; Bansal, Manish B

    2006-02-01

    In a prospective manner we studied various factors affecting fluid absorption during HoLEP. We also simultaneously evaluated changes in serum electrolytes and hemoglobin decrease during HoLEP. This prospective study comprised of 53 patients who underwent HoLEP at our institute. Irrigation fluid was normal saline tagged with ethanol (1% w/v). Intraoperatively a standard breath analyzer was used to monitor expired breath ethanol levels during the procedure at 10-minute intervals. Patients who absorbed irrigating fluid as indicated by positive intraoperative breath tests were considered absorbers. Serum electrolyte and hemoglobin estimations were done before and after surgery. Total irrigation time, amount of irrigation fluid used, weight of resected tissue and presence of capsular perforation were recorded. Statistical analysis was performed to observe the effects of various factors on the amount of intraoperative fluid absorption. Of 53 patients studied 14 (26.41%) demonstrated fluid absorption in the range of 213 to 930 ml (mean 459). Preoperative prostate weight, total irrigation time, amount of irrigation fluid used and resected tissue weight were all significantly greater in absorbers. Similarly, absorbers had a statistically significant decrease in hemoglobin level postoperatively. There was no statistically significant change in serum electrolytes between absorbers and nonabsorbers. Preoperative weight of prostate, total irrigation time, amount of irrigation fluid used and weight of resected tissue all directly influence the amount of fluid absorption during HoLEP. There is no significant change in serum electrolytes and no risk of the transurethral resection syndrome.

  5. Dependence of intestinal glucose absorption on sodium, studied with a new arterial infusion technique

    PubMed Central

    Fisher, R. B.; Gardner, M. L. G.

    1974-01-01

    1. A new preparation of isolated rat jejunum plus ileum (ca. 100 cm) is described in which a saline infusate is pumped into the superior mesenteric artery, the superior mesenteric vein having been ligated. 2. The arterial infusate washes out the tissue spaces: the lumen is perfused in a single pass with a segmented flow as by Fisher & Gardner (1974). 3. At an arterial infusion rate of 3 ml./min, steady states are set up in the tissue fluid within 10-15 min: the compositions of the fluids bathing both sides of the mucosa can therefore be controlled. 4. The rate of glucose absorption from the lumen falls only gradually when the luminal sodium is replaced by choline abruptly while the tissue fluid sodium is maintained at 144 m-equiv/l. by arterial infusion. 5. The rate of glucose absorption from the lumen is unaffected by replacement of sodium in the arterial infusate by choline. 6. Ouabain (10-4 M) in an arterial infusate containing sodium 144 m-equiv/l. causes inhibition of glucose and water absorption from the lumen. There is no effect of ouabain when the arterial infusate contains sodium, 0 or 72 m-equiv/l. 7. Arterial ouabain does not reverse the effects of depletion of luminal sodium. Simultaneous removal of luminal sodium and application of arterial ouabain causes faster inhibition of glucose absorption than does either treatment alone. 8. Glucose absorption is more likely to depend on rate of efflux of sodium from mucosal cell to tissue fluid than on a sodium gradient at the brush border or on intracellular sodium concentration. PMID:4422318

  6. Stark effect spectrophone for continuous absorption spectra monitoring. [a technique for gas analysis

    NASA Technical Reports Server (NTRS)

    Kavaya, M. J. (Inventor)

    1981-01-01

    A Stark effect spectrophone using a pulsed or continuous wave laser having a beam with one or more absorption lines of a constituent of an unknown gas is described. The laser beam is directed through windows of a closed cell while the unknown gas to be modified flows continuously through the cell between electric field plates disposed in the cell on opposite sides of the beam path through the cell. When the beam is pulsed, energy absorbed by the gas increases at each point along the beam path according to the spectral lines of the constituents of the gas for the particular field strengths at those points. The pressure measurement at each point during each pulse of energy yields a plot of absorption as a function of electric field for simultaneous detection of the gas constituents. Provision for signal averaging and modulation is included.

  7. A Method for Eliminating Beam Steering Error for the Modulated Absorption-Emission Thermometry Technique

    DTIC Science & Technology

    2014-01-01

    broadened and merged. It is also suitable for environments where broadband emitters such as soot are present. Radiometric measurements in general can be...emitters such as soot are present. Radiometric measurements in general can be made with very high accuracy. The international temperature scale (ITS...by a fitting to a model. In the case of sooting flames, the emissivity is a result of the nearly black absorption and emission features of soot

  8. VO2+ ions in zinc lead borate glasses studied by EPR and optical absorption techniques.

    PubMed

    Prakash, P Giri; Rao, J Lakshmana

    2005-09-01

    Electron paramagnetic resonance (EPR) and optical absorption spectra of vanadyl ions in zinc lead borate (ZnO-PbO-B2O3) glass system have been studied. EPR spectra of all the glass samples exhibit resonance signals characteristic of VO2+ ions. The values of spin-Hamiltonian parameters indicate that the VO2+ ions in zinc lead borate glasses were present in octahedral sites with tetragonal compression and belong to C4V symmetry. The spin-Hamiltonian parameters g and A are found to be independent of V2O5 content and temperature but changing with ZnO content. The decrease in Deltag( parallel)/Deltag( perpendicular) value with increase in ZnO content indicates that the symmetry around VO2+ ions is more octahedral. The decrease in intensity of EPR signal above 10 mol% of V2O5 is attributed to a fall in the ratio of the number of V4+ ions (N4) to the number of V5+ ions (N5). The number of spins (N) participating in resonance was calculated as a function of temperature for VO2+ doped zinc lead borate glass sample and the activation energy was calculated. From the EPR data, the paramagnetic susceptibility was calculated at various temperatures and the Curie constant was evaluated from the 1/chi-T graph. The optical absorption spectra show single absorption band due to VO2+ ions in tetragonally distorted octahedral sites.

  9. 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).

  10. X-ray absorption and Mössbauer spectroscopies characterization of iron nanoclusters prepared by the gas aggregation technique.

    PubMed

    Sánchez-Marcos, J; Laguna-Marco, M A; Martínez-Morillas, R; Céspedes, E; Menéndez, N; Jiménez-Villacorta, F; Prieto, C

    2012-11-01

    Partially oxidized iron nanoclusters have been prepared by the gas-phase aggregation technique with typical sizes of 2-3 nm. This preparation technique has been reported to obtain clusters with interesting magnetic properties such as very large exchange bias. In this paper, a sample composition study carried out by Mössbauer and X-ray absorption spectroscopies is reported. The information reached by these techniques, which is based on the iron short range order, results to be an ideal way to have a characterization of the whole sample since the obtained data are an average over a very large amount of the clusters. In addition, our results indicate the presence of ferrihydrite, which is a compound typically ignored when studying this type of systems.

  11. Investigation of potential of differential absorption Lidar techniques for remote sensing of atmospheric pollutants

    NASA Technical Reports Server (NTRS)

    Butler, C. F.; Shipley, S. T.; Allen, R. J.

    1981-01-01

    The NASA multipurpose differential absorption lidar (DIAL) system uses two high conversion efficiency dye lasers which are optically pumped by two frequency-doubled Nd:YAG lasers mounted rigidly on a supporting structure that also contains the transmitter, receiver, and data system. The DIAL system hardware design and data acquisition system are described. Timing diagrams, logic diagrams, and schematics, and the theory of operation of the control electronics are presented. Success in obtaining remote measurements of ozone profiles with an airborne systems is reported and results are analyzed.

  12. 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…

  13. Laser absorption-scattering technique applied to asymmetric evaporating fuel sprays for simultaneous measurement of vapor/liquid mass distributions

    NASA Astrophysics Data System (ADS)

    Gao, J.; Nishida, K.

    2010-10-01

    This paper describes an Ultraviolet-Visible Laser Absorption-Scattering (UV-Vis LAS) imaging technique applied to asymmetric fuel sprays. Continuing from the previous studies, the detailed measurement principle was derived. It is demonstrated that, by means of this technique, cumulative masses and mass distributions of vapor/liquid phases can be quantitatively measured no matter what shape the spray is. A systematic uncertainty analysis was performed, and the measurement accuracy was also verified through a series of experiments on the completely vaporized fuel spray. The results show that the Molar Absorption Coefficient (MAC) of the test fuel, which is typically pressure and temperature dependent, is the major error source. The measurement error in the vapor determination has been shown to be approximately 18% under the assumption of constant MAC of the test fuel. Two application examples of the extended LAS technique were presented for exploring the dynamics and physical insight of the evaporating fuel sprays: diesel sprays injected by group-hole nozzles and gasoline sprays impinging on an inclined wall.

  14. Validation of phenol red versus gravimetric method for water reabsorption correction and study of gender differences in Doluisio's absorption technique.

    PubMed

    Tuğcu-Demiröz, Fatmanur; Gonzalez-Alvarez, Isabel; Gonzalez-Alvarez, Marta; Bermejo, Marival

    2014-10-01

    The aim of the present study was to develop a method for water flux reabsorption measurement in Doluisio's Perfusion Technique based on the use of phenol red as a non-absorbable marker and to validate it by comparison with gravimetric procedure. The compounds selected for the study were metoprolol, atenolol, cimetidine and cefadroxil in order to include low, intermediate and high permeability drugs absorbed by passive diffusion and by carrier mediated mechanism. The intestinal permeabilities (Peff) of the drugs were obtained in male and female Wistar rats and calculated using both methods of water flux correction. The absorption rate coefficients of all the assayed compounds did not show statistically significant differences between male and female rats consequently all the individual values were combined to compare between reabsorption methods. The absorption rate coefficients and permeability values did not show statistically significant differences between the two strategies of concentration correction. The apparent zero order water absorption coefficients were also similar in both correction procedures. In conclusion gravimetric and phenol red method for water reabsorption correction are accurate and interchangeable for permeability estimation in closed loop perfusion method. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Multilayer thin film design for far ultraviolet polarizers using an induced transmission and absorption technique

    NASA Technical Reports Server (NTRS)

    Kim, Jongmin; Zukic, Muamer; Torr, Douglas G.

    1993-01-01

    An explanation of induced transmission for spectral regions excluding the far ultraviolet (FUV) is given to better understand how induced transmission and absorption can be used to design effective polarizers in the FUV spectral region. We achieve high s-polarization reflectance and a high degree of polarization (P equals (Rs-Rp)/(Rs+Rp)) by means of a MgF2/Al/MgF2 three layer structure on an opaque thick film of Al as the substrate. For example, our polarizer designed for the Lyman-alpha line (lambda equals 121.6 nm) has 87.95 percent reflectance for the s-polarization case and 0.43 percent for the p-polarization case, with a degree of polarization of 99.03 percent. If a double reflection polarizer is made with this design, it will have a degree of polarization of 99.99 percent and s-polarization throughput of 77.35 percent.

  16. One-step fabrication of submicrostructures by low one-photon absorption direct laser writing technique with local thermal effect

    SciTech Connect

    Nguyen, Dam Thuy Trang; Tong, Quang Cong; Ledoux-Rak, Isabelle

    In this work, local thermal effect induced by a continuous-wave laser has been investigated and exploited to optimize the low one-photon absorption (LOPA) direct laser writing (DLW) technique for fabrication of polymer-based microstructures. It was demonstrated that the temperature of excited SU8 photoresist at the focusing area increases to above 100 °C due to high excitation intensity and becomes stable at that temperature thanks to the use of a continuous-wave laser at 532 nm-wavelength. This optically induced thermal effect immediately completes the crosslinking process at the photopolymerized region, allowing obtain desired structures without using the conventional post-exposure bake (PEB) step, which ismore » usually realized after the exposure. Theoretical calculation of the temperature distribution induced by local optical excitation using finite element method confirmed the experimental results. LOPA-based DLW technique combined with optically induced thermal effect (local PEB) shows great advantages over the traditional PEB, such as simple, short fabrication time, high resolution. In particular, it allowed the overcoming of the accumulation effect inherently existed in optical lithography by one-photon absorption process, resulting in small and uniform structures with very short lattice constant.« less

  17. Pre-Saturation Technique of the Recycled Aggregates: Solution to the Water Absorption Drawback in the Recycled Concrete Manufacture †

    PubMed Central

    García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-del Pozo, Julia Mª; Guerra-Romero, M. Ignacio

    2014-01-01

    The replacement of natural aggregates by recycled aggregates in the concrete manufacturing has been spreading worldwide as a recycling method to counteract the large amount of construction and demolition waste. Although legislation in this field is still not well developed, many investigations demonstrate the possibilities of success of this trend given that concrete with satisfactory mechanical and durability properties could be achieved. However, recycled aggregates present a low quality compared to natural aggregates, the water absorption being their main drawback. When used untreated in concrete mix, the recycled aggregate absorb part of the water initially calculated for the cement hydration, which will adversely affect some characteristics of the recycled concrete. This article seeks to demonstrate that the technique of pre-saturation is able to solve the aforementioned problem. In order to do so, the water absorption of the aggregates was tested to determine the necessary period of soaking to bring the recycled aggregates into a state of suitable humidity for their incorporation into the mixture. Moreover, several concrete mixes were made with different replacement percentages of natural aggregate and various periods of pre-saturation. The consistency and compressive strength of the concrete mixes were tested to verify the feasibility of the proposed technique. PMID:28788188

  18. Pseudorandom Noise Code-Based Technique for Thin Cloud Discrimination with CO2 and O2 Absorption Measurements

    NASA Technical Reports Server (NTRS)

    Campbell, Joel F.; Prasad, Narasimha S.; Flood, Michael A.

    2011-01-01

    NASA Langley Research Center is working on a continuous wave (CW) laser based remote sensing scheme for the detection of CO2 and O2 from space based platforms suitable for ACTIVE SENSING OF CO2 EMISSIONS OVER NIGHTS, DAYS, AND SEASONS (ASCENDS) mission. ASCENDS is a future space-based mission to determine the global distribution of sources and sinks of atmospheric carbon dioxide (CO2). A unique, multi-frequency, intensity modulated CW (IMCW) laser absorption spectrometer (LAS) operating at 1.57 micron for CO2 sensing has been developed. Effective aerosol and cloud discrimination techniques are being investigated in order to determine concentration values with accuracies less than 0.3%. In this paper, we discuss the demonstration of a pseudo noise (PN) code based technique for cloud and aerosol discrimination applications. The possibility of using maximum length (ML)-sequences for range and absorption measurements is investigated. A simple model for accomplishing this objective is formulated, Proof-of-concept experiments carried out using SONAR based LIDAR simulator that was built using simple audio hardware provided promising results for extension into optical wavelengths.

  19. One-step fabrication of submicrostructures by low one-photon absorption direct laser writing technique with local thermal effect

    NASA Astrophysics Data System (ADS)

    Nguyen, Dam Thuy Trang; Tong, Quang Cong; Ledoux-Rak, Isabelle; Lai, Ngoc Diep

    2016-01-01

    In this work, local thermal effect induced by a continuous-wave laser has been investigated and exploited to optimize the low one-photon absorption (LOPA) direct laser writing (DLW) technique for fabrication of polymer-based microstructures. It was demonstrated that the temperature of excited SU8 photoresist at the focusing area increases to above 100 °C due to high excitation intensity and becomes stable at that temperature thanks to the use of a continuous-wave laser at 532 nm-wavelength. This optically induced thermal effect immediately completes the crosslinking process at the photopolymerized region, allowing obtain desired structures without using the conventional post-exposure bake (PEB) step, which is usually realized after the exposure. Theoretical calculation of the temperature distribution induced by local optical excitation using finite element method confirmed the experimental results. LOPA-based DLW technique combined with optically induced thermal effect (local PEB) shows great advantages over the traditional PEB, such as simple, short fabrication time, high resolution. In particular, it allowed the overcoming of the accumulation effect inherently existed in optical lithography by one-photon absorption process, resulting in small and uniform structures with very short lattice constant.

  20. Measuring the molecular second hyperpolarizability in absorptive solutions by the third harmonic generation ratio technique.

    PubMed

    Tokarz, Danielle; Cisek, Richard; Prent, Nicole; Fekl, Ulrich; Barzda, Virginijus

    2012-11-28

    Measurement of the second hyperpolarizability (γ) values of compounds can provide insight into the molecular structural requirements for enhancement of third harmonic generation (THG) signal. A convenient method for measuring the γ of compounds in solutions was developed by implementing the THG ratio method which is based on measuring the THG intensity from two interfaces using a nonlinear optical microscope while accounting for the refractive index of solutions at the fundamental and third harmonic wavelengths. We demonstrated that the difference in refractive index at both wavelengths strongly influenced the calculation of γ values when compounds have absorption near the third harmonic or fundamental wavelength. To this end, a refractometer with the wavelength tuning range from UV to near IR was constructed, and the measured refractive indices were used to extract the γ values. The γ values of carotenoids and chlorophylls found in photosynthetic pigment-protein complexes were explored. Large differences in the refractive index at third harmonic and fundamental wavelengths for chlorophylls result in γ values that are more than two orders of magnitude larger than γ values for carotenoids as well as the sign of chlorophylls'γ values is negative while carotenoids have positive γ values. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Multilayer Thin Film Polarizer Design for Far Ultraviolet using Induced Transmission and Absorption Technique

    NASA Technical Reports Server (NTRS)

    Kim, Jongmin; Zukic, Muamer; Wilson, Michele M.; Park, Jung Ho; Torr, Douglas G.

    1994-01-01

    Good theoretical designs of far ultraviolet polarizers have been reported using a MgF2/Al/MgF2 three layer structure on a thick Al layer as a substrate. The thicknesses were determined to induce transmission and absorption of p-polarized light. In these designs Al optical constants were used from films produced in ultrahigh vacuum (UHV: 10(exp -10) torr). Reflectance values for polarizers fabricated in a conventional high vacuum (p approx. 10(exp -6 torr)) using the UHV design parameters differed dramatically from the design predictions. Al is a highly reactive material and is oxidized even in a high vacuum chamber. In order to solve the problem other metals have been studied. It is found that a larger reflectance difference is closely related to higher amplitude and larger phase difference of Fresnel reflection coefficients between two polarizations at the boundary of MgF2/metal. It is also found that for one material a larger angle of incidence from the surface normal brings larger amplitude and phase difference. Be and Mo are found good materials to replace Al. Polarizers designed for 121.6 nm with Be at 60 deg and with Mo at 70 deg are shown as examples.

  2. Screening Technique for Lead and Cadmium in Toys and Other Materials Using Atomic Absorption Spectroscopy

    ERIC Educational Resources Information Center

    Brouwer, Henry

    2005-01-01

    A simple procedure to quickly screen different consumer products for the presence of lead, cadmium, and other metals is described. This screening technique avoids expending a lot of preparation time on samples known to contain low levels of hazardous metals where only samples testing positive for the desired elements need to be analyzed…

  3. A technique for lyopreservation of Clostridium ljungdahlii in a biocomposite matrix for CO absorption

    SciTech Connect

    Schulte, Mark J.; Solocinski, Jason; Wang, Mian

    A system capable of biocatalytic conversion of distributed sources of single carbon gases such as carbon monoxide into hydrocarbons can be highly beneficial for developing commercially viable biotechnology applications in alternative energy. Several anaerobic bacterial strains can be used for such conversion. The anaerobic carbon monoxide-fixing bacteria Clostridium ljungdahlii OTA1 is a model CO assimilating microorganism that currently requires cryogenic temperature for storage of the viable strains. If these organisms can be stabilized and concentrated in thin films in advanced porous materials, it will enable development of high gas fraction, biocomposite absorbers with elevated carbon monoxide (CO) mass transfer rate,more » that require minimal power input and liquid, and demonstrate elevated substrate consumption rate compared to conventional suspended cell bioreactors. We report development of a technique for dry-stabilization of C. ljungdahlii OTA1 on a paper biocomposite. Bacterial samples coated onto paper were desiccated in the presence of trehalose using convective drying and stored at 4°C. Optimal dryness was ~1g H 2O per gram of dry weight (g DW). CO uptake directly following biocomposite rehydration steadily increases over time indicating immediate cellular metabolic recovery. A high-resolution Raman microspectroscopic hyperspectral imaging technique was employed to spatially quantify the residual moisture content. We have demonstrated for the first time that convectively dried and stored C. ljungdahlii strains were stabilized in a desiccated state for over 38 days without a loss in CO absorbing reactivity. The Raman hyperspectral imaging technique described here is a non-invasive characterization tool to support development of dry-stabilization techniques for microorganisms on inexpensive porous support materials. In conclusion, the present study successfully extends and implements the principles of dry-stabilization for preservation of strictly

  4. A Method for Eliminating Beam Steering Error for the Modulated Absorption-Emission Thermometry Technique

    DTIC Science & Technology

    2015-01-01

    emissivity and the radiative intensity of the gas over a spectral band. The temperature is then calculated from the Planck function. The technique does not...pressure budget for cooling channels reduces pump horsepower and turbine inlet temperature DISTRIBUTION STATEMENT A – Approved for public release...distribution unlimited 4 Status of Modeling and Simulation • Existing data set for film cooling effectiveness consists of wall heat flux measurements • CFD

  5. A technique for lyopreservation of Clostridium ljungdahlii in a biocomposite matrix for CO absorption

    DOE PAGES

    Schulte, Mark J.; Solocinski, Jason; Wang, Mian; ...

    2017-07-05

    A system capable of biocatalytic conversion of distributed sources of single carbon gases such as carbon monoxide into hydrocarbons can be highly beneficial for developing commercially viable biotechnology applications in alternative energy. Several anaerobic bacterial strains can be used for such conversion. The anaerobic carbon monoxide-fixing bacteria Clostridium ljungdahlii OTA1 is a model CO assimilating microorganism that currently requires cryogenic temperature for storage of the viable strains. If these organisms can be stabilized and concentrated in thin films in advanced porous materials, it will enable development of high gas fraction, biocomposite absorbers with elevated carbon monoxide (CO) mass transfer rate,more » that require minimal power input and liquid, and demonstrate elevated substrate consumption rate compared to conventional suspended cell bioreactors. We report development of a technique for dry-stabilization of C. ljungdahlii OTA1 on a paper biocomposite. Bacterial samples coated onto paper were desiccated in the presence of trehalose using convective drying and stored at 4°C. Optimal dryness was ~1g H 2O per gram of dry weight (g DW). CO uptake directly following biocomposite rehydration steadily increases over time indicating immediate cellular metabolic recovery. A high-resolution Raman microspectroscopic hyperspectral imaging technique was employed to spatially quantify the residual moisture content. We have demonstrated for the first time that convectively dried and stored C. ljungdahlii strains were stabilized in a desiccated state for over 38 days without a loss in CO absorbing reactivity. The Raman hyperspectral imaging technique described here is a non-invasive characterization tool to support development of dry-stabilization techniques for microorganisms on inexpensive porous support materials. In conclusion, the present study successfully extends and implements the principles of dry-stabilization for preservation of strictly

  6. 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.…

  7. Semi-Empirical Validation of the Cross-Band Relative Absorption Technique for the Measurement of Molecular Mixing Ratios

    NASA Technical Reports Server (NTRS)

    Pliutau, Denis; Prasad, Narasimha S

    2013-01-01

    Studies were performed to carry out semi-empirical validation of a new measurement approach we propose for molecular mixing ratios determination. The approach is based on relative measurements in bands of O2 and other molecules and as such may be best described as cross band relative absorption (CoBRA). . The current validation studies rely upon well verified and established theoretical and experimental databases, satellite data assimilations and modeling codes such as HITRAN, line-by-line radiative transfer model (LBLRTM), and the modern-era retrospective analysis for research and applications (MERRA). The approach holds promise for atmospheric mixing ratio measurements of CO2 and a variety of other molecules currently under investigation for several future satellite lidar missions. One of the advantages of the method is a significant reduction of the temperature sensitivity uncertainties which is illustrated with application to the ASCENDS mission for the measurement of CO2 mixing ratios (XCO2). Additional advantages of the method include the possibility to closely match cross-band weighting function combinations which is harder to achieve using conventional differential absorption techniques and the potential for additional corrections for water vapor and other interferences without using the data from numerical weather prediction (NWP) models.

  8. Determination of mercury in an assortment of dietary supplements using an inexpensive combustion atomic absorption spectrometry technique.

    PubMed

    Levine, Keith E; Levine, Michael A; Weber, Frank X; Hu, Ye; Perlmutter, Jason; Grohse, Peter M

    2005-01-01

    The concentrations of mercury in forty, commercially available dietary supplements, were determined using a new, inexpensive analysis technique. The method involves thermal decomposition, amalgamation, and detection of mercury by atomic absorption spectrometry with an analysis time of approximately six minutes per sample. The primary cost savings from this approach is that labor-intensive sample digestion is not required prior to analysis, further automating the analytical procedure. As a result, manufacturers and regulatory agencies concerned with monitoring lot-to-lot product quality may find this approach an attractive alternative to the more classical acid-decomposition, cold vapor atomic absorption methodology. Dietary supplement samples analyzed included astragalus, calcium, chromium picolinate, echinacea, ephedra, fish oil, ginger, ginkgo biloba, ginseng, goldenseal, guggul, senna, St John's wort, and yohimbe products. Quality control samples analyzed with the dietary supplements indicated a high level of method accuracy and precision. Ten replicate preparations of a standard reference material (NIST 1573a, tomato leaves) were analyzed, and the average mercury recovery was 109% (2.0% RSD). The method quantitation limit was 0.3 ng, which corresponded to 1.5 ng/g sample. The highest found mercury concentration (123 ng/g) was measured in a concentrated salmon oil sample. When taken as directed by an adult, this product would result in an approximate mercury ingestion of 7 mug per week.

  9. Absorption edge parameters of the LIII edge for compounds of Hg, Tl, Pb and Bi using EDXRF technique

    NASA Astrophysics Data System (ADS)

    Singh, Gurinderjeet; Singh, Amrit; Gupta, Manoj Kumar; Dhaliwal, A. S.; Kahlon, K. S.

    2018-03-01

    The measurement of Absorption edge parameters of the LIII edge of pure elements Hg, Tl, Pb and Bi along with their compounds HgCl2, HgO, HgF2, TlCl, Tl2O3, PbCl2, PbF2, Pb3O4, BiF3, BiCl3 and Bi2O3 has been done using EDXRF technique. In the present measurements 241Am (59.54 keV) radioactive source of activity 100 mCi along with CANBERRA make cryo-cooled Si (Li) detector is used. The measured results are compared with theoretically calculated values from FFAST version 2.1 (Chantler et al., 2005) and shows good agreement with each other within experimental uncertainties within 3.5%. It is observed that the values of absorption edge parameters of the LIII edge depends slightly on the chemical environment and shows almost constant behaviour with effective atomic number (Zeff)

  10. 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.

  11. The nature of C-class asteroids from 3-micron spectrophotometry

    NASA Technical Reports Server (NTRS)

    Feierberg, M. A.; Lebofsky, L. A.; Tholen, D. J.

    1985-01-01

    Narrowband spectrophotometry between 2.3 and 3.5 micrometers is presented for 14 main-belt C asteroids greater than 100 km in diameter. Absorption features at 3 micrometers due to water of hydration are present in the spectra of nine of the asteroids, with intensities ranging from 6 to 23 percent. The other five asteroids have no such absorption greater than 2 percent in intensity. The present C-asteroid population may be fragments of larger parent bodies with anhydrous C3-like cores and hydrated C1I- or C2M-like mantles.

  12. Contrastive Study on the Structure and the Ultraviolet Absorption Property of Multiple-Doped and Element-Doped ZnO Thin Films

    NASA Astrophysics Data System (ADS)

    Xu, Yunyun; Zhang, Tao; Lin, Zhenrong; Tian, Yanfeng; Zhou, Shandan

    Sb2O3- and CeO2-doped ZnO thin films were prepared by RF magnetron sputtering technique. The influence of Sb2O3 and CeO2 on the structure and ultraviolet (UV) absorption properties was studied by X-ray diffraction and UV-Vis spectrophotometry. Results show that multiple doping of films had a prominent effect on the development of crystal grains and the UV absorption property. Ce and Sb exist in many forms in the ZnO film. The multiple-doped films also show enhanced UVA absorption, and the UV absorption peak widens and the absorption intensity increases. Sb plays a dominant role on the structure and UV absorption of ZnO thin films, which are enhanced by Ce.

  13. Employing X-ray absorption technique for better detector resolution and measurement of low cross-section events

    NASA Astrophysics Data System (ADS)

    Sharma, Gaurav; Puri, Nitin K.; Kumar, Pravin; Nandi, T.

    2018-03-01

    The versatility of X-ray absorption technique is experimentally employed for enhancing the detector resolution and to rejuvenate the low probable transitions obscured in the pile-up region, during a beam-foil spectroscopy experiment. The multiple aluminum absorber layers (10 μm each) are used to suppress the pile-up contribution drastically and to restore a weak transition which is about 1.38 × 104 times weaker than a one-electron-one-photon transitions viz. Kα and Khα. The weak line is possibly originating from a two-electron-one-photon transition in He-like Ti. Further, the transitions, which were obscured in the spectra due to high intensity ratio, are revived by dissimilar line intensity attenuation using this technique. The measured lifetimes of Kα line with and without intensity attenuation match well within error bar. The present technique finds potential implications in understanding the structure of multiple-core-vacant ions and other low cross section processes in ion-solid collisions.

  14. 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.

  15. A technique for measurement of material damping in metals. [absorption of structural vibration

    NASA Technical Reports Server (NTRS)

    Heine, J. C.

    1976-01-01

    The paper outlines the theory, design, and application of an apparatus based on the single beam resonant dwell technique to determine the damping capacity of metallic materials by measuring the response of a structural element to excitation at a modal frequency. In this apparatus, a cantilever beam specimen of a test material is clamped to a bar which is connected at one end to an electromagnetic shaker and at the other to a heavy base. The thickness of the bar at the base end is reduced by two saw cuts to provide a pivot around which the remainder of the bar can rotate when excited by the shaker which is connected to the bar by a rod passing through a hole in the base. The response of the supporting system to shaker excitation is measured with an accelerometer mounted on the bar at the root of the specimen. Specimen response is measured optically with a low-power microscope with a reticle. Specimen loss factor is determined in terms of acceleration at the beam root, beam tip displacement, and the beam natural frequency.

  16. Analysis of diffential absorption lidar technique for measurements of anhydrous hydrogen chloride from solid rocket motors using a deuterium fluoride laser

    NASA Technical Reports Server (NTRS)

    Bair, C. H.; Allario, F.

    1977-01-01

    An active optical technique (differential absorption lidar (DIAL)) for detecting, ranging, and quantifying the concentration of anhydrous HCl contained in the ground cloud emitted by solid rocket motors (SRM) is evaluated. Results are presented of an experiment in which absorption coefficients of HCl were measured for several deuterium fluoride (DF) laser transitions demonstrating for the first time that a close overlap exists between the 2-1 P(3) vibrational transition of the DF laser and the 1-0 P(6) absorption line of HCl, with an absorption coefficient of 5.64 (atm-cm) to the -1 power. These measurements show that the DF laser can be an appropriate radiation source for detecting HCl in a DIAL technique. Development of a mathematical computer model to predict the sensitivity of DIAL for detecting anhydrous HCl in the ground cloud is outlined, and results that assume a commercially available DF laser as the radiation source are presented.

  17. Validation of an analytical method for the quantitative determination of selenium in bacterial biomass by ultraviolet-visible spectrophotometry.

    PubMed

    Mörschbächer, Ana Paula; Dullius, Anja; Dullius, Carlos Henrique; Bandt, Cassiano Ricardo; Kuhn, Daniel; Brietzke, Débora Tairini; Malmann Kuffel, Fernando José; Etgeton, Henrique Pretto; Altmayer, Taciélen; Gonçalves, Tamara Engelmann; Oreste, Eliézer Quadro; Ribeiro, Anderson Schwingel; de Souza, Claucia Fernanda Volken; Hoehne, Lucélia

    2018-07-30

    The present paper describes the validation of a spectrophotometry method involving molecular absorption in the visible ultraviolet-visible (UV-Vis) region for selenium (Se) determination in the bacterial biomass produced by lactic acid bacteria (LAB). The method was found to be suitable for the target application and presented a linearity range from 0.025 to 0.250 mg/L Se. The angular and linear coefficients of the linear equation were 1.0678 and 0.0197 mg/L Se, respectively, and the linear correlation coefficient (R 2 ) was 0.9991. Analyte recovery exceeded 96% with a relative standard deviation (RSD) below 3%. The Se contents in LAB ranged from 0.01 to 20 mg/g. The Se contents in the bacterial biomass determined by UV-Vis were not significantly different (p > 0.05) those determined by graphite furnace atomic absorption spectrometry. Thus, Se can be quantified in LAB biomass using this relatively simpler technique. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. 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.

  19. Tomographic multiaxis-differential optical absorption spectroscopy observations of Sun-illuminated targets: a technique providing well-defined absorption paths in the boundary layer

    NASA Astrophysics Data System (ADS)

    Frins, Erna; Bobrowski, Nicole; Platt, Ulrich; Wagner, Thomas

    2006-08-01

    A novel experimental procedure to measure the near-surface distribution of atmospheric trace gases by using passive multiaxis differential absorption optical spectroscopy (MAX-DOAS) is proposed. The procedure consists of pointing the receiving telescope of the spectrometer to nonreflecting surfaces or to bright targets placed at known distances from the measuring device, which are illuminated by sunlight. We show that the partial trace gas absorptions between the top of the atmosphere and the target can be easily removed from the measured total absorption. Thus it is possible to derive the average concentration of trace gases such as NO2, HCHO, SO2, H2O, Glyoxal, BrO, and others along the line of sight between the instrument and the target similar to the well-known long-path DOAS observations (but with much less expense). If tomographic arrangements are used, even two- or three-dimensional trace gas distributions can be retrieved. The basic assumptions of the proposed method are confirmed by test measurements taken across the city of Heidelberg.

  20. 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.

  1. Standardization and validation of a new atomic absorption spectroscopy technique for determination and quantitation of aluminium adjuvant in immunobiologicals.

    PubMed

    Mishra, Arti; Bhalla, Sumir Rai; Rawat, Sameera; Bansal, Vivek; Sehgal, Rakesh; Kumar, Sunil

    2007-10-01

    In the present study, Aluminium quantification in immunobiologicals has been described using atomic absorption spectroscopy (AAS) technique. The assay was found to be linear in 25-125 microg/ml Aluminium range. The procedure was found to be accurate for different vaccines with recoveries of external additions ranging between 93.26 and 103.41%. The mean Limit of Variation (L.V.) for both intra- and inter-assay precision was calculated to be 1.62 and 2.22%, respectively. Further the procedure was found to be robust in relation to digestion temperature, alteration in acid (HNO(3) and H(2)SO(4)) ratio used for sample digestion and storage of digested vaccine samples up to a period of 15 days. After validation, AAS method was compared for its equivalency with routinely used complexometric titration method. On simultaneously applying on seven different groups of both bacterial and viral vaccines, viz., DPT, DT, TT, Hepatitis-A and B, Antirabies vaccine (cell culture) and tetravalent DPT-Hib, a high degree of positive correlation (+0.85-0.998) among AAS and titration methods was observed. Further AAS method was found to have an edge over complexometric titration method that a group of vaccines, viz., ARV (cell culture, adsorbed) and Hepatitis-A, in which Aluminium estimation is not feasible by pharmacopoeial approved complexometric titration method (possibly due to some interference in the sample matrix), this newly described and validated AAS assay procedure delivered accurate and reproducible results.

  2. Applications of the direct photon absorption technique for measuring bone mineral content in vivo. Determination of body composition in vivo

    NASA Technical Reports Server (NTRS)

    Cameron, J. R.

    1972-01-01

    The bone mineral content, BMC, determined by monoenergetic photon absorption technique, of 29 different locations on the long bones and vertebral columns of 24 skeletons was measured. Compressive tests were made on bone from these locations in which the maximum load and maximum stress were measured. Also the ultimate strain, modulus of elasticity and energy absorbed to failure were determined for compact bone from the femoral diaphysis and cancellous bone from the eighth through eleventh thoracic vertebrae. Correlations and predictive relationships between these parameters were examined to investigate the applicability of using the BMC at sites normally measured in vivo, i.e. radius and ulna in estimating the BMC and/or strength of the spine or femoral neck. It was found that the BMC at sites on the same bone were highly correlated r = 0.95 or better; the BMC at sites on different bones were also highly interrelated, r = 0.85. The BMC at various sites on the long bones could be estimated to between 10 and 15 per cent from the BMC of sites on the radius or ulna.

  3. An efficient and accurate technique to compute the absorption, emission, and transmission of radiation by the Martian atmosphere

    NASA Technical Reports Server (NTRS)

    Lindner, Bernhard Lee; Ackerman, Thomas P.; Pollack, James B.

    1990-01-01

    CO2 comprises 95 pct. of the composition of the Martian atmosphere. However, the Martian atmosphere also has a high aerosol content. Dust particles vary from less than 0.2 to greater than 3.0. CO2 is an active absorber and emitter in near IR and IR wavelengths; the near IR absorption bands of CO2 provide significant heating of the atmosphere, and the 15 micron band provides rapid cooling. Including both CO2 and aerosol radiative transfer simultaneously in a model is difficult. Aerosol radiative transfer requires a multiple scattering code, while CO2 radiative transfer must deal with complex wavelength structure. As an alternative to the pure atmosphere treatment in most models which causes inaccuracies, a treatment was developed called the exponential sum or k distribution approximation. The chief advantage of the exponential sum approach is that the integration over k space of f(k) can be computed more quickly than the integration of k sub upsilon over frequency. The exponential sum approach is superior to the photon path distribution and emissivity techniques for dusty conditions. This study was the first application of the exponential sum approach to Martian conditions.

  4. COMPENSATIONAL THREE-WAVELENGTH DIFFERENTIAL-ABSORPTION LIDAR TECHNIQUE FOR REDUCING THE INFLUENCE OF DIFFERENTIAL SCATTERING ON OZONE-CONCENTRATION MEASUREMENTS.

    EPA Science Inventory

    A three-wavelength differential-absorption lidar (DIAL) technique for the UV spectral region is presented that reduces the influence of aerosol differential scattering on measured O3-concentration profiles. The principal advantage of this approach is that, to a good first approxi...

  5. Mercury in Environmental and Biological Samples Using Online Combustion with Sequential Atomic Absorption and Fluorescence Measurements: A Direct Comparison of Two Fundamental Techniques in Spectrometry

    ERIC Educational Resources Information Center

    Cizdziel, James V.

    2011-01-01

    In this laboratory experiment, students quantitatively determine the concentration of an element (mercury) in an environmental or biological sample while comparing and contrasting the fundamental techniques of atomic absorption spectrometry (AAS) and atomic fluorescence spectrometry (AFS). A mercury analyzer based on sample combustion,…

  6. Nonlinear absorption in single LaF3 and MgF2 layers at 193 nm measured by surface sensitive laser induced deflection technique

    SciTech Connect

    Muehlig, Christian; Bublitz, Simon; Kufert, Siegfried

    2009-12-10

    We report nonlinear absorption data of LaF3 and MgF2 single layers at 193 nm. A highly surface sensitive measurement strategy of the laser induced deflection technique is introduced and applied to measure the absorption of highly transparent thin films independently of the substrate absorption. Linear absorptions k=({alpha}x{lambda})/4{pi} of 2x10{sup -4} and 8.5x10{sup -4} (LaF3) and 1.8x10{sup -4} and 6.9x10{sup -4} (MgF2) are found. Measured two photon absorption (TPA) coefficients are {beta}=1x10{sup -4} cm/W (LaF3), 1.8x10{sup -5}, and 5.8x10{sup -5} cm/W (MgF2). The TPA coefficients are several orders of magnitude higher than typical values for fluoride single crystals, which is likelymore » to result from sequential two step absorption processes.« less

  7. Analysis of rainwater dissolved organic carbon compounds using fluorescence spectrophotometry

    NASA Astrophysics Data System (ADS)

    Muller, Catherine L.; Baker, Andy; Hutchinson, Robert; Fairchild, Ian J.; Kidd, Chris

    Global rainwater dissolved organic carbon (DOC) flux was recently estimated as 430 × 10 12 g C yr -1, yet little is known about the wide range of chemical compounds present, their sources, temporal patterns of variation, and the subsequent impact on climate and the environment. Precipitation events were sampled in Birmingham, UK between April 2005 and May 2007. Rainwater DOC compounds were analysed using fluorescence spectrophotometry. Three fluorophores were identified: HUmic-LIke Substances (HULIS), TYrosine-LIke Substances (TYLIS) and TRYptophan-LIke Substances (TRYLIS). Peak fluorescence intensities and locations for each substance were examined, and their variations with various meteorological parameters were investigated. The mean HULIS fluorescence intensity from all events was 209 a.u. (with sample fluorescence ranging from 37 a.u. to 995 a.u); mean fluorescence intensity was 469 a.u. (214-988 a.u) and 265 a.u. (50-876 a.u.) for TYLIS and TRYLIS, respectively. Results indicate that highest HULIS fluorescence intensities are experienced during convective events and events of continental origin, suggesting terrestrial/anthropogenic sources. Under well-mixed conditions, HULIS fluorescence intensity decreases, whereas during low wind speed, stagnation of the atmosphere results in higher fluorescence intensities, attributed to a build up of localised sources, particularly anthropogenic. TYLIS and TRYLIS did not show any significant trends for the meteorological variables. Fluorescence spectrophotometry is a fast, non-invasive technique which is demonstrated to be a powerful means of fingerprinting rainfall DOC compounds in real time for small sample volumes.

  8. Spectrophotometry of Artemisia tridentata to quantitatively determine subspecies

    USGS Publications Warehouse

    Richardson, Bryce; Boyd, Alicia; Tobiasson, Tanner; Germino, Matthew

    2018-01-01

    Ecological restoration is predicated on our abilities to discern plant taxa. Taxonomic identification is a first step in ensuring that plants are appropriately adapted to the site. An example of the need to identify taxonomic differences comes from big sagebrush (Artemisia tridentata). This species is composed of three predominant subspecies occupying distinct environmental niches, but overlap and hybridization are common in ecotones. Restoration of A. tridentata largely occurs using wildland collected seed, but there is uncertainty in the identification of subspecies or mix of subspecies from seed collections. Laboratory techniques that can determine subspecies composition would be desirable to ensure that subspecies match the restoration site environment. In this study, we use spectrophotometry to quantify chemical differences in the water-soluble compound, coumarin. Ultraviolet (UV) absorbance of A. tridentata subsp. vaseyana showed distinct differences among A.t. tridentata and wyomingensis. No UV absorbance differences were detected between A.t. tridentata and wyomingensis. Analyses of samples from > 600 plants growing in two common gardens showed that UV absorbance was unaffected by environment. Moreover, plant tissues (leaves and seed chaff) explained only a small amount of the variance. UV fluorescence of water-eluted plant tissue has been used for many years to indicate A.t. vaseyana; however, interpretation has been subjective. Use of spectrophotometry to acquire UV absorbance provides empirical results that can be used in seed testing laboratories using the seed chaff present with the seed to certify A. tridentata subspecies composition. On the basis of our methods, UV absorbance values 3.1 would indicate either A.t. tridentata or wyomingensis. UV absorbance values between 2.7 and 3.1 would indicate a mixture of A.t. vaseyana and the other two subspecies.

  9. [Wavelength Selection in Hemolytic Evaluation Systems with Spectrophotometry Detection].

    PubMed

    Zhang, Hong; Su, Baochang; Ye, Xunda; Luo, Man

    2016-04-01

    Spectrophotometry is a simple hemolytic evaluation method commonly used in new drugs,biomedical materials and blood products.It is for the quantitative analysis of the characteristic absorption peaks of hemoglobin.Therefore,it is essential to select the correct detection wavelength when the evaluation system has influences on the conformation of hemoglobin.Based on the study of changes in the characteristic peaks over time of the hemolysis supernatant in four systems,namely,cell culture medium,phosphate buffered saline(PBS),physiological saline and banked blood preservation solution,using continuous wavelength scanning,the selections of detection wavelength were proposed as follows.In the cell culture medium system,the wavelength of 415 nm should be selected within 4h;,near 408 nm should be selected within 4~72h.In PBS system,within 4h,541 nm,577nm or 415 nm should be selected;4~72h,541 nm,577nm or near 406 nm should be selected.In physiological saline system,within 4h,414 nm should be selected;4~72h,near 405 nm should be selected;within 12 h,541nm or 577 nm could also be selected.In banked blood preservation solution system,within 72 h,415nm,540 nm or 576 nm should be selected.

  10. Comparison of different Aethalometer correction schemes and a reference multi-wavelength absorption technique for ambient aerosol data

    NASA Astrophysics Data System (ADS)

    Saturno, Jorge; Pöhlker, Christopher; Massabò, Dario; Brito, Joel; Carbone, Samara; Cheng, Yafang; Chi, Xuguang; Ditas, Florian; Hrabě de Angelis, Isabella; Morán-Zuloaga, Daniel; Pöhlker, Mira L.; Rizzo, Luciana V.; Walter, David; Wang, Qiaoqiao; Artaxo, Paulo; Prati, Paolo; Andreae, Meinrat O.

    2017-08-01

    Deriving absorption coefficients from Aethalometer attenuation data requires different corrections to compensate for artifacts related to filter-loading effects, scattering by filter fibers, and scattering by aerosol particles. In this study, two different correction schemes were applied to seven-wavelength Aethalometer data, using multi-angle absorption photometer (MAAP) data as a reference absorption measurement at 637 nm. The compensation algorithms were compared to five-wavelength offline absorption measurements obtained with a multi-wavelength absorbance analyzer (MWAA), which serves as a multiple-wavelength reference measurement. The online measurements took place in the Amazon rainforest, from the wet-to-dry transition season to the dry season (June-September 2014). The mean absorption coefficient (at 637 nm) during this period was 1.8 ± 2.1 Mm-1, with a maximum of 15.9 Mm-1. Under these conditions, the filter-loading compensation was negligible. One of the correction schemes was found to artificially increase the short-wavelength absorption coefficients. It was found that accounting for the aerosol optical properties in the scattering compensation significantly affects the absorption Ångström exponent (åABS) retrievals. Proper Aethalometer data compensation schemes are crucial to retrieve the correct åABS, which is commonly implemented in brown carbon contribution calculations. Additionally, we found that the wavelength dependence of uncompensated Aethalometer attenuation data significantly correlates with the åABS retrieved from offline MWAA measurements.

  11. Reliability of a new technique for the determination of vitamin B12 absorption in children: single stool sample test--a double isotope technique

    SciTech Connect

    Hjelt, K.

    1986-03-01

    The fractional vitamin B12 absorption (FAB12) was determined in 39 patients with various gastrointestinal diseases by a double-isotope technique, employing a single stool sample test (SSST), as well as a complete stool collection. The age of the patients ranged from 2.5 months to 16.2 years (mean 5.0 years). The test dose was administered orally and consisted of 0.5-4.5 micrograms of /sup 57/CoB12 (approximately 0.05 microCi), carmine powder, and 2 mg /sup 51/CrCl/sub 3/ (approximately 1.25 microCi) as the inabsorbable tracer. The wholebody radiation to a 1-year-old child averaged only 20 mrad. The stool and napkin was collected and homogenized bymore » addition of 300 ml chromium sulfuric acid. A 300-ml sample of the homogenized stool and napkin, as well as 300 ml chromium sulfuric acid (75% v/v) containing the standards, were counted in a broad-based well counter. The FAB12 determined by SSST employing the stool with the highest content of /sup 51/Cr (which corresponded to the most carmine-colored stool) correlated closely to the FAB12 based on complete stool collection (r = 0.98, n = 39, p less than 0.001). The reproducibility of FAB12 determined by SSST was assessed from double assays in 19 patients. For a mean value of 12%, the SD was 3%, which corresponded to a coefficient of variation (CV) of 25%. The excretion of /sup 57/Co and /sup 51/Cr in the urine was examined in six patients with moderate to severe mucosal damage and was found to be low.« less

  12. Analysis of algebraic reconstruction technique for accurate imaging of gas temperature and concentration based on tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Hui-Hui, Xia; Rui-Feng, Kan; Jian-Guo, Liu; Zhen-Yu, Xu; Ya-Bai, He

    2016-06-01

    An improved algebraic reconstruction technique (ART) combined with tunable diode laser absorption spectroscopy(TDLAS) is presented in this paper for determining two-dimensional (2D) distribution of H2O concentration and temperature in a simulated combustion flame. This work aims to simulate the reconstruction of spectroscopic measurements by a multi-view parallel-beam scanning geometry and analyze the effects of projection rays on reconstruction accuracy. It finally proves that reconstruction quality dramatically increases with the number of projection rays increasing until more than 180 for 20 × 20 grid, and after that point, the number of projection rays has little influence on reconstruction accuracy. It is clear that the temperature reconstruction results are more accurate than the water vapor concentration obtained by the traditional concentration calculation method. In the present study an innovative way to reduce the error of concentration reconstruction and improve the reconstruction quality greatly is also proposed, and the capability of this new method is evaluated by using appropriate assessment parameters. By using this new approach, not only the concentration reconstruction accuracy is greatly improved, but also a suitable parallel-beam arrangement is put forward for high reconstruction accuracy and simplicity of experimental validation. Finally, a bimodal structure of the combustion region is assumed to demonstrate the robustness and universality of the proposed method. Numerical investigation indicates that the proposed TDLAS tomographic algorithm is capable of detecting accurate temperature and concentration profiles. This feasible formula for reconstruction research is expected to resolve several key issues in practical combustion devices. Project supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 61205151), the National Key Scientific Instrument and Equipment Development Project of China (Grant

  13. 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.

  14. A tomographic technique for the simultaneous imaging of temperature, chemical species, and pressure in reactive flows using absorption spectroscopy with frequency-agile lasers

    SciTech Connect

    Cai, Weiwei; Kaminski, Clemens F., E-mail: cfk23@cam.ac.uk

    2014-01-20

    This paper proposes a technique that can simultaneously retrieve distributions of temperature, concentration of chemical species, and pressure based on broad bandwidth, frequency-agile tomographic absorption spectroscopy. The technique holds particular promise for the study of dynamic combusting flows. A proof-of-concept numerical demonstration is presented, using representative phantoms to model conditions typically prevailing in near-atmospheric or high pressure flames. The simulations reveal both the feasibility of the proposed technique and its robustness. Our calculations indicate precisions of ∼70 K at flame temperatures and ∼0.05 bars at high pressure from reconstructions featuring as much as 5% Gaussian noise in the projections.

  15. 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.

  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. Studying the local structures of novel materials using the Extended X-ray Absorption Fine Structure technique

    NASA Astrophysics Data System (ADS)

    Jiang, Yu

    2009-12-01

    In this dissertation, investigations on the local lattice structures for a variety of novel materials using Extended X-ray Absorption Fine Structure (EXAFS) technique are presented. Different experiment schemes were applied to obtain EXAFS data with high quality, and some interesting results were obtained by careful analysis. The power of the EXAFS technique was once again proved. In Chapter 1, I first briefly introduce the EXAFS theory and experiments, then give readers who are not familiar with this technique a short introduction on data reduction and analysis, and finally discuss some problems that are easily ignored in the interpretation of the experiment results. In Chapter 2, a temperature-dependent EXAFS investigation of La 1-xCaxMnO 3 is presented for the concentration range that spans the ferromagnetic-insulator (FMI) to ferromagnetic-metal (FMM) transition region, x = 0.16, 0.18, 0.20, and 0.22; the titrated hole concentrations are slightly higher y = 0.2, 0.22, 0.24, and 0.25 respectively. In Chapter 3, I report EXAFS studies of n- and p-type Ba8Ga 16Ge30 samples (type I clathrate) at the Ga, Ge, and Ba K-edges, to probe the local structure, particularly around the Ba atoms located inside 20- and 24-atom cages (Ba1 and Ba2 sites respectively) formed of Ga/Ge atoms. In agreement with diffraction analysis we find Ba2 is off-center, with a component in the bc plane (0.15 A) comparable to that found in diffraction; however, under the assumption of a stiff cage we also require a significant a component. This suggests a coupling or attraction between the Ba2 atoms and the hexagonal rings at the top or bottom of the cage that encloses the Ba2 site. In Chapter 4, I report detailed degradation and rejuvenation studies for AC electro-luminescence (EL) devices made using the phosphor ZnS:Cu,CI. We find that the AC EL emission spectra vary considerably with AC driving frequency but all spectra can be fit to a sum of four Gaussians. The combined experiments place

  18. Understanding of sub-band gap absorption of femtosecond-laser sulfur hyperdoped silicon using synchrotron-based techniques

    PubMed Central

    Limaye, Mukta V.; Chen, S. C.; Lee, C. Y.; Chen, L. Y.; Singh, Shashi B.; Shao, Y. C.; Wang, Y. F.; Hsieh, S. H.; Hsueh, H. C.; Chiou, J. W.; Chen, C. H.; Jang, L. Y.; Cheng, C. L.; Pong, W. F.; Hu, Y. F.

    2015-01-01

    The correlation between sub-band gap absorption and the chemical states and electronic and atomic structures of S-hyperdoped Si have been extensively studied, using synchrotron-based x-ray photoelectron spectroscopy (XPS), x-ray absorption near-edge spectroscopy (XANES), extended x-ray absorption fine structure (EXAFS), valence-band photoemission spectroscopy (VB-PES) and first-principles calculation. S 2p XPS spectra reveal that the S-hyperdoped Si with the greatest (~87%) sub-band gap absorption contains the highest concentration of S2− (monosulfide) species. Annealing S-hyperdoped Si reduces the sub-band gap absorptance and the concentration of S2− species, but significantly increases the concentration of larger S clusters [polysulfides (Sn2−, n > 2)]. The Si K-edge XANES spectra show that S hyperdoping in Si increases (decreased) the occupied (unoccupied) electronic density of states at/above the conduction-band-minimum. VB-PES spectra evidently reveal that the S-dopants not only form an impurity band deep within the band gap, giving rise to the sub-band gap absorption, but also cause the insulator-to-metal transition in S-hyperdoped Si samples. Based on the experimental results and the calculations by density functional theory, the chemical state of the S species and the formation of the S-dopant states in the band gap of Si are critical in determining the sub-band gap absorptance of hyperdoped Si samples. PMID:26098075

  19. Influence of Ga doping ratio on the saturable absorption mechanism in Ga doped ZnO thin solid films processed by sol-gel spin coating technique

    NASA Astrophysics Data System (ADS)

    Sandeep, K. M.; Bhat, Shreesha; Dharmaprakash, S. M.; Byrappa, K.

    2017-03-01

    In the present study, the nonlinear optical properties of sol-gel spin coated gallium doped zinc oxide (GZO) thin solid films are explored with nanosecond laser pulses using the z-scan technique. The higher doping ratios of Ga result in a large redshift of the energy gap (0.38 eV) due to the existence of enhanced grain boundary defects in GZO films. A positive nonlinear absorption coefficient is observed in undoped 1 at.wt.% GZO and 2 at.wt.% GZO films, and a negative nonlinear absorption coefficient in 3 at.wt.% GZO film. Fewer defects in undoped 1% GZO and 2% GZO films resulted in reverse saturable absorption (RSA), whereas a saturable absorption (SA) mechanism is observed in 3% GZO films and is attributed to the enhanced defect concentration in the band structure of GZO. However, all the films showed a self-defocusing mechanism, derived by a closed aperture z-scan technique. The present work sheds light on the defect mechanism involved in the observed nonlinear properties of GZO films.

  20. ABO grouping of highly-dilute blood by the absorption-elution technique using nitrocellulose beads--application to a casework investigation.

    PubMed

    Fujitani, N; Matoba, R; Kobayashi, T; Matsuda, H; Yoshida, K; Fukita, K

    1991-04-01

    This paper reports a homicidal case in which the absorption-elution technique using nitrocellulose beads as immunoadsorbents was successfully applied to ABO grouping from highly-diluted blood. A 21-year-old man was found dead in bed while staying in a hotel. He had multiple wounds over the entire body. By autopsy the cause of death was decided to be traumatic shock. The victim's blood group was A. A bucket filled with faint-colored water was found at the scene. By means of the absorption-elution technique using nitrocellulose beads the water was grouped as B. Later, a 32-year-old man staying in the hotel together with the victim was suspected and arrested. The suspect's blood group was B. He confessed that he had injured himself in the hands with a knife during the struggle and washed them in the water.

  1. Rocket-borne instrumentation using the resonant absorption technique to study the geocoronal and interplanetary helium emissions.

    PubMed

    Crifo, J F; Fahr, H J; Seidi, P; Wulf-Mathies, C

    1979-09-01

    A rocket payload able to perform a thorough and independent analysis of the He I 58.43340-nm geocoronal and interplanetary emissions is presented. It includes a sun-pointed resonant absorption spectrometer and a sky-scanning resonant absorption photometer. Both incorporate a similar helium resonance cell of original design featuring a most flexible pressure scanning capability and an accurate pressure measuring device, so that scanning by wavelength bandpasses from 20 down to 1 pm can be achieved. A description of the design and calibration of the instrument is given, followed by an indication of its successful operation in flight.

  2. [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.

  3. In vitro prediction of gastrointestinal absorption of novel β-hydroxy-β-arylalkanoic acids using PAMPA technique.

    PubMed

    Savić, Jelena; Dobričić, Vladimir; Nikolic, Katarina; Vladimirov, Sote; Dilber, Sanda; Brborić, Jasmina

    2017-03-30

    Prediction of gastrointestinal absorption of thirteen newly synthesized β-hydroxy-β-arylalkanoic acids (HAA) and ibuprofen was performed using PAMPA test. The highest values of PAMPA parameters (%T and P app ) were calculated for 1C, 1B and 2C and these parameters were significantly lower in comparison to ibuprofen. QSPR analysis was performed in order to identify molecular descriptors with the highest influence on %T and -logP app and to create models which could be used for the design of novel HAA with improved gastrointestinal absorption. Obtained results indicate that introduction of branched side chain, as well as introduction of substituents on one phenyl ring (which disturb symmetry of the molecule) could have positive impact on gastrointestinal absorption. On the basis of these results, six novel HAA were designed and PAMPA parameters %T and -logP app were predicted by use of selected QSPR models. Designed derivatives should have better gastrointestinal absorption than HAA tested in this study. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Recording of absorption spectra by a three-beam integral technique with a tunable laser and external cavity

    NASA Astrophysics Data System (ADS)

    Korolenko, P. V.; Nikolaev, I. V.; Ochkin, V. N.; Tskhai, S. N.

    2014-04-01

    An integral method is considered for recording absorption using three laser beams transmitted through and reflected from an external cavity with the absorbing medium (R-ICOS). The method is the elaboration of a known single-beam ICOS method and allows suppression of the influence of radiation phase fluctuations in the resonator on recording weak absorption spectra. First of all, this reduces high-frequency instabilities and gives a possibility to record spectra during short time intervals. In this method, mirrors of the resonator may have moderate reflection coefficients. Capabilities of the method have been demonstrated by the examples of weak absorption spectra of atmospheric methane and natural gas in a spectral range around 1650 nm. With the mirrors having the reflection coefficients of 0.8-0.99, a spectrum can be recorded for 320 μs with the accuracy sufficient for detecting a background concentration of methane in atmosphere. For the acquisition time of 20 s, the absorption coefficients of ~2×10-8 cm-1 can be measured, which corresponds to a 40 times less molecule concentration than the background value.

  5. The brilliant blue FCF ion-molecular forms in solutions according to the spectrophotometry data

    NASA Astrophysics Data System (ADS)

    Chebotarev, A. N.; Bevziuk, K. V.; Snigur, D. V.; Bazel, Ya. R.

    2017-10-01

    The brilliant blue FCF acid-base properties in aqueous solutions have been studied and its ionization constants have been defined by tristimulus colorimetry and spectrophotometry methods. The scheme of the acid-base dye equilibrium has been proposed and a diagram of the distribution of its ionic-molecular forms has been built. It has been established that the dominant form of the dye was the electroneutral form, which molar absorptivity (ɛ625 = 0.97 × 105) increases with the increase of the dielectric permittivity of the solvent. It has been shown that the replacement of polar solvents by less polar ones is causing a bathochromic shift of the maximum absorption band of the dye, the value of which is correlated with the value of the Hansen parameter. Tautomerization constants have been defined in a number of solvents and associated with the value of the Dimroth-Reichardt parameter.

  6. Masked-backlighter technique used to simultaneously image x-ray absorption and x-ray emission from an inertial confinement fusion plasma.

    PubMed

    Marshall, F J; Radha, P B

    2014-11-01

    A method to simultaneously image both the absorption and the self-emission of an imploding inertial confinement fusion plasma has been demonstrated on the OMEGA Laser System. The technique involves the use of a high-Z backlighter, half of which is covered with a low-Z material, and a high-speed x-ray framing camera aligned to capture images backlit by this masked backlighter. Two strips of the four-strip framing camera record images backlit by the high-Z portion of the backlighter, while the other two strips record images aligned with the low-Z portion of the backlighter. The emission from the low-Z material is effectively eliminated by a high-Z filter positioned in front of the framing camera, limiting the detected backlighter emission to that of the principal emission line of the high-Z material. As a result, half of the images are of self-emission from the plasma and the other half are of self-emission plus the backlighter. The advantage of this technique is that the self-emission simultaneous with backlighter absorption is independently measured from a nearby direction. The absorption occurs only in the high-Z backlit frames and is either spatially separated from the emission or the self-emission is suppressed by filtering, or by using a backlighter much brighter than the self-emission, or by subtraction. The masked-backlighter technique has been used on the OMEGA Laser System to simultaneously measure the emission profiles and the absorption profiles of polar-driven implosions.

  7. Temperature dependence of the optical absorption spectra of InP/ZnS quantum dots

    NASA Astrophysics Data System (ADS)

    Savchenko, S. S.; Vokhmintsev, A. S.; Weinstein, I. A.

    2017-03-01

    The optical-absorption spectra of InP/ZnS (core/shell) quantum dots have been studied in a broad temperature range of T = 6.5-296 K. Using the second-order derivative spectrophotometry technique, the energies of optical transitions at room temperature were found to be E 1 = 2.60 ± 0.02 eV (for the first peak of excitonic absorption in the InP core) and E 2 = 4.70 ± 0.02 eV (for processes in the ZnS shell). The experimental curve of E 1( T) has been approximated for the first time in the framework of a linear model and in terms of the Fan's formula. It is established that the temperature dependence of E 1 is determined by the interaction of excitons and longitudinal acoustic phonons with hω = 15 meV.

  8. Marine Particulate Absorption Techniques and Applications in the Study of Inherent and Apparent Optical Properties of the Ocean

    DTIC Science & Technology

    1992-01-01

    Meteortpl.. 24. 193-205. 1985. Bricaud. . . Morel, and L. Prieur. Absorption by dissolved Kalle . K .. What do we know about the ’Glso’. nor.10...Oceanogr.. 26. 43-53. 1991. Kalle . K .. The problem of Gelbstoff in the sea. Oceanogr. Mar. Bricaud..5A. Morel, and L. Prieur. Optical efficiency factors of...with report. Carder, K . L, S. K . Hawes, K . A. Baker, R. C. Smith, R. G. Steward, B. G. Mitchell. 1991. Reflectance model for quantifying chlorophyll a

  9. Resonance lamp absorption technique for simultaneous determination of the OH concentration and temperature at 10 spatial positions in combustion environments

    NASA Technical Reports Server (NTRS)

    Shirinzadeh, B.; Gregory, Ray W.

    1994-01-01

    A rugged, easy to implement, line-of-sight absorption instrument which utilizes a low pressure water vapor microwave discharge cell as the light source, has been developed to make simultaneous measurements of the OH concentration and temperature at 10 spatial positions. The design, theory, and capability of the instrument are discussed. Results of the measurements obtained on a methane/air flat flame burner are compared with those obtained using a single-frequency, tunable dye laser system.

  10. The role of spectrophotometry in the diagnosis of melanoma

    PubMed Central

    2010-01-01

    Background Spectrophotometry (SPT) could represent a promising technique for the diagnosis of cutaneous melanoma (CM) at earlier stages of the disease. Starting from our experience, we further assessed the role of SPT in CM early detection. Methods During a health campaign for malignant melanoma at National Cancer Institute of Naples, we identified a subset of 54 lesions to be addressed to surgical excision and histological examination. Before surgery, all patients were investigated by clinical and epiluminescence microscopy (ELM) screenings; selected lesions underwent spectrophotometer analysis. For SPT, we used a video spectrophotometer imaging system (Spectroshade® MHT S.p.A., Verona, Italy). Results Among the 54 patients harbouring cutaneous pigmented lesions, we performed comparison between results from the SPT screening and the histological diagnoses as well as evaluation of both sensitivity and specificity in detecting CM using either SPT or conventional approaches. For all pigmented lesions, agreement between histology and SPT classification was 57.4%. The sensitivity and specificity of SPT in detecting melanoma were 66.6% and 76.2%, respectively. Conclusions Although SPT is still considered as a valuable diagnostic tool for CM, its low accuracy, sensitivity, and specificity represent the main hamper for the introduction of such a methodology in clinical practice. Dermoscopy remains the best diagnostic tool for the preoperative diagnosis of pigmented skin lesions. PMID:20707921

  11. The role of spectrophotometry in the diagnosis of melanoma.

    PubMed

    Ascierto, Paolo A; Palla, Marco; Ayala, Fabrizio; De Michele, Ileana; Caracò, Corrado; Daponte, Antonio; Simeone, Ester; Mori, Stefano; Del Giudice, Maurizio; Satriano, Rocco A; Vozza, Antonio; Palmieri, Giuseppe; Mozzillo, Nicola

    2010-08-13

    Spectrophotometry (SPT) could represent a promising technique for the diagnosis of cutaneous melanoma (CM) at earlier stages of the disease. Starting from our experience, we further assessed the role of SPT in CM early detection. During a health campaign for malignant melanoma at National Cancer Institute of Naples, we identified a subset of 54 lesions to be addressed to surgical excision and histological examination. Before surgery, all patients were investigated by clinical and epiluminescence microscopy (ELM) screenings; selected lesions underwent spectrophotometer analysis. For SPT, we used a video spectrophotometer imaging system (Spectroshade MHT S.p.A., Verona, Italy). Among the 54 patients harbouring cutaneous pigmented lesions, we performed comparison between results from the SPT screening and the histological diagnoses as well as evaluation of both sensitivity and specificity in detecting CM using either SPT or conventional approaches. For all pigmented lesions, agreement between histology and SPT classification was 57.4%. The sensitivity and specificity of SPT in detecting melanoma were 66.6% and 76.2%, respectively. Although SPT is still considered as a valuable diagnostic tool for CM, its low accuracy, sensitivity, and specificity represent the main hamper for the introduction of such a methodology in clinical practice. Dermoscopy remains the best diagnostic tool for the preoperative diagnosis of pigmented skin lesions.

  12. Combination of rice husk and coconut shell activated adsorbent to adsorb Pb(II) ionic metal and it’s analysis using solid-phase spectrophotometry (sps)

    NASA Astrophysics Data System (ADS)

    Rohmah, D. N.; Saputro, S.; Masykuri, M.; Mahardiani, L.

    2018-03-01

    The purpose of this research was to know the effect and determine the mass comparation which most effective combination between rice husk and coconut shell activated adsorbent to adsorb Pb (II) ion using SPS method. This research used experimental method. Technique to collecting this datas of this research is carried out by several stages, which are: (1) carbonization of rice husk and coconut shell adsorbent using muffle furnace at a temperature of 350°C for an hour; (2) activation of the rice husk and coconut shell adsorbent using NaOH 1N and ZnCl2 15% activator; (3) contacting the adsorbent of rice husk and coconut shell activated adsorbent with liquid waste simulation of Pb(II) using variation comparison of rice husk and coconut shell, 1:0; 0:1; 1:1; 2:1; 1:2; (4) analysis of Pb(II) using Solid-Phase Spectrophotometry (SPS); (5) characterization of combination rice husk and coconut shell activated adsorbent using FTIR. The result of this research show that the combined effect of combination rice husk and coconut shell activated adsorbent can increase the ability of the adsorbent to absorb Pb(II) ion then the optimum adsorbent mass ratio required for absorbing 20 mL of Pb(II) ion with a concentration of 49.99 µg/L is a ratio of 2:1 with the absorption level of 97,06%Solid-Phase Spectrophotometry (SPS) is an effective method in the level of µg/L, be marked with the Limit of Detection (LOD) of 0.03 µg/L.

  13. A three-color absorption/scattering imaging technique for simultaneous measurements on distributions of temperature and fuel concentration in a spray

    NASA Astrophysics Data System (ADS)

    Qi, Wenyuan; Zhang, Yuyin

    2018-04-01

    A three-color imaging technique was proposed for simultaneous measurements on distributions of fuel/air mixture temperature and fuel vapor/liquid concentrations in evaporating sprays. The idea is based on that the vapor concentration is proportional to the absorption of vapor to UV light, the liquid-phase concentration is related to the light extinction due to scattering of droplet to visible light, and the mixture temperature can be correlated to the absorbance ratio at two absorbing wavelengths or narrow bands. For verifying the imaging system, the molar absorption coefficients of p-xylene at the three narrow bands, which were centered respectively at 265, 289, and 532 nm with FWHM of 10 nm, were measured in a specially designed calibration chamber at different temperatures (423-606 K) and pressure of 3.6 bar. It was found that the ratio of the molar absorption coefficients of p-xylene at the two narrow bands centered at the two UV wavelengths is sensitive to the mixture temperature. On the other hand, the distributions of fuel vapor/liquid concentrations can be obtained by use of absorbance due to ultraviolet absorption of vapor and visible light scattering of droplets. Combining these two methods, a simultaneous measurement on distributions of mixture temperature and fuel vapor/liquid concentrations can be realized. In addition, the temperature field obtained from the ratio of the two absorbing narrow bands can be further used to improve the measurement accuracy of vapor/liquid concentrations, because the absorption coefficients depend on temperature. This diagnostic was applied to an evaporating spray inside a high-temperature and high-pressure constant volume chamber.

  14. Triple-Pulse Integrated Path Differential Absorption Lidar for Carbon Dioxide Measurement - Novel Lidar Technologies and Techniques with Path to Space

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Refaat, Tamer F.; Petros, Mulugeta

    2017-01-01

    The societal benefits of understanding climate change through identification of global carbon dioxide sources and sinks led to the desired NASA's active sensing of carbon dioxide emissions over nights, days, and seasons (ASCENDS) space-based missions of global carbon dioxide measurements. For more than 15 years, NASA Langley Research Center (LaRC) have developed several carbon dioxide active remote sensors using the differential absorption lidar (DIAL) technique operating at the two-micron wavelength. Currently, an airborne two-micron triple-pulse integrated path differential absorption (IPDA) lidar is under development. This IPDA lidar measures carbon dioxide as well as water vapor, the dominant interfering molecule on carbon dioxide remote sensing. Advancement of this triple-pulse IPDA lidar development is presented.

  15. All-optical laser spectral narrowing and line fixing at atomic absorption transition by injection competition and gain knock-down techniques

    NASA Astrophysics Data System (ADS)

    Gacheva, Lazarina I.; Deneva, Margarita A.; Kalbanov, Mihail H.; Nenchev, Marin N.

    2008-12-01

    We present two original, all optical techniques, to produce a narrowline laser light, fixed at the frequency of a chosen reference atomic absorption transition. The first type of systems is an essential improvement of our method 3,4 for laser spectral locking using a control by two frequency scanned, competitive injections with disturbed power ratio by the absorption at the reference line. The new development eliminates the narrowing limiting problem, related with the fixed laser longitudinal mode structure. We have proposed an original new technique for continuously tunable single mode laser operation in combination with synchronously and equal continuous tuning of the modes of the amplifier. By adapting the laser differential rate equations, the system is analyzed theoretically in details and is shown its feasibility. The results are in agreement with previous our experiments. The essential advantage, except simplicity of realization, is that the laser line can be of order of magnitude and more narrowed than the absorption linewidth. The second system is based of the laser amplifier arrangement with a gain knock-down from the competitive frequency scanned pulse, except at the wavelength of the desired absorption reference line. The essential advantages of the last system are that the problem of fixing laser mode presence is naturally avoided. The theoretical modeling and the numerical investigations show the peculiarity and advantages of the system proposed. The developed approaches are of interest for applications in spectroscopy, in DIAL monitoring of the atmospheric pollutants, in isotope separation system and potentially - for creation of simple, all optical, frequency standards for optical communications. Also, the continuously tunable single mode laser (and the combination with the simultaneously tunable amplifier) presents itself the interest for many practical applications in spectroscopy, metrology, and holography. We compare the action and the

  16. Development of the surface-sensitive soft x-ray absorption fine structure measurement technique for the bulk insulator

    SciTech Connect

    Yonemura, Takumi, E-mail: yonemura-takumi@sei.co.jp; Iihara, Junji; Uemura, Shigeaki

    We have succeeded in measuring X-ray absorption fine structure (TEY-XAFS) spectra of insulating plate samples by total electron yield. The biggest problem is how to suppress the charge-up. We have attempted to deposit a gold stripe electrode on the surface and obtained a TEY-XAFS spectrum. This indicates that the metal stripe electrode is very useful in the TEY-XAFS measurement of the insulating plate samples. In the detailed analysis, we have found that the effective area for suppressing charge-up was approximately 120 μm from the edge of the electrode.

  17. Measurement of polarization dependence of two-photon absorption coefficient in InP using extended Z-scan technique for thick materials

    NASA Astrophysics Data System (ADS)

    Oishi, Masaki; Shinozaki, Tomohisa; Hara, Hikaru; Yamamoto, Kazunuki; Matsusue, Toshio; Bando, Hiroyuki

    2018-03-01

    The two-photon absorption coefficient β in InP has been measured in the wavelength range of 1640 to 1800 nm by the Z-scan technique in relatively thick materials. The values of β have been evaluated from the fit to the equation including the spatial and temporal profiles of the focused Gaussian beam. The polarization dependence of β has also been measured. The dependence has been expressed very well by the expression of β with the imaginary part of the third-order nonlinear susceptibility tensor χ(3).

  18. A structural study of bone changes in knee osteoarthritis by synchrotron-based X-ray fluorescence and X-ray absorption spectroscopy techniques

    NASA Astrophysics Data System (ADS)

    Sindhupakorn, Bura; Thienpratharn, Suwittaya; Kidkhunthod, Pinit

    2017-10-01

    Osteoarthritis (OA) is characterized by degeneration of articular cartilage and thickening of subchondral bone. The present study investigated the changing of biochemical components of cartilage and bone compared between normal and OA people. Using Synchrotron-based X-ray fluorescence (SR-XRF) and X-ray absorption spectroscopy (XAS) techniquesincluding X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) were employed for the bone changes in kneeosteoarthritisstudies. The bone samples were collected from various osteoarthritis patients with both male and female in the ages range between 20 and 74 years old. SR-XRF results excited at 4240 eV for Ca elements show a majority three main groups, based on their XRF intensities, 20-36 years, 40-60 years and over 70 years, respectively. By employing XAS techniques, XANES features can be used to clearly explain in term of electronic transitions occurring in bone samples which are affected from osteoarthritis symptoms. Moreover, a structural change around Ca ions in bone samples is obviously obtained by EXAFS results indicating an increase of Ca-amorphous phase when the ages increase.

  19. Investigation of the effect of solubility increase at the main absorption site on bioavailability of BCS class II drug (risperidone) using liquisolid technique.

    PubMed

    Khames, Ahmed

    2017-11-01

    BCS class II drugs usually suffer inadequate bioavailability as dissolution step is the absorption rate limiting step. In this work, the effect of solubility increase at the main absorption site for these drugs was investigated using risperidone as a drug model. Liquisolid technique was applied to prepare risperidone per-oral tablets of high dissolution rate at intestinal pH (6.8) using versatile nonionic surfactants of high solubilizing ability [Transcutol HP, Labrasol and Labrasol/Labrafil (1:1) mixture] as liquid vehicles at different drug concentrations (10-30%) and fixed (R). The prepared liquisolid tablets were fully evaluated and the dissolution rate at pH 6.8 was investigated. The formulae that showed significantly different release rate were selected and subjected to mathematical modeling using DE 25 , MDT and similarity factor (f2). Depending on mathematical modeling results, formula of higher dissolution rate was subjected to solid state characterization using differential scanning calorimetric (DSC), infrared spectroscopy (IR) and X-ray diffraction (XRD). Finally, the drug bioavailability was studied in comparison to conventional tablets in rabbits. Results showed that liquisolid tablet prepared using Labrasol/Labrafil (1:1) mixture as liquid vehicle containing 10% risperidone is a compatible formula with law drug crystallinity and higher dissolution rate (100% in 25 min). The drug bioavailability was significantly increased in comparison to the conventional tablets (1441.711 μg h/mL and 137.518 μg/mL in comparison to 321.011 μg h/mL and 38.673 μg/mL for AUC and Cp max , respectively). This led to the conclusion that liquisolid technique was efficiently improved drug solubility and solubility increase of BCS class II drugs at their main absorption site significantly increases their bioavailability.

  20. An Improved Computational Technique for Calculating Electromagnetic Forces and Power Absorptions Generated in Spherical and Deformed Body in Levitation Melting Devices

    NASA Technical Reports Server (NTRS)

    Zong, Jin-Ho; Szekely, Julian; Schwartz, Elliot

    1992-01-01

    An improved computational technique for calculating the electromagnetic force field, the power absorption and the deformation of an electromagnetically levitated metal sample is described. The technique is based on the volume integral method, but represents a substantial refinement; the coordinate transformation employed allows the efficient treatment of a broad class of rotationally symmetrical bodies. Computed results are presented to represent the behavior of levitation melted metal samples in a multi-coil, multi-frequency levitation unit to be used in microgravity experiments. The theoretical predictions are compared with both analytical solutions and with the results or previous computational efforts for the spherical samples and the agreement has been very good. The treatment of problems involving deformed surfaces and actually predicting the deformed shape of the specimens breaks new ground and should be the major usefulness of the proposed method.

  1. 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.

  2. Signal-to-noise enhancement techniques for quantum cascade absorption spectrometers employing optimal filtering and other approaches

    NASA Astrophysics Data System (ADS)

    Disselkamp, R. S.; Kelly, J. F.; Sams, R. L.; Anderson, G. A.

    Optical feedback to the laser source in tunable diode laser spectroscopy (TDLS) is known to create intensity modulation noise due to elatoning and optical feedback (i.e. multiplicative technical noise) that usually limits spectral signal-to-noise (S/N). The large technical noise often limits absorption spectroscopy to noise floors 100-fold greater than the Poisson shot noise limit due to fluctuations in the laser intensity. The high output powers generated from quantum cascade (QC) lasers, along with their high gain, makes these injection laser systems especially susceptible to technical noise. In this article we discuss a method of using optimal filtering to reduce technical noise. We have observed S/N enhancements ranging from 20% to a factor of 50. The degree to which optimal filtering enhances S/N depends on the similarity between the Fourier components of the technical noise and those of the signal, with lower S/N enhancements observed for more similar Fourier decompositions of the signal and technical noise. We also examine the linearity of optimal filtered spectra in both time and intensity. This was accomplished by creating a synthetic spectrum for the species being studied (CH4, N2O, CO2 and H2O in ambient air) utilizing line positions and linewidths with an assumed Voigt profile from a commercial database (HITRAN). Agreement better than 0.036% in wavenumber and 1.64% in intensity (up to a 260-fold intensity ratio employed) was observed. Our results suggest that rapid ex post facto digital optimal filtering can be used to enhance S/N for routine trace gas detection.

  3. [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.

  4. 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Multi-filter spectrophotometry of quasar environments

    NASA Technical Reports Server (NTRS)

    Craven, Sally E.; Hickson, Paul; Yee, Howard K. C.

    1993-01-01

    A many-filter photometric technique for determining redshifts and morphological types, by fitting spectral templates to spectral energy distributions, has good potential for application in surveys. Despite success in studies performed on simulated data, the results have not been fully reliable when applied to real, low signal-to-noise data. We are investigating techniques to improve the fitting process.

  6. 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)

  7. 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)

  8. The determination of copper in biological materials by flame spectrophotometry

    PubMed Central

    Newman, G. E.; Ryan, M.

    1962-01-01

    A method for the determination of the copper content of biological materials by flame spectrophotometry is described. The effects of interference by ions such as sodium and phosphate were eliminated by isolating copper as the dithizonate in CCl4. Results obtained for the urinary excretion of copper by a patient with Wilson's disease before and after treatment with penicillamine are reported. PMID:14479334

  9. 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…

  10. Column carbon dioxide and water vapor measurements by an airborne triple-pulse integrated path differential absorption lidar: novel lidar technologies and techniques with path to space

    NASA Astrophysics Data System (ADS)

    Singh, U. N.; Petros, M.; Refaat, T. F.; Yu, J.; Ismail, S.

    2017-09-01

    The 2-micron wavelength region is suitable for atmospheric carbon dioxide (CO2) measurements due to the existence of distinct absorption features for the gas at this wavelength region [1]. For more than 20 years, researchers at NASA Langley Research Center (LaRC) have developed several high-energy and high repetition rate 2-micron pulsed lasers [2]. Currently, LaRC team is engaged in designing, developing and demonstrating a triple-pulsed 2-micron direct detection Integrated Path Differential Absorption (IPDA) lidar to measure the weighted-average column dry-air mixing ratios of carbon dioxide (XCO2) and water vapor (XH2O) from an airborne platform [1, 3-5]. This novel technique allows measurement of the two most dominant greenhouse gases, simultaneously and independently, using a single instrument. This paper will provide status and details of the development of this airborne 2-micron triple-pulse IPDA lidar. The presented work will focus on the advancement of critical IPDA lidar components. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver and detector upgrades, laser packaging and lidar integration. Future plans for IPDA lidar ground integration, testing and flight validation will also be discussed. This work enables new Earth observation measurements, while reducing risk, cost, size, volume, mass and development time of required instruments.

  11. Determination of wood burning and fossil fuel contribution of black carbon at Delhi, India using aerosol light absorption technique.

    PubMed

    Tiwari, S; Pipal, A S; Srivastava, A K; Bisht, D S; Pandithurai, G

    2015-02-01

    A comprehensive measurement program of effective black carbon (eBC), fine particle (PM2.5), and carbon monoxide (CO) was undertaken during 1 December 2011 to 31 March 2012 (winter period) in Delhi, India. The mean mass concentrations of eBC, PM2.5, and CO were recorded as 12.1 ± 8.7 μg/m(3), 182.75 ± 114.5 μg/m(3), and 3.41 ± 1.6 ppm, respectively, during the study period. Also, the absorption Angstrom exponent (AAE) was estimated from eBC and varied from 0.38 to 1.29 with a mean value of 1.09 ± 0.11. The frequency of occurrence of AAE was ~17 % less than unity whereas ~83 % greater than unity was observed during the winter period in Delhi. The mass concentrations of eBC were found to be higher by ~34 % of the average value of eBC (12.1 μg/m(3)) during the study period. Sources of eBC were estimated, and they were ~94 % from fossil fuel (eBCff) combustion whereas only 6 % was from wood burning (eBCwb). The ratio between eBCff and eBCwb was 15, which indicates a higher impact from fossil fuels compared to biomass burning. When comparing eBCff during day and night, a factor of three higher concentrations was observed in nighttime than daytime, and it is due to combustion of fossil fuel (diesel vehicle emission) and shallow boundary layer conditions. The contribution of eBCwb in eBC was higher between 1800 and 2100 hours due to burning of wood/biomass. A significant correlation between eBC and PM2.5 (r = 0.78) and eBC and CO (r = 0.46) indicates the similarity in location sources. The mass concentration of eBC was highest (23.4 μg/m(3)) during the month of December when the mean visibility (VIS) was lowest (1.31 km). Regression analysis among wind speed (WS), VIS, soot particles, and CO was studied, and significant negative relationships were seen between VIS and eBC (-0.65), eBCff (-0.66), eBCwb (-0.34), and CO (-0.65); however, between WS and eBC (-0.68), eBCff (-0.67), eBCwb (-0.28), and CO (-0.53). The regression analysis indicated

  12. Thermal expansion behavior study of Co nanowire array with in situ x-ray diffraction and x-ray absorption fine structure techniques

    NASA Astrophysics Data System (ADS)

    Mo, Guang; Cai, Quan; Jiang, Longsheng; Wang, Wei; Zhang, Kunhao; Cheng, Weidong; Xing, Xueqing; Chen, Zhongjun; Wu, Zhonghua

    2008-10-01

    In situ x-ray diffraction and x-ray absorption fine structure techniques were used to study the structural change of ordered Co nanowire array with temperature. The results show that the Co nanowires are polycrystalline with hexagonal close packed structure without phase change up until 700 °C. A nonlinear thermal expansion behavior has been found and can be well described by a quadratic equation with the first-order thermal expansion coefficient of 4.3×10-6/°C and the second-order thermal expansion coefficient of 5.9×10-9/°C. The mechanism of this nonlinear thermal expansion behavior is discussed.

  13. Molecular basis of structural make-up of feeds in relation to nutrient absorption in ruminants, revealed with advanced molecular spectroscopy: A review on techniques and models

    SciTech Connect

    Rahman, Md. Mostafizar; Yu, Peiqiang

    Progress in ruminant feed research is no more feasible only based on wet chemical analysis, which is merely able to provide information on chemical composition of feeds regardless of their digestive features and nutritive value in ruminants. Studying internal structural make-up of functional groups/feed nutrients is often vital for understanding the digestive behaviors and nutritive values of feeds in ruminant because the intrinsic structure of feed nutrients is more related to its overall absorption. In this article, the detail information on the recent developments in molecular spectroscopic techniques to reveal microstructural information of feed nutrients and the use of nutritionmore » models in regards to ruminant feed research was reviewed. The emphasis of this review was on (1) the technological progress in the use of molecular spectroscopic techniques in ruminant feed research; (2) revealing spectral analysis of functional groups of biomolecules/feed nutrients; (3) the use of advanced nutrition models for better prediction of nutrient availability in ruminant systems; and (4) the application of these molecular techniques and combination of nutrient models in cereals, co-products and pulse crop research. The information described in this article will promote better insight in the progress of research on molecular structural make-up of feed nutrients in ruminants.« less

  14. 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.

  15. Spectrophotometry of cerebrospinal fluid in subacute and chronic subdural haematomas

    PubMed Central

    Kjellin, K. G.; Steiner, L.

    1974-01-01

    Spectrophotometric examinations were performed on cerebrospinal and subdural fluids in subacute (five patients) and chronic (20 patients) subdural haematomas, with special reference to the diagnostic aid of CSF spectrophotometry. Spectrophotometric xanthochromia of haemorrhagic origin was found in all CSFs examined, while definite visible xanthochromia was observed in only 28% and the CSF was judged as colourless in 52% of those cases. Characteristic bleeding patterns were found spectrophotometrically in all the 20 CSFs examined within 24 hours after lumbar puncture, haematoma patterns being detected in 90-95% of the cases. In many cases the electrophoretically separated protein fractions of CSF and subdural fluids were spectrophotometrically examined. In conclusion, CSF spectrophotometry is a simple, fast, and extremely sensitive method, which in our opinion should be used routinely in the diagnosis of suspected subdural haematomas, if lumbar puncture is not contraindicated. PMID:4140892

  16. Visual inspection versus spectrophotometry in detecting bilirubin in cerebrospinal fluid

    PubMed Central

    Linn, F; Voorbij, H; Rinkel, G; Algra, A; van Gijn, J

    2005-01-01

    Methods: Clinicians and students assessed CSF specimens with seven degrees of extinction between 0.00 and 0.09 at 450–460 nm as "yellow," "doubtful," or "colourless" after random presentation under standard conditions. The assessments were compared with spectrophotometry, with 0.05 being taken as the cut off level for the presence of bilirubin. Results were compared between the two groups and explored by means of receiver operating characteristic (ROC) curves. Results: All 51 clinicians and 50 of 51 students scored the tubes with extinction of 0.06 or higher as "yellow" or "doubtful." Tubes without any bilirubin were scored as "yellow" by three of the students only. The ROC curves confirmed that the diagnostic properties of the visual inspection versus spectrophotometry were slightly better for the clinicians than for the students. Conclusions: If CSF is considered colourless, the extinction of bilirubin is too low to be compatible with a diagnosis of recent subarachnoid haemorrhage. If CSF is not considered colourless, spectrophotometry should be carried out to determine the level of extinction of bilirubin. PMID:16170095

  17. Non-grey dimming events of KIC 8462852 from GTC spectrophotometry

    NASA Astrophysics Data System (ADS)

    Deeg, Hans J.; Alonso, Roi; Nespral, David; Boyajian, Tabetha S.

    2018-02-01

    We report ground-based spectrophotometry of KIC 8462852 obtained during its first dimming events since the end of the Kepler mission. The dimmings show a clear colour signature and are deeper in visual blue than in red wavelengths. The wavelength dependency of the flux loss can be described with an absorption Ångström coefficient of 2.19 ± 0.45, which is compatible with absorption by optically thin dust with particle sizes of the order of 0.0015 to 0.15 μm. These particles would be smaller than is required to be resistant against blow-out by radiation pressure when close to the star. During occultation events, these particles must be replenished from a comoving body on time-scales of days. If dust is indeed the source of the dimming events of KIC 8462852, deeper dimming events should show more neutral colours, as is expected from optically thick absorbers. The individual reduced spectra of the target and reference stars are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/610/L12

  18. Interaction between Eu(III) and graphene oxide nanosheets investigated by batch and extended X-ray absorption fine structure spectroscopy and by modeling techniques.

    PubMed

    Sun, Yubing; Wang, Qi; Chen, Changlun; Tan, Xiaoli; Wang, Xiangke

    2012-06-05

    The interaction mechanism between Eu(III) and graphene oxide nanosheets (GONS) was investigated by batch and extended X-ray absorption fine structure (EXAFS) spectroscopy and by modeling techniques. The effects of pH, ionic strength, and temperature on Eu(III) adsorption on GONS were evaluated. The results indicated that ionic strength had no effect on Eu(III) adsorption on GONS. The maximum adsorption capacity of Eu(III) on GONS at pH 6.0 and T = 298 K was calculated to be 175.44 mg·g(-1), much higher than any currently reported. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggested that Eu(III) adsorption on GONS was an endothermic and spontaneous process. Results of EXAFS spectral analysis indicated that Eu(III) was bound to ∼6-7 O atoms at a bond distance of ∼2.44 Å in the first coordination shell. The value of Eu-C bond distance confirmed the formation of inner-sphere surface complexes on GONS. Surface complexation modeling gave an excellent fit with the predominant mononuclear monodentate >SOEu(2+) and binuclear bidentate (>SO)(2)Eu(2)(OH)(2)(2+) complexes. This paper highlights the application of GONS as a suitable material for the preconcentration and removal of trivalent lanthanides and actinides from aqueous solutions in environmental pollution management.

  19. An automated flow injection system for metal determination by flame atomic absorption spectrometry involving on-line fabric disk sorptive extraction technique.

    PubMed

    Anthemidis, A; Kazantzi, V; Samanidou, V; Kabir, A; Furton, K G

    2016-08-15

    A novel flow injection-fabric disk sorptive extraction (FI-FDSE) system was developed for automated determination of trace metals. The platform was based on a minicolumn packed with sol-gel coated fabric media in the form of disks, incorporated into an on-line solid-phase extraction system, coupled with flame atomic absorption spectrometry (FAAS). This configuration provides minor backpressure, resulting in high loading flow rates and shorter analytical cycles. The potentials of this technique were demonstrated for trace lead and cadmium determination in environmental water samples. The applicability of different sol-gel coated FPSE media was investigated. The on-line formed complex of metal with ammonium pyrrolidine dithiocarbamate (APDC) was retained onto the fabric surface and methyl isobutyl ketone (MIBK) was used to elute the analytes prior to atomization. For 90s preconcentration time, enrichment factors of 140 and 38 and detection limits (3σ) of 1.8 and 0.4μgL(-1) were achieved for lead and cadmium determination, respectively, with a sampling frequency of 30h(-1). The accuracy of the proposed method was estimated by analyzing standard reference materials and spiked water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Quantifying uncertainty in measurement of mercury in suspended particulate matter by cold vapor technique using atomic absorption spectrometry with hydride generator.

    PubMed

    Singh, Nahar; Ahuja, Tarushee; Ojha, Vijay Narain; Soni, Daya; Tripathy, S Swarupa; Leito, Ivo

    2013-01-01

    As a result of rapid industrialization several chemical forms of organic and inorganic mercury are constantly introduced to the environment and affect humans and animals directly. All forms of mercury have toxic effects; therefore accurate measurement of mercury is of prime importance especially in suspended particulate matter (SPM) collected through high volume sampler (HVS). In the quantification of mercury in SPM samples several steps are involved from sampling to final result. The quality, reliability and confidence level of the analyzed data depends upon the measurement uncertainty of the whole process. Evaluation of measurement uncertainty of results is one of the requirements of the standard ISO/IEC 17025:2005 (European Standard EN IS/ISO/IEC 17025:2005, issue1:1-28, 2006). In the presented study the uncertainty estimation in mercury determination in suspended particulate matter (SPM) has been carried out using cold vapor Atomic Absorption Spectrometer-Hydride Generator (AAS-HG) technique followed by wet chemical digestion process. For the calculation of uncertainty, we have considered many general potential sources of uncertainty. After the analysis of data of seven diverse sites of Delhi, it has been concluded that the mercury concentration varies from 1.59 ± 0.37 to 14.5 ± 2.9 ng/m(3) with 95% confidence level (k = 2).

  1. 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.

  2. On the sub-band gap optical absorption in heat treated cadmium sulphide thin film deposited on glass by chemical bath deposition technique

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, P.; Karim, B.; Guha Roy, S.

    2013-12-01

    The sub-band gap optical absorption in chemical bath deposited cadmium sulphide thin films annealed at different temperatures has been critically analyzed with special reference to Urbach relation. It has been found that the absorption co-efficient of the material in the sub-band gap region is nearly constant up to a certain critical value of the photon energy. However, as the photon energy exceeds the critical value, the absorption coefficient increases exponentially indicating the dominance of Urbach rule. The absorption coefficients in the constant absorption region and the Urbach region have been found to be sensitive to annealing temperature. A critical examination of the temperature dependence of the absorption coefficient indicates two different kinds of optical transitions to be operative in the sub-band gap region. After a careful analyses of SEM images, energy dispersive x-ray spectra, and the dc current-voltage characteristics, we conclude that the absorption spectra in the sub-band gap domain is possibly associated with optical transition processes involving deep levels and the grain boundary states of the material.

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

    PubMed

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

    2011-02-11

    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.

  4. Infrared Absorption of Methanol-Water Clusters Mn(H2O), n = 1-4, Recorded with the Vuv-Ionization Techniques

    NASA Astrophysics Data System (ADS)

    Lee, Yu-Fang; Lee, Yuan-Pern

    2016-06-01

    We investigated IR spectra in the CH- and OH-stretching regions of size-selected methanol-water clusters, Mn(H_2O) with M representing CH_3OH and n = 1-4, in a pulsed supersonic jet by using the VUV (vacuum-ultraviolet)-ionization/IR-depletion technique. The VUV light at 118 nm served as the source of ionization in a time-of-flight mass spectrometer. The tunable IR laser served as a source of dissociation for clusters before ionization. Spectra of methanol-water clusters in the OH region show significant variations as the number of methanol molecules increase, whereas spectra in the CH region are similar. For M(H_2O), absorption of a structure with H_2O as a proton donor was observed at 3570, 3682, and 3722 wn, whereas that of methanol as a proton donor was observed at 3611 and 3753 wn. For M2(H_2O), the OH-stretching band of the dangling OH of H_2O was observed at 3721 wn, whereas overlapped bands near 3425, 3472, and 3536 wn correspond to the OH-stretching modes of three hydrogen-bonded OH in a cyclic structure. For M3(H_2O), the dangling OH shifts to 3715 wn, and the hydrogen-bonded OH-stretching bands become much broader, with a band near 3179 wn having the smallest wavenumber. Scaled harmonic vibrational wavenumbers and relative IR intensities predicted for the methanol-water clusters with the M06-2X/aug-cc-pVTZ method are consistent with our experimental results. For M4(H_2O), observed spectrum agree less with theoretical predictions, indicating the presence of isomers other than the most stable cyclic one. Spectra of Mn(H_2O) and Mn+1 are compared and the cooperative hydrogen-bonding is discussed.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. The reaction of fully reduced cytochrome c oxidase with oxygen studied by flow-flash spectrophotometry at room temperature. Evidence for new pathways of electron transfer.

    PubMed Central

    Hill, B C; Greenwood, C

    1984-01-01

    Absorption changes during the O2 reaction of reduced bovine cytochrome c oxidase were investigated by the rapid-reaction technique of flow-flash spectrophotometry in the Soret, visible and near-i.r. spectral regions. New features in the time courses of absorption change were observed relative to the earlier findings reported by Greenwood & Gibson [(1967) J. Biol. Chem. 242, 1782-1787]. These new features arise in the Soret and near-i.r. regions and allow the reaction to be described at all wavelengths as a composite of three exponential processes. There is a rapid O2-sensitive phase detectable in the Soret and visible region. The second phase has a rate that is somewhat less dependent on O2 concentration than is the fastest phase rate and is detectable in all three spectral regions. The rate of the third phase is almost independent of the O2 concentration and is also detectable in all spectral regions. Analysis of the three phases gives their rates and absorption amplitudes. The fast phase reaches a rate of 2.5 X 10(4) s-1 at the highest O2 concentration available at 20 degrees C, whereas the phase of intermediate rate is limited at a value of 7 X 10(3) s-1 and the slow phase rate is limited at 700 s-1. The ratios of the kinetic difference spectra for the fast phase and the slow phase do not correspond to the spectra of the individual haem centres. A branched mechanism is advanced that is able to reconcile the kinetic and static difference spectra. This mechanism suggests that some of the cytochrome a is oxidized along with cytochrome a3 in the initial O2-sensitive phase. In addition, the model requires that CuA is oxidized heterogeneously. This fits with the complex time course of oxidation observed at 830 nm while retaining CuA as virtually the sole contributor to absorbance at this wavelength. PMID:6326750

  10. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. 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.

  12. 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.

  13. Infrared absorption of methanol-water clusters (CH3OH)n(H2O), n = 1-4, recorded with the VUV-ionization/IR-depletion technique

    NASA Astrophysics Data System (ADS)

    Lee, Yu-Fang; Kelterer, Anne-Marie; Matisz, Gergely; Kunsági-Máté, Sándor; Chung, Chao-Yu; Lee, Yuan-Pern

    2017-04-01

    We recorded infrared (IR) spectra in the CH- and OH-stretching regions of size-selected clusters of methanol (M) with one water molecule (W), represented as MnW, n = 1-4, in a pulsed supersonic jet using the photoionization/IR-depletion technique. Vacuum ultraviolet emission at 118 nm served as the source of ionization in a time-of-flight mass spectrometer to detect clusters MnW as protonated forms Mn-1WH+. The variations in intensities of Mn-1WH+ were monitored as the wavelength of the IR laser light was tuned across the range 2700-3800 cm-1. IR spectra of size-selected clusters were obtained on processing of the observed action spectra of the related cluster-ions according to a mechanism that takes into account the production and loss of each cluster due to IR photodissociation. Spectra of methanol-water clusters in the OH region show significant variations as the number of methanol molecules increases, whereas those in the CH region are similar for all clusters. Scaled harmonic vibrational wavenumbers and relative IR intensities predicted with the M06-2X/aug-cc-pVTZ method for the methanol-water clusters are consistent with our experimental results. For dimers, absorption bands of a structure WM with H2O as a hydrogen-bond donor were observed at 3570, 3682, and 3722 cm-1, whereas weak bands of MW with methanol as a hydrogen-bond donor were observed at 3611 and 3753 cm-1. For M2W, the free OH band of H2O was observed at 3721 cm-1, whereas a broad feature was deconvoluted to three bands near 3425, 3472, and 3536 cm-1, corresponding to the three hydrogen-bonded OH-stretching modes in a cyclic structure. For M3W, the free OH shifted to 3715 cm-1, and the hydrogen-bonded OH-stretching bands became much broader, with a weak feature near 3179 cm-1 corresponding to the symmetric OH-stretching mode of a cyclic structure. For M4W, the observed spectrum agrees unsatisfactorily with predictions for the most stable cyclic structure, indicating significant contributions from

  14. Infrared absorption of methanol-water clusters (CH3OH)n(H2O), n = 1-4, recorded with the VUV-ionization/IR-depletion technique.

    PubMed

    Lee, Yu-Fang; Kelterer, Anne-Marie; Matisz, Gergely; Kunsági-Máté, Sándor; Chung, Chao-Yu; Lee, Yuan-Pern

    2017-04-14

    We recorded infrared (IR) spectra in the CH- and OH-stretching regions of size-selected clusters of methanol (M) with one water molecule (W), represented as M n W, n = 1-4, in a pulsed supersonic jet using the photoionization/IR-depletion technique. Vacuum ultraviolet emission at 118 nm served as the source of ionization in a time-of-flight mass spectrometer to detect clusters M n W as protonated forms M n-1 WH + . The variations in intensities of M n-1 WH + were monitored as the wavelength of the IR laser light was tuned across the range 2700-3800 cm -1 . IR spectra of size-selected clusters were obtained on processing of the observed action spectra of the related cluster-ions according to a mechanism that takes into account the production and loss of each cluster due to IR photodissociation. Spectra of methanol-water clusters in the OH region show significant variations as the number of methanol molecules increases, whereas those in the CH region are similar for all clusters. Scaled harmonic vibrational wavenumbers and relative IR intensities predicted with the M06-2X/aug-cc-pVTZ method for the methanol-water clusters are consistent with our experimental results. For dimers, absorption bands of a structure WM with H 2 O as a hydrogen-bond donor were observed at 3570, 3682, and 3722 cm -1 , whereas weak bands of MW with methanol as a hydrogen-bond donor were observed at 3611 and 3753 cm -1 . For M 2 W, the free OH band of H 2 O was observed at 3721 cm -1 , whereas a broad feature was deconvoluted to three bands near 3425, 3472, and 3536 cm -1 , corresponding to the three hydrogen-bonded OH-stretching modes in a cyclic structure. For M 3 W, the free OH shifted to 3715 cm -1 , and the hydrogen-bonded OH-stretching bands became much broader, with a weak feature near 3179 cm -1 corresponding to the symmetric OH-stretching mode of a cyclic structure. For M 4 W, the observed spectrum agrees unsatisfactorily with predictions for the most stable cyclic structure

  15. 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%.

  16. Systematic approach for describing the geometry of spectrophotometry

    NASA Astrophysics Data System (ADS)

    Early, Edward A.

    2003-07-01

    In the field of spectrophotometry, the value of the quantities depends upon the geometry under which they are measured. Therefore, it is imperative to completely describe the measurement geometry. Many documentary standards specify the geometry for a particular application. However, to accurately specify the geometry, a general, basic understanding of the relevant parameters for describing the geometry is required. A systematic approach for describing the measurement geometry is presented, which will hopefully have a positive impact on documentary standards. The key to describing the geometry is to consider the illuminator and receiver of the instrument as optical systems with pupils and windows. It is these optical systems, together with the reference plane, that determine the sampling aperture of the instrument. The geometry is then completely described by the relations between the sampling aperture and the optical systems of the illuminator and receiver. These concepts are illustrated by considering three configurations of pupils and windows relative to the focal point of an optical system.

  17. 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.

  18. 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.

  19. 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. Copyright © 2013 Elsevier Inc. All rights reserved.

  20. On-line photolithography modeling using spectrophotometry and Prolith/2

    NASA Astrophysics Data System (ADS)

    Engstrom, Herbert L.; Beacham, Jeanne E.

    1994-05-01

    Spectrophotometry has been applied to optimizing photolithography processes in semiconductor manufacturing. For many years thin film measurement systems have been used in manufacturing for controlling film deposition processes. The combination of film thickness mapping with photolithography modeling has expanded the applications of this technology. Experimental measurements of dose-to-clear, the minimum light exposure dose required to fully develop a photoresist, are described. It is shown how dose-to-clear and photoresist contrast may be determined rapidly and conveniently from measurements of a dose exposure matrix on a monitor wafer. Such experimental measurements may underestimate the dose-to- clear because of thickness variations of the photoresist and underlying layers on the product wafer. Online modeling of the photolithographic process together with film thickness maps of the entire wafer can overcome this problem. Such modeling also provides maps of dose-to- clear and resist linewidth that can be used to estimate and optimize yield.

  1. HPLC determination of flavonoid glycosides in Mongolian Dianthus versicolor Fisch. (Caryophyllaceae) compared with quantification by UV spectrophotometry.

    PubMed

    Obmann, Astrid; Purevsuren, Sodnomtseren; Zehl, Martin; Kletter, Christa; Reznicek, Gottfried; Narantuya, Samdan; Glasl, Sabine

    2012-01-01

    Dianthus versicolor is used in traditional Mongolian medicine against liver impairment. Fractions enriched in flavone-di- and triglycosides were shown to enhance bile secretion. Therefore, reliable and accurate analytical methods are needed for the determination of these flavonoids in the crude drug and extracts thereof. To provide a validated HPLC-DAD (diode array detector) method especially developed for the separation of polar flavonoids and to compare the data obtained with those evaluated by UV spectrophotometry. Separations were carried out on an Aquasil® C₁₈-column (4.6 mm × 250.0 mm, 5 µm) with a linear gradient of acetonitrile and water (adjusted to pH 2.8 with trifluoroacetic acid) as mobile phase. Rutoside was employed as internal standard with linear behavior in a concentration range of 0.007-3.5 mg/mL. Accuracy was determined by spiking the crude drug with saponarin resulting in recoveries between 92% and 102%. The method allows the quantification of highly polar flavonoid glycosides and the determination of their total content. For saponarin a linear response was evaluated within the range 0.007-3.5 mg/mL (R²  > 0.9999). It was proven that threefold sonication represents a time-saving, effective and cheap method for the extraction of the polar flavonoid glycosides. The contents determined by HPLC were shown to be in agreement with those obtained employing UV spectrophotometry. The study has indicated that the newly developed HPLC method represents a powerful technique for the quality control of D. versicolor. Ultraviolet spectrophotometry may be used alternatively provided that the less polar flavonoids are removed by purification. Copyright © 2011 John Wiley & Sons, Ltd.

  2. Non-Heme Iron Absorption and Utilization from Typical Whole Chinese Diets in Young Chinese Urban Men Measured by a Double-Labeled Stable Isotope Technique

    PubMed Central

    Yang, Lichen; Zhang, Yuhui; Wang, Jun; Huang, Zhengwu; Gou, Lingyan; Wang, Zhilin; Ren, Tongxiang; Piao, Jianhua; Yang, Xiaoguang

    2016-01-01

    Background This study was to observe the non-heme iron absorption and biological utilization from typical whole Chinese diets in young Chinese healthy urban men, and to observe if the iron absorption and utilization could be affected by the staple food patterns of Southern and Northern China. Materials and Methods Twenty-two young urban men aged 18–24 years were recruited and randomly assigned to two groups in which the staple food was rice and steamed buns, respectively. Each subject received 3 meals containing approximately 3.25 mg stable 57FeSO4 (the ratio of 57Fe content in breakfast, lunch and dinner was 1:2:2) daily for 2 consecutive days. In addition, approximately 2.4 mg 58FeSO4 was administered intravenously to each subject at 30–60 min after dinner each day. Blood samples were collected from each subject to measure the enrichment of the 57Fe and 58Fe. Fourteen days after the experimental diet, non-heme iron absorption was assessed by measuring 57Fe incorporation into red blood cells, and absorbed iron utilization was determined according to the red blood cell incorporation of intravenously infused 58Fe SO4. Results Non-heme iron intake values overall, and in the rice and steamed buns groups were 12.8 ±2.1, 11.3±1.3 and 14.3±1.5 mg, respectively; the mean 57Fe absorption rates were 11±7%, 13±7%, and 8±4%, respectively; and the mean infused 58Fe utilization rates were 85±8%, 84±6%, and 85±10%, respectively. There was no significantly difference in the iron intakes, and 57Fe absorption and infused 58Fe utilization rates between rice and steamed buns groups (all P>0.05). Conclusion We present the non-heme iron absorption and utilization rates from typical whole Chinese diets among young Chinese healthy urban men, which was not affected by the representative staple food patterns of Southern and Northern China. This study will provide a basis for the setting of Chinese iron DRIs. PMID:27099954

  3. Determination of piroxicam in pharmaceutical preparations by ultraviolet direct spectrophotometry, ultraviolet difference spectrophotometry and high performance liquid chromatography

    SciTech Connect

    Hackmann, E.R.M.; Santos Gianotto, E.A. dos; Miritello Santoro, M.I.R.

    1993-02-01

    Piroxicam in pharmaceutical preparations (capsules (C), tablets (T), oral drops (OD), suppositories (S) and simulated sample (SS)) was determined by UV direct spectrophotometry (UVS) at 333 nm, by UV difference spectrophotometry (UVDS) at 327 nm, and in C and T, by high performance liquid chromatography (HPLC). For UVS, Beer's law was obeyed in the range 3.0-8.5 [mu]g/mL. The coefficient of correlation (CC), absolute precision (AP) and relative precision (RP) were 0.9999, 0.02 and 0.33%, respectively. The coefficient of variation (CV) for C, T, OD, S and SS were 0.48%, 0.35%, 0.48% and 0.19%, respectively. The recovery average (RA) was 100.22%.more » For UVDS, Beer's law was obeyed in the range 5.0-15.0 [mu]g/mL. The CC, AP and RP were respectively 0.9999, 0.05 and 0.47%. The CV for C, T, OD, S and SS were 0.64%, 0.84%, 0.62%, 0.54% and 0.15%, respectively. The RA was 99.02%. In HPLC determination, a LiChrospher[reg sign] 100 RP-18 (5 [mu]m) in LiChroCART[reg sign] 125-4 column at ambient temperature with a mobile phase consisting of methanol: (buffer solution citric acid-dibasic sodium phosphate pH 3.0) (55:45) and UV detection at 254 nm enabled the determination of piroxicam in C and T. The response peak area versus concentration presented linearity in the range 10.0-100.0 [mu]g/mL. The CC, AP and RP were 0.9997, 0.45 and 0.90%, respectively. The CV was 0.51%-0.82% and the RA, 97.13%. 14 refs., 1 fig., 5 tabs.« less

  4. Laser-based absorption spectroscopy as a technique for rapid in-line analysis of respired gas concentrations of O2 and CO2

    PubMed Central

    Cummings, Beth; Hamilton, Michelle L.; Ciaffoni, Luca; Pragnell, Timothy R.; Peverall, Rob; Ritchie, Grant A. D.; Hancock, Gus

    2011-01-01

    The use of sidestream analyzers for respired gas analysis is almost universal. However, they are not ideal for measurements of respiratory gas exchange because the analyses are both temporally dissociated from measurements of respiratory flow and also not generally conducted under the same physical conditions. This study explores the possibility of constructing an all optical, fast response, in-line breath analyzer for oxygen and carbon dioxide. Using direct absorption spectroscopy with a diode laser operating at a wavelength near 2 μm, measurements of expired carbon dioxide concentrations were obtained with an absolute limit of detection of 0.04% at a time resolution of 10 ms. Simultaneously, cavity enhanced absorption spectroscopy at a wavelength near 760 nm was employed to obtain measurements of expired oxygen concentrations with an absolute limit of detection of 0.26% at a time resolution of 10 ms. We conclude that laser-based absorption spectroscopy is a promising technology for in-line analysis of respired carbon dioxide and oxygen concentrations. PMID:21512147

  5. Laser-based absorption spectroscopy as a technique for rapid in-line analysis of respired gas concentrations of O2 and CO2.

    PubMed

    Cummings, Beth; Hamilton, Michelle L; Ciaffoni, Luca; Pragnell, Timothy R; Peverall, Rob; Ritchie, Grant A D; Hancock, Gus; Robbins, Peter A

    2011-07-01

    The use of sidestream analyzers for respired gas analysis is almost universal. However, they are not ideal for measurements of respiratory gas exchange because the analyses are both temporally dissociated from measurements of respiratory flow and also not generally conducted under the same physical conditions. This study explores the possibility of constructing an all optical, fast response, in-line breath analyzer for oxygen and carbon dioxide. Using direct absorption spectroscopy with a diode laser operating at a wavelength near 2 μm, measurements of expired carbon dioxide concentrations were obtained with an absolute limit of detection of 0.04% at a time resolution of 10 ms. Simultaneously, cavity enhanced absorption spectroscopy at a wavelength near 760 nm was employed to obtain measurements of expired oxygen concentrations with an absolute limit of detection of 0.26% at a time resolution of 10 ms. We conclude that laser-based absorption spectroscopy is a promising technology for in-line analysis of respired carbon dioxide and oxygen concentrations.

  6. Percutaneous absorption

    PubMed Central

    Brisson, Paul

    1974-01-01

    Clinical effectiveness of topically applied medications depends on the ability of the active ingredient to leave its vehicle and penetrate into the epidermis. The stratum corneum is that layer of the epidermis which functionally is the most important in limiting percutaneous absorption, showing the characteristics of a composite semipermeable membrane. A mathematical expression of transepidermal diffusion may be derived from Fick's Law of mass transport; factors altering the rate of diffusion are discussed. PMID:4597976

  7. Determination of chlorine in atmosphere by kinetic spectrophotometry.

    PubMed

    Meng, Jian-Xin; Wang, Xiao-Bo; Ruan, Ge-Lan; Li, Guo-Qiang; Deng, Zhao-Xia

    2005-03-01

    A kinetic method for determination of chlorine in air was described in the present work. The method based on fading of methyl orange (MO) containing solution in air absorption process. A determination limit of 2.64 microg L(-1) was found. With the present method, chlorine concentration could be determined in several minutes with convenient manipulation. As concentration variation of methyl orange in the absorption solution did not affect the experimental results, fabrication and preservation of the stock absorption is also convenient. The present method is promising in monitoring chlorine concentration in atmosphere.

  8. Determination of chlorine in atmosphere by kinetic spectrophotometry

    NASA Astrophysics Data System (ADS)

    Meng, Jian-Xin; Wang, Xiao-Bo; Ruan, Ge-Lan; Li, Guo-Qiang; Deng, Zhao-Xia

    2005-03-01

    A kinetic method for determination of chlorine in air was described in the present work. The method based on fading of methyl orange (MO) containing solution in air absorption process. A determination limit of 2.64 μg L -1 was found. With the present method, chlorine concentration could be determined in several minutes with convenient manipulation. As concentration variation of methyl orange in the absorption solution did not affect the experimental results, fabrication and preservation of the stock absorption is also convenient. The present method is promising in monitoring chlorine concentration in atmosphere.

  9. Intraoperative Vascular Neuromonitoring in Patients with Subarachnoid Hemorrhage: A Pilot Study Using Combined Laser-Doppler Spectrophotometry.

    PubMed

    Schmitz, Emilija; Bischoff, Barbara; Wolf, Dennis; Schmitt, Hubert J; Eyupoglu, Ilker Y; Roessler, Karl; Buchfelder, Michael; Sommer, Björn

    2017-11-01

    Intraoperative monitoring of cerebral microcirculation in patients with subarachnoid hemorrhage (SAH) may predict the postoperative neurologic outcome. In this pilot study, we examined the value of a novel noninvasive real-time measurement technique for detecting changes in local microcirculation. We used the O2C (Oxygen to see) laser-Doppler spectrophotometry system in 14 patients with Hunt & Hess grade 2-5 SAH who underwent microsurgical cerebral aneurysm clipping. A subdural probe recorded capillary venous oxygenation (SO 2 ), relative hemoglobin concentration, blood cell velocity, and blood flow at a tissue depth of 7 mm. Data were recorded immediately before dural closure. We also recorded somatosensory evoked potentials (SEPs) with median and tibial nerve stimulation. Results were compared with neurologic performance, as measured on the modified Rankin Scale, at the day of discharge from the hospital and 12 months thereafter. Patient functional outcomes after discharge and 12 months were correlated with pathological decreased flow and increased SO 2 values. In 6 of 8 patients, microcirculatory monitoring parameters indicated ischemia during surgery, as shown by electrophysiological SEP changes and infarction detected on the postoperative computed tomography (CT) scan. Pathological SEP results correlated closely with infarct demarcation as seen on CT. Our results indicate the potential benefit of intraoperative combined laser-Doppler flowmetry and spectrophotometry for predicting postoperative clinical outcomes in this small patient sample. Larger-cohort testing is needed to verify our findings and show the possible merits of this novel method. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. 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)

  11. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. [Infrared spectrophotometry for crystalline composition of staghorn calculi].

    PubMed

    Ma, Kai; Huang, Xiao-bo; Xu, Qing-quan; Li, Jian-xing; Xiong, Liu-lin; Yang, Bo; Ye, Xiong-jun; Chen, Liang; Wang, Xiao-feng; Na, Yan-qun

    2010-11-30

    To provide theoretic rationales for treatment and prevention of staghorn calculi by analyzing stone composition and studying the relationship between stone and urinary tract infections. The clinical data of 51 staghorn calculi patients were analyzed retrospectively. The stone compositions were studied by infrared spectrophotometry. Six types of stone compositions were obtained. There were calcium oxalate monohydrate, calcium oxalate dehydrate, carbonate apatite, magnesium ammonium phosphate hexahydrate, uric acid and L-cystine. The majority of stones were of mixed compositions, pure stones were found in 15 cases (29.4%). Among all stones, calcium oxalate stones were found in 41 cases (80.4%) and uric stones in 10 cases (19.6%). Infectious stones were found in 26 cases (51.0%). Urinary tract infections were found in 40 (78.4%) patients and positive urine/stone culture was detected in 33 (64.7%) patients. With multiple crystalline compositions and etiological factors, the staghorn calculi are closely correlated with urinary tract infections.

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

    PubMed

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

    2016-11-30

    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.

  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. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. 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)

  16. Classification of commercial wines from the Canary Islands (Spain) by chemometric techniques using metallic contents.

    PubMed

    Frías, Sergio; Conde, José E; Rodríguez-Bencomo, Juan J; García-Montelongo, Francisco; Pérez-Trujillo, Juan P

    2003-02-06

    Eleven elements, K, Na, Ca, Mg, Fe, Cu, Zn, Mn, Sr, Li and Rb, were determined in dry and sweet wines bearing the denominations of origin of El Hierro, La Palma and Lanzarote islands (Canary Islands, Spain). Analyses were performed by flame atomic absorption spectrophotometry, with the exceptions of lithium and rubidium for which flame atomic emission spectrophotometry was used. Sweet wines from La Palma were elaborated as naturally sweet with over-ripe grapes and significant differences were found in all the analysed elements with the exceptions of sodium, iron and rubidium with regard to dry wines from the same island. Contrarily, sweet wines from Lanzarote elaborated with grapes in a similar ripening state to dry wines did not present significant differences between them with the exception of strontium, the content of which was greater in dry wines. Among the three islands, significant differences in mean content were found with the exceptions of iron and copper. Cluster analysis and principal component analysis show differences in wines according to the island of origin and the ripening state of the grapes. Linear discriminant analysis using rubidium, sodium, manganese and strontium, the four most discriminant elements, gave 100% recognition ability and 95.6% prediction ability. The sensitivity and specificity obtained using soft independent modelling of class analogy (SIMCA) as a modelling multivariate technique were both 100% for El Hierro and Lanzarote, and 100 and 95%, respectively, for La Palma. The modelling and discriminant capacities of the different metals were also studied.

  17. Comparison of soil pollution concentrations determined using AAS and portable XRF techniques.

    PubMed

    Radu, Tanja; Diamond, Dermot

    2009-11-15

    Past mining activities in the area of Silvermines, Ireland, have resulted in heavily polluted soils. The possibility of spreading pollution to the surrounding areas through dust blow-offs poses a potential threat for the local communities. Conventional environmental soil and dust analysis techniques are very slow and laborious and consequently there is a need for fast and accurate analytical methods, which can provide real-time in situ pollution mapping. Laboratory-based aqua regia acid digestion of the soil samples collected in the area followed by the atomic absorption spectrophotometry (AAS) analysis confirmed very high pollution, especially by Pb, As, Cu, and Zn. In parallel, samples were analyzed using portable X-ray fluorescence radioisotope and miniature tube powered (XRF) NITON instruments and their performance was compared. Overall, the portable XRF instrument gave excellent correlation with the laboratory-based reference AAS method.

  18. Absorption Coefficient of a Semiconductor Thin Film from Photoluminescence

    NASA Astrophysics Data System (ADS)

    Rey, G.; Spindler, C.; Babbe, F.; Rachad, W.; Siebentritt, S.; Nuys, M.; Carius, R.; Li, S.; Platzer-Björkman, C.

    2018-06-01

    The photoluminescence (PL) of semiconductors can be used to determine their absorption coefficient (α ) using Planck's generalized law. The standard method, suitable only for self-supported thick samples, like wafers, is extended to multilayer thin films by means of the transfer-matrix method to include the effect of the substrate and optional front layers. α values measured on various thin-film solar-cell absorbers by both PL and photothermal deflection spectroscopy (PDS) show good agreement. PL measurements are extremely sensitive to the semiconductor absorption and allow us to advantageously circumvent parasitic absorption from the substrate; thus, α can be accurately determined down to very low values, allowing us to investigate deep band tails with a higher dynamic range than in any other method, including spectrophotometry and PDS.

  19. Correction of pathlength amplification in the filter-pad technique for measurements of particulate absorption coefficient in the visible spectral region.

    PubMed

    Stramski, Dariusz; Reynolds, Rick A; Kaczmarek, Sławomir; Uitz, Julia; Zheng, Guangming

    2015-08-01

    Spectrophotometric measurement of particulate matter retained on filters is the most common and practical method for routine determination of the spectral light absorption coefficient of aquatic particles, ap(λ), at high spectral resolution over a broad spectral range. The use of differing geometrical measurement configurations and large variations in the reported correction for pathlength amplification induced by the particle/filter matrix have hindered adoption of an established measurement protocol. We describe results of dedicated laboratory experiments with a diversity of particulate sample types to examine variation in the pathlength amplification factor for three filter measurement geometries; the filter in the transmittance configuration (T), the filter in the transmittance-reflectance configuration (T-R), and the filter placed inside an integrating sphere (IS). Relationships between optical density measured on suspensions (ODs) and filters (ODf) within the visible portion of the spectrum were evaluated for the formulation of pathlength amplification correction, with power functions providing the best functional representation of the relationship for all three geometries. Whereas the largest uncertainties occur in the T method, the IS method provided the least sample-to-sample variability and the smallest uncertainties in the relationship between ODs and ODf. For six different samples measured with 1 nm resolution within the light wavelength range from 400 to 700 nm, a median error of 7.1% is observed for predicted values of ODs using the IS method. The relationships established for the three filter-pad methods are applicable to historical and ongoing measurements; for future work, the use of the IS method is recommended whenever feasible.

  20. Qualitative and Quantitative Content Determination of Macro-Minor Elements in Bryonia Alba L. Roots using Flame Atomic Absorption Spectroscopy Technique.

    PubMed

    Karpiuk, Uliana Vladimirovna; Al Azzam, Khaldun Mohammad; Abudayeh, Zead Helmi Mahmoud; Kislichenko, Viktoria; Naddaf, Ahmad; Cholak, Irina; Yemelianova, Oksana

    2016-06-01

    To determine the elements in Bryonia alba L. roots, collected from the Crimean Peninsula region in Ukraine. Dry ashing was used as a flexible method and all elements were determined using atomic absorption spectrometry (AAS) equipped with flame and graphite furnace. The average concentrations of the determined elements, expressed as mg/100 g dry weight of the sample, were as follow: 13.000 for Fe, 78.000 for Si, 88.000 for P, 7.800 for Al, 0.130 for Mn, 105.000 for Mg, 0.030 for Pb, 0.052 for Ni, 0.030 for Mo, 210.000 for Ca, 0.130 for Cu, 5.200 for Zn, 13.000 for Na, 1170.000 for K, 0.780 for Sr, 0.030 for Co, 0.010 for Cd, 0.010 for As, and 0.010 for Hg. Toxic elements such as Cd and Pb were also found but at very low concentration. Among the analyzed elements, K was the most abundant followed by Ca, Mg, P, Si, Fe, Na, and Zn, whereas Hg, As, Cd, Co, Mo, and Pb were found in low concentration. The results suggest that the roots of Bryonia alba L. plant has potential medicinal property through their high element contents present. Moreover, it showed that the AAS method is a simple, fast, and reliable for the determination of elements in plant materials. The obtained results of the current study provide justification for the usage of such fruit in daily diet for nutrition and for medicinal usage in the treatment of various diseases.

  1. Qualitative and Quantitative Content Determination of Macro-Minor Elements in Bryonia Alba L. Roots using Flame Atomic Absorption Spectroscopy Technique

    PubMed Central

    Karpiuk, Uliana Vladimirovna; Al Azzam, Khaldun Mohammad; Abudayeh, Zead Helmi Mahmoud; Kislichenko, Viktoria; Naddaf, Ahmad; Cholak, Irina; Yemelianova, Oksana

    2016-01-01

    Purpose: To determine the elements in Bryonia alba L. roots, collected from the Crimean Peninsula region in Ukraine. Methods: Dry ashing was used as a flexible method and all elements were determined using atomic absorption spectrometry (AAS) equipped with flame and graphite furnace. Results: The average concentrations of the determined elements, expressed as mg/100 g dry weight of the sample, were as follow: 13.000 for Fe, 78.000 for Si, 88.000 for P, 7.800 for Al, 0.130 for Mn, 105.000 for Mg, 0.030 for Pb, 0.052 for Ni, 0.030 for Mo, 210.000 for Ca, 0.130 for Cu, 5.200 for Zn, 13.000 for Na, 1170.000 for K, 0.780 for Sr, 0.030 for Co, 0.010 for Cd, 0.010 for As, and 0.010 for Hg. Toxic elements such as Cd and Pb were also found but at very low concentration. Among the analyzed elements, K was the most abundant followed by Ca, Mg, P, Si, Fe, Na, and Zn, whereas Hg, As, Cd, Co, Mo, and Pb were found in low concentration. Conclusion: The results suggest that the roots of Bryonia alba L. plant has potential medicinal property through their high element contents present. Moreover, it showed that the AAS method is a simple, fast, and reliable for the determination of elements in plant materials. The obtained results of the current study provide justification for the usage of such fruit in daily diet for nutrition and for medicinal usage in the treatment of various diseases. PMID:27478794

  2. 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.

  3. Simultaneous determination of dextromethorphan HBr and bromhexine HCl in tablets by first-derivative spectrophotometry.

    PubMed

    Tantishaiyakul, V; Poeaknapo, C; Sribun, P; Sirisuppanon, K

    1998-06-01

    A rapid, simple and direct assay procedure based on first-derivative spectrophotometry, using a zero-crossing and peak-to-base measurement at 234 and 324 nm, respectively, has been developed for the specific determination of dextromethorphan HBr and bromhexine HCl in tablets. Calibration graphs were linear with the correlation coefficients of 0.9999 for both analytes. The limit of detections were 0.033 and 0.103 microgram ml-1 for dextromethorphan HBr and bromhexine HCl, respectively. A HPLC method has been developed as the reference method. The results obtained by the first-derivative spectrophotometry were in good agreement with those found by the HPLC method.

  4. Estimation of nitrate and nitrogen forms of vegetables by UV-spectrophotometry after photo-oxydation.

    PubMed

    Ribeiro, T; Depres, S; Couteau, G; Pauss, A

    2003-01-01

    An alternative method for the estimation of nitrate and nitrogen forms in vegetables is proposed. Nitrate can be directly estimated by UV-spectrophotometry after an extraction step with water. The other nitrogen compounds are photo-oxidized into nitrate, and then estimated by UV-spectrophotometry. An oxidative solution of sodium persulfate and a Hg-UV lamp is used. Preliminary assays were realized with vegetables like salade, spinachs, artichokes, small peas, broccolis, carrots, watercress; acceptable correlations between expected and experimental values of nitrate amounts were obtained, while the detection limit needs to be lowered. The optimization of the method is underway.

  5. 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 CCl 4 (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.

  6. 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.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    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 × 107 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.

  9. 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. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Absorption rates and free radical scavenging values of vitamin C-lipid metabolites in human lymphoblastic cells.

    PubMed

    Weeks, Benjamin S; Perez, Pedro P

    2007-10-01

    In this study we investigated the cellular absorption rates, antioxidant and free radical scavenging activity of vitamin C-lipid metabolites. The absorption was measured in a human lymphoblastic cell line using a spectrophotometric technique. Cellular vitamin C levels in the human lymphoblastic H9 cell line were measured using the 2,4-dinitrophenylhydrazine spectrophotometric technique. Free radical scavenging activity of vitamin C-lipid metabolites was measured by the reduction of 1,1-diphenyl-2-picryl hydrazyl (DPPH) to 1,1-diphenyl-2-picryl hydrazine. Vitamin C-lipid metabolite scavenging of peroxyl radical oxygen reactive species (ORAC) was determined by fluorescence spectrophotometry. Compared to ascorbic acid (AA), calcium ascorbate (CaA), and calcium ascorbate-calcium threonate-dehydroascorbate (Ester-C), vitamin C-lipid metabolites (PureWay-C) were more rapidly absorbed by the H9 human T-lymphocytes. The vitamin C-lipid metabolites (PureWay-C) also reduced pesticide-induced T-lymphocyte aggregation by 84%, while calcium ascorbate-calcium threonate-dehydroascorbate (Ester-C) reduced aggregation by only 34%. The vitamin C-lipid metabolites (PureWay-C) demonstrated free radical scavenging activity of nearly 100% reduction of DPPH at 20 microg/ml and oxygen radical scavenging of over 1200 micro Trolox equivalents per gram. These data demonstrate that the vitamin C-lipid metabolites (PureWay-C) are more rapidly taken-up and absorbed by cells than other forms of vitamin C, including Ester-C. This increased rate of absorption correlates with an increased protection of the T-lymphocytes from pesticide toxicities. Further, vitamin C-lipid metabolites (PureWay-C) are a potent antioxidant and have significant free radical scavenging capabilities.

  11. Spectrophotometry at 10 microns of T Tauri stars

    NASA Technical Reports Server (NTRS)

    Cohen, M.; Witteborn, F. C.

    1985-01-01

    New 8-13 micron spectra of 32 T Tau, or related young, stars are presented. Silicate emission features are commonly seen. Absorptions occur less frequently but also match the properties of silicate materials. The shape of the emission feature suggests that a more crystalline grain is responsible in the T Tau stars than those of the Trapezium region. The evolution of the silicate component of the circumstellar shell around T Tau stars, and its dependence upon stellar wind activity, visual linear polarization, and extinction are investigated. Several correlations suggest that the shells are likely to be flattened, disklike structures rather than spherical.

  12. 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.

  13. The synthesis of corncobs (zea mays) active charcoal and water hyacinth (eichornia crassipes) adsorbent to adsorb Pb(II) with it’s analysis using solid-phase spectrophotometry (sps)

    NASA Astrophysics Data System (ADS)

    Saputro, S.; Masykuri, M.; Mahardiani, L.; Kurniastuti, D.

    2018-03-01

    This research aim to examine the effect of the combination between corncobs and water hyacinth to adsorb lead (II), the most effective combination have determined by compared the ratio of corncobs adsorbent and water hyacinth to the increasing adsorption of the Pb(II), prove the effectiveness of the solid-phase spectrophotometry (sps) to determine the levels of Pb(II) as the result of the corncobs active charcoal adsorption and water hyacinth in the level of µg/L. The research method used is experimental method. The data collecting technique is carried out by several stages, which are carbonization using muffle furnace at a temperature of 350°C for 1.5 hours, activation of the corncobs charcoal and water hyacinth using HCl 1M and HCl 5M activator, contacting the adsorbent of corncobs active charcoal and water hyacinth with liquid waste simulation of Pb(II) using variation of corncobns and water hyacinth, 1:0; 0:1; 1:1; 2:1; 1:2, analysis of Pb(II) using an sps, characterization of corncobs active charcoal adsorbent and water hyacinth using FTIR. Research results show that the combined effect of activated charcoal corncobs and water hyacinth can increase the ability of the adsorbent to absorb Pb(II), the optimum adsorbent mass ratio of 1:1 with the absorption level of 90.33%, SPS is an effective method to analyze the decreasing level of Pb(II) as the adsorbtion result of the corncobs active charcoal and water hyacinth in the level of µg/L, with the limit of detection (LOD) of 0.06 µg/L.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Spectrophotometry or visual inspection to most reliably detect xanthochromia in subarachnoid hemorrhage: systematic review.

    PubMed

    Chu, Kevin; Hann, Angus; Greenslade, Jaimi; Williams, Julian; Brown, Anthony

    2014-09-01

    We assess the sensitivity and specificity of xanthochromia as adjudicated by visual inspection and spectrophotometry at predicting the presence of cerebral aneurysm in patients with suspected subarachnoid hemorrhage who have a normal computed tomography (CT) head scan result. A systematic review was performed. MEDLINE and EMBASE databases were searched. Relevant studies with clinical data on the diagnostic accuracy of visual inspection or spectrophotometry were considered. Patients who had a normal CT head scan result followed by a lumbar puncture were included in this review. Sensitivities, specificities, and heterogeneity (I(2)) were calculated. Subgroup analyses were performed to explore reasons for the heterogeneity. There were major methodological limitations in the studies found. Twenty-two relevant articles were heterogeneous in regard to time to lumbar puncture, spectrophotometry methods, and follow-up of patients not undergoing cerebral angiography. Twelve of the 22 studies selected patients on the basis of a cerebral aneurysm or subarachnoid hemorrhage on imaging, or a positive lumbar puncture result. These studies were excluded from our initial analysis, which included only patients with clinically suspected subarachnoid hemorrhage. In this initial analysis, pooled estimates of sensitivity and specificity for spectrophotometry were 87% (95% confidence interval [CI] 71% to 96%; I(2)=26%) and 86% (95% CI 84% to 88%; I(2)=96%), respectively. For visual inspection, pooled sensitivity and specificity were 83% (95% CI 59% to 96%; I(2)=52%) and 96% (95% CI 93% to 97%; I(2)=76%), respectively. Sensitivity estimates are difficult to interpret without knowing time to lumbar puncture. The heterogeneity in the underlying studies, combined with significant overlap in pooled confidence limits, makes it impossible to provide a definite conclusion about the diagnostic accuracy of spectrophotometry versus visual inspection. Copyright © 2014 American College of Emergency

  20. A methodological approach to study the stability of selected watercolours for painting reintegration, through reflectance spectrophotometry, Fourier transform infrared spectroscopy and hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Pelosi, Claudia; Capobianco, Giuseppe; Agresti, Giorgia; Bonifazi, Giuseppe; Morresi, Fabio; Rossi, Sara; Santamaria, Ulderico; Serranti, Silvia

    2018-06-01

    The aim of this work is to investigate the stability to simulated solar radiation of some paintings samples through a new methodological approach adopting non-invasive spectroscopic techniques. In particular, commercial watercolours and iron oxide based pigments were used, these last ones being prepared for the experimental by gum Arabic in order to propose a possible substitute for traditional reintegration materials. Reflectance spectrophotometry in the visible range and Hyperspectral Imaging in the short wave infrared were chosen as non-invasive techniques for evaluation the stability to irradiation of the chosen pigments. These were studied before and after artificial ageing procedure performed in Solar Box chamber under controlled conditions. Data were treated and elaborated in order to evaluate the sensitivity of the chosen techniques in identifying the variations on paint layers, induced by photo-degradation, before they could be observed by eye. Furthermore a supervised classification method for monitoring the painted surface changes adopting a multivariate approach was successfully applied.

  1. 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.

  2. 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.

  3. 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.

  4. Noise analysis for CCD-based ultraviolet and visible spectrophotometry.

    PubMed

    Davenport, John J; Hodgkinson, Jane; Saffell, John R; Tatam, Ralph P

    2015-09-20

    We present the results of a detailed analysis of the noise behavior of two CCD spectrometers in common use, an AvaSpec-3648 CCD UV spectrometer and an Ocean Optics S2000 Vis spectrometer. Light sources used include a deuterium UV/Vis lamp and UV and visible LEDs. Common noise phenomena include source fluctuation noise, photoresponse nonuniformity, dark current noise, fixed pattern noise, and read noise. These were identified and characterized by varying light source, spectrometer settings, or temperature. A number of noise-limiting techniques are proposed, demonstrating a best-case spectroscopic noise equivalent absorbance of 3.5×10(-4)  AU for the AvaSpec-3648 and 5.6×10(-4)  AU for the Ocean Optics S2000 over a 30 s integration period. These techniques can be used on other CCD spectrometers to optimize performance.

  5. Coordinated Time Resolved Spectrophotometry of Asteroid 163249 (2002 GT)

    NASA Astrophysics Data System (ADS)

    Ryan, Erin L.; Woodward, C.; Gordon, M.; Wagner, M. R.; Chesley, S.; Hicks, M.; Pittichova, J.; Pravec, P.

    2013-10-01

    The near-Earth asteroid 163249 (2002 GT), classified as a potentially hazardous asteroid (PHA), has been identified a potential rendezvous target for the NASA Deep Impact spacecraft on 4 Jan 2020. As part of a coordinated international effort to study this asteroid during its 2013 apparition (J. Pittichová et al. DPS 2013), we obtained simultaneous Sloan r-band photometry at the Steward Observatory Bok 2.3-m telescope (+90Prime) and optical spectroscopic observations covering a wavelength interval from ~5400 to ~8500 Angstrom at the MMT 6.5-m (+RedChannel spectrograph) on 2013 June 16 and 17 UT near close Earth approach (heliocentric distance ~1.07 AU; geocentric distance ~0.13 AU) at 180 sec intervals over the ~3.76 hr rotational period. Our objective was to obtain a temporal sequence of spectra to assess surface mineralogy (seeking to potentially detect the 0.7 micron absorption bands attributed to phylosilicate materials) and to determine whether variations in the spectral slope and/or surface mineralogy are evident as a function of rotational period. Here we present initial analysis of these datasets, describing the light-curve and the reflectance spectra as a function of rotational phase. These datasets will be incorporated into a larger compendium describing the characteristics of asteroid 163249. Acknowledgement: This research supported in part by NASA 12-PAST-12-0010 grant NNX13AJ11G , and an appointment (E.L.R.) to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by Oak Ridge Associated Universities through a contract with NASA. Observations reported here were obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona. P.P. was supported by the Grant Agency of the Czech Republic, Grant P209/12/0229.

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

    NASA Astrophysics Data System (ADS)

    Brown, R. H.

    1983-12-01

    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. 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.

  8. Complex polarimetric and spectral techniques in diagnostics of blood plasma of patients with ovarian cancer as a preliminary stage molecular genetic screening

    NASA Astrophysics Data System (ADS)

    Grzegorzewski, B.; Peresunko, O. P.; Yermolenko, S. B.

    2018-01-01

    This work is devoted to the substantiation and selection of patients with ovarian cancer (OC) for the purpose of conducting expensive molecular genetic studies on genotyping. As diagnostic methods have been used ultraviolet spectrometry samples of blood plasma in the liquid state, infrared spectroscopy middle range (2,5 - 25 microns) dry residue of plasma polarization and laser diagnostic technique of thin histological sections of biological tissues. Obtained results showed that the use of spectrophotometry in the range of 1000-3000 cm-1 allowed to establish quantitative parameters of the plasma absorption rate of blood of patients in the third group in different ranges, which would allow in the future to conduct an express analysis of the patient's condition (procedure screening) for further molecular-genetic typing on BRCA I and II.

  9. Spectrophotometry of planetary atmosphere from the X-15 rocket airplane

    NASA Technical Reports Server (NTRS)

    Murcray, W. B.

    1973-01-01

    Nike-Apache and Nike-Tomahawk rocket flights using spectrophotometric techniques to investigate auroral activity are reported. The specific objectives were to obtain data relative to typical auroral situations, including quiet pre-breakup auroras, westward traveling surges, breakup auroras, and post-breakup auroras. It was found that excited atoms move considerable distances between excitation and emission owing to the high velocity wind conditions prevailing above 200 km. Based on the results of these observations, recommendations are made for future studies of ionized atmospheric activity at higher altitudes.

  10. Accuracy of indocyanine green pulse spectrophotometry clearance test for liver function prediction in transplanted patients

    PubMed Central

    Hsieh, Chung-Bao; Chen, Chung-Jueng; Chen, Teng-Wei; Yu, Jyh-Cherng; Shen, Kuo-Liang; Chang, Tzu-Ming; Liu, Yao-Chi

    2004-01-01

    AIM: To investigate whether the non-invasive real-time Indocynine green (ICG) clearance is a sensitive index of liver viability in patients before, during, and after liver transplantation. METHODS: Thirteen patients were studied, two before, three during, and eight following liver transplantation, with two patients suffering acute rejection. The conventional invasive ICG clearance test and ICG pulse spectrophotometry non-invasive real-time ICG clearance test were performed simultaneously. Using linear regression analysis we tested the correlation between these two methods. The transplantation condition of these patients and serum total bilirubin (T. Bil), alanine aminotransferase (ALT), and platelet count were also evaluated. RESULTS: The correlation between these two methods was excellent (r2 = 0.977). CONCLUSION: ICG pulse spectrophotometry clearance is a quick, non-invasive, and reliable liver function test in transplantation patients. PMID:15285026

  11. 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. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. The Use of Self-scanned Silicon Photodiode Arrays for Astronomical Spectrophotometry

    NASA Technical Reports Server (NTRS)

    Cochran, A. L.

    1984-01-01

    The use of a Reticon self scanned silicon photodiode array for precision spectrophotometry is discussed. It is shown that internal errors are + or - 0.003 mag. Observations obtained with a photodiode array are compared with observations obtained with other types of detectors with agreement, from 3500 A to 10500 A, of 1%. The photometric properties of self scanned photodiode arrays are discussed. Potential pitfalls are given.

  13. 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.

  14. Measurement of stain on extracted teeth using spectrophotometry and digital image analysis.

    PubMed

    Lath, D L; Smith, R N; Guan, Y H; Karmo, M; Brook, A H

    2007-08-01

    The aim of this study was to assess the reliability and validate a customized image analysis system, designed for use within clinical trials of general dental hygiene and whitening products, for the measurement of stain levels on extracted teeth and to compare it with reflectance spectrophotometry. Twenty non-carious extracted teeth were soaked in an artificial saliva, brushed for 1 min using an electric toothbrush and a standard toothpaste, bleached using a 5.3% hydrogen peroxide solution and cycled for 6 h daily through a tea solution. CIE L* values were obtained after each treatment step using the customized image analysis system and a reflectance spectrophotometer. A statistical analysis was carried out in SPSS. Fleiss' coefficient of reliability for intra-operator repeatability of the image analysis system and spectrophotometry was 0.996 and 0.946 respectively. CIE L* values were consistently higher using the image analysis compared with spectrophotometry, and t-tests for each treatment step showed significant differences (P < 0.05) for the two methods. Limits of agreement between the methods were -27.95 to +2.07, with a 95% confidence of the difference calculated as -14.26 to -11.84. The combined results for all treatment steps showed a significant difference between the methods for the CIE L* values (P < 0.05). The image analysis system has proven to be a reliable method for assessment of changes in stain level on extracted teeth. The method has been validated against reflectance spectrophotometry. This method may be used for pilot in vitro studies/trials of oral hygiene and whitening products, before expensive in vivo tests are carried out.

  15. Comparison of gas chromotography, spectrophotometry and near infrared spectroscopy to quantify prussic acid potential in forages.

    PubMed

    Goff, Ben M; Moore, Kenneth J; Fales, Steven L; Pedersen, Jeffery F

    2011-06-01

    Sorghum [Sorghum bicolor (L.) Moench] has been shown to contain the cyanogenic glycoside dhurrin, which is responsible for the disorder known as prussic acid poisoning in livestock. The current standard method for estimating hydrogen cyanide (HCN) uses spectrophotometry to measure the aglycone, p-hydroxybenzaldehyde (p-HB), after hydrolysis. Errors may occur due to the inability of this method to solely estimate the absorbance of p-HB at a given wavelength. The objective of this study was to compare the use of gas chromatography (GC) and near infrared spectroscopy (NIRS) methods, along with a spectrophotometry method to estimate the potential for prussic acid (HCNp) of sorghum and sudangrasses over three stages maturities. It was shown that the GC produced higher HCNp estimates than the spectrophotometer for the grain sorghums, but lower concentrations for the sudangrass. Based on what is known about the analytical process of each method, the GC data is likely closer to the true HCNp concentrations of the forages. Both the GC and spectrophotometry methods yielded robust equations with the NIRS method; however, using GC as the calibration method resulted in more accurate and repeatable estimates. The HCNp values obtained from using the GC quantification method are believed to be closer to the actual values of the forage, and that use of this method will provide a more accurate and easily automated means of quantifying prussic acid. Copyright © 2011 Society of Chemical Industry.

  16. 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. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. 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.

  18. 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).

  19. 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".

  20. Interactions of praseodymium and neodymium with nucleosides and nucleotides: absorption difference and comparative absorption spectral study.

    PubMed

    Misra, S N; Anjaiah, K; Joseph, G; Abdi, S H

    1992-02-01

    The interactions of praseodymium(III) and neodymium(III) with nucleosides and nucleotides have been studied in different stoichiometry in water and water-DMF mixtures by employing absorption difference and comparative absorption spectrophotometry. The 4f-4f bands were analysed by linear curve analysis followed by gaussian curve analysis, and various spectral parameters were computed, using partial and multiple regression method. The magnitude of changes in both energy interaction and intensity were used to explore the degree of outer and inner sphere coordination, incidence of covalency and the extent of metal 4f-orbital involvement in chemical bonding. Crystalline complexes of the type [Ln(nucleotide)2(H2O)2]- (where nucleotide--GMP or IMP) were characterized by IR, 1H NMR, 31P NMR data. These studies indicated that the binding of the nucleotide is through phosphate oxygen in a bidentate manner and the complexes undergo substantial ionisation in aqueous medium, thereby supporting the observed weak 4f-4f bands and lower values for nephelauxetic effect (1-beta), bonding (b) and covalency (delta) parameters derived from coulombic and spin orbit interaction parameters.

  1. Comparative study between derivative spectrophotometry and multivariate calibration as analytical tools applied for the simultaneous quantitation of Amlodipine, Valsartan and Hydrochlorothiazide.

    PubMed

    Darwish, Hany W; Hassan, Said A; Salem, Maissa Y; El-Zeany, Badr A

    2013-09-01

    Four simple, accurate and specific methods were developed and validated for the simultaneous estimation of Amlodipine (AML), Valsartan (VAL) and Hydrochlorothiazide (HCT) in commercial tablets. The derivative spectrophotometric methods include Derivative Ratio Zero Crossing (DRZC) and Double Divisor Ratio Spectra-Derivative Spectrophotometry (DDRS-DS) methods, while the multivariate calibrations used are Principal Component Regression (PCR) and Partial Least Squares (PLSs). The proposed methods were applied successfully in the determination of the drugs in laboratory-prepared mixtures and in commercial pharmaceutical preparations. The validity of the proposed methods was assessed using the standard addition technique. The linearity of the proposed methods is investigated in the range of 2-32, 4-44 and 2-20 μg/mL for AML, VAL and HCT, respectively. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Comparative study between derivative spectrophotometry and multivariate calibration as analytical tools applied for the simultaneous quantitation of Amlodipine, Valsartan and Hydrochlorothiazide

    NASA Astrophysics Data System (ADS)

    Darwish, Hany W.; Hassan, Said A.; Salem, Maissa Y.; El-Zeany, Badr A.

    2013-09-01

    Four simple, accurate and specific methods were developed and validated for the simultaneous estimation of Amlodipine (AML), Valsartan (VAL) and Hydrochlorothiazide (HCT) in commercial tablets. The derivative spectrophotometric methods include Derivative Ratio Zero Crossing (DRZC) and Double Divisor Ratio Spectra-Derivative Spectrophotometry (DDRS-DS) methods, while the multivariate calibrations used are Principal Component Regression (PCR) and Partial Least Squares (PLSs). The proposed methods were applied successfully in the determination of the drugs in laboratory-prepared mixtures and in commercial pharmaceutical preparations. The validity of the proposed methods was assessed using the standard addition technique. The linearity of the proposed methods is investigated in the range of 2-32, 4-44 and 2-20 μg/mL for AML, VAL and HCT, respectively.

  3. 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.

  4. 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. © 2010 Blackwell Publishing Ltd.

  5. Acid-Base Properties of Azo Dyes in Solution Studied Using Spectrophotometry and Colorimetry

    NASA Astrophysics Data System (ADS)

    Snigur, D. V.; Chebotarev, A. N.; Bevziuk, K. V.

    2018-03-01

    Colorimetry and spectrophotometry with chemometric data processing were used to study the acid-base properties of azo dyes in aqueous solution. The capabilities of both methods were compared. Ionization constants of all the functional groups of the azo compounds studied could be determined relative to the change in the specific color difference depending on the acidity of the medium. The colorimetric functions of ion-molecular forms of azo compounds used as an analytical signal allow us to obtain complete information on the acid-base equilibrium in a wide acidity range.

  6. Absolute spectrophotometry of Wolf-Rayet stars from 1200 to 7000 A - A cautionary tale

    NASA Technical Reports Server (NTRS)

    Garmany, C. D.; Conti, P. S.; Massey, P.

    1984-01-01

    It is demonstrated that absolute spectrophotometry of the continua of Wolf-Rayet stars may be obtained over the wavelength range 1200-7000 A using IUE and optical measurements. It is shown that the application of a 'standard' reddening law to the observed data gives spurious results in many cases. Additional UV extinction is apparently necessary and may well be circumstellar in origin. In such hot stars, the long-wavelength 'tail' of the emergent stellar continuum are measured. The inadequacy of previous attempts to determine intrinsic continua and effective temperatures of Wolf-Rayet stars is pointed out.

  7. Rocket instrument for far-UV spectrophotometry of faint astronomical objects.

    PubMed

    Hartig, G F; Fastie, W G; Davidsen, A F

    1980-03-01

    A sensitive sounding rocket instrument for moderate (~10-A) resolution far-UV (lambda1160-lambda1750-A) spectrophotometry of faint astronomical objects has been developed. The instrument employs a photon-counting microchannel plate imaging detector and a concave grating spectrograph behind a 40-cm Dall-Kirkham telescope. A unique remote-control pointing system, incorporating an SIT vidicon aspect camera, two star trackers, and a tone-encoded command telemetry link, permits the telescope to be oriented to within 5 arc sec of any target for which suitable guide stars can be found. The design, construction, calibration, and flight performance of the instrument are discussed.

  8. 2.7- to 4.1-micron spectrophotometry of icy satellites of Saturn and Jupiter

    NASA Technical Reports Server (NTRS)

    Lebofsky, L. A.; Feierberg, M. A.

    1985-01-01

    Spectrophotometry is presented in the 2.7-4.1 micrometer spectral region for icy satellites of Saturn (Tethys, Dione, Rhea, Iapetus and Hyperion) and Jupiter (Europa, Ganymede and Callisto). The 3.6-micrometer reflectance peak characteristic of fine-grained water ice is observed prominently on the satellites of Saturn, faintly on the leading side of Europa, and not at all on Ganymede, Callisto or the dark side of Iapetus. The spectral reflectances of these icy satellites may be affected by their equilibrium surface temperatures and magnetospheric effects.

  9. 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.

  10. 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.

  11. 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.

  12. In-vitro Equilibrium Phosphate Binding Study of Sevelamer Carbonate by UV-Vis Spectrophotometry.

    PubMed

    Prasaja, Budi; Syabani, M Maulana; Sari, Endah; Chilmi, Uci; Cahyaningsih, Prawitasari; Kosasih, Theresia Weliana

    2018-06-12

    Sevelamer carbonate is a cross-linked polymeric amine; it is the active ingredient in Renvela ® tablets. US FDA provides recommendation for demonstrating bioequivalence for the development of a generic product of sevelamer carbonte using in-vitro equilibrium binding study. A simple UV-vis spectrophotometry method was developed and validated for quantification of free phosphate to determine the binding parameter constant of sevelamer. The method validation demonstrated the specificity, limit of quantification, accuracy and precision of measurements. The validated method has been successfully used to analyze samples in in-vitro equilibrium binding study for demonstrating bioequivalence. © Georg Thieme Verlag KG Stuttgart · New York.

  13. Nickel absorption and kinetics in human volunteers.

    PubMed

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

    1989-05-01

    Mathematical modeling of the kinetics of nickel absorption, distribution, and elimination was performed in healthy human volunteers who ingested NiSO4 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 NiSO4 dose (12 micrograms of nickel/kg, n = 4; 18 micrograms of nickel/kg, n = 4; or 50 micrograms of nickel/kg, n = 1). In Experiment 1, each of the subjects fasted 12 hr before and 3 hr after drinking one of the specified NiSO4 doses dissolved in water; in Experiment 2, the respective subjects fasted 12 hr before consuming a standard American breakfast that contained the identical dose of NiSO4 added to scrambled eggs. Kinetic analyses, using a compartmental model, provided excellent goodness-of-fit for paired data sets from all subjects. Absorbed nickel averaged 27 +/- 17% (mean +/- SD) of the dose ingested in water vs 0.7 +/- 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 +/- 9 hr. Renal clearance of nickel averaged 8.3 +/- 2.0 ml/min/1.73 m2 in Experiment 1 and 5.8 +/- 4.3 ml/min/1.73 m2 in Experiment 2. This study confirms that dietary constituents profoundly reduce the bioavailability of Ni2+ 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.

  14. 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

    to carbonyl- and nitro- functional groups on conjugated and aromatic organic structures (e.g. PAH, and terpene derived products). Using 12-hour fine (0.1-1.0 micron) aerosol samples collected in the field on quartz filters, uv/vis and infrared spectra were obtained in the laboratory using integrating spheres and diffuse reflectance spectroscopy, respectively. An inter-comparison of the "real-time" measurements made by the photo-acoustic, aethalometer and MAAP techniques have been described. In addition, the in situ aethalometer (seven-channel) results are compared with continuous integrating sphere uv-visible spectra to examine the angstrom absorption coefficient variance. These results will be briefly overviewed and the specific posters detailing these results will be highlighted highlighted. This work was performed as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City under the support of the Atmospheric Science Program. "This researchwas supported by the Office of Science (BER), U. S. Department of Energy, Grant No. DE-FG02-07ER64329.

  15. A novel double-tracer technique to characterize absorption, distribution, metabolism and excretion (ADME) of [14C]tofogliflozin after oral administration and concomitant intravenous microdose administration of [13C]tofogliflozin in humans.

    PubMed

    Schwab, Dietmar; Portron, Agnes; Backholer, Zoe; Lausecker, Berthold; Kawashima, Kosuke

    2013-06-01

    Human mass balance studies and the assessment of absolute oral bioavailability (F) are usually assessed in separate studies. Intravenous microdose administration of an isotope tracer concomitant to an unlabeled oral dose is an emerging technique to assess F. We report a novel double-tracer approach implemented for tofogliflozin combining oral administration of a radiolabel tracer with concomitant intravenous administration of a stable isotope tracer. Tofogliflozin is a potent and selective sodium/glucose cotransporter 2 inhibitor for the treatment of type 2 diabetes mellitus currently in clinical development. The objectives of the present study were to assess the systemic exposure of major circulating metabolites, excretion balance, F and contribution of renal clearance (CLR) to total clearance (CL) of tofogliflozin in healthy subjects within one study applying a novel double-tracer technique. Six healthy male subjects received 20 mg [(12)C/(14)C]tofogliflozin (3.73 MBq) orally and a concomitant microdose of 0.1 mg [(13)C]tofogliflozin intravenously. Pharmacokinetics of tofogliflozin were determined for the oral and intravenous route; the pharmacokinetics of the metabolites M1 and M5 were determined for the oral route. Quantification of [(12)C]tofogliflozin in plasma and urine and [(13)C]tofogliflozin in plasma was performed by selective LC-MS/MS methods. For the pre-selected metabolites of tofogliflozin, M1 and M5, a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) was applied to plasma and urine samples. Total radioactivity was assessed in plasma, urine and feces. Pharmacokinetic analysis was conducted by non-compartmental methods. The pharmacokinetics of tofogliflozin in healthy subjects were characterized by an F of 97.5 ± 12.3 %, CL of 10.0 ± 1.3 l/h and volume of distribution at steady-state (V(ss)) of 50.6 ± 6.7 l. The main route of elimination of total drug-related material was by excretion into urine (77.0 ± 4.1 % of the dose). The

  16. 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. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. 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.

  18. Levels of cadmium, lead and zinc protoporphyrin absorption in different risk groups.

    PubMed

    Aurelio, L M; Pilar, D L; Fulgencio, G G; Adoración, P B; Enrique, G C; Alicia, H M; Aurelio, L M

    1993-12-01

    We studied groups of workers, of pregnant women and of neonates exposed and unexposed to cadmium and lead at their place of work or in the environment. A total of 118 exposed and 28 unexposed workers were studied, together with 90 exposed and 100 unexposed pregnant women and neonates. Concentrations of cadmium and lead in the blood were determined by atomic absorption spectrophotometry. There were significant differences in cadmium concentrations between workers and neonates, and significant differences in lead concentrations between workers and pregnant women. We believe these differences are due mainly to high levels of pollution in the area studied.

  19. 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

  20. Optical properties of orthodontic aligners--spectrophotometry analysis of three types before and after aging.

    PubMed

    Lombardo, Luca; Arreghini, Angela; Maccarrone, Roberta; Bianchi, Anna; Scalia, Santo; Siciliani, Giuseppe

    2015-01-01

    The aim was to assess and compare absorbance and transmittance values of three types of clear orthodontic aligners before and after two cycles of in vitro aging. Nine samples of orthodontic aligners from three different manufacturers (Invisalign, Align Technology, Santa Clara, CA, USA; All-In, Micerium, Avegno, GE, Italy; F22 Aligner, Sweden & Martina, Due Carrare, PD, Italy) were selected, and each sample was subjected to spectrophotometry analysis of both its transmittance and absorbance a total of 27 times. Samples were subsequently aged in vitro at a constant temperature in artificial saliva supplemented with food colouring for two cycles of 14 days each. The spectrophotometry protocol was then repeated, and the resulting data were analysed and compared by means of ANOVA (p < 0.05). All types of aligners tested yielded lower transmittance and higher absorbance values after aging, but the difference was not significant in any case. That being said, the F22 aligners were found to be most transparent, both before and after aging, followed by Invisalign and All-In, and these differences were statistically significant. Commercial aligners possess significantly different optical, and therefore aesthetic, properties, both as delivered and following aging.

  1. 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. Copyright © 2013 Wiley Periodicals, Inc.

  2. 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.

  3. 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.

  4. Feasibility of Using Fluorescence Spectrophotometry to Develop a Sensitive Dye Immersion Method for Container Closure Integrity Testing of Prefilled Syringes.

    PubMed

    Lu, Xujin; Lloyd, David K; Klohr, Steven E

    2016-01-01

    A feasibility study was conducted for a sensitive and robust dye immersion method for the measurement of container closure integrity of unopened prefilled syringes using fluorescence spectrophotometry as the detection method. A Varian Cary Eclipse spectrofluorometer was used with a custom-made sample holder to position the intact syringe in the sample compartment for fluorescence measurements. Methylene blue solution was initially evaluated as the fluorophore in a syringe with excitation at 607 nm and emission at 682 nm, which generated a limit of detection of 0.05 μg/mL. Further studies were conducted using rhodamine 123, a dye with stronger fluorescence. Using 480 nm excitation and 525 nm emission, the dye in the syringe could be easily detected at levels as low as 0.001 μg/mL. The relative standard deviation for 10 measurements of a sample of 0.005 μg/mL (with repositioning of the syringe after each measurement) was less than 1.1%. A number of operational parameters were optimized, including the photomultiplier tube voltage, excitation, and emission slit widths. The specificity of the testing was challenged by using marketed drug products and a protein sample, which showed no interference to the rhodamine detection. Results obtained from this study demonstrated that using rhodamine 123 for container closure integrity testing with in-situ (in-syringe) fluorescence measurements significantly enhanced the sensitivity and robustness of the testing and effectively overcame limitations of the traditional methylene blue method with visual or UV-visible absorption detection. Ensuring container closure integrity of injectable pharmaceutical products is necessary to maintain quality throughout the shelf life of a sterile drug product. Container closure integrity testing has routinely been used to evaluate closure integrity during product development and production line qualification of prefilled syringes, vials, and devices. However, container closure integrity testing

  5. 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.

  6. 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.

  7. 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).

  8. 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. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. UV-Vis spectrophotometry of quinone flow battery electrolyte for in situ monitoring and improved electrochemical modeling of potential and quinhydrone formation.

    PubMed

    Tong, Liuchuan; Chen, Qing; Wong, Andrew A; Gómez-Bombarelli, Rafael; Aspuru-Guzik, Alán; Gordon, Roy G; Aziz, Michael J

    2017-12-06

    Quinone-based aqueous flow batteries provide a potential opportunity for large-scale, low-cost energy storage due to their composition from earth abundant elements, high aqueous solubility, reversible redox kinetics and their chemical tunability such as reduction potential. In an operating flow battery utilizing 9,10-anthraquinone-2,7-disulfonic acid, the aggregation of an oxidized quinone and a reduced hydroquinone to form a quinhydrone dimer causes significant variations from ideal solution behavior and of optical absorption from the Beer-Lambert law. We utilize in situ UV-Vis spectrophotometry to establish (a), quinone, hydroquinone and quinhydrone molar attenuation profiles and (b), an equilibrium constant for formation of the quinhydrone dimer (K QHQ ) ∼ 80 M -1 . We use the molar optical attenuation profiles to identify the total molecular concentration and state of charge at arbitrary mixtures of quinone and hydroquinone. We report density functional theory calculations to support the quinhydrone UV-Vis measurements and to provide insight into the dimerization conformations. We instrument a quinone-bromine flow battery with a Pd-H reference electrode in order to demonstrate how complexation in both the negative (quinone) and positive (bromine) electrolytes directly impacts measured half-cell and full-cell voltages. This work shows how accounting for electrolyte complexation improves the accuracy of electrochemical modeling of flow battery electrolytes.

  10. Multiplexed absorption tomography with calibration-free wavelength modulation spectroscopy

    SciTech Connect

    Cai, Weiwei; Kaminski, Clemens F., E-mail: cfk23@cam.ac.uk

    2014-04-14

    We propose a multiplexed absorption tomography technique, which uses calibration-free wavelength modulation spectroscopy with tunable semiconductor lasers for the simultaneous imaging of temperature and species concentration in harsh combustion environments. Compared with the commonly used direct absorption spectroscopy (DAS) counterpart, the present variant enjoys better signal-to-noise ratios and requires no baseline fitting, a particularly desirable feature for high-pressure applications, where adjacent absorption features overlap and interfere severely. We present proof-of-concept numerical demonstrations of the technique using realistic phantom models of harsh combustion environments and prove that the proposed techniques outperform currently available tomography techniques based on DAS.

  11. High temperature measurement of water vapor absorption

    NASA Technical Reports Server (NTRS)

    Keefer, Dennis; Lewis, J. W. L.; Eskridge, Richard

    1985-01-01

    An investigation was undertaken to measure the absorption coefficient, at a wavelength of 10.6 microns, for mixtures of water vapor and a diluent gas at high temperature and pressure. The experimental concept was to create the desired conditions of temperature and pressure in a laser absorption wave, similar to that which would be created in a laser propulsion system. A simplified numerical model was developed to predict the characteristics of the absorption wave and to estimate the laser intensity threshold for initiation. A non-intrusive method for temperature measurement utilizing optical laser-beam deflection (OLD) and optical spark breakdown produced by an excimer laser, was thoroughly investigated and found suitable for the non-equilibrium conditions expected in the wave. Experiments were performed to verify the temperature measurement technique, to screen possible materials for surface initiation of the laser absorption wave and to attempt to initiate an absorption wave using the 1.5 kW carbon dioxide laser. The OLD technique was proven for air and for argon, but spark breakdown could not be produced in helium. It was not possible to initiate a laser absorption wave in mixtures of water and helium or water and argon using the 1.5 kW laser, a result which was consistent with the model prediction.

  12. Determination of Se in soil samples using the proton induced X-ray emission technique

    NASA Astrophysics Data System (ADS)

    Cruvinel, Paulo E.; Flocchini, Robert G.

    1993-04-01

    An alternative method for the direct determination of total Se in soil samples is presented. A large number of trace elements is present in soil at concentration values in the range of part per billion and tenths of parts of million. The most common are the trace elements of Al, Si, K, Ca, Ti, V, Cr, Fe, Cu, Zn, Br, Rb, Mo, Cd and Pb. As for biological samples many of these elements are of great importance for the nutrition of plants, while others are toxic and others have an unknown role. Selenium is an essential micronutrient for humans and animals but it is also known that in certain areas Se deficiency or toxicity has caused endemic disease to livestock and humans through the soil-plant-animal linkage. In this work the suitability of the proton induced X-ray emission (PIXE) technique as a fast and nondestructive technique useful to measure total the Se content in soil samples is demonstrated. To validate the results a comparison of data collected using the conventional atomic absorption spectrophotometry (AAS) method was performed.

  13. Tracer techniques for urine volume determination and urine collection and sampling back-up system

    NASA Technical Reports Server (NTRS)

    Ramirez, R. V.

    1971-01-01

    The feasibility, functionality, and overall accuracy of the use of lithium were investigated as a chemical tracer in urine for providing a means of indirect determination of total urine volume by the atomic absorption spectrophotometry method. Experiments were conducted to investigate the parameters of instrumentation, tracer concentration, mixing times, and methods for incorporating the tracer material in the urine collection bag, and to refine and optimize the urine tracer technique to comply with the Skylab scheme and operational parameters of + or - 2% of volume error and + or - 1% accuracy of amount of tracer added to each container. In addition, a back-up method for urine collection and sampling system was developed and evaluated. This back-up method incorporates the tracer technique for volume determination in event of failure of the primary urine collection and preservation system. One chemical preservative was selected and evaluated as a contingency chemical preservative for the storage of urine in event of failure of the urine cooling system.

  14. Detection of bacterial growth by gas absorption.

    PubMed

    Waters, J R

    1992-05-01

    When 24 different aerobic organisms were grown in a shaken culture, all were found to first absorb gas from the headspace. In a rudimentary medium, such as tryptic soy broth, 16 of the 24 organisms did not produce gas following the initial gas absorption. We have developed a simple, noninvasive method for detecting both gas absorption and production in multiple culture vials. The time to positivity was compared with that obtained by the BACTEC 460 blood culture system. For nearly all of these organisms, there was no difference. For some of those organisms that did not produce gas, e.g. Staphylococcus epidermidis, Moraxella osloensis, and Neisseria meningitidis, detection by gas absorption was a few hours faster. Gas absorption appears to be a promising technique for a new automated blood culture system because of its simplicity and because medium without special additives can be used to detect organisms that do not produce gas.

  15. Compounds affecting cholesterol absorption

    NASA Technical Reports Server (NTRS)

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

  16. 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.

  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. Laser Atmospheric Absorption Studies.

    DTIC Science & Technology

    1977-05-01

    A. Modification of Commercial C09 Laser 50 B. CW HF/DF Laser System * 53 C. Microcomputer Data Link 55 D . Fourier Transform...improved accuracy are used [5]. c. The absorption coefficient is listed for each absorbing species separately which some codes require. d . A super...series of water vapor absorption measurements was planned. The results of the first four lines studied are presented here in Figures 33a- d . Figure

  19. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R [Albuquerque, NM; Reed, Scott T [Albuquerque, NM; Ashley, Carol S [Albuquerque, NM; Martinez, F Edward [Horseheads, NY

    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.

  20. Solar selective absorption coatings

    DOEpatents

    Mahoney, Alan R [Albuquerque, NM; Reed, Scott T [Albuquerque, NM; Ashley, Carol S [Albuquerque, NM; Martinez, F Edward [Horseheads, NY

    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.

  1. Absorption fluids data survey

    NASA Astrophysics Data System (ADS)

    Macriss, R. A.; Zawacki, T. S.

    Development of improved data for the thermodynamic, transport and physical properties of absorption fluids were studied. A specific objective of this phase of the study is to compile, catalog and coarse screen the available US data of known absorption fluid systems and publish it as a first edition document to be distributed to manufacturers, researchers and others active in absorption heat pump activities. The methodology and findings of the compilation, cataloguing and coarse screening of the available US data on absorption fluid properties and presents current status and future work on this project are summarized. Both in house file and literature searches were undertaken to obtain available US publications with pertinent physical, thermodynamic and transport properties data for absorption fluids. Cross checks of literature searches were also made, using available published bibliographies and literature review articles, to eliminate secondary sources for the data and include only original sources and manuscripts. The properties of these fluids relate to the liquid and/or vapor state, as encountered in normal operation of absorption equipment employing such fluids, and to the crystallization boundary of the liquid phase, where applicable. The actual data were systematically classified according to the type of fluid and property, as well as temperature, pressure and concentration ranges over which data were available. Data were sought for 14 different properties: Vapor-Liquid Equilibria, Crystallization Temperature, Corrosion Characteristics, Heat of Mixing, Liquid-Phase-Densities, Vapor-Liquid-Phase Enthalpies, Specific Heat, Stability, Viscosity, Mass Transfer Rate, Heat Transfer Rate, Thermal Conductivity, Flammability, and Toxicity.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Developments of Si-PIN detectors for Continuous Spectro-photometry of Black Holes (CSPOB)

    SciTech Connect

    Bhoumik, Debashis; Mondal, Shyamal; Chakrabarti, S. K.

    2008-10-08

    The goal of the proposed small-satellite mission named Continuous Spectro-Photometry of Black holes (CSPOB) is to observe a given galactic black hole candidate for several months continuously or almost continuously. In the former case, two identical satellites are required, while one satellite is sufficient if we employ one satellite. Such an observation from 0.5keV to 30keV should answer several questions regarding the spectral and timing properties of accretion processes. In particular, on the origin of the sub-Keplerian component of the accretion flow which is observed in many black hole candidates. We present preliminary results on the development of X-ray detectorsmore » based on Hamamatsu made Si-PIN Photodiodes at our laboratory.« less

  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. A methodological approach to study the stability of selected watercolours for painting reintegration, through reflectance spectrophotometry, Fourier transform infrared spectroscopy and hyperspectral imaging.

    PubMed

    Pelosi, Claudia; Capobianco, Giuseppe; Agresti, Giorgia; Bonifazi, Giuseppe; Morresi, Fabio; Rossi, Sara; Santamaria, Ulderico; Serranti, Silvia

    2018-06-05

    The aim of this work is to investigate the stability to simulated solar radiation of some paintings samples through a new methodological approach adopting non-invasive spectroscopic techniques. In particular, commercial watercolours and iron oxide based pigments were used, these last ones being prepared for the experimental by gum Arabic in order to propose a possible substitute for traditional reintegration materials. Reflectance spectrophotometry in the visible range and Hyperspectral Imaging in the short wave infrared were chosen as non-invasive techniques for evaluation the stability to irradiation of the chosen pigments. These were studied before and after artificial ageing procedure performed in Solar Box chamber under controlled conditions. Data were treated and elaborated in order to evaluate the sensitivity of the chosen techniques in identifying the variations on paint layers, induced by photo-degradation, before they could be observed by eye. Furthermore a supervised classification method for monitoring the painted surface changes adopting a multivariate approach was successfully applied. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. Signs of strong Na and K absorption in the transmission spectrum of WASP-103b

    NASA Astrophysics Data System (ADS)

    Lendl, M.; Cubillos, P. E.; Hagelberg, J.; Müller, A.; Juvan, I.; Fossati, L.

    2017-09-01

    Context. Transmission spectroscopy has become a prominent tool for characterizing the atmospheric properties on close-in transiting planets. Recent observations have revealed a remarkable diversity in exoplanet spectra, which show absorption signatures of Na, K and H2O, in some cases partially or fully attenuated by atmospheric aerosols. Aerosols (clouds and hazes) themselves have been detected in the transmission spectra of several planets thanks to wavelength-dependent slopes caused by the particles' scattering properties. Aims: We present an optical 550-960 nm transmission spectrum of the extremely irradiated hot Jupiter WASP-103b, one of the hottest (2500 K) and most massive (1.5 MJ) planets yet to be studied with this technique. WASP-103b orbits its star at a separation of less than 1.2 times the Roche limit and is predicted to be strongly tidally distorted. Methods: We have used Gemini/GMOS to obtain multi-object spectroscopy throughout three transits of WASP-103b. We used relative spectrophotometry and bin sizes between 20 and 2 nm to infer the planet's transmission spectrum. Results: We find that WASP-103b shows increased absorption in the cores of the alkali (Na, K) line features. We do not confirm the presence of any strong scattering slope as previously suggested, pointing towards a clear atmosphere for the highly irradiated, massive exoplanet WASP-103b. We constrain the upper boundary of any potential cloud deck to reside at pressure levels above 0.01 bar. This finding is in line with previous studies on cloud occurrence on exoplanets which find that clouds dominate the transmission spectra of cool, low surface gravity planets while hot, high surface gravity planets are either cloud-free, or possess clouds located below the altitudes probed by transmission spectra. The spectrophotometric time series data are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc

  18. Single-shot measurement of nonlinear absorption and nonlinear refraction.

    PubMed

    Jayabalan, J; Singh, Asha; Oak, Shrikant M

    2006-06-01

    A single-shot method for measurement of nonlinear optical absorption and refraction is described and analyzed. A spatial intensity variation of an elliptical Gaussian beam in conjugation with an array detector is the key element of this method. The advantages of this single-shot technique were demonstrated by measuring the two-photon absorption and free-carrier absorption in GaAs as well as the nonlinear refractive index of CS2 using a modified optical Kerr setup.

  19. 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.

  20. 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.

  1. Geant4 simulations of the absorption of photons in CsI and NaI produced by electrons with energies up to 4 MeV and their application to precision measurements of the β-energy spectrum with a calorimetric technique

    NASA Astrophysics Data System (ADS)

    Huyan, X.; Naviliat-Cuncic, O.; Voytas, P.; Chandavar, S.; Hughes, M.; Minamisono, K.; Paulauskas, S. V.

    2018-01-01

    The yield of photons produced by electrons slowing down in CsI and NaI was studied with four electromagnetic physics constructors included in the Geant4 toolkit. The subsequent absorption of photons in detector geometries used for measurements of the β spectrum shape was also studied with a focus on the determination of the absorption fraction. For electrons with energies in the range 0.5-4 MeV, the relative photon yields determined with the four Geant4 constructors differ at the level of 10-2 in amplitude and the relative absorption fractions differ at the level of 10-4 in amplitude. The differences among constructors enabled the estimation of the sensitivity to Geant4 simulations for the measurement of the β energy spectrum shape in 6He decay using a calorimetric technique with ions implanted in the active volume of detectors. The size of the effect associated with photons escaping the detectors was quantified in terms of a slope which, on average, is respectively - 5 . 4 %/MeV and - 4 . 8 %/MeV for the CsI and NaI geometries. The corresponding relative uncertainties as determined from the spread of results obtained with the four Geant4 constructors are 0.0067 and 0.0058.

  2. Photo-induced intersubband absorption in {Si}/{SiGe} quantum wells

    NASA Astrophysics Data System (ADS)

    Boucaud, P.; Gao, L.; Visocekas, F.; Moussa, Z.; Lourtioz, J.-M.; Julien, F. H.; Sagnes, I.; Campidelli, Y.; Badoz, P.-A.; Vagos, P.

    1995-12-01

    We have investigated photo-induced intersubband absorption in the valence band of {Si}/{SiGe} quantum wells. Carriers are optically generated in the quantum wells using an argon ion laser. The resulting infrared absorption is probed with a step-scan Fourier transform infrared spectrometer. The photo-induced infrared absorption in SiGe quantum wells is dominated by two contributions: the free carrier absorption, which is similar to bulk absorption in a uniformly doped SiGe layer, and the valence subband absorption in the quantum wells. Both p- and s-polarized intersubband absorptions are measured. We have observed that the photo-induced intersubband absorption in doped samples is shifted to lower energy as compared to direct intersubband absorption. This absorption process is attributed to carriers away from the Brillouin zone center. We show that the photo-induced technique is appropriate to study valence band mixing effects and their influence on intersubband absorption.

  3. Colour analysis of the equine endometrium: comparison of spectrophotometry and computer-assisted analysis of photographs within the L*a*b* colour space system.

    PubMed

    Neuhauser, S; Handler, J

    2013-09-01

    The aims of this study were to compare two different methods of quantifying the colour of the luminal surface of the equine endometrium and to relate the results to histopathological evidence of inflammation and fibrosis. The mucosal surfaces of 17 equine uteri obtained from an abattoir were assessed using a spectrophotometer and by computer-assisted analysis of photographs. Values were converted into L(*)a(*)b(*) colour space. Although there was significant correlation between the two methods of quantification, variations in 'brightness', 'red' and 'yellow' values were noted. Within a given uterus, measurements using the spectrophotometer did not differ significantly. Using photographic analysis, brightness differed between horns, although no differences in chromaticity were found. Histopathological classification of changes within endometria corresponded to measured differences in colour. Extensive fibrosis was associated with increased brightness and decreased chromaticity using both methods. Inflammation correlated with reduced chromaticity, when measured by spectrophotometry, and with reduced brightness and yellow values, when assessed photographically. For this technique to gain wider acceptance as a diagnostic tool, e.g. for the endoscopic evaluation of uterine mucosae in vivo, standardised illumination techniques will be required so that colours can be compared and interpreted accurately. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. 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…

  5. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C.P.; Rockwood, S.D.; Jensen, R.J.; Lyman, J.L.; Aldridge, J.P. III.

    1987-04-07

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO[sub 2] laser light may be used to highly enrich [sup 34]S in natural SF[sub 6] and [sup 11]B in natural BCl[sub 3]. 8 figs.

  6. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

    1987-01-01

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

  7. Laser isotope separation by multiple photon absorption

    DOEpatents

    Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

    1977-01-01

    Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, in the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

  8. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. 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

  10. Acoustic Absorption in Porous Materials

    NASA Technical Reports Server (NTRS)

    Kuczmarski, Maria A.; Johnston, James C.

    2011-01-01

    An understanding of both the areas of materials science and acoustics is necessary to successfully develop materials for acoustic absorption applications. This paper presents the basic knowledge and approaches for determining the acoustic performance of porous materials in a manner that will help materials researchers new to this area gain the understanding and skills necessary to make meaningful contributions to this field of study. Beginning with the basics and making as few assumptions as possible, this paper reviews relevant topics in the acoustic performance of porous materials, which are often used to make acoustic bulk absorbers, moving from the physics of sound wave interactions with porous materials to measurement techniques for flow resistivity, characteristic impedance, and wavenumber.

  11. UV laser long-path absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Dorn, Hans-Peter; Brauers, Theo; Neuroth, Rudolf

    1994-01-01

    Long path Differential Optical Absorption Spectroscopy (DOAS) using a picosecond UV laser as a light source was developed in our institute. Tropospheric OH radicals are measured by their rotational absorption lines around 308 nm. The spectra are obtained using a high resolution spectrograph. The detection system has been improved over the formerly used optomechanical scanning device by application of a photodiode array which increased the observed spectral range by a factor of 6 and which utilizes the light much more effectively leading to a considerable reduction of the measurement time. This technique provides direct measurements of OH because the signal is given by the product of the absorption coefficient and the OH concentration along the light path according to Lambert-Beers law. No calibration is needed. Since the integrated absorption coefficient is well known the accuracy of the measurement essentially depends on the extent to which the OH absorption pattern can be detected in the spectra. No interference by self generated OH radicals in the detection lightpath has been observed. The large bandwidth (greater than 0.15 nm) and the high spectral resolution (1.5 pm) allows absolute determination of interferences by other trace gas absorptions. The measurement error is directly accessible from the absorption-signal to baseline-noise ratio in the spectra. The applicability of the method strongly depends on visibility. Elevated concentrations of aerosols lead to considerable attenuation of the laser light which reduces the S/N-ratio. In the moderately polluted air of Julich, where we performed a number of OH measurement spectra. In addition absorption features of unidentified species were frequently detected. A quantitative deconvolution even of the known species is not easy to achieve and can leave residual structures in the spectra. Thus interferences usually increase the noise and deteriorate the OH detection sensitivity. Using diode arrays for sensitive

  12. 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

  13. 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.

  14. X-ray absorption spectroscopy: EXAFS (Extended X-ray Absorption Fine Structure) and XANES (X-ray Absorption Near Edge Structure)

    SciTech Connect

    Alp, E.E.; Mini, S.M.; Ramanathan, M.

    1990-04-01

    The x-ray absorption spectroscopy (XAS) had been an essential tool to gather spectroscopic information about atomic energy level structure in the early decades of this century. It has also played an important role in the discovery and systematization of rare-earth elements. The discovery of synchrotron radiation in 1952, and later the availability of broadly tunable synchrotron based x-ray sources have revitalized this technique since the 1970's. The correct interpretation of the oscillatory structure in the x-ray absorption cross-section above the absorption edge by Sayers et. al. has transformed XAS from a spectroscopic tool to a structural technique. EXAFS (Extended X-raymore » Absorption Fine Structure) yields information about the interatomic distances, near neighbor coordination numbers, and lattice dynamics. An excellent description of the principles and data analysis techniques of EXAFS is given by Teo. XANES (X-ray Absorption Near Edge Structure), on the other hand, gives information about the valence state, energy bandwidth and bond angles. Today, there are about 50 experimental stations in various synchrotrons around the world dedicated to collecting x-ray absorption data from the bulk and surfaces of solids and liquids. In this chapter, we will give the basic principles of XAS, explain the information content of essentially two different aspects of the absorption process leading to EXAFS and XANES, and discuss the source and samples limitations.« less

  15. Linear absorptive dielectrics

    NASA Astrophysics Data System (ADS)

    Tip, A.

    1998-06-01

    Starting from Maxwell's equations for a linear, nonconducting, absorptive, and dispersive medium, characterized by the constitutive equations D(x,t)=ɛ1(x)E(x,t)+∫t-∞dsχ(x,t-s)E(x,s) and H(x,t)=B(x,t), a unitary time evolution and canonical formalism is obtained. Given the complex, coordinate, and frequency-dependent, electric permeability ɛ(x,ω), no further assumptions are made. The procedure leads to a proper definition of band gaps in the periodic case and a new continuity equation for energy flow. An S-matrix formalism for scattering from lossy objects is presented in full detail. A quantized version of the formalism is derived and applied to the generation of Čerenkov and transition radiation as well as atomic decay. The last case suggests a useful generalization of the density of states to the absorptive situation.

  16. 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.

  17. Deep echelle spectrophotometry of S 311, a Galactic HII region located outside the solar circle

    NASA Astrophysics Data System (ADS)

    García-Rojas, J.; Esteban, C.; Peimbert, A.; Peimbert, M.; Rodríguez, M.; Ruiz, M. T.

    2005-09-01

    We present echelle spectrophotometry of the Galactic HII region S 311. The data have been taken with the Very Large Telescope Ultraviolet-Visual Echelle Spectrograph in the 3100-10400 Årange. We have measured the intensities of 263 emission lines; 178 are permitted lines of H0, D0 (deuterium), He0, C0, C+, N0, N+, O0, O+, S+, Si0, Si+, Ar0 and Fe0; some of them are produced by recombination and others mainly by fluorescence. Physical conditions have been derived using different continuum- and line-intensity ratios. We have derived He+, C++ and O++ ionic abundances from pure recombination lines as well as abundances from collisionally excited lines for a large number of ions of different elements. We have obtained consistent estimations of t2 applying different methods. We have found that the temperature fluctuations paradigm is consistent with the Te(HeI) versus Te(HI) relation for HII regions, in contrast with what has been found for planetary nebulae. We report the detection of deuterium Balmer lines up to Dδ in the blue wings of the hydrogen lines, whose excitation mechanism seems to be continuum fluorescence.

  18. 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.

  19. Feasibility of spectro-photometry in X-rays (SPHINX) from the moon

    NASA Astrophysics Data System (ADS)

    Sarkar, Ritabrata; Chakrabarti, Sandip Kumar

    2010-08-01

    Doing space Astronomy on lunar surface has several advantages. We present here feasibility of an All Sky Monitoring Payload for Spectro-photometry in X-rays (SPHINX) which can be placed on a lander on the moon or in a space craft orbiting around the moon. The Si-PIN photo-diodes and CdTe crystals are used to detect solar flares, bright gamma bursts, soft gamma-ray repeaters from space and also X-ray fluorescence (XRF) from lunar surface. We present the complete Geant4 simulation to study the feasibility of such an instrument in presence of Cosmic Diffused X-Ray Background (CDXRB). We find that the signal to noise ratio is sufficient for moderate to bright GRBs (above 5 keV), for the quiet sun (up to 100 keV), solar flares, soft gamma-ray repeaters, X-ray Fluorescence (XRF) of lunar surface etc. This is a low-cost system which is capable of performing multiple tasks while stationed at the natural satellite of our planet.

  20. Evaluation of Biologically Active Compounds from Calendula officinalis Flowers using Spectrophotometry

    PubMed Central

    2012-01-01

    Background This study aimed to quantify the active biological compounds in C. officinalis flowers. Based on the active principles and biological properties of marigolds flowers reported in the literature, we sought to obtain and characterize the molecular composition of extracts prepared using different solvents. The antioxidant capacities of extracts were assessed by using spectrophotometry to measure both absorbance of the colorimetric free radical scavenger 2,2-diphenyl-1-picrylhydrazyl (DPPH) as well as the total antioxidant potential, using the ferric reducing power (FRAP) assay. Results Spectrophotometric assays in the ultraviolet-visible (UV-VIS) region enabled identification and characterization of the full range of phenolic and flavonoids acids, and high-performance liquid chromatography (HPLC) was used to identify and quantify phenolic compounds (depending on the method of extraction). Methanol ensured more efficient extraction of flavonoids than the other solvents tested. Antioxidant activity in methanolic extracts was correlated with the polyphenol content. Conclusions The UV-VIS spectra of assimilator pigments (e.g. chlorophylls), polyphenols and flavonoids extracted from the C. officinalis flowers consisted in quantitative evaluation of compounds which absorb to wavelengths broader than 360 nm. PMID:22540963

  1. Infrared Photometry and Spectrophotometry of Supernova 1987A - Part Two - 1987NOV to 1991MAR Observations

    NASA Astrophysics Data System (ADS)

    Bouchet, P.; Danziger, I. J.

    1993-06-01

    We present the infrared (1-20 micron) observations of SN 1987A obtained at ESO La Silla between 29 October 1987 and 27 March 1991 (day 1493); photometry and narrow band CVF spectrophotometry (λ/{DELTA}λ ~ 60) were acquired during that period. The infrared light curves and the spectra are shown and discussed. The spectral energy distribution is dominated by an increasing IR excess after day 530 (beyond 3.5 microns) due to the presence of dust in the envelope which was first discovered by its spectroscopic signature. We show that dust is still present at least until day ~1400, and that the two zone model for the expanding envelope, suggested from the visible spectra obtained at ESO, can account for the observed changes in the near-infrared colours in the period days 530-560. Hydrogen lines, observed in the spectrum from the very beginning, are present until day 1109 (although Brγ is hardly noticeable on the 9 March 1990 spectrum) and we describe the variations of their intensities throughout our monitoring period. Attention is drawn to the presence of CO emission observed until November 1988, and to the evolution of cobalt through the observation of the fine structure line of [Co II] at 10.52 microns. The temporal behaviour of the emission lines due to [Ni I] 3.12 microns and [Si I] + [Fe II] 1.644 microns are also shown.

  2. Quality control of test iodine in urine by spectrophotometry UV-Vis

    NASA Astrophysics Data System (ADS)

    Huda, Thorikul; Nafisah, Durotun; Kumorowulan, Suryati; Lestari, Sri

    2017-12-01

    A quality control of iodine test in with UV-Vis spectrophotometry has been done. The purpose of this research is to find out whether the test results of samples conducted by Clinical Office of Research and Development Of GAKI (BP2GAKI) laboratory are still controlled, feasible and reliable, and still consistent over time, as indicated by the control chart. Quality control parameters are linearity, precision, accuracy, limit of detection, and limit of quantification. Based on the quality control that has been done, obtained linearity (r)= -0.9974, the detection limit and the limit of quantitation are respectively 2.26 µg/L and 7.54 µg/L, while the accuracy is calculated by %recovery and precision with value % RSD are 97.4161% and 1.7136% respectively. The quality control of iodine test in urine using the control chart shows excellent or stable results for 30 days and no variation of the results is very different for each day.

  3. Cryptic gentes revealed in pallid cuckoos Cuculus pallidus using reflectance spectrophotometry

    PubMed Central

    Starling, M; Heinsohn, R; Cockburn, A; Langmore, N.E

    2006-01-01

    Many cuckoo species lay eggs that match those of their hosts, which can significantly reduce rejection of their eggs by the host species. However, egg mimicry is problematic for generalist cuckoos that parasitize several host species with different egg types. Some generalist cuckoos have overcome this problem by evolving several host-specific races (gentes), each with its own, host-specific egg type. It is unknown how generalist cuckoos lacking gentes are able to avoid egg rejection by hosts. Here we use reflectance spectrophotometry (300–700 nm) on museum egg collections to test for host-specific egg types in an Australian generalist cuckoo reported to have a single egg type. We show that the colour of pallid cuckoo (Cuculus pallidus) eggs differed between four host species, and that their eggs closely mimicked the eggs of the host they parasitized. These results reveal that pallid cuckoos have host-specific egg types that have not been detected by human observation, and indicate that gentes could be more common than previously realized. PMID:16822754

  4. [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.

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

    PubMed Central

    Cherry, M I; Bennett, A T

    2001-01-01

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

  6. 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). Copyright © 2014 Elsevier B.V. All rights reserved.

  7. 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.

  8. A NEW CONCEPT FOR SPECTROPHOTOMETRY OF EXOPLANETS WITH SPACE-BORNE TELESCOPES

    SciTech Connect

    Matsuo, Taro; Itoh, Satoshi; Shibai, Hiroshi

    2016-06-01

    We propose a new concept for the spectral characterization of transiting exoplanets with future space-based telescopes. This concept, called densified pupil spectroscopy, allows us to perform high, stable spectrophotometry against telescope pointing jitter and deformation of the primary mirror. This densified pupil spectrometer comprises the following three roles: division of a pupil into a number of sub-pupils, densification of each sub-pupil, and acquisition of the spectrum of each sub-pupil with a conventional spectrometer. Focusing on the fact that the divided and densified sub-pupil can be treated as a point source, we discovered that a simplified spectrometer allows us to acquiremore » the spectra of the densified sub-pupils on the detector plane−an optical conjugate with the primary mirror−by putting the divided and densified sub-pupils on the entrance slit of the spectrometer. The acquired multiple spectra are not principally moved on the detector against low-order aberrations such as the telescope pointing jitter and any deformation of the primary mirror. The reliability of the observation result is also increased by statistically treating them. Our numerical calculations show that because this method suppresses the instrumental systematic errors down to 10 ppm under telescopes with modest pointing accuracy, next generation space telescopes with more than 2.5 m diameter potentially provide opportunities to characterize temperate super-Earths around nearby late-type stars through the transmission spectroscopy and secondary eclipse.« less

  9. Comments on a Method to Measure Sucralose Using UV Photodegradation Followed by UV Spectrophotometry.

    PubMed

    Fang, Te; Andrews, Susan A; Hofmann, Ron

    2017-05-01

    A simple and quick method to measure sucralose in aqueous solution at concentrations in the order of 0.1-1.2 g·L-1 proposed by Idris et al. uses UV irradiation prior to UV spectrophotometry. The photolysis of sucralose forms a photoactive compound characterized by maximum absorbance at approximately 270 nm. The conditions required for sucralose photolysis, however, had not been completely reported. In this work, the procedure described by Idris et al. was replicated using a low-pressure UV lamp to irradiate sucralose samples with a wider range of initial concentrations (0.04-10 g·L-1) with known fluences. It was determined that care must be taken to ensure that the same fluence is applied for both calibration and measurement steps because the absorbance of the sucralose photolysis product is a function of the applied fluence. The way the samples are irradiated also has an impact on the results in that the method exhibits a greater linear range if an apparatus is used that maximizes the fluence rate (e.g., by placing samples closer to the UV source or using a higher-intensity lamp).

  10. A System for Photon-Counting Spectrophotometry of Prompt Optical Emission from Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Vestrand, W. T.; Albright, K.; Casperson, D.; Fenimore, E.; Ho, C.; Priedhorsky, W.; White, R.; Wren, J.

    2003-04-01

    With the launch of HETE-2 and the coming launch of the Swift satellite, there will be many new opportunities to study the physics of the prompt optical emission with robotic ground-based telescopes. Time-resolved spectrophotometry of the rapidly varying optical emission is likely to be a rich area for discovery. We describe a program to apply state-of-the-art photon-counting imaging technology to the study of prompt optical emission from gamma-ray bursts. The Remote Ultra-Low Light Imaging (RULLI) project at Los Alamos National Laboratory has developed an imaging sensor which employs stacked microchannel plates and a crossed delay line readout with 200 picosecond photon timing to measure the time of arrival and positions for individual optical photons. RULLI detectors, when coupled with a transmission grating having 300 grooves/mm, can make photon-counting spectroscopic observations with spectral resolution that is an order of magnitude greater and temporal resolution three orders of magnitude greater than the most capable photon-counting imaging detectors that have been used for optical astronomy.

  11. Iodine absorption cells quality evaluation methods

    NASA Astrophysics Data System (ADS)

    Hrabina, Jan; Zucco, Massimo; Holá, Miroslava; Šarbort, Martin; Acef, Ouali; Du-Burck, Frédéric; Lazar, Josef; Číp, Ondřej

    2016-12-01

    The absorption cells represent an unique tool for the laser frequency stabilization. They serve as irreplaceable optical frequency references in realization of high-stable laser standards and laser sources for different brands of optical measurements, including the most precise frequency and dimensional measurement systems. One of the most often used absorption media covering visible and near IR spectral range is molecular iodine. It offers rich atlas of very strong and narrow spectral transitions which allow realization of laser systems with ultimate frequency stabilities in or below 10-14 order level. One of the most often disccussed disadvantage of the iodine cells is iodine's corrosivity and sensitivity to presence of foreign substances. The impurities react with absorption media and cause spectral shifts of absorption spectra, spectral broadening of the transitions and decrease achievable signal-to-noise ratio of the detected spectra. All of these unwanted effects directly influence frequency stability of the realized laser standard and due to this fact, the quality of iodine cells must be precisely controlled. We present a comparison of traditionally used method of laser induced fluorescence (LIF) with novel technique based on hyperfine transitions linewidths measurement. The results summarize advantages and drawbacks of these techniques and give a recommendation for their practical usage.

  12. 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)

  13. Rapidly variable relatvistic absorption

    NASA Astrophysics Data System (ADS)

    Parker, M.; Pinto, C.; Fabian, A.; Lohfink, A.; Buisson, D.; Alston, W.; Jiang, J.

    2017-10-01

    I will present results from the 1.5Ms XMM-Newton observing campaign on the most X-ray variable AGN, IRAS 13224-3809. We find a series of nine absorption lines with a velocity of 0.24c from an ultra-fast outflow. For the first time, we are able to see extremely rapid variability of the UFO features, and can link this to the X-ray variability from the inner accretion disk. We find a clear flux dependence of the outflow features, suggesting that the wind is ionized by increasing X-ray emission.

  14. 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.

  15. Intestinal absorption of copper: influence of carbohydrates.

    PubMed

    Wapnir, R A; Balkman, C

    1992-02-01

    Macronutrients can modulate the intestinal absorption of trace elements by binding the metal or altering mucosal function. We investigated whether certain simple and complex carbohydrates modify copper (Cu) absorption, using an in vivo perfusion technique in the rat. Corn syrup solids, which contain a mixture of glucose polymers of diverse length, added at either 20 or 50 mosm/kg enhanced Cu absorption from a 31.5 microM (2 mg/liter) Cu solution (128 +/- 11 and 130 +/- 11 pmol/min x cm, respectively, vs 101 +/- 4 pmol/min x cm, P less than 0.05, in the absence of carbohydrate). This was concomitant with a stimulation of net water absorption (1.05 +/- 0.08 and 0.84 +/- 0.08 microliter/min x cm, respectively, vs 0.63 +/- 0.02 microliter/min x cm with no carbohydrate, P less than 0.05). Glucose, fructose, lactose, or sucrose had no influence on Cu absorption, although they altered water exchanges, an effect attributable to a reduction of the outflow component of fluid recirculation. Low concentrations of lactose resulted in a greater accumulation of Cu in the intestinal mucosa (8.75 +/- 0.71 micrograms/g vs 5.77 +/- 0.68 micrograms/g for controls, P less than 0.05). Hence, solutes that moderately stimulate mucosa-to-serosa fluid influx in a progressive manner, such as glucose polymers, may contribute to functionally increase Cu absorption. Conversely, conditions which tend to reduce water inflow or increase water outflow across the small intestinal mucosa, as may occur with high lactose diets or in cases of chronic diarrhea, may have negative effects.

  16. Calcium absorption is not increased by caseinophosphopeptides.

    PubMed

    Teucher, Birgit; Majsak-Newman, Gosia; Dainty, Jack R; McDonagh, David; FitzGerald, Richard J; Fairweather-Tait, Susan J

    2006-07-01

    One of the suggested health benefits of caseinophosphopeptides (CPPs) is their ability to enhance calcium absorption. This possibility is based on the assumption that they resist proteolysis in the upper gastrointestinal tract and maintain calcium in a soluble form at alkaline pH in the distal ileum. The effects of CPP-enriched preparations (containing candidate functional food ingredients) on calcium absorption from a calcium lactate drink were tested. A randomized crossover trial was undertaken in 15 adults in whom we measured the absorption of calcium from a calcium lactate drink (drink A: 400 mg Ca as lactate) and 2 preparations enriched with forms of CPP (1.7 g each; drinks B and C). Both drinks B and C contained 400 mg Ca as calcium lactate plus approximately 100 mg CPP-derived calcium). Each volunteer received the 3 drinks in random order. Absorption was measured by the dual-label calcium stable-isotope technique. The quantity of calcium absorbed was significantly lower from drink A (103 mg) than from drink B (117 mg; P = 0.012) or drink C (121 mg; P = 0.002), which indicated a positive effect of the CPPs. However, because the CPP preparations contributed additional calcium besides that found in the calcium lactate (drink A), fractional absorption of calcium from drink B (23%) was slightly but significantly (P = 0.015) lower than that from drink A (26%). The differences in calcium absorption are unlikely to have any biological significance. CPPs are unsuitable as candidate ingredients for functional foods that are designed to deliver improved calcium nutrition.

  17. 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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Noninvasive Measurement of Hemoglobin Using Spectrophotometry: Is it Useful for the Critically Ill Child?

    PubMed

    Akyildiz, Basak

    2018-01-01

    This study compared the accuracy of noninvasively measuring hemoglobin using spectrophotometry (SpHb) with a pulse CO-oximeter and laboratory hemoglobin (Hb) measurements. A total of 345 critically ill children were included prospectively. Age, sex, and factors influencing the reliabilityof SpHb such as SpO2, heart rate, perfusion index (PI), and vasoactive inotropic score were recorded. SpHb measurements were recorded during the blood draw and compared with the Hb measurement. Thirteen patients (low PI in 9 patients and no available Hb in 4 patients) were excluded and 332 children were eligible for final analysis. The mean Hb was 8.71±1.49 g/dL (range, 5.9 to 12 g/dL) and the mean SpHb level was 9.55±1.53 g/dL (range, 6 to 14.2 g/dL). The SpHb bias was 0.84±0.86,with the limits of agreement ranging from -2.5 to 0.9 g/dL. The difference between Hb and SpHb was >1.5 g/dL for only 47 patients. Of these, 24 patients had laboratory Hb levels <7 g/dL. There was a weak positive correlation between differences and PI (r=0.349; P= 0.032). The pulse CO-oximeter is a promising tool for measuring SpHb and monitoring critically ill children. However, PI may affect these results. Additional studies investigating the reliability of the trend of continuous SpHb values compared with simultaneously measured laboratory Hb values in the same patient are warranted.

  19. Evaluating optimal superficial limb perfusion at different angles using non-invasive micro-lightguide spectrophotometry.

    PubMed

    Darmanin, Geraldine; Jaggard, Matthew; Hettiaratchy, Shehan; Nanchahal, Jagdeep; Jain, Abhilash

    2013-06-01

    It is common practice to elevate the limbs postoperatively to reduce oedema and hence optimise perfusion and facilitate rehabilitation. However, elevation may be counterproductive as it reduces the mean perfusion pressure. There are no clear data on the optimal position of the limbs even in normal subjects. The optimal position of limbs was investigated in 25 healthy subjects using a non-invasive micro-lightguide spectrophotometry system "O2C", which indirectly measures skin and superficial tissue perfusion through blood flow, oxygen saturation and relative haemoglobin concentration. We found a reduction in skin and superficial tissue blood flow of 17% (p=0.0001) on arm elevation (180° shoulder flexion) as compared to heart level and an increase in skin and superficial tissue blood flow of 25% (p=0.02) on forearm elevation of 45°. Lower limb skin and superficial tissue blood flow decreased by 15% (p=0.004) on elevation to 47 cm and by 70% on dependency (p=0.0001) compared to heart level. However, on elevation of the lower limb there was also a 28% reduction in superficial venous pooling (p=0.0001) compared to heart level. In the normal limb, the position for optimal superficial perfusion of the upper limb is with the arm placed at heart level and forearm at 45°. In the lower limb the optimal position for superficial perfusion would be at heart level. However, some degree of elevation may be useful if there is an element of venous congestion. Copyright © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  20. Testing near-infrared spectrophotometry using a liquid neonatal head phantom

    NASA Astrophysics Data System (ADS)

    Wolf, Martin; Baenziger, Oskar; Keel, Matthias; Dietz, Vera; von Siebenthal, Kurt; Bucher, Hans U.

    1998-12-01

    We constructed a liquid phantom, which mimics the neonatal head for testing near infrared spectrophotometry instruments. It consists of a spherical, 3.5 mm thick layer of silicone rubber simulating skin and bone and acts as container for a liquid solution with IntralipidTM, 60 micrometers ol/l haemoglobin and yeast. The IntralipidTM concentration was varied to test the influence of scattering on haemoglobin concentrations and tissue oxygenation determined by the Critikon 2020. The solution was oxygenated using pure oxygen and then deoxygenated by the yeast. For the instruments algorithm, we found with increasing scattering (0.5%, 1%, 1.5% and 2% IntralipidTM concentration) an increasing offset added to the oxy- (56.7, 90.8, 112.5, 145.2 micrometers ol/l respectively) and deoxyhaemoglobin (25.4, 44.3, 58.5, 65.9 micrometers ol/l) concentration causing a decreasing range (41.3, 31.3, 25.0, 22.2%) of the tissue oxygen saturation reading. However, concentration changes were quantified correctly independently of the scattering level. For an other algorithm based on the analytical solution the offsets were smaller: oxyhaemoglobin 12.2, 34.0, 53.2, 88.8 micrometers ol/l and deoxyhaemoglobin 1.6, 11.2, 22.2, 28.1 micrometers ol/l. The range of the tissue oxygen saturation reading was higher: 71.3, 55.5, 45.7, 39.4%. However, concentration changes were not quantified correctly and depended on scattering. This study demonstrates the need to develop algorithms, which take into consideration the anatomical structures.

  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. High Ultraviolet Absorption in Colloidal Gallium Nanoparticles Prepared from Thermal Evaporation

    PubMed Central

    Bravo, Iria; Catalan-Gomez, Sergio; Vázquez, Luis; Lorenzo, Encarnación; Pau, Jose Luis

    2017-01-01

    New methods for the production of colloidal Ga nanoparticles (GaNPs) are introduced based on the evaporation of gallium on expendable aluminum zinc oxide (AZO) layer. The nanoparticles can be prepared in aqueous or organic solvents such as tetrahydrofuran in order to be used in different sensing applications. The particles had a quasi mono-modal distribution with diameters ranging from 10 nm to 80 nm, and their aggregation status depended on the solvent nature. Compared to common chemical synthesis, our method assures higher yield with the possibility of tailoring particles size by adjusting the deposition time. The GaNPs have been studied by spectrophotometry to obtain the absorption spectra. The colloidal solutions exhibit strong plasmonic absorption in the ultra violet (UV) region around 280 nm, whose width and intensity mainly depend on the nanoparticles dimensions and their aggregation state. With regard to the colloidal GaNPs flocculate behavior, the water solvent case has been investigated for different pH values, showing UV-visible absorption because of the formation of NPs clusters. Using discrete dipole approximation (DDA) method simulations, a close connection between the UV absorption and NPs with a diameter smaller than ~40 nm was observed. PMID:28684687

  4. 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.

  5. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. 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, Frederic 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).

  7. Bacteria Adherence Properties of Nitrogen-Doped TiO2 Coatings by Plasma Surface Alloying Technique

    NASA Astrophysics Data System (ADS)

    Wang, Hefeng; Tang, Bin; Li, Xiuyan; Fan, Ailan

    Titanium nitride coatings on 316L stainless steel (S. S) were obtained by plasma surface alloying technique. Nitrogen-doped titanium dioxide (TiO2-xNx) was synthesized by oxidative annealing the resulted TiNx coatings in air. The reference TiO2 samples were also prepared by oxidation of sputtered Ti coatings. The as-prepared coatings were characterized by X-ray diffraction, glow discharge optical emission spectrometer (GDOES), scanning electron microscopy, X-ray hotoelectron spectroscopy and UV-Vis spectrophotometry, respectively. The bacteria adherence property of the TiO2-xNx coatings on stainless steel on the oral bacteria Streptococcus Mutans was investigated and compared with that of stainless steel by fluorescence microscopy. The mechanism of the bacteria adherence was discussed. The results show that the TiO2-xNx coatings are composed of anatase crystalline structure. SEM measurement indicates a rough surface morphology with three-dimensional homogenous protuberances after annealing treatment. Optical properties reveal an extended tailing of the absorption edge toward the visible region due to nitrogen presence. The band gap of the N-doped sample is reduced from 2.29 eV to 1.90 eV compared with the pure TiO2 one. Because of the different roughness and microstructure, the TiO2-xNx coatings inhibit the bacteria adherence.

  8. A double-tracer technique to characterize absorption, distribution, metabolism and excretion (ADME) of [14C]-basimglurant and absolute bioavailability after oral administration and concomitant intravenous microdose administration of [13C6]-labeled basimglurant in humans.

    PubMed

    Guerini, Elena; Schadt, Simone; Greig, Gerard; Haas, Ruth; Husser, Christophe; Zell, Manfred; Funk, Christoph; Hartung, Thomas; Gloge, Andreas; Mallalieu, Navita L

    2017-02-01

    1. The emerging technique of employing intravenous microdose administration of an isotope tracer concomitantly with an [ 14 C]-labeled oral dose was used to characterize the disposition and absolute bioavailability of a novel metabotropic glutamate 5 (mGlu5) receptor antagonist under clinical development for major depressive disorder (MDD). 2. Six healthy volunteers received a single 1 mg [ 12 C/ 14 C]-basimglurant (2.22 MBq) oral dose and a concomitant i.v. tracer dose of 100 μg of [ 13 C 6 ]-basimglurant. Concentrations of [ 12 C]-basimglurant and the stable isotope [ 13 C 6 ]-basimglurant were determined in plasma by a specific LC/MS-MS method. Total [ 14 C] radioactivity was determined in whole blood, plasma, urine and feces by liquid scintillation counting. Metabolic profiling was conducted in plasma, urine, blood cell pellet and feces samples. 3. The mean absolute bioavailability after oral administration (F) of basimglurant was ∼67% (range 45.7-77.7%). The major route of [ 14 C]-radioactivity excretion, primarily in form of metabolites, was in urine (mean recovery 73.4%), with the remainder excreted in feces (mean recovery 26.5%). The median t max for [ 12 C]-basimglurant after the oral administration was 0.71 h (range 0.58-1.00) and the mean terminal half-life was 77.2 ± 38.5 h. Terminal half-life for the [ 14 C]-basimglurant was 178 h indicating presence of metabolites with a longer terminal half-life. Five metabolites were identified with M1-Glucuronide as major and the others in trace amounts. There was minimal binding of drug to RBCs. IV pharmacokinetics was characterized with a mean ± SD CL of 11.8 ± 7.4 mL/h and a Vss of 677 ± 229 L. 4. The double-tracer technique used in this study allowed to simultaneously characterize the absolute bioavailability and disposition characteristics of the new oral molecular entity in a single study.

  9. MULTIMAGNON ABSORPTION IN MNF2-OPTICAL ABSORPTION SPECTRUM.

    DTIC Science & Technology

    The absorption spectrum of MnF2 at 4.2K in the 3900A region was measured in zero external fields and in high fields. Exciton lines with magnon ...sidebands are observed, accompanied by a large number of weak satellite lines. Results on the exciton and magnon absorptions are similar to those of...McClure et al. The satellite lines are interpreted as being multi- magnon absorptions, and it is possible to fit the energy of all the absorptions with

  10. Peculiarities of light absorption by spherical microcapsules

    NASA Astrophysics Data System (ADS)

    Geints, Yurii E.; Panina, Ekaterina K.; Zemlyanov, Alexander A.

    2018-04-01

    Optical radiation absorption in the poly-layer spherical microparticles simulating the inorganic/organic polyshell absorbing microcapsules is considered. With the aim of the finite-difference time-domain technique, the spatial distribution of the absorbed light power in microcapsules of various sizes and internal structure is numerically calculated. For the purpose of light absorption enhancement, we have engineered the optimal structure of a capsule consisting of a strong-refracting transparent outer coating and an absorbing layer which covers a liquid core. The proposed microcapsule prototype provides for a manifold increase in the absorbed light power density in comparison with the usual single-layer absorbing capsule. We show that for light-wavelengths-scaled microcapsules it is optimal to use a material with the refractive index larger than two as an outer shell, for example, titanium dioxide (TiO2). The highest values of the absorbed power density can be obtained in microcapsules with absorbing shell thickness of approximately a tenth of a laser wavelength. When laser radiation is scattered by a dimer constituted by two identical absorbing microcapsules the absorbed power density can be maximized by the choosing of proper dimer spatial configuration. In the case of strongly absorbing particles, the absorption maximum corresponds to a shift of the capsules to a distance of about their diameter, and in the case of weakly absorbing particles the absorption is maximal when particles are in geometrical shades of each other.

  11. 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.

  12. Triple effect absorption cycles

    SciTech Connect

    Erickson, D.C.; Potnis, S.V.; Tang, J.

    1996-12-31

    Triple effect absorption chillers can achieve 50% COP improvement over double-effect systems. However, to translate this potential into cost-effective hardware, the most promising embodiments must be identified. In this study, 12 generic triple effect cycles and 76 possible hermetic loop arrangements of those 12 generic cycles were identified. The generic triple effect cycles were screened based on their pressure and solubility field requirements, generic COPs, risk involved in the component design, and number of components in a high corrosive environment. This screening identified four promising arrangements: Alkitrate Topping cycle, Pressure Staged Envelope cycle, High Pressure Overlap cycle, and Dual Loopmore » cycle. All of these arrangements have a very high COP ({approximately} 1.8), however the development risk and cost involved is different for each arrangement. Therefore, the selection of a particular arrangement will depend upon the specific situation under consideration.« less

  13. 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.

  14. Nonequilibrium quantum absorption refrigerator

    NASA Astrophysics Data System (ADS)

    Du, Jian-Ying; Zhang, Fu-Lin

    2018-06-01

    We study a quantum absorption refrigerator, in which a target qubit is cooled by two machine qubits in a nonequilibrium steady-state. It is realized by a strong internal coupling in the two-qubit fridge and a vanishing tripartite interaction among the whole system. The coherence of a machine virtual qubit is investigated as quantumness of the fridge. A necessary condition for cooling shows that the quantum coherence is beneficial to the nonequilibrium fridge, while it is detrimental as far as the maximum coefficient of performance (COP) and the COP at maximum power are concerned. Here, the COP is defined only in terms of heat currents caused by the tripartite interaction, with the one maintaining the two-qubit nonequilibrium state being excluded. The later can be considered to have no direct involvement in extracting heat from the target, as it is not affected by the tripartite interaction.

  15. Determination of optical absorption coefficient with focusing photoacoustic imaging.

    PubMed

    Li, Zhifang; Li, Hui; Zeng, Zhiping; Xie, Wenming; Chen, Wei R

    2012-06-01

    Absorption coefficient of biological tissue is an important factor for photothermal therapy and photoacoustic imaging. However, its determination remains a challenge. In this paper, we propose a method using focusing photoacoustic imaging technique to quantify the target optical absorption coefficient. It utilizes the ratio of the amplitude of the peak signal from the top boundary of the target to that from the bottom boundary based on wavelet transform. This method is self-calibrating. Factors, such as absolute optical fluence, ultrasound parameters, and Grüneisen parameter, can be canceled by dividing the amplitudes of the two peaks. To demonstrate this method, we quantified the optical absorption coefficient of a target with various concentrations of an absorbing dye. This method is particularly useful to provide accurate absorption coefficient for predicting the outcomes of photothermal interaction for cancer treatment with absorption enhancement.

  16. Spectrophotometric Determination of the Dissociation Constant of an Acid-Base Indicator Using a Mathematical Deconvolution Technique

    ERIC Educational Resources Information Center

    Alter, Krystyn P.; Molloy, John L.; Niemeyer, Emily D.

    2005-01-01

    A laboratory experiment reinforces the concept of acid-base equilibria while introducing a common application of spectrophotometry and can easily be completed within a standard four-hour laboratory period. It provides students with an opportunity to use advanced data analysis techniques like data smoothing and spectral deconvolution to…

  17. An investigation of a mathematical model for atmospheric absorption spectra

    NASA Technical Reports Server (NTRS)

    Niple, E. R.

    1979-01-01

    A computer program that calculates absorption spectra for slant paths through the atmosphere is described. The program uses an efficient convolution technique (Romberg integration) to simulate instrument resolution effects. A brief information analysis is performed on a set of calculated spectra to illustrate how such techniques may be used to explore the quality of the information in a spectrum.

  18. 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

  19. 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.

  20. Differential absorption lidar measurements of atmospheric temperature and pressure profiles

    NASA Technical Reports Server (NTRS)

    Korb, C. L.

    1981-01-01

    The theory and methodology of using differential absorption lidar techniques for the remote measurement of atmospheric pressure profiles, surface pressure, and temperature profiles from ground, air, and space-based platforms are presented. Pressure measurements are effected by means of high resolution measurement of absorption at the edges of the oxygen A band lines where absorption is pressure dependent due to collisional line broadening. Temperature is assessed using measurements of the absorption at the center of the oxygen A band line originating from a quantum state with high ground state energy. The population of the state is temperature dependent, allowing determination of the temperature through the Boltzmann term. The results of simulations of the techniques using Voigt profile and variational analysis are reported for ground-based, airborne, and Shuttle-based systems. Accuracies in the 0.5-1.0 K and 0.1-0.3% range are projected.

  1. 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

  2. Optical Absorption in Liquid Semiconductors

    NASA Astrophysics Data System (ADS)

    Bell, Florian Gene

    An infrared absorption cell has been developed which is suitable for high temperature liquids which have absorptions in the range .1-10('3) cm('-1). The cell is constructed by clamping a gasket between two flat optical windows. This unique design allows the use of any optical windows chemically compatible with the liquid. The long -wavelength limit of the measurements is therefore limited only by the choice of the optical windows. The thickness of the cell can easily be set during assembly, and can be varied from 50 (mu)m to .5 cm. Measurements of the optical absorption edge were performed on the liquid alloy Se(,1-x)Tl(,x) for x = 0, .001, .002, .003, .005, .007, and .009, from the melting point up to 475(DEGREES)C. The absorption was found to be exponential in the photon energy over the experimental range from 0.3 eV to 1.2 eV. The absorption increased linearly with concentration according to the empirical relation (alpha)(,T)(h(nu)) = (alpha)(,1) + (alpha)(,2)x, and the absorption (alpha)(,1) was interpreted as the absorption in the absence of T1. (alpha)(,1) also agreed with the measured absorption in 100% Se at corresponding temperatures and energies. The excess absorption defined by (DELTA)(alpha) = (alpha)(,T)(h(nu))-(alpha)(,1) was interpreted as the absorption associated with Tl and was found to be thermally activated with an activation energy E(,t) = 0.5 eV. The exponential edge is explained as absorption on atoms immersed in strong electric fields surrounding ions. The strong fields give rise to an absorption tail similar to the Franz-Keldysh effect. A simple calculation is performed which is based on the Dow-Redfield theory of absorption in an electric field with excitonic effects included. The excess absorption at low photon energies is proportional to the square of the concentration of ions, which are proposed to exist in the liquid according to the relation C(,i) (PROPORTIONAL) x(' 1/2)(.)e('-E)t('/kT), which is the origin of the thermal activation

  3. Sensitive determination of total particulate phosphorus and particulate inorganic phosphorus in seawater using liquid waveguide spectrophotometry.

    PubMed

    Ehama, Makoto; Hashihama, Fuminori; Kinouchi, Shinko; Kanda, Jota; Saito, Hiroaki

    2016-06-01

    Determining the total particulate phosphorus (TPP) and particulate inorganic phosphorus (PIP) in oligotrophic oceanic water generally requires the filtration of a large amount of water sample. This paper describes methods that require small filtration volumes for determining the TPP and PIP concentrations. The methods were devised by validating or improving conventional sample processing and by applying highly sensitive liquid waveguide spectrophotometry to the measurements of oxidized or acid-extracted phosphate from TPP and PIP, respectively. The oxidation of TPP was performed by a chemical wet oxidation method using 3% potassium persulfate. The acid extraction of PIP was initially carried out based on the conventional extraction methodology, which requires 1M HCl, followed by the procedure for decreasing acidity. While the conventional procedure for acid removal requires a ten-fold dilution of the 1M HCl extract with purified water, the improved procedure proposed in this study uses 8M NaOH solution for neutralizing 1M HCl extract in order to reduce the dilution effect. An experiment for comparing the absorbances of the phosphate standard dissolved in 0.1M HCl and of that dissolved in a neutralized solution [1M HCl: 8M NaOH=8:1 (v:v)] exhibited a higher absorbance in the neutralized solution. This indicated that the improved procedure completely removed the acid effect, which reduces the sensitivity of the phosphate measurement. Application to an ultraoligotrophic water sample showed that the TPP concentration in a 1075mL-filtered sample was 8.4nM with a coefficient of variation (CV) of 4.3% and the PIP concentration in a 2300mL-filtered sample was 1.3nM with a CV of 6.1%. Based on the detection limit (3nM) of the sensitive phosphate measurement and the ambient TPP and PIP concentrations of the ultraoligotrophic water, the minimum filtration volumes required for the detection of TPP and PIP were estimated to be 15 and 52mL, respectively. Copyright © 2016

  4. 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.

  5. Applications of absorption spectroscopy using quantum cascade lasers.

    PubMed

    Zhang, Lizhu; Tian, Guang; Li, Jingsong; Yu, Benli

    2014-01-01

    Infrared laser absorption spectroscopy (LAS) is a promising modern technique for sensing trace gases with high sensitivity, selectivity, and high time resolution. Mid-infrared quantum cascade lasers, operating in a pulsed or continuous wave mode, have potential as spectroscopic sources because of their narrow linewidths, single mode operation, tunability, high output power, reliability, low power consumption, and compactness. This paper reviews some important developments in modern laser absorption spectroscopy based on the use of quantum cascade laser (QCL) sources. Among the various laser spectroscopic methods, this review is focused on selected absorption spectroscopy applications of QCLs, with particular emphasis on molecular spectroscopy, industrial process control, combustion diagnostics, and medical breath analysis.

  6. Flameless Atomic Absorption Spectroscopy: Effects of Nitrates and Sulfates.

    DTIC Science & Technology

    1980-05-01

    ATTACHED DDJ~P 1413 EDITION 01 INO, 6 5 IabSoLEr J UjN!LbAa~ A- i SELU 0 IONOF I tG 651 J Flameless Atomic Absorption Spectroscopy: Effects of Nitrates...analytical techniques, flameless atomic absorption is subject to matrix or interference effects. Upon heating, nitrate and sulfate salts decompose to...Eklund and J.E. Smith, Anal Chem, 51, 1205 (1979) R.H. Eklund and J.A. Holcombe, Anal Chim. Acta, 109, 97 (1979) FLAMELESS ATOMIC ABSORPTION

  7. 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.

  8. Atmospheric absorption of terahertz radiation and water vapor continuum effects

    NASA Astrophysics Data System (ADS)

    Slocum, David M.; Slingerland, Elizabeth J.; Giles, Robert H.; Goyette, Thomas M.

    2013-09-01

    The water vapor continuum absorption spectrum was investigated using Fourier Transform Spectroscopy. The transmission of broadband terahertz radiation from 0.300 to 1.500 THz was recorded for multiple path lengths and relative humidity levels. The absorption coefficient as a function of frequency was determined and compared with theoretical predictions and available water vapor absorption data. The prediction code is able to separately model the different parts of atmospheric absorption for a range of experimental conditions. A variety of conditions were accurately modeled using this code including both self and foreign gas broadening for low and high water vapor pressures for many different measurement techniques. The intensity and location of the observed absorption lines were also in good agreement with spectral databases. However, there was a discrepancy between the resonant line spectrum simulation and the observed absorption spectrum in the atmospheric transmission windows caused by the continuum absorption. A small discrepancy remained even after using the best available data from the literature to account for the continuum absorption. From the experimental and resonant line simulation spectra the air-broadening continuum parameter was calculated and compared with values available in the literature.

  9. Studies on absorption coefficient near edge of multi elements

    NASA Astrophysics Data System (ADS)

    Eisa, M. H.; Shen, H.; Yao, H. Y.; Mi, Y.; Zhou, Z. Y.; Hu, T. D.; Xie, Y. N.

    2005-12-01

    X-ray absorption near edge structure (XANES) was used to study the near edge mass-absorption coefficients of seven elements, such as, Ti, V, Fe, Co, Ni, Cu and Zn. It is well known that, on the near edge absorption of element, when incident X-ray a few eV change can make the absorption coefficient an order magnitude alteration. So that, there are only a few points mass-absorption coefficient at the near edge absorption and that always average value in published table. Our results showed a wide range of data, the total measured data of mass-absorption coefficient of the seven elements was about 505. The investigation confirmed that XANES is useful technique for multi-element absorption coefficient measurement. Details of experimental methods and results are given and discussed. The experimental work has been performed at Beijing Synchrotron Radiation Facility. The measured values were compared with the published data. Good agreement between experimental results and published data is obtained.

  10. The practical application of reflectance spectrophotometry for the demonstration of haemoglobin and its degradation in bruises

    PubMed Central

    Hughes, V K; Ellis, P S; Burt, T; Langlois, N E I

    2004-01-01

    Aims: To develop a non-invasive method to demonstrate the presence of haemoglobin and its degradation products in bruises in live human subjects for the purposes of objectively assisting in the determination of the age of a bruise. Methods: The cuvette holder unit of a Cary 100 Bio UV-Visible Spectrophotometer was replaced with the manufacture’s fibre optic cable and optical reflectance probe. The probe was placed on the skin surface. The absorption spectrum from 780 to 380 nm was collected and transformed into the first derivative. Calculation of the first derivative permits absorption attributed to haemoglobin degradation (primarily to bilirubin, but also haemosiderin) to be separated from absorption by haemoglobin. First derivative and colorimetry values, expressed as CIEL*a*b data, were derived from scans of 50 bruises. Results: The fibre optic cable and probe allowed the spectrophotometer to collect reproducible absorption spectra of bruises in the skin of living subjects. A bruise at three days has greater negative first derivative values at 480 and 490 nm than does a fresh bruise, indicating the local degradation of haemoglobin. Correlation between the first derivative and the CIEL*a*b “b” values in a series of bruises indicates that the yellow colour in a bruise is proportional to the amount of local haemoglobin breakdown. Conclusion: The ability to demonstrate the presence of haemoglobin and measure its degradation in bruises in living human subjects by a non-invasive method has not been described previously, and may be of use in the objective ageing of bruises for forensic purposes. PMID:15047735

  11. Differential-optoacoustic absorption detector

    NASA Technical Reports Server (NTRS)

    Shumate, M. S.

    1977-01-01

    Two-cell spectrophone detects trace amounts of atmospheric pollutants by measuring absorption coefficients of gases with various laser sources. Device measures pressure difference between two tapered cells with differential manometer. Background signal is reduced by balanced window heating and balanced carrier gas absorption in two cells.

  12. 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).

  13. 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.

  14. 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.

  15. Likelihood of aneurysmal subarachnoid haemorrhage in patients with normal unenhanced CT, CSF xanthochromia on spectrophotometry and negative CT angiography.

    PubMed

    Rana, A K; Turner, H E; Deans, K A

    2013-01-01

    Patients with suspected subarachnoid haemorrhage, a normal noncontrast computed tomography (CT) and cerebrospinal fluid (CSF) evidence of haemoglobin breakdown products often undergo CT angiography (CTA). If this is normal, then invasive catheter angiography may be offered. In current clinical practice, haemoglobin breakdown products are detected by spectrophotometry rather than visible xanthochromia, and CTA is performed on multidetector scanners. The aim of this study was to determine if such patients should still have a catheter angiography, given the associated risks. Patients positive for CSF spectrophotometry (n=26) were retrospectively identified from the clinical biochemistry information system and imaging data from the electronic radiology records were reviewed. Discharge letters were consulted to relate the biochemistry and radiology results to the final diagnosis. 15 patients with CT angiography were found. Nine patients had normal CT angiography. No causative aneurysms had been missed. One patient had small, coincidental aneurysms missed on initial reading of the CTA. The likelihood of a clinically significant aneurysm in a patient who is CT negative, lumbar puncture positive and CTA negative is low. Double reporting of negative CT angiograms may be advisable.

  16. 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.

  17. 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.

  18. Fjord light regime: Bio-optical variability, absorption budget, and hyperspectral light availability in Sognefjord and Trondheimsfjord, Norway

    NASA Astrophysics Data System (ADS)

    Mascarenhas, V. J.; Voß, D.; Wollschlaeger, J.; Zielinski, O.

    2017-05-01

    Optically active constituents (OACs) in addition to water molecules attenuate light via processes of absorption and scattering and thereby determine underwater light availability. An analysis of their optical properties helps in determining the contribution of each of these to light attenuation. With an aim to study the bio-optical variability, absorption budget and 1% spectral light availability, hydrographical (temperature and salinity), and hyperspectral optical (downwelling irradiance and upwelling radiance) profiles were measured along fjord transects in Sognefjord and Trondheimsfjord, Norway. Optical water quality observations were also performed using Secchi disc and Forel-Ule scale. In concurrence, water samples were collected and analyzed via visible spectrophotometry, fluorometry, and gravimetry to quantify and derive inherent optical properties of the water constituents. An absorption model (R2 = 0.91, n = 36, p < 0.05) as a function of OACs is developed for Sognefjord using multiple regression analysis. Influenced by glacial meltwater, Sognefjord had higher concentration of inorganic suspended matter, while Trondheimsfjord had higher concentrations of CDOM. Increase in turbidity caused increased attenuation of light upstream, as a result of which the euphotic depth decreased from outer to inner fjord sections. Triangular representation of absorption budget revealed dominant absorption by CDOM at 443-555 nm, while that by phytoplankton at 665 nm. Sognefjord however exhibited much greater optical complexity. A significantly strong correlation between salinity and acdom440 is used to develop an algorithm to estimate acdom440 using salinity in Trondheimsfjord.

  19. 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.

  20. Hydride generation coupled to microfunnel-assisted headspace liquid-phase microextraction for the determination of arsenic with UV-Vis spectrophotometry.

    PubMed

    Hashemniaye-Torshizi, Reihaneh; Ashraf, Narges; Arbab-Zavar, Mohammad Hossein

    2014-12-01

    In this research, a microfunnel-assisted headspace liquid-phase microextraction technique has been used in combination with hydride generation to determine arsenic (As) by UV-Vis spectrophotometry. The method is based on the reduction of As to arsine (AsH3) in acidic media by sodium tetrahydroborate (NaBH4) followed by its subsequent reaction with silver diethyldithiocarbamate (AgDDC) to give an absorbing complex at 510 nm. The complexing reagent (AgDDC) has been dissolved in a 1:1 (by the volume ratio) mixture of chloroform/chlorobenzene microdroplet and exposed to the generated gaseous arsine via a reversed microfunnel in the headspace of the sample solution. Several operating parameters affecting the performance of the method have been examined and optimized. Acetonitrile solvent has been added to the working samples as a sensitivity enhancement agent. Under the optimized operating conditions, the detection limit has been measured to be 0.2 ng mL(-1) (based on 3sb/m criterion, n b = 8), and the calibration curve was linear in the range of 0.5-12 ng mL(-1). The relative standard deviation for eight replicate measurements was 1.9 %. Also, the effects of several potential interferences have been studied. The accuracy of the method was validated through the analysis of JR-1 geological standard reference material. The method has been successfully applied for the determination of arsenic in raw and spiked soft drink and water samples with the recoveries that ranged from 91 to 106 %.

  1. The role of ultraviolet-A reflectance and ultraviolet-A induced fluorescence in the appearance of budgerigar plumage: insights from spectrofluorometry and reflectance spectrophotometry.

    PubMed Central

    Pearn, Sophie M; Bennett, Andrew T D; Cuthill, Innes C

    2003-01-01

    Fluorescence has so far been found in 52 parrot species when illuminated with ultraviolet-A (UVA) 'black' lamps, and two attempts have been made to determine whether such fluorescence plays any role in sexual signalling. However, the contribution of the reflectance versus fluorescence to the total radiance from feathers, even in the most studied species to date (budgerigars), is unclear. Nor has the plumage of this study species been systematically assessed to determine the distribution of fluorescent patches. We therefore used spectrofluorometry to determine which areas of budgerigars fluoresce and the excitation and emission spectra involved; this is the first time that such a technique has been applied to avian plumage. We found that both the yellow crown and (normally hidden) white downy chest feathers exhibit strong UVA-induced fluorescence, with peak emissions at 527 nm and 436 nm, respectively. Conversely, the bright-green chest and dark-blue tail feathers do not fluoresce. When comparing reflectance spectra (400-700 nm) from the yellow crown using illuminants with a proportion of UVA comparable to daylight, and illuminants with all UVA removed, no measurable difference resulting from fluorescence was found. This suggests that under normal daylight the contribution of fluorescence to radiance is probably trivial. Furthermore, these spectra revealed that males had fluorescent crowns with substantially higher reflectance than those of females, in both the UV waveband and at longer wavelengths. Reflectance spectrophotometry was also performed on a number of live wild-type male budgerigars to investigate the chromatic contrast between the different plumage areas. This showed that many plumage regions are highly UV-reflective. Overall our results suggest that rapid surveys using UVA black lamps may overestimate the contribution of fluorescence to plumage coloration, and that any signalling role of fluorescence emissions, at least from the yellow crown of

  2. Application of experimental design and derivative spectrophotometry methods in optimization and analysis of biosorption of binary mixtures of basic dyes from aqueous solutions.

    PubMed

    Asfaram, Arash; Ghaedi, Mehrorang; Ghezelbash, Gholam Reza; Pepe, Francesco

    2017-05-01

    Simultaneous biosorption of malachite green (MG) and crystal violet (CV) on biosorbent Yarrowia lipolytica ISF7 was studied. An appropriate derivative spectrophotometry technique was used to evaluate the concentration of each dye in binary solutions, despite significant interferences in visible light absorbances. The effects of pH, temperature, growth time, initial MG and CV concentration in batch experiments were assessed using Design of Experiment (DOE) according to central composite second order response surface methodology (RSM). The analysis showed that the greatest biosorption efficiency (>99% for both dyes) can be obtained at pH 7.0, T=28°C, 24h mixing and 20mgL -1 initial concentrations for both MG and CV dyes. The quadratic constructed equation ability for fitting experimental data is judged based on criterions like R 2 values, significant p and lack-of-fit value strongly confirm its high adequacy and applicability for prediction of revel behavior of the system under study. The proposed model showed very high correlation coefficients (R 2 =0.9997 for CV and R 2 =0.9989 for MG), while supported by closeness of predicted and experimental value. A kinetic analysis was carried out, showing that for both dyes a pseudo-second order kinetic model adequately describes the available data. The Langmuir isotherm model in single and binary components has better performance for description of dyes biosorption with maximum monolayer biosorption capacity of 59.4 and 62.7mgg -1 in single component and 46.4 and 50.0mgg -1 for CV and MB in binary components, respectively. The surface structure of biosorbents and the possible biosorbents-dyes interactions between were also evaluated by Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The values of thermodynamic parameters including ΔG° and ΔH° strongly confirm which method is spontaneous and endothermic. Copyright © 2017. Published by Elsevier Inc.

  3. Effects of Pulsed Electromagnetic Fields on Breast Cancer Cell Line MCF 7 Using Absorption Spectroscopy.

    PubMed

    Alcantara, Dominic Z; Soliman, Ian Jerry S; Pobre, Romeric F; Naguib, Raouf N G

    2017-07-01

    We present an analysis of the effects of pulsed electromagnetic fields (PEMF) with 3.3 MHz carrier frequency and modulated by audio resonant frequencies on the MCF-7 breast cancer cell line in vitro using absorption spectroscopy. This involves a fluorescence dye called PrestoBlue™ Cell Viability Reagent and a spectrophotometry to test the viability of MCF-7 breast cancer cells under different PEMF treatment conditions in terms of the cell absorption values. The DNA molecule of the MCF-7 breast cancer cells has an electric dipole property that renders it sensitive and reactive to applied electromagnetic fields. Resonant frequencies derived from four genes mutated in MCF-7 breast cancer cells [rapamycin-insensitive companion of mammalian target of rapamycin (RICTOR), peroxisome proliferator-activated receptor (PPARG), Nijmegen breakage syndrome 1 (NBN) and checkpoint kinase 2 (CHEK2)] were applied in generating square pulsed electromagnetic waves. Effects were monitored through measurement of absorption of the samples with PrestoBlue™, and the significance of the treatment was determined using the t-test. There was a significant effect on MCF-7 cells after treatment with PEMF at the resonant frequencies of the following genes for specific durations of exposure: RICTOR for 10 min, PPARG for 10 min, NBN for 15 min, and CHEK2 for 5 min. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  4. Simultaneous determination of polysaccharides and 21 nucleosides and amino acids in different tissues of Salvia miltiorrhiza from different areas by UV-visible spectrophotometry and UHPLC with triple quadrupole MS/MS.

    PubMed

    Xiang, Xiang; Sha, Xiuxiu; Su, Shulan; Zhu, Zhenhua; Guo, Sheng; Yan, Hui; Qian, Dawei; Duan, Jin-Ao

    2018-03-01

    Salvia miltiorrhiza, a traditional Chinese medicine, is a widely used herbal medicine to treat cardiovascular and cerebrovascular diseases. In this study, ultraviolet (UV)-visible spectrophotometry and ultra-high performance liquid chromatography with triple quadrupole tandem mass spectrometry analytical methods were used for rapid quantification of polysaccharides and 21 nucleosides and amino acids in S. miltiorrhiza to determine 17 samples of different tissues from different areas. Based on the total contents, hierarchical clustering analysis and principal components analysis were performed to classify these samples. The established methods were validated with good linearity, precision, repeatability, stability, and recovery. Chemical analysis revealed a higher content of total analytes in the sample of inflorescence from Nanjing (34.17 mg/g), sample of root and rhizome from Shaanxi (34.13 mg/g) and sample of stem and leaf from Nanjing (31.14 mg/g), respectively, indicating that root and rhizome from Shaanxi and the aerial parts from Nanjing exhibited the highest quality due to their highest content. In addition, contents of nucleosides and amino acids in the aerial parts (14.67 mg/g) were much higher than that in roots and rhizomes (9.17 mg/g). This study suggested that UV-visible spectrophotometry and ultra-high performance liquid chromatography with triple quadrupole tandem mass spectrometry are effective techniques to analyze polysaccharides, nucleosides, and amino acids in plants, and they provided valuable information for the development and utilization value of the aerial parts of S. miltiorrhiza. This analysis would also provide useful information for the quality control of S. miltiorrhiza. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. 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.

  6. Enhanced absorption of light by charged nanoparticles.

    PubMed

    Rosenkrantz, Etai; Arnon, Shlomi

    2010-04-15

    We found that various charged nanoparticles (NPs) can raise the attenuation of electromagnetic (EM) radiation over 30 times more efficiently during resonance in comparison to equivalent noncharged particles for a given set of parameters. A condition that indicates a state of resonance between the incident EM radiation and the NP surface excitations is mathematically derived. Our results shed light on the mechanism responsible for the strong absorption of light by such charged NPs. The outcome of this research could help to design a new generation of communication devices as well as a new technique for biological cell imaging.

  7. Nonlinear absorption and optical limiting in gold-precipitated glasses induced by a femtosecond laser

    NASA Astrophysics Data System (ADS)

    Qu, Shiliang; Gao, Yachen; Jiang, Xiongwei; Zeng, Huidan; Song, Yinglin; Qiu, Jianrong; Zhu, Congshan; Hirao, K.

    2003-09-01

    Nonlinear absorptions of Au nanoparticles precipitated silicate glasses by irradiation of a focused femtosecond pulsed laser were investigated using Z-scan technique with 8 ns pulses at 532 nm. Optical limiting (OL) effects in such glasses have been also measured. It is observed that the behaviors of transition from saturable absorption to reverse saturable absorption and the OL performances for different samples are significantly different, which depend drastically on the irradiation power density of the femtosecond laser used for the Au nanoparticles precipitation in the glass. Strong nonlinear absorptions in these samples are mainly attributed to the surface plasmon resonance (SPR) and free carrier absorptions of the precipitated Au nanoparticles.

  8. Solar absorptance and thermal emittance of some common spacecraft thermal-control coatings

    NASA Technical Reports Server (NTRS)

    Henninger, J. H.

    1984-01-01

    Solar absorptance and thermal emittance of spacecraft materials are critical parameters in determining spacecraft temperature control. Because thickness, surface preparation, coatings formulation, manufacturing techniques, etc. affect these parameters, it is usually necessary to measure the absorptance and emittance of materials before they are used. Absorptance and emittance data for many common types of thermal control coatings, are together with some sample spectral data curves of absorptance. In some cases for which ultraviolet and particle radiation data are available, the degraded absorptance and emittance values are also listed.

  9. Gas in scattering media absorption spectroscopy - GASMAS

    NASA Astrophysics Data System (ADS)

    Svanberg, Sune

    2008-09-01

    An overview of the new field of Gas in Scattering Media Absorption Spectroscopy (GASMAS) is presented. GASMAS combines narrow-band diode-laser spectroscopy with diffuse media optical propagation. While solids and liquids have broad absorption features, free gas in pores and cavities in the material is characterized by sharp spectral signatures, typically 10,000 times sharper than those of the host material. Many applications in materials science, food packaging, pharmaceutics and medicine have been demonstrated. So far molecular oxygen and water vapour have been studied around 760 and 935 nm, respectively. Liquid water, an important constituent in many natural materials, such as tissue, has a low absorption at such wavelengths, allowing propagation. Polystyrene foam, wood, fruits, food-stuffs, pharmaceutical tablets, and human sinus cavities have been studied. Transport of gas in porous media can readily be studied by first immersing the material in, e.g., pure nitrogen, and then observing the rate at which normal air, containing oxygen, reinvades the material. The conductance of the sinus connective passages can be measured in this way by flushing the nasal cavity with nitrogen. Also other dynamic processes such as drying of materials can be studied. The techniques have also been extended to remote-sensing applications (LIDAR-GASMAS).

  10. Absorption sites of orally administered drugs in the small intestine.

    PubMed

    Murakami, Teruo

    2017-12-01

    In pharmacotherapy, drugs are mostly taken orally to be absorbed systemically from the small intestine, and some drugs are known to have preferential absorption sites in the small intestine. It would therefore be valuable to know the absorption sites of orally administered drugs and the influencing factors. Areas covered:In this review, the author summarizes the reported absorption sites of orally administered drugs, as well as, influencing factors and experimental techniques. Information on the main absorption sites and influencing factors can help to develop ideal drug delivery systems and more effective pharmacotherapies. Expert opinion: Various factors including: the solubility, lipophilicity, luminal concentration, pKa value, transporter substrate specificity, transporter expression, luminal fluid pH, gastrointestinal transit time, and intestinal metabolism determine the site-dependent intestinal absorption. However, most of the dissolved fraction of orally administered drugs including substrates for ABC and SLC transporters, except for some weakly basic drugs with higher pKa values, are considered to be absorbed sequentially from the proximal small intestine. Securing the solubility and stability of drugs prior to reaching to the main absorption sites and appropriate delivery rates of drugs at absorption sites are important goals for achieving effective pharmacotherapy.

  11. Studies on Inhibition of Intestinal Absorption of Radioactive Strontium

    PubMed Central

    Skoryna, Stanley C.; Paul, T. M.; Edward, Deirdre Waldron

    1964-01-01

    A method is reported which permits selective suppression of absorption of radioactive strontium from ingested food material, permitting the calcium to be available to the body. Studies were carried out in vivo by injection of Sr89 and Ca45 in the presence of inert carrier into ligated intestinal segments in rats, and the amount of absorption was measured by standard monitoring techniques. The pattern of absorption of both ions is very similar but the rate of absorption is different. It was found that the polyelectrolyte, sodium alginate, obtained from brown algae (Phaeophyceae), injected simultaneously with radiostrontium effectively reduces the absortion of Sr89 from all segments of the intestine by as much as 50-80% of the control values. No significant reduction in absorption of Ca45 was observed in equivalent concentrations. The reduction in blood levels of Sr89 and in bone uptake corresponded to the absorption pattern. The difference in the effect on strontium and calcium absorption may be due to differences in the binding capacity of sodium alginate from the two metal ions under the conditions present in vivo. PMID:14180534

  12. Solvatochromic Effects on the Absorption Spectrum of 2-Thiocytosine

    PubMed Central

    2017-01-01

    The solvatochromic effects of six different solvents on the UV absorption spectrum of 2-thiocytosine have been studied by a combination of experimental and theoretical techniques. The steady-state absorption spectra show significant shifts of the absorption bands, where in more polar solvents the first absorption maximum shifts to higher transition energies and the second maximum to lower energies. The observed solvatochromic shifts have been rationalized using three popular solvatochromic scales and with high-level multireference quantum chemistry calculations including implicit and explicit solvent effects. It has been found that the dipole moments of the excited states account for some general shifts in the excitation energies, whereas the explicit solvent interactions explain the differences in the spectra recorded in the different solvents. PMID:28452483

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

    SciTech Connect

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

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

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

    DOE PAGES

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

    2017-03-06

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

  15. Broadband absorption with gradient metasurfaces

    NASA Astrophysics Data System (ADS)

    Kwon, Hoyeong; Chalabi, Hamidreza; Alù, Andrea

    2018-03-01

    A metasurface with appropriately designed transverse spatial inhomogeneities can provide the desired phase redistribution in response to an incident wave with arbitrary incident angle. This property of gradient metasurfaces has been used to modify light propagation in unusual manners, to transform the impinging optical wavefront with large flexibility. In this work, we show how gradient metasurfaces can be tailored to offer high absorption in thin absorptive layers, and how to design realistic metasurfaces for this purpose using dielectric materials.

  16. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. 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

    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 themore » 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)« less

  18. 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.

  19. Application of wavelet and Fuorier transforms as powerful alternatives for derivative spectrophotometry in analysis of binary mixtures: A comparative study

    NASA Astrophysics Data System (ADS)

    Hassan, Said A.; Abdel-Gawad, Sherif A.

    2018-02-01

    Two signal processing methods, namely, Continuous Wavelet Transform (CWT) and the second was Discrete Fourier Transform (DFT) were introduced as alternatives to the classical Derivative Spectrophotometry (DS) in analysis of binary mixtures. To show the advantages of these methods, a comparative study was performed on a binary mixture of Naltrexone (NTX) and Bupropion (BUP). The methods were compared by analyzing laboratory prepared mixtures of the two drugs. By comparing performance of the three methods, it was proved that CWT and DFT methods are more efficient and advantageous in analysis of mixtures with overlapped spectra than DS. The three signal processing methods were adopted for the quantification of NTX and BUP in pure and tablet forms. The adopted methods were validated according to the ICH guideline where accuracy, precision and specificity were found to be within appropriate limits.

  20. 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.

  1. 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.

  2. Scramjet Performance Assessment Using Water Absorption Diagnostics (U)

    NASA Technical Reports Server (NTRS)

    Cavolowsky, John A.; Loomis, Mark P.; Deiwert, George

    1995-01-01

    Simultaneous multiple path measurements of temperature and H2O concentration will be presented for the AIMHYE test entries in the NASA Ames 16-Inch Shock Tunnel. Monitoring the progress of high temperature chemical reactions that define scramjet combustor efficiencies is a task uniquely suited to nonintrusive optical diagnostics. One application strategy to overcome the many challenges and limitations of nonintrusive measurements is to use laser absorption spectroscopy coupled with optical fibers. Absorption spectroscopic techniques with rapidly tunable lasers are capable of making simultaneous measurements of mole fraction, temperature, pressure, and velocity. The scramjet water absorption diagnostic was used to measure combustor efficiency and was compared to thrust measurements using a nozzle force balance and integrated nozzle pressures to develop a direct technique for evaluating integrated scramjet performance. Tests were initially performed with a diode laser tuning over a water absorption feature at 1391.7 nm. A second diode laser later became available at a wavelength near 1343.3 nm covering an additional water absorption feature and was incorporated in the system for a two-wavelength technique. Both temperature and mole fraction can be inferred from the lineshape analysis using this approach. Additional high temperature spectroscopy research was conducted to reduce uncertainties in the scramjet application. The lasers are optical fiber coupled to ports at the combustor exit and in the nozzle region. The output from the two diode lasers were combined in a single fiber, and the resultant two-wavelength beam was subsequently split into four legs. Each leg was directed through 60 meters of optical fiber to four combustor exit locations for measurement of beam intensity after absorption by the water within the flow. Absorption results will be compared to 1D combustor analysis using RJPA and nozzle CFD computations as well as to data from a nozzle metric

  3. Spectrophotometry of VIIZW421 and IIZW67 - s0 Galaxies Dominated by Young Stars

    NASA Astrophysics Data System (ADS)

    Sparke, L. S.; Kormendy, J.; Spinrad, H.

    1980-02-01

    We investigate the stellar content of two SO galaxies whose spectra show deep Balmer absorption lines but little emission. Continuum colors and the Faber-Burstein (Mg)0 index show that the blue light is dominated by young stars. In VII Zw 421 there is a radial population gradient; the nucleus has relatively more young stars than the lens. An approximate spectral synthesis confirms the need for young (rather than metal-poor) stars to produce sufficiently strong Balmer lines. In VII Zw 421 the best synthesis implies that 45Th of the nuclear light at 5000 Å comes from stars close to A1 V in type. In the lens, the young-star contribution is smaller by a factor of 2-3. Also, in the nucleus only, the observed Na D lines are much stronger than in our model. This suggests a connection with the young component and supports Faber and Burstein's conclusion that abnormally strong Na D absorption is sometimes interstellar. Thus VII Zw 421 and II Zw 67 are similar to NGC 5102, the nearest SO galaxy dominated by young stars. The present SO's provide important constraints on any interpretation of the young component. At - 19.9 and -21.5 absolute B mag (H0 = 50 km s-1 1 Mpc-1), they are unusually luminous for their early-type spectra. They are also unusually compact, which may provide them with gravitational potential wells deep enough to retain gas despite processes which remove gas from other early-type galaxies.

  4. 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. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

  5. Rapid determination of lovastatin in the fermentation broth of Aspergillus terreus using dual-wavelength UV spectrophotometry.

    PubMed

    Li, Shi-Weng; Song, Hong-Ping; Leng, Yan

    2014-01-01

    Lovastatin, a hypocholesterolemic drug, is produced by submerged fermentation of Aspergillus terreus Thom (Trichocomaceae). High performance liquid chromatography is usually used to determine lovastatin in samples of the fermentation broth. However, this method is inconvenient and costly, especially in the context of high-throughput sample analysis. A direct and simple dual-wavelength ultraviolet spectrophotometric method for quantifying lovastatin in the fermentation broth of A. terreus was developed. A. terreus Z15-7 was used for all experiments. The liquid fermentation was conducted at 30 °C in a rotary shaker at 150 rpm for 15 d. Silica gel and neutral alumina column chromatography were used for the separation and purification of lovastatin from the fermentation broth. The limits of detection of lovastatin were 0.320 μg/ml in the lovastatin standard solution and 0.490 μg/ml in the fermentation broth sample and the limits of quantification of lovastatin were 1.265 μg/ml in the lovastatin standard solution and 3.955 μg/ml in the fermentation broth sample. The amounts of lovastatin in the fermentation broth ranged from 876.614 to 911.967 μg/ml, with relative standard deviations from 1.203 to 1.709%. The mean recoveries of lovastatin using silica gel and neutral alumina column chromatography were 84.2 ± 0.82 and 87.2 ± 0.21%, respectively. Dual-wavelength UV spectrophotometry is a rapid, sensitive, accurate, and convenient method for quantifying lovastatin in fermentation broth. Neutral alumina column chromatography is more efficient than silica gel column chromatography for the purification and determination lovastatin using the developed dual-wavelength UV spectrophotometry method.

  6. 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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Rapid measurement of indocyanine green retention by pulse spectrophotometry: a validation study in 70 patients with Child-Pugh A cirrhosis before hepatectomy for hepatocellular carcinoma.

    PubMed

    Cheung, Tan To; Chan, See Ching; Chok, Kenneth S H; Chan, Albert C Y; Yu, Wan Ching; Poon, Ronnie T P; Lo, Chung Mau; Fan, Sheung Tat

    2012-06-01

    The indocyanine green (ICG) retention test is the most popular liver function test for selecting patients for major hepatectomy. Traditionally, it is done using spectrophotometry with serial blood sampling. The newly-developed pulse spectrophotometry is a faster alternative, but its accuracy on Child-Pugh A cirrhotic patients undergoing hepatectomy for hepatocellular carcinoma has not been well documented. This study aimed to assess the accuracy of the LiMON(®), one of the pulse spectrophotometry systems, in measuring preoperative ICG retention in these patients and to devise an easy formula for conversion of the results so that they can be compared with classical literature records where ICG retention was measured by the traditional method. We measured the liver function of 70 Child-Pugh A cirrhotic patients before hepatectomy for hepatocellular carcinoma from September 2008 to January 2009. ICG retention at 15 minutes measured by traditional spectrophotometry (ICGR15) was compared with ICG retention at 15 minutes measured by the LiMON (ICGR15(L)). The median ICGR15 was 14.7% (5.6%-32%) and the median ICGR15(L) was 10.4% (1.2%-28%). The mean difference between them was -4.3606. There was a strong correlation between ICGR15 and ICGR15(L) (correlation coefficient, 0.844; 95% confidence interval, 0.762-0.899). The following formula was devised: ICGR15=1.16XICGR15(L)+2.73. The LiMON provides a fast and repeatable way to measure ICG retention at 15 minutes, but with constant underestimation of the real value. Therefore, when comparing results obtained by traditional spectrophotometry and the LiMON, adjustment of results from the latter is necessary, and this can be done with a simple mathematical calculation using the above formula.

  8. Atomic Absorption Spectroscopy. The Present and the Future.

    ERIC Educational Resources Information Center

    Slavin, Walter

    1982-01-01

    The status of current techniques and methods of atomic absorption (AA) spectroscopy (flame, hybrid, and furnace AA) is discussed, including limitations. Technological opportunities and how they may be used in AA are also discussed, focusing on automation, microprocessors, continuum AA, hybrid analyses, and others. (Author/JN)

  9. Plasmon resonances, anomalous transparency, and reflectionless absorption in overdense plasmas

    NASA Astrophysics Data System (ADS)

    Smolyakov, A.; Sternberg, N.

    2018-03-01

    The structure of the surface and standing wave resonances and their coupling in the configuration of the overdense plasma slab with a single diffraction grating are studied, using impedance matching techniques. Analytical criteria and exact expressions are obtained for plasma and diffraction grating parameters which define resonance conditions for absolute transparency in the ideal plasma and reflectionless absorption in a plasma with dissipation.

  10. Atomic Absorption, Atomic Fluorescence, and Flame Emission Spectrometry.

    ERIC Educational Resources Information Center

    Horlick, Gary

    1984-01-01

    This review is presented in six sections. Sections focus on literature related to: (1) developments in instrumentation, measurement techniques, and procedures; (2) performance studies of flames and electrothermal atomizers; (3) applications of atomic absorption spectrometry; (4) analytical comparisons; (5) atomic fluorescence spectrometry; and (6)…

  11. Architecture for Absorption Based Heaters

    SciTech Connect

    Moghaddam, Saeed; Chugh, Devesh

    An absorption based heater is constructed on a fluid barrier heat exchanging plate such that it requires little space in a structure. The absorption based heater has a desorber, heat exchanger, and absorber sequentially placed on the fluid barrier heat exchanging plate. The vapor exchange faces of the desorber and the absorber are covered by a vapor permeable membrane that is permeable to a refrigerant vapor but impermeable to an absorbent. A process fluid flows on the side of the fluid barrier heat exchanging plate opposite the vapor exchange face through the absorber and subsequently through the heat exchanger. Themore » absorption based heater can include a second plate with a condenser situated parallel to the fluid barrier heat exchanging plate and opposing the desorber for condensation of the refrigerant for additional heating of the process fluid.« less

  12. Absorption of Orally Administered Hyaluronan.

    PubMed

    Kimura, Mamoru; Maeshima, Takuya; Kubota, Takumi; Kurihara, Hitoshi; Masuda, Yasunobu; Nomura, Yoshihiro

    2016-12-01

    Hyaluronan (HA) has been utilized as a supplement. However, the absorption of orally administrated HA remains controversial. The degradation and absorption of HA in the intestine were investigated in this study. HA excretion into the feces, degradation in the intestinal tract, absorption through the large intestine, and translocation to the blood and skin were examined. HA administered orally was not detected in rat feces. HA was degraded by cecal content, but not by artificial gastric juice and intestinal juice. Oligosaccharide HA passed through excised large intestine sacs. Furthermore, disaccharides, tetrasaccharides, and polysaccharides HA were distributed to the skin of rats following oral administration of high molecular weight HA (300 kDa). The results of the study suggest that orally administered HA is degraded to oligosaccharides by intestinal bacteria, and oligosaccharide HA is absorbed in the large intestine and is subsequently distributed throughout the tissues, including the skin.

  13. Thermodynamic derivatives of infrared absorptance

    NASA Technical Reports Server (NTRS)

    Broersma, S.; Walls, W. L.

    1974-01-01

    Calculation of the concentration, pressure, and temperature dependence of the spectral absorptance of a vibrational absorption band. A smooth thermodynamic dependence was found for wavelength intervals where the average absorptance is less than 0.65. Individual rotational lines, whose parameters are often well known, were used as bases in the calculation of medium resolution spectra. Two modes of calculation were combined: well-separated rotational lines plus interaction terms, or strongly overlapping lines that were represented by a compound line of similar shape plus corrections. The 1.9- and 6.3-micron bands of H2O and the 4.3-micron band of CO2 were examined in detail and compared with experiment.

  14. 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.

  15. 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. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. 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.

  17. The Kinetics of Mo(Co)6 Substitution Monitored by Fourier Transform Infrared Spectrophotometry.

    ERIC Educational Resources Information Center

    Suslick, Kenneth S.; And Others

    1987-01-01

    Describes a physical chemistry experiment that uses Fourier transform (FTIR) spectrometers and microcomputers as a way of introducing students to the spectral storage and manipulation techniques associated with digitized data. It can be used to illustrate FTIR spectroscopy, simple kinetics, inorganic mechanisms, and Beer's Law. (TW)

  18. 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.

  19. 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.

  20. 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.

  1. An Inexpensive Optical Absorption Experiment

    NASA Astrophysics Data System (ADS)

    Greenslade, Thomas B.

    2006-09-01

    This optical absorption experiment can be put together in only a few minutes with materials found in most secondary or undergraduate stockrooms. The absorption material is the partly transparent flexible anti-static plastic material used to package solid-state devices. The detector is a hand-held photographic exposure meter of the type that was in common use before the advent of point-and-shoot cameras. A graph of the intensity of the transmitted light as a function of the number of sheets of the material is a decreasing exponential. The emphasis of the experiment is on the mathematical form.

  2. Atmospheric Measurements by Cavity Enhanced Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Yi, Hongming; Wu, Tao; Coeur-Tourneur, Cécile; Fertein, Eric; Gao, Xiaoming; Zhao, Weixiong; Zhang, Weijun; Chen, Weidong

    2015-04-01

    Since the last decade, atmospheric environmental monitoring has benefited from the development of novel spectroscopic measurement techniques owing to the significant breakthroughs in photonic technology from the UV to the infrared spectral domain [1]. In this presentation, we will overview our recent development and applications of cavity enhanced absorption spectroscopy techniques for in situ optical monitoring of chemically reactive atmospheric species (such as HONO, NO3, NO2, N2O5) in intensive campaigns [2] and/or in smog chamber studies [3]. These field deployments demonstrated that modern photonic technologies (newly emergent light sources combined with high sensitivity spectroscopic techniques) can provide a useful tool to improve our understanding of tropospheric chemical processes which affect climate, air quality, and the spread of pollution. Experimental detail and preliminary results will be presented. Acknowledgements. The financial support from the French Agence Nationale de la Recherche (ANR) under the NexCILAS (ANR-11-NS09-0002) and the CaPPA (ANR-10-LABX-005) contracts is acknowledged. References [1] X. Cui, C. Lengignon, T. Wu, W. Zhao, G. Wysocki, E. Fertein, C. Coeur, A. Cassez,L. Croisé, W. Chen, et al., "Photonic Sensing of the Atmosphere by absorption spectroscopy", J. Quant. Spectrosc. Rad. Transfer 113 (2012) 1300-1316 [2] T. Wu, Q. Zha, W. Chen, Z. XU, T. Wang, X. He, "Development and deployment of a cavity enhanced UV-LED spectrometer for measurements of atmospheric HONO and NO2 in Hong Kong", Atmos. Environ. 95 (2014) 544-551 [3] T. Wu, C. Coeur-Tourneur, G. Dhont,A. Cassez, E. Fertein, X. He, W. Chen,"Application of IBBCEAS to kinetic study of NO3 radical formation from O3 + NO2 reaction in an atmospheric simulation chamber", J. Quant. Spectrosc. Rad. Transfer 133 (2014)199-205

  3. Light absorption of organic carbon emitted from burning wood, charcoal, and kerosene in household cookstoves.

    PubMed

    Xie, Mingjie; Shen, Guofeng; Holder, Amara L; Hays, Michael D; Jetter, James J

    2018-05-02

    Household cookstove emissions are an important source of carbonaceous aerosols globally. The light-absorbing organic carbon (OC), also termed brown carbon (BrC), from cookstove emissions can impact the Earth's radiative balance, but is rarely investigated. In this work, PM 2.5 filter samples were collected during combustion experiments with red oak wood, charcoal, and kerosene in a variety of cookstoves mainly at two water boiling test phases (cold start CS, hot start HS). Samples were extracted in methanol and extracts were examined using spectrophotometry. The mass absorption coefficients (MAC λ , m 2 g -1 ) at five wavelengths (365, 400, 450, 500, and 550 nm) were mostly inter-correlated and were used as a measurement proxy for BrC. The MAC 365 for red oak combustion during the CS phase correlated strongly to the elemental carbon (EC)/OC mass ratio, indicating a dependency of BrC absorption on burn conditions. The emissions from cookstoves burning red oak have an average MAC λ 2-6 times greater than those burning charcoal and kerosene, and around 3-4 times greater than that from biomass burning measured in previous studies. These results suggest that residential cookstove emissions could contribute largely to ambient BrC, and the simulation of BrC radiative forcing in climate models for biofuel combustion in cookstoves should be treated specifically and separated from open biomass burning. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Aprotic solvents effect on the UV-visible absorption spectra of bixin.

    PubMed

    Rahmalia, Winda; Fabre, Jean-François; Usman, Thamrin; Mouloungui, Zéphirin

    2014-10-15

    We describe here the effects of aprotic solvents on the spectroscopic characteristics of bixin. Bixin was dissolved in dimethyl sulfoxide, acetone, dichloromethane, ethyl acetate, chloroform, dimethyl carbonate, cyclohexane and hexane, separately, and its spectra in the resulting solutions were determined by UV-visible spectrophotometry at normal pressure and room temperature. We analyzed the effect of aprotic solvents on λmax according to Onsager cavity model and Hansen theory, and determined the approximate absorption coefficient with the Beer-Lambert law. We found that the UV-visible absorption spectra of bixin were found to be solvent dependent. The S0→S2 transition energy of bixin in solution was dependent principally on the refractive index of the solvents and the bixin-solvent dispersion interaction. There was a small influence of the solvents dielectric constant, permanent dipole interaction and hydrogen bonding occurred between bixin and solvents. The absorbance of bixin in various solvents, with the exception of hexane, increased linearly with concentration. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Aprotic solvents effect on the UV-visible absorption spectra of bixin

    NASA Astrophysics Data System (ADS)

    Rahmalia, Winda; Fabre, Jean-François; Usman, Thamrin; Mouloungui, Zéphirin

    2014-10-01

    We describe here the effects of aprotic solvents on the spectroscopic characteristics of bixin. Bixin was dissolved in dimethyl sulfoxide, acetone, dichloromethane, ethyl acetate, chloroform, dimethyl carbonate, cyclohexane and hexane, separately, and its spectra in the resulting solutions were determined by UV-visible spectrophotometry at normal pressure and room temperature. We analyzed the effect of aprotic solvents on λmax according to Onsager cavity model and Hansen theory, and determined the approximate absorption coefficient with the Beer-Lambert law. We found that the UV-visible absorption spectra of bixin were found to be solvent dependent. The S0 → S2 transition energy of bixin in solution was dependent principally on the refractive index of the solvents and the bixin-solvent dispersion interaction. There was a small influence of the solvents dielectric constant, permanent dipole interaction and hydrogen bonding occurred between bixin and solvents. The absorbance of bixin in various solvents, with the exception of hexane, increased linearly with concentration.

  6. Molecular hydrogen absorption systems in Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Balashev, S. A.; Klimenko, V. V.; Ivanchik, A. V.; Varshalovich, D. A.; Petitjean, P.; Noterdaeme, P.

    2014-05-01

    We present a systematic search for molecular hydrogen absorption systems at high redshift in quasar spectra from the Sloan Digital Sky Survey (SDSS)-II Data Release 7 and SDSS-III Data Release 9. We have selected candidates using a modified profile fitting technique taking into account that the Lyα forest can effectively mimic H2 absorption systems at the resolution of SDSS data. To estimate the confidence level of the detections, we use two methods: a Monte Carlo sampling and an analysis of control samples. The analysis of control samples allows us to define regions of the spectral quality parameter space where H2 absorption systems can be confidently identified. We find that H2 absorption systems with column densities log NH2 > 19 can be detected in only less than 3 per cent of SDSS quasar spectra. We estimate the upper limit on the detection rate of saturated H2 absorption systems (NH2 > 19) in damped Lyα (DLA) systems to be about 7 per cent. We provide a sample of 23 confident H2 absorption system candidates that would be interesting to follow up with high-resolution spectrographs. There is a 1σ r - i colour excess and non-significant AV extinction excess in quasar spectra with an H2 candidate compared to standard DLA-bearing quasar spectra. The equivalent widths of C II, Si II and Al III (but not Fe II) absorptions associated with H2 candidate DLAs are larger compared to standard DLAs. This is probably related to a larger spread in velocity of the absorption lines in the H2-bearing sample.

  7. Absorption of Bile Pigments by the Gall Bladder*

    PubMed Central

    Ostrow, J. Donald

    1967-01-01

    A technique is described for preparation in the guinea pig of an in situ, isolated, vascularized gall bladder that exhibits normal absorptive functions. Absorption of labeled bile pigments from the gall bladder was determined by the subsequent excretion of radioactivity in hepatic bile. Over a wide range of concentrations, unconjugated bilirubin-14C was well absorbed, whereas transfer of conjugated bilirubin proceeded slowly. Mesobilirubinogen-3H was absorbed poorly from whole bile, but was absorbed as rapidly as unconjugated bilirubin from a solution of pure conjugated bile salt. Bilirubin absorption was not impaired by iodoacetamide, 1.5 mM, or dinitrophenol, 1.0 mM, even though water transport was affected. This indicated that absorption of bilirubin was not dependent upon water transport, nor upon energy-dependent processes. The linear relationship between absorption and concentration of pigment at low concentrations in bile salt solutions suggested that pigment was transferred by passive diffusion. At higher pigment concentrations or in whole bile, this simple relationship was modified by interactions of pigment with bile salts and other constituents of bile. These interactions did not necessarily involve binding of bilirubin in micelles. The slow absorption of the more polar conjugates and photo-oxidative derivatives of bilirubin suggested that bilirubin was absorbed principally by nonionic, and partially, by ionic diffusion. Concentrations of pure conjugated bile salts above 3.5 mM were found to be injurious to the gall bladder mucosa. This mucosal injury did not affect the kinetics of bilirubin absorption. During in vitro incubation of bile at 37°C, decay of bilirubin and hydrolysis of the conjugate proceeded as first-order reactions. The effects of these processes on the kinetics of bilirubin absorption, and their possible role in the formation of “white bile” and in the demonstrated appearance of unconjugated bilirubin in hepatic bile, are discussed

  8. 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.

  9. Metal powder absorptivity: Modeling and experiment

    SciTech Connect

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

    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.

  10. 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.

  11. Deep tissue near infrared second derivative spectrophotometry for the assessment of claudication in peripheral arterial disease.

    PubMed

    Koutsiaris, Aristotle G

    2017-01-01

    The purpose of this study was the application of a second derivative near infrared spectrophotometric (NIRS) technique to the human calf muscle in order to see if peripheral arterial disease (PAD) patients can be discriminated from control subjects, before, during and after a standard treadmill exercise test. Three groups of human subjects were studied: group A consisted of 10 control subjects and groups B and C were formed by PAD patients classified as Fontaine's stage 2a (5 patients) and 2b (10 patients), respectively. The measurement protocol for all groups was 9.75 minutes of standing up (phase 1), 1 minute of exercise (phase 2) and 1 minute of rest (phase 3). Seven variables were defined at different times from the onset of the measurement protocol. All variables were significantly higher (p < 0.05) in group A in comparison to groups B and C. The level of significance was ten times higher (p < 0.005) at the onset (15 seconds) of the experiment and during phases 2 and 3. However, none of the variables in group B was significantly different from those in group C. It is shown for the first time that a second derivative NIRS technique can discriminate (p = 0.003) healthy subjects from PAD patients, in just 15 seconds of standing, with no exercise requirement. More experiments are required in order to uncover the full potential of the technique in the diagnosis of the PAD.

  12. Nonlinear absorption enhancement of AuNPs based polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Zulina, Natalia A.; Baranov, Mikhail A.; Kniazev, Kirill I.; Kaliabin, Viacheslav O.; Denisyuk, Igor Yu.; Achor, Susan U.; Sitnikova, Vera E.

    2018-07-01

    Au nanoparticles (AuNPs) based polymer nanocomposites with high nonlinear absorption coefficient were synthesized by UV-photocuring. AuNPs were synthesized by laser ablation method in liquid monomer isodecyl acrylate (IDA). In this research, two colloids with 70 nm and 20 nm nanoparticles average sizes were studied. Size control was performed with SEM and STEM. Prepared nanomaterials exhibit strong third-order nonlinear optical responses under CW laser irradiation at 532 nm, which was estimated by using z-scan technique performed with open aperture. It was found experimentally that nonlinear absorption β is almost twice higher for nanocomposites with smaller AuNPs.

  13. Reverse saturable absorption (RSA) in fluorinated iridium derivatives

    NASA Astrophysics Data System (ADS)

    Ferry, Michael J.; O'Donnell, Ryan M.; Bambha, Neal; Ensley, Trenton R.; Shensky, William M.; Shi, Jianmin

    2017-08-01

    The photophysical properties of cyclometallated iridium compounds are beneficial for nonlinear optical (NLO) applications, such as the design of reverse saturable absorption (RSA) materials. We report on the NLO characterization of a family of compounds of the form [Ir(pbt)2(LX)], where pbt is 2-phenylbenzothiazole and LX is a beta-diketonate ligand. In particular, we investigate the effects of trifluoromethylation on compound solubility and photophysics compared to the parent acetylacetonate (acac) version. The NLO properties, such as the singlet and triplet excited-state cross sections, of these compounds were measured using the Z-scan technique. The excited-state lifetimes were determined from visible transient absorption spectroscopy.

  14. Picosecond absorption relaxation measured with nanosecond laser photoacoustics

    PubMed Central

    Danielli, Amos; Favazza, Christopher P.; Maslov, Konstantin; Wang, Lihong V.

    2010-01-01

    Picosecond absorption relaxation—central to many disciplines—is typically measured by ultrafast (femtosecond or picosecond) pump-probe techniques, which however are restricted to optically thin and weakly scattering materials or require artificial sample preparation. Here, we developed a reflection-mode relaxation photoacoustic microscope based on a nanosecond laser and measured picosecond absorption relaxation times. The relaxation times of oxygenated and deoxygenated hemoglobin molecules, both possessing extremely low fluorescence quantum yields, were measured at 576 nm. The added advantages in dispersion susceptibility, laser-wavelength availability, reflection sensing, and expense foster the study of natural—including strongly scattering and nonfluorescent—materials. PMID:21079726

  15. Picosecond absorption relaxation measured with nanosecond laser photoacoustics.

    PubMed

    Danielli, Amos; Favazza, Christopher P; Maslov, Konstantin; Wang, Lihong V

    2010-10-18

    Picosecond absorption relaxation-central to many disciplines-is typically measured by ultrafast (femtosecond or picosecond) pump-probe techniques, which however are restricted to optically thin and weakly scattering materials or require artificial sample preparation. Here, we developed a reflection-mode relaxation photoacoustic microscope based on a nanosecond laser and measured picosecond absorption relaxation times. The relaxation times of oxygenated and deoxygenated hemoglobin molecules, both possessing extremely low fluorescence quantum yields, were measured at 576 nm. The added advantages in dispersion susceptibility, laser-wavelength availability, reflection sensing, and expense foster the study of natural-including strongly scattering and nonfluorescent-materials.

  16. Aerosol Absorption and Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Stier, Philip; Seinfeld, J. H.; Kinne, Stefan; Boucher, Olivier

    2007-01-01

    We present a comprehensive examination of aerosol absorption with a focus on evaluating the sensitivity of the global distribution of aerosol absorption to key uncertainties in the process representation. For this purpose we extended the comprehensive aerosol-climate model ECHAM5-HAM by effective medium approximations for the calculation of aerosol effective refractive indices, updated black carbon refractive indices, new cloud radiative properties considering the effect of aerosol inclusions, as well as by modules for the calculation of long-wave aerosol radiative properties and instantaneous aerosol forcing. The evaluation of the simulated aerosol absorption optical depth with the AERONET sun-photometer network shows a good agreement in the large scale global patterns. On a regional basis it becomes evident that the update of the BC refractive indices to Bond and Bergstrom (2006) significantly improves the previous underestimation of the aerosol absorption optical depth. In the global annual-mean, absorption acts to reduce the shortwave anthropogenic aerosol top-of-atmosphere (TOA) radiative forcing clear-sky from -0.79 to -0.53 W m(sup -2) (33%) and all-sky from -0.47 to -0.13W m(sup -2 (72%). Our results confirm that basic assumptions about the BC refractive index play a key role for aerosol absorption and radiative forcing. The effect of the usage of more accurate effective medium approximations is comparably small. We demonstrate that the diversity in the AeroCom land-surface albedo fields contributes to the uncertainty in the simulated anthropogenic aerosol radiative forcings: the usage of an upper versus lower bound of the AeroCom land albedos introduces a global annual-mean TOA forcing range of 0.19W m(sup -2) (36%) clear-sky and of 0.12W m(sup -2) (92%) all-sky. The consideration of black carbon inclusions on cloud radiative properties results in a small global annual-mean all-sky absorption of 0.05W m(sup -2) and a positive TOA forcing perturbation of 0

  17. Nonlinear Terahertz Absorption of Graphene Plasmons.

    PubMed

    Jadidi, Mohammad M; König-Otto, Jacob C; Winnerl, Stephan; Sushkov, Andrei B; Drew, H Dennis; Murphy, Thomas E; Mittendorff, Martin

    2016-04-13

    Subwavelength graphene structures support localized plasmonic resonances in the terahertz and mid-infrared spectral regimes. The strong field confinement at the resonant frequency is predicted to significantly enhance the light-graphene interaction, which could enable nonlinear optics at low intensity in atomically thin, subwavelength devices. To date, the nonlinear response of graphene plasmons and their energy loss dynamics have not been experimentally studied. We measure and theoretically model the terahertz nonlinear response and energy relaxation dynamics of plasmons in graphene nanoribbons. We employ a terahertz pump-terahertz probe technique at the plasmon frequency and observe a strong saturation of plasmon absorption followed by a 10 ps relaxation time. The observed nonlinearity is enhanced by 2 orders of magnitude compared to unpatterned graphene with no plasmon resonance. We further present a thermal model for the nonlinear plasmonic absorption that supports the experimental results. The model shows that the observed strong linearity is caused by an unexpected red shift of plasmon resonance together with a broadening and weakening of the resonance caused by the transient increase in electron temperature. The model further predicts that even greater resonant enhancement of the nonlinear response can be expected in high-mobility graphene, suggesting that nonlinear graphene plasmonic devices could be promising candidates for nonlinear optical processing.

  18. Atmospheric pressure and temperature profiling using near IR differential absorption lidar

    NASA Technical Reports Server (NTRS)

    Korb, C. L.; Schwemmer, G. K.; Dombrowski, M.; Weng, C. Y.

    1983-01-01

    The present investigation is concerned with differential absorption lidar techniques for remotely measuring the atmospheric temperature and pressure profile, surface pressure, and cloud top pressure-height. The procedure used in determining the pressure is based on the conduction of high-resolution measurements of absorption in the wings of lines in the oxygen A band. Absorption with respect to these areas is highly pressure sensitive in connection with the mechanism of collisional line broadening. The method of temperature measurement utilizes a determination of the absorption at the center of a selected line in the oxygen A band which originates from a quantum state with high ground state energy.

  19. Spectra resolution for simultaneous spectrophotometric determination of lamivudine and zidovudine components in pharmaceutical formulation of human immunodeficiency virus drug based on using continuous wavelet transform and derivative transform techniques.

    PubMed

    Sohrabi, Mahmoud Reza; Tayefeh Zarkesh, Mahshid

    2014-05-01

    In the present paper, two spectrophotometric methods based on signal processing are proposed for the simultaneous determination of two components of an anti-HIV drug called lamivudine (LMV) and zidovudine (ZDV). The proposed methods are applied to synthetic binary mixtures and commercial pharmaceutical tablets without the need for any chemical separation procedures. The developed methods are based on the application of Continuous Wavelet Transform (CWT) and Derivative Spectrophotometry (DS) combined with the zero cross point technique. The Daubechies (db5) wavelet family (242 nm) and Dmey wavelet family (236 nm) were found to give the best results under optimum conditions for simultaneous analysis of lamivudine and zidovudine, respectively. In addition, the first derivative absorption spectra were selected for the determination of lamivudine and zidovudine at 266 nm and 248 nm, respectively. Assaying various synthetic mixtures of the components validated the presented methods. Mean recovery values were found to be between 100.31% and 100.2% for CWT and 99.42% and 97.37% for DS, respectively for determination of LMV and ZDV. The results obtained from analyzing the real samples by the proposed methods were compared to the HPLC reference method. One-way ANOVA test at 95% confidence level was applied to the results. The statistical data from comparing the proposed methods with the reference method showed no significant differences. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. DETERMINATION OF TOTAL MERCURY IN FISH TISSUES USING PYROLYSIS ATOMIC ABSORPTION SPECTROMETRY WITH GOLD AMALGAMATION

    EPA Science Inventory

    A simple and rapid procedure for measuring total mercury in fish tissues is evaluated and
    compared with conventional techniques. Using an automated instrument incorporating combustion, preconcentration by amalgamation with gold, and atomic absorption spectrometry (AAS), mill...

  1. Two-photon absorption in diazobenzene compounds

    NASA Astrophysics Data System (ADS)

    Andrade, A. A.; Yamaki, S. B.; Misoguti, L.; Zilio, S. C.; Atvars, Teresa D. Z.; Oliveira, O. N.; Mendonça, C. R.

    2004-12-01

    An investigation is made into molecular design strategies to enhance the two-photon absorption (2PA) of organic materials by measuring the 2PA cross-section of diazoaromatic compounds with the femtosecond pulses Z-scan technique at 775 nm. These diazo dyes exhibit a moderate 2PA cross-section, of the order of 300 GM, comparable to those of regular azoaromatic compounds. The increase in the π-electron bridge in the diazoaromatic compounds does not bring, therefore, substantial increase to the measured 2PA intensities, while the main factor to enhance the 2PA cross-section is the presence of charge donor and acceptor groups. It is concluded that current molecular design strategies are unlikely to produce azoaromatic compounds that are useful for applications requiring very high 2PA coefficients.

  2. Calcium Absorption from Fortified Ice Cream Formulations Compared with Calcium Absorption from Milk

    PubMed Central

    van der Hee, Regine M.; Miret, Silvia; Slettenaar, Marieke; Duchateau, Guus S.M.J.E.; Rietveld, Anton G.; Wilkinson, Joy E.; Quail, Patricia J.; Berry, Mark J.; Dainty, Jack R.; Teucher, Birgit; Fairweather-Tait, Susan J.

    2009-01-01

    Objective Optimal bone mass in early adulthood is achieved through appropriate diet and lifestyle, thereby protecting against osteoporosis and risk of bone fracture in later life. Calcium and vitamin D are essential to build adequate bones, but calcium intakes of many population groups do not meet dietary reference values. In addition, changes in dietary patterns are exacerbating the problem, thereby emphasizing the important role of calcium-rich food products. We have designed a calcium-fortified ice cream formulation that is lower in fat than regular ice cream and could provide a useful source of additional dietary calcium. Calcium absorption from two different ice cream formulations was determined in young adults and compared with milk. Subjects/setting Sixteen healthy volunteers (25 to 45 years of age), recruited from the general public of The Netherlands, participated in a randomized, reference-controlled, double-blind cross-over study in which two test products and milk were consumed with a light standard breakfast on three separate occasions: a standard portion of ice cream (60 g) fortified with milk minerals and containing a low level (3%) of butter fat, ice cream (60 g) fortified with milk minerals and containing a typical level (9%) of coconut oil, and reduced-fat milk (1.7% milk fat) (200 mL). Calcium absorption was measured by the dual-label stable isotope technique. Statistical analysis Effects on calcium absorption were evaluated by analysis of variance. Results Fractional absorption of calcium from the 3% butterfat ice cream, 9% coconut oil ice cream, and milk was 26%±8%, 28%±5%, and 31%±9%, respectively, and did not differ significantly (P=0.159). Conclusions Results indicate that calcium bioavailability in the two calcium-fortified ice cream formulations used in this study is as high as milk, indicating that ice cream may be a good vehicle for delivery of calcium. PMID:19394469

  3. Calcium absorption from fortified ice cream formulations compared with calcium absorption from milk.

    PubMed

    van der Hee, Regine M; Miret, Silvia; Slettenaar, Marieke; Duchateau, Guus S M J E; Rietveld, Anton G; Wilkinson, Joy E; Quail, Patricia J; Berry, Mark J; Dainty, Jack R; Teucher, Birgit; Fairweather-Tait, Susan J

    2009-05-01

    Optimal bone mass in early adulthood is achieved through appropriate diet and lifestyle, thereby protecting against osteoporosis and risk of bone fracture in later life. Calcium and vitamin D are essential to build adequate bones, but calcium intakes of many population groups do not meet dietary reference values. In addition, changes in dietary patterns are exacerbating the problem, thereby emphasizing the important role of calcium-rich food products. We have designed a calcium-fortified ice cream formulation that is lower in fat than regular ice cream and could provide a useful source of additional dietary calcium. Calcium absorption from two different ice cream formulations was determined in young adults and compared with milk. Sixteen healthy volunteers (25 to 45 years of age), recruited from the general public of The Netherlands, participated in a randomized, reference-controlled, double-blind cross-over study in which two test products and milk were consumed with a light standard breakfast on three separate occasions: a standard portion of ice cream (60 g) fortified with milk minerals and containing a low level (3%) of butter fat, ice cream (60 g) fortified with milk minerals and containing a typical level (9%) of coconut oil, and reduced-fat milk (1.7% milk fat) (200 mL). Calcium absorption was measured by the dual-label stable isotope technique. Effects on calcium absorption were evaluated by analysis of variance. Fractional absorption of calcium from the 3% butterfat ice cream, 9% coconut oil ice cream, and milk was 26%+/-8%, 28%+/-5%, and 31%+/-9%, respectively, and did not differ significantly (P=0.159). Results indicate that calcium bioavailability in the two calcium-fortified ice cream formulations used in this study is as high as milk, indicating that ice cream may be a good vehicle for delivery of calcium.

  4. Spectrophotometry of Peculiar B-Stars and A-Stars - Part Nine - HD5797 HD12288 9-TAURI HD81009 HD111133 33-LIBRAE and HD216533

    NASA Astrophysics Data System (ADS)

    Adelman, S. J.

    1981-02-01

    Optical region spectrophotometry of λλ3300-7100 is presented for seven sharp-lined peculiar A stars: HD 5797, HD 12288, 9 Tauri, HD 81009, HD 111133, 33 Librae, and HD 216533. Many of proposed periods in the literature are questioned. Some of the deviations from the predictions of normal stellar atmospheres suggest that such continua are only remotely related to those of peculiar A stars.

  5. 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…

  6. Birefringence and anisotropic optical absorption in porous silicon

    SciTech Connect

    Efimova, A. I., E-mail: efimova@vega.phys.msu.ru; Krutkova, E. Yu.; Golovan', L. A.

    2007-10-15

    The refractive indices and the coefficients of optical absorption by free charge carriers and local vibrations in porous silicon (por-Si) films, comprising nanometer-sized silicon residues (nanocrystals) separated by nanometer-sized pores (nanopores) formed in the course of electrochemical etching of the initial single crystal silicon, have been studied by polarization-resolved IR absorption spectroscopy techniques. It is shown that the birefringence observed in por-Si is related to the anisotropic shapes of nanocrystals and nanopores, while the anisotropy (dichroism) of absorption by the local vibrational modes is determined predominantly by the microrelief of the surface of nanocrystals. It is demonstrated that silicon-hydrogen surfacemore » bonds in nanocrystals can be restored by means of selective hydrogen thermodesorption with the formation of a considerable number of H-terminated surface Si-Si dimers.« less

  7. Paracetamol absorption from different sites in the human small intestine.

    PubMed Central

    Gramatté, T; Richter, K

    1994-01-01

    Site-specificity in the small intestinal absorption of paracetamol was investigated using a segmental intestinal steady state perfusion technique (triple-lumen tubing system) combined with simultaneous measurements of serum drug concentrations. Dissolved paracetamol was perfused over 160 min into different parts of the small intestine (65-210 cm beyond the teeth). Each of the four healthy subjects was studied twice with a proximal and a more distal site of perfusion. Serum drug concentrations were similar after proximal and distal perfusions. Mean drug absorption rates calculated from intestinal aspirate concentrations were similar in both parts of the intestine--proximal: 869 micrograms 30 cm-1 min-1 (95% CI: 659-1079) vs distal: 941 micrograms 30 cm-1 min-1 (794-1088). The absorption rate was related directly to the amount of paracetamol perfused per unit time as well as to the rate of transmucosal water fluxes. PMID:7917782

  8. Nonlinear absorption of short intense laser pulse in multispecies plasma

    SciTech Connect

    Kargarian, A.; Hajisharifi, K.; Mehdian, H.

    In the present paper, the detailed investigation concerning the effect of inclusion of heavy negative ions into the finite background plasma on the laser absorption has been carried out by employing particle-in-cell simulation method. For this purpose, in this configuration, the laser energy absorption relying on the nonlinear phenomena such as phase-mixing, wave-breaking, and scattering has been studied in the Raman-Brillouin regime. It is shown that the inclusion of heavy negative ions suppresses the scattering while increases the phase-mixing time. Moreover, it is illustrated that this inclusion can increase the laser absorption in finite plasma environment, after saturation. The obtainedmore » results are expected to be relevant to the experiments on the mass spectrometry with laser desorption techniques as well as on the laser-plasma interaction with application to particles acceleration.« less

  9. UV absorption spectrum of allene radical cations in solid argon

    NASA Astrophysics Data System (ADS)

    Chin, Chih-Hao; Lin, Meng-Yeh; Huang, Tzu-Ping; Wu, Yu-Jong

    2018-05-01

    Electron bombardment during deposition of an Ar matrix containing a small proportion of allene generated allene cations. Further irradiation of the matrix sample at 385 nm destroyed the allene cations and formed propyne cations in solid Ar. Both cations were identified according to previously reported IR absorption bands. Using a similar technique, we recorded the ultraviolet absorption spectrum of allene cations in solid Ar. The vibrationally resolved progression recorded in the range of 266-237 nm with intervals of about 800 cm-1 was assigned to the A2E ← X2E transition of allene cations, and the broad continuum absorption recorded in the region of 229-214 nm was assigned to their B2A1 ← X2E transition. These assignments were made based on the observed photolytic behavior of the progressions and the vertical excitation energies and oscillator strengths calculated using time-dependent density functional theory.

  10. Optical nonlinear absorption characteristics of Sb2Se3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Muralikrishna, Molli; Kiran, Aditha Sai; Ravikanth, B.; Sowmendran, P.; Muthukumar, V. Sai; Venkataramaniah, Kamisetti

    2014-04-01

    In this work, we report for the first time, the nonlinear optical absorption properties of antimony selenide (Sb2Se3) nanoparticles synthesized through solvothermal route. X-ray diffraction results revealed the crystalline nature of the nanoparticles. Electron microscopy studies revealed that the nanoparticles are in the range of 10 - 40 nm. Elemental analysis was performed using EDAX. By employing open aperture z-scan technique, we have evaluated the effective two-photon absorption coefficient of Sb2Se3 nanoparticles to be 5e-10 m/W at 532 nm. These nanoparticles exhibit strong intensity dependent nonlinear optical absorption and hence could be considered to have optical power limiting applications in the visible range.

  11. 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. © 2014 The Authors.

  12. Determination of carcinogenic herbicides in milk samples using green non-ionic silicone surfactant of cloud point extraction and spectrophotometry.

    PubMed

    Mohd, N I; Zain, N N M; Raoov, M; Mohamad, S

    2018-04-01

    A new cloud point methodology was successfully used for the extraction of carcinogenic pesticides in milk samples as a prior step to their determination by spectrophotometry. In this work, non-ionic silicone surfactant, also known as 3-(3-hydroxypropyl-heptatrimethylxyloxane), was chosen as a green extraction solvent because of its structure and properties. The effect of different parameters, such as the type of surfactant, concentration and volume of surfactant, pH, salt, temperature, incubation time and water content on the cloud point extraction of carcinogenic pesticides such as atrazine and propazine, was studied in detail and a set of optimum conditions was established. A good correlation coefficient ( R 2 ) in the range of 0.991-0.997 for all calibration curves was obtained. The limit of detection was 1.06 µg l -1 (atrazine) and 1.22 µg l -1 (propazine), and the limit of quantitation was 3.54 µg l -1 (atrazine) and 4.07 µg l -1 (propazine). Satisfactory recoveries in the range of 81-108% were determined in milk samples at 5 and 1000 µg l -1 , respectively, with low relative standard deviation, n  = 3 of 0.301-7.45% in milk matrices. The proposed method is very convenient, rapid, cost-effective and environmentally friendly for food analysis.

  13. 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.

  14. Can tissue spectrophotometry and laser Doppler flowmetry help to identify patients at risk for wound healing disorders after neck dissection?

    PubMed

    Rohleder, Nils H; Flensberg, Sandra; Bauer, Florian; Wagenpfeil, Stefan; Wales, Craig J; Koerdt, Steffen; Wolff, Klaus D; Hölzle, Frank; Steiner, Timm; Kesting, Marco R

    2014-03-01

    Microcirculation and oxygen supply in cervical skin were measured with an optical, noninvasive method in patients with or without radiotherapy before neck dissection. The course of wound healing was monitored after the surgical procedure to identify predictive factors for postoperative wound healing disorders. Tissue spectrophotometry and laser Doppler flowmetry were used to determine capillary oxygen saturation, hemoglobin concentration, blood flow, and blood velocity at 2-mm and 8-mm depths in the cervical skin of 91 patients before neck dissection in a maxillofacial unit of a university hospital in Munich, Germany. Parameters were evaluated for differences between patients with irradiation (24) and without (67) and patients with wound healing disorders (25) and without (66) (univariate or multivariate statistical analyses). Velocity at 2 mm was lower in irradiated skin (P = .016). Flow at 2 mm was higher in patients with wound healing disorders (P = .018). High flow values could help to identify patients at risk for cervical wound healing disorders. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. An optical investigation of dentinal discoloration due to commonly endodontic sealers, using the transmitted light polarizing microscopy and spectrophotometry.

    PubMed

    Suciu, Ioana; Ionescu, Ecaterina; Dimitriu, Bogdan Alexandru; Bartok, Ruxandra Ioana; Moldoveanu, Georgiana Florentina; Gheorghiu, Irina Maria; Suciu, Ileana; Ciocîrdel, Mihai

    2016-01-01

    The aim of this study was to establish the degree of tooth crown staining by commonly used endodontic sealers. Crown discolorations by tooth canal sealers [AH Plus (Dentsply DeTrey Gmbh, Konstanz, Germany); Endofill (Produits Dentaires SA, Vevey, Switzerland); Apexit (Dentsply DeTrey Gmbh, Konstanz, Germany); and MTA Fillapex (Angelus, Londrina, Brazil)] were tested on extracted human premolars. The samples were divided into five groups of five samples each, after root canal sealing. Five teeth were used as control groups. The spectrophotometric method was performed in order to quantify in terms of color change of the coronal part (it was also recorded a track on how the color changes over time). For the microscopic study of the extracted dental specimens subjected to this study, polarized transmitted light microscopy was used. This method involves the development of special microscopic preparations, called "thin sections". In our case, the thin section was performed on 20 prepared and obturated recently extracted teeth. The degree of discoloration was determined after one week and three months using spectrophotometry and polarized light microscopy. All sealers usually cause some degree of discoloration on the cervical aspect of the crowns that increases in time. AH Plus and Endofill caused the greatest discoloration, followed by Apexit and MTA Fillapex.

  16. 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.

  17. Retinopathy of prematurity and induced changes in arterial oxygen saturation with near infrared spectrophotometry: a retrospective cohort study

    NASA Astrophysics Data System (ADS)

    von Siebenthal, K.; Keel, M.; Dietz, V.; Fauchere, J. C.; Martin, X.; Wolf, Martin; Duc, G.; Bucher, H. U.

    1996-10-01

    Near-infrared spectrophotometry (NIRS) is a noninvasive method for measuring oxygenated and deoxygenated hemoglobin in the neonatal brain. Using oxygen as a tracer, it is possible to calculate cerebral blood flow (cbf) and hemoglobin concentration (cHbc), which corresponds to cerebral blood volume, by inducing small changes in arterial oxygen saturation. Variability of tcpO2 is considered to be associated with severe retinopathy of prematurity (ROP). A preliminary analysis without control found a 51 percent incidence of ROP in infants subjected to NIRS measurements whereas among infants who were not exposed to oxygen changes, only 29 percent developed ROP. A controlled study with matched pairs was performed. Thirty-nine premature newborns who had received NIRS recordings were matched with 39 out of 172 infants who had not received NIRS. Using this controlled study design there was no difference in the incidence and severity of ROP between the two groups. The conclusions are that: 1) small changes in oxygen saturation of 3 to 10 percent to measure cbf and cHbc did not increase the incidence or the degree of severity of ROP. 2) A controlled study design is important. Analyses of uncontrolled data would have led to the conclusion that oxygen changes as used with NIRS increase the risk of ROP.

  18. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    PubMed

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

    2015-12-01

    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 (redfleshed) 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.

  20. Catalysis of CO₂ absorption in aqueous solution by inorganic oxoanions and their application to post combustion capture.

    PubMed

    Phan, Duong T; Maeder, Marcel; Burns, Robert C; Puxty, Graeme

    2014-04-15

    To reduce CO2 emission into the atmosphere, particularly from coal-fired power stations, post combustion capture (PCC) using amine-based solvents to chemically absorb CO2 has been extensively developed. From an infrastructure viewpoint, the faster the absorption of CO2, the smaller the absorber required. The use of catalysts for this process has been broadly studied. In this manuscript, a study of the catalytic efficiencies of inorganic oxoanions such as arsenite, arsenate, phosphite, phosphate, and borate is described. The kinetics of the accelerated CO2 absorption at 25 °C was investigated using stopped-flow spectrophotometry. The catalytic rate constants of these anions for the reaction of CO2 with H2O were determined to be 137.7(3), 30.3(7), 69(2), 32.7(9), and 13.66(7) M(-1)s(-1), respectively. A new mechanism for the catalytic reaction of oxoanions with CO2 has also been proposed. The applicability of these catalysts to PCC was further studied by simulation of the absorption process under PCC conditions using their experimental catalytic rate constants. Arsenite and phosphite were confirmed to be the best catalysts for CO2 capture. However, considering the toxicological effect of arsenic and the oxidative instability of phosphite, phosphate would be the most promising inorganic catalyst for PCC process from the series of inorganic oxoanions studied.

  1. Effect of morphology and solvent on two-photon absorption of nano zinc oxide

    SciTech Connect

    Kavitha, M.K.; Haripadmam, P.C.; Gopinath, Pramod

    Highlights: ► ZnO nanospheres and triangular structures synthesis by novel precipitation technique. ► The effect of precursor concentration on the size and shape of nano ZnO. ► Open aperture Z-scan measurements of the ZnO nanoparticle dispersions. ► Nanospheres exhibit higher two photon absorption coefficient than triangular nanostructures. ► Nanospheres dispersed in water exhibit higher two photon absorption coefficient than its dispersion in 2-propanol. - Abstract: In this paper, we report the effect of morphology and solvent on the two-photon absorption of nano zinc oxide. Zinc oxide nanoparticles in two different morphologies like nanospheres and triangular nanostructures are synthesized by novelmore » precipitation technique and their two-photon absorption coefficient is measured using open aperture Z-scan technique. Experimental results show that the zinc oxide nanospheres exhibit higher two-photon absorption coefficient than the zinc oxide triangular nanostructures. The zinc oxide nanospheres dispersed in water exhibit higher two-photon absorption coefficient than that of its dispersion in 2-propanol. The zinc oxide nanospheres dispersed in water shows a decrease in two-photon absorption coefficient with an increase in on-axis irradiance. The result confirms the dependence of shape and solvent on the two-photon absorption of nano zinc oxide.« less

  2. Ultraviolet absorption experiment MA-059

    NASA Technical Reports Server (NTRS)

    Donahue, T. M.; Hudson, R. D.; Anderson, J.; Kaufman, F.; Mcelroy, M. B.

    1976-01-01

    The ultraviolet absorption experiment performed during the Apollo Soyuz mission involved sending a beam of atomic oxygen and atomic nitrogen resonance radiation, strong unabsorbable oxygen and nitrogen radiation, and visual radiation, all filling the same 3 deg-wide field of view from the Apollo to the Soyuz. The radiation struck a retroreflector array on the Soyuz and was returned to a spectrometer onboard the Apollo. The density of atomic oxygen and atomic nitrogen between the two spacecraft was measured by observing the amount of resonance radiation absorbed when the line joining Apollo and Soyuz was perpendicular to their velocity with respect to the ambient atmosphere. Information concerning oxygen densities was also obtained by observation of resonantly fluorescent light. The absorption experiments for atomic oxygen and atomic nitrogen were successfully performed at a range of 500 meters, and abundant resonance fluorescence data were obtained.

  3. Landing gear energy absorption system

    NASA Technical Reports Server (NTRS)

    Hansen, Christopher P. (Inventor)

    1994-01-01

    A landing pad system is described for absorbing horizontal and vertical impact forces upon engagement with a landing surface where circumferentially arranged landing struts respectively have a clevis which receives a slidable rod member and where the upper portion of a slidable rod member is coupled to the clevis by friction washers which are force fit onto the rod member to provide for controlled constant force energy absorption when the rod member moves relative to the clevis. The lower end of the friction rod is pivotally attached by a ball and socket to a support plate where the support plate is arranged to slide in a transverse direction relative to a housing which contains an energy absorption material for absorbing energy in a transverse direction.

  4. AERONET derived (BC) aerosol absorption

    NASA Astrophysics Data System (ADS)

    Kinne, S.

    2015-12-01

    AERONET is a ground-based sun-/sky-photometer network with good annual statistics at more than 400 sites worldwide. Inversion methods applied to these data define all relevant column aerosol optical properties and reveal even microphysical detail. The extracted data include estimates for aerosol size-distributions and for aerosol refractive indices at four different solar wavelengths. Hereby, the imaginary parts of the refractive indices define the aerosol column absorption. For regional and global averages and radiative impact assessment with off-line radiative transfer, these local data have been extended with distribution patterns offered by AeroCom modeling experiments. Annual and seasonal absorption distributions for total aerosol and estimates for component contributions (such as BC) are presented and associated direct forcing impacts are quantified.

  5. Vitamin B12 absorption capacity in healthy children

    SciTech Connect

    Hjelt, K.; Krasilnikoff, P.A.

    1986-03-01

    B12 absorption was investigated in 47 healthy children aged 7 months to 15.8 years (median 4.9 years). The patients had either recovered from giardiasis, the post-gastroenteritis syndrome, or had celiac disease in remission (treated with a gluten-free diet). The B12 absorption was measured by a double-isotope technique using /sup 57/CoB12 and /sup 51/CrCl/sub 3/, the latter being the inabsorbable marker. The radiation dose was minimal. The results were presented as fractional absorption of B12 (FAB12). Within the different age groups, the absorption test was performed by means of the following oral amounts of B12: 0- less than 1 year, 0.5more » microgram; 1-3 years: 1.7 micrograms, 4-6 years, 2.5 micrograms; 7-10 years; 3.3 micrograms; and 11-15 years, 4.5 micrograms. When using these oral amounts of B12, the medians (and ranges) of FAB12 were found to be: 1-3 years (n = 18), 37% (16-80%); 4-6 years (n = 10), 27% (19-40%); 7-10 years (n = 9), 32% (21-44%); and 11-15 years (n = 8), 27% (19-59%). The FAB12 in two children aged 7 and 11 months was 31% and 32%, respectively. These results may be interpretated as reference values for B12 absorption in children. Further absorption tests were performed in seven children representing the four age groups from 1 to 15 years. When a high oral amount of B12 was given (i.e., three times the saturation dose), the FAB12 ranged from 0 to 20% (median 9%), whereas a low amount (i.e., one-ninth of the saturation dose) produced fractional absorptions from 65 to 82% (median 74%).« less

  6. Noninvasive photoacoustic measurement of absorption coefficient using internal light irradiation of cylindrical diffusing fiber

    NASA Astrophysics Data System (ADS)

    Peng, Dong-qing; Zhu, Li-li; Li, Zhi-fang; Li, Hui

    2017-09-01

    Absorption coefficient of biological tissue is an important parameter in biomedicine, but its determination remains a challenge. In this paper, we propose a method using focusing photoacoustic imaging technique and internal light irradiation of cylindrical diffusing fiber (CDF) to quantify the target optical absorption coefficient. Absorption coefficients for ink absorbers are firstly determined through photoacoustic and spectrophotometric measurements at the same excitation, which demonstrates the feasibility of this method. Also, the optical absorption coefficients of ink absorbers with several concentrations are measured. Finally, the two-dimensional scanning photoacoustic image is obtained. Optical absorption coefficient measurement and simultaneous photoacoustic imaging of absorber non-invasively are the typical characteristics of the method. This method can play a significant role for non-invasive determination of blood oxygen saturation, the absorption-based imaging and therapy.

  7. Photodetector with enhanced light absorption

    DOEpatents

    Kane, James

    1985-01-01

    A photodetector including a light transmissive electrically conducting layer having a textured surface with a semiconductor body thereon. This layer traps incident light thereby enhancing the absorption of light by the semiconductor body. A photodetector comprising a textured light transmissive electrically conducting layer of SnO.sub.2 and a body of hydrogenated amorphous silicon has a conversion efficiency about fifty percent greater than that of comparative cells. The invention also includes a method of fabricating the photodetector of the invention.

  8. Consistency of ARESE II Cloud Absorption Estimates and Sampling Issues

    NASA Technical Reports Server (NTRS)

    Oreopoulos, L.; Marshak, A.; Cahalan, R. F.; Lau, William K. M. (Technical Monitor)

    2002-01-01

    Data from three cloudy days (March 3, 21, 29, 2000) of the ARM Enhanced Shortwave Experiment II (ARESE II) were analyzed. Grand averages of broadband absorptance among three sets of instruments were compared. Fractional solar absorptances were approx. 0.21-0.22 with the exception of March 3 when two sets of instruments gave values smaller by approx. 0.03-0.04. The robustness of these values was investigated by looking into possible sampling problems with the aid of 500 nm spectral fluxes. Grand averages of 500 nm apparent absorptance cover a wide range of values for these three days, namely from a large positive (approx. 0.011) average for March 3, to a small negative (approximately -0.03) for March 21, to near zero (approx. 0.01) for March 29. We present evidence suggesting that a large part of the discrepancies among the three days is due to the different nature of clouds and their non-uniform sampling. Hence, corrections to the grand average broadband absorptance values may be necessary. However, application of the known correction techniques may be precarious due to the sparsity of collocated flux measurements above and below the clouds. Our analysis leads to the conclusion that only March 29 fulfills all requirements for reliable estimates of cloud absorption, that is, the presence of thick, overcast, homogeneous clouds.

  9. Precision atomic beam density characterization by diode laser absorption spectroscopy

    SciTech Connect

    Oxley, Paul; Wihbey, Joseph

    2016-09-15

    We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident lasermore » light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10{sup −5} are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10{sup 4} atoms cm{sup −3}. The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.« less

  10. Precision atomic beam density characterization by diode laser absorption spectroscopy.

    PubMed

    Oxley, Paul; Wihbey, Joseph

    2016-09-01

    We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10 -5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10 4 atoms cm -3 . The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

  11. CALCIUM ABSORPTION IN MAN: BASED ON LARGE VOLUME LIQUID SCINTILLATION COUNTER STUDIES.

    PubMed

    LUTWAK, L; SHAPIRO, J R

    1964-05-29

    A technique has been developed for the in vivo measurement of absorption of calcium in man after oral administration of 1 to 5 microcuries of calcium-47 and continuous counting of the radiation in the subject's arm with a large volume liquid scintillation counter. The maximum value for the arm counting technique is proportional to the absorption of tracer as measured by direct stool analysis. The rate of uptake by the arm is lower in subjects with either the malabsorption syndrome or hypoparathyroidism. The administration of vitamin D increases both the absorption rate and the maximum amount of calcium absorbed.

  12. Wavelength and energy dependent absorption of unconventional fuel mixtures

    NASA Astrophysics Data System (ADS)

    Khan, N.; Saleem, Z.; Mirza, A. A.

    2005-11-01

    Economic considerations of laser induced ignition over the normal electrical ignition of direct injected Compressed Natural Gas (CNG) engines has motivated automobile industry to go for extensive research on basic characteristics of leaner unconventional fuel mixtures to evaluate practical possibility of switching over to the emerging technologies. This paper briefly reviews the ongoing research activities on minimum ignition energy and power requirements of natural gas fuels and reports results of present laser air/CNG mixture absorption coefficient study. This study was arranged to determine the thermo-optical characteristics of high air/fuel ratio mixtures using laser techniques. We measured the absorption coefficient using four lasers of multiple wavelengths over a wide range of temperatures and pressures. The absorption coefficient of mixture was found to vary significantly over change of mixture temperature and probe laser wavelengths. The absorption coefficients of air/CNG mixtures were measured using 20 watts CW/pulsed CO2 laser at 10.6μm, Pulsed Nd:Yag laser at 1.06μm, 532 nm (2nd harmonic) and 4 mW CW HeNe laser at 645 nm and 580 nm for temperatures varying from 290 to 1000K using optical transmission loss technique.

  13. WFC3: Precision Infrared Spectrophotometry with Spatial Scans of HD 189733b and Vega

    NASA Astrophysics Data System (ADS)

    McCullough, Peter R.; Crouzet, N.; Deming, D.; Madhusudhan, N.; Deustua, S. E.; WFC3

    2014-01-01

    The Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) now routinely provides near-infrared spectroscopy of transiting extrasolar planet atmospheres with better than ~50 ppm precision per 0.05-micron resolution bin per transit, for sufficiently bright host stars. Two improvements of WFC3 (the detector) and HST (the spatial scanning technique) have made transiting planet spectra more sensitive and more repeatable than was feasible with NICMOS. In addition, the data analysis is much simpler with WFC3 than with NICMOS. We present time-series spectra of HD 189733b from 1.1 to 1.7 microns in transit and eclipse with fidelity similar to that of the WFC3 transit spectrum of HD 209458b (Deming et al. 2013). In a separate program, we obtained scanned infrared spectra of the bright star, Vega, thereby extending the dynamic range of WFC3 to ~26 magnitudes! Analysis of these data will affect the absolute spectrophotometric calibration of the WFC3, placing it on an SI traceable scale.

  14. Absorption characteristics of forest fire particulate matter

    Treesearch

    E.M. Patterson; Charles K. McMahon

    1984-01-01

    Abstract. Absorption properties of smokes from laboratory fires that represent prescription hums in the Southern states have been quantified to relate variations in measured absorption parameters to variation in fire conditions and to estimate emission factors for elemental carbon. Results showed significant differences in absorption of the smoke...

  15. Investigation of Drug–Polymer Compatibility Using Chemometric-Assisted UV-Spectrophotometry

    PubMed Central

    Mohamed, Amir Ibrahim; Abd-Motagaly, Amr Mohamed Elsayed; Ahmed, Osama A. A.; Amin, Suzan; Mohamed Ali, Alaa Ibrahim

    2017-01-01

    A simple chemometric-assisted UV-spectrophotometric method was used to study the compatibility of clindamycin hydrochloride (HC1) with two commonly used natural controlled-release polymers, alginate (Ag) and chitosan (Ch). Standard mixtures containing 1:1, 1:2, and 1:0.5 w/w drug–polymer ratios were prepared and UV scanned. A calibration model was developed with partial least square (PLS) regression analysis for each polymer separately. Then, test mixtures containing 1:1 w/w drug–polymer ratios with different sets of drug concentrations were prepared. These were UV scanned initially and after three and seven days of storage at 25 °C. Using the calibration model, the drug recovery percent was estimated and a decrease in concentration of 10% or more from initial concentration was considered to indicate instability. PLS models with PC3 (for Ag) and PC2 (for Ch) showed a good correlation between actual and found values with root mean square error of cross validation (RMSECV) of 0.00284 and 0.01228, and calibration coefficient (R2) values of 0.996 and 0.942, respectively. The average drug recovery percent after three and seven days was 98.1 ± 2.9 and 95.4 ± 4.0 (for Ag), and 97.3 ± 2.1 and 91.4 ± 3.8 (for Ch), which suggests more drug compatibility with an Ag than a Ch polymer. Conventional techniques including DSC, XRD, FTIR, and in vitro minimum inhibitory concentration (MIC) for (1:1) drug–polymer mixtures were also performed to confirm clindamycin compatibility with Ag and Ch polymers. PMID:28275214

  16. Hydration shell parameters of aqueous alcohols: THz excess absorption and packing density.

    PubMed

    Matvejev, V; Zizi, M; Stiens, J

    2012-12-06

    Solvation in water requires minimizing the perturbations in its hydrogen bonded network. Hence solutes distort water molecular motions in a surrounding domain, forming a molecule-specific hydration shell. The properties of those hydration shells impact the structure and function of the solubilized molecules, both at the single molecule and at higher order levels. The size of the hydration shell and the picoseconds time-scale water dynamics retardation are revealed by terahertz (THz) absorption coefficient measurements. Room-temperature absorption coefficient at f = 0.28 [THz] is measured as a function of alcohol concentration in aqueous methanol, ethanol, 1,2-propanol, and 1-butanol solutions. Highly diluted alcohol measurements and enhanced overall measurement accuracy are achieved with a THz absorption measurement technique of nL-volume liquids in a capillary tube. In the absorption analysis, bulk and interfacial molecular domains of water and alcohol are considered. THz ideal and excess absorption coefficients are defined in accordance with thermodynamics mixing formulations. The parameter extraction method is developed based on a THz excess absorption model and hydrated solute molecule packing density representation. First, the hydration shell size is deduced from the hydrated solute packing densities at two specific THz excess absorption nonlinearity points: at infinite alcohol dilution (IAD) and at the THz excess absorption extremum (EAE). Consequently, interfacial water and alcohol molecular domain absorptions are deduced from the THz excess absorption model. The hydration shell sizes obtained at the THz excess absorption extremum are in excellent agreement with other reports. The hydration shells of methanol, ethanol, 1- and 2-propanol consist of 13.97, 22.94, 22.99, and 31.10 water molecules, respectively. The hydration shell water absorption is on average 0.774 ± 0.028 times the bulk water absorption. The hydration shell parameters might shed light on

  17. Method and apparatus for enhancing laser absorption sensitivity

    NASA Technical Reports Server (NTRS)

    Webster, Christopher R. (Inventor)

    1987-01-01

    A simple optomechanical method and apparatus is described for substantially reducing the amplitude of unwanted multiple interference fringes which often limit the sensitivities of tunable laser absorption spectrometers. An exterior cavity is defined by partially transmissible surfaces such as a laser exit plate, a detector input, etc. That cavity is spoiled by placing an oscillating plate in the laser beam. For tunable diode laser spectroscopy in the mid-infrared region, a Brewster-plate spoiler allows the harmonic detection of absorptances of less than 10 to the -5 in a single laser scan. Improved operation is achieved without subtraction techniques, without complex laser frequency modulation, and without distortion of the molecular lineshape signal. The technique is applicable to tunable lasers operating from UV to IR wavelengths and in spectrometers which employ either short or long pathlengths, including the use of retroreflectors or multipass cells.

  18. Advanced regenerative absorption refrigeration cycles

    DOEpatents

    Dao, Kim

    1990-01-01

    Multi-effect regenerative absorption cycles which provide a high coefficient of performance (COP) at relatively high input temperatures. An absorber-coupled double-effect regenerative cycle (ADR cycle) (10) is provided having a single-effect absorption cycle (SEA cycle) (11) as a topping subcycle and a single-effect regenerative absorption cycle (1R cycle) (12) as a bottoming subcycle. The SEA cycle (11) includes a boiler (13), a condenser (21), an expansion device (28), an evaporator (31), and an absorber (40), all operatively connected together. The 1R cycle (12) includes a multistage boiler (48), a multi-stage resorber (51), a multisection regenerator (49) and also uses the condenser (21), expansion device (28) and evaporator (31) of the SEA topping subcycle (11), all operatively connected together. External heat is applied to the SEA boiler (13) for operation up to about 500 degrees F., with most of the high pressure vapor going to the condenser (21) and evaporator (31) being generated by the regenerator (49). The substantially adiabatic and isothermal functioning of the SER subcycle (12) provides a high COP. For higher input temperatures of up to 700 degrees F., another SEA cycle (111) is used as a topping subcycle, with the absorber (140) of the topping subcycle being heat coupled to the boiler (13) of an ADR cycle (10). The 1R cycle (12) itself is an improvement in that all resorber stages (50b-f) have a portion of their output pumped to boiling conduits (71a-f) through the regenerator (49), which conduits are connected to and at the same pressure as the highest pressure stage (48a) of the 1R multistage boiler (48).

  19. Acquiring Sediment and Element Compositional Changes Based on a Diffuse Reflectance Spectrophotometry Technology from Cores Offshore Southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Pan, H. J.; Chen, M. T.

    2014-12-01

    Heavy summer monsoon rainfall along with typhoon-induced extreme precipitation cause frequent geological hazards that often threaten the human's safety and property in Taiwan. These geological hazards can be triggered by both natural factors, and/or have become deteriorated by perturbations from more and more human activities ever since few thousand years ago. However, due to the limit of instrumental records for observing long-term environmental changes in Taiwan, few evidence exist for distinguishing the human-induced impacts from natural climate change. Here we report a study on a high quality marine sediment core (MD103264) which were retrieved from the high sedimentation rate area from offshore southwestern Taiwan and present evidence for the long-term climate and possibly human-induced environmental changes since the last glacial. We are using the VIS-NIR Diffuse Reflectance Spectrophotometry (DRS) methods to study the cores. Interpreting the VIS-NIR reflectance spectra through the VARIMAX-rotation, principle component analysis (VPCA) helps conducting rapid and inexpensive measurements for acquiring high-resolution biogenic component, clay, and iron oxide mineral compositional data from the cores. We are also using X-Ray Fluorescence (XRF) analysis, which is also useful in determining the element compositional changes in the core. Our studies aim toward understanding the sediment and element compositional changes that reflect the patterns of changes in precipitation and soil erosion on land since the last glacial to the Holocene, during which the human activities (deforestation, agriculture, and land uses change) may have increased drastically. We will report and interpret the preliminary results of the optical analyses of the core.

  20. Determination of the unsulfonated color concentration from D&C Yellow No. 10 by the derivative spectrophotometry

    NASA Astrophysics Data System (ADS)

    Berdie, A. D.; Jitian, S.

    2018-01-01

    The method that we used is based on the measurement of the first derivative of the mixture of the two colorants at the wavelength for which one of them has the first derivative equal to zero. The Code of Federal Regulations (21 CFR 74.1710) specifies for D&C Yellow No. 10 the maximum permitted levels of an unsulfonated subsidiary color and of diethyl ether-soluble matter other than that specified. In the proposed method a color additive sample is dissolved in water and the unsulfonated subsidiary color are extracted from this solution with dichloromethane. The analysts in dichloromethane solution are determined by spectrophotometry. The unsulfonated subsidiary colors determined are: - D&C Yellow No. 11 [2-(2-Quinolinyl)-1H-indene-1,3(2H)-dione] (Y11), from which D&C Yellow No. 10 is manufactured by sulfonating and - 1,5-Naphthyridinequinophthalone (1,5-NQ). Another compound soluble in water and dichloromethane (which I called S) is present in dichloromethane solution after extraction together with the other two colors and can affect the correct determination of the concentrations. The dichloromethane-soluble matter other than specified is a mixture consisting mostly of chlorinated derivatives of the unsulfonated subsidiary color. Because the S color is present both in aqueous and in dichloromethane solutions, the spectra of calibration solutions should be corrected. The applied correction does not affect the determination of the unsulfonated subsidiary colors concentrations. D&C Yellow No. 11 and 1,5-NQ are used as standard for unsulfonated subsidiary colors.